Polishing composition

Abstract

[Problem] The present application provides a polishing composition that can increase the ratio of the polishing rate of a layer containing a nitrogen atom-silicon atom bond such as silicon nitride to the polishing rate of a layer containing a silicon atom-oxygen atom bond such as silicon oxide, and ensure stability. [Solution] A polishing composition for polishing a polishing object, the polishing composition containing abrasive grains, an acid, and an aqueous carrier, the abrasive grains being colloidal silica having an organic acid fixed to the surface, the number of silanol groups of the abrasive grains being 3.50 / nm 2 Hereinafter, the value obtained by dividing the average primary particle diameter (nm) of the abrasive grains by the number of silanol groups (number / nm 2 ) is 8.00 or more, and the pH of the polishing composition is less than 6.0.

Description

Technical Field

[0001] This disclosure relates to compositions for grinding. Background Technology

[0002] In semiconductor device manufacturing processes, there is a challenge of grinding non-chemically reactive silicon nitride films at high speeds. Furthermore, there is also a challenge of increasing the grinding speed of silicon nitride films relative to that of silicon oxide films.

[0003] For example, Patent Document 1 mentions that conventional chemical mechanical polishing water-based dispersions require high polishing pressure and have problems with storage stability. It aims to provide a chemical mechanical polishing water-based dispersion that can significantly increase the polishing speed ratio of silicon nitride film to silicon oxide film and has good storage stability, as well as a chemical mechanical polishing method using the same.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2011 / 093153 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] The problem to be solved by this invention is to provide a technique for controlling the selectivity ratio and ensuring the stability of the polishing composition by means of other methods not disclosed in Patent Document 1. More specifically, the problem of the present invention is to provide a polishing composition that can increase the ratio of the polishing speed of layers containing nitrogen-silicon bonds, such as silicon nitride, to the polishing speed of layers containing silicon-oxygen bonds, such as silicon oxide, while ensuring stability.

[0009] Solution for solving the problem

[0010] This invention provides a grinding composition for grinding an object. The composition comprises abrasive grains, an acid, and an aqueous carrier. The abrasive grains are colloidal silica with an organic acid immobilized on their surface, and the abrasive grains have a silanol group number of 3.50 per nm. 2 Hereinafter, the average primary particle size (nm) of the abrasive grains is divided by the number of silanol units (units / nm). 2 The obtained value is above 8.00, and the pH of the grinding composition is less than 6.0.

[0011] The effects of the invention

[0012] According to this disclosure, a polishing composition can be provided that can increase the ratio of the polishing speed of a layer containing nitrogen-silicon atom bonds, such as silicon nitride, to the polishing speed of a layer containing silicon-oxygen atom bonds, such as silicon oxide, while ensuring stability. Detailed Implementation

[0013] In this specification, "X~Y" is used to mean "above X and below Y" as the lower and upper limits, encompassing the values ​​(X and Y) stated before and after it. When multiple "X~Y" are stated, such as "X1~Y1 or X2~Y2", "X1 and below Y1 or X2 and below Y2", disclosures with each value as the upper limit, disclosures with each value as the lower limit, and combinations of their upper and lower limits are all disclosed (i.e., become the legal basis for modification). Specifically, modifications to above X1, below Y2, below X1, above Y2, above X1~X2, and above X1~Y2 are all considered legal. It should be noted that "above X" means X or more than X, thus including the meaning of "greater than X". Similarly, "below Y" means Y or less than Y, thus including the meaning of "less than Y". Furthermore, unless otherwise specified, the operation and physical properties are measured at room temperature (20°C~25°C) / relative humidity 40~50%RH. It should be noted that the concentration described in this specification can be the concentration at the point of use (POU) or the concentration before dilution to the POU concentration. The dilution ratio can be 2 to 10 times. Additionally, it should be understood that this application discloses all embodiments and combinations of descriptions disclosed in this specification. That is, it should be understood that this can serve as the basis for modifications. Furthermore, when describing the content and concentration of each component, if two or more are included, their combined amount can be considered.

[0014] <Grinding Composition>

[0015] According to one embodiment of this disclosure, the abrasive comprises abrasive particles, an acid, and an aqueous carrier, wherein the abrasive particles are colloidal silica with an organic acid immobilized on their surface, and the abrasive particles have a silanol group number of 3.50 / nm. 2 The following is a description of an embodiment of this disclosure: A grinding composition is provided for grinding an object. The grinding composition comprises abrasive grains, an acid, and an aqueous carrier. The abrasive grains are colloidal silica with an organic acid immobilized on its surface, and the abrasive grains have a silanol group number of 3.50 per nm. 2 Hereinafter, the average primary particle size (nm) of the abrasive grains is divided by the number of silanol units (units / nm). 2The obtained value is 8.00 or higher, and the pH of the polishing composition is less than 6.0. Therefore, the ratio of the polishing speed of layers containing nitrogen-silicon bonds, such as silicon nitride, to the polishing speed of layers containing silicon-oxygen bonds, such as silicon oxide (also referred to as the "selectivity ratio" in this specification), can be increased, and stability can be ensured.

[0016] [Abrasive grains]

[0017] The grinding composition disclosed herein comprises abrasive grains. The abrasive grains have the function of mechanically grinding the object being ground. The abrasive grains contained in the grinding composition of this invention are colloidal silica with an organic acid immobilized on its surface, and the abrasive grains have a silanol group number of 3.50 / nm. 2 The following are methods for chemically introducing organic acids onto the surface of silica particles. There are no particular limitations. In addition to methods that first introduce thiol groups, alkyl groups, hydroxyl groups, aldehyde groups, etc., onto the surface of silica particles and then oxidize them into sulfonic acid groups, carboxylic acid groups, etc., there are also methods that introduce organic acid groups with bonding protecting groups onto the surface of silica particles and then remove the protecting groups.

[0018] As a specific example, if sulfonic acid groups are immobilized on silica particles, this can be done, for example, using the method described in "Sulfonicacid-functionalized silica through of thiol groups", Chem. Commun. 246-247 (2003). Specifically, this involves coupling silica particles with a silane coupling agent containing thiol groups, such as 3-mercaptopropyltrimethoxysilane, and then oxidizing the thiol groups using an oxidizing agent such as hydrogen peroxide. This results in silica particles with sulfonic acid groups immobilized on their surface. Alternatively, if carboxylic acid groups are immobilized on silica particles, this can be done, for example, using the method described in "Novel Silane Coupling Agents Containing a Photolabile 2-NitrobenzylEster 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 photoreactive 2-nitrobenzyl ester with silica particles and then subjecting them to light irradiation for surface modification, silica particles with carboxylic acid groups immobilized on the surface can be obtained.

[0019] According to one embodiment of the present invention, when introducing organic acid onto the surface of silica particles, silica particles with a relatively low proportion of silanol groups are used as the raw material. This significantly reduces the amount of organic acid chemically introduced onto the surface of the silica particles and suppresses the influence of unused organic acid release during the reaction on the grinding speed.

[0020] According to one embodiment of this disclosure, the number of silanol groups in the abrasive grains of the grinding composition is 3.40 per nm. 2 Below, 3.30 per nm 2 Below, 3.20 per nm 2 Below, 3.10 per nm 2 Below, 3.00 per nm 2 Below, 2.90 per nm 2 Below, 2.80 per nm 2 Below, 2.70 per nm 2 Below, 2.60 per nm 2 Below, 2.50 per nm 2 Below, 2.40 per nm 2 Below, less than 2.36 per nm 2 2.30 units / nm 2 Below, 2.20 per nm 2 Below, 2.10 per nm 2 Below, 2.00 per nm 2 Below, 1.90 per nm 2 Below, 1.80 per nm 2 Below or 1.70 per nm 2 The method for determining the silanol number of abrasive grains can be the method disclosed in the examples. If the silanol number of abrasive grains is too high, it may be unable to suppress the grinding speed of layers containing silicon-oxygen atom bonds, such as silicon oxide. According to one embodiment of this disclosure, the silanol number of abrasive grains in the grinding composition is 1.10 per nm. 2 Above, 1.20 units / nm 2 Above, 1.30 per nm 2 Above, 1.40 per nm 2 Above, 1.50 per nm 2 Above, 1.60 per nm 2 Above, 1.70 per nm 2 Above, 1.80 per nm 2 Above, 1.90 per nm 2 Above, 2.00 units / nm 2 Above, 2.10 per nm 2Above, 2.20 per nm 2 Above, 2.30 per nm 2 Above, 2.60 per nm 2 Above, 2.90 per nm 2 Above or 3.10 per nm 2 The above. If the number of silanol groups in the abrasive grains is too low, the grains may aggregate. Regarding controlling the number of silanol groups in the abrasive grains to 3.50 per nm... 2 The following methods, as examples, include heat treatment using an autoclave and controlling the molar ratio of organic acids introduced onto the surface of silica particles. As described above, by preparing raw materials with a low silanol content in the silica particles to which organic acids are to be introduced, it is also possible to prepare colloidal silica with a relatively high proportion of silanol content on the surface while suppressing the release of organic acids that may affect the grinding speed.

[0021] The silanol content of the abrasive particles can be obtained using silica particles before they are mixed with other components to prepare the polishing slurry (polishing composition), or silica particles sampled from the polishing slurry (polishing composition). Based on the assumption that the change before and after polishing slurry preparation is small, the silanol content of the silica particles can be either the silanol content of the silica particles before the preparation of the polishing slurry (polishing composition), or the silanol content of the silica particles sampled from the polishing slurry (polishing composition).

[0022] According to one embodiment of this disclosure, the lower limit of the average primary particle size of the abrasive grains in the grinding composition is 11.0 nm or more, 12.0 nm or more, 13.0 nm or more, 14.0 nm or more, 15.0 nm or more, 16.0 nm or more, 17.0 nm or more, 18.0 nm or more, 19.0 nm or more, 20.0 nm or more, 21.0 nm or more, 22.0 nm or more, 23.0 nm or more, 24.0 nm or more, or 25.0 nm. Above 26.0nm, 27.0nm, 28.0nm, 29.0nm, 30.0nm, 31.0nm, 32.0nm, 33.0nm, 34.0nm, 35.0nm, 36.0nm, 37.0nm, 38.0nm, 39.0nm, 40.0nm, 41.0nm, 42.0nm, or 43.0nm. By increasing the lower limit of the average primary particle size of the abrasive grains, the grinding speed of layers containing nitrogen-silicon atomic bonds, such as silicon nitride, can be increased while ensuring the necessary selectivity.

[0023] According to one embodiment of this disclosure, the upper limit of the average primary particle size of the abrasive grains in the grinding composition is 60.0 nm or less, 55.0 nm or less, 50.0 nm or less, 45.0 nm or less, 44.0 nm or less, 43.0 nm or less, 42.0 nm or less, 41.0 nm or less, 40.0 nm or less, 39.0 nm or less, 38.0 nm or less, 37.0 nm or less, 36.0 nm or less, 35.0 nm or less, 34.0 nm or less, 33.0 nm or less, 32.0 nm or less, 31.0 nm or less, 30.0 nm or less, 29.0 nm or less, 28.0 nm or less, 27.0 nm or less, 26.0 nm or less, 25.0 nm or less, 24.0 nm or less, 23.0 nm or less, 22.0 nm or less, or 21.0 nm or less. By appropriately setting the upper limit of the average primary particle size of the abrasive grains, the aggregation of abrasive grains can be suppressed. According to one embodiment of this disclosure, the average primary particle size of the abrasive grains in the grinding composition is 11.0 nm or more and 60.0 nm or less. The method for determining the average primary particle size is based on the method described in the examples.

[0024] According to one embodiment of this disclosure, the lower limit of the average secondary particle size of the abrasive grains in the polishing composition is 21 nm or more, 23 nm or more, 25 nm or more, 27 nm or more, 29 nm or more, 31 nm or more, 33 nm or more, 35 nm or more, 37 nm or more, 39 nm or more, 41 nm or more, 43 nm or more, 50 nm or more, 55 nm or more, or 60 nm or more. By increasing the lower limit of the average secondary particle size of the abrasive grains, the polishing speed of layers containing nitrogen-silicon atomic bonds, such as silicon nitride, can be increased while ensuring the necessary selectivity ratio. According to one embodiment of this disclosure, the upper limit of the average secondary particle size of the abrasive grains in the grinding composition is 100 nm or less, 95 nm or less, 90 nm or less, 85 nm or less, 80 nm or less, 75 nm or less, 70 nm or less, less than 70 nm, 65 nm or less, 60 nm or less, 55 nm or less, 50 nm or less, less than 50 nm, 49 nm or less, 48 ​​nm or less, 47 nm or less, 46 nm or less, 45 nm or less, 44 nm or less, 40 nm or less, or 35 nm or less. By appropriately setting the upper limit of the average secondary particle size of the abrasive grains, the aggregation of abrasive grains can be suppressed. According to one embodiment of this disclosure, the average secondary particle size of the abrasive grains in the grinding composition is 21 nm or more and 100 nm or less. The method for determining the average secondary particle size is based on the method described in the examples.

[0025] According to one embodiment of this disclosure, the average degree of association of the abrasive grains in the grinding composition (average secondary grain size (nm) / average primary grain size (nm)) is 1.10 or more, 1.20 or more, 1.30 or more, 1.40 or more, or 1.50 or more. According to one embodiment of this disclosure, the average degree of association of the abrasive grains in the grinding composition (average secondary grain size (nm) / average primary grain size (nm)) is 2.00 or less, 1.90 or less, 1.80 or less, 1.70 or less, 1.60 or less, 1.50 or less, or 1.40 or less.

[0026] According to one embodiment of this disclosure, the abrasive grains in the polishing composition have a negative Zeta potential. The value of this Zeta potential is, for example, -10 mV or less, -15 mV or less, -20 mV or less, -25 mV or less, -30 mV or less, -35 mV or less, -40 mV or less, -45 mV or less, or -50 mV or less. Alternatively, the value of this Zeta potential is, for example, -65 mV or more, -55 mV or more, -50 mV or more, -45 mV or more, -30 mV or more, or -25 mV or more. Furthermore, the value of this Zeta potential is, for example, -65 mV or more and -10 mV or less. By giving the abrasive grains in the polishing composition a Zeta potential within the aforementioned upper, lower, or range limits, the polishing speed of layers containing nitrogen-silicon atom bonds, such as silicon nitride, can be further increased. The Zeta potential of the abrasive grains in the polishing composition can be measured based on the method described in the examples. The zeta potential of abrasive grains can be adjusted by the amount of anionic groups (especially organic acid groups) present in the abrasive grains, the pH of the grinding composition, etc.

[0027] According to one embodiment of this disclosure, the concentration of abrasive particles in the polishing composition is 1.00% by mass or more, 1.50% by mass or more, greater than 1.95% by mass, 2.00% by mass or more, 2.50% by mass or more, 3.00% by mass or more, 3.10% by mass or more, 3.20% by mass or more, 3.30% by mass or more, 3.40% by mass or more, 3.50% by mass or more, 3.60% by mass or more, or 3.70% by mass or more. When the concentration of abrasive particles in the polishing composition is low, it may be impossible to increase the polishing speed of layers containing nitrogen-silicon atomic bonds, such as silicon nitride, and it may also be impossible to improve the selectivity. Furthermore, the polishing speed of layers containing nitrogen-silicon atomic bonds, such as silicon nitride, on a patterned wafer is generally estimated based on the polishing speed on a blank wafer, but if the abrasive particle concentration is low, a deviation may sometimes occur between the polishing speed on the blank wafer and the polishing speed on the patterned wafer (a decrease in the polishing speed on the patterned wafer). Therefore, the concentration of abrasive particles in the polishing composition is preferably 2.00% by mass or more. According to one embodiment of this disclosure, the concentration of abrasive particles in the grinding composition is 10.00% by mass or less, 9.00% by mass or less, 8.00% by mass or less, 7.00% by mass or less, 6.00% by mass or less, less than 6.00% by mass, less than 5.00% by mass, less than 5.00% by mass, less than 4.50% by mass, less than 4.00% by mass, or less than 4.00% by mass. According to one embodiment of this disclosure, the concentration of abrasive particles in the grinding composition is 1.00% by mass or more and 10.00% by mass or less. According to one embodiment of this disclosure, the concentration of abrasive particles in the grinding composition is greater than 1.95% by mass and less than 4.50% by mass. According to one embodiment of this disclosure, the concentration of abrasive particles in the grinding composition is 2.00% by mass or more and less than 4.00% by mass. When the concentration of abrasive particles in the grinding composition is less than 2.00% by mass, especially less than 1.95% by mass, it may not be possible to increase the grinding speed of layers containing nitrogen-silicon atom bonds, such as silicon nitride. When the concentration is 4.00% by mass or more, especially 4.50% by mass or more, the grinding speed of layers containing oxygen-silicon atom bonds may increase, and the selectivity ratio of the grinding speed of layers containing nitrogen-silicon atom bonds to that of layers containing oxygen-silicon atom bonds may decrease.

[0028] According to one embodiment of the present disclosure, the proportion of colloidal silica with organic acid fixed on its surface in the abrasive grains contained in the grinding composition is 90% or more by mass, 95% or more by mass, 98% or more by mass, 99% or more by mass, 99.5% or more by mass, or 99.9% or more by mass (up to 100% by mass).

[0029] According to one embodiment of the present disclosure, the surface of the abrasive grains constituting the grinding composition is modified with a silane coupling agent.

[0030] (Average primary particle size / silanol number)

[0031] According to one embodiment of this disclosure, the average primary particle size (nm) of the abrasive grains is divided by the number of silanol units (units / nm). 2 The resulting value (average primary particle size / silanol number) is above 8.00. "The average primary particle size (nm) of the abrasive grains divided by the silanol number (particles / nm)..." 2 The limitation of "a value of 8.00 or higher" holds true when the average primary particle size of the abrasive grains is sufficiently large and the silanol number of the abrasive grains is sufficiently small. By making the average primary particle size of the abrasive grains sufficiently large, the grinding speed of layers containing nitrogen-silicon atom bonds, such as silicon nitride, can be increased. On the other hand, by making the silanol number of the abrasive grains small, the grinding speed of layers containing silicon-oxygen atom bonds, such as silicon oxide, can be decreased. When the average primary particle size / silanol number is less than 8.00, it may be impossible to increase the ratio of the grinding speed of layers containing nitrogen-silicon atom bonds, such as silicon nitride, to the grinding speed of layers containing silicon-oxygen atom bonds, such as silicon oxide.

[0032] According to one embodiment of this disclosure, the average primary particle size / silanol number is 9.00 or more, 10.00 or more, 11.00 or more, 12.00 or more, 13.00 or more, 14.00 or more, 15.00 or more, 16.00 or more, 17.00 or more, 18.00 or more, or 19.00 or more. By making the average primary particle size / silanol number particularly 14.00 or more, the grinding speed of layers containing nitrogen-silicon atom bonds, such as silicon nitride, can be significantly increased, and the selectivity can be improved. According to one embodiment of this disclosure, the average primary particle size (nm) of the abrasive grains is divided by the number of silanols (number / nm). 2 The resulting values ​​are below 50.00, below 40.00, below 30.00, or below 20.00. By having this upper limit, there is a technical effect that is beneficial in suppressing the grinding speed of layers containing silicon atom-oxygen atom bonds.

[0033] It should be noted that the average primary particle size / silanol number is the particle size of the abrasive relative to the silanol number. Therefore, in this sense, the average secondary particle size / silanol number has also been studied as a limiting factor. However, the average secondary particle size refers to the average particle size of the particles in the primary particle association state of the abrasive. It is foreseeable that the number of particles forming this association state may vary. Therefore, it is considered appropriate to limit the parameter to the average primary particle size / silanol number.

[0034] [pH and pH adjusters]

[0035] In one embodiment of this disclosure, the pH of the polishing composition is less than 6.0. When the pH of the polishing composition is 6.0 or higher, the polishing speed of layers containing nitrogen-silicon atom bonds, such as silicon nitride, may become insufficient. Furthermore, the dissolution of colloidal silica may occur, leading to decreased stability. According to one embodiment of this disclosure, the pH of the polishing composition is 5.8 or lower, 5.6 or lower, 5.4 or lower, 5.2 or lower, 5.0 or lower, 4.8 or lower, 4.6 or lower, 4.4 or lower, 4.2 or lower, 4.0 or lower, 3.8 or lower, 3.6 or lower, 3.4 or lower, 3.2 or lower, or 3.0 or lower. According to one embodiment of this disclosure, the pH of the polishing composition is 1.0 or higher, 1.2 or higher, 1.4 or higher, 1.6 or higher, 1.8 or higher, 2.0 or higher, 2.2 or higher, 2.4 or higher, 2.6 or higher, or 2.8 or higher. According to one embodiment of this disclosure, the pH of the polishing composition is 1.0 or higher and less than 6.0. According to one embodiment of this disclosure, the pH of the grinding composition is 2.0 or higher and 5.0 or lower. In another embodiment, the grinding composition includes a pH adjuster for adjusting to the aforementioned upper limit pH, lower limit pH, or range pH. The pH adjuster may be an acid. 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, hexanoic acid, 3,3-dimethyl-butyric acid, 2-ethylbutyric acid, 4-methylvaleric acid, heptanoic acid, 2-methylhexanoic acid, 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, diethylene glycolic acid, 2-furancarboxylic acid, 2,5-furandicarboxylic acid, 3-furancarboxylic acid, 2-tetrahydrofurancarboxylic acid, methoxyacetic acid, methoxyphenylacetic acid, and phenoxyacetic acid.

[0036] In one embodiment of this disclosure, the grinding composition may contain an alkali for raising the pH of the grinding composition to prevent excessive pH reduction during pH adjustment. Examples of alkalis include aliphatic amines, aromatic amines, and other amines; organic bases such as quaternary ammonium hydroxide; hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide; hydroxides of alkaline earth metals (Group 2 elements); and ammonia.

[0037] In one embodiment of this disclosure, the amount of pH adjuster (e.g., acid) contained in the grinding composition is an amount suitable for setting the upper limit pH, lower limit pH, or range pH as described above. The pH of the grinding composition can be measured, for example, using a pH meter, and more specifically, based on the methods described in the examples.

[0038] [Liquid carrier]

[0039] The grinding composition of this invention comprises an aqueous carrier. The aqueous carrier preferably comprises water. According to one embodiment of this disclosure, the aqueous carrier is not limited to alcohols such as methanol, ethanol, and ethylene glycol; ketones such as acetone, etc., and the water content in the aqueous carrier is 90% by mass or more, 95% by mass or more, 98% by mass or more, 99% by mass or more, 99.5% by mass or more, or 99.9% by mass or more (up to a maximum of 100% by mass).

[0040] [Other ingredients]

[0041] According to one embodiment of this disclosure, the grinding composition may further include or exclude other components such as water-soluble polymers, complexing agents, metal corrosion inhibitors, preservatives, reducing agents, and surfactants, as needed.

[0042] (preservative)

[0043] According to one embodiment of this disclosure, the grinding composition can be an aqueous liquid, thus allowing microorganisms (bacteria, molds) to easily proliferate, potentially leading to compromised stability during long-term storage and use. Therefore, a preservative is added, which may contain a preservative that inhibits the proliferation of microorganisms (bacteria, molds). Examples of such preservatives include isothiazolinite preservatives such as 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one; parabens and phenoxyethanol, etc. These preservatives and fungicides can be used individually or in combination of two or more.

[0044] According to one embodiment of this disclosure, the grinding composition, for example, does not contain any of the inorganic salts such as ammonium salts and organic salts (below the detection limit), or even if it contains at least one of them, it is less than 0.05% by mass or less than 5 mM. This embodiment improves the selectivity. The ammonium salt can be an inorganic acid salt or an organic acid salt. Examples of inorganic acid salts include ammonium sulfate, ammonium nitrate, ammonium chloride, ammonium fluoride, ammonium borate, ammonium carbonate, diammonium bicarbonate, ammonium dihydrogen carbonate, ammonium hypophosphite, ammonium phosphite, and ammonium phosphate. Examples of organic acid salts include ammonium formate, ammonium acetate, ammonium propionate, ammonium butyrate, ammonium valerate, ammonium benzoate, ammonium glycolate, ammonium salicylate, ammonium glycerate, ammonium oxalate, ammonium malonate, ammonium succinate, ammonium glutamate, ammonium adipate, ammonium heptaate, ammonium maleate, ammonium phthalate, ammonium malate, ammonium tartrate, diammonium hydrogen citrate, triammonium citrate, ammonium lactate, and ammonium diethylene glycolate.

[0045] [Object to be ground]

[0046] In one embodiment of this disclosure, the workpiece being ground has a layer comprising oxygen-silicon bonds. Examples of such a layer include TEOS-type silica (hereinafter also simply referred to as "TEOS" or "silicon dioxide") formed using tetraethyl orthosilicate as a precursor, HDP (High Density Plasma), USG (Undoped Silicate Glass), PSG (Phosphorus Silicate Glass), BPSG (Boron-Phospho Silicate Glass), or RTO (Rapid Thermal Oxidation). The TEOS film can be formed by plasma CVD.

[0047] In one embodiment of this disclosure, the object to be ground has a layer comprising nitrogen-silicon atomic bonds. Examples of such a layer include silicon nitride films or SiCN (silicon carbonitride).

[0048] [Method for manufacturing the grinding composition]

[0049] According to one embodiment of this disclosure, the grinding composition can be obtained, for example, by stirring and mixing the abrasive particles disclosed in this specification, an acid, an aqueous carrier, and other additives added as needed. Details of each component are as described above. There are no particular limitations on the temperature during mixing, but it is preferably 10°C or higher and 40°C or lower; heating may also be used to improve the dissolution rate. Furthermore, there are no particular limitations on the mixing time, as long as uniform mixing is achieved.

[0050] [Grinding methods and semiconductor substrate manufacturing methods]

[0051] The polishing compositions disclosed in this specification are particularly suitable for polishing workpieces having layers containing nitrogen-silicon bonds, such as silicon nitride. Therefore, this specification provides a polishing method for polishing workpieces having layers containing nitrogen-silicon bonds, such as silicon nitride, using the polishing compositions disclosed in this specification. The polishing compositions disclosed in this specification are particularly suitable for polishing workpieces having layers containing oxygen-silicon bonds and layers containing nitrogen-silicon bonds. Therefore, this specification provides a polishing method for polishing workpieces having layers containing oxygen-silicon bonds and layers containing nitrogen-silicon bonds using the polishing compositions disclosed in this specification.

[0052] Grinding of the object to be ground can be done using a general grinding apparatus, but it is preferable to use a grinding apparatus that has the characteristics of being able to precisely control the grinding conditions and stably ensure the in-plane uniformity of the wafer. "Stabilizing the in-plane uniformity of the wafer" can be determined, for example, by the magnitude of the non-uniformity value obtained by the following formula (Equation 1), based on the average value (R) of the grinding speed at 49 points along the diameter direction of the wafer and the standard deviation (σ) of the grinding speed at 49 points.

[0053] Non-uniformity (%) = (σ / R) × 100 (Equation 1).

[0054] The aforementioned unevenness (%) is, for example, below 5%, below 3%, or below 1%. As a lower limit, it exceeds 0% in reality.

[0055] As a polishing apparatus, a general polishing apparatus can be used, which includes a support for holding a substrate with the object to be polished, a motor capable of changing rotation speed, and a polishing plate for attaching a polishing pad (polishing cloth). As the polishing pad, general non-woven fabrics, polyurethane, and porous fluoropolymers can be used without particular limitations. It is preferable to perform a troughing process on the polishing pad to collect polishing fluid. Regarding polishing conditions, for example, the rotational speed of the polishing plate and the carrier (polishing head) is preferably 10 rpm or more and 200 rpm or less, 20 rpm or more and less than 117 rpm, 30 rpm or more and 110 rpm or less, 40 rpm or more and 100 rpm or less, or 50 rpm or more and 90 rpm or less. If the polishing composition disclosed in this specification is used, the polishing speed of the object to be polished can be increased even if the rotational speed of the polishing plate and the carrier (polishing head) in the polishing apparatus is low. The pressure applied to the substrate having the object to be polished (polishing pressure) is preferably 0.5 psi or more and 10 psi or less, more preferably 1.0 psi or more and 6.0 psi or less, even more preferably 1.5 psi or more and 4.0 psi or less, even more preferably 2.0 psi or more and 3.8 psi or less, even more preferably 2.1 psi or more and 3.5 psi or less. Even more preferably 2.2 psi or more and 3.0 psi or less. In particular, when the pressure applied to the substrate having the object to be polished (polishing pressure) is 2.1 psi or more, a polishing composition that can increase the polishing speed ratio of layers containing nitrogen-silicon bonds, such as silicon nitride, to layers containing silicon-oxygen bonds, such as silicon oxide, and ensures stability can be provided, thereby increasing throughput (typically the number of wafers that can be processed per unit time).

[0056] There are no particular limitations on the method of supplying the abrasive composition to the abrasive pad; for example, a continuous supply method using a pump or the like can be employed. The supply amount is not limited, but it is preferable that the surface of the abrasive pad is always covered by the abrasive composition disclosed herein.

[0057] [Grinding speed]

[0058] The grinding speeds disclosed in this specification can be determined using the conditions described in the examples.

[0059] The polishing composition of this invention is capable of polishing layers containing nitrogen-silicon bonds at high polishing speeds. According to one embodiment of this disclosure, the polishing composition has the characteristic of setting the polishing speed of the nitrogen-silicon bond-containing layer to 300 Å / min or more, 320 Å / min or more, 340 Å / min or more, 360 Å / min or more, 380 Å / min or more, 400 Å / min or more, 420 Å / min or more, 440 Å / min or more, 460 Å / min or more, 480 Å / min or more, 500 Å / min or more, 520 Å / min or more, 540 Å / min or more, or 560 Å / min or more. Polishing chemically unreactive silicon nitride at high speeds can improve process productivity and is therefore preferred. According to one embodiment of this disclosure, the polishing composition has the characteristic of setting the polishing speed of the nitrogen-silicon bond-containing layer to 1000 Å / min or less, 800 Å / min or less, or 600 Å / min or less. It should be noted that 1 Å = 0.1 nm.

[0060] The polishing composition of this invention can polish layers containing oxygen-silicon bonds at low polishing speeds. According to one embodiment of this disclosure, the polishing composition has the characteristic of setting the polishing speed of the layer containing oxygen-silicon bonds to 200 Å / min or less, 180 Å / min or less, 160 Å / min or less, 140 Å / min or less, 120 Å / min or less, 100 Å / min or less, 90 Å / min or less, 80 Å / min or less, 70 Å / min or less, or 60 Å / min or less. According to another embodiment of this disclosure, the polishing composition has the characteristic of setting the polishing speed of the layer containing oxygen-silicon bonds to 30 Å / min or more, 40 Å / min or more, 50 Å / min or more, or greater than 55 Å / min. By having such lower limits, a second layer containing nitrogen-silicon bonds can be polished at high speed in processes such as polishing high-k gate insulating films, and a process window suitable for controlling the amount of polishing of the first layer containing oxygen-silicon bonds is ensured; therefore, this polishing composition is preferred. Here, the process window refers to the process width required for, for example, the small-scale polishing of a layer containing oxygen-silicon bonds (e.g., TEOS) that forms the substrate. If the polishing speed is too slow, the polishing time becomes longer, leading to a decrease in productivity; if the polishing speed is too fast, the amount of material removed becomes difficult to control. For example, when setting the polishing speed to remove 50 Å of the TEOS film, at a polishing speed of 500 Å / min (too high), a 1-second shift in polishing time results in an 8 Å shift in the amount of material removed; at a polishing speed of 50 Å / min, even a 1-second shift in polishing time results in a shift in the amount of material removed that is controlled to less than 1 Å. In processes like polishing high-k gate insulating films, where small-scale polishing of layers containing oxygen-silicon bonds (e.g., TEOS) is necessary, while a high polishing speed increases productivity, it is preferable to adjust the speed to prevent it from becoming too high.

[0061] [Selection Ratio]

[0062] According to one embodiment of this disclosure, the polishing composition has the characteristic that the ratio of the polishing speed (Å / min) of the layer containing nitrogen-silicon bonds to the polishing speed (Å / min) of the layer containing oxygen-silicon bonds is greater than 3.40, greater than 4.00, 4.20 or more, 4.40 or more, greater than 4.40, 4.60 or more, 4.80 or more, 5.00 or more, 5.20 or more, 5.40 or more, greater than 5.53, 5.60 or more, 5.80 or more, 6.00 or more, 6.20 or more, 6.40 or more, 6.60 or more, 6.80 or more, 7.00 or more, 7.20 or more, 7.40 or more, 7.60 or more, 7.70 or more, 8.00 or more, 8.20 or more, 8.40 or more, 8.60 or more, or 8.80 or more. According to one embodiment of this disclosure, the polishing composition has the characteristic that the ratio of the polishing rate (Å / min) of the layer containing nitrogen-silicon bonds to the polishing rate (Å / min) of the layer containing oxygen-silicon bonds is set to 9.00 or less, less than 8.96, 8.50 or less, 8.00 or less, 7.50 or less, 7.00 or less, 6.50 or less, 6.00 or less, 5.60 or less, or 5.00 or less. By setting such an upper limit on the selectivity ratio, particularly by setting the selectivity ratio to 8.00 or less, it is possible to polish the second layer containing nitrogen-silicon bonds at high speed in processes such as polishing high-k gate insulating films, and a process window suitable for controlling the amount of polishing of the first layer containing oxygen-silicon bonds is ensured. Therefore, this polishing composition is preferred.

[0063] This disclosure includes the following methods and forms.

[0064] 1. A grinding composition for grinding an object, the grinding composition comprising abrasive grains, an acid, and an aqueous carrier, wherein the abrasive grains are colloidal silica with an organic acid immobilized on its surface, and the abrasive grains have a silanol group number of 3.50 / nm. 2 Hereinafter, the average primary particle size (nm) of the abrasive grains is divided by the number of silanol units (units / nm). 2 The obtained value is above 8.00, and the pH of the grinding composition is less than 6.0.

[0065] 2. The polishing composition according to 1, wherein the object to be polished has a layer comprising nitrogen-silicon bonds.

[0066] 3. The grinding composition according to 2, wherein the grinding object has a layer containing oxygen-silicon bonds and a layer containing nitrogen-silicon bonds.

[0067] 4. The polishing composition according to 3, wherein the ratio of the polishing rate (Å / min) of the layer containing nitrogen-silicon bonds to the polishing rate (Å / min) of the layer containing oxygen-silicon bonds is greater than 3.40.

[0068] 5. The grinding composition according to any one of 1 to 4, wherein the pH is 2.0 or higher and 5.0 or lower.

[0069] 6. The grinding composition according to any one of 1 to 5, wherein the number of silanol groups in the abrasive grains is 2.00 per nm. 2 the following.

[0070] 7. The grinding composition according to any one of 1. to 6, wherein the concentration of the abrasive particles is 2.00% by mass or more.

[0071] 8. The grinding composition according to any one of 1. to 7, wherein the ratio of the average secondary particle size (nm) of the abrasive grains to the average primary particle size (nm) of the abrasive grains is 1.8 or less.

[0072] [Example]

[0073] The present disclosure is further described in detail using the following examples and comparative examples. However, the technical scope of the present disclosure is not limited to the following examples. It should be noted that unless otherwise specified, "%" and "parts" refer to "mass %" and "parts by mass," respectively. Furthermore, in the following examples, unless otherwise specified, the operation is carried out at room temperature (above 20°C and below 25°C) and relative humidity (above 40%RH and below 50%RH). It should be noted that the physical properties are measured as follows.

[0074] <Average primary grain size of abrasive grains>

[0075] The average primary particle size of the abrasive particles was calculated from the specific surface area of ​​silica particles and the density of the abrasive particles, measured using a Micromeritics “Flow Sorb II 2300” based on the BET method.

[0076] <Average secondary grain size of abrasive particles>

[0077] The average secondary particle size of the abrasive grains was measured as the volume average particle size (arithmetic mean particle size based on volume; Mv) using a dynamic light scattering particle size / particle size distribution device UPA-UT151 (manufactured by Nikkiso Corporation).

[0078] <Zeta potential of abrasive particles>

[0079] The Zeta potential of the abrasive particles in the grinding composition was calculated as follows: Zetasizer Nano, manufactured by Malvern Panalytical Co., Ltd., was measured using laser Doppler method (electrophoretic light scattering method) at a measurement temperature of 25°C, and the obtained data was analyzed using the Smoluchowski formula.

[0080] <pH of the grinding composition>

[0081] The pH of the grinding composition was determined by using a glass electrode hydrogen ion concentration indicator (Horiba Manufacturing Co., Ltd., model: F-23) and calibrating at three points using standard buffer solutions (phthalate pH buffer pH: 4.01 (25°C), neutral phosphate pH buffer pH: 6.86 (25°C), and carbonate pH buffer pH: 10.01 (25°C)). The glass electrode was then placed in the grinding composition, and the value after stabilization for more than 2 minutes was taken as the pH value.

[0082] <Method for Calculating the Silanol Base Number>

[0083] Number of silanol groups per unit surface area of ​​abrasive grains (unit: cells / nm) 2 After measuring or calculating each parameter using the following measurement or calculation methods, calculate the result using the following method.

[0084] More specifically, in the following formula, C represents the total mass of the abrasive particles, and S represents the BET specific surface area of ​​the abrasive particles. More specifically, firstly, 1.50g of the abrasive particles (as the solid component) is collected in a 200ml beaker, and 100ml of pure water is added to prepare a slurry. Then, 30g of sodium chloride is added to dissolve it. Next, 1N hydrochloric acid is added to adjust the pH of the slurry to 3.0-3.5, and then pure water is added until the slurry reaches 150ml.

[0085] For this slurry, the pH was adjusted to 4.0 at 25°C using an automatic titration apparatus (Hiranuma Sangyo Co., Ltd., COM-1700). Then, the volume V[L] of the 0.1N sodium hydroxide solution required to raise the pH from 4.0 to 9.0 was determined by pH titration. The average silanol group density (silanol number) can be calculated using the following formula.

[0086] ρ=(c×V×N A ) / (C×S)

[0087] In the above formula,

[0088] ρ represents the average silanol group density (number of silanol groups) (number / nm) 2 );

[0089] c represents the concentration (mol / L) of the sodium hydroxide solution used in the titration;

[0090] V represents the volume (L) of sodium hydroxide solution required to raise the pH from 4.0 to 9.0;

[0091] N A This represents Avogadro's constant (numbers / mol);

[0092] C represents the total mass of the abrasive particles (solid content) (g);

[0093] S represents the weighted average of the BET specific surface area of ​​the abrasive particles (nm). 2 / g). The BET specific surface area is the value of the specific surface area of ​​abrasive particles based on the BET method, measured using the "Macsorb (registered trademark) HM model-1210" manufactured by Mounttech Co., Ltd.

[0094] <Preparation of Grinding Compositions>

[0095] (Example 1)

[0096] A polishing composition was prepared by mixing colloidal silica, acid, and water as abrasive particles, as shown in Table 1. Specifically, the polishing composition of Example 1 has an average primary particle size of 31.2 nm, an average secondary particle size of 43 nm, and a silanol number of 1.64 per nm. 2 The sulfonic acid-immobilized colloidal silica, maleic acid, and water were mixed according to the compositions shown in Table 1.

[0097] (Examples 2-3, Comparative Example 1)

[0098] The size and silanol number of the sulfonic acid-immobilized colloidal silica were changed as shown in Table 1. Otherwise, the grinding composition was prepared in the same manner as in Example 1.

[0099] (Comparative Example 2)

[0100] The type of colloidal silica was changed to unmodified colloidal silica with unimmobilized sulfonic acid on the surface, i.e., the colloidal silica shown in Table 1. Otherwise, the grinding composition was prepared in the same manner as in Example 1.

[0101] (Example 4)

[0102] The concentration of colloidal silica was varied as shown in Table 1, and the grinding composition was prepared in the same manner as in Example 1.

[0103] (Example 5)

[0104] The concentration of colloidal silica was varied as shown in Table 1, and the grinding composition was prepared in the same manner as in Example 1.

[0105] [evaluate]

[0106] Prepare the following (1) and (2) as the objects to be ground, and grind them under the following conditions:

[0107] (1) Silicon nitride film (SiN film): A silicon wafer (200 mm, blank wafer) with a silicon nitride film (SiN film) with a thickness of 2000 Å formed on its surface.

[0108] (2) Silicon oxide film (TEOS film): A silicon wafer (200 mm, blank wafer) on which a TEOS type silicon oxide (SiO2) film with a thickness of 10000 Å is formed on its surface.

[0109] (Grinding apparatus and grinding conditions)

[0110] Grinding apparatus: Mirra 200mm CMP single-sided grinding apparatus manufactured by Applied Materials.

[0111] Abrasive pad: Rigid polyurethane pad IC1010 manufactured by Nitta Hass Corporation

[0112] Grinding pressure: 2.5 psi (1 psi = 6894.76 Pa)

[0113] Grinding plate speed: 47 rpm

[0114] Grinding head (carrier) speed: 43 rpm

[0115] Supply of grinding composition: sag

[0116] Grinding composition supply rate: 200 mL / min

[0117] Grinding time: 60 seconds.

[0118] <Grinding Speed>

[0119] For each object to be ground, the thickness before and after grinding was determined using an optical film thickness gauge (ASET-f5x: manufactured by KLA-Tencor Co., Ltd.). The film thickness was determined using an optical film thickness gauge (ASET-f5x: manufactured by KLA-Tencor Co., Ltd.).

[0120] For each object to be ground, the grinding speed is calculated by dividing the difference in film thickness before and after grinding [(thickness before grinding) - (thickness after grinding)] by the grinding time.

[0121] <Dispersion Stability>

[0122] Place the grinding composition into a 100ml plastic bottle and store at 25°C for one week. After storage, visually inspect the sample to confirm the presence or absence of precipitate; the presence of precipitate indicates aggregation.

[0123] Good: No sediment was produced.

[0124] Aggregation: produces precipitates.

[0125] [Table 1]

[0126]

[0127] <Inspection>

[0128] According to the embodiments, a polishing composition can be provided that can increase the ratio of the polishing speed of a layer containing nitrogen-silicon atom bonds, such as silicon nitride, to the polishing speed of a layer containing silicon-oxygen atom bonds, such as silicon oxide, and ensure stability.

[0129] Comparing Example 1 and Example 2, Example 2 shows a superior selection ratio, but the overall grinding speed of SiN and TEOS decreases. Therefore, it can be said that the grinding composition of Example 1 is superior.

[0130] Comparing Example 1 and Example 3, Example 1 is superior from the viewpoints of grinding speed and productivity.

[0131] The abrasive concentration of the grinding composition in Example 4 is lower than that in Example 1. Therefore, the grinding speed of TEOS in Example 4 is suppressed compared to that in Example 1, but the grinding speed of SiN is also slower. As a result, the selectivity of Example 4 is lower than that of Example 1. Therefore, it can be said that the grinding composition of Example 1 is superior to that of Example 4.

[0132] The abrasive concentration of the grinding composition in Example 5 is higher than that in Example 1. Example 5 was prepared with the expectation of increasing the grinding speed of SiN, but it was unexpected that the grinding speed of SiN reached its limit. On the other hand, the grinding speed of TEOS increased, resulting in a decrease in selectivity. Therefore, it can be said that the grinding composition of Example 1 is superior to that of Example 5.

[0133] As can be seen from the above, the grinding composition of Example 1 is the best among all examples.

[0134] Comparative Example 1 uses silanol groups greater than 3.50 per nm. 2 Average primary particle size (nm) divided by the number of silanol particles (nm) 2Examples of abrasive grains with values ​​less than 8.00 were obtained. As a result, the grinding speed of TEOS increased, but the selectivity could not be improved. Therefore, these parameters are considered important in order to solve the problems disclosed in this specification.

[0135] The abrasive grains used in the grinding composition of Comparative Example 2 were unmodified, resulting in abrasive grain aggregation.

[0136] This application is based on Japanese Patent Application No. 2025-051438, filed on March 26, 2025, the entire disclosure of which is incorporated herein by reference.

Claims

1. A grinding composition for grinding an object. The grinding composition comprises abrasive particles, an acid, and an aqueous carrier. The abrasive particles are colloidal silica with organic acids fixed on their surface. The abrasive grains have 3.50 silanol groups per nm. 2 the following, The average primary particle size (nm) of the abrasive grains divided by the number of silanol units (per nm) 2 The obtained value is 8.00 or higher. The pH of the grinding composition is less than 6.

0.

2. The grinding composition according to claim 1, wherein, The object to be ground has a layer containing nitrogen-silicon bonds.

3. The grinding composition according to claim 2, wherein, The object to be ground has a layer containing oxygen-silicon bonds and a layer containing nitrogen-silicon bonds.

4. The grinding composition according to claim 3, wherein, The ratio of the grinding rate (Å / min) of the layer containing nitrogen-silicon bonds to the grinding rate (Å / min) of the layer containing oxygen-silicon bonds is greater than 3.

40.

5. The grinding composition according to claim 1, wherein, The pH is above 2.0 and below 5.

0.

6. The grinding composition according to claim 1, wherein, The abrasive grains have 2.00 silanol groups per nm. 2 the following.

7. The grinding composition according to claim 1, wherein, The concentration of the abrasive particles is 2.00% by mass or more.

8. The grinding composition according to claim 1, wherein, The ratio of the average secondary particle size (nm) of the abrasive grains to the average primary particle size (nm) of the abrasive grains is 1.8 or less.

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