WO2016021325A1 - Polishing liquid for cmp and polishing method using same - Google Patents

Polishing liquid for cmp and polishing method using same Download PDF

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Publication number
WO2016021325A1
WO2016021325A1 PCT/JP2015/068377 JP2015068377W WO2016021325A1 WO 2016021325 A1 WO2016021325 A1 WO 2016021325A1 JP 2015068377 W JP2015068377 W JP 2015068377W WO 2016021325 A1 WO2016021325 A1 WO 2016021325A1
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Prior art keywords
polishing
cmp
additive
liquid
inorganic insulating
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PCT/JP2015/068377
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French (fr)
Japanese (ja)
Inventor
吉川　茂
寿夫 瀧澤
宗宏 太田
奈央 山村
愛子 木野
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日立化成株式会社
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Publication of WO2016021325A1 publication Critical patent/WO2016021325A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00—Lapping machines or devices; Accessories
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K3/00—Materials not provided for elsewhere
    • C09K3/14—Anti-slip materials; Abrasives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
    • H01L21/304—Mechanical treatment, e.g. grinding, polishing, cutting

Definitions

  • the present invention relates to a CMP polishing liquid for use in chemical mechanical polishing (CMP), and a polishing method using the same.
  • CMP chemical mechanical polishing
  • the present invention relates to, for example, a CMP polishing liquid for polishing a semiconductor wafer material, and a polishing method using the same.
  • the present invention particularly relates to a polishing slurry for CMP for polishing silicon oxide provided on the surface of a semiconductor wafer, and a polishing method using the same.
  • the CMP technique is a technique for flattening the surface after forming a thin film on a substrate by chemical vapor deposition (CVD) or the like.
  • CVD chemical vapor deposition
  • processing by CMP is indispensable. If the surface of the substrate is uneven, inconveniences such as inability to focus in the exposure process and insufficient formation of a fine wiring structure occur.
  • the CMP technology is a process for forming an element isolation region by polishing a plasma oxide material (BPSG, HDP-SiO 2 , p-TEOS, etc.), a process for forming an interlayer insulating material, or a silicon oxide in a device manufacturing process.
  • the present invention is also applied to a step of flattening a plug (for example, an Al / Cu plug) after embedding a member (for example, a silicon oxide film) containing metal in a metal wiring.
  • CMP is usually performed using an apparatus capable of supplying a polishing liquid onto a polishing pad.
  • the substrate surface is polished by pressing the substrate against the polishing pad while supplying a polishing liquid between the substrate surface and the polishing pad.
  • a high-performance polishing liquid is one of elemental techniques, and various polishing liquids have been developed so far.
  • a groove is provided in advance on the substrate surface, and an inorganic insulating material (for example, silicon oxide) is formed by CVD or the like so as to fill the groove.
  • the element isolation region is formed by planarizing the surface of the inorganic insulating material by CMP.
  • STI shallow trench isolation
  • the polishing process of the inorganic insulating material is divided into two stages to improve the production efficiency.
  • the first step rough cutting step
  • the inorganic insulating material provided on the substrate is removed at high speed.
  • the second step finishing step
  • the inorganic insulating material is finished to an arbitrary thickness.
  • polishing liquids for CMP for removing inorganic insulating materials for example, silicon oxide
  • a polishing liquid containing a compound having a specific chemical structure is known as a polishing liquid that can be used in the first step (roughing step) (for example, see Patent Document 1 below).
  • the step removal property is given priority over the polishing rate in the first step.
  • the step removability indicates that the inorganic insulating material (convex portion surface) in the pattern wafer having the inorganic insulating material on the convex surface with respect to the polishing amount (polishing rate) of the inorganic insulating material in the blanket wafer having the inorganic insulating material on the surface.
  • Polishing amount (polishing speed) ratio polishing amount in pattern wafer / polishing amount in blanket wafer.
  • the step-removability may be low.
  • the decrease in the step removal property increases the removal time of the inorganic insulating material in the second step and causes a deterioration in throughput, and also decreases the flatness after polishing. If the flatness after polishing is lowered, the depth of focus of lithography cannot be ensured, and it becomes difficult to form a device.
  • the present invention is intended to solve the above-described problems, and an object of the present invention is to provide a polishing slurry for CMP that can achieve both a high polishing rate and step removal performance for an inorganic insulating material, and a polishing method using the same. .
  • the present inventors have made extensive studies on additives to be added to the CMP polishing liquid.
  • the present inventors prepared many polishing liquids for CMP using various organic compounds as additives. These CMP polishing liquids were used to polish the inorganic insulating material, and the polishing rate and the step removal performance were evaluated.
  • the use of 4-pyrone compounds having a specific chemical structure and compounds having acidic functional groups and basic functional groups as additives makes it possible to achieve both high polishing speed and step removal performance for inorganic insulating materials.
  • the present invention has been completed.
  • the CMP polishing liquid according to the present invention contains abrasive grains, a first additive, a second additive, and water, and the first additive is represented by the following general formula (1).
  • the second additive is a compound having an acidic functional group and a basic functional group. [Wherein, X 11 , X 12 and X 13 are each independently a hydrogen atom or a monovalent substituent. ]
  • the CMP polishing liquid according to the present invention can achieve both a high polishing rate and a step removal property for an inorganic insulating material.
  • the interaction between the polishing liquid for CMP and the inorganic insulating material can be achieved by using a 4-pyrone compound having a specific chemical structure as the first additive.
  • the polishing rate is increased.
  • the functional group of the second additive reacts with the inorganic insulating material.
  • strong load dependency occurs. Thereby, it is presumed that the step removability with a heavy load increases, and as a result, the step removability increases.
  • the CMP polishing liquid according to the present invention has a feature that it is possible to achieve both a high polishing rate and a high level difference removal property, and is therefore suitable for polishing an inorganic insulating material having irregularities.
  • the CMP polishing liquid according to the present invention has an advantage that both a high polishing rate and a high level of step removal can be achieved even when polishing a semiconductor material that is relatively difficult to remove steps with the conventional CMP polishing liquid. is there. For example, even when polishing an inorganic insulating material having a T-shaped or lattice-shaped concave or convex portion like a semiconductor substrate having a memory cell, both a high polishing rate and a high level difference can be achieved.
  • the polishing slurry for CMP containing the first additive in addition to achieving a high polishing rate for the inorganic insulating material, aggregation of abrasive grains can be suppressed.
  • the 4-pyrone compound having the specific structure described above is an additive that can increase the interaction between the polishing slurry for CMP and the inorganic insulating material. Therefore, since there is no effect of weakening the repulsive force such as electrostatic repulsive force between the abrasive grains, it is presumed that the aggregation of the abrasive grains can be suppressed.
  • the first additive is a group consisting of 3-hydroxy-2-methyl-4-pyrone, 5-hydroxy-2- (hydroxymethyl) -4-pyrone, and 2-ethyl-3-hydroxy-4-pyrone It is preferably at least one selected from the group. Thereby, a higher polishing rate can be obtained.
  • the acidic functional group of the second additive is preferably a sulfonic acid group.
  • the basic functional group of the second additive is preferably an amino group. In these cases, high step-removability can be easily obtained.
  • the second additive is more preferably at least one selected from the group consisting of sulfamic acid and aminobenzenesulfonic acid.
  • the content of the first additive is preferably 0.001 to 5 parts by mass with respect to 100 parts by mass of the CMP polishing liquid. Thereby, the improvement effect of the polishing rate can be obtained more efficiently.
  • the content of the second additive is preferably 0.0001 to 1 part by mass with respect to 100 parts by mass of the CMP polishing liquid.
  • the abrasive preferably contains a cerium compound.
  • the cerium-based compound is preferably cerium oxide.
  • the CMP polishing liquid according to the present invention may be used for polishing an inorganic insulating material. That is, the present invention provides an application of the CMP polishing liquid to polishing a substrate having an inorganic insulating material on the surface.
  • the present invention provides a polishing method using the CMP polishing liquid. That is, the polishing method according to the present invention is a polishing method for polishing a substrate having an inorganic insulating material on the surface, and the CMP polishing liquid according to the present invention is supplied between the inorganic insulating material and the polishing pad. And a step of polishing the inorganic insulating material with a polishing pad. According to such a polishing method, it is possible to achieve both a high polishing rate and a step removal property for the inorganic insulating material. In addition, since a high polishing rate is achieved without largely depending on the surface shape of the substrate to be polished, the polishing method is suitable for roughing an inorganic insulating material and polishing a semiconductor substrate having memory cells.
  • the present invention it is possible to achieve both a high polishing rate and a step removal property for an inorganic insulating material (for example, silicon oxide).
  • an inorganic insulating material for example, silicon oxide
  • ADVANTAGE OF THE INVENTION According to this invention, the application to the grinding
  • polishing of a silicon oxide of the polishing liquid for CMP can be provided.
  • ADVANTAGE OF THE INVENTION the application to the grinding
  • ADVANTAGE OF THE INVENTION the application to the grinding
  • ADVANTAGE OF THE INVENTION the application to polishing of the semiconductor substrate which has a memory cell of CMP polishing liquid can be provided.
  • ADVANTAGE OF THE INVENTION the application to the grinding
  • each component in the composition means the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition. .
  • the polishing slurry for CMP contains abrasive grains (polishing particles), a first additive, a second additive, and water, and the first additive is 4-pyrone. And a second additive is a compound having an acidic functional group and a basic functional group.
  • abrasive grains polishing particles
  • a second additive is a compound having an acidic functional group and a basic functional group.
  • the abrasive grains can include, for example, a cerium compound, alumina, silica, titania, zirconia, magnesia, mullite, silicon nitride, ⁇ -sialon, aluminum nitride, titanium nitride, silicon carbide, boron carbide, and the like.
  • a constituent component of these abrasive grains one kind may be used alone, or two or more kinds may be used in combination. Among these, the addition effect of the first additive and the second additive can be satisfactorily exhibited, and the high polishing rate and the step removal property for the inorganic insulating material having unevenness (for example, silicon oxide) are more highly compatible. From the viewpoint, a cerium-based compound is preferable.
  • a polishing liquid for CMP using abrasive grains containing a cerium-based compound has a feature that there are relatively few polishing flaws on a polished surface (referred to as a surface after polishing; hereinafter the same).
  • a surface after polishing Conventionally, from the viewpoint of easily achieving a high polishing rate for an inorganic insulating material (for example, silicon oxide), CMP polishing liquids containing silica particles as abrasive grains have been widely used.
  • CMP polishing liquids using silica particles generally have a problem that polishing scratches are likely to occur on the polished surface. In a device having a fine pattern with a wiring width of 45 nm or later, even a fine scratch that has not been a problem may affect the reliability of the device.
  • a conventional CMP polishing liquid using abrasive grains containing a cerium compound tends to have a slightly lower polishing rate for inorganic insulating materials (eg, silicon oxide) than a CMP polishing liquid using silica particles. It was.
  • a high polishing rate and a step difference with respect to an inorganic insulating material can be obtained by using an abrasive containing a cerium compound, the first additive, and the second additive in combination. Removability is compatible. This suggests that the combination of the cerium compound, the first additive, and the second additive is particularly effective for polishing.
  • cerium compound examples include cerium oxide, cerium hydroxide, ammonium cerium nitrate, cerium acetate, cerium sulfate hydrate, cerium bromate, cerium bromide, cerium chloride, cerium oxalate, cerium nitrate, and cerium carbonate. .
  • cerium oxide is preferable. By using cerium oxide, an excellent polished surface with few polishing flaws can be obtained while achieving both a high polishing rate and a high level difference removability.
  • the abrasive grains preferably include polycrystalline cerium oxide having a crystal grain boundary (for example, polycrystalline cerium oxide having a plurality of crystallites surrounded by the crystal grain boundary).
  • the polycrystalline cerium oxide particles having such a structure are different from simple aggregates in which single crystal particles are aggregated, and become fine due to stress during polishing, and at the same time, have an active surface (a surface not exposed to the outside before becoming fine). Since it appears one after another, it is considered that a high polishing rate for an inorganic insulating material (for example, silicon oxide) can be maintained at a high level.
  • Such polycrystalline cerium oxide particles are described in detail in, for example, International Publication No. WO99 / 31195.
  • the method for producing abrasive grains containing cerium oxide is not particularly limited, and examples include a liquid phase synthesis; a method of oxidizing by baking or hydrogen peroxide.
  • a method of firing a cerium source such as cerium carbonate is preferred.
  • the firing temperature is preferably 350 to 900 ° C.
  • the produced cerium oxide particles are aggregated, it is preferably mechanically pulverized.
  • the pulverization method is not particularly limited, but for example, dry pulverization using a jet mill or the like; wet pulverization using a planetary bead mill or the like is preferable.
  • the jet mill is described in, for example, “Chemical Engineering Papers”, Vol. 6, No. (1980), pp. 527-532.
  • the average particle size of the abrasive grains is preferably 50 nm or more, more preferably 70 nm or more, and still more preferably 80 nm or more.
  • the polishing rate for the inorganic insulating material for example, silicon oxide
  • the average particle size of the abrasive grains is preferably 500 nm or less, more preferably 300 nm or less, still more preferably 280 nm or less, particularly preferably 250 nm or less, and extremely preferably 200 nm or less.
  • the average particle size is 500 nm or less, polishing scratches can be suppressed as compared with the case where the average particle size exceeds 500 nm.
  • a conventionally known method can be used.
  • control of the firing temperature, firing time, pulverization conditions, etc .; application of filtration, classification, etc. may be mentioned.
  • the average particle diameter of the abrasive grains means the median value of the volume distribution obtained by measuring the slurry sample in which the abrasive grains are dispersed with a dynamic light scattering particle size distribution meter. Specifically, it is a value measured using LB-500 (trade name) manufactured by HORIBA, Ltd. Adjust the content of abrasive grains in the slurry sample so that the abrasive grain content is 0.5% by mass based on the total mass of the slurry sample, and set this in the LB-500 to measure the median volume distribution I do. The degree of agglomeration of abrasive grains can also be evaluated by measuring the median diameter (cumulative median value) with LB-500.
  • the content of the abrasive grains is 0.5 mass% based on the total mass of the slurry sample by concentrating or diluting the CMP polishing liquid with water. After adjusting the content of the abrasive grains of the slurry sample so as to become, it can be measured by the same method.
  • the content of the abrasive grains is preferably 0.10 parts by mass or more, more preferably 0.15 parts by mass or more, and further 0.20 parts by mass or more with respect to 100 parts by mass of the polishing slurry for CMP. preferable.
  • the content of the abrasive is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, still more preferably 3.0 parts by mass or less, and 2.0 parts by mass with respect to 100 parts by mass of the polishing slurry for CMP.
  • the following is particularly preferable, and 1.0 mass part or less is extremely preferable.
  • the content of the abrasive grains is 10 parts by mass or less, the aggregation of the abrasive grains tends to be suppressed as compared with the case where the content exceeds 10 parts by mass, and a high polishing rate tends to be achieved.
  • the first additive is a 4-pyrone compound represented by the following general formula (1).
  • the polishing slurry for CMP according to the present embodiment by using the 4-pyrone compound represented by the general formula (1) as the first additive, compared to the conventional polishing slurry for CMP, A high polishing rate for inorganic insulating materials can be achieved.
  • X 11 , X 12 and X 13 are each independently a hydrogen atom or a monovalent substituent.
  • the monovalent substituent include an aldehyde group, a hydroxy group (hydroxyl group), a carboxyl group, a sulfonic acid group, a phosphoric acid group, a bromine atom, a chlorine atom, an iodine atom, a fluorine atom, a nitro group, a hydrazine group, and a carbon number of 1 to 8 alkyl groups (which may be substituted with OH, COOH, Br, Cl, I, or NO 2 ), aryl groups having 6 to 12 carbon atoms, alkenyl groups having 1 to 8 carbon atoms, and the like.
  • a methyl group, an ethyl group, or a hydroxymethyl group is preferable.
  • the monovalent substituent is bonded to a carbon atom adjacent to the oxy group from the viewpoint of easy synthesis. It is preferable. That is, it is preferable that at least one of X 11 and X 12 is a monovalent substituent. Furthermore, easy in view of improvement is obtained of the abrasive grains of the polishing ability, it is preferable that at least two are hydrogen atom of X 11, X 12 and X 13, among the X 11, X 12 and X 13 2 More preferably, one is a hydrogen atom.
  • the 4-pyrone compound has a structure in which a hydroxy group is bonded to at least a carbon atom adjacent to the carbon atom of the carbonyl group.
  • the “4-pyrone compound” has a 6-membered ring ( ⁇ -pyrone ring) structure in which an oxy group and a carbonyl group are included and the carbonyl group is located at the 4-position with respect to the oxy group. It is a heterocyclic compound.
  • a hydroxy group is bonded to a carbon atom adjacent to the carbonyl group in the ⁇ -pyrone ring, and a substituent other than a hydrogen atom is attached to the other carbon atom. May be substituted.
  • 3-hydroxy-2-methyl-4-pyrone also known as 3-hydroxy-2-methyl-4H-pyran-4-one, Maltol
  • 5-hydroxy-2- (hydroxymethyl) -4-pyrone also known as 5-hydroxy-2- (hydroxymethyl) -4H-pyran-4-one, kojic acid
  • 2-ethyl-3 At least one compound selected from the group consisting of -hydroxy-4-pyrone (alias: 2-ethyl-3-hydroxy-4H-pyran-4-one) is preferred.
  • the first additive one kind may be used alone, or two or more kinds may be used in combination.
  • a high polishing rate can also be obtained by using a combination of two or more of the first additives.
  • the first additive is preferably water-soluble.
  • a desired amount of the first additive can be dissolved well in the polishing slurry for CMP, and an effect of improving the polishing rate and agglomeration of abrasive grains can be achieved.
  • the suppression effect can be achieved to a higher level.
  • the solubility of the first additive in 100 g of water at room temperature (25 ° C.) is preferably 0.001 g or more, more preferably 0.005 g or more, still more preferably 0.01 g or more, and particularly preferably 0.05 g or more.
  • the upper limit of solubility is not particularly limited.
  • the content of the first additive is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, still more preferably 0.01 parts by mass or more, with respect to 100 parts by mass of the polishing slurry for CMP. 0.02 parts by mass or more is particularly preferable, and 0.03 parts by mass or more is very preferable.
  • the content of the first additive is 0.001 part by mass or more, there is a tendency that a stable polishing rate is easily achieved as compared to the case of less than 0.001 part by mass.
  • the content of the first additive is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, still more preferably 1 part by mass or less, and 0.5 parts by mass or less with respect to 100 parts by mass of the polishing slurry for CMP. Is particularly preferable, and 0.3 parts by mass or less is extremely preferable.
  • the content of the first additive is 5 parts by mass or less, aggregation of abrasive grains tends to be suppressed as compared with the case where the content exceeds 5 parts by mass, and a high polishing rate tends to be easily achieved.
  • the CMP polishing liquid according to the present embodiment contains a compound having an acidic functional group and a basic functional group (excluding a compound corresponding to the first additive) as the second additive. Thereby, in addition to a high polishing rate, high step removal performance can be obtained.
  • An acidic functional group is a functional group that exhibits acidity in an aqueous solution.
  • Examples of the acidic functional group include a sulfonic acid group, a sulfonic acid group, a carboxyl group, a carboxylic acid group, a phosphoric acid group, and a phosphoric acid group, and a sulfonic acid group is preferable.
  • the basic functional group is a functional group that exhibits basicity in an aqueous solution. Examples of basic functional groups include amino groups.
  • the acid dissociation constant pKa of the second additive at room temperature (25 ° C.) (the negative common logarithm of the equilibrium constant Ka (logarithm of the reciprocal), and when there are two or more pKa, the lowest first step pKa1) is Less than 4 is preferable, 3.5 or less is more preferable, and 3.3 or less is more preferable.
  • the lower limit of the acid dissociation constant pKa is not particularly limited and is, for example, ⁇ 10 or more.
  • an amino group-containing sulfonic acid compound is preferable.
  • the “amino group-containing sulfonic acid compound” means at least one selected from the group consisting of a sulfonic acid group (sulfo group, —SO 3 H) and a sulfonic acid group (—SO 3 M: M is a metal atom), an amino group (—NH 2 ) in one molecule.
  • the metal atom M of the sulfonate group include alkali metals such as Na and K, and alkaline earth metals such as Mg and Ca.
  • amino group-containing sulfonic acid compounds include sulfamic acid (also known as amidosulfuric acid), aminomethanesulfonic acid, aminoethanesulfonic acid (1-aminoethanesulfonic acid, 2-aminoethanesulfonic acid, etc.), aminopropanesulfonic acid, amino Benzenesulfonic acid (ortanylic acid (also known as 2-aminobenzenesulfonic acid), methanylic acid (also known as 3-aminobenzenesulfonic acid), sulfanilic acid (also known as 4-aminobenzenesulfonic acid), aminonaphthalenesulfonic acid, These salts (for example, salts containing the metal atom M) and the like can be mentioned.
  • sulfamic acid also known as amidosulfuric acid
  • aminomethanesulfonic acid aminoethanesulfonic acid (1-aminoethanesulfonic acid
  • the second additive is preferably at least one selected from the group consisting of sulfamic acid and aminobenzene sulfonic acid from the viewpoint of easily obtaining high step removal, and at least selected from the group consisting of sulfamic acid and sulfanilic acid.
  • One type is more preferable.
  • the second additive one kind may be used alone, or two or more kinds may be used in combination.
  • the molecular weight of the second additive is preferably 500 or less, more preferably 300 or less, still more preferably 250 or less, and even more preferably 200 or less, from the viewpoint that the functional group of the second additive easily reacts with the inorganic insulating material. Particularly preferred.
  • the lower limit of the molecular weight is, for example, 50 or more.
  • the content of the second additive is preferably 0.0001 parts by mass or more, more preferably 0.0005 parts by mass or more, and still more preferably 0.001 parts by mass or more with respect to 100 parts by mass of the polishing slurry for CMP.
  • the content of the second additive is preferably 1 part by mass or less, more preferably 0.5 part by mass or less, still more preferably 0.2 part by mass or less, relative to 100 parts by mass of the polishing slurry for CMP.
  • 1 part by mass or less is particularly preferable, 0.05 part by mass or less is extremely preferable, 0.01 part by mass or less is very preferable, and 0.007 part by mass or less is even more preferable.
  • the content of the second additive is 1 part by mass or less, it tends to suppress the aggregation of abrasive grains compared to the case where the content exceeds 1 part by mass, and tends to achieve both a high polishing rate and high step removal performance. is there.
  • the content of the second additive can be adjusted according to the type of the first additive.
  • the water contained in the CMP polishing liquid according to the present embodiment is not particularly limited, but deionized water, ion-exchanged water, and ultrapure water are preferable. In addition, you may use polar solvents, such as ethanol and acetone, together with water as needed.
  • the CMP polishing liquid according to this embodiment may contain a surfactant from the viewpoint of improving the dispersion stability of the abrasive grains and / or the flatness of the polished surface.
  • a surfactant examples include ionic surfactants and nonionic surfactants, and nonionic surfactants are preferred.
  • the surfactant one kind may be used alone, or two or more kinds may be used in combination.
  • Nonionic surfactants include polyoxypropylene polyoxyethylene alkyl ether, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene polyoxypropylene ether derivatives, polyoxypropylene glyceryl ether, polyethylene glycol oxyethylene Ether type surfactants such as adducts, oxyethylene adducts of methoxypolyethylene glycol, oxyethylene adducts of acetylenic diols; ester type surfactants such as sorbitan fatty acid esters and glycerol borate fatty acid esters; polyoxyethylene alkylamines Amino ether type surfactants such as polyoxyethylene sorbitan fatty acid ester, polyoxyethylene glycerol borate fatty acid ester Ether ester type surfactants such as tellurium and polyoxyethylene alkyl ester; alkanolamide type surfactants such as fatty acid alkanolamide and polyoxyethylene fatty acid
  • the CMP polishing liquid according to the present embodiment may contain other components in addition to the surfactant in accordance with desired characteristics.
  • examples of such components include pH adjusters as described later, pH buffering agents for suppressing fluctuations in pH, aminocarboxylic acids, and cyclic monocarboxylic acids. It is desirable that the content of these components be in a range that does not excessively reduce the effect of the polishing liquid.
  • the pH of the polishing slurry for CMP according to this embodiment is preferably 8.0 or less, more preferably less than 8.0, still more preferably 7.0 or less, particularly preferably 6.0 or less, and extremely preferably 5.0 or less. Preferably, 4.5 or less is very preferable, and 4.0 or less is even more preferable.
  • the polishing slurry for CMP according to this embodiment preferably has a pH of 1.5 or more, more preferably 2.0 or more, still more preferably 2.5 or more, and particularly preferably 3.0 or more.
  • the absolute value of the zeta potential of the inorganic insulating material (for example, silicon oxide) can be increased as compared with the case of less than 1.5, and a higher polishing rate is achieved.
  • the pH is defined as the pH at a liquid temperature of 25 ° C.
  • the pH of the CMP polishing liquid according to the present embodiment can be measured with a pH meter (for example, model number PHL-40 manufactured by Electrochemical Instrument Co., Ltd.).
  • a pH meter for example, model number PHL-40 manufactured by Electrochemical Instrument Co., Ltd.
  • two pH meters are calibrated using phthalate pH buffer solution (pH 4.01) and neutral phosphate pH buffer solution (pH 6.86) as standard buffers, and then the electrodes of the pH meter are polished. Put in the solution and measure the value after 2 minutes or more has stabilized. At this time, both the standard buffer solution and the polishing solution are set to 25 ° C.
  • the pH of the CMP polishing liquid within the range of 1.5 to 8.0.
  • Proton or hydroxy anion acts on the compound blended as an additive to change the chemical form of the compound, and against the inorganic insulating material (for example, silicon oxide) and / or stopper material (for example, silicon nitride) on the substrate surface. Improves wettability and affinity.
  • the abrasive grains contain cerium oxide, the contact efficiency between the abrasive grains and the inorganic insulating material (for example, silicon oxide) is improved, and a higher polishing rate is achieved. This is because the sign of the zeta potential of cerium oxide is positive while the sign of the zeta potential of an inorganic insulating material (for example, silicon oxide) is negative, and electrostatic attraction acts between the two.
  • the pH of the polishing slurry for CMP varies depending on the type of compound used as an additive.
  • the CMP polishing liquid may contain a pH adjusting agent in order to adjust the pH to the above range.
  • the pH adjuster is not particularly limited, and examples thereof include acids such as nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, boric acid and acetic acid; bases such as sodium hydroxide, ammonia, potassium hydroxide and calcium hydroxide. From the viewpoint of improving productivity, a CMP polishing liquid may be prepared without using a pH adjuster, and such a CMP polishing liquid may be applied to CMP as it is.
  • the polishing liquid for CMP can be classified into (A) normal type, (B) concentrated type, and (C) two-liquid type, and the preparation method and usage differ depending on the type.
  • the normal type is a polishing liquid that can be used as it is without pretreatment such as dilution during polishing.
  • the concentrated type is a polishing liquid in which the contents are concentrated in comparison with the (A) normal type in consideration of convenience of storage or transportation.
  • the two-liquid type is divided into a liquid A containing a certain component and a liquid B containing other components at the time of storage or transportation, and the liquid A and the liquid B are mixed and used at the time of use. A polishing liquid.
  • the normal type can be obtained by dissolving or dispersing the abrasive grains, the first additive, the second additive, and, if necessary, other components in water, which is the main dispersion medium. it can.
  • 100 parts by weight of polishing slurry for CMP having 0.5 parts by weight of abrasive grains, 0.1 parts by weight of first additive, and 0.001 parts by weight of second additive.
  • the CMP polishing liquid 1000 g may be adjusted to contain 5 g of abrasive grains, 1 g of the first additive, and 0.01 g of the second additive.
  • the polishing liquid for CMP can be prepared using, for example, a stirrer, a homogenizer, an ultrasonic disperser, a wet ball mill, or the like.
  • the fine graining treatment of the abrasive grains can be carried out by a sedimentation classification method or a method using a high pressure homogenizer.
  • the sedimentation classification method is a method having a step of forcibly sedimenting coarse particles of slurry containing abrasive grains with a centrifuge and a step of taking out only the supernatant.
  • a method using a high-pressure homogenizer is a method in which abrasive grains in a dispersion medium collide with each other at a high pressure.
  • the concentrated type is diluted with water so that the content of the contained components becomes a desired content immediately before use.
  • (A) Liquid characteristics (pH, grain size of abrasive grains, etc.) and polishing characteristics (polishing rate for inorganic insulating material (for example, silicon oxide), inorganic insulation for stopper material (for example, silicon nitride) similar to normal type Stirring or abrasive dispersion may be performed for an arbitrary time until a material (for example, silicon oxide polishing selectivity) can be reproduced.
  • the concentration type the volume is reduced according to the degree of concentration, so that the cost for storage and transportation can be reduced.
  • the concentration ratio is preferably 1.5 times or more, more preferably 2 times or more, further preferably 3 times or more, and particularly preferably 5 times or more. When the concentration ratio is 1.5 times or more, it is possible to obtain merit related to storage and transportation as compared to the case of less than 1.5 times.
  • the concentration factor is preferably 40 times or less, more preferably 20 times or less, and still more preferably 15 times or less. When the concentration ratio is 40 times or less, it is easy to suppress the aggregation of abrasive grains as compared to the case where the concentration ratio exceeds 40 times.
  • (B) The point to be noted when using the concentrated type is that the pH changes before and after dilution with water.
  • the pH of the concentrated type polishing liquid should be set low in advance, taking into account the increase in pH due to mixing with water. That's fine. For example, when water (pH: about 5.6) in which carbon dioxide is dissolved is used and (B) concentrated type polishing liquid having pH 4.0 is diluted 10 times, the pH of the diluted polishing liquid is 4. It rises to about 3.
  • the pH of the concentrated type is preferably 1.5 to 7.0 from the viewpoint of obtaining a polishing liquid having a suitable pH after dilution with water.
  • the lower limit of the pH is preferably 1.5 or more, more preferably 2.0 or more, and further preferably 2.5 or more.
  • the upper limit of the pH is preferably 7.0 or less, more preferably 6.7 or less, still more preferably 6.0 or less, and particularly preferably 5.5 or less from the viewpoint of suppressing the aggregation of abrasive grains.
  • the two-liquid type has an advantage that it can avoid agglomeration of abrasive grains and the like as compared with the (B) concentrated type.
  • the component which each of the liquid A and the liquid B contains is arbitrary.
  • a slurry containing abrasive grains and surfactants blended as necessary is prepared as liquid A, and a solution containing additives and other ingredients blended as needed is liquid B.
  • liquid A a slurry containing abrasive grains and surfactants blended as necessary
  • liquid B a solution containing additives and other ingredients blended as needed.
  • any acid or alkali may be added to the liquid A to adjust the pH.
  • the two-liquid type polishing liquid is useful when the polishing characteristics are deteriorated in a relatively short time due to aggregation of abrasive grains or the like in a state where the respective components are mixed.
  • at least one of the liquid A and the liquid B may be a concentrated type.
  • the liquid A, the liquid B, and water may be mixed when using the polishing liquid.
  • the concentration ratio and pH of the liquid A or the liquid B are arbitrary, and the liquid characteristics and polishing characteristics of the final mixture may be the same as those of the (A) normal type polishing liquid.
  • the polishing method according to the present embodiment includes a polishing step of polishing an inorganic insulating material (for example, silicon oxide) using the CMP polishing liquid according to the present embodiment.
  • an inorganic insulating material for example, silicon oxide
  • the substrate having an inorganic insulating material for example, silicon oxide
  • the polishing step the substrate having an inorganic insulating material (for example, silicon oxide) on the surface is polished and planarized by the CMP technique using the CMP polishing liquid according to the present embodiment.
  • the CMP polishing liquid according to this embodiment includes an inorganic insulating material on a substrate having an inorganic insulating material (for example, silicon oxide) on the surface, and a predetermined polishing member (for example, A step of polishing the inorganic insulating material by the polishing member while being supplied to the polishing pad.
  • the inorganic insulating material is polished to remove at least a part of the inorganic insulating material.
  • the inorganic insulating material to be polished may be in the form of a film (inorganic insulating film such as a silicon oxide film).
  • the content and pH of each component of the CMP polishing liquid are appropriately adjusted.
  • the polishing method according to the present embodiment is suitable for polishing a substrate having an inorganic insulating material (for example, silicon oxide) on the surface in the following device manufacturing process.
  • Devices include diodes, transistors, compound semiconductors, thermistors, varistors, thyristors and other individual semiconductors; DRAM (dynamic random access memory), SRAM (static random access memory), EPROM (erasable programmable read) ⁇ Only memory (memory), mask ROM (mask read only memory), EEPROM (electrically erasable programmable read only memory), storage devices such as flash memory; theoretical circuit such as microprocessor, DSP, ASIC, etc. Element; Integrated circuit element such as compound semiconductor represented by MMIC (monolithic microwave integrated circuit); Hybrid integrated circuit (hybrid IC); Light-emitting diode; Such as photoelectric conversion elements, such as elements and the like.
  • the CMP polishing liquid according to the present embodiment can achieve both a high polishing rate and a high level difference removal property. Therefore, the polishing method using the CMP polishing liquid can be applied to a substrate for which it has been difficult to achieve a high polishing rate by the conventional method using the CMP polishing liquid.
  • the polishing method according to the present embodiment is particularly suitable for flattening a surface to be polished having a step (unevenness) on the surface.
  • An example of a substrate having such a surface to be polished is a logic semiconductor substrate.
  • the surface of the substrate may have a T-shaped or lattice-shaped concave or convex portion, and the polishing method according to the present embodiment is viewed from above (in the direction facing the surface of the substrate). It is suitable for polishing a substrate having on its surface a portion in which concave portions or convex portions are provided in a T shape or a lattice shape.
  • an inorganic insulating material for example, silicon oxide
  • a semiconductor substrate having memory cells for example, a substrate of a device such as a DRAM or flash memory
  • the CMP polishing liquid according to the present embodiment has a high polishing speed and a high step removal property. It shows that they can be compatible.
  • the substrate to which the polishing method according to this embodiment can be applied is not limited to a substrate in which the entire surface of the substrate is formed of a silicon oxide film, but a silicon nitride film, a polycrystalline silicon film, or the like in addition to the silicon oxide film is formed on the substrate surface. Further, it may be a substrate.
  • the polishing method according to the present embodiment includes an inorganic insulating film such as a silicon oxide film, a glass film, and silicon nitride on a wiring board having predetermined wiring; polysilicon, Al, Cu, Ti, TiN, W, Ta It can also be applied to a substrate on which a film mainly containing TaN or the like is formed.
  • Examples of a method for forming a silicon oxide film on the substrate surface include a low pressure CVD method and a plasma CVD method.
  • a low pressure CVD method for example, monosilane (SiH 4 ) is used as the Si source, and oxygen (O 2 ) is used as the oxygen source.
  • SiH 4 monosilane
  • oxygen O 2
  • a silicon oxide film is formed.
  • heat treatment is performed at a temperature of 1000 ° C. or lower after CVD.
  • the plasma CVD method has an advantage that a chemical reaction requiring a high temperature can be performed at a low temperature under normal thermal equilibrium.
  • As the reaction gas for example, SiH 4, SiH 4 -N 2 O -containing gas using N 2 O as oxygen source, and, TEOS-O 2 system using tetraethoxysilane (TEOS) to Si source as Si source Gas (TEOS-plasma CVD method) can be mentioned.
  • the substrate temperature is preferably 250 to 400 ° C.
  • the reaction pressure is preferably 67 to 400 Pa.
  • the silicon oxide film to be polished may be doped with an element such as phosphorus or boron.
  • the silicon nitride film can be formed by a low pressure CVD method, a plasma CVD method, or the like.
  • the low pressure CVD method for example, dichlorosilane (SiH 2 Cl 2 ) is used as the Si source, and ammonia (NH 3 ) is used as the nitrogen source.
  • NH 3 ammonia
  • SiH 2 Cl 2 —NH 3 oxidation reaction at a high temperature of 900 ° C.
  • a silicon nitride film is formed.
  • SiH 4 —NH 3 based gas using SiH 4 as a Si source and NH 3 as a nitrogen source is used as a reactive gas.
  • the substrate temperature is preferably 300 to 400 ° C.
  • the first step (roughing step) of polishing the silicon oxide film 3 at a high polishing rate and high step removal property, and the remaining silicon oxide film 3 have an arbitrary film thickness.
  • a second step (finishing step) for polishing at a high polishing rate is a process for forming an STI structure on a substrate (wafer) by CMP in the polishing method according to the present embodiment.
  • FIG. 1A is a cross-sectional view showing a substrate before polishing.
  • FIG. 1B is a cross-sectional view showing the substrate after the first step.
  • FIG.1 (c) is sectional drawing which shows the board
  • CMP CMP
  • a substrate (wafer) is disposed on the polishing pad so that the surface of the silicon oxide film 3 and the polishing pad come into contact with each other, and the surface of the silicon oxide film 3 is polished by the polishing pad. . More specifically, the surface to be polished of the silicon oxide film 3 is pressed against the polishing pad of the polishing surface plate, and the two are relative to each other in a state where the polishing liquid for CMP is supplied between the surface to be polished and the polishing pad. The silicon oxide film 3 is polished by moving to.
  • the CMP polishing liquid according to the present embodiment can be applied to both the first step and the second step, but can be used in the first step because it can achieve both a high polishing rate and a high level difference removal property. It is particularly preferred. Although the case where the polishing process is performed in two stages is illustrated here, the polishing process can be performed in one stage from the state shown in FIG. 1A to the state shown in FIG.
  • polishing apparatus for example, an apparatus including a holder for holding a substrate, a polishing surface plate to which the polishing pad is attached, and means for supplying a polishing liquid onto the polishing pad is suitable.
  • the polishing apparatus include polishing apparatuses manufactured by Ebara Manufacturing Co., Ltd. (model numbers: EPO-111, EPO-222, FREX200, and FREX300), APPLIED MATERIALS polishing apparatuses (trade name: Mirara 3400, Reflexion polishing machine), and the like.
  • a polishing pad For example, a general nonwoven fabric, a polyurethane foam, a porous fluororesin, etc. can be used. Further, the polishing pad is preferably subjected to groove processing so that the polishing liquid is accumulated.
  • the polishing conditions are not particularly limited, but from the viewpoint of suppressing the substrate from popping out, the rotation speed of the polishing platen is preferably 200 min ⁇ 1 or less, and the pressure (working load) applied to the substrate causes scratches on the polishing surface. From the viewpoint of suppression, 100 kPa or less is preferable.
  • the substrate is thoroughly washed in running water, and further, water droplets adhering to the substrate are removed by a spin dryer or the like and then dried.
  • polishing in this way, surface irregularities can be eliminated and a smooth surface can be obtained over the entire surface of the substrate.
  • a substrate having a desired number of layers can be manufactured by repeating the formation of the film and the step of polishing the film a predetermined number of times.
  • the substrate thus obtained can be used as various electronic parts and mechanical parts.
  • semiconductor elements include: semiconductor elements; optical glasses such as photomasks, lenses, and prisms; inorganic conductive films such as ITO; optical integrated circuits / optical switching elements / optical waveguides composed of glass and crystalline materials; Examples include optical single crystals such as scintillators; solid laser single crystals; sapphire substrates for blue laser LEDs; semiconductor single crystals such as SiC, GaP and GaAs; glass substrates for magnetic disks; magnetic heads and the like.
  • the average particle size of the abrasive grains was measured using a dynamic light scattering particle size distribution meter (trade name: LB-500, manufactured by Horiba, Ltd.). As a result, the average particle size was 150 nm.
  • the liquid phase after the above centrifugation was diluted with deionized water to adjust the abrasive content to 5.0% by mass. Further, immediately before polishing, each compound shown in Table 1 or Table 2 is added to the liquid phase in which the content of abrasive grains is adjusted to 5.0% by mass so as to have the content described in each table. The pH was adjusted to 3.4 using organic acid or ammonia. Thereafter, stirring was performed for 10 minutes to obtain a polishing slurry for CMP. The content of abrasive grains in the CMP polishing liquid was as shown in the table.
  • the pH of the CMP polishing liquid was determined under the following conditions. Measurement temperature: 25 ⁇ 5 ° C Measuring instrument: manufactured by Electrochemical Instrument Co., Ltd. Model number: PHL-40
  • the CMP polishing liquids according to Examples 1 to 7 obtained in this way were diluted with pure water so that the abrasive content was 0.5% by mass based on the total mass of the sample.
  • a sample for diameter measurement was obtained.
  • the average particle size of the abrasive grains was measured by a dynamic light scattering type particle size distribution analyzer (trade name: LB-500, manufactured by Horiba, Ltd.), and all were 150 ⁇ 5 nm.
  • the polishing slurry for CMP according to Examples 1 to 7 is a polishing solution prepared using the first additive and the second additive.
  • the CMP polishing liquid according to Comparative Examples 1 to 3 is a polishing liquid prepared without using the second additive.
  • the CMP polishing liquid according to Comparative Example 4 is a polishing liquid prepared without using the first additive and the second additive.
  • the CMP polishing liquid according to Comparative Example 5 and Comparative Example 6 is a polishing liquid prepared without using the first additive.
  • “A” is 5-hydroxy-2-hydroxymethyl-4-pyrone (also known as kojic acid)
  • “B” is 3-hydroxy-2 -Methyl-4-pyrone (also known as maltol).
  • a blanket wafer having a silicon oxide film on the surface as a film to be polished was prepared.
  • a blanket wafer is a wafer having a silicon oxide film having a thickness of 1000 nm disposed on a silicon substrate having a diameter of 300 mm.
  • a pattern wafer (trade name: SEMATECH764, manufactured by ADVANTECH) having an uneven silicon oxide film as a film to be polished was prepared.
  • a silicon nitride film (film thickness: 1500 nm) is formed as a stopper film on a part of a silicon substrate having a diameter of 300 mm, and then a recess is formed by etching the silicon substrate without the silicon nitride film by 350 nm.
  • the blanket wafer and the pattern wafer were polished using a polishing apparatus (manufactured by APPLIED MATERIALS, trade name: Reflexion LK).
  • the wafer was set in a holder having a suction pad for attaching the wafer.
  • a polishing pad made of porous urethane resin k-groove groove, manufactured by Rodel, model number: IC-1010 was attached to a polishing surface plate having a diameter of 800 mm.
  • the holder was placed on the polishing pad with the silicon oxide film forming surface of the wafer facing down.
  • the wafer pressing pressure was set to 28 kPa.
  • each of the CMP polishing liquids prepared by the above method was dropped onto the polishing pad attached to the polishing platen at a flow rate of 250 mL / min, and the polishing platen and the wafer were rotated at a rotational speed of 93 min ⁇ 1 and 87 min, respectively.
  • the silicon oxide film was polished by rotating at -1 . Thereafter, the polished wafer was thoroughly washed with pure water using a PVA brush (polyvinyl alcohol brush) and then dried.
  • the time X required for polishing the silicon oxide film by 300 nm was calculated as the time for polishing the pattern wafer for each polishing liquid for CMP.
  • the pattern wafer was polished for the time X by using each polishing liquid for CMP.
  • the amount of film thickness change before and after polishing of the silicon oxide film on the convex part of the pattern wafer was measured using an optical interference type film thickness measuring device (trade name: RE-3000, manufactured by Dainippon Screen Mfg. Co., Ltd.).
  • the film thickness change amount at this time was determined as a pattern wafer polishing amount (PTW).
  • divided the pattern wafer polishing amount by 300 nm was computed as level
  • Examples 1 to 7 using the first additive and the second additive had higher step removal performance than Comparative Examples 1 to 6. Further, in Examples 1 to 7, it was shown that the silicon oxide film can be polished while achieving both a high polishing rate and a high level difference removing property.
  • the average particle diameter of the abrasive grains was measured after one day from the preparation of the polishing liquid by mixing the respective components of the polishing liquid.
  • the particle size was 150 nm, which was the same as the particle size at the time of preparing abrasive grains. Thereby, it was confirmed that aggregation of a particle size is suppressed.
  • a polishing slurry for CMP that can achieve both a high polishing rate and a step removal property for a silicon oxide film.
  • the present invention also provides a polishing method using the CMP polishing liquid.

Abstract

A polishing liquid for CMP according to the present invention contains abrasive grains, a first additive, a second additive and water. The first additive is a 4-pyrone compound represented by general formula (1), and the second additive is a compound having an acidic functional group and a basic functional group. (In the formula, each of X11, X12 and X13 independently represents a hydrogen atom or a monovalent substituent.)

Description

ＣＭＰ用研磨液及びこれを用いた研磨方法Polishing liquid for CMP and polishing method using the same
　本発明は、ケミカルメカニカルポリッシング（ＣＭＰ）に使用するためのＣＭＰ用研磨液、及び、これを用いた研磨方法に関する。本発明は、例えば、半導体ウェハ材料を研磨するためのＣＭＰ用研磨液、及び、これを用いた研磨方法に関する。本発明は、特に、半導体ウェハの表面に設けられた酸化ケイ素を研磨するためのＣＭＰ用研磨液、及び、これを用いた研磨方法に関する。 The present invention relates to a CMP polishing liquid for use in chemical mechanical polishing (CMP), and a polishing method using the same. The present invention relates to, for example, a CMP polishing liquid for polishing a semiconductor wafer material, and a polishing method using the same. The present invention particularly relates to a polishing slurry for CMP for polishing silicon oxide provided on the surface of a semiconductor wafer, and a polishing method using the same.
　半導体製造の分野では、超ＬＳＩデバイスの高性能化に伴い、従来技術の延長線上の微細化技術では高集積化及び高速化を両立することは限界になってきている。そこで、半導体素子の微細化を進めつつ、垂直方向にも高集積化する技術、すなわち配線を多層化する技術が開発されている。 In the field of semiconductor manufacturing, along with the improvement in performance of VLSI devices, it is becoming the limit to achieve both high integration and high speed with the miniaturization technology on the extension line of the prior art. In view of this, a technique for increasing the integration in the vertical direction while miniaturizing semiconductor elements, that is, a technique for multilayering wiring has been developed.
　配線が多層化されたデバイスを製造するプロセスにおいて、最も重要な技術の一つにＣＭＰ技術がある。ＣＭＰ技術は、化学気相蒸着（ＣＶＤ）等によって基板上に薄膜を形成した後、その表面を平坦化する技術である。例えば、リソグラフィの焦点深度を確保するためには、ＣＭＰによる処理が不可欠である。基板表面に凹凸があると、露光工程における焦点合わせが不可能となったり、微細な配線構造を充分に形成できなかったり等の不都合が生じる。ＣＭＰ技術は、デバイスの製造過程において、プラズマ酸化物材料（ＢＰＳＧ、ＨＤＰ－ＳｉＯ２、ｐ－ＴＥＯＳ等）の研磨によって素子分離領域を形成する工程、層間絶縁材料を形成する工程、又は、酸化ケイ素を含む部材（例えば酸化ケイ素膜）を金属配線に埋め込んだ後にプラグ（例えばＡｌ・Ｃｕプラグ）を平坦化する工程などにも適用される。 One of the most important techniques in the process of manufacturing a device with multi-layered wiring is the CMP technique. The CMP technique is a technique for flattening the surface after forming a thin film on a substrate by chemical vapor deposition (CVD) or the like. For example, in order to ensure the depth of focus of lithography, processing by CMP is indispensable. If the surface of the substrate is uneven, inconveniences such as inability to focus in the exposure process and insufficient formation of a fine wiring structure occur. The CMP technology is a process for forming an element isolation region by polishing a plasma oxide material (BPSG, HDP-SiO 2 , p-TEOS, etc.), a process for forming an interlayer insulating material, or a silicon oxide in a device manufacturing process. The present invention is also applied to a step of flattening a plug (for example, an Al / Cu plug) after embedding a member (for example, a silicon oxide film) containing metal in a metal wiring.
　ＣＭＰは、通常、研磨パッド上に研磨液を供給できる装置を用いて行われる。基板表面と研磨パッドとの間に研磨液を供給しながら、基板を研磨パッドに押し付けることによって、基板表面が研磨される。ＣＭＰ技術においては、高性能の研磨液が要素技術の一つであり、これまでにも種々の研磨液が開発されている。 CMP is usually performed using an apparatus capable of supplying a polishing liquid onto a polishing pad. The substrate surface is polished by pressing the substrate against the polishing pad while supplying a polishing liquid between the substrate surface and the polishing pad. In the CMP technique, a high-performance polishing liquid is one of elemental techniques, and various polishing liquids have been developed so far.
　ところで、基板上に素子分離領域を形成する工程においては、予め基板表面に溝を設け、この溝を埋めるように無機絶縁材料（例えば酸化ケイ素）がＣＶＤ等によって形成される。その後、無機絶縁材料の表面をＣＭＰによって平坦化することによって素子分離領域が形成される。表面に溝等の素子分離構造が設けられた基板上に無機絶縁材料を形成する場合、無機絶縁材料の表面にも素子分離構造の凹凸に応じた凹凸が生じる。凹凸を有する表面の研磨では、凸部が優先的に除去される一方、凹部がゆっくりと除去されることによって表面の平坦化がなされる。 Incidentally, in the step of forming the element isolation region on the substrate, a groove is provided in advance on the substrate surface, and an inorganic insulating material (for example, silicon oxide) is formed by CVD or the like so as to fill the groove. Then, the element isolation region is formed by planarizing the surface of the inorganic insulating material by CMP. When an inorganic insulating material is formed on a substrate provided with an element isolation structure such as a groove on the surface, irregularities corresponding to the irregularities of the element isolation structure also occur on the surface of the inorganic insulating material. In polishing a surface having irregularities, the convex portions are preferentially removed, while the concave portions are removed slowly to flatten the surface.
　半導体生産のプロセスマージン及び歩留りを向上するためには、基板上に形成した無機絶縁材料の不要な部分をウェハ面内で可能な限り均一に且つ高速に除去することが好ましい。例えば、素子分離領域の狭幅化に対応すべく、シャロー・トレンチ分離（ＳＴＩ）を採用した場合、基板上に設けられた無機絶縁材料の段差及び不要な部分を高い研磨速度で取り除くことが要求される。 In order to improve the process margin and yield of semiconductor production, it is preferable to remove unnecessary portions of the inorganic insulating material formed on the substrate as uniformly and as fast as possible on the wafer surface. For example, when shallow trench isolation (STI) is adopted to cope with the narrowing of the element isolation region, it is required to remove the step and unnecessary portion of the inorganic insulating material provided on the substrate at a high polishing rate. Is done.
　一般に、無機絶縁材料の研磨処理を二段階に分け、生産効率の向上を図る場合がある。第一の工程（荒削り工程）では、基板上に設けられた無機絶縁材料を高速に除去する。第二の工程（仕上げ工程）では、無機絶縁材料を任意の厚みとなるように仕上げる。 Generally, there are cases where the polishing process of the inorganic insulating material is divided into two stages to improve the production efficiency. In the first step (rough cutting step), the inorganic insulating material provided on the substrate is removed at high speed. In the second step (finishing step), the inorganic insulating material is finished to an arbitrary thickness.
　無機絶縁材料（例えば酸化ケイ素）を除去するためのＣＭＰ用研磨液は種々知られている。例えば、第一の工程（荒削り工程）に用い得る研磨液として、特定の化学構造を有する化合物を含有する研磨液が知られている（例えば、下記特許文献１参照）。 Various polishing liquids for CMP for removing inorganic insulating materials (for example, silicon oxide) are known. For example, a polishing liquid containing a compound having a specific chemical structure is known as a polishing liquid that can be used in the first step (roughing step) (for example, see Patent Document 1 below).
国際公開第２０１０／０６７８４４号International Publication No. 2010/067844
　近年、第一の工程においては、無機絶縁材料に対する高い研磨速度だけではなく、高い段差除去性が要求されてきている。特に、無機絶縁材料に対するＣＭＰを二段階以上に分ける場合、第一の工程では研磨速度よりも段差除去性が優先されるようになってきている。なお、段差除去性は、表面に無機絶縁材料を有するブランケットウェハにおける前記無機絶縁材料の研磨量（研磨速度）に対する、凸部表面に無機絶縁材料を有するパターンウェハにおける前記無機絶縁材料（凸部表面）の研磨量（研磨速度）の比率（パターンウェハにおける研磨量／ブランケットウェハにおける研磨量）で評価することができる。当該比率が高い場合には、パターンウェハにおける凸部表面の無機絶縁材料の除去率が高く、段差を優先的に除去することができる。 In recent years, in the first step, not only a high polishing rate for an inorganic insulating material but also a high step removal property has been required. In particular, when CMP for an inorganic insulating material is divided into two or more steps, the step removal property is given priority over the polishing rate in the first step. The step removability indicates that the inorganic insulating material (convex portion surface) in the pattern wafer having the inorganic insulating material on the convex surface with respect to the polishing amount (polishing rate) of the inorganic insulating material in the blanket wafer having the inorganic insulating material on the surface. ) Polishing amount (polishing speed) ratio (polishing amount in pattern wafer / polishing amount in blanket wafer). When the ratio is high, the removal rate of the inorganic insulating material on the convex surface of the pattern wafer is high, and the step can be removed preferentially.
　しかし、単に無機絶縁材料に対する研磨速度が高いＣＭＰ用研磨液を用いると、段差除去性が低いことがある。段差除去性の低下は、第二の工程における無機絶縁材料の除去時間を増大させスループットの悪化を招くことに加え、研磨後の平坦性を低下させる。研磨後の平坦性が低下すると、リソグラフィの焦点深度を確保できずデバイスの形成が難しくなる。 However, when a polishing slurry for CMP, which has a high polishing rate for inorganic insulating materials, is used, the step-removability may be low. The decrease in the step removal property increases the removal time of the inorganic insulating material in the second step and causes a deterioration in throughput, and also decreases the flatness after polishing. If the flatness after polishing is lowered, the depth of focus of lithography cannot be ensured, and it becomes difficult to form a device.
　本発明は、前記課題を解決しようとするものであり、無機絶縁材料に対する高い研磨速度及び段差除去性を両立できるＣＭＰ用研磨液、及び、これを用いた研磨方法を提供することを目的とする。 The present invention is intended to solve the above-described problems, and an object of the present invention is to provide a polishing slurry for CMP that can achieve both a high polishing rate and step removal performance for an inorganic insulating material, and a polishing method using the same. .
　本発明者らは、前記課題を解決すべく、ＣＭＰ用研磨液に配合する添加剤について鋭意検討を重ねた。本発明者らは、種々の有機化合物を添加剤として使用してＣＭＰ用研磨液を多数調製した。これらのＣＭＰ用研磨液を用いて無機絶縁材料を研磨し、研磨速度及び段差除去性の評価を行った。その結果、特定の化学構造を有する４－ピロン系化合物と、酸性官能基及び塩基性官能基を有する化合物とを添加剤として使用することが、無機絶縁材料に対する高い研磨速度及び段差除去性を両立することに有効であることを見出し、本発明を完成させた。 In order to solve the above-mentioned problems, the present inventors have made extensive studies on additives to be added to the CMP polishing liquid. The present inventors prepared many polishing liquids for CMP using various organic compounds as additives. These CMP polishing liquids were used to polish the inorganic insulating material, and the polishing rate and the step removal performance were evaluated. As a result, the use of 4-pyrone compounds having a specific chemical structure and compounds having acidic functional groups and basic functional groups as additives makes it possible to achieve both high polishing speed and step removal performance for inorganic insulating materials. As a result, the present invention has been completed.
　本発明に係るＣＭＰ用研磨液は、砥粒と、第一の添加剤と、第二の添加剤と、水と、を含有し、前記第一の添加剤が、下記一般式（１）で表される４－ピロン系化合物であり、前記第二の添加剤が、酸性官能基及び塩基性官能基を有する化合物である。
Figure JPOXMLDOC01-appb-C000002
 ［式中、Ｘ１１、Ｘ１２及びＸ１３は、それぞれ独立に、水素原子又は１価の置換基である。］ The CMP polishing liquid according to the present invention contains abrasive grains, a first additive, a second additive, and water, and the first additive is represented by the following general formula (1). And the second additive is a compound having an acidic functional group and a basic functional group.
Figure JPOXMLDOC01-appb-C000002
 [Wherein, X 11 , X 12 and X 13 are each independently a hydrogen atom or a monovalent substituent. ]
　本発明に係るＣＭＰ用研磨液によれば、無機絶縁材料に対する高い研磨速度及び段差除去性を両立できる。これらの効果が奏される要因は必ずしも明らかではないが、特定の化学構造を有する４－ピロン系化合物を第一の添加剤として使用することで、ＣＭＰ用研磨液と無機絶縁材料との相互作用が大きくなり、その結果、研磨速度が高くなると推測される。また、酸性官能基及び塩基性官能基を有する化合物を第二の添加剤として使用（第一の添加剤と併用）することで、第二の添加剤の前記官能基が無機絶縁材料と反応することにより、強い荷重依存性が生じると推測される。これにより、荷重が強くかかる段差凸部の除去性が高くなり、その結果、段差除去性が高くなると推測される。 The CMP polishing liquid according to the present invention can achieve both a high polishing rate and a step removal property for an inorganic insulating material. Although the cause of these effects is not necessarily clear, the interaction between the polishing liquid for CMP and the inorganic insulating material can be achieved by using a 4-pyrone compound having a specific chemical structure as the first additive. As a result, it is estimated that the polishing rate is increased. Further, by using a compound having an acidic functional group and a basic functional group as the second additive (in combination with the first additive), the functional group of the second additive reacts with the inorganic insulating material. Thus, it is estimated that strong load dependency occurs. Thereby, it is presumed that the step removability with a heavy load increases, and as a result, the step removability increases.
　前記の通り、本発明に係るＣＭＰ用研磨液は、高い研磨速度及び高い段差除去性を両立できるという特長を有するため、凹凸を有する無機絶縁材料の研磨に適している。また、本発明に係るＣＭＰ用研磨液は、従来のＣＭＰ用研磨液では段差除去が比較的困難な半導体材料を研磨する場合であっても高い研磨速度及び高い段差除去性を両立できるという利点がある。例えば、メモリセルを有する半導体基板のように、Ｔ字形状又は格子形状の凹部又は凸部を有する表面の無機絶縁材料を研磨する場合であっても高い研磨速度及び高い段差除去性を両立できる。 As described above, the CMP polishing liquid according to the present invention has a feature that it is possible to achieve both a high polishing rate and a high level difference removal property, and is therefore suitable for polishing an inorganic insulating material having irregularities. In addition, the CMP polishing liquid according to the present invention has an advantage that both a high polishing rate and a high level of step removal can be achieved even when polishing a semiconductor material that is relatively difficult to remove steps with the conventional CMP polishing liquid. is there. For example, even when polishing an inorganic insulating material having a T-shaped or lattice-shaped concave or convex portion like a semiconductor substrate having a memory cell, both a high polishing rate and a high level difference can be achieved.
　前記第一の添加剤を含有するＣＭＰ用研磨液によれば、無機絶縁材料に対する高い研磨速度を達成できることに加えて、砥粒の凝集を抑制することができる。かかる効果が奏される要因は必ずしも明らかではないが、上述した特定構造を有する４－ピロン系化合物が、ＣＭＰ用研磨液と無機絶縁材料との相互作用を大きくし得る添加剤であるにもかかわらず、砥粒同士の静電的反発力等の反発力を弱める効果がないため、砥粒の凝集を抑制することができると推測される。 According to the polishing slurry for CMP containing the first additive, in addition to achieving a high polishing rate for the inorganic insulating material, aggregation of abrasive grains can be suppressed. Although the cause of such an effect is not necessarily clear, although the 4-pyrone compound having the specific structure described above is an additive that can increase the interaction between the polishing slurry for CMP and the inorganic insulating material. Therefore, since there is no effect of weakening the repulsive force such as electrostatic repulsive force between the abrasive grains, it is presumed that the aggregation of the abrasive grains can be suppressed.
　第一の添加剤は、３－ヒドロキシ－２－メチル－４－ピロン、５－ヒドロキシ－２－（ヒドロキシメチル）－４－ピロン、及び、２－エチル－３－ヒドロキシ－４－ピロンからなる群より選ばれる少なくとも一種であることが好ましい。これにより、更に高い研磨速度が得られる。 The first additive is a group consisting of 3-hydroxy-2-methyl-4-pyrone, 5-hydroxy-2- (hydroxymethyl) -4-pyrone, and 2-ethyl-3-hydroxy-4-pyrone It is preferably at least one selected from the group. Thereby, a higher polishing rate can be obtained.
　第二の添加剤の酸性官能基は、スルホン酸基であることが好ましい。また、第二の添加剤の塩基性官能基は、アミノ基であることが好ましい。これらの場合、高い段差除去性が容易に得られる。同様の観点から、第二の添加剤は、スルファミン酸及びアミノベンゼンスルホン酸からなる群より選ばれる少なくとも一種であることがより好ましい。 The acidic functional group of the second additive is preferably a sulfonic acid group. The basic functional group of the second additive is preferably an amino group. In these cases, high step-removability can be easily obtained. From the same viewpoint, the second additive is more preferably at least one selected from the group consisting of sulfamic acid and aminobenzenesulfonic acid.
　第一の添加剤の含有量は、当該ＣＭＰ用研磨液１００質量部に対して０．００１～５質量部であることが好ましい。これにより、研磨速度の向上効果が更に効率的に得られる。 The content of the first additive is preferably 0.001 to 5 parts by mass with respect to 100 parts by mass of the CMP polishing liquid. Thereby, the improvement effect of the polishing rate can be obtained more efficiently.
　第二の添加剤の含有量は、当該ＣＭＰ用研磨液１００質量部に対して０．０００１～１質量部であることが好ましい。これにより、凹凸を有する基板（例えば半導体基板）の段差凸部に対する除去性の向上効果が更に効率的に得られる。 The content of the second additive is preferably 0.0001 to 1 part by mass with respect to 100 parts by mass of the CMP polishing liquid. Thereby, the improvement effect of the removability with respect to the level | step difference convex part of the board | substrate (for example, semiconductor substrate) which has an unevenness | corrugation is obtained more efficiently.
　砥粒は、セリウム系化合物を含むことが好ましい。セリウム系化合物は、酸化セリウムであることが好ましい。 The abrasive preferably contains a cerium compound. The cerium-based compound is preferably cerium oxide.
　本発明に係るＣＭＰ用研磨液は、無機絶縁材料を研磨するために用いられてもよい。すなわち、本発明は、前記ＣＭＰ用研磨液の、表面に無機絶縁材料を有する基板の研磨への応用を提供する。 The CMP polishing liquid according to the present invention may be used for polishing an inorganic insulating material. That is, the present invention provides an application of the CMP polishing liquid to polishing a substrate having an inorganic insulating material on the surface.
　本発明は、前記ＣＭＰ用研磨液を用いた研磨方法を提供する。すなわち、本発明に係る研磨方法は、表面に無機絶縁材料を有する基板を研磨する研磨方法であって、本発明に係るＣＭＰ用研磨液が無機絶縁材料と研磨パッドとの間に供給された状態で研磨パッドによって無機絶縁材料を研磨する工程を備える。このような研磨方法によれば、無機絶縁材料に対する高い研磨速度及び段差除去性を両立できる。また、研磨対象の基板の表面形状に大きく依存することなく高い研磨速度が達成されるため、前記研磨方法は、無機絶縁材料の荒削り、及び、メモリセルを有する半導体基板の研磨に適している。 The present invention provides a polishing method using the CMP polishing liquid. That is, the polishing method according to the present invention is a polishing method for polishing a substrate having an inorganic insulating material on the surface, and the CMP polishing liquid according to the present invention is supplied between the inorganic insulating material and the polishing pad. And a step of polishing the inorganic insulating material with a polishing pad. According to such a polishing method, it is possible to achieve both a high polishing rate and a step removal property for the inorganic insulating material. In addition, since a high polishing rate is achieved without largely depending on the surface shape of the substrate to be polished, the polishing method is suitable for roughing an inorganic insulating material and polishing a semiconductor substrate having memory cells.
　本発明によれば、無機絶縁材料（例えば酸化ケイ素）に対する高い研磨速度及び段差除去性を両立できる。特に、本発明によれば、凹凸を有する無機絶縁材料に対する高い研磨速度及び段差除去性を両立できる。本発明によれば、ＣＭＰ用研磨液の、半導体ウェハ材料の研磨への応用を提供できる。本発明によれば、ＣＭＰ用研磨液の、無機絶縁材料の研磨への応用を提供できる。本発明によれば、ＣＭＰ用研磨液の、酸化ケイ素の研磨への応用を提供できる。本発明によれば、ＣＭＰ用研磨液の、表面に無機絶縁材料を有する基板の研磨への応用を提供できる。本発明によれば、ＣＭＰ用研磨液の、半導体ウェハの表面に設けられた酸化ケイ素の研磨への応用を提供できる。本発明によれば、ＣＭＰ用研磨液の、凹凸を有する無機絶縁材料の研磨への応用を提供できる。本発明によれば、ＣＭＰ用研磨液の、メモリセルを有する半導体基板の研磨への応用を提供できる。本発明によれば、ＣＭＰ用研磨液の、Ｔ字形状又は格子形状の凹部又は凸部を有する表面の無機絶縁材料の研磨への応用を提供できる。 According to the present invention, it is possible to achieve both a high polishing rate and a step removal property for an inorganic insulating material (for example, silicon oxide). In particular, according to the present invention, it is possible to achieve both a high polishing rate and a step removal property for an inorganic insulating material having irregularities. ADVANTAGE OF THE INVENTION According to this invention, the application to the grinding | polishing of the semiconductor wafer material of the polishing liquid for CMP can be provided. ADVANTAGE OF THE INVENTION According to this invention, the application to the grinding | polishing of an inorganic insulating material of the polishing liquid for CMP can be provided. ADVANTAGE OF THE INVENTION According to this invention, the application to the grinding | polishing of a silicon oxide of the polishing liquid for CMP can be provided. ADVANTAGE OF THE INVENTION According to this invention, the application to the grinding | polishing of the board | substrate which has an inorganic insulating material on the surface of CMP polishing liquid can be provided. ADVANTAGE OF THE INVENTION According to this invention, the application to the grinding | polishing of the silicon oxide provided in the surface of the semiconductor wafer of the polishing liquid for CMP can be provided. ADVANTAGE OF THE INVENTION According to this invention, the application to the grinding | polishing of the inorganic insulating material which has an unevenness | corrugation of CMP polishing liquid can be provided. ADVANTAGE OF THE INVENTION According to this invention, the application to polishing of the semiconductor substrate which has a memory cell of CMP polishing liquid can be provided. ADVANTAGE OF THE INVENTION According to this invention, the application to the grinding | polishing of the inorganic insulating material of the surface which has the recessed part or convex part of T shape or a grid | lattice shape of the polishing liquid for CMP can be provided.
酸化ケイ素膜が研磨されて半導体基板にシャロー・トレンチ分離構造が形成される過程を示す模式断面図である。It is a schematic cross-sectional view showing a process in which a silicon oxide film is polished to form a shallow trench isolation structure in a semiconductor substrate.
　以下、本発明の実施形態について詳細に説明する。なお、本明細書において、「～」を用いて示された数値範囲は、「～」の前後に記載される数値をそれぞれ最小値及び最大値として含む範囲を示す。また、組成物中の各成分の含有量は、組成物中に各成分に該当する物質が複数存在する場合、特に断らない限り、組成物中に存在する当該複数の物質の合計量を意味する。 Hereinafter, embodiments of the present invention will be described in detail. In the present specification, numerical ranges indicated by using “to” indicate ranges including numerical values described before and after “to” as the minimum value and the maximum value, respectively. Further, the content of each component in the composition means the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition. .
＜ＣＭＰ用研磨液＞
　本実施形態に係るＣＭＰ用研磨液は、砥粒（研磨粒子）と、第一の添加剤と、第二の添加剤と、水と、を含有し、第一の添加剤が、４－ピロン系化合物であり、第二の添加剤が、酸性官能基及び塩基性官能基を有する化合物であることを特徴とする。以下、ＣＭＰ用研磨液の調製に使用する各成分等について説明する。 <CMP polishing liquid>
The polishing slurry for CMP according to this embodiment contains abrasive grains (polishing particles), a first additive, a second additive, and water, and the first additive is 4-pyrone. And a second additive is a compound having an acidic functional group and a basic functional group. Hereinafter, each component used for the preparation of the polishing liquid for CMP will be described.
（砥粒）
　砥粒は、例えば、セリウム系化合物、アルミナ、シリカ、チタニア、ジルコニア、マグネシア、ムライト、窒化ケイ素、α－サイアロン、窒化アルミニウム、窒化チタン、炭化ケイ素、炭化ホウ素等を含むことができる。これらの砥粒の構成成分としては、一種を単独で用いてもよく、二種以上を併用してもよい。これらの中でも、第一の添加剤及び第二の添加剤の添加効果を良好に発揮でき、凹凸を有する無機絶縁材料（例えば酸化ケイ素）に対する高い研磨速度及び段差除去性が更に高度に両立される観点から、セリウム系化合物が好ましい。 (Abrasive grains)
The abrasive grains can include, for example, a cerium compound, alumina, silica, titania, zirconia, magnesia, mullite, silicon nitride, α-sialon, aluminum nitride, titanium nitride, silicon carbide, boron carbide, and the like. As a constituent component of these abrasive grains, one kind may be used alone, or two or more kinds may be used in combination. Among these, the addition effect of the first additive and the second additive can be satisfactorily exhibited, and the high polishing rate and the step removal property for the inorganic insulating material having unevenness (for example, silicon oxide) are more highly compatible. From the viewpoint, a cerium-based compound is preferable.
　セリウム系化合物を含む砥粒を用いたＣＭＰ用研磨液は、研磨面（研磨後の表面を言う。以下同じ）に生じる研磨傷が比較的少ないという特長を有する。従来、無機絶縁材料（例えば酸化ケイ素）に対する高い研磨速度を達成しやすい観点から、砥粒としてシリカ粒子を含むＣＭＰ用研磨液が広く用いられている。しかし、シリカ粒子を用いたＣＭＰ用研磨液は、一般に研磨面に研磨傷が生じやすいという課題がある。配線幅が４５ｎｍ世代以降の微細パターンを有するデバイスにおいては、従来問題にならなかったような微細な傷であっても、デバイスの信頼性に影響するおそれがある。 A polishing liquid for CMP using abrasive grains containing a cerium-based compound has a feature that there are relatively few polishing flaws on a polished surface (referred to as a surface after polishing; hereinafter the same). Conventionally, from the viewpoint of easily achieving a high polishing rate for an inorganic insulating material (for example, silicon oxide), CMP polishing liquids containing silica particles as abrasive grains have been widely used. However, CMP polishing liquids using silica particles generally have a problem that polishing scratches are likely to occur on the polished surface. In a device having a fine pattern with a wiring width of 45 nm or later, even a fine scratch that has not been a problem may affect the reliability of the device.
　なお、セリウム系化合物を含む砥粒を使用した従来のＣＭＰ用研磨液は、シリカ粒子を使用したＣＭＰ用研磨液と比較し、無機絶縁材料（例えば酸化ケイ素）に対する研磨速度がやや低い傾向があった。しかし、本実施形態においては、セリウム系化合物を含む砥粒と、第一の添加剤と、第二の添加剤とを併用することで、無機絶縁材料（例えば酸化ケイ素）に対する高い研磨速度及び段差除去性が両立される。このことは、セリウム系化合物と、第一の添加剤と、第二の添加剤との組み合わせが、特に研磨に有効であることを示唆している。 Note that a conventional CMP polishing liquid using abrasive grains containing a cerium compound tends to have a slightly lower polishing rate for inorganic insulating materials (eg, silicon oxide) than a CMP polishing liquid using silica particles. It was. However, in the present embodiment, a high polishing rate and a step difference with respect to an inorganic insulating material (for example, silicon oxide) can be obtained by using an abrasive containing a cerium compound, the first additive, and the second additive in combination. Removability is compatible. This suggests that the combination of the cerium compound, the first additive, and the second additive is particularly effective for polishing.
　セリウム系化合物としては、酸化セリウム、セリウム水酸化物、硝酸アンモニウムセリウム、酢酸セリウム、硫酸セリウム水和物、臭素酸セリウム、臭化セリウム、塩化セリウム、シュウ酸セリウム、硝酸セリウム、炭酸セリウム等が挙げられる。これらの中でも、酸化セリウムが好ましい。酸化セリウムを使用することで、高い研磨速度及び高い段差除去性を両立しつつ、研磨傷が少ない優れた研磨面が得られる。 Examples of the cerium compound include cerium oxide, cerium hydroxide, ammonium cerium nitrate, cerium acetate, cerium sulfate hydrate, cerium bromate, cerium bromide, cerium chloride, cerium oxalate, cerium nitrate, and cerium carbonate. . Among these, cerium oxide is preferable. By using cerium oxide, an excellent polished surface with few polishing flaws can be obtained while achieving both a high polishing rate and a high level difference removability.
　酸化セリウムを使用する場合、砥粒は、結晶粒界を有する多結晶酸化セリウム（例えば、結晶粒界に囲まれた複数の結晶子を有する多結晶酸化セリウム）を含むことが好ましい。かかる構成の多結晶酸化セリウム粒子は、単結晶粒子が凝集した単なる凝集体とは異なっており、研磨中の応力により細かくなると同時に、活性面（細かくなる前は外部にさらされていない面）が次々と現れるため、無機絶縁材料（例えば酸化ケイ素）に対する高い研磨速度を高度に維持できると考えられる。このような多結晶酸化セリウム粒子については、例えば、国際公開公報ＷＯ９９／３１１９５号に詳しく説明されている。 In the case of using cerium oxide, the abrasive grains preferably include polycrystalline cerium oxide having a crystal grain boundary (for example, polycrystalline cerium oxide having a plurality of crystallites surrounded by the crystal grain boundary). The polycrystalline cerium oxide particles having such a structure are different from simple aggregates in which single crystal particles are aggregated, and become fine due to stress during polishing, and at the same time, have an active surface (a surface not exposed to the outside before becoming fine). Since it appears one after another, it is considered that a high polishing rate for an inorganic insulating material (for example, silicon oxide) can be maintained at a high level. Such polycrystalline cerium oxide particles are described in detail in, for example, International Publication No. WO99 / 31195.
　酸化セリウムを含む砥粒の製造方法としては、特に制限はないが、液相合成；焼成又は過酸化水素等により酸化する方法などが挙げられる。前記結晶粒界を有する多結晶酸化セリウムを含む砥粒を得る場合には、炭酸セリウム等のセリウム源を焼成する方法が好ましい。前記焼成時の温度は、３５０～９００℃が好ましい。製造された酸化セリウム粒子が凝集している場合は、機械的に粉砕することが好ましい。粉砕方法としては、特に制限はないが、例えば、ジェットミル等による乾式粉砕；遊星ビーズミル等による湿式粉砕が好ましい。ジェットミルは、例えば、「化学工学論文集」、第６巻、第５号、（１９８０）、５２７～５３２頁に説明されている。 The method for producing abrasive grains containing cerium oxide is not particularly limited, and examples include a liquid phase synthesis; a method of oxidizing by baking or hydrogen peroxide. When obtaining abrasive grains containing polycrystalline cerium oxide having crystal grain boundaries, a method of firing a cerium source such as cerium carbonate is preferred. The firing temperature is preferably 350 to 900 ° C. When the produced cerium oxide particles are aggregated, it is preferably mechanically pulverized. The pulverization method is not particularly limited, but for example, dry pulverization using a jet mill or the like; wet pulverization using a planetary bead mill or the like is preferable. The jet mill is described in, for example, “Chemical Engineering Papers”, Vol. 6, No. (1980), pp. 527-532.
　砥粒の平均粒径は、５０ｎｍ以上が好ましく、７０ｎｍ以上がより好ましく、８０ｎｍ以上が更に好ましい。平均粒径が５０ｎｍ以上であると、５０ｎｍ未満の場合と比較して無機絶縁材料（例えば酸化ケイ素）に対する研磨速度を高くできる。砥粒の平均粒径は、５００ｎｍ以下が好ましく、３００ｎｍ以下がより好ましく、２８０ｎｍ以下が更に好ましく、２５０ｎｍ以下が特に好ましく、２００ｎｍ以下が極めて好ましい。平均粒径が５００ｎｍ以下であると、５００ｎｍを超える場合と比較して研磨傷を抑制できる。砥粒の平均粒径を制御するためには、従来公知の方法を使用することができる。平均粒径の制御方法としては、前記酸化セリウム粒子を例にすると、前記焼成温度、焼成時間、粉砕条件等の制御；濾過、分級等の適用などが挙げられる。 The average particle size of the abrasive grains is preferably 50 nm or more, more preferably 70 nm or more, and still more preferably 80 nm or more. When the average particle size is 50 nm or more, the polishing rate for the inorganic insulating material (for example, silicon oxide) can be increased as compared with the case of less than 50 nm. The average particle size of the abrasive grains is preferably 500 nm or less, more preferably 300 nm or less, still more preferably 280 nm or less, particularly preferably 250 nm or less, and extremely preferably 200 nm or less. When the average particle size is 500 nm or less, polishing scratches can be suppressed as compared with the case where the average particle size exceeds 500 nm. In order to control the average particle diameter of the abrasive grains, a conventionally known method can be used. As a method for controlling the average particle diameter, taking the cerium oxide particles as an example, control of the firing temperature, firing time, pulverization conditions, etc .; application of filtration, classification, etc. may be mentioned.
　「砥粒の平均粒径」とは、砥粒が分散したスラリサンプルを動的光散乱式粒度分布計で測定した体積分布の中央値を意味する。具体的には、株式会社堀場製作所製のＬＢ－５００（商品名）等を用いて測定される値である。砥粒の含有量がスラリサンプルの全質量基準で０．５質量％になるようにスラリサンプルの砥粒の含有量を調整し、これをＬＢ－５００にセットして体積分布の中央値の測定を行う。ＬＢ－５００によってメジアン径（累積中央値）を測定することによって、砥粒の凝集の程度を評価することもできる。ＣＭＰ用研磨液中の砥粒の平均粒径を測定する場合は、前記ＣＭＰ用研磨液を濃縮又は水で希釈することによって砥粒の含有量がスラリサンプルの全質量基準で０．５質量％になるようにスラリサンプルの砥粒の含有量を調整してから、同様の方法で測定することができる。 “The average particle diameter of the abrasive grains” means the median value of the volume distribution obtained by measuring the slurry sample in which the abrasive grains are dispersed with a dynamic light scattering particle size distribution meter. Specifically, it is a value measured using LB-500 (trade name) manufactured by HORIBA, Ltd. Adjust the content of abrasive grains in the slurry sample so that the abrasive grain content is 0.5% by mass based on the total mass of the slurry sample, and set this in the LB-500 to measure the median volume distribution I do. The degree of agglomeration of abrasive grains can also be evaluated by measuring the median diameter (cumulative median value) with LB-500. When measuring the average particle size of the abrasive grains in the CMP polishing liquid, the content of the abrasive grains is 0.5 mass% based on the total mass of the slurry sample by concentrating or diluting the CMP polishing liquid with water. After adjusting the content of the abrasive grains of the slurry sample so as to become, it can be measured by the same method.
　砥粒の含有量（粒子含有量）は、ＣＭＰ用研磨液１００質量部に対して、０．１０質量部以上が好ましく、０．１５質量部以上がより好ましく、０．２０質量部以上が更に好ましい。砥粒の含有量が０．１０質量部以上であると、０．１０質量部未満の場合と比較して高い研磨速度が達成される傾向がある。砥粒の含有量は、ＣＭＰ用研磨液１００質量部に対して、１０質量部以下が好ましく、５．０質量部以下がより好ましく、３．０質量部以下が更に好ましく、２．０質量部以下が特に好ましく、１．０質量部以下が極めて好ましい。砥粒の含有量が１０質量部以下であると、１０質量部を超える場合と比較して砥粒の凝集を抑制しやすく、高い研磨速度を達成しやすい傾向がある。 The content of the abrasive grains (particle content) is preferably 0.10 parts by mass or more, more preferably 0.15 parts by mass or more, and further 0.20 parts by mass or more with respect to 100 parts by mass of the polishing slurry for CMP. preferable. When the content of the abrasive grains is 0.10 parts by mass or more, a high polishing rate tends to be achieved as compared with the case of less than 0.10 parts by mass. The content of the abrasive is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, still more preferably 3.0 parts by mass or less, and 2.0 parts by mass with respect to 100 parts by mass of the polishing slurry for CMP. The following is particularly preferable, and 1.0 mass part or less is extremely preferable. When the content of the abrasive grains is 10 parts by mass or less, the aggregation of the abrasive grains tends to be suppressed as compared with the case where the content exceeds 10 parts by mass, and a high polishing rate tends to be achieved.
（第一の添加剤）
　第一の添加剤は、下記一般式（１）で表される４－ピロン系化合物である。本実施形態に係るＣＭＰ用研磨液によれば、一般式（１）で表される４－ピロン系化合物を第一の添加剤として使用することにより、従来のＣＭＰ用研磨液と比較して、無機絶縁材料に対する高い研磨速度を達成できる。
Figure JPOXMLDOC01-appb-C000003
 (First additive)
The first additive is a 4-pyrone compound represented by the following general formula (1). According to the polishing slurry for CMP according to the present embodiment, by using the 4-pyrone compound represented by the general formula (1) as the first additive, compared to the conventional polishing slurry for CMP, A high polishing rate for inorganic insulating materials can be achieved.
Figure JPOXMLDOC01-appb-C000003
　式（１）中、Ｘ１１、Ｘ１２及びＸ１３は、それぞれ独立に、水素原子又は１価の置換基である。１価の置換基としては、アルデヒド基、ヒドロキシ基（水酸基）、カルボキシル基、スルホン酸基、リン酸基、臭素原子、塩素原子、ヨウ素原子、フッ素原子、ニトロ基、ヒドラジン基、炭素数１～８のアルキル基（ＯＨ、ＣＯＯＨ、Ｂｒ、Ｃｌ、Ｉ又はＮＯ２で置換されていてもよい）、炭素数６～１２のアリール基、炭素数１～８のアルケニル基等が挙げられる。１価の置換基としては、メチル基、エチル基、ヒドロキシメチル基が好ましい。 In formula (1), X 11 , X 12 and X 13 are each independently a hydrogen atom or a monovalent substituent. Examples of the monovalent substituent include an aldehyde group, a hydroxy group (hydroxyl group), a carboxyl group, a sulfonic acid group, a phosphoric acid group, a bromine atom, a chlorine atom, an iodine atom, a fluorine atom, a nitro group, a hydrazine group, and a carbon number of 1 to 8 alkyl groups (which may be substituted with OH, COOH, Br, Cl, I, or NO 2 ), aryl groups having 6 to 12 carbon atoms, alkenyl groups having 1 to 8 carbon atoms, and the like. As the monovalent substituent, a methyl group, an ethyl group, or a hydroxymethyl group is preferable.
　前記４－ピロン系化合物がＸ１１、Ｘ１２及びＸ１３として１価の置換基を有する場合、１価の置換基は、合成が簡易である観点から、オキシ基に隣接する炭素原子に結合していることが好ましい。すなわち、Ｘ１１及びＸ１２の少なくとも一方が１価の置換基であることが好ましい。さらに、砥粒の研磨能力の向上効果が得られやすい観点から、Ｘ１１、Ｘ１２及びＸ１３のうち少なくとも２つは水素原子であることが好ましく、Ｘ１１、Ｘ１２及びＸ１３のうち２つが水素原子であることがより好ましい。 When the 4-pyrone compound has a monovalent substituent as X 11 , X 12 and X 13 , the monovalent substituent is bonded to a carbon atom adjacent to the oxy group from the viewpoint of easy synthesis. It is preferable. That is, it is preferable that at least one of X 11 and X 12 is a monovalent substituent. Furthermore, easy in view of improvement is obtained of the abrasive grains of the polishing ability, it is preferable that at least two are hydrogen atom of X 11, X 12 and X 13, among the X 11, X 12 and X 13 2 More preferably, one is a hydrogen atom.
　前記４－ピロン系化合物は、少なくともカルボニル基の炭素原子に隣接している炭素原子にヒドロキシ基が結合した構造を有する。ここで、「４－ピロン系化合物」とは、オキシ基及びカルボニル基が含まれるとともに、オキシ基に対してカルボニル基が４位に位置している６員環（γ－ピロン環）構造を有する複素環式化合物である。本実施形態の４－ピロン系化合物は、このγ－ピロン環におけるカルボニル基に隣接している炭素原子にヒドロキシ基が結合しており、それ以外の炭素原子には、水素原子以外の置換基が置換していてもよい。 The 4-pyrone compound has a structure in which a hydroxy group is bonded to at least a carbon atom adjacent to the carbon atom of the carbonyl group. Here, the “4-pyrone compound” has a 6-membered ring (γ-pyrone ring) structure in which an oxy group and a carbonyl group are included and the carbonyl group is located at the 4-position with respect to the oxy group. It is a heterocyclic compound. In the 4-pyrone compound of this embodiment, a hydroxy group is bonded to a carbon atom adjacent to the carbonyl group in the γ-pyrone ring, and a substituent other than a hydrogen atom is attached to the other carbon atom. May be substituted.
　このような４－ピロン系化合物としては、更に高い研磨速度を得る観点から、３－ヒドロキシ－２－メチル－４－ピロン（別名：３－ヒドロキシ－２－メチル－４Ｈ－ピラン－４－オン、マルトール）、５－ヒドロキシ－２－（ヒドロキシメチル）－４－ピロン（別名：５－ヒドロキシ－２－（ヒドロキシメチル）－４Ｈ－ピラン－４－オン、コウジ酸）、及び、２－エチル－３－ヒドロキシ－４－ピロン（別名：２－エチル－３－ヒドロキシ－４Ｈ－ピラン－４－オン）からなる群より選ばれる少なくとも一種の化合物が好ましい。 As such a 4-pyrone compound, from the viewpoint of obtaining a higher polishing rate, 3-hydroxy-2-methyl-4-pyrone (also known as 3-hydroxy-2-methyl-4H-pyran-4-one, Maltol), 5-hydroxy-2- (hydroxymethyl) -4-pyrone (also known as 5-hydroxy-2- (hydroxymethyl) -4H-pyran-4-one, kojic acid), and 2-ethyl-3 At least one compound selected from the group consisting of -hydroxy-4-pyrone (alias: 2-ethyl-3-hydroxy-4H-pyran-4-one) is preferred.
　第一の添加剤としては、一種を単独で用いてもよく、二種以上を併用してもよい。第一の添加剤を二種以上組み合わせて使用することによっても高い研磨速度が得られる。 As the first additive, one kind may be used alone, or two or more kinds may be used in combination. A high polishing rate can also be obtained by using a combination of two or more of the first additives.
　第一の添加剤は、水溶性であることが好ましい。水への溶解度が高い化合物を使用することにより、所望の量の第一の添加剤を良好にＣＭＰ用研磨液中に溶解させることができ、研磨速度の向上効果、及び、砥粒の凝集の抑制効果をより一層高水準に達成し得る。室温（２５℃）の水１００ｇに対する第一の添加剤の溶解度は、０．００１ｇ以上が好ましく、０．００５ｇ以上がより好ましく、０．０１ｇ以上が更に好ましく、０．０５ｇ以上が特に好ましい。なお、溶解度の上限は特に制限はない。 The first additive is preferably water-soluble. By using a compound having a high solubility in water, a desired amount of the first additive can be dissolved well in the polishing slurry for CMP, and an effect of improving the polishing rate and agglomeration of abrasive grains can be achieved. The suppression effect can be achieved to a higher level. The solubility of the first additive in 100 g of water at room temperature (25 ° C.) is preferably 0.001 g or more, more preferably 0.005 g or more, still more preferably 0.01 g or more, and particularly preferably 0.05 g or more. The upper limit of solubility is not particularly limited.
　第一の添加剤の含有量は、ＣＭＰ用研磨液１００質量部に対して、０．００１質量部以上が好ましく、０．００５質量部以上がより好ましく、０．０１質量部以上が更に好ましく、０．０２質量部以上が特に好ましく、０．０３質量部以上が極めて好ましい。第一の添加剤の含有量が０．００１質量部以上であると、０．００１質量部未満の場合と比較して安定した研磨速度を達成しやすい傾向がある。第一の添加剤の含有量は、ＣＭＰ用研磨液１００質量部に対して、５質量部以下が好ましく、３質量部以下がより好ましく、１質量部以下が更に好ましく、０．５質量部以下が特に好ましく、０．３質量部以下が極めて好ましい。第一の添加剤の含有量が５質量部以下であると、５質量部を超える場合と比較して砥粒の凝集を抑制しやすく、高い研磨速度を達成しやすい傾向がある。 The content of the first additive is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, still more preferably 0.01 parts by mass or more, with respect to 100 parts by mass of the polishing slurry for CMP. 0.02 parts by mass or more is particularly preferable, and 0.03 parts by mass or more is very preferable. When the content of the first additive is 0.001 part by mass or more, there is a tendency that a stable polishing rate is easily achieved as compared to the case of less than 0.001 part by mass. The content of the first additive is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, still more preferably 1 part by mass or less, and 0.5 parts by mass or less with respect to 100 parts by mass of the polishing slurry for CMP. Is particularly preferable, and 0.3 parts by mass or less is extremely preferable. When the content of the first additive is 5 parts by mass or less, aggregation of abrasive grains tends to be suppressed as compared with the case where the content exceeds 5 parts by mass, and a high polishing rate tends to be easily achieved.
（第二の添加剤）
　本実施形態に係るＣＭＰ用研磨液は、第二の添加剤として、酸性官能基及び塩基性官能基を有する化合物（第一の添加剤に該当する化合物を除く）を含有している。これにより、高い研磨速度に加え、高い段差除去性を得ることができる。 (Second additive)
The CMP polishing liquid according to the present embodiment contains a compound having an acidic functional group and a basic functional group (excluding a compound corresponding to the first additive) as the second additive. Thereby, in addition to a high polishing rate, high step removal performance can be obtained.
　酸性官能基とは、水溶液中で酸性を示す官能基である。酸性官能基としては、スルホン酸基、スルホン酸塩基、カルボキシル基、カルボン酸塩基、リン酸基、リン酸塩基等が挙げられ、スルホン酸基が好ましい。塩基性官能基とは、水溶液中で塩基性を示す官能基である。塩基性官能基としては、アミノ基等が挙げられる。 An acidic functional group is a functional group that exhibits acidity in an aqueous solution. Examples of the acidic functional group include a sulfonic acid group, a sulfonic acid group, a carboxyl group, a carboxylic acid group, a phosphoric acid group, and a phosphoric acid group, and a sulfonic acid group is preferable. The basic functional group is a functional group that exhibits basicity in an aqueous solution. Examples of basic functional groups include amino groups.
　室温（２５℃）における第二の添加剤の酸解離定数ｐＫａ（平衡定数Ｋａの負の常用対数（逆数の対数）、ｐＫａが２つ以上ある場合は、一番低い第一段階のｐＫａ１）は、４未満が好ましく、３．５以下がより好ましく、３．３以下が更に好ましい。これにより、ＣＭＰ用研磨液中で第二の添加剤の少なくとも一部がイオン化して水素イオンが放出され、第二の添加剤と被研磨材料とが容易に反応する。前記酸解離定数ｐＫａの下限は特に制限はなく、例えば－１０以上である。 The acid dissociation constant pKa of the second additive at room temperature (25 ° C.) (the negative common logarithm of the equilibrium constant Ka (logarithm of the reciprocal), and when there are two or more pKa, the lowest first step pKa1) is Less than 4 is preferable, 3.5 or less is more preferable, and 3.3 or less is more preferable. Thereby, at least a part of the second additive is ionized in the CMP polishing liquid to release hydrogen ions, and the second additive and the material to be polished easily react. The lower limit of the acid dissociation constant pKa is not particularly limited and is, for example, −10 or more.
　第二の添加剤としては、アミノ基含有スルホン酸化合物が好ましい。「アミノ基含有スルホン酸化合物」とは、スルホン酸基（スルホ基、－ＳＯ３Ｈ）及びスルホン酸塩基（－ＳＯ３Ｍ：Ｍは金属原子）からなる群より選ばれる少なくとも一種と、アミノ基（－ＮＨ２）とを１分子内に有する化合物である。スルホン酸塩基の金属原子Ｍとしては、Ｎａ、Ｋ等のアルカリ金属、Ｍｇ、Ｃａ等のアルカリ土類金属などが挙げられる。 As the second additive, an amino group-containing sulfonic acid compound is preferable. The “amino group-containing sulfonic acid compound” means at least one selected from the group consisting of a sulfonic acid group (sulfo group, —SO 3 H) and a sulfonic acid group (—SO 3 M: M is a metal atom), an amino group (—NH 2 ) in one molecule. Examples of the metal atom M of the sulfonate group include alkali metals such as Na and K, and alkaline earth metals such as Mg and Ca.
　アミノ基含有スルホン酸化合物としては、スルファミン酸（別名：アミド硫酸）、アミノメタンスルホン酸、アミノエタンスルホン酸（１－アミノエタンスルホン酸、２－アミノエタンスルホン酸等）、アミノプロパンスルホン酸、アミノベンゼンスルホン酸（オルタニル酸（別名：２－アミノベンゼンスルホン酸）、メタニル酸（別名：３－アミノベンゼンスルホン酸）、スルファニル酸（別名：４－アミノベンゼンスルホン酸）等）、アミノナフタレンスルホン酸、これらの塩（例えば、前記金属原子Ｍを含む塩）などが挙げられる。第二の添加剤としては、高い段差除去性が容易に得られる観点から、スルファミン酸及びアミノベンゼンスルホン酸からなる群より選ばれる少なくとも一種が好ましく、スルファミン酸及びスルファニル酸からなる群より選ばれる少なくとも一種がより好ましい。 Examples of amino group-containing sulfonic acid compounds include sulfamic acid (also known as amidosulfuric acid), aminomethanesulfonic acid, aminoethanesulfonic acid (1-aminoethanesulfonic acid, 2-aminoethanesulfonic acid, etc.), aminopropanesulfonic acid, amino Benzenesulfonic acid (ortanylic acid (also known as 2-aminobenzenesulfonic acid), methanylic acid (also known as 3-aminobenzenesulfonic acid), sulfanilic acid (also known as 4-aminobenzenesulfonic acid), aminonaphthalenesulfonic acid, These salts (for example, salts containing the metal atom M) and the like can be mentioned. The second additive is preferably at least one selected from the group consisting of sulfamic acid and aminobenzene sulfonic acid from the viewpoint of easily obtaining high step removal, and at least selected from the group consisting of sulfamic acid and sulfanilic acid. One type is more preferable.
　第二の添加剤としては、一種を単独で用いてもよく、二種以上を併用してもよい。 As the second additive, one kind may be used alone, or two or more kinds may be used in combination.
　第二の添加剤の分子量は、第二の添加剤の前記官能基が無機絶縁材料と容易に反応する観点から、５００以下が好ましく、３００以下がより好ましく、２５０以下が更に好ましく、２００以下が特に好ましい。分子量の下限は、例えば５０以上である。 The molecular weight of the second additive is preferably 500 or less, more preferably 300 or less, still more preferably 250 or less, and even more preferably 200 or less, from the viewpoint that the functional group of the second additive easily reacts with the inorganic insulating material. Particularly preferred. The lower limit of the molecular weight is, for example, 50 or more.
　第二の添加剤の含有量は、ＣＭＰ用研磨液１００質量部に対して、０．０００１質量部以上が好ましく、０．０００５質量部以上がより好ましく、０．００１質量部以上が更に好ましい。第二の添加剤の含有量が０．０００１質量部以上であると、高い研磨速度及び高い段差除去性を安定して両立しやすい傾向がある。第二の添加剤の含有量は、ＣＭＰ用研磨液１００質量部に対して、１質量部以下が好ましく、０．５質量部以下がより好ましく、０．２質量部以下が更に好ましく、０．１質量部以下が特に好ましく、０．０５質量部以下が極めて好ましく、０．０１質量部以下が非常に好ましく、０．００７質量部以下がより一層好ましい。第二の添加剤の含有量が１質量部以下であると、１質量部を超える場合と比較して砥粒の凝集を抑制しやすく、高い研磨速度及び高い段差除去性を両立しやすい傾向がある。第二の添加剤の含有量は、第一の添加剤の種類に応じて調整することができる。 The content of the second additive is preferably 0.0001 parts by mass or more, more preferably 0.0005 parts by mass or more, and still more preferably 0.001 parts by mass or more with respect to 100 parts by mass of the polishing slurry for CMP. When the content of the second additive is 0.0001 parts by mass or more, there is a tendency that a high polishing rate and a high level difference removability are easily and stably achieved. The content of the second additive is preferably 1 part by mass or less, more preferably 0.5 part by mass or less, still more preferably 0.2 part by mass or less, relative to 100 parts by mass of the polishing slurry for CMP. 1 part by mass or less is particularly preferable, 0.05 part by mass or less is extremely preferable, 0.01 part by mass or less is very preferable, and 0.007 part by mass or less is even more preferable. When the content of the second additive is 1 part by mass or less, it tends to suppress the aggregation of abrasive grains compared to the case where the content exceeds 1 part by mass, and tends to achieve both a high polishing rate and high step removal performance. is there. The content of the second additive can be adjusted according to the type of the first additive.
（水）
　本実施形態に係るＣＭＰ用研磨液が含有する水は、特に制限されるものではないが、脱イオン水、イオン交換水及び超純水が好ましい。なお、必要に応じて、エタノール、アセトン等の極性溶媒などを水と併用してもよい。 (water)
The water contained in the CMP polishing liquid according to the present embodiment is not particularly limited, but deionized water, ion-exchanged water, and ultrapure water are preferable. In addition, you may use polar solvents, such as ethanol and acetone, together with water as needed.
（他の成分）
　本実施形態に係るＣＭＰ用研磨液は、砥粒の分散安定性及び／又は研磨面の平坦性を向上させる観点から、界面活性剤を含有することができる。界面活性剤としては、イオン性界面活性剤、非イオン性界面活性剤等が挙げられ、非イオン性界面活性剤が好ましい。界面活性剤としては、一種を単独で用いてもよく、二種以上を併用してもよい。 (Other ingredients)
The CMP polishing liquid according to this embodiment may contain a surfactant from the viewpoint of improving the dispersion stability of the abrasive grains and / or the flatness of the polished surface. Examples of the surfactant include ionic surfactants and nonionic surfactants, and nonionic surfactants are preferred. As the surfactant, one kind may be used alone, or two or more kinds may be used in combination.
　非イオン性界面活性剤として、ポリオキシプロピレンポリオキシエチレンアルキルエーテル、ポリオキシエチレンアルキルエーテル、ポリオキシエチレンアルキルアリルエーテル、ポリオキシエチレンポリオキシプロピレンエーテル誘導体、ポリオキシプロピレングリセリルエーテル、ポリエチレングリコールのオキシエチレン付加体、メトキシポリエチレングリコールのオキシエチレン付加体、アセチレン系ジオールのオキシエチレン付加体等のエーテル型界面活性剤；ソルビタン脂肪酸エステル、グリセロールボレイト脂肪酸エステル等のエステル型界面活性剤；ポリオキシエチレンアルキルアミン等のアミノエーテル型界面活性剤；ポリオキシエチレンソルビタン脂肪酸エステル、ポリオキシエチレングリセロールボレイト脂肪酸エステル、ポリオキシエチレンアルキルエステル等のエーテルエステル型界面活性剤；脂肪酸アルカノールアミド、ポリオキシエチレン脂肪酸アルカノールアミド等のアルカノールアミド型界面活性剤；ポリビニルピロリドン；ポリアクリルアミド；ポリジメチルアクリルアミド；ポリビニルアルコールなどが挙げられる。非イオン性界面活性剤としては、一種を単独で用いてもよく、二種以上を併用してもよい。 Nonionic surfactants include polyoxypropylene polyoxyethylene alkyl ether, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene polyoxypropylene ether derivatives, polyoxypropylene glyceryl ether, polyethylene glycol oxyethylene Ether type surfactants such as adducts, oxyethylene adducts of methoxypolyethylene glycol, oxyethylene adducts of acetylenic diols; ester type surfactants such as sorbitan fatty acid esters and glycerol borate fatty acid esters; polyoxyethylene alkylamines Amino ether type surfactants such as polyoxyethylene sorbitan fatty acid ester, polyoxyethylene glycerol borate fatty acid ester Ether ester type surfactants such as tellurium and polyoxyethylene alkyl ester; alkanolamide type surfactants such as fatty acid alkanolamide and polyoxyethylene fatty acid alkanolamide; polyvinylpyrrolidone; polyacrylamide; polydimethylacrylamide; It is done. As a nonionic surfactant, 1 type may be used independently and 2 or more types may be used together.
　本実施形態に係るＣＭＰ用研磨液は、界面活性剤以外に、所望とする特性に合わせてその他の成分を含有していてもよい。このような成分としては、後述するようなｐＨ調整剤、ｐＨの変動を抑えるためのｐＨ緩衝剤、アミノカルボン酸、環状モノカルボン酸等が挙げられる。これらの成分の含有量は、研磨液の前記効果を過度に低下させない範囲とすることが望ましい。 The CMP polishing liquid according to the present embodiment may contain other components in addition to the surfactant in accordance with desired characteristics. Examples of such components include pH adjusters as described later, pH buffering agents for suppressing fluctuations in pH, aminocarboxylic acids, and cyclic monocarboxylic acids. It is desirable that the content of these components be in a range that does not excessively reduce the effect of the polishing liquid.
（ｐＨ）
　本実施形態に係るＣＭＰ用研磨液のｐＨは、８．０以下が好ましく、８．０未満がより好ましく、７．０以下が更に好ましく、６．０以下が特に好ましく、５．０以下が極めて好ましく、４．５以下が非常に好ましく、４．０以下がより一層好ましい。ｐＨが８．０以下であると、８．０を超える場合と比較して砥粒の凝集等を抑制しやすく、第一の添加剤及び第二の添加剤の添加効果が得られやすい。本実施形態に係るＣＭＰ用研磨液のｐＨは、１．５以上が好ましく、２．０以上がより好ましく、２．５以上が更に好ましく、３．０以上が特に好ましい。ｐＨが１．５以上であると、１．５未満の場合と比較して無機絶縁材料（例えば酸化ケイ素）のゼータ電位の絶対値を大きな値とすることができ、更に高い研磨速度が達成される。なお、ｐＨは、液温２５℃におけるｐＨと定義する。 (PH)
The pH of the polishing slurry for CMP according to this embodiment is preferably 8.0 or less, more preferably less than 8.0, still more preferably 7.0 or less, particularly preferably 6.0 or less, and extremely preferably 5.0 or less. Preferably, 4.5 or less is very preferable, and 4.0 or less is even more preferable. When the pH is 8.0 or less, it is easy to suppress agglomeration of abrasive grains and the like compared to the case where the pH exceeds 8.0, and the effect of adding the first additive and the second additive is easily obtained. The polishing slurry for CMP according to this embodiment preferably has a pH of 1.5 or more, more preferably 2.0 or more, still more preferably 2.5 or more, and particularly preferably 3.0 or more. When the pH is 1.5 or more, the absolute value of the zeta potential of the inorganic insulating material (for example, silicon oxide) can be increased as compared with the case of less than 1.5, and a higher polishing rate is achieved. The The pH is defined as the pH at a liquid temperature of 25 ° C.
　本実施形態に係るＣＭＰ用研磨液のｐＨは、ｐＨメータ（例えば、電気化学計器株式会社製の型番ＰＨＬ－４０）で測定することができる。例えば、フタル酸塩ｐＨ緩衝液（ｐＨ４．０１）と中性リン酸塩ｐＨ緩衝液（ｐＨ６．８６）とを標準緩衝液として用いてｐＨメータを２点校正した後、ｐＨメータの電極を研磨液に入れて、２分以上経過して安定した後の値を測定する。このとき、標準緩衝液と研磨液の液温は共に２５℃とする。 The pH of the CMP polishing liquid according to the present embodiment can be measured with a pH meter (for example, model number PHL-40 manufactured by Electrochemical Instrument Co., Ltd.). For example, two pH meters are calibrated using phthalate pH buffer solution (pH 4.01) and neutral phosphate pH buffer solution (pH 6.86) as standard buffers, and then the electrodes of the pH meter are polished. Put in the solution and measure the value after 2 minutes or more has stabilized. At this time, both the standard buffer solution and the polishing solution are set to 25 ° C.
　また、ＣＭＰ用研磨液のｐＨを１．５～８．０の範囲内に調整することで、次の２つの効果が得られると考えられる。
　（１）添加剤として配合した化合物にプロトン又はヒドロキシアニオンが作用して、当該化合物の化学形態が変化し、基板表面の無機絶縁材料（例えば酸化ケイ素）及び／又はストッパ材料（例えば窒化ケイ素）に対する濡れ性及び親和性が向上する。
　（２）砥粒が酸化セリウムを含む場合、砥粒と無機絶縁材料（例えば酸化ケイ素）との接触効率が向上し、更に高い研磨速度が達成される。これは、酸化セリウムのゼータ電位の符号が正であるのに対し、無機絶縁材料（例えば酸化ケイ素）のゼータ電位の符号が負であり、両者の間に静電的引力が働くためである。 Further, it is considered that the following two effects can be obtained by adjusting the pH of the CMP polishing liquid within the range of 1.5 to 8.0.
(1) Proton or hydroxy anion acts on the compound blended as an additive to change the chemical form of the compound, and against the inorganic insulating material (for example, silicon oxide) and / or stopper material (for example, silicon nitride) on the substrate surface. Improves wettability and affinity.
(2) When the abrasive grains contain cerium oxide, the contact efficiency between the abrasive grains and the inorganic insulating material (for example, silicon oxide) is improved, and a higher polishing rate is achieved. This is because the sign of the zeta potential of cerium oxide is positive while the sign of the zeta potential of an inorganic insulating material (for example, silicon oxide) is negative, and electrostatic attraction acts between the two.
　ＣＭＰ用研磨液のｐＨは、添加剤として使用する化合物の種類によって変化する。ＣＭＰ用研磨液は、ｐＨを前記の範囲に調整するためにｐＨ調整剤を含有していてもよい。ｐＨ調整剤としては、特に制限はないが、硝酸、硫酸、塩酸、リン酸、ホウ酸、酢酸等の酸；水酸化ナトリウム、アンモニア、水酸化カリウム、水酸化カルシウム等の塩基などが挙げられる。なお、生産性が向上する観点から、ｐＨ調整剤を使用することなくＣＭＰ用研磨液を調製し、このようなＣＭＰ用研磨液をＣＭＰにそのまま適用してもよい。 The pH of the polishing slurry for CMP varies depending on the type of compound used as an additive. The CMP polishing liquid may contain a pH adjusting agent in order to adjust the pH to the above range. The pH adjuster is not particularly limited, and examples thereof include acids such as nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, boric acid and acetic acid; bases such as sodium hydroxide, ammonia, potassium hydroxide and calcium hydroxide. From the viewpoint of improving productivity, a CMP polishing liquid may be prepared without using a pH adjuster, and such a CMP polishing liquid may be applied to CMP as it is.
＜ＣＭＰ用研磨液の調製法及び使用法＞
　ＣＭＰ用研磨液は、（Ａ）通常タイプ、（Ｂ）濃縮タイプ及び（Ｃ）２液タイプに分類でき、タイプによって調製法及び使用法が相違する。（Ａ）通常タイプは、研磨時に希釈等の前処理をせずにそのまま使用できる研磨液である。（Ｂ）濃縮タイプは、保管又は輸送の利便性を考慮し、（Ａ）通常タイプと比較して含有成分を濃縮した研磨液である。（Ｃ）２液タイプは、保管又は輸送に際して、一定の成分を含む液Ａと、他の成分を含む液Ｂとに分けた状態としておき、使用時に液Ａ及び液Ｂを混合して使用する研磨液である。 <Preparation method and usage of polishing liquid for CMP>
The polishing liquid for CMP can be classified into (A) normal type, (B) concentrated type, and (C) two-liquid type, and the preparation method and usage differ depending on the type. (A) The normal type is a polishing liquid that can be used as it is without pretreatment such as dilution during polishing. (B) The concentrated type is a polishing liquid in which the contents are concentrated in comparison with the (A) normal type in consideration of convenience of storage or transportation. (C) The two-liquid type is divided into a liquid A containing a certain component and a liquid B containing other components at the time of storage or transportation, and the liquid A and the liquid B are mixed and used at the time of use. A polishing liquid.
　（Ａ）通常タイプは、砥粒、第一の添加剤、第二の添加剤、及び、必要に応じてその他の成分を、主な分散媒である水に溶解又は分散させることによって得ることができる。例えば、砥粒の含有量０．５質量部、第一の添加剤の含有量０．１質量部、第二の添加剤の含有量０．００１質量部を有するＣＭＰ用研磨液１００質量部を１０００ｇ調製するには、ＣＭＰ用研磨液１０００ｇが砥粒５ｇ、第一の添加剤１ｇ、第二の添加剤０．０１ｇを含有するように調整すればよい。 (A) The normal type can be obtained by dissolving or dispersing the abrasive grains, the first additive, the second additive, and, if necessary, other components in water, which is the main dispersion medium. it can. For example, 100 parts by weight of polishing slurry for CMP having 0.5 parts by weight of abrasive grains, 0.1 parts by weight of first additive, and 0.001 parts by weight of second additive. To prepare 1000 g, the CMP polishing liquid 1000 g may be adjusted to contain 5 g of abrasive grains, 1 g of the first additive, and 0.01 g of the second additive.
　ＣＭＰ用研磨液は、例えば、攪拌機、ホモジナイザ、超音波分散機、湿式ボールミル等を使用して調製することができる。なお、砥粒の平均粒径が所望の範囲となるように、ＣＭＰ用研磨液の調製過程において砥粒の微粒子化処理を行ってもよい。砥粒の微粒子化処理は、沈降分級法又は高圧ホモジナイザを用いた方法によって実施できる。沈降分級法は、砥粒を含むスラリの粗大粒子を遠心分離機で強制的に沈降させる工程と、上澄み液のみを取り出す工程とを有する方法である。高圧ホモジナイザを用いた方法は、分散媒中の砥粒同士を高圧で衝突させる方法である。 The polishing liquid for CMP can be prepared using, for example, a stirrer, a homogenizer, an ultrasonic disperser, a wet ball mill, or the like. In addition, you may perform the micronization process of an abrasive grain in the preparation process of polishing liquid for CMP so that the average particle diameter of an abrasive grain may become a desired range. The fine graining treatment of the abrasive grains can be carried out by a sedimentation classification method or a method using a high pressure homogenizer. The sedimentation classification method is a method having a step of forcibly sedimenting coarse particles of slurry containing abrasive grains with a centrifuge and a step of taking out only the supernatant. A method using a high-pressure homogenizer is a method in which abrasive grains in a dispersion medium collide with each other at a high pressure.
　（Ｂ）濃縮タイプは、使用直前に、含有成分の含有量が所望の含有量となるように水で希釈される。希釈後、（Ａ）通常タイプと同程度の液状特性（ｐＨ、砥粒の粒径等）及び研磨特性（無機絶縁材料（例えば酸化ケイ素）に対する研磨速度、ストッパ材料（例えば窒化ケイ素）に対する無機絶縁材料（例えば酸化ケイ素）の研磨選択比等）を再現できるまで、任意の時間にわたって攪拌又は砥粒の分散処理を行ってもよい。（Ｂ）濃縮タイプでは、濃縮の度合いに応じて容積が小さくなるため、保管及び輸送にかかるコストを減らすことができる。 (B) The concentrated type is diluted with water so that the content of the contained components becomes a desired content immediately before use. After dilution, (A) Liquid characteristics (pH, grain size of abrasive grains, etc.) and polishing characteristics (polishing rate for inorganic insulating material (for example, silicon oxide), inorganic insulation for stopper material (for example, silicon nitride) similar to normal type Stirring or abrasive dispersion may be performed for an arbitrary time until a material (for example, silicon oxide polishing selectivity) can be reproduced. (B) In the concentration type, the volume is reduced according to the degree of concentration, so that the cost for storage and transportation can be reduced.
　濃縮倍率は、１．５倍以上が好ましく、２倍以上がより好ましく、３倍以上が更に好ましく、５倍以上が特に好ましい。濃縮倍率が１．５倍以上であると、１．５倍未満の場合と比較して保管及び輸送に関するメリットを得ることができる。濃縮倍率は、４０倍以下が好ましく、２０倍以下がより好ましく、１５倍以下が更に好ましい。濃縮倍率が４０倍以下であると、４０倍を超える場合と比較して砥粒の凝集を抑制しやすい。 The concentration ratio is preferably 1.5 times or more, more preferably 2 times or more, further preferably 3 times or more, and particularly preferably 5 times or more. When the concentration ratio is 1.5 times or more, it is possible to obtain merit related to storage and transportation as compared to the case of less than 1.5 times. The concentration factor is preferably 40 times or less, more preferably 20 times or less, and still more preferably 15 times or less. When the concentration ratio is 40 times or less, it is easy to suppress the aggregation of abrasive grains as compared to the case where the concentration ratio exceeds 40 times.
　（Ｂ）濃縮タイプの使用に際して注意すべき点は、水による希釈の前後でｐＨが変化する点である。（Ａ）通常タイプと同じｐＨの研磨液を（Ｂ）濃縮タイプから調製するには、水との混合によるｐＨ上昇を考慮に入れ、濃縮タイプの研磨液のｐＨを予め低めに設定しておけばよい。例えば、二酸化炭素が溶解した水（ｐＨ：約５．６）を使用し、ｐＨ４．０の（Ｂ）濃縮タイプの研磨液を１０倍に希釈した場合、希釈後の研磨液のｐＨは４．３程度にまで上昇する。 (B) The point to be noted when using the concentrated type is that the pH changes before and after dilution with water. (A) To prepare a polishing liquid having the same pH as that of the normal type from (B) the concentrated type, the pH of the concentrated type polishing liquid should be set low in advance, taking into account the increase in pH due to mixing with water. That's fine. For example, when water (pH: about 5.6) in which carbon dioxide is dissolved is used and (B) concentrated type polishing liquid having pH 4.0 is diluted 10 times, the pH of the diluted polishing liquid is 4. It rises to about 3.
　（Ｂ）濃縮タイプのｐＨは、水による希釈後において適したｐＨの研磨液を得る観点から、１．５～７．０が好ましい。ｐＨの下限は、１．５以上が好ましく、２．０以上がより好ましく、２．５以上が更に好ましい。ｐＨの上限は、砥粒の凝集を抑制する観点から、７．０以下が好ましく、６．７以下がより好ましく、６．０以下が更に好ましく、５．５以下が特に好ましい。 (B) The pH of the concentrated type is preferably 1.5 to 7.0 from the viewpoint of obtaining a polishing liquid having a suitable pH after dilution with water. The lower limit of the pH is preferably 1.5 or more, more preferably 2.0 or more, and further preferably 2.5 or more. The upper limit of the pH is preferably 7.0 or less, more preferably 6.7 or less, still more preferably 6.0 or less, and particularly preferably 5.5 or less from the viewpoint of suppressing the aggregation of abrasive grains.
　（Ｃ）２液タイプは、（Ｂ）濃縮タイプと比較して砥粒の凝集等を回避できるという利点がある。液Ａ及び液Ｂがそれぞれ含有する成分は任意である。例えば、砥粒と、必要に応じて配合される界面活性剤等とを含むスラリを液Ａとして調製し、添加剤と、必要に応じて配合される他の成分とを含む溶液を液Ｂとして調製することができる。この場合、液Ａにおける砥粒の分散性を高めるため、任意の酸又はアルカリを液Ａに配合し、ｐＨを調整してもよい。 (C) The two-liquid type has an advantage that it can avoid agglomeration of abrasive grains and the like as compared with the (B) concentrated type. The component which each of the liquid A and the liquid B contains is arbitrary. For example, a slurry containing abrasive grains and surfactants blended as necessary is prepared as liquid A, and a solution containing additives and other ingredients blended as needed is liquid B. Can be prepared. In this case, in order to improve the dispersibility of the abrasive grains in the liquid A, any acid or alkali may be added to the liquid A to adjust the pH.
　（Ｃ）２液タイプの研磨液は、各成分が混合された状態では、砥粒の凝集等によって研磨特性が比較的短時間で低下する場合に有用である。なお、保管及び輸送にかかるコスト削減の観点から、液Ａ及び液Ｂを少なくとも一方を濃縮タイプとしてもよい。この場合、研磨液を使用する際に、液Ａと液Ｂと水とを混合すればよい。液Ａ又は液Ｂの濃縮倍率及びｐＨは任意であり、最終的な混合物の液状特性及び研磨特性が（Ａ）通常タイプの研磨液と同程度であればよい。 (C) The two-liquid type polishing liquid is useful when the polishing characteristics are deteriorated in a relatively short time due to aggregation of abrasive grains or the like in a state where the respective components are mixed. In addition, from the viewpoint of cost reduction for storage and transportation, at least one of the liquid A and the liquid B may be a concentrated type. In this case, the liquid A, the liquid B, and water may be mixed when using the polishing liquid. The concentration ratio and pH of the liquid A or the liquid B are arbitrary, and the liquid characteristics and polishing characteristics of the final mixture may be the same as those of the (A) normal type polishing liquid.
＜研磨方法＞
　本実施形態に係る研磨方法は、本実施形態に係るＣＭＰ用研磨液を用いて無機絶縁材料（例えば酸化ケイ素）を研磨する研磨工程を備える。例えば、研磨工程では、本実施形態に係るＣＭＰ用研磨液を用いて、表面に無機絶縁材料（例えば酸化ケイ素）を有する基板をＣＭＰ技術によって研磨して平坦化する。本実施形態に係る研磨方法は、具体的には、本実施形態に係るＣＭＰ用研磨液が、表面に無機絶縁材料（例えば酸化ケイ素）を有する基板における無機絶縁材料と、所定の研磨部材（例えば研磨パッド）との間に供給された状態で研磨部材によって無機絶縁材料を研磨する工程を備える。本実施形態に係る研磨方法では、無機絶縁材料を研磨して無機絶縁材料の少なくとも一部を除去する。研磨対象である無機絶縁材料は、膜状（無機絶縁膜。例えば酸化ケイ素膜）であってもよい。本実施形態に係る研磨方法において、ＣＭＰ用研磨液の各成分の含有量及びｐＨ等は適宜調整される。 <Polishing method>
The polishing method according to the present embodiment includes a polishing step of polishing an inorganic insulating material (for example, silicon oxide) using the CMP polishing liquid according to the present embodiment. For example, in the polishing step, the substrate having an inorganic insulating material (for example, silicon oxide) on the surface is polished and planarized by the CMP technique using the CMP polishing liquid according to the present embodiment. Specifically, in the polishing method according to this embodiment, the CMP polishing liquid according to this embodiment includes an inorganic insulating material on a substrate having an inorganic insulating material (for example, silicon oxide) on the surface, and a predetermined polishing member (for example, A step of polishing the inorganic insulating material by the polishing member while being supplied to the polishing pad. In the polishing method according to this embodiment, the inorganic insulating material is polished to remove at least a part of the inorganic insulating material. The inorganic insulating material to be polished may be in the form of a film (inorganic insulating film such as a silicon oxide film). In the polishing method according to the present embodiment, the content and pH of each component of the CMP polishing liquid are appropriately adjusted.
　本実施形態に係る研磨方法は、以下のようなデバイスの製造過程において、表面に無機絶縁材料（例えば酸化ケイ素）を有する基板を研磨することに適している。デバイスとしては、ダイオード、トランジスタ、化合物半導体、サーミスタ、バリスタ、サイリスタ等の個別半導体；ＤＲＡＭ（ダイナミック・ランダム・アクセス・メモリー）、ＳＲＡＭ（スタティック・ランダム・アクセス・メモリー）、ＥＰＲＯＭ（イレイザブル・プログラマブル・リード・オンリー・メモリー）、マスクＲＯＭ（マスク・リード・オンリー・メモリー）、ＥＥＰＲＯＭ（エレクトリカル・イレイザブル・プログラマブル・リード・オンリー・メモリー）、フラッシュメモリ等の記憶素子；マイクロプロセッサー、ＤＳＰ、ＡＳＩＣ等の理論回路素子；ＭＭＩＣ（モノリシック・マイクロウェーブ集積回路）に代表される化合物半導体等の集積回路素子；混成集積回路（ハイブリッドＩＣ）；発光ダイオード；電荷結合素子等の光電変換素子などが挙げられる。 The polishing method according to the present embodiment is suitable for polishing a substrate having an inorganic insulating material (for example, silicon oxide) on the surface in the following device manufacturing process. Devices include diodes, transistors, compound semiconductors, thermistors, varistors, thyristors and other individual semiconductors; DRAM (dynamic random access memory), SRAM (static random access memory), EPROM (erasable programmable read)・ Only memory (memory), mask ROM (mask read only memory), EEPROM (electrically erasable programmable read only memory), storage devices such as flash memory; theoretical circuit such as microprocessor, DSP, ASIC, etc. Element; Integrated circuit element such as compound semiconductor represented by MMIC (monolithic microwave integrated circuit); Hybrid integrated circuit (hybrid IC); Light-emitting diode; Such as photoelectric conversion elements, such as elements and the like.
　本実施形態に係るＣＭＰ用研磨液は、高い研磨速度及び高い段差除去性を両立できる。そのため、当該ＣＭＰ用研磨液を用いた研磨方法は、従来のＣＭＰ用研磨液を用いた方法では高い研磨速度を達成することが困難であった基板に対しても適用できる。 The CMP polishing liquid according to the present embodiment can achieve both a high polishing rate and a high level difference removal property. Therefore, the polishing method using the CMP polishing liquid can be applied to a substrate for which it has been difficult to achieve a high polishing rate by the conventional method using the CMP polishing liquid.
　本実施形態に係る研磨方法は、表面に段差（凹凸）を有する被研磨面の平坦化に特に適している。このような被研磨面を有する基板としては、例えば、ロジック用の半導体基板が挙げられる。また、基板の表面は、Ｔ字形状又は格子形状の凹部又は凸部を有していてもよく、本実施形態に係る研磨方法は、上（基板の前記表面に対向する方向）から見たときに凹部又は凸部がＴ字形状又は格子形状に設けられた部分を表面に有する基板を研磨することに適している。例えば、メモリセルを有する半導体基板（例えば、ＤＲＡＭ及びフラッシュメモリ等のデバイスの基板）の表面に設けられた無機絶縁材料（例えば酸化ケイ素）も高い速度で研磨できる。これらは、従来のＣＭＰ用研磨液を用いた方法では高い研磨速度を達成することが困難であったものであり、本実施形態に係るＣＭＰ用研磨液が、高い研磨速度及び高い段差除去性を両立できることを示している。 The polishing method according to the present embodiment is particularly suitable for flattening a surface to be polished having a step (unevenness) on the surface. An example of a substrate having such a surface to be polished is a logic semiconductor substrate. The surface of the substrate may have a T-shaped or lattice-shaped concave or convex portion, and the polishing method according to the present embodiment is viewed from above (in the direction facing the surface of the substrate). It is suitable for polishing a substrate having on its surface a portion in which concave portions or convex portions are provided in a T shape or a lattice shape. For example, an inorganic insulating material (for example, silicon oxide) provided on the surface of a semiconductor substrate having memory cells (for example, a substrate of a device such as a DRAM or flash memory) can be polished at a high speed. These are difficult to achieve a high polishing rate by the conventional method using the CMP polishing liquid, and the CMP polishing liquid according to the present embodiment has a high polishing speed and a high step removal property. It shows that they can be compatible.
　なお、本実施形態に係る研磨方法を適用できる基板は、基板表面全体が酸化ケイ素膜によって形成された基板に限らず、基板表面に酸化ケイ素膜の他に窒化ケイ素膜、多結晶シリコン膜等を更に有する基板であってもよい。また、本実施形態に係る研磨方法は、所定の配線を有する配線板上に、酸化ケイ素膜、ガラス膜、窒化ケイ素等の無機絶縁膜；ポリシリコン、Ａｌ、Ｃｕ、Ｔｉ、ＴｉＮ、Ｗ、Ｔａ、ＴａＮ等を主として含有する膜などが形成された基板に対しても適用できる。 The substrate to which the polishing method according to this embodiment can be applied is not limited to a substrate in which the entire surface of the substrate is formed of a silicon oxide film, but a silicon nitride film, a polycrystalline silicon film, or the like in addition to the silicon oxide film is formed on the substrate surface. Further, it may be a substrate. In addition, the polishing method according to the present embodiment includes an inorganic insulating film such as a silicon oxide film, a glass film, and silicon nitride on a wiring board having predetermined wiring; polysilicon, Al, Cu, Ti, TiN, W, Ta It can also be applied to a substrate on which a film mainly containing TaN or the like is formed.
　基板表面に酸化ケイ素膜を形成する方法としては、低圧ＣＶＤ法、プラズマＣＶＤ法等が挙げられる。低圧ＣＶＤ法による酸化ケイ素膜の形成方法では、例えば、Ｓｉ源としてモノシラン（ＳｉＨ４）、酸素源として酸素（Ｏ２）を用いる。このＳｉＨ４－Ｏ２系酸化反応を４００℃以下の低温で行うことによって酸化ケイ素膜が形成される。場合によっては、ＣＶＤ後に１０００℃又はそれ以下の温度での熱処理が実施される。 Examples of a method for forming a silicon oxide film on the substrate surface include a low pressure CVD method and a plasma CVD method. In the method for forming a silicon oxide film by the low pressure CVD method, for example, monosilane (SiH 4 ) is used as the Si source, and oxygen (O 2 ) is used as the oxygen source. By performing this SiH 4 —O 2 oxidation reaction at a low temperature of 400 ° C. or lower, a silicon oxide film is formed. In some cases, heat treatment is performed at a temperature of 1000 ° C. or lower after CVD.
　プラズマＣＶＤ法は、通常の熱平衡下では高温を必要とする化学反応が低温でできる利点を有する。プラズマ発生法には、容量結合型及び誘導結合型の２つが挙げられる。反応ガスとしては、例えば、Ｓｉ源としてＳｉＨ４、酸素源としてＮ２Ｏを用いたＳｉＨ４－Ｎ２Ｏ系ガス、及び、テトラエトキシシラン（ＴＥＯＳ）をＳｉ源に用いたＴＥＯＳ－Ｏ２系ガス（ＴＥＯＳ－プラズマＣＶＤ法）が挙げられる。基板温度は２５０～４００℃が好ましい。反応圧力は６７～４００Ｐａが好ましい。 The plasma CVD method has an advantage that a chemical reaction requiring a high temperature can be performed at a low temperature under normal thermal equilibrium. There are two plasma generation methods, capacitive coupling type and inductive coupling type. As the reaction gas, for example, SiH 4, SiH 4 -N 2 O -containing gas using N 2 O as oxygen source, and, TEOS-O 2 system using tetraethoxysilane (TEOS) to Si source as Si source Gas (TEOS-plasma CVD method) can be mentioned. The substrate temperature is preferably 250 to 400 ° C. The reaction pressure is preferably 67 to 400 Pa.
　高温リフローによる表面平坦化を図るために、酸化ケイ素膜にリン（Ｐ）をドープする場合、ＳｉＨ４－Ｏ２－ＰＨ３系反応ガスを用いることが好ましい。このように、研磨対象の酸化ケイ素膜は、リン、ホウ素等の元素がドープされたものであってもよい。 In order to planarize the surface by high-temperature reflow, when doping silicon (P) into the silicon oxide film, it is preferable to use a SiH 4 —O 2 —PH 3 -based reactive gas. Thus, the silicon oxide film to be polished may be doped with an element such as phosphorus or boron.
　窒化ケイ素膜も酸化ケイ素膜と同様、低圧ＣＶＤ法、プラズマＣＶＤ法等により形成することができる。低圧ＣＶＤ法では、例えば、Ｓｉ源としてジクロルシラン（ＳｉＨ２Ｃｌ２）、窒素源としてアンモニア（ＮＨ３）を用いる。このＳｉＨ２Ｃｌ２－ＮＨ３系酸化反応を９００℃の高温で行うことによって窒化ケイ素膜が形成される。プラズマＣＶＤ法では、例えば、Ｓｉ源としてＳｉＨ４、窒素源としてＮＨ３を用いたＳｉＨ４－ＮＨ３系ガスが反応ガスとして挙げられる。この場合、基板温度は３００～４００℃が好ましい。 Similarly to the silicon oxide film, the silicon nitride film can be formed by a low pressure CVD method, a plasma CVD method, or the like. In the low pressure CVD method, for example, dichlorosilane (SiH 2 Cl 2 ) is used as the Si source, and ammonia (NH 3 ) is used as the nitrogen source. By performing this SiH 2 Cl 2 —NH 3 oxidation reaction at a high temperature of 900 ° C., a silicon nitride film is formed. In the plasma CVD method, for example, SiH 4 —NH 3 based gas using SiH 4 as a Si source and NH 3 as a nitrogen source is used as a reactive gas. In this case, the substrate temperature is preferably 300 to 400 ° C.
　図１を参照して、本実施形態に係る研磨方法においてＣＭＰによって基板（ウェハ）にＳＴＩ構造を形成するプロセスについて説明する。本実施形態に係る研磨方法は、酸化ケイ素膜３を高い研磨速度と高い段差除去性とで研磨する第一の工程（荒削り工程）、及び、残りの酸化ケイ素膜３を任意の膜厚となるように高い研磨速度で研磨する第二の工程（仕上げ工程）とを備える。 A process for forming an STI structure on a substrate (wafer) by CMP in the polishing method according to the present embodiment will be described with reference to FIG. In the polishing method according to this embodiment, the first step (roughing step) of polishing the silicon oxide film 3 at a high polishing rate and high step removal property, and the remaining silicon oxide film 3 have an arbitrary film thickness. And a second step (finishing step) for polishing at a high polishing rate.
　図１（ａ）は研磨前の基板を示す断面図である。図１（ｂ）は第一の工程後の基板を示す断面図である。図１（ｃ）は第二の工程後の基板を示す断面図である。これらの図に示すように、ＳＴＩ構造を形成する過程では、シリコン基板１上に成膜した酸化ケイ素膜３の段差Ｄを解消するため、部分的に突出した不要な箇所をＣＭＰによって優先的に除去する。なお、表面が平坦化した時点で適切に研磨を停止させるため、酸化ケイ素膜３の下には、研磨速度の遅い窒化ケイ素膜（ストッパ膜）２を予め形成しておくことが好ましい。第一の工程及び第二の工程を経ることによって酸化ケイ素膜３の段差Ｄが解消され、埋め込み部分５を有する素子分離構造が形成される。 FIG. 1A is a cross-sectional view showing a substrate before polishing. FIG. 1B is a cross-sectional view showing the substrate after the first step. FIG.1 (c) is sectional drawing which shows the board | substrate after a 2nd process. As shown in these figures, in the process of forming the STI structure, in order to eliminate the step D of the silicon oxide film 3 formed on the silicon substrate 1, unnecessary protruding portions are preferentially processed by CMP. Remove. In order to stop the polishing appropriately when the surface is flattened, it is preferable to previously form a silicon nitride film (stopper film) 2 having a low polishing rate under the silicon oxide film 3 in advance. By passing through the first step and the second step, the step D of the silicon oxide film 3 is eliminated, and an element isolation structure having a buried portion 5 is formed.
　酸化ケイ素膜３を研磨するには、酸化ケイ素膜３の表面と研磨パッドとが当接するように、研磨パッド上に基板（ウェハ）を配置し、研磨パッドによって酸化ケイ素膜３の表面を研磨する。より具体的には、研磨定盤の研磨パッドに酸化ケイ素膜３の被研磨面側を押し当て、被研磨面と研磨パッドとの間にＣＭＰ用研磨液が供給された状態で両者を相対的に動かすことによって酸化ケイ素膜３を研磨する。 In order to polish the silicon oxide film 3, a substrate (wafer) is disposed on the polishing pad so that the surface of the silicon oxide film 3 and the polishing pad come into contact with each other, and the surface of the silicon oxide film 3 is polished by the polishing pad. . More specifically, the surface to be polished of the silicon oxide film 3 is pressed against the polishing pad of the polishing surface plate, and the two are relative to each other in a state where the polishing liquid for CMP is supplied between the surface to be polished and the polishing pad. The silicon oxide film 3 is polished by moving to.
　本実施形態に係るＣＭＰ用研磨液は、第一の工程及び第二の工程のいずれにも適用できるが、高い研磨速度及び高い段差除去性を両立し得るので、第一の工程において使用されることが特に好ましい。なお、ここでは、研磨工程を２段階に分けて実施する場合を例示したが、図１（ａ）に示す状態から図１（ｃ）に示す状態まで一段階で研磨処理することもできる。 The CMP polishing liquid according to the present embodiment can be applied to both the first step and the second step, but can be used in the first step because it can achieve both a high polishing rate and a high level difference removal property. It is particularly preferred. Although the case where the polishing process is performed in two stages is illustrated here, the polishing process can be performed in one stage from the state shown in FIG. 1A to the state shown in FIG.
　研磨装置としては、例えば、基板を保持するホルダーと、研磨パッドが貼り付けられる研磨定盤と、研磨パッド上に研磨液を供給する手段とを備える装置が好適である。研磨装置としては、株式会社荏原製作所製の研磨装置（型番：ＥＰＯ－１１１、ＥＰＯ－２２２、ＦＲＥＸ２００、ＦＲＥＸ３００）、ＡＰＰＬＩＥＤ　ＭＡＴＥＲＩＡＬＳ社製の研磨装置（商品名：Ｍｉｒｒａ３４００、Ｒｅｆｌｅｘｉｏｎ研磨機）等が挙げられる。研磨パッドとしては、特に制限はなく、例えば、一般的な不織布、発泡ポリウレタン、多孔質フッ素樹脂等を使用することができる。また、研磨パッドは、研磨液が溜まるような溝加工が施されたものが好ましい。 As the polishing apparatus, for example, an apparatus including a holder for holding a substrate, a polishing surface plate to which the polishing pad is attached, and means for supplying a polishing liquid onto the polishing pad is suitable. Examples of the polishing apparatus include polishing apparatuses manufactured by Ebara Manufacturing Co., Ltd. (model numbers: EPO-111, EPO-222, FREX200, and FREX300), APPLIED MATERIALS polishing apparatuses (trade name: Mirara 3400, Reflexion polishing machine), and the like. . There is no restriction | limiting in particular as a polishing pad, For example, a general nonwoven fabric, a polyurethane foam, a porous fluororesin, etc. can be used. Further, the polishing pad is preferably subjected to groove processing so that the polishing liquid is accumulated.
　研磨条件としては、特に制限はないが、基板が飛び出すことを抑制する観点から、研磨定盤の回転速度は２００ｍｉｎ－１以下が好ましく、基板にかける圧力（加工荷重）は、研磨面の傷を抑制する観点から、１００ｋＰａ以下が好ましい。研磨している間、ポンプ等によって研磨パッドに研磨液を連続的に供給することが好ましい。この供給量に制限はないが、研磨パッドの表面が常に研磨液で覆われていることが好ましい。 The polishing conditions are not particularly limited, but from the viewpoint of suppressing the substrate from popping out, the rotation speed of the polishing platen is preferably 200 min −1 or less, and the pressure (working load) applied to the substrate causes scratches on the polishing surface. From the viewpoint of suppression, 100 kPa or less is preferable. During polishing, it is preferable to continuously supply the polishing liquid to the polishing pad by a pump or the like. Although there is no restriction | limiting in this supply amount, it is preferable that the surface of a polishing pad is always covered with polishing liquid.
　研磨終了後、流水中で基板を充分に洗浄し、さらに、基板上に付着した水滴をスピンドライヤ等により払い落としてから乾燥させることが好ましい。このように研磨することによって、表面の凹凸を解消し、基板全面にわたって平滑な面を得ることができる。膜の形成及びこれを研磨する工程を所定の回数繰り返すことによって、所望の層数を有する基板を製造することができる。 After completion of polishing, it is preferable that the substrate is thoroughly washed in running water, and further, water droplets adhering to the substrate are removed by a spin dryer or the like and then dried. By polishing in this way, surface irregularities can be eliminated and a smooth surface can be obtained over the entire surface of the substrate. A substrate having a desired number of layers can be manufactured by repeating the formation of the film and the step of polishing the film a predetermined number of times.
　このようにして得られた基板は、種々の電子部品及び機械部品として使用することができる。具体例としては、半導体素子；フォトマスク、レンズ、プリズム等の光学ガラス；ＩＴＯ等の無機導電膜；ガラス及び結晶質材料で構成される光集積回路・光スイッチング素子・光導波路；光ファイバーの端面、シンチレータ等の光学用単結晶；固体レーザ単結晶；青色レーザＬＥＤ用サファイヤ基板；ＳｉＣ、ＧａＰ、ＧａＡｓ等の半導体単結晶；磁気ディスク用ガラス基板；磁気ヘッドなどが挙げられる。 The substrate thus obtained can be used as various electronic parts and mechanical parts. Specific examples include: semiconductor elements; optical glasses such as photomasks, lenses, and prisms; inorganic conductive films such as ITO; optical integrated circuits / optical switching elements / optical waveguides composed of glass and crystalline materials; Examples include optical single crystals such as scintillators; solid laser single crystals; sapphire substrates for blue laser LEDs; semiconductor single crystals such as SiC, GaP and GaAs; glass substrates for magnetic disks; magnetic heads and the like.
　以下、本発明を実施例により更に詳細に説明するが、本発明はこれらの実施例に限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
［砥粒の作製］
　炭酸セリウム水和物４０ｋｇをアルミナ製容器に入れ、８３０℃で２時間、空気中で焼成して黄白色の粉末を２０ｋｇ得た。この粉末についてＸ線回折法で相同定を行い、当該粉末が多結晶体の酸化セリウムを含むことを確認した。焼成によって得られた粉末の粒子径をＳＥＭで観察したところ、２０～１００μｍであった。次いで、ジェットミルを用いて酸化セリウム粉末２０ｋｇを乾式粉砕した。粉砕後の酸化セリウム粉末をＳＥＭで観察したところ、結晶粒界を有する多結晶酸化セリウム粒子が含まれていることが確認された。また、酸化セリウム粉末の比表面積は９．４ｍ２／ｇであった。比表面積の測定はＢＥＴ法によって実施した。 [Production 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. This powder was subjected to phase identification by X-ray diffraction, and it was confirmed that the powder contained polycrystalline cerium oxide. When the particle diameter of the powder obtained by firing was observed by SEM, it was 20 to 100 μm. Next, 20 kg of cerium oxide powder was dry-ground using a jet mill. When the cerium oxide powder after pulverization was observed with an SEM, it was confirmed that polycrystalline cerium oxide particles having crystal grain boundaries were contained. The specific surface area of the cerium oxide powder was 9.4 m 2 / g. The specific surface area was measured by the BET method.
［ＣＭＰ用研磨液の調製］
（実施例１～７及び比較例１～６）
　前記で得られた酸化セリウム粉末１５．０ｋｇ及び脱イオン水８４．９８ｋｇを容器内に入れて混合した。さらに、７０質量％の硝酸水溶液を添加することによりｐＨを４．５未満に調整すると共に最終的なスラリの質量を１００．００ｋｇに調整した後、１０分間攪拌してスラリを得た。得られたスラリを別の容器に３０分かけて送液した。その間、送液する配管内で、スラリに対して超音波周波数４００ｋＨｚにて超音波照射を行った。得られたスラリにおける砥粒の含有量は１５．０質量％であった。 [Preparation of polishing liquid for CMP]
(Examples 1 to 7 and Comparative Examples 1 to 6)
15.0 kg of the cerium oxide powder obtained above and 84.98 kg of deionized water were placed in a container and mixed. Furthermore, the pH was adjusted to less than 4.5 by adding a 70% by mass aqueous nitric acid solution, and the final slurry mass was adjusted to 100.00 kg, followed by stirring for 10 minutes to obtain a slurry. The obtained slurry was sent to another container over 30 minutes. In the meantime, ultrasonic irradiation was performed on the slurry at an ultrasonic frequency of 400 kHz in the pipe for feeding the liquid. The content of abrasive grains in the obtained slurry was 15.0% by mass.
　砥粒の平均粒径を測定するために、５００ｍＬビーカー４個にそれぞれ５００ｇ±２０ｇのスラリを採取し、遠心分離を行った。遠心分離は、外周にかかる遠心力が５００Ｇになる条件で２分間実施した。ビーカー内の液相を回収した。液相は、酸化セリウムを含む砥粒を含有していた。液相の水量を調整して、液相の全質量基準で砥粒の含有量を０．５質量％に調整した。その後、動的光散乱式粒度分布計（株式会社堀場製作所製、商品名：ＬＢ－５００）を用いて砥粒の平均粒径を測定した結果、平均粒径は１５０ｎｍであった。 In order to measure the average particle size of the abrasive grains, 500 g ± 20 g of slurry was collected from each of four 500 mL beakers and centrifuged. Centrifugation was performed for 2 minutes under the condition that the centrifugal force applied to the outer periphery was 500G. The liquid phase in the beaker was collected. The liquid phase contained abrasive grains containing cerium oxide. The amount of water in the liquid phase was adjusted, and the content of abrasive grains was adjusted to 0.5% by mass based on the total mass of the liquid phase. Thereafter, the average particle size of the abrasive grains was measured using a dynamic light scattering particle size distribution meter (trade name: LB-500, manufactured by Horiba, Ltd.). As a result, the average particle size was 150 nm.
　上述の遠心分離後の液相を脱イオン水で希釈し、砥粒の含有量を５．０質量％に調整した。また、研磨直前に、砥粒の含有量が５．０質量％に調整された前記液相に、表１又は表２に示す各化合物を各表に記載の含有量となるように添加すると共に、有機酸又はアンモニアを用いてｐＨを３．４に調整した。その後、１０分間攪拌してＣＭＰ用研磨液を得た。ＣＭＰ用研磨液における砥粒の含有量は、表に示すとおりであった。 The liquid phase after the above centrifugation was diluted with deionized water to adjust the abrasive content to 5.0% by mass. Further, immediately before polishing, each compound shown in Table 1 or Table 2 is added to the liquid phase in which the content of abrasive grains is adjusted to 5.0% by mass so as to have the content described in each table. The pH was adjusted to 3.4 using organic acid or ammonia. Thereafter, stirring was performed for 10 minutes to obtain a polishing slurry for CMP. The content of abrasive grains in the CMP polishing liquid was as shown in the table.
　なお、ＣＭＰ用研磨液のｐＨは下記の条件で求めた。
　　測定温度：２５±５℃
　　測定器：電気化学計器株式会社製、型番：ＰＨＬ－４０ The pH of the CMP polishing liquid was determined under the following conditions.
Measurement temperature: 25 ± 5 ° C
Measuring instrument: manufactured by Electrochemical Instrument Co., Ltd. Model number: PHL-40
　なお、このようにして得られた実施例１～７に係るＣＭＰ用研磨液を、サンプルの全質量基準で砥粒の含有量が０．５質量％となるように純水で希釈して粒径測定用のサンプルを得た。このサンプルを用いて、動的光散乱式粒度分布計（株式会社堀場製作所製、商品名：ＬＢ－５００）により砥粒の平均粒径を測定したところ、いずれも１５０±５ｎｍであった。 The CMP polishing liquids according to Examples 1 to 7 obtained in this way were diluted with pure water so that the abrasive content was 0.5% by mass based on the total mass of the sample. A sample for diameter measurement was obtained. Using this sample, the average particle size of the abrasive grains was measured by a dynamic light scattering type particle size distribution analyzer (trade name: LB-500, manufactured by Horiba, Ltd.), and all were 150 ± 5 nm.
　実施例１～７に係るＣＭＰ用研磨液は、第一の添加剤及び第二の添加剤を使用して調製された研磨液である。比較例１～３に係るＣＭＰ用研磨液は、第二の添加剤を使用せずに調製された研磨液である。比較例４に係るＣＭＰ用研磨液は、第一の添加剤及び第二の添加剤を使用せずに調製された研磨液である。比較例５及び比較例６に係るＣＭＰ用研磨液は、第一の添加剤を使用せずに調製された研磨液である。表１及び表２中の第一の添加剤に関して、「Ａ」は、５－ヒドロキシ－２－ヒドロキシメチル－４－ピロン（別名：コウジ酸）であり、「Ｂ」は、３－ヒドロキシ－２－メチル－４－ピロン（別名：マルトール）である。 The polishing slurry for CMP according to Examples 1 to 7 is a polishing solution prepared using the first additive and the second additive. The CMP polishing liquid according to Comparative Examples 1 to 3 is a polishing liquid prepared without using the second additive. The CMP polishing liquid according to Comparative Example 4 is a polishing liquid prepared without using the first additive and the second additive. The CMP polishing liquid according to Comparative Example 5 and Comparative Example 6 is a polishing liquid prepared without using the first additive. Regarding the first additive in Tables 1 and 2, “A” is 5-hydroxy-2-hydroxymethyl-4-pyrone (also known as kojic acid), and “B” is 3-hydroxy-2 -Methyl-4-pyrone (also known as maltol).
［研磨特性評価］
（ウェハの準備）
　表面に酸化ケイ素膜を被研磨膜として有するブランケットウェハを準備した。ブランケットウェハは、直径３００ｍｍのシリコン基板上に配置された膜厚１０００ｎｍの酸化ケイ素膜を有するウェハである。 [Polishing property evaluation]
(Wafer preparation)
A blanket wafer having a silicon oxide film on the surface as a film to be polished was prepared. A blanket wafer is a wafer having a silicon oxide film having a thickness of 1000 nm disposed on a silicon substrate having a diameter of 300 mm.
　また、凹凸のある酸化ケイ素膜を被研磨膜として有するパターンウェハ（ＡＤＶＡＮＴＥＣＨ社製、商品名：ＳＥＭＡＴＥＣＨ７６４）を準備した。このパターンウェハは、直径３００ｍｍのシリコン基板上の一部にストッパ膜として窒化ケイ素膜（膜厚：１５００ｎｍ）を形成した後、窒化ケイ素膜のない部分のシリコン基板を３５０ｎｍエッチングして凹部を形成し、次いで、プラズマＣＶＤ法で６００ｎｍの酸化ケイ素膜をストッパ膜上及び凹部内に成膜して得られたウェハである。パターンウェハは、線幅がＬｉｎｅ／Ｓｐａｃｅ＝５０／５０μｍのパターンを有している。 Moreover, a pattern wafer (trade name: SEMATECH764, manufactured by ADVANTECH) having an uneven silicon oxide film as a film to be polished was prepared. In this pattern wafer, a silicon nitride film (film thickness: 1500 nm) is formed as a stopper film on a part of a silicon substrate having a diameter of 300 mm, and then a recess is formed by etching the silicon substrate without the silicon nitride film by 350 nm. Then, a wafer obtained by forming a 600 nm silicon oxide film on the stopper film and in the recess by plasma CVD. The pattern wafer has a pattern with a line width of Line / Space = 50/50 μm.
（ウェハの研磨）
　研磨装置（ＡＰＰＬＩＥＤ　ＭＡＴＥＲＩＡＬＳ社製、商品名：Ｒｅｆｌｅｘｉｏｎ　ＬＫ）を使用し、前記ブランケットウェハ及びパターンウェハを研磨した。ウェハ取り付け用の吸着パッドを有するホルダーに、前記ウェハをセットした。また、直径８００ｍｍの研磨定盤に多孔質ウレタン樹脂製の研磨パッド（ｋ－ｇｒｏｏｖｅ溝、ロデール社製、型番：ＩＣ－１０１０）を貼り付けた。 (Wafer polishing)
The blanket wafer and the pattern wafer were polished using a polishing apparatus (manufactured by APPLIED MATERIALS, trade name: Reflexion LK). The wafer was set in a holder having a suction pad for attaching the wafer. Further, a polishing pad made of porous urethane resin (k-groove groove, manufactured by Rodel, model number: IC-1010) was attached to a polishing surface plate having a diameter of 800 mm.
　前記ウェハの酸化ケイ素膜形成面を下に向けて前記ホルダーを研磨パッド上に載せた。ウェハ押付け圧力は、２８ｋＰａに設定した。 The holder was placed on the polishing pad with the silicon oxide film forming surface of the wafer facing down. The wafer pressing pressure was set to 28 kPa.
　そして、前記方法で調製した各ＣＭＰ用研磨液を、研磨定盤に貼り付けた研磨パッド上に２５０ｍＬ／ｍｉｎの流量で滴下しながら、研磨定盤とウェハとをそれぞれ回転数９３ｍｉｎ－１、８７ｍｉｎ－１で回転させて、酸化ケイ素膜を研磨した。その後、ＰＶＡブラシ（ポリビニルアルコールブラシ）を使用して研磨後のウェハを純水でよく洗浄した後、乾燥させた。 Then, each of the CMP polishing liquids prepared by the above method was dropped onto the polishing pad attached to the polishing platen at a flow rate of 250 mL / min, and the polishing platen and the wafer were rotated at a rotational speed of 93 min −1 and 87 min, respectively. The silicon oxide film was polished by rotating at -1 . Thereafter, the polished wafer was thoroughly washed with pure water using a PVA brush (polyvinyl alcohol brush) and then dried.
（研磨速度の評価）
　光干渉式膜厚測定装置（大日本スクリーン製造株式会社製、商品名：ＲＥ－３０００）を用いて、ブランケットウェハにおける研磨前後の酸化ケイ素膜の膜厚変化を測定し、膜厚変化量の平均から研磨速度を算出した。表１及び表２に結果を示す。なお、研磨速度の単位は「ｎｍ／ｍｉｎ」である。 (Evaluation of polishing rate)
Using a light interference type film thickness measuring device (trade name: RE-3000, manufactured by Dainippon Screen Mfg. Co., Ltd.), the change in the thickness of the silicon oxide film before and after polishing on the blanket wafer was measured, and the average of the change in film thickness From this, the polishing rate was calculated. Tables 1 and 2 show the results. The unit of the polishing rate is “nm / min”.
（段差除去性の評価）
　前記で測定されたブランケットウェハの研磨速度に基づき、各ＣＭＰ用研磨液について、パターンウェハを研磨するための時間として、酸化ケイ素膜を３００ｎｍ研磨するために要する時間Ｘを算出した。次に、各ＣＭＰ用研磨液を用いて、パターンウェハを前記時間Ｘ研磨した。パターンウェハの凸部における酸化ケイ素膜の研磨前後の膜厚変化量を光干渉式膜厚測定装置（大日本スクリーン製造株式会社製、商品名：ＲＥ－３０００）を用いて測定した。このときの膜厚変化量をパターンウェハ研磨量（ＰＴＷ）として求めた。また、パターンウェハ研磨量を３００ｎｍ（ブランケットウェハ研磨量（ＢＫＴ））で除した数値を段差除去性として算出した。表１及び表２に結果を示す。 (Evaluation of step removal)
Based on the polishing rate of the blanket wafer measured above, the time X required for polishing the silicon oxide film by 300 nm was calculated as the time for polishing the pattern wafer for each polishing liquid for CMP. Next, the pattern wafer was polished for the time X by using each polishing liquid for CMP. The amount of film thickness change before and after polishing of the silicon oxide film on the convex part of the pattern wafer was measured using an optical interference type film thickness measuring device (trade name: RE-3000, manufactured by Dainippon Screen Mfg. Co., Ltd.). The film thickness change amount at this time was determined as a pattern wafer polishing amount (PTW). Moreover, the numerical value which remove | divided the pattern wafer polishing amount by 300 nm (blanket wafer polishing amount (BKT)) was computed as level | step difference removal property. Tables 1 and 2 show the results.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　表１及び表２の結果から、第一の添加剤及び第二の添加剤を使用した実施例１～７では、比較例１～６と比較し、高い段差除去性を有していた。また、実施例１～７では、高い研磨速度及び高い段差除去性を両立しつつ酸化ケイ素膜を研磨できることが示された。 From the results shown in Tables 1 and 2, Examples 1 to 7 using the first additive and the second additive had higher step removal performance than Comparative Examples 1 to 6. Further, in Examples 1 to 7, it was shown that the silicon oxide film can be polished while achieving both a high polishing rate and a high level difference removing property.
　また、実施例及び比較例において用いた各ＣＭＰ用研磨液について、研磨液の各含有成分を混合して研磨液を調製してから１日経過後に砥粒の平均粒径を測定したところ、平均粒径は１５０ｎｍであり、砥粒作製時の粒径と同じであった。これにより、粒径の凝集が抑制されていることが確認された。 In addition, for each of the CMP polishing liquids used in Examples and Comparative Examples, the average particle diameter of the abrasive grains was measured after one day from the preparation of the polishing liquid by mixing the respective components of the polishing liquid. The particle size was 150 nm, which was the same as the particle size at the time of preparing abrasive grains. Thereby, it was confirmed that aggregation of a particle size is suppressed.
　本発明者等は発明を実施する最良の形態を明細書に記述している。前記の説明を同業者が読んだ場合、これらに似た好ましい変形形態が明らかになる場合もある。本発明者等は、本発明の異なる形態の実施、並びに、本発明の根幹を適用した類似形態の発明の実施についても充分意識している。また、本発明にはその原理として、特許請求の範囲中に列挙した内容の全ての変形形態、さらに、様々な前記要素の任意の組み合わせが利用できる。その全てのあり得る任意の組み合わせは、本明細書中において特別な限定がない限り、あるいは、文脈によりはっきりと否定されない限り、本発明に含まれる。 The inventors have described the best mode for carrying out the invention in the specification. Preferred variations similar to these may become apparent when reading the above description by one of ordinary skill in the art. The present inventors are fully aware of the implementation of different forms of the present invention as well as the implementation of similar forms of the invention to which the foundation of the present invention is applied. Moreover, the present invention can use, as its principle, all the modifications described in the claims and any combination of the various elements. All possible combinations thereof are included in the invention unless otherwise specified herein or otherwise clearly denied by context.
　本発明によれば、酸化ケイ素膜に対する高い研磨速度及び段差除去性を両立できるＣＭＰ用研磨液が提供される。また、本発明によれば、前記ＣＭＰ用研磨液を用いた研磨方法が提供される。 According to the present invention, there is provided a polishing slurry for CMP that can achieve both a high polishing rate and a step removal property for a silicon oxide film. The present invention also provides a polishing method using the CMP polishing liquid.
　１…シリコン基板、２…ストッパ膜（窒化ケイ素膜）３…酸化ケイ素膜、５…埋め込み部分、Ｄ…酸化ケイ素膜の膜厚の標高差（段差）。 DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 2 ... Stopper film (silicon nitride film) 3 ... Silicon oxide film, 5 ... Embedded part, D ... Elevation difference (step) of film thickness of silicon oxide film.

Claims (11)

  1. 　砥粒と、第一の添加剤と、第二の添加剤と、水と、を含有し、
    　前記第一の添加剤が、下記一般式（１）で表される４－ピロン系化合物であり、
    　前記第二の添加剤が、酸性官能基及び塩基性官能基を有する化合物である、ＣＭＰ用研磨液。
    Figure JPOXMLDOC01-appb-C000001
     ［式中、Ｘ１１、Ｘ１２及びＸ１３は、それぞれ独立に、水素原子又は１価の置換基である。］     Containing abrasive grains, a first additive, a second additive, and water,
    The first additive is a 4-pyrone compound represented by the following general formula (1):
    A polishing slurry for CMP, wherein the second additive is a compound having an acidic functional group and a basic functional group.
    Figure JPOXMLDOC01-appb-C000001
     [Wherein, X 11 , X 12 and X 13 are each independently a hydrogen atom or a monovalent substituent. ]
  2. 　前記第一の添加剤が、３－ヒドロキシ－２－メチル－４－ピロン、５－ヒドロキシ－２－（ヒドロキシメチル）－４－ピロン、及び、２－エチル－３－ヒドロキシ－４－ピロンからなる群より選ばれる少なくとも一種である、請求項１に記載のＣＭＰ用研磨液。 The first additive comprises 3-hydroxy-2-methyl-4-pyrone, 5-hydroxy-2- (hydroxymethyl) -4-pyrone, and 2-ethyl-3-hydroxy-4-pyrone. The polishing slurry for CMP according to claim 1, which is at least one selected from the group.
  3. 　前記第二の添加剤の前記酸性官能基がスルホン酸基である、請求項１又は２に記載のＣＭＰ用研磨液。 The polishing slurry for CMP according to claim 1 or 2, wherein the acidic functional group of the second additive is a sulfonic acid group.
  4. 　前記第二の添加剤の前記塩基性官能基がアミノ基である、請求項１～３のいずれか一項に記載のＣＭＰ用研磨液。 The polishing slurry for CMP according to any one of claims 1 to 3, wherein the basic functional group of the second additive is an amino group.
  5. 　前記第二の添加剤が、スルファミン酸及びアミノベンゼンスルホン酸からなる群より選ばれる少なくとも一種である、請求項１～４のいずれか一項に記載のＣＭＰ用研磨液。 The polishing slurry for CMP according to any one of claims 1 to 4, wherein the second additive is at least one selected from the group consisting of sulfamic acid and aminobenzenesulfonic acid.
  6. 　前記第一の添加剤の含有量が当該ＣＭＰ用研磨液１００質量部に対して０．００１～５質量部である、請求項１～５のいずれか一項に記載のＣＭＰ用研磨液。 6. The CMP polishing liquid according to claim 1, wherein the content of the first additive is 0.001 to 5 parts by mass with respect to 100 parts by mass of the CMP polishing liquid.
  7. 　前記第二の添加剤の含有量が当該ＣＭＰ用研磨液１００質量部に対して０．０００１～１質量部である、請求項１～６のいずれか一項に記載のＣＭＰ用研磨液。 7. The CMP polishing liquid according to claim 1, wherein the content of the second additive is 0.0001 to 1 part by mass with respect to 100 parts by mass of the CMP polishing liquid.
  8. 　前記砥粒がセリウム系化合物を含む、請求項１～７のいずれか一項に記載のＣＭＰ用研磨液。 The polishing slurry for CMP according to any one of claims 1 to 7, wherein the abrasive grains contain a cerium-based compound.
  9. 　前記セリウム系化合物が酸化セリウムである、請求項８に記載のＣＭＰ用研磨液。 The polishing slurry for CMP according to claim 8, wherein the cerium-based compound is cerium oxide.
  10. 　無機絶縁材料を研磨するために用いられる、請求項１～９のいずれか一項に記載のＣＭＰ用研磨液。 10. The polishing slurry for CMP according to claim 1, which is used for polishing an inorganic insulating material.
  11. 　表面に無機絶縁材料を有する基板を研磨する研磨方法であって、
    　請求項１～１０のいずれか一項に記載のＣＭＰ用研磨液が前記無機絶縁材料と研磨パッドとの間に供給された状態で前記研磨パッドによって前記無機絶縁材料を研磨する工程を備える、研磨方法。     A polishing method for polishing a substrate having an inorganic insulating material on a surface,
    A polishing process comprising: polishing the inorganic insulating material with the polishing pad in a state where the polishing liquid for CMP according to any one of claims 1 to 10 is supplied between the inorganic insulating material and the polishing pad. Method.
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