A polishing composition and its preparation method and application

Abstract

The present invention relates to the field of chemical mechanical polishing technology, and specifically to a polishing composition, its preparation method, and application, comprising the following steps: mixing a silica hydrosol, an amino acid or a salt thereof, and a silane coupling agent containing a first group to obtain a dispersion; the first group is selected from one or more of a sulfur-containing group, an epoxy group, an isocyanate group, and an acyloxy group; mixing the dispersion with an oxidant, and heating the mixture at a temperature of 40°C to 70°C to obtain a modified silica hydrosol; and mixing the modified silica hydrosol, an anionic water-soluble polymer, an organic base, and water to obtain a polishing composition. The polishing composition obtained by mixing the modified silica hydrosol obtained by the above-mentioned specific method with an anionic water-soluble polymer, an organic base, and water can greatly reduce DCN defects on the surface of polished silicon wafers.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical mechanical polishing, and in particular to a polishing composition, a preparation method thereof and an application thereof. Background Art

[0002] Chemical-Mechanical Polishing (CMP), also known as chemical mechanical planarization, is a technique used in semiconductor device manufacturing to planarize silicon wafers or other substrate materials during processing. CMP typically utilizes an alkaline silica polishing slurry. The alkali reacts with silicon to form soluble silicates through a chemical corrosion reaction. The adsorption of small, soft, negatively charged SiO2 particles, coupled with mechanical friction between the polishing pad and the silicon wafer, effectively polishes away the reaction products, thereby removing surface damage and contaminants from the wafer. As integrated circuit process nodes continue to shrink, the requirements for substrates are also becoming increasingly stringent. To improve wafer surface quality and reduce surface particle residue, wafer CMP typically involves three steps: rough polishing, intermediate polishing, and fine polishing. Intermediate polishing is the second step in CMP, and its performance directly impacts the surface condition after fine polishing.

[0003] Post-CMP defects on silicon wafers are primarily categorized into three types: particle residue, scratches, and organic residue. Scratches on the wafer surface are irreversible and cannot be removed by CMP cleaning or single-wafer cleaning. Therefore, scratches on the wafer surface are one of the most important parameters affecting wafer yield. Defect detection equipment (such as KLA's SP5) classifies defects based on the angle of incident light: DCO, DIC, and DCN. DCN defects typically represent wide, shallow scratches that directly impact device performance and yield, and in severe cases, can cause circuit breaks or shorts. Given the specific conditions for the fine polishing solution, the impact of the intermediate polishing solution on DCN defects is crucial. Deep scratches on the wafer during the intermediate polishing process can significantly strain the fine polishing repair process. Inadequate fine polishing repairs can easily lead to DCN defects.

[0004] Currently, there is little research on polishing liquid in silicon wafers in China. Therefore, new technologies are needed to reduce the number of DCN defects that occur during the silicon wafer CMP process. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to reduce the number of DCN defects occurring during the CMP process of silicon wafers, thereby providing a polishing composition and a preparation method and application thereof.

[0006] To this end, in a first aspect, the present application provides a method for preparing a polishing composition, comprising the following steps:

[0007] Step S1: mixing silica hydrosol, amino acid or its salt with a silane coupling agent containing a first group to obtain a dispersion; the first group is selected from one or more of a sulfur-containing group, an epoxy group, an isocyanate group, and an acyloxy group;

[0008] Step S2: mixing the dispersion with an oxidant, and heating the mixture at a temperature of 40-70° C. to obtain a modified silica hydrosol;

[0009] Step S3: Mixing the modified silica hydrosol, anionic water-soluble polymer, organic base and water to prepare a polishing composition.

[0010] Furthermore, based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the silica hydrosol is 85%-99.8%.

[0011] Furthermore, based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the amino acid or its salt is 0.009%-5%.

[0012] Furthermore, based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the silane coupling agent containing the first group is 0.009%-5%.

[0013] Furthermore, based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the oxidant is 0.009%-5%.

[0014] Furthermore, based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the silica hydrosol is 86%-97.2%.

[0015] Furthermore, based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the amino acid or its salt is 0.1%-2%.

[0016] Furthermore, based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the silane coupling agent containing the first group is 0.1%-2%.

[0017] Furthermore, based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the oxidant is 0.1%-2%.

[0018] Furthermore, the temperature of the heating treatment is 45-60° C.; and / or the time of the heating treatment is 3-60 min.

[0019] Furthermore, the particle size of the silica hydrosol is 30-120 nm.

[0020] Furthermore, the solid content of the silica hydrosol is 10 wt%-50 wt%.

[0021] Furthermore, the amino acid is selected from one or more of glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, and histidine.

[0022] Furthermore, the sulfur-containing group is selected from one or more of a thiol group, a disulfide group, and a tetrasulfide group.

[0023] Furthermore, the silane coupling agent containing the first group is selected from at least one of 3-mercaptopropyltrimethoxysilane, bis-(3-triethoxysilylpropyl)tetrasulfide, bis-(3-triethoxysilylpropyl)disulfide, γ-(2,3-epoxypropyloxy)propyltrimethoxysilane, γ-(2,3-epoxypropyloxy)propyltriethoxysilane, γ-(2,3-epoxypropyloxy)propylmethyldimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-methacryloxypropyltrichlorosilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, 3-isocyanatopropyltriethoxysilane, and isocyanatepropyltrimethoxysilane.

[0024] Furthermore, the oxidant is selected from at least one of hypochlorous acid and its salts, perchloric acid and its salts, Na2O2, K2O2, MgO2, CaO2, BaO2, hydrogen peroxide, permanganate and its salts, FeCl3, dichromic acid and its salts, periodic acid and its salts, oxygen, and ozone.

[0025] Furthermore, the mass ratio of the modified silica hydrosol to the anionic water-soluble polymer is 5-80:0.01-1.

[0026] Furthermore, the mass ratio of the modified silica hydrosol to the organic base is 5-80:0.5-10.

[0027] Furthermore, the mass ratio of the modified silica hydrosol to water is 5-80:9-95.

[0028] Furthermore, the mass ratio of the modified silica hydrosol to the anionic water-soluble polymer is 10-40:0.1-1.

[0029] Furthermore, the mass ratio of the modified silica hydrosol to the organic base is 10-40:1-5.

[0030] Furthermore, the mass ratio of the modified silica hydrosol to water is 10-40:54-89.

[0031] Further, the organic base is selected from one or more of methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, propylenediamine, butylenediamine, hydroxyethylethylenediamine, diethylenetriamine, monoethanolamine, N-(2-aminoethyl)ethanolamine, hexamethylenediamine, N,N,N',N'-tetramethyl-1,6-hexanediamine, 1-(2-aminoethyl)piperazine, N-methylpiperazine, piperazine, imidazole, methylimidazole, 1,2,4-triazole, 4-amino-1,2,4-triazole, guanidine carbonate, guanidine hydrochloride, guanidine nitrate, tetramethylammonium hydroxide, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium fluoride, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetraethylammonium chloride, tetraethylammonium bromide, and tetraethylammonium fluoride.

[0032] Furthermore, the anionic water-soluble polymer is selected from one or more of polyacrylic acid and its salts, polymethacrylic acid and its salts, anionic polyacrylamide and its salts, polyethylene sulfonic acid and its salts, and polystyrene sulfonic acid and its salts.

[0033] Furthermore, the weight average molecular weight of the anionic water-soluble polymer is 2,000-10,000,000.

[0034] In a second aspect, the present application provides a polishing composition prepared by any of the above-mentioned preparation methods.

[0035] In a third aspect, the present application provides the use of a polishing composition prepared by any of the above-mentioned preparation methods in chemical mechanical polishing of silicon wafers.

[0036] Furthermore, the polishing composition can be used as a medium polishing liquid.

[0037] The technical solution of the present invention has the following advantages:

[0038] 1. The present invention provides a method for preparing a polishing composition, comprising the following steps: mixing a silica hydrosol, an amino acid or a salt thereof, and a silane coupling agent containing a first group to obtain a dispersion; the first group being selected from one or more of a sulfur-containing group, an epoxy group, an isocyanate group, and an acyloxy group; mixing the dispersion with an oxidizing agent and heating the mixture at a temperature of 40°C to 70°C to obtain a modified silica hydrosol; and mixing the modified silica hydrosol, an anionic water-soluble polymer, an organic base, and water to obtain a polishing composition. The polishing composition obtained by mixing the modified silica hydrosol obtained by the above-mentioned specific method with the anionic water-soluble polymer, an organic base, and water can significantly reduce DCN defects on the surface of polished silicon wafers.

[0039] Specifically, during the preparation process of the modified silica hydrosol, the silica hydrosol, an amino acid or a salt thereof, and a silane coupling agent containing a first group are first mixed, and then mixed with an oxidant, and then heated under specific temperature conditions, so that the silane coupling agent and the amino acid modify the surface of the silica particles in the silica hydrosol, and then the surface is oxidized under the above-mentioned temperature conditions.

[0040] During the modification process, the amino groups in the amino acids carry a positive charge, which helps the silane coupling agent adhere to the silica particle surface after hydrolysis. The carboxyl and amino groups in the amino acids can also directly form bonds with the Si-OH groups on the silica particle surface, resulting in adhesion to the silica particle surface. After modification, the oxidant, when heated under the aforementioned temperature conditions, oxidizes the first group of the silane coupling agent (e.g., the mercapto group can be further oxidized to a sulfonic acid group), significantly increasing the negative charge on the silica particle surface and enhancing the electrostatic repulsion between particles. Furthermore, the amino groups in the amino acid molecules attached to the silica particle surface can be oxidized to other groups, such as nitro groups, further increasing the electrostatic repulsion between particles and significantly reducing the number of large particles in the silica sol. Consequently, the combined use of the modified silica hydrosol with anionic water-soluble polymers and organic bases can significantly reduce scratch defects on the silicon wafer surface, specifically DCN defects.

[0041] 2. The preparation method of the polishing composition provided by the present invention can further reduce DCN defects after CMP of silicon wafers by controlling the mass percentage of the silica hydrosol to 85%-99.8%, the mass percentage of the amino acid or its salt to 0.009%-5%, the mass percentage of the silane coupling agent containing the first group to 0.009%-5%, or the mass percentage of the oxidant to 0.009%-5%, based on the total mass of the raw materials used in the modified silica hydrosol. In particular, when the mass percentage of the silica hydrosol to 86%-97.2%, the mass percentage of the amino acid or its salt to 0.1%-2%, the mass percentage of the silane coupling agent containing the first group to 0.1%-2%, or the mass percentage of the oxidant to 0.1%-2%, based on the total amount of the raw materials used in the modified silica hydrosol, the polishing composition can further reduce DCN defects after CMP of silicon wafers.

[0042] 3. The preparation method of the polishing composition provided by the present invention can further reduce DCN defects after CMP of silicon wafers by controlling the heating temperature to 45-60°C or the heating time to 3-60 min, especially 10-30 min.

[0043] 4. The preparation method of the polishing composition provided by the present invention can further reduce DCN defects after CMP of silicon wafers by controlling the mass ratio of the modified silica hydrosol to the anionic water-soluble polymer to 5-80:0.01-1; in particular, controlling the mass ratio of the modified silica hydrosol to the anionic water-soluble polymer to 10-40:0.1-1. DETAILED DESCRIPTION

[0044] The following examples are provided for a better understanding of the present invention and are not intended to limit the best mode of implementation. They do not limit the content and scope of protection of the present invention. Any product identical or similar to the present invention obtained by anyone under the guidance of the present invention or by combining the features of the present invention with other prior arts shall fall within the scope of protection of the present invention.

[0045] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0046] The impact of intermediate polishing on DCN defects is crucial. Deep scratches on silicon wafers during intermediate polishing can place significant strain on fine polishing repairs. Inadequate fine polishing repairs can easily lead to DCN defects. Research on intermediate polishing for silicon wafers is limited in China. Therefore, new technologies are needed to reduce the number of DCN defects during silicon wafer CMP.

[0047] To this end, in a first aspect, the present application provides a method for preparing a polishing composition, comprising the following steps:

[0048] Step S1: mixing silica hydrosol, amino acid or its salt with a silane coupling agent containing a first group to obtain a dispersion; the first group is selected from one or more of a sulfur-containing group, an epoxy group, an isocyanate group, and an acyloxy group;

[0049] Step S2: mixing the dispersion with an oxidant, and heating the mixture at a temperature of 40-70° C. to obtain a modified silica hydrosol;

[0050] Step S3: Mixing the modified silica hydrosol, anionic water-soluble polymer, organic base and water to prepare a polishing composition.

[0051] The polishing composition prepared by mixing the modified silica hydrosol obtained by the above specific method with an anionic water-soluble polymer, an organic base and water can greatly reduce DCN defects on the surface of the polished silicon wafer.

[0052] In the special treatment process of the silica hydrosol of the present invention, there is no specific requirement for the stirring and mixing method, and commonly used liquid stirring methods in the industry can be used, such as magnetic stirring, stirring with a stirring paddle, etc.

[0053] For example, in step S2, the temperature of the heating treatment can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, or 70°C, preferably 45-60°C.

[0054] In some specific embodiments, the heating time is 3-60 min, for example, 3 min, 5 min, 8 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, etc., preferably 10-30 min.

[0055] In some specific embodiments, the particle size of the silica hydrosol is 30-120 nm, for example, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, etc., the particle size is a secondary particle size, and the solid content is 10-50 wt%, for example, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, etc.

[0056] In some specific embodiments, based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the silica hydrosol is 85%-99.8%, the mass percentage of the amino acid or its salt is 0.009%-5%, the mass percentage of the silane coupling agent containing the first group is 0.009%-5%, and the mass percentage of the oxidant is 0.009%-5%.

[0057] In some specific embodiments, based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the silica hydrosol is 85%-99.8%, including but not limited to 85%, 88%, 91%, 94%, 97%, 99%, 99.8%, etc., preferably 86%-97.2%.

[0058] In some specific embodiments, the mass percentage of the amino acid or its salt is 0.009%-5% based on the total mass of the raw materials used in the modified silica hydrosol, including but not limited to 0.009%, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, preferably 0.1-2%.

[0059] In some specific embodiments, the amino acids are selected from one or more of glycine, alanine, valine, leucine, isoleucine, methionine (methionine), proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, and histidine, preferably one or more of glycine, alanine, valine, and leucine.

[0060] In some specific embodiments, the sulfur-containing group is selected from one or more of a thiol group, a disulfide group, and a tetrasulfide group.

[0061] In some specific embodiments, the silane coupling agent containing the first group is selected from at least one of 3-mercaptopropyltrimethoxysilane, bis-(3-triethoxysilylpropyl)tetrasulfide, bis-(3-triethoxysilylpropyl)disulfide, γ-(2,3-epoxypropyloxy)propyltrimethoxysilane, γ-(2,3-epoxypropyloxy)propyltriethoxysilane, γ-(2,3-epoxypropyloxy)propylmethyldimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-methacryloxypropyltrichlorosilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, 3-isocyanatopropyltriethoxysilane, and isocyanatepropyltrimethoxysilane. Preferred are 3-mercaptopropyltrimethoxysilane, γ-(2,3-epoxypropyloxy)propyltrimethoxysilane, γ-methacryloxypropyltrichlorosilane, and isocyanatopropyltriethoxysilane.

[0062] In some specific embodiments, based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the silane coupling agent containing the first group is 0.009%-5%, for example, including but not limited to 0.009%, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, and preferably 0.1-2%.

[0063] In some specific embodiments, the oxidant is selected from at least one of hypochlorous acid and its salts, perchloric acid and its salts, Na2O2, K2O2, MgO2, CaO2, BaO2, hydrogen peroxide, permanganate and its salts, FeCl3, dichromic acid and its salts, periodic acid and its salts, oxygen, and ozone. Preferably, the oxidant is hydrogen peroxide, potassium periodate, or potassium permanganate.

[0064] In some specific embodiments, based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the oxidant is 0.009%-5%, for example, including but not limited to 0.009%, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, preferably 0.1-2%.

[0065] In some specific embodiments, the mass ratio of the modified silica hydrosol to the anionic water-soluble polymer is 5-80:0.01-1, including but not limited to 5:1, 10:0.5, 20:0.1, 80:0.01, and preferably 10-40:0.1-1.

[0066] In some specific embodiments, the mass ratio of the modified silica hydrosol to the organic base is 5-80:0.5-10, including but not limited to 5:10, 10:5, 20:1, 80:0.5, and preferably 10-40:1-5.

[0067] In some specific embodiments, the mass ratio of the modified silica hydrosol to water is 5-80:9-95, including but not limited to 5:95, 10:80, 20:50, 80:5, and preferably 10-40:54-89.

[0068] In some specific embodiments, the organic base is selected from one or more of methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, propylenediamine, butylenediamine, hydroxyethylethylenediamine, diethylenetriamine, monoethanolamine, N-(2-aminoethyl)ethanolamine, hexamethylenediamine, N,N,N',N'-tetramethyl-1,6-hexanediamine, 1-(2-aminoethyl)piperazine, N-methylpiperazine, piperazine, imidazole, methylimidazole, 1,2,4-triazole, 4-amino-1,2,4-triazole, guanidine carbonate, guanidine hydrochloride, guanidine nitrate, tetramethylammonium hydroxide, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium fluoride, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetraethylammonium chloride, tetraethylammonium bromide, and tetraethylammonium fluoride. More preferably, it is tetramethylammonium hydroxide.

[0069] In some specific embodiments, the anionic water-soluble polymer is selected from one or more of polyacrylic acid and its salts, polymethacrylic acid and its salts, anionic polyacrylamide and its salts, polyethylene sulfonic acid and its salts, and polystyrene sulfonic acid and its salts.

[0070] In some specific embodiments, the weight average molecular weight of the anionic water-soluble polymer is 2000-10000000, including but not limited to 2000, 5000, 8000, 10000, 80000, 10000000, preferably 2000-80000.

[0071] In some specific embodiments, the step of adjusting the pH value using a pH adjuster is further included after mixing.

[0072] In the present invention, the pH value of the silicon wafer polishing composition is adjusted to be between 9.5 and 11.5, for example, 9.5, 10.0, 10.5, 11.0, or 11.5, by adding a pH adjuster to the modified silica hydrosol. The pH regulator in the silicon wafer polishing composition is selected from hydrogen chloride, nitric acid, sulfuric acid, phosphoric acid, sodium hydroxide, potassium hydroxide, lithium hydroxide, tetramethylammonium hydroxide, imidazole, N-methylimidazole, 1,2,4-triazole, tetramethylguanidine, formic acid, acetic acid, propionic acid, itaconic acid, succinic acid, tartaric acid, citric acid, maleic acid, glycolic acid, malonic acid, oxalic acid, succinic acid, malic acid, gluconic acid, alanine, glycine, lactic acid, trifluoroacetic acid, ethylenediaminetetraacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid, triethylenediamine, propylenediaminetetraacetic acid, hydroxyethylethylenediamine, hydroxyethylethylenediaminetriacetic acid, pyrophosphoric acid, 2-aminoethylphosphonic acid, 1-hydroxyethyl 1,1-diphosphonic acid, aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid, ethane-1,1-diphosphonic acid, ethane-1,1 ,2-triphosphonic acid, methanehydroxyphosphonic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid or their salts, preferably any one of oxalic acid, hydrogen chloride, potassium hydroxide and tetramethylammonium hydroxide; more preferably potassium hydroxide or oxalic acid.

[0073] In a second aspect, the present application provides a polishing composition prepared by any of the above-mentioned preparation methods.

[0074] In a third aspect, the present application provides the use of a polishing composition prepared by any of the above-mentioned preparation methods in chemical mechanical polishing of silicon wafers.

[0075] In the present application, anionic water-soluble polymers are a class of high molecular weight compounds that can dissolve in aqueous solution and dissociate into negatively charged groups (such as carboxylate ions, sulfonate ions, etc.).

[0076] In the present application, "or its salts" or "and their salts" refers to an acid, a salt of the corresponding acid, or a combination of the two. The salt may be a chemically acceptable salt, such as but not limited to sodium salt, potassium salt or ammonium salt.

[0077] Unless otherwise specified, the raw materials and reagents used in the Examples and Comparative Examples of the present invention were purchased from commercial sources. Unless otherwise specified, the purity was analytical grade or higher.

[0078] Silica hydrosol (also known as "silica sol") is a dispersion of nano-sized silica particles in water.

[0079] Example 1

[0080] This embodiment provides a method for preparing a polishing composition, comprising the following steps:

[0081] Step S1: Add 0.1 kg of glycine and 0.1 kg of 3-mercaptopropyltrimethoxysilane to 10 kg of silica sol (average particle size 60 nm, solid content 40 wt%), and stir thoroughly to obtain dispersion A;

[0082] Step S2: 0.1 kg of hydrogen peroxide (mass percentage concentration is 30%) was added to the dispersion A, and then heated under stirring at 50°C for 20 minutes to obtain a modified silica hydrosol;

[0083] Step S3: Take 2500g of modified silica hydrosol, and add 300g of 25% by mass tetramethylammonium hydroxide aqueous solution, 50g of polyacrylic acid with a weight average molecular weight of 2000, and 100g of oxalic acid in sequence during stirring, and add ionized water to 10kg to obtain a polishing composition.

[0084] Example 2

[0085] This embodiment provides a method for preparing a polishing composition, comprising the following steps:

[0086] Step S1: Add 0.001 kg of alanine and 0.2 kg of γ-(2,3-epoxypropoxy)propyltrimethoxysilane to 10 kg of silica sol (average particle size of 120 nm, solid content of 50 wt%), and stir thoroughly to obtain dispersion A;

[0087] Step S2: adding 0.5 kg of potassium periodate to dispersion A, and then heating the dispersion A under stirring at 40° C. for 3 min to obtain a modified silica hydrosol;

[0088] Step S3: 8000 g of modified silica hydrosol was taken, and 50 g of propylene diamine, 1 g of polymethacrylic acid with a weight average molecular weight of 80,000, and 5 g of potassium hydroxide were added in sequence during stirring, and ionized water was added to 10 kg to obtain a polishing composition.

[0089] Example 3

[0090] This embodiment provides a method for preparing a polishing composition, comprising the following steps:

[0091] Step S1: Add 0.01 kg of valine and 0.01 kg of γ-methacryloxypropyltrichlorosilane to 10 kg of silica sol (average particle size 30 nm, solid content 10 wt%), and stir thoroughly to obtain dispersion A;

[0092] Step S2: adding 0.01 kg of potassium periodate to dispersion A, and then heating the dispersion A under stirring at 45°C for 10 minutes to obtain a modified silica hydrosol;

[0093] Step S3: 500 g of modified silica hydrosol was taken, and 100 g of piperazine, 100 g of anionic polyacrylamide with a weight average molecular weight of 5,000,000, and 50 g of sodium hydroxide were added in sequence during stirring, and ionized water was added to 10 kg to obtain a polishing composition.

[0094] Example 4

[0095] This embodiment provides a method for preparing a polishing composition, comprising the following steps:

[0096] Step S1: 0.2 kg of leucine and 0.001 kg of triethoxypropyl isocyanate were added to 10 kg of silica sol (average particle size of 60 nm, solid content of 40 wt%), and the mixture was stirred thoroughly to obtain dispersion A;

[0097] Step S2: adding 0.2 kg of hypochlorous acid to dispersion A, and then heating the dispersion A under stirring at 60° C. for 30 min to obtain a modified silica hydrosol;

[0098] Step S3: Take 1000 g of modified silica hydrosol, add 1000 g of guanidine hydrochloride, 10 g of polystyrene sulfonic acid with a weight average molecular weight of 10,000, and 200 g of acrylic acid in sequence while stirring, and add deionized water to 10 kg to obtain a polishing composition.

[0099] Example 5

[0100] This embodiment provides a method for preparing a polishing composition, comprising the following steps:

[0101] Step S1: Add 0.5 kg of proline and 0.5 kg of γ-methacryloxypropyltrimethoxysilane to 10 kg of silica sol (average particle size 60 nm, solid content 40 wt%), and stir thoroughly to obtain dispersion A;

[0102] Step S2: adding 0.001 kg of potassium dichromate to dispersion A, and then heating the dispersion under stirring at 70°C for 60 min to obtain a modified silica hydrosol;

[0103] Step S3: 4000 g of modified silica hydrosol was taken, and while stirring, 500 g of 35% tetraethylammonium hydroxide aqueous solution, 5 g of polystyrene sulfonic acid with a weight average molecular weight of 10,000, and 500 g of tartaric acid were added in sequence, and ionized water was added to 10 kg to obtain a polishing composition.

[0104] Comparative Example 1

[0105] This comparative example is substantially the same as Example 1, except that in step S1, 3-mercaptopropyltrimethoxysilane is not added to the silica sol.

[0106] Comparative Example 2

[0107] This comparative example is substantially the same as Example 1, except that, in step S2, no hydrogen peroxide is added to the dispersion A.

[0108] Comparative Example 3

[0109] This comparative example is substantially the same as Example 1, except that no glycine is added to the silica sol in step S1.

[0110] Comparative Example 4

[0111] This comparative example is basically the same as Example 1, except that in step S1, the same mass of malonic acid is used instead of glycine.

[0112] Comparative Example 5

[0113] This comparative example is substantially the same as Example 1, except that, in step S1, γ-aminopropyltrimethoxysilane of the same mass is used instead of 3-mercaptopropyltrimethoxysilane.

[0114] Comparative Example 6

[0115] This comparative example is basically the same as Example 1, except that the treatment temperature of step S2 is different. Specifically, in this comparative example, step S2 is adjusted as follows: 0.2 kg of hypochlorous acid is added to dispersion A, and then stirred at room temperature (25°C) for 30 minutes to obtain a modified silica hydrosol.

[0116] Comparative Example 7

[0117] This comparative example is basically the same as Example 1, except that in step S2, the heating temperature is adjusted to 80°C.

[0118] Comparative Example 8

[0119] This comparative example is basically the same as Example 1, except that no polyacrylic acid is added in step S3.

[0120] Comparative Example 9

[0121] This comparative example is basically the same as Example 1, except that, in step S3, cationic polyacrylamide with a weight average molecular weight of 5,000,000 is used instead of polyacrylic acid with a weight average molecular weight of 2,000.

[0122] Comparative Example 10

[0123] This comparative example provides a method for preparing a polishing composition, comprising the following steps:

[0124] Step S1: Add 0.1 kg of 3-mercaptopropyltrimethoxysilane to 10 kg of silica sol (60 nm, 40 wt%) and stir thoroughly to obtain dispersion A;

[0125] Step S2: 0.1 kg of hydrogen peroxide (mass percentage concentration is 30%) was added to the dispersion A, and then heated under stirring at 50°C for 20 minutes to obtain a modified silica hydrosol;

[0126] Step S3: Take 2500g of modified silica hydrosol, and add 0.1kg of glycine, 300g of 25% by mass tetramethylammonium hydroxide solution, 50g of polyacrylic acid with a weight average molecular weight of 2000, and 100g of oxalic acid in sequence while stirring, and add ionized water to 10kg to obtain a polishing composition.

[0127] Test Case

[0128] To verify the polishing effect of the polishing composition of this application, silicon wafer substrates (with a P100 crystal orientation and a resistivity of 1-100 Ω˙cm) from the same batch were divided into several groups and then subjected to rough polishing, intermediate polishing, and fine polishing processes, respectively. Each group of silicon wafer substrates was subjected to intermediate polishing using the polishing composition of each example and comparative example. The polishing composition could be diluted with deionized water at varying ratios as needed before use. In this experiment, the polishing compositions of the examples and comparative examples were diluted with deionized water at a mass ratio of 1:30. The process parameters for rough polishing, intermediate polishing, and fine polishing are shown in Tables 1 and 2. The rough polishing solution used in the rough polishing process was Glanzox 1306, manufactured by Fujimi Corporation of Japan, at a dilution ratio of 30X. The fine polishing solution used in the fine polishing process was Glanzox 3108, manufactured by Fujimi Corporation of Japan, at a dilution ratio of 30X.

[0129] Table 1 Rough polishing and medium polishing test process and parameters

[0130]

[0131] Table 2 Fine polishing test process and parameters

[0132]

[0133] A KLA SP5 was used to test residual particles on the surface of silicon wafers after fine polishing and cleaning. Only DCN defects 40nm or larger were counted on each wafer after cleaning. Standard RCA cleaning solutions were used. The SC-1 solution had the following volume ratio: ammonia: 30% hydrogen peroxide: water = 1:1:6. The SC-2 solution had the following volume ratio: hydrogen chloride: 30% hydrogen peroxide: water = 1:1:7. The number of particles 40nm or larger remaining on the wafer surface was counted as the DCN defect count. The results are shown in Table 3.

[0134] Table 3 Polishing performance test results of polishing compositions

[0135]

[0136] Comparison of the above data demonstrates that the silicon wafer polishing composition of the present invention can significantly reduce DCN defects 40 nm or larger on the surface of polished silicon wafers. The number of DCN defects on polished silicon wafers in Examples 1-5 is less than 50, demonstrating a significant advantage over Comparative Examples 1-10. Comparison of Example 1 with Comparative Examples 1-3 demonstrates that Example 1 effectively reduces DCN defects on the surface of silicon wafers through the synergistic addition of a silane coupling agent, an amino acid, and an oxidizing agent. Comparison of Example 1 with Comparative Example 4 demonstrates that the silica hydrosol treated with malonic acid instead of amino acids in Comparative Example 4 does not effectively reduce DCN defects on the surface of silicon wafers. Comparison of Example 1 with Comparative Example 5 demonstrates that Example 1 effectively reduces particle residue on the surface of silicon wafers by treating the silica hydrosol with a silane coupling agent containing a primary group such as a mercapto or epoxy group. Comparison of Example 1 with Comparative Examples 6 and 7 demonstrates that Example 1 significantly reduces particle residue on the surface of silicon wafers by controlling the heating temperature of the silica hydrosol treatment within an appropriate range.

[0137] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing a silicon wafer polishing composition, characterized in that: The steps include: Step S1: mixing silica hydrosol, amino acid or its salt with a silane coupling agent containing a first group to obtain a dispersion; the first group is a thiol group; Step S2: mixing the dispersion with an oxidant, and heating the mixture at a temperature of 40° C. to 70° C. to obtain a modified silica hydrosol; Step S3: Mixing the modified silica hydrosol, anionic water-soluble polymer, organic base and water to prepare a silicon wafer polishing composition.

2. The method for preparing the silicon wafer polishing composition according to claim 1, wherein Based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the silica hydrosol is 85%-99.8%; and / or, based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the amino acid or its salt is 0.009%-5%; And / or, based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the silane coupling agent containing the first group is 0.009%-5%; And / or, based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the oxidant is 0.009%-5%.

3. The method for preparing the silicon wafer polishing composition according to claim 2, wherein: Based on the total amount of raw materials used in the modified silica hydrosol, the mass percentage of the silica hydrosol is 86%-97.2%; and / or, based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the amino acid or its salt is 0.1%-2%; And / or, based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the silane coupling agent containing the first group is 0.1%-2%; And / or, based on the total mass of the raw materials used in the modified silica hydrosol, the mass percentage of the oxidant is 0.1%-2%.

4. The method for preparing the silicon wafer polishing composition according to any one of claims 1 to 3, wherein: The temperature of the heating treatment is 45-60° C.; and / or, the time of the heating treatment is 3-60 min; and / or, step S3 further includes the step of adding a pH regulator.

5. The method for preparing the silicon wafer polishing composition according to any one of claims 1 to 3, characterized in that: The particle size of the silica hydrosol is 30-120 nm; and / or, the solid content of the silica hydrosol is 10 wt% to 50 wt%; and / or, the amino acids are selected from one or more of glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, and histidine; and / or, the silane coupling agent containing the first group is selected from 3-mercaptopropyltrimethoxysilane; And / or, the oxidant is selected from at least one of hypochlorous acid and its salts, perchloric acid and its salts, Na2O2, K2O2, MgO2, CaO2, BaO2, hydrogen peroxide, permanganate and its salts, FeCl3, dichromic acid and its salts, periodic acid and its salts, oxygen, and ozone.

6. The method for preparing the silicon wafer polishing composition according to claim 1, wherein: The mass ratio of the modified silica hydrosol to the anionic water-soluble polymer is 5-80:0.01-1; and / or, the mass ratio of the modified silica hydrosol to the organic base is 5-80:0.5-10; And / or, the mass ratio of the modified silica hydrosol to water is 5-80:9-95.

7. The method for preparing the silicon wafer polishing composition according to claim 6, wherein: The mass ratio of the modified silica hydrosol to the anionic water-soluble polymer is 10-40:0.1-1; and / or, the mass ratio of the modified silica hydrosol to the organic base is 10-40:1-5; And / or, the mass ratio of the modified silica hydrosol to water is 10-40:54-89.

8. The method for preparing the silicon wafer polishing composition according to any one of claims 1, 6 or 7, wherein: The organic base is selected from one or more of methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, propylenediamine, butylenediamine, hydroxyethylethylenediamine, diethylenetriamine, monoethanolamine, N-(2-aminoethyl)ethanolamine, hexamethylenediamine, N,N,N',N'-tetramethyl-1,6-hexanediamine, 1-(2-aminoethyl)piperazine, N-methylpiperazine, piperazine, imidazole, methylimidazole, 1,2,4-triazole, 4-amino-1,2,4-triazole, guanidine carbonate, guanidine hydrochloride, guanidine nitrate, tetramethylammonium hydroxide, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium fluoride, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetraethylammonium chloride, tetraethylammonium bromide, and tetraethylammonium fluoride; And / or, the anionic water-soluble polymer is one or more selected from polyacrylic acid and its salts, polymethacrylic acid and its salts, anionic polyacrylamide and its salts, polyethylene sulfonic acid and its salts, polystyrene sulfonic acid and its salts; And / or, the weight average molecular weight of the anionic water-soluble polymer is 2,000-10,000,000.

9. A silicon wafer polishing composition obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the silicon wafer polishing composition prepared by the preparation method according to any one of claims 1 to 8 in chemical mechanical polishing of silicon wafers.

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