Polishing solution for silicon wafers

Abstract

In one embodiment, a polishing liquid for silicon wafers is provided that can improve the wettability of the silicon wafer surface, suppress the residue of abrasive particles, and improve the polishing speed. [Solution] In one embodiment, this disclosure relates to a polishing solution for silicon wafers containing a polyamine-N-oxide having a structure derived from one polyamine selected from polyethyleneimine, polyallylamine, and polydiallylamine, and a structure derived from one or more compounds selected from epoxy group-containing compounds and acrylamide compounds, and abrasive grains.

Description

[Technical Field]

[0001] This disclosure relates to a silicon wafer polishing solution and a method for manufacturing a semiconductor device, which includes a step of polishing a silicon wafer using the silicon wafer polishing solution. [Background technology]

[0002] In recent years, with the increasing demand for higher recording capacity in semiconductor memory, silicon wafers used to manufacture semiconductor memory are required to have not only high flatness but also reduced surface defects.

[0003] Therefore, in order to reduce residues on the silicon wafer surface, which are one of the surface defects, various polishing solutions containing wetting agents have been developed for silicon wafer polishing, with the aim of improving the wettability (hydrophilization) of the silicon wafer surface.

[0004] As an example of a polishing solution technology containing a wetting agent, Patent Document 1 discloses a semiconductor polishing composition that contains abrasive grains and a polyalkylene imine having hydrophilic groups, characterized in that it hydrophilizes the surface of the workpiece after polishing and prevents aggregation of abrasive grains. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2006-196671 [Overview of the project] [Problems that the invention aims to solve]

[0006] In recent years, the increasing demand for semiconductor memory has created a strong need to improve the productivity of silicon wafers. However, with the technologies described above, the wettability of the silicon wafer surface is insufficient, sometimes resulting in abrasive particles remaining on the silicon wafer after polishing. Furthermore, there was room for improvement in the polishing speed.

[0007] Therefore, this disclosure relates to a silicon wafer polishing solution that can improve the wettability of the silicon wafer surface, suppress the residue of abrasive particles, and improve the polishing speed, as well as a method for manufacturing a semiconductor device that includes a step of polishing a silicon wafer using the silicon wafer polishing solution. [Means for solving the problem]

[0008] This disclosure relates, in one aspect, to a polishing solution for silicon wafers, comprising a polyamine-N-oxide having a structure derived from one polyamine selected from polyethyleneimine, polyallylamine, and polydiallylamine, and a structure derived from one or more compounds selected from epoxy group-containing compounds and acrylamide compounds, and abrasive grains.

[0009] This disclosure relates, in one embodiment, to a method for manufacturing a semiconductor device, which includes a step of polishing a silicon wafer using the silicon wafer polishing solution of this disclosure. [Effects of the Invention]

[0010] The silicon wafer polishing solution disclosed herein can improve the wettability of the silicon wafer surface, suppress the residue of abrasive particles, and improve the polishing speed. [Modes for carrying out the invention]

[0011] [Polishing solution for silicon wafers] This disclosure is based on the finding that by using a polishing solution containing a specific polyamine-N-oxide, the wettability of the silicon wafer surface can be improved, the silicon wafer can be made hydrophilic, and the polishing speed can be increased.

[0012] In other words, in one embodiment, this disclosure relates to a silicon wafer polishing solution (hereinafter also referred to as "the polishing solution of this disclosure") containing a polyamine-N-oxide having a structure derived from one polyamine selected from polyethyleneimine, polyallylamine, and polydiallylamine, and a structure derived from one or more compounds selected from epoxy group-containing compounds and acrylamide compounds, and abrasive grains.

[0013] The silicon wafer polishing solution disclosed herein can improve the wettability of the silicon wafer surface, suppress the residue of abrasive particles, and improve the polishing speed.

[0014] Although the detailed mechanism of action of the polishing solution disclosed herein is not clear, it is presumed to be as follows. The polishing solution of this disclosure contains a polyamine-N-oxide having a structure derived from one selected polyamine and a structure derived from one or more selected epoxy group-containing compounds and acrylamide compounds, and abrasive grains. The polyamine-N-oxide has a large number of nitrogen atoms in its molecule due to having a polyamine-derived structure. Furthermore, at least some of these nitrogen atoms have an N-oxide structure, so it has high polarity but zero charge. Thus, the polyamine-N-oxide has high polarity in many parts of its molecule but no charge within the molecule, so the rigidification of the polymer chain due to repulsion between charged groups, which can occur in charged polymer compounds, does not occur. Furthermore, the polyamine-N-oxide contained in the polishing solution of this disclosure has a structure derived from one or more selected epoxy group-containing compounds and acrylamide compounds, so it exhibits high polarity similar to the N-oxide structure, and the polarity of the N-oxide structure can be further enhanced. Therefore, when the polishing solution of this disclosure comes into contact with a silicon wafer, the polyamine-N-oxide has a suitable affinity for the semimetallic silicon atoms and its adsorption sites are densely located, resulting in high adsorption to the silicon wafer and abrasive particles. Its high polarity enhances the wettability of the silicon wafer surface where adsorption has occurred, allowing for efficient polishing. Furthermore, the high wettability of the silicon wafer surface reduces the residue of abrasive particles on the silicon wafer after polishing. However, this disclosure does not have to be construed as being limited to these mechanisms.

[0015] (Polyamine-N-oxide) The polyamine-N-oxide contained in the polishing solution of this disclosure has a structure derived from one polyamine selected from polyethyleneimine, polyallylamine, and polydiallylamine (hereinafter also referred to as "the polyamine of this disclosure") and a structure derived from one or more compounds selected from epoxy group-containing compounds and acrylamide compounds. At least some of the nitrogen atoms contained in the structure derived from the polyamine of this disclosure have an N-oxide structure. In other words, the polyamine-N-oxide contained in the polishing solution of this disclosure is a water-soluble polymer having a structure derived from the polyamine of this disclosure and a structure derived from one or more epoxy group-containing compounds and acrylamide compounds, wherein at least a portion of the nitrogen atoms contained in the polyamine of this disclosure have an N-oxide structure. Hereinafter, a polyamine-N-oxide contained in the polishing solution of this disclosure, having a structure derived from the polyamine of this disclosure and a structure derived from one or more compounds selected from epoxy group-containing compounds and acrylamide compounds, will also be referred to as "the polyamine-N-oxide of this disclosure." The polyamine-N-oxide of this disclosure may be a single type or a combination of two or more types. The polyamine of this disclosure is preferably at least one selected from polyethyleneimine homopolymer obtained by polymerizing ethyleneimine as a monomer, polyallylamine homopolymer obtained by polymerizing allylamine as a monomer, and polydiallylamine homopolymer obtained by polymerizing diallylamine as a monomer. A preferred weight-average molecular weight of the polyamine of this disclosure, that is, the weight-average molecular weight of the structure derived from the polyamine of this disclosure in the polyamine-N-oxide of this disclosure, is preferably 2,000 or more, more preferably 5,000 or more, even more preferably 10,000 or more, and even more preferably 15,000 or more, from the viewpoint of increasing the wettability of the resulting polyamine-N-oxide of this disclosure and increasing the polishing rate, and similarly, preferably 200,000 or less, more preferably 150,000 or less, even more preferably 100,000 or less, and even more preferably 80,000 or less. When the polyamine-derived structure of the polyamine-N-oxide of the present disclosure is derived from polyethyleneimine, the weight average molecular weight of the polyethyleneimine-derived structure is preferably 2,000 or more, more preferably 5,000 or more, still more preferably 10,000 or more, and even more preferably 15,000 or more from the viewpoint of enhancing the wettability of the obtained polyamine-N-oxide of the present disclosure and increasing the polishing rate. From the same viewpoint, it is preferably 200,000 or less, more preferably 150,000 or less, still more preferably 100,000 or less, and even more preferably 80,000 or less. When the polyamine-derived structure of the polyamine-N-oxide of the present disclosure is derived from polyallylamine or polydiallylamine, the weight average molecular weight of the polyallylamine- or polydiallylamine-derived structure is preferably 2,000 or more, more preferably 5,000 or more from the viewpoint of enhancing the wettability of the obtained polyamine-N-oxide of the present disclosure and increasing the polishing rate. From the same viewpoint, it is preferably 200,000 or less, more preferably 100,000 or less, still more preferably 50,000 or less, and even more preferably 10,000 or less. In the present disclosure, "water-soluble" means having a solubility of 0.5 g / 100 mL or more, preferably 2 g / 100 mL or more in water (20 °C).

[0016] The polyamine-N-oxide of the present disclosure has a structure derived from one or more compounds selected from epoxy group-containing compounds and acrylamide compounds. In one or more embodiments, the structure derived from the epoxy group-containing compound preferably has a bond between the nitrogen atom contained in the polyamine of the present disclosure and the carbon atom to which the oxygen atom of the epoxy group in the epoxy group is bonded. The structure derived from the acrylamide compound preferably has a bond between the same nitrogen atom and the carbon atom at the β-position with respect to the carbonyl group of the amide group of the acrylamide compound.

[0017] In the polyamine-N-oxides of this disclosure, at least one of alkylene oxide compounds and glycidyl group-containing compounds can be used as the epoxy group-containing compound that generates the structure derived from the epoxy group-containing compound. The epoxy group-containing compound may be one type or a combination of two or more types. Examples of alkylene oxide compounds include at least one selected from ethylene oxide, 1,2-propylene oxide, 1,2-butylene oxide, and 2,3-butylene oxide, of which ethylene oxide is preferred. That is, when the polyamine-N-oxide of this disclosure has a structure derived from an alkylene oxide compound, it is preferable that it has a structure derived from ethylene oxide. Examples of glycidyl group-containing compounds include at least one selected from alkylglycidyl ethers, arylglycidyl ethers, alkylarylglycidyl ethers, and glycidol. Specific examples of alkylglycidyl ethers include alkylglycidyl ethers having 1 to 8 carbon atoms, among which one or more are selected from methylglycidyl ether, ethylglycidyl ether, and butylglycidyl ether. An example of an arylglycidyl ether is phenylglycidyl ether. An example of an alkylaryl ether is one or more selected from benzylglycidyl ether, isopropylphenylglycidyl ether, and butylphenylglycidyl ether, with glycidol being more preferred among these. That is, when the polyamine-N-oxide of this disclosure has a structure derived from a glycidyl group-containing compound, it is preferable that it has a structure derived from glycidol. Among these, from the viewpoint of improving the wettability of the polishing liquid of this disclosure and suppressing the residue of abrasive particles, and from the viewpoint of increasing the polishing speed, the epoxy group-containing compound that generates a structure derived from the epoxy group-containing compound is preferably a glycidyl group-containing compound, and more preferably glycidol. That is, if the polyamine-N-oxide of this disclosure has a structure derived from an epoxy group-containing compound, it is more preferable that the structure derived from the epoxy group-containing compound is a structure derived from glycidol. Structures derived from epoxy group-containing compounds in this disclosure can be obtained in one or more embodiments by reacting the polyamine of this disclosure with the epoxy group-containing compound. The ratio of nitrogen atoms in the polyamine-derived structure of this disclosure that react with the epoxy group-containing compound (reaction rate of nitrogen atoms) is preferably 50% or more, more preferably 60% or more, even more preferably 80% or more, even more preferably 90% or more, and even more preferably 100% or more, from the viewpoint of improving the wettability of the polishing liquid of this disclosure and suppressing the residue of abrasive particles, and from the viewpoint of improving the polishing speed. In this disclosure, the ratio of nitrogen atoms in the polyamine-derived structure of this disclosure that react with the epoxy group-containing compound (the reaction rate of nitrogen atoms) is: 13 The proportions of primary, secondary, and tertiary nitrogen atoms in the polyamine-derived structure of this disclosure, calculated by 13C-NMR measurement, are estimated from the changes before and after reaction with epoxy group-containing compounds. Specifically, the amount of carbon atoms adjacent to tertiary nitrogen atoms, secondary nitrogen atoms, and primary nitrogen atoms in the polyamine-derived structure of this disclosure is measured. 13 The ratios of tertiary nitrogen atoms, secondary nitrogen atoms, and primary nitrogen atoms in the polyamine-derived structure of this disclosure are determined by 13C-NMR. Similarly, the ratios of tertiary nitrogen atoms, secondary nitrogen atoms, and primary nitrogen atoms in the polymer compound after reacting the polyamine-derived structure with the epoxy group-containing compound are determined. The sum of the difference between the ratio of tertiary nitrogen atoms in the polymer compound after reacting the polyamine-derived structure with the epoxy group-containing compound (increase in the ratio of tertiary nitrogen atoms) and the difference between the ratio of secondary nitrogen atoms in the polyamine-derived structure with the epoxy group-containing compound (decrease in the ratio of secondary nitrogen atoms) is taken as the ratio of nitrogen atoms in the polyamine-derived structure that reacted with the epoxy group-containing compound. Furthermore, in this disclosure, since tertiary nitrogen atoms and secondary nitrogen atoms exist that are bonded to both epoxy group-containing compounds and groups derived from the polyamine skeleton of this disclosure, the reaction ratio may exceed 100%.

[0018] In the polyamine-N-oxide of this disclosure, specific examples of compounds that generate a structure derived from an acrylamide compound include at least one selected from acrylamide, N-methylacrylamide, N-ethylacrylamide, N-isopropylacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, and N,N-diisopropylacrylamide. Among these, at least one selected from N,N-dimethylacrylamide and N,N-diethylacrylamide is more preferred, and N,N-dimethylacrylamide is even more preferred, from the viewpoint of improving the wettability of the polishing solution of this disclosure, suppressing the residue of abrasive particles, and increasing the polishing speed. In other words, when the polyamine-N-oxide of this disclosure has a structure derived from an acrylamide compound, in one or more embodiments, at least one selected from a structure derived from N,N-dimethylacrylamide and a structure derived from N,N-diethylacrylamide is more preferred, and having a structure derived from N,N-dimethylacrylamide is even more preferred. The structures derived from acrylamide compounds in this disclosure can be obtained in one or more embodiments by reacting a polyamine of this disclosure with an acrylamide compound. The ratio of nitrogen atoms in the polyamine-derived structure of this disclosure that are reactable with the acrylamide compound (reaction rate of nitrogen atoms) is preferably 50% or more, more preferably 60% or more, even more preferably 80% or more, even more preferably 90% or more, and even more preferably 100% or more. In this disclosure, the ratio of nitrogen atoms in the polyamine-derived structure of this disclosure that react with the acrylamide compound (the reaction rate of nitrogen atoms) is: 13 The proportions of primary, secondary, and tertiary nitrogen atoms in the polyamine-derived structure of this disclosure, calculated by 13C-NMR measurement, are estimated from the changes before and after reaction with the acrylamide compound. Specifically, the amount of carbon atoms adjacent to tertiary nitrogen atoms, secondary nitrogen atoms, and primary nitrogen atoms in the polyamine-derived structure of this disclosure is measured. 13The ratios of tertiary nitrogen atoms, secondary nitrogen atoms, and primary nitrogen atoms in the polyamine-derived structure of this disclosure are determined by 13C-NMR. Similarly, the ratios of tertiary nitrogen atoms, secondary nitrogen atoms, and primary nitrogen atoms in the polymer compound after reacting the polyamine-derived structure of this disclosure with the acrylamide compound are determined. The sum of the difference between the ratio of tertiary nitrogen atoms in the polymer compound after reacting the polyamine-derived structure of this disclosure and the ratio of tertiary nitrogen atoms in the polyamine-derived structure of this disclosure (increase in the ratio of tertiary nitrogen atoms), and the difference between the ratio of secondary nitrogen atoms in the polyamine-derived structure of this disclosure and the ratio of secondary nitrogen atoms in the polymer compound after reacting the polyamine-derived structure of this disclosure with the acrylamide compound (decrease in the ratio of secondary nitrogen atoms), is defined as the ratio of nitrogen atoms in the polyamine-derived structure of this disclosure that reacted with the acrylamide compound. Furthermore, in this disclosure, since there are tertiary nitrogen atoms and secondary nitrogen atoms that are bonded to both the acrylamide compound and the polyamine skeleton of this disclosure, the reaction ratio may exceed 100%.

[0019] In one or more embodiments, the polyamine-N-oxides of this disclosure can be obtained by N-oxidizing a nitrogen atom in a polyamine to which an epoxy group-containing compound and / or an acrylamide compound has been added, using an oxidizing agent such as hydrogen peroxide.

[0020] In the polyamine-N-oxide of this disclosure, the proportion of nitrogen atoms in the structure derived from the polyamine of this disclosure that are in an N-oxide structure (hereinafter also referred to as the "ratio of N-oxide structures in nitrogen atoms of the polyamine-N-oxide of this disclosure") is preferably 10% or more, more preferably 25% or more, even more preferably 50% or more, even more preferably 55% or more, even more preferably 90% or more, even more preferably 98% or more, even more preferably 99% or more, and even more preferably 100%. In this disclosure, the ratio of N-oxide structures in nitrogen atoms of the polyamine-N-oxide of this disclosure is determined by the method using the total amine value described in the examples.

[0021] From the viewpoint of improving the wettability of the polishing solution of this disclosure and suppressing the residue of abrasive particles, and from the viewpoint of increasing the polishing speed, it is preferable that the polyamine-N-oxide of this disclosure has one or more structures selected from any of the following formulas (I) to (VI). [ka] In the above equations (I) to (VI), R 1 , R 2 Each of these independently represents either a hydrogen atom, an alkyl group, an aryl group, or an alkylaryl group.

[0022] In the above equations (I) to (VI), R 1 From the viewpoint of further improving the wettability of the polishing fluid of this disclosure and suppressing the residue of abrasive particles, and from the viewpoint of further increasing the polishing speed, it is more preferable that R be a hydrogen atom. 2 From the viewpoint of further improving the wettability of the polishing solution of this disclosure and suppressing the residue of abrasive particles, and from the viewpoint of further increasing the polishing speed, it is more preferable that the group be a methyl group.

[0023] In one or more embodiments, the polyamine-N-oxide of the present disclosure is preferably one or more selected from the following polymers (1) to (3), from the viewpoint of improving the wettability of the polishing solution of the present disclosure and suppressing the residue of abrasive particles, and from the viewpoint of improving the polishing speed. Polymer (1): A glycidol adduct of polyethyleneimine, wherein at least some of the nitrogen atoms of the amino group of the glycidol adduct of polyethyleneimine are N-oxideized. Polymer (2): An N,N-dimethylacrylamide adduct of polyethyleneimine, wherein at least some of the nitrogen atoms of the amino group of the N,N-dimethylacrylamide adduct of polyethyleneimine are N-oxideized. Polymer (3): A glycidol adduct of polyallylamine, wherein at least a portion of the nitrogen atoms of the amino group of the glycidol adduct of polyallylamine is N-oxideized.

[0024] The polymer (1) is a polymer having a structure derived from polyethyleneimine and a structure derived from glycidol in one or more embodiments, and at least a part of the nitrogen atoms contained in the structure derived from polyethyleneimine has an N-oxide structure, and has at least one of the structures represented by the formula (I) and the structure represented by the formula (II), and R 1 is a polymer having a hydrogen atom. The polymer (2) is a polymer having a structure derived from polyethyleneimine and a structure derived from N,N-dimethylacrylamide in one or more embodiments, and at least a part of the nitrogen atoms contained in the structure derived from polyethyleneimine has an N-oxide structure, and has at least one of the structures represented by the formula (III) and the structure represented by the formula (IV), and R 2 is a polymer having a methyl group. The polymer (3) is a polymer having a structure derived from polyallylamine and a structure derived from glycidol in one or more embodiments, and at least a part of the nitrogen atoms contained in the structure derived from polyallylamine has an N-oxide structure, and has the structure represented by the formula (V), and R 1 is a polymer having a hydrogen atom.

[0025] In one or more embodiments, the polyamine-N-oxide of the present disclosure may be the following polymer (4). Polymer (4): A glycidol adduct of polydiallylamine, in which at least a part of the nitrogen atoms of the amino groups of the glycidol adduct of polydiallylamine is N-oxidized

[0026] The polymer (4) is a polymer having a structure derived from polydiallylamine and a structure derived from glycidol in one or more embodiments, and at least a part of the nitrogen atoms contained in the structure derived from polydiallylamine has an N-oxide structure, and has the structure represented by the formula (VI), and R 1 is a polymer having a hydrogen atom.

[0027] The weight-average molecular weight of the polyamine-N-oxide in this disclosure is preferably 2,000 or more, more preferably 3,000 or more, even more preferably 5,000 or more, even more preferably 10,000 or more, even more preferably 15,000 or more, even more preferably 20,000 or more, and even more preferably 40,000 or more, and similarly, preferably 200,000 or less, and more preferably 170,000 or less. In this disclosure, the weight-average molecular weight can be measured, for example, by the method described in the examples.

[0028] The content of the polyamine-N-oxide in the polishing solution of this disclosure is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, even more preferably 0.01% by mass or more, from the viewpoint of increasing the polishing speed when using the polishing solution of this disclosure, and from the viewpoint of economic efficiency, preferably 3% by mass or less, more preferably 2% by mass or less, even more preferably 1% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.05% by mass or less, and even more preferably 0.02% by mass or less. When there is a combination of two or more polyamine-N-oxides, the content of the polyamine-N-oxides is the total content of those polyamine-N-oxides.

[0029] In this disclosure, "content of each component in the polishing solution of this disclosure" means the content of each component at the time of use, that is, when the polishing solution of this disclosure is used on a silicon wafer.

[0030] (Abrasive grains) The abrasive particles contained in the polishing solution of this disclosure are preferably silica particles and cerium oxide (ceria) particles, with silica particles being more preferred. The silica particles are preferably one or more selected from colloidal silica, fumed silica, and pulverized silica, with colloidal silica being more preferred among these.

[0031] From the viewpoint of ease of handling, a slurry form is preferred for the use of abrasive particles. When the abrasive particles contained in the polishing solution of this disclosure are colloidal silica, it is preferable that the colloidal silica is obtained from the hydrolysis of alkoxysilane, from the viewpoint of preventing contamination of silicon wafers by alkali metals, alkaline earth metals, etc. Silica particles obtained from the hydrolysis of alkoxysilane can be produced by known methods.

[0032] When the abrasive particles contained in the polishing solution of this disclosure are silica particles, the average primary particle diameter of the silica particles is preferably 10 nm or more, more preferably 15 nm or more, and even more preferably 20 nm or more, from the viewpoint of improving the polishing speed, and preferably 200 nm or less, more preferably 150 nm or less, even more preferably 100 nm or less, and even more preferably 50 nm or less, from the viewpoint of reducing residue on the substrate. In this disclosure, the average primary particle diameter of the abrasive particles can be measured, for example, by the method described in the examples.

[0033] When the abrasive particles contained in the polishing solution of this disclosure are silica particles, the average secondary particle diameter of the silica particles is preferably 20 nm or more, more preferably 30 nm or more, even more preferably 40 nm or more, and even more preferably 50 nm or more, from the viewpoint of improving the polishing speed, and preferably 100 nm or less, more preferably 90 nm or less, and even more preferably 80 nm or less, from the viewpoint of reducing residue on the substrate. More specifically, the average secondary particle diameter of the silica particles is preferably 20 nm or more and 100 nm or less, more preferably 30 nm or more and 90 nm or less, even more preferably 40 nm or more and 80 nm or less, and even more preferably 50 nm or more and 80 nm or less. In this disclosure, the average secondary particle diameter is a value measured by dynamic light scattering (DLS) and is a value measured by the method described in the examples. In one or more embodiments, the average secondary particle diameter is also referred to as the DLS particle size. The average primary particle diameter and average secondary particle diameter of the silica particles are the same when measured using the polishing solution of this disclosure and the concentrated polishing solution of this disclosure described later.

[0034] In the polishing fluid of this disclosure, the abrasive content is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and even more preferably 0.03% by mass or more, relative to the total polishing fluid of this disclosure, from the viewpoint of increasing the polishing speed. From the viewpoint of suppressing residue on the surface of the silicon wafer, it is preferably 5% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and even more preferably 0.2% by mass or less. If the abrasive is a combination of two or more types, the abrasive content is the total content of those types.

[0035] In the polishing solution of the present disclosure, the mass ratio of the polyamine-N-oxide content of the present disclosure to the abrasive grain content (polyamine-N-oxide / abrasive grains) is preferably 0.001 or higher, more preferably 0.01 or higher, even more preferably 0.03 or higher, even more preferably 0.05 or higher, and from the viewpoint of increasing the polishing speed when using the polishing solution of the present disclosure, it is preferably 5 or lower, more preferably 1 or lower, even more preferably 0.5 or lower, and even more preferably 0.2 or lower.

[0036] The zeta potential of the polishing fluid of this disclosure, i.e., the zeta potential of the abrasive grains in the polishing fluid, is preferably -10mV or less, more preferably -15mV or less, and even more preferably -20mV or less, from the viewpoint of reducing surface roughness (haze), and preferably -45mV or more, and even more preferably -40mV or more, from the viewpoint of improving the polishing speed. More specifically, the zeta potential of the abrasive grains in the polishing fluid of this disclosure is preferably -45mV or more and -10mV or less, more preferably -40mV or more and -15mV or less, and even more preferably -40mV or more and -20mV or less. The zeta potential of abrasive particles in the polishing solution of this disclosure can be measured by the method described in the examples.

[0037] (water) The polishing solution of this disclosure may contain water in one or more embodiments. The water may be at least one selected from ion-exchanged water, distilled water, and ultrapure water. The water content in the polishing solution of this disclosure may be the remainder obtained by subtracting polyamine-N-oxide, abrasive grains, and optional components described later, which may be added as needed, from the total polishing solution (100% by mass).

[0038] (Basic compounds) In one or more embodiments, the polishing solution of the present disclosure preferably further contains a basic compound from the viewpoint of increasing the polishing speed. That is, in one or more embodiments, the polishing solution of the present disclosure preferably contains the polyamine-N-oxide of the present disclosure, abrasive particles, water, and a basic compound. Preferred examples of basic compounds contained in the polishing solution of this disclosure include at least one selected from alkali metal hydroxides, alkali metal carbonates, ammonia, and quaternary ammonium hydroxides. Of these, at least one selected from alkali metal hydroxides, ammonia, and quaternary ammonium hydroxides is more preferred, at least one selected from sodium hydroxide, potassium hydroxide, ammonia, and tetramethylammonium hydroxide is even more preferred, and ammonia is even more preferred. The basic compound may be one or a combination of two or more.

[0039] If the polishing solution of this disclosure contains a basic compound, the content of the basic compound in the polishing solution of this disclosure is preferably 1 ppm by mass or more, more preferably 5 ppm by mass or more, even more preferably 10 ppm by mass or more, and from the viewpoint of increasing the polishing speed, preferably 300 ppm by mass or less, more preferably 200 ppm by mass or less, and even more preferably 100 ppm by mass or less. If the basic compound is a combination of two or more types, the content of the basic compound is the total content of those basic compounds. In this disclosure, 1% by mass is 10,000 ppm by mass (the same applies hereinafter).

[0040] If the polishing solution of this disclosure contains a basic compound, the mass ratio of the basic compound content to the polyamine-N-oxide content of this disclosure (basic compound / polyamine-N-oxide of this disclosure) is preferably 0.01 or higher, more preferably 0.1 or higher, even more preferably 0.2 or higher, and from the viewpoint of increasing the polishing speed when using the polishing solution of this disclosure, it is preferably 10 or lower, more preferably 1 or lower, and even more preferably 0.6 or lower.

[0041] (Other ingredients) The polishing solution of the present disclosure may further contain at least one optional component selected from water-soluble polymer compounds other than the polyamine-N-oxide of the present disclosure, pH adjusters, preservatives, water-soluble organic solvents, chelating agents, anionic surfactants, and nonionic surfactants, to the extent that the effect of the polishing solution of the present disclosure is not impaired.

[0042] (pH) From the viewpoint of increasing the polishing speed when using the polishing solution of this disclosure, the pH of the polishing solution of this disclosure is preferably 9 or higher, more preferably 9.5 or higher, even more preferably 10 or higher, and similarly preferably 12 or lower, more preferably 11.5 or lower, and even more preferably 11 or lower. In this disclosure, the pH is the value measured at 25°C.

[0043] [Concentrated polishing solution for silicon wafers] The polishing solutions of this disclosure may include forms that are manufactured as concentrates and diluted at the time of use, from the viewpoint of storage and transport. That is, this disclosure relates in one or more embodiments to concentrates for obtaining the polishing solutions of this disclosure. The concentration ratio of the concentrated polishing solution of this disclosure is preferably 2 times or more, more preferably 10 times or more, even more preferably 30 times or more, and even more preferably 50 times or more, from the viewpoint of manufacturing and transportation costs, and preferably 300 times or less, more preferably 200 times or less, even more preferably 150 times or less, and even more preferably 100 times or less, from the viewpoint of storage stability. The concentration ratio of the polishing solution concentrate in this disclosure means [solid content concentration of the polishing solution concentrate / solid content concentration of the polishing solution at the time of use]. Here, "solid content concentration of the polishing solution concentrate" is the ratio of the mass of components other than water in the polishing solution concentrate to the mass of the polishing solution concentrate, and "solid content concentration of the polishing solution at the time of use" is the ratio of the mass of components other than water in the polishing solution at the time of use to the mass of the polishing solution at the time of use. The concentrated polishing solution of this disclosure can be used after diluting it with water so that the content of each component at the time of use is as described above (i.e., the content of each component in the polishing solution at the time of use). The pH of the concentrated polishing solution of the polishing solution of the present disclosure is preferably 9 or higher, more preferably 9.5 or higher, even more preferably 10 or higher, and similarly, preferably 12 or lower, more preferably 11.5 or lower, and even more preferably 11 or lower, from the viewpoint of increasing the polishing rate when preparing the polishing solution of the present disclosure. In the present disclosure, the pH is the value measured at 25°C as described above.

[0044] [Method for manufacturing a polishing solution for silicon wafers] The polishing solution of this disclosure can be obtained by compounding the polyamine-N-oxide of this disclosure with abrasive grains and, if necessary, a basic compound, water, and other components. Accordingly, in other embodiments, this disclosure relates to a method for producing a polishing solution for silicon wafers, which includes a step of compounding the polyamine-N-oxide of this disclosure with abrasive grains. In this disclosure, "compounding" includes mixing the polyamine-N-oxide of this disclosure, abrasive grains, and, if necessary, a basic compound, water, and other components simultaneously or in any order. The compounding can be carried out, for example, by stirring with a magnetic rotor using a magnetic stirrer, stirring with anchor blades or paddle blades, or by using a homomixer, homogenizer, ultrasonic disperser, etc.

[0045] The polishing solution of this disclosure can be used, for example, in a polishing step for polishing a silicon wafer in the manufacturing process of a semiconductor substrate, or in a silicon wafer polishing method that includes a polishing step for polishing a silicon wafer. The polishing process for polishing the silicon wafer includes a lapping (rough polishing) step to flatten the silicon wafer obtained by slicing a silicon single crystal ingot into a thin disc shape, and a finish polishing step to make the surface of the silicon wafer mirror-like after etching the lapped silicon wafer. The polishing solution of this disclosure is more preferably used in the finish polishing step.

[0046] [Polishing solution kit] This disclosure relates, in one aspect, to a kit for manufacturing the polishing solution of this disclosure (hereinafter also referred to as the "kit of this disclosure"). According to the kit of this disclosure, a polishing solution for silicon wafers can be obtained that can improve the polishing speed of silicon wafers and suppress the residue of abrasive particles by improving the wettability of silicon wafers. In one or more embodiments, the kits of the present disclosure include polishing solution kits containing a solution comprising the polyamine N-oxide of the present disclosure and water. The polishing solution kits may optionally contain other components as described above. If the polishing solution kit is referred to as polishing solution kit A, then when used for polishing silicon wafers, polishing solution kit A can be mixed with polishing solution kit B containing abrasive particles, and further mixed with water as necessary, to obtain the silicon wafer polishing solution of the present disclosure.

[0047] [Manufacturing method for semiconductor devices] This disclosure relates, in one embodiment, to a method for manufacturing a semiconductor device (hereinafter also referred to as "the semiconductor device manufacturing method of this disclosure") which includes a step of polishing a silicon wafer using the polishing solution of this disclosure. In this disclosure, "semiconductor device" refers to an electronic component that uses a semiconductor. The silicon wafers polished in the aforementioned silicon wafer polishing process include silicon wafers obtained by slicing a silicon single crystal ingot into a thin disc shape, and silicon wafers that have undergone a lapping process to flatten the sliced ​​silicon wafer and an etching process to etch the silicon wafer that has undergone the lapping process. In the semiconductor device manufacturing method of the present disclosure, the silicon wafer used in the step of polishing the silicon wafer with the polishing solution of the present disclosure is preferably a silicon wafer that has undergone a lapping step in which a silicon wafer obtained by slicing a silicon ingot is planarized, and an etching step in which the silicon wafer that has undergone the lapping step is etched. In one or more embodiments, the polishing step for polishing the silicon wafer is a finishing polishing step. [Examples]

[0048] The present disclosure will be further described below with reference to examples, but these are illustrative and the disclosure is not limited to these examples.

[0049] 1. Preparation of concentrated polishing solution (Concentrates of polishing solutions 1-3, 5-7, and comparative polishing solution 1) 1.5 parts by mass of polyamine-N-oxide 1 to 6 or water-soluble polymer (HEC) shown in Table 2, 10 parts by mass of silica particles [commercially available, average primary particle size 35 nm], and 88.5 parts by mass of ultrapure water were mixed to obtain concentrates of polishing solutions 1 to 3, 5 to 7, and a concentrate of comparative polishing solution 1. (Concentrated polishing solution 4) A concentrated polishing solution 4 was obtained by mixing 0.5 parts by mass of polyamine-N-oxide 3, 10 parts by mass of silica particles, and 89.5 parts by mass of ultrapure water, as shown in Table 2. The pH of each polishing solution concentrate at 25°C ranged from 10.4 to 11.0. The pH values ​​were measured at 25°C using a pH meter (Toa Denpa Kogyo Co., Ltd., HM-30G), and were recorded one minute after immersing the pH meter electrode in the polishing solution concentrate.

[0050] The silica particles, HEC, and polyamine-N-oxide used in the preparation of the concentrates of each polishing solution were as follows: Silica particles [colloidal silica, commercially available, average primary particle diameter 35 nm] HEC: Hydroxyethylcellulose [Sumitomo Seika Co., Ltd., SE-400, weight-average molecular weight 250,000] Polyamine-N-oxide 1 [Manufactured by Kao Corporation] Synthesis method: 5.38 g of polyethyleneimine SP-200 (manufactured by Nippon Shokubai Co., Ltd., weight-average molecular weight 16,000, amine value: 18 mmol / g·solid) (amine ratio primary amine: secondary amine: tertiary amine = 35:35:30 (molar ratio)) and 10 g of water were placed in a 100 mL round-bottom flask. 12.0 g of glycidol (manufactured by Kanto Chemical Co., Ltd., purity >95%) was added dropwise over 1 hour, and the mixture was stirred at 60°C for 2 hours to obtain a reaction solution containing the reaction product of polyethyleneimine and glycidol. 15.8 g of 35% hydrogen peroxide (manufactured by ADEKA) was added dropwise over 1 hour, and the mixture was stirred at 60°C for 6 hours to prepare the polyamine-N-oxide 1 shown in Table 1. Polyamine-N-oxide 2 [Manufactured by Kao Corporation] Synthesis method: 60.0 g of polyethyleneimine SP-200 (manufactured by Nippon Shokubai Co., Ltd., weight-average molecular weight 16,000, amine value: 18 mmol / g·solid) (amine ratio primary amine: secondary amine: tertiary amine = 35:35:30 (molar ratio)) and 205 g of water were placed in a 2 L three-necked flask. Under a nitrogen atmosphere, 145 g of N,N-dimethylacrylamide (manufactured by Fujifilm Wako Reagents Co., Ltd., reagent grade) was added dropwise over 1 hour at 60°C, and the mixture was then stirred at 60°C for 5 hours to obtain a reaction solution containing the reaction product of polyethyleneimine and N,N-dimethylacrylamide. 271 g of 35% hydrogen peroxide (manufactured by ADEKA Corporation) was added dropwise over 1 hour, and the mixture was stirred at 60°C for 6 hours to prepare the polyamine-N-oxide 2 shown in Table 1. Polyamine-N-oxide 3 [Manufactured by Kao Corporation] Synthesis method: 60.0 g of polyethyleneimine HM-2000 (manufactured by Nippon Shokubai Co., Ltd., weight-average molecular weight 54,000, amine value: 18 mmol / g·solid) (amine ratio primary amine: secondary amine: tertiary amine = 1:1:0.9 (molar ratio)) and 205 g of water were placed in a 2 L three-necked flask. Under a nitrogen atmosphere, 145 g of N,N-dimethylacrylamide (manufactured by Fujifilm Wako Reagents Co., Ltd., reagent grade) was added dropwise over 1 hour at 60°C, and the mixture was then stirred at 60°C for 5 hours to obtain a reaction solution containing the reaction product of polyethyleneimine and N,N-dimethylacrylamide. 271 g of 35% hydrogen peroxide (manufactured by ADEKA Corporation) was added dropwise over 1 hour, and the mixture was stirred at 60°C for 6 hours to prepare the polyamine-N-oxide 3 shown in Table 1. Polyamine-N-oxide 4 [Manufactured by Kao Corporation] Synthesis method: In a 500 mL three-necked flask, 14.9 g of polyethyleneimine SP-018 (manufactured by Nippon Shokubai Co., Ltd., weight-average molecular weight 5,800, amine value: 19 mmol / g·solid, amine ratio primary amine: secondary amine: tertiary amine = 35:35:30 (molar ratio)) and 50.8 g of water were placed. Under a nitrogen atmosphere, 36.2 g of N,N-dimethylacrylamide (manufactured by Fujifilm Wako Reagents Co., Ltd., reagent grade) was added dropwise over 1 hour at 60°C, and the mixture was then stirred at 60°C for 5 hours to obtain a reaction solution containing the reaction product of polyethyleneimine and N,N-dimethylacrylamide. 33.6 g of 35% hydrogen peroxide (manufactured by ADEKA Corporation) was added dropwise over 1 hour, and the mixture was stirred at 60°C for 6 hours to prepare the polyamine-N-oxide 4 shown in Table 1. Polyamine-N-oxide 5 [Manufactured by Kao Corporation] Synthesis method: In a 500 mL three-necked flask, 14.8 g of polyethyleneimine SP-018 (manufactured by Nippon Shokubai Co., Ltd., weight-average molecular weight 5,800, amine value: 19 mmol / g·solid) (amine ratio primary amine: secondary amine: tertiary amine = 35:35:30 (molar ratio)) and 50.6 g of water were placed. Under a nitrogen atmosphere at 60°C, 36.0 g of N,N-dimethylacrylamide (manufactured by Fujifilm Wako Reagents Co., Ltd., reagent grade) was added dropwise over 1 hour, and the mixture was stirred at 60°C for 5 hours to obtain a reaction solution containing the reaction product of polyethyleneimine and N,N-dimethylacrylamide. To this reaction solution, 16.7 g of 35% hydrogen peroxide (manufactured by ADEKA Corporation) was added dropwise over 1 hour, and the mixture was stirred at 60°C for 6 hours to prepare the polyamine-N-oxide 5 shown in Table 1. Polyamine-N-oxide 6 [Manufactured by Kao Corporation] Synthesis method: In a 500 mL three-necked flask, 20 g of polyallylamine (manufactured by Nitto Boseki, weight average weight 5,000 g, amine value 17 mmol / g·solid, amine ratio primary amine:secondary amine:tertiary amine = 100:0:0 (molar ratio)) and 168 g of water were placed. Under a nitrogen atmosphere, 76 g of glycidol was added dropwise over 1 hour at 60°C, and the mixture was then stirred at 60°C for 1 hour to obtain a reaction solution containing the reaction product of polyallylamine and glycidol. 90 g of 35% hydrogen peroxide (manufactured by ADEKA) was added dropwise over 1 hour, and the mixture was stirred at 60°C for 6 hours to prepare the polyamine-N-oxide 6 shown in Table 1.

[0051] [Table 1]

[0052] 2. Measurement methods for various parameters (1) Method for measuring the ratio of N-oxide structures at nitrogen atoms in the polyamine-N-oxide of the present disclosure The values ​​calculated using the following formula were used as the ratio of N-oxide structures at the nitrogen atoms of the polyamine-N-oxide in this disclosure. The ratio (%) of N-oxide structures at the nitrogen atom of the polyamine-N-oxide in this disclosure = 100 - (total amine value (after hydrogen peroxide reaction)) / (total amine value (before hydrogen peroxide reaction)) × 100 The total amine value is the amount of hydrochloric acid required to neutralize the total amount of primary, secondary, and tertiary amines in 1 g of an amino group-containing compound, converted to the number of milligrams of potassium hydroxide. In calculating the ratio of N-oxide structures at the nitrogen atom of the polyamine-N-oxide of this disclosure, the total amine value is determined by the following procedure. A polyamine-N-oxide (amino group-containing compound for measuring total amine value (after hydrogen peroxide reaction)) or a reaction product of polyamines with one or more compounds selected from the epoxy group-containing compounds and acrylamide compounds of the polyamines disclosed herein (amino group-containing compound for measuring total amine value (before hydrogen peroxide reaction)) was accurately measured into a 100 mL beaker as a sample and dissolved in water. Potentiometric titration was performed using an HM-41K pH meter (manufactured by Toa DKK Co., Ltd.) with a 0.2 mol / L alcoholic hydrochloric acid standard solution. A blank test was performed simultaneously and calculated using the following formula. Total amine value (mgKOH / g.solid) = (XY) × M × f × 56.108 / Sample amount (g) X: Titration volume (mL) for this test Y: Titration volume of blank test (mL) M: Molar concentration (mol / L) of alcoholic hydrochloric acid standard solution f: Factor of alcoholic hydrochloric acid standard solution 56.108: Molecular weight of KOH (g / mol)

[0053] (2) Measurement of the weight-average molecular weight of the polyamine-N oxide and water-soluble polymers of the present disclosure The weight-average molecular weights of the polyamine-N-oxides and water-soluble polymers in this disclosure were calculated based on the peaks in the chromatograms obtained by applying gel permeation chromatography (GPC) under the following conditions. <Measurement conditions for polyamine-N-oxide and water-soluble polymers in this disclosure> Equipment: HLC-8320 GPC (manufactured by Tosoh Corporation, with integrated detector) Column: α-M + α-M (cation) Eluent: 0.15M Na2SO4 / 1% CH3COOH Flow rate: 1mL / min Column temperature: 40℃ Detector: Schodex RI SE-61 differential refractive index detector Standard substance: Monodisperse pullulan with a known molecular weight

[0054] (3) Reaction rate of nitrogen atoms in the polyamine-derived structures of this disclosure The ratio of nitrogen atoms in the polyamine-derived structure of this disclosure that react with a glycidyl group-containing compound or an acrylamide compound (reaction rate of nitrogen atoms) is: 13 The ratio (mol%) of primary, secondary, and tertiary nitrogen atoms in the polyamine-derived structure of this disclosure, calculated by 13C-NMR measurement, was estimated from the changes before and after reaction with a glycidyl group-containing compound.

[0055] (4) Measurement of the average primary particle size of silica particles (colloidal silica) The average primary particle size of colloidal silica was measured as follows: The average primary particle size (nm) of colloidal silica is calculated using the specific surface area S(m²) calculated by the BET (nitrogen adsorption) method. 2 The calculation was performed using the following formula with ( / g). Average primary particle diameter (nm)=2727 / S The specific surface area S of colloidal silica was measured by nitrogen adsorption method (BET method) using a micromeritic automatic specific surface area analyzer (Micromeritic Automatic Specific Surface Area Analyzer "Flowsorb III 2305", manufactured by Shimadzu Corporation) after the following [pretreatment] had been performed. [Pre-processing] (a) Adjust the pH of the colloidal silica slurry to 2.5 ± 0.1 with an aqueous nitric acid solution. (b) Place the colloidal silica slurry, adjusted to pH 2.5 ± 0.1, into a petri dish and dry it in a hot air dryer at 150°C for 1 hour. (c) After drying, the obtained sample is finely ground in an agate mortar. (d) The pulverized sample is suspended in deionized water at 40°C and filtered through a membrane filter with a pore size of 1 μm. (e) Wash the filtrate on the filter five times with 20g of deionized water (40°C). (f) Place the filter with the filtrate attached into a petri dish and dry it in an atmosphere of 110°C for 4 hours. (g) Take the dried filtrate carefully, making sure no filter debris is mixed in, and grind it finely in a mortar to obtain a sample for measurement.

[0056] 5. Preparation and evaluation of polishing solutions for Examples 1-7 and Comparative Example 1 (1) Preparation of polishing solution One part by mass of the concentrate of the above polishing solution and 0.0107 parts by mass of aqueous ammonia [28% by mass aqueous ammonia, manufactured by Kishida Chemical Co., Ltd., reagent grade] were mixed, and then ultrapure water was added to make a total of 100 parts by mass and mixed again to obtain polishing solutions 1 to 7, which are the polishing solutions of this disclosure, and comparative polishing solution 1, which is a comparative polishing solution. The content (mass %) or mass ppm, effective content) of each component in Table 2 refers to the polishing solution obtained by diluting the concentrate of the above polishing solution, i.e., the polishing solution used in a polishing machine when polishing silicon wafers. The water content in each polishing solution is the residue obtained by subtracting the polyamine-N-oxide or water-soluble polymer, silica particles, and ammonia of this disclosure from the total amount of polishing solution (100 mass%). The pH of each polishing solution (used for polishing silicon wafers) at 25°C was 10.2. The pH at 25°C was measured using a pH meter (Toa Denpa Kogyo Co., Ltd., HM-30G), and the value was obtained 1 minute after immersing the pH meter electrode in the polishing solution composition or its concentrate.

[0057] (2) Measurement of DLS particle size and zeta potential of abrasive grains in polishing solution The method for measuring the DLS particle size and zeta potential of abrasive particles (silica particles) in the polishing solution during silicon wafer polishing is as follows. The results are shown in Table 2. <DLS particle size of silica particles> The DLS particle size (nm) of the silica particles was measured by adding the polishing solution of this disclosure (polishing solution used for silicon wafer polishing) to deionized water, and then placing the resulting aqueous dispersion (silica particle content: 0.1 mass%) into a Disposable Sizing Cuvette (polystyrene 10 mm cell) to a height of 10 mm from the bottom, and measuring it using dynamic light scattering (instrument name: "Zetasizer Nano ZS", manufactured by Sysmex Corporation). <Measurement of Zeta Potential of Silica Particles in the Polishing Solution of This Disclosure> The polishing solution of this disclosure (polishing solution used for polishing silicon wafers) was added to deionized water and diluted. The resulting aqueous dispersion (silica particle content: 0.1% by mass) was placed in a capillary cell DTS1070, and the zeta potential was measured using a zetasizing device Nano ZS [Malvern] under the following conditions. Sample: Refractive index: 1.450 Absorption rate: 0.010 Dispersion medium: Viscosity: 0.8872 cP, Refractive index: 1.330, Dielectric constant: 78.5 Temperature: 25℃

[0058] (3) Polishing method etc. Each polishing solution was filtered (Compact cartridge filter "MCP-LX-C10S", manufactured by Advantech Co., Ltd.) immediately before polishing, and then the following silicon wafers were polished and washed under the following polishing conditions. <Silicon wafer to be polished> Single-crystal silicon wafer [200mm diameter silicon single-sided mirror-finished substrate, conduction type: P, crystal orientation: 100, resistivity: 0.1Ω·cm or more and less than 100Ω·cm] The above single-crystal silicon wafers were pre-polished using a commercially available polishing solution composition (GLANZOX 1302, manufactured by Fujimi Incorporated). The haze of the single-crystal silicon wafers after rough polishing and before finishing polishing was 2-3 ppm.

[0059] <Finishing polishing conditions> Grinding machine: Single-sided 8-inch grinding machine "GRIND-X SPP600s" (manufactured by Okamoto Kogyo) Polishing pad: Suede pad (manufactured by Toray Cortex, Asker hardness: 64, thickness: 1.37 mm, nap length: 450 μm, opening diameter: 60 μm) Silicon substrate polishing pressure: 100 g / cm² 2 Plate rotation speed: 60 rpm Polishing time: 2 minutes Supply rate of polishing solutions 1-7 and comparative polishing solution 1: 150g / min Temperature of polishing solutions 1-7 and comparative polishing solution 1: 23°C Carrier rotation speed: 62 rpm

[0060] <Cleaning method> After final polishing, the silicon wafers were subjected to ozone cleaning and dilute hydrofluoric acid cleaning as described below. For ozone cleaning, an aqueous solution containing 20 ppm ozone was sprayed from a nozzle at a flow rate of 1 L / min towards the center of the silicon wafer rotating at 600 rpm for 3 minutes. The temperature of the ozonated water was kept at room temperature. Next, dilute hydrofluoric acid cleaning was performed. For dilute hydrofluoric acid cleaning, an aqueous solution containing 0.5 mass% ammonium hydrogen fluoride (special grade, Nacalai Tesque Co., Ltd.) was sprayed from a nozzle at a flow rate of 1 L / min towards the center of the silicon wafer rotating at 600 rpm for 6 seconds. The above ozone cleaning and dilute hydrofluoric acid cleaning were performed as one set, for a total of two sets, and finally, spin drying was performed. For spin drying, the silicon wafer was rotated at 1,500 rpm.

[0061] (4) Evaluation of wettability The wet area of ​​each silicon wafer immediately after polishing was calculated as the ratio of the wet area to the area of ​​one side of the silicon wafer. The results are shown in Table 2.

[0062] (5) Evaluation of polishing speed The mass of each silicon wafer before and after polishing was measured using a precision balance (Sartorius BP-210S). The obtained mass difference was divided by the silicon wafer density, area, and polishing time to determine the single-sided polishing rate per unit time. The results are shown in Table 2. Note that the mass of the silicon wafer after polishing refers to the mass of the silicon substrate after the above-mentioned finish polishing and cleaning.

[0063] (6) Evaluation of residual silica on silicon wafers For Example 3 and Comparative Example 1, the silicon wafers after cleaning were subjected to particle measurement using a wafer surface inspection device WM-10 (manufactured by TOPCON) with a detection sensitivity of 61 nm, and the number of particles (unit: particles) was evaluated. The results are shown in Table 3.

[0064] [Table 2]

[0065] [Table 3]

[0066] As shown in Table 2, the polishing solutions of Examples 1 to 7 using the polyamine-N-oxide of this disclosure showed improved wettability and polishing speed compared to the polishing solution of Comparative Example 1 using a water-soluble polymer (HEC) other than the polyamine-N-oxide of this disclosure. Furthermore, as shown in Table 3, the polishing solution of Example 3, which had a large absolute value of the zeta potential of the polishing solution during silicon wafer polishing, was able to reduce the amount of silica remaining on the silicon wafer compared to the polishing solution of Comparative Example 1, which had a smaller absolute value. Also, as shown in Table 2, the absolute values ​​of the zeta potential of the polishing solutions of Examples 1 to 7 were larger than those of the polishing solution of Comparative Example 1. From the above, it was found that using a polishing solution containing the polyamine-N-oxide and abrasive grains of this disclosure can improve the wettability of the silicon wafer surface, suppress the residue of abrasive grains, and improve the polishing speed. [Industrial applicability]

[0067] By using the polishing solution of this disclosure, the wettability of the silicon wafer surface can be improved and the polishing speed can be increased. Therefore, the polishing solution of this disclosure is useful in various processes of semiconductor manufacturing, and in particular, it is useful as a polishing solution composition for the final polishing of silicon wafers.

Claims

1. A polishing solution for silicon wafers, comprising a polyamine-N-oxide having a structure derived from one polyamine selected from polyethyleneimine, polyallylamine, and polydiallylamine, and a structure derived from one or more compounds selected from epoxy group-containing compounds and acrylamide compounds, and abrasive grains.

2. The silicon wafer polishing solution according to claim 1, wherein the structure derived from the epoxy group-containing compound is a structure derived from glycidol.

3. The silicon wafer polishing solution according to claim 1, wherein the structure derived from the acrylamide compound is at least one selected from the structure derived from N,N-dimethylacrylamide and the structure derived from N,N-diethylacrylamide.

4. The silicon wafer polishing solution according to claim 1, wherein the polyamine-N-oxide has one or more structures selected from any of the following formulas (I) to (VI). 【Chemistry 1】 In the above formula, R 1 , R 2 Each of these independently represents either a hydrogen atom, an alkyl group, an aryl group, or an alkylaryl group.

5. The silicon wafer polishing solution according to claim 1, wherein the polyamine-N-oxide is one or more selected from any of the following polymers (1) to (3). Polymer (1): A glycidol adduct of polyethyleneimine, wherein at least a portion of the nitrogen atoms of the amino group of the glycidol adduct of polyethyleneimine is N-oxideized. Polymer (2): An N,N-dimethylacrylamide adduct of polyethyleneimine, wherein at least a portion of the nitrogen atoms of the amino group of the N,N-dimethylacrylamide adduct of polyethyleneimine is N-oxideized. Polymer (3): A glycidol adduct of polyallylamine, wherein at least a portion of the nitrogen atoms of the amino group of the glycidol adduct of polyallylamine is N-oxideized.

6. The silicon wafer polishing solution according to claim 1, wherein the weight-average molecular weight of the polyamine-N-oxide is 2,000 or more and 200,000 or less.

7. The abrasive liquid for silicon wafers according to claim 1, wherein the abrasive particles are silica particles.

8. The silicon wafer polishing solution according to claim 1, further comprising a basic compound.

9. A method for manufacturing a semiconductor device, comprising the step of polishing a silicon wafer using a silicon wafer polishing solution described in any one of claims 1 to 8.

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