Surface treatment composition

Abstract

[Problem] To provide a means for reducing scratches generated in a surface treatment step. [Solution] This surface treatment composition comprises a water-soluble polymer and a solvent, wherein: said surface treatment composition is used for a surface treatment of a polished object to be polished obtained by polishing an object to be polished using a polishing composition; the surface treatment is performed in the presence of abrasive grains; and a protective film, containing the water-soluble polymer and formed when the surface treatment is performed under a surface treatment condition A using said surface treatment composition, has a film thickness of at least 0.5 nm.

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, for example, to the gate formation process in transistor fabrication. When fabricating transistors, materials such as metals, silicon oxide, polycrystalline silicon, and silicon nitride (SiN) 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] Polishing processes are generally performed to eliminate unevenness and flatten the surface of the object being polished. However, we have found that even after the polishing process, the flattening of the polished object may not be completely achieved.

[0009] Here, the inventors have also found 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. However, as disclosed in Patent Document 1, the surface treatment process is generally intended to remove residue adhering to the polished object after the polishing process, or to prevent residue from re-adhering by protecting the surface of the polished object, and is not a process for polishing the polished object itself. In other words, the polishing process and the surface treatment process have different roles, and it is recognized in this industry that these should be clearly distinguished.

[0010] As described above, the surface treatment using the surface treatment composition disclosed in the example of Patent Document 1 is performed with the aim of removing abrasive residue and the like from the polishing composition that adheres to the polished SiN substrate after the CMP process. However, the inventors have found that when this surface treatment is performed, a phenomenon occurs in which scratches occur on the surface of the polished SiN substrate. These scratches lead to a deterioration in the surface quality of the polished SiN substrate.

[0011] Therefore, the present invention aims to provide a means for reducing scratches that occur in a surface treatment process.

[0012] 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 particles, and the thickness of the protective film containing the water-soluble polymer formed when the surface treatment is performed using the surface treatment composition under surface treatment condition A is 0.5 nm or more.

[0013] According to the present invention, a means for reducing scratches generated in a surface treatment process can be provided.

[0014] 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.

[0015] <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 thickness of the protective film containing the water-soluble polymer formed when the surface treatment is performed using the surface treatment composition under surface treatment condition A is 0.5 nm or more. Such a surface treatment composition can reduce scratches (on the surface of the polished object) that occur in the surface treatment process.

[0016] As described above, the 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 introduced from the preceding polishing process. By utilizing these abrasive particles derived from the polishing composition, the surface treatment composition during the surface treatment process is given a certain degree of ability to polish the polished object to be polished, thereby reducing scratches on the final surface-treated object to be polished. Therefore, according to one embodiment of the present invention, the abrasive particles include those derived from the polishing composition.

[0017] <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.

[0018] [Polishing Composition] As the polishing composition, known polishing compositions can be used as appropriate. Examples of polishing compositions include polishing compositions containing silica abrasive grains 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 grains 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 grains in the polishing composition may be, for example, 0.1 to 20% by mass.

[0019] 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.

[0020] [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 oxycarbonite 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 ).

[0021] <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, and the surface treatment is performed in the presence of abrasive grains.

[0022] When surface treatment is performed using the surface treatment composition of the present invention, a protective film may be formed. The surface treatment composition of the present invention is designed such that the thickness of the protective film containing a water-soluble polymer formed when surface treatment is performed using the surface treatment composition under surface treatment condition A is 0.5 nm or more. By performing a surface treatment process using such a surface treatment composition, scratches on the surface of a polished object can be reduced. Surface treatment condition A is the condition used when measuring the thickness of film, etc., using an atomic force microscope (AFM), 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.

[0023] [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.

[0024] 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.

[0025] 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.

[0026] Cationic polymers are polymers that have cationic groups such as amino groups and quaternary ammonium groups. Examples include polyacrylamide.

[0027] Anionic polymers are explained in section (B) below. Nonionic polymers are explained in section (E) below.

[0028] 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, 0.005% 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.

[0029] [Solvent] The surface treatment composition of the present invention preferably 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 consists 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.

[0030] 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.

[0031] [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.

[0032] <Coefficient of Friction of Protective Film> The coefficient of friction of the protective film is, simply put, an indicator of how easily abrasive grains that come into contact with the protective film during the surface treatment process move (slip) on the protective film in the direction of the protective film surface (horizontal direction). When this value is large, specifically preferably 1.9 or higher, the lateral slippage of abrasive grains on the protective film is significantly suppressed, and therefore, scratches on the object obtained after surface treatment of the polished object (surface-treated polished object) can be reduced. The coefficient of friction of the protective film can be measured based on the torsion signal measured from LFM (Lateral Force Microscope) using AFM. Specifically, spherical SiO2, which represents silica abrasive grains, is attached to the tip of the probe. ２ By attaching a probe (tip) and detecting the horizontal component of the force it receives from the surface of the protective film as the twist of the cantilever, it is possible to determine (spherical SiO ２ It can be measured as the coefficient of friction (generated between the probe and the surface of the protective film). A more specific method for measuring the coefficient of friction of the protective film is described in the examples.

[0033] According to one embodiment of the present invention, the coefficient of friction of the protective film may be 2.0 or higher, 2.1 or higher, 2.2 or higher, or 2.3 or higher. According to one embodiment of the present invention, the coefficient of friction of the protective film is 2.9 or lower, 2.8 or lower, 2.7 or lower, 2.6 or lower, or 2.5 or lower. According to one embodiment of the present invention, the coefficient of friction of the protective film may be 1.9 or higher and 2.9 or lower, 2.0 or higher and 2.8 or lower, 2.1 or higher and 2.7 or lower, 2.2 or higher and 2.6 or lower, or 2.3 or higher and 2.5 or lower.

[0034] <Method for controlling the thickness of the protective film> [Basic technical concept] In this invention, in order to reduce scratches on the surface of a polished object after surface treatment, the thickness of the protective film formed by surface treatment using a surface treatment composition under surface treatment condition A is controlled to be 0.5 nm or more. This suppresses lateral slippage of abrasive grains during the surface treatment process and allows surface treatment without roughening the surface. As a result, scratches on the resulting surface-treated polished object can be reduced. In order to control the thickness of the protective film to 0.5 nm or more, it is important to sufficiently adsorb the components that form the protective film (especially the water-soluble polymer, which is its main component) onto the polished object.

[0035] 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, having 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 ratio of the amount of the adsorption aid to the amount of the water-soluble polymer is 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.

[0036] [Measurement of Adsorption Amount by QCM Method] Measuring 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.

[0037] According to one embodiment of the present invention, the adsorption amount is 167 ng / cm ２ more than, 170 ng / cm ２ or more, 200 ng / cm ２ or more, 300 ng / cm ２ or more, 400 ng / cm ２ or more, or 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 results may be as follows. Note that PVA, a water-soluble polymer contained in the surface treatment composition of Comparative Example 1 in the Examples section described later, is a nonionic polymer, and therefore does not electrostatically attract to the negatively charged polished object (polished silicon nitride substrate) and hardly adsorbs. Therefore, in Comparative Example 1, a protective film sufficient to achieve a film thickness of 0.5 nm or more cannot be formed. Also, polyacrylic acid, a water-soluble polymer contained in the surface treatment composition of Comparative Example 2, is anionic, and therefore electrostatically repels the negatively charged polished object (polished silicon nitride substrate), 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. Therefore, in Comparative Example 2, as in Comparative Example 1, a protective film sufficient to achieve a film thickness of 0.5 nm or more cannot be formed. In contrast, the amount of adsorption aid contained in the surface treatment composition in the examples is sufficiently large to make the protective film thickness 0.5 nm or more, or the ratio of the amount of adsorption aid to the amount of anionic polymer is sufficiently large to make the protective film thickness 0.5 nm or more. Therefore, the thickness of the resulting protective film is 0.5 nm or more.

[0038] The thickness of the protective film can be measured based on force curve measurement using AFM. The specific measurement method is as described in the examples.

[0039] The thickness of the protective film is preferably 0.7 nm or more, and is also 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.

[0040] <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 to be polished using a polishing composition.

[0041] Therefore, according to one embodiment of the present invention, a surface treatment composition is provided comprising the following components (A) to (C): (A) component: piperazine compound, (B) component: anionic polymer, and (C) component: acid. The pH of the surface treatment composition is preferably greater than 7.0.

[0042] <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.

[0043] The piperazine compound as component (A) is preferably represented by the following chemical formula.

[0044]

[0045] 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.

[0046] 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 ２The 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.

[0047] 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 ２ The 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.

[0048] 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 ２This 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.

[0049] Here, the alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. Specific examples of such alkyl groups are shown in the above R. １ and R ２Examples 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.

[0050] 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.

[0051] 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) 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). ２ Ethyl 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 ２It is particularly preferable that the n-propyl group is substituted with ).

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057]

[0058] 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.

[0059] 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.

[0060] (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.

[0061] (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) 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.

[0062] (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; ２It 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.

[0063] (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; ２ It 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).

[0064] (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.

[0065] 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).

[0066] 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.

[0067] <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.

[0068] Component (B) interacts with component (A) and adsorbs to component (A), thereby forming a protective film on the polished object.

[0069] 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.

[0070] 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-tert-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.

[0071] When anionic polymers exist in salt form, examples include salts of alkali metals such as lithium salts, sodium salts, potassium salts, rubidium salts, and cesium salts, as well as salts of Group 2 elements (alkaline earth metals) such as magnesium salts, calcium salts, strontium salts, and barium salts, including polycarboxylic acids, polysulfonic acids, and poly(carboxylic acid-sulfonic acids).

[0072] These anionic polymers can be used individually or in combination of two or more.

[0073] 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.

[0074] Component (B) may include anionic polymers other than those listed above. Preferably, component (B) consists only of the anionic polymers listed above.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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).

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] (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.).

[0087] (B) The anionic polymer as component can be used alone or in combination of two or more types.

[0088] 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.

[0089] 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.

[0090] As described above, polyacrylic acid, a water-soluble polymer contained in the surface treatment composition of Comparative Example 2, is anionic, and therefore repels the negatively charged polished object (polished silicon nitride substrate), making adsorption difficult. In Comparative Example 2, 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 2, the thickness of the protective film is not 0.5 nm or more. In contrast, the amount of adsorption aid contained in the surface treatment composition in the example is sufficiently large to make the thickness of the protective film 0.5 nm 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 thickness of the protective film 0.5 nm or more. Therefore, the thickness of the resulting protective film is 0.5 nm 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.

[0091] <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.

[0092] An acid can be a Lewis acid, and a Lewis acid can be a Brønsted acid. The 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.

[0093] 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.

[0094] (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.

[0095] ΔG = ΔH - TΔS The Gibbs free energy is calculated by determining the hydrated molar Gibbs free energy ΔhydG (kJ) per mole of acid added to the surface treatment composition, referring to the following references: ・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).

[0096]

[0097] (C) The hydration energy of the acid as component (C) is preferably -2000 kJ / mol or higher, -1800 kJ / mol or higher, -1600 kJ / mol or higher, -1400 kJ / mol or higher, -1200 kJ / mol or higher, -1000 kJ / mol or higher, -800 kJ / mol or higher, -600 kJ / mol or higher, -400 kJ / mol or higher, or -350 kJ / mol or higher. Note that the hydrated molar Gibbs energy is an acid-specific value, and the hydration energy of the acid in the surface treatment composition can be calculated by multiplying this by the number of moles added.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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 is obtained from the intercept of the linear approximation. In this specification, the intrinsic viscosity is specifically the value measured by the method described in the examples.

[0103] In the present invention, the intrinsic viscosity of component (B) is 3.0 dL / g or less, 2.5 dL / g or less, 2.0 dL / g or less, 1.8 dL / g or less, or 1.5 dL / g or less.

[0104] Because the shrunk polymer (especially component (B)) has a dense structure, the protective film formed on the polished workpiece is high-density and high-viscosity. Furthermore, high density and high viscosity of the protective film result in a thicker film thickness. A thick protective film suppresses the movement (i.e., lateral slippage) of abrasive grains in the surface direction on the protective film. Therefore, even if the surface treatment process is performed in the presence of abrasive grains, the abrasive grains are less likely to slip laterally on a thick protective film, and scratches on the resulting surface-treated polished workpiece are reduced.

[0105] (C) As a component, a high 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 high 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.

[0106] 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.

[0107] Here, among the components that can be contained in the surface treatment composition, in particular, the component (A) and the component (C) have a high ability to vary the pH of the composition. On the other hand, the component (B), the component (D) described later, and the component (E) also have a certain ability to vary the pH of the composition, but in addition to these, components used in the art as components for varying the pH of the surface treatment composition (so-called pH adjusters) may be included. When a pH adjuster is contained in the surface treatment composition, it is preferable that the pH of the surface treatment composition is adjusted as described in the item of [pH]. Examples of such pH adjusters include hydroxides of alkali metals such as potassium hydroxide (KOH) and sodium hydroxide (NaOH); carbonates of alkali metals such as potassium carbonate (K ２ CO ３ ), sodium carbonate (Na ２ CO ３ ); hydroxides of Group 2 elements (alkaline earth metals); ammonia (ammonium hydroxide); organic bases such as quaternary ammonium hydroxide compounds, etc.

[0108] <Number of scratches on the polished object> According to one embodiment of the present invention, the number of scratches on the surface of the polished object after applying the surface treatment composition of the present invention to the polished object can be less than 200, 150 or less, 100 or less, 90 or less, 80 or less, 60 or less, 50 or less, 40 or less, or 30 or less. The protective film formed by the surface treatment composition in the present invention is as thick as 0.5 nm or more, and the number of scratches on the surface of the polished object (surface-treated polished object) obtained after applying the surface treatment composition of the present invention to the polished object can be significantly reduced. The lower limit value of the number of scratches is 0. Specifically, the number of scratches can be measured by the method described in the examples.

[0109] <Component (D)> According to one embodiment of the present invention, the surface treatment composition preferably contains the following buffer. Component (D): A buffer represented by the formula: A - COO - NH ４ ＋ (A is an alkyl group or a phenyl group having 1 to 10 carbon atoms). The 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) in order to keep the pH constant.

[0110] 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, etc., component (D) is the above formula: A - COO - NH ４ ＋ It is preferably composed of the buffer represented by (component (D) is the above formula: A - COO - NH ４ ＋ It is the buffer represented by). Due to the presence of component (D), scratches on the polished object to be polished can be further reduced. 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 above formula: A - COO - NH ４ ＋ It is the buffer represented by).

[0111] 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 ＋ This is shown as follows. 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).

[0112] 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.

[0113] 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.

[0114] <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.

[0115] 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.

[0116] Nonionic polymers have the function of improving the wettability of the surface of polished objects.

[0117] 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.

[0118] 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.

[0119] From the viewpoint of further reducing scratches on polished objects, preferred 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.

[0120] Component (E) may include nonionic polymers other than those listed above. From the viewpoint of further reducing scratches on the polished object, 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).

[0121] 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.

[0122] 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.

[0123] (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 Resonac Co., Ltd.).

[0124] (E) The nonionic polymer as component can be used alone or in combination of two or more types.

[0125] 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).

[0126] 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).

[0127] 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.

[0128] 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.

[0129] 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.

[0130] <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 an anionic 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 anionic polymer (component (B)). 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.

[0131] 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.

[0132] 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).

[0133] 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).

[0134] 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).

[0135] <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. 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.

[0136] <Surface Treatment Method> In one embodiment of the present invention, the surface treatment composition can reduce scratches on 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 scratches on the surface of a polished object containing a material having nitrogen-silicon bonds by surface treatment of the polished object using the surface treatment composition of the present invention. In this specification, "surface treatment method" may include a method for reducing scratches on the surface of a polished object.

[0137] The surface treatment method of the present invention can reduce scratches on the surface of a polished object (particularly a polished substrate having nitrogen-silicon bonds). Specifically, the present invention provides a method for reducing scratches on the surface of a polished object, which involves surface-treating a polished object containing a material (silicon material) containing nitrogen-silicon bonds using the surface treatment composition of the present invention.

[0138] The surface treatment method of the present invention is carried out by directly contacting the surface treatment composition with a polished object.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] <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.

[0145] <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.

[0146] 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.

[0147] 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.

[0148] 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).

[0149] <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 can be carried out in the presence of abrasive grains. When the surface is treated using the surface treatment composition under surface treatment condition A, the thickness of the protective film containing the water-soluble polymer formed is preferably 0.5 nm or more.

[0150] 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.

[0151] The present invention further encompasses the following aspects and embodiments.

[0152] 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 thickness of the protective film containing the water-soluble polymer formed when the surface treatment is performed using the surface treatment composition under surface treatment condition A is 0.5 nm or more; 2. The surface treatment composition according to 1, wherein the abrasive grains include those derived from the abrasive composition; 3. The surface treatment composition according to 1 or 2, comprising the following components (A) to (C): (A) component: piperazine compound, (B) component: anionic polymer, (C) component: acid; 4. The surface treatment composition according to 3, wherein component (A) is represented by the following formula (a);

[0153]

[0154] 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; ２1 is an alkyl group having 1 to 10 carbon atoms, which may be substituted with any of primary to tertiary amino groups; 5. The surface treatment composition according to 3. or 4., wherein component (A) has two or more amino groups whose pKa is greater than the pH of the surface treatment composition; 6. The surface treatment composition according to any one of 3. to 5., wherein the content of component (A) is greater than 0.052% by mass of the total mass of the surface treatment composition; 7. The surface treatment composition according to any one of 3. to 6., wherein the intrinsic viscosity of component (B) is 3.0 dL / g or less; 8. The surface treatment composition according to any one of 3. to 7., 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; 9. The hydration energy of component (C) is -2000 kJ / mol or more and -100 kJ / mol or less, according to 3. to 8. A surface treatment composition according to any one of the following: 10. A surface treatment composition according to any one of 3 to 9, wherein the (C) component comprises at least one selected from the group consisting of acetic acid, nitric acid, sulfuric acid, phosphoric acid, thiocyanic acid, and hydrochloric acid; 11. A surface treatment composition according to any one of 3 to 10, wherein the coefficient of friction of the protective film is 1.9 or higher; 12. A surface treatment composition according to any one of 3 to 11, further comprising the following (D) component: (D) component: 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 12, wherein component (D) comprises ammonium acetate; 14. The surface treatment composition according to any one of 3 to 13, further comprising component (E) below; (E) component: nonionic polymer; 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.

[0155] 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.

[0156] <Preparation of components (A) to (E)> The following components (A) to (E) were prepared.

[0157] <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).

[0158] <Component (B): Anionic polymer> Polyacrylic acid (weight-average molecular weight (Mw) = 25,000).

[0159] <(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).

[0160] <(C') component: base> - Ammonia (molecular weight: 17).

[0161] <(D) Component: pH buffering agent> Ammonium acetate (molecular weight: 77).

[0162] <Component (E): Nonionic polymer> Polyvinyl alcohol (PVA) (weight-average molecular weight (Mw) = 10,000).

[0163] The weight-average molecular weights (Mw) of components (B) and (E) described above were measured by the following method.

[0164] [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.

[0165] <Preparation of Surface Treatment Composition> (Example 1) The surface treatment composition of Example 1 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.

[0166] (Examples 2-6, Comparative Examples 1 and 2) Surface treatment compositions for Examples 2-6 and Comparative Examples 1 and 2 were prepared in the same manner as in Example 1, except that the composition of the surface treatment composition in Example 1 was changed to the composition shown in Table 1. A "-" indicates that the component was not added. Furthermore, the surface treatment compositions prepared above do not contain abrasive grains (abrasive grain content = 0% by mass).

[0167] [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.

[0168] <Preparation of polished workpieces> Polished workpieces (polished silicon nitride substrates) were prepared by the following chemical mechanical polishing (CMP) process.

[0169] [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.

[0170] 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.

[0171] The average primary particle size is calculated from the specific surface area (SA) of silica and the true density of silica, using the BET method measured with Micromeritex's "Flow Sorb II 2300," and is given by: Primary particle size (nm) = 6000 / (True density (g / cm³) ３ ) × SA (m 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.

[0172] 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).

[0173] (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.

[0174] <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.

[0175] (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.

[0176] 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.

[0177] <Measurement of Friction Coefficient> The friction coefficient of the protective film on the substrate obtained by performing the following surface treatment condition A was evaluated based on the torsion signal measured from the LFM by AFM. The measurement method and the method for calculating the friction coefficient are shown below.

[0178] [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.

[0179] AFM detects the horizontal component of the force acting on the probe (tip) from the surface as the twist of the cantilever, thereby detecting spherical SiO ２The frictional force between the probe and the surface can be measured. Using the LFM of Dimension IconIR (manufacturer: Bruker; model number: Dimension IconIR (Model: SPN-211116-01); software name: NanoScope 10.0), the frictional force under any load can be evaluated as the magnitude of the torsional signal (unit: V).

[0180] In this evaluation, the probe (spherical SiO ２ The frictional force was calculated by dividing the difference between the average value of the torsional signal on the forward path and the average value of the torsional signal on the return path during a reciprocal scan of an AFM probe with a probe tip (CP-FM-SiO, manufactured by sQube) by 2. Since the torsional direction is opposite for the forward and return paths, the difference was used. This measurement was performed four times at different locations, and the arithmetic mean of these measurements was applied as the frictional force (F) (before normalization).

[0181] When measuring LFM, it is necessary to consider the effect of vertical offset in addition to the load determined by the cantilever deflection. Vertical offset is the shift of the optical axis in the y-axis direction that occurs when the probe is attached to the AFM unit. The set load (deflection setpoint) is controlled by the amount of cantilever deflection determined by the photodetector, and its origin is the center of the y-axis (Vertical = 0V). The difference from the origin after subtracting the vertical offset becomes the actual load (effective load). In this evaluation, the set load is SiO2 in the surface treatment process. ２ The loads that particles can apply to the protective film layer were set to 1.0 μN, 1.2 μN, and 1.4 μN, and the effective load (N) (before normalization) for each was adopted by taking into account the offset from each set load.

[0182] The coefficient of friction (before normalization) is given by the following formula:

[0183]

[0184] This is shown.

[0185] In other words, the coefficient of friction (μ) (before normalization) for each set load was calculated by dividing the average value (before normalization) of the friction force (F) obtained by the reciprocating scan of the AFM probe at each set load by the effective load (N) (before normalization). The arithmetic mean obtained by dividing the sum of these values ​​by 3 was adopted as the coefficient of friction (μ) (before normalization).

[0186] The measurements were performed in a liquid solution as the measurement environment (atmosphere). Specifically, the solution used was obtained by removing the water-soluble polymer components (components (E) and (B)) from the compositions described in the various examples and comparative examples. The pH was the same as that of the compositions described in the examples and comparative examples.

[0187]

[0188] On the other hand, the coefficient of friction (μ) (control) of the silicon nitride substrate (without protective film) prepared above was measured in the same manner as above, except that pure water was used as the "in liquid" measurement.

[0189] Finally, as described above, the coefficient of friction (μ) (before normalization) was normalized by dividing it by the coefficient of friction (μ) (reference), and the coefficient of friction (μ) (normalized) was calculated.

[0190]

[0191] <Measurement of Hydration Energy> The Gibbs free energy of the acid was calculated based on the hydrated molar Gibbs free energy ΔhydG (kJ / mol) per mole of acid added to the surface treatment composition, using the following references as a reference (see Table 4 below): ・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). The hydration energy of the acid in the surface treatment compositions listed in Table 1 below was calculated by multiplying the molar Gibbs energy of the acid by the number of moles of acid added to the surface treatment composition. Note that this calculation was not performed for the surface treatment composition in Comparative Example 1, which does not contain acid.

[0192]

[0193] <Measurement of Intrinsic Viscosity> The method for measuring the intrinsic viscosity of polyacrylic acid (PAA) is as follows:

[0194] Polymer solutions were prepared by adding PAA, aminoethylpiperazine (AEP), and acid. Solutions were prepared with PAA concentrations adjusted to 0.01% by mass, 0.03% by mass, and 0.05% by mass. The polymer solution corresponding to the surface treatment composition of Comparative Example 1, which does not contain polyacrylic acid, was not measured. For the polymer solutions corresponding to the surface treatment compositions of Comparative Example 2 and Examples 1 to 6, nitric acid, acetic acid, sulfuric acid, and phosphoric acid, similar to those used in the surface treatment compositions, were used, respectively. The viscosity of the solvent was measured using each polymer solution after removing the PAA. The viscosity of the polymer solution and solvent was measured using an Ubbelohde viscometer. The reduced viscosity was determined from the obtained viscosity values, and the relationship with the polymer concentration was plotted. The intercept of the linear approximation was taken as the intrinsic viscosity of polyacrylic acid. Polyvinyl alcohol (PVA), which is contained in the actual surface treatment compositions, was not added to the polymer solutions in this test. The reason for this is that the purpose of this test is to measure the intrinsic viscosity of polyacrylic acid alone, and PVA does not adsorb onto SiN and is not included in the protective film.

[0195] <Measurement of Protective Film Thickness> The thickness of the protective film on the silicon nitride substrate was measured as follows. Specifically, the thickness of the protective film on the silicon nitride substrate obtained by surface treatment under the above surface treatment condition A was evaluated based on force curve measurement using AFM (Manufacturer: Bruker; Model: Dimension IconIR (Model: SPN-211116-01); Software: NanoScope 10.0). The force curve measurement was performed using an AFM probe with a DLC probe (B20-FMR, NANOANDORE) under the following conditions.

[0196]

[0197] <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.

[0198] [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.

[0199] [Scratch 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>.

[0200] (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.

[0201] <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.

[0202] The reason for performing water polishing is that removing the protective film (including PVA in Comparative Example 1) allows for the measurement of scratches on the surface-treated SiN substrate.

[0203] (Scratch measurement) [Preparation of polished workpiece] Polished workpieces (polished silicon nitride substrates) were prepared after being polished by the following chemical mechanical polishing (CMP) process.

[0204] (CMP process) As the object to be polished, a silicon wafer (silicon nitride substrate) (300 mm, blanket wafer, manufactured by Advantech Co., Ltd.) was prepared, with a silicon nitride film with a thickness of 2500 Å formed on its surface by CVD.

[0205] Silica slurry (Composition: Colloidal silica (average primary particle size: 35 nm, average secondary particle size: 70 nm) 10% by mass, Polyvinylpyrrolidone (Pitzcol® K30A, Daiichi Kogyo Seiyaku Co., Ltd., Mw = 45,000) 0.25% by mass, EL ammonia water (Concentration: 28.0% by mass to 30.0% by mass (NH) ３ A silica slurry (manufactured by Kanto Chemical Co., Ltd.) containing 0.33% by mass, with distilled water as the solvent, was prepared. The abrasive composition was prepared by diluting the above silica slurry five times with distilled water. The pH of the obtained abrasive composition was 10.0.

[0206] The silicon nitride substrate prepared as described above was polished using the polishing composition obtained above under the following conditions to obtain a polished object (polished silicon nitride substrate).

[0207] <Polishing equipment and polishing conditions> Polishing equipment: FREX300E manufactured by Ebara Corporation Polishing pad: Foamed polyurethane pad H800-Type1 manufactured by Fuji Spinning Holdings Co., Ltd. Conditioner (dresser): Nylon brush (manufactured by 3M) Polishing pressure: 2.0 psi (1 psi = 6894.76 Pa, the same applies below) Polishing plate rotation speed: 80 rpm Head rotation speed: 80 rpm Supply of polishing composition: flow Polishing composition supply amount: 200 mL / min Polishing time: 30 seconds.

[0208] (Rinse Polishing) After polishing the surface of the object to be polished in the CMP process described above, the polished object was removed from the polishing platen. Subsequently, within the same polishing apparatus, the polished object was mounted on another polishing platen, and rinse polishing was performed on the surface of the polished object using the respective surface treatment compositions of the examples and comparative examples under the following conditions.

[0209] <Rinse polishing equipment and rinse polishing conditions> Polishing equipment: FREX300E manufactured by Ebara Corporation Polishing pad: Foamed polyurethane pad H800-Type1 manufactured by Fuji Spinning Holdings Co., Ltd. Conditioner (dresser): Nylon brush (manufactured by 3M) Polishing pressure: 1.0 psi Plate rotation speed: 80 rpm Head rotation speed: 80 rpm Supply of surface treatment composition: Flow-through Supply amount of surface treatment composition: 300 mL / min Polishing time: 60 seconds.

[0210] (Post-cleaning treatment) After rinsing and polishing, 0.3% by mass NH ３ The polished surface of the polished object was brush-cleaned with an aqueous solution for 20 seconds, and then rinsed with deionized water for 40 seconds to obtain a rinse-polished object (a rinse-polished object and a comparative rinse-polished object).

[0211] (Scratch Evaluation) Using the Surfscan® SP5 optical inspection machine manufactured by KLA-Tencor Co., Ltd., the number of scratches on the surface of rinse-polished objects (rinse-polished objects and comparative rinse-polished objects) was evaluated.

[0212] Specifically, for each rinse-polished object, the number of residue particles with a diameter exceeding 70 nm (when the object is a silicon nitride substrate) and the number of residue particles with a diameter exceeding 50 nm (when the object is a TEOS substrate) were counted in the remaining portion after excluding a 5 mm wide area from the outer edge of one side (the area from 0 mm to 5 mm when the outer edge is considered 0 mm). Subsequently, 100 residue particles were sampled from the remaining portion after excluding the 5 mm wide area from the outer edge of one side of each rinse-polished object using SEM observation. Then, from the 100 sampled residue particles, the type of residue (abrasive grains, scratches, or organic residues) was identified by visual SEM observation, and the number of scratches was measured.

[0213]

[0214] As is clear from Table 1 above, it was found that when surface treatment was performed using the surface treatment composition of the example, scratches on the surface of the polished object (surface-treated object) were reduced.

Claims

A surface treatment composition comprising a water-soluble polymer and a solvent, The aforementioned surface treatment composition is used for surface treatment of a polished object obtained by polishing the object using the polishing composition. The surface treatment is performed in the presence of abrasive grains. A surface treatment composition wherein the thickness of the protective film containing the water-soluble polymer formed when the surface treatment is performed using the surface treatment composition under surface treatment condition A is 0.5 nm or more. 　 The surface treatment composition according to claim 1, wherein the abrasive particles include those derived from the polishing composition. 　 The surface treatment composition according to claim 1, comprising the following components (A) to (C): (A) Component: Piperazine compound, (B) Component: Anionic polymer, (C) Component: acid. 　 The (A) component is represented by the following formula (a), the surface treatment composition according to claim 3: 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. 　 The surface treatment composition according to claim 3, wherein component (A) has two or more amino groups whose pKa is greater than the pH of the surface treatment composition. 　 The surface treatment composition according to claim 3, wherein the content of component (A) is greater than 0.052% by mass with respect to the total mass of the surface treatment composition. 　 The surface treatment composition according to claim 3, wherein the intrinsic viscosity of component (B) is 3.0 dL / g or less. 　 The surface treatment composition according to claim 3, 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. 　 The surface treatment composition according to claim 3, wherein the hydration energy of component (C) is -2000 kJ / mol or more and -100 kJ / mol or less. 　 The surface treatment composition according to claim 3, 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. 　 The surface treatment composition according to claim 3, wherein the coefficient of friction of the protective film is 1.9 or greater. 　 The surface treatment composition according to claim 3, further comprising the following component (D): (D) Component: Formula: A-COO-NH ４ ＋ A buffering agent represented by (A is an alkyl group or phenyl group having 1 to 10 carbon atoms). 　 The surface treatment composition according to claim 12, wherein the (D) component comprises ammonium acetate. 　 The surface treatment composition according to claim 3, further comprising the following component (E); (E) Component: Nonionic polymer. 　 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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