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 carboxy-containing polymer, 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 improves stochastics and achieves high sensitivity and high resolution. However, this type of metal resist has many issues, including insufficient solubility in resist solvents, storage stability, and defects caused by post-etching residues.

[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 have discovered that a resist composition comprising as its main components a hypervalent iodine compound having a specific carboxylate ligand and a carboxy group-containing polymer 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 carboxy group-containing polymer, 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 1 is a hydrocarbyl group having 1 to 10 carbon atoms which may contain a halogen atom or a heteroatom. R 2is 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 carboxyl group-containing polymer contains a repeating unit represented by the following formula (2): [ka] (In the formula, R A is a hydrogen atom, a halogen atom, a methyl group, or a trifluoromethyl group. X A is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX A1 -X A1 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the saturated hydrocarbylene group may contain at least one bond selected from a hydroxy group, an ether bond, an ester bond, and a lactone ring. * represents a bond to a carbon atom in the main chain. 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 11 and R 12 are each independently a halogen atom or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. 11 and R 12may 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 13 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 13 may be the same or different. 13 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. 10. A laminate comprising a substrate and a resist film on the substrate, wherein the resist film contains a polymer containing a repeating unit represented by the following formula (4): [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 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. 2may 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, provided that *1 and *2 are bonded to adjacent carbon atoms of the aromatic ring. R A is a hydrogen atom, a halogen atom, a methyl group, or a trifluoromethyl group. X A is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX A1 -X A1 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the saturated hydrocarbylene group may contain at least one bond selected from a hydroxy group, an ether bond, an ester bond, and a lactone ring. * represents a bond to a carbon atom in the main chain. 11. The laminate of 10, comprising a resist underlayer film between the substrate and the resist film. 12. A pattern forming method comprising the steps of exposing a resist film of the laminate of either 10 or 11 to high-energy rays, and developing the exposed resist film using a developer. 13. The pattern formation method of 12, wherein the high-energy beam is an electron beam or extreme ultraviolet light. 14. The pattern forming method of 12 or 13, wherein the developer dissolves exposed areas but does not dissolve unexposed areas. 15. The pattern forming method of 12 or 13, 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 carboxy group-containing polymer, 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 1 is 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 2 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; aryl groups having 6 to 40 carbon atoms, such as a phenyl group, a naphthyl group, or an anthracenyl group; or groups obtained by combining these. 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 bonded.

[0022] In formula (1), R 3 is 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 alkanediyl groups having 1 to 10 carbon atoms, such as methanediyl, ethane-1,1-diyl, ethane-1,2-diyl, propane-1,1-diyl, propane-1,2-diyl, propane-1,3-diyl, propane-2,2-diyl, butane-2,3-diyl, butane-1,4-diyl, 2-methylpropane-1,2-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, nonane-1,9-diyl, and decane-1,10-diyl; cyclopentanediyl, cyclohexanediyl, norbornanediyl, adamantanediyl, and tricyclo[5.2.1.0]diyl. 2,6] cyclic saturated hydrocarbylene groups having 3 to 10 carbon atoms, such as a decanediyl group; alkenediyl groups having 2 to 10 carbon atoms, such as a vinylene group or a propenylene 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]

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[0046] [ka]

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[0050] [ka]

[0051] [Carboxy group-containing polymer] The carboxyl group-containing polymer preferably contains a carboxyl group-containing repeating unit, which is preferably represented by the following formula (2): [ka]

[0052] In formula (2), R A is a hydrogen atom, a halogen atom, a methyl group, or a trifluoromethyl group. A is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX A1 -X A1is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the saturated hydrocarbylene group may contain at least one bond selected from a hydroxy group, an ether bond, an ester bond, and a lactone ring. * represents a bond to a carbon atom in the main chain.

[0053] Specific examples of the carboxy group-containing repeating unit include, but are not limited to, the following: A is the same as above. [ka]

[0054] [ka]

[0055] The carboxy group-containing polymer may further contain a repeating unit other than the carboxy group-containing repeating unit (hereinafter also referred to as "other repeating unit"). The other repeating unit is not particularly limited, but is preferably one that can improve the solubility in a solvent of a polymer that is poorly soluble in a solvent when composed solely of a repeating unit having a carboxy group. Preferred examples of such repeating units include repeating units having a hydrocarbyl group having 1 to 20 carbon atoms and optionally containing at least one selected from the group consisting of a halogen atom, a hydroxy group, a cyano group, a carbonyl group, a nitro group, a sulfonic acid group, an amino group, an isocyanate group, an amide bond, an imide bond, an ester bond, an ether bond, a sulfide bond, a carbonate bond, a lactone ring, and a sultone ring.

[0056] Specific examples of the other repeating units include, but are not limited to, those shown below. A is the same as above, and X B are each independently —CH— or —O—. [ka]

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[0078] [ka]

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[0080] [ka]

[0081] [ka]

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[0083] [ka]

[0084] [ka]

[0085] [ka]

[0086] In the carboxyl group-containing polymer, the molar ratio of the carboxyl group-containing repeating units to the other repeating units is preferably 10:90 to 90:10, more preferably 15:85 to 85:15, and even more preferably 20:80 to 80:20.

[0087] The weight average molecular weight (Mw) of the carboxy group-containing polymer is preferably 1,000 to 500,000, more preferably 3,000 to 100,000. In the present invention, Mw is a value measured in terms of polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

[0088] Furthermore, if the carboxyl group-containing polymer has a broad molecular weight distribution (Mw / Mn), the presence of low-molecular-weight and high-molecular-weight polymers may result in the appearance of foreign matter on the pattern after exposure, or the pattern shape may be deteriorated. Therefore, since the effects of Mw and Mw / Mn tend to become greater as the pattern rule becomes finer, in order to obtain a resist composition that is suitable for use with fine pattern dimensions, it is preferable that the carboxyl group-containing polymer have a narrow Mw / Mn distribution of 1.0 to 2.0.

[0089] The carboxyl group-containing polymer can be synthesized, for example, by polymerizing a monomer that provides the repeating unit described above in an organic solvent with the addition of a radical polymerization initiator by heating.

[0090] Specific examples of organic solvents used in the polymerization reaction include toluene, benzene, THF, diethyl ether, dioxane, cyclohexane, cyclopentane, methyl ethyl ketone (MEK), propylene glycol monomethyl ether acetate (PGMEA), and γ-butyrolactone (GBL). Specific examples of the polymerization initiator include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), 1,1'-azobis(1-acetoxy-1-phenylethane), benzoyl peroxide, and lauroyl peroxide. The amount of the polymerization initiator added is preferably 0.01 to 25 mol% based on the total amount of monomers to be polymerized. The reaction temperature is preferably 50 to 150°C, and more preferably 60 to 100°C. The reaction time is preferably 2 to 24 hours, and more preferably 2 to 12 hours from the viewpoint of production efficiency.

[0091] The polymerization initiator may be added to the monomer solution and then fed to the reaction vessel. Alternatively, an initiator solution may be prepared separately from the monomer solution and then fed to the reaction vessel independently. From the perspective of quality control, it is preferable to prepare the monomer solution and the initiator solution independently and then add them dropwise, since radicals generated from the initiator during the waiting time may cause the polymerization reaction to proceed, resulting in the formation of an ultra-high molecular weight polymer. The acid labile group may be used as is after being introduced into the monomer, or may be protected or partially protected after polymerization. To adjust the molecular weight, a known chain transfer agent such as dodecyl mercaptan or 2-mercaptoethanol may be used in combination. In this case, the amount of the chain transfer agent added is preferably 0.01 to 20 mol % of the total amount of monomers to be polymerized.

[0092] The amount of each monomer in the monomer solution may be appropriately set so as to achieve the preferred content ratio of the repeating units described above.

[0093] In the resist composition of the present invention, the hypervalent iodine compound and the carboxyl group-containing polymer are preferably contained in such a molar ratio that the content ratio of the hypervalent iodine compound to the carboxylic acid-containing repeating units in the polymer is 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 carboxyl group-containing polymer may be used alone, or two or more types having different composition ratios, Mw, and / or Mw / Mn may be used in combination.

[0094] [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]

[0095] In formula (3), k is an integer of 0 to 5.

[0096] In formula (3), R 11 and R 12 are each independently a halogen atom or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. 11 and R 12 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. 11 and R 12 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.

[0097] In formula (3), R 13 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; aryl groups having 6 to 40 carbon atoms, such as a phenyl group, a naphthyl group, or an anthracenyl group; or groups obtained by combining these. Furthermore, 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. When k is 2, 3, 4, or 5, each R 13 may be the same or different from each other, and multiple R 13 may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded.

[0098] Other specific examples of hypervalent iodine compounds include, but are not limited to, the following: [ka]

[0099] [ka]

[0100] [ka]

[0101] [ka]

[0102] [ka]

[0103] [ka]

[0104] [ka]

[0105] When the resist composition of the present invention contains another hypervalent iodine compound, the total content ratio of the hypervalent iodine compound represented by Formula (1) and the other hypervalent iodine compound relative to the carboxylic acid-containing repeating unit in the polymer 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 other hypervalent iodine compound is preferably contained in a molar ratio relative to the hypervalent iodine compound represented by Formula (1):hypervalent iodine compound represented by Formula (1) of 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 different types.

[0106] [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), the carboxyl group-containing polymer, 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] As described above, the resist composition of the present invention contains a hypervalent iodine compound and a carboxyl group-containing polymer as main components, but does not contain an acid-labile group-containing base polymer or a photoacid generator, as 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, for example.

[0116] The hypervalent iodine compound represented by formula (1) is a tricoordinate compound with 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, can be mixed with a high-molecular-weight carboxylic acid compound, and the resulting low-boiling acetic acid can be removed to complete the ligand exchange. If the carboxylic acid compound is a polymer, the polymer and the hypervalent iodine compound will bond to form a high-molecular-weight hypervalent iodine compound.

[0117] High molecular weight hypervalent iodine compounds are generated during film formation. This is because even if such high molecular weight hypervalent iodine compounds are synthesized in advance, they are insoluble in many organic solvents, making it impossible to prepare a solution. This is presumably because hypervalent iodine compounds, which have low solvent solubility due to their inherent high polarization, become even less soluble when a high molecular weight carboxylic acid-containing polymer is used as a ligand. Therefore, it is desirable to remove the original low molecular weight carboxylic acid component during film formation and the subsequent baking process to complete the ligand exchange reaction and form a resist film.

[0118] The resist film formed in this manner is presumed to contain a polymer in which a carboxyl group-containing polymer and a hypervalent iodine compound are bonded together, that is, the polymer is presumed to contain a repeating unit represented by the following formula (4): [ka] (In the formula, m, n, R 2 , R 3 , *1, *2, R A , X A is the same as above.)

[0119] The resist film of the present invention thus formed on the substrate undergoes photodecomposition of the hypervalent iodine compound, which is its main component, to change polarity, and a pattern is formed by the development step. By appropriately selecting the developer, either a positive or negative pattern can be formed.

[0120] 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.

[0121] 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, and the hypervalent iodine compound represented by formula (1) contains only one carboxylate ligand capable of undergoing the aforementioned ligand exchange. This prevents crosslinking between polymers during film formation, and polarity change occurs at a lower exposure dose than when other hypervalent iodine compounds are used alone. In other words, these features enable the resist composition of the present invention to achieve high sensitivity, high resolution, and low LWR.

[0122] Metal resists containing metal tin compounds as their main component, which have 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.

[0123] Japanese Patent Publication No. 2015-180928 and Japanese Patent Publication No. 2018-095853 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.

[0124] [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.

[0125] 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.

[0126] 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.

[0127] After exposure, PEB is performed as needed, preferably on a hot plate or in an oven at 30 to 150°C for 10 seconds to 30 minutes, more preferably at 60 to 120°C for 30 seconds to 20 minutes.

[0128] 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 a tetramethylammonium hydroxide solution; 2-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.

[0129] 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.

[0130] 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]

[0131] 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.

[0132] [1] Synthesis of hypervalent iodine compounds [Synthesis Example 1-1] Synthesis of hypervalent iodine compound I-1 [ka]

[0133] A solution of 13.6 g of starting compound SM-1 (iodobenzoic acid) in 40 g of acetonitrile was added dropwise to a solution of 40 g of Oxone (registered trademark) (potassium peroxymonosulfate) dissolved 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 intermediate In-1 as a solid (yield: 11.6 g, 81%). Next, 8 g of In-1 and 27 mL of acetic anhydride were mixed and stirred at 140 °C for 2 hours. The reaction solution was 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 desired hypervalent iodine compound I-1 as a solid (yield: 7.0 g, 5%). Nuclear magnetic resonance spectrum of hypervalent iodine compound I-1 ( 1The results of H-NMR / DMSO-d6 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. Single quadrupole mass spectrometry (ESI): POSITIVE M + H + 307.0 (equivalent to C9H7IO4)

[0134] [Synthesis Example 1-2] Synthesis of hypervalent iodine compound I-2 [ka]

[0135] A hypervalent iodine compound I-2 was synthesized (yield 86%) in the same manner as in Synthesis Example 1-1, except that the starting compound SM-2 was used instead of the starting compound SM-1. Nuclear magnetic resonance spectrum of hypervalent iodine compound I-2 ( 1 The results of H-NMR / DMSO-d6 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. Single quadrupole mass spectrometry (ESI): POSITIVE M + H + 325.0 (equivalent to C9H6FIO4)

[0136] [Synthesis Example 1-3] Synthesis of hypervalent iodine compound I-3 [ka]

[0137] 3.4 g of trichloroisocyanuric acid was added to a solution prepared by dissolving 15 g of the raw material compound SM-3 in 40 g of acetonitrile. After stirring at room temperature for 30 minutes, the precipitated solid was filtered off to obtain intermediate In-3 (yield: 10.6 g, 65%). Next, 8 g of IM-3, 3.3 g of silver acetate, and 100 g of acetonitrile were mixed and stirred at room temperature for 10 hours. The precipitated solid was filtered off. The resulting solid was extracted with acetonitrile, and the extract was evaporated under reduced pressure to give the target hypervalent iodine compound I-3 as a solid (yield: 8.5 g, 100%). Nuclear magnetic resonance spectrum of hypervalent iodine compound I-3 ( 1 The results of H-NMR / CDCl3 and single quadrupole mass spectrometry are shown below. 1 H-NMR (500MHz, CDCl3) δ 2.18 (s, 3H), 7.61-7.79 (m, 3H), 7.93 (d, J=8.4Hz, 1H) ppm. Single quadrupole mass spectrometry (ESI): POSITIVE M + H + 428.9(C 11 H8F6IO3 equivalent)

[0138] [2] Polymer synthesis The monomers used in the synthesis of the polymer are as follows: [ka]

[0139] [ka]

[0140] [ka]

[0141] [Synthesis Example 2-1] Synthesis of Polymer P-1 A monomer-polymerization initiator solution was prepared by placing 56 g of monomer a-1, 105 g of monomer b-1, 5.4 g of V-601 (Fujifilm Wako Pure Chemical Industries, Ltd.), and 180 g of MEK in a flask under a nitrogen atmosphere. 55 g of MEK was placed in a separate flask under a nitrogen atmosphere and heated to 80°C with stirring. The monomer-polymerization initiator solution was then added dropwise over 4 hours. After the addition, the polymerization solution was stirred for 2 hours while maintaining the temperature at 80°C, and then cooled to room temperature. The resulting polymerization solution was added dropwise to 4000 g of vigorously stirred hexane, and the precipitated polymer was filtered. The resulting polymer was washed twice with 1200 g of hexane and then vacuum-dried at 50°C for 20 hours to obtain polymer P-1 as a white powder (yield: 155 g, 96%). The Mw of polymer P-1 was 7700, and the Mw / Mn ratio was 1.82. The Mw is a polystyrene-equivalent value measured by GPC using THF as a solvent. [ka]

[0142] [Synthesis Examples 2-2 to 2-10] Synthesis of Polymers P-2 to P-10 The polymers shown in Table 1 below were synthesized in the same manner as in Synthesis Example 1, except that the types and blending ratios of the respective monomers were changed.

[0143] [Table 1]

[0144] [3] Preparation of resist composition [Examples 1-1 to 1-16, Comparative Examples 1-1 to 1-3] Resist compositions (R-01 to R-16) and a comparative resist composition (CR-01) were prepared by dissolving a hypervalent iodine compound, another hypervalent iodine compound, and a polymer in a solvent containing 0.01% by mass of a surfactant (PF-636, Omnova) according to the compositions shown in Table 2 below, and filtering the resulting solution through a 0.2 μm Teflon (registered trademark) filter. Comparative resist compositions (CR-02 to CR-03) were also prepared by dissolving a polymer, a photoacid generator, and a sensitivity adjuster in a solvent containing 0.01% by mass of a surfactant (PF-636, Omnova) according to the compositions shown in Table 3 below, and filtering the resulting solution through a 0.2 μm Teflon (registered trademark) filter.

[0145] [Table 2]

[0146] [Table 3]

[0147] In Tables 2 and 3, other hypervalent iodine compounds O-1, photoacid generators PAG-1, sensitivity adjusters Q-1 and solvents are as follows.

[0148] [ka]

[0149] [ka]

[0150] [ka]

[0151] Solvent: PGMEA (propylene glycol monomethyl ether acetate) AcOH (acetic acid) HBM (2-hydroxyisobutyric acid methyl ester) PA (propionic acid) GBL (γ-butyrolactone)

[0152] [4] EUV lithography evaluation (line and space pattern, positive tone development) [Examples 2-1 to 2-16, Comparative Examples 2-1 to 2-3] Each resist composition (R-01 to R-16, CR-01 to CR-03) was spin-coated onto a Si substrate coated with a 20 nm thick silicon-containing spin-on hard mask (SHB-A940, manufactured by Shin-Etsu Chemical Co., Ltd.) (43% silicon by mass). The resist was then pre-baked (PAB) for 60 seconds on a hot plate at the temperature listed in Table 4 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 4. Development was then performed for 30 seconds using the developer listed in Table 4 to form an LS pattern with a space width of 18 nm and a pitch of 36 nm.

[0153] The resulting resist patterns were evaluated as follows, and the results are shown in Table 4.

[0154] [Sensitivity evaluation] The LS pattern was observed using a critical dimension 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.

[0155] [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.

[0156] [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.

[0157] [Table 4]

[0158] Developer: nBA (butyl acetate) CHA (cyclohexyl acetate) TMAH (2.38% by mass tetramethylammonium hydroxide aqueous solution)

[0159] [5] EUV lithography evaluation (line and space pattern, negative tone development) [Examples 3-1 to 3-16, Comparative Examples 3-1 to 3-3] Each resist composition (R-1 to R-16, CR-01 to CR-03) was spin-coated onto a Si substrate coated with a 20 nm thick silicon-containing spin-on hard mask (SHB-A940, manufactured by Shin-Etsu Chemical Co., Ltd.) (43% silicon by mass), and then pre-baked (PAB) for 60 seconds using a hot plate at the temperature listed in Table 5 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 a 60 second PEB on a hot plate at the temperature listed in Table 5. Development was then performed for 30 seconds using the developer listed in Table 5 to form an LS pattern with a space width of 18 nm and a pitch of 36 nm.

[0160] The resulting resist patterns were evaluated as follows, and the results are shown in Table 4.

[0161] [Sensitivity evaluation] The LS pattern was observed using a critical dimension 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.

[0162] [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.

[0163] [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.

[0164] [Table 5]

[0165] The results shown in Tables 4 and 5 demonstrate that the resist composition of the present invention exhibits excellent sensitivity, LWR, and resolution in both positive tone and negative tone development when forming a line and space pattern by EUV exposure.

[0166] [6] EUV lithography evaluation (contact hole pattern) [Examples 4-1 to 4-16, Comparative Examples 4-1 to 4-3] Each resist composition (R-01 to R-16, CR-01 to CR-03) was spin-coated onto a Si substrate with a 20 nm thick silicon-containing spin-on hard mask (SHB-A940, manufactured by Shin-Etsu Chemical Co., Ltd.) (43% silicon by mass) and pre-baked (PAB) for 60 seconds at the temperature listed in Table 6 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, wafer dimensions 64 nm pitch, +20% bias hole pattern mask), baked (PEB) for 60 seconds on a hot plate at the temperature listed in Table 6, and developed for 30 seconds using the developer listed in Table 6 to produce a 32 nm hole pattern.

[0167] The resulting resist patterns were evaluated as follows, and the results are shown in Table 6. [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 32 nm was determined. 2 ) was sought.

[0168] [CD Uniformity (CDU) Evaluation] 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.

[0169] [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 for forming 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.

[0170] [Table 6]

[0171] The results shown in Table 6 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 carboxy group-containing polymer, 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 carboxyl group-containing polymer contains a repeating unit represented by the following formula (2): 【Chemistry 2】 (In the formula, R A is a hydrogen atom, a halogen atom, a methyl group, or a trifluoromethyl group. X A represents a single bond, a phenylene group, a naphthylene group, or *-C(=O)-O-X A1 - is. X A1 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the saturated hydrocarbylene group may contain at least one bond selected from a hydroxy group, an ether bond, an ester bond, and a lactone ring. * represents a bond to a carbon atom in the main chain.

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 11 and R 12 are each independently a halogen atom or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. 11 and R 12 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 13 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 13 may be the same or different. 13 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.

10. A laminate comprising a substrate and a resist film on the substrate, wherein the resist film contains a polymer containing a repeating unit represented by the following formula (4): 【Chemistry 4】 (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 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, provided that *1 and *2 are bonded to adjacent carbon atoms of the aromatic ring. R A is a hydrogen atom, a halogen atom, a methyl group, or a trifluoromethyl group. X A represents a single bond, a phenylene group, a naphthylene group, or *-C(=O)-O-X A1 - is. X A1 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the saturated hydrocarbylene group may contain at least one bond selected from a hydroxy group, an ether bond, an ester bond, and a lactone ring. * represents a bond to a carbon atom in the main chain.

11. The laminate according to claim 10 , further comprising a resist underlayer film between the substrate and the resist film.

12. 12. A pattern forming method comprising the steps of: exposing a resist film of the laminate according to claim 10 to high-energy rays; and developing the exposed resist film with a developer.

13. 13. The pattern formation method according to claim 12, wherein the high-energy beam is an electron beam or extreme ultraviolet light.

14. 13. The pattern forming method according to claim 12, wherein the developer dissolves exposed areas but does not dissolve unexposed areas.

15. 13. The pattern forming method according to claim 12, wherein the developer dissolves the unexposed areas but does not dissolve the exposed areas.

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