Resist composition and pattern forming method

Abstract

To provide a non-chemically amplified resist composition excellent in sensitivity and resolution in photolithography using a high-energy ray, and a pattern forming method using the resist composition.SOLUTION: A resist composition comprises a hypervalent iodine compound represented by the formula (1), a carboxylic-acid compound, and a solvent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resist composition and a pattern forming method. [Background technology]

[0002] As the IoT market expands, there is a growing demand for higher integration, higher speeds, and lower power consumption in LSIs, leading to rapid progress in miniaturization of pattern rules. Logic devices, in particular, are driving this miniaturization. The most advanced miniaturization technology is ArF immersion lithography, with double patterning, triple patterning, and quadruple patterning being used to mass-produce 10nm-node devices. Furthermore, studies are underway to develop 7nm-node devices using next-generation extreme ultraviolet (EUV) lithography with a wavelength of 13.5nm.

[0003] As miniaturization progresses, image blurring due to acid diffusion has become a problem (Non-Patent Document 1). It has been suggested that in order to ensure resolution in fine patterns with processing dimensions of 45 nm and below, not only is it important to improve dissolution contrast, as has been proposed in the past, but also to control acid diffusion (Non-Patent Document 2). However, because chemically amplified resist compositions increase sensitivity and contrast through acid diffusion, attempts to minimize acid diffusion by lowering the post-exposure bake (PEB) temperature or shortening the PEB time result in significant decreases in sensitivity and contrast.

[0004] Adding an acid generator that generates bulky acid is effective in suppressing acid diffusion. Therefore, copolymerization of an onium salt acid generator with a polymerizable olefin into a polymer has been proposed. However, for resist film pattern formation with feature sizes of 16 nm or less, it is believed that chemically amplified resist compositions cannot be used to form patterns due to acid diffusion, and the development of non-chemically amplified resist compositions is desired.

[0005] One material for non-chemically amplified resist compositions is polymethyl methacrylate (PMMA), a positive resist material whose main chain is cleaved by EUV irradiation, resulting in a decrease in molecular weight, which improves solubility in organic solvent developers.

[0006] Hydrogen silsesquioxane (HSQ) is a negative resist material that becomes insoluble in alkaline developers due to crosslinking caused by the condensation reaction of silanols generated by EUV irradiation. Chlorine-substituted calixarenes also function as negative resist materials. These negative resist materials have small molecular size before crosslinking and are free of blurring due to acid diffusion, resulting in low edge roughness and extremely high resolution, and are used as pattern transfer materials to indicate the resolution limit of exposure equipment. However, these materials have insufficient sensitivity, and further improvement is needed.

[0007] One of the challenges in developing materials for EUV lithography is the low photon count in EUV exposure. EUV energy is much higher than that of ArF excimer laser light, and the photon count in EUV exposure is one-fourteenth that of ArF exposure. Furthermore, the pattern dimensions formed with EUV exposure are less than half those of ArF exposure. This makes EUV exposure susceptible to variations in photon count. The variations in photon count in the extremely short wavelength radiation region are a physical phenomenon known as shot noise, and this effect cannot be eliminated. Therefore, so-called stochastics has attracted attention. While the effects of shot noise cannot be eliminated, methods for reducing this effect are being discussed. Shot noise not only increases dimensional uniformity (CDU) and line width roughness (LWR), but also causes hole blockage with a probability of one in several million. Blocked holes cause poor electrical conduction, preventing transistor operation and adversely affecting overall device performance. When considering practical sensitivity, resist compositions containing PMMA or HSQ as the main component are significantly affected by stochastics and are unable to achieve the desired resolution performance.

[0008] As a method for reducing the impact of shot noise on the resist side, the introduction of elements that have high absorption of EUV light has attracted attention. Patent Document 1 proposes a chemically amplified resist composition containing iodine atoms that have high absorption of EUV light. However, as mentioned above, chemically amplified resist compositions cannot achieve excellent resolution performance in EUV lithography, where processing dimensions will become increasingly finer in the future.

[0009] Patent Document 2 proposes a negative resist composition using a tin compound. Because this composition contains tin, which has high absorption of EUV light, as its main component, it has improved stochastics and can achieve high sensitivity and high resolution. However, so-called metal resists of this type have many issues, such as insufficient solubility in resist solvents, storage stability, and defects due to post-etching residues. Furthermore, since metal resists are negative resists in which the exposed areas become insoluble in developer solutions by primarily becoming metal oxides, applying them to contact hole patterning requires an additional reversal process, which raises cost concerns.

[0010] In response to this, Patent Document 3 proposes a positive resist composition using a hypervalent iodine compound. Because this composition contains iodine, which has high absorption of EUV light, it has improved stochastics, similar to metal resists, and can achieve high sensitivity and high resolution. Furthermore, because it is composed solely of organic molecules, it can address issues with metal resists, such as developer solubility and defects caused by residues. However, its performance as a resist material is still unsatisfactory, and there is a need for the development of resist materials that are useful for forming even finer patterns. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Publication No. 2018-5224 [Patent Document 2] Special Publication No. 2021-503482 [Patent Document 3] Japanese Patent Application Publication No. 2023-167368 [Non-patent literature]

[0012] [Non-Patent Document 1] SPIE Vol. 5039 p1 (2003) [Non-patent document 2] SPIE Vol. 6520 p65203L-1 (2007) Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resist composition that exhibits excellent sensitivity and resolution in photolithography using high-energy rays, particularly electron beam (EB) lithography and EUV lithography, and a pattern formation method that uses the resist composition. [Means for solving the problem]

[0014] As a result of extensive research into achieving the above-mentioned object, the present inventors discovered that a resist composition containing as its main components a hypervalent iodine compound having a specific carboxylate ligand and a carboxylic acid compound provides a resist film that exhibits extremely high sensitivity and excellent resolution, and is therefore extremely effective for precise microfabrication, which led to the completion of the present invention.

[0015] That is, the present invention provides the following resist composition and pattern forming method. 1. A resist composition comprising a hypervalent iodine compound represented by the following formula (1), a carboxylic acid compound, and a solvent: [ka] (In the formula, m is 0 or 1. When m is 0, n is an integer of 0 to 4, and when m is 1, n is an integer of 0 to 6. R 1is a hydrocarbyl group having 1 to 10 carbon atoms which may contain a halogen atom or a heteroatom. R 2 is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a halogen atom or a heteroatom. When n is 2 or more, each R 2 may be the same or different. 2 may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached. R 3 is a carbonyl group or a hydrocarbylene group having 1 to 10 carbon atoms which may contain a hetero atom. *1 and *2 represent bonds to carbon atoms of the aromatic ring in the formula. However, *1 and *2 are bonded to adjacent carbon atoms of the aromatic ring.) 2. The resist composition of 1, wherein the carboxylic acid compound is represented by the following formula (2): [ka] (In the formula, p is an integer of 1 to 4. R 11 is a p-valent hydrocarbon group having 1 to 40 carbon atoms or a p-valent heterocyclic group having 2 to 40 carbon atoms, and when p is 2, R 11 may be an ether bond, a carbonyl group, an azo group, a thioether bond, a carbonate bond, a carbamate bond, a sulfinyl group, or a sulfonyl group. Some or all of the hydrogen atoms of the p-valent hydrocarbon group or p-valent heterocyclic group may be substituted with a group containing a heteroatom, and some of the -CH2- groups of the p-valent hydrocarbon group may be substituted with a group containing a heteroatom. R 12 is a single bond or a hydrocarbylene group having 1 to 10 carbon atoms, and some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing a hetero atom, or some of the -CH2- of the hydrocarbylene group may be substituted with a group containing a hetero atom. When p is 2, 3, or 4, each R 12 may be the same as or different from each other.) 3. The resist composition of 1 or 2, further comprising a hypervalent iodine compound represented by the following formula (3): [ka] (In the formula, k is an integer of 0 to 5. R 21 and R 22 are each independently a halogen atom or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. 21 and R 22 may be bonded to each other to form a ring together with the carbon atoms to which they are bonded and the atoms between said carbon atoms. R 23 is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a halogen atom or a heteroatom. When k is 2, 3, 4, or 5, each R 23 may be the same or different. 23 may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached.) 4. A laminate comprising a substrate and a resist film formed on the substrate from a resist composition according to any one of 1 to 3. 5. The laminate of 4, further comprising a resist underlayer film between the substrate and the resist film. 6. A pattern forming method comprising the steps of: forming a resist film on a substrate, or on an underlayer film of a substrate having an underlayer film laminated thereon, using the resist composition according to any one of 1 to 3; exposing the resist film to high-energy rays; and developing the exposed resist film using a developer. 7. The pattern formation method according to claim 6, wherein the high-energy beam is an electron beam or extreme ultraviolet light. 8. The pattern forming method according to 6 or 7, wherein the developer dissolves exposed areas but does not dissolve unexposed areas. 9. The pattern forming method according to 6 or 7, wherein the developer dissolves the unexposed areas but does not dissolve the exposed areas. [Effects of the Invention]

[0016] The resist composition of the present invention achieves both high sensitivity and high resolution, and is extremely useful for forming fine patterns, particularly in EB lithography and EUV lithography. DETAILED DESCRIPTION OF THE INVENTION

[0017] [Resist composition] The resist composition of the present invention comprises a hypervalent iodine compound having a specific carboxylate ligand, a carboxylic acid compound, and a solvent.

[0018] [Hypervalent iodine compounds] The hypervalent iodine compound is a three-coordinate hypervalent iodine compound represented by the following formula (1). [ka]

[0019] In formula (1), m is 0 or 1. When m is 0, n is an integer of 0 to 4, and when m is 1, n is an integer of 0 to 6. n is preferably 0, 1, 2, 3, or 4, more preferably 0, 1, 2, or 3, even more preferably 0, 1, or 2, and most preferably 0 or 1.

[0020] In formula (1), R 1is a hydrocarbyl group having 1 to 10 carbon atoms which may contain a halogen atom or a heteroatom. Specific examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The hydrocarbyl group having 1 to 10 carbon atoms may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 10 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, and an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, and a tricyclo[5.2.1.0 2,6 ] cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as a decanyl group or an adamantyl group; alkenyl groups having 2 to 10 carbon atoms, such as a vinyl group or an allyl group; aryl groups having 6 to 10 carbon atoms, such as a phenyl group or a naphthyl group; and groups obtained by combining these. In addition, some or all of the hydrogen atoms in the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms, nitrogen atoms, or halogen atoms, and some of the -CH2- groups in the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms, or nitrogen atoms, resulting in the hydrocarbyl groups containing hydroxy groups, cyano groups, halogen atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonate ester bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic anhydrides (-C(=O)-OC(=O)-), etc. 1 As the alkyl group, a hydrocarbyl group having 1 to 4 carbon atoms or a fluorinated hydrocarbyl group having 1 to 4 carbon atoms is preferred, and a hydrocarbyl group having 1 to 4 carbon atoms is more preferred.

[0021] In formula (1), R 2is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a halogen atom or a heteroatom. Specific examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The hydrocarbyl group having 1 to 40 carbon atoms may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 40 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, and an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, and a tricyclo[5.2.1.0 2,6 ] cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms, such as a decanyl group, an adamantyl group, or an adamantylmethyl group; and aryl groups having 6 to 40 carbon atoms, such as a phenyl group, a naphthyl group, or an anthracenyl group. In addition, some or all of the hydrogen atoms in the hydrocarbyl group may be substituted with a group containing a heteroatom, such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- in the hydrocarbyl group may be substituted with a group containing a heteroatom, such as an oxygen atom, a sulfur atom, or a nitrogen atom, so that the hydrocarbyl group may contain a hydroxy group, a cyano group, a halogen atom, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), or the like. When n is 2 or more, each R 2 may be the same or different. 2 may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached.

[0022] In formula (1), R 3is a carbonyl group or a hydrocarbylene group having 1 to 10 carbon atoms which may contain a heteroatom. The hydrocarbylene group having 1 to 10 carbon atoms may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkylene groups having 1 to 10 carbon atoms, such as methanediyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, propane-1,3-diyl group, propane-2,2-diyl group, butane-2,3-diyl group, butane-1,4-diyl group, 2-methylpropane-1,2-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, and decane-1,10-diyl group; cyclopentanediyl group, cyclohexanediyl group, norbornanediyl group, adamantanediyl group, and tricyclo[5.2.1.0]diyl group. 2,6 ]Cyclic saturated hydrocarbylene groups having 3 to 10 carbon atoms, such as a decanediyl group; alkenylene groups having 2 to 10 carbon atoms, such as a vinylene group or a propynylene group; arylene groups having 6 to 10 carbon atoms, such as a phenylene group, a methylphenylene group, an ethylphenylene group, an n-propylphenylene group, an isopropylphenylene group, an n-butylphenylene group or a naphthylene group; and groups obtained by combining these. In addition, some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- groups of the hydrocarbylene group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in the hydrocarbylene group containing a hydroxy group, a cyano group, a halogenated alkyl group, a halogen atom, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), or the like. 3 is preferably a carbonyl group, a hydrocarbylene group having 1 to 4 carbon atoms, or a fluorinated hydrocarbylene group having 1 to 4 carbon atoms.

[0023] In formula (1), *1 and *2 represent bonds to the carbon atoms of the aromatic ring in the formula. However, *1 and *2 are bonded to adjacent carbon atoms of the aromatic ring. The combinations of *1, *2, and m can have the following four patterns: [ka] (where n, R 2 and R 3 The dashed line indicates R 1 -C(=O)-O- represents a bond.)

[0024] Specific examples of the hypervalent iodine compound represented by formula (1) include, but are not limited to, the following: In the following formula, Me is a methyl group. [ka]

[0025] [ka]

[0026] [ka]

[0027] [ka]

[0028] [ka]

[0029] [ka] [ka]

[0030]

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[0031]

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[0032]

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[0033]

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[0034]

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[0035]

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[0036]

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[0037]

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[0038]

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[0039]

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[0040]

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[0041]

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[0042]

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[0043]

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[0044]

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[0045]

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[0046]

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[0047]

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[0048]

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[0049]

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[0050]

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[0051] [Kuronic acid compound] The carboxylic acid compound used in the present invention may be any carboxylic acid compound generally defined in organic chemistry, but is preferably one represented by the following formula (2). [ka]

[0052] In formula (2), p is an integer of 1 to 4. 11 is a p-valent hydrocarbon group having 1 to 40 carbon atoms or a p-valent heterocyclic group having 2 to 40 carbon atoms, and when p is 2, R 11 may be an ether bond, a carbonyl group, an azo group, a thioether bond, a carbonate bond, a carbamate bond, a sulfinyl group, or a sulfonyl group. In addition, some or all of the hydrogen atoms of the p-valent hydrocarbon group or p-valent heterocyclic group may be substituted with a group containing a heteroatom, and some of the -CH2- of the p-valent hydrocarbon group may be substituted with a group containing a heteroatom. R 12 is a single bond or a hydrocarbylene group having 1 to 10 carbon atoms, and some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing a hetero atom, or some of the -CH2- of the hydrocarbylene group may be substituted with a group containing a hetero atom. When p is 2, 3, or 4, each R 12 may be the same as or different from each other.

[0053] R 11 The p-valent hydrocarbon group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. The p-valent hydrocarbon group is a group obtained by eliminating p hydrogen atoms from a hydrocarbon. Specific examples of the hydrocarbon include alkanes having 1 to 40 carbon atoms, alkenes having 2 to 40 carbon atoms, alkynes having 2 to 40 carbon atoms, saturated cyclic hydrocarbons having 3 to 40 carbon atoms, unsaturated cyclic hydrocarbons having 3 to 40 carbon atoms, and aromatic hydrocarbons having 6 to 40 carbon atoms.

[0054] Specific examples of the alkanes having 1 to 40 carbon atoms include methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, and structural isomers thereof.

[0055] Specific examples of the alkenes having 1 to 40 carbon atoms include ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, decene, and structural isomers thereof.

[0056] Specific examples of the alkyne having 1 to 40 carbon atoms include acetylene, propyne, butyne, pentyne, hexyne, heptyne, octyne, nonyne, decyne, and structural isomers thereof.

[0057] Specific examples of the cyclic saturated hydrocarbon having 3 to 40 carbon atoms include cyclopropane, cyclobutane, cyclohexane, cycloheptane, cyclooctane, adamantane, and norbornane.

[0058] Specific examples of the cyclic unsaturated hydrocarbon having 3 to 40 carbon atoms include cyclopropene, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, and norbornene.

[0059] Specific examples of the aromatic hydrocarbon having 6 to 40 carbon atoms include benzene, naphthalene, and biphenyl.

[0060] R 11 The p-valent heterocyclic group represented by the following formula is a group obtained by eliminating p hydrogen atoms from a heterocyclic compound. Examples of the heterocyclic compound include furan, pyridine, pyrazole, and thiazolidine.

[0061] The p-valent hydrocarbon group or p-valent heterocyclic group may have some or all of its hydrogen atoms substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and as a result, may contain a hydroxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. The m-valent hydrocarbon group may have some of its -CH- groups substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, may contain a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), etc.

[0062] R 12The hydrocarbylene group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a nonane-1,9-diyl group, a decane-1,10-diyl group, an undecane-1,11-diyl group, a dodecane-1,1 alkanediyl groups having 1 to 20 carbon atoms, such as a 2-diyl group; cyclic saturated hydrocarbylene groups having 3 to 20 carbon atoms, such as a cyclopentanediyl group, a cyclohexanediyl group, a norbornanediyl group, and an adamantanediyl group; unsaturated aliphatic hydrocarbylene groups having 2 to 20 carbon atoms, such as a vinylene group and a propene-1,3-diyl group; arylene groups having 6 to 20 carbon atoms, such as a phenylene group and a naphthylene group; and groups obtained by combining these. In addition, some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, or some of the -CH- constituting the hydrocarbylene group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbylene group may contain a hydroxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride or the like.

[0063] Of the carboxylic acid compounds represented by formula (2), those in which p is 2, 3, or 4 are preferred. In this case, when mixed with a hypervalent iodine compound, a strong resist film with a high molecular weight is easily formed, which is preferred from the viewpoints of etching resistance and developer resistance.

[0064] Specific examples of the carboxylic acid compound include, but are not limited to, the following: [ka]

[0065] [ka]

[0066] [ka]

[0067] [ka]

[0068] [ka]

[0069] [ka]

[0070] In the resist composition of the present invention, the molar ratio of the hypervalent iodine compound to the carboxylic acid compound is preferably hypervalent iodine compound:carboxylic acid compound=10:90 to 90:10, more preferably 20:80 to 80:20, and even more preferably 30:70 to 70:30. The hypervalent iodine compound may be used alone, or two or more types may be used in combination. The carboxylic acid compound may be used alone, or two or more types may be used in combination.

[0071] [Other hypervalent iodine compounds] The resist composition of the present invention may contain a hypervalent iodine compound represented by the following formula (3) (hereinafter also referred to as other hypervalent iodine compounds). By adding the other hypervalent iodine compounds, the reactivity to light can be controlled and the sensitivity can be adjusted. [ka]

[0072] In formula (3), k is an integer of 0 to 5.

[0073] In formula (3), R 21 and R 22 are each independently a halogen atom or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. 21 and R 22 may be bonded to each other to form a ring together with the carbon atoms to which they are bonded and the atoms between the carbon atoms. Specific examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The hydrocarbyl group having 1 to 10 carbon atoms may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 10 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, and an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, and a tricyclo[5.2.1.0 2,6 ] cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as a decanyl group or an adamantyl group; alkenyl groups having 2 to 10 carbon atoms, such as a vinyl group or an allyl group; aryl groups having 6 to 10 carbon atoms, such as a phenyl group or a naphthyl group; and groups obtained by combining these. In addition, some or all of the hydrogen atoms in the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms, nitrogen atoms, or halogen atoms, and some of the -CH2- groups in the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms, or nitrogen atoms, resulting in the hydrocarbyl groups containing hydroxy groups, cyano groups, halogen atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonate ester bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic anhydrides (-C(=O)-OC(=O)-), etc. 21 and R22 As the alkyl group, a hydrocarbyl group having 1 to 4 carbon atoms or a fluorinated hydrocarbyl group having 1 to 4 carbon atoms is preferred, and a hydrocarbyl group having 1 to 4 carbon atoms is more preferred.

[0074] In formula (3), R 23 is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a halogen atom or a heteroatom. Specific examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The hydrocarbyl group having 1 to 40 carbon atoms may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 40 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, and an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, and a tricyclo[5.2.1.0 2,6 ] cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms, such as a decanyl group, an adamantyl group, or an adamantylmethyl group; and aryl groups having 6 to 40 carbon atoms, such as a phenyl group, a naphthyl group, or an anthracenyl group. Furthermore, some or all of the hydrogen atoms in the hydrocarbyl group may be substituted with a group containing a heteroatom, such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- groups in the hydrocarbyl group may be substituted with a group containing a heteroatom, such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in the hydrocarbyl group containing a hydroxy group, a cyano group, a halogen atom, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, or a carboxylic anhydride (-C(=O)-OC(=O)-). When k is 2, 3, 4, or 5, each R 23 may be the same or different from each other, and multiple R 23may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached.

[0075] Other specific examples of hypervalent iodine compounds include, but are not limited to, the following: [ka]

[0076] [ka]

[0077] [ka]

[0078] [ka]

[0079] [ka]

[0080] [ka]

[0081] [ka]

[0082] When the resist composition of the present invention contains other hypervalent iodine compounds, the molar ratio of the total of the hypervalent iodine compound represented by Formula (1) and the other hypervalent iodine compounds to the carboxylic acid compound is preferably 10:90 to 90:10, more preferably 20:80 to 80:20, and even more preferably 30:70 to 70:30. Furthermore, the molar ratio of the hypervalent iodine compound represented by Formula (1) to the other hypervalent iodine compounds is preferably 1:99 to 99:1, more preferably 1:99 to 50:50. The other hypervalent iodine compounds may be used singly or in combination of two or more.

[0083] [solvent] The resist composition of the present invention contains a solvent. The solvent is not particularly limited as long as it can dissolve the hypervalent iodine compound represented by formula (1), a carboxylic acid compound, other hypervalent iodine compounds, and other components described below and can form a film. Such a solvent is preferably an organic solvent, and specific examples thereof include ketones such as cyclohexanone, methyl-2-n-pentyl ketone, and methyl isoamyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, diacetone alcohol, 4-methyl-2-pentanol, and methyl 2-hydroxyisobutyrate; propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether; Examples of suitable solvents include ethers such as propylene glycol dimethyl ether and diethylene glycol dimethyl ether; esters such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol mono tert-butyl ether acetate; carboxylic acids such as formic acid, acetic acid, and propionic acid; lactones such as γ-butyrolactone; and mixed solvents thereof.

[0084] The content of the solvent in the resist composition of the present invention is preferably an amount such that the solids concentration in the resist composition is 0.1 to 20 mass%, more preferably 0.1 to 15 mass%, and even more preferably 0.1 to 10 mass%. In the present invention, the term "solids" refers collectively to all components of the resist composition other than the solvent. The solvents may be used alone or in combination of two or more.

[0085] The resist composition of the present invention may further contain a surfactant. The surfactant is preferably a fluorine-based and / or silicone-based surfactant. Specific examples of such surfactants include those described in paragraph

[0276] of U.S. Patent Application Publication No. 2008 / 0248425. Furthermore, surfactants other than the fluorine-based and / or silicone-based surfactants described in paragraph

[0280] of U.S. Patent Application Publication No. 2008 / 0248425 may also be used.

[0086] When the resist composition of the present invention contains the surfactant, the content thereof is preferably 0.0001 to 2 mass % of the total solid content. The surfactant may be used alone or in combination of two or more.

[0087] The resist composition of the present invention may further contain at least one selected from a radical scavenger and a crosslinking agent, which makes it possible to control the photoreaction during photolithography and adjust the sensitivity.

[0088] Specific examples of the radical scavenger include hindered phenols, quinones, hindered amines, and thiol compounds. Specific examples of the hindered phenols include dibutylhydroxytoluene and 2,2'-methylenebis(4-methyl-6-tert-butylphenol). Specific examples of the quinones include 4-methoxyphenol (methoquinone) and hydroquinone. Specific examples of the hindered amines include 2,2,6,6-tetramethylpiperidine and 2,2,6,6-tetramethylpiperidine-N-oxy radical. Specific examples of the thiols include dodecanethiol and hexadecanethiol.

[0089] When the resist composition of the present invention contains the radical scavenger, the content thereof is preferably 0.01 to 10 mass % of the total solid content. The radical scavenger may be used alone or in combination of two or more.

[0090] Specific examples of the crosslinking agent include compounds having a carbon-carbon unsaturated bond as a functional group, such as a vinyl group, a (meth)acrylate group, an allyl group, an alkynyl group, or an aromatic ring. Specific examples of compounds having a vinyl group include linear alkenes, branched alkenes, and cyclic alkenes, which may have a substituent. Specific examples of compounds having a (meth)acrylate group include acrylic acid, methacrylic acid, acrylic acid esters, and methacrylic acid esters, which may have a substituent. Specific examples of compounds having an allyl group include allyl alcohol, allyl ether, allyl ester, allyl amide, allyl amine, and allyl group-containing isocyanurates, which may have a substituent. Specific examples of compounds having an alkynyl group include linear alkynes, branched alkynes, cyclic alkynes, alkynyl alcohols, alkynyl ethers, alkynyl esters, alkynyl amides, alkynyl amines, and alkynyl group-containing isocyanurates, which may have a substituent. Specific examples of compounds having an aromatic ring include arenes, heteroarenes, styrene, stilbene, phenylacetylene, acenaphthylene, chalcone, and the like, which may have a substituent. The crosslinking agent may have only one or more of the functional groups. The number of functional groups contained in the crosslinking agent is preferably 1 to 10, and more preferably 2 to 8.

[0091] When the resist composition of the present invention contains the crosslinking agent, the content thereof is preferably 0.01 to 50 mass % of the total solid content. The crosslinking agents may be used alone or in combination of two or more.

[0092] As described above, the resist composition of the present invention contains a hypervalent iodine compound and a carboxylic acid compound as main components, but does not contain an acid-labile group-containing base polymer or a photoacid generator, which are contained in conventional chemically amplified resist compositions. However, the resist composition of the present invention, particularly upon exposure to EB or EUV, generates a difference in solubility between the exposed and unexposed areas, making it possible to form positive or negative patterns. The mechanism behind this is not completely clear, but is presumed to be as follows.

[0093] The hypervalent iodine compound represented by formula (1) is a tricoordinate compound containing a carboxylate ligand. When such a tricoordinate iodine compound is mixed with a carboxylic acid compound, an exchange of the carboxylate ligand is thought to occur via an equilibrium reaction. If the original carboxylate ligand can be removed in some way, a hypervalent iodine compound with a new ligand is generated. For example, 1-acetoxy-1,2-benziodoxol-3-(1H)-one, a relatively readily available hypervalent iodine compound, is mixed with a high-molecular-weight carboxylic acid compound, and the resulting low-boiling acetic acid is removed to complete the ligand exchange. A sufficiently large molecular weight ligand can form a robust resist film. In particular, using a carboxylic acid compound with multiple carboxy groups (e.g., a dicarboxylic acid compound) is thought to be able to form a high-molecular-weight polyester structure containing the hypervalent iodine compound, ensuring film-forming properties and sufficient developer resistance.

[0094] Such a bond between a hypervalent iodine compound and a carboxylic acid compound is generated during film formation. That is, by removing the low-molecular-weight carboxylic acid component generated during film formation and the subsequent baking step, the ligand exchange reaction is completed and a resist film is formed.

[0095] The resist film obtained from the resist composition of the present invention has extremely low organic solvent solubility. This is presumably due to the iodine compound, which has a high polarization. However, it is presumed that this compound becomes soluble in organic solvents when decomposed by light, and a positive pattern can be formed by organic solvent development. On the other hand, the resist film becomes insoluble in an alkaline aqueous solution upon exposure, and therefore a negative pattern can be formed by alkaline aqueous solution development. Furthermore, if the photodecomposition product is a low-molecular-weight component, it is possible to remove the exposed portion by volatilization, i.e., patterning can be performed without using a developer.

[0096] Based on the above speculation, it can be said that the resist composition of the present invention is a non-chemically amplified resist composition. Unlike conventional chemically amplified resist compositions, the resist composition of the present invention does not require an acid labile group-containing base polymer or a photoacid generator, and therefore does not suffer from adverse effects due to acid diffusion (e.g., image blurring), making it possible to resolve fine patterns.

[0097] The resist composition of the present invention is particularly effective in EUV lithography. This is because the resist composition of the present invention contains iodine atoms with high absorption capacity for EUV light. Furthermore, the hypervalent iodine compound represented by formula (1) contains only one carboxylate ligand capable of undergoing the aforementioned ligand exchange. Therefore, crosslinking by carboxylic acid does not occur during film formation, and polarity change occurs at a lower exposure dose than when other hypervalent iodine compounds are used alone. These features enable the resist composition of the present invention to achieve high sensitivity, high resolution, and low LWR. Furthermore, the resulting decomposition product, iodide, is expected to have low volatility (a molecular weight that does not volatilize in vacuum during EB or EUV exposure) due to the presence of a carboxyl group, preventing contamination of optical systems due to outgassing during exposure, as occurs with conventional resist compositions.

[0098] Metal resists containing metal tin compounds as their main component, which have a high absorption capacity for EUV light similar to that of iodine atoms, have been reported as resist compositions for EUV lithography capable of forming fine patterns (e.g., Patent Document 2). However, as mentioned above, such metal resists have many problems, such as insufficient solubility in solvents, poor storage stability, and defects due to post-etching residues caused by the presence of metal elements. On the other hand, the resist composition of the present invention does not contain metal elements, making it more advantageous than metal resists in terms of defects and also has no issues with solvent solubility. Furthermore, the resist composition of the present invention can be applied to both positive-tone and negative-tone resists, thereby offering a wide range of uses. For example, in the contact hole formation process, metal resists developed using negative-tone development require a reversal process step after pillar pattern formation, whereas positive-tone resists do not require such a step. Therefore, from the perspective of process simplicity, the resist composition of the present invention can be said to be more useful than metal resists.

[0099] Japanese Patent Publication No. 2015-180928 and Japanese Patent Publication No. 2018-95853 describe resist compositions containing a hypervalent iodine compound as an additive and resist compositions incorporating a hypervalent iodine compound into the polymer backbone of a base polymer. However, these patent documents only describe the ability of the resist compositions to improve line edge roughness, and make no mention of the possibility of the hypervalent iodine compound undergoing photodecomposition or functioning as a material for a non-chemically amplified resist composition. Furthermore, according to the descriptions of the blending amounts and specific examples, the hypervalent iodine compound is not the main component. Patent Document 3 also proposes a positive resist composition using a hypervalent iodine compound, but does not describe the hypervalent iodine compound represented by Formula (1) of the present invention, nor does it mention the improvement in sensitivity or resolution that can be achieved by using such a compound. Therefore, these patent documents are unlikely to suggest a non-chemically amplified resist composition, such as the present invention, that exhibits extremely high sensitivity, excellent resolution, and is extremely effective for precise microfabrication. In other words, it can be said that the present invention provides a clearly novel resist composition and patterning method.

[0100] [Pattern formation method] When the resist composition of the present invention is used in the manufacture of various integrated circuits, known lithography techniques can be applied. For example, a pattern formation method can include a method comprising the steps of forming a resist film on a substrate using the resist composition, exposing the resist film to high-energy rays, and, if necessary, developing the exposed resist film using a developer.

[0101] First, the resist composition of the present invention is applied to a substrate for integrated circuit manufacturing, or to a substrate having a laminated underlayer film (e.g., Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflective coating), or to a substrate for mask circuit manufacturing, or to a substrate having a laminated underlayer film (e.g., CrO, CrON, MoSi2, SiO2), by a suitable coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, or doctor coating, to a coating thickness of 0.01 to 2 μm. This is then prebaked on a hot plate, preferably at 60 to 200°C for 10 seconds to 30 minutes, more preferably at 80 to 180°C for 30 seconds to 20 minutes, to form a resist film. The underlayer film refers to a film formed between the substrate and the resist film in a multilayer resist process. The underlayer film is not particularly limited, and conventionally known underlayer films can be used.

[0102] Next, the resist film is exposed to high-energy radiation. Examples of the high-energy radiation include ultraviolet radiation, far ultraviolet radiation, EB, EUV, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation. When ultraviolet radiation, far ultraviolet radiation, EUV, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation are used as the high-energy radiation, the exposure dose is preferably 1 to 300 mJ / cm, either directly or using a mask for forming a desired pattern. 2 approximately, more preferably 10 to 200 mJ / cm 2 When EB is used as the high energy beam, the exposure dose is preferably 0.1 to 2000 μC / cm 2 directly or using a mask for forming a desired pattern. 2 approximately, more preferably 0.5 to 1500 μC / cm 2 The resist composition of the present invention is particularly suitable for fine patterning using high-energy rays such as EB or EUV.

[0103] After exposure, PEB is performed as needed, preferably on a hot plate or in an oven at 30 to 120°C for 10 seconds to 30 minutes, more preferably at 60 to 100°C for 30 seconds to 20 minutes.

[0104] After exposure or PEB, the film is developed with a developer as needed to form a pattern. Examples of the developer include an alkaline aqueous solution such as tetramethylammonium hydroxide solution; n-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, isopropyl alcohol, isoamyl alcohol, n-butanol, n-pentanol, cyclohexanol, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butenyl acetate, isopentyl acetate, cyclohexyl acetate, propyl formate, butyl formate, isobutyl formate, and formic acid. Examples of organic solvents that can be used include pentyl, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonate, ethyl crotonate, methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, ethyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, 2-phenylethyl acetate, 2-propanol, 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, diacetone alcohol, and 4-methyl-2-pentanol. These developers may be used alone or in combination of two or more.

[0105] After development, rinsing is performed as necessary. A preferred rinsing solution is a solvent that is miscible with the developer but does not dissolve the resist film. Examples of such solvents that are preferably used include alcohols having 3 to 10 carbon atoms, ether compounds having 8 to 12 carbon atoms, alkanes, alkenes, alkynes, and aromatic solvents having 6 to 12 carbon atoms. Alternatively, water may be used as a rinsing solution instead of an organic solvent.

[0106] Rinsing can reduce the occurrence of resist pattern collapse and defects. Rinsing is not always necessary, and not performing rinsing can reduce the amount of solvent used. [Example]

[0107] The present invention will be specifically explained below by showing synthesis examples, examples and comparative examples, but the present invention is not limited to the following examples.

[0108] [1] Synthesis of hypervalent iodine [Synthesis Example 1] Synthesis of hypervalent iodine compound I-1 (1) Synthesis of Compound In-1 [ka]

[0109] A solution of 13.6 g of iodobenzoic acid in 40 g of acetonitrile was added dropwise to a solution of 40 g of Oxone (registered trademark) (potassium peroxymonosulfate) in 40 g of water at room temperature. After the addition, the mixture was stirred for 2 hours, and the precipitated solid was filtered off. The resulting solid was washed with 40 mL of water, then with 40 mL of acetone, and dried under reduced pressure at 40°C to obtain the target compound In-1 as a solid (yield: 11.6 g, 81%). Nuclear magnetic resonance spectrum of compound In-1 ( 1 The results of H-NMR / DMSO-d6) are shown below. 1H-NMR (500MHz, DMSO-d6) δ 7.73 (m,1H), 7.87 (d, J=8.3Hz, 1H), 7.96 (m, 1H), 8.05 (dd, J=8.2, 1.3Hz, 1H), 8.10 (s, 1H) ppm.

[0110] (2) Synthesis of hypervalent iodine compound I-1 [ka]

[0111] After mixing 8 g of compound In-1 and 27 mL of acetic anhydride, the mixture was stirred at 140°C for 2 hours, and the reaction mixture was returned to room temperature. The precipitated solid was filtered off. The resulting solid was washed with diisopropyl ether and dried under reduced pressure at 40°C to obtain the target hypervalent iodine compound I-1 as a solid (yield: 7.0 g, 75%). Nuclear magnetic resonance spectrum of hypervalent iodine compound I-1 ( 1 The results of H-NMR / DMSO-d6), IR spectrum and single quadrupole mass spectrometry are shown below. 1 H-NMR (500MHz, DMSO-d6) δ 2.25 (s, 3H), 7.75 (m, 1H), 7.78 (m, 1H), 8.05 (m, 2H) ppm. IR (D-ATR): ν= 3306, 3108, 3071, 1661, 1584, 1571, 1476, 1446, 1367, 1261, 1240, 1126, 1013, 921, 826, 808, 755, 691, 675, 648, 608, 544, 499, 475, 450cm -1 Single quadrupole mass spectrometry (ESI): POSITIVE M + H + 307.0 (equivalent to C9H7IO4)

[0112] [Synthesis Example 2] Synthesis of hypervalent iodine compound I-2 (1) Synthesis of compound In-2 [ka]

[0113] A solution of 5 g of 5-methyliodobenzoic acid in 40 g of acetonitrile was added dropwise to a solution of 15 g of oxone in 20 g of water at room temperature. After the addition, the mixture was stirred for 4 hours, and the precipitated solid was filtered off. The resulting solid was washed with 40 mL of water, then with 40 mL of acetone, and dried under reduced pressure at 40 °C to obtain the target compound In-2 as a solid (yield: 4.2 g, 79%). Nuclear magnetic resonance spectrum of compound In-2 ( 1 The results of H-NMR / DMSO-d6) are shown below. 1 H-NMR (500MHz, DMSO-d6) δ 7.73 (m, 1H), 7.87 (d, J=8.3Hz, 1H), 7.96 (m, 1H), 8.05 (dd, J=8.2, 1.3Hz, 1H), 8.10 (s, 1H) ppm.

[0114] (2) Synthesis of hypervalent iodine compound I-2 [ka]

[0115] After mixing 3.4 g of compound In-2 and 15 mL of acetic anhydride, the mixture was stirred at 140°C for 2 hours. The reaction mixture was then returned to room temperature and the precipitated solid was filtered off. The resulting solid was washed with diisopropyl ether and dried under reduced pressure at 40°C to obtain the target hypervalent iodine compound I-2 as a solid (yield: 3.8 g, 97%). Nuclear magnetic resonance spectrum of hypervalent iodine compound I-2 ( 1 The results of H-NMR / DMSO-d6), IR spectrum and single quadrupole mass spectrometry are shown below. 1H-NMR (500MHz, DMSO-d6) δ 2.37 (s, 3H), 2.53 (s, 3H), 7.68 (m, 1H), 7.80 (m, 1H), 7.92 (m, 1H) ppm. IR(D-ATR): ν= 3072, 2961, 1707, 1589, 1476, 1441, 1378, 1293, 1523, 1212, 1187, 1165, 1142, 1118, 1074, 1055, 998, 978, 956, 788, 752, 738, 683, 653, 529, 517, 504 cm -1 . Single quadrupole mass spectrometry (ESI): POSITIVE M + H + 538.9(C 10 (equivalent to H9IO4)

[0116] [Synthesis Example 3] Synthesis of hypervalent iodine compound I-3 (1) Synthesis of compound In-3 [ka]

[0117] A solution of 6 g of 6-fluoroiodobenzoic acid in 40 g of acetonitrile was added dropwise to a solution of 17 g of oxone in 20 g of water at room temperature. After the addition, the mixture was stirred for 4 hours, and the precipitated solid was filtered off. The resulting solid was washed with 40 mL of water, then with 40 mL of acetone, and dried under reduced pressure at 40 °C to obtain the target compound In-3 as a solid (yield: 5.3 g, 85%). Nuclear magnetic resonance spectrum of compound In-3 ( 1 H-NMR, 19 The results of F-NMR / DMSO-d6) measurement are shown below. 1 H-NMR (500MHz, DMSO-d6) δ 7.52 (dd, J=10.2, 8.3, 1H), 7.72 (d, J=8.3Hz, 1H), 7.90 (m, 1H), 8.25 (s, 1H) ppm. 19F-NMR (470MHz, DMSO-d6) δ -114.2 ppm.

[0118] (2) Synthesis of hypervalent iodine compound I-3 [ka]

[0119] After mixing 5.3 g of compound In-3 and 20 mL of acetic anhydride, the mixture was stirred at 140°C for 2 hours, and the reaction mixture was returned to room temperature. The precipitated solid was filtered off. The resulting solid was washed with diisopropyl ether and dried under reduced pressure at 40°C to obtain the target hypervalent iodine compound I-3 as a solid (yield: 5.2 g, 86%). Nuclear magnetic resonance spectrum of hypervalent iodine compound I-3 ( 1 H-NMR, 19 The results of F-NMR / DMSO-d6), IR spectrum and single quadrupole mass spectrometry are shown below. 1 H-NMR (500MHz, DMSO-d6) δ 2.21 (s, 3H), 7.61 (m, 1H), 7.72 (d, J=8.2Hz, 1H), 7.95 (d, J=4.2Hz, 1H) ppm. 19 F-NMR (470MHz, DMSO-d6) δ -111.3 ppm. IR(D-ATR): ν= 3094, 2931, 2426, 1688, 1638, 1593, 1575, 1455, 1437, 1370, 1336, 1300, 1246, 1100, 1058, 1025, 983, 934, 861, 803, 692, 680, 668, 615, 576, 501, 472 cm -1 . Single quadrupole mass spectrometry (ESI): POSITIVE M + H + 325.0 (equivalent to C9H6FIO4)

[0120] [Synthesis Example 4] Synthesis of hypervalent iodine compound I-4 (1) Synthesis of compound In-4 [ka]

[0121] A solution of 10 g of 5-fluoroiodobenzoic acid in 40 g of acetonitrile was added dropwise to a solution of 27 g of oxone in 40 g of water at room temperature. After the addition, the mixture was stirred for 4 hours, and the precipitated solid was filtered off. The resulting solid was washed with 40 mL of water, then with 40 mL of acetone, and dried under reduced pressure at 40 °C to obtain the target compound In-4 as a solid (yield: 8.8 g, 83%). Nuclear magnetic resonance spectrum of compound In-4 ( 1 H-NMR, 19 The results of F-NMR / DMSO-d6) measurement are shown below. 1 H-NMR (500MHz, DMSO-d6) δ 7.76 (dd, J=8.3, 2.6Hz, 1H), 7.80 (m, 2H), 8.21 (s, 1H) ppm. 19 F-NMR (470MHz, DMSO-d6) δ -112.8 ppm.

[0122] (2) Synthesis of Compound I-4 [ka]

[0123] After mixing 8.8 g of compound In-4 and 30 mL of acetic anhydride, the mixture was stirred at 140°C for 2 hours, and the reaction mixture was returned to room temperature. The precipitated solid was filtered off. The resulting solid was washed with diisopropyl ether and dried under reduced pressure at 40°C to obtain the target hypervalent iodine compound I-4 as a solid (yield: 9.2 g, 91%). The nuclear magnetic resonance spectrum of the hypervalent iodine compound I-4 ( 1 H-NMR, 19 The results of F-NMR / DMSO-d6), IR spectrum and single quadrupole mass spectrometry are shown below. 1H-NMR (500MHz, DMSO-d6) δ 2.21 (s, 3H), 7.64-7.96 (m, 3H) ppm. 19 F-NMR (470MHz, DMSO-d6) δ -111.8 ppm. IR(D-ATR): ν= 3098, 3070, 2933, 1697, 1681, 1635, 1584, 1457, 1424, 1370, 1295, 1263, 1234, 1197, 1130, 1100, 1088, 1013, 919, 887, 845, 786, 777, 681, 608, 537, 507 cm -1 . Single quadrupole mass spectrometry (ESI): POSITIVE M + H + 325.0 (equivalent to C9H6FIO4)

[0124] [Synthesis Example 5] Synthesis of hypervalent iodine I-5 (1) Synthesis of Compound In-5 [ka]

[0125] A solution of 27.8 g of 3,4-difluoroiodobenzoic acid in 100 g of acetonitrile was added dropwise to a solution of 25.6 g of oxone in 40 g of water at room temperature. After the addition, the mixture was stirred for 4 hours, and the precipitated solid was filtered off. The resulting solid was washed with 60 mL of water, then with 60 mL of acetone, and dried under reduced pressure at 40 °C to obtain the target compound In-5 as a solid (yield: 21.8 g, 74%). Nuclear magnetic resonance spectrum of compound In-5 ( 1 H-NMR, 19 The results of F-NMR / DMSO-d6) measurement are shown below. 1 H-NMR (500MHz, DMSO-d6) δ 7.76 (dd, J=8.3, 2.6Hz, 1H), 7.80 (m, 2H), 8.21 (s, 1H) ppm. 19F-NMR (470MHz, DMSO-d6) δ -132.7, -138.6 ppm.

[0126] (2) Synthesis of hypervalent iodine compound I-5 [ka]

[0127] After mixing 12.3 g of compound In-5 and 30 mL of acetic anhydride, the mixture was stirred at 140°C for 2 hours, and the reaction mixture was returned to room temperature. The precipitated solid was filtered off. The resulting solid was washed with diisopropyl ether and dried under reduced pressure at 40°C to obtain the target hypervalent iodine compound I-5 as a solid (yield: 9.8 g, 70%). Nuclear magnetic resonance spectrum of hypervalent iodine compound I-5 ( 1 H-NMR, 19 The results of F-NMR / DMSO-d6), IR spectrum and single quadrupole mass spectrometry are shown below. 1 H-NMR (500MHz, DMSO-d6) δ 2.24 (s, 3H), 7.90 (m, 1H), 8.05 (m, 1H) ppm. 19 F-NMR (470MHz, DMSO-d6) δ -122.7, -130.6 ppm. IR(D-ATR): ν= 3100, 3073, 3055, 1761, 1682, 1659, 1644, 1602, 1486, 1413, 1367, 1325, 1283, 1231, 1090, 1046, 1021, 951, 912, 882, 825, 805, 779, 770, 679, 662, 507, 607, 578, 499, 449 cm -1 . Single quadrupole mass spectrometry (ESI): POSITIVE M + H + 343.0 (equivalent to C9H6F2IO4)

[0128] [2] Preparation of resist composition [Examples 1-1 to 1-18, Comparative Examples 1-1 to 1-4] Resist compositions (R-01 to R-18) and a comparative resist composition (CR-01) were prepared by dissolving a hypervalent iodine compound and a carboxylic acid compound in a solvent according to the compositions shown in Table 1 below, and filtering the resulting solution through a 0.2 μm Teflon (registered trademark) filter. Comparative resist compositions (CR-02 to CR-04) were also prepared by mixing a base polymer, a photoacid generator, a sensitivity adjuster, a solvent, and 0.01 mass% of a surfactant (PF-636, manufactured by Omnova) according to the compositions shown in Table 2 below, and filtering the resulting solution through a 0.2 μm Teflon (registered trademark) filter.

[0129] [Table 1]

[0130] [Table 2]

[0131] In Table 1, the hypervalent iodine compound (O-1), carboxylic acid compounds (CA-1 to CA-10), and solvents are as follows. [ka]

[0132] [ka]

[0133] Solvent: PGMEA (propylene glycol monomethyl ether acetate) AcOH (acetic acid) GBL (γ-butyrolactone)

[0134] In Table 2, the base polymer (P-1), photoacid generators (PAG-1, PAG-2) and sensitivity adjusters (Q-1, Q-2) are as follows. [ka]

[0135] [ka]

[0136] [ka]

[0137] [3] EUV lithography evaluation (line and space patterns) [Examples 2-1 to 2-18, Comparative Examples 2-1 to 2-4] Each resist composition (R-01 to R-18, CR-01 to CR-04) was spin-coated onto a Si substrate coated with a 20 nm thick silicon-containing spin-on hard mask SHB-A940 (43% silicon by mass) manufactured by Shin-Etsu Chemical Co., Ltd., and pre-baked (PAB) for 60 seconds at the temperature listed in Table 3 to produce a 40 nm thick resist film. A 36 nm line-and-space (LS) 1:1 pattern was exposed using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9, 90-degree dipole illumination), followed by PEB for 60 seconds on a hot plate at the temperature listed in Table 3. Development was then performed for 30 seconds using the developer listed in Table 3 to form an LS pattern with a space width of 18 nm and a pitch of 36 nm. In Examples 2-2, 2-3, and 2-7, the pattern was formed by PEB, and therefore development using a developer was not performed.

[0138] The resulting resist patterns were evaluated as follows, and the results are shown in Table 3.

[0139] [Sensitivity evaluation] The LS pattern was observed using a length measurement SEM (CG-6300) manufactured by Hitachi High-Tech Corporation, and the optimum exposure dose Eop (mJ / cm) for obtaining an LS pattern with a space width of 18 nm and a pitch of 36 nm was determined. 2 ) was calculated and used as the sensitivity.

[0140] [LWR rating] The LS pattern obtained by irradiation with the optimum exposure dose was measured at 10 points in the longitudinal direction of the space width using a critical dimension SEM (CG-6300) manufactured by Hitachi High-Tech Corporation, and the LWR was calculated as three times the standard deviation (σ) (3σ). The smaller this value, the less roughness and the more uniform the space width pattern obtained.

[0141] [Limiting resolution evaluation] The limiting line width (nm) that can be resolved when forming a pattern by gradually increasing the exposure dose from the optimum exposure dose at which the LS pattern is formed was determined using a critical dimension SEM (CG-6300) manufactured by Hitachi High-Technologies Corporation, and this was taken as the limiting resolution (nm). The smaller this value, the better the limiting resolution, indicating that a finer pattern can be formed.

[0142] [Table 3]

[0143] Developer: nBA (butyl acetate) TMAH (2.38% by mass tetramethylammonium hydroxide aqueous solution)

[0144] The results shown in Table 3 demonstrate that the resist composition of the present invention is excellent in sensitivity, LWR, and resolution when forming an LS pattern by EUV exposure.

[0145] [4] EUV lithography evaluation (contact hole pattern) [Examples 3-1 to 3-18, Comparative Examples 3-1 to 3-4] Each resist composition (R-01 to R-18, CR-01 to CR-04) was spin-coated onto a Si substrate on which a 20 nm-thick silicon-containing spin-on hard mask SHB-A940 (43% silicon by mass) manufactured by Shin-Etsu Chemical Co., Ltd. had been formed. The substrate was then pre-baked (PAB) for 60 seconds at the temperature listed in Table 4 using a hot plate to produce a 50 nm-thick resist film. The resist film was then exposed to light using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadruple-pole illumination, a hole pattern mask with a 64 nm pitch on the wafer and a +20% bias). PEB was performed on a hot plate for 60 seconds at the temperature listed in Table 4, and development was performed for 30 seconds using the developer listed in Table 4 to obtain a 32 nm hole pattern. In Examples 3-2, 3-3, and 3-7, the patterns were formed by PEB, and therefore development using a developer was not performed.

[0146] The resulting resist patterns were evaluated as follows, and the results are shown in Table 4.

[0147] [Sensitivity evaluation] The contact hole pattern was observed using a length measuring SEM (CG-6300) manufactured by Hitachi High-Tech Corporation, and the optimum exposure dose Eop (mJ / cm) for obtaining a hole pattern with a dimension of 22 nm was determined. 2 ) was calculated and used as the sensitivity.

[0148] [CDU Rating] The dimensions of 50 hole patterns obtained by irradiation with the optimal exposure dose were measured, and the CDU was calculated as three times the standard deviation (σ). The smaller this value, the more uniform the hole diameter pattern obtained.

[0149] [Limiting resolution evaluation] The limiting hole diameter (nm) that can be resolved when forming a hole pattern by gradually decreasing the exposure dose from the optimum exposure dose required to form the hole pattern was determined using a critical dimension SEM (CG-6300) manufactured by Hitachi High-Technologies Corporation, and this was taken as the limiting resolution (nm). The smaller this value, the better the limiting resolution, indicating that a pattern with a finer hole diameter can be formed.

[0150] [Table 4]

[0151] The results shown in Table 4 demonstrate that the resist composition of the present invention is excellent in sensitivity, CDU, and resolution when forming a contact hole pattern by EUV exposure.

Claims

1. A resist composition comprising a hypervalent iodine compound represented by the following formula (1), a carboxylic acid compound, and a solvent: 【Chemical 1】 (In the formula, m is 0 or 1. When m is 0, n is an integer of 0 to 4, and when m is 1, n is an integer of 0 to 6. R 1 is a hydrocarbyl group having 1 to 10 carbon atoms which may contain a halogen atom or a heteroatom. R 2 is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a halogen atom or a heteroatom. When n is 2 or more, each R 2 may be the same or different. 2 may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached. R 3 is a carbonyl group or a hydrocarbylene group having 1 to 10 carbon atoms which may contain a heteroatom. *1 and *2 represent bonds to carbon atoms of the aromatic ring in the formula. However, *1 and *2 are bonded to adjacent carbon atoms of the aromatic ring.)

2. 2. The resist composition according to claim 1, wherein the carboxylic acid compound is represented by the following formula (2): 【Chemistry 2】 (wherein p is an integer of 1 to 4. R 11 is a p-valent hydrocarbon group having 1 to 40 carbon atoms or a p-valent heterocyclic group having 2 to 40 carbon atoms, and when p is 2, R 11 may be an ether bond, a carbonyl group, an azo group, a thioether bond, a carbonate bond, a carbamate bond, a sulfinyl group, or a sulfonyl group. In addition, some or all of the hydrogen atoms of the p-valent hydrocarbon group or the p-valent heterocyclic group may be substituted with a group containing a hetero atom, and the -CH 2 A portion of - may be substituted with a group containing a hetero atom. R 12 represents a single bond or a hydrocarbylene group having 1 to 10 carbon atoms, and some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing a hetero atom, and the —CH 2 When p is 2, 3, or 4, each R 12 may be the same as or different from each other.)

3. 2. The resist composition according to claim 1, further comprising a hypervalent iodine compound represented by the following formula (3): 【Chemistry 3】 (wherein k is an integer from 0 to 5. R 21 and R 22 are each independently a halogen atom or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. 21 and R 22 may be bonded to each other to form a ring together with the carbon atoms to which they are bonded and the atoms between said carbon atoms. R 23 is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a halogen atom or a heteroatom. When k is 2, 3, 4, or 5, each R 23 may be the same or different. 23 may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded.)

4. A laminate comprising a substrate and a resist film formed on the substrate from the resist composition according to any one of claims 1 to 3.

5. The laminate according to claim 4 , further comprising a resist underlayer film between the substrate and the resist film.

6. 4. A pattern forming method comprising the steps of: forming a resist film on a substrate, or on an underlayer film of a substrate having an underlayer film laminated thereon, using the resist composition according to claim 1; exposing the resist film to high-energy rays; and developing the exposed resist film using a developer.

7. 7. The pattern forming method according to claim 6, wherein the high-energy beam is an electron beam or extreme ultraviolet light.

8. 7. The pattern forming method according to claim 6, wherein the developer dissolves the exposed area but does not dissolve the unexposed area.

9. 7. The pattern forming method according to claim 6, wherein the developer dissolves the unexposed areas but does not dissolve the exposed areas.

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