Abrasive material slurry

Abstract

The abrasive slurry of the present invention comprises cerium oxide abrasive particles, magnesium hydroxide abrasive particles, a dispersant and a solvent, wherein the average particle size of the cerium oxide abrasive particles and the magnesium hydroxide abrasive particles is 0.01 μm or more and 0.5 μm or less.

Description

Technical Field

[0001] This invention relates to abrasive slurries. Background Technology

[0002] With the increasing density and precision of semiconductor devices, CMP (Chemical Mechanical Polishing) has been developed as a technique to planarize the surface of thin films formed by methods such as CVD (Chemical Vapor Deposition) in the semiconductor wafer manufacturing process.

[0003] The efficiency of CMP (Continuous Metallurgical Processing) is greatly affected by the selection of the abrasive slurry and the abrasive pad. In particular, the selection of the abrasive slurry is the main reason for the significant impact on the efficiency of CMP. The abrasive slurry used in CMP contains abrasive particles such as silica (SiO2) and cerium oxide (CeO2). For example, Patent Document 1 discloses an abrasive composition containing cerium oxide microparticles as abrasives. The abrasive composition disclosed in Patent Document 1 contains cerium oxide microparticles with a purity of 99% by mass or more (with an average particle size (D50) of 0.01 μm to 1.0 μm), a chelating agent, a dispersant with polyacrylic acid or polymethacrylic acid groups, and elements such as Mg, Al, K, and C (with a content of less than 30 ppm).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2001 / 080296 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, the abrasive material composition disclosed in Patent Document 1 contains very fine cerium oxide particles as abrasive grains, resulting in a decrease in the grinding rate over time. Furthermore, maintaining the grinding rate during the grinding process increases the management costs of the abrasive material.

[0009] In view of the above-mentioned problems, the present invention provides an abrasive slurry that can suppress the decrease in grinding rate caused by time changes even when the abrasive grains are fine.

[0010] Methods for solving problems

[0011] The abrasive slurry of the present invention, which was completed to solve the above-mentioned problems, is characterized by having cerium oxide abrasive particles, magnesium hydroxide abrasive particles, a dispersant and a solvent, wherein the average particle size of the cerium oxide abrasive particles and the magnesium hydroxide abrasive particles is 0.01 μm or more and 0.5 μm or less.

[0012] The abrasive slurry of the present invention contains cerium oxide abrasive particles, magnesium hydroxide abrasive particles, a dispersant, and a solvent, thereby suppressing the decrease in grinding rate caused by time changes even when the average particle size of the cerium oxide abrasive particles and the magnesium hydroxide abrasive particles is fine, ranging from 0.01 μm to 0.5 μm.

[0013] As cerium oxide-based abrasive grains, cerium oxide abrasive grains are preferred. Specifically, examples include cerium (IV) oxide and cerium (III) oxide, with cerium (IV) oxide being preferred from the viewpoint of material stability. Furthermore, cerium oxide-based abrasive grains can be composed of a single type of cerium oxide particle or a mixture of two or more types of cerium oxide particles. It should be noted that cerium oxide-based abrasive grains may also contain other elements such as F (fluorine), Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. In particular, they may also contain other elements such as F (fluorine), La, Pr, and Nd.

[0014] In addition to the cerium oxide-based abrasive grains described above, the abrasive slurry of the present invention also contains magnesium hydroxide-based abrasive grains. It is speculated that magnesium hydroxide-based abrasive grains, compared to cerium oxide-based abrasive grains, adsorb the abrasive debris (fine powder after grinding) from the workpiece being ground, thus inhibiting the reduction in grinding performance and functioning as an additive. Magnesium hydroxide-based abrasive grains are preferably, for example, magnesium hydroxide abrasive grains. Furthermore, the magnesium hydroxide-based abrasive grains can be a single type of magnesium hydroxide particle or a mixture of two or more types of magnesium hydroxide particles. It should be noted that the magnesium hydroxide-based abrasive grains may also contain other elements such as Ca, Si, Fe, Al, S, and B. In particular, they may also contain other elements such as Ca and Si.

[0015] In addition to the cerium oxide-based and magnesium hydroxide-based abrasive grains described above, the abrasive slurry of the present invention also contains the solvent and dispersant described later. If the cerium oxide-based abrasive grains are fine, they tend to agglomerate; therefore, by including the dispersant, the dispersibility with the solvent is improved.

[0016] For the abrasive slurry of the present invention, from the viewpoint of suppressing the decrease in grinding rate and reducing the surface roughness Ra of the grinding surface, it is preferable that the average particle size of the cerium oxide-based abrasive grains and the magnesium hydroxide-based abrasive grains is 0.01 μm or more and 0.5 μm or less. Furthermore, it is more preferable that the average particle size of the cerium oxide-based abrasive grains and the magnesium hydroxide-based abrasive grains is 0.05 μm or more and 0.2 μm or less.

[0017] The average particle size of cerium oxide abrasive and magnesium hydroxide abrasive is determined by particle size distribution measurement method using dynamic light scattering (D50), and can be measured as follows.

[0018] Dynamic light scattering method refers to a method in which the intensity of light scattering from a group of particles undergoing Brownian motion is measured by irradiating a solution such as a suspension with light such as a laser, and the particle size and distribution are determined based on the time variation of this intensity. Specifically, the particle size distribution is evaluated using a Zeta potential-particle size-molecular weight measurement system (manufactured by Otsuka Electronics Co., Ltd.: ELSZ-2000ZS) according to JIS Z8828:2019 "Particle size analysis - Dynamic light scattering method". The grinding material slurry of the present invention, diluted with pure water to a solid component concentration of 0.005% to 0.1% by mass, is used as the test sample. This solid component concentration can be calculated as follows: First, 5g of the grinding material slurry of the present invention is collected and heated at 180°C for 60 minutes under atmospheric atmosphere, and the mass (Xg) of the obtained solid component is measured. Then, the solid component concentration can be calculated by calculating Xg (mass of solid component) ÷ 5g (mass of the collected grinding material slurry of the present invention) × 100. Prior to the measurement, the sample was filtered using a filter with a particle trapping capacity of 11 μm or greater, and then ultrasonically treated for 3 minutes using an ultrasonic cleaner (AS ONE: VS-100III). The liquid temperature of the sample was then adjusted to 25°C. It should be noted that the particle size (D50) refers to the median particle size, representing the 50% cumulative value of the cumulative distribution curve.

[0019] Furthermore, from the viewpoint of achieving the objectives of this application, it is preferable that the average particle size of cerium oxide abrasive grains is 0.01 μm or more and 0.5 μm or less, or it can be 0.05 μm or more and 0.2 μm or less.

[0020] Furthermore, from the viewpoint of achieving the objectives of this application, it is preferable that the average particle size of magnesium hydroxide abrasives is 0.01 μm or more and 0.5 μm or less, or it may be 0.05 μm or more and 0.2 μm or less.

[0021] Furthermore, the abrasive slurry of the present invention contains ZrO2 and Al2O3 chips from the media used in the process of pulverizing cerium oxide-based and magnesium hydroxide-based abrasive particles in the manufacturing method of the abrasive slurry of the present invention, as described later. It should be noted that the content of ZrO2 and Al2O3 in the abrasive slurry of the present invention does not affect the grinding performance of the abrasive slurry of the present invention.

[0022] In addition, the abrasive slurry of the present invention is characterized by having a solvent, wherein the solvent comprises water.

[0023] The abrasive slurry of the present invention has high dispersibility with water, therefore pure water can be used as a solvent. Furthermore, as a solvent, pure water, water-soluble organic solvents such as alcohols and ketones, or mixtures thereof, are preferred from the perspective of sufficiently improving the grinding rate; water is more preferred. When the abrasive slurry of the present invention is set to 100% by mass, the solvent content is preferably 60% by mass or more and 99.9% by mass or less, more preferably 80% by mass or more and 90% by mass or less. Typically, when the abrasive slurry of the present invention is set to 100% by mass, the solvent content can be 98% by mass or less, 97% by mass or less, or 95% by mass or less.

[0024] In addition, the grinding material slurry of the present invention is characterized by having a dispersant, wherein the dispersant comprises one or more selected from organic acid alkali metal salts, phosphates, and polymeric dispersants.

[0025] The abrasive slurry of the present invention has a dispersant, which comprises one or more selected from organic acid alkali metal salts, phosphates, and polymeric dispersants, thereby inhibiting the agglomeration of cerium oxide abrasive particles.

[0026] The organic acid-base metal salt preferably contains one or more selected from sodium citrate, sodium gluconate, and sodium tartrate. Furthermore, examples of sodium citrate include monosodium citrate, disodium citrate, and trisodium citrate. Examples of sodium tartrate include monosodium tartrate and disodium tartrate. Sodium tartrate can be an L-form, a D-form, a meso compound, or a mixture thereof. The organic acid-base metal salt can be a hydrate.

[0027] Furthermore, the determination of organic acid and alkali metal salts contained in the abrasive slurry of the present invention is preferably performed using high-performance liquid chromatography (HPLC). Using HPLC, the types and weights of organic acid and alkali metal salts can be determined using known methods. Alternatively, the organic acid and alkali metal salts contained in the abrasive slurry of the present invention can be separated before determination.

[0028] Phosphoric acids include phosphoric acid, condensed phosphoric acid, and their alkali metal salts. Among these, one or more phosphoric acids selected from sodium phosphate, sodium hexametaphosphate, sodium pyrophosphate, sodium tetrapolyphosphate, and sodium hyperpolyphosphate can be listed as alkali metal salts.

[0029] Furthermore, the determination of phosphates contained in the grinding material slurry of the present invention is preferably performed by high-performance liquid chromatography (HPLC). In HPLC, the types and weights of phosphates can be determined using known methods by employing a non-inhibitor anion exchange column. For example, the Shodex non-inhibitor anion exchange column IC I-524A (manufactured by Showa Scientific Co., Ltd.) is an example of a non-inhibitor anion exchange column; by using this column, the phosphates contained in the grinding material slurry of the present invention can be separated and determined.

[0030] Examples of polymeric dispersants include one or more water-soluble organic polymers selected from polyacrylic acid, polycarboxylic acid, polycarboxylate salts, and copolymers thereof. Polyacrylates are particularly preferred as polymeric dispersants, and ammonium polyacrylates are more preferred.

[0031] Furthermore, the abrasive slurry of the present invention is characterized in that, when the abrasive slurry is set to 100% by mass, the content of cerium oxide abrasive particles is 0.5% by mass or more and 40% by mass or less, and the content of magnesium hydroxide abrasive particles is 0.005% by mass or more and 20% by mass or less.

[0032] From the viewpoint of achieving a good grinding rate, it is preferable that the content of cerium oxide-based abrasive particles in the abrasive slurry of the present invention is 0.5% by mass or more and 40% by mass or less. Furthermore, the content of cerium oxide-based abrasive particles is more preferably 3.0% by mass or more and 35.0% by mass or less, even more preferably 4.0% by mass or more and 30.0% by mass or less, particularly preferably 5.0% by mass or more and 25.0% by mass or less, and most preferably 15.0% by mass or more and 25.0% by mass or less. Typically, the content of cerium oxide-based abrasive particles in the abrasive slurry of the present invention can be 40% by mass or less, 38% by mass or less, or 36% by mass or less. It should be noted that the content of cerium oxide-based abrasive particles in the abrasive slurry of the present invention is considered as the total content of total rare earth oxides (TREO), rare earth oxides, and fluorine (F) in the abrasive slurry of the present invention.

[0033] Furthermore, from the viewpoint of suppressing the decrease in grinding rate, it is preferable that the content of magnesium hydroxide-based abrasive particles in the grinding material slurry of the present invention is 0.005% by mass or more and 20% by mass or less. More preferably, the content of magnesium hydroxide-based abrasive particles is 0.05% by mass or more and 5% by mass or less, even more preferably 0.1% by mass or more and 5% by mass or less, and particularly preferably 0.5% by mass or more and 3% by mass or less. Typically, the content of magnesium hydroxide-based abrasive particles in the grinding material slurry of the present invention can be 20% by mass or less, 18% by mass or less, or 16% by mass or less. It should be noted that the content of magnesium hydroxide-based abrasive particles in the grinding material slurry of the present invention is used as the Mg content in the grinding material slurry of the present invention.

[0034] The total rare earth oxide (TREO) and rare earth oxide content were determined using ICP-OES (inductively coupled plasma optical emission spectrometry) or ICP-MS (inductively coupled plasma mass spectrometry), and the fluorine (F) content was determined using the fluoride ion electrode method. Furthermore, the Mg content in the magnesium hydroxide-based abrasive particles was determined using ICP-OES or ICP-MS.

[0035] Specifically, 100 ml of the grinding material slurry of the present invention is placed in a glass beaker and heated and dried at 120°C for 24 hours to obtain the dried grinding material of the present invention. Using this dried grinding material, the content of each component is determined. The total rare earth oxide (TREO) content is determined by oxalate precipitation-calcination-gravimetric method (units: solids: mass %, liquids: g / L). As a pretreatment, the dried grinding material of the present invention is dissolved using nitric acid, perchloric acid, and hydrogen peroxide, and then boiled to prepare the test sample. Alternatively, if the test object is a liquid, dissolution with nitric acid or the like is not required; boiling can be performed directly.

[0036] In addition, regarding the F (fluorine) content, the solid material (abrasive material) to be measured is soluble by alkaline melting-warm water extraction, and the F concentration in the solution is measured by the fluoride ion electrode method, thereby calculating the F content (mass%) in the solid material.

[0037] Furthermore, the Mg content can be calculated as follows. Nitric acid, perchloric acid, and hydrogen peroxide are added to the dried grinding material of the present invention, and the mixture is heated to decompose and become soluble. The Mg concentration can be measured using an ICP-OES apparatus. The added magnesium hydroxide content can be estimated by multiplying it by the hydroxide coefficient. This hydroxide coefficient is Mg(OH)2 / Mg={24.3+(16.0+1.01)×2} / 24.3≈2.40.

[0038] Furthermore, from the viewpoint of improving dispersibility, it is preferable that the content of the dispersant in the grinding material slurry of the present invention is 0.001% by mass or more and 15% by mass or less. More preferably, the content of the dispersant is 0.001% by mass or more and 10% by mass or less, even more preferably 0.005% by mass or more and 5% by mass or less, and particularly preferably 0.5% by mass or more and 3% by mass or less. Typically, the content of the dispersant in the grinding material slurry of the present invention may be 15% by mass or less, 13% by mass or less, or 11% by mass or less.

[0039] The content of dispersant in the grinding material slurry of the present invention is determined by gel permeation chromatography (GPC), liquid chromatography (LC), and liquid chromatography-mass spectrometry (LC-MS).

[0040] It should be noted that, unless otherwise specified in this specification, the contents of cerium oxide abrasive particles, magnesium hydroxide abrasive particles, and dispersant in the grinding material slurry of the present invention are the same as the contents in the grinding slurry before grinding begins.

[0041] Furthermore, the abrasive slurry of the present invention is characterized in that the weight ratio of the magnesium hydroxide-based abrasive grains to the weight of the cerium oxide-based abrasive grains is 1.25 × 10⁻⁶. -4 Above and below 40.

[0042] From the viewpoint of suppressing the decrease in grinding rate, it is preferable that the weight ratio of the magnesium hydroxide-based abrasive grains in the abrasive slurry of the present invention to the weight of the cerium oxide-based abrasive grains is 1.25 × 10⁻⁶. -4 Above and below 40.

[0043] Furthermore, more preferably, the weight ratio of the magnesium hydroxide abrasive particles to the weight of the cerium oxide abrasive particles is 0.001 or more and 1 or less, and even more preferably, the weight ratio is 0.01 or more and 0.1 or less.

[0044] As described above, the weight of cerium oxide-based abrasive particles in the abrasive slurry of the present invention is the total content of total rare earth oxides (TREO), rare earth oxides, and fluorine (F). Furthermore, the weight of magnesium hydroxide-based abrasive particles in the abrasive slurry of the present invention is the magnesium hydroxide content, as described above. Therefore, the weight ratio of the magnesium hydroxide-based abrasive particles to the weight of the cerium oxide-based abrasive particles is calculated. It should be noted that, through SEM-EDX analysis of the cerium oxide-based abrasive particles, when Mg is present in the cerium oxide-based abrasive particles, the average weight ratio of Mg to Ce in 20 cerium oxide-based abrasive particles is calculated based on the results of semi-quantitative analysis. By subtracting the weight of Mg contained in the cerium oxide-based abrasive particles from the overall Mg content of the abrasive slurry of the present invention, the weight of the magnesium hydroxide-based abrasive particles can be calculated.

[0045] Furthermore, the abrasive slurry of the present invention is characterized in that, when the cerium oxide-based abrasive particles are set to 100% by mass, the Ce content of the cerium oxide-based abrasive particles is 100% by mass or less (converted to CeO2), the La content is 40% by mass or less (converted to La2O3), the F content is 10% by mass or less (converted to F), and the Pr content is Pr6O... 11 The conversion is less than 10% by mass, and the Nd content is less than 10% by mass when converted from Nd2O3.

[0046] From the perspective that higher purity of cerium oxide leads to higher grinding speed, cerium oxide-based abrasive grains are preferred as abrasives. On the other hand, when cerium oxide particles contain impurities, from the viewpoint of improving grinding speed, it is also preferable to keep the proportion of rare earth elements other than cerium as such impurities as as low as possible. If the proportion of rare earth elements other than cerium, especially lanthanum (La) and praseodymium (Pr), is low, the grinding speed is further improved.

[0047] From the viewpoint of achieving a good grinding rate, it is preferable that the Ce content in the cerium oxide abrasive grains of the present invention is 100% by mass or less, calculated as CeO2. Furthermore, this Ce content is more preferably 50% by mass or more and 100% by mass or less, even more preferably 60% by mass or more and 100% by mass or less, particularly preferably 70% by mass or more and 100% by mass or less, particularly preferably 80% by mass or more and 100% by mass or less, and particularly preferably 90% by mass or more and 100% by mass or less. Typically, this Ce content can be 100% by mass or less, 98% by mass or less, or 96% by mass or less.

[0048] The La content in the cerium oxide-based abrasive grains of the present invention, converted to La2O3, can be 40% by mass or less. Alternatively, this La content can be 0% by mass or more and 40% by mass or less, 0.1% by mass or more and 40% by mass or less, or 20% by mass or more and 40% by mass or less. Typically, this La content can be 40% by mass or less, 38% by mass or less, or 36% by mass or less.

[0049] The ferrous oxide (F) content in the cerium oxide abrasive grains of the present invention can be 10% by mass or less. Alternatively, the F content can be 0% by mass or more and 10% by mass or less, or 2% by mass or more and 8% by mass or less. Typically, the F content can be 10% by mass or less, 8% by mass or less, or 6% by mass or less.

[0050] The Pr content in the cerium oxide-based abrasive grains of this invention is Pr6O 11The conversion can be less than 10% by mass. Alternatively, the Pr content can be 0% or more and less than 10% by mass, or 0.1% or more and less than 10% by mass, or 2% or more and less than 8% by mass. Typically, the Pr content can be less than 10% by mass, less than 8% by mass, or less than 6% by mass.

[0051] The Nd content in the cerium oxide-based abrasive grains of the present invention, converted to Nd₂O₃, can be 10% by mass or less. Alternatively, this Nd content can be 0% by mass or more and 10% by mass or less, 0.1% by mass or more and 10% by mass or less, or 0.1% by mass or more and 5% by mass or less. Typically, this Nd content can be 10% by mass or less, 8% by mass or less, or 6% by mass or less.

[0052] The contents of the cerium oxide-based abrasive grains of the present invention can be determined as follows. Specifically, the test sample obtained from the above-described total rare earth oxide (TREO) determination can be dissolved in perchloric acid and hydrogen peroxide, and the CeO2 / TREO ratio can be calculated by ICP-OES. Furthermore, the contents of La2O3 / TREO and Pr6O2 / TREO ratios can also be determined. 11 / TREO and Nd2O3 / TREO can also be calculated in the same way.

[0053] Furthermore, the abrasive slurry of the present invention may contain any additives other than the cerium oxide-based abrasives, magnesium hydroxide-based abrasives, dispersants, and solvents described above. These arbitrary additives include dispersants, pH adjusters, viscosity adjusters, chelating agents, oxidants, surfactants, and rust inhibitors. When the abrasive slurry of the present invention is set to 100% by mass, the content of any arbitrary additive is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less. Typically, the content of this arbitrary additive may be 10% by mass or less, 8% by mass or less, or 6% by mass or less.

[0054] The grinding method for grinding a workpiece using the grinding material slurry of the present invention described below will be described below.

[0055] The following grinding methods can be listed: The grinding material slurry of the present invention is supplied to a grinding pad, the surface of the workpiece being ground comes into contact with the grinding pad, and grinding is performed through the relative motion between the two. Alternatively, the grinding material slurry of the present invention can be poured, or the grinding material slurry of the present invention can be circulated by repeatedly performing the following operation: the grinding material slurry of the present invention supplied to the grinding pad for grinding is recovered, and the recovered grinding material slurry of the present invention is supplied back to the grinding pad. The grinding material slurry of the present invention can be circulated and repeatedly ground to grind the workpiece, thus reducing the amount used. The grinding pad can be, for example, conventionally used non-woven fabric, a pad impregnated with resins such as polyurethane or epoxy resin, or suede material. Considering the grinding force and ease of operation of the grinding fixture, a grinding pressure of 5 kPa or more and 1.0 × 10⁻⁶ is preferred. 2 The pressure is below 5 kPa, particularly above 5 kPa and below 5.0 × 10 kPa. The feed rate of the grinding material slurry is preferably 10 mL / min or more and 2000 mL / min or less, more preferably 50 mL / min or more and 800 mL / min or less.

[0056] Examples of materials that can be ground using the abrasive slurry of the present invention include glass, quartz, silicon oxide, silicon (silicon wafers, etc.), and high-hardness materials with a Mohs hardness of 8 or higher. Furthermore, the abrasive slurry of the present invention can also be used for chemical-mechanical polishing (CMP) through a chemical reaction with the workpiece caused by cerium oxide. In addition, by adding an oxidizing agent, such as potassium permanganate or hydrogen peroxide, to the abrasive slurry of the present invention, a CMP process that more effectively accelerates the chemical reaction can be performed. The workpiece ground in the CMP process is, for example, a high-hardness material with a Mohs hardness of 8 or higher. Mohs hardness refers to the hardness obtained by numerically quantifying the hardness based on scratching a standard substance, and can be measured using a Mohs hardness tester using conventional methods. The Mohs hardness scale assigns standard materials a hardness of 1 to 10, starting with the softest materials. The specific Mohs hardness values ​​for these standard materials are: 1 for talc, 2 for gypsum, 3 for calcite, 4 for fluorite, 5 for apatite, 6 for orthoclase, 7 for quartz, 8 for topaz, 9 for corundum, and 10 for diamond. Materials with a Mohs hardness of 8 or higher include silicon carbide (approximately 9 on the Mohs scale), gallium nitride (approximately 9 on the Mohs scale), and diamond.

[0057] Furthermore, the workpiece to be polished using the polishing slurry of the present invention is preferably a silicon wafer or the like with a silicon oxide layer on its surface, or it may be a multilayer structure, or a composite material made by combining multiple materials. In particular, in the case of silicon or the like, the polishing slurry of the present invention can be used in the manufacturing process of semiconductor devices having a substrate (wafer) during the formation of STI (Shallow Trench Isolation) structures, the planarization of pre-metal insulating materials or interlayer insulating materials, the formation of plugs or embedded metal wiring, etc.

[0058] Next, the method for manufacturing the abrasive slurry of the present invention described above will be explained. Examples of the method for manufacturing the abrasive slurry of the present invention include a wet grinding method and a dry grinding method.

[0059] In the manufacturing methods based on wet grinding or dry grinding described later, the particle size of the cerium oxide (abrasive particles, CeO2) or magnesium hydroxide (additive, abrasive particles, Mg(OH)2) used as raw materials is the particle size (D50) of the cumulative fraction of the volume reference, determined by laser diffraction / scattering particle size distribution measurement method. Specifically, the sample for measurement is prepared by diluting the raw material with water to a concentration of approximately 0.01%. Then, the particle size (D50) of the cumulative fraction of the volume reference is measured using a laser diffraction / scattering particle size distribution measurement apparatus (MicrotracBEL Co., Ltd.: MT3300EXII).

[0060] First, the following describes the manufacturing method of the abrasive slurry of the present invention based on wet grinding.

[0061] Add pure water, cerium oxide (abrasive particles, CeO2), magnesium hydroxide (additive, abrasive particles, Mg(OH)2), and a dispersant (e.g., trisodium citrate) to a container, and place the container on a paint mixer (60 Hz) to rotate it at high speed, thereby slurrying the mixture. It should be noted that a bead mill can also be used instead of a paint mixer.

[0062] Beads (0.1 mm zirconia) are added to the container, and the slurry mixture is wet-crushed, thereby crushing the cerium oxide in the mixture.

[0063] The slurry was collected by filtering the mixture containing pulverized cerium oxide in the container through a filter, thereby separating it from the beads.

[0064] Then, the concentration of solid components, i.e. the concentration of cerium oxide abrasive particles, in the collected supernatant is determined by a heated moisture meter. Pure water is added in a manner that reaches the specified concentration for mixing, thereby obtaining the abrasive material slurry of the present invention.

[0065] Next, the method for manufacturing the abrasive slurry of the present invention based on dry grinding will be described.

[0066] Cerium oxide (abrasive particles, CeO2) and beads (zirconia, φ0.4mm) are placed in a container, which is then placed on a paint mixer (60Hz) to rotate the container at high speed, thereby dry-crushing the cerium oxide.

[0067] Use a filter to separate the mixture containing dry-crushed cerium oxide from the beads in the container, and collect the mixture containing the dry-crushed cerium oxide.

[0068] Then, pure water, dry-crushed cerium oxide (abrasive particles, CeO2), magnesium hydroxide (additive, abrasive particles, Mg(OH)2), and dispersant (e.g., trisodium citrate) are added to the container, and the container is placed on a paint mixer (60 Hz) to make the container rotate at high speed, thereby slurrying the mixture.

[0069] Then, the collected slurry is filtered with a filter having particle capture performance (e.g., particle capture performance of 2μm or larger), and the concentration of solid components in the supernatant, i.e. the concentration of cerium oxide abrasive particles, is measured with a heated moisture meter. Pure water is added in a manner that reaches the specified concentration and the mixture is stirred to obtain the abrasive material slurry of the present invention.

[0070] It should be noted that when the expressions "X to Y" (where X and Y are arbitrary numbers) are used in this specification, unless otherwise specified, they include the meaning of "X or more and Y or less," and also include the meaning of "preferably greater than X" or "preferably less than Y." Furthermore, when the expressions are "X or more" (where X is any number) or "Y or less" (where Y is any number), they also include the intention of "preferably greater than X" or "preferably less than Y."

[0071] Invention Effects

[0072] The grinding material slurry of the present invention can suppress the decrease in grinding rate caused by time changes even if the particle size of the abrasive grains is fine. Attached Figure Description

[0073] Figure 1 This is a summary table of the physical properties and measurement results of the abrasive slurries of Examples 1-9 and Comparative Examples 1-5. Detailed Implementation

[0074] The following examples further illustrate the abrasive slurry of embodiments of the present invention. However, the following examples do not limit the present invention.

[0075] (Example 1)

[0076] First, pure water, cerium oxide (CeO2, 22.2 μm particle size) as cerium oxide-based abrasive particles, magnesium hydroxide (Mg(OH)2, 3.5 μm particle size) as additive and magnesium hydroxide-based abrasive particles, and trisodium citrate as dispersant were added to a container and mixed to obtain a slurry containing cerium oxide. Specifically, when the grinding material slurry of Example 1 was set to 100% by mass, the amount of magnesium hydroxide added was 0.78% by mass. Furthermore, when the grinding material slurry of Example 1 was set to 100% by mass, the amount of trisodium citrate added was 0.6% by mass.

[0077] Next, the container was placed on a paint mixer (60 Hz) and rotated at high speed to wet grind the cerium oxide (CeO2) and magnesium hydroxide (Mg(OH)2) to a final average abrasive particle size of 0.1 μm.

[0078] The mixture of cerium oxide and wet-crushed slurry in the container is filtered to separate it from the beads, and the mixture is collected.

[0079] The collected mixture slurry was mixed with pure water using a heated moisture meter to reduce the concentration of solid components in the supernatant, i.e., the concentration of cerium oxide abrasive particles, to 10% by mass when the grinding material slurry of Example 1 was set to 100% by mass, thus obtaining the grinding material slurry of Example 1.

[0080] (Example 2)

[0081] In Example 2, except that the particle size of magnesium hydroxide (Mg(OH)2) was set to 6 μm, the same manufacturing method as in Example 1 was carried out to obtain the grinding material slurry of Example 2.

[0082] (Example 3)

[0083] In Example 3, except that the particle size of magnesium hydroxide (Mg(OH)2) was set to 0.15 μm, the same manufacturing method as in Example 1 was carried out to obtain the grinding material slurry of Example 3.

[0084] (Example 4)

[0085] In Example 4, except that the amount of magnesium hydroxide (Mg(OH)2) added was set to 0.1% by mass, the same manufacturing method as in Example 1 was carried out to obtain the grinding material slurry of Example 4.

[0086] (Example 5)

[0087] In Example 5, except that the dispersant was changed from trisodium citrate to trisodium gluconate, the same manufacturing method as in Example 1 was carried out to obtain the grinding material slurry of Example 5.

[0088] (Example 6)

[0089] In Example 6, except that the dispersant was changed from trisodium citrate to (L)-disodium tartrate dihydrate, the same manufacturing method as in Example 1 was carried out to obtain the grinding material slurry of Example 6.

[0090] (Example 7)

[0091] In Example 7, except that the amount of magnesium hydroxide (Mg(OH)2) added was set to 0.01% by mass, the same manufacturing method as in Example 1 was carried out to obtain the grinding material slurry of Example 7.

[0092] (Example 8)

[0093] In Example 8, except that the amount of magnesium hydroxide (Mg(OH)2) added was set to 10% by mass, the same manufacturing method as in Example 1 was carried out to obtain the grinding material slurry of Example 8.

[0094] (Example 9)

[0095] In Example 9, wet grinding was performed with cerium oxide (CeO2) as cerium oxide abrasive and magnesium hydroxide (Mg(OH)2) as magnesium hydroxide abrasive, so that the final average particle size of the abrasive particles was 0.3 μm. Otherwise, the same manufacturing method as in Example 1 was carried out to obtain the abrasive material slurry of Example 9.

[0096] (Comparative Example 1)

[0097] In Comparative Example 1, the additive was changed from magnesium hydroxide (Mg(OH)2, raw material particle size 3.5 μm) to calcium hydroxide (Ca(OH)2, raw material particle size 26.9 μm). Otherwise, the same manufacturing method as in Example 1 was carried out to obtain the grinding material slurry of Comparative Example 1.

[0098] (Comparative Example 2)

[0099] In Comparative Example 2, the additive was changed from magnesium hydroxide (Mg(OH)2, raw material particle size 3.5 μm) to aluminum hydroxide (Al(OH)3, raw material particle size 70.1 μm). Otherwise, the same manufacturing method as in Example 1 was carried out to obtain the grinding material slurry of Comparative Example 2.

[0100] (Comparative Example 3)

[0101] In Comparative Example 3, except that no additives were added, the same manufacturing method as in Example 1 was performed to obtain the abrasive slurry of Comparative Example 3.

[0102] (Comparative Example 4)

[0103] In Comparative Example 4, the average particle size of cerium oxide (CeO2) as cerium oxide abrasive and magnesium hydroxide (Mg(OH)2) as magnesium hydroxide abrasive was set to 0.7 μm. Otherwise, the same manufacturing method as in Example 1 was performed to obtain the abrasive slurry of Comparative Example 4.

[0104] (Comparative Example 5)

[0105] In Comparative Example 5, no additives were added, and the average particle size of the cerium oxide (CeO2) abrasive particles used as cerium oxide abrasive particles was set to 0.7 μm. Otherwise, the same manufacturing method as in Example 1 was performed to obtain the abrasive slurry of Comparative Example 5.

[0106] Then, for the abrasive material slurries of Examples 1-9 and Comparative Examples 1-5, the following physical property values ​​were measured. The measured physical property values ​​and the methods for measuring these values ​​are shown below, and the measurement results are presented in… Figure 1 .

[0107] <Component Analysis>

[0108] The total rare earth oxide (TREO) content in the cerium oxide abrasive particles used in the abrasive slurries of Examples 1-9 and Comparative Examples 1-5 was determined by oxalate precipitation-calcination-gravimetric method (unit: solids: mass %; liquids: g / L). As a pretreatment for this determination, when the analyte was a solid (abrasive raw material or abrasive material), it was dissolved using nitric acid, perchloric acid, and hydrogen peroxide, and then boiled. When the analyte was a liquid, it was directly boiled. Specifically, 100 ml of the abrasive slurry from Examples 1-9 and Comparative Examples 1-5 was placed in separate glass beakers and dried at 120°C for 24 hours to obtain a dried powder. This powder was then dissolved by adding 5 mL of 60% nitric acid, 5 mL of 60% perchloric acid, and 1 mL of 35% hydrogen peroxide water, and boiled to prepare the test samples for Examples 1-9 and Comparative Examples 1-5. Then, the total rare earth oxide (TREO) content of the test samples from Examples 1-9 and Comparative Examples 1-5 was determined by oxalate precipitation-calcination-gravimetric method. The test samples obtained from the above total rare earth oxide (TREO) determination were dissolved in 5 mL of 60% nitric acid, 5 mL of 60% perchloric acid, and 1 mL of 35% hydrogen peroxide water, and the CeO2 / TREO ratio was calculated by ICP-OES. Additionally, the La2O3 / TREO and Pr6O2 / TREO ratios were also determined. 11 / TREO and Nd2O3 / TREO are calculated in the same way. In addition, regarding the fluorine (F) content, the test sample is soluble by alkaline melting-warm water extraction, and the F concentration in the solution is determined by the fluoride ion electrode method, thereby calculating the F content (mass%) in the test sample.

[0109] To determine the content of magnesium hydroxide-based abrasive particles used in the abrasive slurries of Examples 1-9 and Comparative Examples 1-5, 5 mL of 60% nitric acid, 5 mL of 60% perchloric acid, and 1 mL of 35% hydrogen peroxide water were added to the above-mentioned solid sample (abrasive raw material or abrasive material). The sample was then heated to decompose and solution occurred. The Mg concentration was determined using an ICP-OES apparatus. The added magnesium hydroxide content was estimated by multiplying it by a hydroxide coefficient. As mentioned above, this hydroxide coefficient is 2.40.

[0110] <Particle size evaluation>

[0111] The average particle size of cerium oxide (CeO2), magnesium hydroxide (Mg(OH)2), calcium hydroxide (Ca(OH)2), and aluminum hydroxide (Al(OH)3) in the abrasive slurries of Examples 1-9 and Comparative Examples 1-5 was determined by a particle size distribution measurement method using dynamic light scattering (D50). The particle size distribution was evaluated using a Zeta potential-particle size-molecular weight measurement system (manufactured by Otsuka Electronics Co., Ltd.: ELSZ-2000ZS) according to JIS Z8828:2019 "Particle size analysis - dynamic light scattering method," measuring the particle size (D50) at a cumulative fraction of 50% based on volume. Furthermore, the abrasive slurries of Examples 1-9 and Comparative Examples 1-5 were diluted with pure water as needed, with the solid component concentration in each abrasive slurry being 0.005% to 0.1% by mass, and used as test samples. Prior to the measurement, the sample was filtered through an 11 μm pore size filter and ultrasonically treated for 3 minutes using an ultrasonic cleaner (AS ONE: VS-100III). The liquid temperature of the sample was then adjusted to 25°C. It should be noted that the particle size (D50) refers to the particle size representing the 50% cumulative value of the cumulative distribution curve, i.e., the median particle size (D50).

[0112] <Grinding Rate Measurement Experiment>

[0113] The grinding rate of the abrasive slurries of Examples 1-9 and Comparative Examples 1-5 was evaluated using the following steps. The grinding material was 60 mm diameter soda-lime glass. A single-sided polishing machine manufactured by MAT Corporation was used as the grinding apparatus. A polyurethane abrasive pad was used as the grinding pad mounted on the base. Furthermore, the abrasive slurry used in the measurement was prepared by adjusting the abrasive particle concentration of the abrasive slurries of Examples 1-9 and Comparative Examples 1-5 to 100 g / L. The feed rate of the abrasive slurry was set to 600 mL / min, and the pressure on the grinding surface was set to 9.8 kPa (100 g / cm³). 2 The grinding mill was set to a rotational speed of 60 rpm. Grinding was then performed, and the mass of the soda-lime glass before and after the grinding process was measured. The decrease in mass of the soda-lime glass caused by the grinding process was calculated, and the grinding rate was determined based on this value. The grinding rate after 20 minutes of grinding was taken as the initial rate, and the grinding rate after 6 hours of grinding was taken as the elapsed rate. If the initial rate was 0.45 μm / min or higher, it was rated "00 (Excellent)"; if the initial rate was 0.40 μm / min or higher but less than 0.45 μm / min, it was rated "0 (Good)"; if the initial rate was less than 0.40 μm / min, it was rated "× (Poor)". If the elapsed rate was 80% or higher of the initial rate, it was rated "00 (Excellent)"; if it was 60% or higher but less than 80% of the initial rate, it was rated "0 (Good)"; if it was less than 60% of the initial rate, it was rated "× (Poor)". It should be noted that the elapsed time rate is preferably 0.2 μm / min or more, more preferably 0.32 μm / min or more, and particularly preferably 0.36 μm / min or more.

[0114] <Grinding Precision Evaluation>

[0115] The surface of the soda-lime glass that underwent 6 hours of grinding in the above-mentioned grinding rate test was washed with pure water, dried in a dust-free environment, and then the grinding accuracy was evaluated. The evaluation of grinding accuracy was as follows: for the ground surface, the surface roughness Ra was measured using an atomic force microscope (AFM; Hitachi High-Tech Science AFM5400L) within a measurement range of 10 μm × 10 μm, and the surface roughness Ra was calculated for evaluation. If the surface roughness Ra was less than 0.24 nm, it was rated as "〇〇 (Excellent)"; if the surface roughness Ra was 0.25 nm or more and less than 0.30 nm, it was rated as "〇 (Good)"; and if the surface roughness Ra was 0.30 nm or more, it was rated as "× (Poor)".

[0116] <pH Measurement>

[0117] In the grinding material slurries of Examples 1-9 and Comparative Examples 1-5, the pH was measured after the pH meter (HORIBA: glass electrode type hydrogen ion concentration indicator D-53) electrode (HORIBA: standard ToupH electrode 9615S-10D) was used and the liquid temperature was stabilized at 25°C. The pH measured after 20 minutes of grinding was taken as the initial pH, and the pH measured after 6 hours of grinding was taken as the elapsed pH.

[0118] like Figure 1 As shown, the abrasive slurries of Examples 1 to 9, by having magnesium hydroxide-based abrasive particles as additives, suppress deterioration caused by time changes even when the average particle size of the cerium oxide-based abrasive particles and the magnesium hydroxide-based abrasive particles is 0.01 μm to 0.5 μm.

[0119] The abrasive slurries of Examples 1-9 contain one or more of sodium citrate, sodium gluconate, and sodium tartrate as dispersants, which inhibits degradation caused by time-related changes.

[0120] The abrasive slurries of Examples 1-9 suppressed the decrease in grinding rate due to time variations and exhibited excellent surface roughness Ra. On the other hand, the abrasive slurries of Comparative Examples 1 and 2 experienced excessive agglomeration due to time variations during grinding, resulting in grinding failure or interruption of the grinding process. Furthermore, the abrasive slurries of Comparative Examples 4 and 5, due to the large average particle size of the cerium oxide-based or magnesium hydroxide-based abrasive grains, achieved a surface roughness Ra of 0.30 nm or higher.

[0121] The pH of the abrasive slurries in Examples 1-9 also suppressed the changes caused by time.

[0122] When the grinding material slurry of Examples 1 to 9 is set to 100% by mass, a good grinding rate can be achieved if the content of cerium oxide abrasive particles is 0.5% by mass or more and 40% by mass or less, and the content of magnesium hydroxide abrasive particles is 0.005% by mass or more and 20% by mass or less.

[0123] Regarding the abrasive slurries of Examples 1-9, if the weight ratio of magnesium hydroxide-based abrasive grains to cerium oxide-based abrasive grains is 1.25 × 10⁻⁶... -4 If the value is above 40 and below 40, the decrease in grinding rate can be suppressed.

[0124] Regarding the abrasive slurries of Examples 1-9, when the cerium oxide-based abrasive grains are set to 100% by mass, if the Ce content (calculated as CeO2) of the cerium oxide-based abrasive grains is 100% by mass or less, the La content (calculated as La2O3) is 40% by mass or less, the F content (calculated as F) is 10% by mass or less, and the Pr content (calculated as Pr6O) is... 11If the Nd content is less than 10% by mass and the Nd content is less than 10% by mass when converted from Nd2O3, a good grinding rate can be achieved.

[0125] In addition to the configurations of each invention and embodiment, the inventions disclosed in this specification also include configurations determined by changing their partial configurations to other configurations disclosed in this specification within the scope of applicability, configurations determined by adding other configurations disclosed in this specification to these configurations, or configurations determined by deleting these partial configurations within the limit of obtaining the local effect.

[0126] Industrial availability

[0127] The abrasive slurry of the present invention is less prone to a decrease in grinding rate due to changes over time, and pH fluctuations are suppressed, making it suitable as an abrasive material for use in CMP processes. Furthermore, because the abrasive slurry of the present invention is less prone to a decrease in grinding rate due to changes over time, and pH fluctuations are suppressed, the abrasive slurry can be used for a longer period of time compared to conventional methods. Therefore, it is possible to reduce the amount of manufactured products and associated waste, and also to reduce energy costs during manufacturing and waste disposal. Due to these aspects, it achieves the advantages of sustainable and efficient management of natural resources, as well as decarbonization (carbon neutralization).

Claims

1. A grinding material slurry, characterized in that, It contains only cerium oxide-based abrasive particles, magnesium hydroxide-based abrasive particles, dispersant and solvent, wherein the average particle size of the cerium oxide-based abrasive particles and the magnesium hydroxide-based abrasive particles is greater than 0.01 μm and less than 0.5 μm.

2. The abrasive slurry according to claim 1, characterized in that, The solvent contains water.

3. The abrasive slurry according to claim 1, characterized in that, The dispersant comprises one or more selected from organic acid alkali metal salts, phosphoric acid, and polymeric dispersants.

4. The abrasive slurry according to claim 3, characterized in that, The organic acid alkali metal salt contains one or more selected from sodium citrate, sodium gluconate, and sodium tartrate.

5. The abrasive slurry according to claim 1, characterized in that, The cerium oxide abrasive grains are cerium oxide abrasive grains.

6. The abrasive slurry according to claim 1, characterized in that, When the abrasive slurry is set to 100% by mass, the content of cerium oxide abrasive particles is 0.5% by mass or more and 40% by mass or less, and the content of magnesium hydroxide abrasive particles is 0.005% by mass or more and 20% by mass or less.

7. The abrasive slurry according to claim 1, characterized in that, The weight ratio of the weight of the magnesium hydroxide-based abrasive particles relative to the weight of the cerium oxide-based abrasive particles is 1.25 x 10 -4 above and 40 below.

8. The abrasive slurry according to claim 1, characterized in that, When the cerium oxide-based abrasive grains are set to 100% by mass, the Ce content (calculated as CeO2) of the cerium oxide-based abrasive grains is less than 100% by mass, the La content (calculated as La2O3) is less than 40% by mass, the F content (calculated as F) is less than 10% by mass, and the Pr content (calculated as Pr6O) is less than 10% by mass. 11 The conversion is less than 10% by mass, and the Nd content is less than 10% by mass when converted from Nd2O3.

9. A grinding material slurry, characterized in that, It contains cerium oxide-based abrasives, magnesium hydroxide-based abrasives, dispersants, and solvents. The grinding material slurry does not contain chelating agents. The average particle size of the cerium oxide-based abrasive grains and the magnesium hydroxide-based abrasive grains is greater than 0.01 μm and less than 0.5 μm.

10. The abrasive slurry according to claim 9, characterized in that, The solvent contains water.

11. The abrasive slurry according to claim 9, characterized in that, The dispersant comprises one or more selected from organic acid alkali metal salts, phosphoric acid, and polymeric dispersants.

12. The abrasive slurry according to claim 11, characterized in that, The organic acid alkali metal salt contains one or more selected from sodium citrate, sodium gluconate, and sodium tartrate.

13. The abrasive slurry according to claim 9, characterized in that, The cerium oxide abrasive grains are cerium oxide abrasive grains.

14. The abrasive slurry according to claim 9, characterized in that, When the abrasive slurry is set to 100% by mass, the content of cerium oxide abrasive particles is 0.5% by mass or more and 40% by mass or less, and the content of magnesium hydroxide abrasive particles is 0.005% by mass or more and 20% by mass or less.

15. The abrasive slurry according to claim 9, characterized in that, The weight ratio of the magnesium hydroxide-based abrasive grains to the weight of the cerium oxide-based abrasive grains is 1.25 × 10⁻⁶. -4 Above and below 40.

16. The abrasive slurry according to claim 9, characterized in that, When the cerium oxide-based abrasive grains are set to 100% by mass, the Ce content (calculated as CeO2) of the cerium oxide-based abrasive grains is less than 100% by mass, the La content (calculated as La2O3) is less than 40% by mass, the F content (calculated as F) is less than 10% by mass, and the Pr content (calculated as Pr6O) is less than 10% by mass. 11 The conversion is less than 10% by mass, and the Nd content is less than 10% by mass when converted from Nd2O3.

17. A grinding method, characterized in that, The workpiece is ground using the abrasive slurry as described in claim 1 or 9.

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