Pattern forming method

Abstract

To provide a resist pattern forming method comprising a step of forming a positive-type or negative-type resist pattern by developing, by dry etching, a resist film after exposure using a non-chemically amplified resist composition excellent in sensitivity and ultimate resolution in photolithography using a high-energy ray.SOLUTION: A resist pattern forming method comprises: (i) forming a resist film on a substrate or on an underlying film of a substrate having the underlying film laminated thereon by using a resist composition comprising at least one hypervalent iodine compound selected from the hypervalent iodine compounds represented by formulae (1) and (2), a carboxylic acid compound, and a solvent; (ii) exposing the resist film to high-energy radiation; (iii) heating the exposed resist film; and (iv) developing the heated resist film by dry etching to form a resist pattern.SELECTED DRAWING: None

Description

[Technical Field]

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

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

[0003] Currently, the resist development process in semiconductor manufacturing is mainly carried out by a wet process (wet development, wet development) using an alkaline aqueous solution or organic solvent as the developer. However, as resist patterns become finer, development using a wet process is becoming increasingly susceptible to swelling of the pattern and the surface tension of the liquid.

[0004] In contrast to this, there is a method of development using a dry process (dry development) that uses an etching method that utilizes plasma. This dry process development is not affected by swelling of the pattern or the surface tension of the liquid. For this reason, development has been underway for some time to make the resist development process dry.

[0005] Patent Document 1 reports that by using a chemically amplified positive resist composition that employs a specific resin component, it is possible to form a high-resolution positive pattern by performing the resist film deposition, exposure, and post-exposure bake (PEB) steps just like a conventional wet process before the development step, and then performing only the development step using a dry process.

[0006] With the advancement of miniaturization, image blurring due to acid diffusion has become a problem with chemically amplified resist compositions (Non-Patent Document 1). It has been suggested that in order to ensure resolution in fine patterns with processing dimensions of 45 nm and below, not only is it important to improve dissolution contrast, as has been proposed in the past, but also to control acid diffusion (Non-Patent Document 2). However, because chemically amplified resist compositions increase sensitivity and contrast through acid diffusion, attempts to minimize acid diffusion by lowering the post-exposure bake (PEB) temperature or shortening the PEB time result in significant decreases in sensitivity and contrast.

[0007] Adding an acid generator that generates bulky acid is effective in suppressing acid diffusion. Therefore, copolymerization of an onium salt acid generator with a polymerizable olefin into a polymer has been proposed. However, for resist film pattern formation with feature sizes of 16 nm or less, it is believed that chemically amplified resist compositions cannot be used to form patterns due to acid diffusion, and the development of non-chemically amplified resist compositions is desired.

[0008] One material for non-chemically amplified resist compositions is polymethyl methacrylate (PMMA), a positive resist material whose main chain is cleaved by EUV irradiation, resulting in a decrease in molecular weight, which improves solubility in organic solvent developers.

[0009] Hydrogen silsesquioxane (HSQ) is a negative resist material that becomes insoluble in alkaline developers due to crosslinking caused by the condensation reaction of silanols generated by EUV irradiation. Chlorine-substituted calixarenes also function as negative resist materials. These negative resist materials have small molecular size before crosslinking and are free of blurring due to acid diffusion, resulting in low edge roughness and extremely high resolution, and are used as pattern transfer materials to indicate the resolution limit of exposure equipment. However, these materials have insufficient sensitivity, and further improvement is needed.

[0010] One of the challenges in developing materials for EUV lithography is the low photon count in EUV exposure. EUV energy is much higher than that of ArF excimer laser light, and the photon count in EUV exposure is one-fourteenth that of ArF exposure. Furthermore, the pattern dimensions formed with EUV exposure are less than half those of ArF exposure. This makes EUV exposure susceptible to variations in photon count. The variations in photon count in the extremely short wavelength radiation region are a physical phenomenon known as shot noise, and this effect cannot be eliminated. Therefore, so-called stochastics has attracted attention. While the effects of shot noise cannot be eliminated, methods for reducing this effect are being discussed. Shot noise not only increases dimensional uniformity (CDU) and line width roughness (LWR), but also causes hole blockage with a probability of one in several million. Blocked holes cause poor electrical conduction, preventing transistor operation and adversely affecting overall device performance. When considering practical sensitivity, resist compositions containing PMMA or HSQ as the main component are significantly affected by stochastics and are unable to achieve the desired resolution performance.

[0011] As a method for reducing the impact of shot noise on the resist side, the introduction of elements that have high absorption of EUV light has attracted attention. Patent Document 2 proposes a chemically amplified resist composition containing iodine atoms that have high absorption of EUV light. However, as mentioned above, chemically amplified resist compositions cannot achieve excellent resolution performance in EUV lithography, where processing dimensions will become increasingly finer in the future. In particular, in line and space patterns, as pattern dimensions become smaller, pattern collapse and breakage increase significantly, and reducing these problems leads to an improvement in limiting resolution.

[0012] Patent Document 3 describes a negative resist composition using a tin compound, and notes that the use of this resist composition enables development using a dry process. Because the resist composition contains tin, which has high absorption of EUV light, as its main component, stochastics are improved. Furthermore, because a dry process is used, there is no influence of swelling of the pattern or surface tension of the liquid, and high sensitivity and high resolution can be achieved. However, so-called metal resists of this type have many issues, such as storage stability and defects caused by post-etching residues. Furthermore, since metal resists are negative resists in which the exposed areas become insoluble in developer, primarily by becoming metal oxides, applying them to contact hole patterning requires an additional reversal process, which raises cost concerns. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] Japanese Patent Application Publication No. 2023-157346 [Patent Document 2] Japanese Patent Application Publication No. 2018-5224 [Patent Document 3] Special Publication No. 2022-538040 [Non-patent literature]

[0014] [Non-Patent Document 1] SPIE Vol. 5039 p1 (2003) [Non-patent document 2] SPIE Vol. 6520 p65203L-1 (2007) Summary of the Invention [Problem to be solved by the invention]

[0015] The present invention has been made in view of the above circumstances, and has an object to provide a method for forming a resist pattern in photolithography using high-energy rays, particularly electron beam (EB) lithography and EUV lithography, which comprises a step of using a non-chemically amplified resist composition that is excellent in sensitivity and limiting resolution, and developing an exposed resist film by dry etching to form a positive or negative resist pattern. [Means for solving the problem]

[0016] As a result of extensive research into achieving the above-mentioned object, the present inventors have discovered that a resist composition containing a predetermined hypervalent iodine compound and a carboxylic acid compound as its main components provides a resist film that exhibits extremely high sensitivity and excellent resolution, and that by using this resist composition for development by dry etching, a positive or negative resist pattern with a good pattern shape can be formed, which is extremely effective for precise microfabrication, and have thereby completed the present invention.

[0017] That is, the present invention provides the following method of forming a resist pattern. 1. (i) forming a resist film on a substrate or on an underlayer film of a substrate having an underlayer film laminated thereon, using a resist composition comprising at least one hypervalent iodine compound selected from the group consisting of hypervalent iodine compounds represented by the following formula (1) and hypervalent iodine compounds represented by the following formula (2), a carboxylic acid compound, and a solvent; (ii) exposing the resist film to high-energy radiation; (iii) a step of heating the exposed resist film; (iv) developing the heat-treated resist film by dry etching to form a resist pattern; A method for forming a resist pattern comprising the steps of: [ka] (In the formula, m is 0 or 1. When m is 0, n is an integer of 0 to 4, and when m is 1, n is an integer of 0 to 6. k is an integer of 0 to 5. R 1 is a hydrocarbyl group having 1 to 10 carbon atoms which may contain a halogen atom or a heteroatom. R 2 is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a halogen atom or a heteroatom. When n is 2 or more, each R 2 may be the same or different. 2 may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached. R 3 is a carbonyl group or a hydrocarbylene group having 1 to 10 carbon atoms which may contain a hetero atom. *1 and *2 represent bonds to carbon atoms of the aromatic ring in the formula, provided that *1 and *2 are bonded to adjacent carbon atoms of the aromatic ring. R 4 and R 5 are each independently a halogen atom or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. 4 and R 5 may be bonded to each other to form a ring together with the carbon atoms to which they are bonded and the atoms between said carbon atoms. R 6 is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a halogen atom or a heteroatom. When k is 2, 3, 4, or 5, each R 6 may be the same or different. 6 may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached. 2. The method for forming a resist pattern according to 1, wherein the carboxylic acid compound is represented by the following formula (3): [ka] (In the formula, p is an integer of 1 to 4. R 11 is a p-valent hydrocarbon group having 1 to 40 carbon atoms or a p-valent heterocyclic group having 2 to 40 carbon atoms, and when p is 2, R 11may be an ether bond, a carbonyl group, an azo group, a thioether bond, a carbonate bond, a carbamate bond, a sulfinyl group, or a sulfonyl group. Some or all of the hydrogen atoms of the p-valent hydrocarbon group or p-valent heterocyclic group may be substituted with a group containing a heteroatom, and some of the -CH2- groups of the p-valent hydrocarbon group may be substituted with a group containing a heteroatom. R 12 is a single bond or a hydrocarbylene group having 1 to 10 carbon atoms, and some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing a hetero atom, or some of the -CH2- of the hydrocarbylene group may be substituted with a group containing a hetero atom. When p is 2, 3, or 4, each R 12 may be the same as or different from each other.) 3. The method for forming a resist pattern according to 1 or 2, wherein the high-energy radiation is i-rays, KrF excimer laser light, ArF excimer laser light, electron beams or extreme ultraviolet rays. 4. The method for forming a resist pattern according to any one of 1 to 3, wherein in step (iv), the dry etching is carried out using a gas containing at least one selected from the group consisting of oxygen and tetrafluoromethane. [Effects of the Invention]

[0018] The resist composition of the present invention is extremely useful for forming fine patterns, achieving both high sensitivity and high resolution by using dry etching development, particularly in i-line, KrF excimer laser, ArF excimer laser, EB lithography, and EUV lithography. DETAILED DESCRIPTION OF THE INVENTION

[0019] [Resist composition] The resist composition used in the method of forming a resist pattern of the present invention contains a predetermined hypervalent iodine compound, a carboxylic acid compound, and a solvent.

[0020] [Hypervalent iodine compounds] The hypervalent iodine compound is a three-coordinate hypervalent iodine compound represented by the following formula (1) or (2). [ka]

[0021] In formula (1), m is 0 or 1. When m is 0, n is an integer of 0 to 4, and when m is 1, n is an integer of 0 to 6. n is preferably 0, 1, 2, 3, or 4, more preferably 0, 1, 2, or 3, even more preferably 0, 1, or 2, and most preferably 0 or 1.

[0022] In formula (1), R 1 is a hydrocarbyl group having 1 to 10 carbon atoms which may contain a halogen atom or a heteroatom. Specific examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The hydrocarbyl group having 1 to 10 carbon atoms may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 10 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, and an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, and a tricyclo[5.2.1.0 2,6] cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as a decanyl group or an adamantyl group; alkenyl groups having 2 to 10 carbon atoms, such as a vinyl group or an allyl group; aryl groups having 6 to 10 carbon atoms, such as a phenyl group or a naphthyl group; and groups obtained by combining these. In addition, some or all of the hydrogen atoms in the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms, nitrogen atoms, or halogen atoms, and some of the -CH2- groups in the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms, or nitrogen atoms, resulting in the hydrocarbyl groups containing hydroxy groups, cyano groups, halogen atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonate ester bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic anhydrides (-C(=O)-OC(=O)-), etc. 1 As the alkyl group, a hydrocarbyl group having 1 to 4 carbon atoms or a fluorinated hydrocarbyl group having 1 to 4 carbon atoms is preferred, and a hydrocarbyl group having 1 to 4 carbon atoms is more preferred.

[0023] In formula (1), R 2 is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a halogen atom or a heteroatom. Specific examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The hydrocarbyl group having 1 to 40 carbon atoms may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 40 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, and an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, and a tricyclo[5.2.1.0 2,6] cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms, such as a decanyl group, an adamantyl group, or an adamantylmethyl group; and aryl groups having 6 to 40 carbon atoms, such as a phenyl group, a naphthyl group, or an anthracenyl group. In addition, some or all of the hydrogen atoms in the hydrocarbyl group may be substituted with a group containing a heteroatom, such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- in the hydrocarbyl group may be substituted with a group containing a heteroatom, such as an oxygen atom, a sulfur atom, or a nitrogen atom, so that the hydrocarbyl group may contain a hydroxy group, a cyano group, a halogen atom, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), or the like. When n is 2 or more, each R 2 may be the same or different. 2 may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached.

[0024] In formula (1), R 3 is a carbonyl group or a hydrocarbylene group having 1 to 10 carbon atoms which may contain a heteroatom. The hydrocarbylene group having 1 to 10 carbon atoms may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkylene groups having 1 to 10 carbon atoms, such as methanediyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, propane-1,3-diyl group, propane-2,2-diyl group, butane-2,3-diyl group, butane-1,4-diyl group, 2-methylpropane-1,2-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, and decane-1,10-diyl group; cyclopentanediyl group, cyclohexanediyl group, norbornanediyl group, adamantanediyl group, and tricyclo[5.2.1.0]diyl group. 2,6]Cyclic saturated hydrocarbylene groups having 3 to 10 carbon atoms, such as a decanediyl group; alkenylene groups having 2 to 10 carbon atoms, such as a vinylene group or a propynylene group; arylene groups having 6 to 10 carbon atoms, such as a phenylene group, a methylphenylene group, an ethylphenylene group, an n-propylphenylene group, an isopropylphenylene group, an n-butylphenylene group or a naphthylene group; and groups obtained by combining these. In addition, some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- groups of the hydrocarbylene group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in the hydrocarbylene group containing a hydroxy group, a cyano group, a halogenated alkyl group, a halogen atom, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), or the like. 3 is preferably a carbonyl group, a hydrocarbylene group having 1 to 4 carbon atoms, or a fluorinated hydrocarbylene group having 1 to 4 carbon atoms.

[0025] In formula (1), *1 and *2 represent bonds to the carbon atoms of the aromatic ring in the formula. However, *1 and *2 are bonded to adjacent carbon atoms of the aromatic ring. The combinations of *1, *2, and m can have the following four patterns: [ka] (where n, R 2 and R 3 The dashed line indicates R 1 -C(=O)-O- represents a bond.)

[0026] In formula (2), k is an integer of 0 to 5.

[0027] In formula (2), R 4 and R 5 are each independently a halogen atom or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom.4 and R 5 may be bonded to each other to form a ring together with the carbon atoms to which they are bonded and the atoms between the carbon atoms. Specific examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The hydrocarbyl group having 1 to 10 carbon atoms may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 10 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, and an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, and a tricyclo[5.2.1.0 2,6 ] cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as a decanyl group or an adamantyl group; alkenyl groups having 2 to 10 carbon atoms, such as a vinyl group or an allyl group; aryl groups having 6 to 10 carbon atoms, such as a phenyl group or a naphthyl group; and groups obtained by combining these. In addition, some or all of the hydrogen atoms in the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms, nitrogen atoms, or halogen atoms, and some of the -CH2- groups in the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms, or nitrogen atoms, resulting in the hydrocarbyl groups containing hydroxy groups, cyano groups, halogen atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonate ester bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic anhydrides (-C(=O)-OC(=O)-), etc. 4 and R 5 As the alkyl group, a hydrocarbyl group having 1 to 4 carbon atoms or a fluorinated hydrocarbyl group having 1 to 4 carbon atoms is preferred, and a hydrocarbyl group having 1 to 4 carbon atoms is more preferred.

[0028] In formula (3), R 6is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a halogen atom or a heteroatom. When k is 2, 3, 4, or 5, each R 6 may be the same or different. 6 may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded. Specific examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The hydrocarbyl group having 1 to 10 carbon atoms may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 40 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, and an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, and a tricyclo[5.2.1.0 2,6 ] cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms, such as a decanyl group or an adamantyl group; alkenyl groups having 2 to 40 carbon atoms, such as a vinyl group or an allyl group; aryl groups having 6 to 40 carbon atoms, such as a phenyl group or a naphthyl group; and groups obtained by combining these. In addition, some or all of the hydrogen atoms in the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms, nitrogen atoms, or halogen atoms, and some of the -CH2- groups in the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms, or nitrogen atoms, resulting in the hydrocarbyl groups containing hydroxy groups, cyano groups, halogen atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonate ester bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic anhydrides (-C(=O)-OC(=O)-), etc. 6 is preferably a hydrocarbyl group having 1 to 4 carbon atoms.

[0029] Specific examples of the hypervalent iodine compound represented by formula (1) include, but are not limited to, the following: In the following formula, Me is a methyl group. [ka]

[0030] [ka]

[0031] [ka]

[0032] [ka]

[0033] [ka]

[0034] [ka] [ka]

[0035] [ka]

[0036] [ka]

[0037] [ka]

[0038]

change

[0039]

change

[0040]

change

[0041]

change

[0042]

change

[0043]

change

[0044]

change

[0045]

change

[0046]

change

[0047]

change

[0048]

change

[0049] [ka]

[0050] [ka]

[0051] [ka]

[0052] [ka]

[0053] [ka]

[0054] [ka]

[0055] [ka]

[0056] Specific examples of the hypervalent iodine compound represented by formula (2) include, but are not limited to, the following: [ka]

[0057] [ka]

[0058] [ka]

[0059] [ka]

[0060] [ka]

[0061] [ka]

[0062] [Carboxylic acid compounds] The carboxylic acid compound used in the present invention may be any carboxylic acid compound generally defined in organic chemistry, but is preferably one represented by the following formula (3). [ka]

[0063] In formula (2), p is an integer of 1 to 4. 11 is a p-valent hydrocarbon group having 1 to 40 carbon atoms or a p-valent heterocyclic group having 2 to 40 carbon atoms, and when p is 2, R 11 may be an ether bond, a carbonyl group, an azo group, a thioether bond, a carbonate bond, a carbamate bond, a sulfinyl group, or a sulfonyl group. In addition, some or all of the hydrogen atoms of the p-valent hydrocarbon group or p-valent heterocyclic group may be substituted with a group containing a heteroatom, and some of the -CH2- of the p-valent hydrocarbon group may be substituted with a group containing a heteroatom. R 12 is a single bond or a hydrocarbylene group having 1 to 10 carbon atoms, and some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing a hetero atom, or some of the -CH2- of the hydrocarbylene group may be substituted with a group containing a hetero atom. When p is 2, 3, or 4, each R 12 may be the same as or different from each other.

[0064] R11 The p-valent hydrocarbon group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. The p-valent hydrocarbon group is a group obtained by eliminating p hydrogen atoms from a hydrocarbon. Specific examples of the hydrocarbon include alkanes having 1 to 40 carbon atoms, alkenes having 2 to 40 carbon atoms, alkynes having 2 to 40 carbon atoms, saturated cyclic hydrocarbons having 3 to 40 carbon atoms, unsaturated cyclic hydrocarbons having 3 to 40 carbon atoms, and aromatic hydrocarbons having 6 to 40 carbon atoms.

[0065] Specific examples of the alkanes having 1 to 40 carbon atoms include methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, and structural isomers thereof.

[0066] Specific examples of the alkenes having 1 to 40 carbon atoms include ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, decene, and structural isomers thereof.

[0067] Specific examples of the alkyne having 1 to 40 carbon atoms include acetylene, propyne, butyne, pentyne, hexyne, heptyne, octyne, nonyne, decyne, and structural isomers thereof.

[0068] Specific examples of the cyclic saturated hydrocarbon having 3 to 40 carbon atoms include cyclopropane, cyclobutane, cyclohexane, cycloheptane, cyclooctane, adamantane, and norbornane.

[0069] Specific examples of the cyclic unsaturated hydrocarbon having 3 to 40 carbon atoms include cyclopropene, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, and norbornene.

[0070] Specific examples of the aromatic hydrocarbon having 6 to 40 carbon atoms include benzene, naphthalene, and biphenyl.

[0071] R 11The p-valent heterocyclic group represented by the following formula is a group obtained by eliminating p hydrogen atoms from a heterocyclic compound. Examples of the heterocyclic compound include furan, pyridine, pyrazole, and thiazolidine.

[0072] The p-valent hydrocarbon group or p-valent heterocyclic group may have some or all of its hydrogen atoms substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and as a result, may contain a hydroxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. The m-valent hydrocarbon group may have some of its -CH- groups substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, may contain a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), etc.

[0073] R 12The hydrocarbylene group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a nonane-1,9-diyl group, a decane-1,10-diyl group, an undecane-1,11-diyl group, a dodecane-1,1 alkanediyl groups having 1 to 20 carbon atoms, such as a 2-diyl group; cyclic saturated hydrocarbylene groups having 3 to 20 carbon atoms, such as a cyclopentanediyl group, a cyclohexanediyl group, a norbornanediyl group, and an adamantanediyl group; unsaturated aliphatic hydrocarbylene groups having 2 to 20 carbon atoms, such as a vinylene group and a propene-1,3-diyl group; arylene groups having 6 to 20 carbon atoms, such as a phenylene group and a naphthylene group; and groups obtained by combining these. In addition, some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, or some of the -CH- constituting the hydrocarbylene group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbylene group may contain a hydroxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride or the like.

[0074] Of 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, a strong resist film with a high molecular weight is easily formed, which is preferred from the viewpoints of etching resistance and developer resistance.

[0075] Specific examples of the carboxylic acid compound include, but are not limited to, the following: [ka]

[0076] [ka]

[0077] [ka]

[0078] [ka]

[0079] [ka]

[0080] [ka]

[0081] In the resist composition, the molar ratio of the hypervalent iodine compound to the carboxylic acid compound is preferably hypervalent iodine compound:carboxylic acid compound=10:90 to 90:10, more preferably 20:80 to 80:20, and even more preferably 30:70 to 70:30. The hypervalent iodine compound may be used alone or in combination of two or more. The carboxylic acid compound may be used alone or in combination of two or more.

[0082] [solvent] The resist composition contains a solvent. The solvent is not particularly limited as long as it can dissolve the hypervalent iodine compound, the carboxylic acid compound, and other components described below and can form a film. Such a solvent is preferably an organic solvent, and examples thereof include ketones such as cyclohexanone, methyl-2-n-pentyl ketone, and methyl isoamyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, diacetone alcohol, methyl 2-hydroxyisobutyrate, 4-methyl-2-pentanol, and methyl 2-hydroxyisobutyrate; propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, and ethylene glycol monoethyl ether. Examples of suitable solvents include ethers such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol mono-tert-butyl ether acetate; carboxylic acids such as formic acid, acetic acid, and propionic acid; lactones such as γ-butyrolactone; and mixed solvents thereof.

[0083] The content of the solvent in the resist composition is preferably an amount such that the solids concentration in the resist composition is 0.1 to 20 mass%, more preferably 0.1 to 15 mass%, and even more preferably 0.1 to 10 mass%. In the present invention, the solids are a collective term for all components of the resist composition other than the solvent. The solvents may be used alone or in combination of two or more.

[0084] [Other ingredients] The resist composition may further contain a surfactant. The surfactant is preferably a fluorine-based and / or silicon-based surfactant. Examples of such surfactants include those described in paragraph

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

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

[0085] When the resist composition contains the surfactant, the content thereof is preferably 0.0001 to 2 mass % of the total solid content. The surfactant may be used alone or in combination of two or more.

[0086] The resist composition may further contain a radical scavenger, which can control photoreactions during photolithography and adjust sensitivity.

[0087] Examples of the radical scavenger include hindered phenols, quinones, hindered amines, and thiol compounds. Specific examples of hindered phenols include dibutylhydroxytoluene (BHT) and 2,2'-methylenebis(4-methyl-6-tert-butylphenol). Examples of quinones include 4-methoxyphenol (methoquinone) and hydroquinone. Examples of hindered amines include 2,2,6,6-tetramethylpiperidine and 2,2,6,6-tetramethylpiperidine-N-oxy radical. Examples of thiols include dodecanethiol and hexadecanethiol.

[0088] When the resist composition contains the radical scavenger, the content thereof is preferably 0.01 to 10 mass % of the total solid content. The radical scavenger may be used alone or in combination of two or more.

[0089] The resist composition may further contain a crosslinking agent, which can accelerate the crosslinking reaction during photolithography and reduce the etch rate.

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

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

[0092] When the resist composition contains the crosslinking agent, it may further contain a photopolymerization initiator. The photopolymerization initiator generates radicals when irradiated with high-energy rays, and can promote crosslinking of the crosslinking agent.

[0093] Specific examples of the photopolymerization initiator include benzophenone, methyl O-benzoylbenzoate, 4-benzoyl-4'-methyldiphenyl ketone, dibenzyl ketone, fluorenone and other benzophenone derivatives; 2,2'-diethoxyacetophenone, 2-hydroxy-2-methylpropiophenone, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino acetophenone derivatives such as 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]-phenyl}-2-methylpropan-1-one and methyl phenylglyoxylate; thioxanthone derivatives such as thioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2-chlorothioxanthone and diethylthioxanthone; benzil, benzil dimethyl ketal ... Benzyl derivatives such as benzyl-β-methoxyethyl acetal; benzoin, benzoin methyl ether, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and other benzoin derivatives; 1-phenyl-1,2-butanedione-2-(O-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(O-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)oxime, 1-phenyl-1, Oxime compounds such as 2-propanedione-2-(O-benzoyl)oxime, 1,3-diphenylpropanetrione-2-(O-ethoxycarbonyl)oxime, 1-phenyl-3-ethoxypropanetrione-2-(O-benzoyl)oxime-1,2-octanedione, 1-[4-(phenylthio)-2-(O-benzoyloxime)]ethanone, and 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime);α-Hydroxyketone compounds such as 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]phenyl}-2-methylpropane; 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl) Examples of suitable compounds include α-aminoalkylphenone compounds such as butan-1-one; phosphine oxide compounds such as bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; and titanocene compounds such as bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium.

[0094] When the resist composition contains the photopolymerization initiator, its content is preferably 0.1 to 10 mass %, more preferably 0.1 to 5 mass %, and most preferably 0.1 to 1 mass %, based on the total solid content. When the content is 0.1 mass % or more, a sufficient blending effect can be obtained.

[0095] As described above, the resist composition contains a hypervalent iodine compound and a carboxyl group-containing polymer as main components, but does not contain an acid-labile group-containing polymer or a photoacid generator, as are contained in conventional chemically amplified resist compositions. However, the resist composition of the present invention can form a positive-tone pattern, in which the exposed portions are removed by development using a dry process, or a negative-tone pattern, in which the unexposed portions are removed by development using a dry process, particularly by exposure to EB or EUV. The mechanism behind this is not completely clear, but is presumed to be as follows, for example.

[0096] The hypervalent iodine compounds represented by formula (1) and formula (2) are tricoordinate compounds containing a carboxylate ligand. When such tricoordinate iodine compounds are mixed with a carboxylic acid compound, an exchange of the carboxylate ligand is thought to occur via an equilibrium reaction. If the original carboxylate ligand can be removed in some way, a hypervalent iodine compound containing a new ligand is generated. For example, by mixing iodobenzene diacetate, a relatively readily available hypervalent iodine compound, with a high molecular weight carboxylic acid compound and removing the resulting low-boiling acetic acid, the ligand exchange is completed. If the ligand has a sufficiently large molecular weight, a strong resist film can be formed. In particular, using a carboxylic acid compound containing multiple carboxy groups (e.g., a dicarboxylic acid compound) is thought to be able to form a high-molecular-weight polyester structure containing the hypervalent iodine compound, ensuring film formability.

[0097] Such a bond between a hypervalent iodine compound and a carboxylic acid compound is generated during film formation. That is, by removing the low-molecular-weight carboxylic acid component generated during film formation and the subsequent baking step, the ligand exchange reaction is completed and a resist film is formed.

[0098] The resist composition can be either positive or negative depending on the selection of components. In the case of a positive resist, the polymer contains a hypervalent iodine compound bonded to it during film formation. However, when this polymer is decomposed by light, it becomes a monovalent iodine compound, and at the same time, the bond between the carboxylic acid compound and the hypervalent iodine compound is released, resulting in a decrease in molecular weight. As a result, a difference in etching rate occurs between the exposed and unexposed areas, and it is presumed that a positive pattern is formed in which the film remains in the unexposed areas during development by a dry process.

[0099] On the other hand, negative-type films contain polymers crosslinked by hypervalent iodine compounds generated during film formation. When this polymer is decomposed by light, crosslinks or bonds are re-crosslinked, converting it into chemical species with a lower etching rate than unexposed areas. As a result, a difference in etching rate occurs between exposed and unexposed areas, and it is presumed that a negative-type pattern is formed in which the film in the exposed areas remains after development using a dry process.

[0100] Although the details of which components are required to produce a positive-type or negative-type resist film are unknown, whether the resist film obtained from the resist composition of the present invention is a positive-type resist film can be determined by the fact that the exposed areas are soluble in organic solvents, and that the exposed areas are insoluble in alkaline aqueous solutions, if the resist film is a negative-type resist film.

[0101] Based on the above speculation, it can be said that the resist composition of the present invention is a non-chemically amplified resist composition. Unlike conventional chemically amplified resist compositions, the resist composition of the present invention does not require an acid labile group-containing polymer or a photoacid generator, and therefore is free from adverse effects due to acid diffusion (e.g., image blurring) and is capable of resolving fine patterns.

[0102] The resist composition of the present invention is particularly effective in EUV lithography because it contains iodine atoms with high absorption capacity for EUV light, which reduces shot noise and enables the achievement of higher resolution and lower LWR.

[0103] Metal resists containing metal tin compounds as their main component, which have high absorption capacity for EUV light similar to that of iodine atoms, have been reported as EUV resist compositions capable of forming fine patterns (e.g., Patent Document 2). However, as mentioned above, such metal resists have many problems, such as insufficient solubility in solvents, poor storage stability, and defects due to post-etching residues caused by the presence of metal elements. On the other hand, the resist composition of the present invention is advantageous over metal resists in terms of defects because it does not contain metal elements, and it also has no issues with solubility in solvents. Furthermore, the resist composition of the present invention can be applied to both positive-tone and negative-tone resists, thereby offering a wide range of uses. For example, in the contact hole formation process, metal resists developed using negative-tone development require a reversal process step after pillar pattern formation, whereas positive-tone resists do not require such a step. Therefore, from the perspective of process simplicity, the resist composition of the present invention can be said to be more useful than metal resists.

[0104] Japanese Patent Publication No. 2015-180928 and Japanese Patent Publication No. 2018-95853 describe resist compositions containing a hypervalent iodine compound as an additive, and resist compositions incorporating a hypervalent iodine compound into the polymer backbone of a base polymer. However, these patent documents only describe the properties of the resist compositions as being able to improve line edge roughness, and make no mention of the possibility of the hypervalent iodine compound being photodecomposed or functioning as a material for a non-chemically amplified resist composition. Furthermore, according to the descriptions of the blending amounts and specific examples, the hypervalent iodine compound is not the main component. Therefore, these patent documents do not suggest a material that can reduce shot noise in EUV lithography and that can form fine patterns as a material for a non-chemically amplified resist composition, as described in the present invention. In other words, it can be said that the present invention clearly provides a novel resist composition and pattern formation method.

[0105] [Method for forming resist pattern] The pattern forming method of the present invention comprises the following steps (i) to (iv): (i) forming a resist film on a substrate, or on an underlayer film of a substrate having an underlayer film laminated thereon, using the resist composition; (ii) exposing the resist film to high-energy radiation; (iii) a step of heating the exposed resist film; (iv) After baking, the heat-treated resist film is developed by dry etching to form a resist pattern. It includes:

[0106] [Step (i)] Step (i) is a process of forming a resist film on a substrate or on an underlayer film of a substrate laminated with an underlayer film using the resist composition described above. Specifically, the resist composition is applied to a substrate for integrated circuit manufacturing, or to the underlayer film of a substrate laminated with an underlayer film (e.g., Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective coating), or to a substrate for mask circuit manufacturing, or to the underlayer film of a substrate laminated with an underlayer film (e.g., CrO, CrON, MoSi2, SiO2), using an appropriate coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, or doctor coating to a coating thickness of 0.01 to 2 μm. This is then pre-baked on a hot plate, preferably at 60 to 200°C for 10 seconds to 30 minutes, more preferably at 80 to 160°C for 30 seconds to 20 minutes, to form a resist film. The underlayer film means a film formed between the substrate and the resist film in a multi-layer resist process. There are no particular limitations on the underlayer film, and any conventionally known underlayer film can be used.

[0107] [Step (ii)] Step (ii) is a step of exposing the resist film to high-energy radiation. Specific examples of the high-energy radiation include ultraviolet radiation, far ultraviolet radiation, EB with an acceleration voltage of 1 to 150 kV, EUV radiation with a wavelength of 3 to 15 nm, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation. When ultraviolet radiation, far ultraviolet radiation, EUV radiation, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation are used as the high-energy radiation, the exposure dose is preferably 1 to 300 mJ / cm, either directly or using a mask for forming a desired pattern. 2 approximately, more preferably 10 to 200 mJ / cm 2 When EB is used as the high energy beam, the exposure dose is preferably 0.1 to 5000 μC / cm 2 either directly or using a mask for forming a desired pattern. 2 approximately, more preferably 0.5 to 3000 μC / cm 2 The resist composition of the present invention is particularly suitable for fine patterning using high-energy rays such as EB or EUV.

[0108] [Step (iii)] Step (iii) is the post-exposure bake (PEB) of the resist film. PEB can be performed using a hot plate, infrared radiation, laser radiation, hot air blowing, or by placing the wafer in an atmosphere at the baking temperature. Currently, most heating methods use a hot plate. By placing a substrate with a resist film formed on it on the hot plate, the resist film is heated by heat transfer from the substrate. The temperature to which the resist film is heated is adjusted by controlling the temperature of the hot plate.

[0109] The PEB temperature is preferably 30 to 170° C., more preferably 40 to 160° C., and even more preferably 50 to 150° C. The PEB treatment time is preferably 10 seconds to 30 minutes, and more preferably 10 seconds to 20 minutes.

[0110] After PEB, a process of exposing the entire surface of the resist film may be included. By exposing the entire surface, crosslinking progresses in the resist film, resulting in a film with higher etching resistance. For the entire surface exposure, the above-mentioned high-energy rays can be used, and it is particularly preferable to use ultraviolet rays, far ultraviolet rays, X-rays, soft X-rays, etc.

[0111] [Step (iv)] In step (iv), the PEB-treated resist film is developed by dry etching to form a resist pattern. When a positive resist composition is used, the exposed portions are removed to open spaces. When a negative resist composition is used, the unexposed portions are removed to open spaces.

[0112] Dry etching can be performed using a general dry etching apparatus in a chamber, for example, by reactive ion etching (RIE) using plasma containing a dry etching gas. The dry etching gas can be a mixed gas obtained by diluting a gas such as oxygen, hydrogen, ammonia, fluorocarbon, chlorine, or bromine with nitrogen, argon, helium, carbon dioxide, carbon monoxide, or sulfur dioxide. It is preferable to use a gas containing at least one selected from the group consisting of oxygen and tetrafluoromethane. In particular, from the viewpoint of ease of controlling the etching rate, it is preferable to use a mixed gas of oxygen and nitrogen or a mixed gas of tetrafluoromethane and nitrogen.

[0113] As dry etching conditions, for example, when a mixed gas of oxygen and nitrogen is used, the pressure inside the chamber is preferably 0.01 to 100 Pa, more preferably 0.1 to 30 Pa. The radio frequency (RF) power is preferably 50 to 1500 W, more preferably 150 to 1000 W. The bias power is preferably 0 to 300 W, more preferably 30 to 200 W. The flow rate of oxygen gas is preferably 3 to 300 sccm, more preferably 5 to 150 sccm. The flow rate of nitrogen gas is preferably 5 to 600 sccm, more preferably 10 to 500 sccm. The processing temperature during development is preferably -20 to 30°C, more preferably -10 to 30°C.

[0114] When a mixed gas of tetrafluoromethane and nitrogen is used, the pressure is preferably 0.01 to 100 Pa, more preferably 0.1 to 30 Pa. The high-frequency power is preferably 50 to 1500 W, more preferably 150 to 1000 W. The bias power is preferably 0 to 300 W, more preferably 30 to 200 W. The flow rate of tetrafluoromethane gas is preferably 3 to 300 sccm, more preferably 5 to 150 sccm. The flow rate of nitrogen gas is preferably 5 to 500 sccm, more preferably 10 to 300 sccm. The processing temperature during development is preferably -20 to 30°C, more preferably -10 to 30°C.

[0115] The dry etching time can be set appropriately, but is preferably about 30 to 300 seconds, and more preferably about 30 to 120 seconds.

[0116] The hole pattern or trench pattern after development can be shrunk by thermal flow, RELACS technology, or DSA technology. [Example]

[0117] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0118] [1] Preparation of resist composition [Examples 1-1 to 1-10, Comparative Examples 1-1 to 1-3] Resist compositions (R-01 to R-10) were prepared by dissolving a hypervalent iodine compound and a carboxylic acid compound in a solvent according to the compositions shown in Table 1 below, and filtering the resulting solution through a 0.2 μm Teflon (registered trademark) filter. Comparative resist compositions (CR-01 to CR-03) were also prepared by mixing a base polymer, a photoacid generator, a sensitivity adjuster, a solvent, and 0.01 mass% of a surfactant (PF-636, manufactured by Omnova) according to the compositions shown in Table 2 below, and filtering the resulting solution through a 0.2 μm Teflon (registered trademark) filter.

[0119] [Table 1]

[0120] [Table 2]

[0121] In Table 1, the hypervalent iodine compounds (I-1-1 to I-1-3, I-2-1), carboxylic acid compounds (CA-1 to CA-8), and solvents are as follows. [ka]

[0122] [ka]

[0123] Solvent: PGMEA (propylene glycol monomethyl ether acetate) AcOH (acetic acid) GBL (γ-butyrolactone)

[0124] The base polymer (P-1), photoacid generators (PAG-1, PAG-2), and sensitivity modifiers (Q-1, Q-2) in Table 2 are as follows: The weight average molecular weight (Mw) of the base polymer is a polystyrene-equivalent value measured by GPC using THF as a solvent. [ka]

[0125] [ka]

[0126] [ka]

[0127] [2] EUV lithography evaluation [Examples 2-1 to 2-10, Comparative Examples 2-1 to 2-3] Each resist material (R-01 to R-10, CR-01 to CR-03) was spin-coated onto a Si substrate coated with a 60-nm-thick anti-reflective coating (DUV-42) manufactured by Nissan Chemical Industries, Ltd., and pre-baked on a hot plate for 60 seconds at the temperature listed in Table 3 to produce a resist film with a thickness of 140 nm. This was then exposed to a 40-nm line-and-space (LS) 1:1 pattern using an EUV scanner NXE3400 (NA 0.33, σ 0.9, 90-degree dipole illumination) manufactured by ASML, and PEB was performed on a hot plate for 60 seconds at the temperature listed in Table 3.

[0128] After the PEB, dry etching was carried out using a dry etching apparatus Terius manufactured by Tokyo Electron Limited under the following conditions. Chamber pressure 12.0Pa RF power 600W Bias power 50W Stage temperature: 25℃ O2 gas flow rate 20sccm N2 gas flow rate: 400sccm Time 30sec

[0129] The resist film and anti-reflection film in the exposed areas were thinned by dry etching until the Si substrate surface was revealed.

[0130] Using a measuring SEM (CG-6300) manufactured by Hitachi High-Technologies Corporation, the exposure dose at which 40 nm lines and spaces were formed at a 1:1 ratio was used as the sensitivity of the resist film, and the wafer was cleaved, and the cross-sectional shape of the 40 nm line and space pattern was observed using an electron microscope (S-4800) manufactured by Hitachi High-Technologies Corporation. The results are also shown in Table 3.

[0131] [Table 3]

[0132] The results shown in Table 3 demonstrate that the use of a resist composition based on a hypervalent iodine compound and a carboxylic acid compound enables pattern formation by dry etching development. Furthermore, when the comparative chemically amplified positive resist composition was used, the pattern disappeared after dry etching, and a sufficient difference in etching rate between the exposed and unexposed areas was not obtained. Furthermore, it was also demonstrated that the use of a resist composition based on a hypervalent iodine compound and a carboxylic acid compound enables the formation of both positive and negative patterns by selecting the carboxylic acid compound used. Development by dry etching eliminates pattern collapse due to stress generated during spin drying in solution development, enabling the formation of patterns with higher aspect ratios and higher resolution.

Claims

1. (i) forming a resist film on a substrate or on an underlayer film of a substrate having an underlayer film laminated thereon, using a resist composition comprising at least one hypervalent iodine compound selected from the group consisting of hypervalent iodine compounds represented by the following formula (1) and hypervalent iodine compounds represented by the following formula (2): (ii) exposing the resist film to high-energy radiation; (iii) a step of heat-treating the exposed resist film; (iv) developing the heat-treated resist film by dry etching to form a resist pattern; A method for forming a resist pattern comprising the steps of: 【Chemical 1】 (In the formula, m is 0 or 1. When m is 0, n is an integer of 0 to 4, and when m is 1, n is an integer of 0 to 6.) R 1 is a hydrocarbyl group having 1 to 10 carbon atoms which may contain a halogen atom or a heteroatom. R 2 is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a halogen atom or a heteroatom. When n is 2 or more, each R 2 may be the same or different. 2 may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached. R 3 is a carbonyl group or a hydrocarbylene group having 1 to 10 carbon atoms which may contain a heteroatom. *1 and *2 represent bonds to carbon atoms of the aromatic ring in the formula, provided that *1 and *2 are bonded to adjacent carbon atoms of the aromatic ring. R 4 and R 5 are each independently a halogen atom or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. 4 and R 5 may be bonded to each other to form a ring together with the carbon atoms to which they are bonded and the atoms between said carbon atoms. R 6 is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a halogen atom or a heteroatom. When k is 2, 3, 4, or 5, each R 6 may be the same or different. 6 may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached.

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

3. 2. The method of forming a resist pattern according to claim 1, wherein the high-energy radiation is i-rays, KrF excimer laser light, ArF excimer laser light, electron beams or extreme ultraviolet rays.

4. 4. The method of forming a resist pattern according to claim 1, wherein in the step (iv), dry etching is carried out using a gas containing at least one selected from the group consisting of oxygen and tetrafluoromethane.

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