Resist composition and pattern forming method

Abstract

The invention relates to a resist composition and a pattern forming method. The present invention addresses the problem of providing a non-chemically amplified resist composition having excellent sensitivity and limit resolution in optical lithography using high-energy rays, and a pattern forming method using the resist composition. [Solution] The resist composition contains a polymer containing a repeating unit having a superatomic iodine structure represented by formula (1), a carboxyl group-containing compound, and a solvent.

Description

Technical Field

[0001] This invention relates to a resist composition and a method for forming a pattern. Background Technology

[0002] With the expansion of the IoT market, there is a growing demand for high integration, high speed, and low power consumption in LSI (Light Detector System), and the miniaturization of patterning is also progressing rapidly. In particular, logic devices are leading the way in miniaturization. Regarding the most advanced miniaturization technologies, mass production of 10nm node devices using ArF immersion lithography with dual, triple, and quadruple patterning is already underway. Furthermore, research is progressing on next-generation 7nm node devices using extreme ultraviolet (EUV) lithography with a wavelength of 13.5nm.

[0003] As miniaturization progresses, image blurring caused by acid diffusion has become a problem (Non-Patent Literature 1). To ensure the resolution of fine patterns with a processing size of 45 nm or less, it has been proposed that not only is the improvement of dissolution contrast, as previously advocated, important, but also the control of acid diffusion is crucial (Non-Patent Literature 2). However, since chemically amplified resist compositions improve sensitivity and contrast through acid diffusion, if acid diffusion is suppressed to the limit by lowering the post-exposure baking (PEB) temperature or shortening the PEB time, sensitivity and contrast will be significantly reduced.

[0004] Adding acid-generating agents that produce bulky acids is effective in suppressing acid diffusion. Therefore, it has been proposed to use onium salts of polymerizable olefins as acid-generating agents in polymer copolymerization. However, considering acid diffusion, in the patterning of resist films with dimensions smaller than 16 nm, it is believed that chemically amplified resist compositions are no longer suitable for patterning, and the development of non-chemically amplified resist compositions is desired.

[0005] Materials used in non-chemically amplified resist compositions include polymethyl methacrylate (PMMA). PMMA is a positive resist material whose main chain is broken and its molecular weight reduced by EUV irradiation, thereby improving its solubility in organic solvent developers.

[0006] Hydrosilsesquioxane (HSQ) is a negative resist material that is insoluble in alkaline developers, resulting from the crosslinking reaction of silanols produced by EUV irradiation. Chlorinated calixarnes also function as negative resist materials. These negative resist materials, due to their small molecular size before crosslinking and the absence of blurring caused by acid diffusion, can be used as pattern transfer materials with low edge roughness and very high resolution, showcasing the resolving limits of exposure devices. However, these materials have insufficient sensitivity and require further improvement.

[0007] One of the main reasons hindering material development for EUV lithography applications is the low photon count in EUV exposure. EUV energy is significantly higher than ArF excimer lasers, and the photon count in EUV exposure is only one-fourteenth that of ArF exposure. Furthermore, the size of patterns formed by EUV exposure is less than half that of ArF exposure. Therefore, EUV exposure is susceptible to variations in photon count. These variations in photon count in extremely short wavelength emission regions constitute shot noise, a physical phenomenon that cannot be eliminated. Thus, so-called stochastics are a concern. While the effects of shot noise cannot be eliminated, we will discuss how to reduce them. Due to shot noise, not only do dimensional uniformity (CDU) and linewidth roughness (LWR) increase, but there is also a one in a million chance of observing hole blockage. Hole blockage leads to poor conductivity and transistor malfunction, thus negatively impacting overall device performance. When considering practical sensitivity, resist compositions with PMMA and HSQ as the main components are significantly affected by stochastics and cannot achieve the desired resolution performance.

[0008] As a method to reduce the impact of shot noise in resists, the introduction of elements with high absorption in EUV light has attracted attention. Patent Document 1 proposes a chemically amplified resist composition containing iodine atoms with high absorption in EUV light. However, as mentioned above, chemically amplified resist compositions cannot achieve excellent resolution performance in EUV lithography with increasingly smaller processing dimensions. Especially in line and space patterns, as the pattern size decreases, pattern collapse and line breaks increase significantly, so reducing these issues is closely related to improving the limiting resolution.

[0009] Patent Document 2 proposes a negative resist composition using tin compounds. It uses tin, which has high absorption under EUV light, as its main component, thus improving stochastics and achieving high sensitivity and high resolution. However, such a metal resist suffers from several issues, including insufficient solubility in the resist solvent, storage stability, and defects caused by etching residue. Furthermore, since the exposed portion of the metal resist becomes a metal oxide and is therefore insoluble in the developer, an additional inversion process is required when using it for patterning contact holes, raising concerns about cost.

[0010] Existing technical documents

[0011] Patent documents

[0012] [Patent Document 1] Japanese Patent Application Publication No. 2018-5224

[0013] [Patent Document 2] Japanese Patent Publication No. 2021-503482

[0014] Non-patent literature

[0015] [Non-Patent Literature 1] SPIE Vol.5039p1 (2003)

[0016] [Non-Patent Literature 2] SPIE Vol.6520p65203L-1(2007) Summary of the Invention

[0017] [The problem that the invention aims to solve]

[0018] The present invention was made in view of the foregoing circumstances, and aims to provide a non-chemically amplified resist composition with excellent sensitivity and limiting resolution in optical lithography using high-energy rays, especially in electron beam (EB) lithography and EUV lithography, and to provide a patterning method using the resist composition.

[0019] [Methods for solving the problem]

[0020] After repeated and in-depth explorations to achieve the aforementioned objectives, the inventors have obtained the following insights, and thus completed this invention: a resist composition with polymers having a predetermined superatomic iodine structure and carboxyl-containing compounds as the main components can provide a resist film exhibiting excellent resolution, which is extremely effective for precision micro-machining.

[0021] That is, the present invention provides the following resist composition and pattern forming method.

[0022] 1. A resist composition comprising:

[0023] Polymers containing repeating units with a superatomic iodine structure as represented by formula (1),

[0024] Compounds containing carboxyl groups, and

[0025] Solvent.

[0026] [Chemistry 1]

[0027]

[0028] In the formula, m is 0 or 1. n is 0, 1, 2, 3 or 4 when m is 0, and 0, 1, 2, 3, 4, 5 or 6 when m is 1.

[0029] R A It can be a hydrogen atom, a halogen atom, a methyl group, or a trifluoromethyl group.

[0030] R 1 and R 2Each group consists independently of a halogen atom, or may contain heteroatoms, and is a hydrocarbon group with 1 to 10 carbon atoms. Also, R 1 and R 2 They can also bond to each other and form rings together with the carbon atoms they are bonded to and the atoms between those carbon atoms.

[0031] R 3 It is a hydrocarbon group with 1 to 20 carbon atoms, which may contain halogen atoms or heteroatoms.

[0032] 2. The resist composition as in 1, wherein the aforementioned carboxyl-containing compound is a polymer containing a repeating unit represented by formula (2) or a compound represented by formula (3).

[0033] [Chemistry 2]

[0034]

[0035] In the formula, R A It can be a hydrogen atom, a halogen atom, a methyl group, or a trifluoromethyl group.

[0036] X A It is a single bond, phenylene, naphthylene, or *-C(=O)-OX A1 -. X A1 It is a saturated hydrocarbon group, phenylene group, or naphthylene group having 1 to 10 carbon atoms, and the saturated hydrocarbon group may also contain a hydroxyl group, ether bond, ester bond, or lactone ring. * indicates an atomic bond with a carbon atom in the main chain.

[0037] k can be 1, 2, 3 or 4.

[0038] R 11 R is a k-valent hydrocarbon group with 1 to 40 carbon atoms or a k-valent heterocyclic group with 2 to 40 carbon atoms, where k is 2. 11 It can also be an ether bond, carbonyl group, azo group, thioether bond, carbonate bond, carbamate bond, sulfinyl group, or sulfonyl group. Furthermore, some or all of the hydrogen atoms of the aforementioned k-valent hydrocarbon group or k-valent heterocyclic group can be replaced by a group containing heteroatoms, and part of the -CH2- of the aforementioned k-valent hydrocarbon group can also be replaced by a group containing heteroatoms.

[0039] R 12 It is a single bond or a hydrocarbon group with 1 to 10 carbon atoms, and some or all of the hydrogen atoms of the hydrocarbon group can be replaced by a group containing a heteroatom, and part of the -CH2- of the hydrocarbon group can also be replaced by a group containing a heteroatom. When k is 2, 3 or 4, each R 12 They can be the same or different.

[0040] 3. A layered body, comprising:

[0041] substrate, and

[0042] A resist film obtained on the substrate from the resist composition as described in 1 or 2.

[0043] 4. The laminate as described in 3, wherein a lower film is provided between the aforementioned substrate and the aforementioned resist film.

[0044] 5. A laminate as described in 3 or 4, wherein the aforementioned resist film is formed by ligand exchange between the aforementioned superatomic iodine compound and a carboxyl-containing compound.

[0045] 6. A pattern forming method, comprising the following steps:

[0046] A resist film is formed on a substrate or on the lower layer of a substrate having a lower layer film, using a resist composition such as 1. or 2.

[0047] The aforementioned resist film was exposed to high-energy rays, and

[0048] The previously exposed resist film was developed using a developer.

[0049] [The effects of the invention]

[0050] The resist composition of the present invention is particularly useful in optical lithography using i-rays, KrF excimer lasers, ArF excimer lasers, EB or EUV, where it achieves both high sensitivity and high resolution to form fine patterns. Detailed Implementation

[0051] [Resist Composition]

[0052] The resist composition of the present invention contains a polymer having a predetermined superatomic iodine structure (hereinafter also referred to as a superatomic iodine-containing polymer) and a carboxyl-containing compound as the main components.

[0053] [Polymers containing superatomic iodine]

[0054] The aforementioned polymer containing superatomic iodine is a repeating unit with a superatomic iodine structure represented by the following formula (1).

[0055] [Chemistry 3]

[0056]

[0057] In equation (1), m is 0 or 1. n is 0, 1, 2, 3 or 4 when m is 0, and 0, 1, 2, 3, 4, 5 or 6 when m is 1.

[0058] In equation (1), R A It can be a hydrogen atom, a halogen atom, a methyl group, or a trifluoromethyl group.

[0059] In equation (1), R 1 and R2 Each group consists independently of a halogen atom, or may contain heteroatoms, and is a hydrocarbon group with 1 to 10 carbon atoms. Also, R 1 and R 2 They can also bond to each other and form rings together with the carbon atoms they are bonded to and the atoms between those carbon atoms.

[0060] R 1 and R 2 Specific examples of halogen atoms that can be represented include: fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.

[0061] R 1 and R 2 The hydrocarbon groups representing 1 to 10 carbon atoms can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, etc., alkyl groups with 1 to 10 carbon atoms; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norcamphenyl, tricyclic [5.2.1.0] 2,6 [Cyclic saturated hydrocarbon groups with 3 to 10 carbon atoms, such as decyl and adamantyl; alkenyl groups with 2 to 10 carbon atoms, such as vinyl and 2-propenyl; aryl groups with 6 to 10 carbon atoms, such as phenyl and naphthyl; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms in the aforementioned hydrocarbon groups may be replaced by groups containing heteroatoms such as oxygen, sulfur, nitrogen, or halogen atoms, and a portion of the -CH2- group in the aforementioned hydrocarbon groups may also be replaced by groups containing heteroatoms such as oxygen, sulfur, or nitrogen atoms. As a result, groups may contain hydroxyl, cyano, halogen, carbonyl, ether, thioether, ester, sulfonate, carbonate, carbamate, lactone ring, sulopentalide ring, carboxylic anhydride (-C(=O)-OC(=O)-), etc.] 1 and R 2 It should preferably be a hydrocarbon group with 1 to 4 carbon atoms.

[0062] In equation (1), R 3 It is a hydrocarbon group with 1 to 20 carbon atoms, which may contain halogen atoms or heteroatoms.

[0063] R 3 Specific examples of halogen atoms that can be represented include: fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.

[0064] R 3The hydrocarbon group represented can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, and other alkyl groups with 1 to 20 carbon atoms; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norcamphenyl, tricyclic [5.2.1.0] 2,6 [Cyclic saturated hydrocarbon groups with 3 to 20 carbon atoms, such as decyl and adamantyl; alkenyl groups with 2 to 20 carbon atoms, such as vinyl and 2-propenyl; aryl groups with 6 to 20 carbon atoms, such as phenyl and naphthyl; and groups obtained by combining them. Furthermore, some or all of the hydrogen atoms of the aforementioned hydrocarbon groups may be replaced by groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the -CH2- of the aforementioned hydrocarbon groups may also be replaced by groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms. As a result, hydroxyl groups, cyano groups, halogen atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonate bonds, carbonate bonds, carbamate bonds, lactone rings, sulopentalide rings, carboxylic anhydrides (-C(=O)-OC(=O)-), etc.]

[0065] Specific examples of the repeating unit represented by equation (1) are listed below, but are not limited to these. Additionally, in the following equation, R... A Same as above.

[0066] [Chemistry 4]

[0067]

[0068] The aforementioned polymers containing superatomic iodine may also contain repeating units other than those represented by formula (1) (hereinafter also referred to as other repeating units). There are no particular limitations on the aforementioned other repeating units, but they should preferably be those that can improve the solubility of polymers that are poorly soluble in solvents when containing only repeating units with superatomic iodine. Furthermore, the aforementioned other repeating units should preferably be repeating units with a ring structure that can be expected to have high etch resistance due to a rigid backbone, or repeating units with a styrene backbone as the main component.

[0069] Specific examples of the aforementioned repeating units may be listed below, but are not limited to these. Additionally, in the following formula, R... A As mentioned above, X B They are either -CH2- or -O-, respectively.

[0070] [Chemistry 5]

[0071]

[0072] [Chemistry 6]

[0073]

[0074] [Chemistry 7]

[0075]

[0076] [Chemistry 8]

[0077]

[0078] [Chemistry 9]

[0079]

[0080] [Chemistry 10]

[0081]

[0082] [Chemistry 11]

[0083]

[0084] [Chemistry 12]

[0085]

[0086] [Chemistry 13]

[0087]

[0088] [Chemistry 14]

[0089]

[0090] [Chemistry 15]

[0091]

[0092] [Chemistry 16]

[0093]

[0094] [Chemistry 17]

[0095]

[0096] [Chemistry 18]

[0097]

[0098] [Chemistry 19]

[0099]

[0100] [Chemistry 20]

[0101]

[0102] [Chemistry 21]

[0103]

[0104] [Chemistry 22]

[0105]

[0106] [Chemistry 23]

[0107]

[0108] [Chemistry 24]

[0109]

[0110] [Chemistry 25]

[0111]

[0112] [Chemistry 26]

[0113]

[0114] [Chemistry 27]

[0115]

[0116] [Chemistry 28]

[0117]

[0118] [Chemistry 29]

[0119]

[0120] [Chemistry 30]

[0121]

[0122] [Chemistry 31]

[0123]

[0124] [Chemistry 32]

[0125]

[0126] [Chemistry 33]

[0127]

[0128] [Chemistry 34]

[0129]

[0130] In the aforementioned polymers containing superatomic iodine, the molar ratio of the repeating unit represented by formula (1) to other repeating units should preferably be 10:90 to 90:10, more preferably 15:85 to 85:15, and even more preferably 20:80 to 80:20.

[0131] The weight-average molecular weight (Mw) of the aforementioned polymer containing superatomic iodine is preferably 1,000 to 500,000, and more preferably 3,000 to 100,000. Furthermore, in this invention, Mw is the polystyrene equivalent value determined by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

[0132] Furthermore, when the aforementioned polymers containing superatomic iodine have a wide molecular weight distribution (Mw / Mn), the presence of both low and high molecular weight polymers may lead to concerns about foreign matter being observed on the pattern and pattern shape deterioration after exposure. Therefore, as the pattern becomes more regular and refined, the influence of Mw and Mw / Mn tends to increase. Thus, in order to obtain a resist composition that can be ideally used for fine pattern sizes, the aforementioned polymers containing superatomic iodine should preferably have a narrow Mw / Mn dispersion of 1.0 to 2.0.

[0133] Examples of methods for synthesizing polymers containing superatomic iodine include: adding a free radical polymerization initiator to a monomer containing iodinated aryl groups in an organic solvent and heating it to polymerize it, thereby oxidizing the iodine site to produce a polymer containing superatomic iodine.

[0134] Organic solvents used in the polymerization reaction can include: anisole, 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), γ-butyrolactone (GBL), etc. Polymerization initiators mentioned above can include: 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylpentanonitrile), dimethyl-2,2-azobis(2-methylpropionate), 1,1'-azobis(1-acetoxy-1-phenylethane), benzoyl peroxide, lauroyl peroxide, etc. The amount of these initiators added relative to the total amount of monomers used to polymerize should preferably be 0.01–25 mol%. The reaction temperature should preferably be 50–150 °C, preferably 60–100 °C. The reaction time should be 2 to 24 hours, but from the perspective of production efficiency, 2 to 12 hours is better.

[0135] The aforementioned polymerization initiator can be added to the aforementioned monomer solution and supplied to the reactor, or a separate initiator solution different from the aforementioned monomer solution can be prepared and supplied to the reactor independently. Since there is a possibility that polymerization may proceed and generate ultra-high molecular weight polymers due to the generation of free radicals from the initiator during the standby time, from a quality management perspective, the monomer solution and initiator solution should preferably be prepared independently and added dropwise. Furthermore, to adjust the molecular weight, known chain transfer agents such as dodecyl mercaptan and 2-mercaptoethanol can also be used in combination. In this case, the amount of these chain transfer agents added, relative to the total amount of monomers used to polymerize, should preferably be 0.01–20 mol%.

[0136] In addition, the amount of each monomer in the aforementioned monomer solution can be appropriately set to achieve the ideal content ratio of the aforementioned repeating units.

[0137] The aforementioned polymers containing superatomic iodine can be used alone or in combination with two or more polymers having different composition ratios, Mw and / or Mw / Mn.

[0138] [Compounds containing carboxyl groups]

[0139] The aforementioned carboxyl-containing compounds are preferably polymers containing repeating units represented by formula (2) or compounds represented by formula (3).

[0140] [Chemistry 35]

[0141]

[0142] In equation (2), R A It can be a hydrogen atom, a halogen atom, a methyl group, or a trifluoromethyl group. X A It is a single bond, phenylene, naphthylene, or *-C(=O)-OX A1 -. X A1 It is a saturated hydrocarbon group, phenylene group, or naphthylene group having 1 to 10 carbon atoms, and the saturated hydrocarbon group may also contain a hydroxyl group, ether bond, ester bond, or lactone ring. * indicates an atomic bond with a carbon atom in the main chain.

[0143] In equation (3), k is 1, 2, 3 or 4.

[0144] In equation (3), R 11 R is a k-valent hydrocarbon group with 1 to 40 carbon atoms or a k-valent heterocyclic group with 2 to 40 carbon atoms, where k is 2. 11 It can also be an ether bond, carbonyl group, azo group, thioether bond, carbonate bond, carbamate bond, sulfinyl group, or sulfonyl group. Furthermore, some or all of the hydrogen atoms of the aforementioned k-valent hydrocarbon group or k-valent heterocyclic group can be replaced by a group containing heteroatoms, and part of the -CH2- of the aforementioned k-valent hydrocarbon group can also be replaced by a group containing heteroatoms.

[0145] R 12It is a single bond or a hydrocarbon group with 1 to 10 carbon atoms, and some or all of the hydrogen atoms of the hydrocarbon group can be replaced by a group containing a heteroatom, and part of the -CH2- of the hydrocarbon group can also be replaced by a group containing a heteroatom. When k is 2, 3 or 4, each R 12 They can be the same or different.

[0146] R 11 The kilovalent hydrocarbon group can be saturated or unsaturated, and can be linear, branched, or cyclic. The aforementioned kilovalent hydrocarbon group is a group obtained by removing k hydrogen atoms from a hydrocarbon. Examples of hydrocarbons mentioned include: alkanes with 1-40 carbon atoms, alkenes with 2-40 carbon atoms, alkynes with 2-40 carbon atoms, cyclic saturated hydrocarbons with 3-40 carbon atoms, cyclic unsaturated hydrocarbons with 3-40 carbon atoms, and aromatic hydrocarbons with 6-40 carbon atoms.

[0147] The aforementioned alkanes with 1 to 40 carbon atoms include: methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, and their structural isomers.

[0148] The aforementioned alkenes with 1 to 40 carbon atoms include: ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, decene, and their structural isomers.

[0149] The aforementioned alkynes with 1 to 40 carbon atoms can be listed as follows: acetylene, propyne, butyne, pentyne, hexyne, heptyne, octyne, nonyne, decyne, and their structural isomers.

[0150] Examples of cyclic saturated hydrocarbons with 3 to 40 carbon atoms include: cyclopropane, cyclobutane, cyclohexane, cycloheptane, cyclooctane, adamantane, norcamphene, etc.

[0151] Examples of cyclic unsaturated hydrocarbons with 3 to 40 carbon atoms include: cyclopropylene, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, and norcamphene.

[0152] Aromatic hydrocarbons with 6 to 40 carbon atoms mentioned above include: benzene, naphthalene, biphenyl, etc.

[0153] R 11 The k-valent heterocyclic group represents a group obtained by removing k hydrogen atoms from a heterocyclic compound. Examples of such heterocyclic compounds include furan, pyridine, pyrazole, and tetrahydrothiazole.

[0154] In the aforementioned kilocyclic hydrocarbon group or kilocyclic heterocyclic group, part or all of its hydrogen atoms may be replaced by groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, resulting in the presence of hydroxyl, cyano, fluorine, chlorine, bromine, iodine, etc. Furthermore, in the aforementioned kilocyclic hydrocarbon group, part of its -CH2- group may be replaced by groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, resulting in the presence of carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonate bonds, carbonate bonds, carbamate bonds, lactone rings, sulfonolactone rings, carboxylic anhydrides (-C(=O)-OC(=O)-), etc.

[0155] R 11 The derivatized hydrocarbon group can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include: methanediyl, ethane-1,1-diyl, ethane-1,2-diyl, propane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, nonane-1,9-diyl, decane-1,10-diyl, undecane-1, Alkyl groups with 1 to 20 carbon atoms, such as 11-diyl and dodecane-1,12-diyl; cyclic saturated alkylene groups with 3 to 20 carbon atoms, such as cyclopentanediyl, cyclohexanediyl, norcamphenediyl, and adamantanediyl; unsaturated aliphatic alkylene groups with 2 to 20 carbon atoms, such as vinylene and propylene-1,3-diyl; aryl groups with 6 to 20 carbon atoms, such as phenylene and naphthylene; and groups obtained by combining them. Furthermore, some or all of the hydrogen atoms in the aforementioned alkylene group may be replaced by groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and a portion of the -CH2- constituting the aforementioned alkylene group may also be replaced by groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms. As a result, it may contain hydroxyl groups, cyano groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonate bonds, carbonate bonds, carbamate bonds, lactone rings, sulcinolone rings, carboxylic anhydrides, etc.

[0156] Among the carboxyl-containing compounds represented by formula (3), k should preferably be 2, 3, or 4. In this case, considering that it is easy to form a high molecular weight, strong resist film, etch resistance, and developer resistance when mixed with superatomic iodine compounds, it is more ideal.

[0157] Specific examples of the repeating unit containing a carboxyl group represented by equation (2) are shown below, but are not limited thereto. Additionally, in the following equation, R... A Same as above.

[0158] [Chemistry 36]

[0159]

[0160] [Chemistry 37]

[0161]

[0162] Specific examples of the aforementioned carboxyl-containing compounds represented by formula (3) are listed below, but are not limited thereto.

[0163] [Chemistry 38]

[0164]

[0165] [Chemistry 39]

[0166]

[0167] [Chemistry 40]

[0168]

[0169] [Chemistry 41]

[0170]

[0171] [Chemistry 42]

[0172]

[0173] [Chemistry 43]

[0174]

[0175] Polymers containing carboxyl groups that contain repeating units represented by formula (2) may also contain repeating units other than those represented by formula (2) (hereinafter also referred to as other repeating units). There are no particular limitations on repeating units other than those represented by formula (2), but they should preferably be those that can improve the solubility of polymers that are poorly soluble in solvents when only repeating units with carboxyl groups are present. In addition, repeating units other than those represented by formula (2) should preferably be repeating units with a ring structure that can be expected to have high etch resistance due to a rigid backbone, or repeating units with a styrene backbone.

[0176] Specific examples of repeating units other than those represented by equation (2) can be listed and illustrated as examples of other repeating units that may also be contained in the aforementioned polymers containing superatomic iodine, but are not limited thereto.

[0177] In the aforementioned carboxyl-containing polymers, the molar ratio of carboxyl-containing repeating units to other repeating units should preferably be 10:90 to 90:10, more preferably 15:85 to 85:15, and even more preferably 20:80 to 80:20.

[0178] The weight-average molecular weight (Mw) of the aforementioned carboxyl-containing polymers is preferably between 1,000 and 500,000, and more preferably between 3,000 and 100,000. Furthermore, in this invention, Mw is the polystyrene equivalent value determined by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

[0179] Furthermore, when the aforementioned carboxyl-containing polymers have a wide molecular weight distribution (Mw / Mn), the presence of both low and high molecular weight polymers may lead to concerns about foreign matter being observed on the pattern after exposure and deterioration of the pattern shape. Therefore, as the pattern becomes more regular and refined, the influence of Mw and Mw / Mn tends to increase. Thus, in order to obtain a resist composition that can be ideally used for fine pattern sizes, the aforementioned carboxyl-containing polymers should preferably have a narrow dispersion of Mw / Mn of 1.0 to 2.0.

[0180] Examples of methods for synthesizing the aforementioned carboxyl-containing polymers include: polymerizing a monomer that provides the aforementioned repeating unit in an organic solvent by adding a free radical polymerization initiator and heating it.

[0181] Specific examples of organic solvents used in the polymerization reaction include: anisole, 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), γ-butyrolactone (GBL), etc. Specific examples of polymerization initiators include: 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylpentanonitrile), dimethyl-2,2-azobis(2-methylpropionate), 1,1'-azobis(1-acetoxy-1-phenylethane), benzoyl peroxide, lauroyl peroxide, etc. The amount of the aforementioned polymerization initiator added, relative to the total amount of monomers used to polymerize, should preferably be 0.01–25 mol%. The reaction temperature should preferably be 50–150 °C, preferably 60–100 °C. The reaction time should be 2 to 24 hours, but from the perspective of production efficiency, 2 to 12 hours is better.

[0182] The aforementioned polymerization initiator can be added to the aforementioned monomer solution and supplied to the reactor, or a separate initiator solution different from the aforementioned monomer solution can be prepared and supplied to the reactor independently. Since there is a possibility that polymerization may proceed and generate ultra-high molecular weight polymers due to the generation of free radicals from the initiator during the standby time, from a quality management perspective, the monomer solution and initiator solution should preferably be prepared independently and added dropwise. Furthermore, to adjust the molecular weight, known chain transfer agents such as dodecyl mercaptan and 2-mercaptoethanol can also be used in combination. In this case, the amount of the aforementioned chain transfer agent added, relative to the total amount of monomers used to polymerize it, should preferably be 0.01 to 20 mol%.

[0183] In addition, the amount of each monomer in the aforementioned monomer solution can be appropriately set to achieve the ideal content ratio of the aforementioned repeating units.

[0184] The aforementioned carboxyl-containing compounds may be used alone or in combination of two or more.

[0185] In the resist composition of the present invention, the molar ratio of the polymer containing superatomic iodine and the compound containing carboxyl groups (when the aforementioned compound containing carboxyl groups is a polymer, the molar ratio of the repeating unit containing superatomic iodine in the polymer to the repeating unit containing carboxyl groups in the polymer) is preferably 10:90 to 90:10, more preferably 20:80 to 80:20, and even more preferably 30:70 to 70:30.

[0186] [solvent]

[0187] The aforementioned resist composition contains a solvent. There are no particular limitations on the solvent being able to dissolve the aforementioned polymers containing superatomic iodine, carboxyl-containing compounds, and other components described below, and which can form a film. Such solvents are preferably organic solvents, such as: ketones like cyclohexanone, anisole, methyl-2-n-pentyl ketone, and methyl isopentyl ketone; alcohols like 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, diacetone alcohol, 4-methyl-2-pentanol, and methyl 2-hydroxyisobutyrate; and propylene glycol monomethyl ether, ethylene glycol monomethyl ether, and propylene glycol monoethyl ether. Ethers such as ethylene glycol monoethyl ether, 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 their mixed solvents, etc.

[0188] In the resist composition of the present invention, the content of the aforementioned solvent is preferably such that the concentration of the solid component 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. Furthermore, in the present invention, the solid component refers to the total components other than the solvent in the entire composition of the resist. The aforementioned solvent may be used alone or in combination of two or more.

[0189] [Other ingredients]

[0190] The aforementioned resist composition may also contain a surfactant. The surfactant is preferably a fluorinated and / or polysiloxane surfactant. Examples of such surfactants include those described in paragraph

[0276] of U.S. Patent Application Publication 2008 / 0248425. Alternatively, surfactants other than those described in paragraph

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

[0191] When the aforementioned resist composition contains the aforementioned surfactant, its content in the total solid components should preferably be 0.0001 to 2% by mass. The aforementioned surfactant may be used alone or in combination of two or more.

[0192] The aforementioned resist composition may also contain more free radical scavengers. By adding free radical scavengers, the photoresist reaction during optical lithography can be controlled and the sensitivity adjusted.

[0193] The aforementioned free radical scavengers include hindered phenols, quinones, hindered amines, and thiols. Specifically, hindered phenols include butylated hydroxytoluene (BHT) and 2,2'-methylenebis(4-methyl-6-tert-butylphenol). Quinones include 4-methoxyphenol and hydroquinone. Hindered amines include 2,2,6,6-tetramethylpiperidine and 2,2,6,6-tetramethylpiperidine-N-oxy radical. Thiols include dodecanethiol and hexadecanethiol.

[0194] When the aforementioned corrosion resist composition contains the aforementioned free radical scavenger, its content in the total solid components should preferably be 0.01 to 10% by mass. The aforementioned free radical scavenger can be used alone or in combination of two or more.

[0195] The aforementioned resist composition may also contain more crosslinking agents. By adding crosslinking agents, the crosslinking reaction during optical lithography can be promoted, the glass transfer points of the pattern can be improved, and patterns with excellent fine line resolution can be obtained.

[0196] The aforementioned crosslinking agents can include compounds with carbon-carbon unsaturated bonds as functional groups, such as vinyl, (meth)acrylate, allyl, alkynyl, and aromatic rings. Specifically, compounds with vinyl groups can include: chain alkenes, branched alkenes, cyclic alkenes, etc., which may also have substituents. Compounds with (meth)acrylate groups can include: acrylic acid, methacrylic acid, acrylates, methacrylates, etc., which may also have substituents. Compounds with allyl groups can include: allyl alcohols, allyl ethers, allyl esters, allyl amides, allylamines, isocyanurates containing allyl groups, etc. Compounds with alkynyl groups can include: chain alkynes, branched alkynes, cyclic alkynes, alkynyl alcohols, alkynyl ethers, alkynyl esters, alkynyl amides, alkynylamines, isocyanurates containing alkynyl groups, etc., which may also have substituents. Compounds containing aromatic rings include: aromatic hydrocarbons, heteroaromatic hydrocarbons, styrene, stilbene, phenylacetylene, acenaphthene, chalcone, etc., which may also contain substituents. Crosslinking agents may contain only one or more of the above functional groups. The number of the above functional groups in the crosslinking agent is preferably 1 or more and 10 or less, and more preferably 2 or more and 8 or less.

[0197] When the aforementioned resist composition contains the aforementioned crosslinking agent, its content in the total solid components should preferably be 0.01 to 50% by mass. The aforementioned crosslinking agent can be used alone or in combination of two or more.

[0198] When the aforementioned resist composition contains the aforementioned crosslinking agent, it may also contain a photopolymerization initiator. The photopolymerization initiator can generate free radicals by irradiation with high-energy rays and promote the crosslinking of the aforementioned crosslinking agent.

[0199] Specific examples of the aforementioned photopolymerization initiators include: benzophenone, methyl O-benzoylbenzoate, 4-benzoyl-4'-methyldiphenyl ketone, dibenzyl ketone, fluorenone, and other benzophenone derivatives; 2,2'-diethoxyacetophenone, 2-hydroxy-2-methylphenylacetone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinylpropane-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropanoyl)-benzyl]-phenyl}-2-methylpropane-1-one, methyl phenylglyoxylate, and other acetophenone derivatives; 9-thioxanone, 2-methyl-9-thio... 9-thioxanthone derivatives such as benzoyl, 2-isopropyl-9-thioxanthone, 4-isopropyl-9-thioxanthone, 2-chloro-9-thioxanthone, and diethyl-9-thioxanthone; benzoyl derivatives such as benzoyl, benzoyl dimethyl ketal, and benzoyl-β-methoxyethyl acetal; benzoin derivatives such as benzoin, benzoin methyl ether, and 2-hydroxy-2-methyl-1-phenylpropane-1-one; 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, and 1-phenyl-1,2-propanedione-2-(O-benzoyl)oxime. Oxime compounds such as 1,3-diphenylpropanetrione-2-(O-ethoxycarbonyl)oxime, 1-phenyl-3-ethoxypropanetrione-2-(O-benzoyl)oxime-1,2-octanedione, 1-[4-(phenylthio)-2-(O-benzoyl oxime)] ethyl ketone, and 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-1-(O-acetyl oxime); 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propane-1-one, and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropanoyl)-benzyl]phenyl}-2-methyl Propane and other α-hydroxy ketone compounds; 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)-butanone-1,2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)butane-1-one and other α-aminoalkylphenyl ketone compounds; bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzoyl diphenylphosphine oxide and other phosphine oxide compounds; bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)phenyl)titanium and other titanoceramsite compounds, etc.

[0200] When the aforementioned photopolymerization initiator is present in the aforementioned resist composition, its content in the total solids component is preferably 0.1–10% by mass, more preferably 0.1–5% by mass, and optimally 0.1–1% by mass. If it is 0.1% by mass or higher, the blending effect can be fully obtained.

[0201] As previously described, the aforementioned resist composition contains polymers containing superatomic iodine and carboxyl-containing compounds as main components, but does not contain polymers containing acid-instable groups or photoacid generators, as found in known chemically amplified resist compositions. However, the resist composition of the present invention, in particular, when exposed to EB or EUV, can form positive patterns where the exposed portions are soluble in the developer, or negative patterns where the exposed portions are insoluble in the developer. The mechanism is not fully elucidated, but is speculated, for example, as follows.

[0202] The repeating unit of the superatomic iodine structure represented by formula (1) has a tricoordinate structure with aryl and carboxylic acid ester ligands. It is believed that a polymer containing superatomic iodine with such repeating units, when mixed with a carboxyl-containing compound, will undergo an equilibrium reaction resulting in the exchange of carboxylic acid ester ligands. If the original carboxylic acid ester ligands can be removed by any method, a superatomic iodine compound with new ligands will be generated. For example, if poly(p-iodophenylacetate), which is a polymer containing superatomic iodine, is mixed with a carboxyl-containing compound, and the resulting low-boiling acetic acid is removed, ligand exchange will be completed. Here, the superatomic iodine-containing polymer will crosslink due to the carboxyl-containing compound, resulting in a polymer with a higher molecular weight.

[0203] The aforementioned cross-linked polymer is generated during film formation. This is because even if such a cross-linked polymer is synthesized beforehand, it is insoluble in almost all organic solvents, thus making solution preparation impossible. It is speculated that this is because the high polarization of the supraatomic iodine compound, which originally resulted in low solvent solubility, uses carboxyl-containing compounds as ligands, further worsening the solubility. Therefore, it is advisable to remove the original low-molecular-weight carboxylic acid components during film formation and the subsequent baking step, thereby completing the ligand exchange reaction and simultaneously forming the resist film.

[0204] In the resist film obtained from the resist composition of the present invention, the polymer containing superatomic iodine, which is its main component, decomposes under light, thereby changing its polarity and forming a pattern using a development step. The mechanism is not fully elucidated, but it is speculated, for example, as follows.

[0205] The resist composition of this invention can be either positive or negative depending on the choice of components. In the positive form, it contains a polymer bonded by a superatomic iodine compound during film formation. This polymer decomposes under light, converting into a monovalent iodine compound, while the bonds between the carboxyl-containing compound and the superatomic iodine compound are released, and the molecular weight decreases. It is presumed that this results in a positive pattern where the exposed areas are removed by the organic solvent.

[0206] On the other hand, when the film is negative, it contains polymers formed by cross-linking of superatomic iodine compounds generated during film formation. These polymers decompose under light, thereby causing the reconstruction of cross-links or bonds, and resulting in an increase in molecular weight and a polarity reversal. It is speculated that the result will be a negative pattern in which the unexposed areas are removed by the alkaline aqueous solution.

[0207] The polymer containing superatomic iodine used in this invention exhibits minimal volatility even under vacuum conditions during EB or EUV exposure. When using low-molecular-weight superatomic iodine compounds, the compounds decompose during exposure and volatilize under vacuum, causing significant exposure shrinkage of the resist film, contamination of the exposure unit by the volatile components, and dimensional changes due to resist pattern shrinkage. Therefore, the aforementioned problems are solved by using the superatomic iodine compounds used in this invention. Furthermore, by using high-molecular-weight polymers containing superatomic iodine, the glass transfer points of the pattern are improved, pattern distortion is prevented, resolution is improved, and etching resistance is also improved.

[0208] Based on the foregoing, it can be inferred that the resist composition of the present invention is a non-chemically amplified resist composition. In the resist composition of the present invention, polymers containing acid-instable groups, such as those found in chemically amplified resist compositions, or photoacid generators, are not necessary. Therefore, fine patterns can be resolved without the adverse effects of acid diffusion (e.g., image blurring).

[0209] The resist composition of this invention is particularly effective in EUV lithography. This is due to the presence of iodine atoms with high absorption capacity for EUV light. In other words, it reduces shot noise and achieves higher resolution and lower LWR.

[0210] Regarding EUV resist compositions capable of forming fine patterns, there have been reports of metal resists with tin compounds as the main component, which have a similar high absorption capacity for EUV light as iodine atoms (e.g., Patent Document 2). However, as mentioned above, such metal resists suffer from numerous problems, including insufficient solvent solubility, poor storage stability, and defects caused by etching residues due to the presence of metal elements. On the other hand, the resist composition of the present invention does not use metal elements, thus offering advantages over metal resists in terms of defects and eliminating problems with solvent solubility. Furthermore, the resist composition of the present invention is applicable in both positive and negative modes, thus having a wide range of uses. For example, in the contact hole formation step, metal resists implemented with negative development require a reversal process after pillar pattern formation, while positive resists do not require such a step. Therefore, from the viewpoint of process simplicity, the resist composition of the present invention is arguably more useful than metal resists.

[0211] Japanese Patent Application Publication Nos. 2015-180928 and 2018-95853 have disclosed resist compositions containing superatomic iodine compounds as additives, or resist compositions incorporating superatomic iodine compounds into the polymer backbone of a base polymer. However, regarding the characteristics of the resist compositions described in these patent documents, they only mention improving line edge roughness, but completely fail to mention the possibility of photodecomposition of the superatomic iodine compounds, or their potential to function as a non-chemically amplified resist composition. Furthermore, according to the descriptions and specific examples related to the doping amount, the superatomic iodine compounds are not the main component. Therefore, it is believed that these patent documents cannot conceive of a material like the one of the present invention, which can reduce shot noise in EUV lithography, and can form fine patterns in the case of a non-chemically amplified resist composition. That is, the present invention can be said to clearly provide a novel resist composition and a method for pattern formation.

[0212] [Pattern Formation Method]

[0213] When the resist composition of the present invention is used in the manufacture of various integrated circuits, known photolithography techniques can be employed. For example, regarding pattern formation methods, methods comprising the following steps can be listed:

[0214] A resist film is formed on a substrate or on the lower layer of a substrate having a lower layer film laminated using the aforementioned resist composition.

[0215] The aforementioned resist film was exposed to high-energy rays, and

[0216] The previously exposed resist film should be developed using a developer solution as needed.

[0217] First, the resist composition of the present invention is coated onto a substrate for integrated circuit manufacturing, or onto the lower layer film of a substrate with a stacked lower layer film (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflective film, etc.), or onto a substrate for shielding circuit manufacturing, or onto the lower layer film of a substrate with a stacked lower layer film (Cr, CrO, CrON, MoSi2, SiO2, etc.), using a suitable coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, or blade coating. The substrate is then pre-baked on a hot plate, preferably at 60–200°C for 10 seconds to 30 minutes, and more preferably at 80–180°C for 30 seconds to 20 minutes, to form a resist film with a thickness of 0.01–2 μm. Furthermore, the lower layer film refers to the film formed between the substrate and the resist film in a multilayer resist process; there are no particular limitations on the aforementioned lower layer film, and known types can be used.

[0218] Then, the aforementioned photoresist film is exposed using high-energy radiation. Examples of such high-energy radiation include: ultraviolet light, far ultraviolet light, EB, EUV, X-rays, soft X-rays, excimer lasers, gamma rays, and synchrotron radiation. When using ultraviolet light, far ultraviolet light, EUV, X-rays, soft X-rays, excimer lasers, gamma rays, or synchrotron radiation, either directly or using shielding to form the desired pattern, the exposure dose should be approximately 1–300 mJ / cm². 2 And preferably, it should be approximately 10–200 mJ / cm³. 2 Irradiation is performed in the manner described above. When using EB (exposed electron beams) for high-energy radiation, either directly or using a shield designed to form a specific pattern, the exposure dose should be approximately 0.1–8000 μC / cm². 2 And preferably, it is about 0.5 to 5000 μC / cm. 2 The resist composition of the present invention is particularly suitable for fine patterning under high-energy radiation, such as EB or EUV.

[0219] After exposure, PEB should be applied as needed. In this case, it is advisable to apply the PEB on a heated plate or in an oven at 30–200°C for 10 to 30 seconds, or more preferably at 60–120°C for 30 to 20 seconds.

[0220] After exposure or PEB, patterning can be achieved by developing with a developer as needed. The developing solutions used at this time can include: alkaline aqueous solutions such as tetramethylammonium hydroxide aqueous solution and tetrabutylammonium hydroxide aqueous solution; 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, 5-methyl-2-hexanone, methylcyclohexanone, acetophenone, methyl acetophenone, isopropanol, isoamyl alcohol, n-butanol, tert-butanol, tert-amyl alcohol, n-amyl alcohol, cyclohexanol, formic acid, acetic acid, propionic acid, propyl acetate, butyl acetate, isobutyl acetate, amyl acetate, butyl acetate, isoamyl acetate, butyl acetate, isoamyl acetate, cyclohexyl acetate, 4-tert-butylcyclohexyl acetate, octyl acetate, isoborneol acetate, propyl formate, butyl formate, isobutyl formate, amyl formate, methyl valerate, methyl valerate, methyl crotonate, ethyl crotonate, methyl propionate, ethyl propionate Esters, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isoamyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, ethyl phenylacetate, benzyl formate, ethyl formate, methyl 3-phenylpropionate, benzyl propionate, 2-phenylethyl acetate, 2-propanol, 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 3-methyl-1-butanol, diacetone alcohol, 4-methyl-2-pentanol, 3-methylcyclohexanol, 3,5,5-trimethylhexyl alcohol, 2,6-dimethyl-4-heptanol, toluene, anisole, ε-caprolactone, and other organic solvents. These developers can be used alone or in combination of two or more.

[0221] After development, rinsing should be performed as needed. The rinsing solution should be a solvent that is miscible with the developer and does not dissolve the resist film. Ideal solvents to use include: alcohols with 3 to 10 carbon atoms, ether compounds with 8 to 12 carbon atoms, alkanes, alkenes, alkynes, and aromatic solvents with 6 to 12 carbon atoms.

[0222] By performing rinsing, the collapse of the resist pattern and the occurrence of defects can be reduced. Furthermore, rinsing is not necessary, and by not performing rinsing, the amount of solvent used can be reduced.

[0223] Example

[0224] The present invention will be specifically described below with examples of synthesis, embodiments and comparative examples, but the present invention is not limited to the following embodiments.

[0225] In the following synthesis examples, the monomers used in the synthesis of the polymers are described below.

[0226] [Chemistry 44]

[0227]

[0228] [Chemistry 45]

[0229]

[0230] [Chemistry 46]

[0231]

[0232] [1] Synthesis of iodine-containing polymers

[0233] [Synthetic Example 1-1] Synthesis of iodine-containing polymer PI-2

[0234] Under nitrogen atmosphere, monomer I-1 (43g), monomer a-1 (57g), V-601 (manufactured by Fujifilm and Koimitsu Chemical Co., Ltd.) 4.2g, and MEK (160g) were measured in a flask to prepare a monomer-polymerization initiator solution. In another flask conditioned under nitrogen atmosphere, MEK (80g) was measured, and the mixture was heated to 80°C with stirring. The aforementioned monomer-polymerization initiator solution was then added dropwise over 4 hours. After the addition was complete, the temperature of the polymerization solution was maintained at 80°C and stirred continuously for 2 hours, then cooled to room temperature. The resulting polymerization solution was added dropwise to 4000g of vigorously stirred hexane, and the precipitated polymer was filtered. The obtained polymer was washed twice with hexane (1200g) and then vacuum dried at 50°C for 20 hours to obtain a white powdered polymer PI-2 (yield 92g, 92% yield). The Mw of polymer PI-2 was 7000, and the Mw / Mn ratio was 1.44. In addition, Mw is the polystyrene conversion value determined by GPC using THF as a solvent.

[0235] [Chemistry 47]

[0236]

[0237] [Synthetic Examples 1-2 to 1-8] Synthesis of polymers PI-1, PI-3 to PI-10 containing superatomic iodine

[0238] By changing the type and blending ratio of monomers, but otherwise using the same method as in Synthesis Example 1-1, the polymers shown in Table 1 below were synthesized.

[0239] [Table 1]

[0240]

[0241] [2] Synthesis of polymers containing superatomic iodine

[0242] [Synthetic Example 2-1] Synthesis of PH-2, a polymer containing superatomic iodine

[0243] Under nitrogen atmosphere, 10 g of polymer PI-2 and 100 g of acetic anhydride were mixed in a flask, and 18 g of 35% hydrogen peroxide solution was added dropwise at room temperature. The reaction solution was stirred at room temperature for 2 hours, then at 60°C for 5 hours, followed by stirring at room temperature for another 2 hours. Hexane was added to the resulting reaction solution, and the supernatant was removed, thereby obtaining 11.5 g of polymer PH-2 (94% yield) as an oil. The Mw of polymer PH-2 was 8600, and the Mw / Mn ratio was 1.44. Mw is a polystyrene conversion value determined by GPC using THF as a solvent.

[0244] [Chemistry 48]

[0245]

[0246] [Synthetic Examples 2-2 to 2-8] Synthesis of polymers PH-1 and PH-3 to PH-10 containing superatomic iodine

[0247] By changing the type of iodine-containing polymer used, the polymers shown in Table 2 below were synthesized using the same method as in Synthesis Example 2-1.

[0248] [Table 2]

[0249] Polymers containing superatomic iodine iodine-containing polymers Mw Mw / Mn PH-1 PI-1 10000 1.44 PH-2 PI-2 8600 1.44 PH-3 PI-3 11000 1.51 PH-4 PI-4 11000 1.42 PH-5 PI-5 10000 1.42 PH-6 PI-6 10000 1.44 PH-7 PI-7 11000 1.41 PH-8 PI-8 10000 1.49 PH-9 PI-9 11000 1.45 PH-10 PI-10 10000 1.40

[0250] [3] Synthesis of carboxyl-containing polymers

[0251] [Synthetic Example 3-1] Synthesis of Carboxyl-Containing Polymer P-1

[0252] Under nitrogen atmosphere, monomer b-4 (22g), monomer a-1 (78g), V-601 (manufactured by Fujifilm and Koimitsu Chemical Co., Ltd.) 5.4g, and MEK (160g) were measured in a flask to prepare a monomer-polymerization initiator solution. In another flask conditioned under nitrogen atmosphere, MEK (55g) was measured, and the mixture was heated to 80°C with stirring. The aforementioned monomer-polymerization initiator solution was then added dropwise over 4 hours. After the addition was complete, the temperature of the polymerization solution was maintained at 80°C and stirred continuously for 2 hours, then cooled to room temperature. The resulting polymerization solution was added dropwise to 4000g of vigorously stirred hexane, and the precipitated polymer was filtered. The obtained polymer was washed twice with hexane (1200g) and then vacuum dried at 50°C for 20 hours to obtain a white powder polymer P-1 (yield 100g, 98% yield). The Mw of polymer P-2 was 7000, and the Mw / Mn ratio was 1.44. In addition, Mw is the polystyrene conversion value determined by GPC using THF as a solvent.

[0253] [Chemistry 49]

[0254]

[0255] [Synthetic Examples 3-2 to 3-5] Synthesis of carboxyl-containing polymers P-2 to P-4, and comparative example polymer P-5.

[0256] By changing the types and blending ratios of the monomers, the polymers shown in Table 3 below were synthesized using the same method as in Synthesis Example 3-1.

[0257] [Table 3]

[0258]

[0259] [4] Preparation of the resist composition

[0260] [Examples 1-1 to 1-17, Comparative Examples 1-1 to 1-4]

[0261] The superatomic iodine compound and the carboxyl-containing compound were dissolved in a solvent containing 0.01% by mass of a surfactant (PF-636, manufactured by OMNOVA) according to the composition shown in Table 4 below. The resulting solution was filtered through a 0.2 μm Teflon (registered trademark) filter to obtain the resist compositions (R-01 to R-17, CR-01 and CR-02). Furthermore, the polymer, photoacid generator and sensitivity modifier were dissolved in a solvent containing 0.01% by mass of a surfactant (PF-636, manufactured by OMNOVA) according to the composition shown in Table 5 below. The resulting solution was filtered through a 0.2 μm Teflon (registered trademark) filter to obtain the resist compositions (CR-03 and CR-04).

[0262] [Table 4]

[0263]

[0264] [Table 5]

[0265]

[0266] In Tables 4 and 5, the superatomic iodine compound H-1, carboxyl-containing compounds m-1 to m-4, photoacid generator PAG-1, sensitivity modifier Q-1, and solvent are described below.

[0267] [Transformation 50]

[0268]

[0269] [Chemistry 51]

[0270]

[0271] [Chemistry 52]

[0272]

[0273] [Chemistry 53]

[0274]

[0275] Solvent: PGMEA (Propylene Glycol Monomethyl Ether Acetate)

[0276] AcOH (acetic acid)

[0277] GBL (γ-butyrolactone)

[0278] [5] Evaluation of EUV lithography (line and spacing patterns)

[0279] [Examples 2-1 to 2-17, Comparative Examples 2-1 to 2-4]

[0280] Each resist composition (R-01 to R-17, CR-01 to CR-04) was spin-coated onto a Si substrate containing Shin-Etsu Chemical Co., Ltd. silicon-containing spin-coated hard shielding SHB-A940 (silicon content 43% by mass) with a film thickness of 20 nm. A pre-baking (PAB) process was performed for 60 seconds at the temperatures listed in Table 6 using a heated plate to obtain a resist film with a thickness of 40 nm. The aforementioned resist film was then exposed to a 36 nm line-to-spacing (LS) 1:1 pattern using an ASML EUV scanning exposure machine NXE3400 (NA 0.33, σ 0.9, 90-degree dipole illumination). A PEB process was then performed on the heated plate at the temperatures listed in Table 6 for 60 seconds, followed by development for 30 seconds using the developer listed in Table 6, forming an LS pattern with a spacing width of 18 nm and a pitch of 36 nm.

[0281] The obtained resist patterns were evaluated as follows. The results are shown in Table 6.

[0282] [Sensitivity Evaluation]

[0283] The aforementioned LS pattern was observed using a Hitachi Advanced Technology Co., Ltd. (GAD) CG-6300 measuring SEM, and the optimal exposure Eop (mJ / cm²) for obtaining an LS pattern with a spacing width of 18nm and a pitch of 36nm was determined. 2 And make it a sensitivity.

[0284] [LWR Evaluation]

[0285] The dimensions of 10 points on an LS pattern obtained by exposure to the optimal amount of light along the length direction of the pitch width were measured using a Hitachi Advanced Technology Co., Ltd. The LWR was defined as three times the standard deviation (σ) obtained from the results (3σ). The smaller this value, the more uniform and less rough the pitch width pattern can be obtained.

[0286] [Evaluation of Extreme Resolution]

[0287] Using a Hitachi Advanced Technologies (AGT) CG-6300 long-range SEM, the limiting linewidth (nm) obtained by progressively increasing the exposure amount to form the aforementioned LS pattern was determined, and this limiting linewidth was set as the limiting resolution (nm). The smaller this value, the better the limiting resolution, and the finer the pattern can be formed.

[0288] [Table 6]

[0289]

[0290] Developer: nBA (Butyl acetate)

[0291] TMAH (2.38% by mass tetramethylammonium hydroxide aqueous solution)

[0292] As shown in Table 6, both positive and negative patterns can be formed depending on the developer used. Furthermore, when comparing Comparative Examples 2-1 and 2-2, which use low-molecular-weight superatomic iodine compounds, with the resist composition of the present invention, the present invention exhibits excellent resolution and LWR. Even when compared with Comparative Examples 2-3 and 2-4, which use chemically amplified resist compositions reacted with acid catalysts, the present invention still demonstrates excellent sensitivity, resolution, and LWR. Therefore, it can be concluded that the resist composition of the present invention exhibits excellent resolution in LS pattern formation under EUV exposure.

[0293] [6] Evaluation of EUV lithography (contact hole pattern)

[0294] [Examples 3-1 to 3-17, Comparative Examples 3-1 to 3-4]

[0295] Each resist composition (R-01 to R-17, CR-01 to CR-04) was spin-coated onto a Si substrate with a silicon-containing spin-coated hard shielding material (SHB-A940, 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd., with a film thickness of 20 nm. PAB was performed for 60 seconds at the temperature listed in Table 7 using a heated plate to obtain a resist film with a thickness of 50 nm. Then, the resist film was exposed using an ASML EUV scanning exposure machine NXE3400 (NA 0.33, σ 0.9 / 0.6, quadrupole illumination, wafer-level hole pattern shielding with a pitch of 64 nm and a +20% offset). PEB was then performed for 60 seconds on a heated plate at the temperature listed in Table 7, followed by 30 seconds of development using the developer listed in Table 7 to obtain a hole pattern with a size of 32 nm.

[0296] The obtained resist pattern was evaluated as follows. The results are shown in Table 7.

[0297] [Sensitivity Evaluation]

[0298] The aforementioned contact hole pattern was observed using a Hitachi Advanced Technology Co., Ltd. (HIT) CG-6300 SEM, and the optimal exposure value Eop (mJ / cm²) for obtaining a hole pattern with a size of 22nm was determined. 2 And make it a sensitivity.

[0299] [CDU Evaluation]

[0300] The dimensions of 50 hole patterns obtained by irradiation with the optimal exposure were measured, and the standard deviation (σ) of the results was defined as three times the value of 3σ (CDU). The smaller this value, the more uniform the hole diameter of the pattern can be obtained.

[0301] [Evaluation of Extreme Resolution]

[0302] Using a Hitachi Advanced Technologies (AGT) CG-6300 long-range SEM, the limiting aperture diameter (nm) was determined by progressively decreasing the exposure amount to form the aforementioned aperture pattern, starting from the optimal exposure. This value was then set as the limiting resolution (nm). The smaller this value, the better the limiting resolution, and the more finer the aperture pattern can be formed.

[0303] [Table 7]

[0304]

[0305] As shown in Table 7, both positive and negative patterns can be formed depending on the developer used. Furthermore, compared to Comparative Examples 3-1 and 3-2 using low molecular weight superatomic iodine compounds, the resist composition of the present invention exhibits excellent resolution and CDU. Even compared to Comparative Examples 3-3 and 3-4 using chemically amplified resist compositions reacted with acid catalysts, the present invention still demonstrates excellent sensitivity, resolution, and CDU. Therefore, it can be concluded that the resist composition of the present invention exhibits excellent resolution in the formation of contact hole patterns by EUV exposure.

Claims

1. A resist composition comprising: a polymer containing a repeating unit having a hypervalent iodine structure represented by the following formula (1), a carboxyl group-containing compound, and a solvent; in the formula, m is 0 or 1; n is 0, 1, 2, 3, or 4 when m is 0, and is 0, 1, 2, 3, 4, 5, or 6 when m is 1; R A is a hydrogen atom, a halogen atom, a methyl group or a trifluoromethyl group; R 1 and R 2 each independently is a halogen atom, or a hydrocarbon group having 1 to 10 carbon atoms which can also contain a hetero atom; and, R 1 and R 2 may be bonded to each other and form a ring together with the carbon atoms to which they are bonded and the atoms between the carbon atoms. R 3 A hydrocarbon group having a carbon number of 1 to 20 which can also contain heteroatoms, or a halogen atom.

2. The resist composition according to claim 1, wherein, the carboxyl group-containing compound is a polymer containing a repeating unit represented by the following formula (2) or a compound represented by the following formula (3); In the formula, R A It can be a hydrogen atom, a halogen atom, a methyl group, or a trifluoromethyl group; X A is a single bond, phenylene, naphthylene or *-C(=O)-O-X A1 -; X A1 is a saturated hydrocarbylene group having a carbon number of 1 to 10, phenylene or naphthylene, and the saturated hydrocarbylene group can also contain a hydroxyl group, an ether bond, an ester bond or a lactone ring; * indicates an atomic bond to a carbon atom of the main chain; k is 1, 2, 3, or 4; R 11 is a k-valent hydrocarbon group having a carbon number of 1 to 40 or a k-valent heterocyclic group having a carbon number of 2 to 40, and when k is 2, R 11 may also be an ether bond, a carbonyl group, an azo group, a sulfide bond, a carbonate bond, a carbamate bond, a sulfinyl group, or a sulfonyl group; further, a part or all of the hydrogen atoms of the k-valent hydrocarbon group or the k-valent heterocyclic group can be substituted with a heteroatom-containing group, and a part of -CH2- of the k-valent hydrocarbon group can also be substituted with a heteroatom-containing group; R 12 R is a single bond or a hydrocarbylene group having a carbon number of 1 to 10, and a part or all of the hydrogen atoms of the hydrocarbylene group can also be substituted with a heteroatom-containing group, and a part of the -CH2- of the hydrocarbylene group can also be substituted with a heteroatom-containing group; when k is 2, 3 or 4, each R 12 may be the same or different.

3. A laminate comprising: a substrate, and a resist film obtained from the resist composition according to claim 1 or 2 on the substrate.

4. The laminate according to claim 3, wherein a lower layer film between the substrate and the resist film.

5. The laminate according to claim 3, wherein the resist film is formed by ligand exchange of the hypervalent iodine compound and the carboxyl group-containing compound.

6. A pattern forming method comprising the steps of: forming a resist film on a substrate or a lower layer film of a substrate having the lower layer film using the resist composition according to claim 1 or 2, exposing the resist film to high-energy rays, and developing the exposed resist film using a developer.

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