Grinding composition

Abstract

To provide a novel composition for polishing for enhancing step performance (especially erosion).SOLUTION: There is provided a composition for polishing used for polishing a polishing target, containing an abrasive grain and a dispersant, having average primary particle diameter of the abrasive grain of 40 nm or less, and coarse particle with particle diameter of 0.2 to 1,600 μm in the abrasive grain is 20,000 or less per 1 cmof the composition for polishing.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polishing composition. [Background technology]

[0002] New microfabrication technologies are being developed to accompany the increasing integration and performance of LSI (Large Scale Integration). Chemical mechanical polishing (CMP) is one such technology, and it is frequently used in the LSI manufacturing process, particularly in the multi-layer wiring formation process, for planarizing interlayer insulating films, forming metal plugs, and forming buried wiring (damascene wiring).

[0003] In recent years, with the shrinking of design rules, the technology required for device manufacturing has become more stringent year by year, and improving step performance has become an important issue for LSI semiconductor devices. In particular, suppressing erosion is essential for improving step performance (for example, JP 2004-123921 A). Summary of the Invention

[0004] Therefore, the problem to be solved by the present invention is to provide a novel polishing composition that contributes to improving step performance (particularly erosion).

[0005] One embodiment of the present invention for solving the above-mentioned problems is a polishing composition used for polishing an object to be polished, comprising abrasive grains and a dispersion medium, wherein the abrasive grains have an average primary particle size of 40 nm or less, and among the abrasive grains, coarse grains having a particle size of 0.2 to 1,600 μm are present in an amount of 1 cm of the polishing composition. 3 The polishing composition has 20,000 or less particles per particle. DETAILED DESCRIPTION OF THE INVENTION

[0006] The present invention will be described below. However, the present invention is not limited to the following embodiments. Unless otherwise specified, operations and measurements of physical properties are performed under conditions of room temperature (20 to 25°C) and relative humidity of 40 to 50% RH.

[0007] (Polishing composition) One aspect of the present invention is a polishing composition used for polishing an object to be polished, comprising abrasive grains and a dispersion medium, wherein the abrasive grains have an average primary particle size of 40 nm or less, and the abrasive grains contain coarse particles having a particle size of 0.2 to 1,600 μm per 1 cm of the polishing composition. 3 The polishing composition has 20,000 or less particles per particle. With this configuration, a novel polishing composition that contributes to improving step performance (particularly erosion) can be provided.

[0008] (abrasive grain) The polishing composition of the present invention contains abrasive grains, the abrasive grains having an average primary particle size of 40 nm or less, and among the abrasive grains, coarse grains having a particle size of 0.2 to 1,600 μm are present in an amount of 1 cm of the polishing composition. 3 The number of particles per wafer is 20,000 or less. According to the present invention, a novel polishing composition that contributes to improved step performance (particularly erosion) can be provided. Erosion can be measured by the following method. An 8-inch SiN / P-TEOS patterned wafer is polished, and the SiN layer is removed from the convex portions of the pattern until the P-TEOS layer is exposed, forming a patterned surface consisting of P-TEOS and SiN on the wafer. Next, for the resulting patterned surface, the difference in step height X (Å) between the P-TEOS portion on the wiring and the P-TEOS portion on the wiring can be measured using an AFM (atomic force microscope) (AFM WA1300, manufactured by Hitachi Construction Machinery FineTech Co., Ltd.) for a line-and-space area of ​​0.25 μm / 0.25 μm.

[0009] Examples of types of abrasive grains include metal oxides such as silica, alumina, zirconia, ceria, and titania. Silica is preferred in order to efficiently achieve the desired effects of the present invention. Suitable examples of silica are not particularly limited, but include colloidal silica, fumed silica, and sol-gel silica. Among these, colloidal silica is preferred.

[0010] In the polishing composition of the present invention, the average primary particle size of the abrasive grains is 40 nm or less. If the average primary particle size of the abrasive grains exceeds 40 nm, the intended effect of the present invention cannot be achieved. In an embodiment of the present invention, the average primary particle size of the abrasive grains is preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 15 nm or less, and may be 13 nm or less, 12 nm or less, 11 nm or less, 10 nm or less, 9 nm or less, or 8 nm or less. In particular, when the average primary particle size is 15 nm or less, 13 nm or less, or 11 nm or less, the erosion suppression effect becomes significant.

[0011] In the polishing composition of the present invention, the average primary particle size of the abrasive grains is 1 nm or more. In the polishing composition of the present invention, the average primary particle size of the abrasive grains is 2 nm or more. Also, in the polishing composition of the present invention, the average primary particle size of the abrasive grains is 3 nm or more. In the polishing composition of the present invention, the average primary particle size of the abrasive grains is 4 nm or more. Also, in the polishing composition of the present invention, the average primary particle size of the abrasive grains is 5 nm or more. Also, in the polishing composition of the present invention, the average primary particle size of the abrasive grains is 6 nm or more, the average primary particle size of the abrasive grains is 7 nm or more, the average primary particle size of the abrasive grains is 8 nm or more, the average primary particle size of the abrasive grains is 9 nm or more, and the average primary particle size of the abrasive grains is 10 nm or more. When the abrasive grains have such an average primary particle size, the removal rate of the silicon nitride film can be improved when polishing the silicon nitride film. In the present invention, the average primary particle size of the abrasive grains is measured by the method described in the Examples.

[0012] In the polishing composition of the present invention, among the abrasive grains, particles having a particle diameter of 0.2 to 1,600 μm (hereinafter, also simply referred to as "coarse particles") are contained in 1 cm of the polishing composition. 3 The number of particles per 1 cm of the polishing composition is 20,000 or less. 3 In an embodiment of the present invention, when the number of coarse particles per 1 cm of the polishing composition exceeds 20,000, the desired effect of the present invention cannot be obtained. 3 Preferably, the number is 10,000 or less per particle, more preferably 8,000 or less, even more preferably 6,000 or less, even more preferably 4,000 or less, even more preferably 3,500 or less, even more preferably 3,230 or less, even more preferably 3,000 or less, even more preferably 2,800 or less, even more preferably 2,500 or less, even more preferably 2,400 or less, even more preferably 2,300 or less, and even more preferably 2,200 or less. In particular, by having the number be 3,230 or less, 3,000 or less, 2,800 or less, 2,500 or less, or 2,300 or less, the erosion suppression effect becomes significant. Note that there is no particular lower limit, but in reality, it is about 0 or more, 100 or more, or 200 or more. In addition, in an embodiment of the present invention, in consideration of improving the polishing rate of a silicon nitride film, it is preferable that a certain number of coarse particles are present, for example, about 500 or more, about 1,000 or more, about 1,500 or more, or about 2,000 or more. In the present invention, the particle size of the coarse particles is measured by the method described in the Examples. In an embodiment of the present invention, the coarse particles are present in an amount of 1 cm of the polishing composition. 3 In the embodiment of the present invention, the coarse particles are present in an amount of 1,000 to 3,230 per cm of the polishing composition. 3 In an embodiment of the present invention, the coarse particles are present in an amount of 1,500 to 3,000 per cm of the polishing composition. 3There are 2,000 to 2,300 particles per hole. This embodiment provides a significant effect of suppressing erosion.

[0013] In an embodiment of the present invention, the average secondary particle diameter of the abrasive grains is preferably 70 nm or less, more preferably 55 nm or less, even more preferably 40 nm or less, even more preferably 30 nm or less, even more preferably 20 nm or less, and even more preferably 15 nm or less. In particular, when the average secondary particle diameter is 40 nm or less, 30 nm or less, 20 nm or less, or 15 nm or less, the erosion suppression effect becomes remarkable. In the polishing composition of the present invention, the average secondary particle diameter of the abrasive grains is 10 nm or more. Also, in the polishing composition of the present invention, the average secondary particle diameter of the abrasive grains is 13 nm or more. Also, in the polishing composition of the present invention, the average secondary particle diameter of the abrasive grains is 32 nm or more. Also, in the polishing composition of the present invention, the average secondary particle diameter of the abrasive grains is 45 nm or more. Also, in the polishing composition of the present invention, the average secondary particle diameter of the abrasive grains is 50 nm or more. In the present invention, the average secondary particle diameter of the abrasive grains is measured by the method described in the Examples.

[0014] In an embodiment of the present invention, in the particle size distribution of the abrasive grains in the polishing composition, measured by laser diffraction scattering method, the ratio of the particle diameter D90 when the cumulative particle mass from the fine particle side reaches 90% of the total particle mass to the particle diameter D10 when the cumulative particle mass of the total particle reaches 10% (also referred to simply as "D90 / D10" in this specification) is preferably 1.3 or more, more preferably 1.4 or more, even more preferably 1.5 or more, even more preferably 1.6 or more, even more preferably 1.7 or more, even more preferably 1.8 or more, even more preferably 1.9 or more, and even more preferably 2.0 or more. In particular, by being 1.8 or more, the erosion suppression effect becomes significant. In an embodiment of the present invention, the upper limit of D90 / D10 is preferably 5.0 or less, more preferably 4.0 or less, even more preferably 3.0 or less, even more preferably 2.9 or less, even more preferably 2.8 or less, even more preferably 2.7 or less, even more preferably 2.6 or less, even more preferably 2.5 or less, even more preferably 2.4 or less, even more preferably 2.3 or less, and even more preferably 2.2 or less. In particular, by having the ratio be 2.3 or less or 2.2 or less, the erosion suppression effect becomes remarkable.

[0015] In an embodiment of the present invention, the abrasive grains have a negative zeta potential in an acidic region, which can increase the polishing rate for an object to be polished that has a positive zeta potential in an acidic region.

[0016] In an embodiment of the present invention, the abrasive grains may have a surface-modified abrasive. Such abrasive grains can be obtained, for example, by doping the abrasive grains with a metal such as aluminum, titanium, or zirconium, or an oxide thereof, or by immobilizing an organic acid. Among these, abrasive grains having an organic acid immobilized on the surface are preferred. Among these, silica having an organic acid chemically bonded to its surface is particularly preferred. In such a form, the abrasive grains have a negative zeta potential in the acidic range. In an embodiment of the present invention, the organic acid is not particularly limited, but examples include sulfonic acid, carboxylic acid, and phosphoric acid, with sulfonic acid being preferred. Note that silica having an organic acid immobilized on its surface has acidic groups (e.g., sulfo, carboxyl, and phosphate groups) derived from the organic acid immobilized on the silica surface by covalent bonding (possibly via a linker structure). Here, the linker structure refers to any structure interposed between the silica surface and the organic acid. Therefore, the silica with organic acid fixed on the surface may have the acidic group derived from organic acid fixed on the surface of silica by direct covalent bond, or may be fixed by covalent bond via a linker structure.The method of introducing these organic acids to the silica surface is not particularly limited, and there is a method of introducing them on the silica surface in the form of mercapto group or alkyl group, etc., and then oxidizing them to sulfonic acid or carboxylic acid, as well as a method of introducing them on the silica surface in the form of a protecting group bonded to the organic acid group, and then removing the protecting group.

[0017] As a specific method for synthesizing silica having an organic acid immobilized on its surface, if sulfonic acid, a type of organic acid, is to be immobilized on the surface of silica, it can be carried out, for example, by the method described in "Sulfonic acid-functionalized silica through quantitative oxidation of thiol groups," Chem. Commun. 246-247 (2003). Specifically, silica having a sulfonic acid immobilized on its surface can be obtained by coupling a silane coupling agent having a thiol group, such as 3-mercaptopropyltrimethoxysilane, to silica and then oxidizing the thiol group with hydrogen peroxide. The colloidal silica having a surface modified with sulfonic acid in the examples of the present invention was also produced in a similar manner.

[0018] Carboxylic acid can be immobilized on the surface of silica by, for example, 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, silica with carboxylic acid immobilized on its surface can be obtained by coupling a silane coupling agent containing a photoreactive 2-nitrobenzyl ester to silica and then irradiating the silica with light.

[0019] In an embodiment of the present invention, the degree of association of the abrasive grains (average secondary particle size / average primary particle size) is preferably 1.6 or more, and more preferably 1.8 or more. Furthermore, in an embodiment of the present invention, the degree of association of the abrasive grains (average secondary particle size / average primary particle size) is preferably 4.5 or less, more preferably 3.0 or less, even more preferably 2.7 or less, even more preferably 2.6 or less, and may be 2.5 or less, 2.4 or less, 2.3 or less, or 2.2 or less. In this case, it is particularly preferable that the average primary particle size of the abrasive grains is 6 nm or more. This embodiment allows the effects of the present invention to be efficiently achieved.

[0020] In an embodiment of the present invention, the lower limit of the content of abrasive grains in the polishing composition is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, even more preferably 0.5 mass% or more, even more preferably 1.0 mass% or more, even more preferably 1.5 mass% or more, and even more preferably 1.8 mass% or more. By having such a lower limit, when polishing a silicon nitride film, the polishing rate of the silicon nitride film can be improved.

[0021] In an embodiment of the present invention, the upper limit of the abrasive grain content in the polishing composition is preferably 30% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, even more preferably 4% by mass or less, even more preferably 3% by mass or less, even more preferably 2.5% by mass or less, and even more preferably 2.2% by mass or less. By having such an upper limit, when polishing a silicon nitride film, an appropriate polishing rate for the silicon nitride film can be achieved. In an embodiment of the present invention, the abrasive grain content is 0.5 to 2.5% by mass. According to such an embodiment, an appropriate number of abrasive grains are contained in the polishing composition, and the desired effect of the present invention can be efficiently achieved.

[0022] (dispersion medium) The polishing composition of the present invention uses a dispersion medium to disperse the components constituting the polishing composition. The dispersion medium may be an organic solvent or water, but is preferably water.

[0023] From the viewpoint of preventing contamination of the object to be polished and inhibiting the action of other components, it is preferable to use water that contains as few impurities as possible. Specifically, it is preferable to use pure water or ultrapure water that has been purified by ion exchange resin to remove impurity ions and then filtered to remove foreign matter, or distilled water.

[0024] (pH adjuster) In an embodiment of the present invention, a pH adjuster may be contained in the polishing composition, particularly to adjust the pH to an acidic or basic range.

[0025] In the present invention, the acidic range means a pH of less than 7, preferably a pH of 6 or less, more preferably a pH of 0.5 to 5, more preferably a pH of 1 to 4, and even more preferably a pH of 1.5 to 3.5. In addition, in the present invention, the neutral range means a pH of 7. In addition, in the present invention, the basic range means a pH of more than 7, preferably a pH of 9 to 13, and more preferably a pH of 10 to 12. In addition, the pH values ​​in the present invention refer to values ​​measured under the conditions described in the Examples.

[0026] In an embodiment of the present invention, the polishing composition is preferably adjusted to be acidic. By using such an embodiment, when polishing a silicon nitride film, the polishing rate of the silicon nitride film can be improved.

[0027] Specific examples of pH adjusters for adjusting to an acidic range may be either inorganic or organic compounds, and include, for example, inorganic acids such as sulfuric acid, nitric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, and phosphoric acid; carboxylic acids such as citric acid, formic acid, acetic acid, propionic acid, benzoic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, maleic acid, phthalic acid, malic acid, tartaric acid, and lactic acid; and organic acids such as organic sulfuric acids such as methanesulfonic acid, ethanesulfonic acid, and isethionic acid. Furthermore, in the case of the above-mentioned acids having a valence of two or more (e.g., sulfuric acid, carbonic acid, phosphoric acid, oxalic acid, etc.), protons (H + ) can be released, the salt form is also acceptable. Specifically, for example, ammonium hydrogen carbonate and ammonium hydrogen phosphate are preferred (the type of counter cation is basically not limited, but a weakly basic cation (ammonium, triethanolamine, etc.) is preferred).

[0028] Specific examples of pH adjusters for adjusting the pH to the basic range may be either inorganic or organic compounds, but include alkali metal hydroxides or salts thereof, quaternary ammonium, quaternary ammonium hydroxides or salts thereof, ammonia, amines, etc.

[0029] Specific examples of alkali metals include potassium, sodium, etc. Specific examples of salts include carbonates, hydrogen carbonates, sulfates, acetates, etc.

[0030] Specific examples of quaternary ammonium include tetramethylammonium, tetraethylammonium, and tetrabutylammonium.

[0031] Specific examples of the quaternary ammonium hydroxide or its salt include tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide.

[0032] (Other ingredients) In the present invention, the polishing composition may further contain, as necessary, known additives that can be used in polishing compositions, such as oxidizing agents, chelating agents, water-soluble polymers, surfactants, preservatives, or antifungal agents, as long as the effects of the present invention are not impaired. However, according to an embodiment of the present invention, the polishing composition is substantially free of oxidizing agents. This embodiment can improve the polishing rate of a silicon nitride film when polishing the silicon nitride film. Note that "substantially free" includes not only the concept of being completely free of an oxidizing agent in the polishing composition, but also the case where the polishing composition contains 0.1 mass % or less of an oxidizing agent.

[0033] (Polished object) In an embodiment of the present invention, the object to be polished preferably includes at least one film selected from a silicon oxide film, a silicon nitride film, a polysilicon film, a titanium nitride film, and a single crystal silicon film. In such an embodiment, the desired effects of the present invention can be efficiently achieved. In an embodiment of the present invention, the silicon oxide film is preferably derived from TEOS (tetraethyl orthosilicate).

[0034] In an embodiment of the present invention, the polishing composition of the present invention is preferably used on an object to be polished, which includes a silicon nitride film and at least one of a silicon oxide film and a polysilicon film. Thus, in a preferred embodiment of the present invention, the object to be polished includes a silicon nitride film and at least one of a silicon oxide film and a polysilicon film. This embodiment has the technical effect of increasing the polishing rate of a silicon nitride film relative to at least one of a silicon oxide film and a polysilicon film. In the polishing composition of the present invention, abrasive grains having an average primary particle size of a specific particle size or less are used, and the polishing composition contains no more than a specific number of coarse particles. By using abrasive grains having an average primary particle size of 15 nm or less, 11 nm or less, 10 nm or less, 9 nm or less, or 8 nm or less, the polishing rate of a silicon nitride film relative to at least one of a silicon oxide film and a polysilicon film can be significantly increased. In particular, by having the number of coarse particles in the polishing composition be 3,230 or less, 3,000 or less, 2,800 or less, 2,500 or less, 2,400 or less, 2,300 or less, or 2,200 or less (or in some cases 1,500 or more, or 2,000 or more), the polishing rate of a silicon nitride film relative to at least one of a silicon oxide film and a polysilicon film can be significantly increased, and erosion can also be suppressed. In such an embodiment, the surprising effects of controlling the selectivity and suppressing erosion can be achieved by adjusting the average primary particle size of the abrasive grains and the number of coarse particles in the polishing composition, without adding any additional additives.

[0035] In an embodiment of the present invention, a separate additive may be added to the polishing composition. A water-soluble additive is suitable as the additive. Suitable water-soluble additives include cationic polymers, anionic polymers, nonionic polymers, cationic surfactants, anionic surfactants, nonionic surfactants, and sugar alcohols. These may be used alone or in combination of two or more. These may be in the form of a salt.

[0036] Specific examples of these additives include at least one selected from the group consisting of anion-modified polyvinyl alcohol, lauryl sulfate or a salt thereof (e.g., a sodium salt), POE allyl phenyl ether phosphate or a salt thereof (e.g., an amine salt), sorbitol, lauryl dimethylamine N-oxide, naphthalenesulfonic acid-formalin condensate, poly(meth)acrylic acid, polyvinylpyrrolidone (PVP), dextrin, polyvinyl alcohol (PVA), POE sorbitan monooleate, and polyglycerin.

[0037] In an embodiment of the present invention, when a polymer (including a sugar alcohol polymer) is used as the water-soluble additive, the lower limit of the weight-average molecular weight is, in order of preference, 1,000 or more, 1,100 or more, 1,200 or more, 1,300 or more, 1,350 or more, 1,400 or more, and 1,450 or more. The upper limit is, in order of preference, 10 million or less, 5 million or less, 2 million or less, 1 million or less, 500,000 or less, 100,000 or less, 10,000 or less, 5,000 or less, 2,500 or less, 2,000 or less, 1,800 or less, and 1,600 or less. The weight-average molecular weight is measured by the method described in the Examples. In an embodiment of the present invention, when a surfactant or a sugar alcohol that is not a polymer is used as the water-soluble additive, the molecular weight is usually less than 1,000.

[0038] (Method of manufacturing polishing composition) A method for producing a polishing composition according to one embodiment of the present invention includes mixing abrasive grains with a dispersion medium, wherein the abrasive grains have an average primary particle size of 40 nm or less, and the abrasive grains contain coarse particles having a particle size of 0.2 to 1,600 μm per 1 cm of the polishing composition. 3 The number of particles is 20,000 or less per particle. More specifically, for example, the abrasive grains and, if necessary, other components are stirred and mixed in the dispersion medium. The temperature at which the components are mixed is not particularly limited, but is preferably 10 to 40°C, and heating may be used to increase the dissolution rate. The mixing time is also not particularly limited.

[0039] In an embodiment of the present invention, the average primary particle diameter of the abrasive grains is 40 nm or less, and among the abrasive grains, coarse particles having a particle diameter of 0.2 to 1,600 μm are contained in 1 cm of the polishing composition. 3 There are no particular limitations on the method for achieving a density of 20,000 or less per particle, but this can be achieved, for example, by filtering through a depth filter with a filtration accuracy of 0.2 μm and a filter medium and core made of polypropylene. Suitable examples of such filters include 254L-SLF-002EF manufactured by ROKI TECHNO CO., LTD. According to one embodiment of the present invention, the preparation of the polishing composition of one aspect of the present invention may include a confirmation step of confirming whether the number of coarse particles is within a predetermined value (or a predetermined range of values).

[0040] (polishing method) The present invention also provides a polishing method in which an object to be polished is polished using the polishing composition described above or a polishing composition obtained by the production method described above.

[0041] As the polishing device, a general polishing device can be used, which is equipped with a holder for holding a substrate or the like having an object to be polished, a motor whose rotation speed can be changed, and a polishing platen onto which a polishing pad (polishing cloth) can be attached.

[0042] The polishing pad can be made of any material, including, without particular limitation, a general nonwoven fabric, polyurethane, porous fluororesin, etc. The polishing pad is preferably provided with grooves for accumulating the polishing composition.

[0043] The polishing conditions are not particularly limited, and for example, the rotation speed of the polishing platen is preferably 10 to 500 rpm, the rotation speed of the carrier is preferably 10 to 500 rpm, and the pressure (polishing pressure) applied to the substrate having the object to be polished is preferably 0.1 to 10 psi. The method of supplying the polishing composition to the polishing pad is also not particularly limited, and for example, a method of continuously supplying it using a pump or the like is used. There is no limit to the amount of supply, but it is preferable that the surface of the polishing pad is always covered with the polishing composition of the present invention.

[0044] (Method of manufacturing semiconductor substrate) The present invention also provides a method for manufacturing a semiconductor substrate, which includes the polishing method described above. The method for manufacturing a semiconductor substrate of the present invention includes the polishing method described above, and therefore can produce a semiconductor substrate with improved step performance, that is, with high flatness.

[0045] Although the embodiments of the present invention have been described in detail, it is clear that this is by way of illustration and example only and not of limitation, and that the scope of the present invention should be interpreted by the appended claims.

[0046] 1. A polishing composition used for polishing an object to be polished, comprising abrasive grains and a dispersion medium, wherein the average primary particle diameter of the abrasive grains is 40 nm or less, and among the abrasive grains, coarse particles having a particle diameter of 0.2 to 1,600 μm are present in an amount of 1 cm of the polishing composition. 3 A polishing composition having 20,000 or less particles per particle.

[0047] 2. The polishing composition according to 1, wherein the average primary particle size of the abrasive grains is 15 nm or less.

[0048] 3. The polishing composition according to 1, wherein the average primary particle size of the abrasive grains is 11 nm or less.

[0049] 4. The polishing composition according to any one of 1. to 3., wherein the abrasive grains have a D90 / D10 ratio of 2.2 or less.

[0050] 5. The polishing composition according to any one of 1. to 4., wherein the content of the abrasive grains is 0.5 to 2.5 mass %.

[0051] 6. The polishing composition according to any one of 1. to 5., wherein the abrasive grains have a negative zeta potential in an acidic region.

[0052] 7. The polishing composition according to any one of 1. to 6., wherein the abrasive grains have an organic acid fixed to the surface thereof.

[0053] 8. The polishing composition according to any one of 1. to 7., wherein the degree of association of the abrasive grains is 2.3 or less.

[0054] 9. The polishing composition according to any one of 1. to 8., which has a pH of 1 to 4.

[0055] 10. The polishing composition according to any one of 1. to 9., which is substantially free of an oxidizing agent.

[0056] 11. The polishing composition according to any one of 1. to 10., wherein the object to be polished comprises at least one film selected from a silicon oxide film, a silicon nitride film, a polysilicon film, a titanium nitride film, and a single crystal silicon film.

[0057] 12. The polishing composition according to any one of 1. to 11., wherein the object to be polished comprises a silicon nitride film; and at least one of a silicon oxide film and a polysilicon film.

[0058] 13. A polishing composition according to any one of 1. to 12., further containing at least one additive selected from the group consisting of cationic polymers, anionic polymers, nonionic polymers, cationic surfactants, anionic surfactants, nonionic surfactants, and sugar alcohols.

[0059] 14. A polishing method comprising polishing an object to be polished using the polishing composition according to any one of 1. to 13.

[0060] 15. A method for manufacturing a semiconductor substrate, comprising the polishing method according to 14. [Example]

[0061] 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. In the following examples, unless otherwise specified, the operations were carried out under the conditions of room temperature (25°C) and relative humidity of 40 to 50% RH.

[0062] <Production of Polishing Composition> (Examples 1 to 18, Comparative Examples 1 to 4) Abrasive grains having the average primary particle size, average secondary particle size, D90 / D10, and number of coarse grains shown in Tables 1 and 2; maleic acid as a pH adjuster; and (in some examples and comparative examples) additives were mixed in a dispersion medium (pure water) to abrasive grain concentration of 2% by mass and pH of 2 (mixing temperature: approximately 25°C, mixing time: approximately 10 minutes). The content of the additive was 0.05 g per kg of polishing composition (except when sorbitol was used as the additive, the content was 2 g). In Table 2, circles 1 and 2 indicate the presence of two types of additives. The weight-average molecular weight (Mw) was measured by gel permeation chromatography (GPC) and calculated as a polymethyl methacrylate equivalent.

[0063] The abrasive grains used in Examples 1, 2, 6 to 18 and Comparative Examples 3 and 4 were colloidal silica whose surfaces were modified with sulfonic acid, while the abrasive grains used in Examples 3 to 5 and Comparative Examples 1 and 2 were colloidal silica whose surfaces were not modified.

[0064] The average primary particle size of the abrasive grains was calculated from the specific surface area of ​​the abrasive grains measured by the BET method using a Micromeritics Flow Sorb II 2300 and the density of the abrasive grains. The average secondary particle size of the abrasive grains was calculated by dynamic light scattering using a Microtrac UPA-UT151.

[0065] The pH of the polishing composition (liquid temperature: 25° C.) was confirmed with a pH meter (manufactured by Horiba Ltd., model number: LAQUA).

[0066] The number of coarse particles (particle diameter of 0.2 μm or more and 1,600 μm or less) was measured as follows.

[0067] [Measuring equipment and conditions] (measuring equipment) Liquid-borne particle measuring instrument (KS-41B: manufactured by Rion Co., Ltd.) (conditions) ·Data correction time: 60sec ·Sample dilution target: 2000 count / mL ·Sample flow rate: 10mL / min.

[0068] <Polishing performance evaluation> As the object to be polished, 200mm wafer (TEOS (silicon oxide film)), 200mm wafer (SiN (silicon nitride) film), Each wafer was polished under the following polishing conditions using the polishing composition obtained above, and the polishing rate was measured. The selectivity was also calculated. Here, TEOS means tetraethyl orthosilicate, and indicates that the silicon oxide film is a silicon oxide film derived from tetraethyl orthosilicate.

[0069] (polishing conditions) Polishing machine: CMP single-sided polishing machine for 200mm wafers (MIRRA: manufactured by AMAT) Polishing pad: Hard foam polyurethane pad (IC1010: manufactured by Rohm and Haas) Pressure: 3 psi (approx. 20.7 kPa) Platen rotation speed: 90 rpm Head (carrier) rotation speed: 87 rpm Polishing composition flow rate: 130 ml / min Grinding time: 1 minute.

[0070] (polishing rate) The removal rate (RR) was calculated using the following formula:

[0071]

number

[0072] The film thickness was measured using an optical interference film thickness measuring device (KLA-Tencor Corporation, model number: ASET) and evaluated by dividing the difference by the polishing time. The results are shown in Tables 1 and 2.

[0073] (selectivity ratio) The selectivity was calculated by dividing the polishing rate (Å / min) of TEOS (silicon oxide film) by the polishing rate (Å / min) of SiN (silicon nitride film). The results are shown in Tables 1 and 2.

[0074] (erosion) A 200 mm diameter silicon nitride / HDP patterned wafer (same as the SiN / P-TEOS patterned wafer below) with a silicon nitride portion and a high-density plasma CVD silicon oxide portion was polished under the above polishing conditions. After polishing, the patterned wafer was measured for erosion (Å) using an atomic force microscope in the area where 0.25 μm wide silicon nitride portions were formed at 0.25 μm intervals. The results are shown in Tables 1 and 2.

[0075] More specifically, it is as follows.

[0076] For erosion, an 8-inch SiN / HDP patterned wafer with the following configuration was polished, and the SiN layer was removed from the convex portions of the pattern until the HDP layer was exposed, forming a patterned surface consisting of HDP and SiN on the wafer. The polishing conditions were as described above.

[0077] [8-inch SiN / P-TEOS patterned wafer] specification 1st layer: SiN, thickness 700 Å (patterned, pattern corresponds to 1st layer, step 600 Å) 2nd layer: HDP, thickness 1000Å (patterned, step 600Å) 3rd layer: Bare-Si.

[0078] Of the above, the first layer corresponds to the polished surface side.

[0079] Next, for the obtained pattern surface, for the part where the line and space was 0.25 μm / 0.25 μm, the difference in height X (Å) between the HDP part of the part without wiring and the HDP part on the wiring was measured as erosion using an AFM (atomic force microscope) (AFM WA1300 manufactured by Hitachi Construction Machinery Finetech Co., Ltd.).

[0080] (scratch) Before the scratch measurement, a cleaning process was carried out as follows.

[0081] Each polished object was cleaned using approximately 0.05% ammonia water, by rubbing the object with a cleaning brush made of a polyvinyl alcohol (PVA) sponge under pressure under the following conditions.

[0082] Polishing device with integrated cleaning device: MirraMesa manufactured by Applied Materials Cleaning brush rotation speed: 100 rpm Polished object rotation speed: 50 rpm Post-cleaning treatment composition type: Water (deionized water) Post-cleaning treatment composition supply amount: 1000 mL / min Cleaning time: 60 seconds.

[0083] [Scratch number evaluation] The number of scratches on the polished object after the above cleaning treatment was measured by SEM observation using a Review SEM RS6000 manufactured by Hitachi, Ltd. First, 100 defects present on the remaining area, excluding a 5 mm wide area from the outer peripheral edge of one side of the polished object (the area from 0 mm to 5 mm wide when the outer peripheral edge is set to 0 mm), were sampled using SEM observation. Next, particle residues were visually identified from the 100 sampled defects using SEM observation, and the percentage of particle residues among the defects was calculated by counting the number of particles. The number of scratches was calculated as the product of the number of defects 0.13 μm or larger (measured using a KLA Tencor SP-2 in the defect count evaluation described above) and the percentage of scratches among the defects (calculated from the SEM observation results).

[0084] [Table 1]

[0085] [Table 2]

[0086] This application is based on Japanese Patent Application No. 2018-041108, filed on March 7, 2018, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A polishing composition used for polishing an object to be polished, abrasive grains and a dispersion medium; The average primary particle diameter of the abrasive grains is 6 nm or more and 40 nm or less, Among the abrasive grains, coarse grains having a particle diameter of 0.2 to 1,600 μm are present in 1 cm of the polishing composition. ３ The polishing composition has 500 or more and 4,000 or less particles per particle.

2. 2. The polishing composition according to claim 1, wherein the abrasive grains have an average primary particle size of 15 nm or less.

3. 3. The polishing composition according to claim 2, wherein the abrasive grains have an average primary particle size of 11 nm or less.

4. 4. The polishing composition according to claim 1, wherein the abrasive grains have a D90 / D10 ratio of 2.2 or less.

5. A polishing composition as described in claim 4, wherein the average secondary particle diameter of the abrasive grains is 10 nm or more and 70 nm or less.

6. 6. The polishing composition according to claim 1, wherein the content of the abrasive grains is 0.5 to 3 mass %.

7. 7. The polishing composition according to claim 1, wherein the abrasive grains have a negative zeta potential in an acidic region.

8. 8. The polishing composition according to claim 1, wherein the abrasive grains have an organic acid fixed to the surface thereof.

9. 9. The polishing composition according to claim 1, wherein the abrasive grains have a degree of association of 2.3 or less.

10. 10. The polishing composition according to claim 1, wherein the pH is 1 to 4.

11. The polishing composition according to any one of claims 1 to 10, which is substantially free of an oxidizing agent.

12. 12. The polishing composition according to claim 1, wherein the object to be polished comprises at least one film selected from a silicon oxide film, a silicon nitride film, a polysilicon film, a titanium nitride film, and a single crystal silicon film.

13. 13. The polishing composition according to claim 1, wherein the object to be polished comprises: a silicon nitride film; and at least one of a silicon oxide film and a polysilicon film.

14. The polishing composition according to any one of claims 1 to 13, further comprising at least one additive selected from the group consisting of a cationic polymer, an anionic polymer, a nonionic polymer, a cationic surfactant, an anionic surfactant, a nonionic surfactant, and a sugar alcohol.

15. The polishing composition of claim 14 , wherein the additive does not include an alkynediol surfactant or an alkynediol ethoxylate surfactant.

16. A polishing method comprising polishing an object to be polished with the polishing composition according to any one of claims 1 to 15.

17. A method for manufacturing a semiconductor substrate, comprising the polishing method according to claim 16.

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