Grinding liquid and grinding method

Abstract

A polishing liquid comprising: abrasive particles including a metal oxide; a hydroxy acid compound selected from the group consisting of a hydroxy acid having a structure represented by the following general formula (A1) and a salt thereof; and water. 11 represents a hydrogen atom or a hydroxyl group, R 12 represents a hydrogen atom, an alkyl group or an aryl group, n11 represents an integer greater than 0, and n12 represents an integer greater than 0. 11 and R 12 The exception is when both are hydrogen atoms. #imgabs0#

Description

Technical Field

[0001] The invention relates to a grinding liquid and a grinding method using the grinding liquid. Background Art

[0002] In the field of semiconductor manufacturing, as the performance of ultra-LSI devices increases, the miniaturization technology that is an extension of the existing technology has gradually become a limitation in terms of both high integration and high speed. Therefore, a technology that promotes the miniaturization of semiconductor elements while also achieving high integration in the vertical direction (i.e., a technology that multilayers the wiring) is being developed. This technology is disclosed, for example, in the following patent document 1.

[0003] In the process of manufacturing devices with multilayered wiring, one of the most important technologies is CMP (chemical mechanical polishing) technology. CMP technology is a technology that flattens the surface of a substrate after forming a ground material on a substrate by chemical vapor deposition (CVD) or the like to obtain a substrate. If there are irregularities on the surface of the flattened substrate, it may cause problems such as inability to focus during the exposure process or inability to fully form a fine wiring structure. In the manufacturing process of the device, CMP technology is also applicable to the process of forming an element separation area by grinding plasma oxide (BPSG, HDP-SiO2, p-TEOS, etc.), the process of forming an interlayer insulating material, and the process of flattening a plug (such as an Al / Cu plug) after embedding silicon oxide into a metal wiring.

[0004] Previous technical literature

[0005] Patent Literature

[0006] Patent Document 1: U.S. Patent No. 4,944,836 Summary of the invention

[0007] Technical issues to be solved by the invention

[0008] In the process of forming the element separation region on the substrate, silicon oxide is formed by CVD or the like in a manner of filling the grooves pre-set on the substrate surface. Then, the surface of the silicon oxide is flattened by CMP, thereby forming the element separation region. In the case of forming silicon oxide on a substrate having a surface for obtaining the element separation region, concavities and convexities corresponding to the concavities and convexities of the substrate are also generated on the surface of the silicon oxide. In the grinding of the surface having concavities and convexities, the convex portions are preferentially removed, and on the other hand, the concavities are slowly removed to achieve flattening.

[0009] In order to improve the yield of semiconductor production, it is preferred to remove the unnecessary part of silicon oxide formed on the substrate as quickly as possible. For example, when shallow trench isolation (STI) is used to narrow the width of the element separation area, it is required to remove the unnecessary part of silicon oxide provided on the substrate at a high polishing speed.

[0010] As the form of the concavoconvex formed on the substrate surface, there are various forms, and the width of the concavoconvex caused by the wiring width, the height of the concavoconvex, and the direction of the wiring can be different according to the purpose of each process or device. However, in the past, when the same grinding liquid was used, even if one substrate could be well ground, sometimes it was not necessarily possible to grind other substrates equally well. Therefore, for the grinding liquid, it is required to obtain a high grinding speed regardless of the concavoconvex state on the ground surface of the substrate.

[0011] One aspect of the present invention is to solve the above-mentioned problems and to provide a polishing liquid which can achieve a high polishing rate when polishing a surface having irregularities, regardless of the irregularities. Another aspect of the present invention is to provide a polishing method using the polishing liquid.

[0012] Means for solving technical problems

[0013] One aspect of the present invention provides a polishing liquid comprising: abrasive particles comprising a metal oxide; a hydroxy acid compound selected from at least one of the group consisting of hydroxy acids having a structure represented by the following general formula (A1) and salts thereof; and water.

[0014]

[0015] [Where R 11 represents a hydrogen atom or a hydroxyl group, R 12 represents a hydrogen atom, an alkyl group or an aryl group, n11 represents an integer greater than 0, and n12 represents an integer greater than 0. 11 and R 12 The exception is when both are hydrogen atoms.]

[0016] Another aspect of the present invention provides a polishing method including the step of polishing a material to be polished using the polishing liquid.

[0017] According to the polishing liquid and the polishing method, when polishing a surface to be polished having irregularities, a high polishing rate can be obtained regardless of the state of the irregularities.

[0018] Effects of the Invention

[0019] According to one aspect of the present invention, a polishing liquid can be provided, which can obtain a high polishing speed when polishing a polished surface having uneven surfaces, regardless of the uneven state. And, according to another aspect of the present invention, a polishing method using the polishing liquid can be provided. These polishing liquids and polishing methods are used to polish an insulating material (e.g., silicon oxide) provided on the surface of a substrate (e.g., a semiconductor wafer). DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and various modifications can be implemented within the scope of the gist thereof.

[0021] <Definition>

[0022] In this specification, the numerical range shown using "~" indicates the range including the numerical values ​​recorded before and after "~" as the minimum and maximum values, respectively. In the numerical range recorded in stages in this specification, the upper limit or lower limit of the numerical range of a certain stage can be arbitrarily combined with the upper limit or lower limit of the numerical range of other stages. In the numerical range recorded in this specification, the upper limit or lower limit of the numerical range can be replaced by the value shown in the embodiment. "A or B" means that any one of A and B can be included, or both can be included. Unless otherwise specified, the materials exemplified in this specification can be used alone, or two or more can be used in combination. In this specification, when there are multiple substances equivalent to each component in the composition, unless otherwise specified, the amount of each component used in the composition refers to the total amount of the multiple substances present in the composition. In this specification, regarding the term "film", when observed as a top view, in addition to the structure of the shape formed on the entire surface, it also includes the structure of the shape formed locally. In this specification, the term "process" refers not only to an independent process but also to a process that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved.

[0023] <Polishing fluid>

[0024] The polishing liquid according to the present embodiment contains: abrasive grains including metal oxide; a hydroxy acid compound selected from the group consisting of hydroxy acids having a structure represented by the following general formula (A1) and salts thereof; and water. The polishing liquid according to the present embodiment can be used as a CMP polishing liquid (polishing liquid for CMP).

[0025]

[0026] [Where R 11 represents a hydrogen atom or a hydroxyl group, R 12represents a hydrogen atom, an alkyl group or an aryl group, n11 represents an integer greater than 0, and n12 represents an integer greater than 0, wherein R 11 and R 12 The exception is when both are hydrogen atoms.]

[0027] According to the polishing liquid involved in the present embodiment, when polishing a polished surface with unevenness, a high polishing speed can be obtained regardless of the unevenness state. For example, when polishing various substrates whose surface unevenness widths are different due to wiring widths, a high polishing speed can be obtained regardless of the unevenness width. This polishing liquid has high versatility and can be used to polish various substrates with different surface states. The above-mentioned hydroxy acid compound is easily and strongly adsorbed on the surface of the abrasive containing metal oxide, and increases the activity of the abrasive surface, from which it can be inferred that a high polishing speed can be obtained regardless of the unevenness state. However, the main factors for obtaining the above-mentioned effects are not limited to this content. According to the polishing liquid involved in the present embodiment, when polishing a polished surface of silicon oxide with unevenness, for example, under the condition of L / S (Line / Space) = 50 / 50μm, it can be obtained The above polishing speed can be obtained under the condition of L / S = 20 / 80μm Above grinding speed.

[0028] However, in the past, when grinding a silicon oxide wafer having a grinding surface without projections and recesses (silicon oxide control wafer coated wafer), a high grinding speed of silicon oxide can be achieved. In contrast, when grinding a silicon oxide wafer having a grinding surface with projections and recesses (silicon oxide pattern wafer), a high grinding speed of silicon oxide cannot sometimes be achieved. On the other hand, according to the polishing liquid involved in the present embodiment, when grinding a grinding surface without projections and recesses, a high grinding speed of an insulating material (such as silicon oxide) can be achieved, and when grinding a grinding surface with projections and recesses, a high grinding speed can be obtained regardless of the projections and recesses. For example, according to the polishing liquid involved in the present embodiment, when grinding a grinding surface of silicon oxide without projections and recesses, a high grinding speed can be obtained. Above (preferably More preferably According to the polishing liquid involved in this embodiment, a high polishing rate can be obtained in both the case of polishing a polished surface with unevenness and the case of polishing a polished surface without unevenness, and a high polishing rate can be obtained regardless of the surface state of the polished surface (the presence or absence of unevenness, density, etc.). In addition, there are many unexplained parts about the mechanism of silicon oxide being polished by CMP, and the cause of this phenomenon is still unclear.

[0029] However, if a polishing fluid with a high polishing speed for insulating materials (such as silicon oxide) is used, the polished surface becomes rough after polishing, and sometimes the flatness deteriorates. Therefore, the polishing process of the insulating material is divided into two stages, and sometimes the production efficiency is improved by using different types of polishing fluids in each process. In the first process (roughening process), most of the insulating material is removed by using a polishing fluid with a high polishing speed for the insulating material. In the second process (finishing process), the insulating material is slowly removed, and the polished surface is finished in a manner that becomes sufficiently flat. In the case where the CMP for the insulating material is divided into two or more stages, since the high polishing speed takes precedence over the flatness in the first process, the reduction in the polishing speed may lead to a reduction in productivity. On the other hand, according to the polishing fluid involved in this embodiment, since a high polishing speed can be obtained regardless of the concave-convex state, the reduction in productivity can be suppressed even when the CMP for the insulating material (such as silicon oxide) is divided into two or more stages.

[0030] (Abrasive particles)

[0031] The abrasive grains include metal oxides. The metal oxides may include cerium oxide (ceria), aluminum oxide, silicon dioxide, titanium dioxide, zirconium oxide, magnesium oxide, mullite, etc. The constituent components of the abrasive grains may be used alone or in combination of two or more. In the case of grinding a surface to be ground with unevenness, the abrasive grains preferably include cerium oxide from the viewpoint of easily obtaining a high grinding speed regardless of the unevenness state.

[0032] The grinding liquid using abrasive grains containing cerium oxide has the advantage of generating fewer grinding scratches on the ground surface. In the past, from the perspective of easily achieving a high grinding speed of the ground material (e.g., insulating materials such as silicon oxide), grinding liquids containing silicon dioxide particles were widely used as abrasive grains. However, the grinding liquid using silicon dioxide particles usually has the problem of easily generating grinding scratches on the ground surface. In devices with fine patterns with a wiring width of 45nm or later, even fine scratches that did not pose a problem in the past may affect the reliability of the device.

[0033] When cerium oxide is used, the abrasive grains preferably include polycrystalline cerium oxide having grain boundaries (e.g., polycrystalline cerium oxide having a plurality of microcrystals surrounded by grain boundaries). Polycrystalline cerium oxide particles of this structure are different from simple aggregates formed by agglomeration of single crystal particles. Since active surfaces (surfaces not exposed to the outside before thinning) appear in sequence while thinning according to stress during grinding, it is considered that a high grinding speed of a material to be ground (e.g., insulating materials such as silicon oxide) can be maintained. Such polycrystalline cerium oxide particles are described in detail in, for example, International Publication No. WO99 / 31195.

[0034] Although the method for producing abrasive grains containing cerium oxide is not particularly limited, examples thereof include liquid phase synthesis, calcination, or oxidation by hydrogen peroxide or the like. In the case of obtaining abrasive grains containing polycrystalline cerium oxide having the above-mentioned grain boundaries, a method of calcining a cerium source such as cerium carbonate is preferred. The temperature during the calcination is preferably 350 to 900°C. In the case where the produced cerium oxide particles are agglomerated, mechanical pulverization is preferably performed. Although the pulverization method is not particularly limited, for example, dry pulverization based on a jet mill or the like, and wet pulverization based on a planetary ball mill or the like are preferred. The jet mill is described, for example, in "Collection of Papers on Chemical Industry", Vol. 6, No. 5, (1980), pp. 527 to 532.

[0035] The abrasive grains may contain constituents other than metal oxides. As constituents other than metal oxides, cerium compounds (excluding cerium oxide), silicon nitride, α-sialon, aluminum nitride, titanium nitride, silicon carbide, boron carbide, etc. may be cited. As cerium compounds, cerium hydroxide, ammonium cerium nitrate, cerium acetate, cerium sulfate hydrate, cerium bromate, cerium bromide, cerium chloride, cerium oxalate, cerium nitrate, cerium carbonate, etc. may be cited.

[0036] From the viewpoint of easily obtaining a high polishing rate of silicon oxide, the lower limit of the content of the metal oxide (e.g., cerium oxide) in the abrasive is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 90% by mass or more, particularly preferably 95% by mass or more, extremely preferably 97% by mass or more, and very preferably 99% by mass or more, based on the total mass of the abrasive (the total mass of the abrasive contained in the polishing liquid). The abrasive containing the metal oxide may be in a form substantially composed of the metal oxide (substantially 100% by mass of the abrasive is a metal oxide). The abrasive may not contain zirconium oxide.

[0037] From the viewpoint of easily obtaining a high polishing speed of the material to be polished (for example, insulating materials such as silicon oxide), the lower limit of the average particle size of the abrasive is preferably 50 nm or more, more preferably 70 nm or more, further preferably 80 nm or more, and particularly preferably 90 nm or more. From the viewpoint of easily suppressing polishing scratches, the upper limit of the average particle size of the abrasive is preferably 500 nm or less, more preferably 300 nm or less, further preferably 280 nm or less, particularly preferably 250 nm or less, extremely preferably 200 nm or less, very preferably 180 nm or less, further preferably 150 nm or less, further preferably 120 nm or less, and particularly preferably 100 nm or less. From these viewpoints, the average particle size of the abrasive is preferably 50 to 500 nm.

[0038] In order to control the average particle size of the abrasive grains, a conventionally known method can be used. Taking cerium oxide particles as an example, as a method for controlling the average particle size of the abrasive grains, the control of the above-mentioned calcination temperature, calcination time, crushing conditions, etc., and the application of filtration, classification, etc. can be listed. As the average particle size of the abrasive grains, the arithmetic mean diameter of the polishing liquid sample in which the abrasive grains are dispersed can be measured by a laser diffraction / scattering particle size distribution meter. The average particle size of the abrasive grains is, for example, a value measured using LA-920 (trade name) manufactured by HORIBA, Ltd.

[0039] In the case of grinding a surface to be ground with unevenness, from the viewpoint of easily obtaining a high grinding speed regardless of the uneven state, the zeta potential (surface potential) of the abrasive in the polishing liquid is preferably positive (zeta potential is greater than 0mV). In the case of grinding a surface to be ground with unevenness, from the viewpoint of easily obtaining a high grinding speed regardless of the uneven state, the lower limit of the zeta potential of the abrasive is preferably 10mV or more, more preferably 20mV or more, further preferably 30mV or more, particularly preferably 40mV or more, extremely preferably 50mV or more, and very preferably 60mV or more. The upper limit of the zeta potential of the abrasive is preferably 200mV or less, more preferably 150mV or less, further preferably 100mV or less, particularly preferably 80mV or less, and extremely preferably 70mV or less. From these viewpoints, the zeta potential of the abrasive is preferably greater than 0mV and less than 200mV, more preferably 10 to 200mV, and further preferably 30 to 70mV. The zeta potential of the abrasive grains can be measured using, for example, a dynamic light scattering potential measuring device (for example, DelsaNano C (device name) manufactured by Beckman Coulter KK).

[0040] The content of the abrasive grains is preferably in the following range based on the total amount of the polishing liquid. From the viewpoint of easily achieving a high polishing rate, the lower limit of the content of the abrasive grains is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, further preferably 0.10% by mass or more, particularly preferably greater than 0.10% by mass, extremely preferably 0.15% by mass or more, very preferably 0.18% by mass or more, further preferably greater than 0.18% by mass, further preferably 0.20% by mass or more, particularly preferably 0.25% by mass or more, extremely preferably greater than 0.25% by mass, very preferably 0.30% by mass or more, further preferably 0.50% by mass or more, further preferably 0.70% by mass or more, particularly preferably 0.90% by mass or more, and extremely preferably 0.95% by mass or more. From the viewpoint of easily suppressing agglomeration of abrasive grains and from the viewpoint of easily achieving a high polishing rate, the upper limit of the content of abrasive grains is preferably 10% by mass or less, more preferably 5.0% by mass or less, further preferably 3.0% by mass or less, particularly preferably 2.0% by mass or less, extremely preferably 1.5% by mass or less, and very preferably 1.0% by mass or less. From these viewpoints, the content of abrasive grains is preferably 0.01 to 10% by mass, more preferably 0.10 to 10% by mass, and further preferably 0.10 to 3.0% by mass.

[0041] (Hydroxy Acid Compounds)

[0042] The polishing liquid according to the present embodiment contains at least one hydroxy acid compound (hereinafter referred to as “specific hydroxy acid compound”) selected from the group consisting of hydroxy acids having a structure represented by the following general formula (A1) and salts thereof. The hydroxy acid is a carboxylic acid having a hydroxyl group.

[0043]

[0044] [Where R 11 represents a hydrogen atom or a hydroxyl group, R 12 represents a hydrogen atom, an alkyl group or an aryl group, n11 represents an integer greater than 0, and n12 represents an integer greater than 0. 11 and R 12 The exception is when both are hydrogen atoms.]

[0045] Examples of hydroxy acid salts having a structure represented by general formula (A1) include salts in which the hydrogen atom of the carboxyl group is replaced with an alkali metal (eg, sodium atom). The polishing liquid according to this embodiment may or may not contain a hydroxy acid compound other than the specific hydroxy acid compound.

[0046] When polishing a surface having irregularities, the specific hydroxy acid compound preferably satisfies at least one of the following characteristics from the viewpoint of easily obtaining a high polishing rate regardless of the state of the irregularities.

[0047] R 12 The number of carbon atoms in the alkyl group is preferably 0-3, more preferably 0-2, further preferably 1 or 2.

[0048] R 12 The aryl group is preferably phenyl.

[0049] n11 is preferably 0 to 3, more preferably 0 to 2, and further preferably 0 or 1.

[0050] n12 is preferably 0 to 3, more preferably 0 to 2, further preferably 0 or 1, and particularly preferably 1.

[0051] The specific hydroxy acid compound preferably has a branched carbon chain.

[0052] The specific hydroxy acid compound preferably does not have a polyoxyalkylene group (eg, a polyoxyethylene group).

[0053] The specific hydroxy acid compound is preferably at least one selected from the group consisting of hydroxy acids and salts thereof having a molecular weight of 90 to 200. The lower limit of the molecular weight is preferably 95 or more, more preferably 100 or more, further preferably greater than 100, particularly preferably 102 or more, and extremely preferably 104 or more. The upper limit of the molecular weight is preferably 180 or less, more preferably 170 or less, further preferably 160 or less, and particularly preferably 150 or less.

[0054] When polishing a polished surface having projections and depressions, from the viewpoint of easily obtaining a high polishing speed regardless of the state of the projections and depressions, the specific hydroxy acid compound preferably includes at least one of the group consisting of a hydroxy acid and a salt thereof having a structure represented by the following general formula (A2), and a hydroxy acid and a salt thereof having a structure represented by the following general formula (A3).

[0055]

[0056] [Where R 21 and R 22 Each independently represents a hydrogen atom, an alkyl group or an aryl group, and R 21 and R 22 The total number of carbon atoms is 2 or more.]

[0057]

[0058] [Where R 3 represents a hydrogen atom, an alkyl group or an aryl group, n31 represents an integer of 0 to 2, and n32 represents an integer greater than 0.]

[0059] When polishing a surface having irregularities, the structure represented by the general formula (A2) preferably satisfies at least one of the following characteristics from the viewpoint of easily obtaining a high polishing rate regardless of the state of the irregularities.

[0060] R 21 The number of carbon atoms in the alkyl group is preferably 0-3, more preferably 0-2, further preferably 1 or 2.

[0061] R 21 The aryl group is preferably phenyl.

[0062] R 21 and R 22 The total number of carbon atoms in is preferably 2-9, more preferably 2-6, and further preferably 2-4.

[0063] When polishing a surface having irregularities, the structure represented by the general formula (A3) preferably satisfies at least one of the following characteristics from the viewpoint of easily obtaining a high polishing rate regardless of the state of the irregularities.

[0064] R 3 A hydrogen atom or an alkyl group is preferred.

[0065] R 3 The number of carbon atoms in the alkyl group is preferably 0-3, more preferably 0-2, further preferably 1 or 2.

[0066] n31 is preferably 0 or 1.

[0067] n32 is preferably 0 to 3, more preferably 0 to 2, further preferably 0 or 1, and particularly preferably 1.

[0068] In the case of polishing a polished surface having unevenness, from the viewpoint of easily obtaining a high polishing rate regardless of the uneven state, and in the case of polishing a polished surface having no unevenness, from the viewpoint of easily achieving a high polishing rate of silicon oxide, the specific hydroxy acid compound preferably includes at least one selected from the group consisting of glyceric acid, mandelic acid, 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(hydroxymethyl)butyric acid, and hydroxyisobutyric acid, more preferably includes at least one selected from the group consisting of glyceric acid, 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(hydroxymethyl)butyric acid, and hydroxyisobutyric acid, and further preferably includes at least one selected from the group consisting of 2,2-bis(hydroxymethyl)butyric acid and hydroxyisobutyric acid. Examples of hydroxyisobutyric acid include 2-hydroxyisobutyric acid (also known as 2-methyllactic acid) and 3-hydroxyisobutyric acid.

[0069] In the case of grinding a grinded surface with unevenness, from the viewpoint of easily obtaining a high grinding speed regardless of the uneven state, and in the case of grinding a grinded surface without unevenness, from the viewpoint of easily achieving a high grinding speed of silicon oxide, based on the total mass of the hydroxy acid compound (the hydroxy acid compound contained in the polishing liquid involved in the present embodiment), the lower limit of the content of the specific hydroxy acid compound is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 90% by mass or more, particularly preferably 95% by mass or more, extremely preferably 97% by mass or more, and very preferably 99% by mass or more. The hydroxy acid compound contained in the polishing liquid involved in the present embodiment can be in the form of substantially consisting of a specific hydroxy acid compound (substantially, 100% by mass of the hydroxy acid compound contained in the polishing liquid involved in the present embodiment is in the form of a specific hydroxy acid compound).

[0070] In the case of grinding a polished surface with unevenness, from the viewpoint of easily obtaining a high polishing speed regardless of the uneven state, and in the case of grinding a polished surface without unevenness, from the viewpoint of easily achieving a high polishing speed of silicon oxide, based on the total mass of the acid component (the acid component contained in the polishing liquid involved in the present embodiment), the content of the specific hydroxy acid compound is preferably in the following range. The lower limit of the content of the specific hydroxy acid compound is preferably 5% by mass or more, more preferably 10% by mass or more, further preferably greater than 10% by mass, particularly preferably 15% by mass or more, extremely preferably greater than 15% by mass, and very preferably 20% by mass or more. The upper limit of the content of the specific hydroxy acid compound is preferably 90% by mass or less, more preferably 85% by mass or less, further preferably 80% by mass or less, particularly preferably 75% by mass or less, and extremely preferably 70% by mass or less. From these viewpoints, the content of the specific hydroxy acid compound is preferably 5 to 90% by mass. In the case of polishing a polished surface having irregularities, from the viewpoint of easily obtaining a particularly high polishing rate regardless of the irregularities, the lower limit of the content of the specific hydroxy acid compound is preferably greater than 20% by mass, more preferably greater than 30% by mass, further preferably greater than 30% by mass, particularly preferably greater than 40% by mass, and extremely preferably greater than 50% by mass, based on the total mass of the acid component.

[0071] In the case of polishing a polished surface with unevenness, from the viewpoint of easily obtaining a high polishing speed regardless of the uneven state, and in the case of polishing a polished surface without unevenness, from the viewpoint of easily achieving a high polishing speed of silicon oxide, the content of the specific hydroxy acid compound is preferably in the following range based on the total mass of the polishing liquid. The lower limit of the content of the specific hydroxy acid compound is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, further preferably 0.05% by mass or more, particularly preferably 0.06% by mass or more, extremely preferably 0.07% by mass or more, and very preferably 0.075% by mass or more. The upper limit of the content of the specific hydroxy acid compound is preferably 10% by mass or less, more preferably 5.0% by mass or less, further preferably 3.0% by mass or less, particularly preferably 1.0% by mass or less, extremely preferably 0.80% by mass or less, very preferably 0.70% by mass or less, further preferably 0.60% by mass or less, further preferably 0.50% by mass or less, particularly preferably 0.40% by mass or less, extremely preferably less than 0.40% by mass, and very preferably 0.30% by mass or less. From these viewpoints, the content of the specific hydroxy acid compound is preferably 0.01 to 10% by mass, more preferably 0.01 to 1.0% by mass.

[0072] In the case of grinding a surface to be ground with unevenness, from the viewpoint of being easy to obtain a particularly high grinding speed regardless of the uneven state, the lower limit of the content of the specific hydroxy acid compound is preferably 0.08% by mass or more, more preferably 0.10% by mass or more, more preferably greater than 0.10% by mass, particularly preferably 0.15% by mass or more, extremely preferably 0.20% by mass or more, very preferably 0.25% by mass or more, and further preferably 0.30% by mass or more, based on the total mass of the polishing liquid. In the case of grinding a surface to be ground without unevenness, from the viewpoint of being easy to achieve a particularly high grinding speed of silicon oxide, the upper limit of the content of the specific hydroxy acid compound is preferably 0.25% by mass or less, more preferably 0.20% by mass or less, further preferably 0.15% by mass or less, particularly preferably 0.10% by mass or less, extremely preferably less than 0.10% by mass, very preferably 0.08% by mass or less, and further preferably 0.075% by mass or less, based on the total mass of the polishing liquid.

[0073] In the case of polishing a polished surface with unevenness, from the viewpoint of easily obtaining a high polishing speed regardless of the uneven state, and in the case of polishing a polished surface without unevenness, from the viewpoint of easily achieving a high polishing speed of silicon oxide, the ratio A1 (the content of hydroxy acid compounds / the content of abrasive grains) of the content of hydroxy acid compounds relative to the content of abrasive grains (the total amount of hydroxy acid compounds contained in the polishing liquid involved in the present embodiment), and / or the ratio A2 (the content of specific hydroxy acid compounds / the content of abrasive grains) of the content of specific hydroxy acid compounds relative to the content of abrasive grains is preferably in the following range (hereinafter, ratio A1 and ratio A2 are referred to as "ratio A"). The lower limit of ratio A is preferably 0.01 or more, more preferably 0.03 or more, further preferably 0.05 or more, particularly preferably 0.06 or more, extremely preferably 0.07 or more, and very preferably 0.075 or more. The upper limit of the ratio A is preferably 10 or less, more preferably 5.0 or less, further preferably 3.0 or less, particularly preferably 1.0 or less, extremely preferably 0.80 or less, very preferably 0.70 or less, further preferably 0.60 or less, further preferably 0.50 or less, particularly preferably 0.40 or less, extremely preferably less than 0.40, and very preferably 0.30 or less. From these viewpoints, the ratio A is preferably 0.01 to 10.

[0074] In the case of grinding a grinded surface with unevenness, from the viewpoint of being easy to obtain a particularly high grinding speed regardless of the uneven state, the lower limit of the ratio A is preferably 0.08 or more, more preferably 0.10 or more, further preferably greater than 0.10, particularly preferably 0.15 or more, extremely preferably 0.20 or more, very preferably 0.25 or more, and further preferably 0.30 or more. In the case of grinding a grinded surface without unevenness, from the viewpoint of being easy to achieve a particularly high grinding speed of silicon oxide, the upper limit of the ratio A is preferably 0.25 or less, more preferably 0.20 or less, further preferably 0.15 or less, particularly preferably 0.10 or less, extremely preferably less than 0.10, very preferably 0.08 or less, and further preferably 0.075 or less.

[0075] (Other ingredients)

[0076] The polishing liquid involved in this embodiment may also contain other additives (except abrasive and hydroxy acid compounds). As additives, acid components other than hydroxy acid compounds; alkaline components; water-soluble polymers; nonionic surfactants, etc. can be listed. Acid components and alkaline components can be used as pH adjusters for adjusting pH. The polishing liquid involved in this embodiment may contain a buffer to stabilize the pH. A buffer can be added as a buffer solution (a solution containing a buffer). As a buffer solution, acetate buffer, phthalate buffer, etc. can be listed.

[0077] The polishing liquid involved in this embodiment may contain at least one amino acid component selected from the group consisting of amino acids and amino acid derivatives as an acid component other than the hydroxy acid compound. As amino acid derivatives, amino acid esters, amino acid salts, peptides, etc. can be listed. Amino acids are compounds having two functional groups, amino group and carboxyl group.

[0078] Examples of the amino acid component include glycine, α-alanine, β-alanine (also known as 3-aminopropionic acid), 2-aminobutyric acid, norvaline, valine, leucine, norleucine, isoleucine, alloisoleucine, phenylalanine, proline, sarcosine, ornithine, lysine, serine, threonine, allothreonine, homoserine, tyrosine, 3,5-diiodo-tyrosine, β-(3,4-dihydroxyphenyl)-alanine, thyroxine, 4-hydroxy-proline, cysteine, methionine, ethionine, lanthionine, and thiocyanate. Acid, cystathionine, cystine, cysteine, aspartic acid, glutamic acid, S-(carboxymethyl)-cysteine, 4-aminobutyric acid, asparagine, glutamine, azoserine, arginine, canavanine, citrulline, δ-hydroxy-lysine, creatine, kynurenine, histidine, 1-methyl-histidine, 3-methyl-histidine, ergothioneine, tryptophan, glycylglycine, diglycylglycine, vasopressin, oxytocin, anal fold frog peptide, octopus toxin, glucagon, secretin, proopiomelanocortin, cholemorphin, prodynorphin, etc.

[0079] From the viewpoint of easily suppressing the agglomeration of abrasive particles (cerium oxide particles, etc.), the amino acid component preferably includes low molecular weight amino acids. The molecular weight of the amino acid component is preferably less than 300, more preferably less than 250, and further preferably less than 200. As such amino acids, glycine (molecular weight 75), α-alanine (molecular weight 89), β-alanine (molecular weight 89), serine (molecular weight 105), histidine (molecular weight 155), glycylglycine (molecular weight 132), diglycylglycine (molecular weight 189), etc. can be cited. In the case of grinding a grinded surface with unevenness, from the viewpoint of easily obtaining a high grinding speed regardless of the uneven state, and in the case of grinding a grinded surface without unevenness, from the viewpoint of easily realizing a high grinding speed of silicon oxide, the amino acid component preferably includes glycine.

[0080] Based on the total mass of the polishing liquid, the content of the acid component (such as amino acid component) other than the hydroxy acid compound is preferably in the following range. From the viewpoint of easily achieving a sufficiently high polishing rate of silicon oxide, the lower limit of the content of the acid component other than the hydroxy acid compound is preferably 0.005 mass % or more, more preferably 0.01 mass % or more, further preferably 0.02 mass % or more, especially preferably 0.03 mass % or more, extremely preferably 0.05 mass % or more, very preferably 0.10 mass % or more, and further preferably 0.20 mass % or more. From the viewpoint of easily achieving a sufficiently high polishing rate of silicon oxide, the upper limit of the content of the acid component other than the hydroxy acid compound is preferably 10 mass % or less, more preferably 5.0 mass % or less, further preferably 3.0 mass % or less, especially preferably 1.0 mass % or less, extremely preferably 0.50 mass % or less, and very preferably 0.40 mass % or less. From these viewpoints, the content of the acid component other than the hydroxy acid compound is preferably 0.005 to 10 mass %.

[0081] In the case of grinding a polished surface with unevenness, from the viewpoint of easily obtaining a high polishing speed regardless of the uneven state, and in the case of grinding a polished surface without unevenness, from the viewpoint of easily achieving a high polishing speed of silicon oxide, the ratio B1 (content of amino acid component / content of hydroxy acid compound) of the content of amino acid component relative to the content of hydroxy acid compound (the total amount of hydroxy acid compound contained in the polishing liquid involved in the present embodiment), and / or the ratio B2 (content of amino acid component / content of specific hydroxy acid compound) of the content of amino acid component relative to the content of specific hydroxy acid compound is preferably in the following range (hereinafter, ratio B1 and ratio B2 are referred to as "ratio B"). The lower limit of ratio B is preferably 0.01 or more, more preferably 0.05 or more, further preferably 0.10 or more, particularly preferably 0.30 or more, and extremely preferably 0.50 or more. The upper limit of ratio B is preferably 10 or less, more preferably 8.0 or less, further preferably 5.0 or less, and particularly preferably 4.0 or less. From these viewpoints, ratio B is preferably 0.01 to 10. When polishing a surface with projections and recesses, the upper limit of the ratio B is preferably 3.0 or less, more preferably 2.0 or less, further preferably 1.5 or less, and particularly preferably 1.0 or less, from the viewpoint of easily obtaining a very high polishing rate regardless of the projection and recess state.

[0082] Examples of the alkaline component include heterocyclic amines, alkanolamines, ammonia, sodium hydroxide, tetramethylammonium hydroxide (TMAH), etc. The polishing liquid according to the present embodiment does not need to contain an alkaline component.

[0083] Heterocyclic amines are amines having at least one heterocyclic ring. As heterocyclic amines, for example, pyrrolidine, pyrrole, imidazole, pyrazole, oxazole, thiazole, pyridine, pyrazine, pyrimidine, pyridazine, triazine, tetrazine and their derivatives (compounds using these compound structures as skeletons) can be cited. As derivatives, aminothiazole, dialkylpyrazole (for example, dimethylpyrazoles such as 3,5-dialkylpyrazoles) and the like can be used. In the case of grinding a grinded surface with unevenness, from the viewpoint of easily obtaining a high grinding speed regardless of the uneven state, and in the case of grinding a grinded surface without unevenness, from the viewpoint of easily achieving a high grinding speed of silicon oxide, the heterocyclic amine preferably includes at least one selected from the group consisting of aminothiazole and dialkylpyrazole (for example, dimethylpyrazoles such as 3,5-dialkylpyrazoles).

[0084] Based on the total amount of the polishing liquid, the content of the heterocyclic amine is preferably in the following range. From the viewpoint of easily achieving a sufficiently high polishing rate for silicon oxide, the lower limit of the heterocyclic amine content is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and further preferably 0.01% by mass or more. From the viewpoint of easily achieving a sufficiently high polishing rate for silicon oxide, the upper limit of the heterocyclic amine content is preferably 10% by mass or less, more preferably 5.0% by mass or less, further preferably 3.0% by mass or less, particularly preferably 1.0% by mass or less, extremely preferably 0.50% by mass or less, and very preferably 0.30% by mass or less. From these viewpoints, the content of the heterocyclic amine is preferably 0.001 to 10% by mass.

[0085] Alkanolamines are compounds having a hydroxyl group and an amino group bonded to an alkane skeleton. Examples of alkanolamines include methanolamine, ethanolamine, diethanolamine, triethanolamine, propanolamine, dimethylethanolamine, N-methylethanolamine, N-polyoxypropyleneethylenediamine, aminoethylethanolamine, heptylamine, isoetharine, and sphingosine.

[0086] Based on the total amount of the polishing liquid, the content of the alkanolamine is preferably in the following range. From the viewpoint of easily achieving a sufficiently high polishing rate for silicon oxide, the lower limit of the alkanolamine content is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and further preferably 0.01% by mass or more. From the viewpoint of easily achieving a sufficiently high polishing rate for silicon oxide, the upper limit of the alkanolamine content is preferably 10% by mass or less, more preferably 5.0% by mass or less, further preferably 3.0% by mass or less, particularly preferably 1.0% by mass or less, extremely preferably 0.50% by mass or less, and very preferably 0.30% by mass or less. From these viewpoints, the content of the alkanolamine is preferably 0.001 to 10% by mass.

[0087] Examples of water-soluble polymers include polyacrylic acid polymers such as polyacrylic acid, polyacrylic acid copolymers, polyacrylic acid salts, and polyacrylic acid copolymer salts; polymethacrylic acid polymers such as polymethacrylic acid and polymethacrylate salts; polyacrylamide; polydimethylacrylamide; polysaccharides such as alginic acid, pectinic acid, carboxymethyl cellulose, agar, curdlan, dextrin, cyclodextrin, and pullulan; vinyl polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, and polyacrylaldehyde; glycerol polymers such as polyglycerol and polyglycerol derivatives; polyethylene glycol, etc.

[0088] The polishing liquid involved in this embodiment may not contain a water-soluble polymer. The polishing liquid involved in this embodiment may not contain a water-soluble polymer. For example, the polishing liquid involved in this embodiment may contain at least one selected from the group consisting of polyvinyl alcohol, polyvinyl pyrrolidone, polyglycerol and polyethylene glycol.

[0089] As nonionic surfactants, ether surfactants such as polyoxypropylene polyoxyethylene alkyl ether, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene polyoxypropylene ether derivatives, polyoxypropylene glycerol ether, polyethylene glycol oxyethylene adducts, methoxy polyethylene glycol oxyethylene adducts, acetylene glycol oxyethylene adducts, etc.; ester surfactants such as sorbitan fatty acid esters and glycerol volatile fatty acid esters; amino ether surfactants such as polyoxyethylene alkylamines; ether ester surfactants such as polyoxyethylene sorbitan fatty acid esters, polyoxyethylene glycerol volatile fatty acid esters, polyoxyethylene alkyl esters; fatty acid alkanolamides, polyoxyethylene fatty acid alkanolamides, etc. Alkanolamide surfactants; acetylene glycol oxyethylene adducts; polyvinyl pyrrolidone; polyacrylamide; polydimethylacrylamide; polyvinyl alcohol, etc. The polishing liquid involved in this embodiment may not contain a nonionic surfactant.

[0090] In the polishing liquid involved in the present embodiment, based on the gross mass of the polishing liquid, the upper limit of the content of the polymer compound having a hydroxyl group may be less than 0.01 mass %, may be below 0.005 mass %, may be below 0.001 mass %, may be below 0.0001 mass %, may be less than 0.0001 mass %. The polishing liquid involved in the present embodiment may not contain the polymer compound having a hydroxyl group.

[0091] In the polishing liquid involved in the present embodiment, based on the gross mass of the polishing liquid, the upper limit of the content of the polymer compound with amide groups can be less than 0.01 mass %, can be below 0.005 mass %, can be below 0.001 mass %, can be below 0.0001 mass %, can also be less than 0.0001 mass %. The polishing liquid involved in the present embodiment may not contain the polymer compound with amide groups. For example, the polishing liquid involved in the present embodiment may not contain poly-N-vinyl acetamide.

[0092] In the polishing liquid involved in the present embodiment, based on the total mass of the polishing liquid, the upper limit of the content of the compound having a cyclic structure (e.g., a compound having two or more cyclic structures) may be less than 0.01% by mass, may be less than 0.005% by mass, may be less than 0.001% by mass, may be less than 0.001% by mass, may be less than 0.0001% by mass, may be less than 0.0001% by mass, and may be less than 0.0001% by mass. The polishing liquid involved in the present embodiment may not contain a compound having a cyclic structure (e.g., a compound having two or more cyclic structures).

[0093] In the polishing liquid involved in the present embodiment, the upper limit of the content of the compound having a polyalkylene chain may be less than 0.01% by mass, may be less than 0.005% by mass, may be less than 0.001% by mass, may be less than 0.0001% by mass, or may be less than 0.0001% by mass, based on the total mass of the polishing liquid. The polishing liquid involved in the present embodiment may not contain a compound having a polyalkylene chain.

[0094] In the polishing liquid according to the present embodiment, the upper limit of the content of the water-soluble polyamide may be less than 0.0001% by mass based on the total mass of the polishing liquid. The polishing liquid according to the present embodiment may not contain the water-soluble polyamide.

[0095] In the polishing liquid involved in the present embodiment, based on the total mass of the polishing liquid, the upper limit of the content of the azo compound (e.g., azo derivative) may be less than 0.025 mass %, may be less than 0.02 mass %, may be less than 0.01 mass %, may be less than 0.005 mass %, may be less than 0.001 mass %, may be less than 0.0001 mass %, may be less than 0.0001 mass %. The polishing liquid involved in the present embodiment may not contain an azo compound (e.g., an azo derivative).

[0096] In the polishing liquid of this embodiment, the upper limit of the oxidant content may be less than 0.003 mol / L, or less than 0.001 mol / L, based on the total amount of the polishing liquid. The polishing liquid of this embodiment may not contain an oxidant.

[0097] (water)

[0098] The polishing liquid involved in this embodiment contains water. Examples of water include deionized water, ultrapure water, etc. The content of water is not particularly limited and may be the remainder of the polishing liquid excluding the content of other components.

[0099] In the case of grinding a grinded surface with unevenness, from the viewpoint of easily obtaining a high grinding speed regardless of the uneven state, and in the case of grinding a grinded surface without unevenness, from the viewpoint of easily achieving a high grinding speed of silicon oxide, based on the total mass of the polishing liquid, the total amount of abrasive and water is preferably in the following range. The lower limit of the total amount of abrasive and water is preferably 95% by mass or more, more preferably 96% by mass or more, further preferably 97% by mass or more, particularly preferably 98% by mass or more, extremely preferably 99% by mass or more, very preferably greater than 99% by mass, further preferably 99.1% by mass or more, further preferably 99.2% by mass or more, particularly preferably 99.3% by mass or more, and extremely preferably 99.4% by mass or more. The upper limit of the total amount of abrasive and water is preferably less than 100% by mass, more preferably 99.9% by mass or less, and further preferably 99.8% by mass or less. From these viewpoints, the total amount of abrasive and water is preferably 95% by mass or more and less than 100% by mass. When polishing a surface without projections and depressions, the total amount of abrasive grains and water is preferably greater than 99.4% by mass, more preferably greater than 99.5% by mass, and even more preferably greater than 99.6% by mass, from the viewpoint of easily achieving a particularly high polishing rate for silicon oxide.

[0100] In the case of grinding a polished surface with unevenness, from the viewpoint of easily obtaining a high polishing speed regardless of the uneven state, and in the case of grinding a polished surface without unevenness, from the viewpoint of easily achieving a high polishing speed of silicon oxide, based on the total mass of the polishing liquid, the total amount of hydroxy acid compounds and water is preferably in the following range. The lower limit of the total amount of hydroxy acid compounds and water is preferably 95% by mass or more, more preferably 96% by mass or more, further preferably 97% by mass or more, especially preferably 98% by mass or more, extremely preferably 98.2% by mass or more, very preferably 98.4% by mass or more, further preferably 98.6% by mass or more, and further preferably 98.7% by mass or more. The upper limit of the total amount of hydroxy acid compounds and water is preferably less than 100% by mass, more preferably 99.8% by mass or less, further preferably 99.5% by mass or less, particularly preferably 99.2% by mass or less, extremely preferably 99% by mass or less, and very preferably less than 99% by mass. From these viewpoints, the total amount of hydroxy acid compounds and water is preferably 95% by mass or more and less than 100% by mass.

[0101] In the case of polishing a polished surface with unevenness, from the viewpoint of easily obtaining a high polishing speed regardless of the uneven state, and in the case of polishing a polished surface without unevenness, from the viewpoint of easily achieving a high polishing speed of silicon oxide, the lower limit of the total amount of abrasive grains, hydroxy acid compounds and water is preferably 95% by mass or more, more preferably 96% by mass or more, further preferably 97% by mass or more, particularly preferably 98% by mass or more, extremely preferably 99% by mass or more, very preferably 99.2% by mass or more, further preferably 99.4% by mass or more, further preferably 99.6% by mass or more, particularly preferably 99.8% by mass or more, extremely preferably 99.9% by mass or more, and very preferably 99.95% by mass or more. The total amount of abrasive grains, hydroxy acid compounds and water may be 100% by mass or less.

[0102] (pH)

[0103] From the viewpoint of easily achieving a sufficiently high polishing rate for silicon oxide, the lower limit of the pH of the polishing liquid involved in the present embodiment is preferably 1.0 or more, more preferably 1.5 or more, further preferably 2.0 or more, particularly preferably 2.2 or more, extremely preferably 2.4 or more, very preferably 2.5 or more, further preferably 3.0 or more, further preferably 3.2 or more, particularly preferably 3.4 or more, and extremely preferably greater than 3.4. From the viewpoint of easily achieving a sufficiently high polishing rate for silicon oxide, the upper limit of the pH is preferably 7.0 or less, more preferably 6.5 or less, further preferably 6.0 or less, particularly preferably 5.5 or less, extremely preferably 5.0 or less, very preferably 4.5 or less, further preferably 4.0 or less, further preferably less than 4.0, particularly preferably 3.8 or less, and extremely preferably 3.5 or less. From these viewpoints, the pH of the polishing liquid is preferably 1.0 to 7.0, more preferably 3.0 to 7.0, further preferably 3.0 to 6.0, particularly preferably 3.0 to 5.0, and extremely preferably 3.5 to 5.0. The pH of the polishing liquid is defined as the pH at a liquid temperature of 25°C.

[0104] The pH of the polishing liquid involved in this embodiment can be measured using a pH meter (e.g., model PHL-40 manufactured by DKK-TOA CORPORATION). For example, after a three-point calibration using a standard buffer solution (phthalate pH buffer solution, pH: 4.01; neutral phosphate pH buffer solution, pH: 6.86; borate pH buffer solution, pH: 9.18), the electrode is placed in the polishing liquid, and the pH after stabilization for more than 3 minutes is measured by the measuring device. At this time, the liquid temperature of the standard buffer solution and the polishing liquid is set to 25°C.

[0105] (How to save and use)

[0106] The polishing liquid involved in this embodiment can be stored as a single-liquid polishing liquid containing at least abrasive grains and a hydroxy acid compound, or can be stored as a multi-liquid (e.g., two-liquid) polishing liquid set in which the constituent components of the polishing liquid are divided into a slurry and an additive liquid in a manner that a slurry (first liquid) and an additive liquid (second liquid) are mixed to form the polishing liquid. The slurry, for example, contains at least abrasive grains and water. The additive liquid, for example, contains at least a hydroxy acid compound and water.

[0107] In the polishing liquid set involved in this embodiment, when polishing is about to start or when polishing, the slurry and the additive liquid are mixed to make the polishing liquid. In addition, the one-liquid polishing liquid can be stored as a polishing liquid storage liquid with a reduced content of liquid medium, and diluted with the liquid medium when polishing. The multi-liquid polishing liquid set can be stored as a slurry storage liquid and an additive liquid storage liquid with a reduced content of liquid medium, and diluted with the liquid medium when polishing.

[0108] <Grinding method>

[0109] The polishing method involved in this embodiment includes a polishing step of polishing the polished surface using the polishing liquid involved in this embodiment. The polishing step is, for example, a step of polishing the insulating material of a substrate having an insulating material (for example, insulating material such as silicon oxide) on the surface using the polishing liquid involved in this embodiment. The polishing step is, for example, a step of polishing the material to be polished (for example, insulating material) by the polishing part while supplying the polishing liquid involved in this embodiment between the material to be polished (for example, insulating material) and the polishing part (polishing pad, etc.). The material to be polished may include an insulating material, an inorganic insulating material, or silicon oxide. The polishing step is, for example, a step of flattening the substrate having an insulating material (for example, insulating material such as silicon oxide) on the surface using the CMP technology using the polishing liquid whose content, pH, etc. of each component are adjusted. The material to be polished may be in the form of a film (polished film) or an insulating film such as a silicon oxide film.

[0110] The grinding process may be a process of grinding a base body, wherein the base body comprises: a substrate having concavities and convexities on the surface; a stopper provided on the substrate along the surface shape of the substrate; and an insulating material (e.g., silicon oxide) provided on the stopper along the shape of the stopper. The grinding process may include: a first process (roughening process) of grinding and removing the insulating material until the portion of the stopper located on the convex portion of the substrate surface is exposed; and a second process (finishing process) of grinding and removing the stopper and the insulating material after the first process. The grinding liquid and the grinding method involved in this embodiment can be used for at least one selected from the group consisting of the first process and the second process. The stopper may include silicon nitride. The stopper may be in the form of a film (stopper film) or a silicon nitride film.

[0111] The polishing method involved in this embodiment is suitable for polishing a substrate having a polished material (e.g., insulating material such as silicon oxide) on the surface during the manufacturing process of the following devices. As devices, individual semiconductors such as diodes, transistors, compound semiconductors, thermistors, varistors, and thyristors can be listed; storage elements such as DRAM (dynamic random access memory), SRAM (static random access memory), EPROM (erasable programmable read-only memory), mask ROM (mask read-only memory), EEPROM (electrically erasable read-only memory), and flash memory; logic circuit elements such as microprocessors, DSPs, and ASICs; integrated circuit elements such as compound semiconductors represented by MMIC (microwave monolithic integrated circuits); photoelectric conversion elements such as hybrid integrated circuits (hybrid ICs), light-emitting diodes, and charge-coupled devices, etc.

[0112] The grinding method involved in this embodiment is particularly suitable for flattening the surface of a substrate having steps (concave and convex) on the surface. As a substrate, for example, a semiconductor device for logic can be cited. The material to be ground can have a portion in which a concave portion or a convex portion is arranged in a T-shape or a lattice shape when viewed from above. For example, the grinding object with the material to be ground can be a semiconductor substrate with a memory cell. According to this embodiment, an insulating material (for example, an insulating material such as silicon oxide) provided on the surface of a semiconductor device (DRAM, flash memory, etc.) having a semiconductor substrate with a memory cell can also be ground at a high speed. According to this embodiment, an insulating material (for example, an insulating material such as silicon oxide) provided on the surface of a 3D-NAND flash memory that is prone to density dependence can also be ground at a high grinding speed while ensuring high flatness.

[0113] The grinding method involved in the present embodiment can grind a material to be ground having a pattern in which the ratio of the line width to the sum of the line width (L: Line) and the space width (S: Space) is within the following range. The ratio of the line width can be more than 10%, more than 20%, more than 30%, more than 40% or more than 50%. The ratio of the line width can be less than 60%, less than 50%, less than 40%, less than 30% or less than 20%. The sum of the line width and the space width can be more than 50μm, more than 80μm or more than 100μm. The sum of the line width and the space width can be less than 200μm, less than 150μm, less than 120μm or less than 100μm. The grinding liquid involved in the present embodiment can be used to grind a material to be ground having a pattern in which the line width ratio is within these ranges. The present embodiment can provide a method for manufacturing a polishing liquid, which includes a selection process, wherein the polishing liquid is selected based on the polishing speed when polishing a material to be polished (e.g., silicon oxide) having a pattern of L / S=50 / 50 μm and the polishing speed when polishing a material to be polished (e.g., silicon oxide) having a pattern of L / S=20 / 80 μm. In the selection process, the polishing liquid can be selected based on the polishing speed when polishing a material to be polished (e.g., silicon oxide) having a pattern of L / S=50 / 50 μm. The above, and the polishing speed when polishing a material to be polished (such as silicon oxide) having a pattern of L / S=20 / 80 μm is Choose the polishing fluid according to the above.

[0114] The polishing object is not limited to a substrate having silicon oxide covering the entire surface, and may be a substrate having silicon nitride, polysilicon, etc. on the surface in addition to silicon oxide. The polishing object may be a substrate having an insulating material (e.g., inorganic insulating materials such as silicon oxide, glass, and silicon nitride), polysilicon, Al, Cu, Ti, TiN, W, Ta, TaN, etc. formed on a wiring board having prescribed wiring.

[0115] As a polishing device, for example, it is preferably a device having a holder for holding a substrate, a polishing platform for attaching a polishing pad, and a member for supplying a polishing liquid to the polishing pad. As a polishing device, a polishing device manufactured by EBARA CORPORATION. (models: EPO-111, EPO-222, FREX200, FREX300, etc.), a polishing device manufactured by Applied Materials, Inc. (trade names: Mirra3400, Reflexion grinder, etc.) and the like can be cited.

[0116] As grinding pad, common nonwoven fabrics, foam, non-foam etc. can be used.As the material of grinding pad, resins such as polyurethane, acrylic resin, polyester, acrylic acid-ester copolymer, polytetrafluoroethylene, polypropylene, polyethylene, poly-4-methylpentene, cellulose, cellulose ester, polyamide (such as nylon (trade name) and aramid fiber), polyimide, polyimide amide, polysiloxane copolymer, ethylene oxide compound, phenolic resin, polystyrene, polycarbonate, epoxy resin can be used.From the viewpoint of easily obtaining excellent grinding speed and flatness, as the material of grinding pad, it is particularly preferred to be selected from at least one of foamed polyurethane and non-foamed polyurethane composition.Grinding pad is preferably implemented with the groove processing that makes the grinding fluid accumulate.

[0117] The grinding conditions are not particularly limited, but the rotation speed of the grinding platform is preferably 200 rpm (min -1 ), from the viewpoint of easily suppressing the scratch of the polished surface, the pressure (processing load) applied on the substrate is preferably below 100kPa. During grinding, the grinding liquid is preferably continuously supplied to the grinding pad by a pump etc. Although this supply amount is not restricted, the surface of the preferred grinding pad is always covered with the grinding liquid.

[0118] After the polishing is completed, the substrate is washed thoroughly in running water, and preferably, water droplets adhering to the substrate are wiped off with a spin dryer or the like, and then dried.

[0119] By grinding in this way, the surface irregularities can be eliminated and a smooth surface can be obtained over the entire substrate. By repeating the formation and grinding of the material to be ground a predetermined number of times, a substrate having a desired number of layers can be manufactured.

[0120] The substrate thus obtained can be used as various electronic components and mechanical components. Specific examples include semiconductor elements; optical glasses such as photomasks, lenses, and prisms; inorganic conductive films such as ITO; optical integrated circuits / optical switch elements and optical waveguides made of glass and crystalline materials; optical single crystals such as end faces of optical fibers and scintillators; solid laser single crystals; sapphire substrates for blue laser LEDs; semiconductor single crystals such as SiC, GaP, and GaAs; glass substrates for magnetic disks; magnetic heads, etc.

[0121] Example

[0122] Hereinafter, the present invention will be described in more detail according to the embodiments. However, the present invention is not limited to these embodiments as long as it does not depart from the technical concept of the present invention. For example, the type of the polishing liquid material and its matching ratio may also be a type and ratio other than the type and ratio described in the present embodiment, and the composition and structure of the polishing object may also be a composition and structure other than the composition and structure described in the present embodiment.

[0123] <Manufacturing of Abrasive Grains>

[0124] After 40 kg of cerium carbonate hydrate was placed in an alumina container, it was calcined in air at 830°C for 2 hours to obtain 20 kg of yellow-white powder. The powder was phase identified by X-ray diffraction, and it was confirmed that the powder contained polycrystalline cerium oxide. The particle size of the powder obtained by calcination was observed by SEM to be 20 to 100 μm. Then, 20 kg of cerium oxide powder was dry-ground using a jet mill. When the ground cerium oxide powder was observed by SEM, it was confirmed that it contained particles containing polycrystalline cerium oxide with grain boundaries. In addition, the specific surface area of ​​the cerium oxide powder is 9.4 m 2 / g. The specific surface area was measured by the BET method.

[0125] <Preparation of CMP polishing slurry>

[0126] 15 kg of the cerium oxide powder and 84.7 kg of deionized water were placed in a container and mixed. In addition, 0.3 kg of 1N acetic acid aqueous solution was added and stirred for 10 minutes to obtain a cerium oxide mixed solution. The cerium oxide mixed solution was sent to another container over 30 minutes. During this period, the cerium oxide mixed solution was irradiated with ultrasonic waves at an ultrasonic frequency of 400 kHz in the piping for liquid delivery.

[0127] A CMP polishing liquid containing 1.0 mass % of the above abrasive grains, the acid components listed in Tables 1 to 3 (hydroxy acid compounds and other acid components), and deionized water (the balance) was obtained.

[0128] When the average particle size of the abrasive grains in the polishing liquid was measured using a laser diffraction / scattering particle size distribution analyzer (manufactured by HORIBA, Ltd., trade name: LA-920), the average particle size was 90 nm in all cases.

[0129] The pH of the CMP polishing liquid was measured under the following conditions: The pH in the Examples and Comparative Examples other than Comparative Example 1 was 3.5, and the pH in Comparative Example 1 was 5.0.

[0130] Measurement temperature: 25℃

[0131] Measuring device: DKK-TOA CORPORATION, model PHL-40

[0132] Determination method: After a three-point calibration using standard buffer (phthalate pH buffer, pH: 4.01 (25°C); neutral phosphate pH buffer, pH: 6.86 (25°C); borate pH buffer, pH: 9.18), the electrode was placed in the polishing liquid and the pH was measured by the measuring device after stabilization for more than 3 minutes.

[0133] An appropriate amount of ceria slurry was placed in DelsaNano C (trade name: manufactured by Beckman Coulter, KK), and the measurement was performed twice at 25° C. The average of the displayed zeta potentials was obtained as the zeta potential. The zeta potential of ceria particles in the ceria slurry was +60 mV.

[0134] <Evaluation of polishing fluid characteristics>

[0135] (Wafer Preparation)

[0136] The CMP polishing liquid was used to polish a control wafer having a silicon oxide film on the surface under the following polishing conditions to obtain a polishing rate (control wafer polishing rate). The control wafer was a wafer having a silicon oxide film with a thickness of 1000 nm disposed on a silicon substrate with a diameter of 200 mm.

[0137] The CMP polishing liquid was used to polish a pattern wafer having a concave-convex silicon oxide film as the film to be polished under the following polishing conditions to obtain the polishing rate. After a silicon nitride film was formed as a stopper film on a portion of a silicon substrate having a diameter of 200 mm, the portion of the silicon substrate without the silicon nitride film was etched 350 nm to form a concave portion, and then a 600 nm silicon oxide film was formed on the stopper film and in the concave portion by a plasma CVD method to obtain a pattern wafer. The pattern wafer had patterns of L / S=50 / 50 μm and L / S=20 / 80 μm.

[0138] [Grinding conditions]

[0139] Polishing device: CMP polisher Mirra3400 (manufactured by Applied Materials, Inc.)

[0140] Polishing pad: Porous urethane pad IC-1010 (manufactured by Rohm and Haas Company)

[0141] Grinding pressure: 3.0psi (20.7kPa)

[0142] Platform speed: 126rpm

[0143] Head speed: 125rpm

[0144] CMP polishing liquid supply: 200ml / min

[0145] Grinding time: 30 seconds

[0146] (Calculation of polishing speed of wafer with coating)

[0147] The film thickness of the silicon oxide film before and after polishing was measured using an optical interference film thickness measuring device (device name: F80) manufactured by Filmetrics Japan, Inc. The film thickness was measured at 79 points at equal intervals on a line (diameter) passing through the center of the wafer, and the average value was obtained as the film thickness. The polishing rate was calculated using the following formula based on the film thickness before and after polishing and the polishing time. The results are shown in Tables 1 to 3.

[0148]

[0149] (Calculation of Pattern Wafer Polishing Speed)

[0150] The film thickness of the silicon oxide film before and after polishing was measured using an optical interference film thickness device (Nanospec AFT-5100) manufactured by nanometrics Inc. The polishing rate was calculated from the film thickness before and after polishing and the polishing time using the following formula. The results are shown in Tables 1 to 3.

[0151]

[0152] [Table 1]

[0153]

[0154] [Table 2]

[0155]

[0156] [Table 3]

[0157]

[0158] In the examples, it was found that when a polished surface having irregularities was polished, a high polishing rate could be obtained regardless of the irregularities.

Claims

1. A polishing liquid comprising: abrasive grains including a metal oxide; a hydroxy acid compound selected from the group consisting of at least one hydroxy acid having a structure represented by the following general formula (A1) and a salt thereof; an amino acid component; and water, wherein the ratio of the content of the hydroxy acid compound to the content of the abrasive grains is 0.50 or less, and the ratio of the content of the amino acid component to the content of the hydroxy acid compound is 3.0 or less; In the formula, R 11 represents a hydrogen atom or a hydroxyl group, R 12 represents a hydrogen atom, an alkyl group or an aryl group, n11 represents an integer greater than 0, and n12 represents an integer greater than 0, wherein, R 11 and R 12 The exception is the case where both are hydrogen atoms.

2. The polishing liquid according to claim 1, wherein The R of the general formula (A1) 12 The number of carbon atoms of the alkyl group is 1 or 2.

3. The polishing liquid according to claim 1, wherein The R of the general formula (A1) 12 The aryl group is phenyl.

4. The polishing liquid according to claim 1, wherein The n11 in the general formula (A1) is 0 or 1.

5. The polishing liquid according to claim 1, wherein The n12 in the general formula (A1) is 1.

6. The polishing liquid according to claim 1, wherein The hydroxy acid compound has a branched carbon chain.

7. The polishing liquid according to claim 1, wherein The hydroxy acid compound does not have a polyoxyalkylene group.

8. The polishing liquid according to claim 1, wherein The molecular weight of the hydroxy acid is 90-200.

9. The polishing liquid according to claim 1, wherein The hydroxy acid compound includes a hydroxy acid having a structure represented by the following general formula (A2) and a salt thereof, In the formula, R 21 and R 22 Each independently represents a hydrogen atom, an alkyl group or an aryl group, and R 21 and R 22 The total number of carbon atoms is 2 or more.

10. The polishing liquid according to claim 9, wherein The R of the general formula (A2) 21 The number of carbon atoms of the alkyl group is 1 or 2.

11. The polishing liquid according to claim 9, wherein The R of the general formula (A2) 21 The aryl group is phenyl.

12. The polishing liquid according to claim 9, wherein The R of the general formula (A2) 21 And the R 22 The total number of carbon atoms is 2 to 4.

13. The polishing liquid according to claim 1, wherein The hydroxy acid compound includes a hydroxy acid having a structure represented by the following general formula (A3) and a salt thereof, In the formula, R 3 represents a hydrogen atom, an alkyl group or an aryl group, n31 represents an integer of 0 to 2, and n32 represents an integer of 0 or greater.

14. The polishing liquid according to claim 13, wherein The R of the general formula (A3) 3 is a hydrogen atom or an alkyl group.

15. The polishing liquid according to claim 13, wherein The R of the general formula (A3) 3 The number of carbon atoms of the alkyl group is 1 or 2.

16. The polishing liquid according to claim 13, wherein The n31 in the general formula (A3) is 0 or 1.

17. The polishing liquid according to claim 13, wherein The n32 in the general formula (A3) is 1.

18. The polishing liquid according to claim 1, wherein The hydroxy acid compound includes at least one selected from the group consisting of glyceric acid, mandelic acid, 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(hydroxymethyl)butyric acid, and hydroxyisobutyric acid.

19. The polishing liquid according to claim 1, wherein The hydroxy acid compound includes at least one selected from the group consisting of glyceric acid, 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(hydroxymethyl)butyric acid, and hydroxyisobutyric acid.

20. The polishing liquid according to claim 18, wherein The hydroxyisobutyric acid includes at least one selected from the group consisting of 2-hydroxyisobutyric acid and 3-hydroxyisobutyric acid.

21. The polishing liquid according to claim 1, wherein The content of the hydroxy acid compound is 0.01 to 10% by mass.

22. The polishing liquid according to claim 1, wherein The content of the hydroxy acid compound is 0.01 to 1.0% by mass.

23. The polishing liquid according to claim 1, wherein The content of the hydroxy acid compound is 0.10 to 1.0 mass %.

24. The polishing liquid according to claim 1, wherein The content of the hydroxy acid compound is 0.20 to 1.0 mass %.

25. The polishing liquid according to claim 1, wherein The ratio of the content of the hydroxy acid compound to the content of the abrasive grains is 0.01 to 0.

50.

26. The polishing liquid according to claim 1, wherein The ratio of the content of the hydroxy acid compound to the content of the abrasive grains is 0.05 to 0.

50.

27. The polishing liquid according to claim 1, wherein The ratio of the content of the hydroxy acid compound to the content of the abrasive grains is 0.10 to 0.

50.

28. The polishing liquid according to claim 1, wherein The ratio of the content of the hydroxy acid compound to the content of the abrasive grains is 0.20 to 0.

50.

29. The polishing liquid according to any one of claims 1 to 28, wherein The metal oxide includes at least one selected from the group consisting of cerium oxide, aluminum oxide, silicon dioxide, titanium oxide, zirconium oxide, magnesium oxide, and mullite.

30. The polishing liquid according to any one of claims 1 to 28, wherein The metal oxide comprises cerium oxide.

31. The polishing liquid according to any one of claims 1 to 28, wherein The average particle size of the abrasive particles is 50 to 500 nm.

32. The polishing liquid according to any one of claims 1 to 28, wherein The average particle size of the abrasive particles is 50 to 150 nm.

33. The polishing liquid according to any one of claims 1 to 28, wherein The abrasive particles have a positive zeta potential.

34. The polishing liquid according to any one of claims 1 to 28, wherein The zeta potential of the abrasive particles is 30 to 70 mV.

35. The polishing liquid according to any one of claims 1 to 28, wherein The content of the abrasive grains is 0.01 to 10% by mass.

36. The polishing liquid according to any one of claims 1 to 28, wherein The content of the abrasive grains is 0.10 to 3.0 mass %.

37. The polishing liquid according to any one of claims 1 to 28, wherein The molecular weight of the amino acid component is 300 or less.

38. The polishing liquid according to any one of claims 1 to 28, wherein The amino acid component includes glycine.

39. The polishing liquid according to any one of claims 1 to 28, wherein The content of the amino acid component is 0.005 to 10% by mass.

40. The polishing liquid according to any one of claims 1 to 28, wherein The content of the amino acid component is 0.10 to 1.0% by mass.

41. The grinding liquid according to any one of claims 1 to 28, wherein The ratio of the content of the amino acid component to the content of the hydroxy acid compound is 0.01 to 3.

0.

42. The grinding liquid according to any one of claims 1 to 28, wherein The ratio of the content of the amino acid component to the content of the hydroxy acid compound is 0.10 to 3.

0.

43. The grinding liquid according to any one of claims 1 to 28, wherein The ratio of the content of the amino acid component to the content of the hydroxy acid compound is 0.01 to 1.

0.

44. The polishing liquid according to any one of claims 1 to 28, further comprising an alkaline component.

45. The polishing liquid according to claim 44, wherein The basic component contains a heterocyclic amine.

46. ​​The polishing liquid according to claim 45, wherein The heterocyclic amine includes at least one selected from the group consisting of aminothiazole and dialkylpyrazole.

47. The polishing liquid according to claim 45, wherein The content of the heterocyclic amine is 0.001 to 10% by mass.

48. The polishing liquid according to claim 45, wherein The content of the heterocyclic amine is 0.01 to 1.0% by mass.

49. The grinding liquid according to any one of claims 1 to 28, wherein The pH is 1.0~7.

0.

50. The polishing liquid according to any one of claims 1 to 28, wherein The pH is 3.0~5.

0.

51. A polishing liquid set, comprising: a first liquid and a second liquid are mixed to form the polishing liquid according to any one of claims 1 to 50, wherein the constituent components of the polishing liquid are divided into the first liquid and the second liquid, The first liquid contains at least the abrasive and water, The second liquid contains at least the hydroxy acid compound and water.

52. Use of the grinding liquid according to any one of claims 1 to 50 for grinding a material to be ground containing silicon oxide.

53. A polishing method comprising the step of polishing a material to be polished using the polishing liquid according to any one of claims 1 to 50.

54. The grinding method according to claim 53, wherein: The polished material includes silicon oxide.

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