Resist composition, laminate, and pattern formation method

Abstract

This invention provides a non-chemically amplified resist composition that exhibits excellent sensitivity and resolution in photolithography using high-energy rays, as well as a pattern formation method using the resist composition. [Solution] A resist composition comprising a hypervalent iodine compound represented by formula (1), a carboxyl group-containing compound, and a solvent. TIFF2026086143000141.tif46166 (In the formula, R 11 R is a hydrocarbyl group having 1 to 10 carbon atoms, which may contain a halogen atom or a heteroatom. 21 X is a C1-C40 hydrocarbyl group which may contain a halogen atom or a heteroatom. 31 Or it is S. 31 This is a hydrocarbyl group which may contain a hydrogen atom, a halogen atom, or a heteroatom.

Description

[Technical Field]

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

[0002] With the expansion of the IoT market, there is an increasing demand for higher integration, higher speed, and lower power consumption in LSIs, leading to rapid miniaturization of pattern rules. Logic devices, in particular, are driving this miniaturization. As cutting-edge miniaturization technology, mass production of 10nm node devices is underway using double, triple, and quadruple patterning in ArF immersion lithography, and further research is progressing on 7nm node devices using next-generation 13.5nm extreme ultraviolet (EUV) lithography.

[0003] As miniaturization progresses, image blurring due to acid diffusion has become a problem (Non-Patent Literature 1). To ensure resolution in fine patterns with processing dimensions of 45 nm or more, it has been suggested that controlling acid diffusion is important, in addition to improving the dissolution contrast as has been conventionally proposed (Non-Patent Literature 2). However, since chemically amplified resist compositions increase sensitivity and contrast through acid diffusion, if acid diffusion is suppressed to the extreme by lowering the post-exposure bake (PEB) temperature or shortening the PEB time, sensitivity and contrast decrease significantly.

[0004] Adding an acid generator that produces bulky acids to suppress acid diffusion is effective. Therefore, copolymerizing an onium salt acid generator with a polymerizable olefin into a polymer has been proposed. However, for pattern formation of resist films with processing dimensions of 16 nm or more, chemically amplified resist compositions are considered insufficient from the standpoint of acid diffusion, and the development of non-chemically amplified resist compositions is desired.

[0005] Polymethyl methacrylate (PMMA) is an example of a material for non-chemically amplified resist compositions. PMMA is a positive-type resist material in which the main chain is cleaved by EUV irradiation, reducing its molecular weight and improving its solubility in organic solvents and developers.

[0006] Hydrogen silsesquioxane (HSQ) is a negative-type resist material that becomes insoluble in alkaline developers due to crosslinking caused by the condensation reaction of silanols induced by EUV irradiation. Chlorine-substituted calixarenes also function as negative-type resist materials. These negative-type resist materials have small molecular sizes before crosslinking and do not blur due to acid diffusion, resulting in low edge roughness and very high resolution. They are used as pattern transfer materials to demonstrate the resolution limit of exposure equipment. However, these materials have insufficient sensitivity and require further improvement.

[0007] One factor that makes material development for EUV lithography difficult is the low number of photons in EUV exposure. The energy of EUV is far higher than that of ArF excimer laser light, and the number of photons in EUV exposure is 1 / 14th of that of ArF exposure. Furthermore, the dimensions of patterns formed by EUV exposure are less than half those of ArF exposure. For this reason, EUV exposure is susceptible to variations in the number of photons. Variations in the number of photons in the ultrashort wavelength synchrotron radiation region are a physical phenomenon called shot noise, and this effect cannot be eliminated. For this reason, so-called stochastics is attracting attention. Although the effect of shot noise cannot be eliminated, how to reduce this effect is being discussed. In addition to increasing dimensional uniformity (CDU) and line width roughness (LWR) due to the effect of shot noise, a phenomenon of hole blockage has been observed with a probability of one in several million. When holes are blocked, it results in poor electrical conductivity and the transistor does not operate, so it negatively affects the overall performance of the device. When considering practical sensitivity, resist compositions primarily composed of PMMA or HSQ are significantly affected by stochastics and have not been able to achieve the desired resolution performance.

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

[0009] Patent Document 2 proposes a negative-type resist composition using a tin compound. Because it mainly consists of tin, which has high absorption of EUV light, its stochastics are improved, enabling high sensitivity and high resolution. However, so-called metal resists of this type have many problems, such as insufficient solubility in resist solvents, storage stability, and defects due to etching residue.

[0010] In contrast, Patent Document 3 proposes a positive-type resist composition using a hypervalent iodine compound. Because it contains iodine elements that have high absorption of EUV light, it improves stochastics similar to metal resists, enabling high sensitivity and high resolution. Furthermore, since it is composed only of organic molecules, it can improve upon the problems of metal resists, such as developer solubility and defects caused by residue. However, its performance as a resist material is still not satisfactory, and there is a need to develop resist materials that are useful for forming even finer patterns. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2018-5224 [Patent Document 2] Special Publication No. 2021-503482 [Patent Document 3] Japanese Patent 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) [Overview of the project] [Problems that the invention aims to solve]

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

[0014] To solve the above problems, the present invention provides a resist composition characterized by comprising a hypervalent iodine compound represented by the following formula (1), a carboxyl group-containing compound, and a solvent. [ka] (In the formula, a1 is 0, 1, or 2. When a1 is 0, b1 is 0, 1, 2, 3, or 4; when a1 is 1, b1 is 0, 1, 2, 3, 4, 5, or 6; and when a1 is 2, b1 is 0, 1, 2, 3, 4, 5, 6, 7, or 8. R 11 Each of these is independently a C1-C10 hydrocarbyl group which may contain a halogen atom or a heteroatom. 21 Each of these is a hydrocarbyl group having 1 to 40 carbon atoms, which may each contain a halogen atom or a heteroatom. When b1 is 2 or more, each R 21 These may be the same or different from each other, and there may be multiple R 21 However, they may bond with each other to form a ring with the carbon atoms of the aromatic ring to which they are bonded. X is a nitrogen atom or a sulfur atom, and in the case of a nitrogen atom, R 31 It may have R 31is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hydrogen atom, a halogen atom, or a hetero atom.)

[0015] For such a resist composition of the present invention, in photolithography using high energy rays, particularly in EB lithography and EUV lithography, it is excellent in sensitivity and resolution.)

[0016] In this case, it is preferable that the carboxy group-containing compound is either or both of a polymer containing a repeating unit represented by the following formula (2) and a compound represented by the following formula (3). [Chemical formula] (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)-O-X 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 a hydroxy group, an ether bond, an ester bond or a lactone ring. * represents a bond to a carbon atom of the main chain. p is 1, 2, 3 or 4. R 41 is a p-valent hydrocarbon group having 1 to 40 carbon atoms or a p-valent heterocyclic group having 2 to 40 carbon atoms. When p is 2, R 41 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. Also, 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 hetero atom, and some of the -CH2- of the p-valent hydrocarbon group may be substituted with a group containing a hetero atom. R 42 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, and 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 R42 They may be the same or different from each other.

[0017] As the carboxyl group-containing compound included in the resist composition of the present invention, such polymers or monomolecular compounds are preferred.

[0018] The above resist composition may further include at least one hypervalent iodine compound represented by the following formula (4) or (5). [ka] (In the formula, m1 and m2 are integers between 0 and 2, and n1 is an integer between 0 and 4 when m1 is 0, an integer between 0 and 6 when m1 is 1, and an integer between 0 and 8 when m1 is 2. When m2 is 0, n2 is an integer between 1 and 3, and n3 is an integer between 0 and 5, satisfying 1 ≤ (n2 + n3) ≤ 6. When m2 is 1, n2 is an integer between 1 and 3, and n3 is an integer between 0 and 7, satisfying 1 ≤ (n2 + n3) ≤ 8. When m2 is 2, n2 is an integer between 1 and 3, and n3 is an integer between 0 and 9, satisfying 1 ≤ (n2 + n3) ≤ 10. R 51 R is a C1-C10 hydrocarbyl group which may contain a halogen atom or a heteroatom. 52 This is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a halogen atom or a heteroatom. When n1 is 2 to 8, each R 52 These may be the same or different from each other. Also, multiple Rs 52 However, they may bond with each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded. 53 This is a C1-C10 hydrocarbylene group, which may contain heteroatoms. *3 and *4 represent the bonds with the carbon atoms of the aromatic ring in the formula. However, *3 and *4 are bonded to adjacent carbon atoms of the aromatic ring. 61 and R 62 Each of these is independently a C1-C10 hydrocarbyl group which may contain a halogen atom or a heteroatom. 61 and R 62However, they may bond with each other to form a ring with the carbon atoms to which they are bonded and the atoms between the carbon atoms. When n2 is 2 to 3, each R 61 and R 62 These may be identical or different from each other. 63 This is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a halogen atom or a heteroatom. When n3 is 2 to 9, each R 63 These may be the same or different from each other. Also, multiple Rs 63 However, they may bond with each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded.

[0019] As the hypervalent iodine compound further included in the resist composition of the present invention, a three-coordinate hypervalent iodine compound represented by the above formula is preferred. When such a three-coordinate iodine(III) compound having an aryl group and a carboxylate ligand is mixed with a carboxyl group-containing compound, similar to the hypervalent iodine compound represented by formula (1) above, the exchange of the compound and the carboxylate ligand is more likely to occur in an equilibrium reaction. At this time, by removing the original carboxylate ligand from the reaction system, the equilibrium is shifted in the direction of generating a hypervalent iodine compound having a new ligand, and ligand exchange proceeds. In this way, a polymer is formed in which the carboxyl group-containing compound is crosslinked by the hypervalent iodine compound. Polymerization proceeds more preferably by further including at least one of the hypervalent iodine compounds represented by formula (4) or (5) above.

[0020] Furthermore, the present invention provides a laminate characterized by comprising a substrate and a resist film which is a film formed of the above-mentioned resist composition on the substrate.

[0021] A laminate comprising a resist film obtained from the resist composition of the present invention exhibits high sensitivity and excellent limiting resolution in the resist film formed from the resist composition described above, making it effective for precise microfabrication. Furthermore, it can be applied to both positive and negative pattern formation, thus offering a wide range of applications and high utility in resist process technology.

[0022] In this case, a further resist underlayer film may be provided between the substrate and the resist film. Furthermore, it is preferable that the resist film contains ligand exchange reaction products between the hypervalent iodine compound and the carboxyl group-containing compound.

[0023] The laminate of the present invention can be configured in such an embodiment as needed.

[0024] Furthermore, the present invention provides a pattern forming method characterized by comprising the steps of: forming a resist film on a substrate or on a resist underlayer of a substrate having a resist underlayer laminated on it using the above-mentioned resist composition; exposing the resist film with high-energy rays; and developing the exposed resist film using a developer.

[0025] The pattern formation method of the present invention is useful for forming even finer patterns because it uses a resist composition with excellent sensitivity and resolution in photolithography using high-energy beams, particularly electron beam (EB) lithography and EUV lithography.

[0026] In this case, it is preferable to use i-rays, KrF excimer laser light, ArF excimer laser light, electron beams, or extreme ultraviolet light as the high-energy beam.

[0027] The pattern formation method of the present invention enables the formation of finer patterns by using such high-energy rays.

[0028] In the pattern formation method of the present invention, the developing solution can be one that dissolves the exposed areas but not the unexposed areas, or one that dissolves the unexposed areas but not the exposed areas.

[0029] The pattern formation method of the present invention can form positive or negative patterns by appropriately selecting a developer, and can therefore be widely applied to the formation of various fine patterns. [Effects of the Invention]

[0030] The resist composition of the present invention is extremely useful in forming fine patterns, particularly in EB lithography and EUV lithography, as it achieves both high sensitivity and high resolution. [Modes for carrying out the invention]

[0031] As a result of diligent research to achieve the above objective, the present inventors have discovered that a resist composition mainly composed of a predetermined hypervalent iodine compound and a carboxyl group-containing compound (polymer or monomolecule compound) provides a resist film that exhibits extremely high sensitivity and excellent resolving power, and is extremely effective for precise microfabrication, leading to the present invention.

[0032] In other words, the present invention is a resist composition characterized by comprising a hypervalent iodine compound represented by the following formula (1), a carboxyl group-containing compound, and a solvent. [ka] (In the formula, a1 is 0, 1, or 2. When a1 is 0, b1 is 0, 1, 2, 3, or 4; when a1 is 1, b1 is 0, 1, 2, 3, 4, 5, or 6; and when a1 is 2, b1 is 0, 1, 2, 3, 4, 5, 6, 7, or 8. R 11 Each of these is independently a C1-C10 hydrocarbyl group which may contain a halogen atom or a heteroatom. 21 Each of these is a hydrocarbyl group having 1 to 40 carbon atoms, which may each contain a halogen atom or a heteroatom. When b1 is 2 or more, each R 21 These may be the same or different from each other, and there may be multiple R 21 However, they may bond with each other to form a ring with the carbon atoms of the aromatic ring to which they are bonded. X is a nitrogen atom or a sulfur atom, and in the case of a nitrogen atom, R 31 It may have R 31 This is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a hydrogen atom, a halogen atom, or a heteroatom.

[0033] The present invention will be described in detail below, but is not limited thereto. In this specification, the description of a numerical range by its endpoints includes all values ​​within that range (for example, "0 to 3" includes 0, 1, 2, and 3).

[0034] [Resist composition] The resist composition of the present invention comprises a predetermined hypervalent iodine compound, a carboxyl group-containing compound, and a solvent as its main components. A carboxyl group is an atomic group (functional group) having the structure "-C(=O)OH".

[0035] [Hypervalent iodine compounds] The essential hypervalent iodine compound in this invention is a three-coordinate hypervalent iodine compound represented by the following formula (1). [ka] (In the formula, a1 is 0, 1, or 2. When a1 is 0, b1 is 0, 1, 2, 3, or 4; when a1 is 1, b1 is 0, 1, 2, 3, 4, 5, or 6; and when a1 is 2, b1 is 0, 1, 2, 3, 4, 5, 6, 7, or 8. R 11 Each of these is independently a C1-C10 hydrocarbyl group which may contain a halogen atom or a heteroatom. 21 Each of these is a hydrocarbyl group having 1 to 40 carbon atoms, which may each contain a halogen atom or a heteroatom. When b1 is 2 or more, each R 21 These may be the same or different from each other, and there may be multiple R 21 However, they may bond with each other to form a ring with the carbon atoms of the aromatic ring to which they are bonded. X is a nitrogen atom or a sulfur atom, and in the case of a nitrogen atom, R 31 It may have R 31 This is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a hydrogen atom, a halogen atom, or a heteroatom.

[0036] In formula (1), a1 is an integer between 0 and 2, and b1 is an integer between 0 and 4 when a1 is 0, an integer between 0 and 6 when a1 is 1, and an integer between 0 and 8 when a1 is 2. b1 is preferably between 0 and 8, more preferably between 0 and 6, even more preferably between 0 and 4, even more preferably between 0 and 2, and most preferably between 0 or 1. Note that the aromatic ring when a1 is 0 is a benzene ring.

[0037] In formula (1), R 11 This is a C1-C10 hydrocarbyl group which may contain halogen atoms or heteroatoms. Specific examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms. The C1-C10 hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C10 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl groups; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0 2,6Examples include cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as decanyl groups and adamantyl groups; alkenyl groups having 2 to 10 carbon atoms, such as vinyl groups and allyl groups; aryl groups having 6 to 10 carbon atoms, such as phenyl groups and naphthyl groups; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the -CH2- groups of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, the group may contain hydroxyl groups, cyano groups, halogen atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic acid anhydrides (-C(=O)-OC(=O)-), etc. 11 Preferably, the group is a hydrocarbyl group having 1 to 4 carbon atoms or a fluorinated hydrocarbyl group having 1 to 4 carbon atoms, and more preferably a hydrocarbyl group having 1 to 4 carbon atoms.

[0038] In formula (1), R 21 This is a C1-C40 hydrocarbyl group which may contain a halogen atom or a heteroatom. Specific examples of the halogen atom include fluorine, chlorine, bromine, and iodine atoms. The C1-C40 hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C40 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl groups; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0 2,6Examples include cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms, such as decanyl groups, adamantyl groups, and adamantylmethyl groups; and aryl groups having 6 to 40 carbon atoms, such as phenyl groups, naphthyl groups, and anthracenyl groups. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the -CH2- of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, it may contain hydroxyl groups, cyano groups, halogen atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic acid anhydrides (-C(=O)-OC(=O)-), etc. When b1 is 2 or more, each R 21 These may be the same or different from each other. Also, multiple Rs 21 However, they may bond with each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded. Also, R 21 The above formula allows for the substitution of any position in the aromatic ring.

[0039] In formula (1), R 31 This is a C1-C20 hydrocarbyl group which may contain hydrogen atoms, halogen atoms, or heteroatoms. The C1-C20 hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C20 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0 2,6Examples include cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as decanyl groups, adamantyl groups, and adamantylmethyl groups; alkenyl groups having 2 to 20 carbon atoms, such as vinyl groups and propenyl groups; aryl groups having 6 to 20 carbon atoms, such as phenyl groups, methylphenyl groups, ethylphenyl groups, n-propylphenyl groups, isopropylphenyl groups, n-butylphenyl groups, and naphthyl groups; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the -CH2- of the hydrocarbyl group may be substituted with a group containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, it may contain a hydroxyl group, a cyano group, an alkyl halide, a halogen atom, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-OC(=O)-), etc. 31 Preferably, the hydrogen atom, methyl group, phenyl group, naphthyl group, or other C1-C10 hydrocarbyl group or C1-C10 fluorinated hydrocarbyl group are used.

[0040] Specific examples of hypervalent iodine compounds represented by formula (1) are listed below, but are not limited to these. In the formula below, Me represents a methyl group. [ka]

[0041] [ka]

[0042] [ka]

[0043] [ka]

[0044] [ka]

[0045] [ka]

[0046] [ka]

[0047] [ka]

[0048] [ka]

[0049] [ka]

[0050] [ka]

[0051] [ka]

[0052] [Method for producing hypervalent iodine compounds] The hypervalent iodine compounds used in the present invention can be obtained by known methods. For example, if the target hypervalent iodine compound is a five-membered heterocycle containing iodine(III) and nitrogen, it can be obtained by oxidative cyclization of 2-iodobenzamide with an oxidizing agent such as peracetic acid, and then acetylating the OH group and NH group with acetic anhydride or the like. Compounds that are five-membered heterocycles containing sulfur instead of nitrogen can be obtained in the same manner. In formula (1) above, X is a nitrogen atom, and R 31 When is anything other than a hydrogen atom, R 31 2-iodobenzamide substituted with R may be used as a starting material, or after the formation of a 5-membered heterocycle, an appropriate substitution reaction may be carried out to R 31 It may be introduced. For synthesis methods, see, for example, J.Am.Chem.Soc.,1997,vol.119,No.31,p.7408-7409, Japanese Patent Publication No. 2015-186792, etc.

[0053] [Carboxylate-containing compounds] The carboxyl group-containing compound is preferably a polymer containing repeating units represented by the following formula (2) or a compound represented by the following formula (3). [ka] (In the formula, R A X is a hydrogen atom, a halogen atom, a methyl group, or a trifluoromethyl group. A This refers to a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX A1 - is X A1 p is a saturated hydrocarbylene group, phenylene group, or naphthylene group having 1 to 10 carbon atoms, and the saturated hydrocarbylene group may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring. * represents a bond with a carbon atom of the main chain. p is 1, 2, 3, or 4. R 41 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 41This 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. Furthermore, 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. 42 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 heteroatom, and some of the -CH2- of the hydrocarbylene group may be substituted with a group containing a heteroatom. When p is 2, 3 or 4, each R 42 They may be the same or different from each other.

[0054] In formula (2), R A X is a hydrogen atom, a halogen atom, a methyl group, or a trifluoromethyl group. A This refers to a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX A1 - is X A1 This is a saturated hydrocarbylene group, phenylene group, or naphthylene group having 1 to 10 carbon atoms, and the saturated hydrocarbylene group may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring. * represents a bond with a carbon atom of the main chain.

[0055] In equation (3), p is 1, 2, 3, or 4.

[0056] In formula (3), R 41 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 41 This 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. Furthermore, 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.

[0057] In formula (3), R 42 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 heteroatom, and some of the -CH2- of the hydrocarbylene group may be substituted with a group containing a heteroatom. When p is 2, 3 or 4, each R 42 They may be the same as or different from each other.

[0058] R 41 The p-valent hydrocarbon group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. The p-valent hydrocarbon group is obtained by removing p hydrogen atoms from a hydrocarbon. Examples of the hydrocarbon include alkanes with 1 to 40 carbon atoms, alkenes with 2 to 40 carbon atoms, alkynes with 2 to 40 carbon atoms, cyclic saturated hydrocarbons with 3 to 40 carbon atoms, cyclic unsaturated hydrocarbons with 3 to 40 carbon atoms, and aromatic hydrocarbons with 6 to 40 carbon atoms.

[0059] Examples of alkanes having 1 to 40 carbon atoms include methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, and their structural isomers.

[0060] Examples of alkenes having 2 to 40 carbon atoms include ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, decene, and their structural isomers.

[0061] Examples of alkynes having 2 to 40 carbon atoms include acetylene, propyne, butyn, pentyn, hexyn, heptyn, octin, nonine, decine, and their structural isomers.

[0062] Examples of the cyclic saturated hydrocarbons having 3 to 40 carbon atoms include cyclopropane, cyclobutane, cyclohexane, cycloheptane, cyclooctane, adamantane, norbornane, and the like.

[0063] Examples of the cyclic unsaturated hydrocarbons having 3 to 40 carbon atoms include cyclopropene, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, and norbornene.

[0064] Examples of aromatic hydrocarbons having 6 to 40 carbon atoms include benzene, naphthalene, and biphenyl.

[0065] R 41 The p-valent heterocyclic group represented by is a group obtained by the elimination of p hydrogen atoms from a heterocyclic compound. Examples of such heterocyclic compounds include furan, pyridine, pyrazole, and thiazolidinediones.

[0066] 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, sulfur atom, nitrogen atom, or halogen atom, and as a result may contain a hydroxyl group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. Furthermore, the p-valent hydrocarbon group may have some of its constituent -CH2- 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 sulfonic acid ester bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-OC(=O)-), etc.

[0067] R 42The hydrocarbylene group represented by can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include methanediyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-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, decane-1,10-diyl group, undecane-1,11-diyl group, and dodecane-1,1 Examples include alkanediyl groups with 1 to 20 carbon atoms, such as 2-diyl groups; cyclic saturated hydrocarbylene groups with 3 to 20 carbon atoms, such as cyclopentanediyl, cyclohexanediyl, norbornanediyl, and adamantanediyl groups; unsaturated aliphatic hydrocarbylene groups with 2 to 20 carbon atoms, such as vinylene and propene-1,3-diyl groups; arylene groups with 6 to 20 carbon atoms, such as phenylene and naphthylene groups; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing heteroatoms such as oxygen, sulfur, nitrogen, or halogen atoms, and some of the -CH2- groups constituting the hydrocarbylene group may be substituted with a group containing heteroatoms such as oxygen, sulfur, or nitrogen atoms, and as a result, the material may contain hydroxyl groups, cyano groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic acid anhydrides, and the like.

[0068] Among the carboxylic acid compounds represented by formula (3), those in which p is 2, 3, or 4 are preferred. In this case, when mixed with a hypervalent iodine compound, it is easier to form a strong high molecular weight resist film, which is preferable from the viewpoint of etching resistance and developer resistance.

[0069] Specific examples of carboxyl group-containing repeating units represented by formula (2) are, but are not limited to, those listed below. Note that in the following formula, R A This is the same as described above. [ka]

[0070] [ka]

[0071] Examples of carboxylic acid compounds represented by formula (3) are listed below, but are not limited to these. The carboxylic acid compounds may be commercially available or synthesized. [ka]

[0072] [ka]

[0073] [ka]

[0074] [ka]

[0075] [ka]

[0076] [ka]

[0077] A carboxyl group-containing polymer containing repeating units represented by formula (2) may further contain other repeating units (hereinafter also referred to as other repeating units). The other repeating units are not particularly limited, but those that can improve the solubility in solvents of polymers that are poorly soluble with only carboxyl group-containing repeating units are preferred. Preferred other repeating units include repeating units having a rigid skeleton and a cyclic structure that is expected to have high etching resistance, and repeating units containing a styrene skeleton.

[0078] Specific examples of the aforementioned other repeating units include, but are not limited to, those listed below. Note that in the following formula, R A This is the same as above, and X B These are, independently, -CH2- or -O-. [ka]

[0079] [ka]

[0080] [ka]

[0081] [ka]

[0082] [ka]

[0083] [ka]

[0084] [ka]

[0085]

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[0086]

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[0087]

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[0088]

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[0089]

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[0090]

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[0091]

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[0092]

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[0093]

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[0094]

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[0095]

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[0096]

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[0097]

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[0098]

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[0099]

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[0100]

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[0101]

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[0102]

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[0103]

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[0104]

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[0105]

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[0106] [ka]

[0107] [ka]

[0108] In the resist composition, the content ratio of the hypervalent iodine compound to the carboxyl group-containing compound (a polymer containing repeating units represented by formula (2) and / or a compound represented by formula (3)) is preferably, in molar ratio, 10:90 to 90:10, more preferably 20:80 to 80:20. The hypervalent iodine compound may be used alone or in combination of two or more types. The carboxyl group-containing polymer may be used alone or in combination of two or more types with different composition ratios, weight-average molecular weights (Mw), and / or molecular weight distributions (Mw / Mn). The aforementioned monomolecule compounds may be used individually or in combination of two or more. The carboxyl group-containing polymer and the aforementioned monomolecule compounds may be used individually or in combination.

[0109] In the carboxyl group-containing polymer, the content ratio (molar ratio) of carboxyl group-containing repeating units and other repeating units is preferably carboxyl group-containing repeating units:other repeating units = 10:90 to 90:10, more preferably 15:85 to 85:15, and even more preferably 20:80 to 80:20.

[0110] The weight-average molecular weight (Mw) of the carboxyl group-containing polymer is preferably 1,000 to 500,000, and more preferably 3,000 to 100,000. In this invention, the weight-average molecular weight Mw and the number-average molecular weight Mn are measured values ​​on a standard polystyrene basis by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent, and the dispersion degree Mw / Mn is a value obtained from these values.

[0111] Furthermore, if the molecular weight distribution (Mw / Mn) of the carboxyl group-containing polymer is broad, low molecular weight and high molecular weight polymers may be present, which may result in the appearance of foreign matter on the pattern or deterioration of the pattern shape after exposure. Therefore, as the pattern rule becomes finer, the influence of Mw and Mw / Mn tends to increase. To obtain a resist composition suitable for fine pattern dimensions, it is preferable that the Mw / Mn of the carboxyl group-containing polymer be narrowly dispersed, between 1.00 and 2.00. It is preferable that Mw / Mn be greater than 1.30, with a lower limit of 1.40, 1.50, or 1.60, and an upper limit of 1.70, 1.80, or 1.90.

[0112] One method for synthesizing the carboxyl group-containing polymer is to heat a monomer that provides the repeating units mentioned above in an organic solvent with a radical polymerization initiator added, and polymerize it.

[0113] Specific examples of organic solvents used in polymerization reactions include toluene, benzene, THF, diethyl ether, dioxane, cyclohexane, cyclopentane, cyclopentanone, cyclohexanone, methyl ethyl ketone (MEK), propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), and γ-butyrolactone (GBL). Specific examples of polymerization initiators 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 polymerization initiator added is preferably 0.01 to 25 mol% of 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.

[0114] The polymerization initiator may be added to the monomer solution and supplied to the reaction vessel, or an initiator solution may be prepared separately from the monomer solution and each supplied to the reaction vessel independently. Since the polymerization reaction may proceed and a superpolymer may be formed by radicals generated from the initiator during the waiting time, it is preferable from a quality control viewpoint to prepare the monomer solution and the initiator solution independently and add them dropwise. In addition, known chain transfer agents such as dodecyl mercaptan and 2-mercaptoethanol may be used in combination to adjust the molecular weight. 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.

[0115] The amount of each monomer in the monomer solution can be appropriately set, for example, to achieve a preferred content ratio of the repeating units described above.

[0116] [Other hypervalent iodine compounds] The resist composition of the present invention may contain a hypervalent iodine compound represented by the following formula (4) or (5) (hereinafter also referred to as "other hypervalent iodine compounds"). By adding other hypervalent iodine compounds, the reactivity to light can be controlled and the sensitivity can be adjusted. [ka] (In the formula, m1 and m2 are integers between 0 and 2, and n1 is an integer between 0 and 4 when m1 is 0, an integer between 0 and 6 when m1 is 1, and an integer between 0 and 8 when m1 is 2. When m2 is 0, n2 is an integer between 1 and 3, and n3 is an integer between 0 and 5, satisfying 1 ≤ (n2 + n3) ≤ 6. When m2 is 1, n2 is an integer between 1 and 3, and n3 is an integer between 0 and 7, satisfying 1 ≤ (n2 + n3) ≤ 8. When m2 is 2, n2 is an integer between 1 and 3, and n3 is an integer between 0 and 9, satisfying 1 ≤ (n2 + n3) ≤ 10. R 51 R is a C1-C10 hydrocarbyl group which may contain a halogen atom or a heteroatom. 52 This is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a halogen atom or a heteroatom. When n1 is 2 to 8, each R 52 These may be the same or different from each other. Also, multiple Rs 52 However, they may bond with each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded. 53 This is a C1-C10 hydrocarbylene group, which may contain heteroatoms. *3 and *4 represent the bonds with the carbon atoms of the aromatic ring in the formula. However, *3 and *4 are bonded to adjacent carbon atoms of the aromatic ring. 61 and R 62 Each of these is independently a C1-C10 hydrocarbyl group which may contain a halogen atom or a heteroatom. 61 and R 62 However, they may bond with each other to form a ring with the carbon atoms to which they are bonded and the atoms between the carbon atoms. When n2 is 2 to 3, each R 61 and R 62 These may be identical or different from each other. 63is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a halogen atom or a hetero atom. When n3 is 2 to 9, each R 63 may be the same as or different from each other. Also, a plurality of R 63 may combine with each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached.)

[0117] In the above formula, m1 and m2 are integers from 0 to 2. When m1 is 0, n1 is an integer from 0 to 4; when m1 is 1, n1 is an integer from 0 to 6; when m1 is 2, n1 is an integer from 0 to 8. When m2 is 0, n2 is an integer from 1 to 3, n3 is an integer from 0 to 5, and 1 ≤ (n2 + n3) ≤ 6 is satisfied. When m2 is 1, n2 is an integer from 1 to 3, n3 is an integer from 0 to 7, and 1 ≤ (n2 + n3) ≤ 8 is satisfied. When m2 is 2, n2 is an integer from 1 to 3, n3 is an integer from 0 to 9, and 1 ≤ (n2 + n3) ≤ 10 is satisfied. R 51 is a hydrocarbyl group having 1 to 10 carbon atoms which may contain a halogen atom or a hetero atom. R 52 is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a halogen atom or a hetero atom. When n1 is 2 to 8, each R 52 may be the same as or different from each other. Also, a plurality of R 52 may combine with each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached. R 53 is a hydrocarbylene group having 1 to 10 carbon atoms which may contain a hetero atom. *3 and *4 represent bonds to the carbon atoms of the aromatic ring in the formula. However, *3 and *4 are attached to adjacent carbon atoms of the aromatic ring. R 61 and R 62 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a halogen atom or a hetero atom. Also, R 61 and R 62However, they may bond with each other to form a ring together with the carbon atoms to which they are bonded and the atoms between those carbon atoms. R 63 This is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a halogen atom or a heteroatom. When n3 is 2 to 9, each R 63 These may be the same or different from each other. Also, multiple Rs 63 However, they may bond with each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded.

[0118] In the above general formula (4), m1 is an integer between 0 and 2. When m1 is 0, n1 is an integer between 0 and 4; when m1 is 1, n1 is an integer between 0 and 6; and when m1 is 2, n1 is an integer between 0 and 8. It is preferable that n1 is 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.

[0119] In the above general formula (4), R 51 This is a C1-C10 hydrocarbyl group which may contain halogen atoms or heteroatoms. Specific examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms. The C1-C10 hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C10 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl groups; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0 2,6Examples include cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as decanyl groups and adamantyl groups; alkenyl groups having 2 to 10 carbon atoms, such as vinyl groups and allyl groups; aryl groups having 6 to 10 carbon atoms, such as phenyl groups and naphthyl groups; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the -CH2- groups of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, the group may contain hydroxyl groups, cyano groups, halogen atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic acid anhydrides (-C(=O)-OC(=O)-), etc. 51 Preferably, the group is a hydrocarbyl group having 1 to 4 carbon atoms or a fluorinated hydrocarbyl group having 1 to 4 carbon atoms, and more preferably a hydrocarbyl group having 1 to 4 carbon atoms.

[0120] In the above general formula (4), R 52 This is a C1-C40 hydrocarbyl group which may contain a halogen atom or a heteroatom. Specific examples of the halogen atom include fluorine, chlorine, bromine, and iodine atoms. The C1-C40 hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C40 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl groups; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0 2,6Examples include cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms, such as decanyl groups, adamantyl groups, and adamantylmethyl groups; and aryl groups having 6 to 40 carbon atoms, such as phenyl groups, naphthyl groups, and anthracenyl groups. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the -CH2- of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, it may contain hydroxyl groups, cyano groups, halogen atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic acid anhydrides (-C(=O)-OC(=O)-), etc. When n is 2 to 8, each R 2 These may be the same or different from each other. Also, multiple Rs 52 However, they may bond with each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded.

[0121] In the above general formula (4), R 53 This is a C1-C10 hydrocarbylene group, which may contain heteroatoms. The C1-C10 hydrocarbylene group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include alkylene groups with 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, decane-1,10-diyl group, etc.; cyclopentanediyl group, cyclohexanediyl group, norbornanediyl group, adamantanediyl group, tricyclo[5.2.1.0 2,6Examples include cyclic saturated hydrocarbylene groups having 3 to 10 carbon atoms, such as decanediyl groups; alkenylene groups having 2 to 10 carbon atoms, such as vinylene groups and propynylene groups; arylene groups having 6 to 10 carbon atoms, such as phenylene groups, methylphenylene groups, ethylphenylene groups, n-propylphenylene groups, isopropylphenylene groups, n-butylphenylene groups, and naphthylene groups; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the -CH2- of the hydrocarbylene group may be substituted with a group containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, it may contain a hydroxyl group, a cyano group, an alkyl halide, a halogen atom, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-OC(=O)-), etc. 53 Preferred members include carbonyl groups, C1-C4 hydrocarbylene groups, or C1-C4 fluorinated hydrocarbylene groups.

[0122] In the general formula (4) above, *3 and *4 represent the bonds with the carbon atoms of the aromatic ring in the formula. However, *3 and *4 are bonded to adjacent carbon atoms of the aromatic ring. There are seven possible combinations of *3, *4 and m1, as shown below. [ka] (In the formula, n1, R 52 and R 53 This is the same as above. The dashed line is R 51 (This represents a bond between -C(=O)-O-.) Note, R 52 , R 53 The above formula allows for the substitution of any position in the aromatic ring.

[0123] Specific examples of the hypervalent iodine compound represented by the above general formula (4) include, but are not limited to, those shown below. In the following formulas, Me represents a methyl group.

Chem.

[0124]

Chem.

[0125]

Chem.

[0126]

Chem.

[0127]

Chem.

[0128]

Chem.

[0129]

Chem.

[0130]

Chem.

[0131]

Chem.

[0132]

Chem.

[0133]

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[0134]

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[0135]

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[0136]

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[0137]

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[0140]

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[0148]

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[0149]

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[0150]

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[0151]

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[0152]

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[0153]

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[0154]

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[0155]

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[0156]

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[0157]

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[0158]

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[0159]

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[0160]

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[0162]

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[0164]

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[0173]

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[0174]

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[0175] [ka]

[0176] [ka]

[0177] [ka]

[0178] [ka]

[0179] In the general formula (5) above, m² is an integer between 0 and 2. When m2 is 0, n2 is an integer between 1 and 3, and n3 is an integer between 0 and 5, satisfying 1 ≤ (n2 + n3) ≤ 6. When m2 is 1, n2 is an integer between 1 and 3, n3 is an integer between 0 and 7, and 1 ≤ (n2 + n3) ≤ 8. When m2 is 2, n2 is an integer between 1 and 3, n3 is an integer between 0 and 9, and 1 ≤ (n2 + n3) ≤ 10.

[0180] In the above general formula (5), R 61 and R 62 Each of these is independently a C1-C10 hydrocarbyl group which may contain a halogen atom or a heteroatom. 61 and R 62However, they may bond to each other and form a ring with the carbon atoms to which they are bonded and the atoms between the carbon atoms. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine. The C1-C10 hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C10 alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0 2,6 Examples include cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as decanyl and adamantyl groups; alkenyl groups having 6 to 10 carbon atoms, such as vinyl and allyl groups; aryl groups having 6 to 10 carbon atoms, such as phenyl and naphthyl groups; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen, sulfur, nitrogen, and halogen atoms, and some of the -CH2- groups of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen, sulfur, and nitrogen atoms, resulting in the presence of hydroxyl groups, cyano groups, halogen atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic acid anhydrides (-C(=O)-OC(=O)-), etc. 61 and R 62 A hydrocarbyl group having 1 to 4 carbon atoms is preferred.

[0181] In the above general formula (5), R 63This is a C1-C40 hydrocarbyl group which may contain a halogen atom or a heteroatom. Examples of the halogen atom include fluorine, chlorine, bromine, and iodine atoms. The C1-C40 hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C40 alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl groups; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0 2,6 Examples include cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms, such as decanyl groups, adamantyl groups, and adamantylmethyl groups; and aryl groups having 6 to 40 carbon atoms, such as phenyl groups, naphthyl groups, and anthracenyl groups. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the -CH2- of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, it may contain hydroxyl groups, cyano groups, halogen atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic acid anhydrides (-C(=O)-OC(=O)-), etc. When n3 is 2 to 9, each R 63 These may be the same or different from each other. Also, multiple Rs 63 However, they may bond with each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded. Note, R 63 The above formula allows for the substitution of any position in the aromatic ring.

[0182] Specific examples of hypervalent iodine compounds represented by the general formula (5) above include, but are not limited to, those listed below.

[0183] [ka]

[0184] [ka]

[0185] [ka]

[0186] [ka]

[0187] If the resist composition of the present invention contains other hypervalent iodine compounds, the other hypervalent iodine compounds may consist solely of the hypervalent iodine compound represented by general formula (4), solely of the hypervalent iodine compound represented by general formula (5), or a combination of the hypervalent iodine compound represented by general formula (4) and the hypervalent iodine compound represented by general formula (5). Furthermore, the hypervalent iodine compound represented by general formula (4) and the hypervalent iodine compound represented by general formula (5) may each be used individually or in combination of two or more different types.

[0188] If the resist composition of the present invention contains other hypervalent iodine compounds, the content ratio of the hypervalent iodine compounds to the carboxyl group-containing compound (or, if the carboxyl group-containing compound is a carboxyl group-containing polymer, the content ratio of the hypervalent iodine compounds to the carboxylic acid-containing repeating units in the polymer) is preferably 1:99 to 99:1, more preferably 10:90 to 90:10, and even more preferably 20:80 to 80:20 in molar ratio. Furthermore, the other hypervalent iodine compounds are preferably included in a molar ratio of other hypervalent iodine compounds to the hypervalent iodine compound represented by formula (1) such that the ratio is 1:99 to 99:1, and more preferably 1:99 to 50:50.

[0189] [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 compound, other hypervalent iodine compounds and other components described later, and form a film. Such solvents are preferably organic solvents, and specific examples 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, and Examples 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 monotert-butyl ether acetate; carboxylic acids such as formic acid, acetic acid, and propionic acid; lactones such as γ-butyrolactone; and mixed solvents thereof.

[0190] In the resist composition of the present invention, the amount of solvent is preferably such that the solid content concentration in the resist composition is 0.1 to 20% by mass, more preferably 0.1 to 15% by mass, and even more preferably 0.1 to 10% by mass. In the present invention, "solid content" refers to all components of the resist composition other than the solvent. The solvent may be used alone or as a mixture of two or more types.

[0191] The resist composition of the present invention may further contain a surfactant. A fluorine-based and / or silicone-based surfactant is preferred. Specific examples of such surfactants include those described in paragraph

[0276] of U.S. Patent Application Publication 2008 / 0248425. Furthermore, surfactants other than the fluorine-based and / or silicone-based surfactants described in paragraph

[0280] of U.S. Patent Application Publication 2008 / 0248425 may also be used.

[0192] If the resist composition of the present invention contains the surfactant, its content is preferably 0.0001 to 2% by mass of the total solids. The surfactant may be used alone or in combination of two or more types.

[0193] The resist composition of the present invention may further contain at least one selected from radical scavengers and crosslinking agents. This allows for control of the photoreaction during photolithography and adjustment of sensitivity.

[0194] Specific examples of the radical scavengers include hindered phenols, quinones, hindered amines, and thiol compounds. Specifically, examples of hindered phenols include dibutylhydroxytoluene (BHT) and 2,2'-methylenebis(4-methyl-6-tert-butylphenol). Specific examples of quinones include 4-methoxyphenol (methoquinone) and hydroquinone. Specific examples of hindered amines include 2,2,6,6-tetramethylpiperidine and 2,2,6,6-tetramethylpiperidine-N-oxy radical. Specific examples of thiols include dodecanethiol and hexadecanethiol.

[0195] If the resist composition of the present invention contains the radical scavenger, its content is preferably 0.01 to 10% by mass of the total solid content. The radical scavenger may be used alone or in combination of two or more types.

[0196] Specific examples of the crosslinking agent include compounds having carbon-carbon unsaturated bonds as functional groups, such as vinyl groups, (meth)acrylate groups, allyl groups, alkynyl groups, and aromatic rings. Specifically, specific examples of compounds having a vinyl group include linear alkenes, branched alkenes, and cyclic alkenes, which may have substituents. Specific examples of compounds having a (meth)acrylate group include acrylic acid, methacrylic acid, acrylic acid esters, and methacrylic acid esters, which may have substituents. Specific examples of compounds having an allyl group include allyl alcohol, allyl ether, allyl ester, allyl amide, allylamine, and allyl group-containing isocyanurates, which may have substituents. Specific examples of compounds having an alkynyl group include linear alkynes, branched alkynes, cyclic alkynes, alkynyl alcohol, alkynyl ether, alkynyl ester, alkynyl amide, alkynylamine, and alkynyl group-containing isocyanurates, which may have substituents. Specific examples of compounds having an aromatic ring include arenes, heteroarenes, styrene, stilbene, phenylacetylene, acenaphthylene, and chalcone, which may have substituents. The crosslinking agent may have only one of the functional groups or may have multiple functional groups. The number of functional groups contained in the crosslinking agent is preferably 1 to 10, and more preferably 2 to 8.

[0197] If the resist composition of the present invention contains the crosslinking agent, its content is preferably 0.01 to 50% by mass of the total solids. The crosslinking agent may be used alone or in combination of two or more types.

[0198] As described above, the resist composition of the present invention mainly contains hypervalent iodine compounds and carboxyl group-containing compounds, but it does not need to contain acid-unstable group-containing base polymers or photoacid generators as found in conventional chemically amplified resist compositions. However, the resist composition of the present invention can form positive or negative patterns, particularly through EB or EUV exposure, due to differences in solubility between exposed and unexposed areas. The mechanism is not fully clear, but it can be inferred, for example, as follows.

[0199] The hypervalent iodine compound represented by formula (1) is a compound containing a three-coordinate hypervalent iodine molecule with a carboxylate ligand. When such a three-coordinate iodine compound is mixed with a carboxylic acid compound, it is thought that an equilibrium reaction occurs in which the carboxylate ligand is exchanged. In this case, if the original carboxylate ligand can be removed by some means, a hypervalent iodine compound with a new ligand is produced. For example, by mixing des-martin periodinane, a hypervalent iodine compound that is relatively easy to obtain, with a carboxylic acid compound with a large molecular weight, and removing the resulting low-boiling point acetic acid, the ligand exchange is completed. Here, the carboxyl group-containing compound becomes a polymer crosslinked by the hypervalent iodine compound.

[0200] Polymers crosslinked with hypervalent iodine compounds are formed during film formation. This is because even if such crosslinked polymers are synthesized beforehand, they do not dissolve in many organic solvents, making it impossible to prepare a solution. This is presumed to be because hypervalent iodine compounds, which inherently have low solvent solubility due to their high polarization, become even less soluble when carboxyl group-containing compounds are used as ligands. 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.

[0201] The resist film of the present invention, formed on a substrate in this manner, changes polarity when its main component, a hypervalent iodine compound, is decomposed by light, and a pattern is formed during the development process. By appropriately selecting the developer, either a positive or negative pattern can be formed.

[0202] The resist composition of the present invention can be either positive or negative depending on the selection of its components. In the case of the positive type, it contains a polymer to which a hypervalent iodine compound is bonded during film formation. When this is decomposed by light, it becomes a monovalent iodine compound, and at the same time, the bond between the carboxyl group-containing compound and the hypervalent iodine compound is released, and the molecular weight decreases. As a result, it is presumed that a positive type pattern is formed in which the exposed areas are removed by an organic solvent.

[0203] On the other hand, in the case of the negative type, the polymer contains a hypervalent iodine compound crosslinked with a hypervalent iodine compound generated during film formation. When this is decomposed by light, crosslinking or re-bonding occurs, leading to an increase in molecular weight and a change in polarity. As a result, it is presumed that a negative type pattern is formed in which the unexposed areas are removed by an alkaline aqueous solution.

[0204] From the above inference, it can be said that the resist composition of the present invention is a non-chemically amplified resist composition. Since the resist composition of the present invention does not require an acid-unstable group-containing base polymer or a photoacid generator like conventional chemically amplified resist compositions, adverse effects due to acid diffusion (e.g., image blurring) do not occur, and fine patterns can be resolved.

[0205] The resist composition of the present invention is particularly effective in EUV lithography. This is because the resist composition of the present invention has iodine atoms with high absorption capacity for EUV light, and the hypervalent iodine compound represented by formula (1) has a carboxylate ligand on one of the iodine atoms that can undergo the aforementioned ligand exchange. As a result, crosslinking with the carboxyl group-containing compound after film formation proceeds at a higher density, and compared to cases where only other hypervalent iodine compounds are used, the difference in dissolution rate between the unexposed and exposed areas, i.e., the dissolution contrast, is larger. In other words, the resist composition of the present invention can achieve high sensitivity, high resolution, and low LWR due to these characteristics. Thus, using a non-chemically amplified resist containing an amide-type or thiocarbonyl-type hypervalent iodine compound and a carboxylic acid compound (carboxyl group-containing compound) improves the solubility of the resist as a whole and its decomposition products in the developer. This enables the formation of patterns with excellent sensitivity and roughness resolution.

[0206] As a resist composition for EUV lithography capable of forming fine patterns, metal resists mainly composed of metallic tin compounds, which have high absorption capacity for EUV light similar to iodine atoms, have been reported (for example, Patent Document 2). However, as mentioned above, such metal resists have many problems, such as insufficient solubility in solvents, storage stability, and defects due to etching residues caused by the presence of metallic elements. On the other hand, the resist composition of the present invention does not use metallic elements, so it is more advantageous than metal resists in terms of defects, and there are no problems with solubility in solvents. Furthermore, the resist composition of the present invention can be applied to both positive and negative type processes, thus having a wide range of applications. For example, in the contact hole formation process, a metal resist developed using negative type development requires an inversion process after pillar pattern formation, but such a process is unnecessary with positive type resists. Therefore, from the viewpoint of process simplicity, the resist composition of the present invention is more useful than metal resists.

[0207] Japanese Patent Publication No. 2015-180928 and Japanese Patent Publication No. 2018-95853 describe resist compositions containing hypervalent iodine compounds as additives, and resist compositions incorporating hypervalent iodine compounds into the polymer backbone of a base polymer. However, these patent documents only state that the resist compositions can improve line edge roughness as a characteristic, and do not mention the possibility of photodegradation of hypervalent iodine compounds or their potential to function as materials for non-chemically amplified resist compositions. Furthermore, according to the descriptions of the amounts used and specific examples, hypervalent iodine compounds are not the main components. In addition, Patent Document 3 proposes a positive-type resist composition using hypervalent iodine compounds, but it does not describe the hypervalent iodine compound represented by formula (1) of the present invention, and does not mention at all that using such compounds improves resolution or LWR. Therefore, it is unlikely that these patent documents would lead to the discovery of a non-chemically amplified resist composition like the present invention, which exhibits extremely high sensitivity, excellent resolving power, and is extremely effective for precise microfabrication. In other words, the present invention clearly provides a novel resist composition and pattern formation method.

[0208] [Laminated structure] The present invention provides a laminate characterized by comprising a substrate and a resist film formed on the substrate, which is a film formed from the resist composition described above. Such a laminate comprising a resist film obtained from the non-chemically amplified resist composition of the present invention is extremely effective for precise microfabrication because the resist film, which is a film formed from the resist composition described above, is extremely sensitive and exhibits excellent limiting resolution. Furthermore, it can be applied to the formation of both positive and negative patterns, thus having a wide range of applications and being extremely useful in resist process technology. In this case, a resist underlayer film may be provided between the substrate and the resist film as needed. Furthermore, it is preferable that the laminate of the present invention contains a resist film which includes a ligand exchange reaction product between the hypervalent iodine compound and the carboxyl group-containing compound. In other words, the laminate is obtained by forming a resist film obtained from the resist composition of the present invention on a substrate, and it is preferable that the resist film is formed by ligand exchange between the hypervalent iodine compound and the carboxyl group-containing compound. As described above, by removing the low molecular weight carboxylic acid produced as a by-product during film formation and the subsequent baking process, the hypervalent iodine compound undergoes a ligand exchange reaction with the carboxyl group-containing compound, forming a resist film containing the ligand exchange reaction product (i.e., giving a film-forming material). Upon completion of the ligand exchange, the carboxyl group-containing compound becomes a polymer crosslinked by the hypervalent iodine compound. Thus, it is preferable to complete the ligand exchange reaction and form a resist film.

[0209] [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 may include the steps of forming a resist film on a substrate using the resist composition described above, or on the resist underlayer of a substrate on which a resist underlayer film is laminated; exposing the resist film with high-energy rays; and developing the exposed resist film using a developer. Hereinafter, the resist underlayer film will also be simply referred to as the "underlayer film".

[0210] First, the resist composition of the present invention is applied to a substrate for integrated circuit manufacturing, or onto the underlying layer of a substrate with a laminated underlying layer (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective film, etc.), or to a substrate for mask circuit manufacturing, or onto the underlying layer of a substrate with a laminated underlying layer (Cr, CrO, CrON, MoSi2, SiO2, etc.) using an appropriate coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, or doctor coating, so that the coating thickness is 0.01 to 2 μm. This is then pre-baked 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 underlying layer refers to the film formed between the substrate and the resist film in a multilayer resist process, and the underlying layer is not particularly limited; conventionally known films can be used.

[0211] Next, the resist film is exposed using high-energy rays. Examples of high-energy rays include ultraviolet rays (g-rays (436 nm), h-rays (405 nm), i-rays (365 nm), etc.), far ultraviolet rays, EB, EUV, X-rays, soft X-rays, excimer laser light (KrF excimer laser light, ArF excimer laser light, etc.), gamma rays, and synchrotron radiation. Preferably, i-rays, KrF excimer laser light, ArF excimer laser light, electron beams, or extreme ultraviolet rays are used as the high-energy rays. When ultraviolet rays, far ultraviolet rays, EUV, X-rays, soft X-rays, excimer laser light, gamma rays, synchrotron radiation, etc. are used as the high-energy rays, the exposure amount is preferably 1 to 300 mJ / cm², either directly or using a mask to form the desired pattern. 2 To the extent, more preferably 10-200 mJ / cm² 2 Irradiate to a degree that results in the desired exposure. When using electroluminescence (EB) as the high-energy beam, the exposure amount is preferably 0.1 to 2000 μC / cm², either directly or using a mask to form the desired pattern. 2 To a degree, more preferably 0.5 to 1500 μC / cm² 2The pattern is drawn to a certain extent. Furthermore, the resist composition of the present invention is particularly suitable for fine patterning using EB or EUV, among other high-energy rays.

[0212] After exposure, PEB (Photopolymerization) is performed as needed. In this case, it is preferable to perform the PEB on a hot plate or in an oven at 30-150°C for 10 seconds to 30 minutes, more preferably at 60-120°C for 30 seconds to 20 minutes.

[0213] After exposure or PEB, develop and pattern the image using a developer as needed. The developers used at this time include alkaline aqueous solutions such as tetramethylammonium hydroxide aqueous 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, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotate, ethyl crotate, propionic acid Examples of organic solvents include methyl, 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 phenyl acetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, 2-phenylethyl acetate, 1-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 individually or in mixtures of two or more.

[0214] After development, rinsing should be performed as needed. A solvent that mixes with the developer but does not dissolve the resist film is preferred as the rinsing solution. Preferred solvents include C3-C10 alcohols, C8-C12 ether compounds, C6-C12 alkanes, alkenes, alkynes, and aromatic solvents. Alternatively, water may be used as the rinsing solution instead of an organic solvent.

[0215] Rinsing can reduce the occurrence of deformation and defects in the resist pattern. However, rinsing is not always necessary, and omitting it can reduce the amount of solvent used.

[0216] As described above, the resist composition of the present invention, upon exposure, creates a difference in solubility between the exposed and unexposed areas, allowing for the formation of positive or negative patterns. Therefore, it is possible to use a developer that dissolves the exposed areas but not the unexposed areas, or vice versa. Thus, the pattern formation method of the present invention can be widely applied to the formation of various fine patterns, as it can form positive or negative patterns by appropriately selecting the developer. [Examples]

[0217] The present invention will be specifically described below with reference to synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples.

[0218] [1] Preparation of hypervalent iodine compounds The hypervalent iodine compounds used in the examples are represented by the following formulas (I-1) to (I-2). [ka]

[0219] I-1 and I-2 were synthesized as follows. [ka]

[0220] [Synthesis Example 1-1] Synthesis of I-1 20 mL of 2.0 M peracetic acid was mixed with 2-iodobenzamide (5 g, 20 mmol) and stirred at 40°C for 5 hours. After returning to room temperature, 100 mL of isopropyl ether (IPE) was added, and the solid was filtered off. The obtained solid was dried at 40°C for 2 hours to obtain M-1 (4.2 g, yield 78%). The nuclear magnetic resonance spectrum of the obtained M-1 is as follows. 1 H NMR:(500MHz,DMSO-d6) δ 7.29(m,1H),7.38(d,J=8.3Hz,1H),7.42(m,1H),7.49(br,1H),7.76(br,1H),7.81(m,1H)ppm.

[0221] M-1 (4.2 g, 16 mmol) was dispersed in acetic anhydride (20 mL) and stirred at 140 °C for 5 hours. After returning to room temperature, 100 mL of IPE was added, and the solid was filtered off. The obtained solid was dried at 40 °C for 2 hours to obtain I-1 (3.9 g, yield 70%). The nuclear magnetic resonance spectrum and mass spectrometry spectrum of the obtained I-1 are as follows. 1 H NMR:(500MHz,CDCl3) δ 1.94(s,3H),2.34(s,3H),7.74(m,1H),7.81(m,1H),8.10(m,1H),8.23(m,1H)ppm. Single quadrupole mass spectrometry (ESI): POSITIVE M + H + 347.9(C 11 H 11 INO4 equivalent)

[0222] [Synthesis Example 1-2] Synthesis of I-2 I-2 was synthesized using the same method as I-1. The nuclear magnetic resonance spectrum and mass spectrometry spectrum of the obtained I-2 are as follows. 1H NMR:(500MHz,CDCl3) δ 2.18(s,3H),3.24(s,3H),7.68(t,J=7.5Hz,1H),7.80(m,1H),8.10-8.22(m,2H)ppm. Single quadrupole mass spectrometry (ESI): POSITIVE M + H + 319.9(C 10 H 11 INO3 equivalent)

[0223] [2] Polymer synthesis The monomers used in the synthesis of the polymer are as follows: [ka]

[0224] [ka]

[0225] [ka]

[0226] [Synthesis Example 2-1] Synthesis of Polymer P-1 Under a nitrogen atmosphere, monomer a-1 (56g), monomer b-1 (105g), 5.4g of V-601 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 180g of MEK were placed in a flask to prepare a monomer-polymerization initiator solution. In another flask under a nitrogen atmosphere, 55g of MEK was placed and heated to 80°C with stirring, and then the monomer-polymerization initiator solution was added dropwise over 4 hours. After the addition was complete, the polymerization solution was kept at 80°C and stirred for 2 hours, then cooled to room temperature. The obtained polymerization solution was added dropwise to 4000g of hexane that had been vigorously stirred, and the precipitated polymer was filtered off. Furthermore, the obtained polymer was washed twice with 1200g of hexane and then vacuum dried at 50°C for 20 hours to obtain a white powdery polymer P-1 (yield 155g, yield 96%). The Mw of polymer P-1 was 7700, and the Mw / Mn ratio was 1.82. Note that Mw and Mn are polystyrene-converted values ​​measured by GPC using THF as the solvent. Specifically, the measurements were taken under the following conditions (the same applies below). ·Equipment: HLC-8320GPC • Column: TSK guardcolumn +TSKgel G4000HXL +TSKgel G2000HXL +TSKgel Super H5000 Pump and column constant temperature: 40°C ·Eluent:THF • Detector: RI (Differential Refraction) detector ·Injection volume: 100 μl [ka]

[0227] [Synthesis Examples 2-2 to 2-10] Synthesis of Polymers P-2 to P-10 The polymers shown in Table 1 below were synthesized using the same method as in Synthesis Example 2-1, except that the types and mixing ratios of each monomer were changed. Note that polymer P-10 is a polymer that does not have a carboxyl group (-COOH) and therefore does not fall under the category of carboxyl group-containing compounds of the present invention.

[0228] [Table 1]

[0229] [3] Preparation of resist composition [Examples 1-1 to 1-22, Comparative Examples 1-1 to 1-4] Hypervalent iodine compounds, other hypervalent iodine compounds, and polymers were dissolved in a solvent containing 0.01% by mass of surfactant (PF-636, manufactured by Omnova) in the compositions shown in Table 2 below. The resulting solutions were filtered through a 0.2 μm Teflon® filter to prepare resist compositions (R-01 to R-22) and comparative resist compositions (CR-01 to CR-02). In addition, comparative resist compositions (CR-03 to CR-04) were prepared by dissolving polymers, photoacid generators, and sensitivity modifiers in a solvent containing 0.01% by mass of surfactant (PF-636, manufactured by Omnova) in the compositions shown in Table 3 below. The resulting solutions were filtered through a 0.2 μm Teflon® filter.

[0230] [Table 2]

[0231] [Table 3]

[0232] In Tables 2 and 3, the other hypervalent iodine compound O-1, carboxyl group-containing compounds m-1 to m-6, photoacid generator PAG-1, sensitivity modifier Q-1, and solvent are as follows:

[0233] [ka]

[0234] [ka]

[0235] [ka]

[0236] [ka]

[0237] • Solvent: PGMEA (Propylene glycol monomethyl ether acetate) AcOH (acetic acid) HBM (methyl 2-hydroxyisobutyrate) PA (propionic acid) GBL (γ-butyrolactone)

[0238] [4] EUV lithography evaluation (line and space pattern, positive tone development) [Examples 2-1 to 2-22, Comparative Examples 2-1 to 2-4] Each resist composition (R-01 to R-22, CR-01 to CR-04) was spin-coated onto a Si substrate formed with a silicon-containing spin-on hard mask SHB-A940 (silicon content 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. to a thickness of 20 nm. A 40 nm thick resist film was then fabricated by post-application baking (PAB) for 60 seconds at the temperatures listed in Table 4 using a hot plate. After exposing a 36 nm line-and-space (LS) 1:1 pattern using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9, 90-degree dipole illumination), PEB was performed on a hot plate for 60 seconds at the temperatures listed in Table 4, followed by development for 30 seconds with the developer listed in Table 4 to form an LS pattern with a space width of 18 nm and a pitch of 36 nm.

[0239] The obtained resist patterns were evaluated as follows. The results are shown in Table 4.

[0240] [Sensitivity evaluation] The aforementioned LS pattern was observed using a Hitachi High-Tech Corporation measuring SEM (CG-6300), and the optimal exposure dose Eop(mJ / cm²) was determined to obtain an LS pattern with a space width of 18 nm and a pitch of 36 nm.2 We calculated this value and defined it as the sensitivity.

[0241] [LWR rating] The LS pattern obtained by irradiating with the optimal exposure was measured at 10 points along the longitudinal direction of the space width using a Hitachi High-Tech SEM (CG-6300), and the LWR was calculated as three times the standard deviation (σ) (3σ) from the results. The smaller this value, the less roughness and the more uniform the space width pattern obtained.

[0242] [Evaluation of Limit Resolution] The minimum line width (nm) at which the pattern can be resolved was determined using a Hitachi High-Tech SEM (CG-6300) to gradually increase the exposure from the optimal exposure for forming the aforementioned LS pattern. This was defined as the limiting resolution (nm). A smaller value indicates superior limiting resolution and the ability to form finer patterns.

[0243] [Table 4]

[0244] Developer: nBA (butyl acetate) CHA (Cyclohexyl Acetate) TMAH (2.38% by mass tetramethylammonium hydroxide aqueous solution)

[0245] [5] EUV lithography evaluation (line and space pattern, negative tone development) [Examples 3-1 to 3-22, Comparative Examples 3-1 to 3-4] Each resist composition (R-1 to R-22, CR-01 to CR-04) was spin-coated onto a Si substrate formed with a silicon-containing spin-on hard mask SHB-A940 (silicon content 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. to a thickness of 20 nm. A 40 nm thick resist film was then fabricated by post-application baking (PAB) for 60 seconds at the temperatures listed in Table 5 using a hot plate. An ASML EUV scanner NXE3400 (NA 0.33, σ 0.9, 90-degree dipole illumination) was used to expose a 36 nm line-and-space (LS) 1:1 pattern. This was then baked (PEB) on a hot plate for 60 seconds at the temperatures listed in Table 5, followed by development for 30 seconds using the developer solutions listed in Table 5 to form an LS pattern with a space width of 18 nm and a pitch of 36 nm.

[0246] The obtained resist patterns were evaluated as follows. The results are shown in Table 5.

[0247] [Sensitivity evaluation] The aforementioned LS pattern was observed using a Hitachi High-Tech Corporation measuring SEM (CG-6300), and the optimal exposure dose Eop(mJ / cm²) was determined to obtain an LS pattern with a space width of 18 nm and a pitch of 36 nm. 2 We calculated this value and defined it as the sensitivity.

[0248] [LWR rating] The LS pattern obtained by irradiating with the optimal exposure was measured at 10 points along the longitudinal direction of the space width using a Hitachi High-Tech SEM (CG-6300), and the LWR was calculated as three times the standard deviation (σ) (3σ) from the results. The smaller this value, the less roughness and the more uniform the space width pattern obtained.

[0249] [Evaluation of Limit Resolution] The minimum line width (nm) at which the pattern can be resolved was determined using a Hitachi High-Tech SEM (CG-6300) to gradually increase the exposure from the optimal exposure for forming the aforementioned LS pattern. This was defined as the limiting resolution (nm). A smaller value indicates superior limiting resolution and the ability to form finer patterns.

[0250] [Table 5]

[0251] The results shown in Tables 4 and 5 indicate that the resist composition of the present invention exhibits excellent sensitivity, LWR, and resolution in line-and-space pattern formation by EUV exposure, regardless of whether positive or negative tone development is performed.

[0252] [6] EUV lithography evaluation (contact hole pattern) [Examples 4-1 to 4-22, Comparative Examples 4-1 to 4-4] Each resist composition (R-01 to R-22, CR-01 to CR-04) was spin-coated onto a Si substrate formed with a silicon-containing spin-on hard mask SHB-A940 (silicon content 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. to a thickness of 20 nm. A 50 nm thick resist film was then fabricated by post-application baking (PAB) for 60 seconds at the temperatures listed in Table 6 using a hot plate. Next, the resist film was exposed using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadruple pole illumination, wafer dimensions of 64 nm pitch, +20% bias hole pattern mask), baked (PEB) on a hot plate for 60 seconds at the temperatures listed in Table 6, and developed for 30 seconds with the developer listed in Table 6 to obtain a 32 nm hole pattern.

[0253] The obtained resist patterns were evaluated as follows. The results are shown in Table 6. [Sensitivity evaluation] The aforementioned contact hole pattern was observed using a Hitachi High-Tech SEM (CG-6300) to determine the optimal exposure dose Eop(mJ / cm²) for obtaining a hole pattern with dimensions of 32 nm. 2 ) was sought.

[0254] [CD Uniformity (CDU) Evaluation] The dimensions of 50 hole patterns obtained by irradiating with the optimal exposure were measured, and the standard deviation (σ) calculated from these results was multiplied by three (3σ) and defined as the CDU. A smaller CDU value indicates a more uniform hole diameter pattern.

[0255] [Evaluation of Limit Resolution] The minimum hole diameter (nm) that can be resolved while gradually decreasing the exposure from the optimal exposure for forming the aforementioned hole pattern was determined using a Hitachi High-Technologies Corporation length-measuring SEM (CG-6300), and this was defined as the limiting resolution (nm). A smaller value indicates superior limiting resolution and the ability to form patterns with finer hole diameters.

[0256] [Table 6]

[0257] The results shown in Table 6 indicate that the resist composition of the present invention exhibits excellent sensitivity, CDU, and resolution in contact hole pattern formation by EUV exposure.

[0258] This specification includes the following embodiments: [1]: A resist composition characterized by comprising a hypervalent iodine compound represented by the following formula (1), a carboxyl group-containing compound, and a solvent. [ka] (In the formula, a1 is 0, 1, or 2. When a1 is 0, b1 is 0, 1, 2, 3, or 4; when a1 is 1, b1 is 0, 1, 2, 3, 4, 5, or 6; and when a1 is 2, b1 is 0, 1, 2, 3, 4, 5, 6, 7, or 8. R 11 Each of these is independently a C1-C10 hydrocarbyl group which may contain a halogen atom or a heteroatom. 21 Each of these is a hydrocarbyl group having 1 to 40 carbon atoms, which may each contain a halogen atom or a heteroatom. When b1 is 2 or more, each R 21These may be the same or different from each other, and there may be multiple R 21 However, they may bond with each other to form a ring with the carbon atoms of the aromatic ring to which they are bonded. X is a nitrogen atom or a sulfur atom, and in the case of a nitrogen atom, R 31 It may have R 31 This is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a hydrogen atom, a halogen atom, or a heteroatom. [2]: The resist composition of [1], characterized in that the carboxyl group-containing compound is either or both a polymer containing repeating units represented by the following formula (2) and a compound represented by the following formula (3). [ka] (In the formula, R A X is a hydrogen atom, a halogen atom, a methyl group, or a trifluoromethyl group. A This refers to a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX A1 - is X A1 p is a saturated hydrocarbylene group, phenylene group, or naphthylene group having 1 to 10 carbon atoms, and the saturated hydrocarbylene group may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring. * represents a bond with a carbon atom of the main chain. p is 1, 2, 3, or 4. R 41 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 41 This 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. Furthermore, 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. 42 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 heteroatom, and some of the -CH2- of the hydrocarbylene group may be substituted with a group containing a heteroatom. When p is 2, 3 or 4, each R42 They may be the same or different from each other. [3]: The resist composition of [1] or [2] further comprising at least one hypervalent iodine compound represented by the following formula (4) or (5). [ka] (In the formula, m1 and m2 are integers between 0 and 2, and n1 is an integer between 0 and 4 when m1 is 0, an integer between 0 and 6 when m1 is 1, and an integer between 0 and 8 when m1 is 2. When m2 is 0, n2 is an integer between 1 and 3, and n3 is an integer between 0 and 5, satisfying 1 ≤ (n2 + n3) ≤ 6. When m2 is 1, n2 is an integer between 1 and 3, and n3 is an integer between 0 and 7, satisfying 1 ≤ (n2 + n3) ≤ 8. When m2 is 2, n2 is an integer between 1 and 3, and n3 is an integer between 0 and 9, satisfying 1 ≤ (n2 + n3) ≤ 10. R 51 R is a C1-C10 hydrocarbyl group which may contain a halogen atom or a heteroatom. 52 This is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a halogen atom or a heteroatom. When n1 is 2 to 8, each R 52 These may be the same or different from each other. Also, multiple Rs 52 However, they may bond with each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded. 53 This is a C1-C10 hydrocarbylene group, which may contain heteroatoms. *3 and *4 represent the bonds with the carbon atoms of the aromatic ring in the formula. However, *3 and *4 are bonded to adjacent carbon atoms of the aromatic ring. 61 and R 62 Each of these is independently a C1-C10 hydrocarbyl group which may contain a halogen atom or a heteroatom. 61 and R 62 However, they may bond with each other to form a ring with the carbon atoms to which they are bonded and the atoms between the carbon atoms. When n2 is 2 to 3, each R 61 and R 62 These may be identical or different from each other. 63This is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a halogen atom or a heteroatom. When n3 is 2 to 9, each R 63 These may be the same or different from each other. Also, multiple Rs 63 However, they may bond with each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded. [4]: A laminate characterized by comprising a substrate and a resist film which is a film formed on the substrate of any one of the resist compositions [1] to [3]. [5]: The laminate of [4], characterized in that a resist underlayer film is further provided between the substrate and the resist film. [6]: A laminate of [4] or [5] characterized in that the resist film contains ligand exchange reaction products of the hypervalent iodine compound and the carboxyl group-containing compound. [7]: A pattern forming method characterized by comprising the steps of: forming a resist film on a substrate or on a resist underlayer of a substrate having a resist underlayer laminated on it using any one of the resist compositions from [1] to [3]; exposing the resist film with high-energy rays; and developing the exposed resist film using a developer. [8]: The pattern formation method of [7], characterized in that the high-energy ray is an i-ray, a KrF excimer laser beam, an ArF excimer laser beam, an electron beam, or an extreme ultraviolet beam. [9]: The pattern formation method of [7] or [8], characterized in that the developer used dissolves the exposed areas but does not dissolve the unexposed areas.

[10] : The pattern formation method of [7] or [8], characterized in that the developing solution used dissolves the unexposed areas but does not dissolve the exposed areas.

[0259] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention.

Claims

1. A resist composition characterized by comprising a hypervalent iodine compound represented by the following formula (1), a carboxyl group-containing compound, and a solvent. 【Chemistry 1】 (In the formula, a1 is 0, 1, or 2. When a1 is 0, b1 is 0, 1, 2, 3, or 4; when a1 is 1, b1 is 0, 1, 2, 3, 4, 5, or 6; and when a1 is 2, b1 is 0, 1, 2, 3, 4, 5, 6, 7, or 8. R １１ Each of these is independently a C1-C10 hydrocarbyl group which may contain a halogen atom or a heteroatom. ２１ Each is independently a C1-C40 hydrocarbyl group which may contain a halogen atom or a heteroatom. When b1 is 2 or more, each R ２１ These may be the same or different from each other, and there may be multiple R ２１ However, they may bond with each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded. X is a nitrogen atom or a sulfur atom, and in the case of a nitrogen atom, R ３１ It may have R. ３１ This is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a hydrogen atom, a halogen atom, or a heteroatom.

2. The resist composition according to claim 1, characterized in that the carboxyl group-containing compound is either or both a polymer containing repeating units represented by the following formula (2) and a compound represented by the following formula (3). 【Chemistry 2】 (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)-O-X 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 a hydroxy group, an ether bond, an ester bond or a lactone ring. * represents a bond to a carbon atom of the main chain. p is 1, 2, 3 or 4. R ４１ is a p-valent hydrocarbon group having 1 to 40 carbon atoms or a p-valent heterocyclic group having 2 to 40 carbon atoms. When p is 2, R ４１ 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. Also, 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 hetero atom, and -CH ２ - of the p-valent hydrocarbon group may be substituted with a group containing a hetero atom. R ４２ 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, and -CH ２ - of the hydrocarbylene group may be substituted with a group containing a hetero atom. When p is 2, 3 or 4, each R ４２ may be the same as or different from each other.)

3. Furthermore, the resist composition according to claim 1 further comprises at least one hypervalent iodine compound represented by the following formula (4) or (5). 【Transformation 3】 (In the formula, m1 and m2 are integers from 0 to 2, and n1 is an integer from 0 to 4 when m1 is 0, an integer from 0 to 6 when m1 is 1, and an integer from 0 to 8 when m1 is 2. When m2 is 0, n2 is an integer from 1 to 3 and n3 is an integer from 0 to 5, satisfying 1 ≤ (n2 + n3) ≤ 6. When m2 is 1, n2 is an integer from 1 to 3 and n3 is an integer from 0 to 7, satisfying 1 ≤ (n2 + n3) ≤ 8.) When m² is 2, n² is an integer from 1 to 3, and n³ is an integer from 0 to 9, satisfying 1 ≤ (n² + n³) ≤ 10. ５１ This is a C1-C10 hydrocarbyl group which may contain a halogen atom or a heteroatom. ５２ This is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a halogen atom or a heteroatom. When n1 is 2 to 8, each R ５２ These may be the same or different from each other. Also, multiple Rs ５２ However, they may bond with each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded. ５３ This is a C1-C10 hydrocarbylene group, which may contain heteroatoms. *3 and *4 represent the bonds with the carbon atoms of the aromatic ring in the formula. However, *3 and *4 are bonded to adjacent carbon atoms of the aromatic ring. R ６１ and R ６２ Each of these is independently a C1-C10 hydrocarbyl group which may contain a halogen atom or a heteroatom. ６１ and R ６２ However, they may bond with each other to form a ring together with the carbon atoms to which they are bonded and the atoms between the carbon atoms. When n2 is 2 to 3, each R ６１ and R ６２ These may be identical or different. ６３ This is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a halogen atom or a heteroatom. When n3 is 2 to 9, each R ６３ These may be the same or different from each other. Also, multiple Rs ６３ However, they may bond with each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded.

4. A laminate characterized by comprising a substrate and a resist film on the substrate which is a film formed from a 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. The laminate according to claim 4, characterized in that the resist film contains a ligand exchange reaction product between the hypervalent iodine compound and the carboxyl group-containing compound.

7. A pattern forming method characterized by comprising the steps of: forming a resist film on a substrate or on a resist underlayer of a substrate having a resist underlayer laminated thereon using a resist composition according to any one of claims 1 to 3; exposing the resist film with high-energy rays; and developing the exposed resist film using a developer.

8. The pattern formation method according to claim 7, characterized in that i-rays, KrF excimer laser light, ArF excimer laser light, electron beams, or extreme ultraviolet light are used as the high-energy rays.

9. The pattern forming method according to claim 7, characterized in that the developing solution used dissolves the exposed areas but does not dissolve the unexposed areas.

10. The pattern forming method according to claim 8, characterized in that the developing solution used dissolves the exposed areas but not the unexposed areas.

11. The pattern forming method according to claim 7, characterized in that the developing solution used dissolves the unexposed areas but not the exposed areas.

12. The pattern forming method according to claim 8, characterized in that the developing solution used dissolves the unexposed areas but not the exposed areas.

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