Method for producing polishing composition

Abstract

Provided is a method for producing a polishing composition in which the degree of dissolution of a chelating agent can be easily confirmed during production. Provided is a method for producing a polishing composition for polishing a surface formed from a silicon material. The method for producing the polishing composition comprises: preparing an alkaline chelating agent-containing liquid containing an alkaline compound, water, and a chelating agent; and mixing a silica dispersion containing silica particles and water with the chelating agent-containing liquid.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a grinding composition.

[0002] This application claims priority to Japanese Patent Application No. 2023-054103, filed on March 29, 2023, the entire contents of which are incorporated herein by reference. Background Technology

[0003] Conventionally, abrasive compositions are used for precision grinding of the surfaces of materials such as metals, semi-metals, non-metals, and their oxides. For example, the surface of silicon wafers, used as components of semiconductor products, is typically refined into a high-quality mirror finish through grinding and polishing processes. These polishing processes include, for example, a pre-polishing process (pre-grinding process) and a final polishing process (final grinding process). The pre-polishing process includes, for example, a coarse grinding process (first grinding process) and an intermediate grinding process (second grinding process). Patent Document 1 is cited as a technical document concerning the abrasive compositions used in the aforementioned polishing processes.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 6882727 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] Polishing compositions used in polishing surfaces formed of silicon (e.g., the surface of a silicon wafer) sometimes contain chelating agents. Through the bonding of the chelating agent with metal elements to form stable complex ions, the polishing composition used in polishing can suppress contamination of the silicon material caused by metal impurities. For example, in the embodiment described in Patent Document 1, tetrasodium ethylenediaminetetraacetate is used as the chelating agent (paragraph 0042).

[0009] The inventors have focused on the following situation: In a polishing composition containing a chelating agent, if the chelating agent is not sufficiently dissolved, the dissolved residual chelating agent remains on the polished surface along with the metal elements, potentially causing metal contamination of the surface. However, polishing compositions containing abrasive particles (e.g., silica particles) become turbid due to these abrasive particles, making it difficult to confirm whether the chelating agent is sufficiently dissolved.

[0010] Therefore, the object of the present invention is to provide a method for manufacturing a grinding composition comprising silica particles and a chelating agent, which allows for easy confirmation of the degree of dissolution of the chelating agent during the manufacturing process.

[0011] Solution for solving the problem

[0012] According to this specification, a method for manufacturing a polishing composition for polishing surfaces formed of silicon material is provided. The manufacturing method includes: preparing an alkaline liquid containing a basic compound, water, and a chelating agent; and mixing a silica dispersion containing silica particles and water with the aforementioned liquid containing the chelating agent. According to this method, by making the liquid containing the chelating agent alkaline, a good dissolution of the chelating agent is easily obtained in the liquid. Furthermore, since there is no turbidity caused by silica particles in the liquid containing the chelating agent before mixing with the silica dispersion, the sufficiency of dissolution of the chelating agent can be easily confirmed by observation (e.g., visual observation) of the liquid containing the chelating agent.

[0013] In some embodiments of the methods disclosed herein, the pH of the silica dispersion mixed with the chelating agent-containing liquid (i.e., the pH before mixing with the chelating agent-containing liquid, hereinafter sometimes referred to as "pH") is... Si The pH value is preferably 6 or higher and 14 or lower. That is, the mixing of the silica dispersion and the liquid containing the chelating agent is preferably carried out by mixing an alkaline (i.e., pH greater than 7.0) liquid containing the chelating agent with a silica dispersion having a pH of 6 or higher and 14 or lower. By making the pH of the silica dispersion mixed with the liquid containing the chelating agent within the above range, a mixture in which the chelating agent is well dissolved can be easily obtained.

[0014] In some methods, an acid with an n-valent (where n≥2) is preferably used as the chelating agent, and the acid dissociation constant pKa of the chelating agent is set as pKa1…pKa in ascending order of numerical value. n At that time, pKa n-1 Compounds exceeding 7.0. In alkaline liquids containing chelating agents, pKa... n-1 Chelating agents with pKa exceeding 7.0 n-1 Compared to chelating agents with a pKa of 7.0 or lower, chelating agents tend to have a higher number of undissociated acid groups (e.g., carboxyl groups), thus resulting in lower solubility. Therefore, when using pKa... n-1 When using chelating agents exceeding 7.0, the manufacturing method disclosed herein is more effective.

[0015] In some embodiments, the chelating agent preferably comprises a chelating agent with a valence of five or more. Chelating agents with a valence of five or more generally have excellent metal ion capture properties, but tend to be a cause of metal contamination due to incomplete dissolution. Therefore, the manufacturing method disclosed herein is particularly meaningful.

[0016] In some embodiments, the above-described polishing composition is a polishing composition used for pre-polishing surfaces formed of the aforementioned silicon material. The methods disclosed herein can preferably be implemented in a manner that manufactures a polishing composition for pre-polishing surfaces formed of silicon material.

[0017] Additionally, according to this specification, a grinding composition manufactured by any of the manufacturing methods disclosed herein is provided. Detailed Implementation

[0018] The preferred embodiments of the present invention will now be described. It should be noted that matters necessary for implementing the present invention, other than those specifically mentioned in this specification, can be understood by those skilled in the art based on prior art in this field. The present invention can be implemented based on the content disclosed in this specification and common technical knowledge in this field.

[0019] Abrasive grains

[0020] According to this specification, a method for manufacturing an abrasive composition comprising silica particles, an alkaline compound, a chelating agent, and water is provided. In a typical embodiment of the method disclosed herein, an abrasive composition comprising the aforementioned silica particles as abrasive grains is manufactured. The method disclosed herein can preferably be carried out in such a manner that the abrasive grains contained in the aforementioned abrasive composition are substantially composed of silica particles. Here, "substantially" means that 95% by weight or more (preferably 98% by weight or more, more preferably 99% by weight or more, and possibly 100% by weight) of the particles constituting the abrasive grains are silica particles.

[0021] There are no particular restrictions on the type of silica particles; appropriate selection is acceptable. One type of silica particle can be used alone, or two or more types can be used in combination. Examples of silica particles include colloidal silica, fumed silica, and precipitated silica. Colloidal silica is particularly preferred from the perspective of minimizing scratches on the surface of the object being ground and providing good grinding performance (such as reducing surface roughness). There are no particular restrictions on the type of colloidal silica; appropriate selection is acceptable. One type of colloidal silica can be used alone, or two or more types can be used in combination. Examples of colloidal silica include colloidal silica produced by ion exchange using water glass (Na silicate) as a raw material (hereinafter also referred to as sodium silicate method silica) and colloidal silica produced by the sol-gel method (hereinafter also referred to as sol-gel method silica). The aforementioned sol-gel method silica is a colloidal silica produced through the hydrolysis and condensation reaction of alkoxysilanes, sometimes also referred to as alkoxide method colloidal silica.

[0022] The true specific gravity of the silica constituting the silica particles is preferably 1.5 or more, more preferably 1.6 or more, and even more preferably 1.7 or more. There is no particular upper limit to the true specific gravity of the silica, but it is typically 2.3 or less, for example, 2.2 or less. The true specific gravity of the silica can be determined using a liquid displacement method based on ethanol as the displacement solution.

[0023] The abrasive composition manufactured by the method disclosed herein may contain particles other than silica particles (hereinafter also referred to as particles other than silica particles) as abrasive grains. These particles other than silica particles may be inorganic particles other than silica particles, organic particles, or organic-inorganic composite particles. Specific examples of inorganic particles include oxide particles such as alumina particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese dioxide particles, zinc oxide particles, and iron oxide red particles; nitride particles such as silicon nitride particles and boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; and carbonates such as calcium carbonate and barium carbonate. Specific examples of organic particles include polymethyl methacrylate (PMMA) particles, poly(meth)acrylic acid particles, and polyacrylonitrile particles. Here, (meth)acrylic acid means including both acrylic acid and methacrylic acid. Particles other than silica may be used alone or in combination of two or more.

[0024] The abrasive grains disclosed herein can be in the form of primary particles or secondary particles formed by the association of multiple primary particles. Primary and secondary abrasive grains can coexist. In some preferred embodiments, at least a portion of the abrasive grains are in the form of secondary particles.

[0025] The average primary particle size of the abrasive grains (e.g., silica particles) is not particularly limited, but from the viewpoint of improving the grinding rate, it is preferably 5 nm or more, more preferably 10 nm or more, and particularly preferably 20 nm or more. From the viewpoint of obtaining a higher grinding effect, the average primary particle size is preferably 25 nm or more, and further preferably 30 nm or more. Abrasive grains with an average primary particle size of 40 nm or more can also be used. In some embodiments, the average primary particle size can, for example, exceed 40 nm, exceed 45 nm, or exceed 50 nm. In addition, from the viewpoint of preventing scratch formation, the average primary particle size of the abrasive grains is preferably 200 nm or less, more preferably 150 nm or less, further preferably 120 nm or less, and particularly preferably 100 nm or less. In some embodiments, the average primary particle size can be 75 nm or less, or 60 nm or less.

[0026] In this specification, the average primary particle size of the abrasive grains refers to the average primary particle size (nm) calculated by the BET method based on the specific surface area (BET value) and the true density (g / cm³). 3 )×BET value (m 2 The particle size is calculated using the formula / g). Specific surface area can be determined, for example, using a surface area measuring device manufactured by Micromeritics, trade name "Flow Sorb II2300".

[0027] The average secondary particle size of the abrasive grains is not particularly limited, and can be appropriately selected from a range of approximately 15 nm to 300 nm. From the viewpoint of improving the grinding rate, an average secondary particle size of 20 nm or more is appropriate, 25 nm or more is advantageous, 30 nm or more is preferred, and 35 nm or more is even more preferred. In some embodiments, the average secondary particle size can be, for example, 40 nm or more, 45 nm or more, preferably 50 nm or more, further 60 nm or more, and 65 nm or more (e.g., 70 nm or more). Furthermore, from the viewpoint of preventing scratch formation, an average secondary particle size of 250 nm or less is generally advantageous, preferably 200 nm or less, and more preferably 150 nm or less. In some embodiments, the average secondary particle size can be 120 nm or less, or 110 nm or less.

[0028] In this specification, the average secondary particle size of the abrasive grains refers to the particle size at the point where the volume accumulation from the smaller particle size side reaches 50% in the particle size distribution measured by dynamic light scattering. For example, it can be measured using the "FPAR-1000" model manufactured by Otsuka Electronics Co., Ltd. or an equivalent product.

[0029] The shape (appearance) of abrasive particles can be spherical or non-spherical. Specific examples of non-spherical particles include peanut-shaped (i.e., the shape of a peanut shell), cocoon-shaped, konpeito-shaped, rugby ball-shaped, etc.

[0030] The average aspect ratio of the abrasive grains is not particularly limited. In principle, the average aspect ratio of the abrasive grains is 1.0 or higher, but it can be 1.05 or higher, 1.10 or higher, or 1.15 or higher. Increasing the average aspect ratio tends to improve the grinding rate. In some cases, the average aspect ratio of the abrasive grains can be greater than 1.2 (specifically, exceeding 1.20), for example, 1.22 or higher. Abrasive grains with an average aspect ratio exceeding 1.2 are typical examples of the aforementioned non-spherical abrasive grains. Furthermore, from the viewpoint of reducing scratches and improving grinding stability, the average aspect ratio of the abrasive grains is preferably 3.0 or lower, more preferably 2.0 or lower. In some cases, the average aspect ratio of the abrasive grains can be, for example, 1.5 or lower, 1.4 or lower, or 1.3 or lower.

[0031] The shape (outline) and average aspect ratio of the aforementioned abrasive grains can be determined, for example, by observation using an electron microscope. As a specific step in determining the average aspect ratio, for example, using a scanning electron microscope (SEM), for a predetermined number (e.g., 200) of abrasive grains whose shapes can be identified as individual particles, the smallest rectangle circumscribed to each grain image is drawn. Then, for each rectangle drawn for a grain image, the length of its longer side (the value of the major diameter) is divided by the length of its shorter side (the value of the minor diameter), and the resulting value is used as the aspect ratio (length-to-width ratio). By taking the arithmetic mean of the aspect ratios of the predetermined number of grains, the average aspect ratio can be obtained.

[0032] The content of abrasive grains is not particularly limited and can be appropriately set according to the purpose. The content of abrasive grains relative to the total weight of the grinding composition can be, for example, 0.01% by weight or more, 0.05% by weight or more, or 0.1% by weight or more. Increasing the content of abrasive grains tends to increase the grinding rate. In some embodiments, the content of abrasive grains can be 0.2% by weight or more, 0.5% by weight or more, or 0.6% by weight or more. Furthermore, from the viewpoint of preventing scratches and saving the amount of abrasive grains used, in some embodiments, the content of abrasive grains can be, for example, 10% by weight or less, 5% by weight or less, 3% by weight or less, 2% by weight or less, 1.5% by weight or less, 1.2% by weight or less, or 1.0% by weight or less. Their content can preferably be applied to the content in the grinding fluid (working slurry) supplied to the object being ground.

[0033] Furthermore, in the case of a grinding composition (i.e., a concentrated solution) used for grinding after dilution, from the viewpoint of storage stability and filterability, the content of abrasive particles is generally appropriate to be 50% by weight or less, and more preferably 40% by weight or less. Additionally, from the viewpoint of maximizing the advantages of producing a concentrated solution, the content of abrasive particles is preferably 1% by weight or more, and more preferably 5% by weight or more.

[0034] <Alkaline compounds>

[0035] The grinding composition manufactured by the method disclosed herein contains an alkaline compound. Here, an alkaline compound refers to a compound that, by being included in the grinding composition, has the function of raising the pH of the composition. The alkaline compound plays a role in chemically grinding the surface to be ground, which can help increase the grinding rate. The alkaline compound can be an organic alkaline compound or an inorganic alkaline compound. One alkaline compound can be used alone or in combination of two or more.

[0036] Examples of organic basic compounds include quaternary ammonium salts such as tetraalkylammonium salts. The anion in these ammonium salts can be, for example, OH-.- F - Cl - ,Br - I - ClO4 - BH4 - HCO3 - For example, quaternary ammonium salts such as choline, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and tetramethylammonium bicarbonate can be preferred. Among these, tetramethylammonium hydroxide (TMAH) is preferred.

[0037] Other examples of organic basic compounds include quaternary phosphonium salts such as tetraalkylphosphonium salts. The anion in these phosphonium salts can be, for example, OH-. - F - Cl - ,Br - I - ClO4 - BH4 - HCO3 - For example, halides and hydroxides of tetramethylphosphonium, tetraethylphosphonium, tetrapropylphosphonium, tetrabutylphosphonium, etc., may be preferred.

[0038] Other examples of basic organic compounds include amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, N-(β-aminoethyl)ethanolamine, hexamethylenediamine, diethylenetriamine, and triethylenetetramine; piperazines such as 1-(2-aminoethyl)piperazine and N-methylpiperazine; azoles such as imidazole and triazole; and guanidines.

[0039] Examples of inorganic basic compounds include ammonia; hydroxides of ammonia, alkali metals, or alkaline earth metals; carbonates of ammonia, alkali metals, or alkaline earth metals; and bicarbonates of ammonia, alkali metals, or alkaline earth metals. Specific examples of the aforementioned hydroxides include lithium hydroxide, potassium hydroxide (KOH), and sodium hydroxide. Specific examples of the aforementioned carbonates or bicarbonates include ammonium bicarbonate, ammonium carbonate, lithium bicarbonate, lithium carbonate, potassium bicarbonate, potassium carbonate (K₂CO₃), sodium bicarbonate, and sodium carbonate.

[0040] Preferred alkaline compounds include ammonia, lithium hydroxide, potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, ammonium bicarbonate, ammonium carbonate, lithium bicarbonate, lithium carbonate, potassium bicarbonate, potassium carbonate, sodium bicarbonate, and sodium carbonate. Examples of preferred substances include ammonia, lithium hydroxide, potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide, lithium carbonate, and potassium carbonate. Quaternary ammonium compounds (quaternary ammonium salts) are preferred alkaline compounds in polishing compositions used for pre-polishing surfaces formed of silicon materials. The use of quaternary ammonium compounds is advantageous from the viewpoint of eliminating bulges around HLMs, for example, in polishing compositions used for pre-polishing silicon wafers with hard laser marking (HLM). One quaternary ammonium compound can be used alone, or two or more can be used in combination. Tetramethylammonium hydroxide is a particularly preferred compound.

[0041] While not particularly limited, from the viewpoint of achieving a good balance between maintaining the grinding rate and eliminating bulges, it is preferable to use a combination of quaternary ammonium compounds (e.g., tetramethylammonium hydroxide) and carbonates (e.g., potassium carbonate) as the basic compound. Additionally, in some methods, alkali metal or alkaline earth metal hydroxides (e.g., potassium hydroxide) may be used in addition to quaternary ammonium compounds (e.g., tetramethylammonium hydroxide) and / or carbonates (e.g., potassium carbonate). In methods using two or more of the above-mentioned quaternary ammonium compounds, carbonates, and hydroxides as the basic compound, the ratio of these components used is not particularly limited, and can be set to an appropriate range that achieves a good balance between maintaining the grinding rate and eliminating bulges, depending on the concentration of the abrasive grains or other containing components.

[0042] The content of the alkaline compound relative to the total amount of the grinding composition is preferably 0.005% by weight or more, more preferably 0.01% by weight or more, and can be 0.03% by weight or more, 0.05% by weight or more, 0.1% by weight or more, 0.2% by weight or more, 0.5% by weight or more, or 1% by weight or more. Increasing the content of the alkaline compound tends to increase the grinding rate. Setting the upper limit of the above-mentioned alkaline compound content to 7% by weight or less is appropriate. From the viewpoint of promoting the dissolution of the chelating agent by keeping the solute concentration in the chelating agent-containing liquid below a certain level, and from the viewpoint of surface quality, it is preferably 5% by weight or less, more preferably 3% by weight or less, and can be 2.5% by weight or less, 1.5% by weight or less, 1.0% by weight or less, or 0.7% by weight or less. It should be noted that when two or more alkaline compounds are used in combination, the above-mentioned content refers to the total content of the two or more alkaline compounds. Their content can preferably be applied, for example, to the content in the grinding fluid (working slurry) supplied to the object being ground.

[0043] Furthermore, in the case of a grinding composition (i.e., a concentrated solution) used for grinding after dilution, from the viewpoint of storage stability and filterability, the content of the alkaline compound is generally appropriate to be 10% by weight or less, more preferably 5% by weight or less (e.g., 4% by weight or less). Additionally, from the viewpoint of maximizing the advantages of producing a concentrated solution, the content of the alkaline compound is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, even more preferably 0.9% by weight or more, and can be 1.5% by weight or more, or 2% by weight or more.

[0044] The content of alkaline compounds in the grinding composition C B Relative to the content of abrasive particles C A weight ratio (C) B / C A There are no particular limitations as long as the effects of the technology disclosed herein can be achieved. The above-mentioned ratio (C) B / C A For example, setting it to about 0.005 or more is appropriate. From the viewpoint of effectively utilizing the addition effect of the alkaline compound, it is preferable to be 0.01 or more, more preferably 0.02 or more, and for example, it can be 0.05 or more. Furthermore, from the viewpoint of utilizing the mechanical grinding of abrasive particles and the dispersion stability of the composition, the above ratio (C) is... B / C A For example, it is appropriate to set it to about 3 or less, preferably 2 or less, more preferably 1.5 or less, it can be 1 or less, it can be 0.5 or less, it can be 0.3 or less, it can be 0.2 or less (e.g., 0.1 or less).

[0045] Chelating agents

[0046] The chelating agent used in the manufacture of the grinding composition disclosed herein can be suitably selected from chelating agents known in the art of grinding compositions. A single chelating agent can be used alone, or two or more can be used in combination. Examples of chelating agents include aminocarboxylic acid chelating agents and organophosphonic acid chelating agents.

[0047] Examples of aminocarboxylic acid chelating agents include alanine, glycine, and aspartic acid (A... SPExamples of aminocarboxylic acid chelating agents include sodium hypotriacetate, ammonium hypotriacetate, sodium ethylenediaminetetraacetate, sodium diethylenetriaminepentaacetate, sodium triethylenetetraaminehexaacetate, and sodium hydroxyethylethylenediaminetriacetate. Aminocarboxylic acid chelating agents can be used in the form of acids or salts. Examples of salts include alkali metal salts (e.g., sodium salts) and ammonium salts. Therefore, examples of aminocarboxylic acid chelating agents include, for example, sodium hypotriacetate, ammonium hypotriacetate, sodium ethylenediaminetetraacetate, sodium diethylenetriaminepentaacetate, sodium triethylenetetraaminehexaacetate, and sodium hydroxyethylethylenediaminetriacetate.

[0048] Examples of organophosphonic acid chelating agents include 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), aminotris(methylenephosphonic acid), ethylenediaminetetra(methylenephosphonic acid) (EDTPO), diethylenetriaminepenta(methylenephosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, ethane-1-hydroxy-1,1-diphosphonic acid, ethane-1,2-hydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, phosphonobutanetricarboxylic acid (PBTC), nitrotris(methylenephosphonic acid) (NTMP), and α-methylphosphorylsuccinic acid. Like aminocarboxylic acid chelating agents, organophosphonic acid chelating agents can be used in acidic form or in salt form (e.g., alkali metal salts such as sodium salts, ammonium salts, etc.).

[0049] In some preferred embodiments, an acidic chelating agent is used as part of (e.g., more than 50 mol%, more than 75 mol%, more than 90 mol%, or more than 95 mol%) or in whole as a chelating agent used in the preparation of the grinding composition. Using an acidic chelating agent is advantageous from the viewpoint of reducing alkali metals in the grinding composition.

[0050] In some preferred embodiments, from the viewpoint of metal ion capture performance, a chelating agent of an acid with an n-valent (wherein n≥2) is used as part of the chelating agent used in the preparation of the grinding composition (e.g., more than 50 mol%, more than 75 mol%, more than 90 mol%, or more than 95 mol% of the total chelating agent). More preferably, a chelating agent with n=3 or more is used; even more preferably, a chelating agent with n=4 or more is used; and particularly preferably, a chelating agent with n=5 or more (i.e., a chelating agent of an acid with a valence of 5 or more) is used. There is no particular limitation on the upper limit of n. In some embodiments, from the viewpoint of dispersion stability of the grinding composition, n=15 or less is appropriate, preferably 12 or less, and more preferably 10 or less (e.g., 8 or less). The chelating agent with n=a predetermined value or more can be appropriately selected from known chelating agents including the specific examples described above. For example, specific examples of chelating agents with n=5 or more include DTPA (5-valent), TTHA (6-valent), EDTPO (8-valent), etc., but are not limited to these.

[0051] In some methods, the acid dissociation constant pKa of the chelating agent used as the chelating agent for the aforementioned n-valent (n≥2) acid is set as pKa1…pKa in ascending order of numerical value. n When using pKa, it is preferable to use pKa. n-1 Compounds with a pKa greater than 7.0. If DTPA is used as an example, then DTPA is a pentavalent (i.e., n = 5) acid, due to pKa5 (pKa... n The value is 10.53, pKa4(pKa) n-1 The pKa is 8.6, therefore it is an n-valent (n≥2) acid, and satisfies pKa. n-1 A value greater than 7.0 is required. Specific examples of chelating agents that meet this requirement include DTPA, TTHA, EDTPO, and EDDHA, but these are not limited to. A suitable chelating agent that meets the above requirement can be selected from known chelating agents. It should be noted that the acid dissociation constant pKa can be the manufacturer's nominal value (catalog value). For example, the value listed in the catalog of Tongjin Chemical Co., Ltd. can be used.

[0052] The pH of the chelating agent-containing liquid described later (pH) ch The relationship between pH and other pH values ​​is easily satisfied. ch >pKa n-1 From this perspective, in some ways, the pKa of the chelating agent used in the manufacture of the grinding composition is... n-1 A value of 12 or less is appropriate, preferably 11 or less, and more preferably 10 or less. Furthermore, if the valence (n) of the acid used as a chelating agent increases, then pKa... n-1The value of α generally tends to increase. From the perspective of easily enjoying the advantages brought by using chelating agents with high valence, in some ways, the pKa of the chelating agent... n-1 Preferably, it is 7.5 or higher, more preferably 8.0 or higher, and even more preferably 8.5 or higher.

[0053] Suitable examples of aminocarboxylic acid chelating agents include EDTA, DTPA, TTHA, and EDDHA. Among these, DTPA, TTHA, and EDDHA are preferred, with DTPA and TTHA being particularly preferred. EDTPO is a particularly preferred organophosphonic acid chelating agent.

[0054] The content of the chelating agent in the grinding composition can be set to, for example, 0.001 mM or more (i.e., 0.001 mmol / L or more), and in some cases, preferably 0.005 mM or more, more preferably 0.01 mM or more, for example, 0.05 mM or more, 0.1 mM or more, 0.5 mM or more, 1.0 mM or more, 1.5 mM or more, or 2.0 mM or more. By increasing the content of the chelating agent in the grinding composition [unit: mM], the metal capture per unit volume of the grinding composition can be increased. This is preferable from the viewpoint of reducing the replacement frequency of the grinding composition in grinding, for example, by recycling the grinding composition (grinding fluid). In addition, the content of the chelating agent in the grinding composition can be set to 250 mM or less, for example. From the viewpoint of easily achieving a good dissolution state of the chelating agent, it is appropriate to set it to 100 mM or less in some ways, preferably 50 mM or less, more preferably 20 mM or less, and it can be 10 mM or less, 5 mM or less, or 3 mM or less.

[0055] Furthermore, in the case of a grinding composition (i.e., a concentrated solution) used for grinding after dilution, the content of the chelating agent in the concentrated solution can be, for example, set to 0.01 mM or more. From the viewpoint of maximizing the advantages of producing a concentrated solution, it is preferably 0.05 mM or more, more preferably 0.1 mM or more, and can be 0.5 mM or more, 1 mM or more, 3 mM or more, or 5 mM or more. Additionally, the content of the chelating agent in the above-mentioned concentrated solution can be, for example, set to 500 mM or less. From the viewpoint of easily achieving a good dissolution state of the chelating agent, in some cases, setting it to 200 mM or less is appropriate, preferably 100 mM or less, more preferably 50 mM or less, 30 mM or less, 20 mM or less, or 15 mM or less.

[0056] <Water>

[0057] The grinding composition disclosed herein contains water. Preferably, ion-exchanged water (deionized water), pure water, ultrapure water, distilled water, etc., can be used. To minimize the obstruction of the function of other components contained in the grinding composition, the total content of transition metal ions in the water used is preferably 100 ppb or less. For example, the purity of the water can be improved by removing impurity ions using an ion exchange resin, removing foreign matter using a filter, distillation, etc.

[0058] The grinding compositions disclosed herein may, as needed, further contain an organic solvent (lower alcohols, lower ketones, etc.) capable of being uniformly mixed with water. Generally, it is preferred that the solvent contained in the grinding compositions is at least 90% by volume water, more preferably at least 95% by volume (e.g., 99 to 100% by volume) water.

[0059] <Water-soluble polymers>

[0060] The polishing composition manufactured by the methods disclosed herein may contain a water-soluble polymer as an optional component. The water-soluble polymer can help improve the surface quality after polishing and enhance the elimination of bulges around the HLM periphery during pre-polishing of silicon wafers with HLM.

[0061] Examples of water-soluble polymers include cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polymers containing nitrogen atoms, and vinyl alcohol polymers. Specific examples include hydroxyethyl cellulose, pullulan, random copolymers or block copolymers of ethylene oxide and propylene oxide, unmodified polyvinyl alcohol, modified polyvinyl alcohol (e.g., acetalized polyvinyl alcohol), polyisoprene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyisoprene sulfonic acid, polystyrene sulfonate, styrene-maleic acid copolymer, polyacrylate, polyvinyl acetate, polyethylene glycol, polyvinylimidazolium, polyvinylcarbazole, polyvinylpyrrolidone, polyacrylamide, polycaprolactam, and polyvinylpiperidine. Water-soluble polymers can be used alone or in combination of two or more.

[0062] In the disclosed technology, the molecular weight of the water-soluble polymer is not particularly limited. For example, the weight-average molecular weight (Mw) of the water-soluble polymer can be set to approximately 200 × 10⁻⁶. 4 Below, 150×10 4 The following is appropriate. From the viewpoint of suppressing grinding vibration and surface defects, the above Mw can be approximately 100 × 10. 4 The following can also be approximately 50×10 4 Below. Furthermore, from the viewpoint of protecting the silicon wafer surface, the aforementioned Mw is typically approximately 0.2 × 10⁻⁶. 4 The above is approximately 0.5 × 10 4The above is appropriate, and it could also be approximately 0.8 × 10⁻⁶. 4 above.

[0063] It should be noted that Mw, as a water-soluble polymer, can be represented by the value obtained from water-based gel permeation chromatography (GPC) (conversion between water-based and polyethylene oxide).

[0064] Although not specifically limited, the total amount of water-soluble polymers relative to the total weight of the grinding composition (or their total content if it contains two or more water-soluble polymers) can, for example, be set to 1.0 × 10⁻⁶. -7 For amounts exceeding 1% by weight, set to 1.0 × 10⁻⁶. -6 A weight percentage of 1.0% or more is appropriate, and in some preferred embodiments, it can be 1.0 × 10⁻⁶. -5 At a weight percentage or higher, it can be 5.0 × 10⁻⁶. -5 At a weight percentage or higher, it can be 1.0 × 10⁻⁶. -4 At a weight percentage or higher, it can be 2.0 × 10⁻⁶. -4 At a weight percentage or higher, it can be 3.0 × 10⁻⁶. -4 The amount is % by weight or more. Furthermore, from the viewpoint of maintaining the grinding rate, the total amount of the aforementioned water-soluble polymer can be set to, for example, 0.5% by weight or less, 0.1% by weight or less, and in some preferred embodiments, it can be 0.05% by weight or less, 0.01% by weight or less, 0.005% by weight or less, 0.001% by weight or less, or 0.0005% by weight or less. Alternatively, the water-soluble polymer may not be used.

[0065] In the case of a grinding composition (i.e., a concentrated solution) used for grinding after dilution, the total amount of the aforementioned water-soluble polymer can, for example, be set to 1.0 × 10⁻⁶. -6 For amounts exceeding 1% by weight, set to 1.0 × 10⁻⁶. -5 A weight percentage above is appropriate, and can be 1.0 × 10⁻⁶. -4 At a weight percentage or higher, it can be 1.0 × 10⁻⁶. -3 At a weight percentage or higher, it can be 5.0 × 10⁻⁶. -3 The total amount of the water-soluble polymer can be set to 5% or less by weight, or 1% or less by weight, preferably 0.5% or less by weight, or 0.1% or less by weight, or 0.05% or less by weight.

[0066] The total amount of water-soluble polymers in the grinding composition (the total content of two or more water-soluble polymers) relative to 100 parts by weight of abrasive grains can be, for example, 0.0001 parts by weight or more, which is appropriate. In some preferred embodiments, it can be 0.005 parts by weight or more, 0.01 parts by weight or more, 0.02 parts by weight or more, 0.05 parts by weight or more, or 0.1 parts by weight or more. Furthermore, from the viewpoint of dispersion stability, the total amount of water-soluble polymers relative to 100 parts by weight of abrasive grains can be, for example, 10 parts by weight or less, or 5 parts by weight or less. From the viewpoint of maintaining the grinding rate, in some preferred embodiments, the total amount of water-soluble polymers relative to 100 parts by weight of abrasive grains can be 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, 0.1 parts by weight or less, or 0.05 parts by weight or less.

[0067] <Other Ingredients>

[0068] The polishing compositions manufactured by the methods disclosed herein may, as needed, contain, within a range that does not significantly impair the effects of the invention, known additives such as inorganic acid salts, organic acid salts, surfactants, preservatives, and fungicides that can be used in polishing compositions (e.g., polishing compositions used in the polishing process of silicon wafers).

[0069] For example, examples of inorganic acid salts include salts of hydrohalic acids (e.g., hydrochloric acid, hydrobromic acid, hydroiodic acid, hydrofluoric acid), nitric acid, sulfuric acid, sulfurous acid, hydrogen sulfite, thiosulfate, silicic acid, boric acid, phosphoric acid, etc. Examples of organic acid salts include salts of carboxylic acids (e.g., formic acid, acetic acid, propionic acid, benzoic acid, butyric acid, trifluoroacetic acid), organic sulfonic acids (e.g., methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid), aminosulfonic acids, organic phosphoric acids (e.g., ethyl phosphoric acid), etc. There are no particular limitations on the cations constituting the above-mentioned inorganic and organic acid salts; examples include alkali metals (lithium, sodium, potassium, etc.), alkaline earth metals (calcium, strontium, barium, etc.), magnesium, ammonium, etc. Specific examples of sulfuric acid salts (sulfates) include lithium sulfate, sodium sulfate, potassium sulfate, ammonium sulfate, etc. It should be noted that the inorganic and organic acid salts in this specification do not contain the aforementioned basic compounds. Furthermore, the organic acid salts in this specification do not contain the aforementioned chelating agents.

[0070] Surfactants can be used alone or in combination of two or more. Examples of surfactants mentioned above are not particularly limited and can include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. By using surfactants (e.g., those with a molecular weight less than 0.2 × 10⁻⁶), 4(Water-soluble organic compounds), the dispersion stability of the grinding composition can be improved. Mw, as a surfactant, can be a value obtained through GPC (converted to aqueous or polyethylene glycol) or a value calculated from the chemical formula.

[0071] In some embodiments, the grinding composition has a composition in which the amount of surfactant is limited. The surfactant content in the grinding composition (e.g., grinding fluid) may be less than 0.3% by weight, less than 0.1% by weight, less than 0.05% by weight, less than 0.005% by weight, or less than 0.0005% by weight. The techniques disclosed herein can preferably be implemented in a manner in which the grinding composition is substantially surfactant-free, i.e., at least intentionally surfactant-free.

[0072] Examples of the aforementioned preservatives and fungicides include isothiazolinate compounds, p-hydroxybenzoates, and phenoxyethanol.

[0073] The polishing composition manufactured by the method disclosed herein is preferably substantially free of oxidants. This is because when an oxidant is included in the polishing composition, the surface formed of silicon material (e.g., the surface of a silicon wafer) is oxidized by supplying the composition, resulting in an oxide film, which may lead to a decrease in polishing rate. Here, "substantially free of oxidants" means that oxidants are intentionally not mixed in, allowing for the unavoidable inclusion of trace amounts of oxidants from raw materials, manufacturing processes, etc. The aforementioned trace amounts refer to a molar concentration of oxidants in the polishing composition of 0.001 mol / L or less (preferably 0.0005 mol / L or less, more preferably 0.0001 mol / L or less, further preferably 0.00005 mol / L or less, particularly preferably 0.00001 mol / L or less). In some preferred embodiments, the polishing composition is free of oxidants. The polishing composition disclosed herein may, for example, preferably be implemented in a manner free of any of hydrogen peroxide, sodium persulfate, ammonium persulfate, and sodium dichloroisocyanurate.

[0074] <Method for manufacturing the grinding composition>

[0075] The method for manufacturing the grinding composition disclosed herein uses silica particles, an alkaline compound, a chelating agent, and water as described above, and may further use any other ingredients as needed. The manufacturing method includes: preparing an alkaline liquid containing a chelating agent; and mixing the liquid containing the chelating agent with a silica dispersion.

[0076] (Liquid containing chelating agents)

[0077] The aforementioned liquid containing a chelating agent comprises an alkaline compound, water, and a chelating agent. The alkaline compound contained in the liquid containing the chelating agent may be a portion of, or substantially all of, the alkaline compounds used in the manufacture of the grinding composition (i.e., the alkaline compounds contained in the manufactured grinding composition) (e.g., 97% or more, 99% or more, or 100% by weight of the total alkaline compounds contained in the grinding composition). The aforementioned portion may be, for example, 1% or more, 5% or more, 10% or more, 25% or more, 35% or more, 50% or more, 75% or more, 85% or more, or 95% or more of the alkaline compounds used in the manufacture of the grinding composition. In the manufacture of a grinding composition containing multiple alkaline compounds, the alkaline compounds contained in the aforementioned liquid containing the chelating agent may be all types of alkaline compounds used in the manufacture of the aforementioned grinding composition, or only a portion of them. In addition, the liquid containing the chelating agent may contain a portion of a certain type of alkaline compound used in the manufacture of the grinding composition, or it may contain substantially all of a certain type, a combination thereof, or all of all types.

[0078] Without including a portion of the type and / or a portion of the alkaline compound used in the manufacture of the grinding composition in the liquid containing the chelating agent, the remaining alkaline compound may, for example, be added to the mixture of the liquid containing the chelating agent and the silica dispersion after mixing, or may be mixed with the liquid containing the chelating agent as a component of the silica dispersion.

[0079] The pH of the liquid containing the chelating agent (the pH before mixing with the silica dispersion, sometimes referred to below as "pH"). ch The pH of the chelating agent-containing liquid is above 7, for example, it can be 8 or higher. In some cases, a pH of 9 or higher is suitable, 10 or higher is advantageous, 10.5 or higher is preferred, 11 or higher is more preferred, 11.5 or higher, 12 or higher, or 12.5 or higher. From the viewpoint of the solubility of the chelating agent contained in the chelating agent-containing liquid, it is preferable to increase the pH of the chelating agent-containing liquid. There is no particular upper limit to the pH of the chelating agent-containing liquid, which is usually 14 or lower. As long as the chelating agent can be sufficiently and well dissolved, the pH of the chelating agent-containing liquid can be, for example, 13.5 or lower, 13 or lower, 12 or lower, or 11 or lower. The pH of the chelating agent-containing liquid can be adjusted by the type and concentration of the components (especially alkaline compounds) contained in the chelating agent-containing liquid. The pH of the chelating agent-containing liquid is determined in the same manner as the pH of the grinding composition described later.

[0080] In some methods, the pH of the liquid containing the chelating agent (pH) ch The pH of the resulting product (hereinafter also referred to as "pH") made using the liquid containing the chelating agent can be higher than that of the grinding composition. R This is advantageous from the viewpoint of the ease of preparing chelating agent-containing liquids, where the chelating agent dissolves well. pH ch With pH R Difference (pH) ch -pH R For example, it can be 0.1 or more, usually 0.5 or more is appropriate, preferably 1 or more, more preferably 1.5 or more, can be 2 or more, can be 2.5 or more, can be 3 or more.

[0081] In some methods of using a chelating agent-containing liquid that contains a chelating agent as an n-valent (n≥2) acid, from the viewpoint of the solubility of the chelating agent, the pH of the chelating agent-containing liquid (pH...) ch Preferably, the pKa of the chelating agent is higher than that of the chelating agent mentioned above. n-1 (i.e., preferably satisfying pH) ch >pKa n-1 More preferably, the pKa of the chelating agent is higher than that of the chelating agent. n .

[0082] The content of the alkaline compound in the chelating agent-containing liquid can be determined by considering the type of alkaline compound and ensuring that the pH of the chelating agent-containing liquid is within an appropriate range. For example, it can be set to a range of approximately 0.001% to 25% by weight. In some embodiments, it is appropriate to set the content of the alkaline compound in the chelating agent-containing liquid to 0.005% by weight or more. From the viewpoint of promoting the dissolution of the chelating agent, setting it to 0.01% by weight or more is advantageous, preferably 0.05% by weight or more, more preferably 0.1% by weight or more, and can be set to 0.2% by weight or more. In other embodiments, it is appropriate to set the content of the alkaline compound in the chelating agent-containing liquid to, for example, 15% by weight or less, preferably 10% by weight or less, and can be set to 8% by weight or less, 6% by weight or less, 4% by weight or less, 2% by weight or less, or 1% by weight or less.

[0083] Furthermore, in the manufacture of a grinding composition (i.e., a concentrated solution) for dilution and grinding, in some embodiments, the content of the alkaline compound in the chelating agent-containing liquid used in the manufacture of the concentrated solution is, for example, 0.1% by weight or more, preferably 0.3% by weight or more, and can be 1% by weight or more or 2% by weight or more. Additionally, the content of the alkaline compound in the chelating agent-containing liquid used in the manufacture of the concentrated solution can be, for example, 25% by weight or less, 24% by weight or less, 20% by weight or less, or 15% by weight or less.

[0084] The chelating agent contained in the liquid containing the chelating agent described above can be a portion of the chelating agent used in the manufacture of the grinding composition, or it can be substantially all of the chelating agent (e.g., 97% or more, 99% or more, or 100% by weight of the total chelating agent contained in the grinding composition). From the viewpoint of improving the effect of the application of the present invention, it is preferable that 80% or more, preferably 90% or more, and more preferably substantially all of the chelating agent contained in the grinding composition is contained in the liquid containing the chelating agent. Therefore, for at least a majority of the chelating agent used in the manufacture of the grinding composition, the degree of solubility of the chelating agent can be easily confirmed before the system becomes turbid due to mixing with the silica dispersion. The degree of solubility of the chelating agent can be confirmed, for example, by visually observing the liquid containing the chelating agent.

[0085] The content of the chelating agent in the liquid containing the chelating agent can be determined by considering the target concentration of the chelating agent in the manufactured grinding composition and the solubility of the chelating agent, and is not particularly limited. In some embodiments, the content of the chelating agent in the liquid containing the chelating agent may be set to 0.005 mM or more, and in some embodiments, preferably 0.01 mM or more, more preferably 0.05 mM or more, for example, 0.1 mM or more, 0.3 mM or more, 0.7 mM or more, 1.0 mM or more, 1.5 mM or more, or 2.0 mM or more. In addition, the content of the chelating agent in the liquid containing the chelating agent may be set to 500 mM or less, for example. From the viewpoint of easily achieving a good solubility state of the chelating agent, in some embodiments, setting it to 150 mM or less is appropriate, preferably 100 mM or less, more preferably 50 mM or less, 30 mM or less, 10 mM or less, or 5 mM or less.

[0086] Furthermore, in some methods of manufacturing a grinding composition (i.e., a concentrated solution) for dilution and grinding, the content of the chelating agent in the liquid containing the chelating agent can be, for example, 0.01 mM or more, preferably 0.05 mM or more, more preferably 0.1 mM or more, 0.5 mM or more, 1 mM or more, 3 mM or more, or 5 mM or more. Additionally, the content of the chelating agent in the liquid containing the chelating agent used in the manufacture of the above-mentioned concentrated solution can be, for example, 1000 mM or less. From the viewpoint of easily achieving a good dissolution state of the chelating agent, in some methods, setting it to 700 mM or less is appropriate, preferably 500 mM or less, more preferably 300 mM or less, 200 mM or less, 100 mM or less, 50 mM or less, 30 mM or less, 20 mM or less, or 10 mM or less.

[0087] From the viewpoint of easily confirming the degree of solubility of the chelating agent, the content of silica particles in the chelating agent-containing liquid is preferably limited. In the chelating agent-containing liquid used to manufacture a grinding composition that combines silica particles and particles other than silica as abrasives, the total content of the silica particles and the particles other than silica is preferably limited; that is, the chelating agent-containing liquid in the manufacturing method disclosed herein preferably limits the content of abrasive particles. In some embodiments, it is appropriate for the content of abrasive particles in the chelating agent-containing liquid to be less than 0.005% by weight, preferably less than 0.001% by weight, more preferably less than 0.0005% by weight, and even more preferably less than 0.0001% by weight. In some preferred embodiments, the chelating agent-containing liquid does not contain abrasive particles.

[0088] Liquids containing chelating agents can be prepared by mixing a basic compound, water, and the chelating agent. The order of mixing is not particularly limited; for example, the chelating agent can be added to a mixture of the basic compound and water, or the basic compound can be added to a mixture of the chelating agent and water. Here, a mixture of a component and water refers to an aqueous solution or aqueous dispersion containing that component. Each component can be added individually or as a mixture with other components (e.g., water). Additionally, it can be added simultaneously with two or more components.

[0089] (Silica dispersion)

[0090] Silica dispersions comprise silica particles and water. From the viewpoint of ease of preparation and miscibility with other components, the silica particle content in the silica dispersion is typically 50% by weight or less, preferably 45% by weight or less, and can be 40% by weight or less, 35% by weight or less, 30% by weight or less, 20% by weight or less, 10% by weight or less, or 5% by weight or less. Furthermore, the lower limit of the silica particle content in the silica dispersion is set in a way that the desired silica particle content is obtained in the manufactured grinding composition, and is generally appropriate to be equal to or greater than the silica particle content in the aforementioned grinding composition. For example, in the manufacture of a grinding composition (i.e., a concentrate) for grinding after dilution, the silica particle content in the silica dispersion is preferably more than 1% by weight, more preferably more than 5% by weight, and can be 10% by weight or more, or 15% by weight or more.

[0091] The pH of the silica dispersion (the pH before mixing with the liquid containing the chelating agent). SiFor example, the pH can be 6 or higher. From the perspective of the dispersion stability of silica particles, a pH of 6.4 or higher is generally suitable. From the viewpoint of easily maintaining the pH of the mixture with the chelating agent-containing liquid as alkaline, a pH of 7 or higher (e.g., exceeding 7) is preferred. In some embodiments, the pH of the silica dispersion can be, for example, 7.5 or higher, 8 or higher, 9 or higher, 10 or higher, 11 or higher, or 12 or higher. Furthermore, the pH of the silica dispersion can be, for example, 14 or lower. From the viewpoint of inhibiting the dissolution of silica particles, a pH of 13.5 or lower is preferred, more preferably 13 or lower, 12.5 or lower, 11.5 or lower, 10.5 or lower, 9.5 or lower, or 8.5 or lower. The pH of the silica dispersion is measured in the same manner as the pH of the grinding composition described later.

[0092] pH of liquids containing chelating agents ch pH of silica dispersion Si The relationship is not specifically limited and can be pH. ch <pH Si It can also be pH ch pH Si It can also be used for pH ch =pH Si From the viewpoint of better utilizing the advantages of pre-preparing a chelating agent-containing liquid containing at least a portion of chelating agents and basic compounds before mixing with a silica dispersion, in some ways, the difference (pH) ch -pH Si A value of 0.1 or higher is appropriate, preferably 0.5 or higher, more preferably 1 or higher, even more preferably 1.5 or higher, and can be 2 or higher, 3 or higher, or 4 or higher.

[0093] The mixing of the chelating agent-containing liquid and the silica dispersion can be carried out by adding the silica dispersion to the chelating agent-containing liquid, by adding the chelating agent-containing liquid to the silica dispersion, or by adding both simultaneously. When manufacturing a grinding composition containing any of the components described above (e.g., water-soluble polymers, surfactants, etc.), each component may be contained in the chelating agent-containing liquid, in the silica dispersion, added after mixing the chelating agent-containing liquid and the silica dispersion, or added simultaneously with the mixing of the chelating agent-containing liquid and the silica dispersion.

[0094] The preparation of the chelating agent-containing liquid and the silica dispersion, the mixing of the chelating agent-containing liquid and the silica dispersion, and the addition of other components can be carried out by known methods using known mixing devices such as blade mixers, ultrasonic dispersers, and homogenizers.

[0095] <Grinding Composition>

[0096] The grinding composition manufactured by the methods disclosed herein is supplied to the grinding object, for example, in the form of a grinding slurry (working slurry) containing the grinding composition, for grinding the grinding object. The grinding slurry may be, for example, a grinding slurry prepared by diluting (e.g., diluting with water) a concentrate of the grinding composition manufactured by any of the methods disclosed herein. Alternatively, the grinding composition may be used directly as a grinding slurry. The concentration ratio of the concentrate may be, for example, about 2 to 140 times by volume, and typically about 5 to 80 times is suitable.

[0097] The pH of the grinding composition is, for example, 8.0 or higher, preferably 8.5 or higher, more preferably 9.0 or higher, even more preferably 9.5 or higher, and can be 10.0 or higher (e.g., 10.5 or higher). A higher pH tends to increase the grinding rate. On the other hand, from the viewpoint of preventing the dissolution of abrasive particles (e.g., silica particles) and suppressing the reduction in the mechanical grinding effect caused by these particles, the pH of the grinding composition is generally suitable to be 12.0 or lower, preferably 11.8 or lower, and more preferably 11.5 or lower. These pH values ​​can preferably be applied to either the pH of the grinding fluid (working slurry) supplied to the object being ground or its concentrate.

[0098] It should be noted that the pH of the grinding composition can be determined as follows: using a pH meter (e.g., a glass electrode hydrogen ion concentration indicator (model F-23) manufactured by Horiba Corporation), after three-point calibration using standard buffer solutions (phthalate pH buffer pH: 4.01 (25°C), neutral phosphate pH buffer pH: 6.86 (25°C), and carbonate pH buffer pH: 10.01 (25°C)), the glass electrode is placed in the grinding composition, and the value is measured after stabilization for more than 2 minutes.

[0099] The grinding composition disclosed herein can be a single dosage form or a multi-dosage form, primarily a two-dosage form. For example, it can be configured as follows: a portion A containing at least abrasive particles and a portion B containing the remaining components are mixed and diluted as needed at an appropriate time to prepare a grinding slurry. The aforementioned portion A can be, for example, the aforementioned silica dispersion or a concentrated solution used as a silica dispersion after dilution. The aforementioned portion B can be, for example, the aforementioned liquid containing a chelating agent or a concentrated solution used as a liquid containing a chelating agent after dilution. Portions A and B can be mixed independently after dilution, pH adjustment, or the addition of other components, or the aforementioned treatment can be performed after mixing portions A and B.

[0100] <Grinding>

[0101] The abrasive composition manufactured by the methods disclosed herein can, for example, be used for abrasive objects in a manner including the following operations.

[0102] That is, a working slurry containing the above-described grinding composition is prepared. Next, the grinding composition is supplied to the object to be ground, and grinding is performed using conventional methods. For example, the object to be ground is placed in a general grinding apparatus, and the grinding composition is supplied to the surface of the object to be ground (the surface to be ground) through the grinding pad of the grinding apparatus. For example, while continuously supplying the above-described grinding composition, the grinding pad is pressed against the surface of the object to be ground, causing the two to move relative to each other (e.g., rotate). After this grinding process, the grinding of the object to be ground is completed.

[0103] The abrasive pad used in the above-described polishing process is not particularly limited. For example, any type can be used, such as polyurethane foam type, non-woven fabric type, suede type, type containing abrasive particles, or type without abrasive particles. In some preferred embodiments, an abrasive pad without abrasive particles is used. Furthermore, as the above-described polishing apparatus, a double-sided polishing apparatus that polishes both sides of the object simultaneously can be used, or a single-sided polishing apparatus that polishes only one side of the object can be used.

[0104] The above-mentioned grinding composition can be used in a manner that discards it once it has been used for grinding (so-called "flushing"), or it can be recycled and reused. As an example of a method for recycling the grinding composition, the following method can be listed: the used grinding composition discharged from the grinding device is recovered into a tank, and the recovered grinding composition is supplied back to the grinding device.

[0105] <Application>

[0106] The polishing composition manufactured by the method disclosed herein is used for polishing surfaces formed of silicon material, preferably for pre-polishing surfaces formed of silicon material. The silicon material preferably comprises at least one material selected from the group consisting of monocrystalline silicon, amorphous silicon, and polycrystalline silicon. The polishing composition described above is particularly suitable for polishing surfaces formed of monocrystalline silicon (e.g., silicon wafers). The polishing composition described above can also be applied to polishing surfaces containing surfaces with HLM (Highly Movable Metallic Lamination). The polishing composition disclosed herein is particularly preferred for use in pre-polishing processes, more specifically as the initial polishing process in polishing processes (primary polishing processes), and subsequent intermediate polishing processes (secondary polishing processes).

[0107] For the silicon wafers described above, before the polishing process using the polishing composition disclosed herein, grinding, etching, and the application of the aforementioned HLM can be performed, which are common processes applicable to silicon wafers.

[0108] The aforementioned silicon wafer, for example, has a surface formed of silicon. Such a silicon wafer is preferably a monocrystalline silicon wafer, such as a monocrystalline silicon wafer obtained by slicing a monocrystalline silicon ingot. The polishing composition disclosed herein is suitable for polishing monocrystalline silicon wafers with HLM (High-Performance Mixture).

[0109] In addition, the grinding composition disclosed herein can also be suitably used for grinding objects that do not have HLM.

[0110] The matters disclosed in this specification include the following.

[0111] [1] A method for manufacturing an abrasive composition, comprising:

[0112] Prepare an alkaline liquid containing a basic compound, water, and a chelating agent; and

[0113] The silica dispersion containing silica particles and water is mixed with the liquid containing the chelating agent described above.

[0114] [2] According to the manufacturing method described in [1] above, the pH of the silica dispersion mixed with the liquid containing the chelating agent is 6 or more and 14 or less.

[0115] [3] According to the manufacturing method described in [1] or [2] above, wherein the chelating agent is an acid with an n-valent (wherein n≥2) acid,

[0116] The acid dissociation constants pKa of the above chelating agents are assigned as pKa1…pKa in ascending order of their numerical values. n At that time, pKa n-1 Greater than 7.0.

[0117] [4] The manufacturing method according to any one of [1] to [3] above, wherein the chelating agent comprises a chelating agent with a valence of 5 or more.

[0118] [5] The manufacturing method according to any one of [1] to [4] above, wherein the above-mentioned polishing composition is a polishing composition for pre-polishing the surface formed of silicon material.

[0119] [6] The manufacturing method according to any one of [1] to [5] above includes: before mixing the silica dispersion with the liquid containing the chelating agent, controlling the degree of solubility of the chelating agent in the liquid containing the chelating agent.

[0120] [7] A grinding composition, which is manufactured by any one of the manufacturing methods described in [1] to [6] above.

[0121] The following describes several embodiments of the present invention, but it is not intended to limit the present invention to the contents shown in these embodiments.

[0122] <List of Abbreviations>

[0123] [Basic compounds]

[0124] TMAH: Tetramethylammonium hydroxide

[0125] KOH: Potassium hydroxide

[0126] K2CO3: Potassium carbonate

[0127] Chelating agent (acid valence, pKa) n-1 )]

[0128] EDTPO: Ethylenediaminetetra(methylenephosphonic acid) (8-valent, 9.22)

[0129] DTPA: Diethylenetriaminepentaacetic acid (5-valent, 8.6%)

[0130] TTHA: Triethylenetetraminehexaacetic acid (hexavalent, 9.4%)

[0131] EDDHA: Ethylenediamine di[(2-hydroxyphenyl)acetic acid] (tetravalent, 10.7)

[0132] EDTA: Ethylenediaminetetraacetic acid (tetravalent, 6.16)

[0133] A SP Aspartic acid (2-valent, 3.9%)

[0134] HEDP: 1-Hydroxyethionyl-1,1-diphosphonic acid (tetravalent, 6.9%)

[0135] Experiment Example 1

[0136] <Preparation of Grinding Compositions>

[0137] (Example 1)

[0138] An alkaline liquid containing TMAH at 0.35 wt% and EDTPO at 2.62 mM was prepared by mixing TMAH with an aqueous solution of EDTPO.

[0139] A silica dispersion (hereinafter referred to as "silica dispersion A") containing sol-gel silica (average secondary particle size 49 nm) as silica particles at pH 7.5 and K2CO3 were sequentially added to the chelating agent liquid and mixed to produce a grinding composition having a final composition of 2% by weight of silica particles, 0.3% by weight of TMAH, 2% by weight of K2CO3, and 2.25 mM of EDTPO.

[0140] (Example 2)

[0141] An alkaline liquid containing TMAH at a content of 0.35% by weight and EDTPO at a content of 2.62 mM was prepared by adding an aqueous solution of TMAH to a mixture of EDTPO and water and mixing.

[0142] Silica dispersion A and K2CO3 were added sequentially to the liquid containing the chelating agent and mixed to produce a grinding composition with the same final composition as in Example 1.

[0143] (Example 3)

[0144] K2CO3 was added to an aqueous solution of TMAH, followed by the addition of EDTPO for mixing, thereby preparing an alkaline liquid containing chelating agent with a content of 0.33 wt% TMAH, 2.2 wt% K2CO3, and 2.47 mM EDTPO.

[0145] Add silica dispersion A to the liquid containing the chelating agent and mix to produce a grinding composition with the same final composition as in Example 1.

[0146] (Example 4)

[0147] An aqueous solution of TMAH was added to a mixture of K2CO3 and water, followed by the addition of EDTPO for mixing, thereby preparing an alkaline liquid containing chelating agent with a content of 0.33 wt% TMAH, 2.2 wt% K2CO3, and 2.47 mM EDTPO.

[0148] Add silica dispersion A to the liquid containing the chelating agent and mix to produce a grinding composition with the same final composition as in Example 1.

[0149] (Example 5)

[0150] An alkaline chelating agent-containing liquid containing 0.17% by weight of TMAH and 2.49 mM of EDTPO was prepared by mixing TMAH with an aqueous solution of EDTPO.

[0151] A grinding composition is prepared by sequentially adding silica dispersion A and an aqueous solution of TMAH to the liquid containing the chelating agent and mixing them, thereby producing a final composition containing silica particles at a content of 2% by weight, TMAH at a content of 0.3% by weight, and EDTPO at a content of 2.25 mM.

[0152] (Example 6)

[0153] An alkaline liquid containing TMAH at a concentration of 0.33 wt% and EDTPO at a concentration of 2.47 mM was prepared by mixing TMAH with an aqueous solution of EDTPO.

[0154] Add silica dispersion A to the liquid containing the chelating agent and mix to produce a grinding composition with the same final composition as in Example 5.

[0155] (Example 7)

[0156] An alkaline chelating agent liquid containing TMAH at a concentration of 0.33 wt% and EDTPO at a concentration of 2.47 mM was prepared by mixing an aqueous solution of TMAH into a mixture of EDTPO and water.

[0157] Add silica dispersion A to the liquid containing the chelating agent and mix to produce a grinding composition with the same final composition as in Example 5.

[0158] (Example 8)

[0159] An alkaline liquid containing chelating agent, comprising 0.17 wt% TMAH and 2.48 mM EDTPO, was prepared by mixing an aqueous solution of TMAH with EDTPO. Additionally, an aqueous solution of TMAH was added to a silica dispersion containing sodium silicate silica (average secondary particle size 71 nm) as silica particles, and the mixture was then mixed to prepare a silica dispersion with pH 13.0, comprising 2.9 wt% TMAH and 39 wt% silica particles (hereinafter referred to as "Silica Dispersion B").

[0160] A grinding composition is prepared by sequentially adding silica dispersion B and K2CO3 to the above-mentioned liquid containing chelating agent and mixing them, thereby producing a grinding composition having a final composition of silica particles at a content of 2% by weight, TMAH at a content of 0.3% by weight, K2CO3 at a content of 2% by weight, and EDTPO at a content of 2.25 mM.

[0161] (Example 9)

[0162] An alkaline liquid containing chelating agent, comprising 0.18 wt% TMAH and 2.64 mM EDTPO, was prepared by mixing an aqueous solution of TMAH with EDTPO. Additionally, an aqueous solution of TMAH was added to a silica dispersion containing sol-gel silica (average secondary particle size 35 nm) as silica particles, and the mixture was then mixed to prepare a silica dispersion with pH 13.0, comprising 1.4 wt% TMAH and 19 wt% silica particles (hereinafter referred to as "Silica Dispersion C").

[0163] A grinding composition is prepared by sequentially adding silica dispersion C and K2CO3 to the above-mentioned liquid containing chelating agent and mixing them, thereby producing a final composition comprising silica particles at a content of 2% by weight, TMAH at a content of 0.3% by weight, K2CO3 at a content of 2% by weight, and EDTPO at a content of 2.25 mM.

[0164] (Comparative Examples 1-6)

[0165] A grinding composition with the same final composition as in Example 1 was prepared by mixing silica dispersion A, TMAH, K2CO3 and EDTPO in the order shown in Table 1.

[0166] (Compare Examples 7 and 8)

[0167] A grinding composition with the same final composition as in Example 5 was prepared by mixing silica dispersion A, TMAH and EDTPO in the order shown in Table 1.

[0168] <Evaluation>

[0169] (Visualization of chelating agent dissolution)

[0170] During the manufacturing process of the grinding compositions in each embodiment and comparative example, the degree of dissolution of the chelating agent was evaluated to see if it could be visually confirmed. The results are shown in Table 1.

[0171] [Table 1]

[0172] Table 1

[0173] As shown in Table 1, in Examples 1 to 9, by visually observing the liquids containing chelating agents prepared in each example, it can be fully confirmed that the chelating agent is well soluble in the liquid containing the chelating agent (visibility: ○).

[0174] It should be noted that, as in Example 10, after performing the same steps as in Example 1 until K2CO3 was mixed, polyvinylpyrrolidone (PVP) with a weight-average molecular weight of 17,000 was further added and mixed, thereby producing a grinding composition having a final composition comprising silica particles at 2% by weight, TMAH at 0.3% by weight, K2CO3 at 2% by weight, EDTPO at 2.25 mM, and PVP at 0.005% by weight. At this time, as in Example 1, by visually observing the liquid containing the chelating agent, it can be sufficiently confirmed that the chelating agent is well dissolved (visibility: ○).

[0175] On the other hand, in Comparative Examples 1 to 8, where a chelating agent was added to a silica dispersion or a mixture of the silica dispersion and an alkaline compound without prior preparation of an alkaline chelating agent-containing liquid, the presence of silica particles hindered the visibility of the degree of dissolution of the added chelating agent (visibility: ×). Furthermore, as Comparative Example 9, the amount of silica dispersion A used was reduced to 0.5% by weight (1 / 4 of the content in Comparative Example 1), and the grinding composition was prepared in the same manner as in Comparative Example 1. It was confirmed that in Comparative Example 9, the presence of silica particles also hindered the visibility of the degree of dissolution of the chelating agent.

[0176] Experiment Example 2

[0177] <Preparation of Grinding Compositions>

[0178] (Examples 11-16)

[0179] Alkaline chelating liquids containing TMAH at 0.35% by weight and chelating agent at 2.62 mM were prepared in the same manner as in Example 1, except that the chelating agents shown in Table 2 were used instead of EDTPO.

[0180] A grinding composition is prepared by sequentially adding silica dispersion A and K2CO3 to the chelating agent-containing liquid and mixing them, thereby producing a final composition containing silica particles at a content of 2% by weight, TMAH at a content of 0.3% by weight, K2CO3 at a content of 2% by weight, and a chelating agent at a content of 2.25 mM.

[0181] (Comparative Example 10)

[0182] Except that no chelating agent is used, the same procedure as in Comparative Example 1 is followed to manufacture a grinding composition comprising silica particles, 0.3% TMAH, and K2CO3 in a final composition of 2% by weight.

[0183] <Evaluation>

[0184] (Visualization of chelating agent dissolution)

[0185] During the manufacture of the grinding compositions in Examples 11-16, the degree of dissolution of the chelating agent was evaluated visually, similar to that in Experimental Example 1. The results are shown in Table 2.

[0186] (Prevents metal contamination)

[0187] By adding a Cu standard solution (an aqueous solution of Cu·HNO3, concentration 1000 mg / L) or a Ni standard solution (an aqueous solution of Ni·HNO3, concentration 1000 mg / L) to the polishing compositions prepared in Examples 1, 11-16 and Comparative Example 10, the compositions contained 500 ppb of Cu or 500 ppb of Ni were prepared. Using this Cu- or Ni-containing polishing composition as the polishing slurry, the surface of the object to be polished (test piece) was polished under the following conditions, followed by cleaning under the following conditions. As the test piece, a commercially available single-crystal silicon wafer (conductive type: P-type) with a diameter of 150 mm that had undergone polishing and etching was used.

[0188] [Grinding conditions]

[0189] Grinding device: Product name "SPM-15" manufactured by Nachi-Fujikoshi Machinery Industry Co., Ltd.

[0190] Abrasive pad: Manufactured by Nitta Haas Incorporated, trade name "MH-S15A"

[0191] Platform speed: 38 rpm

[0192] Grinding pressure: 31.2 kPa

[0193] Grinding time: 20 minutes

[0194] Polishing slurry supply rate: 8L / min (for a total of 40L of polishing slurry used in circulation)

[0195] Maintain grinding environment temperature: 20℃

[0196] [Cleaning conditions]

[0197] The test piece was removed from the grinding apparatus and immersed for 5 minutes in a cleaning tank containing SC-1 cleaning solution (31% hydrogen peroxide water: 29% ammonia water: water = 1:1:10 (volume ratio)). Then, it was immersed for 5 minutes in a cleaning tank containing ultrapure water. This was repeated twice, once more in a cleaning tank containing SC-1 cleaning solution, and then again in a cleaning tank containing ultrapure water. Finally, it was immersed for 5 minutes in a cleaning tank containing SC-2 cleaning solution (31% hydrogen peroxide water: 37% hydrogen chloride water: water = 1:1:6.6 (volume ratio)), and then again in a cleaning tank containing ultrapure water. The sample was then dried using a rotary dryer. The temperature of both SC-1 and SC-2 cleaning solutions was 83°C.

[0198] The test pieces, after being ground and cleaned under the above conditions, were subjected to heat treatment at 200°C for 48 hours. Then, the natural oxide film on the surface of the test pieces was decomposed in the gas phase using hydrofluoric acid vapor, and recovered using a solution containing hydrofluoric acid and hydrogen peroxide.

[0199] Quantitative analysis of metallic impurities in the recovered drug solution was performed using inductively coupled plasma mass spectrometry (ICP-MS4500), and the surface area of ​​the test piece per 1 cm² was determined. 2 The detection amount of each analyte metal (Cu or Ni) [atm / cm] 2 Based on this value, the resistance to metal contamination was evaluated according to the following five levels. The results are shown in Table 2. It should be noted that in Comparative Example 10, the quantitative analysis of the amount of Cu contained in the recovered solution was overloaded, and the amount of Cu could not be determined. Therefore, this column in Table 2 shows "Unable to determine".

[0200] A: Less than 1×10 11 atm / cm 2

[0201] B: 1×10 11 atm / cm 2 Above and less than 5×10 11 atm / cm 2

[0202] C: 5×10 11 atm / cm 2 Above and less than 50×10 11 atm / cm 2

[0203] D: 50×10 11 atm / cm 2 Above and less than 500×10 11 atm / cm 2

[0204] E: 500×10 11 atm / cm 2 above

[0205] [Table 2]

[0206] Table 2

[0207]

[0208] As shown in Table 2, in Examples 11-16, visual observation of the chelating agent-containing liquids prepared in each example sufficiently confirmed that the chelating agent dissolved well in the chelating agent-containing liquid, similar to that in Example 1 (visibility: ○). Furthermore, the grinding compositions prepared in Examples 1, 11-16 exhibited significantly higher resistance to metal contamination compared to the grinding composition prepared in Comparative Example 10 without using a chelating agent. Specifically, the grinding compositions prepared in Examples 1, 11-13 showed high resistance to metal contamination, while the grinding compositions prepared in Examples 1, 11-12 showed particularly high resistance to metal contamination.

[0209] Experiment Example 3

[0210] <Preparation of Grinding Composition (Concentrate)>

[0211] (Example 17)

[0212] An alkaline liquid containing chelating agent, comprising 2.84 wt% TMAH and 6.51 mM EDTPO, was prepared by mixing an aqueous solution of TMAH with EDTPO. Additionally, an aqueous solution of TMAH was added to a silica dispersion containing sodium silicate-processed silica (average secondary particle size 71 nm) as silica particles, and the mixture was then mixed to prepare a silica dispersion with pH 13.0, comprising 1.1 wt% TMAH and 42 wt% silica particles (hereinafter referred to as "Silica Dispersion D").

[0213] A grinding composition (concentrate) is prepared by sequentially adding silica dispersion D and K2CO3 to the above-mentioned liquid containing chelating agent and mixing them, thereby producing a grinding composition (concentrate) containing silica particles at a content of 30% by weight, TMAH at a content of 1.5% by weight, K2CO3 at a content of 1.2% by weight, and EDTPO at a content of 1.74 mM.

[0214] (Example 18)

[0215] An alkaline chelating agent-containing liquid containing 1.96% by weight of TMAH and 2.4 mM of EDTPO was prepared by mixing TMAH with an aqueous solution of EDTPO.

[0216] A grinding composition (concentrate) is prepared by sequentially adding silica dispersion D and K2CO3 to the chelating agent-containing liquid and mixing them, thereby producing a grinding composition (concentrate) containing silica particles at a content of 25% by weight, TMAH at a content of 1.5% by weight, K2CO3 at a content of 1% by weight, and EDTPO at a content of 1.05 mM.

[0217] (Example 19)

[0218] An alkaline chelating agent liquid containing 14% by weight of TMAH and 92 mM of DTPA was prepared by adding DTPA to an aqueous solution of TMAH and mixing.

[0219] A silica dispersion (silica dispersion A) containing sol-gel silica (average secondary particle size 49 nm) as silica particles at pH 7.5 is added to the chelating agent liquid and mixed to produce a grinding composition (concentrate) containing silica particles at 18% by weight, TMAH at 1.8% by weight, and DTPA at 13 mM.

[0220] (Example 20)

[0221] DTPA was added to an aqueous solution of KOH and mixed to prepare an alkaline liquid containing 12% by weight of KOH and 102 mM of DTPA.

[0222] A silica dispersion A is added to the chelating agent-containing liquid and mixed to produce a grinding composition (concentrate) comprising 18% by weight silica particles, 1.2% by weight KOH, and 11 mM DTPA.

[0223] It should be noted that the pH of the chelating agent-containing liquids prepared in Examples 1 to 20 above is all above 13.

[0224] <Evaluation>

[0225] (Visualization of chelating agent dissolution)

[0226] In the manufacturing process of the grinding compositions (concentrates) of Examples 17-20, the degree of dissolution of the chelating agent was evaluated visually, similar to that in Experimental Example 1. The results are shown in Table 3.

[0227] [Table 3]

[0228] Table 3

[0229]

[0230] As shown in Table 3, in Examples 17-20, by visually observing the liquids containing chelating agents prepared in each example, it can be fully confirmed that the chelating agent is well soluble in the liquid containing chelating agents, just as in Example 1 (visibility: ○).

[0231] It should be noted that the polishing composition (concentrate) manufactured in Examples 17 to 20 can be diluted with ultrapure water to about 20 to 50 times, and the diluted polishing composition can be used directly as a polishing fluid for polishing silicon materials (e.g., pre-polishing of silicon wafers).

[0232] The above description provides detailed examples of the present invention, but these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes technologies obtained by various modifications and alterations to the above-described examples.

Claims

1. A method for manufacturing a polishing composition, the polishing composition being used to polish a surface formed of silicon material, the manufacturing method comprising: Prepare an alkaline liquid containing an alkaline compound, water, and a chelating agent; as well as A silica dispersion containing silica particles and water is mixed with the liquid containing the chelating agent.

2. The manufacturing method according to claim 1, wherein, The silica dispersion mixed with the chelating agent has a pH of 6 or higher and 14 or lower.

3. The manufacturing method according to claim 1 or 2, wherein, The chelating agent is an acid with an n-valent oxidation state, where n ≥ 2. The acid dissociation constants pKa of the chelating agent are set as pKa1…pKa in ascending order of their numerical values. n At that time, pKa n-1 Greater than 7.

0.

4. The manufacturing method according to claim 1 or 2, wherein, The chelating agent comprises a chelating agent with a valence of 5 or higher.

5. The manufacturing method according to claim 1 or 2, wherein, The grinding composition is used to pre-grind the surface formed of silicon material.

6. A grinding composition manufactured by the manufacturing method described in claim 1 or 2.

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