Surface treatment composition

Abstract

[Problem] To provide a surface treatment composition capable of suppressing the polishing speed of a polished polishing object in a surface treatment process. [Solution] A surface treatment composition which contains a water-soluble polymer and a solvent is used for surface treatment of a polished polishing object that is obtained by polishing a polishing object by using a polishing composition. The surface treatment is performed in the presence of abrasive grains. The repulsive force obtained when the surface treatment is performed using the surface treatment composition under a surface treatment condition A is 0.003 N / m or more.

Description

Surface treatment composition

[0001] This invention relates to a surface treatment composition.

[0002] In recent years, with the increasing use of multilayer wiring on semiconductor substrate surfaces, chemical mechanical polishing (CMP) technology, which involves using polishing compositions to polish and planarize semiconductor substrates during device manufacturing, has become widely used.

[0003] The CMP process has been applied to various processes in semiconductor manufacturing, such as the gate formation process in transistor fabrication. During transistor fabrication, materials such as metals, silicon oxide, polycrystalline silicon, and silicon nitride are sometimes polished.

[0004] After the polishing process, a polished object (a so-called polished object) is obtained. It is known that this polished object can be further treated with a composition that contains polymers and other components, but usually does not contain abrasive particles, in order to improve its surface.

[0005] For example, Patent Document 1 describes a surface treatment composition comprising the following components (A) to (C), with a pH greater than 7.0: (A) Component: A quaternary nitrogen-containing onium salt compound having at least one of a linear or branched alkyl group having 7 or more carbon atoms and a linear or branched alkenyl group having 7 or more carbon atoms; (B) Component: A nonionic polymer; (C) Component: Formula: A-COO-NH ４ ＋ A surface treatment method using a buffering agent represented by (where A is an alkyl group or phenyl group having 1 to 10 carbon atoms) is disclosed.

[0006] In the examples described in the document, it is disclosed that a polished object (polished SiN substrate) is obtained by polishing a SiN substrate using a silica slurry, and surface treatment is performed by applying a surface treatment composition to the polished SiN substrate to reduce the number of defects on the polished SiN substrate.

[0007] Japanese Patent Publication No. 2023-146030

[0008] The inventors have discovered that in the surface treatment process, a phenomenon occurs in which the polished object is polished by abrasive particles derived from the polishing composition brought in from the preceding polishing process.

[0009] However, in the preceding polishing process, the principle is that the desired elimination of steps has already been achieved by controlling the polishing speed of the polished workpiece to be constant. Therefore, if the polished workpiece is polished at a high polishing speed in the subsequent surface treatment process, it would lead to the risk of the eliminated steps reappearing.

[0010] Therefore, the problem that the present invention aims to solve is to provide a surface treatment composition that can suppress the polishing speed of a polished object during the surface treatment process.

[0011] One aspect of the present invention is a surface treatment composition comprising a water-soluble polymer and a solvent, wherein the surface treatment composition is used for surface treatment of a polished object obtained by polishing the object using an abrasive composition, the surface treatment is performed in the presence of abrasive grains, and the surface repulsion force obtained when the surface is treated with the surface treatment composition under surface treatment condition A is 0.003 N / m or more.

[0012] In the surface treatment process, a surface treatment composition can be provided that can suppress the polishing speed of a polished object.

[0013] The present invention will now be described in detail. In this specification, "X to Y" is used to mean "X or greater and Y or less," including the numerical values ​​(X and Y) described before and after it as the lower and upper limits, respectively. When multiple "X to Y" are described, for example, "X1 to Y1, or X2 to Y2," the disclosure of each numerical value as the upper limit, the disclosure of each numerical value as the lower limit, and all combinations of these upper and lower limits are disclosed (i.e., they provide a lawful basis for corrections). Specifically, corrections to X1 or greater, corrections to Y2 or less, corrections to X1 or less, corrections to Y2 or greater, corrections to X1 to X2, corrections to X1 to Y2, etc., must all be considered lawful. Unless otherwise specified, operations and measurements of physical properties, etc., are performed under conditions of room temperature (20 to 25°C) / relative humidity 40 to 50% RH. The concentrations described in this specification may be the concentration at the point of use (POU), or the concentration before dilution to the POU concentration. The dilution ratio may be 2 to 10 times. Furthermore, it should be understood that all combinations of embodiments and descriptions disclosed herein are disclosed in this application; that is, they should be understood as grounds for amendment. Also, when the content or concentration of each component is described, if two or more are included, it may be the total amount. Furthermore, if a feature or aspect of this disclosure is described in terms of the Markush group, a person skilled in the art will recognize that this disclosure is described in terms of any individual component or subgroup of components of the Markush group. It should be noted that any description of the mechanism of disclosure in the specification is not beyond speculation, and it goes without saying that the scope of protection of the present invention is not limited by this mechanism.

[0014] <Surface Treatment Composition> One embodiment of the present invention is a surface treatment composition comprising a water-soluble polymer and a solvent, wherein the surface treatment composition is used for surface treatment of a polished object obtained by polishing the object using an abrasive composition, the surface treatment is performed in the presence of abrasive grains, and the surface repulsion force obtained when the surface is treated with the surface treatment composition under surface treatment condition A is 0.003 N / m or more. With such a surface treatment composition, the polishing speed of the polished object can be suppressed in the surface treatment process.

[0015] As described above, the present inventors have found that in the surface treatment process, a phenomenon occurs in which the polished object to be polished is polished by abrasive particles derived from the polishing composition brought in from the preceding polishing process. Therefore, according to one embodiment of the present invention, the abrasive particles include those derived from the polishing composition.

[0016] <Polished Objects> In this specification, "polished objects" means objects that have been polished in a polishing process. The polishing process is preferably a chemical mechanical polishing (CMP) process. The polishing process may consist of a single step or multiple steps. Examples of polishing processes consisting of multiple steps include a process in which a preliminary polishing (rough polishing) step is followed by a finish polishing step, or a process in which a primary polishing step is followed by one or more secondary polishing steps and then a finish polishing step.

[0017] [Polishing Composition] Any known polishing composition can be used as appropriate. Examples of polishing compositions include those containing silica abrasive particles such as colloidal silica and an aqueous carrier such as water. The polishing composition may further contain known water-soluble polymers and pH adjusters. The average primary particle diameter of the silica abrasive particles may be about 10 to 100 nm, and the average secondary particle diameter may be about 20 to 230 nm. The water-soluble polymer may include polymers having an N-vinyl cyclic lactam structure, such as polyvinylpyrrolidone and polyvinylcaprolactam. The pH adjuster may include basic compounds such as ammonia. The pH of the polishing composition may be about 1 to 13. The concentration of silica abrasive particles in the polishing composition may be, for example, 0.1 to 20% by mass.

[0018] For the polishing process, a general polishing apparatus can be used, which has a holder for holding the object to be polished, a motor with adjustable rotation speed, and a polishing platen to which a polishing pad (abrasive cloth) can be attached. Either a single-sided polishing apparatus or a double-sided polishing apparatus may be used.

[0019] [Objects to be polished] There are no particular restrictions on the materials included in the objects to be polished, but Si-based materials are included. Polished objects obtained by polishing the objects to be polished also include similar materials. Examples of Si-based materials include materials having nitrogen-silicon bonds, such as silicon nitride (SiN). Other materials having nitrogen-silicon bonds include silicon oxynitride films (SiON films), silicon carbonitride (SiCN) films, silicon oxycarbonitride films (SiOCN films), nitrogen-doped hafnium silicate films (HfSiON films), and SiAlON films (SiAlON films). Examples of Si-based materials include silicon oxide (SiO₂) such as TEOS-type silicon oxide films (hereinafter also simply referred to as "TEOS" or "TEOS film") produced using tetraethyl orthosilicate as a precursor. ２ There are also materials that have oxygen-silicon bonds, such as ).

[0020] <Surface Treatment Composition> One embodiment of the present invention provides a surface treatment composition comprising a water-soluble polymer and a solvent. This surface treatment composition is used for surface treatment of a polished object obtained by polishing the object using an abrasive composition. When the surface is treated using the surface treatment composition under surface treatment condition A, the surface repulsion force obtained is 0.003 N / m or more. Having such a repulsion force allows for a slower polishing speed of the polished object during the surface treatment process. Surface treatment condition A is a condition used when measuring AFM (Autonomous Frequency Measurement) such as repulsion force, and it goes without saying that surface treatment using the surface treatment composition of the present invention is not limited to this surface treatment condition. Details of surface treatment condition A are described in the Examples section.

[0021] [Water-soluble polymer] The water-soluble polymer is not particularly limited, and cationic polymers, anionic polymers, and nonionic polymers can all be used. The water-soluble polymer can be used alone or in combination of two or more types. The water-soluble polymer may be a commercially available product or a synthetic product. In this specification, "water-soluble" may mean that the solubility in water (25°C) is 1 g / 100 mL or more. Furthermore, a water-soluble polymer is defined as a polymer that, when dissolved in water at a concentration of 0.5% by mass at the temperature at which the water-soluble polymer is most soluble, has a mass of insoluble matter filtered out when filtered through a G2 glass filter (maximum pore size 40-50 μm) that is within 50% by mass of the added water-soluble polymer.

[0022] Water-soluble polymers are typically compounds with a weight-average molecular weight (Mw) of 1,000 or more. The weight-average molecular weight (Mw) can be measured by the method described in the examples.

[0023] The lower limit of the weight-average molecular weight (Mw) of water-soluble polymers can be 1,000 or more, 2,000 or more, 5,000 or more, 10,000 or more, or 20,000 or more. The upper limit of the weight-average molecular weight (Mw) of water-soluble polymers can be 5,000,000 or less, 3,000,000 or less, 2,000,000 or less, 1,500,000 or less, 500,000 or less, 100,000 or less, 80,000 or less, 60,000 or less, or 40,000 or less. For example, the weight-average molecular weight (Mw) of water-soluble polymers is typically between 1,000 and 5,000,000, 2,000 and 3,000,000, 5,000 and 2,000,000, 10,000 and 1,500,000, 20,000 and 500,000, 20,000 and 100,000, 20,000 and 80,000, 20,000 and 60,000, or 20,000 and 40,000.

[0024] Cationic polymers are polymers that have cationic groups such as amino groups and quaternary ammonium groups. Examples include polyacrylamide.

[0025] Anionic polymers are explained in section (B) below. Nonionic polymers are explained in section (E) below.

[0026] The lower limit of the water-soluble polymer content in the surface treatment composition may be 0.0001% by mass or more, 0.001% by mass or more, 0.005% by mass or more, or 0.01% by mass or more, based on 100% by mass of the total mass of the surface treatment composition (relative to the surface treatment composition). The upper limit of the water-soluble polymer content in the surface treatment composition may be 2.0% by mass or less, 1.5% by mass or less, 1.0% by mass or less, 0.5% by mass or less, 0.4% by mass or less, 0.3% by mass or less, or 0.2% by mass or less, based on 100% by mass of the total mass of the surface treatment composition (relative to the surface treatment composition). In one embodiment of the present invention, the content of the water-soluble polymer in the surface treatment composition is 0.0001% by mass or more and 2.0% by mass or less, 0.001% by mass or more and 1.5% by mass or less, 0.005% by mass or more and 1.0% by mass or less, 0.05% by mass or more and 0.5% by mass or less, 0.01% by mass or more and 0.5% by mass or less, 0.01% by mass or more and 0.4% by mass or less, 0.01% by mass or more and 0.3% by mass or less, or 0.01% by mass or more and 0.2% by mass or less.

[0027] [Solvent] The surface treatment composition of the present invention contains a solvent. The solvent has the function of dispersing or dissolving each component. The solvent preferably contains water, and more preferably contains only water. According to one embodiment of the present invention, 85% or more by mass, 90% or more by mass, 95% or more by mass, or 99% or more by mass of the solvent is composed of water (upper limit is 100% by mass). Alternatively, the solvent may be a mixed solvent of water and an organic solvent for the dispersion or dissolution of each component. In this case, examples of organic solvents that can be used include acetone, acetonitrile, ethanol, methanol, isopropanol, glycerin, ethylene glycol, propylene glycol, triethanolamine, etc., which are organic solvents that are miscible with water. Alternatively, these organic solvents may be used without mixing with water to disperse or dissolve each component, and then mixed with water. These organic solvents can be used individually or in combination of two or more.

[0028] From the viewpoint of preventing contamination of the polished object and interference with the action of other components, water that contains as little residue as possible is preferable. For example, water with a total transition metal ion content of 100 ppb or less is preferable. Here, the purity of the water can be increased by operations such as removing residual ions using ion exchange resin, removing foreign matter by filtration, and distillation. Specifically, it is preferable to use, for example, deionized water (ion-exchanged water), pure water, ultrapure water, or distilled water.

[0029] [pH] The pH of the surface treatment composition may be greater than 7.0, 7.5 or higher, 7.7 or higher, or 8.0 or higher. The pH of the surface treatment composition may be 13.0 or lower, 12.5 or lower, 12.0 or lower, 11.0 or lower, 10.0 or lower, 9.5 or lower, 9.0 or lower, or 8.5 or lower. The pH of the surface treatment composition may be greater than 7.0 and 13.0 or lower, 7.5 or higher and 12.5 or lower, 7.7 or higher and 12.0 or lower, 8.0 or higher and 11.0 or lower, 8.0 or higher and 10.0 or lower, 8.0 or higher and 9.5 or lower, 8.0 or higher and 9.0 or lower, or 8.0 or higher and 8.5 or lower.

[0030] <Repulsive Force> In the present invention, the repulsive force of the surface obtained when the surface is treated using the surface treatment composition under surface treatment condition A is 0.003 N / m or more. The repulsive force disclosed in the present invention is, simply put, the force that acts when abrasive grains approach and come into contact with a polished object during the surface treatment process, causing them to move away from each other. The repulsive force disclosed in the present invention is thought to be manifested mainly by two types of mechanisms: one is steric repulsion due to the protective film formed by surface treatment using the surface treatment composition; the other is electrostatic repulsion between the abrasive grains and the polished object that occurs in the surface treatment environment.

[0031] (Protective film) In one embodiment of the present invention, a protective film is formed during the surface treatment. During the surface treatment, a protective film is formed on the polished workpiece that inhibits contact of the abrasive grains. The "inhibition of contact of abrasive grains" can also be confirmed by the fact that the polishing speed of the polished workpiece treated with the surface treatment composition is relatively slower than the polishing speed of a polished workpiece without a protective film during surface treatment, which can serve as a control. In one embodiment of the present invention, the thickness of the protective film obtained using the surface treatment composition under surface treatment condition A is 0.5 nm or more, 0.7 nm or more, 0.8 nm or more, 0.9 nm or more, 1.0 nm or more, 1.1 nm or more, or 1.2 nm or more. The thickness of the protective film is usually 10 nm or less. The thickness of the protective film can be measured based on force curve measurement by AFM. The thickness of the protective film obtained by surface treatment under the above surface treatment condition A can be evaluated based on force curve measurement using AFM (manufacturer: Bruker; model number: Dimension IconIR (Model: SPN-211116-01); software name: NanoScope 10.0). Force curve measurement can be performed using an AFM probe with a DLC probe (B20-FMR, manufactured by NANOANDORE) under the following conditions. The thickness of the protective film in the examples was 0.2 to 1.2 nm. Except for Example 1, the thickness of the protective film was 0.7 to 1.2 nm.

[0032]

[0033] In order to achieve a surface repulsion force of 0.003 N / m or more, which is obtained when surface treatment is performed using a surface treatment composition under surface treatment condition A, by forming a protective film, it is important, as a prerequisite, to sufficiently adsorb the components that form the protective film (particularly the water-soluble polymer, which is its main component) onto the polished object.

[0034] For this purpose, for example, i) it is preferable to use a water-soluble polymer contained in the surface treatment composition and the polished object to be polished in the pH environment where the surface treatment step is performed, which have opposite signs of potential. For example, when the potential of the polished object to be polished in the pH environment where the surface treatment step is performed is negative, it is preferable to use a cationic water-soluble polymer as the water-soluble polymer contained in the surface treatment composition. Also, ii) when the potential of the water-soluble polymer contained in the surface treatment composition and the potential of the polished object to be polished in the pH environment where the surface treatment step is performed have the same sign, for example, when the water-soluble polymer contained in the surface treatment composition is an anionic water-soluble polymer and the potential of the polished object to be polished in the pH environment where the surface treatment step is performed is negative, they cause electrostatic repulsion and are difficult to adsorb. Therefore, it is preferable to add an adsorption aid for adsorbing them. Here, the adsorption aid refers to an agent having an electric charge with a sign opposite to that of the water-soluble polymer and the polished object to be polished. Also, in the form of ii), the amount of the adsorption aid and the ratio of the amount of the adsorption aid to the amount of the water-soluble polymer are important. For example, in order to sufficiently adsorb an anionic water-soluble polymer to a polished object to be polished having a negative potential, an adsorption aid with a sufficient amount and amount ratio corresponding thereto is required.

[0035] [Measurement of adsorption amount by QCM method] Measurement of the adsorption amount by the QCM method can be cited as a method for determining whether the water-soluble polymer, which is the main component for forming the protective film, can sufficiently adsorb to the polished object to be polished. The specific measurement method is according to the method described in the examples.

[0036] According to one embodiment of the present invention, the adsorption amount is more than 167 ng / cm ２ more than 170 ng / cm ２ or more, more than 200 ng / cm ２ or more, more than 300 ng / cm ２ or more, more than 400 ng / cm ２ or more, or more than 450 ng / cm ２ or more. By having such a lower limit value, it can be judged that the components for forming the protective film can adsorb to the polished object to be polished in a sufficient amount. According to one embodiment of the present invention, the adsorption amount is, for example, 1500 ng / cm ２ or less, or 1200 ng / cm ２The following is possible. Note that polyacrylic acid, a water-soluble polymer contained in the surface treatment composition of Comparative Example 1 in the Examples section described later, is anionic, and therefore it repels the negatively charged polished object (polished silicon nitride substrate) electrostatically, making adsorption difficult. For this reason, aminoethylpiperazine, which can function as an adsorption aid, is used, but the amount is set to be considerably less than the amount in the Examples, or the ratio of the amount of the adsorption aid to the amount of the anionic polymer is set to be small. Consequently, in Comparative Example 1, a protective film sufficient to achieve a repulsive force of 0.003 N / m or more is not formed. In contrast, the amount of adsorption aid contained in the surface treatment composition in the Examples is sufficiently large to make the repulsive force of the protective film 0.003 N / m or more, or the ratio of the amount of the adsorption aid to the amount of the anionic polymer is sufficiently large to make the repulsive force of the protective film 0.003 N / m or more. When the repulsive force increases due to the formation of a sufficient protective film, contact between the abrasive grains and the polished object is inhibited during the surface treatment process, the frequency of contact decreases, and the polishing speed of the polished object can be slowed down.

[0037] (Electrostatic Repulsion) Since PVA, a water-soluble polymer contained in the surface treatment composition of Example 1, is a nonionic polymer, it does not electrostatically attract and hardly adsorbs to the negatively charged polished object (polished silicon nitride substrate). Therefore, hardly any protective film is formed. However, the large repulsive force is understood to be due to sufficient electrostatic repulsion between the abrasive grains and the polished object. During surface treatment, if the zeta potentials of the abrasive grains and the polished object are of the same sign, electrostatic repulsion occurs, and the approach and contact of the abrasive grains with the polished object are inhibited. Therefore, the polishing speed of the polished object during surface treatment slows down.

[0038] According to one embodiment of the present invention, in the pH environment of the surface treatment, both the zeta potential (X) of the abrasive grains and the zeta potential (Y) of the polished object are negative. According to one embodiment of the present invention, in the pH environment of the surface treatment, both the zeta potential (X) of the abrasive grains and the zeta potential (Y) of the polished object are negative, and the sum of the absolute values ​​of the zeta potential (X) and the absolute values ​​of the zeta potential (Y) is greater than 31 mV, 33 mV or more, 36 mV or more, 39 mV or more, 42 mV or more, greater than 45 mV, 50 mV or more, 55 mV or more, 60 mV or more, 65 mV or more, or 70 mV or more. According to one embodiment of the present invention, in the environment described above, the zeta potential (X) of the abrasive grains and the zeta potential (Y) of the polished object are both negative, and the sum of the absolute values ​​of the zeta potential (X) and the zeta potential (Y) is 120 mV or less, 100 mV or less, or 80 mV or less. According to one embodiment of the present invention, in the environment described above, the zeta potential (X) of the abrasive grains and the zeta potential (Y) of the polished object are both negative, and the sum of the absolute values ​​of the zeta potential (X) and the zeta potential (Y) is greater than 31 mV and less than or equal to 120 mV, 33 mV or more and less than or equal to 120 mV, 36 mV or more and less than or equal to 120 mV, 39 mV or more and less than or equal to 100 mV, 42 mV or more and less than or equal to 100 mV, greater than 45 mV and less than or equal to 100 mV, 50 mV or more and less than or equal to 100 mV, 55 mV or more and less than or equal to 80 mV, 60 mV or more and less than or equal to 80 mV, 65 mV or more and less than or equal to 80 mV, or 70 mV or more and less than or equal to 80 mV. According to one embodiment of the present invention, in the environment described above, the zeta potential (X) of the abrasive grains and the zeta potential (Y) of the polished object are both positive, and the sum of the absolute values ​​of the zeta potential (X) and the zeta potential (Y) is greater than 45 mV and 100 mV or less, 50 mV or more and 100 mV or less, 55 mV or more and 100 mV or less, 60 mV or more and 100 mV or less, 65 mV or more and 100 mV or less, or 70 mV or more and 100 mV or less.

[0039] (Adhesion Force) According to one embodiment of the present invention, the adhesion force of the protective film is 0.0015 N / m or less, 0.0010 N / m or less, 0.0008 N / m or less, 0.0006 N / m or less, 0.0004 N / m or less, 0.0003 N / m or less, 0.0002 N / m or less, 0.0001 N / m or less, 0.0000 N / m or less, -0.0001 N / m or less, or -0.0002 N / m or less. Here, the adhesion force of the protective film is, simply put, an index that indicates how difficult it is for abrasive grains that come into contact with the protective film during the surface treatment process to separate from the protective film. If this value is large, the abrasive grains will not easily separate from the protective film during the surface treatment process, that is, the abrasive grains will not easily detach from the polished workpiece during surface treatment. A small adhesion force of the protective film reduces the number of effective abrasive grains that come into contact with the polished workpiece via the protective film. Therefore, the polishing efficiency decreases. The adhesion force of the protective film can be measured in AFM measurement by detecting the vertical component (cantilever deflection signal) that occurs when the probe attempts to move away from the surface of the protective film, out of the force acting on the surface of the protective film. A more specific method for measuring the adhesion force of the protective film is described in the examples.

[0040] According to one embodiment of the present invention, the adhesion force of the protective film is -0.0003 N / m or more, -0.0002 N / m or more, -0.0001 N / m or more, 0.0000 N / m or more, 0.0001 N / m or more, or 0.0002 N / m or more.

[0041] According to one embodiment of the present invention, the adhesion force of the protective film is -0.0003 N / m or more and 0.0015 N / m or less, -0.0003 N / m or more and 0.0004 N / m or less, -0.0002 N / m or more and 0.0003 N / m or less, -0.0001 N / m or more and 0.0002 N / m or less, or 0.0000 N / m or more and 0.0001 N / m or less.

[0042] <Description of Embodiments of Surface Treatment Composition> According to one embodiment of the present invention, the surface treatment composition comprises the following components (A) to (C), and the surface treatment composition is used for surface treatment of a polished object obtained by polishing the object using an abrasive composition. Therefore, according to one embodiment of the present invention, a surface treatment composition comprising the following components (A) to (C) is provided: (A) component: piperazine compound, (B) component: anionic polymer, (C) component: acid. The pH of the surface treatment composition is preferably greater than 7.0. In addition, in this embodiment, the surface treatment composition preferably further comprises at least one of the following components (D) and (E), and it is more preferable that the surface treatment composition comprises the following components (D) and (E).

[0043] According to one embodiment of the present invention, the surface treatment composition comprises component (E): a nonionic polymer and a solvent, and the surface treatment composition is used for surface treatment of a polished object obtained by polishing the object using an abrasive composition. Thus, according to one embodiment of the present invention, a surface treatment composition comprising component (E): a nonionic polymer and a solvent is provided. The pH of the surface treatment composition is preferably greater than 7.0. Furthermore, in this embodiment, the surface treatment composition preferably further comprises at least one of the following component (C') and component (D), and more preferably comprises the following component (C') and component (D).

[0044] <Component (A)> According to one embodiment of the present invention, the surface treatment composition contains a piperazine compound as component (A). A piperazine compound refers to a compound having a piperazine structure.

[0045] The piperazine compound as component (A) is preferably represented by the following chemical formula.

[0046]

[0047] In the above formula (a), R １ R represents an alkyl group having 1 to 10 carbon atoms, which may be substituted with a hydrogen atom or a primary, secondary, or tertiary amino group.２ This represents an alkyl group having 1 to 10 carbon atoms, which may be substituted with a primary, secondary, or tertiary amino group.

[0048] In the above formula (a), R １ and R ２ They may be the same or different from each other. Also, R １ and R ２ The alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. Specific examples of linear alkyl groups include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl groups. Specific examples of branched alkyl groups include isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, tert-pentyl group, neopentyl group, 1,2-dimethylpropyl group, isohexyl group, 1,3-dimethylbutyl group, 1-isopropylpropyl group, 1,2-dimethylbutyl group, 1,4-dimethylpentyl group, 3-ethylpentyl group, 2-methyl-1-isopropylpropyl group, 1-ethyl-3-methylbutyl group, 2-ethylhexyl group, 3-methyl-1-isopropylbutyl group, 2-methyl-1-isopropyl group, 1-tert-butyl-2-methylpropyl group, and isodecyl group. Specific examples of cyclic (alicyclic) alkyl groups include cycloalkyl groups with 3 to 10 carbon atoms, such as cyclopropyl group, cyclobutyl group, cyclopentyl group, and cyclohexyl group.

[0049] Among them, R １ and R ２ The alkyl group is preferably linear or branched, and more preferably linear. For the alkyl group, the upper limit of the number of carbon atoms is preferably 8 or less, more preferably 6 or less, even more preferably 5 or less, and particularly preferably 3 or less. On the other hand, the lower limit of the number of carbon atoms is preferably 2 or more. Therefore, as an example, R １ and R ２The number of carbon atoms in the alkyl group is preferably 1 to 8, more preferably 1 to 6, even more preferably 1 to 5, even more preferably 1 to 3, and particularly preferably 2 or 3.

[0050] The alkyl group described above may be substituted with at least one amino group from among primary, secondary, and tertiary amino groups, or it may be unsubstituted. In this specification, "primary amino group" means -NH ２ This is intended. Similarly, a "secondary amino group" is a functional group (-NHR) having one hydrogen atom and one organic group on a nitrogen atom, and the bond between one of the carbon atoms constituting the organic group and the nitrogen atom is a single bond. Ａ However, R Ａ (where represents an organic group). Similarly, a "tertiary amino group" is a functional group (-N(R)) having two identical or different organic groups on a nitrogen atom, where the bond between one of the carbon atoms constituting each organic group and the nitrogen atom is a single bond. Ｂ ) (Caution Ｃ ); however, R Ｂ and R Ｃ Each of these represents an organic group independently. Ａ ) constitutes R Ａ , and the above tertiary amino group (-N(R Ｂ ) (Caution Ｃ )) constitutes R Ｂ and R Ｃ An organic group as defined above means a group containing a carbon atom. Ａ , R Ｂ or R Ｃ Each of these is preferably a hydrocarbon group, more preferably an alkyl group or an aryl group, and even more preferably an alkyl group. Ａ , R Ｂ and R Ｃ The number of carbon atoms in the alkyl group is not particularly limited, but from the viewpoint of excellent removal of component (A) itself, it is preferably 1 to 10.

[0051] Here, the alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. Specific examples of such alkyl groups are given above in R １ and R ２ Examples of alkyl groups as listed above are similar to those mentioned above. Examples of secondary amino groups having the above alkyl group include alkylamino groups having 1 to 10 carbon atoms, such as methylamino group, ethylamino group, n-propylamino group, n-butylamino group, isobutylamino group, n-hexylamino group, n-heptylamino group, n-octylamino group, n-nonylamino group, and n-decylamino group. Examples of tertiary amino groups having the above alkyl group include dialkylamino groups having 2 to 20 carbon atoms, such as dimethylamino group, diethylamino group, di-n-propylamino group, di-n-butylamino group, and methylethylamino group.

[0052] In the above formula (a), R １ and R ２ When the alkyl group is substituted with any of the primary, secondary, or tertiary amino groups, it is preferable that the alkyl group is substituted with a primary or tertiary amino group, and more preferably with a primary amino group.

[0053] More specifically, R １ and R ２ When an alkyl group is substituted with any of the primary, secondary, or tertiary amino groups, the alkyl group is a primary amino group (-NH ２ A methyl group substituted with (-NH) or a primary amino group (-NH) ２ Ethyl group substituted with (-NH) primary amino group (-NH) ２ Preferably, the group is an n-propyl group substituted with a primary amino group (-NH), a methyl group substituted with a dimethylamino group, an ethyl group substituted with a dimethylamino group, or an n-propyl group substituted with a primary amino group (-NH). ２ Ethyl group substituted with (-NH) primary amino group (-NH) ２ It is more preferable that the n-propyl group is substituted with a primary amino group (-NH), or that the ethyl group is substituted with a primary amino group (-NH). ２Ethyl groups substituted with (-NH) or primary amino groups (-NH) ２ It is more preferably an n-propyl group substituted with a primary amino group (-NH ２ It is particularly preferable that the n-propyl group is substituted with ).

[0054] In addition, in the above formula (a), R １ and R ２ At least one of them is an alkyl group substituted with any of primary to tertiary amino groups, but preferably R １ is a hydrogen atom and R ２ R is an alkyl group substituted with any of the primary, secondary, or tertiary amino groups, or １ and R ２ Both are alkyl groups substituted with any of primary to tertiary amino groups, more preferably R １ is a hydrogen atom and R ２ is an alkyl group substituted with a primary amino group, or R １ and R ２ Both are alkyl groups substituted with primary or tertiary amino groups, and R is particularly preferred. １ is a hydrogen atom and R ２ is an alkyl group substituted with a primary amino group, or R １ and R ２ Both are alkyl groups substituted with primary amino groups.

[0055] Specifically, examples of piperazine compounds represented by formula (a) include 1-methylpiperazine, 1-ethylpiperazine, 1-propylpiperazine, aminomethylpiperazine, aminoethylpiperazine, aminopropylpiperazine, 1-(2-dimethylaminoethyl)-4-methylpiperazine, 1-(2-dimethylaminoethyl)-4-ethylpiperazine, 1-(2-dimethylaminoethyl)-4-propylpiperazine, 1-(2-diethylaminoethyl)-4-methylpiperazine, 1-(2-diethylaminoethyl)-4-ethylpiperazine, 1-(2-diethylaminoethyl)-4-propylpiperazine, 1,4-bis(3-aminomethyl)piperazine, 1,4-bis(3-aminoethyl)piperazine, and 1,4-bis(3-aminopropyl)piperazine.

[0056] The piperazine compound as component (A) preferably has two or more amino groups whose pKa is greater than the pH of the surface treatment composition. In this specification, "amino groups whose pKa is greater than the pH of the surface treatment composition" is also referred to as "large pKa amino groups". Here, the number of large pKa amino groups present in the piperazine compound is two or more, which allows the piperazine compound to interact with both the surface of the polished object and component (B). As a result, a protective film formed by the adsorption of component (B) can be sufficiently formed on the surface of the polished object. The number of large pKa amino groups present in the piperazine compound is preferably two or more and five or less, more preferably two or more and four or less, even more preferably two or three, and particularly preferably two.

[0057] Furthermore, it is preferable that the difference between the pKa of the piperazine compound as component (A) and the pH of the surface treatment composition be as large as possible. Specifically, the difference between the maximum pKa of the amino group present in the piperazine compound (maximum pKa) and the pH of the surface treatment composition (=maximum pKa-pH) is, for example, 0.5 or more, preferably 0.6 or more, more preferably 1.0 or more, even more preferably exceeding 1.30, even more preferably 1.50 or more, particularly preferably 1.60 or more, and most preferably 2.00 or more. Since a larger difference between the maximum pKa of the amino group present in the piperazine compound (maximum pKa) and the pH of the surface treatment composition (=maximum pKa-pH) is preferable, there is no particular upper limit to the above difference, but for example, it is 4.0 or less, preferably 3.5 or less, and more preferably 3.0 or less.

[0058] pKa (acid dissociation constant) is a value calculated from the concentrations of each component in the acid dissociation equilibrium of piperazine compounds in water at 25°C. Specifically, it is the logarithmic value of the value Ka calculated by the following formula.

[0059]

[0060] In this specification, the pKa (acid dissociation constant) of the amino group present in piperazine compounds was calculated using ChemSketch, a structural formula drawing software. Specifically, the structural formula of each compound was written out, and the pKa was automatically calculated from that structure.

[0061] In this specification, the maximum pKa (maximum pKa) of the amino groups present in the piperazine compound is the value that is the highest among the pKa values ​​of each amino group measured above.

[0062] (A) Among the piperazine compounds that are component (A), it is preferable that the proportion of piperazine compounds represented by the above formula (a) and having two or more amino groups whose pKa is greater than the pH of the surface treatment composition is 80% by mass or more, 90% by mass or more, 95% by mass or more, 99% by mass or more, or 100% by mass.

[0063] (A) Component is R１ R is an alkyl group having 1 to 5 carbon atoms (especially a linear alkyl group) which may be substituted with a hydrogen atom or a primary or tertiary amino group; ２ It is preferable that the compound comprises a piperazine compound represented by the above formula (a), which is an alkyl group having 1 to 5 carbon atoms (particularly a linear alkyl group) that may be substituted with a primary or tertiary amino group. In this embodiment, component (A) is R １ R is an alkyl group having 1 to 5 carbon atoms (especially a linear alkyl group) which may be substituted with a hydrogen atom or a primary or tertiary amino group; ２ It is more preferable that the compound represented by formula (a) above is an alkyl group having 1 to 5 carbon atoms (especially a linear alkyl group) which may be substituted with a primary or tertiary amino group.

[0064] (A) Component is R １ R is an alkyl group having 1 to 5 carbon atoms (especially a linear alkyl group) which may be substituted with a hydrogen atom or a primary or tertiary amino group; ２ It is preferable that the compound comprises a piperazine compound represented by the above formula (a), which is an alkyl group having 1 to 5 carbon atoms (particularly a linear alkyl group) substituted with a primary or tertiary amino group. In this embodiment, component (A) is R １ R is an alkyl group having 1 to 5 carbon atoms (especially a linear alkyl group) which may be substituted with a hydrogen atom or a primary or tertiary amino group; ２ It is more preferable that the compound represented by formula (a) above is an alkyl group having 1 to 5 carbon atoms (especially a linear alkyl group) substituted with a primary or tertiary amino group.

[0065] (A) Component is R １ R is an alkyl group having 1 to 3 carbon atoms (especially a linear alkyl group) which may be substituted with a hydrogen atom or a primary or tertiary amino group; ２It is particularly preferable that it contains a piperazine compound represented by the above formula (a), which is an alkyl group having 1 to 3 carbon atoms substituted with a primary amino group (especially a linear alkyl group). In this embodiment, component (A) is R １ R is an alkyl group having 1 to 3 carbon atoms (especially a linear alkyl group) which may be substituted with a hydrogen atom or a primary or tertiary amino group; ２ It is more preferable that the compound represented by formula (a) above is an alkyl group having 1 to 3 carbon atoms substituted with a primary amino group (especially a linear alkyl group).

[0066] (A) The piperazine compounds that can be used as component (A) may be manufactured by synthesis or may be commercially available. The piperazine compounds as component (A) may be used alone or in combination of two or more.

[0067] The amount of component (A) in the surface treatment composition should be sufficient to adsorb component (B) onto the polished object. The preferred amount of component (A), based on 100% of the total mass of the surface treatment composition (relative to the surface treatment composition), is in the following order: over 0.052% by mass, 0.06% by mass or more, 0.08% by mass or more, 0.1% by mass or more, 0.2% by mass or more, 0.3% by mass or more, 0.4% by mass or more, and 0.5% by mass or more. By setting such lower limits, component (A) functions sufficiently as an adsorption aid for adsorbing component (B) onto the polished object (especially a polished substrate having nitrogen-silicon bonds), and a suitable protective film can be formed on the polished object (especially a polished substrate having nitrogen-silicon bonds). The upper limit of the content of component (A) in the surface treatment composition is preferably 2.0% by mass or less, more preferably 1.5% by mass or less, even more preferably 1.2% by mass or less, and particularly preferably 1.1% by mass or less, with respect to the total mass of the surface treatment composition being 100% by mass (relative to the surface treatment composition), from the viewpoint of preventing aggregation of abrasive grains remaining on the surface. In one embodiment of the present invention, the content of component (A) is greater than 0.052% by mass and 2.0% by mass or less, 0.001% by mass or more and 2.0% by mass or less, 0.005% by mass or more and 1.5% by mass or less, 0.01% by mass or more and 1.2% by mass or less, 0.03% by mass or more and 1.1% by mass or less, 0.10% by mass or more and 1.0% by mass or less, 0.25% by mass or more and 0.9% by mass or less, or 0.30% by mass or more and 0.8% by mass or less, with respect to the total mass of the surface treatment composition being 100% by mass (relative to the surface treatment composition).

[0068] Furthermore, if the surface treatment composition contains two or more components (A), the content of component (A) refers to the total amount of these components.

[0069] <Component (B)> According to one embodiment of the present invention, the surface treatment composition includes an anionic polymer as component (B). Herein, "anionic polymer" refers to a polymer having anionic groups such as carboxylic acid groups, sulfonic acid groups, or phosphate groups or salts thereof in its molecule.

[0070] Component (B) interacts with component (A) and adsorbs to component (A), thereby forming a protective film on the polished object.

[0071] Anionic polymers are polymers having identical (homopolymer) or different (copolymer) repeating structural units, and are typically compounds with a weight-average molecular weight (Mw) of 1,000 or more. When the anionic polymer is a copolymer, the copolymer may take the form of a block copolymer, random copolymer, graft copolymer, or alternating copolymer.

[0072] Examples of anionic polymers include polycarboxylic acids such as polyacrylic acid, polyacrylic acid copolymers, polymethacrylic acid, polymethacrylic acid copolymers, poly(acrylic acid-polymethacrylic acid) copolymers, maleic anhydride copolymers, carboxymethylcellulose, and alginic acid; polysulfonic acids such as polystyrene sulfonic acid, polystyrene sulfonic acid copolymers, polynaphthalene sulfonic acid, and acrylamide-t-butylsulfonic acid; poly(carboxylic acid-sulfonic acid) (copolymers of carboxylic acid and sulfonic acid); and salts thereof. Furthermore, not only those having such a main chain structure, but also graft copolymers having anionic polymer structures in the side chains can be suitably used.

[0073] When anionic polymers are in the form of salts, examples include alkali metal salts such as lithium salts, sodium salts, potassium salts, rubidium salts, and cesium salts, as well as salts of Group 2 elements such as magnesium salts, calcium salts, strontium salts, and barium salts, for polycarboxylic acids, polysulfonic acids, and poly(carboxylic acid-sulfonic acids).

[0074] These anionic polymers can be used individually or in combination of two or more.

[0075] Among these, anionic polymers preferably have a carboxylic acid group, a sulfonic acid group or a salt thereof, more preferably have a carboxylic acid group or a sulfonic acid group or an alkali metal salt thereof, even more preferably have a carboxylic acid group or a sulfonic acid group, and particularly preferably have a carboxylic acid group.

[0076] Component (B) may include anionic polymers other than those listed above. Preferably, component (B) consists only of the anionic polymers listed above.

[0077] Component (B) preferably comprises at least one anionic polymer selected from the group consisting of poly(meth)acrylic acid, polystyrene sulfonic acid, and poly(carboxylic acid-sulfonic acid) (a copolymer of carboxylic acid and sulfonic acid), and salts thereof. In this embodiment, component (B) is more preferably at least one anionic polymer selected from the group consisting of poly(meth)acrylic acid, polystyrene sulfonic acid, and poly(carboxylic acid-sulfonic acid) (a copolymer of carboxylic acid and sulfonic acid), and salts thereof.

[0078] Component (B) preferably comprises at least one anionic polymer selected from the group consisting of poly(meth)acrylic acid and polystyrene sulfonic acid, and their salts. In this embodiment, component (B) is more preferably at least one anionic polymer selected from the group consisting of poly(meth)acrylic acid and polystyrene sulfonic acid, and their salts. This embodiment is particularly applicable when the polished workpiece contains a material having nitrogen-silicon bonds.

[0079] Component (B) preferably comprises at least one anionic polymer selected from the group consisting of poly(meth)acrylic acid, polystyrene sulfonic acid, and their alkali metal salts. In this embodiment, component (B) is more preferably at least one anionic polymer selected from the group consisting of poly(meth)acrylic acid, polystyrene sulfonic acid, and their alkali metal salts. This embodiment is particularly applicable when the polished object contains a material having nitrogen-silicon bonds.

[0080] Component (B) preferably comprises at least one of poly(meth)acrylic acid and its alkali metal salt. In this embodiment, component (B) is more preferably at least one of poly(meth)acrylic acid and its alkali metal salt. This embodiment is particularly applicable when the polished workpiece contains a material having nitrogen-silicon bonds.

[0081] It is preferable that the proportion of poly(meth)acrylic acid or its salt among component (B) contained in the surface treatment composition is 80% by mass or more, 85% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more (upper limit, 100% by mass).

[0082] Furthermore, component (B) may also preferably include at least one anionic polymer selected from the group consisting of polystyrene sulfonic acid, poly(carboxylic acid-sulfonic acid) (a copolymer of carboxylic acid and sulfonic acid), and salts thereof. In this embodiment, it is even more preferable that component (B) consists only of at least one anionic polymer selected from the group consisting of polystyrene sulfonic acid, poly(carboxylic acid-sulfonic acid) (a copolymer of carboxylic acid and sulfonic acid), and salts thereof. This embodiment is particularly applicable when the polished workpiece contains silicon dioxide.

[0083] Component (B) may also preferably include at least one anionic polymer selected from the group consisting of polystyrene sulfonic acid and poly(carboxylic acid-sulfonic acid) (a copolymer of carboxylic acid and sulfonic acid), and their alkali metal salts. In this embodiment, it is more preferable that component (B) consists only of at least one anionic polymer selected from the group consisting of polystyrene sulfonic acid and poly(carboxylic acid-sulfonic acid) (a copolymer of carboxylic acid and sulfonic acid), and their alkali metal salts. This embodiment is particularly applicable when the polished workpiece contains silicon dioxide.

[0084] Component (B) may also preferably contain at least one of polystyrene sulfonic acid and its alkali metal salt. In this embodiment, component (B) is more preferably at least one of polystyrene sulfonic acid and its alkali metal salt. This embodiment is particularly applicable when the polished workpiece contains silicon dioxide.

[0085] The lower limit of the weight-average molecular weight (Mw) of the anionic polymer (e.g., poly(meth)acrylic acid) is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 5,000 or more, even more preferably 10,000 or more, and particularly preferably 20,000 or more. The upper limit of the weight-average molecular weight (Mw) of the anionic polymer (e.g., poly(meth)acrylic acid) is 5,000,000 or less, 3,000,000 or less, 2,000,000 or less, 1,500,000 or less, 500,000 or less, 100,000 or less, 80,000 or less, 60,000 or less, or 40,000 or less.

[0086] For example, the weight-average molecular weight (Mw) of anionic polymers (e.g., poly(meth)acrylic acid) is typically between 1,000 and 5,000,000, 2,000 and 3,000,000, 5,000 and 2,000,000, 10,000 and 1,500,000, 20,000 and 500,000, 20,000 and 100,000, 20,000 and 80,000, 20,000 and 60,000, or 20,000 and 40,000.

[0087] The weight-average molecular weight (Mw) of the anionic polymer can be measured as a polyethylene glycol equivalent using gel permeation chromatography (GPC). Details of the measurement method are described in the examples below.

[0088] (B) The anionic polymer that can be used as component may be manufactured by synthesis or may be a commercially available product. Examples of commercially available products include polyacrylic acid (manufactured by Toagosei Co., Ltd.), sodium polystyrene sulfonate (manufactured by Tosoh Finechem Co., Ltd.), and copolymer of carboxylic acid and sulfonic acid (sodium salt) (manufactured by Toagosei Co., Ltd.).

[0089] (B) The anionic polymer as component can be used alone or in combination of two or more types.

[0090] The content of component (B) in the surface treatment composition is set appropriately depending on the type of component (B) used and the desired effect. The preferred content of component (B) is, in order of 0.0001% by mass or more, 0.001% by mass or more, 0.003% by mass or more, 0.005% by mass or more, 0.007% by mass or more, and 0.01% by mass or more, with the total mass of the surface treatment composition being 100% by mass (relative to the surface treatment composition). Setting the content of component (B) in the surface treatment composition is important in order to form a sufficient amount of protective film on the polished workpiece which has a negative charge under the surface treatment environment. Having such a lower limit ensures sufficient interaction between component (B) and component (A) and sufficient adsorption of component (A) to the polished workpiece. Furthermore, the upper limit of the content of component (B) in the surface treatment composition is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, even more preferably 0.3% by mass or less, and particularly preferably 0.1% by mass or less, with the total mass of the surface treatment composition being 100% by mass (relative to the surface treatment composition). In one embodiment of the present invention, it is 0.0001% by mass or more and 1.0% by mass or less, 0.001% by mass or more and 0.5% by mass or less, 0.005% by mass or more and 0.3% by mass or less, or 0.01% by mass or more and 0.1% by mass or less. Note that if the surface treatment composition contains two or more types of component (B), the content of component (B) refers to the total amount of these components.

[0091] Alternatively, or in addition to the above, setting the mixing ratio of component (A) and component (B) in the surface treatment composition is important in order to form a sufficient amount of protective film on the polished workpiece which has a negative charge under the surface treatment environment. The mixing ratio of component (A) to component (B) (component (A) / component (B) content ratio) (mass ratio) is preferably greater than 1.3, 1.5 or more, 2 or more, 5 or more, 10 or more, 20 or more, 25 or more, 30 or more, 35 or more, 40 or more, 45 or more, and 50 or more, in that order. Having such a lower limit ensures sufficient interaction between component (B) and component (A) and sufficient adsorption of component (A) onto the polished workpiece.

[0092] As described above, polyacrylic acid, a water-soluble polymer contained in the surface treatment composition of Comparative Example 1, is anionic, and therefore repels the negatively charged polished object (polished silicon nitride substrate), making adsorption difficult. In Comparative Example 1, aminoethylpiperazine, which functions as an adsorption aid, is used, but the amount is set to be considerably less than the amount in the example, or the ratio of the amount of adsorption aid to the amount of anionic polymer is set to be small. As a result, in Comparative Example 1, the repulsive force is not 0.003 N / m or more. In contrast, the amount of adsorption aid contained in the surface treatment composition in the example is sufficiently large to make the repulsive force of the protective film 0.003 N / m or more, or the ratio of the mass of the adsorption aid to the mass of the anionic polymer is sufficiently large to make the repulsive force of the protective film 0.003 N / m or more. Therefore, the repulsive force of the resulting protective film is 0.003 N / m or more. In one embodiment of the present invention, the mixing ratio of component (A) to component (B) (component (A) / component (B) content ratio) (mass ratio) is, for example, 100 or less, 90 or less, 80 or less, 70 or less, 60 or less, or 55 or less. In one embodiment of the present invention, the mixing ratio of component (A) to component (B) (component (A) / component (B) content ratio) (mass ratio) is greater than 1.3 and less than or equal to 100, 1.5 or more and less than or equal to 100, 2 or more and less than or equal to 90, 5 or more and less than or equal to 80, 10 or more and less than or equal to 70, 20 or more and less than or equal to 60, 25 or more and less than or equal to 50, 30 or more and less than or equal to 55, 35 or more and less than or equal to 55, 40 or more and less than or equal to 55, or 50 or more and less. Note that if the surface treatment composition contains two or more types of component (A), the content of component (A) refers to the total amount of these components. Similarly, if the surface treatment composition contains two or more components (B), the content of components (B) refers to their total amount.

[0093] <Acid (component (C))> According to one embodiment of the present invention, the surface treatment composition contains an acid as component (C). While component (A) can function as a pH adjusting agent to increase pH, component (C) can also function as a pH adjusting agent to decrease pH.

[0094] An acid can be a Lewis acid, and a Lewis acid can be a Brønsted acid. An acid can be either organic or inorganic. Examples of organic acids include formic acid, acetic acid, glycolic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, docosahexaenoic acid, eicosapentaenoic acid, lactic acid, malic acid, tartaric acid, citric acid, benzoic acid, phthalic acid, and isophthalic acid. Examples of carboxylic acids include terephthalic acid, salicylic acid, gallic acid, melitic acid, cinnamic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, aconitic acid, amino acids, anthranilic acid, sulfonic acids (such as isethionic acid and camphor sulfonic acid), and organic phosphonic acids (such as hydroxyethylidene diphosphonic acid and diethylenetriaminepentamethylenephosphonic acid). Examples of inorganic acids include nitric acid, carbonic acid, hydrochloric acid, sulfuric acid, thiocyanic acid, phosphoric acid, hypophosphorous acid, phosphorous acid, phosphonic acid, boric acid, hydrofluoric acid, orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, and hexametaphosphoric acid.

[0095] According to one embodiment of the present invention, component (C) comprises at least one selected from the group consisting of acetic acid, nitric acid, sulfuric acid, phosphoric acid, thiocyanic acid, and hydrochloric acid.

[0096] (C) The acid in the component is preferably an acid that hydrates easily. The hydration Gibbs free energy (hydration energy) is an indicator used to evaluate whether an acid hydrates easily. To explain this, an electrolyte, which is an acid, dissolves in water to form an aqueous solution. Breaking down an ionic crystal into separate free ions usually requires 100 to 1000 kJ / mol of energy (ΔhydrateG). On the other hand, water molecules are polarized, and due to electrostatic interactions between ions and water molecules, the water molecules surround the ions, become oriented and stabilized, and form hydrated ions. Hydration also requires energy to break down the water structure and orient the water molecules. When electrolytes dissolve in water, some are exothermic and others are endothermic. The hydration Gibbs free energy is expressed by enthalpy ΔH and entropy ΔS, and is represented by the following equation. When ΔH is negative, it is exothermic, and when it is positive, it is endothermic. Regardless of whether it is exothermic or endothermic, when ΔH < TΔS, ΔG is negative and a dissolution reaction occurs. The larger the absolute value, the stronger the hydration and stabilization.

[0097] ΔG = ΔH - TΔS The Gibbs energy is calculated based on the hydrated molar Gibbs energy ΔhydG (kJ / mol) in the following references, and is calculated per mole of acid added to the surface treatment composition.

[0098] - Y. Marcus, Thermodynamics of Solvation of Ions, J. CHEM. SOC. FARADAY TRANS., 1991, 87(18), 2995-2999. - Takao Kodama, What is the energy of ATP?, Biophysics 50(2), 094-095 (2010).

[0099]

[0100] (C) The hydration energy of the acid is preferably -2000 kJ / mol or more, -1800 kJ / mol or more, -1600 kJ / mol or more, -1400 kJ / mol or more, -1200 kJ / mol or more, -1000 kJ / mol or more, -800 kJ / mol or more, -600 kJ / mol or more, -400 kJ / mol or more, or -350 kJ / mol or more.

[0101] Note that the hydrated molar Gibbs energy is an acid-specific value, and the hydrated energy of the acid in the surface treatment composition can be calculated by multiplying this value by the number of moles added.

[0102] If the hydration energy of the acid contained in the surface treatment composition is negative, the electrolyte will dissolve, and if the absolute value is large, the acid will attract the water contained in the surface treatment composition as a solvent, causing water to accumulate around the acid, while the amount of water around the polymer (especially component (B)) will be relatively low. The polymer (especially component (B)) that has had water removed will shrink, and as a result, the intrinsic viscosity of the polymer (especially component (B)) will decrease.

[0103] Here, intrinsic viscosity, also known as intrinsic viscosity, is an important physical property of polymer solutions. It is proportional to the increase in viscosity when one polymer molecule is dissolved in an infinite amount of solvent, and serves as an indicator that reflects the shape of the polymer chain. Intrinsic viscosity can be calculated as follows.

[0104] When the viscosity of a polymer solution is η and the viscosity of the solvent is ηs, the rate of increase in viscosity is called the specific viscosity ηsp, and it is calculated by the following formula.

[0105] ηsp = (η - ηs) / ηs The increase in viscosity per unit concentration c of polymer is called the reduced viscosity ηred, and is calculated using the following formula.

[0106] ηred = ηsp / c Several diluted solutions of the polymer solution are prepared, their reduced viscosity is determined, and the relationship between concentration and reduced viscosity is plotted. The intrinsic viscosity of the polymer can be obtained from the intercept of the linear approximation.

[0107] Because the shrunk polymer (especially component (B)) has a dense structure, the protective film formed on the polished workpiece is of high density. Therefore, even if the surface treatment process is carried out in the presence of abrasive grains, the protective film significantly suppresses contact between the abrasive grains and the polished workpiece, thereby slowing down the polishing speed of the resulting polished workpiece.

[0108] (C) As a component, a higher hydration energy of the acid is preferable, but the electrolyte (acid) must be dissolved, and for that to be the case, the value must be negative, so it must be 0 kJ / mol or less. A higher hydration energy of the acid is preferable, so from that viewpoint, the preference is in the order of phosphoric acid < sulfuric acid < acetic acid < hydrochloric acid < nitric acid < thiocyanic acid.

[0109] According to one embodiment of the present invention, the hydration energy of the acid as component (C) is -2000 kJ / mol or more and 0 kJ / mol or less, -2000 kJ / mol or more and -100 kJ / mol or less, -1800 kJ / mol or more and 0 kJ / mol or less, -1600 kJ / mol or more and 0 kJ / mol or less, -1400 kJ / mol or more and 0 kJ / mol or less, -1200 kJ / mol or more and 0 kJ / mol or less, -1000 kJ / mol or more and 0 kJ / mol or less, -800 kJ / mol or more and -100 kJ / mol or less, -600 kJ / mol or more and -100 kJ / mol or less, -400 kJ / mol or more and -100 kJ / mol or less, or -350 kJ / mol or more and -100 kJ / mol or less.

[0110] <Base (component (C'))> According to one embodiment of the present invention, the surface treatment composition contains a base as component (C'). Component (C') can function as a pH adjuster to increase pH. Note that component (C') does not contain component (A) mentioned above.

[0111] (C') Component may include alkali metal hydroxides such as potassium hydroxide (KOH) and sodium hydroxide (NaOH); potassium carbonate (K ２ CO ３ ), sodium carbonate (Na ２ CO ３ Examples include alkali metal carbonates such as ), hydroxides of Group 2 elements, ammonia (ammonium hydroxide), and organic bases such as quaternary ammonium hydroxide compounds.

[0112] According to one embodiment of the present invention, the amount of base (component (C')) in the surface treatment composition may be sufficient to adjust the pH of the surface treatment composition to the lower limit, upper limit, or range described above in [pH]. For example, by setting the pH of the surface treatment composition to above 7.0, the zeta potential of the surface of abrasive grains (e.g., silica such as colloidal silica) brought in from the preceding polishing process becomes negative during the surface treatment. If the zeta potential of the polished object to be surface treated is also negative during the surface treatment process, electrostatic repulsion occurs between the abrasive grains and the polished object. The occurrence of electrostatic repulsion can significantly suppress the polishing speed of the polished object.

[0113] <Polishing Speed ​​of Polished Objects> As described above, the protective film formed by the surface treatment composition of one embodiment of the present invention also functions as a steric repulsion layer in certain aspects, and therefore can significantly slow down the polishing speed of polished objects. Furthermore, the surface treatment composition of one embodiment of the present invention is prepared so that the zeta potential of abrasive grains introduced from, for example, the previous polishing process during the surface treatment process has the same sign as the zeta potential of the polished object. Therefore, the polishing speed of polished objects during surface treatment is significantly suppressed by steric repulsion by the protective film or electrostatic repulsion of abrasive grains with the polished object. When the surface treatment composition of the present invention is applied to a polished object, the polishing speed of the polished object during surface treatment may be less than 3.6 Å / min, 2.4 Å / min or less, 2.2 Å / min or less, 2.0 Å / min or less, 1.8 Å / min or less, 1.6 Å / min or less, 1.4 Å / min or less, 1.2 Å / min or less, 1.0 Å / min or less, 0.8 Å / min or less, 0.6 Å / min or less, or 0.4 Å / min or less. In principle, the desired elimination of steps has already been achieved in the preceding polishing process by controlling the polishing speed of the polished object to be constant. According to the present invention, the polishing speed of the polished object in the subsequent surface treatment process can be kept low, thus reducing the risk of steps that have already been eliminated reappearing. According to one embodiment of the present invention, when the surface treatment composition of the present invention is applied to a polished object, the polishing speed of the polished object during surface treatment may be, for example, 0.2 Å / min or more, 0.5 Å / min or more, 0.7 Å / min or more, 1.0 Å / min or more, 1.2 Å / min or more, 1.4 Å / min or more, or 1.5 Å / min or more.

[0114] <Component (D)> According to one embodiment of the present invention, the surface treatment composition preferably contains the following buffering agent: Component (D): Formula: A-COO-NH ４ ＋ A buffering agent represented by (A being an alkyl group or phenyl group having 1 to 10 carbon atoms). Formula as component (D): A-COO-NH ４ ＋The buffer represented by (A is an alkyl group or a phenyl group having 1 to 10 carbon atoms) is also simply referred to as "buffer" or "ammonium monocarboxylic acid" or "ammonium monocarboxylic acid". In this specification, the "buffer" means a substance that imparts a buffering action to the surface treatment composition (solution) to keep the pH constant.

[0115] Component (D) may contain components other than the buffer represented by the above formula: A - COO - NH ４ ＋ (for example, a known buffer), but from the viewpoint of further improving the effects of the present invention, component (D) is the above formula: A - COO - NH ４ ＋ It is preferably composed of the buffer represented by (component (D) is the buffer represented by the above formula: A - COO - NH ４ ＋ ). The presence of component (D) can suppress the polishing rate of the polished object to be polished. That is, in a preferred form of the present invention, component (D) is the above formula: A - COO - NH ４ ＋ It is composed of the buffer represented by (component (D) is the buffer represented by the above formula: A - COO - NH ４ ＋ ).

[0116] In the above formula: A - COO - NH ４ ＋ A is an alkyl group or a phenyl group having 1 to 10 carbon atoms. Here, as the alkyl group, R in the above formula (a) １ and R ２Examples of alkyl groups similar to those given as specific examples for alkyl groups are provided. Of these, from the viewpoint of further improving the effects of the present invention, A is preferably a linear or branched alkyl group having 1 to 8 carbon atoms, more preferably a linear or branched alkyl group having 1 to 3 carbon atoms, even more preferably a methyl group (ammonium acetate) or an ethyl group (ammonium propionate), and particularly preferably a methyl group (ammonium acetate). That is, in a preferred embodiment of the present invention, the buffering agent is the above formula: A-COO-NH, where A is a linear or branched alkyl group having 1 to 8 carbon atoms. ４ ＋ This is shown. In a more preferred embodiment of the present invention, the buffer is the above formula: A-COO-NH, where A is a linear or branched alkyl group having 1 to 3 carbon atoms. ４ ＋ As shown. In a further preferred embodiment of the present invention, the buffer is the above formula: A-COO-NH where A is a methyl group or an ethyl group. ４ ＋ This is represented by (the buffering agent is ammonium acetate or ammonium propionate). In a particularly preferred embodiment of the present invention, component (D) (buffering agent) comprises ammonium acetate. In the most preferred embodiment of the present invention, component (D) (buffering agent) is ammonium acetate. According to one embodiment of the present invention, 85% or more by mass, 90% or more by mass, 95% or more by mass, or 99% or more by mass of component (D) contained in the surface treatment composition is composed of ammonium acetate (upper limit is 100% by mass).

[0117] The content of component (D) in the surface treatment composition is set appropriately according to the type of component (D) used and the desired effect. The content of component (D) is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and particularly preferably 0.01% by mass or more, based on 100% by mass of the total mass of the surface treatment composition (relative to the surface treatment composition). Furthermore, the upper limit of the content of component (D) in the surface treatment composition is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and particularly preferably 0.1% by mass or less, based on 100% by mass of the total mass of the surface treatment composition (relative to the surface treatment composition). In one embodiment of the present invention, the content of component (D) is 0.001% by mass or more and 0.5% by mass or less, 0.005% by mass or more and 0.3% by mass or less, or 0.01% by mass or more and 0.1% by mass or less, based on 100% by mass of the total mass of the surface treatment composition (relative to the surface treatment composition). Furthermore, if the surface treatment composition contains two or more components (D), the content of component (D) refers to the total amount of these components.

[0118] Alternatively, or in addition to the above, the mixing ratio of component (A) and component (D) in the surface treatment composition is set appropriately according to the types of component (A) and component (D) used and the desired effect. The mixing ratio of component (A) to component (D) (component (A) / component (D) content ratio) (mass ratio) is preferably 0.01 or more, more preferably 0.1 or more, even more preferably 0.5 or more, even more preferably greater than 0.5, particularly preferably 5 or more, and most preferably 10 or more. The mixing ratio of component (A) to component (D) (component (A) / component (D) content ratio) (mass ratio) is preferably 50 or less, more preferably 40 or less, and particularly preferably 20 or less. In one embodiment of the present invention, the mixing ratio of component (A) to component (D) (component (A) / component (D) content ratio) (mass ratio) is 0.01 to 50, 0.1 to 40, 0.5 to 40, greater than 0.5 and 40 or less, 5 to 40 or less, or 10 to 20 or less. Note that if the surface treatment composition contains two or more types of component (A), the content of component (A) refers to the total amount of these components. Similarly, if the surface treatment composition contains two or more types of component (D), the content of component (D) refers to the total amount of these components.

[0119] <Component (E)> According to one embodiment of the present invention, the surface treatment composition preferably further comprises a nonionic polymer. That is, in a preferred embodiment of the present invention, the surface treatment composition further comprises component (E): component (E): nonionic polymer.

[0120] In this context, "nonionic polymer" refers to a polymer that does not contain anionic groups such as carboxylic acid groups, sulfonic acid groups, or phosphate groups, or cationic groups such as amino groups or quaternary ammonium groups within its molecule.

[0121] Nonionic polymers have the function of improving the wettability of the surface of polished objects.

[0122] Nonionic polymers are polymers having identical (homopolymer) or different (copolymer) repeating structural units, and are typically compounds with a weight-average molecular weight (Mw) of 1,000 or more. When the nonionic polymer is a copolymer, the copolymer may take the form of a block copolymer, random copolymer, graft copolymer, or alternating copolymer.

[0123] Examples of nonionic polymers include polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, poly-N-vinylacetamide, polyvinyl ethers (such as polyvinyl methyl ether, polyvinyl ethyl ether, and polyvinyl isobutyl ether), polyglycerin, polyethylene glycol, polypropylene glycol, water-soluble polysaccharides such as hydroxyethylcellulose, alginic acid polyhydric alcohol esters, water-soluble urea resins, dextrin derivatives, and casein. In addition to those having such main chain structures, graft copolymers having nonionic polymer structures in the side chains can also be suitably used. Furthermore, copolymers such as ethylene-vinyl alcohol copolymers and butenediol-vinyl alcohol copolymers can also be used. These nonionic polymers can be used individually or in combination of two or more.

[0124] From the viewpoint of suppressing the polishing rate of the polished workpiece, suitable examples of nonionic polymers include: polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, poly-N-vinylacetamide, polyethylene glycol, hydroxyethylcellulose, butenediol-vinyl alcohol copolymer, etc. Therefore, in one embodiment, the nonionic polymer as component (E) preferably includes at least one selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, poly-N-vinylacetamide, polyethylene glycol, hydroxyethylcellulose, and butenediol-vinyl alcohol copolymer. In yet another embodiment, the nonionic polymer preferably includes at least one selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, and poly-N-vinylacetamide. In yet another embodiment, the nonionic polymer preferably includes polyvinyl alcohol or polyvinylpyrrolidone. In yet another embodiment, the nonionic polymer preferably includes polyvinyl alcohol.

[0125] Component (E) may include nonionic polymers other than those listed above. From the viewpoint of suppressing the polishing speed of the polished workpiece, it is preferable that component (E) consists only of the nonionic polymers listed above. According to one embodiment of the present invention, 85% or more, 90% or more, 95% or more, or 99% or more by mass of component (E) contained in the surface treatment composition is composed of polyvinyl alcohol (upper limit is 100% by mass).

[0126] The lower limit of the weight-average molecular weight (Mw) of the nonionic polymer is preferably 1,000 or more, more preferably 3,000 or more, even more preferably exceeding 5,000, particularly preferably 8,000 or more, and most preferably 10,000 or more. The upper limit of the weight-average molecular weight (Mw) of the nonionic polymer is preferably 1,000,000 or less, more preferably 100,000 or less, even more preferably 80,000 or less, particularly preferably 50,000 or less, and most preferably less than 50,000. As an example, the weight-average molecular weight (Mw) of the nonionic polymer is preferably 1,000 or more and 1,000,000 or less, more preferably 3,000 or more and 100,000 or less, even more preferably more than 5,000 and 80,000 or less, particularly preferably 8,000 or more and 50,000 or less, and most preferably 10,000 or more and less than 50,000.

[0127] The weight-average molecular weight (Mw) of nonionic polymers can be measured as a polyethylene glycol equivalent using gel permeation chromatography (GPC). Details of the measurement method are described in the examples below.

[0128] (E) The nonionic polymer that can be used as component may be manufactured by synthesis or may be a commercially available product. Examples of commercially available products include JMR®-10HH, JMR®-3HH (both from Nippon Vitamin Vinegar & Polyvinyl Acetate Co., Ltd.), Pitzcol® K30A, K30L (both from Daiichi Kogyo Seiyaku Co., Ltd.), CMC Daicel® 1150, 1170 (both from Daicel Mirise Co., Ltd.), and GE191-104, 107 (both from Showa Denko K.K. (now Resonac Corporation)).

[0129] (E) The nonionic polymer as component can be used alone or in combination of two or more types.

[0130] When the surface treatment composition contains component (E), the amount of component (E) in the surface treatment composition is set appropriately according to the type of component (E) used and the desired effect. The amount of component (E) is 0.0001% by mass or more, 0.001% by mass or more, 0.005% by mass or more, 0.01% by mass or more, 0.03% by mass or more, 0.05% by mass or more, or 0.07% by mass or more, with the total mass of the surface treatment composition being 100% by mass (relative to the surface treatment composition). Furthermore, the upper limit of the amount of component (E) in the surface treatment composition is 1.5% by mass or less, 1.0% by mass or less, 0.5% by mass or less, 0.3% by mass or less, 0.2% by mass or less, 0.1% by mass or less, 0.09% by mass or less, 0.07% by mass or less, 0.05% by mass or less, or 0.03% by mass or less, with the total mass of the surface treatment composition being 100% by mass (relative to the surface treatment composition).

[0131] Furthermore, the upper limit of the content of component (E) in the surface treatment composition is 0.0001% by mass or more and 1.5% by mass or less, 0.001% by mass or more and 1.0% by mass or less, 0.005% by mass or more and 0.5% by mass or less, 0.01% by mass or more and 0.3% by mass or less, 0.03% by mass or more and 0.2% by mass or less, 0.05% by mass or more and 0.1% by mass or less, or 0.07% by mass or more and 0.09% by mass or less, with the total mass of the surface treatment composition being 100% by mass (relative to the surface treatment composition).

[0132] Furthermore, if the surface treatment composition contains two or more (E) components, the content of (E) components refers to the total amount of these components.

[0133] Alternatively, or in addition to the above, the mixing ratio of component (A) and component (E) in the surface treatment composition is set appropriately according to the types of component (A) and component (E) used and the desired effect. The mixing ratio of component (A) to component (E) (component (A) / component (E) content ratio) (mass ratio) is 0.01 or more, 0.05 or more, 0.1 or more, 0.5 or more, 1 or more, 5 or more, 10 or more, 13 or more, or 16 or more. The mixing ratio of component (A) to component (E) (component (A) / component (E) content ratio) (mass ratio) is 20 or less, 18 or less, 16 or less, 14 or less, 12 or less, 10 or less, or 8 or less. The mixing ratio of component (A) to component (E) (component (A) / component (E) content ratio) (mass ratio) is 0.01 to 20, 0.05 to 18, 0.1 to 16, 0.5 to 14, 1 to 12, or 5 to 10.

[0134] Furthermore, if the surface treatment composition contains two or more components (A), the content of components (A) refers to the total amount of these components. Similarly, if the surface treatment composition contains two or more components (E), the content of components (E) refers to the total amount of these components.

[0135] <Other Additives> A surface treatment composition according to one embodiment of the present invention may contain other additives in any proportion as needed, as long as they do not hinder the effects of the present invention. However, it is desirable to avoid adding them as much as possible, as they may cause foreign matter (residue). Therefore, it is preferable to add as little of the other additives as possible. Examples of other additives include surfactants, chelating agents, antifungal agents (preservatives), reducing agents, oxidizing agents, etc. A surface treatment composition according to one embodiment of the present invention contains a water-soluble polymer and is alkaline. Such a surface treatment composition preferably contains an antifungal agent (preservative). The antifungal agent (preservative) is not particularly limited and can be appropriately selected depending on the type of water-soluble polymer. Specifically, examples include isothiazoline-based preservatives such as 2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, 1,2-benzoisothiazole-3(2H)-one (BIT), and phenoxyethanol.

[0136] In one embodiment of the present invention, the surface treatment composition is substantially composed of a piperazine compound (component (A)), an anionic polymer (component (B)), an acid (component (C)), a buffer (component (D)), a nonionic polymer (component (E)), and water. In one embodiment of the present invention, the surface treatment composition is substantially composed of a piperazine compound (component (A)), an anionic polymer (component (B)), an acid (component (C)), a buffer (component (D)), a nonionic polymer (component (E)), water, and an antifungal agent (preservative).

[0137] In one embodiment of the present invention, the surface treatment composition is substantially composed of a base (component (C')), a buffer (component (D)), a nonionic polymer (component (E)), and water. In another embodiment of the present invention, the surface treatment composition is substantially composed of a base (component (C')), a buffer (component (D)), a nonionic polymer (component (E)), water, and an antifungal agent (preservative).

[0138] In the above embodiment, "the surface treatment composition is substantially composed of X" means that the total content of X exceeds 99% by mass (upper limit: 100% by mass) when the total mass of the surface treatment composition is taken as 100% by mass (relative to the surface treatment composition). Preferably, the surface treatment composition is composed of X (the above total content = 100% by mass). For example, "substantially composed of a piperazine compound (component (A)), anionic polymer (component (B)), acid (component (C)), buffer (component (D)), nonionic polymer (component (E)), and water" means that the total content of "piperazine compound (component (A)), anionic polymer (component (B)), acid (component (C)), buffer (component (D)), nonionic polymer (component (E)), and water" exceeds 99% by mass (upper limit: 100% by mass) when the total mass of the surface treatment composition is taken as 100% by mass (relative to the surface treatment composition).

[0139] According to one embodiment of the present invention, it is preferable that the surface treatment composition is substantially free of abrasive particles. Here, "substantially free of abrasive particles" means that the abrasive particle content relative to the entire surface treatment composition is less than 0.01% by mass. That is, in one embodiment of the present invention, the abrasive particle content is less than 0.01% by mass or less than 0.001% by mass (below the detection limit) (lower limit: 0% by mass), with the total mass of the surface treatment composition being 100% by mass (relative to the surface treatment composition).

[0140] <Method for Producing Surface Treatment Composition> According to one embodiment of the present invention, the method for producing a surface treatment composition involves mixing a water-soluble polymer with water. For example, it can be obtained by stirring and mixing a piperazine compound (component (A)), an anionic polymer (component (B)), an acid (component (C)), a buffer (component (D)), a nonionic polymer (component (E)), water, and optionally a preservative and / or other additive. Alternatively, for example, it can be obtained by stirring and mixing a base (component (C')), a buffer (component (D)), a nonionic polymer (component (E)), water, and optionally an antifungal agent (preservative) and / or other additive. Details of each component are as described above. In the above embodiment, the temperature when mixing each component is not particularly limited, but 10°C to 40°C is preferred, and heating may be used to increase the dissolution rate. The mixing time is also not particularly limited.

[0141] <Surface Treatment Method> In one embodiment of the present invention, the surface treatment composition can reduce organic residue on the surface after treatment while suppressing polishing of the surface of a polished object (particularly a polished substrate having nitrogen-silicon bonds). Therefore, the present invention provides a surface treatment method comprising surface treatment of a polished object using the surface treatment composition of the present invention. The surface treatment method is particularly effective for surface treatment of materials containing nitrogen-silicon bonds (silicon materials). That is, the present invention provides a surface treatment method that reduces organic residue on the surface after treatment by surface treatment of a polished object containing a material having nitrogen-silicon bonds using the surface treatment composition of the present invention, while suppressing polishing of the surface of the polished object. In this specification, "surface treatment method" may include a method for reducing organic residue on the surface of a polished object.

[0142] The surface treatment method of the present invention makes it possible to reduce organic residue on the surface after treatment while suppressing the polishing of the surface of a polished object (particularly a polished substrate having nitrogen-silicon bonds). Specifically, the present invention provides a method for reducing organic residue on the surface after treatment while suppressing the polishing of the surface of a polished object, comprising surface treatment of a polished object containing a material (silicon material) containing nitrogen-silicon bonds using the surface treatment composition of the present invention.

[0143] The surface treatment method of the present invention is carried out by directly contacting the surface treatment composition with a polished object.

[0144] Specifically, the surface treatment process can be carried out by placing the polished object after the polishing process on the polishing platen of the polishing apparatus, bringing the polishing pad into contact with the polished object, supplying a surface treatment composition to the contact area, and sliding the polished object and the polishing pad relative to each other.

[0145] As a polishing device, a general polishing device can be used that has a holder for holding the object to be polished, a motor with adjustable rotation speed, and a polishing platen to which a polishing pad (abrasive cloth) can be attached.

[0146] The surface treatment process can be carried out using either a single-sided polishing apparatus or a double-sided polishing apparatus. Furthermore, it is preferable that the polishing apparatus is equipped with a nozzle for discharging a surface treatment composition in addition to a nozzle for discharging a polishing composition.

[0147] As the polishing pad, general nonwoven fabrics, polyurethanes, and porous fluororesins can be used without particular limitations. Preferably, the polishing pad has grooves that allow the surface treatment composition to accumulate.

[0148] There are no particular restrictions on the surface treatment process conditions. For example, the rotation speed of the polishing platen and the rotation speed of the head (carrier) can be set independently to 10 rpm (0.17 s). －１ ) or more 100rpm (1.67s －１ It is preferable that the pressure applied to the polished workpiece (polishing pressure) is 0.5 psi (3.4 kPa) or more and 10 psi (68.9 kPa) or less. The method of supplying the surface treatment composition to the polishing pad is not particularly limited, and for example, a method of continuous supply using a pump or the like (flow-through) is employed. There is no limit to the amount supplied, but it is preferable that the surface of the polishing pad is always covered with the surface treatment composition, and it is preferable that it is 10 mL / min or more and 5000 mL / min or less. The surface treatment time is also not particularly limited, but it is preferable that it is 5 seconds or more and 180 seconds or less.

[0149] <Post-cleaning treatment> Furthermore, as a surface treatment method, it is preferable to further clean the polished object after surface treatment using the surface treatment composition. For example, the protective film and water-soluble polymer can be removed by performing the water polishing described in the example.

[0150] <Method for Manufacturing Semiconductor Substrates> The surface treatment method of the present invention is preferably applied when the polished object to be polished is a polished semiconductor substrate. That is, the present invention also provides a method for manufacturing a semiconductor substrate, in which the polished object to be polished is a polished semiconductor substrate, and the polished semiconductor substrate is surface-treated by the above surface treatment method.

[0151] In this case, it is preferable that the polished object to be polished contains at least one of a material containing nitrogen-silicon bonds (silicon material) and silicon oxide. That is, the present invention also provides a method for manufacturing a semiconductor substrate, comprising a polishing step of obtaining a polished semiconductor substrate by polishing a pre-polished semiconductor substrate containing a material having nitrogen-silicon bonds or silicon oxide using a polishing composition containing abrasive particles, and a surface treatment step of surface treating the polished semiconductor substrate using a surface treatment composition.

[0152] Details of the semiconductor substrate to which this manufacturing method is applied are as described in the description of the polished object to be surface-treated with the above-mentioned surface treatment composition.

[0153] Furthermore, the method for manufacturing a semiconductor substrate is not particularly limited, as long as it includes a step of surface-treating the surface of a polished semiconductor substrate using a surface treatment composition (surface treatment step).

[0154] <Preferred Embodiments of Surface Treatment Compositions> According to the present invention, a surface treatment composition is provided comprising the following components (A) to (C): Component (A): piperazine compound, Component (B): anionic polymer, Component (C): acid, and satisfying at least one of the following i) to iii): i) The content of Component (A) in the surface treatment composition is greater than 0.052% by mass, ii) The mixed mass ratio of Component (A) and Component (B) in the surface treatment composition (Component (A) / Component (B)) is greater than 1.3 and less than or equal to 100, iii) The hydration energy of Component (C) is between -2000 kJ / mol and less than or equal to -100 kJ / mol, and / or Component (C) comprises at least one selected from the group consisting of acetic acid, nitric acid, sulfuric acid, phosphoric acid, thiocyanic acid, and hydrochloric acid. Such surface treatment composition is used for surface treatment of a polished object obtained by polishing the object using an abrasive composition, and the surface treatment may be carried out in the presence of abrasive grains. Preferably, the surface repulsion force obtained when the surface is treated with the surface treatment composition under surface treatment condition A is 0.003 N / m or more.

[0155] According to one embodiment of the present invention, i) and ii) are combined. According to one embodiment of the present invention, i) and iii) are combined. According to one embodiment of the present invention, ii) and iii) are combined. According to one embodiment of the present invention, i), ii) and iii) are combined.

[0156] According to the present invention, the following components (C'), (D), and (E): (C'): base, (D): formula: A-COO-NH ４ ＋ A surface treatment composition is provided, comprising a buffering agent represented by (A being an alkyl group or phenyl group having 1 to 10 carbon atoms) and component E: a nonionic polymer, wherein the surface treatment composition is used for surface treatment of a polished object obtained by polishing the object with an abrasive composition, the surface treatment is performed in the presence of abrasive grains, and in the environment of the surface treatment, the zeta potential (X) of the abrasive grains and the zeta potential (Y) of the polished object are both negative, and the sum of the absolute values ​​of the zeta potential (X) and the zeta potential (Y) is greater than 45 mV. Preferably, the surface repulsion force obtained when the surface is treated with the surface treatment composition under surface treatment condition A is 0.003 N / m or more.

[0157] The present invention further encompasses the following aspects and embodiments.

[0158] 1. A surface treatment composition comprising a water-soluble polymer and a solvent, wherein the surface treatment composition is used for surface treatment of a polished object obtained by polishing the object using an abrasive composition, the surface treatment is performed in the presence of abrasive grains, and the surface repulsion force obtained when the surface is treated with the surface treatment composition under surface treatment condition A is 0.003 N / m or more.

[0159] 2. The surface treatment composition according to 1, wherein the abrasive grains include those derived from the polishing composition.

[0160] 3. The surface treatment composition according to 1. or 2., wherein the polishing speed of the polished object to be polished in the surface treatment is less than 3.6 Å / min.

[0161] 4. A surface treatment composition according to any one of 1 to 3, wherein, in the environment described above, the zeta potential (X) of the abrasive grains and the zeta potential (Y) of the polished object are both negative, and the sum of the absolute values ​​of the zeta potential (X) and the zeta potential (Y) is greater than 31 mV.

[0162] 5. A surface treatment composition according to any one of 1 to 4, wherein a protective film that inhibits contact of the abrasive grains is formed on the polished object during the surface treatment.

[0163] 6. A surface treatment composition according to any one of 1 to 5, comprising the following components (A) to (C): (A) component: piperazine compound, (B) component: anionic polymer, (C) component: acid.

[0164] 7. The above-mentioned component (A) is represented by the following formula (a), the surface treatment composition described in 6.:

[0165]

[0166] In the above formula (a), R １ R is an alkyl group having 1 to 10 carbon atoms, which may be substituted with a hydrogen atom or a primary to tertiary amino group; ２ This is an alkyl group having 1 to 10 carbon atoms, which may be substituted with any of the primary to tertiary amino groups.

[0167] 8. The surface treatment composition according to 6. or 7., wherein component (A) has two or more amino groups whose pKa is greater than the pH of the surface treatment composition.

[0168] 9. The surface treatment composition according to any one of 6. to 8., wherein the content of component (A) is greater than 0.052% by mass with respect to the total mass of the surface treatment composition.

[0169] 10. The surface treatment composition according to any one of 6 to 9, wherein component (B) comprises at least one selected from the group consisting of poly(meth)acrylic acid, polystyrene sulfonic acid, and poly(carboxylic acid-sulfonic acid), and salts thereof.

[0170] 11. The surface treatment composition according to any one of 6 to 10, wherein component (C) comprises at least one selected from the group consisting of acetic acid, nitric acid, sulfuric acid, phosphoric acid, thiocyanic acid, and hydrochloric acid.

[0171] 12. A surface treatment composition according to any of 6. to 11., further comprising the following component (D): Component (D): Formula: A-COO-NH ４ ＋ A buffering agent represented by (A is an alkyl group or phenyl group having 1 to 10 carbon atoms).

[0172] 13. The surface treatment composition according to 12, wherein component (D) comprises ammonium acetate.

[0173] 14. A surface treatment composition according to any one of 6. to 13., further comprising the following component (E): (E) component: nonionic polymer.

[0174] 15. The surface treatment composition according to 14, wherein component (E) comprises at least one selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, poly-N-vinylacetamide, polyethylene glycol, hydroxyethylcellulose, and butenediol-vinyl alcohol copolymer.

[0175] The present invention will be described in more detail using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Unless otherwise specified, "%" and "parts" mean "mass percent" and "parts by mass," respectively. In addition, in the following examples, unless otherwise specified, the operations were carried out under conditions of room temperature (25°C) / relative humidity of 40% RH or higher and 50% RH or lower.

[0176] <Preparation of components (A) to (E)> The following components (A) to (E) were prepared.

[0177] <Component (A): Piperazine compound> ・Aminoethylpiperazine (in formula (a), R １ = H, R ２ = aminoethyl group (-CH ２ CH ２ NH ２)) (molecular weight = 129; pKa = 10.11, 8.78, 1.74).

[0178] <Component (B): Anionic polymer> Polyacrylic acid (weight-average molecular weight (Mw) = 25,000).

[0179] <(C) Components: Acids> • Phosphoric acid (molecular weight: 98) • Acetic acid (molecular weight: 60) • Nitric acid (molecular weight: 63) • Sulfuric acid (62.5% by mass; molecular weight: 98).

[0180] <(C') component: base> - Ammonia (molecular weight: 17).

[0181] <(D) Component: pH buffering agent> Ammonium acetate (molecular weight: 77).

[0182] <Component (E): Nonionic polymer> Polyvinyl alcohol (PVA) (weight-average molecular weight (Mw) = 10,000).

[0183] The weight-average molecular weights (Mw) of components (B) and (E) described above were measured by the following method.

[0184] [Measurement of Weight-Average Molecular Weight (Mw)] The weight-average molecular weight (Mw) of the water-soluble polymers (components (B) and (E)) was measured using the weight-average molecular weight (polyethylene glycol equivalent) value obtained by gel permeation chromatography (GPC). The weight-average molecular weight was measured using the following apparatus and conditions: GPC apparatus: Shimadzu Corporation Model: Prominence + ELSD detector (ELSD-LTII) Column: VP-ODS (Shimadzu Corporation) Mobile phase A: MeOH B: 1% aqueous acetic acid solution Flow rate: 1 mL / min Detector: ELSD Temp. 40°C, Gain 8, N ２ Gas pressure: 350 kPa. Oven temperature: 40°C. Injection volume: 40 μL.

[0185] <Preparation of Surface Treatment Composition> (Example 1) The surface treatment composition of Example 1 was prepared by stirring and mixing component (C'): ammonia, component (D): ammonium acetate, component (E): polyvinyl alcohol, and distilled water as a solvent at 25°C for 5 minutes to obtain the composition shown in Table 1.

[0186] (Example 2) The surface treatment composition for Example 2 was prepared by stirring and mixing (A) a piperazine compound, (B) polyacrylic acid, (C) acetic acid, (D) ammonium acetate, (E) polyvinyl alcohol, and distilled water as a solvent at 25°C for 5 minutes to obtain the composition shown in Table 1.

[0187] (Examples 3-7, Comparative Example 1) Surface treatment compositions for Examples 3-7 and Comparative Example 1 were prepared in the same manner as in Example 2, except that the composition of the surface treatment composition in Example 2 was changed to the composition shown in Table 1.

[0188] Note that "-" indicates that the component in question has not been added. Furthermore, the surface treatment composition prepared above does not contain abrasive particles (abrasive particle content = 0% by mass).

[0189] [Measurement of pH of surface treatment compositions] The pH of the surface treatment compositions (liquid temperature: 25°C) was confirmed using a pH meter (product name: LAQUA®, manufactured by Horiba, Ltd.), and all surface treatment compositions were found to be 8.0.

[0190] <Preparation of polished workpieces> Polished workpieces (polished silicon nitride substrates) were prepared by the following chemical mechanical polishing (CMP) process.

[0191] [CMP Process] A silicon wafer (silicon nitride substrate) (300 mm, blanket wafer, manufactured by Advantech Co., Ltd.) with a silicon nitride film thickness of 2500 Å formed on its surface by CVD was prepared as the object to be polished.

[0192] Silica slurry (Composition: Colloidal silica (average primary particle size: 35 nm, average secondary particle size: 70 nm) 10% by mass, polyvinylpyrrolidone (Mw = 45,000) 0.25% by mass, EL ammonia water (Concentration: 28.0% to 30.0% by mass (NH) ３ A silica slurry (0.33% by mass, solvent: distilled water) was prepared. The above silica slurry was diluted fivefold with distilled water to prepare a polishing composition. The pH of the obtained polishing composition was 10.0.

[0193] The average primary particle diameter is calculated using the BET method with Micromeritex's "Flow Sorb II 2300" to determine the specific surface area (SA) of silica and the true density of silica, and is given by: Primary particle diameter (nm) = 6000 / (True density (g / cm³) × SA (nm) ２ The average secondary particle diameter was calculated using the formula ( / g). The average secondary particle diameter was measured using a dynamic light scattering particle size / particle size distribution analyzer UPA-UT151 manufactured by Nikkiso Co., Ltd.

[0194] The silicon nitride substrate prepared as described above was polished using the polishing composition described above under the following conditions to obtain a polished object (polished silicon nitride substrate).

[0195] (Polishing equipment and polishing conditions) Polishing equipment: Lapping machine EJ-380IN-CH-D manufactured by Nippon Engis Co., Ltd. Polishing pad: Foamed polyurethane pad IC1010 manufactured by Nitta DuPont Co., Ltd. Conditioner (dresser): Diamond dresser (manufactured by Noritake Co., Limited) (in-situ conditioning) Polishing pressure: 2.4 psi (1 psi = 6894.76 Pa, same applies below) Polishing plate rotation speed: 60 rpm Head rotation speed: 60 rpm Supply of polishing composition: flow Polishing composition supply amount: 50 mL / min Polishing time: 60 seconds.

[0196] <Adsorption amount of components in surface treatment composition by QCM method> By measuring the amount of adsorption onto a polished silicon nitride substrate, which is used as a representation of a polished silicon nitride substrate, using the method described below, the amount of adsorption equivalent to the amount of adsorption onto the polished silicon nitride substrate was measured, and the results are shown in Table 1.

[0197] (Adsorption amount measurement by QCM method) The amount of adsorption of components contained in the surface treatment composition onto the silicon nitride sensor surface was measured using the Quartz crystal microbalance method (QCM method). A QCM-D measuring device Q-Sense-Pro (manufactured by Altec Corporation) was used for the measurement.

[0198] The measurement procedure was as follows: First, 800 μL of pure water was placed in the measuring device and stabilized at 25°C. Then, each surface treatment composition was flowed at a flow rate of 40 μL / min for 10 minutes to measure the amount of adsorption (ng / cm³) of the components contained in the surface treatment composition onto the silicon nitride sensor electrode surface (per unit area). ２ ) was measured.

[0199] <Zeta Potential> The zeta potential of the polished silicon nitride substrate and the zeta potential of the abrasive grains during surface treatment using each surface treatment composition were measured using the following model experiment.

[0200] (Zeta potential of polished silicon nitride substrate) To measure the zeta potential of polished silicon nitride substrate, a 60 mm square piece of polished silicon nitride substrate was used as the measurement object. The measurement object was placed in a solid zeta potential measuring instrument SurPASS3 (zeta potential meter) manufactured by Anton Paar Japan Co., Ltd. Next, each of the surface treatment compositions prepared above was passed through the measurement object, and the zeta potential (mV) of the polished silicon nitride substrate was measured. For reference, the zeta potential of the polished object under pH conditions was measured by passing ammonia water (pH = 8), which reproduces the pH environment in which the surface treatment process is performed, through the measurement object, and it was -62 mV.

[0201] (Zeta potential of abrasive grains) The zeta potential of abrasive grains was measured by mixing the same abrasive grains used in the CMP process into each surface treatment composition, based on the recommended abrasive grain concentration of the measuring device, to a concentration of 0.1% by mass. The surface treatment composition containing these abrasive grains was subjected to a Zetasizer Nano manufactured by Malvern Panalytical, and measured by laser Doppler (electrophoretic light scattering measurement) under conditions of a measurement temperature of 25°C. The obtained data was then analyzed using Smoluchowski's formula to calculate the zeta potential.

[0202] <Measurement of Rebound Force> The rebound force of the surface obtained when the surface treatment composition was treated under surface treatment condition A was measured as follows.

[0203] [Surface Treatment Conditions A] Surface treatment target: Silicon nitride substrate prepared above Surface treatment equipment: Lapping machine EJ-380IN-CH-D manufactured by Nippon Engis Co., Ltd. Pad: Foamed polyurethane pad H600CB (3-1S)-Z5 manufactured by Fujibo Ehime Co., Ltd. Conditioner (dresser): Nylon brush (manufactured by Nippon Engis Co., Ltd.) (in-situ conditioning) Pressure: 1.4 psi Plate rotation speed: 60 rpm Head rotation speed: 60 rpm Supply of surface treatment composition: Flow-through Supply amount of surface treatment composition: 100 mL / min Polishing time: 60 seconds.

[0204] The repulsive force can be measured by detecting the vertical component (cantilever deflection signal) of the force received from the surface when the probe approaches the surface, with the repulsive force direction considered positive, and the maximum value before reaching the SiN on the surface obtained by surface treatment. More specifically, the repulsive force is measured by the probe (spherical SiO ２ The cantilever deflection displacement was evaluated based on the force curve measured using AFM (Dimension IconIR) (Manufacturer: Bruker; Model: Dimension IconIR (Model: SPN-211116-01); Software: NanoScope 10.0) with a probe-equipped AFM probe (CP-FM-SiO, manufactured by sQube). Four measurements were performed, and the arithmetic mean was adopted as the repulsive force. The measurement environment (Atmosphere) was "In Liquid," and specifically, a solution was used that had the water-soluble polymer components (components (E) and (B)) removed from the compositions described in the various examples and comparative examples. The pH was the same as the compositions described in the examples and comparative examples.

[0205]

[0206] <Measurement of Adhesion Force> When a polishing object is surface-treated using a surface treatment composition under surface treatment condition A, the vertical component (cantilever deflection signal) that occurs when the probe attempts to separate from the surface is detected, and the maximum value of this component, with the attractive force direction as positive, can be measured as the adhesion force. In this evaluation, the adhesion force is measured using a probe (spherical SiO ２ The adhesion force was evaluated based on the deflection displacement of the cantilever measured from the force curve obtained using AFM (Dimension IconIR) (Manufacturer: Bruker; Model: Dimension IconIR (Model: SPN-211116-01); Software: NanoScope 10.0) with a probe-equipped AFM probe (CP-FM-SiO, manufactured by sQube). Four measurements were taken, and the arithmetic mean was adopted as the adhesion force. The measurement environment (Atmosphere) was "In Liquid," and specifically, a solution was used from the compositions described in the various examples and comparative examples, with the water-soluble polymer components (components (E) and (B)) removed. The pH was the same as the compositions described in the examples and comparative examples.

[0207]

[0208] <Surface Treatment Process> Polished silicon nitride substrates were subjected to surface treatment using each surface treatment composition under the following conditions to obtain each surface-treated silicon nitride substrate.

[0209] [Surface Treatment Conditions] Surface treatment target: Polished silicon nitride substrate Surface treatment equipment: Lapping machine EJ-380IN-CH-D manufactured by Nippon Engis Co., Ltd. Pad: Foamed polyurethane pad H600CB (3-1S)-Z5 manufactured by Fujibo Ehime Co., Ltd. Conditioner (dresser): Nylon brush (manufactured by Nippon Engis Co., Ltd.) (in-situ conditioning) Pressure: 1.4 psi Plate rotation speed: 60 rpm Head rotation speed: 60 rpm Supply of surface treatment composition: Flow-through Supply amount of surface treatment composition: 100 mL / min Polishing time: 60 seconds.

[0210] [Polishing speed and organic residue measurement of surface-treated SiN substrates] The following processes were performed using each surface-treated silicon nitride substrate obtained by the above <surface treatment process>.

[0211] (Water polishing) A surface-treated silicon nitride substrate was water-polished using deionized water under the following conditions to obtain a water-polished silicon nitride substrate.

[0212] <Water polishing conditions> Water polishing equipment: Lapping machine EJ-380IN-CH-D manufactured by Nippon Engis Co., Ltd. Pad: Foamed polyurethane pad H600CB (3-1S)-Z5 manufactured by Fujibo Ehime Co., Ltd. Conditioner (dresser): Nylon brush (manufactured by Nippon Engis Co., Ltd.) (in-situ conditioning) Pressure: 1.4 psi Plate rotation speed: 60 rpm Head rotation speed: 60 rpm Supply of deionized water: Flowing Deionized water supply rate: 5500 mL / min Polishing time: 180 seconds.

[0213] The reason for performing water polishing is that removing the protective film (including PVA in Comparative Example 1) allows for the measurement of the film thickness of the surface-treated SiN substrate.

[0214] (Measurement of polishing speed) The polishing speed of the polished silicon nitride substrate during surface treatment was determined by measuring the film thickness before and after polishing using an optical interference film thickness measuring device (manufactured by SCREEN Holdings Co., Ltd., model number: Lambda Ace VM-2030), and then dividing the difference in film thickness before and after polishing by the polishing time. The polishing speed is the arithmetic mean of three measurements. Since the waste liquid after surface treatment contained 0.02 mass% of abrasive particles, it can be considered that the surface treatment of the polished object was performed in the presence of 0.02 mass% of abrasive particles.

[0215] (Organic Residue Evaluation) The number of residues on the surface after surface treatment was evaluated using the Surfscan® SP5 optical inspection machine manufactured by KLA-Tencor Co., Ltd. Specifically, the number of residues with a diameter of 70 nm or more was counted in the remaining portion after excluding a 5 mm wide portion from the outer edge of one side of the water-polished silicon nitride substrate (the region from 0 mm to 5 mm when the outer edge is set to 0 mm). Then, the number of organic residues was measured by SEM observation using a Review SEM RS6000 manufactured by Hitachi High-Tech Corporation. First, 100 residues were sampled from the remaining portion after excluding the 5 mm wide portion from the outer edge of one side of the water-polished silicon nitride substrate using SEM observation. Next, the type of residue was identified from the 100 sampled residues by visual SEM observation, and the number of organic residues (pad debris, polymers, etc.) was measured. For reference, we examined polished silicon nitride substrates that had not undergone surface treatment and found over 10,000 organic residue particles. In our industry, a number of organic residue particles less than 500 is considered acceptable for practical use.

[0216]

Claims

1. A surface treatment composition comprising a water-soluble polymer and a solvent, wherein the surface treatment composition is used for surface treatment of a polished object obtained by polishing the object using an abrasive composition, the surface treatment is performed in the presence of abrasive grains, and the surface repulsion force obtained when the surface treatment is performed using the surface treatment composition under surface treatment condition A is 0.003 N / m or more.

2. The surface treatment composition according to claim 1, wherein the abrasive grains include those derived from the polishing composition.

3. The surface treatment composition according to claim 1, wherein the polishing speed of the polished object to be polished in the surface treatment is less than 3.6 Å / min.

4. The surface treatment composition according to claim 1, wherein in the environment described above, the zeta potential (X) of the abrasive grains and the zeta potential (Y) of the polished object are both negative, and the sum of the absolute values ​​of the zeta potential (X) and the zeta potential (Y) is greater than 31 mV.

5. The surface treatment composition according to claim 1, wherein a protective film is formed on the polished object to be polished during the surface treatment, which inhibits contact of the abrasive particles.

6. A surface treatment composition according to claim 1 or 5, comprising the following components (A) to (C): (A) a piperazine compound, (B) an anionic polymer, (C) an acid.

7. The surface treatment composition according to claim 6, wherein component (A) is represented by the following formula (a): In the above formula (a), R １ R is an alkyl group having 1 to 10 carbon atoms, which may be substituted with a hydrogen atom or a primary to tertiary amino group; ２ This is an alkyl group having 1 to 10 carbon atoms, which may be substituted with any of the primary to tertiary amino groups.

8. The surface treatment composition according to claim 6, wherein component (A) has two or more amino groups whose pKa is greater than the pH of the surface treatment composition.

9. The surface treatment composition according to claim 6, wherein the content of component (A) is greater than 0.052% by mass with respect to the total mass of the surface treatment composition.

10. The surface treatment composition according to claim 6, wherein component (B) comprises at least one selected from the group consisting of poly(meth)acrylic acid, polystyrene sulfonic acid, and poly(carboxylic acid-sulfonic acid), and salts thereof.

11. The surface treatment composition according to claim 6, wherein component (C) comprises at least one selected from the group consisting of acetic acid, nitric acid, sulfuric acid, phosphoric acid, thiocyanic acid, and hydrochloric acid.

12. The surface treatment composition according to claim 6, further comprising the following component (D): Component (D): Formula: A-COO-NH ４ ＋ A buffering agent represented by (A is an alkyl group or phenyl group having 1 to 10 carbon atoms).

13. The surface treatment composition according to claim 12, wherein component (D) comprises ammonium acetate.

14. The surface treatment composition according to claim 6, further comprising the following component (E): Component (E): Nonionic polymer.

15. The surface treatment composition according to claim 14, wherein component (E) comprises at least one selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, poly-N-vinylacetamide, polyethylene glycol, hydroxyethylcellulose, and butenediol-vinyl alcohol copolymer.

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