Polishing solution and polishing method

Abstract

To provide polishing liquid capable of achieving a high polishing rate without depending on a state of irregularities in polishing an irregular surface of interest.SOLUTION: Polishing liquid contains: abrasive grains containing metal oxide; at least one kind of hydroxy acid compound selected from a group consisting of a hydroxy acid having a structure represented by a general formula (A1) below and a salt thereof; and water. [In the formula, R11 represents a hydrogen atom or a hydroxy group, R12 represents a hydrogen atom, an alkyl group, or an aryl group, n11 represents an integer of 0 or more, and n12 represents an integer of 0 or more; however, the case where both of R11 and R12 are hydrogen atoms is excluded].SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polishing solution and a polishing method using the same. [Background technology]

[0002] In the field of semiconductor manufacturing, with the increasing performance of ultra-large-scale integrated circuits (ULSIs), it is becoming increasingly difficult to achieve both high integration and high speed using conventional miniaturization techniques. Therefore, technologies are being developed that allow for both miniaturization of semiconductor elements and high integration in the vertical direction (i.e., technologies for multi-layer wiring). This technology is disclosed, for example, in Patent Document 1 below.

[0003] In the manufacturing process of devices with multilayer wiring, one of the most important technologies is CMP (Chemical Mechanical Polishing). CMP is a technique that involves forming a substrate on a surface using chemical vapor deposition (CVD) or the like to obtain a base material, and then planarizing the surface of that substrate. If there are irregularities on the surface of the substrate after planarization, problems arise such as the inability to focus during the exposure process or the inability to adequately form fine wiring structures. CMP is also applied in the device manufacturing process to processes such as forming element isolation regions by polishing plasma oxides (BPSG, HDP-SiO2, p-TEOS, etc.), forming interlayer insulating materials, and planarizing plugs (e.g., Al·Cu plugs) after embedding silicon oxide in metal wiring. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] U.S. Patent No. 4944836 [Overview of the project] [Problems that the invention aims to solve]

[0005] Incidentally, in the process of forming an element isolation region on a substrate, silicon oxide is formed by CVD or the like to fill grooves that have been pre-formed on the surface of the substrate. Subsequently, the element isolation region is formed by planarizing the surface of the silicon oxide by CMP. When silicon oxide is formed on a substrate that has irregularities on its surface to obtain the element isolation region, irregularities corresponding to the irregularities of the substrate also occur on the surface of the silicon oxide. In polishing a surface with irregularities, the protrusions are preferentially removed, while the recesses are slowly removed, thereby achieving flattening.

[0006] To improve the throughput of semiconductor production, it is preferable to remove unwanted silicon dioxide formed on the substrate as quickly as possible. For example, when shallow trench isolation (STI) is adopted to accommodate the narrowing of the device isolation region, it is required to remove unwanted silicon dioxide from the substrate at a high polishing rate.

[0007] There are various types of irregularities formed on the surface of a substrate, and the width of the irregularities due to the wiring width, the height of the irregularities, and the direction of the wiring may differ depending on each process or the application of the device. However, conventionally, even if one substrate can be polished well using the same polishing solution, it is not always the case that other substrates can be polished well in the same way. Therefore, it is necessary to obtain a high polishing speed regardless of the state of irregularities on the surface of the substrate being polished using a polishing solution.

[0008] One aspect of the present invention aims to solve the above-mentioned problems and provides a polishing liquid that can achieve a high polishing speed regardless of the state of the unevenness when polishing a surface that has irregularities. Another aspect of the present invention provides a polishing method using the polishing liquid. [Means for solving the problem]

[0009] One aspect of the present invention provides a polishing liquid containing abrasive grains containing a metal oxide, at least one 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. [Chemical formula] [In the formula, R 11 represents a hydrogen atom or a hydroxy group, R 12 represents a hydrogen atom, an alkyl group or an aryl group, n11 represents an integer of 0 or more, and n12 represents an integer of 0 or more. However, the case where both R 11 and R 12 are hydrogen atoms is excluded.]

[0010] Another aspect of the present invention provides a polishing method including a step of polishing a material to be polished using the above-described polishing liquid.

[0011] According to the above-described polishing liquid and polishing method, when polishing a surface to be polished having irregularities, a high polishing rate can be obtained without depending on the state of the irregularities.

Effects of the Invention

[0012] According to one aspect of the present invention, it is possible to provide a polishing liquid capable of obtaining a high polishing rate without depending on the state of irregularities when polishing a surface to be polished having irregularities. Further, according to another aspect of the present invention, it is possible to provide a polishing method using the polishing liquid. These polishing liquids and polishing methods can be used for polishing an insulating material (for example, silicon oxide) provided on the surface of a substrate (for example, a semiconductor wafer).

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof.

[0014] <Definition> In this specification, a numerical range indicated using "~" indicates a range that includes the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value of a certain step's numerical range can be arbitrarily combined with the upper limit value or the lower limit value of the numerical ranges of other steps. In the numerical ranges described in this specification, the upper limit value or the lower limit value of that numerical range may be replaced with the value shown in the examples. "A or B" means that either one of A and B may be included, or both may be included. The materials exemplified in this specification can be used alone or in combination of two or more, unless otherwise specified. In this specification, the usage amount of each component in the composition means the total amount of the plurality of substances corresponding to each component in the composition, unless otherwise specified when there are a plurality of substances corresponding to each component in the composition. In this specification, the term "film" includes, in addition to the structure formed over the entire surface when observed as a plan view, the structure formed partially. In this specification, the term "step" includes not only an independent step but also, even when it cannot be clearly distinguished from other steps, as long as the intended action of that step is achieved.

[0015] <Polishing liquid> The polishing liquid according to this embodiment contains abrasive grains containing a metal oxide, at least one hydroxy acid compound selected from the group consisting of a hydroxy acid having a structure represented by the following general formula (A1) and its salt, and water. The polishing liquid according to this embodiment can be used as a CMP polishing liquid (polishing liquid for CMP). [Chemical formula] [In the formula, R 11 represents a hydrogen atom or a hydroxy group, R 12 represents a hydrogen atom, an alkyl group or an aryl group, n11 represents an integer of 0 or more, and n12 represents an integer of 0 or more. However, the case where both R 11 and R 12 are hydrogen atoms is excluded.]

[0016] The polishing fluid according to this embodiment makes it possible to obtain a high polishing speed regardless of the state of the surface irregularities when polishing a surface having irregularities. For example, when polishing various substrates with different widths of surface irregularities due to wiring width, a high polishing speed can be obtained regardless of the width of the irregularities. Such a polishing fluid is highly versatile and can be used to polish various substrates with different surface conditions. It is presumed that the above-mentioned hydroxy acid compound is strongly adsorbed onto the surface of abrasive grains containing metal oxides and improves the surface activity of the abrasive grains, thereby enabling a high polishing speed regardless of the state of the surface irregularities. However, the factors that can achieve the above effect are not limited to this. According to the polishing fluid according to this embodiment, when polishing a silicon oxide surface having irregularities, for example, a polishing speed of 12,000 Å / min or more can be obtained under the condition L / S (Line / Space) = 50 / 50 μm, and a polishing speed of 190,000 Å / min or more can be obtained under the condition L / S = 20 / 80 μm.

[0017] Conventionally, when polishing silicon oxide wafers having a smooth surface to be polished (silicon oxide blanket wafers), a high polishing speed for silicon oxide can be achieved. However, when polishing silicon oxide wafers having a smooth surface to be polished (silicon oxide pattern wafers), it may not be possible to achieve a high polishing speed for silicon oxide. On the other hand, with the polishing solution according to this embodiment, a high polishing speed for insulating materials (e.g., silicon oxide) can be achieved when polishing a smooth surface to be polished, while a high polishing speed can be obtained when polishing a surface with irregularities, regardless of the state of the irregularities. For example, with the polishing solution according to this embodiment, a polishing speed of 3000 Å / min or more (preferably 5000 Å / min or more, more preferably 8000 Å / min or more) can be obtained when polishing a smooth silicon oxide surface to be polished. The polishing solution according to this embodiment makes it possible to obtain a high polishing speed in both cases: when polishing a surface with irregularities and when polishing a surface without irregularities. A high polishing speed can be obtained regardless of the surface condition of the surface to be polished (presence or absence of irregularities, density, etc.). However, much remains unknown about the mechanism by which silicon dioxide is polished by CMP, and the cause of this phenomenon is not clear.

[0018] Incidentally, when using a polishing solution with a high polishing rate for insulating materials (e.g., silicon dioxide), the polished surface may become rough and lack flatness after polishing. Therefore, production efficiency is sometimes improved by dividing the polishing process for insulating materials into two stages and using different types of polishing solutions in each stage. In the first stage (roughing stage), a polishing solution with a high polishing rate for insulating materials is used to remove most of the insulating material. In the second stage (finishing stage), the insulating material is slowly removed and the polished surface is finished to be sufficiently flat. When CMP for insulating materials is divided into two or more stages, in the first stage, a high polishing rate is prioritized over flatness, so a decrease in polishing rate can lead to a decrease in productivity. On the other hand, with the polishing solution according to this embodiment, it is possible to obtain a high polishing rate regardless of the state of unevenness, so even when CMP for insulating materials (e.g., silicon dioxide) is divided into two or more stages, a decrease in productivity can be suppressed.

[0019] (Abrasive grains) The abrasive grains contain metal oxides. These metal oxides may include cerium oxide (ceria), alumina, silica, titania, zirconia, magnesia, mullite, etc. The abrasive grains can be composed of one component alone or a combination of two or more components. When polishing a surface with irregularities, it is preferable that the abrasive grains contain cerium oxide, as this allows for a high polishing speed regardless of the irregularity.

[0020] Polishing solutions using abrasive grains containing cerium oxide have the advantage of producing relatively few polishing scratches on the polished surface. Conventionally, polishing solutions containing silica particles as abrasive grains have been widely used from the viewpoint of easily achieving high polishing speeds on the material to be polished (for example, insulating materials such as silicon oxide). However, polishing solutions using silica particles generally have the problem of easily causing polishing scratches on the polished surface. In devices with fine patterns with wiring widths of 45 nm generation or later, even minute scratches that were not a problem in the past may affect the reliability of the device.

[0021] When using cerium oxide, it is preferable that the abrasive grains include polycrystalline cerium oxide having grain boundaries (for example, polycrystalline cerium oxide having multiple crystallites surrounded by grain boundaries). Polycrystalline cerium oxide particles with this configuration differ from mere aggregates of single-crystal particles. As they become finer under stress during polishing, active surfaces (surfaces not exposed to the outside before becoming finer) are successively revealed, which is thought to allow for a high polishing rate to be maintained for the material being polished (for example, insulating materials such as silicon oxide). Such polycrystalline cerium oxide particles are described in detail, for example, in International Publication No. WO99 / 31195.

[0022] There are no particular limitations on the method for producing abrasive grains containing cerium oxide, but examples include liquid-phase synthesis; calcination; or oxidation with hydrogen peroxide, etc. When obtaining abrasive grains containing polycrystalline cerium oxide having the aforementioned grain boundaries, a method of calcining a cerium source such as cerium carbonate is preferred. The calcination temperature is preferably 350 to 900°C. If the produced cerium oxide particles are aggregated, it is preferable to mechanically grind them. There are no particular limitations on the grinding method, but for example, dry grinding using a jet mill, etc., or wet grinding using a planetary bead mill, etc., are preferred. A jet mill is described, for example, in "Journal of Chemical Engineering," Vol. 6, No. 5, (1980), pp. 527-532.

[0023] Abrasive grains may contain components other than metal oxides. Examples of components other than metal oxides include cerium compounds (excluding cerium oxide), silicon nitride, α-sialon, aluminum nitride, titanium nitride, silicon carbide, and boron carbide. Examples of cerium compounds include cerium hydroxide, cerium ammonium nitrate, cerium acetate, cerium sulfate hydrate, cerium bromate, cerium bromide, cerium chloride, cerium oxalate, cerium nitrate, and cerium carbonate.

[0024] The lower limit of the metal oxide (e.g., cerium oxide) content in the abrasive grains is preferably 50% by mass or more, more preferably 70% by mass or more, even more 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 grains (total mass of abrasive grains contained in the polishing fluid), from the viewpoint of easily obtaining a high polishing rate of silicon oxide. The abrasive grains containing metal oxides may be substantially composed of metal oxides (a configuration in which substantially 100% by mass of the abrasive grains is metal oxide). The abrasive grains may be a configuration that does not contain zirconia.

[0025] The lower limit of the average particle size of the abrasive grains is preferably 50 nm or more, more preferably 70 nm or more, even more preferably 80 nm or more, and particularly preferably 90 nm or more, from the viewpoint of easily obtaining a high polishing speed of the material to be polished (e.g., insulating material such as silicon oxide). The upper limit of the average particle size of the abrasive grains is preferably 500 nm or less, more preferably 300 nm or less, even more preferably 280 nm or less, particularly preferably 250 nm or less, extremely preferably 200 nm or less, very preferably 180 nm or less, even more preferably 150 nm or less, even more preferably 120 nm or less, and particularly preferably 100 nm or less, from the viewpoint of easily suppressing polishing scratches. From these viewpoints, the average particle size of the abrasive grains is preferably between 50 and 500 nm.

[0026] Conventional known methods can be used to control the average particle size of abrasive grains. Taking cerium oxide particles as an example, methods for controlling the average particle size of abrasive grains include controlling the firing temperature, firing time, and grinding conditions mentioned above; and applying filtration, classification, etc. As the average particle size of abrasive grains, the arithmetic mean diameter measured using a laser diffraction / scattering particle size analyzer on a polishing liquid sample in which abrasive grains are dispersed can be used. The average particle size of abrasive grains is a value measured using, for example, the LA-920 (product name) manufactured by Horiba, Ltd.

[0027] The zeta potential (surface potential) of abrasive grains in the polishing solution is preferably positive (zeta potential greater than 0mV) from the viewpoint of easily obtaining a high polishing speed regardless of the state of unevenness when polishing a surface with irregularities. The lower limit of the zeta potential of abrasive grains is preferably 10mV or more, more preferably 20mV or more, even more preferably 30mV or more, particularly preferably 40mV or more, extremely preferably 50mV or more, and very preferably 60mV or more, from the viewpoint of easily obtaining a high polishing speed regardless of the state of unevenness when polishing a surface with irregularities. The upper limit of the zeta potential of abrasive grains is preferably 200mV or less, more preferably 150mV or less, even more preferably 100mV or less, particularly preferably 80mV or less, and extremely preferably 70mV or less. From these viewpoints, the zeta potential of abrasive grains is preferably greater than 0mV and 200mV or less, more preferably 10 to 200mV, and even more preferably 30 to 70mV. The zeta potential of abrasive grains can be measured, for example, using a dynamic light scattering zeta potential measuring device (e.g., DelsaNano C, manufactured by Beckman Coulter, Inc.).

[0028] The content of abrasive grains is preferably in the following range based on the total mass of the polishing liquid. From the perspective that a high polishing rate is likely to be achieved, the lower limit of the content of abrasive grains is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, still more preferably 0.10% by mass or more, particularly preferably exceeding 0.10% by mass, extremely preferably 0.15% by mass or more, very preferably 0.18% by mass or more, even more preferably exceeding 0.18% by mass, still more preferably 0.20% by mass or more, particularly preferably 0.25% by mass or more, extremely preferably exceeding 0.25% by mass, very preferably 0.30% by mass or more, even more preferably 0.50% by mass or more, still more 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 perspective of suppressing the aggregation of abrasive grains and 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, still more 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 perspectives, the content of abrasive grains is preferably 0.01 to 10% by mass, more preferably 0.10 to 10% by mass, and still more preferably 0.10 to 3.0% by mass.

[0029] (Hydroxy acid compound) 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. Hydroxy acid is a carboxylic acid having a hydroxy group. [Chemical formula] [In the formula, R 11 represents a hydrogen atom or a hydroxy group, R 12 represents a hydrogen atom, an alkyl group or an aryl group, n11 represents an integer of 0 or more, and n12 represents an integer of 0 or more. However, the case where both R 11 and R 12 are hydrogen atoms is excluded.]

[0030] Examples of hydroxy acid salts having the structure represented by general formula (A1) include salts in which the hydrogen atoms of the carboxyl group are replaced with alkali metals (e.g., sodium atoms). The polishing solution according to this embodiment may or may not contain hydroxy acid compounds other than the specified hydroxy acid compound.

[0031] When polishing a surface with irregularities, it is preferable that the specific hydroxy acid compound satisfies at least one of the following characteristics, from the viewpoint of easily obtaining a high polishing speed regardless of the state of the irregularities. R 12 The number of carbon atoms in the alkyl group is preferably 0 to 3, more preferably 0 to 2, and even more preferably 1 or 2. R 12 The aryl group is preferably a phenyl group. n11 is preferably 0 to 3, more preferably 0 to 2, and even more preferably 0 or 1. n12 is preferably 0 to 3, more preferably 0 to 2, even more preferably 0 or 1, and particularly preferably 1. The specific hydroxy acid compound preferably has a branched carbon chain. It is preferable that the specific hydroxy acid compound does not have a polyoxyalkylene group (e.g., a polyoxyethylene group). The specific hydroxy acid compound is preferably at least one selected from the group consisting of hydroxy acids and their salts having a molecular weight of 90 to 200. The lower limit of the molecular weight is preferably 95 or higher, more preferably 100 or higher, even more preferably greater than 100, particularly preferably 102 or higher, and extremely preferably 104 or higher. The upper limit of the molecular weight is preferably 180 or lower, more preferably 170 or lower, even more preferably 160 or lower, and particularly preferably 150 or lower.

[0032] The specific hydroxy acid compound preferably includes at least one selected from the group consisting of hydroxy acids and their salts having the structure represented by the following general formula (A2), and hydroxy acids and their salts having the structure represented by the following general formula (A3), from the viewpoint of easily obtaining a high polishing speed regardless of the state of the unevenness when polishing a surface to be polished that has irregularities.

[0033] [ka] [In the formula, R 21 and R 22 Each of these 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.

[0034] [ka] [In the formula, R 3 [where n31 represents a hydrogen atom, alkyl group, or aryl group, n31 represents an integer between 0 and 2, and n32 represents an integer greater than or equal to 0.]

[0035] The structure represented by general formula (A2) is preferable to satisfy at least one of the following characteristics, from the viewpoint of easily obtaining a high polishing speed regardless of the state of the unevenness when polishing a surface to be polished that has irregularities. R 21 The number of carbon atoms in the alkyl group is preferably 0 to 3, more preferably 0 to 2, and even more preferably 1 or 2. R 21 The aryl group is preferably a phenyl group. R 21 and R 22 The total number of carbon atoms is preferably 2 to 9, more preferably 2 to 6, and even more preferably 2 to 4.

[0036] The structure represented by general formula (A3) is preferable to satisfy at least one of the following characteristics, from the viewpoint of easily obtaining a high polishing speed regardless of the state of the unevenness when polishing a surface to be polished that has irregularities. R 3 It is preferable that this is a hydrogen atom or an alkyl group. R 3 The number of carbon atoms in the alkyl group is preferably 0 to 3, more preferably 0 to 2, and even more preferably 1 or 2. n31 is preferably 0 or 1. n32 is preferably 0 to 3, more preferably 0 to 2, even more preferably 0 or 1, and particularly preferably 1.

[0037] The specific hydroxy acid compound preferably contains 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, from the viewpoint of easily obtaining a high polishing speed regardless of the state of unevenness when polishing a surface to be polished that has irregularities, and from the viewpoint of easily achieving a high polishing speed of silicon dioxide when polishing a surface to be polished that does not have irregularities. More preferably, it contains 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 even more preferably, it contains 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.

[0038] 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, even more 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 hydroxy acid compound (hydroxy acid compound contained in the polishing solution according to this embodiment). The hydroxy acid compound contained in the polishing solution according to this embodiment may be substantially composed of the specific hydroxy acid compound (a configuration in which substantially 100% by mass of the hydroxy acid compound contained in the polishing solution according to this embodiment is the specific hydroxy acid compound).

[0039] The content of the specific hydroxy acid compound is preferably within the following ranges based on the total mass of the acid component (the acid component contained in the polishing solution according to this embodiment), from the viewpoint of easily obtaining a high polishing speed regardless of the state of unevenness when polishing a surface to be polished that has irregularities, and from the viewpoint of easily achieving a high polishing speed of silicon dioxide when polishing a surface to be polished that does not have irregularities. 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, even more preferably more than 10% by mass, particularly preferably 15% by mass or more, extremely preferably more 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, even more 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. The lower limit of the content of the specific hydroxy acid compound is preferably more than 20% by mass, more preferably 30% by mass or more, even more preferably 30% by mass or more, particularly preferably 40% by mass or more, and extremely preferably 50% by mass or more, based on the total mass of the acid component, from the viewpoint of easily obtaining a particularly high polishing speed regardless of the state of the unevenness when polishing a surface to be polished that has irregularities.

[0040] The content of the specific hydroxy acid compound is preferably within the following ranges based on the total mass of the polishing solution, from the viewpoint of easily obtaining a high polishing speed regardless of the state of unevenness when polishing a surface to be polished that has irregularities, and from the viewpoint of easily achieving a high polishing speed of silicon dioxide when polishing a surface to be polished that does not have irregularities. 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, even more 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, even more 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, even more preferably 0.60% by mass or less, even more 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, and more preferably 0.01 to 1.0% by mass.

[0041] 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, even 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 even more preferably 0.30% by mass or more, based on the total mass of the polishing solution, from the viewpoint of easily achieving a particularly high polishing speed of silicon dioxide when polishing a surface that does not have irregularities. 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, even more 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 even more preferably 0.075% by mass or less, based on the total mass of the polishing solution, from the viewpoint of easily achieving a particularly high polishing speed of silicon dioxide when polishing a surface that does not have irregularities.

[0042] The ratio A1 (hydroxy acid compound content / abrasive grain content) of the hydroxy acid compound content to the abrasive grain content (total amount of hydroxy acid compounds contained in the polishing solution according to this embodiment) and / or the ratio A2 (specific hydroxy acid compound content / abrasive grain content) of the specific hydroxy acid compound content to the abrasive grain content are preferably within the following ranges from the viewpoint of easily obtaining a high polishing speed regardless of the state of unevenness when polishing a surface to be polished that has irregularities, and from the viewpoint of easily achieving a high polishing speed of silicon dioxide when polishing a surface to be polished that does not have irregularities (hereinafter, ratios A1 and A2 will be referred to as "ratio A"). The lower limit of ratio A is preferably 0.01 or higher, more preferably 0.03 or higher, even more preferably 0.05 or higher, particularly preferably 0.06 or higher, extremely preferably 0.07 or higher, and very preferably 0.075 or higher. The upper limit of ratio A is preferably 10 or less, more preferably 5.0 or less, even more preferably 3.0 or less, particularly preferably 1.0 or less, extremely preferably 0.80 or less, very preferably 0.70 or less, even more preferably 0.60 or less, even more 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, ratio A is preferably between 0.01 and 10.

[0043] The lower limit of ratio A is preferably 0.08 or higher, more preferably 0.10 or higher, even more preferably greater than 0.10, particularly preferably 0.15 or higher, extremely preferably 0.20 or higher, very preferably 0.25 or higher, and even more preferably 0.30 or higher, from the viewpoint of easily achieving a particularly high polishing speed of silicon dioxide when polishing a surface without irregularities. The upper limit of ratio A is preferably 0.25 or lower, more preferably 0.20 or lower, even more preferably 0.15 or lower, particularly preferably 0.10 or lower, extremely preferably less than 0.10, very preferably 0.08 or lower, and even more preferably 0.075 or lower, from the viewpoint of easily achieving a particularly high polishing speed of silicon dioxide when polishing a surface without irregularities.

[0044] (Other ingredients) The polishing solution according to this embodiment may further contain other additives (excluding abrasive particles and hydroxy acid compounds). Examples of additives include acid components other than hydroxy acid compounds; alkaline components; water-soluble polymers; and nonionic surfactants. Acid components and alkaline components can be used as pH adjusters to adjust the pH. The polishing solution according to this embodiment may contain a buffer to stabilize the pH. A buffer may be added as a buffer solution (a liquid containing a buffer). Examples of buffer solutions include acetate buffers and phthalate buffers.

[0045] The polishing solution according to 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 hydroxy acid compounds. Examples of amino acid derivatives include amino acid esters, amino acid salts, peptides, etc. An amino acid is a compound having both an amino group and a carboxyl group.

[0046] The amino acid components include glycine, α-alanine, β-alanine (also known as 3-aminopropanoic acid), 2-aminobutyric acid, norvaline, valine, leucine, norleucine, isoleucine, alloisoleucine, phenylalanine, proline, sarcosine, ornithine, lysine, serine, threonine, allothreonine, homoserine, tyrosine, 3,5-diiodotyrosine, β-(3,4-dihydroxyphenyl)-alanine, thyroxine, 4-hydroxyproline, cysteine, methionine, ethionine, lanthionine, cystathionine, cystine, and cysteine. Examples include acids, aspartic acid, glutamic acid, S-(carboxymethyl)-cysteine, 4-aminobutyric acid, asparagine, glutamine, azacerin, arginine, canavanine, citrulline, δ-hydroxylysine, creatine, kynurenine, histidine, 1-methylhistidine, 3-methylhistidine, ergothioneine, tryptophan, glycylglycine, glycylglycylglycine, vasopressin, oxytocin, cassinin, eledoisin, glucagon, secretin, proopomelanocortin, enkephalin, prodinorphine, etc.

[0047] The amino acid component preferably contains low molecular weight amino acids, from the viewpoint of easily suppressing the aggregation of abrasive grains (cerium oxide particles, etc.). The molecular weight of the amino acid component is preferably 300 or less, more preferably 250 or less, and even more preferably 200 or less. Examples of such amino acids include 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), and glycylglycylglycine (molecular weight 189). The amino acid component preferably contains glycine, from the viewpoint of easily obtaining a high polishing speed regardless of the state of unevenness when polishing a surface to be polished that has irregularities, and from the viewpoint of easily achieving a high polishing speed of silicon oxide when polishing a surface to be polished that does not have irregularities.

[0048] The content of acid components other than hydroxy acid compounds (e.g., amino acid components) is preferably within the following ranges based on the total mass of the polishing solution. The lower limit of the content of acid components other than hydroxy acid compounds is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, even more preferably 0.02% by mass or more, particularly preferably 0.03% by mass or more, extremely preferably 0.05% by mass or more, very preferably 0.10% by mass or more, and even more preferably 0.20% by mass or more, from the viewpoint of easily achieving a sufficiently high polishing speed of silicon dioxide. The upper limit of the content of acid components other than hydroxy acid compounds is preferably 10% by mass or less, more preferably 5.0% by mass or less, even more 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 0.40% by mass or less, from the viewpoint of easily achieving a sufficiently high polishing speed of silicon dioxide.

[0049] The ratio B1 (content of amino acid component / content of hydroxy acid compound) of the content of hydroxy acid compound (total amount of hydroxy acid compound contained in the polishing solution according to this embodiment) and / or the ratio B2 (content of amino acid component / content of specific hydroxy acid compound) of the content of specific hydroxy acid compound are preferably within the following ranges from the viewpoint of easily obtaining a high polishing speed regardless of the state of unevenness when polishing a surface to be polished that has irregularities, and from the viewpoint of easily achieving a high polishing speed of silicon dioxide when polishing a surface to be polished that does not have irregularities (hereinafter, ratios B1 and B2 will be referred to as "ratio B"). The lower limit of ratio B is preferably 0.01 or higher, more preferably 0.05 or higher, even more preferably 0.10 or higher, particularly preferably 0.30 or higher, and extremely preferably 0.50 or higher. The upper limit of ratio B is preferably 10 or lower, more preferably 8.0 or lower, even more preferably 5.0 or lower, and particularly preferably 4.0 or lower. From these viewpoints, ratio B is preferably 0.01 to 10. The upper limit of ratio B is preferably 3.0 or less, more preferably 2.0 or less, even more preferably 1.5 or less, and particularly preferably 1.0 or less, from the viewpoint of easily obtaining a particularly high polishing speed regardless of the state of the unevenness when polishing a surface to be polished that has irregularities.

[0050] Examples of alkaline components include heterocyclic amines, alkanolamines, ammonia, sodium hydroxide, and tetramethylammonium hydroxide (TMAH). The polishing solution according to this embodiment does not need to contain an alkaline component.

[0051] A heterocyclic amine is an amine having at least one heterocycle. Examples of heterocyclic amines include pyrrolidine, pyrrole, imidazole, pyrazole, oxazole, thiazole, pyridine, pyrazine, pyrimidine, pyridazine, triazine, tetrazine, and their derivatives (compounds with the structure of these compounds as a backbone). Examples of derivatives include aminothiazole and dialkylpyrazole (e.g., dimethylpyrazole such as 3,5-dialkylpyrazole). From the viewpoint of easily obtaining a high polishing speed regardless of the state of unevenness when polishing a surface to be polished that has irregularities, and from the viewpoint of easily achieving a high polishing speed of silicon dioxide when polishing a surface to be polished that does not have irregularities, it is preferable that the heterocyclic amine includes at least one selected from the group consisting of aminothiazole and dialkylpyrazole (e.g., dimethylpyrazole such as 3,5-dialkylpyrazole).

[0052] The heterocyclic amine content is preferably within the following ranges based on the total mass of the polishing solution. 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 even more preferably 0.01% by mass or more, from the viewpoint of easily achieving a sufficiently high polishing rate of silicon dioxide. The upper limit of the heterocyclic amine content is preferably 10% by mass or less, more preferably 5.0% by mass or less, even more 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 the viewpoint of easily achieving a sufficiently high polishing rate of silicon dioxide. From these viewpoints, the heterocyclic amine content is preferably 0.001 to 10% by mass.

[0053] Alkanolamines are compounds having hydroxyl and amino groups bonded to an alkane skeleton. Examples of alkanolamines include methanolamine, ethanolamine, diethanolamine, triethanolamine, propanolamine, dimethylethanolamine, N-methylethanolamine, N-polyoxypropyleneethylenediamine, aminoethylethanolamine, heptaminol, isoethanoline, and sphingosine.

[0054] The alkanolamine content is preferably within the following ranges based on the total mass of the polishing solution. The lower limit of the alkanolamine content is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and even more preferably 0.01% by mass or more, from the viewpoint of easily achieving a sufficiently high polishing rate of silicon dioxide. The upper limit of the alkanolamine content is preferably 10% by mass or less, more preferably 5.0% by mass or less, even more 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 the viewpoint of easily achieving a sufficiently high polishing rate of silicon dioxide. From these viewpoints, the alkanolamine content is preferably 0.001 to 10% by mass.

[0055] 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 polymethacrylic acid salts; polyacrylamide; polydimethylacrylamide; polysaccharides such as alginic acid, pectinic acid, carboxymethylcellulose, agar, curdlan, dextrin, cyclodextrin, and pullulan; vinyl polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyacrolein; glycerin polymers such as polyglycerin and polyglycerin derivatives; and polyethylene glycol.

[0056] The polishing solution according to this embodiment does not need to contain a water-soluble polymer. For example, the polishing solution according to this embodiment does not need to contain at least one selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, polyglycerin, and polyethylene glycol.

[0057] Examples of nonionic surfactants include ether-type surfactants such as polyoxypropylene polyoxyethylene alkyl ether, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene polyoxypropylene ether derivatives, polyoxypropylene glyceryl ether, oxyethylene adducts of polyethylene glycol, oxyethylene adducts of methoxypolyethylene glycol, and oxyethylene adducts of acetylene diols; ester-type surfactants such as sorbitan fatty acid esters and glycerol borate fatty acid esters; amino ether-type surfactants such as polyoxyethylene alkylamines; ether ester-type surfactants such as polyoxyethylene sorbitan fatty acid esters, polyoxyethylene glycerol borate fatty acid esters, and polyoxyethylene alkyl esters; alkanolamide-type surfactants such as fatty acid alkanolamides and polyoxyethylene fatty acid alkanolamides; oxyethylene adducts of acetylene diols; polyvinylpyrrolidone; polyacrylamide; polydimethylacrylamide; and polyvinyl alcohol. The polishing solution according to this embodiment does not need to contain a nonionic surfactant.

[0058] In the polishing solution according to this embodiment, the upper limit of the content of the polymer compound having a hydroxyl group may be less than 0.01% by mass, 0.005% by mass or less, 0.001% by mass or less, 0.0001% by mass or less, or less than 0.0001% by mass, based on the total mass of the polishing solution. The polishing solution according to this embodiment does not need to contain a polymer compound having a hydroxyl group.

[0059] In the polishing solution according to this embodiment, the upper limit of the content of the polymer compound having an amide group may be less than 0.01% by mass, 0.005% by mass or less, 0.001% by mass or less, 0.0001% by mass or less, or less than 0.0001% by mass, based on the total mass of the polishing solution. The polishing solution according to this embodiment does not need to contain a polymer compound having an amide group. For example, the polishing solution according to this embodiment does not need to contain poly-N-vinylacetamide.

[0060] In the polishing solution according to this embodiment, the upper limit of the content of compounds having a cyclic structure (for example, compounds having two or more cyclic structures) may be less than 0.01% by mass, 0.005% by mass or less, 0.001% by mass or less, less than 0.001% by mass, 0.0001% by mass or less, or less than 0.0001% by mass, based on the total mass of the polishing solution. The polishing solution according to this embodiment does not need to contain compounds having a cyclic structure (for example, compounds having two or more cyclic structures).

[0061] In the polishing solution according to this embodiment, the upper limit of the content of compounds having polyalkylene chains may be less than 0.01% by mass, 0.005% by mass or less, 0.001% by mass or less, 0.0001% by mass or less, or less than 0.0001% by mass, based on the total mass of the polishing solution. The polishing solution according to this embodiment does not need to contain compounds having polyalkylene chains.

[0062] In the polishing solution according to this embodiment, the upper limit of the water-soluble polyamide content may be less than 0.0001% by mass, based on the total mass of the polishing solution. The polishing solution according to this embodiment does not need to contain water-soluble polyamide.

[0063] In the polishing solution according to this embodiment, the upper limit of the content of azo compounds (e.g., azo derivatives) may be less than 0.025% by mass, 0.02% by mass or less, 0.01% by mass or less, 0.005% by mass or less, 0.001% by mass or less, 0.0001% by mass or less, or less than 0.0001% by mass, based on the total mass of the polishing solution. The polishing solution according to this embodiment does not need to contain azo compounds (e.g., azo derivatives).

[0064] In the polishing solution according to this embodiment, the upper limit of the oxidizing agent content may be less than 0.003 mol / L and 0.001 mol / L or less, based on the total volume of the polishing solution. The polishing solution according to this embodiment does not need to contain an oxidizing agent.

[0065] (water) The polishing solution according to this embodiment contains water. Examples of water include deionized water and ultrapure water. The amount of water is not particularly limited and may be the remainder of the polishing solution after removing the other constituent components.

[0066] The total amount of abrasive grains and water is preferably within the following ranges based on the total mass of the polishing solution, from the viewpoint of easily obtaining a high polishing speed regardless of the state of unevenness when polishing a surface to be polished that has irregularities, and from the viewpoint of easily achieving a high polishing speed of silicon dioxide when polishing a surface to be polished that does not have irregularities. The lower limit of the total amount of abrasive grains and water is preferably 95% by mass or more, more preferably 96% by mass or more, even more preferably 97% by mass or more, particularly preferably 98% by mass or more, extremely preferably 99% by mass or more, very preferably exceeding 99% by mass, even more preferably 99.1% by mass or more, even more 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 grains and water is preferably less than 100% by mass, more preferably 99.9% by mass or less, and even more preferably 99.8% by mass or less. From these viewpoints, the total amount of abrasive grains and water is preferably 95% by mass or more and less than 100% by mass. The total amount of abrasive grains and water is preferably more than 99.4% by mass, more preferably 99.5% by mass or more, and even more preferably 99.6% by mass or more, from the viewpoint of easily achieving a particularly high polishing rate of silicon dioxide when polishing a surface that does not have irregularities.

[0067] The total amount of hydroxy acid compounds and water is preferably within the following ranges based on the total mass of the polishing solution, from the viewpoint of easily obtaining a high polishing speed regardless of the state of unevenness when polishing a surface to be polished that has irregularities, and from the viewpoint of easily achieving a high polishing speed of silicon dioxide when polishing a surface to be polished that does not have irregularities. 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, even more preferably 97% by mass or more, particularly preferably 98% by mass or more, extremely preferably 98.2% by mass or more, very preferably 98.4% by mass or more, even more preferably 98.6% by mass or more, and even more 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, even more 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 perspectives, the total amount of hydroxy acid compounds and water is preferably 95% by mass or more and less than 100% by mass.

[0068] 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, even more 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, even more preferably 99.4% by mass or more, even more 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, based on the total mass of the polishing solution. The total amount of abrasive grains, hydroxy acid compounds, and water may be 100% by mass or less.

[0069] (pH) From the viewpoint of easily achieving a sufficiently high polishing rate of silicon dioxide, the lower limit of the pH of the polishing solution according to this embodiment is preferably 1.0 or higher, more preferably 1.5 or higher, even more preferably 2.0 or higher, particularly preferably 2.2 or higher, extremely preferably 2.4 or higher, very preferably 2.5 or higher, even more preferably 3.0 or higher, even more preferably 3.2 or higher, particularly preferably 3.4 or higher, and extremely preferably exceeding 3.4. From the viewpoint of easily achieving a sufficiently high polishing rate of silicon dioxide, the upper limit of the pH is preferably 7.0 or lower, more preferably 6.5 or lower, even more preferably 6.0 or lower, particularly preferably 5.5 or lower, extremely preferably 5.0 or lower, very preferably 4.5 or lower, even more preferably 4.0 or lower, even more preferably less than 4.0, particularly preferably 3.8 or lower, and extremely preferably 3.5 or lower. From these perspectives, the pH of the polishing solution is preferably 1.0 to 7.0, more preferably 3.0 to 7.0, even more preferably 3.0 to 6.0, particularly preferably 3.0 to 5.0, and most preferably 3.5 to 5.0. The pH of the polishing solution is defined as the pH at a liquid temperature of 25°C.

[0070] The pH of the polishing solution according to this embodiment can be measured using a pH meter (for example, model PHL-40, manufactured by Denki Kagaku Keiki Co., Ltd.). For example, after performing a three-point calibration using standard buffer solutions (phthalate pH buffer, pH: 4.01; neutral phosphate pH buffer, pH: 6.86; borate pH buffer, pH: 9.18), the electrode is placed in the polishing solution, and the pH is measured using the aforementioned measuring device after 3 minutes or more have passed and the solution has stabilized. The temperature of both the standard buffer solution and the polishing solution should be 25°C.

[0071] (Storage format and usage format) The polishing liquid according to this embodiment may be stored as a one-component polishing liquid containing at least abrasive grains and a hydroxy acid compound, or it may be stored as a multi-component (e.g., two-component) polishing liquid set in which the components of the polishing liquid are separated into slurry and additive liquid so that the slurry (first liquid) and additive liquid (second liquid) are mixed to form the polishing liquid. The slurry contains, for example, at least abrasive grains and water. The additive liquid contains, for example, at least a hydroxy acid compound and water.

[0072] In the polishing fluid set according to this embodiment, the slurry and additive liquid are mixed to prepare the polishing fluid immediately before or during polishing. Furthermore, the single-component polishing fluid may be stored as a storage solution for polishing fluid with a reduced liquid medium content, and may also be diluted with the liquid medium before use during polishing. The multi-component polishing fluid set may be stored as a storage solution for slurry and a storage solution for additive liquid with reduced liquid medium content, and may also be diluted with the liquid medium before use during polishing.

[0073] <Polishing method> The polishing method according to this embodiment comprises a polishing step of polishing a material to be polished using a polishing solution according to this embodiment. The polishing step is, for example, a step of polishing an insulating material (for example, an insulating material such as silicon oxide) on a substrate having an insulating material on its surface using a polishing solution according to this embodiment. The polishing step is, for example, a step of polishing the material to be polished with a polishing member (polishing pad, etc.) while supplying the polishing solution according to this embodiment between the material to be polished (for example, an insulating material) and a polishing member. The material to be polished may contain an insulating material, an inorganic insulating material, or silicon oxide. The polishing step is, for example, a step of planarizing a substrate having an insulating material (for example, an insulating material such as silicon oxide) on its surface using CMP technology, using a polishing solution whose content of each component, pH, etc., has been 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.

[0074] The polishing process may be a process of polishing a substrate comprising a substrate having an uneven 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 polishing process may include a first step (rough polishing step) of polishing and removing the insulating material until the portion of the stopper located on the protrusions on the substrate surface is exposed, and a second step (finishing step) of polishing and removing the stopper and insulating material after the first step. The polishing liquid and polishing method according to this embodiment can be used in at least one selected from the group consisting of the first step and the second step. The stopper may contain silicon nitride. The stopper may be in the form of a film (stopper film) or a silicon nitride film.

[0075] The polishing method according to this embodiment is suitable for polishing a substrate having a polishing material (for example, an insulating material such as silicon dioxide) on its surface during the manufacturing process of the following devices. Examples of devices include discrete semiconductors such as diodes, transistors, compound semiconductors, thermistors, varistors, and thyristors; memory 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 eraseable programmable read-only memory), and flash memory; theoretical circuit elements such as microprocessors, DSPs, and ASICs; integrated circuit elements such as compound semiconductors represented by MMICs (monolithic microwave integrated circuits); and photoelectric conversion elements such as hybrid integrated circuits (hybrid ICs), light-emitting diodes, and charge-coupled elements.

[0076] The polishing method according to this embodiment is particularly suitable for flattening the surface of a substrate having steps (unevenness) on its surface. Examples of substrates include semiconductor devices for logic. The material to be polished may have portions where recesses or protrusions are arranged in a T-shape or grid pattern when viewed from above. For example, the object to be polished may be a semiconductor substrate having memory cells. According to this embodiment, insulating materials (e.g., insulating materials such as silicon oxide) provided on the surface of a semiconductor device (DRAM, flash memory, etc.) equipped with a semiconductor substrate having memory cells can also be polished at a high speed. According to this embodiment, insulating materials (e.g., insulating materials such as silicon oxide) provided on the surface of a 3D-NAND flash memory, which is prone to density dependence, can also be polished at a high polishing speed while ensuring high flatness.

[0077] The polishing method according to this embodiment can polish materials having a pattern in which the ratio of line width to the sum of line width (L: Line) and space width (S: Space) is within the following ranges: The ratio of line width may be 10% or more, 20% or more, 30% or more, 40% or more, or 50% or more. The ratio of line width may be 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less. The sum of line width and space width may be 50 μm or more, 80 μm or more, or 100 μm or more. The sum of line width and space width may be 200 μm or less, 150 μm or less, 120 μm or less, or 100 μm or less. The polishing liquid according to this embodiment can be used to polish materials having a pattern in which the ratio of line width is within these ranges. This embodiment provides a method for manufacturing a polishing solution, comprising a selection step for selecting a polishing solution based on the polishing speed when polishing a material to be polished having an L / S = 50 / 50 μm pattern (e.g., silicon dioxide) and the polishing speed when polishing a material to be polished having an L / S = 20 / 80 μm pattern (e.g., silicon dioxide). In the selection step, the polishing solution may be selected based on the fact that the polishing speed when polishing a material to be polished having an L / S = 50 / 50 μm pattern (e.g., silicon dioxide) is 12,000 Å / min or more, and the polishing speed when polishing a material to be polished having an L / S = 20 / 80 μm pattern (e.g., silicon dioxide) is 190,000 Å / min or more.

[0078] The object to be polished is not limited to a substrate having silicon oxide covering the entire surface, but may also be a substrate having silicon nitride, polycrystalline silicon, or the like in addition to silicon oxide on its surface. The object to be polished may be a substrate on which an insulating material (for example, an inorganic insulating material such as silicon oxide, glass, or silicon nitride), polysilicon, Al, Cu, Ti, TiN, W, Ta, TaN, etc. are formed on a wiring board having predetermined wiring.

[0079] A suitable polishing apparatus is one that includes, for example, a holder for holding a substrate, a polishing platen to which a polishing pad is attached, and means for supplying polishing fluid onto the polishing pad. Examples of polishing apparatuses include those manufactured by Ebara Corporation (model numbers: EPO-111, EPO-222, FREX200, FREX300, etc.) and those manufactured by APPLIED MATERIALS (product names: Mirra3400, Reflexion polishing machine, etc.).

[0080] As polishing pads, general nonwoven fabrics, foams, and non-foamed materials can be used. As materials for polishing pads, resins such as polyurethane, acrylic resin, polyester, acrylic-ester copolymer, polytetrafluoroethylene, polypropylene, polyethylene, poly-4-methylpentene, cellulose, cellulose ester, polyamide (e.g., nylon (trademark name) and aramid), polyimide, polyimidamide, polysiloxane copolymer, oxirane compounds, phenolic resin, polystyrene, polycarbonate, and epoxy resin can be used. As materials for polishing pads, at least one selected from the group consisting of foamed polyurethane and non-foamed polyurethane is particularly preferred from the viewpoint of easily obtaining excellent polishing speed and flatness. It is preferable that the polishing pad has grooves that allow the polishing liquid to accumulate.

[0081] There are no particular restrictions on the polishing conditions, but to prevent the substrate from flying off, the rotation speed of the polishing platen should be 200 rpm (min). -1 The following is preferable, and the pressure (processing load) applied to the base is preferably 100 kPa or less, from the viewpoint of easily suppressing scratches on the polished surface. It is preferable to continuously supply polishing fluid to the polishing pad by a pump or the like during polishing. There is no limit to the amount supplied, but it is preferable that the surface of the polishing pad is always covered with polishing fluid.

[0082] After polishing is complete, it is preferable to thoroughly wash the substrate in running water, and then remove any water droplets adhering to the substrate using a spin dryer or the like before drying it.

[0083] By polishing in this manner, surface irregularities are eliminated, and a smooth surface can be obtained across the entire substrate. By repeating the formation and polishing of the material to be polished a predetermined number of times, a substrate with a desired number of layers can be manufactured.

[0084] The substrates obtained in this way can be used as various electronic and mechanical components. Specific examples include semiconductor devices; optical glass such as photomasks, lenses, and prisms; inorganic conductive films such as ITO; optical integrated circuits, optical switching elements, and optical waveguides composed of glass and crystalline materials; optical single crystals such as end faces of optical fibers and scintillators; solid-state laser single crystals; sapphire substrates for blue laser LEDs; semiconductor single crystals such as SiC, GaP, and GaAs; glass substrates for magnetic disks; and magnetic heads. [Examples]

[0085] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to these examples, as long as it does not deviate from the technical concept of the present invention. For example, the type of material and its mixing ratio for the polishing solution may be other than those described in these examples, and the composition and structure of the object to be polished may also be other than those described in these examples.

[0086] <Preparation of abrasive grains> 40 kg of cerium carbonate hydrate was placed in an alumina container and calcined in air at 830°C for 2 hours to obtain 20 kg of a yellowish-white powder. Phase identification of this powder was performed by X-ray diffraction, confirming that it contained polycrystalline cerium oxide. SEM observation of the powder obtained by calcination revealed a particle size of 20–100 μm. Next, 20 kg of cerium oxide powder was dry-milled using a jet mill. SEM observation of the cerium oxide powder after milling confirmed the presence of particles containing polycrystalline cerium oxide with grain boundaries. The specific surface area of ​​the cerium oxide powder was 9.4 m². 2 The value was / g. Specific surface area was measured using the BET method.

[0087] <Preparation of CMP Polishing Liquid> 15 kg of the above cerium oxide powder and 84.7 kg of deionized water were placed in a container and mixed. Further, 0.3 kg of 1N acetic acid aqueous solution was added and stirred for 10 minutes to obtain a cerium oxide mixed solution. This cerium oxide mixed solution was fed into another container over 30 minutes. During that time, ultrasonic irradiation was performed on the cerium oxide mixed solution at an ultrasonic frequency of 400 kHz in the pipe through which the solution was fed.

[0088] A CMP polishing liquid containing 1.0% by mass of the above abrasive grains, the acid components (hydroxy acid compounds and other acid components) described in Tables 1 to 3, and deionized water (the balance) was obtained.

[0089] When the average particle size of the abrasive grains in the polishing liquid was measured using a laser diffraction / scattering type particle size distribution analyzer (manufactured by Horiba, Ltd., trade name: LA-920), the average particle size was 90 nm in all cases.

[0090] 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 of Comparative Example 1 was 5.0. Measurement temperature: 25 °C Measuring device: manufactured by Electrochemical Instruments Co., Ltd., model number PHL-40 Measurement method: After performing three-point calibration using standard buffer solutions (phthalate pH buffer solution, pH: 4.01 (25 °C); neutral phosphate pH buffer solution, pH: 6.86 (25 °C); borate pH buffer solution, pH: 9.18), the electrode was placed in the polishing liquid, and after more than 3 minutes had passed and it had stabilized, the pH was measured using the above measuring device.

[0091] An appropriate amount of ceria slurry was put into a product named DelsaNano C manufactured by Beckman Coulter, Inc., and measurements were performed twice at 25 °C. The average value of the displayed zeta potential was obtained as the zeta potential. The zeta potential of the ceria particles in the ceria slurry was +60 mV.

[0092] <Evaluation of Polishing Characteristics> (Preparation of Wafer) Using the CMP polishing solution described above, a blanket wafer having a silicon oxide film on its surface was polished under the following polishing conditions to determine the polishing speed (blanket wafer polishing speed). The blanket wafer is a wafer having a silicon oxide film with a thickness of 1000 nm placed on a silicon substrate with a diameter of 200 mm.

[0093] Using the CMP polishing solution described above, a pattern wafer having a silicon oxide film with uneven surfaces as the film to be polished was polished under the following polishing conditions to determine the polishing speed. The pattern wafer was obtained by forming a silicon nitride film as a stopper film on a portion of a silicon substrate with a diameter of 200 mm, then etching the silicon substrate without the silicon nitride film to 350 nm to form recesses, and then depositing a 600 nm silicon oxide film on the stopper film and in the recesses using plasma CVD. The pattern wafer has patterns with L / S = 50 / 50 μm and L / S = 20 / 80 μm.

[0094] [Polishing conditions] Polishing equipment: CMP polishing machine Mirra3400 (manufactured by APPLIED MATERIALS) Polishing pad: Porous urethane pad IC-1010 (manufactured by Rohm & Haas Japan Co., Ltd.) Polishing pressure: 3.0 psi (20.7 kPa) Plate rotation speed: 126 rpm Head rotation speed: 125 rpm CMP polishing solution supply rate: 200 mL / min Polishing time: 30 seconds

[0095] (Calculation of blanket wafer polishing speed) The film thickness of silicon oxide films before and after polishing was measured using an optical interferometry film thickness analyzer (device name: F80) manufactured by Filmetrics. Film thickness was measured at 79 equally spaced points along a line (diameter) passing through the center of the wafer, and the average value was obtained as the film thickness. Based on the film thickness before and after polishing and the polishing time, the polishing speed was calculated using the following formula. The results are shown in Tables 1-3. Polishing speed [Å / min] = (film thickness before polishing [Å] - film thickness after polishing [Å]) / polishing time [min]

[0096] (Calculation of pattern wafer polishing speed) The film thickness of silicon oxide films before and after polishing was measured using a Nanometrics optical interference film thickness analyzer (device name: Nanospec AFT-5100). Based on the film thickness before and after polishing and the polishing time, the polishing rate was calculated using the following formula. The results are shown in Tables 1-3. Polishing speed [Å / min] = (film thickness before polishing [Å] - film thickness after polishing [Å]) / polishing time [min]

[0097] [Table 1]

[0098] [Table 2]

[0099] [Table 3]

[0100] The embodiment demonstrates that when polishing a surface with irregularities, a high polishing speed can be obtained regardless of the state of the irregularities.

Claims

1. It contains abrasive grains containing a metal oxide, at least one hydroxy acid compound selected from the group consisting of hydroxy acids and salts thereof having a structure represented by the following general formula (A1), an amino acid component, and water. A polishing solution in which the ratio of the content of the amino acid component to the content of the hydroxy acid compound is 3.0 or less. 【Chemistry 1】 [In the formula, R １１ R represents a hydrogen atom or a hydroxyl group. １２ R represents a hydrogen atom, an alkyl group, or an aryl group, n11 represents an integer of 0 or more, and n12 represents an integer of 0 or more. However, R １１ and R １２ This excludes the cases where both are hydrogen atoms, and the cases where R11 is a hydrogen atom, R12 is a methyl group, n11 is 0, and n12 is 0.

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

3. The polishing liquid according to claim 1 or 2, wherein n12 in the general formula (A1) is 1.

4. The polishing solution according to any one of claims 1 to 3, wherein the hydroxy acid compound comprises 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.

5. The polishing solution according to any one of claims 1 to 4, wherein the content of the hydroxy acid compound is 0.01 to 1.0% by mass.

6. The polishing solution according to any one of claims 1 to 5, wherein the metal oxide contains cerium oxide.

7. The polishing liquid according to any one of claims 1 to 6, wherein the content of the abrasive grains is 0.10 to 3.0% by mass.

8. The polishing solution according to any one of claims 1 to 7, wherein the amino acid component contains glycine.

9. The polishing solution according to any one of claims 1 to 8, further containing an alkaline component.

10. The polishing solution according to any one of claims 1 to 9, wherein the pH is 1.0 to 7.

0.

11. The polishing solution according to any one of claims 1 to 10, wherein the pH is 3.0 to 5.

0.

12. A polishing method comprising the step of polishing a material to be polished using a polishing solution described in any one of claims 1 to 11.

13. The polishing method according to claim 12, wherein the material to be polished contains silicon dioxide.

Images