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 resolution in optical lithography using high-energy rays, and a pattern forming method using the resist composition. [Solution] The resist composition contains a superatomic iodine compound represented by formula (1), a carboxyl group-containing polymer, and a solvent.

Description

TECHNICAL FIELD

[0001] The present application relates to a resist composition and a pattern forming method. BACKGROUND

[0002] With the expansion of the IoT market, further requirements for high integration, high speed, and low power consumption of LSIs are being made, and the miniaturization of pattern rules is also rapidly progressing. In particular, logic devices are leading the miniaturization. As for the most advanced miniaturization technology, mass production of 10-nm-node devices by double patterning, triple patterning, and quadruple patterning of ArF immersion lithography is underway, and in addition, the exploration of 7-nm-node devices by the next-generation wavelength 13.5-nm extreme ultraviolet (EUV) lithography is progressing.

[0003] With the progress of miniaturization, blurring of images due to diffusion of acid also becomes a problem (Non-Patent Literature 1). In order to ensure resolution of fine patterns of 45 nm or less in processing size, it has been proposed that not only improvement of the dissolution contrast, which has been advocated in the past, but also control of acid diffusion is important (Non-Patent Literature 2). However, a chemically amplified resist composition improves sensitivity and contrast by diffusion of acid, so if acid diffusion is suppressed to the limit by lowering the post-exposure bake (PEB) temperature or shortening the PEB time, etc., the sensitivity and contrast will be significantly reduced.

[0004] It is effective to suppress acid diffusion by adding an acid generator that generates a bulky acid. Thus, it has been proposed to copolymerize an onium salt of a polymerizable olefin in a polymer to add an acid generator. However, in pattern formation of resist films of 16 nm or less in processing size, it is considered that from the viewpoint of acid diffusion, chemically amplified resist compositions have been unable to perform pattern formation, and development of non-chemically amplified resist compositions is expected.

[0005] A material for a non-chemically amplified resist composition can be exemplified by polymethyl methacrylate (PMMA). PMMA is a positive resist material that improves the solubility in a developer of an organic solvent by cleavage of the main chain and reduction of the molecular weight due to EUV irradiation.

[0006] Hydrogensiloxane (HSQ) is crosslinked by condensation reaction of silanol generated by EUV irradiation, and thereby becomes a negative resist material that is insoluble in an alkali developer. Also, a calixarene substituted with chlorine functions as a negative resist material. These negative resist materials, since the molecular size before crosslinking is small and there is no blurring due to acid diffusion, can be used as a pattern transfer material that is small in edge roughness and very high in resolution, and exhibits the resolution limit of an exposure device. However, these materials are insufficient in sensitivity, and further improvement is required.

[0007] A major cause of difficulty in developing materials for EUV lithography applications can be cited as the small number of photons in EUV exposure. The energy of EUV is much higher than that of ArF excimer laser, and the number of photons in EUV exposure is 1 / 14 of that in ArF exposure. In addition, the size of a pattern formed by EUV exposure is half or less than that of ArF exposure. Therefore, EUV exposure is easily affected by variations in the number of photons. Variations in the number of photons in the region of emitted light of an extremely short wavelength are shot noise, a physical phenomenon, and the effect cannot be eliminated. Therefore, so-called Stochastics is attracting attention. The effect of shot noise is discussed, but how to reduce the effect is not discussed. Due to the effect of shot noise, not only CDU (Critical Dimension Uniformity) and LWR (Line Width Roughness) become large, but also there is a probability of 1 in 1,000,000 that a hole blockage phenomenon is observed. If a hole is blocked, a transistor does not operate due to poor conduction, and therefore, the performance of the entire device is adversely affected. When considering the sensitivity in practical use, a resist composition in which PMMA and HSQ are used as main components is greatly affected by Stochastics, and it can be impossible to obtain a desired resolution capability.

[0008] As a method for reducing the effect of shot noise from the aspect of a resist, an element having a large absorption of EUV light is attracting attention. Patent Document 1 claims a chemically amplified resist composition containing an iodine atom having a large absorption of EUV light. However, as described above, a chemically amplified resist composition cannot achieve a good resolution capability in EUV lithography in which the processing size is increasingly miniaturized in the future.

[0009] Patent Document 2 claims a negative resist composition using a tin compound. This is because tin, an element having a large absorption of EUV light, is used as a main component, and therefore, Stochastics can be improved, and high sensitivity and high resolution can be achieved. However, such a metal resist has many problems such as insufficient solubility in a solvent for a resist, storage stability, and defects caused by a residue after etching.

[0010] In contrast, Patent Document 3 claims a positive resist composition using a hypervalent iodine compound. This is because an iodine element having a large absorption of EUV light is contained, and therefore, Stochastics can be improved as in the case of a metal resist, and high sensitivity and high resolution can be achieved. In addition, since only an organic molecule is used, the problems of a metal resist, that is, defects caused by solubility in a developer and a residue can be improved. However, the performance of a resist material has not been satisfactory so far, and development of a resist material useful in further miniaturized pattern formation is required.

[0011] Prior Art Documents

[0012] Patent Documents

[0013] [Patent Literature 1] Japanese Patent Application Laid-Open (JP A) No. 2018-5224

[0014] [Patent Literature 2] Japanese Patent Application Laid-Open (JP A) No. 2021-503482

[0015] [Patent Literature 3] Japanese Patent Application Laid-Open (JP A) No. 2023-167368

[0016] Non-Patent Literature

[0017] [Non-Patent Literature 1] SPIE Vol. 5039 p1 (2003)

[0018] [Non-Patent Literature 2] SPIE Vol. 6520 p65203L-1 (2007) SUMMARY

[0019] [Problems to be Solved by the Invention]

[0020] The present application has been achieved in view of the foregoing circumstances, and aims to provide a resist composition excellent in sensitivity and resolution in optical lithography using high-energy rays, particularly in electron beam (EB) lithography and EUV lithography, and to provide a pattern forming method using the resist composition.

[0021] [Means for Solving the Problems]

[0022] As a result of repeated and intensive studies in order to achieve the foregoing object, the present inventors have obtained the following insight, and thus completed the present application; a resist composition having, as main components, a hypervalent iodine compound having a predetermined carboxylate ligand and a carboxyl group-containing polymer can provide a resist film extremely high in sensitivity and exhibiting excellent resolution, and is extremely effective in precision fine processing.

[0023] That is, the present application provides the following resist composition and pattern forming method.

[0024] 1. A resist composition comprising:

[0025] a hypervalent iodine compound represented by the following formula (1),

[0026] a carboxyl group-containing polymer, and

[0027] a solvent.

[0028] [Chemical Formula 1]

[0029]

[0030] In the formula, m is 0 or 1. n is an integer of 0 to 4 when m is 0, and is an integer of 0 to 6 when m is 1.

[0031] R 1a halogen atom, or a hydrocarbon group having 1 to 10 carbons which can also contain a hetero atom.

[0032] R 2 a halogen atom, or a hydrocarbon group having 1 to 40 carbons which can also contain a hetero atom. When n is 2 or more, each R 2 may be the same or different. Also, a plurality of R 2 may be bonded to each other and form a ring together with the carbon atoms of the aromatic ring to which they are bonded.

[0033] R 3 a carbonyl group, or a hydrocarbylene group having 1 to 10 carbons which can also contain a hetero atom.

[0034] *1 and *2 represent atomic 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.

[0035] 2. The resist composition of 1, wherein the carboxyl group-containing polymer is one containing a repeating unit represented by the following formula (2).

[0036] [Chemical Formula 2]

[0037]

[0038] in the formula, R A is a hydrogen atom, a halogen atom, a methyl group or a trifluoromethyl group.

[0039] X A is a single bond, a phenylene group, a naphthylene group or *-C(=O)-O-X A1 -. X A1 is a saturated hydrocarbylene group having 1 to 10 carbons, a phenylene group or a naphthylene group, and the saturated hydrocarbylene group can also contain at least one selected from a hydroxyl group, an ether bond, an ester bond and a lactone ring. * represents an atomic bond to the carbon atom of the main chain.

[0040] 3. The resist composition of 1 or 2, further containing a hypervalent iodine compound represented by the following formula (3).

[0041] [Chemical Formula 3]

[0042]

[0043] in the formula, k is an integer of 0 to 5.

[0044] R 11 and R 12 are each independently a halogen atom, or a hydrocarbon group having 1 to 10 carbons which can also contain a hetero atom. Also, R 11 and R 12 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.

[0045] R 13 A halogen atom, or a hydrocarbon group having 1 to 40 carbon atoms which can also contain a hetero atom. When k is 2, 3, 4 or 5, each R 13 may be the same or different. Also, a plurality of R 13 may be bonded to each other and form a ring together with the carbon atoms of the aromatic ring to which they are bonded.

[0046] 4. A laminate comprising:

[0047] a substrate, and

[0048] a resist film on the substrate obtained from the resist composition according to any one of 1. to 3.

[0049] 5. The laminate according to 4, wherein a resist underlayer film is provided between the substrate and the resist film.

[0050] 6. A pattern forming method comprising the steps of:

[0051] forming a resist film on a substrate or on an underlayer film of a substrate having the underlayer film using the resist composition according to any one of 1. to 3.

[0052] exposing the resist film to high-energy rays, and

[0053] developing the exposed resist film using a developer.

[0054] 7. The pattern forming method according to 6, wherein the high-energy rays are electron beams or extreme ultraviolet rays.

[0055] 8. The pattern forming method according to 6 or 7, wherein the developer dissolves the exposed portions and does not dissolve the unexposed portions.

[0056] 9. The pattern forming method according to 6 or 7, wherein the developer dissolves the unexposed portions and does not dissolve the exposed portions.

[0057] 10. A laminate comprising a substrate and a resist film on the substrate, wherein the resist film is a polymer containing a repeating unit represented by the following formula (4).

[0058] [Chem. 4]

[0059]

[0060] wherein m is 0 or 1. n is an integer of 0 to 4 when m is 0, and is an integer of 0 to 6 when m is 1.

[0061] R 2a halogen atom, or a hydrocarbon group having 1 to 40 carbon atoms which can also contain a hetero atom. When n is 2 or more, each R 2 may be the same or different. Also, a plurality of R 2 may be bonded to each other and form a ring together with the carbon atoms of the aromatic ring to which they are bonded.

[0062] R 3 is a carbonyl group, or a hydrocarbylene group having 1 to 10 carbon atoms which can also contain a hetero atom.

[0063] *1 and *2 represent atomic 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.

[0064] R A is a hydrogen atom, a halogen atom, a methyl group or a trifluoromethyl group.

[0065] X A is a single bond, a phenylene group, a naphthylene group or *-C(=O)-O-X A1 -. X A1 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, and the saturated hydrocarbylene group can also contain at least one selected from the group consisting of a hydroxyl group, an ether bond, an ester bond and a lactone ring. * represents an atomic bond to a carbon atom of the main chain.

[0066] 11. The laminate according to 10, wherein a resist underlayer film is provided between the substrate and the resist film.

[0067] 12. A pattern forming method comprising the steps of:

[0068] exposing the resist film of the laminate according to any one of 10 or 11 to a high-energy ray, and

[0069] developing the exposed resist film using a developer.

[0070] 13. The pattern forming method according to 12, wherein the high-energy ray is an electron beam or an extreme ultraviolet ray.

[0071] 14. The pattern forming method according to 12 or 13, wherein the developer dissolves the exposed portion and does not dissolve the unexposed portion.

[0072] 15. The pattern forming method according to 12 or 13, wherein the developer dissolves the unexposed portion and does not dissolve the exposed portion.

[0073] [Effects of the Invention]

[0074] The resist composition of the present application is extremely useful in that it has both high sensitivity and high resolution, and forms a fine pattern, particularly in EB lithography and EUV lithography. DETAILED DESCRIPTION

[0075] [Resist composition]

[0076] The resist composition of the present invention contains a hypervalent iodine compound having a predetermined carboxylate ligand, a carboxyl group-containing polymer, and a solvent.

[0077] [Hypervalent iodine compounds]

[0078] The aforementioned hypervalent iodine compound is preferably a tricoordinate hypervalent iodine compound represented by the following formula (1).

[0079] [Chemistry 5]

[0080]

[0081] In formula (1), m is 0 or 1. n is an integer of 0 to 4 when m is 0, and an integer of 0 to 6 when m is 1. 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.

[0082] In formula (1), R 1 It is a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may also contain heteroatoms. Specific examples of the aforementioned halogen atom include: a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. The aforementioned hydrocarbon 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 methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, tricyclo[5.2.1.0 2,6 ] Cyclic saturated hydrocarbon groups having 3 to 10 carbon atoms, such as decyl and adamantyl; alkenyl groups having 2 to 10 carbon atoms, such as vinyl and allyl; aryl groups having 6 to 10 carbon atoms, such as phenyl and naphthyl; groups obtained by combining them, etc. In addition, part or all of the hydrogen atoms of the aforementioned hydrocarbon groups may be substituted by groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and part of the -CH2- of the aforementioned hydrocarbon groups may be substituted by groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, and 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, sultone rings, carboxylic anhydride (-C(=O)-OC(=O)-), etc. R 1 It is preferably a hydrocarbon group having 1 to 4 carbon atoms or a fluorinated hydrocarbon group having 1 to 4 carbon atoms, and more preferably a hydrocarbon group having 1 to 4 carbon atoms.

[0083] In formula (1), R 2It is a halogen atom or a hydrocarbon group having 1 to 40 carbon atoms which may also contain heteroatoms. Specific examples of the aforementioned halogen atom include: a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. The aforementioned hydrocarbon 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 methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, tricyclo[5.2.1.0 2,6 ] cyclic saturated hydrocarbon groups having 3 to 40 carbon atoms, such as decyl, adamantyl, and adamantylmethyl; aryl groups having 6 to 40 carbon atoms, such as phenyl, naphthyl, and anthracenyl. In addition, part or all of the hydrogen atoms of the aforementioned hydrocarbon groups may be substituted by groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and part of the -CH2- of the aforementioned hydrocarbon groups may be substituted by groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, and 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, sultone rings, carboxylic anhydride (-C(=O)-OC(=O)-), etc. When n is 2 or more, each R 2 They can be the same or different from each other. 2 They may also be bonded to each other and to the carbon atoms of the aromatic ring to which they are bonded to form a ring.

[0084] In formula (1), R 3 It 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, ethane-1,1-diyl, ethane-1,2-diyl, propane-1,1-diyl, propane-1,2-diyl, propane-1,3-diyl, propane-2,2-diyl, butane-2,3-diyl, butane-1,4-diyl, 2-methylpropane-1,2-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, nonane-1,9-diyl, and decane-1,10-diyl; cyclopentanediyl, cyclohexanediyl, norbornanediyl, adamantanediyl, tricyclo[5.2.1.0 2,6cyclohexylidene, cycloheptylidene, cyclooctylidene, cyclononylidene, cyclodecylidene, and the like. Also, part or all of the hydrogen atoms of the aforementioned alkylene group can be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, and the like, and part of the -CH2- of the aforementioned alkylene group can also be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, and the like, as a result of which it can also contain a hydroxyl 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 ester bond, a carbamate ester bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=0)-0-C(=0)-), and the like. R 3 It is preferably a carbonyl group, an alkylene group having 1 to 4 carbons, or a fluorinated alkylene group having 1 to 4 carbons.

[0085] In formula (1), *1 and *2 represent atomic bonds to carbon atoms of the aromatic ring in the formula. However, *1 and *2 are bonded to adjacent carbon atoms of the aromatic ring. The combinations of *1, *2, and m can be considered in the four patterns shown below.

[0086] [Chemical Formula 6]

[0087]

[0088] In the formula, n, R 2 and R 3 are the same as described above. The dotted line indicates an atomic bond to -C(=0)-0-. 1 -C(=0)-0-.

[0089] Specific examples of the hyperhalogen compound represented by formula (1) can include those shown below, but are not limited thereto. In the following formulae, Me is a methyl group.

[0090] [Chemical Formula 7]

[0091]

[0092] [Chemical Formula 8]

[0093]

[0094] [Chemical Formula 9]

[0095]

[0096] [Chemical Formula 10]

[0097]

[0098] [Chemical Formula 11]

[0099]

[0100] [Chemical Formula 12]

[0101]

[0102] [Chemical Formula 13]

[0103]

[0104] [Chemical Formula 14]

[0105]

[0106] [Chemical Formula 15]

[0107]

[0108] [Chemical Formula 16]

[0109]

[0110] [Chemical Formula 17]

[0111]

[0112] [Chemical Formula 18]

[0113]

[0114] [Chemical Formula 19]

[0115]

[0116] [Chemical Formula 20]

[0117]

[0118] [Chemical Formula 21]

[0119]

[0120] [Chemical Formula 22]

[0121]

[0122] [Chemical Formula 23]

[0123]

[0124] [Chemical Formula 24]

[0125]

[0126] [Chemical Formula 25]

[0127]

[0128] [Chemical 26]

[0129]

[0130] [Chemical 27]

[0131]

[0132] [Chemical 28]

[0133]

[0134] [Chemical 29]

[0135]

[0136] [Chemical 30]

[0137]

[0138] [Chemical 31]

[0139]

[0140] [Chemical 32]

[0141]

[0142] [Chemical 33]

[0143]

[0144] [Chemical 34]

[0145]

[0146] [Carboxyl group-containing polymer]

[0147] The aforementioned carboxyl group-containing polymer is preferably one containing a carboxyl group-containing repeating unit. The aforementioned carboxyl group-containing repeating unit is preferably one represented by the following formula (2).

[0148] [Chemical 35]

[0149]

[0150] In formula (2), R A is a hydrogen atom, a halogen atom, a methyl group or a trifluoromethyl group. X A is a single bond, a phenylene group, a naphthylene group or a *-C(=O)-O-X A1 - group. X A1which is a saturated hydrocarbylene group, phenylene group or naphthylene group having a carbon number of 1 to 10, and the saturated hydrocarbylene group can also have at least one selected from the group consisting of a hydroxyl group, ether bond, ester bond and lactone ring. * represents a bond to a carbon atom of the main chain.

[0151] Specific examples of the aforementioned carboxyl group-containing repeating unit can include the following, but are not limited thereto. In addition, in the following formulae, R A and the aforementioned are the same.

[0152] [Chemical Formula 36]

[0153]

[0154] [Chemical Formula 37]

[0155]

[0156] The aforementioned carboxyl group-containing polymer can also further contain a repeating unit other than the aforementioned carboxyl group-containing repeating unit (hereinafter also referred to as other repeating unit). The aforementioned other repeating unit is not particularly limited, and is preferably a repeating unit that can improve the solubility in a solvent of a polymer that is difficult to dissolve in a solvent when only the carboxyl group-containing repeating unit is present. Such a repeating unit is preferably a repeating unit having a hydrocarbon group having a carbon number of 1 to 20, which can also contain at least one selected from the group consisting of a halogen atom, hydroxyl group, cyano group, carbonyl group, nitro group, sulfonic acid group, amino group, isocyanate group, amide bond, imide bond, ester bond, ether bond, sulfide bond, carbonate bond, lactone ring and sultone ring.

[0157] Specific examples of the aforementioned other repeating unit can include the following, but are not limited thereto. In addition, in the following formulae, R A and the aforementioned are the same, X B are each independently -CH2- or -O-.

[0158] [Chemical Formula 38]

[0159]

[0160] [Chemical Formula 39]

[0161]

[0162] [Chemical Formula 40]

[0163]

[0164] [Chemical Formula 41]

[0165]

[0166] [Chemical Formula 42]

[0167]

[0168] [Chem. 43]

[0169]

[0170] [Chem. 44]

[0171]

[0172] [Chem. 45]

[0173]

[0174] [Chem. 46]

[0175]

[0176] [Chem. 47]

[0177]

[0178] [Chem. 48]

[0179]

[0180] [Chem. 49]

[0181]

[0182] [Chem. 50]

[0183]

[0184] [Chem. 51]

[0185]

[0186] [Chem. 52]

[0187]

[0188] [Chem. 53]

[0189]

[0190] [Chem. 54]

[0191]

[0192] [Chem. 55]

[0193]

[0194] [Chem. 56]

[0195]

[0196] [Chem. 57]

[0197]

[0198] [Chemical Formula 58]

[0199]

[0200] [Chemical Formula 59]

[0201]

[0202] [Chemical Formula 60]

[0203]

[0204] [Chemical Formula 61]

[0205]

[0206] [Chemical Formula 62]

[0207]

[0208] [Chemical Formula 63]

[0209]

[0210] [Chemical Formula 64]

[0211]

[0212] [Chemical Formula 65]

[0213]

[0214] [Chemical Formula 66]

[0215]

[0216] [Chemical Formula 67]

[0217]

[0218] The aforementioned carboxyl group-containing polymer preferably has a ratio (molar ratio) of the carboxyl group-containing repeating unit to the other repeating unit of 10:90 to 90:10, more preferably 15:85 to 85:15, and even more preferably 20:80 to 80:20.

[0219] The aforementioned carboxyl group-containing polymer preferably has a weight average molecular weight (Mw) of 1,000 to 500,000, and more preferably 3,000 to 100,000. In the present application, the Mw is a polystyrene-equivalent value measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

[0220] Further, in the aforementioned carboxyl group-containing polymer, when the molecular weight distribution (Mw / Mn) is wide, there are low-molecular-weight and high-molecular-weight polymers, and thus there are concerns that foreign matter is observed on a pattern after exposure, the pattern shape deteriorates, and the like. Therefore, as the pattern rule is made finer, the influence of Mw and Mw / Mn easily becomes large, and thus in order to obtain a resist composition that can be desirably used for a fine pattern size, the Mw / Mn of the aforementioned carboxyl group-containing polymer is preferably narrow and is preferably 1.0 to 2.0.

[0221] The aforementioned carboxyl group-containing polymer can be synthesized, for example, by a method in which a monomer that provides the aforementioned repeating unit is added with a radical polymerization initiator in an organic solvent and is subjected to heating to be polymerized.

[0222] Specific examples of the organic solvent used for the polymerization reaction include toluene, benzene, THF, diethyl ether, dioxane, cyclohexane, cyclopentane, methyl ethyl ketone (MEK), propylene glycol monomethyl ether acetate (PGMEA), γ-butyrolactone (GBL), and the like. Specific examples of the aforementioned polymerization initiator include 2,2'-azobis(isobutyronitrile) (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropanoate), 1,1'-azobis(1-acetoxy-1-phenylethane), benzoyl peroxide, lauryl peroxide, and the like. The addition amount of the aforementioned polymerization initiator is preferably 0.01 to 25 mol% with respect to the total of the monomers that are subjected to polymerization. The reaction temperature is preferably 50 to 150°C, and is more preferably 60 to 100°C. The reaction time is preferably 2 to 24 hours, and is more preferably 2 to 12 hours from the viewpoint of production efficiency.

[0223] The aforementioned polymerization initiator can be added to the aforementioned monomer solution and supplied to the reaction vessel, or an initiator solution that is different from the aforementioned monomer solution can be prepared and separately supplied to the reaction vessel. Since there is a possibility that polymerization proceeds and an ultrahigh-molecular-weight substance is generated due to radicals generated from the initiator in the waiting time, the monomer solution and the initiator solution are preferably prepared and added separately from the viewpoint of quality management. The acid-labile group can be directly used as one introduced into the monomer, or can be protected or partially protected after polymerization. Further, in order to adjust the molecular weight, a known chain transfer agent such as dodecyl mercaptan or 2-mercaptoethanol can also be used in combination. At this time, the addition amount of the aforementioned chain transfer agent is preferably 0.01 to 20 mol% with respect to the total of the monomers that are subjected to polymerization.

[0224] In addition, the amount of each monomer in the aforementioned monomer solution can be appropriately set, for example, in a manner that the desired content ratio of the aforementioned repeating unit is obtained.

[0225] In the resist composition of the present invention, the hypervalent iodine compound and the carboxyl group-containing polymer are preferably present in the polymer at a molar ratio of 10:90 to 90:10 relative to the carboxylic acid-containing repeating units, 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 carboxyl group-containing polymer may be used alone or in combination of two or more having different composition ratios, Mw values, and / or Mw / Mn values.

[0226] [Other hypervalent iodine compounds]

[0227] The resist composition of the present invention may also contain a hypervalent iodine compound represented by the following formula (3) (hereinafter also referred to as other hypervalent iodine compound). By adding other hypervalent iodine compounds, the reactivity to light can be controlled and the sensitivity can be adjusted.

[0228] [Chemistry 68]

[0229]

[0230] In formula (3), k is an integer from 0 to 5.

[0231] In formula (3), R 11 and R 12 are each independently a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may contain a hetero atom. 11 and R 12 They may also bond to each other and form a ring together with the carbon atoms to which they are bonded and the atoms between the carbon atoms. Specific examples of the aforementioned halogen atoms include: fluorine atom, chlorine atom, bromine atom, iodine atom, etc. The aforementioned hydrocarbon group having 1 to 10 carbon atoms may be saturated or unsaturated, and may be straight-chain, branched, or cyclic. Specific examples thereof include: alkyl groups having 1 to 10 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, tricyclo[5.2.1.0 2,6a carbon number of 6 to 10, such as phenyl, naphthyl, anthryl, and the like; a group obtained by combining them; and the like. Also, a part or all of the hydrogen atoms of the aforementioned hydrocarbon group can be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, and the like, and a part of -CH2- of the aforementioned hydrocarbon group can also be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, and the like, as a result of which it can also contain a hydroxyl 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 ester bond, a carbamate ester bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=0)-0-C(=0)-), and the like. R 11 and R 12 It is preferably a hydrocarbon group having a carbon number of 1 to 4 or a fluorinated hydrocarbon group having a carbon number of 1 to 4, and more preferably a hydrocarbon group having a carbon number of 1 to 4.

[0232] In formula (3), R 13 is a halogen atom, or a hydrocarbon group having a carbon number of 1 to 40 which can also contain a hetero atom. Specific examples of the aforementioned halogen atom can include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like. The aforementioned hydrocarbon group having a carbon number of 1 to 40 can be either saturated or unsaturated, and can be any of linear, branched, or cyclic. Specific examples thereof can include alkyl groups having a carbon number of 1 to 40 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 t-butyl group, an n-pentyl group, a t-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, an n-decyl group, and the like; cyclic saturated hydrocarbon groups having a carbon number of 3 to 40 such as 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, a tricyclo[5.2.1.02'6]decyl group, an adamantyl group, an adamantylmethyl group, and the like; aryl groups having a carbon number of 6 to 40 such as a phenyl group, a naphthyl group, an anthryl group, and the like; and a group obtained by combining them; and the like. Also, a part or all of the hydrogen atoms of the aforementioned hydrocarbon group can be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, and the like, and a part of -CH2- of the aforementioned hydrocarbon group can also be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, and the like, as a result of which it can also contain a hydroxyl 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 ester bond, a carbamate ester bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=0)-0-C(=0)-), and the like. 2,6 a carbon number of 6 to 10, such as phenyl, naphthyl, anthryl, and the like; a group obtained by combining them; and the like. Also, a part or all of the hydrogen atoms of the aforementioned hydrocarbon group can be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, and the like, and a part of -CH2- of the aforementioned hydrocarbon group can also be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, and the like, as a result of which it can also contain a hydroxyl 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 ester bond, a carbamate ester bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=0)-0-C(=0)-), and the like. R 13 may be the same as each other or different from each other, and also, a plurality of R 13 may also be bonded to each other and form a ring together with the carbon atoms of the aromatic ring to which they are bonded.

[0233] Specific examples of other hypervalent iodine compounds can include those shown below, but are not limited thereto.

[0234] [Formula 69]

[0235]

[0236] [Chemical Formula 70]

[0237]

[0238] [Chemical Formula 71]

[0239]

[0240] [Chemical Formula 72]

[0241]

[0242] [Chemical Formula 73]

[0243]

[0244] [Chemical Formula 74]

[0245]

[0246] [Chemical Formula 75]

[0247]

[0248] When the resist composition of the present application contains other hypervalent iodine compounds, the total content ratio of the hypervalent iodine compound represented by formula (1) in the aforementioned polymer and the aforementioned other hypervalent iodine compound with respect to the carboxylic acid-containing repeating unit is preferably 10:90 to 90:10, more preferably 20:80 to 80:20, and even more preferably 30:70 to 70:30, in terms of molar ratio. Further, the aforementioned other hypervalent iodine compound is preferably contained in a ratio of other hypervalent iodine compound: hypervalent iodine compound represented by formula (1) = 1:99 to 99:1, more preferably 1:99 to 50:50, in terms of molar ratio. The aforementioned other hypervalent iodine compound can be used alone or in combination of two or more kinds.

[0249] [Solvent]

[0250] The resist composition of the present application contains a solvent. The aforementioned solvent is not particularly limited as long as it can dissolve the hypervalent iodine compound represented by formula (1), the carboxyl group-containing polymer, other hypervalent iodine compounds, and other components described later and form a film. Such a solvent is preferably an organic solvent, and specific examples thereof include: ketones such as cyclohexanone, methyl-2-n-pentyl ketone, and methyl isobutyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, diacetone alcohol, 4-methyl-2-pentanol, and methyl 2-hydroxyisobutyrate; ethers such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, 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, t-butyl acetate, t-butyl propionate, and propylene glycol mono-t-butyl ether acetate; carboxylic acids such as formic acid, acetic acid, and propionic acid; lactones such as γ-butyrolactone; and mixed solvents thereof.

[0251] In the resist composition of the present application, the content of the aforementioned solvent is preferably an amount in which the concentration of solid components in the resist composition becomes 0.1 to 20% by mass, more preferably an amount in which the concentration of solid components in the resist composition becomes 0.1 to 15% by mass, and still more preferably an amount in which the concentration of solid components in the resist composition becomes 0.1 to 10% by mass. In addition, the solid components in the present application refer to the total of all components in the resist composition except for the solvent. The aforementioned solvent can be used alone as one kind or in combination with two or more kinds.

[0252] The resist composition of the present application can further contain a surfactant. The aforementioned surfactant is preferably a fluorine-based and / or silicone-based surfactant. Specific examples of such a surfactant include the surfactants described in paragraph

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

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

[0253] When the resist composition of the present application contains the aforementioned surfactant, the content thereof is preferably 0.0001 to 2% by mass in the total solid components. The aforementioned surfactant can be used alone as one kind or in combination with two or more kinds.

[0254] The resist composition of the present application can further contain at least one selected from the group consisting of a radical scavenger and a crosslinking agent. By this, the photo-reaction in the optical lithography can be controlled, and the sensitivity can be adjusted.

[0255] Specific examples of the aforementioned radical scavenger include hindered phenols, quinones, hindered amines, mercaptan compounds, and the like. Specifically, specific examples of the aforementioned hindered phenols include dibutylhydroxytoluene, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), and the like. Specific examples of the aforementioned quinones include 4-methoxyphenol (MEHQ), hydroquinone, and the like. Specific examples of the aforementioned hindered amines include 2,2,6,6-tetramethylpiperidine, 2,2,6,6-tetramethylpiperidine-N-oxyl, and the like. Specific examples of the aforementioned mercaptans include dodecanethiol, hexadecanethiol, and the like.

[0256] The resist composition of the present application contains the aforementioned radical scavenger, and the content thereof is preferably 0.01 to 10% by mass in the total solid content. The aforementioned radical scavenger can be used singly or in combination of two or more.

[0257] Specific examples of the aforementioned crosslinking agent include compounds having a carbon-carbon unsaturated bond such as a vinyl group, a (meth)acrylate group, an allyl group, an alkynyl group, or an aromatic ring as a functional group. Specifically, specific examples of the compound having a vinyl group include chain alkenes, branched alkenes, cyclic alkenes, and the like, which can have a substituent. Specific examples of the compound having a (meth)acrylate group include acrylic acid, methacrylic acid, acrylate esters, methacrylate esters, and the like, which can have a substituent. Specific examples of the compound having an allyl group include allyl alcohol, allyl ether, allyl ester, allyl amide, allyl amine, and isocyanurates having an allyl group, which can have a substituent. Specific examples of the compound having an alkynyl group include chain alkynes, branched alkynes, cyclic alkynes, alkynyl alcohol, alkynyl ether, alkynyl ester, alkynyl amide, alkynyl amine, and isocyanurates having an alkynyl group, which can have a substituent. Specific examples of the compound having an aromatic ring include arenes, heteroarenes, styrene, stilbene, phenylacetylene, acenaphthene, Chalcone, and the like, which can have a substituent. The crosslinking agent can have only one of the aforementioned functional groups or a plurality of them. The number of the aforementioned functional groups contained in the crosslinking agent is preferably 1 or more and 10 or less, and more preferably 2 or more and 8 or less.

[0258] The resist composition of the present application contains the aforementioned crosslinking agent, and the content thereof is preferably 0.01 to 50% by mass in the total solid content. The aforementioned crosslinking agent can be used singly or in combination of two or more.

[0259] The resist composition of the present application contains, as main components, a hypervalent iodine compound and a carboxyl group-containing polymer as described above, but does not contain a base polymer containing an acid-labile group, a photoacid generator, etc. as contained in a known chemically amplified resist composition. However, the resist composition of the present application, particularly when exposed to EB or EUV, can produce a difference in solubility between the exposed and unexposed portions, and form a positive or negative pattern. The mechanism thereof has not been fully elucidated, but it is, for example, presumed as follows.

[0260] The hypervalent iodine compound represented by formula (1) is a tridentate compound having a carboxylate ligand. Such a tridentate iodine compound is believed to undergo exchange of the carboxylate ligand in a counter reaction by mixing with a carboxylic acid compound. At this time, if the original carboxylate ligand can be removed by any method, a hypervalent iodine compound having a new ligand is produced. For example, 1-acetyloxy-1,2-benziodoxol-3-(1H)-one, which is easily obtained as a hypervalent iodine compound, is mixed with a carboxylic acid compound having a large molecular weight, and the produced acetic acid having a low boiling point is removed, whereby the ligand exchange is completed. Here, when the carboxylic acid compound is a polymer, a high molecular weight hypervalent iodine compound bonded to the polymer and the hypervalent iodine compound is produced.

[0261] The high molecular weight hypervalent iodine compound is produced at the time of film formation. The reason is that even if such a high molecular weight hypervalent iodine compound is synthesized in advance, it is not soluble in a plurality of organic solvents, and thus a solution cannot be prepared. It is presumed that this is because the hypervalent iodine compound inherently has low solvent solubility due to large polarization, and the high molecular weight body, i.e., the carboxylic acid-containing polymer, is used as a ligand, and thus the solubility is further deteriorated. Therefore, it is desirable to set a step in which the original low molecular carboxylic acid component is removed at the time of film formation and in a baking step thereafter, and the ligand exchange reaction is completed at the same time as the resist film is formed.

[0262] The resist film produced at this time is presumed to contain a polymer bonded to the carboxyl group-containing polymer and the hypervalent iodine compound. That is, the aforementioned polymer is presumed to contain a repeating unit represented by the following formula (4).

[0263] [Chem. 76]

[0264]

[0265] In the formula, m, n, R 2 , R 3 , *1, *2, R A , X A are the same as described above.

[0266] The resist film of the present application formed on a substrate in this way has a main component, i.e., a hypervalent iodine compound, which is decomposed by light, whereby the polarity is changed, and a pattern is formed by a developing step. In addition, by appropriately selecting a developer, a positive or negative pattern can be formed.

[0267] As described above, the resist composition of the present application is a non-chemically amplified resist composition. Since the base polymer, the photoacid generator, and the acid-labile group-containing acid in the resist composition of the present application are not necessary as in known chemically amplified resist compositions, adverse effects (e.g., blur) due to diffusion of the acid do not occur, and a fine pattern can be resolved.

[0268] The resist composition of the present application is particularly effective in EUV lithography. This is because the resist composition of the present application has iodine atoms having a high absorption ability for EUV light, and the hypervalent iodine compound represented by formula (1) has only one carboxylate ligand capable of causing ligand exchange, so that crosslinking of polymers with each other does not occur during film formation, and has a feature that polarity change is induced at a lower exposure amount compared to the case where only a hypervalent iodine compound is used. That is, the resist composition of the present application can achieve high sensitivity, high resolution, and low LWR by these features.

[0269] As a resist composition for EUV lithography in which a fine pattern can be formed, there is a report on a metal resist in which a metal tin compound having a high absorption ability for EUV light as well as iodine atoms is used as a main component (Patent Literature 2). However, as described above, such a metal resist has many problems such as insufficient solubility in a solvent, storage stability, and defects due to residues of metal elements after etching. On the other hand, the resist composition of the present application is more advantageous than the metal resist in terms of defects because it does not use metal elements, and the solubility in a solvent is also not a problem. In addition, the resist composition of the present application is applicable to either a positive or a negative type, and thus has a wide range of uses. For example, in a contact hole forming step, a metal resist developed in a negative type requires a reversal processing step after a column pattern is formed, but a positive resist does not require such a step. Therefore, the resist composition of the present application can also be said to be more useful than the metal resist in terms of ease of processing.

[0270] Patent Documents 1 and 2 describe resist compositions containing a hypervalent iodine compound as an additive, and a resist composition in which a hypervalent iodine compound is incorporated into the polymer skeleton of a base polymer. However, in these patent documents, in terms of the properties of the aforementioned resist compositions, only the improvement of line edge roughness is described, but there is no mention at all of the possibility that the hypervalent iodine compound will photodecompose, or the possibility of functioning as a material for a non-chemically amplified resist composition. Furthermore, according to the description and examples related to the amount of blending, the hypervalent iodine compound is not a main component. Also, Patent Document 3 claims a positive resist composition using a hypervalent iodine compound, but there is no description of the hypervalent iodine compound represented by formula (1) of the present invention, and there is no mention at all of the improvement of sensitivity and resolution by using such a compound. It is thus clear that from these patent documents, a non-chemically amplified resist composition that is extremely high in sensitivity and exhibits excellent resolution, and is extremely effective in precision fine processing, cannot be conceived. That is, the present invention can be said to provide a definitely novel resist composition and a pattern forming method.

[0271] [Pattern forming method]

[0272] When the resist composition of the present invention is used in the manufacture of various integrated circuits, a known photolithography technique can be used. For example, in terms of the pattern forming method, a method including the steps of forming a resist film on a substrate using the aforementioned resist composition, exposing the aforementioned resist film to high-energy rays, and developing the aforementioned exposed resist film as needed using a developer can be cited.

[0273] First, the resist composition of the present invention is applied to a substrate for integrated circuit manufacture, or to the underlayer film of a substrate having an underlayer film (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, an organic antireflection film, etc.) thereon, or to a substrate for mask circuit manufacture, or to the underlayer film of a substrate (Cr, CrO, CrON, MoSi2, SiO2, etc.) having an underlayer film thereon, by a suitable coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, blade coating, etc., in a manner so that the film thickness becomes 0.01 to 2 μm. This is prebaked on a hot plate, preferably at 60 to 200°C for 10 seconds to 30 minutes, and more preferably at 80 to 180°C for 30 seconds to 20 minutes, to form a resist film. In addition, the underlayer film means a film formed between the substrate and the resist film in a multilayer resist process, and the aforementioned underlayer film is not particularly limited, and known ones can be used.

[0274] Then, the aforementioned resist film is exposed to high energy rays. The aforementioned high energy rays can include ultraviolet rays, far ultraviolet rays, EB, EUV, X-rays, soft X-rays, excimer laser, γ-rays, synchrotron radiation, and the like. When the aforementioned high energy rays are ultraviolet rays, far ultraviolet rays, EUV, X-rays, soft X-rays, excimer laser, γ-rays, synchrotron radiation, and the like, the exposure is performed directly or using a mask for forming a desired pattern, with an exposure dose of preferably about 1 to 300 mJ / cm 2 and more preferably about 10 to 200 mJ / cm 2 . When the high energy rays are EB, the exposure is performed directly or using a mask for forming a desired pattern, with an exposure dose of preferably about 0.1 to 2000 μC / cm 2 and more preferably about 0.5 to 1500 μC / cm 2 . In addition, the resist composition of the present application is particularly suitable for fine patterning using EB or EUV among the high energy rays.

[0275] After the exposure, PEB is performed as necessary. At this time, the PEB is performed on a hot plate or in an oven after the exposure, with conditions of preferably 30 to 150°C for 10 seconds to 30 minutes and more preferably 60 to 120°C for 30 seconds to 20 minutes.

[0276] After the exposure or PEB, development is performed using a developer as necessary and patterning is performed. The developer used at this time can include an aqueous alkali solution such as a tetramethylammonium hydroxide aqueous solution; and an organic solvent such as 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, phenylacetone, methylphenylacetone, isopropyl alcohol, isopentyl alcohol, n-butyl alcohol, n-pentyl alcohol, cyclohexanol, propyl acetate, butyl acetate, isobutyl acetate, amyl acetate, butenyl acetate, isoamyl acetate, cyclohexyl acetate, propyl formate, butyl formate, isobutyl formate, amyl formate, isoamyl formate, methyl pentanoate, methyl pentenoate, methyl crotonate, ethyl crotonate, methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, amyl lactate, isoamyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, ethyl phenylacetate, benzyl formate, phenethyl formate, methyl 3-phenylpropionate, benzyl propionate, 2-phenylethyl acetate, 2-propanol, 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, diacetone alcohol, 4-methyl-2-pentanol, and the like. These developers can be used singly or in combination of two or more.

[0277] After development, rinsing is performed as needed. The rinsing solution should preferably be a solvent that is miscible with the developer and does not dissolve the resist film. Suitable solvents include alcohols with 3 to 10 carbon atoms, ether compounds with 8 to 12 carbon atoms, alkanes, alkenes, and alkynes with 6 to 12 carbon atoms, and aromatic solvents. Alternatively, water can be used as the rinsing solution in place of the organic solvent.

[0278] By performing rinsing, the occurrence of resist pattern collapse and defects can be reduced. In addition, rinsing is not essential, and by not performing rinsing, the amount of solvent used can be reduced.

[0279] Example

[0280] Hereinafter, the present invention will be described in detail with reference to synthesis examples, examples, and comparative examples. However, the present invention is not limited to the following examples.

[0281] [1] Synthesis of hypervalent iodine compounds

[0282] [Synthesis Example 1-1] Synthesis of Hypervalent Iodine Compound I-1

[0283] [Chemistry 77]

[0284]

[0285] In a solution in which 40 g of potassium peroxymonosulfate (Oxone) (registered trademark) was dissolved in 40 g of water, a solution in which 13.6 g of the raw material compound SM-1 (iodobenzoic acid) was dissolved in 40 g of acetonitrile was added dropwise at room temperature. After the addition, the mixture was stirred for 2 hours, and the precipitated solid was filtered. The obtained solid was washed with 40 mL of water, washed with 40 mL of acetone, and dried under reduced pressure at 40 ° C. to obtain the intermediate In-1 (yield 11.6 g, yield 81%) as a solid. Then, 8 g of In-1 and 27 mL of anhydrous acetic acid were mixed, stirred at 140 ° C. for 2 hours, the reaction solution was returned to room temperature, and the precipitated solid was filtered. The obtained solid was washed with diisopropyl ether and dried under reduced pressure at 40 ° C. to obtain the target hypervalent iodine compound I-1 (yield 7.0 g, yield 5%) as a solid.

[0286] The nuclear magnetic resonance spectrum of the hypervalent iodine compound I-1 ( 1 The measurement results of H-NMR / DMSO-d6) and single quadrupole mass spectrometry are shown below.

[0287] 1 H-NMR (500MHz, DMSO-d6) δ2.25(s,3H),7.75(m,1H),7.78(m,1H),8.05(m,2H)ppm.

[0288] Single quadrupole mass analysis (ESI): POSITIVE M + H + 307.0 (equivalent to C9H7IO4) [Synthesis Example 1-2] Synthesis of Hypervalent Iodine Compound I-2

[0289] [Chemistry 78]

[0290]

[0291] A hypervalent iodine compound I-2 was synthesized (yield 86%) in the same manner as in Synthesis Example 1-1 except that the raw material compound SM-2 was used in place of the raw material compound SM-1.

[0292] The nuclear magnetic resonance spectrum of the hypervalent iodine compound I-2 ( 1 The measurement results of H-NMR / DMSO-d6) and single quadrupole mass spectrometry are shown below.

[0293] 1 H-NMR (500MHz, DMSO-d6) δ2.21 (s, 3H), 7.61 (m, 1H), 7.72 (d, J = 8.2Hz, 1H), 7.95 (d, J = 4.2Hz, 1H) ppm.

[0294] Single quadrupole mass analysis (ESI): POSITIVE M + H + 325.0 (equivalent to C9H6FIO4)

[0295] [Synthesis Example 1-3] Synthesis of Hypervalent Iodine Compound I-3

[0296] [Chemistry 79]

[0297]

[0298] To a solution of 15 g of the raw material compound SM-3 dissolved in 40 g of acetonitrile was added 3.4 g of trichloroisocyanuric acid, and the mixture was stirred at room temperature for 30 minutes. The precipitated solid was filtered to obtain the intermediate In-3 (yield 10.6 g, 65%).

[0299] Next, 8 g of IM-3, 3.3 g of silver acetate, and 100 g of acetonitrile were mixed and stirred at room temperature for 10 hours. The precipitated solid was filtered. The resulting solid was extracted with acetonitrile, and the extract was distilled off under reduced pressure to obtain the target hypervalent iodine compound I-3 as a solid (yield 8.5 g, 100%).

[0300] The nuclear magnetic resonance spectrum of the hypervalent iodine compound I-3 ( 1The results of H-NMR / CDCl3) and single quadrupole mass analysis are shown below.

[0301] 1 H-NMR (500 MHz, CDCl3) δ 2.18 (s, 3H), 7.61-7.79 (m, 3H), 7.93 (d, J = 8.4 Hz, IH) ppm.

[0302] Single quadrupole mass analysis (ESI): POSITIVE M + H + 428.9 (corresponding to C 11 H8F6IO3)

[0303] [2] Synthesis of polymer

[0304] The monomers used for the synthesis of the polymer are described below.

[0305] [Chemical Formula 80]

[0306]

[0307] [Chemical Formula 81]

[0308]

[0309] [Chemical Formula 82]

[0310]

[0311] [Synthesis Example 2-1] Synthesis of Polymer P-1

[0312] A monomer-polymerization initiator solution was prepared by measuring monomer a-1 (56 g), monomer b-1 (105 g), V-601 (Fuji Photo Film Co., Ltd. and Otsuka Pharmaceutical Co., Ltd.) 5.4 g, and MEK 180 g in a flask under a nitrogen atmosphere. MEK 55 g was measured in another flask which had been adjusted to a nitrogen atmosphere, and the solution was heated to 80°C while stirring, and then the above monomer-polymerization initiator solution was added dropwise over 4 hours. After the dropwise addition was completed, the polymerization solution was continuously stirred for 2 hours while maintaining the temperature at 80°C, and then cooled to room temperature. The resulting polymerization solution was added dropwise to hexane 4000 g which was stirred vigorously, and the precipitated polymer was separated by filtration. The resulting polymer was washed twice with hexane 1200 g, and then vacuum dried at 50°C for 20 hours to obtain polymer P-1 (yield 155 g, yield 96%) as a white powder. The Mw of polymer P-1 was 7700, and Mw / Mn was 1.82. In addition, the Mw was a polystyrene conversion value measured by GPC using THF as a solvent.

[0313] [Chemical Formula 83]

[0314]

[0315] [Synthesis Examples 2-2 to 2-10] Synthesis of Polymers P-2 to P-10

[0316] The kind of each monomer and the blending ratio were changed, and otherwise, in the same manner as in Synthesis Example 1, polymers shown in Table 1 below were synthesized.

[0317] [Table 1]

[0318]

[0319] [3] Preparation of Resist Composition

[0320] [Examples 1-1 to 1-16, Comparative Examples 1-1 to 1-3]

[0321] An ultrahalogen compound, another ultrahalogen compound, and a polymer shown in Table 2 below were dissolved in a solvent containing 0.01 mass% of a surfactant (PF-636, manufactured by OMNOVA) to prepare a solution, and the solution was filtered with a Teflon (registered trademark) filter having a pore size of 0.2 μm, whereby a resist composition (R-01 to R-16) and a comparative resist composition (CR-01) were prepared. Also, a polymer, a photoacid generator, and a sensitivity adjustor shown in Table 3 below were dissolved in a solvent containing 0.01 mass% of a surfactant (PF-636, manufactured by OMNOVA) to prepare a solution, and the solution was filtered with a Teflon (registered trademark) filter having a pore size of 0.2 μm, whereby comparative resist compositions (CR-02 to CR-03) were prepared.

[0322] [Table 2]

[0323]

[0324]

[0325] [Table 3]

[0326]

[0327] In Tables 2 and 3, the other ultrahalogen compound O-1, the photoacid generator PAG-1, the sensitivity adjustor Q-1, and the solvent are as described below.

[0328] [Chemical Formula 84]

[0329]

[0330] [Chemical Formula 85]

[0331]

[0332] [Chem. 86]

[0333]

[0334] • Solvent: PGMEA (propylene glycol monomethyl ether acetate)

[0335] AcOH (acetic acid)

[0336] HBM (methyl 2-hydroxyisobutyrate)

[0337] PA (propionic acid)

[0338] GBL (γ-butyrolactone)

[0339] [4] EUV lithography evaluation (line and space pattern, positive tone development)

[0340] [Examples 2-1 to 2-16, Comparative Examples 2-1 to 2-3]

[0341] Each of the resist compositions (R-01 to R-16, CR-01 to CR-03) was spin-coated on a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content: 43 mass%) manufactured by Showa Denko K.K. was formed in a film thickness of 20 nm, and prebaked (PAB) at the temperature described in Table 4 for 60 seconds using a hot plate to produce a resist film having a film thickness of 40 nm. After exposure of a 36-nm line and space (LS) 1:1 pattern using an EUV scanning exposure machine NXE3400 (NA 0.33, σ 0.9, 90-degree dipole illumination) manufactured by ASML, PEB was performed on a hot plate at the temperature described in Table 4 for 60 seconds, and then development was performed using the developer described in Table 4 for 30 seconds to form an LS pattern having a space width of 18 nm and a pitch of 36 nm.

[0342] For the obtained resist pattern, the following evaluations were performed. The results are shown in Table 4.

[0343] [Sensitivity evaluation]

[0344] The aforementioned LS pattern was observed using a length measuring SEM (CG-6300) manufactured by Hitachi High-Tech, and the optimum exposure amount Eop (mJ / cm2) at which an LS pattern having a space width of 18 nm and a pitch of 36 nm could be obtained was calculated, and this was taken as the sensitivity. 2

[0345] [LWR evaluation]

[0346] ​For the LS pattern obtained by irradiation at the optimum exposure amount, the dimensions of 10 places were measured in the longitudinal direction along the pitch width with a length-measuring SEM (CG-6300) manufactured by Hitachi High-Tech, and the value of 3 times the standard deviation (σ) was calculated from the results, and was made the LWR. The smaller this value, the more uniform the pitch width pattern with a smaller roughness can be obtained.

[0347] [Limit of resolution evaluation]

[0348] The exposure amount was increased little by little from the optimum exposure amount at which the aforementioned LS pattern was formed, and the limit of line width (nm) at which resolution was performed when the pattern was formed was calculated using a length-measuring SEM (CG-6300) manufactured by Hitachi High-Tech, and was made the limit of resolution (nm). The smaller this value, the more excellent the limit of resolution, and a finer pattern can be formed.

[0349] [Table 4]

[0350]

[0351] Developer: nBA (butyl acetate)

[0352] CHA (cyclohexyl acetate)

[0353] TMAH (2.38 mass% aqueous tetramethylammonium hydroxide solution)

[0354] [5] EUV lithography evaluation (line and space pattern, negative tone development)

[0355] [Examples 3-1 to 3-16, Comparative Examples 3-1 to 3-3]

[0356] Each of the resist compositions (R-1 to R-16, CR-01 to CR-03) was spin-coated on a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 manufactured by Showa Denko K.K. (content of silicon: 43 mass%) was formed in a film thickness of 20 nm, and a resist film having a film thickness of 40 nm was prepared by prebaking (PAB) using a hot plate at the temperature described in Table 5 for 60 seconds. After exposure of a 36 nm line and space (LS) 1:1 pattern using an EUV scanning exposure machine NXE3400 (NA 0.33, σ 0.9, 90-degree dipole illumination) manufactured by ASML, baking (PEB) was performed on a hot plate at the temperature described in Table 5 for 60 seconds, and then development was performed with the developer described in Table 5 for 30 seconds, to form an LS pattern having a pitch width of 18 nm and a pitch of 36 nm.

[0357] For the obtained resist pattern, the following evaluation was performed. The results are shown in Table 4.

[0358] [Sensitivity evaluation]

[0359] The aforementioned LS pattern was observed using a length-measuring SEM (CG-6300) manufactured by Hitachi High-Tech, and the optimum exposure amount Eop (mJ / cm2) at which an LS pattern having a pitch width of 18 nm and a pitch of 36 nm could be obtained was determined, and was made the sensitivity. 2

[0360] [LWR evaluation]

[0361] For the LS pattern obtained by irradiation at the optimum exposure amount, the dimensions of 10 places were measured in the longitudinal direction of the pitch width using a length-measuring SEM (CG-6300) manufactured by Hitachi High-Tech, and the 3 times value (3σ) of the standard deviation (σ) was determined from the results, and was made the LWR. The smaller this value, the more uniform the pitch width pattern having a smaller roughness can be obtained.

[0362] [Limit of resolution evaluation]

[0363] The exposure amount was gradually increased in small amounts from the optimum exposure amount at which the aforementioned LS pattern was formed, and the limit of the line width (nm) at which resolution was performed when the pattern was formed was determined using a length-measuring SEM (CG-6300) manufactured by Hitachi High-Tech, and was made the limit of resolution (nm). The smaller this value, the better the limit of resolution, and a finer pattern can be formed.

[0364] [Table 5]

[0365]

[0366] From the results shown in Table 4 and Table 5, it was found that the resist composition of the present application is excellent in sensitivity, LWR, and resolution in the formation of line and space patterns by EUV exposure, regardless of either positive or negative development.

[0367] [6] EUV lithography evaluation (contact hole pattern)

[0368] [Examples 4-1 to 4-16, Comparative Examples 4-1 to 4-3]

[0369] ​Each of the resist compositions (R-01 to R-16, CR-01 to CR-03) was spin-coated on a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content: 43 mass%) manufactured by Showa Denko K.K. was formed in a film thickness of 20 nm, and a film thickness of 50 nm of the resist film was prepared by using a hot plate, prebaking (PAB) at the temperature described in Table 6 for 60 seconds. Then, the foregoing resist film was exposed using an EUV scanning exposure machine NXE3400 (NA 0.33, σ 0.9 / 0.6, quadrupole illumination, a mask of a hole pattern of a size of 64 nm pitch, +20% offset on a wafer) manufactured by ASML Co., and baking (PEB) was performed on a hot plate at the temperature described in Table 6 for 60 seconds, and development was performed using the developing solution described in Table 6 for 30 seconds, to obtain a hole pattern of a size of 32 nm.

[0370] For the obtained resist pattern, the following evaluations were performed. The results are shown in Table 6.

[0371] [Sensitivity Evaluation]

[0372] The foregoing contact hole pattern was observed using a length measuring SEM (CG-6300) manufactured by Hitachi High-Tech Co., and the optimum exposure amount Eop (mJ / cm2) at which a hole pattern of a size of 32 nm could be obtained was calculated. 2

[0373] [CD Uniformity (CDU) Evaluation]

[0374] The sizes of 50 hole patterns obtained by irradiation at the optimum exposure amount were measured, and the value 3 times the standard deviation (σ) calculated from the results thereof (3σ) was taken as the CDU. The smaller this value, the more uniform the pattern of hole diameters that can be obtained.

[0375] [Limit of Resolution Evaluation]

[0376] The exposure amount was gradually reduced in small amounts from the optimum exposure amount at which the foregoing hole pattern was formed, and the limit of hole diameter (nm) at which resolution was performed when the hole pattern was formed was calculated using a length measuring SEM (CG-6300) manufactured by Hitachi High-Tech Co., and this was taken as the limit of resolution (nm). The smaller this value, the better the limit of resolution, and the pattern of hole diameters that can be obtained is finer.

[0377] [Table 6]

[0378]

[0379] As is clear from the results shown in Table 6, the resist compositions of the present application are excellent in sensitivity, CDU, and resolution in the formation of a contact hole pattern by EUV exposure.​

Claims

1. A resist composition comprising: A hypervalent iodine compound represented by the following formula (1): Carboxyl-containing polymers, and solvents; In the formula, m is 0 or 1; n is an integer from 0 to 4 when m is 0, and an integer from 0 to 6 when m is 1; R 1 is a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may also contain a heteroatom; R 2 is a halogen atom or a hydrocarbon group having 1 to 40 carbon atoms which may contain heteroatoms; when n is 2 or more, each R 2 They can be the same or different from each other; moreover, multiple R 2 They can also bond to each other and to the carbon atoms of the aromatic ring to which they are bonded to form a ring; R 3 is a carbonyl group, or an alkylene group having 1 to 10 carbon atoms which may also contain heteroatoms; *1 and *2 represent atomic bonds between carbon atoms in the aromatic ring in the formula; however, *1 and *2 are bonded to adjacent carbon atoms in the aromatic ring.

2. The resist composition according to claim 1, wherein The carboxyl group-containing polymer is a polymer containing a repeating unit represented by the following formula (2): Where R A is a hydrogen atom, a halogen atom, a methyl group or a trifluoromethyl group; X A is a single bond, phenylene, naphthylene or *-C(=O)-OX A1 -;X A1 It is a saturated alkylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, and the saturated alkylene group may contain at least one selected from a hydroxyl group, an ether bond, an ester bond and a lactone ring; * represents an atomic bond to a carbon atom of the main chain.

3. The resist composition according to claim 1, further comprising a hypervalent iodine compound represented by the following formula (3); Wherein, k is an integer from 0 to 5; R 11 and R 12 are independently a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may contain a hetero atom; and R 11 and R 12 They may also bond to each other and to the carbon atoms to which they are bonded and the atoms between the carbon atoms to form a ring; R 13 is a halogen atom or a hydrocarbon group having 1 to 40 carbon atoms which may also contain heteroatoms; when k is 2, 3, 4 or 5, each R 13 They can be the same or different from each other; moreover, multiple R 13 They may also be bonded to each other and to the carbon atoms of the aromatic ring to which they are bonded to form a ring.

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

5. The laminate according to claim 4, wherein A resist underlayer film is provided between the substrate and the resist film.

6. A pattern forming method comprising the following steps: Using the resist composition according to any one of claims 1 to 3, a resist film is formed on a substrate or on an underlayer film of a substrate on which an underlayer film is laminated. The resist film is exposed to high energy radiation, and The exposed resist film is developed using a developer.

7. The pattern forming method according to claim 6, wherein: The high-energy rays are electron beams or extreme ultraviolet rays.

8. The pattern forming method according to claim 6, wherein: The developer dissolves the exposed portion and does not dissolve the unexposed portion.

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

10. A laminate comprising a substrate and a resist film on the substrate, wherein: The resist film is a polymer containing a repeating unit represented by the following formula (4); In the formula, m is 0 or 1; n is an integer from 0 to 4 when m is 0, and an integer from 0 to 6 when m is 1; R 2 is a halogen atom or a hydrocarbon group having 1 to 40 carbon atoms which may contain heteroatoms; when n is 2 or more, each R 2 They can be the same or different from each other; moreover, multiple R 2 They can also bond to each other and to the carbon atoms of the aromatic ring to which they are bonded to form a ring; R 3 is a carbonyl group, or an alkylene group having 1 to 10 carbon atoms which may also contain heteroatoms; *1 and *2 represent atomic bonds between carbon atoms in an aromatic ring in the formula; however, *1 and *2 are bonded to adjacent carbon atoms in the aromatic ring; R A is a hydrogen atom, a halogen atom, a methyl group or a trifluoromethyl group; X A is a single bond, phenylene, naphthylene or *-C(=O)-OX A1 -;X A1 It is a saturated alkylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, and the saturated alkylene group may contain at least one selected from a hydroxyl group, an ether bond, an ester bond and a lactone ring; * represents an atomic bond to a carbon atom of the main chain.

11. The laminate according to claim 10, wherein A resist underlayer film is provided between the substrate and the resist film.

12. A pattern forming method comprising the following steps: exposing the resist film of the laminate according to any one of claims 10 or 11 to high-energy radiation, and The exposed resist film is developed using a developer.

13. The pattern forming method according to claim 12, wherein: The high-energy rays are electron beams or extreme ultraviolet rays.

14. The pattern forming method according to claim 12, wherein: The developer dissolves the exposed portion and does not dissolve the unexposed portion.

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

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