Sulfonic acid modified colloidal silica and its manufacturing method

Abstract

The present invention provides a sulfonic acid-modified colloidal silica which is excellent in stability over time of the amount of metal adsorption and can suppress the amount of abrasive grains remaining on the polished metal surface after polishing and cleaning. The present invention provides a sulfonic acid modified colloidal silica containing silica particles, (1) The silica particles have a surface modified with a sulfonic acid group, (2) the Cu ion adsorption amount of the silica particles is 5.00 to 110.00 μmol / g; (3) The ratio of Cu ion adsorption amount to S content of the silica particles (Cu ion adsorption amount (μmol / g) / S content (μmol / g)) is 0.50 or more, (4) The rate of change over time in the amount of Cu ion adsorption of the silica particles is 1.30 or less, as measured by the following measurement method: 1. A sulfonic acid-modified colloidal silica comprising: [Method for measuring the rate of change over time in Cu ion adsorption amount on silica particles] The sulfonic acid-modified colloidal silica is allowed to stand for three months at 25° C. The amount of Cu ions adsorbed to the silica particles (μmol / g) before and after standing is measured, and the rate of change over time in the amount of Cu ions adsorbed to the silica particles is calculated using the following formula. (Change in Cu ion adsorption amount of silica particles over time) = Cu ion adsorption amount after standing (μmol / g) / Cu ion adsorption amount before standing (μmol / g)

Description

[Technical field]

[0001] The present invention relates to a sulfonic acid-modified colloidal silica and a method for producing the same. [Background technology]

[0002] Colloidal silica is silica particles dispersed in a medium such as water, and is used as a property improver in the fields of paper, textiles, steel, etc., as well as an abrasive used in polishing semiconductor devices such as semiconductor wafers (CMP).

[0003] In the manufacturing process of semiconductor devices, a polishing process is performed in which metal materials such as wiring materials and barrier metal materials are polished to form wiring structures. In the polishing process, it is required to polish and remove the metal materials at a high speed in order to improve the productivity of semiconductor devices.

[0004] In order to polish and remove metal materials at high speed, sulfonic acid-modified colloidal silica, which has sulfo groups on its surface that have the property of chemically reacting with and adsorbing metals, is used as an abrasive for polishing.

[0005] In light of this background, various inventions relating to sulfonic acid-modified colloidal silica have been filed for patent. For example, Patent Document 1 discloses sulfonic acid-modified colloidal silica, and discloses that the sulfonic acid-modified colloidal silica can be suitably used for semiconductor polishing applications.

[0006] Furthermore, Patent Document 2 discloses that a high metal film polishing rate can be achieved while suppressing corrosion of the metal film by using a polishing slurry that contains, as an abrasive, silica particles having functional groups (sulfo groups) on the surface that are reactive to metal films and that contains substantially no etching agent. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2023-146033 A [Patent Document 2] JP 2020-115501 A Summary of the Invention [Problem to be solved by the invention]

[0008] As a result of intensive research, the present inventors have found that conventional sulfonic acid-modified colloidal silica has the following problem: When sulfonic acid-modified colloidal silica is stored for a long period of time, the amount of metal adsorbed thereon changes over time, and as a result, when the sulfonic acid-modified colloidal silica is used as abrasive grains for polishing metal materials, the polishing removal rate of the metal changes over time.

[0009] Furthermore, when the sulfonic acid-modified colloidal silica is used as an abrasive for polishing metal materials, there is a problem that a large amount of silica abrasive remains on the polished metal surface after polishing and cleaning because the adsorptivity to metals is too high.

[0010] For example, Patent Documents 1 and 2 do not discuss the stability of the metal adsorption amount over time for sulfonic acid-modified colloidal silica. Furthermore, the inventors have confirmed that the metal adsorption amount of the sulfonic acid-modified colloidal silica produced by the method described in these documents changes over time, which causes a problem that the polishing removal rate of metal changes over time when the sulfonic acid-modified colloidal silica is used as an abrasive for polishing metal.

[0011] In view of the above circumstances, an object of the present invention is to provide a sulfonic acid-modified colloidal silica which has excellent stability over time in the amount of metal adsorption and can suppress the amount of abrasive grains remaining on the polished metal surface after polishing and cleaning. [Means for solving the problem]

[0012] As a result of intensive research into achieving the above-mentioned object, the present inventors have found that the above-mentioned object can be achieved by a sulfonic acid-modified colloidal silica which contains silica particles whose surfaces are modified with sulfonic acid groups, in which the Cu ion adsorption amount of the silica particles and the ratio of the Cu ion adsorption amount of the silica particles to the S content are in specific ranges, and in which the rate of change over time in the Cu ion adsorption amount of the silica particles, as measured by a specific measurement method, is in a specific range, and have thus completed the present invention.

[0013] That is, the present invention relates to the following sulfonic acid-modified colloidal silica and a production method thereof. 1. A sulfonic acid modified colloidal silica containing silica particles, (1) The silica particles have a surface modified with a sulfonic acid group, (2) the Cu ion adsorption amount of the silica particles is 5.00 to 110.00 μmol / g; (3) The ratio of Cu ion adsorption amount to S content of the silica particles (Cu ion adsorption amount (μmol / g) / S content (μmol / g)) is 0.50 or more, (4) The rate of change over time in the amount of Cu ion adsorption of the silica particles is 1.30 or less, as measured by the following measurement method: 1. A sulfonic acid-modified colloidal silica comprising: [Method for measuring the rate of change over time in Cu ion adsorption amount on silica particles] The sulfonic acid modified colloidal silica is allowed to stand for 3 months at 25° C. The amount of Cu ions adsorbed to the silica particles (μmol / g) before and after standing is measured, and the rate of change over time in the amount of Cu ions adsorbed to the silica particles is calculated using the following formula. (Change in Cu ion adsorption amount of silica particles over time) = Cu ion adsorption amount after standing (μmol / g) / Cu ion adsorption amount before standing (μmol / g) 2. The sulfonic acid modified colloidal silica according to item 1, wherein the amount of Cu ions adsorbed on the silica particles is 8.00 to 105.00 μmol / g. 3. The sulfonic acid modified colloidal silica according to item 1 or 2, wherein the silica particles have an S content of 10.00 to 200.00 μmol / g. 4. The sulfonic acid modified colloidal silica according to any one of items 1 to 3, wherein the ratio of the Cu ion adsorption amount to the S content is 0.55 or more. 5. The sulfonic acid modified colloidal silica according to any one of items 1 to 4, having a hydrogen peroxide concentration of 1000 ppm or less. 6. A method for producing sulfonic acid-modified colloidal silica, comprising the steps of: (I) a step I of modifying colloidal silica by adding a silane coupling agent having a mercapto group; (II) adding hydrogen peroxide to the modified colloidal silica to oxidize the mercapto groups on the surface of the silica particles and convert them into sulfo groups; and (III) a step III of heating the colloidal silica to which hydrogen peroxide has been added at a temperature of 80° C. or higher for 15 hours or longer; The amount of the silane coupling agent having a mercapto group added is 25.00 to 400.00 μmol / g per 1 g of silica particles, The amount of hydrogen peroxide added is 3.30 mol / mol or more per 1 mol of the silane coupling agent having a mercapto group. A manufacturing method comprising the steps of: 7. The method according to item 6, wherein the silane coupling agent having a mercapto group is at least one selected from the group consisting of 3-mercaptopropyltrimethoxysilane, 2-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane. Effect of the Invention

[0014] The sulfonic acid modified colloidal silica of the present invention has excellent stability over time in the amount of metal adsorption, and the change over time in the polishing removal rate of metal is suppressed.Furthermore, the sulfonic acid modified colloidal silica of the present invention exhibits a high polishing removal rate of metal, and the amount of abrasive grains remaining on the polished metal surface after polishing and cleaning is suppressed.Furthermore, according to the production method of the present invention, the above-mentioned sulfonic acid modified colloidal silica of the present invention can be produced. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention will be described in detail below. Note that the following description of the components may be based on representative embodiments and specific examples, but the present invention is not limited to such embodiments.

[0016] In the numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. In addition, in the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in an example or a value that can be unambiguously derived from an example. Furthermore, in this specification, a numerical value connected with "~" means a numerical range that includes the numerical values ​​before and after "~" as the lower and upper limits.

[0017] In this specification, the expressions "contain" and "include" include the concepts of "contain", "include", "consist essentially of" and "consist only of".

[0018] The sulfonic acid-modified colloidal silica of the present invention is a sulfonic acid-modified colloidal silica containing silica particles, characterized in that: (1) the silica particles have surfaces modified with sulfonic acid groups; (2) the silica particles have a Cu ion adsorption amount of 5.00 to 110.00 μmol / g; (3) the ratio of the Cu ion adsorption amount to the S content of the silica particles (Cu ion adsorption amount (μmol / g) / S content (μmol / g)) is 0.50 or more; and (4) the rate of change over time in the Cu ion adsorption amount of the silica particles, as measured by a specific measurement method, is 1.30 or less.

[0019] The sulfonic acid modified colloidal silica of the present invention has (1) silica particles whose surfaces are modified with sulfonic acid groups and has the configurations (2) to (4), and therefore the metal adsorption capacity is controlled within an appropriate range for abrasive grains for metal polishing, and the metal adsorption amount is highly stable over time. Such sulfonic acid modified colloidal silica of the present invention has a suppressed change over time in the metal polishing removal rate, and the amount of abrasive grains remaining on the polished metal surface after polishing and cleaning is extremely small, so that it can be used extremely suitably as abrasive grains for metal polishing.

[0020] The manufacturing method of the present invention includes (I) a step I of adding a silane coupling agent having a mercapto group to colloidal silica to perform a modification treatment, (II) a step II of adding hydrogen peroxide to the modified colloidal silica to oxidize the mercapto group on the surface of the silica particles and convert it to a sulfo group, and (III) a step III of heating the colloidal silica to which hydrogen peroxide has been added at a temperature of 80° C. or higher for 15 hours or more, and the amount of the silane coupling agent having a mercapto group and the amount of the hydrogen peroxide added are within a specific range. According to the manufacturing method of the present invention, the amount of the modifier added to modify the surface of the raw colloidal silica with sulfonic acid is optimized, and the colloidal silica is heated under appropriate conditions after the addition of the modifier, so that the metal adsorption capacity is controlled within an appropriate range as an abrasive grain for metal polishing, and a sulfonic acid modified colloidal silica having high stability over time in the amount of metal adsorption can be produced.

[0021] The colloidal silica of the present invention and its production method will be described in detail below.

[0022] 1. Sulfonic acid modified colloidal silica The sulfonic acid-modified colloidal silica of the present invention (hereinafter also simply referred to as "colloidal silica") is a sulfonic acid-modified colloidal silica containing silica particles, in which (1) the surfaces of the silica particles are modified with sulfonic acid groups, (2) the Cu ion adsorption amount of the silica particles is 5.00 to 110.00 μmol / g, (3) the ratio of the Cu ion adsorption amount to the S content of the silica particles (Cu ion adsorption amount (μmol / g) / S content (μmol / g)) is 0.50 or more, and (4) the rate of change over time in the Cu ion adsorption amount of the silica particles, as measured by a specific measurement method, is 1.30 or less.

[0023] The silica particles contained in the colloidal silica of the present invention have their surfaces modified with sulfonic acid groups. In this specification, the state in which the surfaces of the silica particles are modified with sulfonic acid groups means a state in which sulfonic acid groups are introduced onto the surfaces of the silica particles by sulfonic acid modification.

[0024] Whether the surface of the colloidal silica has been modified with a sulfonic acid group can be confirmed by a method for confirming the presence or absence of a sulfo group on the particle surface by X-ray photoelectron spectroscopy (XPS) in the examples described later.

[0025] The Cu ion adsorption amount of the silica particles contained in the colloidal silica of the present invention is 5.00 to 110.00 μmol / g. If the Cu ion adsorption amount is less than 5.00 μmol / g, the polishing removal rate of metal decreases. If the Cu ion adsorption amount exceeds 110.00 μmol / g, the adsorption ability to the metal to be polished becomes excessively high, and the amount of abrasive grains remaining on the polished metal surface after polishing and cleaning increases. The Cu ion adsorption amount is preferably 8.00 to 105.00 μmol / g, more preferably 8.20 to 103.00 μmol / g.

[0026] In this specification, the Cu ion adsorption amount of the silica particles is measured by the measurement method described in the examples described later.

[0027] The silica particles contained in the colloidal silica of the present invention preferably have an S content of 10.00 to 200.00 μmol / g, more preferably 12.00 to 190.00 μmol / g, even more preferably 13.00 to 185.00 μmol / g, and particularly preferably 14.00 to 180.00 μmol / g. By setting the lower limit of the S content within the above range, the polishing removal rate of metal is further improved. In addition, by setting the upper limit of the S content within the above range, adsorption to the metal to be polished is appropriately suppressed, and the amount of abrasive grains remaining on the polished metal surface after polishing and cleaning is reduced.

[0028] In this specification, the S content of the silica particles is measured by the measurement method described in the examples below.

[0029] The colloidal silica of the present invention has a ratio of Cu ion adsorption amount to S content (Cu ion adsorption amount (μmol / g) / S content (μmol / g)) of 0.50 or more in silica particles. If the ratio of Cu ion adsorption amount to S content is less than 0.50, the metal adsorption amount changes significantly over time, and the polishing removal rate of metal changes significantly over time during storage of the slurry. The ratio of Cu ion adsorption amount to S content is preferably 0.53 or more, more preferably 0.55 or more. The upper limit of the ratio of Cu ion adsorption amount to S content is not particularly limited, and is preferably 1.30 or less, more preferably 1.10 or less.

[0030] In this specification, the ratio of the Cu ion adsorption amount to the S content (Cu ion adsorption amount / S content) is measured by the measurement method described in the examples described later.

[0031] The colloidal silica of the present invention has a rate of change over time of Cu ion adsorption amount of the silica particles of 1.30 or less. If the rate of change over time is less than 1.30, the rate of change over time of the polishing removal rate of metal increases. The rate of change over time is preferably 1.20 or less, more preferably 1.15 or less. The lower limit of the rate of change over time is not particularly limited, and may be 0.90, 0.95, 1.00, or 1.02.

[0032] In this specification, the rate of change over time in the amount of Cu ion adsorption on the silica particles is measured by the measurement method described in the examples below.

[0033] The colloidal silica of the present invention may contain hydrogen peroxide.

[0034] The hydrogen peroxide concentration of the colloidal silica of the present invention is preferably 1000 ppm or less, more preferably 900 ppm or less, even more preferably 800 ppm or less, and particularly preferably 700 ppm or less. The hydrogen peroxide concentration is preferably 10 ppm or more, more preferably 20 ppm or more, and even more preferably 30 ppm or more. By setting the lower limit of the hydrogen peroxide concentration within the above range, the polishing removal rate of metal is further improved. By setting the upper limit of the hydrogen peroxide concentration within the above range, corrosion and excessive etching of the metal to be polished are suppressed, and the risk of expansion and rupture of the filling container due to gas generated by the self-decomposition of hydrogen peroxide is reduced.

[0035] In this specification, the hydrogen peroxide concentration of the colloidal silica is measured by the measurement method described in the examples described later.

[0036] The colloidal silica of the present invention contains silica particles. The content of silica particles in the colloidal silica is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, based on 100% by mass of the colloidal silica. The content of silica in the colloidal silica is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, based on 100% by mass of the colloidal silica. When the lower limit of the content of silica particles in the colloidal silica is within the above range, the polishing performance when the colloidal silica is used as an abrasive is further improved. When the upper limit of the content of silica particles in the colloidal silica is within the above range, the dispersion stability of the silica particles is further improved.

[0037] In this specification, the content of silica particles in colloidal silica can be calculated from the following formula by drying 10.0 g of colloidal silica on a hot plate at 150° C., then removing moisture by heat treatment at 800° C. for 1 hour, and defining the amount of solid content thus obtained as Wg. Content of silica particles in colloidal silica [%] = (W ÷ 10.0) × 100

[0038] The average primary particle diameter of the silica particles contained in the colloidal silica of the present invention is preferably 100 nm or less, more preferably 80 nm or less, and even more preferably 50 nm or less. When the upper limit of the average primary particle diameter is in the above range, the flatness is further improved when polished using the colloidal silica of the present invention. In addition, the average primary particle diameter of the silica particles is preferably 5 nm or more, more preferably 10 nm or more, and even more preferably 20 nm or more. When the lower limit of the average primary particle diameter of the silica particles is in the above range, the storage stability of the colloidal silica is further improved. The average primary particle diameter of the silica particles is measured by the following measurement method.

[0039] (Method of measuring average primary particle size) Colloidal silica is pre-dried on a hot plate and then heat-treated at 800°C for 1 hour to prepare a measurement sample. The BET specific surface area is measured using the prepared measurement sample. The true specific gravity of silica is 2.2, and the formula is 2727 / BET specific surface area (m2 / g) is converted to the average primary particle size (nm) of the silica particles in the colloidal silica.

[0040] The average secondary particle diameter of the silica particles contained in the colloidal silica of the present invention is preferably 200 nm or less, more preferably 150 nm or less, even more preferably 110 nm or less, and particularly preferably 80 nm or less. When the upper limit of the average secondary particle diameter is in the above range, the flatness is further improved when polishing is performed using the colloidal silica of the present invention. In addition, the lower limit of the average secondary particle diameter is not particularly limited, and is preferably 5 nm or more, more preferably 10 nm or more, even more preferably 15 nm or more, and particularly preferably 20 nm or more. When the lower limit of the average secondary particle diameter is in the above range, the polishing performance is further improved when the colloidal silica is used as an abrasive. The average secondary particle diameter of the silica particles is measured by the following measurement method.

[0041] (Method for measuring average secondary particle size) As a sample for measuring the average secondary particle size, colloidal silica is added to a 0.3% by mass citric acid aqueous solution and homogenized to a silica concentration of 0.8% by mass. The average secondary particle size (nm) is measured using the measurement sample by dynamic light scattering (Otsuka Electronics Co., Ltd. "ELSZ-2000S").

[0042] The pH of the colloidal silica of the present invention may be appropriately set according to the use of the colloidal silica, and is not particularly limited, but is preferably 2.0 or more, more preferably 3.0 or more. The pH is preferably 11.0 or less, more preferably 10.0 or less. By setting the lower limit of the pH in the above range, the long-term dispersion stability of the silica particles of the colloidal silica is further improved. By setting the upper limit of the pH in the above range, the long-term dispersion stability of the colloidal silica is further improved.

[0043] The colloidal silica of the present invention preferably contains 1 ppm or less of metal impurities such as sodium, potassium, iron, aluminum, calcium, magnesium, titanium, nickel, chromium, copper, zinc, lead, silver, manganese, cobalt, etc. By containing 1 ppm or less of metal impurities, the colloidal silica can be suitably used for polishing electronic materials, etc.

[0044] The colloidal silica of the present invention can be used as an abrasive (CMP) for semiconductor devices such as semiconductor wafers. In addition, it can be used as a property improver in the fields of paper, fiber, steel, etc., and can also be used as an additive for fillers, external toner additives, etc. by drying to form a powder.

[0045] 2. Manufacturing method of colloidal silica The method for producing colloidal silica of the present invention includes (I) a step I of adding a silane coupling agent having a mercapto group to colloidal silica to perform a modification treatment, (II) a step II of adding hydrogen peroxide to the modified colloidal silica to oxidize the mercapto groups on the silica particle surface and convert them to sulfo groups, and (III) a step III of heating the colloidal silica to which the hydrogen peroxide has been added at a temperature of 80° C. or higher for 15 hours or more, wherein the amount of the silane coupling agent having a mercapto group added is 25.00 to 400.00 μmol / g per 1 g of silica particles, and the amount of the hydrogen peroxide added is 3.30 mol / mol or more per 1 mol of the silane coupling agent having a mercapto group added. The method for producing colloidal silica of the present invention has the above-mentioned configuration, and thus can suitably produce the sulfonic acid-modified colloidal silica of the present invention described above.

[0046] Each step of the production method of the present invention will be described in detail below.

[0047] (Process I) Step I is a step of adding a silane coupling agent having a mercapto group to colloidal silica to perform a modification treatment.

[0048] In the above step I, the temperature of the colloidal silica is not particularly limited, and is preferably 5 to 100° C., and more preferably 20 to 80° C. When the lower limit of the temperature of the colloidal silica is within the above range, aggregation of silica particles during modification with sulfonic acid groups is further suppressed. When the upper limit of the temperature of the colloidal silica is within the above range, evaporation of the solvent is further suppressed.

[0049] In the production method of the present invention, a silane coupling agent having a mercapto group is added to colloidal silica to perform a modification treatment. That is, the modification treatment in step I is a modification treatment for converting the functional groups of the silica particles into sulfonic acid groups.

[0050] The raw colloidal silica is not limited as long as it has silanol groups on the surface, but considering that it does not contain metal impurities that are diffusible in semiconductors or corrosive ions such as chlorine, colloidal silica obtained by hydrolysis and condensation using hydrolyzable silicon compounds (e.g., alkoxysilanes or their derivatives) as raw materials is preferred. These silicon compounds can be used alone or in combination of two or more.

[0051] In the present invention, the silicon compound is preferably an alkoxysilane represented by the following general formula (1) or a derivative thereof. Si(OR)4(1) [In the formula, R is an alkyl group, preferably a lower alkyl group having 1 to 8 carbon atoms, and more preferably a lower alkyl group having 1 to 4 carbon atoms.]

[0052] Examples of the R include methyl, ethyl, propyl, isopropyl, butyl, pentyl, and hexyl groups, and R is preferably tetramethoxysilane, R is methyl, R is tetraethoxysilane, and R is isopropyl. Examples of the derivatives of alkoxysilane include low condensates obtained by partially hydrolyzing alkoxysilane. In the present invention, it is preferable to use tetramethoxysilane because it is easy to control the hydrolysis rate, it is easy to obtain single nm fine silica particles, and there is little residual unreacted material.

[0053] The silicon compound is hydrolyzed and condensed in a reaction solvent to form colloidal silica. Water or an organic solvent containing water is used as the reaction solvent.

[0054] Examples of the organic solvent include hydrophilic organic solvents such as alcohols, such as methanol, ethanol, isopropanol, n-butanol, t-butanol, pentanol, ethylene glycol, propylene glycol, and 1,4-butanediol, and ketones, such as acetone and methyl ethyl ketone.

[0055] The amount of water added to the organic solvent is not particularly limited as long as the amount required for hydrolysis of the silicon compound is present, and is preferably about 2 to 200 moles per mole of the silicon compound.

[0056] It is preferable to add a basic catalyst to the reaction solvent to adjust the reaction solvent to alkaline. As a result, the reaction solvent is adjusted to preferably pH 8 to 11, more preferably pH 8.5 to 10.5, and colloidal silica can be formed quickly. The type of basic catalyst is not particularly limited. As the basic catalyst, an organic base catalyst that does not contain a metal component is preferable in terms of avoiding the inclusion of metal impurities, and among them, an organic base catalyst containing nitrogen is preferable. Examples of such organic base catalysts include ethylenediamine, diethylenetriamine, triethylenetetraamine, ammonia, urea, monoethanolamine, diethanolamine, triethanolamine, tetramethylammonium hydroxide (TMAH), tetramethylguanidine, 3-ethoxypropylamine, dipropylamine, and triethylamine. These can be used alone or in combination of two or more. Ammonia is preferable in terms of excellent catalytic action and high volatility, which makes it easy to remove in a subsequent process. From the viewpoint of increasing the true specific gravity of the silica particles, it is preferable to select an organic base catalyst having a boiling point of 90°C or higher so that the catalyst is unlikely to volatilize even at high reaction temperatures, and at least one selected from tetramethylammonium hydroxide and 3-ethoxypropylamine is more preferable.

[0057] In the present invention, a silane coupling agent having a mercapto group, which can be chemically converted to a sulfonic acid group, is added to colloidal silica, and then the mercapto group is converted to a sulfonic acid group, thereby modifying the colloidal silica with sulfonic acid. This is based on the fact that a silane coupling agent having a sulfonic acid group is difficult to obtain, since the sulfonic acid group has high acidity and is prone to hydrolysis.

[0058] Examples of silane coupling agents having a mercapto group include 3-mercaptopropyltrimethoxysilane, 2-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane.

[0059] The above mercapto group-containing silane coupling agents can be used alone or in combination of two or more.

[0060] When adding a coupling agent to colloidal silica, it is preferable to include a hydrophilic organic solvent in the colloidal silica, taking into consideration the solubility of the coupling agent. In this regard, when colloidal silica is obtained by the Stöber method, in which alkoxysilane is hydrolyzed and condensed in an alcohol-water solvent using a basic catalyst, the alcohol is contained in the reaction solution, so there is no need to add a hydrophilic organic solvent. In this case, the hydrophilic organic solvent is more preferably 5% by mass or more relative to the water in the colloidal silica, so this can be adjusted by concentrating the reaction solution as necessary.

[0061] On the other hand, when adding silane coupling agent to water-dispersed colloidal silica, add hydrophilic solvent to the extent that silane coupling agent dissolves.As hydrophilic organic solvent, for example, alcohol such as isopropyl alcohol, ethanol and methanol can be mentioned, among which, it is preferable to use the same kind of alcohol as that produced by hydrolysis of silicon compound.This is because by using the same kind of alcohol as that produced by hydrolysis of silicon compound, it is possible to easily recover and reuse solvent.

[0062] The amount of the silane coupling agent having the mercapto group is 25.00 to 400.00 μmol / g per 1 g of silica particles. If the amount of the silane coupling agent is less than 25.00 μmol / g, the polishing removal rate of metal using the produced colloidal silica decreases. If the amount of the silane coupling agent is more than 400.00 μmol / g, the amount of abrasive grains remaining on the polished metal surface after polishing and cleaning using the produced colloidal silica increases. The lower limit of the amount of the silane coupling agent is preferably 30.00 μmol / g or more, more preferably 35.00 μmol / g or more. The upper limit of the amount of the silane coupling agent is preferably 380.00 μmol / g or less, more preferably 360.00 μmol / g or less.

[0063] The reaction time when the silane coupling agent is added is not limited, but is preferably 5 minutes to 10 hours, more preferably 10 minutes to 2 hours, and even more preferably 15 minutes to 1 hour.

[0064] The pH of the colloidal silica when the silane coupling agent is added is not limited, but is preferably from 7 to 11. By setting the upper limit of the pH in the above range, the silane coupling agent becomes more likely to react with the silica surface, and self-condensation of the silane coupling agents themselves is further suppressed.

[0065] In the above-described step I, a silane coupling agent having a mercapto group is added to the colloidal silica, and the colloidal silica is modified.

[0066] (Process II) Step II is a step in which hydrogen peroxide is added to the colloidal silica that has been subjected to the above-mentioned modification treatment to oxidize the mercapto groups on the surface of the silica particles and convert them to sulfo groups.

[0067] In step II, hydrogen peroxide is added to a silane coupling agent having a mercapto group. The hydrogen peroxide acts as an oxidizing agent, and the mercapto group modified on the colloidal silica is oxidized.

[0068] The amount of hydrogen peroxide added is 3.30 mol / mol or more per 1 mol of the silane coupling agent having a mercapto group. If the amount of hydrogen peroxide added is less than 3.30 mol / mol, the polishing removal rate of metal using the produced colloidal silica changes significantly over time. The amount of hydrogen peroxide added is preferably 3.40 mol / mol or more, more preferably 3.50 mol / mol or more. The amount of hydrogen peroxide added is preferably 6.00 mol / mol or less, more preferably 5.70 mol / mol or less. By setting the upper limit of the amount of hydrogen peroxide added within the above range, corrosion and excessive etching of the metal to be polished are suppressed when the produced colloidal silica is used to polish the metal, and the risk of expansion and rupture of the filling container due to gas generated by the self-decomposition of hydrogen peroxide is reduced.

[0069] By the above-described step II, the mercapto groups on the surface of the silica particles of the modified colloidal silica can be oxidized and converted to sulfo groups.

[0070] (Process III) Step III is a step of heating the colloidal silica to which the hydrogen peroxide has been added at a temperature of 80° C. or higher for 15 hours or longer.

[0071] In the above step III, the temperature at which the colloidal silica is heated is 80°C or higher. If the temperature is lower than 80°C, the polishing removal rate of metal using the produced colloidal silica will change significantly over time. The above temperature is preferably 85°C or higher, more preferably 90°C or higher, and even more preferably 95°C or higher. The upper limit of the above temperature is not particularly limited, and may be 100°C or lower.

[0072] In the above step III, the heating time for heating the colloidal silica is 15 hours or more. If the heating time is less than 15 hours, the rate of polishing and removing metal using the produced colloidal silica will change significantly over time. The heating time is preferably 16 hours or more, more preferably 18 hours or more, and even more preferably 19 hours or more. The upper limit of the heating time is not particularly limited, and may be 50 hours or less, 40 hours or less, or 30 hours or less.

[0073] The sulfonic acid-modified colloidal silica of the present invention can be produced by the step III described above.

[0074] Since the sulfonic acid-modified colloidal silica obtained according to the above-mentioned production method may contain a solvent other than water, in order to further improve the long-term storage stability of the colloidal silica, the dispersion medium mainly consisting of the reaction solvent may be replaced with water as necessary. This water replacement may be carried out after adding the silane coupling agent in step I and before adding hydrogen peroxide in step II.

[0075] The method of replacing the dispersion medium mainly composed of the reaction solvent with water is not particularly limited, and for example, a method of dropping a certain amount of water while heating the colloidal silica can be mentioned. In addition, a method of separating the colloidal silica from the dispersion medium mainly composed of the reaction solvent by precipitation / separation, centrifugation, etc., and then dispersing it in water can be mentioned.

[0076] The sulfonic acid-modified colloidal silica of the present invention can be produced by the production method having the steps described above. EXAMPLES

[0077] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these.

[0078] Example 1 (Production of sulfonic acid modified colloidal silica) A mixture of 1522.2 parts by mass of tetramethoxysilane and 413.0 parts by mass of methanol was dropped into 15171 parts by mass of a mixture of 2212.7 parts by mass of pure water, 567.3 parts by mass of 26% by mass ammonia water, and 12391 parts by mass of methanol over a period of 25 minutes while maintaining the liquid temperature at 20°C, to prepare a silica sol with water and methanol as a dispersion medium. The silica sol was heated and concentrated under normal pressure to obtain 3000 parts by mass of a concentrated liquid with a silica particle content of 20% by mass. 3-mercaptopropyltrimethoxysilane was added to the concentrated liquid as a silane coupling agent, and the mixture was refluxed at the boiling point to perform thermal aging. Next, while adding pure water to keep the volume constant, methanol and ammonia were replaced with water, and when the pH became 8 or less, the liquid temperature of the silica sol was temporarily lowered to room temperature. Next, 35% by mass of hydrogen peroxide water was added, heated again, and cooled to room temperature to obtain a sulfonic acid-modified colloidal silica. The amount of silane coupling agent added per 1 g of silica particles, the amount of hydrogen peroxide added per 1 mol of silane coupling agent, the heating temperature after adding hydrogen peroxide, and the heating time after adding hydrogen peroxide were adjusted as shown in Table 1.

[0079] Examples 2 to 9, Comparative Examples 1 to 5 A sulfonic acid-modified colloidal silica was produced in the same manner as in Example 1, except that the production conditions were set as shown in Table 1 and colloidal silica having the properties shown in Table 1 was prepared.

[0080] Example 10 (Production of sulfonic acid modified colloidal silica) A mixture of 1522.2 parts by mass of tetramethoxysilane and 413.0 parts by mass of methanol was dropped into 14498 parts by mass of a mixture of 787.9 parts by mass of pure water, 786.0 parts by mass of 26% by mass ammonia water, and 12924 parts by mass of methanol over a period of 55 minutes while maintaining the liquid temperature at 35°C, to prepare a silica sol with water and methanol as a dispersion medium. The silica sol was heated and concentrated under normal pressure to obtain 3000 parts by mass of a concentrated liquid with a silica particle content of 20% by mass. 3-mercaptopropyltrimethoxysilane was added to the concentrated liquid as a silane coupling agent, and the mixture was refluxed at the boiling point to perform thermal aging. Next, while adding pure water to keep the volume constant, methanol and ammonia were replaced with water, and when the pH became 8 or less, the liquid temperature of the silica sol was once lowered to room temperature. Next, 35% by mass of hydrogen peroxide water was added, heated again, and cooled to room temperature to obtain a sulfonic acid-modified colloidal silica. The amount of silane coupling agent added per 1 g of silica particles, the amount of hydrogen peroxide added per 1 mol of silane coupling agent, the heating temperature after adding hydrogen peroxide, and the heating time after adding hydrogen peroxide were adjusted as shown in Table 1.

[0081] Example 11 (Production of sulfonic acid modified colloidal silica) A mixture of 1,522.8 parts by mass of tetramethoxysilane and 389.8 parts by mass of methanol was dropped into 14,449 parts by mass of a mixture of 1,344.8 parts by mass of pure water, 1,111.7 parts by mass of 26% by mass ammonia water, and 11,992 parts by mass of methanol over a period of 30 minutes while maintaining the liquid temperature at 20°C, to prepare a silica sol with water and methanol as a dispersion medium. The silica sol was heated and concentrated under normal pressure to obtain 3,000 parts by mass of a concentrated liquid with a silica particle content of 20% by mass. 3-mercaptopropyltrimethoxysilane was added to the concentrated liquid as a silane coupling agent, and the mixture was refluxed at the boiling point to perform thermal aging. Next, while adding pure water to keep the volume constant, methanol and ammonia were replaced with water, and when the pH became 8 or less, the liquid temperature of the silica sol was temporarily lowered to room temperature. Next, 35% by mass of hydrogen peroxide water was added, heated again, and cooled to room temperature to obtain sulfonic acid-modified colloidal silica. The amount of silane coupling agent added per 1 g of silica particles, the amount of hydrogen peroxide added per 1 mol of silane coupling agent, the heating temperature after adding hydrogen peroxide, and the heating time after adding hydrogen peroxide were adjusted as shown in Table 1.

[0082] Evaluation method The colloidal silica of the examples and comparative examples obtained as described above were evaluated by the following methods.

[0083] (Method of confirming the presence or absence of sulfo groups on particle surfaces using X-ray photoelectron spectroscopy (XPS)) The colloidal silica solution was centrifuged at 77,400 G, 5°C, and for 90 minutes. The resulting precipitate was dried at 60°C for 12 hours, after which the silica was crushed and dried at 60°C under reduced pressure of -0.1 MPa or less gauge pressure for 2 hours to prepare a measurement sample. Using the measurement sample, the presence or absence of sulfo groups on the silica particle surface was confirmed by X-ray photoelectron spectroscopy under the following conditions. Measuring equipment: Shimadzu AXIS-NOVA Irradiation X-ray: Al-Kα (15kV, 10mA) Analytical X-ray spot diameter: 300 x 700 μm

[0084] In addition, a precision analysis was performed near the S2s orbital (binding energy 230 eV) using a value standardized with the Si2p binding energy set at 103.60 eV, and the peak at a binding energy of 233 eV was determined to be a peak derived from a sulfo group. The presence or absence of a sulfo group was confirmed based on whether or not the peak derived from the sulfo group was detected.

[0085] (Cu ion adsorption amount of silica particles) The amount of Cu ions adsorbed on the silica particles was measured by the following procedure. 1. 0.1M HCl was added to 10 g of colloidal silica to adjust the pH to the range of 2.5 to 2.9. 2. A 0.5M aqueous solution of copper (II) sulfate was added to the colloidal silica so that the amount of Cu (II) ions added per 1 g of silica was 2400 μmol, and the solution was then allowed to stand for 5 minutes. 3. The solution was centrifuged at 77,400 G, 5° C., and 90 minutes, and the resulting precipitate was dried at 60° C. for 12 hours. 4. The obtained dried powder was pulverized in an agate mortar, 20 mL of ultrapure water was added, and the mixture was ultrasonically cleaned for 30 seconds. 5. After ultrasonic cleaning, the solution was filtered under reduced pressure using a membrane filter with a pore size of 1 μm, and the silica solid content was recovered on the membrane filter. 6. The silica solid collected on the membrane filter was dried at 60°C for 12 hours. The steps 7.4 to 7.6 were repeated a total of three times to wash off Cu ions that were not adsorbed on the silica particle surface. 8. The silica solids were further dried at 60°C for 12 hours. 9. 5 mL of 38% hydrofluoric acid was added to 1 g of silica solids, and the mixture was left to stand for 60 minutes to dissolve the silica. Ultrapure water was then added to the solution to make up to 100 mL. 10. The Cu ion concentration of the obtained solution was measured by ICP-AES using the absolute calibration curve method. From the obtained Cu ion concentration, the amount of Cu ion adsorption per 1 g of silica was calculated using the following formula. Cu ion adsorption amount (μmol / 1g of silica) = Cu ion concentration (ppm) / 63.55 (g / mol)

[0086] (S content of silica particles) The S content of the silica particles was measured by the following procedure. 1. The colloidal silica was centrifuged at 77,400 G, 5° C., and 90 minutes. The resulting precipitate was dried at 60° C. for 12 hours. 2. The obtained dried powder was pulverized in an agate mortar, 20 mL of ultrapure water was added, and the mixture was ultrasonically cleaned for 30 seconds. 3. After ultrasonic cleaning, the solution was filtered under reduced pressure using a membrane filter with a pore size of 1 μm, and the silica solid content was recovered on the membrane filter. 4. The silica solids collected on the membrane filter were dried at 60°C for 24 hours. 5. 5 mL of 38% hydrofluoric acid was added to 1 g of silica solids, and the mixture was left to stand for 60 minutes to dissolve the silica. Ultrapure water was then added to the solution to make up to 100 mL. 6. The S concentration of the obtained solution was measured by ICP-AES using the absolute calibration curve method. From the obtained S concentration, the S content per 1 g of silica was calculated using the following formula. S content (μmol / g) = S concentration (ppm) / 32.07 (g / mol)

[0087] (Cu ion adsorption amount / S content) The Cu ion adsorption amount / S content was calculated from the values ​​of the Cu ion adsorption amount (μmol / g) and the S content (μmol / g) measured by the above-mentioned measurement method according to the following formula. [Cu ion adsorption amount / S content]=Cu ion adsorption amount (μmol / g) / S content (μmol / g)

[0088] (Change in Cu ion adsorption amount of silica particles over time) The colloidal silica of the Examples and Comparative Examples was allowed to stand for 3 months at 25° C. The amount of Cu ions adsorbed (μmol / g) on ​​the silica particles before and after standing was measured, and the rate of change over time in the amount of Cu ions adsorbed on the silica particles was calculated using the following formula. (Change rate of Cu ion adsorption amount of silica particles over time) = Cu ion adsorption amount after standing (μmol / g) / Cu ion adsorption amount before standing (μmol / g)

[0089] (Measurement of hydrogen peroxide concentration in colloidal silica) The hydrogen peroxide concentration of the colloidal silica was measured by the following procedure. 1. 48 g of ultrapure water was added to 2.00 g of colloidal silica to prepare a diluted solution. 2. 5 mL of 47% sulfuric acid was added to the diluted solution, and 10 mL of 0.1 g / mL potassium iodide aqueous solution was added. After addition, the mixture was stirred for 900 seconds using a stirrer in a light-shielded environment. 3. After stirring, potentiometric titration was performed using the following measuring equipment and titration reagent, and the amount of 0.01 mol / L sodium thiosulfate solution added at the end point of the titration was determined. Measuring equipment: Automatic potentiometric titrator AT-710 manufactured by Kyoto Electronics Industry Titration reagent: 0.01 mol / L sodium thiosulfate aqueous solution 4. The amount of 0.01 mol / L sodium thiosulfate solution added at the end point of the titration was T mL, and the molecular weight of hydrogen peroxide was 34.02, so the hydrogen peroxide concentration in the colloidal silica was calculated using the following formula. Colloidal silica hydrogen peroxide concentration [ppm] =0.01×T×(1 / 1000)×(1 / 2)×34.02×(1000000 / 2.00)

[0090] (Silica particle content) The content of silica particles in the colloidal silica was calculated from the following formula, where 10.0 g of colloidal silica was dried on a hot plate at 150°C, then heated at 800°C for 1 hour to remove moisture, and the amount of solid content obtained was taken as Wg. Content of silica particles in colloidal silica [%] = (W ÷ 10.0) × 100

[0091] (Average primary particle size) Colloidal silica was pre-dried on a hot plate and then heat-treated at 800°C for 1 hour to prepare a measurement sample. The BET specific surface area was measured using the prepared measurement sample. The true specific gravity of silica was 2.2, and the formula was 2727 / BET specific surface area (m 2 / g) was converted to the average primary particle size (nm) of the silica particles in the colloidal silica.

[0092] (Average secondary particle size) Colloidal silica was added to a 0.3% by mass aqueous solution of citric acid to prepare a homogenized solution with a silica concentration of 0.8% by mass. The average secondary particle diameter (nm) of the measurement sample was measured by dynamic light scattering (Otsuka Electronics Co., Ltd., "ELSZ-2000S").

[0093] (Metal impurity content) The content of metal impurities was measured using an atomic absorption spectrometer. The sum of the contents of sodium, potassium, iron, aluminum, calcium, magnesium, titanium, nickel, chromium, copper, zinc, lead, silver, manganese, and cobalt in the colloidal silica was defined as the content of metal impurities.

[0094] (Cu polishing speed) The colloidal silica of each of the examples and comparative examples was adjusted to a silica particle concentration of 3 wt %, and then the oxidizing agent concentration and pH were adjusted as follows, and the resulting solution was subjected to a polishing test. Oxidizer concentration: Hydrogen peroxide concentration 0.25 wt% (by weight of polishing slurry) pH adjustment: pH 2 (using 60% perchloric acid) Polishing test conditions Polishing machine: NF-300CMP manufactured by Nanofactor Co., Ltd. Polishing target: 3cm x 3cm square PVD-Cu film wafer (Cu film thickness 1μm) Polishing pad: Nitta Haas IC1000TMPad Slurry supply rate: 50mL / min Head rotation speed: 32 rpm Platen rotation speed: 32 rpm Polishing pressure: Cu film, 1.5psi Polishing time: Cu film, 1min Film thickness measuring device: Cu film, electrical resistance type film thickness measuring device

[0095] (Change in Cu polishing speed over time when slurry is left stationary) The colloidal silica of each of the examples and comparative examples was allowed to stand for 3 months at 25° C. The Cu polishing rate before and after standing was measured, and the rate of change over time in the Cu polishing rate during storage of the slurry was calculated using the following formula. Rate of change over time in Cu polishing rate when the slurry is left standing (%) = (Cu polishing rate after standing (Å / min) - Cu polishing rate before standing (Å / min)) × 100 ÷ Cu polishing rate before standing (Å / min)

[0096] (Amount of particles remaining on the polished surface after polishing and cleaning) The polished PVD-Cu coated wafers were cleaned by scrubbing with a PVA roll brush in the scrubbing section built into the cleaning and drying equipment MAT ZAB-8S1M under the following conditions: To hold the wafer in place, a jig was used with a frame made of glass epoxy resin and a wafer fixing part made of polyurethane. Brush: AION SCL BRUSH ROLLER 48 (40 / 26) x 224 mm Scrub time: 1min Brush rotation speed: 200 rpm -Spin speed of wafer fixing part: 50 rpm After scrubbing, ultrapure water was poured onto the polished substrate at 750mL / min for 1 minute, and then the substrate was processed in the spin dryer built into the above equipment at 1800rpm for 20 seconds. After drying, the number of particles remaining on the polished surface of the wafer was measured using Shimadzu Corporation's SPM-9700HT.

[0097] The results are shown in Table 1.

[0098] [Table 1]

Claims

1. A sulfonic acid modified colloidal silica containing silica particles, (1) The silica particles have a surface modified with a sulfonic acid group, (2) the Cu ion adsorption amount of the silica particles is 5.00 to 110.00 μmol / g; (3) The ratio of the Cu ion adsorption amount to the S content of the silica particles (Cu ion adsorption amount (μmol / g) / S content (μmol / g)) is 0.50 or more; (4) The rate of change over time in the amount of Cu ion adsorption of the silica particles is 1.30 or less, as measured by the following measurement method:

1. A sulfonic acid-modified colloidal silica comprising: [Method for measuring rate of change over time in amount of Cu ions adsorbed on silica particles] The sulfonic acid-modified colloidal silica is allowed to stand for 3 months at 25° C. The Cu ion adsorption amount (μmol / g) of the silica particles before and after standing is measured, and the rate of change over time in the Cu ion adsorption amount of the silica particles is calculated using the following formula. (Change rate of Cu ion adsorption amount of silica particles over time) = Cu ion adsorption amount after standing (μmol / g) / Cu ion adsorption amount before standing (μmol / g)

2. 2. The sulfonic acid modified colloidal silica according to claim 1, wherein the silica particles have a Cu ion adsorption amount of 8.00 to 105.00 μmol / g.

3. 2. The sulfonic acid modified colloidal silica according to claim 1, wherein the silica particles have an S content of 10.00 to 200.00 μmol / g.

4. 2. The sulfonic acid modified colloidal silica according to claim 1, wherein a ratio of the Cu ion adsorption amount to the S content is 0.55 or more.

5. 2. The sulfonic acid modified colloidal silica according to claim 1, having a hydrogen peroxide concentration of 1,000 ppm or less.

6. A method for producing sulfonic acid-modified colloidal silica, comprising the steps of: (I) Step I of modifying colloidal silica by adding a silane coupling agent having a mercapto group; (II) adding hydrogen peroxide to the modified colloidal silica to oxidize the mercapto groups on the silica particle surface and convert them into sulfo groups; and (III) a step III of heating the colloidal silica to which hydrogen peroxide has been added at a temperature of 80° C. or higher for 15 hours or longer; The amount of the silane coupling agent having a mercapto group added is 25.00 to 400.00 μmol / g per 1 g of silica particles, The amount of hydrogen peroxide added is 3.30 mol / mol or more per 1 mol of the silane coupling agent having a mercapto group. A manufacturing method comprising the steps of:

7. The manufacturing method according to claim 6, wherein the silane coupling agent having a mercapto group is at least one selected from the group consisting of 3-mercaptopropyltrimethoxysilane, 2-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane.