Slurry composition, method for storing slurry composition, method for producing CMP slurry, and polishing method

Abstract

To provide a slurry composition suppressed in a change in physical properties and capable of being imparted with stable polishing performance even after stored over a long period of time, a method for storing the slurry composition, a method for producing a CMP slurry, and a polishing method.SOLUTION: A slurry composition contains colloidal silica and an acidic compound, and has a pH of less than 7. The colloidal silica has a surface modified by an aminosilane coupling agent, and, when the average secondary particle diameter of the colloidal silica is set to dp [nm], the ratio of the volume of the colloidal silica to the volume of the slurry composition is set to F, and the circle ratio is set to π, the average distance h between particle surfaces of the colloidal silica represented by Equation (1) is less than 65 nm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a slurry composition, a method for storing a slurry composition, a method for producing a CMP slurry, and a polishing method. [Background technology]

[0002] BACKGROUND ART In recent years, with the trend toward multilayer wiring on semiconductor substrate surfaces, a technique known as chemical mechanical polishing (CMP) is used to polish and flatten semiconductor substrates when manufacturing devices. CMP is a method of planarizing the surface of an object to be polished, such as a semiconductor substrate, using a slurry containing abrasive grains such as silica, alumina, or ceria, anticorrosives, surfactants, etc. The object to be polished can be silicon, polysilicon, silicon oxide film (silicon oxide), silicon nitride, or wiring or plugs made of metal, etc.

[0003] If the physical properties of the CMP slurry change between the time of production and the time of use, problems such as poor polishing may occur. Therefore, it is required that the physical properties and polishing performance of the CMP slurry be stable from the time of production until the time of use for polishing. Summary of the Invention [Problem to be solved by the invention]

[0004] CMP slurries containing cationized colloidal silica have the problem that the abrasive grains, cationized colloidal silica, are not very stable, and the physical properties of the slurry change between production and use, resulting in a decline in polishing performance.

[0005] The present invention has been made in view of the above circumstances, and aims to provide a slurry composition capable of producing a CMP slurry that is suppressed from changing in physical properties even when stored for a long period of time and has stable polishing performance, a method for storing the slurry composition, a method for producing a CMP slurry, and a polishing method. [Means for solving the problem]

[0006] In view of the above problems, the present inventors have conducted extensive research. As a result, they have found that a slurry composition containing colloidal silica and an acidic compound, having a pH of less than 7, in which the surface of the colloidal silica is modified with an aminosilane coupling agent, and in which the average particle-to-surface distance of the colloidal silica, as shown in the following formula (1), is less than 65 nm, exhibits suppressed changes in physical properties even after long-term storage and has stable polishing performance. In formula (1), h [nm] is the average particle-to-surface distance of the colloidal silica, and d p [nm] is the average secondary particle diameter of the colloidal silica, F is the ratio of the volume of the colloidal silica to the volume of the slurry composition, and π is the ratio of the circumference of a circle to its diameter.

[0007]

number

[0008] According to one aspect of the present invention, it is possible to provide a slurry composition capable of producing a CMP slurry that is suppressed from changing in physical properties even when stored for a long period of time and has stable polishing performance, a method for storing the slurry composition, a method for producing a CMP slurry, and a polishing method. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a graph showing the change in zeta potential of a CMP slurry made from a slurry composition stored at 80° C. for 7 days, relative to the change in zeta potential of a CMP slurry made from a slurry composition immediately after production, versus the mass concentration of colloidal silica in the slurry composition, in one embodiment of the present invention. [Figure 2]1 is a graph showing the change in zeta potential of a CMP slurry made from a slurry composition stored at 80° C. for 7 days, relative to the average inter-particle surface distance of colloidal silica in a slurry composition immediately after production, in one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention will be described in detail. A slurry composition according to an embodiment of the present invention contains colloidal silica and an acidic compound, and the pH of the slurry composition is less than 7. The surface of the colloidal silica is modified with an aminosilane coupling agent, and the average particle-to-surface distance h of the colloidal silica, as represented by the following formula (1), is less than 65 nm. Here, d p [nm] is the average secondary particle diameter of the colloidal silica, F is the ratio of the volume of the colloidal silica to the volume of the slurry composition, and π is the ratio of the circumference of a circle to its diameter.

[0011]

number

[0012] The slurry composition according to this embodiment may be used as a CMP slurry for storage, since the change in physical properties of the CMP slurry over time is small and the change in polishing performance can be suppressed, making it suitable for long-term storage.

[0013] The slurry composition according to this embodiment will be described in detail below. Note that the following embodiment shows an example of the present invention, and the present invention is not limited to the embodiment. Furthermore, various modifications or improvements can be made to the following embodiment, and such modifications or improvements can also be included in the present invention.

[0014] <Abrasive grain> The slurry composition according to this embodiment contains colloidal silica as abrasive grains. 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, colloidal silica produced by the sol-gel method, which can produce high-purity colloidal silica, is preferred.

[0015] (Surface modification) Colloidal silica is surface-modified with an aminosilane coupling agent. This surface modification causes the aminosilane coupling agent to be fixed to the surface of the colloidal silica, resulting in cationization. In this specification, cationized colloidal silica is referred to as "cationized colloidal silica." As a method for producing colloidal silica having an amino group, there is a method of immobilizing a silane coupling agent having an amino group, such as aminoethyltrimethoxysilane, on the surface of silica particles, as described in JP-A-2005-162533. In this specification, the silane coupling agent having an amino group is referred to as an "aminosilane coupling agent."

[0016] Examples of aminosilane coupling agents include bis(2-hydroxyethyl)-3-aminopropyltrialkoxysilane, diethylaminomethyltrialkoxysilane, (N,N-diethyl-3-aminopropyl)trialkoxysilane, 3-(N-styrylmethyl-2-aminoethylamino)propyltrialkoxysilane, aminopropyltrialkoxysilane, trialkoxysilylpropyl-N,N,N-trimethylammonium, bis(methyldialkoxysilylpropyl)-N-methylamine, bis(trialkoxysilylpropyl)urea, bis(3-(trialkoxysilyl)propyl )-ethylenediamine, bis(trialkoxysilylpropyl)amine, 3-aminopropyltrialkoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldialkoxysilane, N-(2-aminoethyl)-3-aminopropyltrialkoxysilane, 3-aminopropylmethyldialkoxysilane, 3-aminopropyltrialkoxysilane, (N-trialkoxysilylpropyl)polyethyleneimine, trialkoxysilylpropyldiethylenetriamine, N-phenyl-3-aminopropyltrialkoxysilane, and 4-aminobutyltrialkoxysilane. In the present embodiment, the aminosilane coupling agent that modifies the surface of the colloidal silica may be used alone, or two or more may be used in combination.

[0017] The aminosilane coupling agent can be added to the colloidal silica either undiluted or diluted with a hydrophilic organic solvent or pure water. Dilution with a hydrophilic organic solvent or pure water can suppress the formation of aggregates. The hydrophilic organic solvent is not particularly limited, but examples thereof include lower alcohols such as methanol, ethanol, isopropanol, and butanol.

[0018] The amount of aminosilane coupling agent used is not particularly limited, but may be such that the mass concentration of the aminosilane coupling agent in the slurry composition is 1 / 1000 times or more, 1 / 500 times or more, or 1 / 200 times or more of the mass concentration of colloidal silica in the slurry composition. Within these ranges, the degree of modification of colloidal silica increases, making it easier to obtain cationized colloidal silica that can be stably dispersed for a long period of time. Furthermore, the mass concentration of the aminosilane coupling agent in the slurry composition may be the same or less than the mass concentration of colloidal silica in the slurry composition, or may be 1 / 2 times or less, or may be 1 / 10 times or less. Within these ranges, problems such as an increase in the secondary particle size of colloidal silica, the formation of aggregates, and gelation are less likely to occur.

[0019] The dispersion stability of colloidal silica can be evaluated by measuring the zeta potential of the colloidal silica. As the absolute value of the zeta potential increases, the electrical repulsion between particles becomes stronger, resulting in higher particle stability. The closer the absolute value of the zeta potential is to zero, the more easily the particles aggregate. Since the zeta potential of ordinary colloidal silica is close to zero under acidic conditions, colloidal silica particles do not electrically repel each other under acidic conditions, so they are prone to aggregation. In contrast, cationized colloidal silica has a positive zeta potential, so particles strongly repel each other even under acidic conditions, making them less likely to aggregate. As a result, the storage stability of the slurry composition is improved.

[0020] (average particle surface distance of colloidal silica) The average particle surface distance (h) of colloidal silica can be calculated by the following formula (1): In formula (1), h [nm] is the average particle surface distance [nm] of colloidal silica, and d p [nm] is the average secondary particle diameter of the colloidal silica, F is the ratio of the volume of the colloidal silica to the volume of the slurry composition, and π is the ratio of the circumference of a circle to its diameter.

[0021]

number

[0022] The average particle-to-surface distance (h) of the cationized colloidal silica contained in the slurry composition may be less than 65 nm, less than 60 nm, or less than 55 nm. When the average particle-to-surface distance is within this range, the average particle-to-surface distance of the cationized colloidal silica contained in the slurry composition becomes much closer than that of a CMP slurry having an average particle-to-surface distance outside the above range. Therefore, even after a long time has passed since production, the aminosilane coupling agent modified on the surface of the colloidal silica contained in the slurry composition is less likely to be removed, making it easier to suppress a decrease in zeta potential.

[0023] The average particle-to-surface distance of the cationized colloidal silica can be appropriately controlled by adjusting the average secondary particle size and volume ratio of the colloidal silica. The larger the average secondary particle size of the colloidal silica, the larger the average particle-to-surface distance (h) tends to be, and the higher the volume ratio of the colloidal silica, the smaller the average particle-to-surface distance (h) tends to be.

[0024] (Average secondary particle size) The average secondary particle diameter of the cationized colloidal silica may be 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, or 50 nm or less. Furthermore, the average secondary particle diameter of the surface-modified cationized colloidal silica may be 30 nm or more, or 40 nm or more. Within these ranges, when the slurry composition is diluted and used as a CMP slurry, the polishing rate of the object to be polished is improved. Furthermore, the occurrence of surface defects on the surface of the object to be polished after polishing with the CMP slurry can be further suppressed. Note that the term "secondary particles" refers to particles formed by the aggregation of colloidal silica (primary particles) having an organic acid fixed to the surface in the slurry composition. The average secondary particle diameter of the secondary particles can be measured, for example, by dynamic light scattering.

[0025] The average secondary particle size of the cationized colloidal silica can be appropriately controlled by selecting a method for producing the cationized colloidal silica.

[0026] (Colloidal silica mass concentration) The mass concentration of colloidal silica in the slurry composition may be 5% by mass or more, or 5.4% by mass or more. The mass concentration of colloidal silica may be 20% by mass or less, or 18% by mass or less. When the mass concentration of colloidal silica is 5% by mass or more, it is possible to obtain a slurry composition that can maintain stable physical properties and polishing performance even after long-term storage.

[0027] <Acidic compounds> The pH of the slurry composition according to this embodiment may be less than 7, less than 5, or less than 3. The pH of the slurry composition according to this embodiment may be equal to or greater than 1, or may be equal to or greater than 2. If the pH is within this range, the zeta potential of the surface-modified cationized colloidal silica tends to be positive, making it less likely to aggregate in the slurry, thereby improving storage stability.

[0028] The pH of the slurry composition according to this embodiment can be adjusted by adding an acidic compound, specific examples of which include inorganic acids and organic acids. Specific examples of inorganic acids include sulfuric acid, nitric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, phosphoric acid, etc. As the acidic compound, an inorganic acid may be used, or sulfuric acid and nitric acid may be used, or nitric acid may be used. Organic acids include carboxylic acids and organic sulfuric acids. Specific examples of carboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, and lactic acid. Specific examples of organic sulfuric acids include methanesulfonic acid, ethanesulfonic acid, and isethionic acid. These acids may be used alone or in combination. These acids may be included in the slurry composition as additives to improve the polishing rate.

[0029] <Water-soluble polymer> The slurry composition according to the embodiment of the present invention may contain a water-soluble polymer. By containing a water-soluble polymer, it is possible to easily suppress changes in the zeta potential of the slurry composition.

[0030] Specific examples of water-soluble polymers include polyvinyl alcohol (PVA), polyvinylpyrrolidone, polyethylene glycol (PEG), polypropylene glycol (PPG), polybutylene glycol, copolymers of oxyethylene (EO) and oxypropylene (PO), methylcellulose, hydroxyethylcellulose, dextrin, pullulan, etc. These water-soluble polymers may be used alone or in combination of two or more. Furthermore, among water-soluble polymers, nonionic polymers are preferred because they do not affect the zeta potential of the slurry composition.

[0031] <Oxidizing agent> The slurry composition according to the embodiment of the present invention may contain an oxidizing agent. Specific examples of the oxidizing agent include hydrogen peroxide, peracetic acid, percarbonate, urea peroxide, perchloric acid, and persulfate. These oxidizing agents may be used alone or in combination of two or more.

[0032] <Mold inhibitors, preservatives> The slurry composition may contain an antifungal agent and a preservative. Specific examples of the antifungal agent and the preservative include isothiazolin-based preservatives (e.g., 2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one), paraoxybenzoic acid esters, and phenoxyethanol. These antifungal agents and preservatives may be used alone or in combination of two or more.

[0033] <Liquid medium> The slurry composition according to an embodiment of the present invention may contain a liquid medium. The liquid medium functions as a dispersion medium or solvent for dispersing or dissolving each component of the slurry composition (e.g., colloidal silica, aminosilane coupling agent, acidic compound, etc.). Examples of liquid media include water and organic solvents. One type may be used alone, or two or more types may be used in combination, but it is preferable for the liquid medium to contain water. However, from the viewpoint of preventing the inhibition of the action of each component, it is preferable to use water that contains as few impurities as possible. Specifically, pure water or ultrapure water that has been filtered to remove impurity ions using an ion exchange resin and then purified of foreign matter, or distilled water, is preferred.

[0034] <Method for producing slurry composition> The method for producing the slurry composition of this embodiment is not particularly limited, and it can be produced by stirring and mixing colloidal silica surface-modified with an aminosilane coupling agent, an acidic compound, and, if necessary, various additives (e.g., water-soluble polymers, oxidizing agents, antifungal agents, etc.) in a liquid medium such as water. The temperature during mixing is not particularly limited, but is preferably, for example, 10°C or higher and 40°C or lower, and heating may be used to improve the dissolution rate. The mixing time is also not particularly limited.

[0035] <Method for storing slurry composition> A method for storing a slurry composition according to another embodiment of the present invention includes preparing a slurry composition containing colloidal silica whose surface is modified with an aminosilane coupling agent and an acidic compound and having a pH less than 7 such that the average particle surface distance (h) of the colloidal silica represented by the formula (1) is less than 65 nm, and storing the prepared slurry composition. Here, h [nm] is the average particle surface distance of the colloidal silica, d p [nm] is the average secondary particle diameter of the colloidal silica contained in the slurry composition, F is the ratio of the volume of the colloidal silica to the volume of the slurry composition, and π is the ratio of the circumference of a circle to its diameter. Also, "preparing" means selecting the average secondary particle diameter and volume ratio of the colloidal silica to produce a slurry composition having a desired average particle surface distance.

[0036]

Number

[0037] The slurry composition in the method for storing a slurry composition according to this embodiment is the same composition as the slurry composition according to the present invention described above.

[0038] In the method for storing a slurry composition according to this embodiment, the slurry composition is stored in a high-concentration state in which physical property changes are unlikely to occur. Therefore, the CMP slurry obtained by diluting the slurry composition at the time of use can have excellent polishing performance compared to the case where the CMP slurry is stored in a state of a normal low-concentration CMP slurry.

[0039] <Method for manufacturing CMP slurry> Another embodiment of the present invention relates to a method for producing a CMP slurry, comprising: preparing a slurry composition containing colloidal silica whose surface has been modified with an aminosilane coupling agent and an acidic compound, and having a pH of less than 7, such that the average particle-to-surface distance (h) of the colloidal silica, as represented by formula (1), is less than 65 nm; storing the prepared slurry composition; and diluting the stored slurry composition with a liquid medium to obtain a CMP slurry. Here, h [nm] is the average particle-to-surface distance of the colloidal silica, and d p [nm] is the average secondary particle size of the colloidal silica contained in the slurry composition, F is the ratio of the volume of the colloidal silica to the volume of the slurry composition, and π is the ratio of the circumference of the circle to its diameter.

[0040]

number

[0041] The slurry composition in the method for producing a CMP slurry according to this embodiment is the same as the above-described slurry composition according to the present invention.

[0042] <Polishing method> The polishing method according to this embodiment includes diluting the slurry composition according to the present invention with a liquid medium to obtain a CMP slurry, and polishing an object to be polished provided on a substrate using the obtained CMP slurry. Examples of liquid media used for dilution include water and organic solvents. One type may be used alone, or two or more types may be used in combination, but it is preferable to use water. However, from the viewpoint of preventing the inhibition of the action of each component, it is preferable to use water that contains as few impurities as possible. Specifically, pure water or ultrapure water, which has been filtered to remove impurity ions using an ion exchange resin, or distilled water, is preferred. The liquid medium used for dilution may be the same type of liquid medium as the liquid medium used in the slurry composition of the present invention, or a different type of liquid medium.

[0043] In the polishing method according to this embodiment, the configuration of the polishing apparatus is not particularly limited, but for example, a general polishing apparatus including a holder for holding a substrate or the like having an object to be polished, a drive unit such as a motor capable of changing the rotation speed, and a polishing table to which a polishing pad (polishing cloth) can be attached can be used. The polishing pad can be made of general nonwoven fabric, polyurethane, porous fluororesin, or the like, without any particular restrictions. The polishing pad can be grooved to allow liquid CMP slurry to accumulate.

[0044] There are no particular restrictions on the polishing conditions. For example, the rotation speed of the polishing platen is 10 rpm (0.17 s -1 ) or more 500rpm(8.3s -1 ) or less is preferable. The pressure (polishing pressure) applied to the substrate having the object to be polished is preferably 0.5 psi (3.4 kPa) or more and 10 psi (68.9 kPa) or less. There are no particular restrictions on the method of supplying the CMP slurry to the polishing pad, and a method of continuously supplying it using a pump or the like is used. There is no restriction on the amount of supply, but it is preferable that the surface of the polishing pad is always covered with the CMP slurry according to this embodiment. The CMP slurry may be a one-component type or a multi-component type such as a two-component type.

[0045] After polishing, the substrate is washed with, for example, running water, and then dried using a spin dryer or the like to remove water droplets adhering to the substrate, thereby obtaining a substrate having, for example, a layer containing a silicon-containing material. In this way, the CMP slurry according to this embodiment can be used for substrate polishing.

[0046] By using the CMP slurry according to this embodiment to polish the surface of an object to be polished provided on a semiconductor substrate, the surface of the semiconductor substrate can be polished at a high polishing rate to produce a polished semiconductor substrate. Examples of semiconductor substrates include silicon, polysilicon, silicon oxide (silicon oxide), silicon nitride, and wiring and plugs made of metal or the like. [Example]

[0047] 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. Furthermore, various modifications or improvements can be made to the following examples, and such modifications or improvements can also be included in the present invention.

[0048] Example 1 <Preparation of Slurry Composition> A surface-modified cationized colloidal silica was obtained by adding 3-aminopropyltriethoxysilane (83.48 mmol / L) as an aminosilane coupling agent to a colloidal silica stock solution (20 mass%). The average secondary particle diameter of the resulting cationized colloidal silica was 50 nm.

[0049] The above-mentioned surface-modified cationized colloidal silica, nitric acid, and water were mixed with stirring to prepare a slurry composition (Example 1) with a colloidal silica mass concentration of 5.4 mass %.

[0050] <Storage of Slurry Composition and Preparation of CMP Slurry> The obtained slurry composition was stored at 80°C for 7 days. Note that "7 days at 80°C" corresponds to "317 days at 25°C" according to the Arrhenius acceleration equation. Thereafter, the slurry composition after storage was diluted with water so that the mass concentration of colloidal silica became 0.9 mass% to prepare a CMP slurry.

[0051] (Examples 2 to 5, Comparative Examples 1 and 2) Slurry compositions of Examples 2 to 5 and Comparative Examples 1 and 2 were prepared in the same manner as in Example 1, except that the colloidal silica concentrations in the slurry compositions were as shown in Table 1 below. Then, similarly to Example 1, the compositions were stored at 80°C for 7 days and diluted with water so that the mass concentration of colloidal silica became 0.9 mass%, thereby producing CMP slurries.

[0052] (Reference example) The slurry composition of Example 1 was diluted with water so that the mass concentration of colloidal silica became 0.9% by mass, and a CMP slurry of the reference example was obtained. Different from Example 1, storage at 80 °C for 7 days was not performed on the slurry composition.

[0053] <Calculation of average particle surface distance> The average particle surface distance of colloidal silica in the slurry compositions of Examples 1 to 5 and Comparative Examples 1 and 2 was calculated from the following formula (1). In formula (1), h is the average particle surface distance [nm], and d p [nm] is the average secondary particle diameter of colloidal silica, F is the ratio of the volume of colloidal silica to the volume of the slurry composition, and π is the ratio of the circumference of a circle to its diameter. Also, the volume ratio F of colloidal silica was determined by conversion from the mass concentration of colloidal silica. The results are shown in Table 1.

[0054]

Number

[0055]

Table 1

[0056] <pH measurement> The pH of the slurry compositions (liquid temperature: 25 °C) of Examples 1 to 5 and Comparative Examples 1 and 2, and the CMP slurries of Examples 1 to 5, Comparative Examples 1 and 2, and the reference example (liquid temperature: 25 °C) was measured with a pH meter (product name: LAQUA (registered trademark), manufactured by Horiba, Ltd.). These results are shown in Table 1.

[0057] <Measurement of zeta potential> The zeta potentials of the cationized colloidal silica in the CMP slurries of Examples 1 to 5 and Comparative Examples 1 and 2 were measured. The zeta potential was calculated by subjecting each CMP slurry to a Zetasizer Nano manufactured by Malvern Panalytical, measuring it at a measurement temperature of 25°C using a flow cell by the laser Doppler method (electrophoretic light scattering measurement method), and analyzing the obtained data using the Smoluchowski equation.

[0058] The amount of decrease in zeta potential was calculated by subtracting the zeta potential of the CMP slurries of Examples 1 to 5 and Comparative Examples 1 and 2 from the zeta potential of the CMP slurry of Reference Example. The rate of decrease in zeta potential was calculated by dividing the amount of decrease in zeta potential by the zeta potential of the CMP slurry of Reference Example. These results are shown in Table 1. The correlation between the rate of decrease in zeta potential and the mass concentration of colloidal silica [mass %] is shown in Figure 1. Furthermore, the correlation between the rate of decrease in zeta potential and the average inter-particle surface distance [nm] of colloidal silica is shown in Figure 2.

[0059] <Polishing speed measurement> Using the CMP slurries of Examples 1 to 5 and Comparative Examples 1 and 2, silicon wafers with a diameter of 300 mm and coated with a silicon dioxide film (TEOS film) were polished under the following polishing conditions. Polishing equipment: Ebara Corporation 300mm CMP single-sided polishing equipment FREX300E Polishing pad: Nitta DuPont polyurethane pad IC1000 Polishing pressure: 3.0 psi (1 psi = 6894.76 Pa) Polishing platen rotation speed: 110 rpm Head rotation speed: 103 rpm ·CMP slurry supply: free-flowing CMP slurry supply rate: 250 mL / min Polishing time: 60 seconds

[0060] For silicon wafers, the film thickness before and after polishing was measured using an ellipsometric film thickness measuring device RE-3500 (SCREEN Semiconductor Solutions Co., Ltd.) and the polishing rate was calculated from the difference in film thickness and the polishing time.

[0061] The increase in the TEOS film polishing rate was calculated by subtracting the polishing rate with the CMP slurry of the Reference Example from the polishing rate with the CMP slurries of Examples 1 to 5 and Comparative Examples 1 and 2. The increase rate in the polishing rate was calculated by dividing the increase in the polishing rate by the polishing rate of the Reference Example. These results are shown in Table 1.

[0062] <Evaluation> As shown in Table 1, the CMP slurries of Examples 1 to 5 had a zeta potential of 30 mV or more, a decrease of 3 mV or less, and a decrease rate of 10% or less. On the other hand, in Comparative Examples 1 and 2, the zeta potential was 25 mV or less, a decrease of more than 10 mV, and a decrease rate of more than 30%, indicating a larger change compared to the CMP slurries of the Examples.

[0063] In Examples 1 to 5, the polishing speed of the TEOS film was 76 Å / min or less, the increase was 5.5 Å / min or less, and the increase rate was 8% or less. On the other hand, in Comparative Examples 1 and 2, the polishing speed of the TEOS film was more than 76 Å / min, the increase was more than 5.5 Å / min, and the increase rate was more than 8%, and it was found that the change rate was larger in both cases than in the Examples.

[0064] These results indicate that slurry compositions in which the mass concentration of colloidal silica is 5 mass % or more as shown in FIG. 1, or in which the average inter-particle surface distance of colloidal silica is 65 nm or less as shown in FIG. 2, tend to exhibit small changes in zeta potential and polishing performance over time.

[0065] The reason for the small changes in zeta potential and polishing performance over time is thought to be as follows: A colloidal silica mass concentration of 5% by mass or more or an average particle-to-surface distance of colloidal silica of 65 nm or less means that the distance between cationized colloidal silica particles is very short. Normally, the aminosilane coupling agent modified on the surface of colloidal silica in a CMP slurry is unstable and therefore detaches from the colloidal silica surface over time and diffuses throughout the slurry. On the other hand, in the slurry composition of the present invention, the average particle-to-surface distance of the cationized colloidal silica is very short, making it less likely to detach from the surface. Therefore, it is thought that a CMP slurry made from the slurry composition of the present invention that has been stored for a long period of time will show little change in its physical properties and polishing performance.

[0066] Furthermore, for example, the present invention can have the following configuration. [1] A slurry composition comprising colloidal silica and an acidic compound, pH is less than 7, the surface of the colloidal silica is modified with an aminosilane coupling agent; The average secondary particle diameter of the colloidal silica is d p a ratio of the volume of the colloidal silica to the volume of the slurry composition is F, and π is the ratio of the diameter of a circle to its circumference; and the average particle-to-surface distance h of the colloidal silica, as represented by formula (1), is less than 65 nm.

[0067]

number

[0068] [2] The slurry composition according to [1], which is a CMP slurry for storage. [3] The slurry composition according to [1] or [2], having a pH of less than 5. [4] The slurry composition according to any one of [1] to [3], wherein the colloidal silica has an average secondary particle size of less than 90 nm. [5] The aminosilane coupling agent may be bis(2-hydroxyethyl)-3-aminopropyltrialkoxysilane, diethylaminomethyltrialkoxysilane, (N,N-diethyl-3-aminopropyl)trialkoxysilane, 3-(N-styrylmethyl-2-aminoethylamino)propyltrialkoxysilane, aminopropyltrialkoxysilane, trialkoxysilylpropyl-N,N,N-trimethylammonium, (bis(methyldialkoxysilylpropyl)-N-methylamine, bis(trialkoxysilylpropyl)urea, bis(3-(trialkoxysilyl)propyl)-ethylenediamine, bis ...

[0023] The slurry composition according to any one of [1] to [4], wherein the alkoxysilane is at least one selected from the group consisting of N-(2-aminoethyl)-3-aminopropyltrialkoxysilane, N-(2-aminoethyl)-3-aminopropyltrialkoxysilane, 3-aminopropylmethyldialkoxysilane, 3-aminopropyltrialkoxysilane, (N-trialkoxysilylpropyl)polyethyleneimine, trialkoxysilylpropyldiethylenetriamine, N-phenyl-3-aminopropyltrialkoxysilane, and 4-aminobutyltrialkoxysilane.

[0069] [6] A slurry composition containing colloidal silica whose surface is modified with an aminosilane coupling agent and an acidic compound and having a pH of less than 7 is prepared by subjecting the colloidal silica to an average secondary particle diameter of d p the average particle-to-surface distance h of the colloidal silica, as represented by formula (1), is less than 65 nm, where F is the ratio of the volume of the colloidal silica to the volume of the slurry composition, and π is the ratio of the circumference of a circle to its diameter. storing the prepared slurry composition; A method for storing a slurry composition, comprising:

[0070]

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[0071] [7] The method for storing the slurry composition according to [6], comprising adjusting the mass concentration of the colloidal silica contained in the slurry composition to 5 mass% or more. [8] The method for storing a slurry composition according to [6] or [7], wherein the colloidal silica has an average secondary particle diameter of less than 90 nm.

[0072] [9] The aminosilane coupling agent may be bis(2-hydroxyethyl)-3-aminopropyltrialkoxysilane, diethylaminomethyltrialkoxysilane, (N,N-diethyl-3-aminopropyl)trialkoxysilane, 3-(N-styrylmethyl-2-aminoethylamino)propyltrialkoxysilane, aminopropyltrialkoxysilane, trialkoxysilylpropyl-N,N,N-trimethylammonium, (bis(methyldialkoxysilylpropyl)-N-methylamine, bis(trialkoxysilylpropyl)urea, bis(3-(trialkoxysilyl)propyl)-ethylenediamine, bis(trialkoxysilyl)propyl

[0023] The method for storing a slurry composition according to any one of [6] to [8], wherein the silyl group is at least one selected from the group consisting of N-(2-aminoethyl)-3-aminopropyltrialkoxysilane, N-(2-aminoethyl)-3-aminopropyltrialkoxysilane, 3-aminopropylmethyldialkoxysilane, 3-aminopropyltrialkoxysilane, (N-trialkoxysilylpropyl)polyethyleneimine, trialkoxysilylpropyldiethylenetriamine, N-phenyl-3-aminopropyltrialkoxysilane, and 4-aminobutyltrialkoxysilane.

[10] A method for producing a CMP slurry for use in chemical mechanical polishing, comprising: A slurry composition containing colloidal silica whose surface has been modified with an aminosilane coupling agent and an acidic compound and having a pH of less than 7 is prepared by dissolving the colloidal silica in a slurry containing an acidic compound and an acidic compound in a slurry containing colloidal silica whose surface has been modified with an aminosilane coupling agent and an acidic compound in a slurry containing colloidal silica whose average secondary particle diameter is d pthe average particle-to-surface distance h of the colloidal silica, as represented by formula (1), is less than 65 nm, where F is the ratio of the volume of the colloidal silica to the volume of the slurry composition, and π is the ratio of the circumference of a circle to its diameter. storing the prepared slurry composition; diluting the stored slurry composition with a liquid medium to obtain a CMP slurry; A method for producing a CMP slurry, comprising:

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[11] Diluting the slurry composition according to any one of [1] to [5] in a liquid medium to obtain a CMP slurry; and polishing an object to be polished provided on a substrate using the obtained CMP slurry.

Claims

1. A slurry composition comprising colloidal silica and an acidic compound, the pH is less than 7, the surface of the colloidal silica is modified with an aminosilane coupling agent; The average secondary particle diameter of the colloidal silica is d ｐ wherein the average particle-to-surface distance h of the colloidal silica, as represented by formula (1), is less than 65 nm, where F is the ratio of the volume of the colloidal silica to the volume of the slurry composition, and π is the ratio of the circumference of a circle to its diameter. [Equation 1]

2. 10. The slurry composition of claim 1, which is a storage CMP slurry.

3. 3. The slurry composition of claim 1 or claim 2, wherein the pH is less than 5.

4. 3. The slurry composition according to claim 1, wherein the colloidal silica has an average secondary particle size of less than 90 nm.

5. The aminosilane coupling agent may be bis(2-hydroxyethyl)-3-aminopropyltrialkoxysilane, diethylaminomethyltrialkoxysilane, (N,N-diethyl-3-aminopropyl)trialkoxysilane, 3-(N-styrylmethyl-2-aminoethylamino)propyltrialkoxysilane, aminopropyltrialkoxysilane, trialkoxysilylpropyl-N,N,N-trimethylammonium, bis(methyldialkoxysilylpropyl)-N-methylamine, bis(trialkoxysilylpropyl)urea, bis(3-(trialkoxysilyl)propyl)-ethylenediamine, bis(trialk ...

3. The slurry composition according to claim 1, wherein the compound is at least one selected from the group consisting of (N-trialkoxysilylpropyl)amine, 3-aminopropyltrialkoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldialkoxysilane, N-(2-aminoethyl)-3-aminopropyltrialkoxysilane, 3-aminopropylmethyldialkoxysilane, 3-aminopropyltrialkoxysilane, (N-trialkoxysilylpropyl)polyethyleneimine, trialkoxysilylpropyldiethylenetriamine, N-phenyl-3-aminopropyltrialkoxysilane, and 4-aminobutyltrialkoxysilane.

6. A slurry composition containing colloidal silica whose surface has been modified with an aminosilane coupling agent and an acidic compound and having a pH of less than 7 is prepared by adjusting the average secondary particle diameter of the colloidal silica to d ｐ the average particle-to-surface distance h of the colloidal silica, as represented by formula (1), is less than 65 nm, where F is the volume ratio of the colloidal silica to the volume of the slurry composition, and π is the ratio of the circumference of a circle to its diameter. storing the prepared slurry composition; A method for storing a slurry composition, comprising: [Equation 2]

7. The method for storing a slurry composition according to claim 6 , comprising adjusting the mass concentration of the colloidal silica contained in the slurry composition to 5 mass % or more.

8. 8. The method for storing a slurry composition according to claim 6 or 7, wherein the colloidal silica has an average secondary particle size of less than 90 nm.

9. The aminosilane coupling agent may be bis(2-hydroxyethyl)-3-aminopropyltrialkoxysilane, diethylaminomethyltrialkoxysilane, (N,N-diethyl-3-aminopropyl)trialkoxysilane, 3-(N-styrylmethyl-2-aminoethylamino)propyltrialkoxysilane, aminopropyltrialkoxysilane, trialkoxysilylpropyl-N,N,N-trimethylammonium, bis(methyldialkoxysilylpropyl)-N-methylamine, bis(trialkoxysilylpropyl)urea, bis(3-(trialkoxysilyl)propyl)-ethylenediamine, bis(trialkoxysilylpropyl) 8. The method for storing a slurry composition according to claim 6 or 7, wherein the silane is at least one selected from the group consisting of N-(2-aminoethyl)-3-aminopropyltrialkoxysilane, N-(2-aminoethyl)-3-aminopropyltrialkoxysilane, 3-aminopropylmethyldialkoxysilane, 3-aminopropyltrialkoxysilane, (N-trialkoxysilylpropyl)polyethyleneimine, trialkoxysilylpropyldiethylenetriamine, N-phenyl-3-aminopropyltrialkoxysilane, and 4-aminobutyltrialkoxysilane.

10. 1. A method for producing a CMP slurry for use in performing chemical mechanical polishing, comprising: A slurry composition containing colloidal silica whose surface has been modified with an aminosilane coupling agent and an acidic compound and having a pH of less than 7 is prepared by adjusting the average secondary particle diameter of the colloidal silica to d ｐ the average particle-to-surface distance h of the colloidal silica, as represented by formula (1), is less than 65 nm, where F is the volume ratio of the colloidal silica to the volume of the slurry composition, and π is the ratio of the circumference of a circle to its diameter. storing the prepared slurry composition; diluting the stored slurry composition with a liquid medium to obtain a CMP slurry; A method for producing a CMP slurry, comprising: [Equation 3]

11. Diluting the slurry composition of claim 1 with a liquid medium to obtain a CMP slurry; and polishing an object to be polished provided on a substrate using the obtained CMP slurry.

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