Polishing composition, polishing method, and method for manufacturing semiconductor substrates

Abstract

This invention provides a means to achieve a good polishing speed for objects containing silicon-based materials while reducing scratches on the surface of polished objects. [Solution] An abrasive composition comprising abrasive grains having a zeta potential of -5mV or less, a first polyoxyalkylene compound having a weight-average molecular weight of 100 to 900, and a second polyoxyalkylene compound having different oxyalkylene units from the first polyoxyalkylene compound and having a weight-average molecular weight of 100 to 900, wherein the pH is less than 7.

Description

[Technical Field]

[0001] The present invention relates to a polishing composition, a polishing method, and a method for manufacturing a semiconductor substrate. [Background technology]

[0002] In recent years, with the increasing use of multilayer wiring on semiconductor substrate surfaces, chemical mechanical polishing (CMP) technology, which physically polishes and flattens semiconductor substrates, has been utilized during device manufacturing. CMP is a method of flattening the surface of a workpiece (object to be polished), such as a semiconductor substrate, using a polishing composition (slurry) containing abrasive particles such as silica, alumina, and ceria, as well as corrosion inhibitors and surfactants. Workpieces to be polished include wiring, plugs, etc., made of silicon, polysilicon, silicon dioxide (SiO2), carbon-containing silicon dioxide (SiOC), silicon nitride (SiN), and metals.

[0003] For example, Patent Document 1 discloses an abrasive composition comprising silica with an organic acid immobilized on its surface and polyalkylene glycol, wherein the molecular weight distribution of the polyalkylene glycol, calculated by gel permeation chromatography (GPC) in terms of polyethylene glycol, has two or more peaks, at least one of the peaks in the molecular weight distribution has a peak top molecular weight of 1,000 to 6,000, at least one of the peaks has a peak top molecular weight of 100 to 800, the polyalkylene glycol contains polyethylene glycol, at least one of the peaks with a peak top molecular weight of 1,000 to 6,000 is derived from polyethylene glycol, and the pH is 3 to 6. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-56348 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, while the technology described in Patent Document 1 exhibits a good polishing speed for the workpiece, there was still room for improvement in terms of reducing surface defects in the polished workpiece.

[0006] Therefore, the present invention aims to provide a means that can achieve a good polishing speed for objects containing silicon-based materials while further reducing defects on the surface of polished objects. [Means for solving the problem]

[0007] The inventors diligently studied to solve the above problems. As a result, they found that the above problems can be solved by an abrasive composition comprising abrasive grains having a zeta potential of -5mV or less, a first polyoxyalkylene compound having a weight-average molecular weight of 100 to 900, and a second polyoxyalkylene compound having different oxyalkylene units from the first polyoxyalkylene compound and a weight-average molecular weight of 100 to 900, and having a pH of less than 7, and thus completed the present invention. [Effects of the Invention]

[0008] According to the present invention, a means can be provided that can achieve a good polishing speed for an object containing silicon-based material while reducing defects on the surface of the polished object. [Modes for carrying out the invention]

[0009] According to one embodiment of the present invention, an abrasive composition is provided comprising abrasive grains having a zeta potential of -5mV or less, a first polyoxyalkylene compound having a weight-average molecular weight of 100 to 900, and a second polyoxyalkylene compound having different oxyalkylene units from the first polyoxyalkylene compound and a weight-average molecular weight of 100 to 900, wherein the pH is less than 7.

[0010] According to the polishing composition of the present invention, it is possible to achieve a good polishing speed for objects containing silicon-based materials while reducing defects on the surface of the polished object.

[0011] The exact reason why the polishing composition of the present invention produces the above-mentioned effects is unknown, but it is thought to be due to the following mechanism. However, this mechanism is speculative, and the technical scope of the present invention is not limited by this mechanism.

[0012] The polishing composition of the present invention comprises a first polyoxyalkylene compound and a second polyoxyalkylene compound having different oxyalkylene units than the first polyoxyalkylene compound. These two types of polyoxyalkylene compounds have different hydrophilicities. If the hydrophilicity of the first polyoxyalkylene compound is higher than that of the second polyoxyalkylene compound, the second polyoxyalkylene compound, which has low hydrophilicity (high hydrophobicity), will adsorb to the residue (especially organic residue) on the surface of the object to be polished. However, because the residue to which the second polyoxyalkylene compound has adsorbed is highly hydrophobic, it becomes difficult to disperse in the dispersion medium (especially water) of the polishing composition. The first polyoxyalkylene compound, which has high hydrophilicity (low hydrophobicity), can further adsorb to the residue to which the second polyoxyalkylene compound has adsorbed, thereby increasing the hydrophilicity of the residue. As a result, the residue on the surface of the object to be polished becomes easier to disperse in the dispersion medium, and it is believed that this can reduce residue and defects such as scratches on the object to be polished.

[0013] The embodiments of the present invention will be described in detail below, but the present invention is not limited to the embodiments described below and can be modified in various ways within the scope of the claims. The embodiments described herein can be combined in any way to form other embodiments. Unless otherwise specified herein, operations and measurements of physical properties, etc., are performed under conditions of room temperature (20°C to 25°C) and relative humidity of 40% RH to 50% RH.

[0014] In this specification, "X or greater and Y or less" is used to mean that the numerical values ​​(X and Y) described before and after it are included as the lower and upper limits. When "X or greater and Y or less" is described multiple times, for example, "X1 or greater and Y1 or less, or X2 or greater and Y2 or less," the disclosure of each numerical value as the upper limit, the disclosure of each numerical value as the lower limit, and all combinations of those upper and lower limits are disclosed (i.e., they provide a lawful basis for correction). Specifically, corrections to X1 or greater, corrections to Y2 or less, corrections to X1 or less, corrections to Y2 or greater, corrections to X1 or greater and X2 or less, corrections to X1 or greater and Y2 or less, etc., must all be considered lawful.

[0015] The content (concentration) described herein may be the content (concentration) at the point of use (POU), or the concentration before dilution to the POU content (concentration).

[0016] The terms "first" and "second" as used herein are merely used for convenience to distinguish between two types of polyoxyalkylene compounds, and the order of "first" and "second" itself has no particular significance.

[0017] In this specification, "defect" refers to a general term for foreign matter (especially organic residue) adhering to the surface of a polished object, or scratches (such as dents) on the surface of a polished object.

[0018] [Abrasive grains] The polishing composition according to the present invention contains abrasive grains. These abrasive grains have the effect of mechanically polishing the object to be polished, thereby improving the polishing speed of the object to be polished by the polishing composition.

[0019] In the polishing composition of the present invention, the abrasive grains have a zeta potential of -5 mV or less. Here, the "zeta (ζ) potential" refers to the potential difference generated at the interface between a solid and a liquid in contact with each other when they perform relative movement. When the zeta potential of the abrasive grains exceeds -5 mV, the defects on the surface of the polished object to be polished (particularly silicon oxide) increase.

[0020] In the present invention, the zeta potential of the abrasive grains is preferably -60 mV or more and -10 mV or less, more preferably -50 mV or more and -10 mV or less, still more preferably -40 mV or more and -15 mV or less, and particularly preferably more than -35 mV and -15 mV or less. When the abrasive grains have a zeta potential within such a range, the polishing rate of the object to be polished can be further improved. Here, the zeta potential of the abrasive grains in the polishing composition is a value measured by the method described in the examples. Further, the zeta potential of the abrasive grains can be adjusted by the amount of anionic groups (particularly organic acid groups) possessed by the abrasive grains described below, the pH of the polishing composition, and the like.

[0021] The type of the abrasive grains is not particularly limited, and examples thereof include metal oxides such as silica, alumina, zirconia, and titania. The abrasive grains can be used alone or in combination of two or more. Commercially available products or synthetic products can be used for the abrasive grains.

[0022] The type of the abrasive grains is preferably silica, and more preferably colloidal silica. Examples of the production method of colloidal silica include the sodium silicate method and the sol-gel method, and colloidal silica produced by any production method can be suitably used as the abrasive grains of the present invention. However, from the viewpoint of reducing metal impurities, colloidal silica produced by the sol-gel method that can be produced with high purity is preferable.

[0023] Colloidal silica can be produced by the sol-gel method using conventionally known techniques. Specifically, colloidal silica can be obtained by using a hydrolyzable silicon compound (e.g., alkoxysilane or its derivatives) as a raw material and carrying out a hydrolysis-condensation reaction.

[0024] In some embodiments of the present invention, the abrasive particles contained in the polishing composition are preferably anion-modified silica, and more preferably anion-modified colloidal silica. The abrasive particles are even more preferably colloidal silica with an organic acid immobilized on its surface. Colloidal silica with an organic acid immobilized on its surface tends to have a larger absolute value of zeta potential in the polishing composition compared to ordinary colloidal silica without an immobilized organic acid. Therefore, it is easier to adjust the zeta potential of the colloidal silica in the polishing composition to -5mV or less.

[0025] As colloidal silica with organic acids immobilized on its surface, colloidal silica with organic acid groups such as carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, and aluminic acid groups immobilized on its surface is preferred. Of these, colloidal silica with sulfonic acid or carboxylic acid immobilized on its surface is preferred from the viewpoint of ease of production, and colloidal silica with sulfonic acid immobilized on its surface is more preferred.

[0026] Immobilizing organic acids onto the surface of colloidal silica cannot be achieved simply by having colloidal silica and organic acids coexist. For example, if one wants to immobilize sulfonic acid, a type of organic acid, onto colloidal silica, this can be done by the method described in, for example, “Sulfonic acid-functionalized silica through quantitative oxidation of thiol groups”, Chem. Commun. 246-247 (2003). Specifically, by coupling a silane coupling agent having a thiol group, such as 3-mercaptopropyltrimethoxysilane, to colloidal silica and then oxidizing the thiol group with hydrogen peroxide, colloidal silica with sulfonic acid immobilized on its surface (sulfonic acid-modified colloidal silica) can be obtained.

[0027] Alternatively, if immobilizing a carboxylic acid, a type of organic acid, onto colloidal silica, this can be done, for example, by the method described in “Novel Silane Coupling Agents Containing a Photolabile 2-Nitrobenzyl Ester for Introduction of a Carboxy Group on the Surface of Silica Gel”, Chemistry Letters, 3, 228-229 (2000). Specifically, by coupling a silane coupling agent containing a photoreactive 2-nitrobenzyl ester onto colloidal silica and then irradiating it with light, colloidal silica with a carboxylic acid immobilized on its surface (carboxylic acid-modified colloidal silica) can be obtained.

[0028] The shape of the abrasive grains is not particularly limited and may be spherical or non-spherical. Specific examples of non-spherical shapes include polygonal prisms such as triangular or square prisms, cylindrical shapes, cylindrical shapes with a bulge in the center, donut shapes with a hole in the center, plate shapes, so-called cocoon shapes with a constriction in the center, so-called aggregate spherical shapes where multiple particles are integrated, so-called konpeito shapes with multiple protrusions on the surface, rugby ball shapes, and many other shapes, and are not particularly limited.

[0029] The size of the abrasive grains is not particularly limited. For example, the average primary particle diameter of the abrasive grains is preferably 5 nm or more, more preferably 8 nm or more, even more preferably 10 nm or more, and particularly preferably 12 nm or more. As the average primary particle diameter of the abrasive grains increases, the polishing speed of the object to be polished by the polishing composition improves. Also, the average primary particle diameter of the abrasive grains is preferably 100 nm or less, more preferably 80 nm or less, even more preferably 60 nm or less, and particularly preferably 50 nm or less. As the average primary particle diameter of the abrasive grains decreases, it becomes easier to obtain a surface with fewer defects by polishing with the polishing composition. That is, the average primary particle diameter of the abrasive grains is preferably 5 nm or more and 100 nm or less, more preferably 8 nm or more and 80 nm or less, even more preferably 10 nm or more and 60 nm or less, and particularly preferably 12 nm or more and 50 nm or less. The average primary particle diameter of the abrasive grains can be calculated, for example, based on the specific surface area (SA) of the abrasive grains calculated from the BET method, assuming that the shape of the abrasive grains is a perfect sphere. In this specification, the average primary particle size of the abrasive grains is the value measured by the method described in the Examples.

[0030] Furthermore, the average secondary particle diameter of the abrasive grains is preferably 10 nm or more, more preferably 15 nm or more, even more preferably 20 nm or more, and particularly preferably 25 nm or more. As the average secondary particle diameter of the abrasive grains increases, the resistance during polishing decreases, and stable polishing becomes possible. Furthermore, the average secondary particle diameter of the abrasive grains is preferably 400 nm or less, more preferably 300 nm or less, even more preferably 200 nm or less, and particularly preferably 100 nm or less. As the average secondary particle diameter of the abrasive grains decreases, the surface area per unit mass of the abrasive grains increases, the frequency of contact with the workpiece improves, and the polishing speed improves further. That is, the average secondary particle diameter of the abrasive grains is preferably 10 nm or more and 400 nm or less, more preferably 15 nm or more and 300 nm or less, even more preferably 20 nm or more and 200 nm or less, and particularly preferably 25 nm or more and 100 nm or less. In this specification, the average secondary particle diameter of the abrasive grains is the value measured by the method described in the examples.

[0031] The average degree of abrasive particle aggregation is preferably 5.0 or less, more preferably 4.0 or less, even more preferably 3.0 or less, and particularly preferably 2.5 or less. As the average degree of abrasive particle aggregation decreases, defects can be reduced more effectively. The average degree of abrasive particle aggregation is also preferably 1.0 or more, more preferably 1.5 or more, and even more preferably 2.0 or more. This average degree of aggregation is obtained by dividing the average secondary particle diameter of the abrasive particle by the average primary particle diameter. As the average degree of abrasive particle aggregation increases, there is the advantageous effect of improving the polishing speed of the object being polished by the polishing composition.

[0032] The upper limit of the aspect ratio of abrasive grains in the polishing composition is not particularly limited, but it is preferably less than 2.0, more preferably 1.8 or less, and even more preferably 1.5 or less. Within this range, defects on the surface of the object to be polished can be further reduced. The aspect ratio is the average of the values ​​obtained by taking the smallest rectangle that circumscribes the image of the abrasive grains using a scanning electron microscope and dividing the length of the longer side of that rectangle by the length of the shorter side of the same rectangle, and can be determined using general image analysis software. The lower limit of the aspect ratio of abrasive grains in the polishing composition is not particularly limited, but it is preferably 1.0 or more, and more preferably 1.2 or more.

[0033] In the particle size distribution determined by laser diffraction scattering of abrasive grains, the lower limit of D90 / D10, which is the ratio of the particle diameter (D90) when the cumulative particle mass from the fine particles reaches 90% of the total particle mass to the particle diameter (D10) when the cumulative particle mass from the fine particles reaches 10% of the total particle mass, is not particularly limited, but is preferably 1.1 or higher, more preferably 1.4 or higher, even more preferably 1.7 or higher, and most preferably 2.0 or higher. Furthermore, in the particle size distribution determined by laser diffraction scattering of abrasive grains in a polishing composition, the upper limit of the ratio D90 / D10, which is the ratio of the particle diameter (D90) when the cumulative particle mass from the fine particles reaches 90% of the total particle mass to the particle diameter (D10) when the cumulative particle mass from the fine particles reaches 10% of the total particle mass, is not particularly limited, but is preferably 3.0 or lower, and more preferably 2.5 or lower. Within this range, defects on the surface of the object to be polished can be further reduced.

[0034] The size of the abrasive grains (average primary particle diameter, average secondary particle diameter, aspect ratio, D90 / D10, etc.) can be appropriately controlled by selecting the manufacturing method for the abrasive grains.

[0035] The abrasive content (concentration) is not particularly limited, but is preferably 0.5% by mass or more, more preferably 0.8% by mass or more, even more preferably 1% by mass or more, even more preferably greater than 1% by mass, and particularly preferably 1.5% by mass or more, relative to the total mass of the polishing composition. Furthermore, the upper limit of the abrasive content (concentration) is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and particularly preferably 5% by mass or less, relative to the total mass of the polishing composition. In other words, the abrasive content (concentration) is preferably 0.5% by mass or more and 20% by mass or less, more preferably 0.8% by mass or more and 20% by mass or less, even more preferably 1% by mass or more and 15% by mass or less, even more preferably greater than 1% by mass and 10% by mass or less, and particularly preferably 1.5% by mass or more and 5% by mass or less, relative to the total mass of the polishing composition. Within this range, the polishing speed can be improved while keeping costs down. Furthermore, if the abrasive composition contains two or more types of abrasive grains, the abrasive grain content (concentration) refers to the total amount of these grains.

[0036] [Polyoxyalkylene compounds] The polishing composition according to the present invention comprises a first polyoxyalkylene compound having a weight-average molecular weight of 100 to 900, and a second polyoxyalkylene compound having different oxyalkylene units from the first polyoxyalkylene compound and having a weight-average molecular weight of 100 to 900.

[0037] Here, the "different oxyalkylene units" of the second polyoxyalkylene compound are, compared to the oxyalkylene units of the first polyoxyalkylene compound, (1) The number of carbon atoms in the alkylene portion is different. (2) The structure of the alkylene portion is different (e.g., linear structure, branched structure) (3) The number of different types of oxyalkylene units is different (for example, the first polyoxyalkylene compound has only one type of oxyalkylene unit, while the second polyoxyalkylene compound has two or more types of oxyalkylene units). (4) When the first and second polyoxyalkylene compounds both have two or more oxyalkylene units, the arrangement of the oxyalkylene units is different (e.g., blocky, random, alternating, periodic, etc.) A second polyoxyalkylene compound is defined as having different oxyalkylene units from the first polyoxyalkylene compound if it satisfies at least one of the following conditions. It is preferable that at least condition (1) above is satisfied, from the viewpoint that the first polyoxyalkylene compound and the second polyoxyalkylene compound can more easily have different hydrophilicities from each other.

[0038] The weight-average molecular weight (Mw) of the first polyoxyalkylene compound and the second polyoxyalkylene compound is between 100 and 900. For example, if the hydrophilicity of the first polyoxyalkylene compound is higher than that of the second polyoxyalkylene compound, when the weight-average molecular weight of the first polyoxyalkylene compound is less than 100, the residue cannot be sufficiently hydrophilized, and as a result, surface defects on the polished object cannot be sufficiently reduced. On the other hand, if the weight-average molecular weight of the first polyoxyalkylene compound exceeds 900, the polishing speed of silicon-containing materials (especially polysilicon) may decrease. Furthermore, if the weight-average molecular weight of the second polyoxyalkylene compound is less than 100, it becomes difficult to adsorb to the residue, and even when combined with the first polyoxyalkylene compound, surface defects on the polished object cannot be sufficiently reduced. On the other hand, if the weight-average molecular weight of the second polyoxyalkylene compound exceeds 900, there is a risk that the polishing speed of silicon-containing materials (especially polysilicon) will decrease, and the second polyoxyalkylene compound itself will become a residue, increasing the number of defects on the surface of the polished object.

[0039] The weight-average molecular weight (Mw) of the first polyoxyalkylene compound and the second polyoxyalkylene compound is preferably 150 or more, but may be 200 or more, 250 or more, 300 or more, 350 or more, or 400 or more. The weight-average molecular weight (Mw) of the first polyoxyalkylene compound and the second polyoxyalkylene compound is preferably 850 or less, but may be 800 or less, 750 or less, 700 or less, 650 or less, 600 or less, 550 or less, 500 or less, 450 or less, 400 or less, or less than 400.

[0040] The weight-average molecular weight (Mw) of the first polyoxyalkylene compound and the second polyoxyalkylene compound can be measured as a value converted to polyethylene glycol using gel permeation chromatography (GPC), and specifically, they can be measured by the method described in the examples.

[0041] The content (concentration) of the first polyoxyalkylene compound and the second polyoxyalkylene compound in the polishing composition according to the present invention is not particularly limited, but it is preferably 50 ppm (0.005%) or more by mass of each compound independently, relative to the total mass of the polishing composition, and may be 100 ppm (0.01%) or more by mass, 150 ppm (0.015%) or more by mass, 200 ppm (0.02%) or more by mass, 250 ppm (0.025%) or more by mass, 300 ppm (0.03%) or more by mass, 400 ppm (0.04%) or more by mass, 500 ppm (0.05%) or more by mass, 600 ppm (0.06%) or more by mass, 700 ppm (0.01%) or more by mass, 800 ppm (0.08%) or more by mass, 900 ppm (0.09%) or more by mass, or 1000 ppm (0.1%) or more by mass. Furthermore, the content (concentration) of the first polyoxyalkylene compound and the second polyoxyalkylene compound in the polishing composition according to the present invention is not particularly limited, but it is preferable that each is independently 5000 ppm (0.5% by mass) or less with respect to the total mass of the polishing composition, and may be 4500 ppm (0.45% by mass) or less, 4000 ppm (0.4% by mass) or less, 3500 ppm (0.35% by mass) or less, 3000 ppm (0.3% by mass) or less, 2500 ppm (0.25% by mass) or less, 2000 ppm (0.2% by mass) or less, 1500 ppm (0.15% by mass) or less, 1000 ppm (0.1% by mass) or less, or less than 1000 ppm (0.1% by mass).

[0042] In some embodiments, the content (concentration) of the first polyoxyalkylene compound in the polishing composition according to the present invention is preferably 200 ppm (0.02% by mass) or more and 4000 ppm (0.4% by mass) or less, more preferably 600 ppm (0.01% by mass) or more and 3500 ppm (0.35% by mass) or less, even more preferably 800 ppm (0.08% by mass) or more and 3000 ppm (0.3% by mass) or less, and particularly preferably 1000 ppm (0.1% by mass) or more and 3000 ppm (0.3% by mass) or less, based on the total mass of the polishing composition. Furthermore, according to some embodiments, the content (concentration) of the second polyoxyalkylene compound is preferably 100 ppm (0.01% by mass) or more and 2000 ppm (0.2% by mass) or less, more preferably 150 ppm (0.015% by mass) or more and 1500 ppm (0.15% by mass) or less, even more preferably 200 ppm (0.02% by mass) or more and 1000 ppm (0.1% by mass) or less, and particularly preferably 200 ppm (0.02% by mass) or more and less than 1000 ppm (0.1% by mass), based on the total mass of the polishing composition.

[0043] In some embodiments, from the viewpoint of easily allowing them to have different hydrophilicities, it is preferable that the weight-average molecular weight of the first polyoxyalkylene compound is lower than that of the second polyoxyalkylene compound. Generally, with such a relationship of weight-average molecular weights, the hydrophilicity of the first polyoxyalkylene compound will be higher than that of the second polyoxyalkylene compound, and the effects of the present invention will be more easily exhibited. Furthermore, in this embodiment, it is preferable that the content of the first polyoxyalkylene compound in the polishing composition is greater than the content of the second polyoxyalkylene compound in the polishing composition. If the weight-average molecular weights and content of the first polyoxyalkylene compound and the second polyoxyalkylene compound are as described above, the hydrophilicity of the first polyoxyalkylene compound may be even higher than that of the second polyoxyalkylene compound. As a result, the residue on the surface of the polished object becomes more hydrophilic, and defects are further reduced.

[0044] A more preferred configuration of the weight-average molecular weight and content relationship between the first polyoxyalkylene compound and the second polyoxyalkylene compound is as follows: (i) Weight average molecular weight Weight-average molecular weight of the first polyoxyalkylene compound: 200 or more and less than 400 Weight-average molecular weight of the second polyoxyalkylene compound: 400 to 800 (ii) Content in the abrasive composition Content of the first polyoxyalkylene compound: 1000 ppm by mass or more and 3000 ppm by mass or less Content of the second polyoxyalkylene compound: 200 ppm by mass or more and less than 1000 ppm by mass Content of the first polyoxyalkylene compound > Content of the second polyoxyalkylene compound Regarding the content in the polishing composition described in (ii) above, if the content of the first polyoxyalkylene compound is greater than the content of the second polyoxyalkylene compound, the first polyoxyalkylene compound is more easily adsorbed by the residue, the residue can be sufficiently hydrophilized, and defects on the surface of the polished object can be further reduced.

[0045] Specific examples of the first polyoxyalkylene compound include, for example, polyethylene glycol, polypropylene glycol, polytrimethylene glycol, polytetramethylene glycol, polypentamethylene glycol, polyhexamethylene glycol, polyethylene glycol-polypropylene glycol random copolymer, polyethylene glycol-polytetramethylene glycol random copolymer, polypropylene glycol-polytetramethylene glycol random copolymer, polyethylene glycol-polypropylene glycol-polytetramethylene glycol random copolymer, polyethylene glycol-polypropylene glycol block copolymer, polypropylene glycol-polypropylene glycol-polypropylene glycol triblock copolymer, polyethylene glycol-polypropylene glycol-polypropylene glycol triblock copolymer, and the like.

[0046] Specific examples of the second polyoxyalkylene compound include compounds similar to the first polyoxyalkylene compound described above. However, in this invention, the second polyoxyalkylene compound has different oxyalkylene units than the first polyoxyalkylene compound.

[0047] In a preferred embodiment, the first polyoxyalkylene compound is polyethylene glycol, and the second polyoxyalkylene compound is polypropylene glycol.

[0048] [pH and pH adjusters] The pH of the polishing composition according to the present invention is less than 7. If the pH of the polishing composition is 7 or higher, the polishing speed of the object to be polished containing silicon-containing material (particularly silicon nitride) will decrease. The pH is preferably 6.0 or lower, more preferably 5.0 or lower, and even more preferably 3.5 or lower. Furthermore, the pH is preferably 1.0 or higher, more preferably 1.5 or higher, and even more preferably 2.0 or higher. In other words, the pH of the polishing composition according to the present invention is preferably 1.0 or higher and 6.0 or lower, more preferably 1.5 or higher and 5.0 or lower, and even more preferably 2.0 or higher and 3.5 or lower.

[0049] The polishing composition according to the present invention may contain a pH adjusting agent for adjusting the pH. The pH adjusting agent may be either an acid or a base, and may be either an inorganic compound or an organic compound. The pH adjusting agent may be used alone or in combination of two or more.

[0050] Specific examples of acids that can be used as pH adjusters include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, and phosphoric acid; and organic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, lactic acid, diglycolic acid, 2-furanic acid, 2,5-franic acid, 3-furanic acid, 2-tetrahydrofuranic acid, methoxyacetic acid, methoxyphenylacetic acid, and phenoxyacetic acid.

[0051] Examples of bases that can be used as pH adjusters include amines such as aliphatic amines and aromatic amines, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides, and ammonia.

[0052] The amount of pH adjuster added is not particularly limited and can be adjusted as appropriate so that the polishing composition reaches the desired pH. The pH of the polishing composition can be measured, for example, by a pH meter, and specifically by the method described in the examples.

[0053] Furthermore, the inorganic salts and organic onium salts described below may also serve as pH adjusters.

[0054] [Water-soluble polymers other than polyoxyalkylene compounds] The polishing composition according to the present invention preferably further contains a water-soluble polymer other than the polyoxyalkylene compound described above (hereinafter also simply referred to as "other water-soluble polymer"). This other water-soluble polymer readily adsorbs to the surface of the object to be polished and plays a role in protecting the surface of the object to be polished. As a result, when polishing is performed using a polishing composition containing other water-soluble polymers, the number of defects on the surface of the polished object can be further reduced.

[0055] The term "water-soluble polymer" as used herein refers to a water-soluble polymer having identical repeating units (homopolymer) or a water-soluble polymer having different repeating units (copolymer), and is typically a compound with a weight-average molecular weight (Mw) of 100 or more. There are no particular restrictions on the type of polymer used as the other water-soluble polymer; anionic, cationic, nonionic, and amphoteric polymers are all acceptable. Furthermore, when the other water-soluble polymer is a copolymer, the copolymer may take the form of a block copolymer, random copolymer, graft copolymer, alternating copolymer, or periodic copolymer.

[0056] Examples of anionic water-soluble polymers include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polymethallyl sulfonic acid, poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, polyacrylic acid, and polymethacrylic acid.

[0057] Examples of cationic water-soluble polymers include polyethyleneimine (PEI), polyvinylamine, polyallylamine, polyvinylpyridine, and polymers of cationic acrylamide. A specific example of polyallylamine is polydiallyldimethylammonium chloride.

[0058] Examples of nonionic water-soluble polymers include, for example, polyvinyl alcohol, ethylene-vinyl alcohol copolymers, polyvinylpyrrolidone, polyacrylamide, poly-N-vinylacetamide, polyamine compounds, polyvinyl ether compounds (polyvinyl methyl ether, polyvinyl ethyl ether, polyvinyl isobutyl ether, etc.), polyglycerin, water-soluble cellulose (hydroxyethylcellulose (HEC), hydroxypropylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, methylcellulose, ethylcellulose, ethylhydroxyethylcellulose) and other polysaccharides, alginic acid polyhydric alcohol esters, water-soluble urea resins, dextrin derivatives, and water-soluble polymers other than polyoxyalkylene compounds such as casein. Furthermore, not only those having such a main chain structure, but also graft copolymers having a nonionic polymer structure in the side chain can be suitably used.

[0059] Examples of amphoteric water-soluble polymers include copolymers of vinyl monomers having anionic groups and vinyl monomers having cationic groups, and vinyl-based amphoteric polymers having carboxybetaine groups or sulfobetaine groups. Specifically, examples include acrylic acid / dimethylaminoethyl methacrylic acid copolymers and acrylic acid / diethylaminoethyl methacrylic acid copolymers.

[0060] Furthermore, copolymers of water-soluble polymers as exemplified above can also be used.

[0061] These other water-soluble polymers can be used individually or in combination of two or more. Furthermore, the other water-soluble polymers may be commercially available or synthesized.

[0062] Among these other water-soluble polymers, nonionic water-soluble polymers are preferred, and polyvinyl alcohol is more preferred, from the viewpoint of being able to further reduce surface defects on polished objects (especially silicon dioxide).

[0063] The weight-average molecular weight (Mw) of other water-soluble polymers can be appropriately set depending on their type. Generally, the lower limit of the weight-average molecular weight (Mw) of other water-soluble polymers is preferably 100 or more, and may be 200 or more, 300 or more, 400 or more, 500 or more, 600 or more, 800 or more, 1,000 or more, 1,500 or more, 2,000 or more, 3,000 or more, 4,000 or more, or 5,000 or more. The upper limit of the weight-average molecular weight (Mw) of other water-soluble polymers is preferably 500,000 or less, and may be 100,000 or less, 50,000 or less, 30,000 or less, 20,000 or less, 10,000 or less, 8,000 or less, 5,000 or less, 3,000 or less, 2,000 or less, 1,000 or less, or 800 or less.

[0064] For example, the weight-average molecular weight (Mw) of other water-soluble polymers may be between 1,000 and 100,000, between 1,500 and 50,000, between 2,000 and 20,000, between 300 and 20,000, or between 5,000 and 20,000. Another example is that the weight-average molecular weight (Mw) of other water-soluble polymers may be between 100 and 2,000, between 200 and 2,000, between 200 and 1,000, or between 300 and 800.

[0065] For example, if the other water-soluble polymer is polyvinyl alcohol, the lower limit of the weight-average molecular weight (Mw) of the polyvinyl alcohol may be 1,000 or more, 1,500 or more, 2,000 or more, 3,000 or more, or 5,000 or more. The upper limit of the weight-average molecular weight (Mw) of the polyvinyl alcohol may be 100,000 or less, 50,000 or less, or 20,000 or less. In other words, the weight-average molecular weight (Mw) of polyvinyl alcohol may be 1,000 to 100,000, 1,500 to 50,000, 2,000 to 20,000, 3,000 to 20,000, or 5,000 to 20,000.

[0066] The weight-average molecular weight (Mw) of other water-soluble polymers can be measured in the same manner as the weight-average molecular weight (Mw) of the first polyoxyalkylene compound and the second polyoxyalkylene compound, specifically by the method described in the examples.

[0067] The content (concentration) of other water-soluble polymers in the polishing composition is preferably 100 ppm (0.01% by mass) or more, more preferably 200 ppm (0.02% by mass) or more, even more preferably 400 ppm (0.04% by mass) or more, even more preferably 600 ppm (0.06% by mass) or more, and particularly preferably 800 ppm (0.08% by mass) or more, relative to the total mass of the polishing composition. Furthermore, the upper limit of the content (concentration) of other water-soluble polymers in the polishing composition is preferably 10,000 ppm (1% by mass) or less, more preferably 8,000 ppm (0.8% by mass) or less, even more preferably 6,000 ppm (0.6% by mass) or less, even more preferably 5,000 ppm (0.5% by mass) or less, and particularly preferably 4,000 ppm (0.4% by mass) or less, relative to the total mass of the polishing composition.

[0068] In other words, the content (concentration) of other water-soluble polymers in the polishing composition is preferably 100 ppm (0.01% by mass) or more and 10,000 ppm (1% by mass) or less, more preferably 200 ppm (0.02% by mass) or more and 8,000 ppm (0.8% by mass) or less, even more preferably 400 ppm (0.04% by mass) or more and 6,000 ppm (0.6% by mass) or less, even more preferably 600 ppm (0.06% by mass) or more and 5,000 ppm (0.5% by mass) or less, and particularly preferably 800 ppm (0.08% by mass) or more and 4,000 ppm (0.4% by mass) or less.

[0069] Furthermore, if the polishing composition contains two or more other water-soluble polymers, the content (concentration) of the other water-soluble polymers refers to their total amount.

[0070] [Inorganic salts] The polishing composition according to the present invention preferably further contains an inorganic salt. The inorganic salt has the function of further reducing defects on the surface of the polished object (particularly silicon dioxide). In addition, the inorganic salt has the function of increasing the electrical conductivity of the polishing composition, thereby further improving the polishing speed of the object to be polished.

[0071] Examples of inorganic salts include those composed of the following cations and anions. Examples of cations include alkali metal ions such as lithium ions, sodium ions, and potassium ions; alkaline earth metal ions such as magnesium ions, calcium ions, and strontium ions; polyatomic ions such as ammonium ions; and complex ions. Examples of anions include halide ions (fluoride ions, chloride ions, bromide ions, iodide ions, etc.), oxoate ions (borate ions, carbonate ions, nitrate ions, nitrite ions, metasilicate ions, phosphate ions, monohydrogen phosphate ions, dihydrogen phosphate ions, phosphonate ions, monohydrogen phosphonate ions, phosphinate ions, sulfate ions, sulfonate ions, sulfite ions, thiosulfate ions, chromate ions, dichromate ions, permanganate ions, etc.), thiocyanate ions, cyanate ions, and sulfamate ions.

[0072] More specific examples of inorganic salts include lithium salts such as lithium chloride, lithium bromide, lithium carbonate, lithium nitrate, and lithium thiocyanate; calcium salts such as calcium chloride, calcium bromide, calcium carbonate, calcium nitrate, and calcium thiocyanate; iron salts such as iron nitrate and iron thiocyanate; potassium salts such as potassium chloride, potassium bromide, potassium nitrate, potassium sulfate, potassium thiocyanate, potassium sulfamate, potassium phosphate, potassium dihydrogen phosphate, potassium monohydrogen phosphate, and potassium monohydrogen phosphonate; sodium salts such as sodium chloride, sodium bromide, sodium nitrate, sodium sulfate, and sodium thiocyanate; zinc salts such as zinc chloride, zinc nitrate, and zinc thiocyanate; magnesium salts such as magnesium nitrate, magnesium sulfate, and magnesium thiocyanate; strontium salts such as strontium nitrate and strontium thiocyanate; and ammonium salts such as ammonium chloride, ammonium bromide, ammonium iodide, ammonium nitrate, ammonium phosphate, ammonium dihydrogen phosphate, ammonium monohydrogen phosphate, ammonium phosphonate, ammonium monohydrogen phosphonate, ammonium sulfate, ammonium thiocyanate, and ammonium sulfamate. These inorganic salts can be used individually or in combination of two or more. Furthermore, the inorganic salts may be commercially available or synthesized.

[0073] Among these, from the viewpoint of better demonstrating the effects of the present invention, it is preferable that the inorganic acid is at least one of an ammonium salt of an inorganic acid and a potassium salt of an inorganic acid. The inorganic acid is preferably sulfuric acid, nitric acid, or carbonic acid. Therefore, the inorganic salt is more preferably at least one selected from the group consisting of ammonium sulfate, ammonium nitrate, ammonium carbonate, potassium sulfate, potassium nitrate, and potassium carbonate, and ammonium sulfate is even more preferable.

[0074] The content (concentration) of inorganic salts in the polishing composition is not particularly limited, but is preferably 100 ppm (0.01%) or more, more preferably 300 ppm (0.03%) or more, even more preferably 500 ppm (0.05%) or more, and particularly preferably 1000 ppm (0.1%) or more, relative to the total mass of the polishing composition. Furthermore, the upper limit of the content (concentration) of inorganic salts in the polishing composition is preferably 20,000 ppm (2.0%) or less, more preferably 10,000 ppm (1.0%) or less, even more preferably 8,000 ppm (0.8%) or less, and particularly preferably 6,000 ppm (0.6%) or less, relative to the total mass of the polishing composition.

[0075] In other words, the inorganic salt content (concentration) is preferably 100 ppm (0.01% by mass) or more and 20,000 ppm (2.0% by mass) or less relative to the total mass of the polishing composition, more preferably 300 ppm (0.03% by mass) or more and 10,000 ppm (1.0% by mass) or less, even more preferably 500 ppm (0.05% by mass) or more and 8,000 ppm (0.8% by mass) or less, and particularly preferably 1,000 ppm (0.1% by mass) or more and 6,000 ppm (0.6% by mass) or less.

[0076] Furthermore, if the abrasive composition contains two or more inorganic salts, the inorganic salt content (concentration) refers to the total amount of these salts.

[0077] [Organic Onium Salt] The polishing composition according to the present invention preferably further contains an organic onium salt. The organic onium salt has the function of further reducing defects on the surface of the polished object (particularly silicon dioxide).

[0078] The organic onium salt used in the present invention is preferably at least one of a tetraalkylammonium salt represented by the following chemical formula 1 and a tetraalkylphosphonium salt represented by the following chemical formula 2.

[0079] [Chemical formula]

[0080] In the above Chemical formula 1 and Chemical formula 2, R 1 ~R 8 are each independently an unsubstituted alkyl group having 1 to 4 carbon atoms, A - and X - are each independently a monovalent anion.

[0081] When using an organic onium salt having an alkyl group with 5 or more carbon atoms, defects on the surface of the polished object to be polished may increase.

[0082] The R in the above Chemical formula 1 and Chemical formula 2 1 ~R 8 Specific examples of the unsubstituted alkyl group having 1 to 4 carbon atoms used therein include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, tert-butyl group. From the viewpoint of more effectively exerting the effects of the present invention, unsubstituted alkyl groups having 2 to 4 carbon atoms such as ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, tert-butyl group are preferred.

[0083] The A in the above Chemical formula 1 and Chemical formula 2 - and X - Examples of the monovalent anion used therein are not particularly limited, but halide ions such as fluoride ion, chloride ion, bromide ion, iodide ion; hydroxide ion; organic acid ions such as benzoate ion, etc. are suitable. The monovalent anion may be used alone or in combination of two or more. From the viewpoint of more effectively exerting the effects of the present invention, A in the above Chemical formula 1 and Chemical formula 2 - and X - are preferably hydroxide ions (OH - ).

[0084] More specific examples of tetraalkylammonium salts represented by the above chemical formula 1 include, for example, tetramethylammonium fluoride, trimethylethylammonium fluoride, dimethyldiethylammonium fluoride, methyltriethylammonium fluoride, tetraethylammonium fluoride, trimethyl n-propylammonium fluoride, trimethylisopropylammonium fluoride, dimethylethyl n-propylammonium fluoride, dimethylethylisopropylammonium fluoride, methyldiethyl n-propylammonium fluoride, methyldiethylisopropylammonium fluoride, triethylisopropylammonium fluoride, triethyl n-propylammonium fluoride, tetra-n-propylammonium fluoride, tetraisopropylammonium fluoride, and tetra-n-butylammonium fluoride. Mufluoride, tetratert-butylammonium fluoride; tetramethylammonium chloride, trimethylethylammonium chloride, dimethyldiethylammonium chloride, methyltriethylammonium chloride, tetraethylammonium chloride, trimethyl n-propylammonium chloride, trimethylisopropylammonium chloride, dimethylethyl n-propylammonium chloride, dimethylethylisopropylammonium chloride, methyldiethyl n-propylammonium chloride, methyldiethylisopropylammonium chloride, triethylisopropylammonium chloride, triethyl n-propylammonium chloride, triethyl n-propylammonium chloride, tetra-n-propylammonium chloride, tetraisopropylammonium chloride, tetra-n-butylammonium chloride, tetratert-butylammonium chloride;Tetramethylammonium bromide, trimethylethylammonium bromide, dimethyldiethylammonium bromide, methyltriethylammonium bromide, tetraethylammonium bromide, trimethyl n-propylammonium bromide, trimethylisopropylammonium bromide, dimethylethyl n-propylammonium bromide, dimethylethylisopropylammonium bromide, methyldiethyl n-propylammonium bromide, methyldiethylisopropylammonium bromide, triethylisopropylammonium bromide, triethyl n-propylammonium bromide, tetra-n-propylammonium bromide, tetraisopropylammonium bromide, tetra-n-butylammonium bromide, tetratert-butylammonium bromide; Tetramethylammonium iodide, trimethylethylammonium iodide, dimethyldiethylammonium iodide, methyltriethylammonium iodide, tetraethylammonium iodide, trimethyl n-propylammonium iodide, trimethylisopropylammonium iodide, dimethylethyl n-propylammonium iodide, dimethylethylisopropylammonium iodide, methyldiethyl n-propylammonium iodide, methyldiethylisopropylammonium iodide, triethylisopropylammonium iodide, triethyl n-propylammonium iodide, tetra-n-propylammonium iodide, tetraisopropylammonium iodide, tetra-n-butylammonium iodide, tetratert-butylammonium iodide;Tetramethylammonium hydroxide, trimethylethylammonium hydroxide, dimethyldiethylammonium hydroxide, methyltriethylammonium hydroxide, tetraethylammonium hydroxide, trimethyl n-propylammonium hydroxide, trimethylisopropylammonium hydroxide, dimethylethyl n-propylammonium hydroxide, dimethylethylisopropylammonium hydroxide, methyldiethyl n-propylammonium hydroxide, methyldiethylisopropylammonium hydroxide, triethylisopropylammonium hydroxide, triethyl n-propylammonium hydroxide, tetra-n-propylammonium hydroxide, tetraisopropylammonium hydroxide, tetra-n-butylammonium hydroxide, tetra-tert-butylammonium hydroxide; tetramethylammonium hydroxide Examples include butylammonium benzoate, trimethylethylammonium benzoate, dimethyldiethylammonium benzoate, methyltriethylammonium benzoate, tetraethylammonium benzoate, trimethyl n-propylammonium benzoate, trimethylisopropylammonium benzoate, dimethylethyl n-propylammonium benzoate, dimethylethylisopropylammonium benzoate, methyldiethyl n-propylammonium benzoate, methyldiethylisopropylammonium benzoate, triethylisopropylammonium benzoate, triethyl n-propylammonium benzoate, tetra-n-propylammonium benzoate, tetraisopropylammonium benzoate, tetra-n-butylammonium benzoate, tetratert-butylammonium benzoate, etc.

[0085] More specific examples of tetraalkylphosphonium salts represented by the above chemical formula 2 include, for example, tetramethylphosphonium fluoride, trimethylethylphosphonium fluoride, dimethyldiethylphosphonium fluoride, methyltriethylphosphonium fluoride, tetraethylphosphonium fluoride, trimethyln-propylphosphonium fluoride, trimethylisopropylphosphonium fluoride, dimethylethyln-propylphosphonium fluoride, dimethylethylisopropylphosphonium fluoride, methyldiethyln-propylphosphonium fluoride, methyldiethylisopropylphosphonium fluoride, triethylisopropylphosphonium fluoride, triethyln-propylphosphonium fluoride, tetran-propylphosphonium fluoride, tetraisopropylphosphonium fluoride, and tetran-butylphosphonium fluoride. Fluoride, tetra-tert-butylphosphonium fluoride; tetramethylphosphonium chloride, trimethylethylphosphonium chloride, dimethyldiethylphosphonium chloride, methyltriethylphosphonium chloride, tetraethylphosphonium chloride, trimethyln-propylphosphonium chloride, trimethylisopropylphosphonium chloride, dimethylethyln-propylphosphonium chloride, dimethylethylisopropylphosphonium chloride, methyldiethyln-propylphosphonium chloride, methyldiethylisopropylphosphonium chloride, triethylisopropylphosphonium chloride, triethyln-propylphosphonium chloride, tetra-n-propylphosphonium chloride, tetraisopropylphosphonium chloride, tetra-n-butylphosphonium chloride, tetra-tert-butylphosphonium chloride;Tetramethylphosphonium bromide, trimethylethylphosphonium bromide, dimethyldiethylphosphonium bromide, methyltriethylphosphonium bromide, tetraethylphosphonium bromide, trimethyln-propylphosphonium bromide, trimethylisopropylphosphonium bromide, dimethylethyln-propylphosphonium bromide, dimethylethylisopropylphosphonium bromide, methyldiethyln-propylphosphonium bromide, methyldiethylisopropylphosphonium bromide, triethylisopropylphosphonium bromide, triethyln-propylphosphonium bromide, tetran-propylphosphonium bromide, tetraisopropylphosphonium bromide, tetran-butylphosphonium bromide, tetratert-butylphosphonium bromide; Tetramethylphosphonium iodide, trimethylethylphosphonium iodide, dimethyldiethylphosphonium iodide, methyltriethylphosphonium iodide, tetraethylphosphonium iodide, trimethyln-propylphosphonium iodide, trimethylisopropylphosphonium iodide, dimethylethyln-propylphosphonium iodide, dimethylethylisopropylphosphonium iodide, methyldiethyln-propylphosphonium iodide, methyldiethylisopropylphosphonium iodide, triethylisopropylphosphonium iodide, triethyln-propylphosphonium iodide, tetran-propylphosphonium iodide, tetraisopropylphosphonium iodide, tetran-butylphosphonium iodide, tetratert-butylphosphonium iodide;Tetramethylphosphonium hydroxide, trimethylethylphosphonium hydroxide, dimethyldiethylphosphonium hydroxide, methyltriethylphosphonium hydroxide, tetraethylphosphonium hydroxide, trimethyln-propylphosphonium hydroxide, trimethylisopropylphosphonium hydroxide, dimethylethyln-propylphosphonium hydroxide, dimethylethylisopropylphosphonium hydroxide, methyldiethyln-propylphosphonium hydroxide, methyldiethylisopropylphosphonium hydroxide, triethylisopropylphosphonium hydroxide, triethyln-propylphosphonium hydroxide, tetran-propylphosphonium hydroxide, tetraisopropylphosphonium hydroxide, tetran-butylphosphonium hydroxide, tetratert-butylphosphonium hydroxide; tetramethylphosphonium hydroxide Examples include trimethylphosphonium benzoate, trimethylethylphosphonium benzoate, dimethyldiethylphosphonium benzoate, methyltriethylphosphonium benzoate, tetraethylphosphonium benzoate, trimethyln-propylphosphonium benzoate, trimethylisopropylphosphonium benzoate, dimethylethyln-propylphosphonium benzoate, dimethylethylisopropylphosphonium benzoate, methyldiethyln-propylphosphonium benzoate, methyldiethylisopropylphosphonium benzoate, triethylisopropylphosphonium benzoate, triethyln-propylphosphonium benzoate, tetran-propylphosphonium benzoate, tetraisopropylphosphonium benzoate, tetran-butylphosphonium benzoate, tetratert-butylammonium benzoate, etc.

[0086] These organic onium salts can be used individually or in combination of two or more. Furthermore, commercially available or synthetic organic onium salts may be used.

[0087] Among these organic onium salts, from the viewpoint of more easily exhibiting the effects of the present invention, tetraalkylammonium salts represented by the above chemical formula 1 are preferred, and at least one selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetra-n-butylammonium hydroxide is more preferred.

[0088] The lower limit of the content (concentration) of organic onium salt in the polishing composition is preferably 10 ppm (0.001%) or more, more preferably 15 ppm (0.0015%) or more, even more preferably 20 ppm (0.002%) or more, and particularly preferably 25 ppm (0.0025%) or more, relative to the total mass of the polishing composition. The upper limit of the content (concentration) of organic onium salt in the polishing composition is preferably 1000 ppm (0.1%) or less, more preferably 500 ppm (0.05%) or less, even more preferably 300 ppm (0.03%) or less, and particularly preferably 100 ppm (0.01%) or less, relative to the total mass of the polishing composition.

[0089] In other words, the content (concentration) of the organic onium salt in the polishing composition is preferably 10 ppm (0.001%) or more and 1000 ppm (0.1%) or less, more preferably 15 ppm (0.015%) or more and 500 ppm (0.05%) or less, even more preferably 20 ppm (0.002%) or more and 300 ppm (0.03%) or less, and particularly preferably 25 ppm (0.0025%) or more and 100 ppm (0.01%) or less, relative to the total mass of the polishing composition.

[0090] Furthermore, if the polishing composition contains two or more organic onium salts, the content (concentration) of the organic onium salts refers to their total amount.

[0091] [Dispersion medium] The polishing composition according to the present invention preferably further contains a dispersion medium. Examples of dispersion mediums include water; alcohols such as methanol, ethanol, and ethylene glycol; ketones such as acetone, and mixtures thereof. Of these, water is preferred as the dispersion medium. That is, according to a more preferred embodiment of the present invention, the dispersion medium contains water. According to an even more preferred embodiment of the present invention, the dispersion medium consists substantially of water. The term "substantially" above means that a dispersion medium other than water may be included insofar as the objective effects of the present invention can be achieved. More specifically, it preferably consists of 90% to 100% by mass of water and 0% to 10% by mass of a dispersion medium other than water, and more preferably consists of 99% to 100% by mass of water and 0% to 1% by mass of a dispersion medium other than water. Most preferably, the dispersion medium is water.

[0092] From the viewpoint of not inhibiting the action of the components contained in the polishing composition, water containing as few impurities as possible is preferred as the dispersion medium. More specifically, pure water, ultrapure water, or distilled water obtained by removing impurity ions with an ion exchange resin and then removing foreign matter by passing it through a filter is more preferred.

[0093] [Other ingredients] The polishing composition of the present invention may further contain other components as needed, such as complexing agents, metal corrosion inhibitors, preservatives, fungicides, reducing agents, and surfactants. Preservatives and fungicides, which are preferred components, will be described below. Oxidizing agents will also be described.

[0094] (Preservatives and fungicides) Examples of preservatives and fungicides that can be added to the polishing composition according to the present invention include isothiazoline-based preservatives such as 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one, parahydroxybenzoic acid esters, and phenoxyethanol. These preservatives and fungicides can be used individually or in combination of two or more.

[0095] (Oxidizing agent) The polishing composition according to the present invention preferably contains substantially no oxidizing agent. If an oxidizing agent is contained in the polishing composition, it may oxidize the surface of the object to be polished, forming an oxide film and potentially increasing the polishing time. Specific examples of oxidizing agents include hydrogen peroxide (H2O2), sodium persulfate, ammonium persulfate, and sodium dichloroisocyanurate. It should be noted that a polishing composition that contains substantially no oxidizing agent means that it does not contain an oxidizing agent, at least intentionally. Therefore, a polishing composition that inevitably contains trace amounts of oxidizing agent due to raw materials or manufacturing methods is included in the concept of a polishing composition that contains substantially no oxidizing agent as described herein. For example, the content (concentration) of the oxidizing agent in the polishing composition is preferably 100 ppm by mass (0.01% by mass) or less, more preferably less than 100 ppm by mass (0.01% by mass), and even more preferably 50 ppm by mass (0.005% by mass) or less. The lower limit of the oxidizing agent content (concentration) is preferably 0 ppm by mass or more, and more preferably 5 ppm by mass (0.0005% by mass) or more.

[0096] [Form of abrasive composition] The polishing composition according to the present invention is typically supplied to an object to be polished in the form of a polishing liquid containing the polishing composition and used to polish the object. The polishing composition according to the present invention may be used as a polishing liquid after being diluted (typically diluted with water), or it may be used as a polishing liquid as is. That is, the concept of the polishing composition according to the present invention encompasses both a polishing composition (working slurry) supplied to an object to be polished and used to polish the object, and a concentrated liquid (working slurry stock) that is diluted and used for polishing. The concentration ratio of the concentrated liquid can be, for example, about 2 to 100 times by volume, and usually about 3 to 50 times is appropriate.

[0097] [Object to be polished] The material to be polished according to the present invention is not particularly limited and includes, for example, single-crystal silicon, polysilicon (polycrystalline silicon), polycrystalline silicon doped with n-type or p-type impurities, amorphous silicon, amorphous silicon doped with n-type or p-type impurities, silicon-containing materials such as silicon oxide, silicon nitride, and silicon carbonitride (SiCN); metals; carbon-containing materials, etc.

[0098] Examples of polishing targets containing silicon dioxide include, for example, TEOS-type silicon dioxide films (hereinafter also simply referred to as "TEOS" or "TEOS film") produced using tetraethyl orthosilicate as a precursor, HDP (High Density Plasma) films, USG (Undoped Silicate Glass) films, PSG (Phosphorus Silicate Glass) films, BPSG (Boron-Phospho Silicate Glass) films, and RTO (Rapid Thermal Oxidation) films.

[0099] Examples of metals include tungsten, copper, aluminum, cobalt, hafnium, nickel, gold, silver, platinum, palladium, rhodium, ruthenium, iridium, and osmium.

[0100] Examples of carbon-containing materials include amorphous carbon, spin-on carbon (SOC), diamond-like carbon (DLC), nanocrystalline diamond, and graphene.

[0101] The object to be polished may be a commercially available product or may be manufactured by a known method.

[0102] Among these, polishing objects containing silicon-containing materials are preferred, and polishing objects containing silicon dioxide are more preferred. Therefore, according to a preferred embodiment of the present invention, the polishing composition is used for polishing polishing objects containing silicon-containing materials.

[0103] [Method for producing abrasive compositions] The method for producing the polishing composition according to this embodiment is not particularly limited and can be obtained, for example, by stirring and mixing abrasive grains, a first polyoxyalkylene compound, a second polyoxyalkylene compound, and other additives as needed. Details of each component are as described above.

[0104] The temperature at which each component is mixed is not particularly limited, but it is preferably between 10°C and 40°C, and heating may be used to increase the dissolution rate. The mixing time is also not particularly limited as long as uniform mixing is achieved.

[0105] [Polishing method and method for manufacturing semiconductor substrates] As described above, the polishing composition according to this embodiment is particularly suitable for polishing objects containing silicon-based materials. Therefore, the present invention provides a polishing method for polishing an object containing silicon-based materials with the polishing composition according to this embodiment. The present invention also provides a method for manufacturing a semiconductor substrate, comprising polishing a semiconductor substrate containing silicon-based materials by the above polishing method.

[0106] As a polishing device, a general polishing device can be used that has a holder for holding a substrate or the like with 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.

[0107] As the polishing pad, general nonwoven fabrics, polyurethanes, and porous fluororesins can be used without any particular restrictions. Preferably, the polishing pad has grooves that allow the polishing liquid to accumulate.

[0108] Regarding the polishing conditions, for example, the rotational speed of the polishing platen and carrier (head) should be 10 rpm (0.17 s). -1 ) or more 500rpm (8.33s -1 Preferably, the pressure applied to the substrate containing the object to be polished (polishing pressure) is between 0.5 psi (3.45 kPa) and 10 psi (68.9 kPa).

[0109] The method of supplying the polishing composition to the polishing pad is not particularly limited; for example, a method of continuous supply using a pump or the like can be 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 polishing composition according to the present invention.

[0110] The polishing composition according to this embodiment may be a one-component type or a multi-component type, including a two-component type. Furthermore, the polishing composition according to the present invention may be prepared by diluting the stock solution of the polishing composition with a diluent such as water to, for example, 2 to 100 times by volume, usually 3 to 50 times.

[0111] [Polishing speed] As described above, the polishing composition according to the present invention can achieve a good polishing speed for silicon-containing materials.

[0112] In the present invention, the polishing speed of silicon nitride (or silicon nitride film) is preferably 600 Å / min or more, more preferably 650 Å / min or more, and even more preferably 680 Å / min or more. Furthermore, the polishing speed of silicon oxide (or silicon oxide film) is preferably 300 Å / min or more, more preferably 340 Å / min or more, and even more preferably 350 Å / min or more. Furthermore, the polishing speed of polysilicon (or polysilicon film) is preferably 200 Å / min or more, more preferably 400 Å / min or more, and even more preferably 500 Å / min or more. Note that 1 Å = 0.1 nm.

[0113] [Number of defects] As described above, the polishing composition according to the present invention can reduce defects on the surface of a polished object.

[0114] In the present invention, the fewer the number of defects on the surface of the polished object, the better. For example, the number of defects on a polished object having a silicon oxide film is preferably 160 or less, more preferably 135 or less, even more preferably 130 or less, and particularly preferably less than 120 (lower limit 0). The number of defects can be measured by the method described in the examples.

[0115] While embodiments of the present invention have been described in detail, these are descriptive and illustrative, and not limiting, and it is clear that the scope of the present invention should be interpreted by the appended claims.

[0116] The present invention encompasses the following aspects and embodiments: [1] An abrasive composition comprising abrasive grains having a zeta potential of -5mV or less, a first polyoxyalkylene compound having a weight-average molecular weight of 100 to 900, and a second polyoxyalkylene compound having different oxyalkylene units from the first polyoxyalkylene compound and having a weight-average molecular weight of 100 to 900, wherein the pH is less than 7: [2] The polishing composition according to [1] above, wherein the abrasive grains are anion-modified silica: [3] The polishing composition according to [1] or [2] above, wherein the weight-average molecular weight of the first polyoxyalkylene compound is lower than the weight-average molecular weight of the second polyoxyalkylene compound: [4] The polishing composition according to any one of [1] to [3] above, wherein the content of the first polyoxyalkylene compound in the polishing composition is greater than the content of the second polyoxyalkylene compound in the polishing composition: [5] The polishing composition according to any one of [1] to [4] above, wherein the first polyoxyalkylene compound is polyethylene glycol and the second polyoxyalkylene compound is polypropylene glycol: [6] Abrasive composition according to any one of [1] to [5] above, further comprising an inorganic salt: [7] Abrasive composition according to any one of [1] to [6] above, further comprising an organic onium salt: [8] A polishing composition according to any one of [1] to [7] above, further comprising a water-soluble polymer other than a polyoxyalkylene compound: [9] A polishing composition according to any of [1] to [8] above, further comprising a dispersion medium:

[10] Polishing compositions according to any of [1] to [9] above, used for polishing objects containing silicon-based materials:

[11] The abrasive composition according to

[10] above, wherein the silicon-containing material is silicon dioxide:

[12] A polishing method comprising polishing an object to be polished containing a silicon-containing material using any of the polishing compositions described in [1] to

[11] above:

[13] A method for manufacturing a semiconductor substrate, comprising the step of polishing a semiconductor substrate containing a silicon-containing material by the polishing method described in

[12] above. [Examples]

[0117] 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%" and "parts by mass," respectively. In the following examples, unless otherwise specified, the operations were carried out under conditions of room temperature (20°C to 25°C) and relative humidity of 40%RH to 50%RH. The physical properties were measured as follows.

[0118] <Average primary particle diameter and average secondary particle diameter of abrasive grains> The average primary particle diameter of the abrasive grains was calculated from the specific surface area of ​​the abrasive grains and the density of the abrasive grains, measured using the BET method with Micromeritex's "Flow SorbII2300". The average secondary particle diameter of the abrasive grains was measured as the volume-average particle diameter (volume-based arithmetic mean diameter; Mv) using a dynamic light scattering particle size and particle size distribution analyzer UPA-UT151 (manufactured by Nikkiso Co., Ltd.).

[0119] <Zeta potential of abrasive grains> The zeta potential of abrasive grains in the polishing composition was calculated by subjecting the polishing composition to a Malvern Panalytical Zetasizer Nano and measuring it using laser Doppler (electrophoretic light scattering measurement) at a measurement temperature of 25°C. The obtained data was then analyzed using the Smoluchowski equation.

[0120] <pH of the abrasive composition> The pH of the polishing composition was measured using a pH meter (manufactured by Horiba, Ltd., model number: LAQUA).

[0121] <Molecular weight measurement of polyoxyalkylene compounds and other water-soluble polymers> The weight-average molecular weight of polyoxyalkylene compounds and other water-soluble polymers was measured using gel permeation chromatography (GPC) under the following conditions: (GPC measurement conditions) Measuring device: HLC-8320GPC (manufactured by Tosoh Corporation) Sample concentration: 0.01% by mass Column: TSKgel(registered trademark) GMPWXL Detector: Differential refractometer Eluent: A solution of 10 mM lithium bromide dissolved in N,N-dimethylformamide. Flow rate: 1mL / min Measurement temperature: 40℃ Molecular weight conversion: Polyethylene glycol conversion Sample injection volume: 200 μL.

[0122] [Manufacturing of sulfonic acid-modified colloidal silica] Sulfonic acid-modified colloidal silica was obtained as abrasive grains by following the procedure below.

[0123] (Preparation process of raw material colloidal silica dispersion (unmodified silica particles)) In a flask, 4080 g of methanol, 610 g of water, and 168 g of 29% by mass aqueous ammonia solution were mixed and the solution temperature was maintained at 20°C. A mixture of 135 g of methanol and 508 g of tetramethoxysilane (TMOS) was then added dropwise over a period of 25 minutes. Subsequently, the mixture was heated and concentrated by water substitution under conditions of pH 7 or higher to obtain 1000 g of 19.5% by mass silica sol (average primary particle size: 34 nm, average secondary particle size: 70 nm).

[0124] (Surface modification process) Next, to 1000 g of the silica sol obtained above (195 g in terms of silica solids), 1.2 g of 3-mercaptopropyltrimethoxysilane (MPS, silane coupling agent, product name: KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.), which had been mixed separately with 4.8 g of methanol (silane coupling agent content relative to the total mass of silica solids: 0.6% by mass), was added dropwise at a flow rate of 1 mL / min. The mixture was then heated, and after boiling, it was replaced with pure water for 3 hours.

[0125] Next, to allow it to cool, the reaction solution was left to stand overnight, and 0.0343 g of 30% hydrogen peroxide solution (3 moles per mole of silane coupling agent) was added, and it was brought to a boil again. After that, the mixture was replaced with pure water for 2 hours, and then cooled to room temperature (25°C) to obtain sulfonic acid-modified colloidal silica.

[0126] (Example 1) <Preparation of polishing composition> To water as a dispersion medium, sulfonic acid-modified colloidal silica (average primary particle diameter: 34 nm, average secondary particle diameter: 70 nm), which was produced in the above-mentioned <Production of Sulfonic Acid-Modified Colloidal Silica>, was added to obtain a mixture with a final content of 4% by mass. To this mixture, ammonium sulfate ((NH4)2SO4), an inorganic salt, was added to obtain a final content of 2000 ppm by mass (0.2% by mass), and tetraethylammonium hydroxide (TEAH), an organic onium salt, was added to obtain a final content of 26 ppm by mass (0.0026% by mass). Furthermore, polyethylene glycol (PEG) with a weight-average molecular weight (Mw) of 200 was added as the first polyoxyalkylene compound to a final content of 200 ppm by mass (0.02% by mass), polypropylene glycol (PPG) with a weight-average molecular weight (Mw) of 400 was added as the second polyoxyalkylene compound to a final content of 600 ppm by mass (0.06% by mass), and polyvinyl alcohol (PVA) with a weight-average molecular weight (Mw) of 10,000 was added as a water-soluble polymer other than the polyoxyalkylene compound to a final content of 1,000 ppm by mass (0.1% by mass). These were then stirred and mixed (stirring temperature: 25°C, stirring time: 20 minutes). Subsequently, the pH of the polishing composition was adjusted to 2.1 using nitric acid to prepare polishing composition 1.

[0127] (Example 2) Polishing composition 2 was prepared in the same manner as in Example 1, except that the amount of polyethylene glycol with a weight-average molecular weight (Mw) of 200 was changed to an amount that resulted in a final content of 600 ppm by mass (0.06% by mass).

[0128] (Example 3) Polishing composition 3 was prepared in the same manner as in Example 1, except that the amount of polyethylene glycol with a weight-average molecular weight (Mw) of 200 was changed to an amount that resulted in a final content of 1000 ppm by mass (0.1% by mass).

[0129] (Example 4) Polishing composition 4 was prepared in the same manner as in Example 1, except that the amount of polyethylene glycol with a weight-average molecular weight (Mw) of 200 was changed to an amount that resulted in a final content of 3000 ppm by mass (0.3% by mass).

[0130] (Example 5) Polishing composition 5 was prepared in the same manner as in Example 2, except that the first polyoxyalkylene compound was replaced with polyethylene glycol having a weight-average molecular weight (Mw) of 400.

[0131] (Example 6) Polishing composition 6 was prepared in the same manner as in Example 2, except that the first polyoxyalkylene compound was replaced with polyethylene glycol having a weight-average molecular weight (Mw) of 600.

[0132] (Example 7) Polishing composition 7 was prepared in the same manner as in Example 2, except that the first polyoxyalkylene compound was replaced with polyethylene glycol having a weight-average molecular weight (Mw) of 800.

[0133] (Example 8) Polishing composition 8 was prepared in the same manner as in Example 4, except that the amount of polypropylene glycol with a weight-average molecular weight (Mw) of 400 was changed to an amount that resulted in a final content of 200 ppm by mass (0.02% by mass).

[0134] (Example 9) Polishing composition 9 was prepared in the same manner as in Example 4, except that the amount of polypropylene glycol with a weight-average molecular weight (Mw) of 400 was changed to an amount that resulted in a final content of 1000 ppm by mass (0.1% by mass).

[0135] (Example 10) Polishing composition 10 was prepared in the same manner as in Example 4, except that the second polyoxyalkylene compound was replaced with polypropylene glycol having a weight-average molecular weight (Mw) of 200.

[0136] (Example 11) Polishing composition 11 was prepared in the same manner as in Example 4, except that the second polyoxyalkylene compound was replaced with polypropylene glycol having a weight-average molecular weight (Mw) of 800.

[0137] (Comparative Example 1) Comparative polishing composition 1 was prepared in the same manner as in Example 1, except that the first polyoxyalkylene compound and the second polyoxyalkylene compound were not used.

[0138] (Comparative Example 2) Comparative polishing composition 2 was prepared in the same manner as in Example 4, except that the second polyoxyalkylene compound was not used.

[0139] (Comparative Example 3) Comparative polishing composition 3 was prepared in the same manner as in Example 1, except that the first polyoxyalkylene compound was not used.

[0140] (Comparative Example 4) Comparative polishing composition 4 was prepared in the same manner as in Example 2, except that polyethylene glycol with a weight-average molecular weight (Mw) of 600 was used instead of polypropylene glycol with a weight-average molecular weight (Mw) of 400.

[0141] (Comparative Example 5) Comparative polishing composition 5 was prepared in the same manner as in Example 2, except that polyethylene glycol with a weight-average molecular weight (Mw) of 1540 was used instead of polyethylene glycol with a weight-average molecular weight (Mw) of 200.

[0142] The composition of the polishing compositions for Examples 1-11 and Comparative Examples 1-5 is shown in Table 1 below. In Table 1, "-" indicates that the component was not used.

[0143] [Table 1]

[0144] [evaluation] <Polishing speed> The polishing compositions obtained in the above examples and comparative examples were used to polish the surface of the object to be polished under the following polishing conditions. The objects used for polishing were a silicon wafer (300 mm, blanket wafer) with a 5000 Å thick polysilicon (Poly-Si) film formed on its surface, a silicon wafer (300 mm, blanket wafer) with a 10000 Å thick P-TEOS film (TEOS film (silicon oxide film) formed by plasma CVD) formed on its surface, and a silicon wafer (300 mm, blanket wafer) with a 3000 Å thick silicon nitride (Si3N4) film formed on its surface. (polishing conditions) Polishing machine: FREX300E manufactured by Ebara Corporation Pad: Nitta DuPont Corporation, rigid polyurethane pad IC1010 Polishing pressure: 2.0 psi (1 psi = 6894.76 Pa, the same applies below) Polishing plate rotation speed: 90 rpm Carrier rotation speed: 90 rpm Supply of polishing composition: flow-through Polishing composition supply amount: 200ml / min, Polishing time: 1 minute The polishing speed was calculated by determining the thickness using an optical film thickness gauge (RE-3500: manufactured by SCREEN Corporation), and then dividing (thickness before polishing) - (thickness after polishing) by the polishing time.

[0145] <Number of defects> For silicon wafers with a P-TEOS film formed on them, after polishing, the surface was brush-cleaned with a 0.3 mass% NH3 aqueous solution for 40 seconds, and then washed with deionized water for 20 seconds to obtain polished objects.

[0146] Subsequently, the number of surface defects on the polished objects was evaluated using the Surfscan® SP5 optical inspection machine manufactured by KLA-Tencor Co., Ltd.

[0147] Specifically, the number of defects with a diameter of 60 nm or more was measured in the remaining portion of one side of a polished object, excluding a 5 mm wide area from the outer edge (the region from 0 mm to 5 mm when the outer edge is defined as 0 mm).

[0148] The evaluation results for polishing speed and defect count are shown in Table 2 below. In Table 2, silicon nitride films are indicated by "Si3N4", P-TEOS films by "SiO2", and polysilicon films by "Poly-Si".

[0149] [Table 2]

[0150] As is clear from Table 2 above, it was found that when the polishing composition of the example was used, surface defects on polished objects containing silicon dioxide could be reduced. On the other hand, it was found that when the polishing composition of the comparative example was used, surface defects on polished objects containing silicon dioxide increased.

Claims

1. Abrasive grains with a zeta potential of -5 mV or less, A first polyoxyalkylene compound having a weight-average molecular weight of 100 or more and 900 or less, A second polyoxyalkylene compound having different oxyalkylene units from the first polyoxyalkylene compound and having a weight-average molecular weight of 100 or more and 900 or less, Includes, A polishing composition having a pH of less than 7.

2. The polishing composition according to claim 1, wherein the abrasive grains are anion-modified silica.

3. The polishing composition according to claim 1, wherein the weight-average molecular weight of the first polyoxyalkylene compound is lower than the weight-average molecular weight of the second polyoxyalkylene compound.

4. The polishing composition according to claim 3, wherein the content of the first polyoxyalkylene compound in the polishing composition is greater than the content of the second polyoxyalkylene compound in the polishing composition.

5. The first polyoxyalkylene compound is polyethylene glycol. The polishing composition according to claim 3, wherein the second polyoxyalkylene compound is polypropylene glycol.

6. The polishing composition according to claim 1, further comprising an inorganic salt.

7. The polishing composition according to claim 1, further comprising an organic onium salt.

8. The polishing composition according to claim 1, further comprising a water-soluble polymer other than a polyoxyalkylene compound.

9. The polishing composition according to claim 1, further comprising a dispersion medium.

10. The polishing composition according to claim 1, used for polishing an object to be polished that contains a silicon-containing material.

11. The polishing composition according to claim 10, wherein the silicon-containing material is silicon dioxide.

12. A polishing method comprising polishing an object to be polished containing a silicon-containing material using the polishing composition described in any one of claims 1 to 11.

13. A method for manufacturing a semiconductor substrate, comprising the step of polishing a semiconductor substrate containing a silicon-containing material by the polishing method described in claim 12.

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