Polishing liquid and polishing method

Abstract

A polishing liquid containing abrasive grains and an acid component, the acid component containing a compound having at least one type selected from the group consisting of a sulfo group and a sulfonate group (excluding sulfuric acid and a salt thereof), the polishing liquid having a pH of more than 4.5. And a polishing method including a step for polishing a surface to be polished using the polishing liquid.

Description

Technical Field

[0001] The present invention relates to a polishing liquid, a polishing method, and the like. Background Art

[0002] In recent years, in the manufacturing process of semiconductor elements, the importance of processing technologies for high density and miniaturization has been increasing. As one of the processing technologies, CMP (Chemical Mechanical Polishing) technology has become an essential technology in the manufacturing process of semiconductor elements for the formation of shallow trench isolation (hereinafter referred to as "STI"), the planarization of pre-metal insulating materials or interlayer insulating materials, the formation of plugs or buried metal wirings, and the like.

[0003] As the most commonly used polishing liquid, for example, a silica-based polishing liquid containing silica (silicon oxide) particles such as fumed silica and colloidal silica as abrasive grains can be cited. The silica-based polishing liquid is characterized by high versatility, and by appropriately selecting the abrasive grain content, pH, additives, etc., it can polish a wide variety of materials regardless of whether they are insulating materials or conductive materials.

[0004] On the other hand, as a polishing liquid mainly for insulating materials such as silicon oxide, the demand for a polishing liquid containing cerium compound particles as abrasive grains is also increasing. For example, a cerium oxide-based polishing liquid containing cerium oxide particles as abrasive grains can polish silicon oxide quickly even at an abrasive grain content lower than that of the silica-based polishing liquid (for example, refer to Patent Documents 1 and 2 below).

[0005] In recent years, in the manufacturing process of semiconductor elements, further miniaturization of wirings has been required, and thus polishing scratches generated during polishing have become a problem. That is, even if minute polishing scratches are generated when polishing with a conventional cerium oxide-based polishing liquid, as long as the size of these polishing scratches is smaller than the conventional wiring width, it does not become a problem. However, in the case of attempting to further miniaturize the wirings, even minute polishing scratches become a problem.

[0006] Regarding this problem, a polishing liquid using cerium hydroxide particles is being studied (for example, refer to Patent Documents 3 to 5 below). Also, methods for manufacturing cerium hydroxide particles are being studied (for example, refer to Patent Documents 6 and 7 below).

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: Japanese Patent Laid-Open No. 10-106994

[0010] Patent Document 2: Japanese Patent Laid-Open No. 08-022970

[0011] Patent Document 3: WO 2002 / 067309

[0012] Patent Document 4: WO 2012 / 070541

[0013] Patent Document 5: WO 2012 / 070542

[0014] Patent Document 6: Japanese Patent Laid-Open No. 2006-249129

[0015] Patent Document 7: WO 2012 / 070544 Summary of the Invention

[0016] Technical Problem to be Solved by the Invention

[0017] In recent years, in semiconductor elements, miniaturization has been accelerating, and as the wiring width is reduced, the film thickness is continuously decreasing. As a result, in the CMP process for forming STI, etc., it is necessary to suppress over-polishing of the stopper layer disposed on the convex portions of the substrate having an uneven pattern while polishing the insulating member. From this viewpoint, for the polishing liquid, excellent polishing selectivity of the insulating material with respect to the stopper layer material (polishing rate ratio: polishing rate of the insulating material / polishing rate of the stopper layer material) is required. For example, excellent polishing selectivity of silicon oxide with respect to silicon nitride (polishing rate ratio: polishing rate of silicon oxide / polishing rate of silicon nitride) is required.

[0018] An object of one aspect of the present invention is to provide a polishing liquid capable of obtaining excellent polishing selectivity of silicon oxide with respect to silicon nitride. Further, an object of another aspect of the present invention is to provide a polishing method using such a polishing liquid.

[0019] Means for Solving the Technical Problem

[0020] One aspect of the present invention includes the following [1] to

[11] .

[0021] [1] A polishing liquid containing abrasive grains and an acid component,

[0022] The acid component contains a compound having at least one selected from the group consisting of a sulfo group and a sulfonate group, and the compound does not contain sulfuric acid and its salts,

[0023] The pH of the polishing liquid exceeds 4.5.

[0024] [2] The polishing liquid according to [1], wherein,

[0025] The abrasive grains contain cerium hydroxide.

[0026] [3] The abrasive liquid according to [1] or [2], wherein,

[0027] the acid component contains an aromatic compound having at least one selected from the group consisting of a sulfo group and a sulfonate group.

[0028] [4] The abrasive liquid according to any one of [1] to [3], wherein,

[0029] the acid component contains a compound without an amino group.

[0030] [5] The abrasive liquid according to any one of [1] to [4], wherein,

[0031] the acid component contains an aminosulfonic acid compound.

[0032] [6] The abrasive liquid according to any one of [1] to [5], wherein,

[0033] the acid component contains at least one selected from the group consisting of p-aminobenzenesulfonic acid and its salts.

[0034] [7] The abrasive liquid according to any one of [1] to [6], wherein,

[0035] based on the total mass of the abrasive liquid, the content of the acid component exceeds 0.2% by mass.

[0036] [8] The abrasive liquid according to any one of [1] to [7], which further contains a nonionic polymer.

[0037] [9] The abrasive liquid according to [8], wherein,

[0038] the nonionic polymer contains a glycerol-based polymer.

[0039]

[10] The abrasive liquid according to any one of [1] to [9], which further contains an alkali component.

[0040]

[11] The abrasive liquid according to any one of [1] to

[10] is used for grinding a surface to be ground containing silicon oxide and silicon nitride.

[0041]

[12] A grinding method, which includes a step of grinding a surface to be ground using the abrasive liquid according to any one of [1] to

[11] .

[0042]

[13] The grinding method according to

[12] , wherein,

[0043] the surface to be ground contains silicon oxide and silicon nitride.

[0044]

[14] A method for manufacturing a part, which includes a step of obtaining the part by using a ground component ground by the grinding method described in

[12] or

[13] .

[0045] Advantages of the Invention

[0046] According to one aspect of the present invention, a polishing liquid capable of obtaining excellent polishing selectivity of silicon oxide with respect to silicon nitride can be provided. And, according to another aspect of the present invention, a polishing method using the polishing liquid can be provided. Detailed Embodiments

[0047] Hereinafter, embodiments of the present invention will be described in detail.

[0048] <Definition>

[0049] In this specification, the "polishing liquid" is defined as a composition that comes into contact with the surface to be polished during polishing. The term "polishing liquid" itself does not impose any limitation on the components contained in the polishing liquid. As described later, the polishing liquid according to this embodiment can contain abrasive grains. Abrasive grains are also referred to as "abrasive particles", but are referred to as "abrasive grains" in this specification. Abrasive grains are generally solid particles, and it is considered that during polishing, the object to be removed is removed by the mechanical action of the abrasive grains and the chemical action of the abrasive grains (mainly the surface of the abrasive grains), but the mechanism of polishing is not limited. The "Polishing Rate" refers to the rate of removing the material per unit time (Removal Rate = Removal Rate).

[0050] A numerical range indicated using "~" represents a range that includes the numerical values described before and after "~" as the minimum value and the maximum value, respectively. "A or more" within the numerical range means A and a range exceeding A. "A or less" within the numerical range means A and a range less than A. Within 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 another step's numerical range. Within the numerical ranges described in this specification, the upper limit value or the lower limit value of this numerical range can be replaced with the values shown in the examples. Unless otherwise specified, the materials exemplified in this specification can be used alone as one kind or two or more kinds can be used in combination. Regarding the amounts of the respective components in the composition, when there are multiple substances corresponding to each component in the composition, unless otherwise specified, it means the total amount of these multiple substances present in the composition. "A or B" only needs to include either A or B, and can also include both. Regarding the term "film", in addition to the structure formed over the entire surface when viewed from a top view, it also includes the structure formed in a part. Regarding the term "process", not only independent processes, but also in cases where it cannot be clearly distinguished from other processes, as long as the function expected of the process can be achieved, it is also included in this term.

[0051] <Polishing liquid>

[0052] The polishing liquid according to this embodiment contains abrasive grains and an acid component, and the pH of the polishing liquid exceeds 4.5. The acid component contains a compound having at least one selected from the group consisting of a sulfo group and a sulfonate group (wherein sulfuric acid and its salts are not included) (hereinafter, such a compound is also referred to as "acid component A").

[0053] The polishing liquid according to this embodiment can be used as a CMP polishing liquid. The polishing liquid according to this embodiment can be used for polishing a polished surface (exposed surface) containing silicon oxide and silicon nitride, and can be used for polishing a polished surface containing silicon oxide and silicon nitride to selectively remove silicon oxide with respect to silicon nitride. The polishing liquid according to this embodiment can be used for polishing a polished surface (exposed surface) containing silicon oxide and silicon carbonitride, and can also be used for polishing a polished surface containing silicon oxide and silicon carbonitride to selectively remove silicon oxide with respect to silicon carbonitride.

[0054] According to the polishing liquid according to this embodiment, silicon oxide can be selectively removed with respect to silicon nitride, and thus excellent polishing selectivity of silicon oxide with respect to silicon nitride (polishing rate ratio: polishing rate of silicon oxide / polishing rate of silicon nitride) can be obtained. According to the polishing liquid according to this embodiment, as the polishing rate ratio of silicon oxide with respect to silicon nitride, a polishing rate ratio of 2.5 or more can be obtained.

[0055] Although the reason for the above effect is not necessarily clear, the inventors et al. speculate as follows. That is, when the pH of the polishing liquid exceeds 4.5, by containing, as an acid component, a compound having at least one selected from the group consisting of a sulfo group and a sulfonate group (wherein sulfuric acid and its salts are not included), the sulfo group and the sulfonate group of the compound are selectively adsorbed on silicon nitride. As a result, the polishing of silicon nitride is significantly inhibited without inhibiting the polishing of silicon oxide. For the above reasons, according to the polishing liquid according to the present embodiment, excellent polishing selectivity of silicon oxide with respect to silicon nitride can be obtained. However, the reason for the effect is not limited to this content.

[0056] The polishing rate ratio of silicon oxide to silicon nitride can be 20 or more, 30 or more, 40 or more, 50 or more, 80 or more, 100 or more, 200 or more, 300 or more, 400 or more, or 500 or more. The polishing rate ratio of silicon oxide to silicon nitride can be 5000 or less, 4500 or less, 4000 or less, 3500 or less, or 3000 or less.

[0057] According to the polishing liquid according to the present embodiment, for example, in the evaluation method of the following examples, as the polishing rate of silicon oxide, it is possible to obtain or more, and the polishing rate of silicon oxide can be or more, or more, or more, or more, or more, or more, or more, or more, or more, or more, or or more.

[0058] According to the polishing liquid according to the present embodiment, for example, in the evaluation method of the following examples, as the polishing rate of silicon nitride, it is possible to obtain or less, and the polishing rate of silicon nitride can be or less, or less, or less, or less, or less, or less, or less, or less, or less, or less, or less, or less, or or less.

[0059] (Abrasive grains)

[0060] Examples of the abrasive material include inorganic substances such as abrasives containing hydroxides of tetravalent metal elements such as cerium, silica, alumina, cerium dioxide (cerium oxide), titanium dioxide, zirconia, germanium dioxide, and silicon carbide; organic substances such as polystyrene, polyacrylic acid, and polyvinyl chloride; and modified products thereof. The "hydroxide of a tetravalent metal element" is a compound containing a tetravalent metal ion (M 4+ ) and at least one hydroxide ion (OH - ). The hydroxide of a tetravalent metal element may contain anions other than hydroxide ions (e.g., nitrate ion NO 3 - and sulfate ion SO 4 2- ). For example, the hydroxide of a tetravalent metal element may contain anions bonded to the tetravalent metal element (e.g., nitrate ion NO 3 - and sulfate ion SO 4 2- ). The abrasive may have water of hydration. As the abrasive containing the hydroxide of a tetravalent metal element, composite particles containing the hydroxide of a tetravalent metal element and silica can also be used.

[0061] The abrasive containing the hydroxide of a tetravalent metal element has a higher reactivity with silica as an insulating material than abrasives formed of silica, cerium dioxide, etc., and can grind silica at a high grinding rate. Moreover, with the abrasive containing the hydroxide of a tetravalent metal element, it is easy to suppress scratches on the ground surface.

[0062] From the viewpoint of easily obtaining excellent grinding selectivity of silica with respect to silicon nitride, the hydroxide of a tetravalent metal element may contain at least one selected from the group consisting of hydroxides of rare earth metal elements and hydroxides of zirconium, and may also contain hydroxides of rare earth metal elements. Examples of tetravalent rare earth metal elements that can be obtained include lanthanide elements such as cerium, praseodymium, and terbium. Among them, from the viewpoint of easily increasing the grinding rate of insulating materials (such as silica), it may be a lanthanide element or cerium. In other words, as the hydroxide of a tetravalent metal element, the abrasive may contain cerium hydroxide (a compound having a hydroxyl group bonded to a cerium atom). Hydroxides of rare earth metal elements and hydroxides of zirconium can be used in combination, and two or more kinds can be selected from hydroxides of rare earth metal elements for use.

[0063] From the viewpoint of easily obtaining excellent polishing selectivity of silica with respect to silicon nitride, the abrasive grains may contain cerium-based particles (particles containing a cerium compound). Examples of the cerium compound (compound containing cerium) as the cerium-based particles include cerium hydroxide, cerium oxide, ammonium cerium nitrate, cerium acetate, cerium sulfate hydrate, cerium bromate, cerium bromide, cerium chloride, cerium oxalate, cerium nitrate, and cerium carbonate. The cerium compound may contain tetravalent cerium or trivalent cerium. The cerium-based particles may have water of hydration. From the viewpoint of easily obtaining excellent polishing selectivity of silica with respect to silicon nitride, the cerium-based particles may contain at least one selected from the group consisting of cerium hydroxide and cerium oxide, may contain cerium hydroxide, may contain at least one selected from the group consisting of cerium hydroxide particles (particles containing cerium hydroxide) and cerium oxide particles (particles containing cerium oxide), or may contain cerium hydroxide particles.

[0064] In the abrasive grains containing a hydroxide of a tetravalent metal element, based on the whole abrasive grains (the whole abrasive grains contained in the polishing liquid), the content of the hydroxide of the tetravalent metal element may be 50% by mass or more, more than 50% by mass, 55% by mass or more, 60% by mass or more, 65% by mass or more, 70% by mass or more, or 75% by mass or more. From the viewpoints of easily preparing the polishing liquid and further excellent polishing characteristics, the form may be such that the abrasive grains are substantially formed of a hydroxide of a tetravalent metal element (the particles of the abrasive grains are substantially 100% by mass of the hydroxide of the tetravalent metal element). The content of cerium hydroxide in the abrasive grains may be within the above range.

[0065] From the viewpoint of easily increasing the polishing rate of an insulating material (such as silica), the average particle diameter of the abrasive grains may be 0.1 nm or more, 0.5 nm or more, 1 nm or more, 2 nm or more, 3 nm or more, 5 nm or more, 10 nm or more, or 12 nm or more. From the viewpoint of easily suppressing scratches on the surface to be polished, the average particle diameter of the abrasive grains may be 100 nm or less, 50 nm or less, 30 nm or less, 20 nm or less, 15 nm or less, or 12 nm or less. From these viewpoints, the average particle diameter of the abrasive grains may be 0.1 to 100 nm.

[0066] The "average particle size" of the abrasive grains refers to the average secondary particle size of the abrasive grains in the polishing liquid. The average particle size of the abrasive grains can be measured using a light diffraction scattering particle size distribution analyzer (for example, manufactured by Beckman Coulter KK, product name: DelsaMax PRO). Regarding the measurement method using the product manufactured by Beckman Coulter KK, product name: DelsaMax PRO, specifically, for example, after placing about 0.5 mL (L represents "liter", the same hereinafter) of the polishing liquid in a measurement cell of 12.5 mm × 12.5 mm × 45 mm (height), the cell is set inside the device. The refractive index of the measurement sample information is set to 1.333, the viscosity is set to 0.887 mPa·s, and the measurement is performed at 25°C. The value displayed as Unimodal Size Mean: single peak size average (cumulative diameter) can be adopted as the average particle size of the abrasive grains.

[0067] From the viewpoint of easily obtaining excellent polishing selectivity of silicon oxide with respect to silicon nitride, the zeta potential of the abrasive grains in the polishing liquid can be positive (exceeding 0 mV). The zeta potential (ζ [mV]) can be measured using a zeta potential measurement device (for example, DelsaNano C (device name) manufactured by Beckman Coulter KK). For example, by placing the polishing liquid in the thick cell unit (high-concentration sample cell) for the zeta potential measurement device and performing the measurement, the zeta potential of the abrasive grains in the polishing liquid can be obtained.

[0068] From the viewpoint of easily obtaining excellent polishing selectivity of silicon oxide with respect to silicon nitride, based on the total mass of the polishing liquid, the content of the abrasive grains can be within the following ranges. The content of the abrasive grains can be 0.001 mass% or more, 0.005 mass% or more, 0.008 mass% or more, 0.01 mass% or more, more than 0.01 mass%, 0.03 mass% or more, 0.04 mass% or more, or 0.05 mass% or more. The content of the abrasive grains can be 10 mass% or less, 5 mass% or less, 1 mass% or less, less than 1 mass%, 0.5 mass% or less, 0.3 mass% or less, 0.1 mass% or less, less than 0.1 mass%, 0.08 mass% or less, 0.07 mass% or less, 0.06 mass% or less, or 0.05 mass% or less. From these viewpoints, the content of the abrasive grains can be 0.001 to 10 mass%. From the same viewpoint, the content of cerium hydroxide can be within the above ranges.

[0069] (Additive)

[0070] The polishing liquid according to the present embodiment contains an additive. "Additive" refers to substances contained in the polishing liquid other than the abrasive grains and water.

[0071] [Acid component A]

[0072] The abrasive liquid according to this embodiment contains, as an acid component, a compound (acid component A) having at least one selected from the group consisting of a sulfo group and a sulfonate group (a functional group in which a hydrogen atom of the sulfo group is substituted with a metal atom (such as a sodium atom or a potassium atom)). By using the acid component A, it is possible to prevent aggregation of abrasive grains and the like while obtaining excellent polishing selectivity of silicon oxide with respect to silicon nitride. The acid component A does not contain sulfuric acid and its salts.

[0073] From the viewpoint of easily obtaining excellent polishing selectivity of silicon oxide with respect to silicon nitride, the number of sulfo groups and sulfonate groups in the acid component A may be 5 or less, 4 or less, 3 or less, 2 or less, or 1.

[0074] The acid component A may have functional groups other than the sulfo group and the sulfonate group. The acid component A may further have, for example, at least one selected from the group consisting of an amino group, a carboxyl group, and a carboxylate group. From the viewpoint of easily suppressing the polishing rate of silicon nitride, the acid component A may not have an amino group.

[0075] From the viewpoint of easily obtaining excellent polishing selectivity of silicon oxide with respect to silicon nitride, the number of amino groups in the acid component A may be 5 or less, 4 or less, 3 or less, or 2 or less.

[0076] From the viewpoint of easily obtaining excellent polishing selectivity of silicon oxide with respect to silicon nitride, the acid component A may contain an organic acid component (organic acid and organic acid derivative), or may contain an aromatic compound. When the acid component A is an aromatic compound, the aromatic ring is adsorbed on the silicon nitride, so that excellent polishing selectivity of silicon oxide with respect to silicon nitride can be easily obtained. The aromatic ring may be a monocyclic ring or a polycyclic ring. The aromatic ring may be at least one selected from the group consisting of a benzene ring, a naphthalene ring, a pyridine ring, and an isoquinoline ring.

[0077] From the viewpoint of easily obtaining excellent polishing selectivity of silicon oxide with respect to silicon nitride, when the acid component A contains an organic acid component, the number of carbon atoms of the organic acid component may be 2 or more, 3 or more, 4 or more, or 5 or more. The number of carbon atoms of the organic acid component may be 12 or less, 11 or less, 10 or less, or 9 or less.

[0078] As the aromatic compound, examples thereof include aromatic sulfonic acids such as aminobenzenesulfonic acid (p-aminobenzenesulfonic acid (alias: 4-aminobenzenesulfonic acid), metanilic acid (alias: 3-aminobenzenesulfonic acid), o-aminobenzenesulfonic acid (alias: 2-aminobenzenesulfonic acid), 2,4-diaminobenzenesulfonic acid, 3,4-diaminobenzenesulfonic acid, 3,4-diaminobenzenesulfonic acid, aminonaphthalenesulfonic acid, 1,3-phenylenediamine-4-sulfonic acid, etc.); aromatic sulfonic acids such as benzenesulfonic acid, dimethylbenzenesulfonic acid, pyridinesulfonic acid, isoquinoline-5-sulfonic acid, etc. The acid component A may contain an aromatic compound having at least one selected from the group consisting of a sulfo group and a sulfonate group, or may contain an aromatic compound having at least one selected from the group consisting of a sulfo group and a sulfonate group and an amino group (aromatic aminosulfonic acid and its salt).

[0079] From the viewpoint of easily obtaining excellent polishing selectivity of silicon oxide relative to silicon nitride, the acid component A may contain at least one aminosulfonic acid compound selected from the group consisting of aminosulfonic acid and aminosulfonate. The aminosulfonic acid compound has an amino group as a cationic moiety and a sulfo group or a sulfonate group as an anionic moiety. Examples of the aminosulfonic acid compound include aromatic aminosulfonic acid, aliphatic aminosulfonic acid, sulfamic acid, and their salts.

[0080] Examples of the aromatic aminosulfonic acid include aminobenzenesulfonic acid (p-aminobenzenesulfonic acid (alias: 4-aminobenzenesulfonic acid), metanilic acid (alias: 3-aminobenzenesulfonic acid), o-aminobenzenesulfonic acid (alias: 2-aminobenzenesulfonic acid), 2,4-diaminobenzenesulfonic acid, 3,4-diaminobenzenesulfonic acid, 3,4-diaminobenzenesulfonic acid, aminonaphthalenesulfonic acid, 1,3-phenylenediamine-4-sulfonic acid, etc.).

[0081] Examples of the aliphatic aminosulfonic acid include aminomethanesulfonic acid, aminoethanesulfonic acid (for example, 1-aminoethanesulfonic acid and 2-aminoethanesulfonic acid (alias taurine)), aminopropanesulfonic acid (for example, 1-aminopropane-2-sulfonic acid and 2-aminopropane-1-sulfonic acid), etc.

[0082] From the viewpoint of easily obtaining excellent polishing selectivity of silicon oxide relative to silicon nitride, the acid component A may contain at least one selected from the group consisting of p-aminobenzenesulfonic acid, sulfamic acid, benzenesulfonic acid, dimethylbenzenesulfonic acid, pyridinesulfonic acid, isoquinoline-5-sulfonic acid, and their salts.

[0083] From the viewpoint of easily obtaining excellent polishing selectivity of silica with respect to silicon nitride, the content of acid component A can be within the following range based on the total mass of the polishing liquid. The content of acid component A can be 0.01% by mass or more, 0.03% by mass or more, 0.05% by mass or more, more than 0.05% by mass, 0.08% by mass or more, 0.1% by mass or more, more than 0.1% by mass, 0.12% by mass or more, 0.14% by mass or more, 0.15% by mass or more, or 0.16% by mass or more. The content of acid component A can be 10% by mass or less, 5% by mass or less, 3% by mass or less, 1% by mass or less, less than 1% by mass, 0.8% by mass or less, 0.6% by mass or less, 0.5% by mass or less, less than 0.5% by mass, 0.4% by mass or less, or 0.35% by mass or less. From these viewpoints, the content of acid component A can be 0.01 to 10% by mass. The content of acid component A can be 0.2% by mass or more, more than 0.2% by mass, 0.22% by mass or more, 0.24% by mass or more, 0.26% by mass or more, 0.28% by mass or more, 0.3% by mass or more, or 0.32% by mass or more.

[0084] From the viewpoint of easily obtaining excellent polishing selectivity of silica with respect to silicon nitride, the content of acid component A (basis: total mass of acid components) in the acid components contained in the polishing liquid, the content of aromatic aminosulfonic acid in the acid components contained in the polishing liquid (basis: total mass of acid components), and / or the content of aromatic aminosulfonic acid in acid component A (basis: total mass of acid component A) can be 80% by mass or more, 90% by mass or more, 95% by mass or more, 98% by mass or more, or 99% by mass or more. It can be a form in which the acid components contained in the polishing liquid are substantially formed of acid component A (substantially 100% by mass of the acid components contained in the polishing liquid is acid component A). It can be a form in which the acid components contained in the polishing liquid are substantially formed of aromatic aminosulfonic acid (substantially 100% by mass of the acid components contained in the polishing liquid is aromatic aminosulfonic acid). It can be a form in which acid component A is substantially formed of aromatic aminosulfonic acid (substantially 100% by mass of acid component A is aromatic aminosulfonic acid).

[0085] From the viewpoint of easily obtaining excellent polishing selectivity of silica relative to silicon nitride, the mass ratio of the content of acid component A to the content of abrasive grains (content of acid component A / content of abrasive grains) can be within the following range. The mass ratio can be 20 or less, 15 or less, 12 or less, 10 or less, 9 or less, 8 or less, 7.5 or less, 7 or less, or 6.5 or less. The mass ratio can be 0.1 or more, 0.5 or more, 1 or more, 1.5 or more, 2 or more, 2.2 or more, 2.4 or more, 2.6 or more, 2.8 or more, 3 or more, 3.2 or more, 3.4 or more, 3.6 or more, 3.8 or more, 4 or more, 4.2 or more, 4.4 or more, 4.6 or more, or 4.8 or more. From these viewpoints, the mass ratio can be 0.1 to 20. The mass ratio can be 5 or more, 5.2 or more, 5.4 or more, 5.6 or more, 5.8 or more, 6 or more, 6.2 or more, or 6.4 or more.

[0086] [Nonionic polymer]

[0087] The polishing liquid according to the present embodiment may further contain a nonionic polymer (nonionic polymer). A "nonionic polymer" is a polymer that does not have a cationic group and a group that can be ionized by a cationic group, and an anionic group and a group that can be ionized by an anion in its main chain or side chain. Examples of the cationic group include an amino group, an imino group, a cyano group, etc., and examples of the anionic group include a carboxyl group, a phosphoric acid group, a sulfonic acid group, etc. The nonionic polymer has a plurality of the same type of structural units (repeating units). By using the nonionic polymer, the abrasive grains are easily dispersed, and thus excellent polishing selectivity of silica relative to silicon nitride can be easily obtained.

[0088] Examples of the nonionic polymer include glycerol-based polymers, polyoxyalkylene compounds, polyvinyl alcohol, polyvinylpyrrolidone, etc.

[0089] Examples of the glycerol-based polymer include polyglycerol, polyglycerol derivatives, etc. Examples of the polyglycerol derivative include polyoxyalkylene polyglycerol ether, polyglycerol fatty acid ester, polyglycerol alkyl ether, etc.

[0090] The polyoxyalkylene compound is a compound having a polyoxyalkylene chain. Examples of the polyoxyalkylene compound include polyalkylene glycols, polyoxyalkylene derivatives, etc.

[0091] Examples of the polyalkylene glycol include polyethylene glycol, polypropylene glycol, polybutylene glycol, etc.

[0092] Examples of polyoxyalkylene derivatives include compounds obtained by introducing substituents into polyalkylene glycols, compounds obtained by adding polyalkylene oxides to organic compounds, etc. Examples of substituents include alkyl ether groups, alkyl phenyl ether groups, phenyl ether groups, styrenated phenyl ether groups, fatty acid ester groups, diol ester groups, etc. Examples of polyoxyalkylene derivatives include aromatic polyoxyalkylene compounds, polyoxyalkylene alkyl ethers, polyoxyalkylene sorbitan fatty acid esters, polyoxyalkylene fatty acid esters, etc.

[0093] An aromatic polyoxyalkylene compound is a compound obtained by introducing a substituent having an aromatic ring into a polyoxyalkylene chain. The aromatic ring may be directly bonded to the polyoxyalkylene chain or may not be directly bonded. The aromatic ring may be a monocyclic ring or a polycyclic ring. The aromatic polyoxyalkylene compound may have a structure in which a plurality of polyoxyalkylene chains are bonded via a substituent having an aromatic ring. From the viewpoint of easily obtaining excellent polishing selectivity of silica with respect to silicon nitride, the polyoxyalkylene chain may be at least one selected from the group consisting of a polyoxyethylene chain, a polyoxypropylene chain, and a polyoxyethylene-polyoxypropylene chain.

[0094] When the aromatic ring is located at the end of the aromatic polyoxyalkylene compound, examples of the substituent having an aromatic ring include aryl groups, etc. Examples of aryl groups include monocyclic aromatic groups such as phenyl, benzyl, tolyl, xylyl, etc.; polycyclic aromatic groups such as naphthyl, etc., and these aromatic groups may further have substituents. Examples of the substituent introduced into the aromatic group include alkyl, vinyl, allyl, alkenyl, alkynyl, styryl, etc., and from the viewpoint of easily obtaining excellent polishing selectivity of silica with respect to silicon nitride, it may be an alkyl or styryl group.

[0095] When the aromatic ring is located in the main chain of the aromatic polyoxyalkylene compound, examples of the substituent having an aromatic ring include arylene groups, etc. Examples of arylene groups include monocyclic aromatic groups such as phenylene, tolylene group, xylylene, etc.; polycyclic aromatic groups such as naphthylene, etc., and these aromatic groups may further have substituents. Examples of the substituent introduced into the aromatic group include alkyl, vinyl, allyl, alkenyl, alkynyl, styryl, etc.

[0096] From the viewpoint of easily obtaining excellent polishing selectivity of silica with respect to silicon nitride, the aromatic polyoxyalkylene compound may contain at least one selected from the group consisting of the compound represented by the following general formula (I) and the compound represented by the following general formula (II).

[0097] R 11 -O-(R 12 -O) m -H…(I)

[0098] [In formula (I), R 11 represents an aryl group which may have substituents, R 12 represents an alkylene group having 1 to 5 carbon atoms which may have substituents, and m represents an integer of 10 or more.]

[0099] H-(O-R 23 ) n1 -O-R 21 -R 25 -R 22 -O-(R 24 -O) n2 -H…(II)

[0100] [In formula (II), R 21 and R 22 each independently represent an arylene group which may have substituents, R 23 , R 24 and R 25 each independently represent an alkylene group having 1 to 5 carbon atoms which may have substituents, and n1 and n2 each independently represent an integer of 15 or more.]

[0101] From the viewpoint of easily obtaining excellent polishing selectivity of silica with respect to silicon nitride, formula (I) can satisfy at least one of the following conditions.

[0102] · As R 11 , it may be the above-mentioned aryl group exemplified as a substituent having an aromatic ring, a phenyl group into which a styryl group or an alkyl group is introduced as a substituent, or a phenyl group into which a styryl group is introduced in plural (for example, 2).

[0103] · As R 12 , it may be an alkylene group having 1 to 3 carbon atoms or an ethylene group.

[0104] · m may be 15 or more or 30 or more.

[0105] · m may be 20000 or less, 10000 or less, 5000 or less, or 1000 or less.

[0106] Examples of the aromatic polyoxyalkylene compound represented by the formula (I) include polyoxyalkylene phenyl ether, polyoxyalkylene alkyl phenyl ether, polyoxyalkylene styrenated phenyl ether, polyoxyalkylene distyrenated phenyl ether, polyoxyalkylene cumyl phenyl ether, polyoxyalkylene benzyl ether, etc. Specific examples of the aromatic polyoxyalkylene compound represented by the formula (I) include polyoxyethylene alkyl phenyl ether, polyoxyethylene nonyl allyl phenyl ether, polyoxyethylene phenyl ether, polyoxyethylene styrenated phenyl ether, polyoxyethylene distyrenated phenyl ether, polyoxypropylene phenyl ether, polyoxyethylene cumyl phenyl ether, polyoxyethylene benzyl ether, etc.

[0107] Examples of the aromatic polyoxyalkylene compound represented by the formula (II) include polyoxyalkylene bisphenol ether, etc. Specific examples of the aromatic polyoxyalkylene compound represented by the formula (II) include 2,2-bis(4-polyoxyethyleneoxyphenyl)propane, etc.

[0108] From the viewpoint of easily obtaining excellent polishing selectivity of silica with respect to silicon nitride, the nonionic polymer may contain at least one selected from the group consisting of glycerol-based polymers and polyoxyalkylene compounds, or may contain glycerol-based polymers and polyoxyalkylene compounds. From the viewpoint of easily obtaining excellent polishing selectivity of silica with respect to silicon nitride, the polyoxyalkylene compound may contain an aromatic polyoxyalkylene compound, may contain at least one selected from the group consisting of polyoxyalkylene styrenated phenyl ether and polyoxyalkylene distyrenated phenyl ether, or may contain at least one selected from the group consisting of polyoxyethylene styrenated phenyl ether and polyoxyethylene distyrenated phenyl ether.

[0109] From the viewpoint of easily obtaining excellent polishing selectivity of silica with respect to silicon nitride, the polishing liquid according to this embodiment may contain a nonionic polymer having the following weight average molecular weight. The weight average molecular weight of the nonionic polymer may be 100 or more, 200 or more, 300 or more, 500 or more, 600 or more, 700 or more, or 750 or more. The weight average molecular weight of the nonionic polymer may be 100,000 or less, 50,000 or less, 10,000 or less, 5,000 or less, 3,000 or less, 1,000 or less, 800 or less, or 750 or less. From these viewpoints, the weight average molecular weight of the nonionic polymer may be 100 to 100,000.

[0110] The weight average molecular weight of the nonionic polymer can be measured, for example, under the following conditions by gel permeation chromatography (GPC) using a calibration curve of standard polystyrene.

[0111] Equipment used: Hitachi L-6000 type [manufactured by Hitachi, Ltd.]

[0112] Column: Gel bags GL-R420 + Gel bag GL-R430 + Gel bag GL-R440 [Product names manufactured by Hitachi High-Tech Corporation, total of 3]

[0113] Eluent: Tetrahydrofuran

[0114] Measurement temperature: 40 °C

[0115] Flow rate: 1.75 mL / min

[0116] Detector: L-3300RI [Manufactured by Hitachi, Ltd.]

[0117] From the viewpoint of easily obtaining excellent polishing selectivity of silica with respect to silicon nitride, based on the total mass of the polishing liquid, the content of the nonionic polymer can be within the following range. The content of the nonionic polymer can be 0.001% by mass or more, 0.005% by mass or more, 0.008% by mass or more, 0.01% by mass or more, 0.03% by mass or more, 0.05% by mass or more, 0.08% by mass or more, 0.1% by mass or more, more than 0.1% by mass, 0.3% by mass or more, 0.4% by mass or more, or 0.5% by mass or more. The content of the nonionic polymer can be 10% by mass or less, 5% by mass or less, 1% by mass or less, less than 1% by mass, 0.8% by mass or less, 0.7% by mass or less, 0.6% by mass or less, 0.55% by mass or less, or 0.5% by mass or less. From these viewpoints, the content of the nonionic polymer can be 0.001 to 10% by mass.

[0118] From the viewpoint of easily obtaining excellent polishing selectivity of silica with respect to silicon nitride, based on the total mass of the polishing liquid, the content of the glycerol-based polymer can be within the following range. The content of the glycerol-based polymer can be 0.001% by mass or more, 0.005% by mass or more, 0.008% by mass or more, 0.01% by mass or more, 0.03% by mass or more, 0.05% by mass or more, 0.08% by mass or more, 0.1% by mass or more, more than 0.1% by mass, 0.3% by mass or more, 0.4% by mass or more, or 0.5% by mass or more. The content of the glycerol-based polymer can be 10% by mass or less, 5% by mass or less, 1% by mass or less, less than 1% by mass, 0.8% by mass or less, 0.7% by mass or less, 0.6% by mass or less, or 0.5% by mass or less. From these viewpoints, the content of the glycerol-based polymer can be 0.001 to 10% by mass.

[0119] In the case where the nonionic polymer contains a glycerol-based polymer, from the viewpoint of easily obtaining excellent polishing selectivity of silica with respect to silicon nitride, based on the total mass of the nonionic polymer, the content of the glycerol-based polymer in the nonionic polymer may be 50% by mass or more, more than 50% by mass, 80% by mass or more, 90% by mass or more, 95% by mass or more, 98% by mass or more, or 99% by mass or more. It may be a form in which the nonionic polymer is substantially formed of a glycerol-based polymer (substantially 100% by mass of the nonionic polymer is a glycerol-based polymer).

[0120] From the viewpoint of easily obtaining excellent polishing selectivity of silica with respect to silicon nitride, the content of the nonionic polymer with respect to 100 parts by mass of the abrasive grains may be within the following range. The content of the nonionic polymer with respect to 100 parts by mass of the abrasive grains may be 2000 parts by mass or less, 1500 parts by mass or less, 1200 parts by mass or less, 1100 parts by mass or less, or 1000 parts by mass or less. The content of the nonionic polymer with respect to 100 parts by mass of the abrasive grains may be 1 part by mass or more, 10 parts by mass or more, 100 parts by mass or more, 500 parts by mass or more, 700 parts by mass or more, 900 parts by mass or more, or 1000 parts by mass or more. From these viewpoints, the content of the nonionic polymer with respect to 100 parts by mass of the abrasive grains may be 1 to 2000 parts by mass.

[0121] From the viewpoint of easily obtaining excellent polishing selectivity of silica with respect to silicon nitride, the content of the nonionic polymer with respect to 100 parts by mass of the acid component A may be within the following range. The content of the nonionic polymer with respect to 100 parts by mass of the acid component A may be 2000 parts by mass or less, 1500 parts by mass or less, 1000 parts by mass or less, 900 parts by mass or less, 800 parts by mass or less, or 700 parts by mass or less. The content of the nonionic polymer with respect to 100 parts by mass of the acid component A may be 1 part by mass or more, 10 parts by mass or more, 50 parts by mass or more, 100 parts by mass or more, 120 parts by mass or more, 140 parts by mass or more, or 150 parts by mass or more. From these viewpoints, the content of the nonionic polymer with respect to 100 parts by mass of the acid component A may be 1 to 2000 parts by mass.

[0122] [Alkali component]

[0123] The abrasive liquid according to this embodiment may further contain an alkali component. By further containing an alkali component in the abrasive liquid containing the acid component A, a pH buffering effect tends to be obtained, so that the pH of the abrasive liquid is easily stabilized, and thus excellent polishing selectivity of silicon oxide with respect to silicon nitride is easily obtained. Examples of the alkali component include compounds having an amino group (heterocyclic amine, alkylamine, etc.), ammonia, sodium hydroxide, etc. Regarding amphoteric compounds, when the isoelectric point (pI) of the compound exceeds 4.5, the compound is treated as an alkali component. Examples of the compound having an isoelectric point exceeding 4.5 include glycine. From the viewpoint of further easily stabilizing the pH of the abrasive liquid, the alkali component may include a compound having an amino group, may include a fatty acid amine, or may include a heterocyclic amine.

[0124] Examples of the fatty acid amine include monoamines such as methylamine, ethylamine, and tris(hydroxymethyl)aminomethane; diamines such as dimethylamine and diethylamine; and triamines such as trimethylamine and triethylamine. From the viewpoint of easily obtaining excellent polishing selectivity of silicon oxide with respect to silicon nitride, the alkali component may include a monoamine or may include tris(hydroxymethyl)aminomethane.

[0125] The heterocyclic amine is an amine having at least one heterocyclic ring. Examples of the heterocyclic amine include compounds having a pyrrolidine ring, a pyrrole ring, an imidazole ring, a pyrazole ring, an oxazole ring, a thiazole ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, a triazine ring, a tetrazine ring, etc. From the viewpoint of easily obtaining excellent polishing selectivity of silicon oxide with respect to silicon nitride, the alkali component may include an imidazole compound (a compound having an imidazole ring) or may include imidazole.

[0126] From the viewpoint of easily obtaining excellent polishing selectivity of silicon oxide with respect to silicon nitride, based on the total mass of the abrasive liquid, the content of the alkali component may be within the following range. The content of the alkali component may be 0.001% by mass or more, 0.005% by mass or more, 0.01% by mass or more, 0.03% by mass or more, 0.05% by mass or more, 0.07% by mass or more, or 0.08% by mass or more. The content of the alkali component may be 3% by mass or less, 1% by mass or less, 0.8% by mass or less, 0.6% by mass or less, 0.5% by mass or less, 0.4% by mass or less, 0.3% by mass or less, or 0.2% by mass or less. From these viewpoints, the content of the alkali component may be 0.001 to 3% by mass.

[0127] When the abrasive liquid according to the present embodiment contains the acid component A and the basic component, from the viewpoint of easily obtaining excellent polishing selectivity of silicon oxide with respect to silicon nitride, the mass ratio of the content of the basic component to the content of the acid component A (content of the basic component / content of the acid component A) may be 0.1 or more, 0.3 or more, 0.5 or more, 0.8 or more, 0.9 or more, 1 or more, 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, 1.5 or more, 1.6 or more, 1.7 or more, 1.8 or more, 1.9 or more, or 2 or more. The mass ratio may be 10 or less, 8 or less, 6 or less, 5 or less, 4 or less, 3.5 or less, 3 or less, 2.9 or less, 2.8 or less, 2.7 or less, 2.6 or less, or 2.5 or less. From these viewpoints, the mass ratio may be 0.1 to 10.

[0128] [Other additives]

[0129] The abrasive liquid according to the present embodiment may contain optional additives (except for the above acid component A, nonionic polymer, or compound corresponding to the basic component). Examples of the optional additives include oxidizing agents (such as hydrogen peroxide), dispersants (such as triethanol ethane), alcohols (such as 3-methoxy-3-methyl-1-butanol), acid components other than the acid component A (such as acid components having a carboxyl group), and the like. The abrasive liquid according to the present embodiment may contain a cationic polymer or may not contain a cationic polymer. Based on the total mass of the abrasive liquid, the content of the cationic polymer may be less than 0.0001% by mass.

[0130] (Water)

[0131] The abrasive liquid according to the present embodiment can contain water. Examples of the water include deionized water, ultrapure water, and the like. The content of the water may be the remainder of the abrasive liquid excluding the contents of the other constituent components.

[0132] (pH)

[0133] From the viewpoint of easily obtaining excellent polishing selectivity of silicon oxide with respect to silicon nitride, the pH of the polishing liquid according to the present embodiment exceeds 4.5. From the viewpoint of easily obtaining excellent polishing selectivity of silicon oxide with respect to silicon nitride, the pH of the polishing liquid may be 4.6 or more, 4.7 or more, 4.8 or more, 4.9 or more, 5 or more, more than 5, or 5.1 or more. From the viewpoint of easily obtaining excellent polishing selectivity of silicon oxide with respect to silicon nitride, the pH of the polishing liquid may be 12 or less, 11 or less, 10 or less, 9 or less, 8.8 or less, 8.6 or less, 8.4 or less, 8.2 or less, 8 or less, less than 8, 7.8 or less, 7.6 or less, 7.5 or less, less than 7.5, 7.4 or less, 7.2 or less, 7 or less, less than 7, 6.8 or less, 6.6 or less, 6.5 or less, less than 6.5, 6.4 or less, 6.2 or less, 6 or less, or less than 6. The pH of the polishing liquid may be 5.2 or more, 5.3 or more, 5.4 or more, 5.5 or more, 5.6 or more, 5.7 or more, 5.8 or more, 5.9 or more, 6 or more, or more than 6. The pH of the polishing liquid is defined as the pH at a liquid temperature of 25°C.

[0134] The pH of the polishing liquid according to the present embodiment can be measured using a pH meter (for example, Model D-51 manufactured by HORIBA, Ltd.). For example, after performing three-point calibration of the pH meter using phthalate pH buffer solution (pH: 4.01), neutral phosphate pH buffer solution (pH: 6.86), and borate pH buffer solution (pH: 9.18) as standard buffer solutions, the electrode of the pH meter is placed in the polishing liquid, and the value after stabilizing for 3 minutes or more is measured. The liquid temperatures of both the standard buffer solution and the polishing liquid are set to 25°C.

[0135] The polishing liquid according to the present embodiment can be stored as a single-liquid type polishing liquid containing at least abrasive grains containing a tetravalent metal element hydroxide and an acid component A, or can be stored as a multi-liquid type (for example, two-liquid type) polishing liquid set in which the constituent components of the above polishing liquid are divided into a slurry and an additive liquid, so that the slurry (first liquid) and the additive liquid (second liquid) are mixed to form the above polishing liquid. The slurry contains, for example, at least abrasive grains and water. The additive liquid contains, for example, at least acid component A and water. The alkali component, other additives, etc. are preferably contained in the additive liquid among the slurry and the additive liquid. The constituent components of the above polishing liquid can be stored as a polishing liquid set divided into three or more liquids.

[0136] In the above polishing liquid set, before or during polishing, the slurry and the additive liquid are mixed to prepare the polishing liquid. The single-liquid type polishing liquid can be stored as a storage liquid for the polishing liquid with a reduced water content, and is diluted with water during polishing for use. The multi-liquid type polishing liquid set can be stored as a storage liquid for the slurry with a reduced water content and a storage liquid for the additive liquid, and is diluted with water during polishing for use.

[0137] The method for manufacturing the abrasive liquid according to this embodiment includes a mixing step of mixing abrasive grains and acid component A. The mixing step may be a step of obtaining the abrasive liquid by mixing the abrasive grains and acid component A with each other. The mixing step may be a step of obtaining the abrasive liquid by mixing components other than the abrasive grains and acid component A (for example, nonionic polymers) with each other in addition to the abrasive grains and acid component A.

[0138] <Grinding method>

[0139] The grinding method according to this embodiment includes a grinding step of grinding a surface to be ground using the abrasive liquid according to this embodiment. In the grinding step, the material to be ground on the surface to be ground is ground and removed. The surface to be ground may contain silicon oxide and silicon nitride. That is, the surface to be ground may have a portion to be ground formed of silicon oxide and a portion to be ground formed of silicon nitride. The grinding step may be a step of grinding the surface to be ground containing silicon oxide and silicon nitride using the abrasive liquid according to this embodiment and selectively removing silicon oxide with respect to silicon nitride. As the abrasive liquid used in the grinding step, the above-mentioned one-liquid type abrasive liquid may be used, or an abrasive liquid obtained by mixing the slurry and the additive liquid in the above-mentioned abrasive liquid set may be used.

[0140] In the grinding step, for example, in a state where the surface to be ground of the substrate is pressed against the grinding pad (grinding cloth) of the grinding plate, the above-mentioned abrasive liquid is supplied between the surface to be ground and the grinding pad, and the substrate and the grinding plate are relatively moved to grind the surface to be ground.

[0141] Examples of the substrate as the object to be ground include a substrate to be ground and the like. Examples of the substrate to be ground include a substrate having a material to be ground formed on a substrate related to semiconductor manufacturing (for example, a semiconductor substrate formed with an STI pattern, a gate pattern, a wiring pattern, etc.). The portion to be ground of the substrate to be ground may contain silicon oxide and silicon nitride. The portion to be ground may be in the form of a film (film to be ground), or may be a silicon oxide film, a silicon nitride film, or the like.

[0142] The portion to be ground may be a silicon carbonitride film. The silicon carbonitride film is a film in which carbon atoms are doped in silicon nitride. It is possible to confirm that the portion to be ground is a silicon carbonitride film by Raman spectroscopy.

[0143] In the grinding method according to this embodiment, as the grinding device, a general grinding device can be used, which has: a bracket capable of holding a substrate having a surface to be ground; and a grinding plate capable of attaching a grinding pad. Motors capable of changing the rotation speed can be installed on the bracket and the grinding plate, respectively. As the grinding device, for example, a grinding device manufactured by APPLIED MATERIALS: Reflexion can be used.

[0144] As the polishing pad, general non-woven fabrics, foams, non-foams, etc. can be used. As the material of the polishing pad, resins such as polyurethane, acrylic resin, polyester, acrylic-ester copolymer, polytetrafluoroethylene, polypropylene, polyethylene, poly-4-methylpentene, cellulose, cellulose ester, polyamide (e.g., nylon (trade name) and aramid), polyimide, polyimide amide, polysiloxane copolymer, ethylene oxide compound, phenolic resin, polystyrene, polycarbonate, and epoxy resin can be used.

[0145] The polishing conditions are not limited, but in order to prevent the substrate from flying out, the rotation speed of the polishing plate can be 200 min -1 Hereinafter, from the viewpoint of sufficiently suppressing the generation of polishing scratches, the polishing pressure (processing load) applied to the substrate can be 100 kPa or less. During polishing, a polishing liquid can be continuously supplied to the polishing pad using a pump or the like. The supply amount is not limited, but the surface of the polishing pad can always be covered with the polishing liquid.

[0146] After polishing, the substrate can be thoroughly cleaned in running water to remove the particles attached to the substrate. In addition to pure water, cleaning chemical liquids such as dilute hydrofluoric acid and ammonia water can also be used for cleaning. To improve the cleaning efficiency, a brush can also be used. And after cleaning, a spin dryer or the like can be used to flick off the water droplets attached to the substrate, and then the substrate can be dried.

[0147] The polishing liquid and polishing method according to the present embodiment are applicable not only to film-like polishing objects but also to various substrates made of glass, silicon, SiC, SiGe, Ge, GaN, GaP, GaAs, sapphire, plastic, etc.

[0148] The polishing liquid and polishing method according to the present embodiment can be used not only in the manufacture of semiconductor devices but also in image display devices such as TFT liquid crystals and organic ELs; optical parts such as photomasks, lenses, prisms, optical fibers, and single crystal scintillators; optical elements such as optical switching elements and optical waveguides; light emitting elements such as solid state lasers and blue laser LEDs; and the manufacture of magnetic storage devices such as disks and magnetic heads.

[0149] <Manufacturing method, etc.>

[0150] The manufacturing method of the parts according to this embodiment includes a part manufacturing process of obtaining parts by using a substrate (a component to be polished) polished by the polishing method according to this embodiment. The parts according to this embodiment are parts obtained by the manufacturing method of the parts according to this embodiment. The parts according to this embodiment are not particularly limited, but may be electronic parts (for example, semiconductor parts such as semiconductor packages), may be wafers (for example, semiconductor wafers), or may be chips (for example, semiconductor chips). As one mode of the manufacturing method of the parts according to this embodiment, in the manufacturing method of the electronic parts according to this embodiment, electronic parts are obtained by using a substrate polished by the polishing method according to this embodiment. As one mode of the manufacturing method of the parts according to this embodiment, in the manufacturing method of the semiconductor parts according to this embodiment, semiconductor parts (for example, semiconductor packages) are obtained by using a substrate polished by the polishing method according to this embodiment. The manufacturing method of the parts according to this embodiment may include a polishing process of polishing a substrate by the polishing method according to this embodiment before the part manufacturing process.

[0151] As one mode of the part manufacturing process, the manufacturing method of the parts according to this embodiment may include a singulation process of singulating a substrate (a component to be polished) polished by the polishing method according to this embodiment. The singulation process may be, for example, a process of cutting a wafer (for example, a semiconductor wafer) polished by the polishing method according to this embodiment to obtain chips (for example, semiconductor chips). As one mode of the manufacturing method of the parts according to this embodiment, the manufacturing method of the electronic parts according to this embodiment may include a process of obtaining electronic parts (for example, semiconductor parts) by singulating a substrate polished by the polishing method according to this embodiment. As one mode of the manufacturing method of the parts according to this embodiment, the manufacturing method of the semiconductor parts according to this embodiment may include a process of obtaining semiconductor parts (for example, semiconductor packages) by singulating a substrate polished by the polishing method according to this embodiment.

[0152] As a method of a component manufacturing process, the manufacturing method of the component according to the present embodiment may include a connecting step of connecting (for example, electrically connecting) a substrate (a component to be polished) polished by the polishing method according to the present embodiment and other components to be connected. The component to be connected to the substrate polished by the polishing method according to the present embodiment is not particularly limited, and may be a substrate polished by the polishing method according to the present embodiment, or may be a component to be connected different from the substrate polished by the polishing method according to the present embodiment. In the connecting step, the substrate and the component to be connected may be directly connected (connected in a state where the substrate and the component to be connected are in contact), or the substrate and the component to be connected may be connected via other components (such as conductive components). The connecting step can be performed before the singulation process, after the singulation process, or before and after the singulation process.

[0153] The connecting step may be a step of connecting the polished surface of the substrate polished by the polishing method according to the present embodiment and the component to be connected, or may be a step of connecting the connecting surface of the substrate polished by the polishing method according to the present embodiment and the connecting surface of the component to be connected. The connecting surface of the substrate may be the polished surface polished by the polishing method according to the present embodiment. Through the connecting step, a connected body including the substrate and the component to be connected can be obtained. In the connecting step, when the connecting surface of the substrate has a metal portion, the component to be connected may be brought into contact with the metal portion. In the connecting step, when the connecting surface of the substrate has a metal portion and the connecting surface of the component to be connected has a metal portion, the metal portions may be brought into contact with each other. The metal portion may contain copper.

[0154] The device according to the present embodiment (for example, an electronic device such as a semiconductor device) includes at least one selected from the group consisting of a substrate polished by the polishing method according to the present embodiment and the component according to the present embodiment.

[0155] Examples

[0156] Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited to these examples as long as the technical idea of the present invention is not departed from. For example, the type and blending ratio of the material of the polishing liquid may be types and ratios other than those described in the present examples, and the composition and structure of the object to be polished may also be compositions and structures other than those described in the present examples.

[0157] <Preparation of abrasive grains>

[0158] 350 g of Ce(NH 4 ) 2 (NO 3)A solution was obtained by mixing a 650 mass% aqueous solution (manufactured by NIHON KAGAKU SANGYO CO., LTD., product name: CAN50 solution) with 7825 g of pure water. Next, the solution was stirred, and 750 g of an aqueous imidazole solution (10 mass% aqueous solution, 1.47 mol / L) was added dropwise at a mixing rate of 5 mL / minute to obtain a precipitate containing cerium hydroxide. Cerium hydroxide was synthesized at a temperature of 25 °C and a stirring speed of 400 min -1 under the condition. Stirring was carried out using a three-blade pitched blade with a total blade length of 5 cm.

[0159] After centrifuging the obtained precipitate (precipitate containing cerium hydroxide) (4000 min -1 , 5 minutes), the liquid phase was removed by decantation, thereby performing solid-liquid separation. After mixing 10 g of the particles obtained by solid-liquid separation and 990 g of water, the particles were dispersed in water using an ultrasonic cleaner to prepare a cerium hydroxide slurry containing abrasive grains containing cerium hydroxide (content of abrasive grains: 1.0 mass%).

[0160] <Measurement of average particle size>

[0161] The result of measuring the average particle size of the abrasive grains (abrasive grains containing cerium hydroxide) in the cerium hydroxide slurry using N5 manufactured by Beckman Coulter KK, product name: N5, was 3 nm. The measurement method is as follows. First, approximately 1 mL of a measurement sample (cerium hydroxide slurry, aqueous dispersion) containing 1.0 mass% of abrasive grains was placed in a 1 cm square cell, and the cell was set inside N5. The refractive index of the measurement sample information of the N5 software was set to 1.333, the viscosity was set to 0.887 mPa·s, and the measurement was carried out at 25 °C.

[0162] <Structural analysis of abrasive grains>

[0163] An appropriate amount of the cerium hydroxide slurry was taken, vacuum-dried to separate the abrasive grains, and then thoroughly washed with pure water to obtain a specimen. Regarding the obtained specimen, as a result of the measurement based on the FT-IR ATR method, in addition to the peak based on hydroxide ions (OH - ), a peak based on nitrate ions (NO 3 - ) was also observed. And, regarding the same specimen, as a result of the XPS (N-XPS) measurement for nitrogen, no peak based on NH 4 +peaks, and peaks based on nitrate ions were observed. From these results, it was confirmed that at least a part of the abrasive grains contained in the cerium hydroxide slurry included particles having nitrate ions bonded to cerium elements. Further, particles having hydroxide ions bonded to cerium elements were contained in at least a part of the abrasive grains, and thus it was confirmed that the abrasive grains contained cerium hydroxide. From these results, it was confirmed that the hydroxide of cerium contained hydroxide ions bonded to cerium elements.

[0164] <Preparation of CMP polishing liquid>

[0165] (Example 1)

[0166] 100 g of an additive solution containing 1.6% by mass of sulfanilic acid, 5% by mass of polyglycerol [nonionic polymer, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., product name: polyglycerol #750, weight average molecular weight: 750, average degree of polymerization 10], 1.4% by mass of imidazole and water (the remainder), 850 g of water, and 50 g of the above cerium hydroxide slurry were mixed to prepare a CMP polishing liquid containing 0.05% by mass of abrasive grains containing cerium hydroxide, 0.16% by mass of sulfanilic acid, 0.5% by mass of polyglycerol, and 0.14% by mass of imidazole.

[0167] (Examples 2 to 15 and Comparative Example 1, Comparative Example 2)

[0168] The types and contents of the acid component and the base component were changed, and except for this, a CMP polishing liquid having the composition shown in Table 1 was prepared in the same manner as in Example 1. In addition, the acid components A1 to A8 and the base components B1 to B2 in the table are as follows.

[0169] [Acid component]

[0170] A1: Sulfanilic acid

[0171] A2: 3-Pyridinesulfonic acid

[0172] A3: Ammonium sulfonate

[0173] A4: Benzenesulfonic acid

[0174] A5: 2,5-Dimethylbenzenesulfonic acid

[0175] A6: Isoquinoline-5-sulfonic acid

[0176] A7: 4-Aminobenzoic acid

[0177] A8: Acetic acid

[0178] [Base component]

[0179] B1: Imidazole

[0180] B2: Tris(hydroxymethyl)aminomethane

[0181] <Evaluation>

[0182] (pH of CMP polishing slurry)

[0183] The pH of the CMP polishing slurry was measured under the following conditions. The results are shown in Table 1.

[0184] Measurement temperature: 25 °C

[0185] Measurement device: Model D-51 manufactured by HORIBA, Ltd.

[0186] 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 (25 °C)), the electrode was placed in the CMP polishing slurry, and the pH after stabilization for 3 minutes or more was measured using the above measurement device.

[0187] (Particle size of abrasive grains)

[0188] The average particle size of the abrasive grains (abrasive grains containing cerium hydroxide) in the CMP polishing slurries of Examples 1 to 15 and Comparative Examples 1 and 2 was measured under the following conditions, and the result was 12 nm.

[0189] Measurement temperature: 25 °C

[0190] Measurement device: Manufactured by Beckman Coulter KK, product name: DelsaMax PRO

[0191] Measurement method: After placing approximately 0.5 mL of the CMP polishing slurry in a measurement cell (disposable micro cuvette) of 12.5 mm × 12.5 mm × 45 mm (height), the cell was set inside the DelsaMax PRO. The refractive index of the measurement sample information was set to 1.333, the viscosity was set to 0.887 mPa·s, and the measurement was performed at 25 °C, and the value displayed as Unimodal SizeMean: single peak size average (cumulative diameter) was read.

[0192] (Polishing rate)

[0193] The following blank wafers were polished using the above CMP polishing slurry under the following CMP polishing conditions.

[0194] [Blank wafer]

[0195] A blank wafer having a silicon oxide film with a thickness of 1000 nm on a silicon substrate (diameter: 300 mm)

[0196] A blank wafer having a silicon nitride film with a thickness of 250 nm on a silicon substrate (diameter: 300 mm)

[0197] [CMP polishing conditions]

[0198] Polishing apparatus: FREX 300X (manufactured by Ebara Corporation)

[0199] CMP polishing slurry flow rate: 200 mL / min

[0200] Substrate to be polished: the above-mentioned blank wafer

[0201] Polishing pad: a foamed polyurethane resin having closed-cell foam (manufactured by ROHM AND HAAS ELECTRONIC MATERIALS CMP INC, model IC1010)

[0202] · Polishing pressure: 20.7 kPa (3.0 psi)

[0203] Relative speed between the substrate to be polished and the polishing platen: 100.5 m / min

[0204] Polishing time: 30 seconds

[0205] Cleaning of the wafer: After CMP processing, ultrasonic waves are applied and the wafer is washed with water, and then dried using a spin dryer.

[0206] [Calculation of polishing rate and polishing rate ratio]

[0207] Using an optical interference film thickness measurement device (device name: F80) manufactured by Filmetrics, INC, the film thicknesses of the films to be polished (silicon oxide film and silicon nitride film) before and after polishing were measured at 65 points. For the 65-point film thickness measurement, on a straight line including the center of the wafer, with the center of the wafer as a reference, at positions of 149 mm, 148 mm, 147 mm, and 145 mm, at positions every 5 mm between 145 mm and -145 mm (140 mm, 135 mm,..., -135 mm, -140 mm), and at positions of -145 mm, -147 mm, -148 mm, and -149 mm (with the center of the wafer as a reference, negative values represent distances on the opposite side of the positive distance). The change in film thickness was calculated using the average value of the 65-point film thicknesses. Based on the change in film thickness and the polishing time, the polishing rates of the materials to be polished (polishing rate RO of silicon oxide and polishing rate RN of silicon nitride) were calculated using the following formula. And, the polishing rate ratio (RO / RN) of the polishing rate RO of silicon oxide to the polishing rate RN of silicon nitride was calculated. The results are shown in Table 1.

[0208]

[0209] [Table 1]

[0210]

[0211] In the examples, it was confirmed that the grinding rate ratio (RO / RN) of the grinding rate RO of silicon oxide to the grinding rate RN of silicon nitride was 20 or more, and thus excellent grinding selectivity of silicon oxide to silicon nitride could be obtained.

Claims

1. A polishing liquid comprising abrasive grains and an acid component, The acid component includes a compound having at least one selected from the group consisting of a sulfonic group and a sulfonate group, and the compound does not include sulfuric acid and its salts, The pH of the polishing liquid exceeds 4.

5.

2. The polishing liquid according to claim 1, wherein The abrasive grains contain cerium hydroxide.

3. The polishing liquid according to claim 1, wherein The acid component includes an aromatic compound having at least one selected from the group consisting of a sulfonic group and a sulfonate group.

4. The polishing liquid according to claim 1, wherein The acid component includes a compound having no amino group.

5. The polishing liquid according to claim 1, wherein The acid component includes an aminosulfonic acid compound.

6. The polishing liquid according to claim 1, wherein The acid component includes at least one selected from the group consisting of p-aminobenzenesulfonic acid and salts thereof.

7. The polishing liquid according to claim 1, wherein The content of the acid component exceeds 0.2 mass % based on the total mass of the polishing liquid. The polishing liquid according to claim 1 , further comprising a nonionic polymer.

9. The polishing liquid according to claim 8, wherein The nonionic polymer includes a glycerin-based polymer. 10 . The polishing liquid according to claim 1 , further comprising an alkali component. The polishing liquid according to claim 1 , which is used for polishing a surface to be polished containing silicon oxide and silicon nitride. 12 . A polishing method comprising the step of polishing a surface to be polished using the polishing liquid according to claim 1 .

13. The grinding method according to claim 12, wherein: The polished surface contains silicon oxide and silicon nitride. 14 . A method for producing a part, comprising the step of obtaining the part using a member to be polished polished by the polishing method according to claim 12 .

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