TWI882986B - Polishing composition - Google Patents

Abstract

An object of the present invention is to provide a new polishing composition that contributes to improving the quality of a device. There is provided a polishing composition containing: an abrasive grain having an organic acid immobilized on a surface thereof; a first water-soluble polymer having a sulfonic acid group or a group having a salt thereof, or a carboxyl group or a group having a salt thereof; a second water-soluble polymer different from the first water-soluble polymer; a nonionic surfactant; and an aqueous carrier, wherein the polishing composition is used for polishing an object to be polished.

Description

Grinding composition

The present invention relates to a polishing composition.

Due to the high integration brought about by the miniaturization of LSI manufacturing process, electronic equipment represented by computers has achieved high performance such as miniaturization, multi-function, and high speed. The new micro-processing technology accompanying the high integration of LSI is the use of chemical mechanical polishing (CMP). CMP is frequently used in LSI manufacturing steps, especially in the flattening of interlayer insulation films, metal stud formation, and embedded wiring (embedded wiring) formation in the multi-layer wiring formation step.

The formation of metal plugs or wiring of semiconductor devices is generally performed by forming a conductive layer made of metal on a silicon oxide film, silicon nitride film, polycrystalline silicon film, etc. having a recessed portion, and then removing a portion of the conductive layer by grinding until the above film is exposed. The grinding step is roughly divided into a main (main body) grinding step for removing most of the object to be removed, and a buff polishing step for finishing the object (e.g., Patent Document 1). [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2004-273502

[Problems to be solved by the invention]

In recent years, the above-mentioned membranes have been thinner, and the inventors have found that the quality of the final device produced by the process using only the main grinding step and the polishing step using a general grinding composition is insufficient. Therefore, the problem to be solved by the present invention is to provide a novel grinding composition that helps to improve the quality of the device of the final product. [Means for solving the problem]

In order to solve the above problems, the inventors have actively and repeatedly conducted research. As a result, it was found that the above problems can be solved by providing the following polishing composition, which comprises: abrasive particles formed by immobilizing an organic acid on the surface, a first water-soluble polymer having a sulfonic acid group or a salt thereof or a carboxyl group or a salt thereof, a second water-soluble polymer different from the first water-soluble polymer, a non-ionic surfactant, and an aqueous carrier, and is used for polishing the polishing object. [Effect of the invention]

The polishing composition according to the present invention helps to improve the device quality of the final product.

The present invention is described below. The present invention is not limited to the following embodiments. Unless otherwise specified, the operation and physical properties are measured at room temperature (20-25°C) and relative humidity 40-50%RH.

The present invention is a polishing composition, which comprises: abrasive grains with an organic acid fixed on the surface, a first water-soluble polymer having a sulfonic acid group or a salt thereof or a carboxyl group or a salt thereof, a second water-soluble polymer different from the first water-soluble polymer, a non-ionic surfactant, and an aqueous carrier, and is used for polishing an object. According to the polishing composition, the device quality of the final product is improved.

[Manufacturing process of device] In one embodiment of the present invention, the device is a semiconductor device. In one embodiment of the present invention, a polishing object is formed on a substrate (e.g., a silicon wafer). The polishing object is not particularly limited, and may be, for example, a polishing object of Si-based materials such as silicon-silicon bonds, nitrogen-silicon bonds, or oxygen-silicon bonds. According to this embodiment, roughness can be eliminated by previous polishing, which has the technical effect of reducing processing time and steps in subsequent processes.

In this embodiment, examples of polishing objects having silicon-oxygen bonds include silicon oxide films, BD (black diamond: SiOCH), SiOC, FSG (fluorosilicate glass), HSQ (hydrogenated silsesquioxane), CYCLOTENE, SiLK, MSQ (methyl silsesquioxane), etc. Examples of polishing objects having silicon-silicon bonds include polycrystalline silicon, amorphous silicon, single crystal silicon, n-type doped single crystal silicon, p-type doped single crystal silicon, phosphorus doped polycrystalline silicon, boron doped polycrystalline silicon, SiGe, etc. Si-based alloys, etc. Examples of polishing objects having silicon-nitrogen bonds include silicon nitride films and SiCN (silicon carbonitride).

According to another embodiment of the present invention, the polishing object is carbon, DFR (dry film resist), SiC, etc.

In one embodiment of the present invention, the manufacturing process of the device includes a main body grinding step and a polishing grinding step. In one embodiment of the present invention, the manufacturing process of the device includes a preliminary grinding step, a main body grinding step and a polishing grinding step. Before, after or before and after these grinding steps, a film-forming step of the grinding object to be ground may be included. In this embodiment, before the main body grinding step for removing most of the grinding object, by performing a preliminary grinding step, the influence of the surface roughness of the substrate or the grinding object on the final device can be minimized. In addition, since the number of defects of the device can also be intentionally reduced, the reliability of the device of the final product will be improved. Moreover, by pre-grinding, the roughness can be eliminated, which can reduce the processing time and steps in the subsequent process.

In one embodiment of the present invention, the film thickness of the polishing object is not particularly limited. In one embodiment of the present invention, the film forming method of the polishing object is not particularly limited, and the known film forming techniques such as ALD, CVD, and PVD can be applied. In order to make the film thickness of the polishing object thinner more efficiently, it is preferred to use ALD, but of course it is not limited to this.

In one embodiment of the present invention, the polishing composition can be used for polishing the polishing object in any step, but is preferably used for polishing in the preparatory polishing step. With this embodiment, the influence of surface roughness on the final device can be minimized. In addition, since the number of defects in the device can be intentionally reduced, the reliability of the device in the final product can be improved. Moreover, by pre-polishing, the roughness can be eliminated, and the processing time and steps in the subsequent process can be reduced. Therefore, in one embodiment of the present invention, a manufacturing process for a semiconductor device is provided, which includes a pre-polishing step, a main body polishing step and a polishing polishing step, and the polishing composition of the embodiment of the present invention is used as the polishing composition in the aforementioned pre-polishing step. By this embodiment, the influence of surface roughness on the final device can be minimized. In addition, since the number of defects of the device can be intentionally reduced, the reliability of the final device can be improved. In one embodiment of the present invention, the polishing compositions used in the preliminary polishing step, the main body polishing step, and the polishing step can be different from each other. That is, the composition of the polishing composition of the preliminary polishing step, the composition of the polishing composition of the main body polishing step, and the polishing composition of the polishing step can be completely different.

[Polishing method] In one embodiment of the present invention, a polishing method for a polishing object is provided, which comprises using a polishing composition to polish the polishing object. According to this polishing method, the device quality of the final product is improved. In one embodiment of the present invention, for example, a method of using a polishing device to press the polishing object against a polishing pad and rotating the polishing object while the polishing composition flows out continuously is used.

As the polishing device, a general polishing device having a polishing platen to which a polishing pad can be attached, equipped with a holder for holding the polishing object, a motor for changing the rotation speed, etc. can be used. As the polishing pad, general non-woven fabrics, polyurethane, porous fluorine resin, etc. can be used without particular limitation.

In one embodiment of the present invention, the grinding conditions in the preliminary grinding step, the main body grinding step and the polishing grinding step are preferably appropriately set.

In one embodiment of the present invention, the upper limit of the pressure between the polishing object and the polishing pad in the preliminary polishing step is preferably less than 3psi, more preferably less than 2psi, and even more preferably less than 1.6psi, and even more preferably less than 1.5psi. In this embodiment, the lower limit of the pressure between the polishing object and the polishing pad in the preliminary polishing step is preferably greater than 0.1psi, more preferably greater than 0.3psi, and even more preferably greater than 0.5psi. In this embodiment, the upper limit of the number of rotations of the polishing head (carrier) in the preliminary polishing step is preferably less than 120rpm, more preferably less than 100rpm, and even more preferably less than 80rpm. In this embodiment, the lower limit of the number of rotations of the polishing head in the preliminary polishing step is preferably greater than 50rpm, more preferably greater than 60rpm, and even more preferably greater than 70rpm. In this embodiment, the upper limit of the platen rotation number in the preliminary grinding step is preferably less than 120 rpm, more preferably less than 100 rpm, and more preferably less than 90 rpm. In this embodiment, the lower limit of the platen rotation number in the preliminary grinding step is preferably 50 rpm or more, more preferably 60 rpm or more, and more preferably 70 rpm or more. The supply amount flowing out in the preliminary grinding step is not limited, but it is preferably that the surface of the grinding object is covered with the grinding composition, for example, 50 to 300 ml/min. In addition, the grinding time is not particularly limited, but it is preferably 5 to 60 seconds.

In the present embodiment, the upper limit of the pressure between the grinding object and the grinding pad in the main grinding step is preferably less than 10psi, more preferably less than 7psi, and even more preferably less than 5psi. In the present embodiment, the lower limit of the pressure between the grinding object and the grinding pad in the main grinding step is preferably greater than 1psi, more preferably greater than 1.5psi, even more preferably greater than 1.6psi, even more preferably greater than 2psi, and even more preferably greater than 3psi. In the present embodiment, the upper limit of the number of rotations of the grinding head in the main grinding step is preferably less than 130rpm, more preferably less than 120rpm, and even more preferably less than 110rpm. In the present embodiment, the lower limit of the number of rotations of the grinding head in the main grinding step is preferably greater than 80rpm, more preferably greater than 90rpm, and even more preferably greater than 100rpm. In this embodiment, the upper limit of the platen rotation number in the main body grinding step is preferably less than 140 rpm, more preferably less than 130 rpm, and more preferably less than 120 rpm. In this embodiment, the lower limit of the platen rotation number in the main body grinding step is preferably 80 rpm or more, more preferably 90 rpm or more, and more preferably 100 rpm or more. The supply amount flowing out in the main body grinding step is not limited, but it is preferably that the surface of the grinding object is covered with the grinding composition, for example, 50~300 ml/min. In addition, the grinding time is not particularly limited, but it is preferably 30~120 seconds.

In the present embodiment, the upper limit of the pressure between the polishing object and the polishing pad in the polishing step is preferably less than 3psi, more preferably less than 2psi, further preferably less than 1.6psi, and further preferably less than 1.5psi. In the present embodiment, the lower limit of the pressure between the polishing object and the polishing pad in the polishing step is preferably greater than 0.3psi, more preferably greater than 0.6psi, and further preferably greater than 0.8psi. In the present embodiment, the upper limit of the number of rotations of the polishing head in the polishing step is preferably less than 100rpm, more preferably less than 90rpm, and further preferably less than 80rpm. In the present embodiment, the lower limit of the number of rotations of the polishing head in the polishing step is preferably greater than 50rpm, more preferably greater than 60rpm, and further preferably greater than 70rpm. In this embodiment, the upper limit of the platen rotation number in the polishing and grinding step is preferably less than 120 rpm, more preferably less than 100 rpm, and more preferably less than 90 rpm. In this embodiment, the lower limit of the platen rotation number in the polishing and grinding step is preferably 60 rpm or more, more preferably 70 rpm or more, and more preferably 80 rpm or more. The supply amount flowing out in the polishing and grinding step is not limited, but it is preferably that the surface of the polishing object is covered with the polishing composition, for example, 50 to 300 ml/min. In addition, the grinding time is not particularly limited, but it is preferably 5 to 60 seconds.

In one embodiment of the present invention, (pressure between the polishing object and the polishing pad in the preliminary polishing step)/(pressure between the polishing object and the polishing pad in the main polishing step) is preferably less than 1.0, more preferably less than 0.75, and even more preferably less than 0.5. In one embodiment of the present invention, (pressure between the polishing object and the polishing pad in the preliminary polishing step)/(pressure between the polishing object and the polishing pad in the main polishing step) is preferably greater than 0.15, more preferably greater than 0.20, and even more preferably greater than 0.25.

In one embodiment of the present invention, (pressure between the polishing object and the polishing pad in the polishing step)/(pressure between the polishing object and the polishing pad in the main polishing step) is preferably less than 1.0, more preferably less than 0.75, and more preferably less than 0.5. In one embodiment of the present invention, (pressure between the polishing object and the polishing pad in the polishing step)/(pressure between the polishing object and the polishing pad in the main polishing step) is preferably greater than 0.15, more preferably greater than 0.20, and more preferably greater than 0.2.

In one embodiment of the present invention, (pressure between the polishing object and the polishing pad in the polishing step)/(pressure between the polishing object and the polishing pad in the preliminary polishing step) is preferably 3.0 or less, more preferably 2.5 or less, and even more preferably 2.0 or less. In one embodiment of the present invention, (pressure between the polishing object and the polishing pad in the polishing step)/(pressure between the polishing object and the polishing pad in the preliminary polishing step) is preferably 0.1 or more, more preferably 0.3 or more, and even more preferably 0.5 or more.

In one embodiment of the present invention, a preliminary polishing step is performed before the main body polishing step, and a polishing step is performed after the main body polishing step. In one embodiment of the present invention, at least one of a cleaning polishing treatment and a washing treatment may be provided after the polishing step. In addition, as the cleaning composition or the washing composition, conventionally known ones may be appropriately used.

[Polishing composition] In one embodiment of the present invention, the polishing composition comprises: abrasive grains having an organic acid fixed on the surface, a first water-soluble polymer having a sulfonic acid group or a salt thereof or a carboxyl group or a salt thereof, a second water-soluble polymer different from the first water-soluble polymer, a non-ionic surfactant, and an aqueous carrier, and is used for polishing an object to be polished.

[Abrasive grains with organic acid fixed on the surface] In one embodiment of the present invention, the polishing composition includes abrasive grains with organic acid fixed on the surface (also referred to as "abrasive grains" in this specification). The abrasive grains contained in the polishing composition have the function of mechanically polishing the polishing object.

In one embodiment of the present invention, specific examples of abrasive grains include particles made of metal oxides such as silicon dioxide, aluminum oxide, zirconium oxide, and titanium oxide. The abrasive grains can be used alone or in combination of two or more. Furthermore, the abrasive grains can be commercially available or synthetic. Among the abrasive grains, silicon dioxide is preferred, fumed silica and colloidal silica are more preferred, and colloidal silica is particularly preferred. As methods for producing colloidal silica, sodium silicate method and sol-gel method are exemplified, and colloidal silica produced by any of the production methods can be preferably used as the abrasive grains of the present invention. However, colloidal silica produced by the sol-gel process is preferred, which can be produced in high purity.

In one embodiment of the present invention, the abrasive grains are abrasive grains with an organic acid fixed on the surface. If abrasive grains with an organic acid fixed on the surface are not used, the desired effect of the present invention cannot be exerted. In particular, when the pH of the polishing composition is adjusted to an acidic region, if the abrasive grains with an organic acid fixed on the surface are not contained, the surface roughness of the polishing object may be deteriorated.

In one embodiment of the present invention, the aforementioned organic acid is not particularly limited, and examples thereof include sulfonic acid, carboxylic acid, phosphoric acid, etc., preferably sulfonic acid. In addition, the silica with an organic acid fixed on the surface is an acidic group (such as a sulfonic group, a carboxyl group, a phosphoric acid group, etc.) derived from the above-mentioned organic acid, which is fixed to the silica surface by covalent bonds (via a linking group structure as the case may be). Here, the so-called linking group structure refers to any structure between the silica surface and the organic acid. Therefore, the silica with an organic acid fixed on the surface can be formed by fixing the acidic group derived from the organic acid to the silica surface by direct covalent bonds, or can be fixed to the silica surface by covalent bonds via a linking group structure. The method of introducing the organic acid onto the surface of silica is not particularly limited. There are methods of introducing the organic acid onto the surface of silica in the form of a hydroxyl group or an alkyl group, followed by oxidation to a sulfonic acid or a carboxylic acid. There are also methods of introducing the organic acid onto the surface of silica in the form of a protective group bonded to the organic acid group, followed by removal of the protective group.

As a specific synthesis method of silica with an organic acid fixed on the surface, if sulfonic acid, one of the organic acids, is fixed on the surface of silica, it can be carried out by, for example, the method described in "Sulfonic acid-functionalized silica through quantitative oxidation of thiol groups" Chem. Commun. 246-247 (2003). Specifically, after coupling a silane coupling agent having a thiol group such as 3-thiolpropyltrimethoxysilane to silica, the thiol group is oxidized with hydrogen peroxide to obtain silica with sulfonic acid fixed on the surface. The colloidal silica with sulfonic acid modified on the surface of the embodiment of the present invention is also produced in the same manner.

If carboxylic acid is immobilized on the surface of silica, it can be done by, for example, the method described in "Novel Silane Coupling Agents Containing a Photo labile 2-Nitrobenzyl Ester for Introduction of a Carboxy Group on the Surface of Silica Gel", Chemistry Letters, 3, 228-229 (2000). Specifically, a silane coupling agent containing a photoreactive 2-nitrobenzyl ester is coupled to silica and then irradiated with light to obtain silica with carboxylic acid immobilized on the surface.

In one embodiment of the present invention, the average primary particle size of the aforementioned abrasive particles is preferably 10 nm or more, more preferably 15 nm or more, more preferably 20 nm or more, more preferably 25 nm or more, and more preferably 30 nm or more. In the polishing composition of the embodiment of the present invention, the average primary particle size of the aforementioned abrasive particles is preferably 60 nm or less, more preferably 50 nm or less, and more preferably 40 nm or less. By making the abrasive particles have the above-mentioned average primary particle size, it has the effect of reducing scratches, reducing defects, and increasing the polishing speed. The average primary particle size of the present invention can be a value measured by the method described in the embodiment.

In one embodiment of the present invention, the average secondary particle size of the aforementioned abrasive particles is preferably 40 nm or more, more preferably 45 nm or more, even more preferably 50 nm or more, even more preferably 55 nm or more, even more preferably 60 nm or more, even more preferably 65 nm or more. In one embodiment of the present invention, the average secondary particle size of the aforementioned abrasive particles is preferably less than 100 nm, more preferably 90 nm or less, more preferably 80 nm or less, even more preferably 70 nm or less. By making the abrasive particles have the above-mentioned average secondary particle size, the polishing speed is increased. The average secondary particle size of the present invention can adopt a value measured by the method described in the embodiment. If the average secondary particle size of the aforementioned abrasive particles is 100 nm or more, there is a concern that the dispersion stability of the abrasive particles is reduced.

In one embodiment of the present invention, in the particle size distribution of the abrasive particles in the polishing composition obtained by the laser diffraction scattering method, the lower limit of the ratio of the particle diameter D90 when the cumulative particle mass reaches 90% from the microparticle side to the particle diameter D10 when the cumulative particle mass reaches 10% (also referred to as "D90/D10" in this specification) is preferably 1.3 or more, more preferably 1.4 or more, more preferably 1.5 or more, and more preferably 1.6 or more. By setting this lower limit, the polishing speed can be increased. In one embodiment of the present invention, the upper limit of D90/D10 is preferably 4.0 or less, more preferably 3.5 or less, more preferably 3.0 or less, and more preferably 2.0 or less.

In one embodiment of the present invention, the aspect ratio of the abrasive grains is preferably 1.05 or more, more preferably 1.10 or more, and even more preferably 1.15 or more. This embodiment has a technical effect of increasing the polishing speed. In one embodiment of the present invention, the aspect ratio of the abrasive grains is preferably 5 or less, more preferably 2 or less, and even more preferably 1.5 or less. This embodiment has a technical effect of increasing the dispersion stability and reducing the number of defects. In addition, the method for measuring the aspect ratio of the abrasive grains is the method described in the embodiment.

In one embodiment of the present invention, in the polishing composition, from the viewpoint of increasing the polishing rate or reducing the surface roughness after polishing, the content of the abrasive grains is preferably more than 0.001% by mass, more preferably more than 0.005% by mass, further preferably more than 0.01% by mass, further preferably more than 0.05% by mass, further preferably more than 0.1% by mass, further preferably more than 0.01% by mass, further preferably more than 0.3% by mass, can be more than 0.8% by mass, can be more than 1.2% by mass, can be more than 2% by mass, can be more than 3% by mass, can be more than 4% by mass. In one embodiment of the present invention, in the polishing composition, from the viewpoint of reducing scratches or reducing the number of defects, the content of the abrasive grains is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less, still more preferably 10% by mass or less, still more preferably 7% by mass or less, and can be 5% by mass or less, 4% by mass or less, 3% by mass or less, 2% by mass or less, 1% by mass or less, less than 1% by mass, 0.8% by mass or less, 0.7% by mass or less, and 0.6% by mass or less. In addition, in this specification, when the content of a substance is contained in two or more kinds of substances, it means the total amount thereof.

(First water-soluble polymer) In one embodiment of the present invention, the polishing composition includes a first water-soluble polymer. The first water-soluble polymer contains: a sulfonic acid group or a salt thereof or a carboxyl group or a salt thereof.

In one embodiment of the present invention, the first water-soluble polymer has a benzene ring. In this embodiment, the benzene ring may be incorporated into the main chain of the first water-soluble polymer or may be incorporated in the form of a side chain group.

In one embodiment of the present invention, the first water-soluble polymer may contain a heteroatom in at least one of its main chain and side chain, but preferably does not contain a heteroatom in order to effectively exert the desired effect of the present invention. In addition, examples of the heteroatom include at least one of an oxygen atom, a nitrogen atom, and a sulfur atom.

In one embodiment of the present invention, the first water-soluble polymer comprises a constituent unit represented by the following formula (1):

R ⁹ is a hydrogen atom or a methyl group, R ¹⁰ and R ¹¹ are each independently a hydrogen atom, -COOR ¹² or -G, but R ¹⁰ and R ¹¹ are not simultaneously hydrogen atoms, -G is a sulfonic acid group,

However, * indicates a bonding position, R ¹² , R ¹³ and R ¹⁵ are independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a hydroxyalkyl group having 1 to 12 carbon atoms or a relative cation, and R ¹⁴ is a divalent group. This embodiment can efficiently exert the desired effect of the present invention. In addition, in this specification, * indicates a bonding position.

In one embodiment of the present invention, the first water-soluble polymer may include two or more different structural units represented by the above formula (1).

Here, the alkyl group having 1 to 12 carbon atoms may be a straight chain or a branched chain, and examples include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, hexadecyl, stearyl, eicosyl, docosyl, tetracosyl, triacontyl, isopropyl, isobutyl, t-butyl, isopentyl, neopentyl, t-pentyl, isoheptyl, 2-ethylhexyl, and isodecyl.

Furthermore, examples of the hydroxyalkyl group having 1 to 12 carbon atoms include a group in which at least one hydrogen atom of the aforementioned alkyl group having 1 to 12 carbon atoms is substituted with a hydroxy group.

Examples of the divalent group include an alkylene group having 1 to 12 carbon atoms and an arylene group having 6 to 24 carbon atoms. The alkylene group having 1 to 12 carbon atoms is a divalent substituent obtained by removing two hydrogen atoms from the alkyl group having 1 to 12 carbon atoms. The arylene group having 6 to 24 carbon atoms is preferably a phenylene group or a naphthalene diyl group.

Examples of relative cations include ammonium ions and sodium ions.

In one embodiment of the present invention, R ⁹ is a hydrogen atom or a methyl group, at least one of R ¹⁰ and R ¹¹ is -G, and -G is a sulfonic acid group or

^R13 is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a hydroxyalkyl group having 1 to 12 carbon atoms, or a relative cation.

In one embodiment of the present invention, two or more different constituent units represented by the above formula (1) are included, one constituent unit is represented by R ⁹ being a hydrogen atom or a methyl group, at least one of R ¹⁰ and R ¹¹ being COOR ¹² , R ¹² being a hydrogen atom or a relative cation, and one constituent unit is represented by R ⁹ being a hydrogen atom or a methyl group, at least one of R ¹⁰ and R ¹¹ being -G, -G being a sulfonic acid group or

^R13 is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a hydroxyalkyl group having 1 to 12 carbon atoms, or a relative cation.

In one embodiment of the present invention, R ⁹ is a hydrogen atom or a methyl group, R ¹⁰ and R ¹¹ are -COOR ¹² and a hydrogen atom, respectively, and R ¹² is a hydrogen atom or a relative cation. In this case, the pH is preferably less than 7.0, and more preferably less than 5.0.

In one embodiment of the present invention, the first water-soluble polymer comprises R ⁹ being a hydrogen atom or a methyl group, R ¹⁰ and R ¹¹ being -COOR ¹² and a hydrogen atom, respectively, and R ¹² being a hydrogen atom or a relative cation constituent unit; and R ⁹ being a hydrogen atom or a methyl group, R ¹⁰ and R ¹¹ being -COOR ¹² , and R ¹² being a hydrogen atom or a relative cation constituent unit. In this case, it may also be in an anhydrous state, but preferably it is not in an anhydrous state.

In one embodiment of the present invention, R ⁹ is a hydrogen atom or a methyl group, R ¹⁰ and R ¹¹ are both -COOR ¹² or a hydrogen atom, and R ¹² is a hydrogen atom or a relative cation.

In one embodiment of the present invention, the first water-soluble polymer comprises a constituent unit in which R ⁹ is a hydrogen atom or a methyl group, R ¹⁰ and R ¹¹ are respectively -COOR ¹² and a hydrogen atom, and R ¹² is a constituent unit of a hydrogen atom or a relative cation; and a constituent unit in which R ⁹ is a hydrogen atom or a methyl group, at least one of R ¹⁰ and R ¹¹ is -COOR ¹² , and R ¹² is a constituent unit of a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.

In one embodiment of the present invention, the first water-soluble polymer comprises R ⁹ is a hydrogen atom or a methyl group, at least one of R ¹⁰ and R ¹¹ is -COOR ¹² , R ¹² is a hydrogen atom or a relative cation constituent unit; and R ⁹ is a hydrogen atom or a methyl group, at least one of R ¹⁰ and R ¹¹ is -G, -G is

^R14 is a divalent group, and ^R15 is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a hydroxyalkyl group having 1 to 12 carbon atoms, or a constituent unit of a relative cationic ion.

In one embodiment of the present invention, R ⁹ is a hydrogen atom or a methyl group, at least one of R ¹⁰ and R ¹¹ is -G, and -G is

^R14 is a divalent group, and ^R15 is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a hydroxyalkyl group having 1 to 12 carbon atoms, or a relative cation.

In one embodiment of the present invention, the first water-soluble polymer is a copolymer of sulfonic acid and carboxylic acid (also referred to as "sulfonic acid/carboxylic acid copolymer"). The copolymer of sulfonic acid and carboxylic acid contains constituent units derived from monomers having sulfonic acid groups and constituent units derived from monomers having carboxylic acid groups.

In one embodiment of the present invention, examples of monomers having a sulfonic acid group include, for example, polyalkylene glycol monomers (A) described in paragraphs [0019] to [0036] of JP-A-2015-168770, or sulfonic acid group-containing monomers (C) described in paragraphs [0041] to [0054] of the same publication.

In one embodiment of the present invention, examples of monomers having a carboxylic acid group include acrylic acid, methacrylic acid, crotonic acid, α-hydroxyacrylic acid, α-hydroxymethacrylic acid, and salts thereof such as metal salts, ammonium salts, and organic amine salts.

In one embodiment of the present invention, the molar ratio of the constituent units derived from the monomers having sulfonic acid groups to the constituent units derived from the monomers having carboxylic acid groups in the sulfonic acid/carboxylic acid copolymer is preferably constituent units derived from the monomers having sulfonic acid groups: constituent units derived from the monomers having carboxylic acid groups = 5:95 to 95:5, more preferably 10:90 to 90:10, further preferably 30:70 to 70:30, further preferably 45:55 to 65:35, and most preferably 50:50 to 60:40.

In one embodiment of the present invention, the weight average molecular weight of the first water-soluble polymer is preferably 1000 or more, 2000 or more, 3000 or more, 4000 or more, 5000 or more, 6000 or more, 6500 or more, 7000 or more, 8000 or more, 9000 or more, 9500 or more, 10,000 or more, 15,000 or more, or more than 15,000, from the viewpoint of the adsorption rate of the polishing object (i.e., the ease of adsorption of the polishing object). In one embodiment of the present invention, the weight average molecular weight of the first water-soluble polymer is preferably 100,000 or less, 30,000 or less, 25,000 or less, 20,000 or less, 15,000 or less, 10,000 or less, 9,500 or less, 9,000 or less, 8,000 or less, 7,000 or less, 6,500 or less, or less than 6,500, from the viewpoint of the release rate from the polishing object (from the ease of release from the polishing object described later). In this embodiment, from the perspective of reducing the number of defects in the polishing object containing oxygen-silicon bonds, the weight average molecular weight is preferably greater than 15,000, from the perspective of reducing the number of defects in the polishing object containing nitrogen-silicon bonds, the weight average molecular weight is preferably less than 6,500, and from the perspective of reducing the number of defects in the polishing object containing silicon-silicon bonds, the weight average molecular weight is preferably 6,500 to 15,000.

In this specification, the weight average molecular weight is measured by gel permeation chromatography (GPC) using polystyrene with a known molecular weight as a standard substance.

In one embodiment of the present invention, the content of the first water-soluble polymer is preferably 0.001 mass % or more, 0.005 mass % or more, 0.05 mass % or more, or 0.8 mass % or more, and may be 0.2 mass % or more, 0.4 mass % or more, 0.6 mass % or more, or 0.8 mass % or more, relative to the total mass of the polishing composition. In one embodiment of the present invention, the content of the first water-soluble polymer is preferably 10 mass % or less, 8 mass % or less, 6 mass % or less, 4 mass % or less, 2 mass % or less, 1.9 mass % or less, 1.8 mass % or less, 1.7 mass % or less, 1.6 mass % or less, 1.5 mass % or less, 1.4 mass % or less, 1.3 mass % or less, 1.2 mass % or less, 1.1 mass % or less, 1.0 mass % or less, 0.9 mass % or less, 0.8 mass % or less, 0.7 mass % or less, 0.6 mass % or less, 0.5 mass % or less, 0.4 mass % or less, 0.3 mass % or less, or 0.2 mass % or less. According to the embodiment of the present invention, even if the amount of the first water-soluble polymer added is relatively small, the effect of the present invention can be effectively exerted through the supplementary synergistic effect of the second water-soluble polymer and the non-ionic surfactant.

In one embodiment of the present invention, the first water-soluble polymer may be a homopolymer or a copolymer. In the case of a copolymer, the first water-soluble polymer may be in the form of a block copolymer, a random copolymer, a graft copolymer, or an alternating copolymer.

In one embodiment of the present invention, the first water-soluble polymer is at least one selected from the group consisting of polystyrene sulfonic acid, a (co)polymer of which a part of the structure includes constituent units derived from polystyrene sulfonic acid, a copolymer of sulfonic acid and carboxylic acid, sulfonated polysulfone and polyaniline. By this embodiment, the desired effect of the present invention can be efficiently exerted.

(Second water-soluble polymer) In one embodiment of the present invention, the polishing composition includes a second water-soluble polymer different from the first water-soluble polymer. It is to be noted that the second water-soluble polymer may also contain a sulfonic acid group or a salt thereof or a carboxyl group or a salt thereof, as long as it is different from the first water-soluble polymer.

In one embodiment of the present invention, the second water-soluble polymer comprises a constituent unit represented by the following formula (2):

X is represented by:

R ¹ to R ⁶ are independently hydrogen or -J, -J is a hydroxyl group, a sulfonic acid group or a salt thereof,

However, * indicates a bonding position, and ^R7 and ^R8 are each independently a hydrogen atom or -E, and -E is represented by the following formula:

However, * indicates a bonding position, and the aforementioned constituent unit includes at least one of -J and -E. By this embodiment, the expected effect of the present invention can be efficiently exerted.

In one embodiment of the present invention, X is as follows:

At least one of R ¹ to R ⁴ is -J, -J is a hydroxyl group, a sulfonic acid group or a salt thereof, or

is better.

In one embodiment of the present invention, X is as follows:

At least one of R ¹ to R ⁴ is -J, and -J is

is better.

In one embodiment of the present invention, X is as follows:

At least one of R ¹ , R ² , R ⁵ and R ⁶ is a hydrogen atom, R ⁸ is -E, and -E is of the following formula:

It means it is better.

In one embodiment of the present invention, the weight average molecular weight of the second water-soluble polymer is preferably 5,000 or more, 10,000 or more, 15,000 or more, 20,000 or more, or 25,000 or more, based on the viewpoint of reducing the number of scratches or defects. In one embodiment of the present invention, the weight average molecular weight of the second water-soluble polymer is preferably 60,000 or less, 50,000 or less, 40,000 or less, less than 30,000, 35,000 or less, 20,000 or less, 15,000 or less, or 12,000 or less, based on the viewpoint of reducing the number of defects after polishing. According to the embodiment of the present invention, even if the weight average molecular weight of the second water-soluble polymer is relatively large, the effect of the present invention can be effectively exerted by the synergistic effect with the first water-soluble polymer and the non-ionic surfactant.

In one embodiment of the present invention, when the second water-soluble polymer is polyvinyl alcohol (PVA) or a (co)polymer whose structure partially includes constituent units derived from polyvinyl alcohol (PVA), the weight average molecular weight is preferably less than 3000, less than 2000, less than 15000, and less than 12000. Furthermore, when the weight average molecular weight of the second water-soluble polymer is less than 15000, polypropylene glycol is preferably used as a surfactant in order to reduce the number of defects in SiN.

In one embodiment of the present invention, the content of the second water-soluble polymer is preferably 0.001 mass % or more, 0.005 mass % or more, 0.05 mass % or more, 0.08 mass % or more, 0.2 mass % or more, 0.4 mass % or more, 0.6 mass % or more, or 0.8 mass % or more relative to the total mass of the polishing composition. By this embodiment, the desired effect of the present invention can be efficiently exerted. In one embodiment of the present invention, the content of the second water-soluble polymer is preferably 10 mass % or less, 8 mass % or less, 6 mass % or less, 4 mass % or less, 2 mass % or less, 1.9 mass % or less, 1.8 mass % or less, 1.7 mass % or less, 1.6 mass % or less, 1.5 mass % or less, 1.4 mass % or less, 1.3 mass % or less, 1.2 mass % or less, or 1.1 mass % or less, and may be 0.8 mass % or less, 0.6 mass % or less, 0.4 mass % or less, or 0.3 mass % or less. According to the implementation form of the present invention, even if the amount of the second water-soluble polymer added is relatively small, the effect of the present invention can be effectively exerted through the supplementary synergistic effect of the first water-soluble polymer and the non-ionic surfactant, especially for polishing objects containing oxygen-silicon bonds and polishing objects containing nitrogen-silicon bonds.

In one embodiment of the present invention, the second water-soluble polymer may be a homopolymer or a copolymer. In the case of a copolymer, the copolymer may be in the form of a block copolymer, a random copolymer, a graft copolymer, or an alternating copolymer.

In one embodiment of the present invention, the second water-soluble polymer is at least one selected from the group consisting of polyvinyl alcohol (PVA), a (co)polymer containing a constituent unit derived from polyvinyl alcohol in a part of its structure, poly-N-vinyl acetamide, and a (co)polymer containing a constituent unit derived from poly-N-vinyl acetamide in a part of its structure. By this embodiment, the desired effect of the present invention can be efficiently exerted.

In one embodiment of the present invention, the saponification degree of the polyvinyl alcohol (PVA) or the (co)polymer containing constituent units derived from polyvinyl alcohol (PVA) in a part of its structure is preferably 90% or more.

In one embodiment of the present invention, at least one of the first water-soluble polymer and the second water-soluble polymer is a homopolymer. This embodiment has a technical effect of reducing defects in silicon nitride films.

In one embodiment of the present invention, the second water-soluble polymer contains a sulfonic acid group or a salt thereof. Since not only the first water-soluble polymer but also the second water-soluble polymer contains a sulfonic acid group or a salt thereof, the first water-soluble polymer and the second water-soluble polymer can be adsorbed on the surface of the polishing object by charge interaction, thereby increasing the density of the protective film. The protective film can reduce the number of defects by playing the role of an easily peelable anti-adhesion film (also referred to as "anti-adhesion film" in this specification) that prevents defect-causing substances from adhering to the surface of the polishing object.

[pH of the polishing composition] In one embodiment of the present invention, the pH of the polishing composition is less than 9.0. In one embodiment of the present invention, the pH of the polishing composition is less than 8.0. In one embodiment of the present invention, the pH of the polishing composition is less than 7.0. In one embodiment of the present invention, the pH of the polishing composition is less than 6.0. In one embodiment of the present invention, the pH of the polishing composition is less than 5.0. In one embodiment of the present invention, the pH of the polishing composition is less than 4.5. In one embodiment of the present invention, the pH of the polishing composition is less than 4.0. In one embodiment of the present invention, the pH of the polishing composition is less than 3.9, less than 3.7, less than 3.5, or less than 3.3. In one embodiment of the present invention, the pH of the polishing composition exceeds 1.0. In one embodiment of the present invention, the pH of the grinding composition exceeds 1.5. In one embodiment of the present invention, the pH of the grinding composition exceeds 2.0. In one embodiment of the present invention, the pH of the grinding composition is 2.1 or more. In one embodiment of the present invention, the pH of the grinding composition is 2.3 or more. In one embodiment of the present invention, the pH of the grinding composition is 2.5 or more. In one embodiment of the present invention, the pH of the grinding composition is 2.7 or more. In one embodiment of the present invention, the pH of the grinding composition exceeds 2.0 and does not reach 5.0, and further exceeds 2.0 and does not reach 4.0. By means of this embodiment, the desired effect of the present invention can be effectively exerted.

In one embodiment of the present invention, the polishing composition includes a pH adjuster. As the pH adjuster, a known acid, base, or salt thereof can be used. Specific examples of the acid that can be used as the pH adjuster include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid and phosphoric acid, or organic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, heptanoic acid, 2-methylhexanoic acid, octanoic acid, 2-ethylhexanoic acid, benzoic acid, hydroxyacetic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, apple acid, tartaric acid, citric acid, lactic acid, diglycolic acid, 2-furancarboxylic acid, 2,5-furandicarboxylic acid, 3-furancarboxylic acid, 2-tetrahydrofurancarboxylic acid, methoxyacetic acid, methoxyphenylacetic acid and phenoxyacetic acid. However, one of the characteristics of the polishing composition of the present invention is that it contains a first water-soluble polymer having a sulfonic acid group or a salt thereof or a carboxylic acid group or a salt thereof. Therefore, according to one embodiment of the present invention, the acid used as the pH adjuster is only the first water-soluble polymer. According to this embodiment, the first water-soluble polymer can be promoted to form a protective film on the surface of the polishing object by charge interaction. The protective film can reduce the number of defects by playing a role as an anti-adhesion film that prevents the defect-causing substance from adhering to the surface of the polishing object and is easy to peel off.

Furthermore, when the second water-soluble polymer contains a sulfonic acid group or a salt thereof, the acid used as the pH adjuster is only the first water-soluble polymer and the second water-soluble polymer. According to this embodiment, the first water-soluble polymer and the second water-soluble polymer can be promoted to form a protective film on the surface of the polishing object by charge interaction. Since the protective film functions as an easily peelable anti-adhesion film that prevents defect-causing substances from adhering to the surface of the polishing object, the number of defects can be reduced. In the embodiment of the present invention, such effects can be particularly exerted on Si-based materials (specifically, all substances containing silicon elements such as silicon oxide, polycrystalline silicon, and silicon nitride) as the polishing object.

Examples of bases that can be used as pH adjusters include amines such as aliphatic amines and aromatic amines, ammonium solutions, organic bases such as quaternary ammonium hydroxide, hydroxides of alkali metals such as potassium hydroxide, hydroxides of Group 2 elements, amino acids such as histidine, and ammonia. The pH adjuster can be used alone or in combination of two or more. The amount of pH adjuster added is not particularly limited, as long as the polishing composition is appropriately adjusted to the desired pH.

(Non-ionic surfactant) In one embodiment of the present invention, the polishing composition includes a non-ionic surfactant.

In one embodiment of the present invention, the non-ionic surfactant is a polymer, and its weight average molecular weight is preferably 50 or more, more preferably 100 or more, and more preferably 200 or more. By this embodiment, the desired effect of the present invention can be effectively exerted. In one embodiment of the present invention, the non-ionic surfactant is a polymer, and its weight average molecular weight is preferably 10,000 or less, more preferably 5,000 or less, and more preferably 1,000 or less. By this embodiment, the desired effect of the present invention can be effectively exerted.

In one embodiment of the present invention, the aforementioned non-ionic surfactant comprises a glycerol structure and an alkyl group with a carbon number of 4 or more. In one embodiment of the present invention, the aforementioned non-ionic surfactant comprises a glycerol structure and an alkyl group with a carbon number of 4 or more. In one embodiment of the present invention, the carbon number of the alkyl group is preferably 6 or more, more preferably 8 or more, and even more preferably 10 or more. By means of this embodiment, it can be selectively adsorbed on the surface of Si-based materials, and the desired effect of the present invention can be effectively exerted. In one embodiment of the present invention, the carbon number of the alkyl group is preferably 18 or less, more preferably 16 or less, and even more preferably 14 or less. By means of this embodiment, it has the technical effect of being adsorbed on the surface of Si-based materials and then being easily detached (for example, during washing or cleaning).

In one embodiment of the present invention, the primary hydroxyl density of the aforementioned non-ionic surfactant is 50% or more. To be more specific, the primary hydroxyl groups in all the hydroxyl groups of the non-ionic surfactant (e.g., polyglycerol-based surfactant) account for 50% or more. When the primary hydroxyl density of the aforementioned non-ionic surfactant is less than 50%, there is a concern that it may be difficult to adsorb on the surface of Si-based materials. According to this embodiment, the primary hydroxyl density is preferably 60% or more, more preferably 65% or more, even more preferably 70% or more, and even more preferably 75% or more. This embodiment has the technical effect of being easily adsorbed on the surface of Si-based materials. According to this embodiment, the primary hydroxyl group density is preferably 99% or less, more preferably 95% or less, further preferably 92% or less, and further preferably 90% or less.

The method for adjusting the primary hydroxyl density of the aforementioned non-ionic surfactant to the above-mentioned value is not particularly limited, and the method disclosed in, for example, Japanese Patent Publication No. 2006-346526 can be used. In addition, although the disclosure is directed to polyglycerol lauryl ester in the publication, the viewpoint of adjusting the primary hydroxyl density to the above-mentioned value can also be applied to other polyol-based non-ionic surfactants (such as polyglycerol lauryl ether). In addition, the ratio of the primary hydroxyl group to the secondary hydroxyl group can be obtained by spectral analysis in a nuclear magnetic resonance device disclosed in [0018] of the document. Furthermore, the first-level hydroxyl density is adjusted to the above value by appropriately combining the techniques disclosed in Japanese Patent Publication No. 2013-181169, Japanese Patent Publication No. 2014-074175, Japanese Patent Publication No. 2019-026822, and Japanese Patent Publication No. 2011-007588.

In one embodiment of the present invention, the non-ionic surfactant may not be the polyglycerol alkyl ether comprising a glycerol structure and an alkyl group having more than 4 carbon atoms as described above, but may be polypropylene glycol, polyglycerol, polyglycerol alkyl ester, dextrin, dextrin derivatives, etc., and is particularly preferably polypropylene glycol.

In one embodiment of the present invention, the nonionic surfactant is a polyglycerol alkyl ether having a weight average molecular weight of 500 or more. If a polyglycerol alkyl ether having a weight average molecular weight of less than 500 is used, there is a concern that a film preventing the adhesion of defect-causing substances cannot be formed on the surface of the polishing object. According to this embodiment, the weight average molecular weight is preferably 750 or more, more preferably 1250 or more, and even more preferably 1500 or more. This embodiment has the technical effect of accelerating the adsorption rate of the defect-causing substances when forming the film preventing adhesion, and facilitating detachment during washing or cleaning.

According to this embodiment, the weight average molecular weight can be less than 2500. According to this embodiment, it is possible to adsorb on the surface of the polishing object to form a film to prevent the adhesion of defect-causing substances.

In one embodiment of the present invention, the polypropylene glycol can be a monool type, a diol type, a triol type, or a mixture thereof. Among them, the diol type is preferred. The diol type is also used in the embodiment.

Furthermore, if polyethylene glycol (PEG) is used instead of polypropylene glycol (PPG), there is a possibility that the surface roughness may be deteriorated.

In one embodiment of the present invention, the weight average molecular weight of the polypropylene glycol is preferably 200 or more, more preferably 300 or more, and even more preferably 400 or more. According to this embodiment, the expected effect of the present invention can be effectively exerted. According to one embodiment of the present invention, the weight average molecular weight of the polypropylene glycol is preferably 10000 or less, more preferably 5000 or less, and even more preferably 2000 or less. According to this embodiment, the solubility of the polypropylene glycol is improved, and the expected effect of the present invention can be effectively exerted.

In one embodiment of the present invention, the content of the nonionic surfactant is preferably 0.001 mass % or more, 0.005 mass % or more, 0.05 mass % or more, 0.08 mass % or more, 0.2 mass % or more, 0.4 mass % or more, 0.6 mass % or more, or 0.8 mass % or more, relative to the total mass of the polishing composition.

In one embodiment of the present invention, the content of the non-ionic surfactant is preferably 10% by mass or less, 8% by mass or less, 6% by mass or less, 4% by mass or less, 2% by mass or less, 1.9% by mass or less, 1.8% by mass or less, 1.7% by mass or less, 1.6% by mass or less, 1.5% by mass or less, 1.4% by mass or less, 1.3% by mass or less, 1.2% by mass or less, or 1.1% by mass or less. In this embodiment, when the non-ionic surfactant is a polyglycerol alkyl ether, the polyglycerol alkyl ether is 0.6% by mass or more or 0.8% by mass or more. Thereby, the number of defects in the polishing object containing oxygen-silicon bonds or the polishing object containing silicon-silicon bonds can be further reduced. In addition, the above description applies to the upper limit.

In one embodiment of the present invention, the weight average molecular weights of the first water-soluble polymer, the second water-soluble polymer, and the non-ionic surfactant are 3000 or more; 5000 or more; 200, 300, 400, or 500 or more, respectively. By using any one of the three compounds contained in the polishing composition of the present embodiment as a polymer having the above-mentioned lower limit molecular weight, it is easy to form a film to prevent the adhesion of defect-causing substances on the polishing object, and the technical effect of the desired effect of the present invention can be effectively exerted. In this form, the upper limit of the weight average molecular weight of the first water-soluble polymer, the second water-soluble polymer, and the non-ionic surfactant is applied as described above.

In one embodiment of the present invention, the non-ionic surfactant is not an amine-type non-ionic surfactant.

(Aqueous carrier) The polishing composition of one embodiment of the present invention usually includes an aqueous carrier. The aqueous carrier has the function of dispersing or dissolving the components. The aqueous carrier is preferably only water. In addition, the aqueous carrier can also be a mixed solvent of water and an organic solvent in order to disperse or dissolve the components.

From the viewpoint of preventing the contamination of the polishing object or the effects of other components, water is preferably water that contains as few impurities as possible. For example, water having a total transition metal ion content of 100 ppb or less is preferred. Here, the purity of the water can be improved by, for example, removing impurity ions using an ion exchange resin, removing foreign matter using a filter, or by distillation. Specifically, deionized water (ion exchange water), pure water, ultrapure water, distilled water, etc. are preferably used as water.

(Other additives) The polishing composition of one embodiment of the present invention may contain other additives in any proportion as needed within the scope that does not hinder the effect of the present invention. Examples of other additives include preservatives, dissolved gases, reducing agents, oxidizing agents, etc.

In one embodiment of the present invention, the polishing composition does not contain at least one selected from the group consisting of polyethylene glycol, polyoxyethylene nonylphenyl ether, polyglycerol and polyoxyethylene lauryl sulfate.

In one embodiment of the present invention, the polishing composition does not contain polyvinyl acetal.

In one embodiment of the present invention, the polishing composition does not contain a polymer containing constituent units derived from hydroxyethylacrylamide.

In one embodiment of the present invention, the polishing composition does not contain a modified polyvinyl alcohol-based polymer containing an alkoxy group.

In one embodiment of the present invention, the polishing composition does not contain a polymer containing constituent units derived from (meth)acrylamide. [Example]

The present invention will be further described in detail using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. In addition, unless otherwise specified, "%" and "parts" represent "mass %" and "mass parts", respectively. In addition, in the following examples, unless otherwise specified, the operation is carried out under the conditions of room temperature (25°C)/relative humidity 40~50%RH.

[Preparation of grinding composition] As shown in Table 1, abrasive particles (sulfonic acid fixed colloidal silica; average primary particle size: 35nm, average secondary particle size: 70nm, D90/D10: 1.7, aspect ratio: 1.2) are mixed with the first water-soluble polymer, the second water-soluble polymer, a surfactant, and a liquid carrier (pure water) to form the composition and pH shown in Table 1. For some examples and comparative examples, ammonia is appropriately added and stirred to prepare each grinding composition (mixing temperature: about 25°C, mixing time: about 10 minutes). In addition, the primary hydroxyl density of polyglycerol lauryl ether and polyglycerol lauryl ester used in the examples and comparative examples is 75%~85%. In addition, the saponification degrees of the polyvinyl alcohol and sulfonic acid-modified polyvinyl alcohol used in the Examples and Comparative Examples were 100% and 99%, respectively.

[Average primary particle size of abrasive grains] The average primary particle size of abrasive grains is calculated from the specific surface area of the abrasive grains and the density of the abrasive grains measured by the BET method using "Flow Sorb II2300" manufactured by MicroMetrics.

[Average secondary particle size of abrasive grains] The average secondary particle size of abrasive grains was calculated by the dynamic light scattering method using "UPA-UT151" manufactured by Microtrac.

[Aspect ratio of abrasive grains] The aspect ratio of abrasive grains is the average value of the aspect ratio (long diameter/short diameter) of 300 randomly selected abrasive grain images measured by FE-SEM.

[pH of polishing composition] The pH of the polishing composition was determined by using a glass electrode type hydrogen ion concentration indicator (manufactured by Horiba, Ltd., model: F-23) and a standard buffer (phthalate pH buffer pH: 4.01 (25°C), neutral phosphoric acid pH buffer pH: 6.86 (25°C), carbonate pH buffer pH: 10.01 (25°C)) for 3-point calibration. The glass electrode was then placed in the polishing composition and the value was measured after stabilization for more than 2 minutes. The results are shown in Table 1.

[Polishing Test] In each embodiment and comparative example, a silicon oxide film with a thickness of 1000Å, a silicon nitride film with a thickness of 1000Å, and a polysilicon film with a thickness of 1000Å formed on the surface of a silicon wafer (300mm, blank wafer) was used as each polishing object (represented as SiO ₂ , SiN, and Poly-Si in the table, respectively). The silicon oxide film was derived from TEOS (tetraethyl orthosilicate). Each polishing object was cut into a small piece (coupon) of a 60mm×60mm wafer as a test piece, and polished under the following conditions.

(Polishing device and polishing conditions) Polishing device: Polishing machine EJ-380IN-CH manufactured by Engis Co., Ltd., Japan Polishing pressure: 1.5psi (=10.3kPa) Polishing pad: Hard polyurethane polishing pad IC1010 manufactured by Nitta Haas Co., Ltd. Polishing platen rotation speed: 83rpm Carrier rotation speed: 77rpm Supply of polishing composition: Continuous flow Supply amount of polishing composition: 200ml/min Polishing time: 20 seconds

(Measurement of polishing speed) Measure the thickness of the test piece (film thickness) before and after polishing with an optical film thickness meter (ASET-f5x: manufactured by KLA TENCOR). Calculate the difference between the thickness of the test piece (film thickness) before and after polishing, divide it by the polishing time, and calculate the polishing speed (Å/min) by sorting units. The results are shown in the table below. Also, 1Å=0.1 nm.

(Determination of the number of defects) For the polished test piece, the number of defects larger than 0.13μm is measured. The number of defects is measured using the wafer defect inspection device SP-2 manufactured by KLA TENCOR. The measurement is performed on the remaining portion of the polished test piece except for the 5mm width portion from the outer edge of one side (when the outer edge is set to 0mm, the portion from 0mm to 5mm). The fewer the number of defects, the fewer the number of surface scratches, roughness, and residues, and the smaller the surface roughness.

(Measurement of surface roughness) The surface roughness (Ra) of the polished test piece was measured using a scanning probe microscope (SPM). As Ra, NANO-NAV12 manufactured by Hitachi High-Tech Co., Ltd. was used. The cantilever was SI-DF40P2. The measurement was performed 3 times at a scanning frequency of 0.86 Hz, X: 512 pt, Y: 512 pt, and the average value was set as the surface roughness (Ra). The scanning range of the SPM was a square area of "2μm×2μm".

Claims (19)

A polishing composition is used for polishing an object to be polished, the polishing composition comprising: abrasive grains having an organic acid fixed on the surface, a first water-soluble polymer having a sulfonic acid group or a salt thereof or a carboxyl group or a salt thereof, a second water-soluble polymer different from the first water-soluble polymer, a non-ionic surfactant, and an aqueous carrier; the content of the abrasive grains is more than 0.001 mass % and less than 30 mass %, the content of the first water-soluble polymer is 0.00 1 mass % to 10 mass %, the content of the second water-soluble polymer is 0.001 mass % to 10 mass %, the content of the non-ionic surfactant is 0.001 mass % to 10 mass %, the weight average molecular weight of the first water-soluble polymer is 1000 to 100,000, the weight average molecular weight of the second water-soluble polymer is 5000 to 60,000, and the first water-soluble polymer comprises a constituent unit represented by the following formula (1):

R ⁹ is a hydrogen atom or a methyl group, R ¹⁰ and R ¹¹ are each independently a hydrogen atom, -COOR ¹² or -G, but R ¹⁰ and R ¹¹ are not simultaneously hydrogen atoms, -G is a sulfonic acid group,

However, * indicates a bonding position, R ¹² , R ¹³ and R ¹⁵ are independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a hydroxyalkyl group having 1 to 12 carbon atoms or a relative cation, and R ¹⁴ is a divalent group; the second water-soluble polymer comprises a constituent unit represented by the following formula (2):

X is represented by:

R ¹ to R ⁶ are independently hydrogen or -J, -J is a hydroxyl group, a sulfonic acid group or a salt thereof,

However, * indicates a bonding position, and ^R7 and ^R8 are each independently a hydrogen atom or -E, and -E is represented by the following formula:

However, * indicates a bonding position, the aforementioned constituent unit includes at least one of -J and -E; the aforementioned non-ionic surfactant includes a polyglycerol alkyl ether having a glycerol structure and an alkyl group with more than 4 carbon atoms, or polypropylene glycol. If the pH of the grinding composition in claim 1 does not reach 9.0. For example, the pH of the grinding composition in claim 2 does not reach 7.0. If the pH of the grinding composition in claim 3 does not reach 5.0. A polishing composition as claimed in any one of claims 1 to 4, wherein the content of the aforementioned abrasive particles exceeds 0.01% by mass. A polishing composition as claimed in any one of claims 1 to 4, wherein the secondary average particle size of the aforementioned abrasive particles is less than 100 nm. A polishing composition as claimed in any one of claims 1 to 4, wherein at least one of the first water-soluble polymer and the second water-soluble polymer is a homopolymer. A polishing composition as claimed in any one of claims 1 to 4, wherein the carbon number of the alkyl group of the aforementioned polyglycerol alkyl ether is 10 or more. A polishing composition as claimed in any one of claims 1 to 4, wherein the primary hydroxyl density of the polyglycerol alkyl ether is 50% or more. A polishing composition as claimed in any one of claims 1 to 4, wherein the first water-soluble polymer is at least one selected from the group consisting of polystyrene sulfonic acid, a (co)polymer containing a constituent unit derived from polystyrene sulfonic acid in a part of its structure, a copolymer of sulfonic acid and carboxylic acid, sulfonated polysulfone, and polyaniline acid. A polishing composition as claimed in any one of claims 1 to 4, wherein the second water-soluble polymer is at least one selected from the group consisting of polyvinyl alcohol (PVA), a (co)polymer containing a constituent unit derived from polyvinyl alcohol (PVA) in a part of its structure, poly-N-vinyl acetamide, and a (co)polymer containing a constituent unit derived from poly-N-vinyl acetamide in a part of its structure. As in claim 11, the polishing composition, wherein the saponification degree of the aforementioned polyvinyl alcohol (PVA) or a (co)polymer containing constituent units derived from polyvinyl alcohol (PVA) in a part of its structure is 90% or more. The polishing composition of claim 1, wherein the second water-soluble polymer contains a sulfonic acid group or a salt thereof. A polishing composition as claimed in any one of claims 1 to 4, wherein the weight average molecular weight of the polyglycerol alkyl ether is 500 or more. A grinding composition as claimed in any one of claims 1 to 4, which is used for preparatory grinding. A polishing composition as claimed in any one of claims 1 to 4, wherein the polishing object comprises silicon-silicon bonds, nitrogen-silicon bonds or oxygen-silicon bonds. A polishing composition as claimed in any one of claims 1 to 4, wherein the weight average molecular weights of the first water-soluble polymer, the second water-soluble polymer and the non-ionic surfactant are respectively 3000 or more, 5000 or more and 200 or more. A method for polishing an object to be polished, comprising the step of polishing the object to be polished using a polishing composition as described in any one of claims 1 to 17. A manufacturing process for a semiconductor device, comprising a preliminary polishing step, a bulk polishing step and a polishing step, and using a polishing composition as described in any one of claims 1 to 17 as the polishing composition in the preliminary polishing step.