ORGANIC MODIFIED METAL OXIDE NANOPARTICLES, ORGANIC MODIFIED METAL OXIDE NANOPARTICLE-CONTAINING SOLUTION, ORGANIC MODIFIED METAL OXIDE NANOPARTICLE-CONTAINING RESIST COMPOSITION, AND METHOD FOR FORMING RESIST PATTERN

Abstract

To provide organically modified metal oxide nanoparticles that can be produced with a simple method and can enhancing sensitivity.SOLUTION: The organically modified metal oxide nanoparticles comprise a core, a first modifier, and a second modifier. The core has a plurality of metal atoms and a plurality of oxygen atoms covalently bonded to the plurality of metal atoms. The first modifier (A1) is a ligand selected from the group consisting of carboxylic acid carboxylate, sulfonic acid sulfonate and phosphoric acid phosphonate coordinating to the core. The second modifier (A2) is a ligand and / or an inorganic negative ion bonded to the core and different in structure from the first modifier (A1). The cores have a structure crosslinked by a covalent bond by at least the first modifier (A1).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to organically modified metal oxide nanoparticles that can be used in photoresist materials used in semiconductor manufacturing processes, etc., a solution containing organically modified metal oxide nanoparticles, a resist composition containing organically modified metal oxide nanoparticles, and a pattern forming method. [Background technology]

[0002] In recent years, semiconductor circuit patterns have become thinner, and research and development of lithography using extreme ultraviolet light (EUV light) has accelerated. As patterns become thinner, the resist films used in pattern formation become thinner. This calls for resist materials that are resistant to etching. Composite materials made of inorganic substances such as metal oxides and organic substances are being considered as candidates.

[0003] For example, a method has been proposed in which nanoparticles of metal oxides such as zirconium or hafnium, organically modified with unsaturated carboxylic acids such as methacrylic acid, are used in negative resist materials (Patent Documents 1 and 2). Since these metal oxide nanoparticles have a metal oxide core, resist materials containing these metal oxide nanoparticles have higher resistance during etching than organic resist materials. Furthermore, since the structure of these metal oxide nanoparticles is highly symmetrical, there is a low possibility that the metal oxide nanoparticles will remain as insoluble matter on the wafer during development of the resist material containing these metal oxide nanoparticles.

[0004] Also, a method has been proposed in which a complex (mononuclear complex or salt) of a metal such as zirconium or hafnium with an organic substance such as a carboxylic acid such as methacrylic acid is used in a resist material (Patent Documents 3 to 5). This resist material is suitable for thinning compared to resist materials containing nanoparticle cores because the size of the complex itself is small. However, this resist material has a higher proportion of organic matter in the formed film compared to resist materials with nanoparticle cores, and therefore has low resistance during etching. Furthermore, since the structural symmetry of this complex is low, there is a high possibility that the complex will remain on the wafer as an insoluble matter during development of a resist material containing this complex. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-173537 A [Patent Document 2] JP 2015-157807 A [Patent Document 3] JP 2015-108781 A [Patent Document 4] JP 2012-185484 A [Patent Document 5] JP 2001-72716 A Summary of the Invention [Problem to be solved by the invention]

[0006] Considering the above, the synthesis of organically modified metal oxide nanoparticles with a core diameter controlled as small as possible is important for the development of resist materials for forming fine line patterns. However, regarding the reaction mechanism of resist materials during EUV exposure, although it has been found that decarboxylation occurs when unsaturated carboxylic acids are used, the detailed mechanism and important factors in the exposure operation that determine resolution and sensitivity have not been clarified, and there is a demand for the establishment of a method for controlling resolution and sensitivity by resist materials.

[0007] Sensitivity and resolution are often adjusted by optimizing the solvents and additives in the resist solution and developer. However, if the sensitivity and resolution of the resist material can be adjusted by controlling the structure of the organically modified metal oxide nanoparticles themselves, more specifically, by modifying the core metal oxide with multiple modifying groups with different structures and controlling their composition, in addition to the elements and structure that make up the core metal oxide, it will be possible to consider more versatile methods for adjusting the resist material.

[0008] The present invention has been made in view of the above circumstances, and has an object to provide organically modified metal oxide nanoparticles, an organically modified metal oxide nanoparticle-containing solution, an organically modified metal oxide nanoparticle-containing resist composition, and a method for forming a resist pattern, which can be produced by a simple method and are capable of improving the resolution and sensitivity of a resist material. [Means for solving the problem]

[0009] The organically modified metal oxide nanoparticles according to the first embodiment of the present invention have two or more cores each including a plurality of metal atoms and a plurality of oxygen atoms covalently bonded to the plurality of metal atoms, a first modifying group (A1) which is a ligand selected from the group consisting of carboxylic acid carboxylates, sulfonic acid sulfonates, and phosphonic acid phosphonates, which is coordinately bonded to the core, and a second modifying group (A2) which is at least one type selected from the group consisting of ligands and inorganic anions having a structure different from that of the first modifying group, and have a structure in which the cores are crosslinked by at least the first modifying groups (A1) through coordinate bonds.

[0010] The organically modified metal oxide nanoparticle-containing solution according to the second embodiment of the present invention contains the organically modified metal oxide nanoparticles according to the above embodiment and a solvent.

[0011] The organically modified metal oxide nanoparticle-containing resist composition according to the third aspect of the present invention contains the organically modified metal oxide nanoparticles according to the above aspect, a solvent, and may further contain an additive. The number of metal atoms contained in one core of the organically modified metal oxide nanoparticles is preferably in the range of 2 to 12.

[0012] A method for forming a resist pattern according to a fourth aspect of the present invention includes the steps of forming a resist film on a support using the resist composition containing organically modified metal oxide nanoparticles according to the above aspect, exposing the resist film, and developing the exposed resist film to form a resist pattern. Effect of the Invention

[0013] According to the present invention, there are provided organically modified metal oxide nanoparticles, an organically modified metal oxide nanoparticle-containing solution, and an organically modified metal oxide nanoparticle-containing resist composition that can be produced by a simple method and are applicable to resist materials with high resolution and sensitivity. Also, according to the present invention, there is provided a method of forming a resist pattern that enables thinning of mask lines. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] When a resist material is irradiated with EUV light, the reactivity, i.e., sensitivity, of organically modified metal oxide nanoparticles composed of metal oxides and ligands such as carboxylic acids contained in the resist material and the resolution of the formed resist pattern vary greatly depending on the constituent elements and structure of the nanoparticle core, and the type, constituent elements, size, and molecular weight of the ligands such as carboxylic acids that are coordinated. In order to disperse the nanoparticle resist material well in the solvent when preparing the resist solution, a carboxylic acid or the like that has a high affinity with the solvent, i.e., has a structure necessary to maintain affinity, is required as the first ligand. On the other hand, considering that decarboxylation of the carboxyl group of the carboxylic acid proceeds when irradiated with EUV light after film formation, it is better to narrow the interparticle distance in the film after film formation as much as possible to avoid the expansion of the distribution of the microstructure of the film due to particle aggregation when irradiated with EUV light, i.e., the decrease in resolution, so that a carboxylic acid or the like with a structure different from the first ligand is required as the second ligand in order to narrow the interparticle distance, for example, by having a small molecular size.

[0015] The inventors have discovered that by coordinating ligands having different structures to a metal oxide core, the resulting organically modified metal oxide nanoparticles maintain their solubility in resist solvents and developers, and when a resist material containing these organically modified metal oxide nanoparticles is irradiated with EUV light, high resolution is maintained and the resist film exhibits high sensitivity to EUV light, in other words, low solubility in a developer of the EUV-irradiated portion after irradiation with EUV light.

[0016] The organically modified metal oxide nanoparticles according to the embodiment of the present invention include two or more cores, a first modifying group (A1), and a second modifying group (A2). The core has a plurality of metal atoms and a plurality of oxygen atoms covalently bonded to the plurality of metal atoms. That is, the core includes a metal oxide. In addition to the metal oxide crystal, the core can include a cluster having a structure in which a plurality of metal atoms are crosslinked by a plurality of oxygen atoms through covalent bonds, and / or a structure in which the cluster is coordinated to a cluster of another core through an organic ligand. That is, the "core" of the present embodiment can include a structure at least partially composed of a cluster, and / or a structure having a bond in which a plurality of cores, at least partially including a cluster, are coordinated to each other through a plurality of organic ligands. Metal oxide crystals and metal oxide clusters are common in that they are combinations of metal atoms and oxygen atoms, but in metal oxide crystals, each particle has a crystal structure in which metal atoms and oxygen atoms are arranged three-dimensionally and regularly, with a certain size (for example, 3 nm to 4 nm), whereas in metal oxide clusters, each particle is a molecule having a metal complex structure, and the individual particles themselves do not have a crystal structure. The multiple metal atoms may be of the same type or may be of different types. The first modifying group (A1) is a ligand selected from the group consisting of carboxylic acid carboxylates, sulfonic acid sulfonates, and phosphonic acid phosphonates, which are coordinately bonded to the core. The carboxylic acid carboxylates are carboxylates. The sulfonic acid sulfonates are sulfonates. The phosphonic acid phosphonates are phosphonates. The second modifying group (A2) is coordinately bonded to the core, and is at least one type selected from the group consisting of ligands and inorganic anions having a structure different from that of the first modifying group (A1). The cores have a structure in which they are cross-linked by a coordinate bond via at least the first modifying group (A1). The term "structure in which they are cross-linked by a coordinate bond via at least the first modifying group (A1)" means that it includes one or both of a structure in which two cores are cross-linked by a coordinate bond via the first modifying group (A1) and a structure in which two cores are cross-linked by coordinate bonds via the first modifying group (A1) and the second modifying group (A2).The two cores may contain a non-bridged first modifying group (A1) and / or a non-bridged second modifying group (A2), provided that they contain the above-mentioned bridged structure.

[0017] The first modifying group (A1) can be a ligand derived from a compound selected from the group consisting of the following general formula (a01), the following general formula (a02), and the following general formula (a03).

[0018] [ka]

[0019] [ka]

[0020] [ka] [In the formula, each R is independently a group selected from an alkyl group having 1 to 18 carbon atoms, an alkoxyalkyl group having 1 to 18 carbon atoms, an alkenyl group having 1 to 18 carbon atoms, an alkenyloxyalkyl group having 1 to 18 carbon atoms, an alkynyl group having 1 to 18 carbon atoms, an alkynyloxyalkyl group having 1 to 18 carbon atoms, an aryl group having 1 to 18 carbon atoms, an aryloxyalkyl group having 1 to 18 carbon atoms, and a cyanoalkyl group having 1 to 18 carbon atoms, or a group in which one or more hydrogen atoms of the above group have been substituted with a substituent, provided that the above substituent does not include a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, a phospho group, or a phosphonate group.]

[0021] The alkyl group, alkenyl group or alkynyl group in the alkyl group having 1 to 18 carbon atoms, alkoxyalkyl group having 1 to 18 carbon atoms, alkenyl group having 1 to 18 carbon atoms, alkenyloxyalkyl group having 1 to 18 carbon atoms, alkynyl group having 1 to 18 carbon atoms, alkynyloxyalkyl group having 1 to 18 carbon atoms, aryloxyalkyl group having 1 to 18 carbon atoms or cyanoalkyl group having 1 to 18 carbon atoms represented by R may be linear, branched or contain a cyclic structure, and is preferably linear or branched. The alkyl group having 1 to 18 carbon atoms, the alkoxyalkyl group having 1 to 18 carbon atoms, the alkenyl group having 1 to 18 carbon atoms, the alkenyloxyalkyl group having 1 to 18 carbon atoms, the alkynyl group having 1 to 18 carbon atoms, the alkynyloxyalkyl group having 1 to 18 carbon atoms, the aryl group having 1 to 18 carbon atoms, the aryloxyalkyl group having 1 to 18 carbon atoms or the cyanoalkyl group having 1 to 18 carbon atoms preferably has 1 to 15 carbon atoms, more preferably has 1 to 10 carbon atoms, further preferably has 1 to 6 carbon atoms, and particularly preferably has 1 to 3 carbon atoms. In the alkyl group having 1 to 18 carbon atoms, the alkoxyalkyl group having 1 to 18 carbon atoms, the alkenyl group having 1 to 18 carbon atoms, the alkenyloxyalkyl group having 1 to 18 carbon atoms, the alkynyl group having 1 to 18 carbon atoms, the alkynyloxyalkyl group having 1 to 18 carbon atoms, the aryl group having 1 to 18 carbon atoms, the aryloxyalkyl group having 1 to 18 carbon atoms, or the cyanoalkyl group having 1 to 18 carbon atoms, the substituent that may replace the hydrogen atom is not particularly limited, and examples thereof include, but are not limited to, an amino group, a hydroxy group, a cyano group, and a halogen atom (such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom). However, the substituent does not include a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, a phospho group, and a phosphonate group.

[0022] When the compound represented by the general formula (a01) is coordinately bonded to the core, H is released from -C(=O)OH in the formula to form -C(=O)O - Therefore, the first modifying group (A1) derived from the compound represented by the general formula (a01) is represented by the formula "RC(=O)O - " can be expressed as: The compound represented by the general formula (a02) is a compound having a structure in which, when it is coordinated to the core, -S(=O 2 )OH releases H to form -S(=O 2 )O - Therefore, the first modifying group (A1) derived from the compound represented by the general formula (a02) is "RS(=O 2 )O - " can be expressed as: The compound represented by the general formula (a03) is, when coordinately bonded to the core, -P(=O)(OH) in the formula 2 H is released from -P(=O)(OH)O - or -P(=O)(O - ) 2 Therefore, the first modifying group (A1) derived from the compound represented by the general formula (a03) is "RP(=O)(OH)O - " or "RP(=O)(O - ) 2 " can be expressed as:

[0023] The first modifying group (A1) is preferably a carboxylic acid carboxylate ligand, more preferably a saturated carboxylic acid, and particularly preferably propionic acid or methacrylic acid. The first modifying group (A1) may be one type alone or two or more types.

[0024] When the first modifying group (A1) is a carboxylic acid carboxylate ligand, the second modifying group (A2) is preferably a ligand selected from the group consisting of carboxylic acid carboxylate, sulfonic acid sulfonate, phosphonic acid phosphonate, hydroxyl group-containing ligand, thiol group-containing ligand, amino group-containing ligand, nitrate ligand (nitrate ion) and hydroxide ion, which are different in structure from the first modifying group (A1), more preferably a ligand selected from the group consisting of carboxylic acid carboxylate and sulfonic acid sulfonate, which are different in structure from the first modifying group (A1), and particularly preferably a carboxylic acid carboxylate, which are different in structure from the first modifying group (A1). The second modifying group (A2) may be one type alone or two or more types. When the second modifying group (A2) is of two or more types, it is preferably at least one type selected from the group consisting of a hydroxide ion and a hydroxy group, and at least one type selected from the group consisting of a carboxylic acid carboxylate and a sulfonic acid sulfonate having a structure different from that of the first modifying group (A1), and more preferably a carboxylic acid carboxylate having a structure different from that of the first modifying group (A1) and a hydroxide ion.

[0025] Examples of carboxylate ligands include ligands derived from acetic acid, propionic acid, butyric acid, isobutyric acid, methacrylic acid, valeric acid, caproic acid, and the like.

[0026] Examples of the sulfonate ligand include ligands derived from methylsulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, and the like.

[0027] Examples of the phosphonate ligand include ligands derived from methylphosphonic acid, phenylphosphonic acid, and the like.

[0028] Examples of the thiol group-containing ligand include ligands derived from butylthiol, benzothiol, trifluoromethylbenzothiol, and the like.

[0029] Examples of the amino group-containing ligand include ligands derived from hexylamine, aniline, and the like.

[0030] When the second modifying group (A2) is a ligand having a structure different from that of the first modifying group (A1), it can be a ligand selected from the group consisting of carboxylic acid carboxylate, sulfonic acid sulfonate, and phosphonic acid phosphonate, and each of the ligands listed above as the first modifying group (A1) can be applied. When the second modifying group (A2) is an inorganic anion, examples of the inorganic anion include a nitrate ligand (nitrate ion) and a hydroxide ion. When the second modifying group (A2) is a ligand and an inorganic anion having a structure different from that of the first modifying group (A1), examples thereof include an acetate carboxylate ligand and a hydroxide ion.

[0031] Specifically, the organically modified metal oxide nanoparticles of this embodiment are preferably represented by the following formula (m01). C01-L01-C02 (m01) In the above formula (m01), C01 is M 6 O 4 (OH) 4 [X a Y b ], where 0≦a≦10 and 1≦b≦11. C02 is M 6 O 4 (OH) 4 [X c Y d ], 0≦c≦10, 1≦d≦11. L01 is Xw, w=24-(a+b+c+d), 2≦w≦12. M is the metal atom, which is a metal atom of a Group 4 element. X is a first modifying group (A1), and Y is a second modifying group (A2).

[0032] In the above formula (m01), the number of ligands of the first modifying groups (A1) of C01 and C02 located on both sides of L01 may be the same (a=c) or different (a≠c). The number of ligands of the second modifying groups (A2) of C01 and C02 may be the same (b=d) or different (b≠d). The number of ligands in the first modifying group (A1) bridging C01 and C02 is preferably 2 or more and 8 or less (2≦w≦8), more preferably 2 or more and 4 or less (2≦w≦4).

[0033] The metal atom of the Group 4 element is preferably one or more selected from Zr, Hf, and Ti, and is more preferably Zr.

[0034] The first modifying group (A1) represented by X is preferably a carboxylic acid carboxylate, more preferably propionic acid or methacrylic acid, and even more preferably propionic acid. The second modifying group (A2) represented by Y is preferably a carboxylic acid carboxylate different from X, more preferably propionic acid or methacrylic acid, and even more preferably methacrylic acid. Examples of the combination of X and Y include a combination of X being methacrylic acid and Y being propionic acid, a combination of X being propionic acid and Y being methacrylic acid, etc. A preferred combination of X and Y is a combination of X being propionic acid and Y being methacrylic acid.

[0035] In the above formula (m01), OH functions as the second modifying group (A2). That is, the organically modified metal oxide nanoparticles represented by formula (m01) contain Y and OH as the second modifying group (A2).

[0036] Each of a and c is preferably 1 to 9 (1≦a≦9, 1≦c≦9), more preferably 2 to 8 (2≦a≦8, 2≦c≦8), and even more preferably 3 to 7 (3≦a≦7, 3≦c≦7). Each of b and d is preferably 2 to 10 (2≦b≦10, 2≦d≦10), more preferably 2 to 8 (2≦b≦8, 2≦d≦8), and even more preferably 3 to 7 (3≦d≦7, 3≦d≦7).

[0037] Specific examples of the organically modified metal oxide nanoparticles represented by formula (m01) include, but are not limited to, organically modified metal oxide nanoparticles (m01-1) in which C01, C02, and L01 in the above formula (m01) are as follows: C01=Zr 6 O 4 (OH) 4 (C 3 H 5 O 2 ) 1.96 (C 4 H 5 O 2 ) 8.04 C02=Zr 6 O 4 (OH) 4 (C 3 H 5 O 2 ) 1.96 (C 4 H 5 O 2 ) 68.04 L01=(C 3 H 5 O 2 ) 4 In the organically modified metal oxide nanoparticles (m01-1), M=Zr and X=C in the formula (m01). 3 H 5 O 2 , Y=C 4 H 5 O 2 , a=1.96, b=8.04, c=1.96, d=8.04, w=4.

[0038] (Solution containing organically modified metal oxide nanoparticles) A solution containing organically modified metal oxide nanoparticles according to one embodiment of the present invention contains the organically modified metal oxide nanoparticles of the above embodiment and a solvent.

[0039] Examples of the solvent for the solution include lactones such as γ-butyrolactone; ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl-n-pentyl ketone, methyl isopentyl ketone, and 2-heptanone; polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol; compounds having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, and dipropylene glycol monoacetate; and compounds having an ether bond such as monoalkyl ethers, monoethyl ether, monopropyl ether, and monobutyl ether of the polyhydric alcohols or the compounds having an ester bond, or monophenyl ether. Derivatives of polyhydric alcohols [among these, propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME) are preferred]; cyclic ethers such as dioxane, esters such as methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, and ethyl ethoxypropionate; aromatic organic solvents such as anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, dibenzyl ether, phenetole, butyl phenyl ether, ethylbenzene, diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymene, and mesitylene, and dimethyl sulfoxide (DMSO) may be mentioned. The solvent may be a mixed solvent containing the above organic solvent as the main component and a small amount of water.

[0040] The organically modified metal oxide nanoparticles are easily dissolved in propylene glycol 1-monomethyl ether 2-acetate (PGMEA), which is one of the general-purpose resist solvents, and therefore it is preferable to use PGMEA as the solvent for the above solution.

[0041] As the metal oxide cluster, as represented by the above formula (m01), 6 O 4 (OH) 4 In addition to the particles (dimers) bridged by the coordinate bonds of the ligands, the structure of M 6 O 4 (OH) 4 [X a Y b ] monomer, where 0≦a≦10 and 1≦b≦11. If one judges only from the viewpoint of particle size, one tends to judge that monomers are better for forming fine lines. However, in actual resist applications, sensitivity is extremely important. In general, if the dissolution rate of the non-EUV irradiated parts is too fast, it tends to be difficult to make the irradiated parts insoluble. Smaller particles are advantageous not only in terms of resolution but also in terms of dissolution rate, but on the other hand, if the particles are too small, the dissolution rate is too fast and even if the irradiation dose is increased, the particles do not become insoluble and the sensitivity is poor. Therefore, appropriate control of the dissolution rate is also important, and it is desirable for the organically modified metal oxide nanoparticles to be dimers or a mixture of dimers and monomers.

[0042] (Resist composition containing organically modified metal oxide nanoparticles) A resist composition containing organically modified metal oxide nanoparticles according to one embodiment of the present invention contains the organically modified metal oxide nanoparticles of the above embodiment and a solvent.

[0043] Examples of the solvent for the resist composition include lactones such as γ-butyrolactone; ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl-n-pentyl ketone, methyl isopentyl ketone, and 2-heptanone; polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol; compounds having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, and dipropylene glycol monoacetate; and compounds having an ether bond such as monoalkyl ethers, monoethyl ethers, monopropyl ethers, and monobutyl ethers of the polyhydric alcohols or the compounds having an ester bond, or monophenyl ethers. Derivatives of polyhydric alcohols such as propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME) are preferred among these; cyclic ethers such as dioxane, esters such as methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, and ethyl ethoxypropionate; aromatic organic solvents such as anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, dibenzyl ether, phenetole, butyl phenyl ether, ethylbenzene, diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymene, and mesitylene, and dimethyl sulfoxide (DMSO) may be mentioned. The solvent may be a mixed solvent containing the above organic solvent as the main component and a small amount of water.

[0044] Since the organically modified metal oxide nanoparticles are easily dissolved in propylene glycol 1-monomethyl ether 2-acetate (PGMEA), which is one of the commonly used resist solvents, it is preferable to use PGMEA as the solvent for the resist composition.

[0045] The resist composition may contain an additive. Examples of the additive include dispersants and stabilizers such as organic carboxylic acids and compounds selected from the group consisting of phosphorus oxo acids and their derivatives, photoresponsive agents such as acid generators, crosslinking promoters, surfactants, base components, and fluorine additive components. The resist composition containing organically modified metal oxide nanoparticles may contain two or more of the additives. Even when an additive is added to a solvent containing organically modified metal oxide nanoparticles, the solubility of the organically modified metal oxide nanoparticles in the solvent can be maintained while maintaining high resolution when irradiated with EUV light, and the resist film can exhibit high sensitivity to EUV light.

[0046] An acid generator is a substance that generates an acid by exposure to exposure light, etc. Examples of such acid generators include onium salt-based acid generators such as iodonium salts and sulfonium salts, oxime sulfonate-based acid generators, diazomethane-based acid generators such as bisalkyl or bisaryl sulfonyl diazomethanes and poly(bissulfonyl) diazomethanes, nitrobenzyl sulfonate-based acid generators, iminosulfonate-based acid generators, and disulfone-based acid generators.

[0047] The crosslinking accelerator is a compound that generates an acid or base by light or heat. By further containing the crosslinking accelerator, the resist pattern formability and etching selectivity can be improved. Examples of the crosslinking accelerator include an onium salt compound and an N-sulfonyloxyimide compound.

[0048] The surfactant is a component that acts to improve the coatability, striations, etc. As the surfactant, for example, ionic or non-ionic fluorine-based and / or silicon-based surfactants can be used.

[0049] The base component is a compound that traps the acid generated by exposure (i.e., controls the diffusion of the acid). Examples of the base component include a photodecomposable base that decomposes upon exposure and loses its ability to control acid diffusion, a nitrogen-containing organic compound, and the like.

[0050] The fluorine additive component is a compound that imparts water repellency to the resist film or improves lithography properties. As the component (F), for example, the fluorine-containing polymer compounds described in JP-A-2010-002870, JP-A-2010-032994, JP-A-2010-277043, JP-A-2011-13569, and JP-A-2011-128226 can be used.

[0051] The method for producing organically modified metal oxide nanoparticles according to an embodiment of the present invention includes a reaction step of reacting a metal oxyacetate and / or a metal alkoxide with an acid selected from the group consisting of carboxylic acid, sulfonic acid, and phosphonic acid in a liquid, such as water, methanol, ethanol, propanol, butanol, or acetone.

[0052] An example of a method for producing organically modified metal oxide nanoparticles using a metal alkoxide will be described. A solution of a metal alkoxide is added to two types of carboxylic acids having different structures, and the mixture is stirred as necessary. The resulting precipitate is washed several times with alcohol, filtered, recovered, and dried. In this way, the organically modified metal oxide nanoparticles of this embodiment can be obtained in a simple manner. The metal alkoxide is preferably one or more of zirconium alkoxide, hafnium alkoxide, and titanium alkoxide, and more preferably zirconium alkoxide.

[0053] The organically modified metal oxide nanoparticle-containing resist composition according to the embodiment of the present invention can be prepared by filtering the organically modified metal oxide nanoparticle-containing solution through a membrane filter having a pore size of about 0.1 μm.

[0054] In addition, after dissolving the organically modified metal oxide nanoparticle-containing resist composition according to the embodiment of the present invention in a solvent component, impurities and the like may be removed using a polyimide porous film, a polyamideimide porous film, or the like. For example, the resist composition may be filtered using a filter made of a polyimide porous film, a filter made of a polyamideimide porous film, or a filter made of a polyimide porous film and a polyamideimide porous film. Examples of the polyimide porous film and the polyamideimide porous film include those described in JP 2016-155121 A.

[0055] The pattern forming method according to the embodiment of the present invention includes a film forming step, an exposure step, and a resist pattern forming step. In the film forming step, a resist film is formed on a support using the organically modified metal oxide nanoparticle-containing solution of the present embodiment or the organically modified metal oxide nanoparticle-containing resist composition of the present embodiment. For example, the solution or the resist composition is applied onto the layer to be etched, and dried to obtain a resist film. There is no particular restriction on the type of the layer to be etched. The layer to be etched is not particularly limited, and may be a conventionally known one, for example, a substrate for electronic components or a substrate on which a predetermined wiring pattern is formed. More specifically, examples of the substrate include a silicon wafer, a substrate made of metal such as copper, chromium, iron, or aluminum, and a glass substrate. The support may be a substrate as described above on which an inorganic and / or organic film is provided. Examples of inorganic films include inorganic anti-reflective coatings (inorganic BARC). Examples of organic films include organic anti-reflective coatings (organic BARC) and organic films such as lower organic films in a multi-layer resist method.

[0056] In the exposure step, the resist film is exposed to light. For example, the resist film is irradiated with EUV light in a predetermined pattern. In the development step, the exposed resist film is developed to form a resist pattern. For example, the resist film is immersed in a developer such as butyl acetate, and the portion not irradiated with EUV light is dissolved in the developer and removed to form an etching opening. By using the organically modified metal oxide nanoparticle-containing solution of this embodiment or the organically modified metal oxide nanoparticle-containing resist composition of this embodiment, the line width of the etching mask can be, for example, 20 nm or less. This allows the mask to be thinned, and fine etching of the layer to be etched is possible.

[0057] In the resist pattern forming step, the resist film exposed in the exposure step is developed to form a resist pattern. Examples of the developer used in this development include an alkaline aqueous solution and a developer containing an organic solvent.

[0058] Examples of the alkaline aqueous solution include alkaline aqueous solutions in which at least one of alkaline compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia water, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene is dissolved.

[0059] Examples of the organic solvent in the developer containing an organic solvent include the same organic solvents as those exemplified in the solvent. Among these, preferred are alcohol solvents, amide solvents, ester solvents, ether solvents, ketone solvents, hydrocarbon solvents, and combinations thereof, and butyl acetate is particularly preferred.

[0060] These developers may be used alone or in combination of two or more. After development, the film is generally washed with water and then dried. EXAMPLES

[0061] EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to the following examples.

[0062] Example 1 2.47 mL of propionic acid and 2.78 mL of methacrylic acid were added to the container and mixed until uniform. 4.5 mL of 80 wt% zirconium butoxide 1-butanol solution was slowly added. After sealing, the container was stirred at room temperature until a precipitate formed (1-20 days). The precipitate was washed five times with a minimum amount of n-butanol (3 mL) and vacuum dried. The precipitate was pulverized to obtain a white solid. The white powder was analyzed by NMR (Bruker, device name "AVANCE III 400"), and it was confirmed that the substance amount ratio (so-called molar ratio) of the ligands contained in the powder was propionic acid:methacrylic acid = 33:67 = 3.96:8.04. The analysis by TG-TDA (HITACHI, device name "STA-7200") showed that the weight loss rate was 54.3%. Furthermore, IR analysis of this white powder (Thermo Scientific, instrument name "NICOLET 6700") revealed an absorption peak (1550 cm) derived from the carboxyl group. -1 and 1420cm -1 ) was confirmed.

[0063] 0.15 g of this white powder was dissolved in 5.0 g of PGMEA. Undissolved white powder was removed using centrifugation and a filter with a pore size of 0.2 μm. Dynamic light scattering analysis of the solution after removal (manufactured by Malvern Instruments, device name "Zetasizer Nano S") showed that the volume-based average particle size of this white powder was about 3 nm. From this result, the obtained white powder was an organically modified metal oxide nanoparticle in which propionic acid and methacrylic acid were coordinated to a core composed of zirconium and oxygen.

[0064] The particle size of about 3 nm obtained from the dynamic light scattering analysis was the diameter of the dispersion including the surrounding ligands, so at least a part of the core was not a metal oxide crystal but a cluster in which zirconium atoms were crosslinked with oxygen atoms. The results of single crystal X-ray structure analysis (RIGAKU, equipment name "XtaLAB P200") showed that the cluster was a Zr 6 O 4 (OH) 4 It was confirmed that the two cores with the composition of 1000 and 10000 had a structure cross-linked by a coordinate bond of propionic acid. 2 ) was 45.7%. Based on the above results, the white powder was 2 The converted content is 44.7%, and [Zr 6 O 4 (OH) 4 (C 4 H 5 O 2 ) 8.04 (C 3 H 5 O 2 ) 3.96 ] 2 It was confirmed that. When this corresponds to the above formula (m01), C01, C02, and L01 are respectively as follows. C01 = Zr 6 O 4 (OH) 4 (C 3 H 5 O 2 ) 1.96 (C 4 H 5 O 2 ) 8.04 C02=Zr 6 O 4 (OH) 4 (C 3 H 5 O 2 ) 1.96 (C 4 H 5 O 2 ) 8.04 L01=(C 3 H 5 O2 ) 4 In the formula (m01), M, X, Y, a, b, c, d, and w are each independently Zr and C. 3 H 5 O 2 , Y=C 4 H 5 O 2 , a=1.96, b=8.04, c=1.96, d=8.04, w=4.

[0065] Comparative Example 1 In a glove box, 1.40 g of 85% zirconium butoxide 1-butanol solution was mixed with 1.02 g of methacrylic acid and left to stand for about three weeks to obtain transparent crystals. The results of single crystal X-ray structure analysis (RIGAKU, XtaLAB Synergy-S) showed that the cluster is composed of six zirconium atoms crosslinked with oxygen by covalent bonds, forming Zr 6 O 4 (OH) 4 The Zr has one core with the composition of 6 O 4 (OH) 4 (C 4 H 5 O 2 ) 12 It was confirmed that the crystals had the following structure. The transparent crystals were collected by filtration under reduced pressure, vacuum dried at room temperature for one day, and pulverized to obtain a white powder. Elemental analysis of the white powder revealed that the carbon content was 36 wt%. Thermogravimetric analysis of the white powder revealed that the weight loss rate was 57%.

[0066] In addition, IR analysis of this white powder (Thermo Fisher Scientific, NICOLET 6700) revealed an absorption peak (1558 cm) derived from the carboxyl group of methacrylic acid. -1 ) and the absorption peak of the stretching vibration band of C=C (1647 cm -1 ) and the absorption peak of the out-of-plane bending vibration band of the vinyl group CH (827 cm -1) was confirmed. Furthermore, the result of matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF / MS) of this white powder (manufactured by Bruker, device name "Autoflex Speed") showed the presence of m / z 1702, which matched the molecular weight of zirconia hexamer coordinated with methacrylic acid. From the above, it was confirmed that the obtained white powder was Zr 6 O 4 (OH) 4 (C 4 H 5 O 2 ) 12 It was.

[0067] 0.09 g of this white powder was dissolved in 3.0 g of PGMEA. Undissolved white powder was removed using centrifugation and a filter with a pore size of 0.45 μm. Dynamic light scattering analysis of the solution after removal showed that the volume-based average particle size of this white powder was about 2 nm. From this result, the obtained white powder was an organically modified metal oxide nanoparticle in which methacrylic acid was coordinated to a core composed of zirconium and oxygen.

[0068] (Formation of resist pattern) A resist pattern was formed using the PGMEA solution of the organically modified metal oxide nanoparticles prepared in Example 1 as the resist composition of Example 1, and the PGMEA solution of the organically modified metal oxide nanoparticles prepared in Comparative Example 1 as the resist composition of Comparative Example 1. Each of the resist compositions of Example 1 and Comparative Example 1 was dropped onto a silicon wafer, rotated at 1500 rpm for 60 seconds to form a film, and then heated at 80°C for 60 seconds to obtain a resist film. 2 After this resist film was exposed to EUV at an irradiation dose of 1000 nm (EUV Frame Exposure System EUVES-7000GC, manufactured by LithoTech Japan), it was developed by immersing it in butyl acetate for 30 seconds, and after drying, the film thickness was measured using a spectroscopic ellipsometer (Horiba Jobin Yvon, device name UVISEL) to determine the sensitivity.

[0069] [Table 1]

[0070] As can be seen from the results in Table 1 above, it was confirmed that the resist composition of Example 1 was superior to that of Comparative Example 1 in sensitivity. [Industrial Applicability]

[0071] The organically modified metal oxide nanoparticle-containing resist solution, the organically modified metal oxide nanoparticle-containing resist composition, and the pattern forming method of the present invention have excellent sensitivity and can therefore be suitably used in the manufacture of semiconductor devices, which are expected to become even more miniaturized in the future.

Claims

1. Two or more cores comprising a plurality of Zr atoms and a plurality of oxygen atoms covalently bonded to the plurality of Zr atoms; a first modifying group (A1) that is a carboxylic acid carboxylate ligand coordinated to the core; a second modifying group (A2) that is coordinately bonded to the core and is a carboxylic acid carboxylate ligand having a structure different from that of the first modifying group (A1); having The organically modified metal oxide nanoparticles have a structure in which the cores are crosslinked by coordinate bonds via at least the first modifying group (A1).

2. The organically modified metal oxide nanoparticles according to claim 1 , wherein the first modifying group (A1) is a ligand derived from a compound represented by the following general formula (a01): 【Chemistry 1】 [In the general formula (a01), each R is independently a group selected from the group consisting of an alkyl group having 1 to 18 carbon atoms, an alkoxyalkyl group having 1 to 18 carbon atoms, an alkenyl group having 1 to 18 carbon atoms, an alkenyloxyalkyl group having 1 to 18 carbon atoms, an alkynyl group having 1 to 18 carbon atoms, an alkynyloxyalkyl group having 1 to 18 carbon atoms, an aryl group having 1 to 18 carbon atoms, an aryloxyalkyl group having 1 to 18 carbon atoms, and a cyanoalkyl group having 1 to 18 carbon atoms, or a group in which one or more hydrogen atoms of the above group have been substituted with a substituent. However, the above substituent does not include a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, a phospho group, or a phosphonate group.]

3. The organically modified metal oxide nanoparticles according to claim 1 or 2, which are represented by the following formula (m01): C01-L01-C02...(m01) In the above formula (m01), C01 is M ６ O ４ (OH) ４ [X a Y b ], where 0≦a≦10 and 1≦b≦11. C02 is M ６ O ４ (OH) ４ [X c Y d ], where 0≦c≦10 and 1≦d≦11. L01 is Xw, where w=24-(a+b+c+d) and 2≦w≦12. [M is a Zr atom, X is the first modifying group (A1), and Y is the second modifying group (A2).]

4. An organically modified metal oxide nanoparticle described in any one of claims 1 to 3, wherein the first modifying group (A1) is a ligand derived from propionic acid and the second modifying group (A2) is a ligand derived from methacrylic acid.

5. The organically modified metal oxide nanoparticles according to claim 1, wherein the core is Zr 6 O 4 (OH) 4 .

6. The organically modified metal oxide nanoparticles according to claim 3, wherein, in formula (m01), X in C01 and C02 is C 3 H 5 O 2 , and Y is C 4 H 5 O 2 .

7. 7. A solution containing organically modified metal oxide nanoparticles, comprising the organically modified metal oxide nanoparticles according to claim 1 and a solvent.

8. 7. A resist composition containing organically modified metal oxide nanoparticles, comprising the organically modified metal oxide nanoparticles according to claim 1 and a solvent.

9. forming a resist film on a support using the resist composition containing organically modified metal oxide nanoparticles according to claim 8; exposing the resist film to light; developing the exposed resist film to form a resist pattern; A method for forming a resist pattern comprising the steps of:

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