Negative resist material and pattern forming method

Abstract

To provide a negative resist material for organic solvent development having high resolution and improved LWR and CDU, and a patterning method using the same.SOLUTION: A negative resist material comprises: a base polymer; and an acid generator, which is a sulfonium salt, comprising a sulfonic acid anion having an iodinated or brominated hydrocarbyl group (excluding one with an iodine atom or a bromine atom binding to a carbon atom on an aromatic ring) and a cation having a polymerizable double bond.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] As LSIs become more highly integrated and faster, pattern rules are becoming increasingly miniaturized. This is due to the increasing popularity of 5G high-speed communications and artificial intelligence (AI), which require high-performance devices to process these. The most advanced miniaturization technology is extreme ultraviolet (EUV) lithography with a wavelength of 13.5 nm, which is currently used to mass-produce 5 nm node devices. Furthermore, the use of EUV lithography is being considered for next-generation 3 nm node devices and the next-generation 2 nm node devices.

[0003] As miniaturization progresses, image blurring due to acid diffusion has become a problem. To ensure resolution in fine patterns with dimensions of 45 nm and smaller, it has been suggested that controlling acid diffusion is important, in addition to improving dissolution contrast, as has been proposed previously (Non-Patent Document 1). However, because chemically amplified resist materials increase sensitivity and contrast through acid diffusion, attempts to minimize acid diffusion by lowering the post-exposure bake (PEB) temperature or shortening the time result in significant decreases in sensitivity and contrast.

[0004] Interference exposure is effective when forming patterns with pitches narrower than the wavelength. In particular, high-contrast light interference between X-direction lines and Y-direction lines generates high-contrast black spots. By combining this with a negative resist material, hole patterns with high dimensional uniformity (CDU) can be formed (Non-Patent Document 2). Non-Patent Document 2 uses a negative resist material that uses a crosslinking agent that reacts between polymers in the presence of acid. Such chemically amplified negative resist materials have the problems of image blurring due to acid diffusion mentioned above, and swelling caused by developer seeping into the partially crosslinked polymers, which leads to pattern collapse and degradation of CDU and line edge roughness (LWR).

[0005] Here, the creation of negative patterns by organic solvent development is a method that has been used for a long time. Cyclized rubber-based resist materials use xylene or the like as a developer, and early chemically amplified resist materials based on poly-tert-butoxycarbonyloxystyrene used anisole as a developer to obtain negative patterns (Non-Patent Document 3).

[0006] A negative pattern can be formed by exposure to ArF excimer laser light and organic solvent development using a chemically amplified resist material whose base polymer is polymethacrylate in which the carboxyl group is substituted with an acid-labile group (Patent Document 1). This organic solvent development process is used in combination with immersion exposure and double patterning using an optical system with an NA exceeding 1 in the manufacture of devices at the 20 nm node and beyond.

[0007] EUV lithography cannot form patterns with a pitch smaller than the exposure wavelength. This is because the NA of EUV exposure is 0.33, which is significantly smaller than the 1.35 of ArF immersion exposure, and the effect of interference exposure is small. The next NA after EUV lithography is 0.55, but even in this generation, negative resist materials do not have an advantage in forming hole patterns.

[0008] Negative patterns are required in EUV lithography when forming isolated patterns or pillar patterns. In this case, the mask has a higher proportion of light-shielding areas, which has the advantage of being less susceptible to defects in the mask blanks.

[0009] Furthermore, when forming an isolated pattern or a pillar pattern on a photomask, a negative resist material is preferably used. This is because the patterning area is smaller when a negative resist material is used, which shortens the patterning time and improves throughput. Therefore, high resolution is also required for resist materials used in electron beam (EB) lithography for mask pattern formation.

[0010] Organic solvent development causes less swelling than alkaline aqueous development, which can result in better CDU and LWR. However, it has the problem of lower resolution due to lower dissolution contrast compared to alkaline aqueous development. If a crosslinker that reacts with acid is added to the resist material to increase the dissolution contrast in organic solvent development, the aforementioned swelling problem will also occur in organic solvent development. It is necessary to improve the dissolution contrast without swelling. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-281974 [Non-patent literature]

[0012] [Non-Patent Document 1] SPIE Vol. 6520 65203L-1 (2007) [Non-patent document 2] IEEE IEDM Tech. Digest 61 (1996) [Non-patent document 3] VLSI. Technol. Symp. p86-87 (1982) Summary of the Invention [Problem to be solved by the invention]

[0013] There is a need to develop negative resist materials compatible with organic solvent processes that can reduce line write (LWR) in line patterns and cover density under (CDU) in hole patterns, while also achieving high resolution. To achieve this, they must have low swelling and high contrast during organic solvent development.

[0014] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a negative resist material for organic solvent development that has high resolution and improved LWR and CDU, and a pattern formation method using the same. [Means for solving the problem]

[0015] As a result of extensive research into achieving the above-mentioned object, the present inventors have discovered that a resist material containing a base polymer and an acid generator that is a sulfonium salt (hereinafter also referred to as sulfonium salt A) consisting of a sulfonate anion having a hydrocarbyl group substituted with an iodine atom or a bromine atom (excluding those in which the iodine atom or bromine atom is bonded to a carbon atom on an aromatic ring), and a cation having a polymerizable double bond, crosslinks the sulfonium salt upon exposure, thereby enhancing the acid diffusion suppression effect, reducing solubility in organic solvents and improving dissolution contrast, thereby improving LWR and CDU, providing excellent resolution and a wide process margin, and have completed the present invention.

[0016] That is, the present invention provides the following negative resist material and pattern forming method. 1. A negative resist material comprising a base polymer and an acid generator which is a sulfonium salt consisting of a sulfonate anion having a hydrocarbyl group substituted with an iodine atom or a bromine atom (excluding those in which the iodine atom or bromine atom is bonded to a carbon atom on an aromatic ring) and a cation having a polymerizable double bond. 2. The negative resist material of 1, wherein the sulfonium salt is represented by the following formula (A): [ka] (In the formula, k 1 is an integer between 1 and 3. 2 is an integer of 1 to 3. m is an integer of 1 to 3, and n is an integer of 0 to 2, provided that m+n=3. p is 1 or 2, and q is an integer of 0 to 4, provided that 1≦p+q≦5. r is an integer of 0 to 5. X BI is a bromine atom or an iodine atom. R is a (k 1 It is a monovalent aliphatic hydrocarbon group, and the aliphatic hydrocarbon group may contain at least one bond selected from a fluorine atom, a chlorine atom, a hydroxy group, a carboxy group, an aryl group having 6 to 12 carbon atoms, an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate bond, a urethane bond, and a urea bond. X 1 is k 2 When k is 1, it is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms which may contain a hetero atom; 2 When is 2 or 3, (k 2 +1)valent hydrocarbon group. X 2 is a single bond, an ester bond or an ether bond. X 3 is a single bond or an aliphatic hydrocarbylene group having 1 to 10 carbon atoms. X 4 represents a single bond, an ester bond, an ether bond, an amide bond, a urethane bond, or an alkanediyl group having 1 to 10 carbon atoms, and some of the -CH2- groups in the alkanediyl group may be substituted with ester bonds, ether bonds, amide bonds, or urethane bonds. R 1 ~R 3are each independently a hydrogen atom, a halogen atom, or a saturated hydrocarbyl group having 1 to 40 carbon atoms, and some or all of the hydrogen atoms of the saturated hydrocarbyl group may be substituted with fluorine atoms or hydroxy groups, some of the -CH2- groups of the saturated hydrocarbyl group may be substituted with ether bonds or ester bonds, and some of the carbon-carbon bonds of the saturated hydrocarbyl group may be double bonds. R 4 and R 5 are each independently a halogen atom, a cyano group, a nitro group, a mercapto group, a sulfo group, a saturated hydrocarbyl group having 1 to 10 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, and the saturated hydrocarbyl group and the aralkyl group may contain an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom. 4 or two R's 5 may be bonded to each other to form a ring together with the benzene ring to which they are bonded, and R 4 and R 5 may be bonded to each other to form a ring together with the benzene ring to which they are bonded and the sulfur atom therebetween. Rf 1 ~Rf 4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and at least one of them is a fluorine atom or a trifluoromethyl group. 1 and Rf 2 may combine to form a carbonyl group.) 3. The negative resist material of 1 or 2, wherein the base polymer contains a repeating unit represented by the following formula (a1): [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. Y 1 is a linking group having 1 to 12 carbon atoms and containing at least one bond selected from a single bond, a phenylene group, a naphthylene group, an ester bond, an ether bond, and a lactone ring. R 11 is an acid labile group. 4. A negative resist material according to any one of 1 to 3, further comprising an organic solvent. 5. A negative resist material according to any one of 1 to 4, further comprising a quencher. 6. A negative resist material according to any one of 1 to 5, further comprising a crosslinking agent. 7. A negative resist material according to any one of 1 to 6, further comprising a surfactant. 8. A pattern forming method comprising the steps of forming a resist film on a substrate using a negative resist material according to any one of 1 to 7, exposing the negative resist film to high-energy rays, and developing the exposed negative resist film using an organic solvent developer. 9. The organic solvent developer is selected from the group consisting of 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, isopentyl acetate, 2-methylbutyl acetate, hexyl acetate, butenyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonate, ethyl crotonate, propyl methyl methyl valerate, methyl pentenoate, methyl crotonate, ethyl crotonate, propyl methyl methyl methyl valerate, methyl pentenoate, methyl crotonate, propyl methyl methyl methyl valerate, methyl pentenoate, methyl crotonate, ethyl ...methyl valerate, methyl pentenoate, methyl crotonate, ethyl propyl methyl methyl methyl methyl valerate, methyl pentenoate, methyl crotonate, ethyl propyl methyl methyl methyl methyl valerate, methyl pentenoate, methyl pentenoate, ethyl propyl methyl methyl methyl methyl methyl valerate, methyl pentenoate, methyl pentenoate, ethyl propyl methyl methyl methyl methyl methyl valerate, methyl 8. A pattern formation method in accordance with claim 8, wherein the compound is one or more selected from the group consisting of methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, and 2-phenylethyl acetate. 10. The pattern formation method of 8 or 9, wherein the high-energy radiation is KrF excimer laser light, ArF excimer laser light, EB, or EUV having a wavelength of 3 to 15 nm. [Effects of the Invention]

[0017] In a resist material containing the base polymer and an acid generator made of sulfonium salt A, exposure causes the elimination of iodine or bromine atoms on the anion side or the generation of radicals from these atoms, which in turn promotes a crosslinking reaction on the cation side, resulting in low acid diffusion and promoting insolubilization in a developer. This makes it possible to develop a resist material with high resolution and improved LWR and CDU. DETAILED DESCRIPTION OF THE INVENTION

[0018] [Negative resist material] The negative resist material of the present invention comprises a base polymer and an acid generator which is a sulfonium salt A.

[0019] [Sulfonium salt A] The sulfonium salt A functions as an acid generator, and is preferably represented by the following formula (A). [ka]

[0020] In formula (A), k 1 is an integer between 1 and 3. 2 is an integer of 1 to 3. m is an integer of 1 to 3, and n is an integer of 0 to 2, provided that m+n=3. p is 1 or 2, and q is an integer of 0 to 4, provided that 1≦p+q≦5. r is an integer of 0 to 5.

[0021] In formula (A), X BI is a bromine atom or an iodine atom. 1 and / or k 2 When is 2 or 3, each X BI may be the same or different from each other.

[0022] In formula (A), R is a (k 1 +1)valent aliphatic hydrocarbon group. 2When R is 2 or 3, each R may be the same or different. The aliphatic hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic.Specific examples thereof include methanediyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, propane-1,3-diyl group, propane-2,2-diyl group, butane-1,1-diyl group, butane-1,2-diyl group, butane-1,3-diyl group, butane-2,3-diyl group, butane-1,4-diyl group, 1,1-dimethylethane-1,2-diyl group, pentane-1,5-diyl group, 2-methylbutane-1,2-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, and the like. alkanediyl groups such as cyclopentane-1,1-diyl, cyclopentane-1,2-diyl, cyclopentane-1,3-diyl, cyclohexane-1,1-diyl, cyclohexane-2,2-diyl, cyclohexane-1,3-diyl, cyclohexane-1,1-diyl, cyclohexane-2,2-diyl, cyclohexane-1,1-diyl, cyclohexane-1,2-diyl, cyclohexane-1,3-diyl, cyclohexane-2,2-diyl, cyclohexane-1,1 ... Cycloalkanediyl groups such as cyclohexane-1,2-diyl, cyclohexane-1,3-diyl, and cyclohexane-1,4-diyl; divalent polycyclic saturated hydrocarbyl groups such as norbornane-2,3-diyl and norbornane-2,6-diyl; alkenediyl groups such as 2-propene-1,1-diyl; alkynediyl groups such as 2-propyne-1,1-diyl; cycloalkenediyl groups such as 2-cyclohexene-1,2-diyl, 2-cyclohexene-1,3-diyl, and 3-cyclohexene-1,2-diyl; 5-norbornene-2 alkanediyl groups substituted with cycloaliphatic hydrocarbyl groups such as cyclopentylmethanediyl, cyclohexylmethanediyl, 2-cyclopentenylmethanediyl, 3-cyclopentenylmethanediyl, 2-cyclohexenylmethanediyl, and 3-cyclohexenylmethanediyl groups; aliphatic hydrocarbylene groups such as groups obtained by combining these; and trivalent or tetravalent groups obtained by further eliminating one or two hydrogen atoms from the above-mentioned aliphatic hydrocarbylene groups.

[0023] The aliphatic hydrocarbon group may contain at least one bond selected from the group consisting of a fluorine atom, a chlorine atom, a hydroxy group, a carboxy group, an aryl group having 6 to 12 carbon atoms, an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate bond, a urethane bond, and a urea bond. In other words, some or all of the hydrogen atoms of the aliphatic hydrocarbon group may be substituted with a fluorine atom, a chlorine atom, a hydroxy group, a carboxy group, or an aryl group having 6 to 12 carbon atoms, or some of the -CH2- groups of the aliphatic hydrocarbon group may be substituted with at least one bond selected from the group consisting of an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate bond, a urethane bond, and a urea bond. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a 2-methylphenyl group, a 3-methylphenyl group, a 4-methylphenyl group, a 1-naphthyl group, a 2-naphthyl group, and a fluorenyl group.

[0024] In formula (A), X 1 is k 2 When k is 1, it is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms which may contain a hetero atom; 2 When is 2 or 3, (k 2 +1)-valent hydrocarbon group. 2 The hydrocarbon group having a valence of +1 may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include the groups exemplified as the aliphatic hydrocarbon group having 1 to 20 carbon atoms represented by R; and aromatic hydrocarbons such as benzene, toluene, xylene, and naphthalene, which are substituted with hydrogen atoms on the aromatic ring of the aromatic hydrocarbon. 2+1); and groups obtained by combining these. In addition, some of the hydrogen atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, so that the group may contain a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxy group, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc.

[0025] In formula (A), X 2 is a single bond, an ester bond or an ether bond.

[0026] In formula (A), X 3 is a single bond or an aliphatic hydrocarbylene group having 1 to 10 carbon atoms. 3 The aliphatic hydrocarbylene group having 1 to 10 carbon atoms represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include the aliphatic hydrocarbylene groups having 1 to 10 carbon atoms exemplified as the aliphatic hydrocarbon group represented by R.

[0027] In formula (A), X 4 is a single bond, an ester bond, an ether bond, an amide bond, a urethane bond, or an alkanediyl group having 1 to 10 carbon atoms, and a portion of the -CH2- in the alkanediyl group may be substituted with an ester bond, an ether bond, an amide bond, or a urethane bond. Examples of the alkanediyl group include a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a nonane-1,9-diyl group, and a decane-1,10-diyl group.

[0028] In formula (A), R 1 ~R3 are each independently a hydrogen atom, a halogen atom, or a saturated hydrocarbyl group having 1 to 40 carbon atoms, and some or all of the hydrogen atoms of the saturated hydrocarbyl group may be substituted with fluorine atoms or hydroxy groups, some of the -CH2- groups of the saturated hydrocarbyl group may be substituted with ether bonds or ester bonds, and some of the carbon-carbon bonds of the saturated hydrocarbyl group may be double bonds.

[0029] R 1 ~R 3 The saturated hydrocarbyl group having 1 to 40 carbon atoms represented by the formula (I) may be linear, branched, or cyclic, and specific examples thereof include alkyl groups having 1 to 40 carbon atoms, such as a methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, 2-ethylhexyl group, nonyl group, decyl group, undecyl group, tridecyl group, pentadecyl group, heptadecyl group, and eicosanyl group; and cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms, such as a cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-adamantyl group, 1-adamantylmethyl group, norbornyl group, norbornylmethyl group, tricyclodecanyl group, tetracyclododecanyl group, tetracyclododecanylmethyl group, and dicyclohexylmethyl group.

[0030] In formula (A), R 4 and R 5 are each independently a halogen atom, a cyano group, a nitro group, a mercapto group, a sulfo group, a saturated hydrocarbyl group having 1 to 10 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, and the saturated hydrocarbyl group and the aralkyl group may contain an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom. 4 or two R's 5 may be bonded to each other to form a ring together with the benzene ring to which they are bonded, and R 4 and R 5may be bonded to each other to form a ring together with the benzene ring to which they are bonded and the sulfur atom therebetween. In this case, the ring preferably has the structure shown below, where the substituents on the aromatic ring are omitted. [ka] (In the formula, the dashed lines represent bonds.)

[0031] In formula (A), Rf 1 ~Rf 4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and at least one of them is a fluorine atom or a trifluoromethyl group. 1 and Rf 2 may combine to form a carbonyl group.

[0032] Examples of the sulfonate anion include, but are not limited to, those shown below. [ka]

[0033] [ka]

[0034] [ka]

[0035] [ka]

[0036] [ka]

[0037] [ka]

[0038] [ka]

[0039] [ka]

[0040] [ka]

[0041] [ka]

[0042] Examples of the sulfonium cation having a polymerizable double bond in the sulfonium salt represented by formula (A) include, but are not limited to, those shown below. [ka]

[0043] [ka]

[0044] [ka]

[0045] [ka]

[0046] [ka]

[0047] [ka]

[0048] [ka]

[0049] [ka]

[0050] [ka]

[0051] The sulfonium salt represented by formula (A) can be synthesized by ion-exchanging a fluorosulfonic acid that provides the anion with a sulfonium salt that is a weaker acid than the fluorosulfonic acid and contains the sulfonium cation. Examples of the weak acid include carbonic acid and halogens. Alternatively, the sulfonium salt can be synthesized by ion-exchanging a sodium or ammonium salt of fluorosulfonic acid that provides the anion with a sulfonium chloride that contains the sulfonium cation.

[0052] In the negative resist material of the present invention, the content of the acid generator, which is a sulfonium salt represented by Formula (A), relative to 100 parts by mass of the base polymer described below is preferably 0.01 to 1,000 parts by mass, and more preferably 0.05 to 500 parts by mass, from the viewpoints of sensitivity and acid diffusion suppression effect.

[0053] [Base polymer] The base polymer contained in the negative resist material of the present invention preferably contains a repeating unit represented by the following formula (a1) (hereinafter also referred to as repeating unit a1). [ka]

[0054] In formula (a1), R A is a hydrogen atom or a methyl group.1 R is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms and containing at least one bond selected from an ester bond, an ether bond, and a lactone ring. 11 is an acid labile group.

[0055] Examples of monomers that provide the repeating unit a1 include, but are not limited to, the following: A and R 11 is the same as above. [ka]

[0056] The base polymer may contain a repeating unit represented by the following formula (a2) (hereinafter also referred to as repeating unit a2). [ka]

[0057] In formula (a2), R A is a hydrogen atom or a methyl group. 2 is a single bond or an ester bond. 3 is a single bond, an ether bond, or an ester bond. 12 is an acid labile group. 13 R is a fluorine atom, a trifluoromethyl group, a cyano group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 7 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 7 carbon atoms, or a saturated hydrocarbyloxycarbonyl group having 2 to 7 carbon atoms. 14 represents a single bond or an alkanediyl group having 1 to 6 carbon atoms, some of the carbon atoms of which may be substituted with an ether bond or an ester bond. a is 1 or 2. b is an integer of 0 to 4.

[0058] Examples of the monomer that provides the repeating unit a2 include, but are not limited to, the following:A and R 12 is the same as above. [ka]

[0059] R in the repeating units a1 and a2 11 and R 12 Examples of the acid labile group represented by the formula (I) include those described in JP-A Nos. 2013-80033 and 2013-83821.

[0060] Typical examples of the acid labile group include those represented by the following formulae (AL-1) to (AL-3). [ka] (In the formula, the dashed lines represent bonds.)

[0061] In formulas (AL-1) and (AL-2), R L1 and R L2 are each independently a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group is preferably a saturated hydrocarbyl group having 1 to 40 carbon atoms, more preferably a saturated hydrocarbyl group having 1 to 20 carbon atoms.

[0062] In formula (AL-1), c is an integer of 0 to 10, and an integer of 1 to 5 is preferred.

[0063] In formula (AL-2), R L3 and R L4 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group is preferably a saturated hydrocarbyl group having 1 to 20 carbon atoms. In addition, RL2 , R L3 and R L4 Any two of these may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom or the carbon atom and oxygen atom to which they are bonded. As the ring, a ring having 4 to 16 carbon atoms is preferred, and an alicyclic ring is particularly preferred.

[0064] In formula (AL-3), R L5 , R L6 and R L7 are each independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group is preferably a saturated hydrocarbyl group having 1 to 20 carbon atoms. In addition, R L5 , R L6 and R L7 Any two of these may be bonded to each other together with the carbon atoms to which they are bonded to form a ring having 3 to 20 carbon atoms. As the ring, a ring having 4 to 16 carbon atoms is preferred, and an alicyclic ring is particularly preferred.

[0065] The base polymer may further contain a repeating unit b containing a phenolic hydroxy group as an adhesive group. Examples of monomers that provide the repeating unit b include, but are not limited to, the following. In the following formula, R A is the same as above. [ka]

[0066] The base polymer may further contain a repeating unit c containing, as another adhesive group, a hydroxy group other than a phenolic hydroxy group, a lactone ring, a sultone ring, an ether bond, an ester bond, a sulfonate ester bond, a carbonyl group, a sulfonyl group, a cyano group, or a carboxy group. Monomers that provide the repeating unit c include, but are not limited to, those shown below. In the following formula, R A is the same as above.

change

[0067]

change

[0068]

change

[0069]

change

[0070]

change

[0071]

change

[0072]

change

[0073]

change

[0074]

change

[0075]

change

[0076]

change

[0077] The base polymer may further contain a repeating unit d derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene, or derivatives thereof. Examples of the monomer that gives the repeating unit d include, but are not limited to, those shown below.

Chemical formula

[0078] The base polymer may further contain a repeating unit e derived from styrene, vinyl naphthalene, vinyl anthracene, vinyl pyrene, methylene indane, vinyl pyridine, or vinyl carbazole.

[0079] The base polymer for a negative resist material for organic solvent development essentially contains a repeating unit a1 containing an acid-labile group. In this case, the content ratios of the repeating units a1, a2, b, c, d, and e are preferably 0 < a1 < 1.0, 0 ≤ a2 < 1.0, 0 < a1 + a2 < 1.0, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.9, 0 ≤ d ≤ 0.8, 0 ≤ e ≤ 0.8, more preferably 0.1 ≤ a1 ≤ 0.9, 0 ≤ a2 ≤ 0.9, 0.1 ≤ a1 + a2 ≤ 0.9, 0 ≤ b ≤ 0.8, 0 ≤ c ≤ 0.8, 0 ≤ d ≤ 0.7, 0 ≤ e ≤ 0.7, and still more preferably 0.2 ≤ a1 ≤ 0.8, 0 ≤ a2 ≤ 0.8, 0.2 ≤ a1 + a2 ≤ 0.8, 0 ≤ b ≤ 0.75, 0 ≤ c ≤ 0.75, 0 ≤ d ≤ 0.6, 0 ≤ e ≤ 0.6. Also, a1 + a2 + b + c + d + e = 1.0.

[0080] To synthesize the base polymer, for example, monomers that give the above-described repeating units may be heated in an organic solvent with a radical polymerization initiator added thereto to perform polymerization.

[0081] Examples of organic solvents used during polymerization include toluene, benzene, tetrahydrofuran (THF), diethyl ether, and dioxane. Examples of polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The polymerization temperature is preferably 50 to 80°C. The reaction time is preferably 2 to 100 hours, and more preferably 5 to 20 hours.

[0082] When a monomer containing a hydroxy group is copolymerized, the hydroxy group may be substituted with an acetal group, such as an ethoxyethoxy group, which is easily deprotected by an acid, during polymerization, and then deprotected with a weak acid and water after polymerization. Alternatively, the hydroxy group may be substituted with an acetyl group, a formyl group, a pivaloyl group, or the like, and then subjected to alkaline hydrolysis after polymerization.

[0083] When hydroxystyrene or hydroxyvinylnaphthalene is copolymerized, acetoxystyrene or acetoxyvinylnaphthalene may be used instead of hydroxystyrene or hydroxyvinylnaphthalene, and after polymerization, the acetoxy groups may be deprotected by the alkaline hydrolysis to form hydroxystyrene units or hydroxyvinylnaphthalene units.

[0084] The base that can be used in alkaline hydrolysis includes aqueous ammonia, triethylamine, etc. The reaction temperature is preferably −20 to 100° C., more preferably 0 to 60° C. The reaction time is preferably 0.2 to 100 hours, more preferably 0.5 to 20 hours.

[0085] The base polymer preferably has a weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) using THF as a solvent of 1,000 to 500,000, more preferably 2,000 to 30,000. When the Mw is within this range, the resist film has good heat resistance and solubility in organic solvent developers.

[0086] Furthermore, if the base polymer has a broad molecular weight distribution (Mw / Mn), the presence of low-molecular-weight and high-molecular-weight polymers may result in the appearance of foreign matter on the pattern after exposure, or the pattern shape may be deteriorated. As the pattern rule becomes finer, the effects of Mw and Mw / Mn tend to become greater. Therefore, in order to obtain a resist material that is suitable for use with fine pattern dimensions, it is preferable that the Mw / Mn of the base polymer has a narrow distribution of 1.0 to 2.0, particularly 1.0 to 1.5.

[0087] The base polymer may contain two or more polymers with different composition ratios, Mw, and Mw / Mn.

[0088] [Organic solvents] The negative resist material of the present invention may contain an organic solvent. The organic solvent is not particularly limited as long as it can dissolve the components described above and below. Examples of the organic solvent include ketones such as cyclohexanone, cyclopentanone, methyl-2-n-pentyl ketone, and 2-heptanone, as described in paragraphs

[0144] and

[0145] of JP-A-2008-111103, alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, and ethylene glycol. Examples of the alkyl ester include ethers such as propylene 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 mono-tert-butyl ether acetate; and lactones such as γ-butyrolactone.

[0089] In the negative resist composition of the present invention, the content of the organic solvent is preferably 100 to 10,000 parts by mass, more preferably 200 to 8,000 parts by mass, per 100 parts by mass of the base polymer. The organic solvents may be used singly or in combination of two or more.

[0090] [Quencher] The negative resist material of the present invention may contain a quencher. The quencher is a compound that can trap the acid generated by the acid generator in the resist material, thereby preventing the acid from diffusing into unexposed areas.

[0091] Examples of the quencher include conventional basic compounds. Examples of conventional basic compounds include primary, secondary, and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxy group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxy group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amides, imides, and carbamates. Particularly preferred are the primary, secondary, and tertiary amine compounds described in paragraphs

[0146] to

[0164] of JP 2008-111103 A, particularly amine compounds having a hydroxy group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonate ester bond, and compounds having a carbamate group described in Japanese Patent No. 3790649 A. Addition of such basic compounds can, for example, further suppress the diffusion rate of acid in the resist film or correct the shape.

[0092] Further, examples of the quencher include onium salts such as sulfonium salts, iodonium salts, and ammonium salts of sulfonic acids, carboxylic acids, or fluorinated alkoxides that are not fluorinated at the α-position. Sulfonic acids, imide acids, or methide acids that are fluorinated at the α-position are necessary for deprotecting the acid labile group of a carboxylic acid ester, and salt exchange with the onium salt releases sulfonic acids, carboxylic acids, or fluorinated alcohols that are not fluorinated at the α-position. Sulfonic acids, carboxylic acids, and fluorinated alcohols that are not fluorinated at the α-position do not undergo a deprotection reaction, and therefore function as quenchers.

[0093] Examples of such quenchers include compounds represented by the following formula (B) (onium salts of sulfonic acids not fluorinated at the α-position), compounds represented by the following formula (C) (onium salts of carboxylic acids), and compounds represented by the following formula (D) (onium salts of alkoxides). [ka]

[0094] In formula (B), R 101 represents a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom, but excludes those in which the hydrogen atom bonded to the carbon atom at the α-position of the sulfo group is substituted with a fluorine atom or a fluoroalkyl group.

[0095] The hydrocarbyl group 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, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0]. 2,6]Cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms such as decanyl group, adamantyl group, and adamantylmethyl group; C2 to 40 alkenyl groups such as vinyl group, allyl group, propenyl group, butenyl group, and hexenyl group; C3 to 40 unsaturated aliphatic hydrocarbyl groups such as cyclohexenyl group; phenyl group, naphthyl group, alkylphenyl group (2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butyl ... Examples of the alkyl groups include aryl groups having 6 to 40 carbon atoms, such as aryl groups (e.g., t-butylphenyl group, 4-n-butylphenyl group), dialkylphenyl groups (e.g., 2,4-dimethylphenyl group, 2,4,6-triisopropylphenyl group), alkylnaphthyl groups (e.g., methylnaphthyl group, ethylnaphthyl group), and dialkylnaphthyl groups (e.g., dimethylnaphthyl group, diethylnaphthyl group); and aralkyl groups having 7 to 40 carbon atoms, such as benzyl group, 1-phenylethyl group, and 2-phenylethyl group.

[0096] Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a cyano group, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like. Examples of the hydrocarbyl group containing a heteroatom include heteroaryl groups such as a thienyl group; alkoxyphenyl groups such as a 4-hydroxyphenyl group, a 4-methoxyphenyl group, a 3-methoxyphenyl group, a 2-methoxyphenyl group, a 4-ethoxyphenyl group, a 4-tert-butoxyphenyl group, and a 3-tert-butoxyphenyl group; alkoxynaphthyl groups such as a methoxynaphthyl group, an ethoxynaphthyl group, an n-propoxynaphthyl group, and an n-butoxynaphthyl group; dialkoxynaphthyl groups such as a dimethoxynaphthyl group and a diethoxynaphthyl group; and aryloxoalkyl groups such as a 2-aryl-2-oxoethyl group, a 2-(1-naphthyl)-2-oxoethyl group, and a 2-(2-naphthyl)-2-oxoethyl group.

[0097] In formula (C), R 102 R is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. 102 Examples of the hydrocarbyl group represented by R 101 Examples of the hydrocarbyl group include the same as those exemplified above. Other specific examples include fluorine-containing alkyl groups such as a trifluoromethyl group, a trifluoroethyl group, a 2,2,2-trifluoro-1-methyl-1-hydroxyethyl group, and a 2,2,2-trifluoro-1-(trifluoromethyl)-1-hydroxyethyl group; and fluorine-containing aryl groups such as a pentafluorophenyl group and a 4-trifluoromethylphenyl group.

[0098] In formula (D), R 103represents a saturated hydrocarbyl group having 1 to 8 carbon atoms and at least three fluorine atoms, or an aryl group having 6 to 10 carbon atoms and at least three fluorine atoms, and the saturated hydrocarbyl group and aryl group may contain a nitro group.

[0099] In formulas (B), (C) and (D), Mq + is an onium cation. The onium cation is preferably a sulfonium cation represented by the following formula (B-1), an iodonium cation represented by the following formula (C-1), or an ammonium cation represented by the following formula (D-1). [ka]

[0100] In formulas (B-1), (C-1) and (D-1), R 111 ~R 119 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 111 and R 112 may be bonded to each other to form a ring together with the sulfur atom to which they are attached, and R 116 and R 117 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

[0101] R 111 ~R 119The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, heptadecyl, octadecyl, nonadecyl, and icosyl groups; cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; alkenyl groups having 2 to 20 carbon atoms, such as vinyl, propenyl, butenyl, and hexenyl groups; and cyclohexyl. Examples of such alkyl groups include cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 20 carbon atoms, such as phenyl, propynyl, and norbornenyl; alkynyl groups having 2 to 20 carbon atoms, such as ethynyl, propynyl, and butynyl; aryl groups having 6 to 20 carbon atoms, such as phenyl, methylphenyl, ethylphenyl, n-propylphenyl, isopropylphenyl, n-butylphenyl, isobutylphenyl, sec-butylphenyl, tert-butylphenyl, naphthyl, methylnaphthyl, ethylnaphthyl, n-propylnaphthyl, isopropylnaphthyl, n-butylnaphthyl, isobutylnaphthyl, sec-butylnaphthyl, and tert-butylnaphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl and phenethyl; and groups obtained by combining these groups. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc.

[0102] Also, Mq + As the onium cation represented by the formula (I), the sulfonium cation of the sulfonium salt represented by the formula (A) can also be preferably used.

[0103] Another example of the quencher is the polymer-type quencher described in JP 2008-239918 A. This quencher enhances the rectangularity of the resist pattern by orienting on the surface of the resist film. The polymer-type quencher also has the effect of preventing pattern thinning and rounding of the pattern top when a protective film for immersion lithography is applied.

[0104] When the negative resist composition of the present invention contains the quencher, the content thereof is preferably 0 to 5 parts by mass, more preferably 0 to 4 parts by mass, relative to 100 parts by mass of the base polymer. The quencher may be used alone or in combination of two or more types.

[0105] [Other ingredients] In addition to the above-mentioned components, the negative resist material of the present invention may also contain an acid generator other than the sulfonium salt represented by Formula (A) (hereinafter also referred to as “other acid generator”), a surfactant, a crosslinking agent, a radical generator, a radical scavenger, a water repellency improver, acetylene alcohols, etc.

[0106] Examples of the other acid generator include compounds (photoacid generators) that generate acid in response to actinic rays or radiation. The photoacid generator may be any compound that generates an acid upon exposure to high-energy rays, but is preferably one that generates a sulfonic acid, an imide acid, or a methide acid. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, and oxime-O-sulfonate-type acid generators. Specific examples of acid generators include those described in paragraphs

[0122] to

[0142] of JP 2008-111103 A, JP 2018-5224 A, and JP 2018-25789 A. When the negative resist material of the present invention contains another acid generator, the content thereof is preferably 0 to 200 parts by mass, and more preferably 0.1 to 100 parts by mass, per 100 parts by mass of the base polymer. The other acid generators may be used alone or in combination of two or more.

[0107] Examples of the surfactant include those described in paragraphs

[0165] and

[0166] of JP 2008-111103 A. Adding a surfactant can further improve or control the coatability of the resist material. When the negative resist material of the present invention contains the surfactant, the content thereof is preferably 0.0001 to 10 parts by mass per 100 parts by mass of the base polymer. The surfactant may be used alone or in combination of two or more types.

[0108] Adding a crosslinking agent to the negative resist material of the present invention can further reduce the dissolution rate of the exposed area, thereby improving the rectangularity of the negative pattern. Examples of crosslinking agents include epoxy compounds, melamine compounds, guanamine compounds, glycoluril compounds, urea compounds, isocyanate compounds, azide compounds, and compounds containing double bonds, such as alkenyloxy groups, acrylic groups, methacrylic groups, and styryl groups, all substituted with at least one group selected from methylol groups, alkoxymethyl groups, and acyloxymethyl groups. These may be used as additives or may be introduced as pendant groups into polymer side chains. Hydroxy-containing compounds may also be used as crosslinking agents.

[0109] Examples of the epoxy compound include tris(2,3-epoxypropyl) isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, and triethylolethane triglycidyl ether.

[0110] Examples of the melamine compound include hexamethylol melamine, hexamethoxymethyl melamine, a compound in which 1 to 6 methylol groups of hexamethylol melamine are methoxymethylated, or a mixture thereof, hexamethoxyethyl melamine, hexaacyloxymethyl melamine, a compound in which 1 to 6 methylol groups of hexamethylol melamine are acyloxymethylated, or a mixture thereof.

[0111] Examples of the guanamine compound include tetramethylolguanamine, tetramethoxymethylguanamine, a compound in which 1 to 4 methylol groups of tetramethylolguanamine are methoxymethylated, or a mixture thereof; tetramethoxyethylguanamine, tetraacyloxyguanamine, a compound in which 1 to 4 methylol groups of tetramethylolguanamine are acyloxymethylated, or a mixture thereof; and the like.

[0112] Examples of glycoluril compounds include tetramethylol glycoluril, tetramethoxy glycoluril, tetramethoxymethyl glycoluril, compounds in which 1 to 4 methylol groups of tetramethylol glycoluril have been methoxymethylated or mixtures thereof, and compounds in which 1 to 4 methylol groups of tetramethylol glycoluril have been acyloxymethylated or mixtures thereof.

[0113] Examples of the urea compound include tetramethylol urea, tetramethoxymethyl urea, a compound in which 1 to 4 methylol groups of tetramethylol urea are methoxymethylated, or a mixture thereof, and tetramethoxyethyl urea.

[0114] Examples of the isocyanate compound include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and cyclohexane diisocyanate.

[0115] Examples of the azide compound include 1,1'-biphenyl-4,4'-bisazide, 4,4'-methylidenebisazide, and 4,4'-oxybisazide.

[0116] Examples of compounds containing an alkenyloxy group include ethylene glycol divinyl ether, triethylene glycol divinyl ether, 1,2-propanediol divinyl ether, 1,4-butanediol divinyl ether, tetramethylene glycol divinyl ether, neopentyl glycol divinyl ether, trimethylolpropane trivinyl ether, hexanediol divinyl ether, 1,4-cyclohexanediol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, sorbitol tetravinyl ether, sorbitol pentavinyl ether, and trimethylolpropane trivinyl ether.

[0117] When the negative resist composition of the present invention contains the crosslinking agent, the content thereof is preferably 0.1 to 50 parts by mass, and more preferably 1 to 40 parts by mass, relative to 100 parts by mass of the base polymer. The crosslinking agents may be used alone or in combination of two or more.

[0118] The negative resist material of the present invention may contain a radical generator to increase the reactivity of the double bond in the acid generator. The radical generator is preferably a photoradical generator, and specific examples thereof include acetophenone, 4,4'-dimethoxybenzyl, benzyl, benzoin, benzophenone, 2-benzoylbenzoic acid, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, benzoin isobutyl ether, 4-benzoylbenzoic acid, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, methyl 2-benzoylbenzoate, 2-(1,3-benzodioxol-5-yl)-4,6-bis(trichloromethyl)-1,3,5-trimethylbenzoate, and the like. Examples of suitable acetophenones include riazine, 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone, 4,4'-dichlorobenzophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,4-diethylthioxanthen-9-one, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 1,4-dibenzoylbenzene, 2-ethylanthraquinone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methylpropiophenone, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 2-isonitrosopropiophenone, 2-phenyl-2-(p-toluenesulfonyloxy)acetophenone (BAPO), and camphorquinone.

[0119] When the negative resist composition of the present invention contains the radical generator, the content thereof is preferably 0.1 to 50 parts by mass relative to 100 parts by mass of the base polymer. The radical generator may be used alone or in combination of two or more types.

[0120] The negative resist material of the present invention may contain a radical scavenger to suppress radical diffusion. Examples of the radical scavenger include hindered phenol compounds, quinone compounds, hindered amine compounds, thiol compounds, and TEMPO compounds. Specifically, examples of hindered phenol compounds include dibutylhydroxytoluene (BHT) and 2,2'-methylenebis(4-methyl-6-tert-butylphenol) (ANTAGE W-400). Examples of quinone compounds include 4-methoxyphenol (methoquinone) and hydroquinone. Examples of hindered amine compounds include 2,2,6,6-tetramethylpiperidine. Examples of thiol compounds include dodecanethiol and hexadecanethiol. Examples of TEMPO compounds include 2,2,6,6-tetramethylpiperidine N-oxy radical.

[0121] When the negative resist composition of the present invention contains the radical scavenger, the content thereof is preferably 0 to 5 parts by mass, more preferably 0 to 4 parts by mass, relative to 100 parts by mass of the base polymer. The radical scavenger may be used alone or in combination of two or more types.

[0122] The water repellency improver improves the water repellency of the resist film surface and can be used in immersion lithography without a topcoat. Preferred examples of the water repellency improver include polymers containing fluorinated alkyl groups and polymers containing a specific 1,1,1,3,3,3-hexafluoro-2-propanol residue structure, with those exemplified in JP-A Nos. 2007-297590 and 2008-111103 being more preferred. The water repellency improver must be soluble in an organic solvent developer. The water repellency improver having the specific 1,1,1,3,3,3-hexafluoro-2-propanol residue described above has good solubility in the developer. As a water repellency improver, polymers containing repeating units containing amino groups or amine salts are highly effective in preventing the evaporation of acid during PEB and preventing poor opening of hole patterns after development. When the negative resist composition of the present invention contains a water repellency improver, the content thereof is preferably 0 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, relative to 100 parts by mass of the base polymer. The water repellency improver may be used alone or in combination of two or more.

[0123] Examples of the acetylene alcohols include those described in paragraphs

[0179] to

[0182] of JP 2008-122932 A. When the negative resist material of the present invention contains an acetylene alcohol, the content thereof is preferably 0 to 5 parts by mass per 100 parts by mass of the base polymer. The acetylene alcohols may be used alone or in combination of two or more.

[0124] [Pattern formation method] When the negative resist material of the present invention is used in the manufacture of various integrated circuits, known lithography techniques can be applied. For example, a pattern formation method can include a method comprising the steps of forming a resist film on a substrate using the negative resist material, exposing the resist film to high-energy radiation, and developing the exposed resist film using a developer.

[0125] First, the negative resist material of the present invention is applied to a substrate for integrated circuit manufacturing (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflective coating, etc.) or a substrate for mask circuit manufacturing (Cr, CrO, CrON, MoSi2, SiO2, etc.) by an appropriate coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, doctor coating, etc., to a coating thickness of 0.01 to 2 μm. This is then prebaked on a hot plate, preferably at 60 to 150°C for 10 seconds to 30 minutes, more preferably at 80 to 120°C for 30 seconds to 20 minutes, to form a resist film.

[0126] Next, the resist film is exposed to high-energy radiation. Examples of the high-energy radiation include ultraviolet radiation, far ultraviolet radiation, EB, EUV radiation with a wavelength of 3 to 15 nm, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation. When ultraviolet radiation, far ultraviolet radiation, EUV radiation, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation are used as the high-energy radiation, the exposure dose is preferably 1 to 200 mJ / cm, either directly or using a mask for forming a desired pattern. 2 approximately, more preferably 10 to 100 mJ / cm 2 When EB is used as the high energy beam, the exposure dose is preferably 0.1 to 500 μC / cm 2 approximately, more preferably 0.5 to 400 μC / cm 2 The negative resist material of the present invention is particularly suitable for fine patterning using high-energy rays such as KrF excimer laser light, ArF excimer laser light, EB, EUV, X-rays, soft X-rays, γ-rays, and synchrotron radiation, and is particularly suitable for fine patterning using EB or EUV.

[0127] During exposure to high-energy radiation, the double bonds of the acid generator represented by formula (A) in the exposed areas of the resist film polymerize, causing a crosslinking reaction. As the crosslinking reaction progresses, the remaining film in the exposed areas increases, improving dissolution contrast and increasing the mechanical strength of the film in the exposed areas, making pattern collapse less likely to occur.

[0128] After exposure, PEB may or may not be performed on a hot plate or in an oven, preferably at 30 to 150° C. for 10 seconds to 30 minutes, more preferably at 50 to 120° C. for 30 seconds to 20 minutes.

[0129] A negative pattern is then obtained by organic solvent development. Developers used in this process include 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, isopentyl acetate, 2-methylbutyl acetate, hexyl acetate, butenyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonate, Examples of the organic solvent include ethyl crotonate, methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, 2-phenylethyl acetate, etc. These organic solvents may be used alone or in combination of two or more.

[0130] After the development is completed, the resist film is rinsed. A solvent that is miscible with the developer but does not dissolve the resist film is preferred as the rinse solution. Preferred examples of such solvents include alcohols having 3 to 10 carbon atoms, ether compounds having 8 to 12 carbon atoms, alkanes, alkenes, alkynes, and aromatic solvents having 6 to 12 carbon atoms.

[0131] Specific examples of alcohols having 3 to 10 carbon atoms include n-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-pentyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, and 3-hexanol. , 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol, 1-octanol, and the like.

[0132] Examples of the ether compound having 8 to 12 carbon atoms include di-n-butyl ether, diisobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, di-sec-pentyl ether, di-tert-pentyl ether, and di-n-hexyl ether.

[0133] Examples of alkanes having 6 to 12 carbon atoms include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, cyclononane, etc. Examples of alkenes having 6 to 12 carbon atoms include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, cyclooctene, etc. Examples of alkynes having 6 to 12 carbon atoms include hexyne, heptine, octyne, etc.

[0134] Examples of aromatic solvents include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, and mesitylene.

[0135] Rinsing can reduce the occurrence of resist pattern collapse and defects. Rinsing is not always necessary, and not performing rinsing can reduce the amount of solvent used.

[0136] The developed hole or trench pattern can also be shrunk using thermal flow, RELACS, or DSA. A shrink agent is applied to the hole pattern, and the diffusion of an acid catalyst from the resist film during baking causes crosslinking of the shrink agent on the surface of the resist film, resulting in adhesion of the shrink agent to the sidewalls of the hole pattern. The baking temperature is preferably 70 to 180°C, more preferably 80 to 170°C, and the baking time is preferably 10 to 300 seconds. Excess shrink agent is removed, and the hole pattern is shrunk. [Example]

[0137] The present invention will be specifically explained below by showing synthesis examples, examples and comparative examples, but the present invention is not limited to the following examples.

[0138] The structures of the acid generators PAG-1 to PAG-15 used in the resist material are shown below. PAG-1 to PAG-15 were synthesized by ion exchange between the ammonium salt of a fluorinated sulfonic acid, which gives the anion shown below, and a sulfonium chloride, which gives the cation shown below. [ka]

[0139] [ka]

[0140] [ka]

[0141] [Synthesis Example] Synthesis of base polymers (polymers P-1 to P-5) Each monomer was combined and copolymerized in THF solvent, then added to methanol. The precipitated solid was washed with hexane, isolated, and dried to obtain the base polymers (polymers P-1 to P-5) with the following compositions. 1 Mw and Mw / Mn were confirmed by H-NMR and GPC (solvent: THF, standard: polystyrene). [ka]

[0142] [ka]

[0143] [Examples 1 to 24, Comparative Examples 1 to 4] Preparation and Evaluation of Negative Resist Materials (1) Preparation of negative resist material A negative resist material was prepared by dissolving each component in the composition shown in Tables 1 and 2 in a solvent containing 100 ppm of Omnova's Polyfox PF-636 surfactant. The solution was then filtered through a 0.2 μm filter.

[0144] In Tables 1 and 2, the components are as follows: Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) PGME (Propylene Glycol Monomethyl Ether) EL (Ethyl lactate) DAA (diacetone alcohol)

[0145] Comparative Acid Generators: cPAG-1 to cPAG-4 [ka]

[0146] Quencher: Q-1~Q-4 [ka]

[0147] Radical scavengers: RC-1, RC-2 [ka]

[0148] Crosslinker: CL-1 [ka]

[0149] (2) EB lithography evaluation A silicon substrate was coated with Nissan Chemical's DUV-42 and baked at 200°C for 60 seconds to form an antireflective film (60 nm thick). Each negative resist material listed in Tables 1 and 2 was spin-coated onto the antireflective film and prebaked at 105°C for 60 seconds using a hot plate to produce a 35 nm thick resist film. Using an Elionix ELS-F125 EB lithography system, lithography was performed at an acceleration voltage of 125 kV and a current of 50 pA. Post-exposure bake (PEB) was performed on the hot plate at the temperatures listed in Tables 1 and 2 for 60 seconds. The substrate was then developed with 2-methylbutyl acetate for 30 seconds, followed by spin drying, yielding a 30 nm line-and-space 1:1 pattern. The formed pattern was observed using a critical dimension SEM (CG5000) manufactured by Hitachi High-Technologies Corporation. The exposure dose required to obtain 30 nm lines and spaces was taken as the sensitivity, and the minimum line width (nm) of the separated lines and spaces at that exposure dose was determined and taken as the limiting resolution. The results are shown in Tables 1 and 2.

[0150] [Table 1]

[0151] [Table 2]

[0152] The results shown in Tables 1 and 2 demonstrate that the negative resist composition of the present invention, which contains sulfonium salt A as an acid generator, is excellent in limiting resolution.

Claims

1. A negative resist material comprising: a base polymer; and an acid generator which is a sulfonium salt composed of a sulfonate anion having a hydrocarbyl group substituted with an iodine atom or a bromine atom (excluding those in which the iodine atom or the bromine atom is bonded to a carbon atom on an aromatic ring), and a cation having a polymerizable double bond; The negative resist material, wherein the sulfonium salt is represented by the following formula (A): 【Chemistry 1】 (In the formula, k 1 is an integer of 1 to 3. k 2 is an integer of 1 to 3. m is an integer of 1 to 3, and n is an integer of 0 to 2, provided that m+n=3. p is 1 or 2, and q is an integer of 0 to 4, provided that 1≦p+q≦5. r is an integer of 0 to 5. X BI is a bromine atom or an iodine atom. R is a (k 1 + 1)-valent aliphatic hydrocarbon group having 1 to 20 carbon atoms, and the aliphatic hydrocarbon group may contain at least one bond selected from a fluorine atom, a chlorine atom, a hydroxy group, a carboxy group, an aryl group having 6 to 12 carbon atoms, an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate bond, a urethane bond, and a urea bond. When k2 is 1, X1 is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom, and when k2 is 2 or 3, X1 is a (k2 + 1)-valent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. X 2 is a single bond, an ester bond or an ether bond. X 3 is a single bond or an aliphatic hydrocarbylene group having 1 to 10 carbon atoms. X 4 is a single bond, an ester bond, an ether bond, an amide bond, a urethane bond or an alkanediyl group having 1 to 10 carbon atoms, and some of the —CH 2 — groups in the alkanediyl group may be substituted with ester bonds, ether bonds, amide bonds or urethane bonds. R 1 to R 3 are each independently a hydrogen atom, a halogen atom, or a saturated hydrocarbyl group having 1 to 40 carbon atoms, and some or all of the hydrogen atoms in the saturated hydrocarbyl group may be substituted with fluorine atoms or hydroxy groups, some of the —CH 2 — groups in the saturated hydrocarbyl group may be substituted with ether bonds or ester bonds, and some of the carbon-carbon bonds in the saturated hydrocarbyl group may be double bonds. R 4 and R 5 are each independently a halogen atom, a cyano group, a nitro group, a mercapto group, a sulfo group, a saturated hydrocarbyl group having 1 to 10 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, and the saturated hydrocarbyl group and aralkyl group may contain an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom. Furthermore, two R 4s or two R 5s may be bonded to each other to form a ring together with the benzene ring to which they are bonded, or R 4 and R 5 may be bonded to each other to form a ring together with the benzene ring to which they are bonded and the sulfur atom therebetween. Rf 1 to Rf 4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, provided that at least one of them is a fluorine atom or a trifluoromethyl group. Rf 1 and Rf 2 may combine to form a carbonyl group.

2. 2. The negative resist material according to claim 1, wherein the base polymer contains a repeating unit represented by the following formula (a1): 【Chemistry 2】 (In the formula, R A are each independently a hydrogen atom or a methyl group. Y 1 is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms and containing at least one bond selected from an ester bond, an ether bond, and a lactone ring. R 11 is an acid labile group.

3. 2. The negative resist material according to claim 1, further comprising an organic solvent.

4. 2. The negative resist material according to claim 1, further comprising a quencher.

5. 2. The negative resist material according to claim 1, further comprising a crosslinking agent.

6. 2. The negative resist material according to claim 1, further comprising a surfactant.

7. A pattern forming method comprising the steps of: forming a resist film on a substrate using the negative resist material according to any one of claims 1 to 6; exposing the negative resist film to high-energy rays; and developing the exposed negative resist film using an organic solvent developer.

8. The organic solvent developer may be selected from the group consisting of 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, isopentyl acetate, 2-methylbutyl acetate, hexyl acetate, butenyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonate, ethyl crotonate, propionate, 8. The pattern formation method according to claim 7, wherein the lactone is at least one selected from the group consisting of methyl lactate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, and 2-phenylethyl acetate.

9. 8. The pattern forming method according to claim 7, wherein the high-energy beam is a KrF excimer laser beam, an ArF excimer laser beam, an electron beam, or extreme ultraviolet light having a wavelength of 3 to 15 nm.

Images