Resist material and pattern forming method

Abstract

To provide a resist material highly sensitive and small in LWR and CDU both in a positive type resist material and in a negative type resist material since the development of a quencher capable of reducing LWR of a line pattern, and dimensional uniformity (CDU) of a hole pattern, and capable of improving sensitivity is desired in a chemical amplification resist material which requires an acid as a catalyst, therefore it is necessary to lessen blur of an image caused by diffusion of an acid, and a method of forming a pattern using the same.SOLUTION: A resist material contains a quencher, where the quencher contains a sulphonium salt of a carboxylic acid which bonds to a maleimide group.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a resist material and a patterning method.

Background Art

[0002] With the increasing integration density and speed of LSIs, the miniaturization of pattern rules has been rapidly progressing. This is because the high-speed communication of 5G and the spread of artificial intelligence (AI) are advancing, and high-performance devices for processing these are required. As the most advanced miniaturization technology, mass production of 5nm node devices by extreme ultraviolet (EUV) lithography with a wavelength of 13.5nm is being carried out. Furthermore, studies using EUV lithography are also underway for next-generation 3nm node and next-next-generation 2nm node devices.

[0003] As miniaturization progresses, image blur due to acid diffusion has become a problem. In order to ensure the resolution of fine patterns with a dimensional size of 45nm or less, it has been proposed that not only the improvement of the dissolution contrast conventionally proposed but also the control of acid diffusion is important (Non-Patent Document 1). However, since chemically amplified resist materials increase sensitivity and contrast by acid diffusion, if the post-exposure bake (PEB) temperature is lowered or the time is shortened to suppress acid diffusion to the limit, the sensitivity and contrast will significantly decrease.

[0004] The triangular trade-off relationship of sensitivity, resolution, and edge roughness is shown. In order to improve the resolution, it is necessary to suppress acid diffusion, but when the acid diffusion distance becomes short, the sensitivity decreases.

[0005] It is effective to suppress acid diffusion by adding an acid generator that generates a bulky acid. Therefore, it has been proposed to include in the polymer a repeating unit derived from an onium salt having a polymerizable unsaturated bond. At this time, the polymer also functions as an acid generator (polymer-bound acid generator). Patent Document 1 proposes sulfonium salts and iodonium salts having a polymerizable unsaturated bond that generate specific sulfonic acids. Patent Document 2 proposes a sulfonium salt in which a sulfonic acid is directly bonded to the main chain.

[0006] For the acid-labile group used in the (meth)acrylate polymer for ArF resist materials, the deprotection reaction proceeds by using a photoacid generator that generates a sulfonic acid in which the α-position is substituted with fluorine, but the deprotection reaction does not proceed with an acid generator that generates a sulfonic acid or carboxylic acid in which the α-position is not substituted with fluorine. When a sulfonium salt or iodonium salt that generates a sulfonic acid in which the α-position is not substituted with fluorine is mixed with a sulfonium salt or iodonium salt that generates a sulfonic acid in which the α-position is substituted with fluorine, the sulfonium salt or iodonium salt that generates a sulfonic acid in which the α-position is not substituted with fluorine undergoes ion exchange with the sulfonic acid in which the α-position is substituted with fluorine. The sulfonic acid in which the α-position is substituted with fluorine generated by light reverts to the sulfonium salt or iodonium salt by ion exchange, so the sulfonium salt or iodonium salt of a sulfonic acid or carboxylic acid in which the α-position is not substituted with fluorine functions as a quencher. A resist composition using a sulfonium salt or iodonium salt that generates a carboxylic acid as a quencher has been proposed (Patent Document 3).

[0007] An acid generator of a bissulfonium salt having two sulfonium salts in one molecule has been proposed (Patent Documents 3 to 5). The acid generated from the bissulfonium salt has a short diffusion length and is suitable, but the bissulfonium salt has poor solubility in the resist solvent, so it tends to aggregate and potentially has the drawback of increasing pattern defects and edge roughness (LWR).

[0008] The photoreaction of maleimide compounds has been reported (Non-Patent Document 2). Here, compounds having a substituent on the double bond of the maleimide group undergo a dimerization reaction, and maleimide compounds without a substituent cause polymerization in addition to the dimerization reaction. Radical generation from maleimide and the resulting polymerization of acrylate have also been shown.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Non-Patent Documents

[0010]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0011] In a chemically amplified resist material using an acid as a catalyst, it is desired to develop a quencher that can reduce the LWR of line patterns and the dimensional uniformity (CDU) of hole patterns and improve the sensitivity. For this purpose, it is necessary to further reduce the image blur caused by acid diffusion.

[0012] The present invention has been made in view of the above circumstances, and an object thereof is to provide a resist material having high sensitivity and a small CDU, and a pattern forming method using the same, whether it is a positive resist material or a negative resist material.

Means for Solving the Problems

[0013] In order to solve the above problems, the present invention provides a resist material containing a quencher, wherein the quencher contains a sulfonium salt of a carboxylic acid that binds to a maleimide group.

[0014] When such a quencher is contained, it is possible to reduce the LWR of the line pattern and the CDU of the hole pattern, and the sensitivity can also be improved.

[0015] The sulfonium salt of the carboxylic acid that binds to the maleimide group is preferably represented by the following general formula (1).

Chemical formula

[0016] For a quencher having such a structure, it is possible to more reliably reduce the LWR of the line pattern and the CDU of the hole pattern, and the sensitivity can also be improved.

[0017] Furthermore, it preferably contains one or more selected from an acid generator that generates an acid, an organic solvent, and a surfactant.

[0018] If it is such a thing, it will become a better resist material.

[0019] The acid generator preferably generates sulfonic acid, imidic acid or methidic acid.

[0020] If it is such a thing, the sulfonium salt of the carboxylic acid bonded to the maleimide group can function more reliably as a quencher.

[0021] Furthermore, it preferably contains a base polymer.

[0022] The base polymer preferably further contains at least one selected from repeating units represented by the following general formulas (f1) to (f3).

Chemical formula

[0023] Since the base polymer contains such repeating units, these repeating units can function as an acid generator.

[0024] Furthermore, it is preferable that the base polymer contains, as a repeating unit having an acid-labile group, a repeating unit represented by the following general formula (a1) or a repeating unit represented by the following formula (a2).

Chemical formula

[0025] When the above base polymer contains a repeating unit having an acid-labile group, it is preferably a chemically amplified positive resist material.

[0026] When the base polymer contains a repeating unit having an acid-labile group in this way, it functions well as a positive resist material.

[0027] It is preferable that the base polymer does not contain an acid-labile group.

[0028] When the above base polymer does not contain a repeating unit having an acid-labile group, it is preferably a chemically amplified negative resist material.

[0029] When the base polymer does not contain a repeating unit having an acid-labile group in this way, it functions well as a negative-type resist material.

[0030] The present invention also provides a pattern forming method including: (1) a step of forming a resist film on a substrate using the above resist material; (2) a step of exposing the resist film with high-energy rays; and (3) a step of developing the exposed resist film using a developer.

[0031] With such a pattern forming method, a target pattern can be formed well.

[0032] After the step (1) and before the step (2), it is preferable to expose the entire surface of the resist film to light having a wavelength at which the sulfonium salt of the carboxylic acid bonded to the maleimide group does not decompose.

[0033] It is preferable that the wavelength at which the sulfonium salt does not decompose is longer than 300 nm.

[0034] When the entire surface of the resist film is exposed to such light, the maleimide group can polymerize and / or couple to further prevent acid diffusion.

[0035] It is preferable that the high-energy rays are KrF excimer laser light, ArF excimer laser light, electron beams, or extreme ultraviolet rays having a wavelength of 3 to 15 nm.

[0036] By using such high-energy rays, a target pattern can be formed well.

Advantages of the Invention

[0037] The sulfonium salt of the carboxylic acid bonded to the maleimide group is a quencher that suppresses acid diffusion. As a result, the acid has low-diffusion characteristics, making it possible to reduce LWR and CDU, and also improve sensitivity. These make it possible to construct a resist material with low LWR, low CDU, and high sensitivity.

BEST MODE FOR CARRYING OUT THE INVENTION

[0038] In a chemically amplified resist material using an acid as a catalyst, it has been desired to develop a quencher capable of reducing the LWR of line patterns and the dimensional uniformity (CDU) of hole patterns and improving the sensitivity at the same time.

[0039] As a result of intensive studies to achieve the above object, the present inventors have found that a resist material to which a sulfonium salt of a carboxylic acid bonded to a maleimide group is added is a quencher for suppressing acid diffusion, and has a high effect of suppressing acid diffusion by increasing the molecular weight by a coupling reaction of the maleimide group upon light irradiation. Therefore, it has been found that a resist material having low acid diffusion, small LWR and CDU, excellent resolution, and a wide process margin can be obtained, and the present invention has been completed.

[0040] That is, the present invention is A resist material containing a quencher, wherein the quencher contains a sulfonium salt of a carboxylic acid bonded to a maleimide group.

[0041] Hereinafter, the present invention will be described, but the present invention is not limited thereto.

[0042] [Resist Material] The resist material of the present invention contains a quencher of a sulfonium salt of a carboxylic acid bonded to a maleimide group.

[0043] [Sulfonium Salt of Carboxylic Acid Bonded to Maleimide Group] The sulfonium salt of the carboxylic acid bonded to the maleimide group is preferably represented by the following general formula (1). [Chemical Formula] (In the formula, R 1 , R 2is a hydrogen atom, a linear, branched, or cyclic alkyl group having 1 to 10 carbon atoms, and R 1 and R 2 may combine to form a ring. X is a single bond or a divalent linking group having 1 to 20 carbon atoms, and may have an ether group, a carbonyl group, an ester group, an amide group, a sultone group, a lactam group, a carbonate group, a halogen atom, a hydroxy group, or a carboxyl group. R 3 ~R 5 are each independently a monovalent hydrocarbon group having 1 to 25 carbon atoms, which may contain a heteroatom. Further, any two of R 3 , R 4 , and R 5 may combine with each other to form a ring together with the sulfur atom to which they are attached.)

[0044] Examples of the carboxylic acid anion bonded to the maleimide group represented by the general formula (1) include, but are not limited to, those shown below.

[0045]

Chemical formula

[0046]

Chemical formula

[0047]

Chemical formula

[0048]

Chemical formula

[0049]

Chemical formula

[0050]

Chemical formula

[0051]

Chem.

[0052]

Chem.

[0053] Examples of the cation of the sulfonium salt represented by the general formula (1) include, but are not limited to, those shown below.

Chem.

[0054]

Chem.

[0055]

Chem.

[0056]

Chem.

[0057]

Chem.

[0058]

Chem.

[0059]

Chem.

[0060]

Chem.

[0061]

Chem.

[0062]

Chem.

[0063]

Chem.

[0064]

Chem.

[0065]

Chem.

[0066]

Chem.

[0067]

Chem.

[0068]

Chem.

[0069]

Chem.

[0070]

Chem.

[0071] [Chemical formula]

[0072] The compound represented by the above general formula (1) can be synthesized, for example, by ion-exchanging a hydrochloride or carbonate of triphenylsulfonium with a carboxylic acid that binds to the maleimide group.

[0073] In the resist material of the present invention, the content of the sulfonium salt of the carboxylic acid that binds to the maleimide group is preferably 0.001 to 50 parts by mass, more preferably 0.01 to 40 parts by mass, and still more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the base polymer described later. The sulfonium salt of the carboxylic acid that binds to the maleimide group can be used alone or in combination of two or more.

[0074] [Base polymer] The base polymer contained in the resist material of the present invention preferably contains a repeating unit containing an acid-labile group in the case of a positive resist material. As the repeating unit containing an acid-labile group, a repeating unit represented by the following general formula (a1) (hereinafter also referred to as repeating unit a1), or a repeating unit represented by the following general formula (a2) (hereinafter also referred to as repeating unit a2) is preferable. [Chemical formula]

[0075] In the above general formulas (a1) and (a2), R A is independently a hydrogen atom or a methyl group. R 11 and R 12 are acid-labile groups. Y 1 is a single bond, a phenylene group or a naphthylene group, or a linking group having 1 to 12 carbon atoms containing at least one selected from an ester bond and a lactone ring. Y 2 is a single bond, an ester bond or an amide bond. Y 3 is a single bond, an ether bond or an ester bond. R 13is a fluorine atom, a trifluoromethyl group, a cyano group, or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R 14 is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and a part of the carbon atoms thereof may be substituted with an ether bond or an ester bond. a is 1 or 2. b is an integer of 0 to 4. However, 1 ≦ a + b ≦ 5.

[0076] In addition, when the above base polymer contains both the repeating unit a1 and the repeating unit a2, R 11 and R 12 may be the same as or different from each other.

[0077] Examples of the monomer that gives the repeating unit a1 include, but are not limited to, those shown below. In the following formulas, R A and R 11 are the same as those above.

Chemical formula

[0078] Examples of the monomer that gives the repeating unit a2 include, but are not limited to, those shown below. In the following formulas, R A and R 12 are the same as those above.

Chemical formula

[0079] In the above general formulas (a1) and (a2), examples of the acid-labile group represented by R 11 and R 12 include those described in JP-A-2013-80033 and JP-A-2013-83821.

[0080] Typically, examples of the acid-labile group include those represented by the following formulas (AL-1) to (AL-3).

Chemical formula

[0081] In the above general formulas (AL-1) and (AL-2), R L1 and R L2 are each independently a monovalent hydrocarbon group having 1 to 40 carbon atoms, and may contain heteroatoms such as an oxygen atom, a sulfur atom, a nitrogen atom, and a fluorine atom. The monovalent hydrocarbon group may be linear, branched, or cyclic, and an alkyl group having 1 to 40 carbon atoms is preferable, and an alkyl group having 1 to 20 carbon atoms is more preferable. In the above general formula (AL-1), a is an integer of 0 to 10, and an integer of 1 to 5 is preferable.

[0082] In the above general formula (AL-2), R L3 and R L4 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and may contain heteroatoms such as an oxygen atom, a sulfur atom, a nitrogen atom, and a fluorine atom. The monovalent hydrocarbon group may be linear, branched, or cyclic, and an alkyl group having 1 to 20 carbon atoms is preferable. Further, any two of R L2 and R L3 and R L4 may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom to which they are bonded or the carbon atom and the oxygen atom. As the above ring, a ring having 4 to 16 carbon atoms is preferable, and an alicyclic ring is particularly preferable.

[0083] In the above general formula (AL-3), R L5 and R L6 and R L7 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, and may contain heteroatoms such as an oxygen atom, a sulfur atom, a nitrogen atom, and a fluorine atom. The monovalent hydrocarbon group may be linear, branched, or cyclic, and an alkyl group having 1 to 20 carbon atoms is preferable. Further, any two of R L5 and R L6 and R L7 may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom to which they are bonded. As the above ring, a ring having 4 to 16 carbon atoms is preferable, and an alicyclic ring is particularly preferable.

[0084] The above base polymer may further contain a repeating unit b containing a phenolic hydroxy group as an adhesion group. Examples of the monomer that provides the repeating unit b include, but are not limited to, the following. In the following formula, R A is the same as above.

Chemical formula

[0085]

Chemical formula

[0086]

Chemical formula

[0087] The above base polymer may further contain a repeating unit c containing a hydroxy group other than a phenolic hydroxy group, a lactone ring, an ether bond, an ester bond, a carbonyl group, a cyano group, or a carboxy group as another adhesion group. Examples of the monomer that provides the repeating unit c include, but are not limited to, the following. In the following formula, R A is the same as above.

[0088]

Chemical formula

[0089]

Chemical formula

[0090]

Chemical formula

[0091]

Chemical formula

[0092]

Chem.

[0093]

Chem.

[0094]

Chem.

[0095]

Chem.

[0096] The above 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.

Chem.

[0097] The above base polymer may further contain a repeating unit e derived from styrene, vinylnaphthalene, vinylanthracene, vinylpyrene, methylene indane, vinylpyridine or vinylcarbazole.

[0098] The base polymer may further contain a repeating unit f derived from an onium salt containing a polymerizable unsaturated bond. Preferred repeating units f include a repeating unit represented by the following general formula (f1) (hereinafter also referred to as repeating unit f1), a repeating unit represented by the following general formula (f2) (hereinafter also referred to as repeating unit f2), and a repeating unit represented by the following general formula (f3) (hereinafter also referred to as repeating unit f3). The repeating units f1 to f3 can be used alone or in combination of two or more.

Chemical formula

[0099] In the above general formulas (f1) to (f3), R A is independently a hydrogen atom or a methyl group. Z 1 is a single bond, a phenylene group, a naphthylene group, -Z 11 -, -O-Z 11 -, -C(=O)-O-Z 11 - or -C(=O)-NH-Z 11 -, and Z 11 is an alkanediyl group having 1 to 6 carbon atoms, an alkenediyl group having 2 to 6 carbon atoms, or a hydrocarbon group having 1 to 20 carbon atoms which may contain a phenylene group, and may contain a carbonyl group, an ester bond, an ether bond or a hydroxy group. Z 2A is a single bond or an ester bond. Z 2B is a single bond or a divalent group having 1 to 18 carbon atoms, and may contain an ester bond, an ether bond, a lactone ring, a bromine atom or an iodine atom. Z 3 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -Z 31 -, -O-Z 31 -, -C(=O)-O-Z 31 - or -C(=O)-NH-Z 31 -, and Z 31is a group containing an alkanediyl group having 1 to 15 carbon atoms, an alkenediyl group having 2 to 15 carbon atoms or a phenylene group, and may contain a carbonyl group, an ester bond, an ether bond, a halogen atom or a hydroxy group. Rf 1 ~Rf 4 are each independently a hydrogen atom, a fluorine atom, an oxygen atom or a trifluoromethyl group, and at least one of them is a fluorine atom, Rf 1 and Rf 2 is an oxygen atom, Rf 1 and Rf 2 is one oxygen atom bonded to one carbon atom to form a carbonyl group.

[0100] In the above general formulas (f1) to (f3), R 21 ~R 28 are each independently a monovalent hydrocarbon group having 1 to 25 carbon atoms which may contain a hetero atom. The monovalent hydrocarbon group may be linear, branched or cyclic, and specific examples thereof include an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, etc. Further, some or all of the hydrogen atoms of these groups may be substituted with an alkyl group having 1 to 10 carbon atoms, a halogen atom, a trifluoromethyl group, a cyano group, a nitro group, a hydroxy group, a mercapto group, an alkoxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 2 to 10 carbon atoms, or an acyloxy group having 2 to 10 carbon atoms, and some of the carbon atoms of these groups may be substituted with a carbonyl group, an ether bond or an ester bond. Also, any two of R 23 , R 24 and R 25 or any two of R 26 , R 27 and R 28 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded.

[0101] In the above general formula (f1), M -is a non-nucleophilic counter ion. Examples of the non-nucleophilic counter ion include halide ions such as chloride ion and bromide ion, fluoroalkylsulfonate ions such as triflate ion, 1,1,1-trifluoroethanesulfonate ion, and nonafluorobutanesulfonate ion, arylsulfonate ions such as tosylate ion, benzenesulfonate ion, 4-fluorobenzenesulfonate ion, and 1,2,3,4,5-pentafluorobenzenesulfonate ion, alkylsulfonate ions such as mesylate ion and butanesulfonate ion, imide acid ions such as bis(trifluoromethylsulfonyl)imide ion, bis(perfluoroethylsulfonyl)imide ion, and bis(perfluorobutylsulfonyl)imide ion, and methide acid ions such as tris(trifluoromethylsulfonyl)methide ion and tris(perfluoroethylsulfonyl)methide ion.

[0102] Examples of the non-nucleophilic counter ion further include sulfonate ions in which the α-position is substituted with fluorine and represented by the following general formula (f1-1), sulfonate ions in which the α-position is substituted with fluorine and the β-position is substituted with a trifluoromethyl group and represented by the following general formula (f1-2), and the like. [Chemical formula]

[0103] In the above general formula (f1-1), R 31 is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and may contain an ether bond, an ester bond, a carbonyl group, a lactone ring, or a fluorine atom. The alkyl group and the alkenyl group may be linear, branched, or cyclic.

[0104] In the above general formula (f1-2), R 32is a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an acyl group having 2 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aryloxy group having 6 to 20 carbon atoms, and may contain an ether bond, an ester bond, a carbonyl group or a lactone ring. The above alkyl group, acyl group and alkenyl group may be linear, branched or cyclic.

[0105] Examples of the cation of the monomer that gives the repeating unit f1 include, but are not limited to, those shown below. In the following formulas, R A is the same as above.

Chemical formula

[0106] Examples of the anion of the monomer that gives the repeating unit f2 include, but are not limited to, those shown below. In the following formulas, R A is the same as above.

Chemical formula

[0107]

Chemical formula

[0108]

Chemical formula

[0109]

Chemical formula

[0110]

Chemical formula

[0111]

Chemical formula

[0112]

Chem.

[0113]

Chem.

[0114]

Chem.

[0115]

Chem.

[0116]

Chem.

[0117]

Chem.

[0118] Examples of the anion of the monomer that gives the repeating unit f3 include, but are not limited to, those shown below. In the following formulas, R A is the same as above.

Chem.

[0119]

Chem.

[0120]

Chem.

[0121] The repeating units f1 to f3 have the function of an acid generator. By bonding the acid generator to the polymer main chain, acid diffusion can be reduced, and a decrease in resolution due to blurring of acid diffusion can be prevented. In addition, the edge roughness and dimensional variations are improved by the uniform dispersion of the acid generator. When using a base polymer containing the repeating units f1 to f3, the blending of the additive acid generator described later can be omitted.

[0122] As the cations of the sulfonium salts of the repeating units f2 and f3, those mentioned above can be used as the cations of the sulfonium salts described by the general formula (1).

[0123] In the above base polymer, the content ratios of the repeating units a1, a2, b, c, d, e, f1, f2, and f3 are preferably 0≦a1≦0.9, 0≦a2≦0.9, 0≦a1 + a2≦0.9, 0≦b≦0.9, 0≦c≦0.9, 0≦d≦0.5, 0≦e≦0.5, 0≦f1≦0.5, 0≦f2≦0.5, 0≦f3≦0.5, 0≦f1 + f2 + f3≦0.5; more preferably 0≦a1≦0.8, 0≦a2≦0.8, 0≦a1 + a2≦0.8, 0≦b≦0.8, 0≦c≦0.8, 0≦d≦0.4, 0≦e≦0.4, 0≦f1≦0.4, 0≦f2≦0.4, 0≦f3≦0.4, 0≦f1 + f2 + f3≦0.4; still more preferably 0≦a1≦0.7, 0≦a2≦0.7, 0≦a1 + a2≦0.7, 0≦b≦0.7, 0≦c≦0.7, 0≦d≦0.3, 0≦e≦0.3, 0≦f1≦0.3, 0≦f2≦0.3, 0≦f3≦0.3, 0≦f1 + f2 + f3≦0.3. However, a1 + a2 + b + c + d + e + f1 + f2 + f3 = 1.0.

[0124] To synthesize the above base polymer, for example, monomers that provide the above-described repeating units may be heated in an organic solvent with the addition of a radical polymerization initiator to perform polymerization.

[0125] Examples of the organic solvent used during polymerization include toluene, benzene, tetrahydrofuran, diethyl ether, dioxane, etc. Examples of the polymerization initiator include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, lauroyl peroxide, etc. The temperature during polymerization is preferably 50 to 80°C. The reaction time is preferably 2 to 100 hours, more preferably 5 to 20 hours.

[0126] When copolymerizing a monomer containing a hydroxy group, during polymerization, the hydroxy group may be substituted with an acetal group that is easily deprotected by an acid such as an ethoxyethoxy group, and then deprotected with a weak acid and water after polymerization, or it may be substituted with an acetyl group, a formyl group, a pivaloyl group, etc., and then subjected to alkaline hydrolysis after polymerization.

[0127] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, instead of hydroxystyrene or hydroxyvinylnaphthalene, acetoxystyrene or acetoxyvinylnaphthalene may be used, and after polymerization, the acetoxy group may be deprotected by the above-mentioned alkaline hydrolysis to obtain hydroxystyrene or hydroxyvinylnaphthalene.

[0128] Examples of the base used during alkaline hydrolysis include aqueous ammonia, triethylamine, etc. Also, 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.

[0129] The above base polymer preferably has a polystyrene-reduced weight average molecular weight (Mw) of 1,000 to 500,000, more preferably 2,000 to 30,000, and still more preferably 3,000 to 10,000 as measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent. When Mw is 1,000 or more, the resist material has excellent heat resistance, and when it is 500,000 or less, the alkali solubility is good, and the trailing phenomenon is less likely to occur after pattern formation.

[0130] Furthermore, when the molecular weight distribution (Mw / Mn) of the above base polymer is narrow, since there are no low molecular weight or high molecular weight polymers, no foreign matter is seen on the pattern after exposure, and there is no risk of deterioration of the pattern shape. As the pattern rule becomes finer, the influence of Mw and Mw / Mn tends to increase. Therefore, in order to obtain a resist material suitably used for fine pattern dimensions, the Mw / Mn of the above base polymer is preferably narrowly dispersed at 1.0 to 2.0, particularly 1.0 to 1.5.

[0131] The above base polymer may contain two or more polymers having different composition ratios, Mw, and Mw / Mn.

[0132] [Acid generator] The resist material of the present invention may contain an acid generator that generates a strong acid (hereinafter, also referred to as an additive acid generator). The strong acid referred to here means a compound having sufficient acidity to cause a deprotection reaction of the acid-labile group of the base polymer in the case of a chemically amplified positive resist material, or a compound having sufficient acidity to cause a polarity change reaction or a crosslinking reaction by an acid in the case of a chemically amplified negative resist material.

[0133] By containing such an acid generator, the sulfonium salt of the carboxylic acid bonded to the above-mentioned maleimide group functions as a quencher, and the resist material of the present invention can function as a chemically amplified positive resist material or a chemically amplified negative resist material.

[0134] Examples of the acid generator include compounds that generate an acid upon exposure to actinic rays or radiation (photoacid generators). Any compound that generates an acid upon irradiation with high-energy rays may be used as the photoacid generator, but those that generate sulfonic acid, imidic acid, or methidic acid are preferred. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, oxime-O-sulfonate type acid generators, and the like. Specific examples of the photoacid generator include those described in paragraphs

[0122] to

[0142] of JP-A-2008-111103.

[0135] As the photoacid generator, a sulfonium salt represented by the following general formula (1-1) or an iodonium salt represented by the following general formula (1-2) can also be preferably used.

Chemical formula

[0136] In the above general formulas (1-1) and (1-2), R 101 , R 102 , R 103 , R 104 and R 105 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom. Further, any two of R 101 , R 102 and R 103 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. The monovalent hydrocarbon group may be linear, branched, or cyclic, and specific examples thereof include the same ones as those described above in the description of R 21 to R 28 in the above general formulas (f1) to (f3).

[0137] As the cation of the sulfonium salt represented by the above general formula (1-1), those exemplified above can be used as the cation of the sulfonium salt described in the general formula (1).

[0138] Examples of the cation of the iodonium salt represented by the general formula (1-2) include, but are not limited to, those shown below.

Chem.

[0139] In the general formulas (1-1) and (1-2), X - is an anion selected from the following general formulas (1A) to (1D).

Chem.

[0140] In the general formula (1A), R fa is a fluorine atom or a monovalent hydrocarbon group having 1 to 40 carbon atoms which may contain a hetero atom. The monovalent hydrocarbon group may be linear, branched or cyclic, and specific examples thereof include the same as those described in the description of R 107 described later.

[0141] As the anion represented by the general formula (1A), those represented by the following general formula (1A’) are preferable.

Chem.

[0142] In the general formula (1A’), R 106 is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. R 107 represents a monovalent hydrocarbon group having 1 to 38 carbon atoms which may contain a hetero atom. As the hetero atom, an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, etc. are preferable, and an oxygen atom is more preferable. As the monovalent hydrocarbon group, those having 6 to 30 carbon atoms are particularly preferable from the viewpoint of obtaining high resolution in fine pattern formation.

[0143] The monovalent hydrocarbon group may be linear, branched or cyclic. Specific examples thereof include linear or branched alkyl groups such as 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, undecyl group, tridecyl group, pentadecyl group, heptadecyl group, icosanyl group, etc.; monovalent saturated cyclic aliphatic hydrocarbon groups such as cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-adamantyl group, 1-adamantylmethyl group, norbornyl group, norbornylmethyl group, tricyclodecanyl group, tetracyclododecanyl group, tetracyclododecanylmethyl group, dicyclohexylmethyl group, etc.; monovalent unsaturated aliphatic hydrocarbon groups such as allyl group, 3-cyclohexenyl group, etc.; aryl groups such as phenyl group, 1-naphthyl group, 2-naphthyl group, etc.; aralkyl groups such as benzyl group, diphenylmethyl group, etc. Further, as the monovalent hydrocarbon group containing a heteroatom, tetrahydrofuryl group, methoxymethyl group, ethoxymethyl group, methylthiomethyl group, acetamidomethyl group, trifluoroethyl group, (2-methoxyethoxy)methyl group, acetoxymethyl group, 2-carboxy-1-cyclohexyl group, 2-oxopropyl group, 4-oxo-1-adamantyl group, 3-oxocyclohexyl group, etc. may be mentioned. Further, a part of the hydrogen atoms of these groups may be substituted with a heteroatom-containing group such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, etc., or a part of the carbon atoms of these groups may be substituted with a heteroatom-containing group such as an oxygen atom, a sulfur atom, a nitrogen atom, etc. As a result, it may contain a hydroxy group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate group, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc.

[0144] Regarding the synthesis of sulfonium salts containing anions represented by the above general formula (1A’), it is detailed in JP-A-2007-145797, JP-A-2008-106045, JP-A-2009-7327, JP-A-2009-258695, etc. Further, sulfonium salts described in JP-A-2010-215608, JP-A-2012-41320, JP-A-2012-106986, JP-A-2012-153644, etc. are also preferably used.

[0145] Examples of the anion represented by the above general formula (1A) include, but are not limited to, the following. In the following formula, Ac is an acetyl group.

Chemical formula

[0146]

Chemical formula

[0147]

Chemical formula

[0148]

Chemical formula

[0149] In the above general formula (1B), R fb1 and R fb2 each independently represent a fluorine atom or a monovalent hydrocarbon group having 1 to 40 carbon atoms which may contain a hetero atom. The above monovalent hydrocarbon group may be linear, branched or cyclic, and specific examples thereof include the same ones as those mentioned in the description of the above R 107 . Preferably, R fb1 and R fb2 are a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. Further, R fb1 and R fb2 are bonded to each other and the group to which they are bonded (-CF2 -SO 2 -N - -SO 2 -CF 2 - may form a ring together with), in which case, R fb1 and R fb2 The group obtained by bonding with each other is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0150] In the general formula (1C) above, R fc1 , R fc2 and R fc3 are each independently a fluorine atom or a monovalent hydrocarbon group having 1 to 40 carbon atoms which may contain a hetero atom. The monovalent hydrocarbon group may be linear, branched or cyclic, and specific examples thereof include the same ones as those listed in the description of R 107 above. R fc1 , R fc2 and R fc3 are preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. Further, R fc1 and R fc2 may bond to each other to form a ring together with the group (-CF 2 -SO 2 -C - -SO 2 -CF 2 -) to which they are bonded. In this case, the group obtained by bonding R fc1 and R fc2 to each other is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0151] In the general formula (1D) above, R fd is a monovalent hydrocarbon group having 1 to 40 carbon atoms which may contain a hetero atom. The monovalent hydrocarbon group may be linear, branched or cyclic, and specific examples thereof include the same ones as those listed in the description of R 107 above.

[0152] Regarding the synthesis of sulfonium salts containing the anion represented by the above general formula (1D), details can be found in JP-A-2010-215608 and JP-A-2014-133723.

[0153] Examples of the anion represented by the above general formula (1D) include, but are not limited to, the following.

Chemical formula

[0154] Note that the photoacid generator containing the anion represented by the above general formula (1D) does not have a fluorine atom at the α-position of the sulfonic group, but has two trifluoromethyl groups at the β-position, and thus has sufficient acidity to cleave the acid-labile group in the resist polymer. Therefore, it can be used as a photoacid generator.

[0155] As the photoacid generator, those represented by the following general formula (2) can also be preferably used.

Chemical formula

[0156] In the above general formula (2), R 201 and R 202 are each independently a monovalent hydrocarbon group having 1 to 30 carbon atoms which may contain a hetero atom. R 203 is a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain a hetero atom. Also, any two of R 201 , R 202 and R 203 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. L A is a single bond, an ether bond, or a divalent hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom. X A , X B , X C and X D are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group. However, X A , XB , X C and X D At least one of them is a fluorine atom or a trifluoromethyl group. k is an integer from 0 to 3.

[0157] The monovalent hydrocarbon group may be linear, branched, or cyclic. Specific examples thereof include linear or branched alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, tert-pentyl group, n-hexyl group, n-octyl group, n-nonyl group, n-decyl group, 2-ethylhexyl group; monovalent saturated cyclic hydrocarbon groups such as cyclopentyl group, cyclohexyl group, cyclopentylmethyl group, cyclopentylethyl group, cyclopentylbutyl group, cyclohexylmethyl group, cyclohexylethyl group, cyclohexylbutyl group, norbornyl group, oxanorbornyl group, tricyclo[5.2.1.0 2,6 decanyl group, adamantyl group and other monovalent saturated cyclic hydrocarbon groups; aryl groups such as phenyl group, naphthyl group, anthracenyl group and the like. Further, some of the hydrogen atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atom, sulfur atom, nitrogen atom, halogen atom, etc., and some of the carbon atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atom, sulfur atom, nitrogen atom, etc. As a result, it may contain a hydroxy group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate group, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc.

[0158] The divalent hydrocarbon group may be linear, branched or cyclic. Specific examples thereof include linear or branched alkanediyl groups such as methylene group, ethylene group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group, tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, heptadecane-1,17-diyl group; divalent saturated cyclic hydrocarbon groups such as cyclopentanediyl group, cyclohexanediyl group, norbornanediyl group, adamantanediyl group; divalent unsaturated cyclic hydrocarbon groups such as phenylene group, naphthylene group and the like. Further, a part of the hydrogen atoms of these groups may be substituted with an alkyl group such as methyl group, ethyl group, propyl group, n-butyl group, tert-butyl group, etc., a part of the hydrogen atoms of these groups may be substituted with a heteroatom-containing group such as oxygen atom, sulfur atom, nitrogen atom, halogen atom, etc., or a part of the carbon atoms of these groups may be substituted with a heteroatom-containing group such as oxygen atom, sulfur atom, nitrogen atom, etc., and as a result, it may contain a hydroxy group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate group, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc. As the heteroatom, an oxygen atom is preferable.

[0159] As the photoacid generator represented by the general formula (2) above, those represented by the following general formula (2') are preferable.

Chemical formula

[0160] In the general formula (2') above, L A is the same as above. R HF is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. R 301 、R 302 and R303 is each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, which may contain a hydrogen atom or a hetero atom. The monovalent hydrocarbon group may be linear, branched, or cyclic, and specific examples thereof include those listed in the description of the above R 107 above. x and y are each independently an integer of 0 to 5, and z is an integer of 0 to 4.

[0161] Examples of the photoacid generator represented by the general formula (2) include, but are not limited to, those shown below. In the following formulas, R HF is the same as above, and Me is a methyl group. [Chemical formula]

[0162] [Chemical formula]

[0163] [Chemical formula]

[0164] Among the above photoacid generators, those containing an anion represented by the formula (1A') or (1D) are particularly preferred because they have low acid diffusion and excellent solubility in the resist solvent. In addition, those containing an anion represented by the formula (2') are particularly preferred because they have extremely low acid diffusion.

[0165] When the resist material of the present invention contains an additive photoacid generator, its content is preferably 0.1 to 50 parts by mass, more preferably 1 to 40 parts by mass, based on 100 parts by mass of the base polymer. By including the repeating unit f in the base polymer and / or by including an additive photoacid generator, the resist material of the present invention can function as a chemically amplified resist material.

[0166] [Organic solvent] An organic solvent may be blended in the resist material of the present invention. The organic solvent is not particularly limited as long as it can dissolve the quencher of the sulfonium salt of the carboxylic acid bonded to the maleimide group described above and other components if contained. Examples of such organic solvents include those described in paragraphs

[0144] to

[0145] of JP-A-2008-111103, such as ketones like cyclohexanone, cyclopentanone, and methyl-2-n-pentyl ketone; alcohols like 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol; ethers like 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 like propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol monotert-butyl ether acetate; lactones like γ-butyrolactone; and mixed solvents thereof.

[0167] In the resist material 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.

[0168] [Other components] In addition to the above-described components, a positive resist material and a negative resist material are constituted by appropriately combining and blending a surfactant, a dissolution inhibitor, a crosslinking agent, etc. according to the purpose. In the exposed area, the dissolution rate of the above base polymer with respect to the developer is accelerated by a catalytic reaction, so that a very high-sensitivity positive resist material and negative resist material can be obtained. In this case, the dissolution contrast and resolution of the resist film are high, there is an exposure margin, the process adaptability is excellent, the pattern shape after exposure is good, and in particular, acid diffusion can be suppressed, so the difference in coarse and fine dimensions is small. For these reasons, the practicality is high, and it can be made very effective as a resist material for ultra-LSI.

[0169] Examples of the surfactant include those described in paragraphs

[0165] to

[0166] of JP-A-2008-111103. By adding a surfactant, the coatability of the resist material can be further improved or controlled. The surfactant can be used alone or in combination of two or more. In the resist material of the present invention, the content of the surfactant is preferably 0.0001 to 10 parts by mass with respect to 100 parts by mass of the base polymer.

[0170] In the case of a positive resist material, by blending a dissolution inhibitor, the difference in dissolution rate between the exposed part and the unexposed part can be further increased, and the resolution can be further improved. As the above dissolution inhibitor, a compound having a molecular weight preferably of 100 to 1,000, more preferably 150 to 800, and containing two or more phenolic hydroxy groups in the molecule, and the hydrogen atoms of the phenolic hydroxy groups are substituted as a whole by acid-labile groups at a ratio of 0 to 100 mol%, or a compound having a carboxy group in the molecule, and the hydrogen atoms of the carboxy group are substituted as a whole by acid-labile groups at an average ratio of 50 to 100 mol% can be mentioned. Specifically, bisphenol A, trisphenol, phenolphthalein, cresol novolak, naphthalene carboxylic acid, adamantane carboxylic acid, compounds in which the hydrogen atoms of the hydroxy groups and carboxy groups of cholic acid are substituted with acid-labile groups, etc. can be mentioned. For example, they are described in paragraphs

[0155] to

[0178] of JP-A-2008-122932.

[0171] When the resist material of the present invention is a positive resist material, the content of the above dissolution inhibitor is preferably 0 to 50 parts by mass, more preferably 5 to 40 parts by mass, based on 100 parts by mass of the base polymer. The above dissolution inhibitor can be used alone or in combination of two or more.

[0172] On the other hand, in the case of a negative resist material, by adding a crosslinking agent, a negative pattern can be obtained by reducing the dissolution rate of the exposed part. As the above crosslinking agent, an epoxy compound, a melamine compound, a guanamine compound, a glycoluril compound or a urea compound, an isocyanate compound, an azide compound, a compound containing a double bond such as an alkenyl ether group, which is substituted with at least one group selected from a methylol group, an alkoxymethyl group and an acyloxymethyl group can be mentioned. These may be used as additives, or may be introduced as pendant groups on the polymer side chain. In addition, a compound containing a hydroxy group can also be used as a crosslinking agent. The crosslinking agent can be used alone or in combination of two or more.

[0173] Examples of the epoxy compound include tris(2,3-epoxypropyl)isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, and triethanol ethane triglycidyl ether.

[0174] Examples of the melamine compound include hexamethylol melamine, hexamethoxymethyl melamine, a compound or mixture thereof in which 1 to 6 methylol groups of hexamethylol melamine are methoxymethylated, hexamethoxyethyl melamine, hexaacyloxymethyl melamine, and a compound or mixture thereof in which 1 to 6 methylol groups of hexamethylol melamine are acyloxymethylated.

[0175] Examples of the guanamine compound include tetramethylol guanamine, tetramethoxymethyl guanamine, a compound or mixture thereof in which 1 to 4 methylol groups of tetramethylol guanamine are methoxymethylated, tetramethoxyethyl guanamine, tetraacyloxy guanamine, and a compound or mixture thereof in which 1 to 4 methylol groups of tetramethylol guanamine are acyloxymethylated.

[0176] Examples of the glycoluril compound include tetramethylol glycoluril, tetramethoxy glycoluril, tetramethoxymethyl glycoluril, a compound or mixture thereof in which 1 to 4 methylol groups of tetramethylol glycoluril are methoxymethylated, and a compound or mixture thereof in which 1 to 4 methylol groups of tetramethylol glycoluril are acyloxymethylated.

[0177] Examples of the urea compound include tetramethylol urea, tetramethoxymethyl urea, a compound or mixture thereof in which 1 to 4 methylol groups of tetramethylol urea are methoxymethylated, and tetramethoxyethyl urea.

[0178] Examples of the isocyanate compound include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, and the like.

[0179] Examples of the azide compound include 1,1'-biphenyl-4,4'-bisazide, 4,4'-methylidenebisazide, 4,4'-oxybisazide, and the like.

[0180] Examples of the compound containing an alkenyl ether 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 the like.

[0181] When the resist material of the present invention is a negative resist material, the content of the crosslinking agent is preferably 0.1 to 50 parts by mass, more preferably 1 to 40 parts by mass, based on 100 parts by mass of the base polymer.

[0182] In the resist material of the present invention, a quencher other than the sulfonium salt of the carboxylic acid bonded to the maleimide group described above (hereinafter referred to as other quenchers) may be blended. Examples of other quenchers include conventional basic compounds. Examples of conventional basic compounds include primary, secondary, and tertiary aliphatic amines, hybrid 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, carbamates, and the like. In particular, the primary, secondary, and tertiary amine compounds described in paragraphs

[0146] to

[0164] of JP-A-2008-111103, particularly amine compounds having a hydroxy group, an ether bond, an ester bond, a lactone ring, a cyano group, a sulfonic acid ester bond, or compounds having a carbamate group described in Japanese Patent No. 3790649 are preferable. By adding such a basic compound, for example, the diffusion rate of acid in the resist film can be further suppressed, or the shape can be corrected.

[0183] Further, examples of other quenchers include onium salts such as sulfonium salts, iodonium salts, and ammonium salts of sulfonic acids and carboxylic acids in which the α-position is not fluorinated, as described in JP-A-2008-158339. Sulfonic acids, imidic acids, or methidic acids in which the α-position is fluorinated are necessary for deprotecting the acid-labile group of the carboxylic acid ester, but sulfonic acids or carboxylic acids in which the α-position is not fluorinated are released by salt exchange with onium salts in which the α-position is not fluorinated. Since sulfonic acids and carboxylic acids in which the α-position is not fluorinated do not cause a deprotection reaction, they function as quenchers.

[0184] As other quencher, a polymer type quencher described in JP-A-2008-239918 can be further mentioned. This enhances the rectangularity of the resist after patterning by orienting on the resist surface after coating. The polymer type quencher also has an effect of preventing film loss of the pattern and rounding of the pattern top when a protective film for immersion exposure is applied.

[0185] In the resist material of the present invention, the content of other quencher is preferably 0 to 5 parts by mass, more preferably 0 to 4 parts by mass with respect to 100 parts by mass of the base polymer. The quencher can be used alone or in combination of two or more.

[0186] The resist material of the present invention may be blended with a water repellency improver for improving the water repellency of the resist surface after spin coating. The above water repellency improver can be used for immersion lithography without using a top coat.

[0187] As the above water repellency improver, a polymer compound containing an alkyl fluoride group, a polymer compound containing a 1,1,1,3,3,3-hexafluoro-2-propanol residue having a specific structure, etc. are preferable, and those exemplified in JP-A-2007-297590, JP-A-2008-111103, etc. are more preferable. The above water repellency improver needs to be dissolved in an alkaline developer or an organic solvent developer. The water repellency improver having the above-described specific 1,1,1,3,3,3-hexafluoro-2-propanol residue has good solubility in the developer. As the water repellency improver, a polymer compound containing a repeating unit containing an amino group or an amine salt has a high effect of preventing evaporation of the acid in the post-exposure bake (PEB) and preventing opening defects of the hole pattern after development. The water repellency improver can be used alone or in combination of two or more.

[0188] In the resist material of the present invention, the content of the water repellency improver is preferably 0 to 20 parts by mass, more preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the base polymer.

[0189] Acetylenic alcohols can also be blended into the resist material of the present invention. Examples of the acetylenic alcohols include those described in paragraphs

[0179] to

[0182] of JP-A-2008-122932. In the resist material of the present invention, the content of the acetylenic alcohols is preferably 0 to 5 parts by mass with respect to 100 parts by mass of the base polymer.

[0190] [Positive resist material and negative resist material] When the resist material of the present invention contains an acid-labile group, it is a chemically amplified positive resist material, and when it does not contain an acid-labile group, it is a chemically amplified negative resist material.

[0191] [Pattern formation method] When the resist material of the present invention is used for manufacturing various integrated circuits, known lithography techniques can be applied.

[0192] Specifically, a pattern formation method can be used that includes (1) a step of forming a resist film on a substrate using the above-described resist material, (2) a step of exposing the resist film with high-energy rays, and (3) a step of developing the exposed resist film using a developer.

[0193] For example, the resist material of the present invention is applied onto a substrate for manufacturing an integrated circuit (Si, SiO 2 , SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflection film, etc.) or a substrate for manufacturing a mask circuit (Cr, CrO, CrON, MoSi 2 , SiO 2 , etc.) by an appropriate coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, doctor coating, etc. so that the coating film thickness becomes 0.01 to 2 μm. This is 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.

[0194] After the above step (1) and before the above step (2), (1’) it is also possible to expose the entire resist film to light with a wavelength at which the sulfonium salt of the carboxylic acid bonded to the maleimide group does not decompose. By this, the maleimide group couples or polymerizes, increasing the molecular weight of the quencher and exhibiting characteristics of lower acid diffusion. At this time, it is preferable that the cation moiety of the sulfonium salt described in the general formula (1) does not decompose. The wavelength at which the sulfonium salt cation does not decompose is light with a wavelength longer than 300 nm, more preferably the i-line (365 nm), h-line (405 nm), g-line (436 nm) of a mercury lamp with a wavelength longer than 350 nm, or light irradiated from a xenon lamp or LED that cuts wavelengths of 300 nm or less. The irradiation energy is in the range of 1 mJ / cm 2 ~1 J / cm 2 .

[0195] Next, the resist film is exposed using high-energy rays. Examples of the high-energy rays include ultraviolet rays, far ultraviolet rays, EB, extreme ultraviolet rays (EUV) with a wavelength of 3 to 15 nm, X-rays, soft X-rays, excimer laser light, γ-rays, synchrotron radiation, etc. When using ultraviolet rays, far ultraviolet rays, EUV, X-rays, soft X-rays, excimer laser light, γ-rays, synchrotron radiation, etc. as the high-energy rays, a mask for forming the target pattern is used, and the exposure amount is preferably about 1 to 200 mJ / cm 2 , more preferably about 10 to 100 mJ / cm 2 . When using EB as the high-energy ray, the exposure amount is preferably about 0.1 to 300 μC / cm 2 , more preferably about 0.5 to 200 μC / cm 2 , and a mask for forming the target pattern is used or direct drawing is performed. The resist material of the present invention is particularly suitable for fine patterning by KrF excimer laser light, ArF excimer laser light, EB, EUV, X-rays, soft X-rays, γ-rays, synchrotron radiation among high-energy rays, and is particularly suitable for fine patterning by KrF excimer laser light, ArF excimer laser light, EB or EUV with a wavelength of 3 to 15 nm.

[0196] 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.

[0197] After exposure or after PEB, in the case of a positive resist material, an alkaline aqueous solution developer such as 0.1 to 10% by mass, preferably 2 to 5% by mass of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetrabutylammonium hydroxide (TBAH), etc. is used, and development is carried out by an ordinary method such as dip method, puddle method, spray method, etc. for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes. The irradiated part is dissolved in the developer, and the unexposed part is not dissolved, and the target positive pattern is formed on the substrate. In the case of a negative resist material, it is the opposite of the case of a positive resist material, that is, the irradiated part is insolubilized in the developer, and the unexposed part is dissolved.

[0198] Using a positive resist material containing a base polymer having an acid-labile group, a negative pattern can also be obtained by organic solvent development. As the developer used at this time, 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, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonate, 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. can be mentioned. These organic solvents can be used alone or in combination of two or more.

[0199] At the end of development, rinsing is performed. As the rinse liquid, a solvent that is miscible with the developer and does not dissolve the resist film is preferred. As such a solvent, 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 are preferably used.

[0200] Specifically, examples of the alcohol 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, 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.

[0201] 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, di-n-hexyl ether, and the like.

[0202] Examples of the alkane having 6 to 12 carbon atoms include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, cyclononane, and the like. Examples of the alkene having 6 to 12 carbon atoms include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, cyclooctene, and the like. Examples of the alkyne having 6 to 12 carbon atoms include hexyne, heptyne, octyne, and the like.

[0203] Examples of aromatic solvents include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, mesitylene, and the like.

[0204] By performing rinsing, it is possible to reduce the occurrence of resist pattern collapse and defects. Also, rinsing is not necessarily essential, and the amount of solvent used can be reduced by not performing rinsing.

[0205] The developed hole pattern or trench pattern can also be shrunk using thermal flow, RELACS technology, or DSA technology. A shrinking agent is applied onto the hole pattern, and cross-linking of the shrinking agent occurs on the surface of the resist due to the diffusion of the acid catalyst from the resist layer during baking, and the shrinking agent adheres to the sidewalls of the hole pattern. The baking temperature is preferably 70 to 180°C, more preferably 80 to 170°C, and the time is preferably 10 to 300 seconds, to remove the excess shrinking agent and shrink the hole pattern.

Examples

[0206] Hereinafter, the present invention will be specifically described by showing synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples.

[0207] The structures of quenchers 1 to 21 and comparative quencher 1 used in the resist material are shown below.

[0208]

Chemical formula

[0209]

Chemical formula

[0210]

Chemical formula

[0211] [Chemical formula]

[0212] [Synthesis Example] Synthesis of Base Polymers (Polymers 1 to 5) Combined with each monomer, a copolymerization reaction was carried out in THF as a solvent, crystallized in methanol, and further washed repeatedly with hexane, and then isolated and dried to obtain base polymers (Polymers 1 to 5) having the following compositions. The compositions of the obtained base polymers were 1 Confirmed by 1H-NMR, and Mw and Mw / Mn were confirmed by GPC (solvent: THF, standard: polystyrene).

[0213] [Chemical formula]

[0214] [Examples 1 to 27, Comparative Examples 1, 2] Solutions in which each component was dissolved in the compositions shown in Tables 1 and 2 were filtered through a 0.2-μm size filter to prepare resist materials. The resist materials of Examples 1 to 26 and Comparative Example 1 were positive type, and the resist materials of Example 27 and Comparative Example 2 were negative type.

[0215] In Tables 1 and 2, each component is as follows. · Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) DAA (diacetone alcohol) EL (ethyl lactate)

[0216] · Acid generator: PAG1 to 5 (see the following structural formula) and blend quencher 1, 2 (see the following structural formula) [Chemical formula]

[0217] [EUV Exposure Evaluation] Each resist material shown in Tables 1 and 2 was spin-coated on a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content: 43 mass%) manufactured by Shin-Etsu Chemical Co., Ltd. was formed to a film thickness of 20 nm, and pre-baked at 100 °C for 60 seconds using a hot plate to produce a resist film with a film thickness of 50 nm. This Si substrate was exposed over the entire surface with an exposure dose of 200 mJ / cm 2 using i-line. Next, exposure was performed using an EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadrupole illumination, mask with a hole pattern having a pitch of 44 nm and a +20% bias in wafer dimensions) manufactured by ASML, and PEB was performed for 60 seconds at the temperatures described in Tables 1 and 2 on a hot plate, followed by development for 30 seconds with a 2.38 mass% TMAH aqueous solution, to obtain a hole pattern with a dimension of 22 nm in Examples 1 to 26 and Comparative Example 1, and a dot pattern with a dimension of 22 nm in Example 27 and Comparative Example 2.

[0218] Using a length-measuring SEM (CG6300) manufactured by Hitachi High-Technologies Corporation, the exposure dose when holes or dots with a dimension of 22 nm were formed was measured and taken as the sensitivity. Also, the dimensions of 50 holes or dots at this time were measured to obtain the dimension variation (CDU, 3σ). The results are shown together in Tables 1 and 2.

[0219]

Table 1

[0220]

Table 2

[0221] From the results shown in Tables 1 and 2, it was found that the resist material of the present invention containing the sulfonium salt of the carboxylic acid that binds to the maleimide group has high sensitivity and a small CDU. On the other hand, in Comparative Example 1 and Comparative Example 2 that do not contain the sulfonium salt of the carboxylic acid that binds to the maleimide group as a quencher, it was found that the sensitivity was low and the CDU was also large. Therefore, it has become clear that the resist material of the present invention containing the sulfonium salt of the carboxylic acid that binds to the maleimide group can be suitably used as a resist material.

[0222] Note that the present invention is not limited to the above-described embodiments. The above-described embodiments are examples, and any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits the same operational effects is included in the technical scope of the present invention.

Claims

1. A resist material containing a quencher, the quencher comprising a sulfonium salt of a carboxylic acid that bonds to a maleimide group.

2. 2. The resist material according to claim 1, wherein the sulfonium salt of a carboxylic acid bonded to the maleimide group is represented by the following general formula (1): 【Chemistry 1】 (In the formula, R １ , R ２ is a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms; R １ and R ２ may be bonded to form a ring. X is a single bond or a divalent linking group having 1 to 20 carbon atoms, and may have an ether group, a carbonyl group, an ester group, an amide group, a sultone group, a lactam group, a carbonate group, a halogen atom, a hydroxyl group, or a carboxyl group. ３ ~R ５ are each independently a monovalent hydrocarbon group having 1 to 25 carbon atoms which may contain a heteroatom. ３ , R ４ and R ５ Any two of may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

3. 2. The resist material according to claim 1, further comprising at least one selected from the group consisting of an acid generator that generates an acid, an organic solvent, and a surfactant.

4. The resist material according to claim 2, further comprising one or more selected from the group consisting of an acid generator that generates an acid, an organic solvent, and a surfactant.

5. The resist material described in claim 3, characterized in that the acid generator generates a sulfonic acid, an imide acid or a methide acid.

6. The resist material according to claim 4, characterized in that the acid generator generates a sulfonic acid, an imide acid or a methide acid.

7. The resist material of claim 1, further comprising a base polymer.

8. The resist material of claim 2, further comprising a base polymer.

9. The resist material described in Claim 7, characterized in that the base polymer further contains at least one type selected from the repeating units represented by the following general formulas (f1) to (f3): 【Chemistry 2】 (In the formula, R A is each independently a hydrogen atom or a methyl group. Z 1 is a single bond, a phenylene group, a naphthylene group, -Z 11 -, -O-Z 11 -, -C(═O)-O-Z 11 - or -C(═O)-NH-Z 11 -. Z 11 is a hydrocarbon group having 1 to 20 carbon atoms which may contain an alkanediyl group having 1 to 6 carbon atoms, an alkenediyl group having 2 to 6 carbon atoms or a phenylene group, and which may contain a carbonyl group, an ester bond, an ether bond or a hydroxy group. Z 2A is a single bond or an ester bond. Z 2B is a single bond or a divalent group having 1 to 18 carbon atoms which may contain an ester bond, an ether bond, a lactone ring, a bromine atom or an iodine atom. Z 3 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -Z 31 -, -O-Z 31 -, -C(═O)-O-Z 31 - or -C(═O)-NH-Z 31 -, Z 31 is a group containing an alkanediyl group having 1 to 15 carbon atoms, an alkenediyl group having 2 to 15 carbon atoms or a phenylene group, and may contain a carbonyl group, an ester bond, an ether bond, a halogen atom or a hydroxyl group. Rf 1 to Rf 4 are each independently a hydrogen atom, a fluorine atom, an oxygen atom or a trifluoromethyl group, but at least one is a fluorine atom, and when Rf 1 and Rf 2 are oxygen atoms, Rf 1 and Rf 2 are one oxygen atom that bonds to one carbon atom to form a carbonyl group. R 21 to R 28 are each independently a monovalent hydrocarbon group having 1 to 25 carbon atoms which may contain a heteroatom. Any two of R 23 , R 24 and R 25 or any two of R 26 , R 27 and R 28 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. M − is a non-nucleophilic counter ion.

10. The resist material described in Claim 8, characterized in that the base polymer further contains at least one type selected from the repeating units represented by the following general formulas (f1) to (f3): 【Chemistry 3】 (In the formula, R A is each independently a hydrogen atom or a methyl group. Z 1 is a single bond, a phenylene group, a naphthylene group, -Z 11 -, -O-Z 11 -, -C(═O)-O-Z 11 - or -C(═O)-NH-Z 11 -. Z 11 is a hydrocarbon group having 1 to 20 carbon atoms which may contain an alkanediyl group having 1 to 6 carbon atoms, an alkenediyl group having 2 to 6 carbon atoms or a phenylene group, and which may contain a carbonyl group, an ester bond, an ether bond or a hydroxy group. Z 2A is a single bond or an ester bond. Z 2B is a single bond or a divalent group having 1 to 18 carbon atoms which may contain an ester bond, an ether bond, a lactone ring, a bromine atom or an iodine atom. Z 3 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -Z 31 -, -O-Z 31 -, -C(═O)-O-Z 31 - or -C(═O)-NH-Z 31 -, Z 31 is a group containing an alkanediyl group having 1 to 15 carbon atoms, an alkenediyl group having 2 to 15 carbon atoms or a phenylene group, and may contain a carbonyl group, an ester bond, an ether bond, a halogen atom or a hydroxyl group. Rf 1 to Rf 4 are each independently a hydrogen atom, a fluorine atom, an oxygen atom or a trifluoromethyl group, but at least one is a fluorine atom, and when Rf 1 and Rf 2 are oxygen atoms, Rf 1 and Rf 2 are one oxygen atom that bonds to one carbon atom to form a carbonyl group. R 21 to R 28 are each independently a monovalent hydrocarbon group having 1 to 25 carbon atoms which may contain a heteroatom. Any two of R 23 , R 24 and R 25 or any two of R 26 , R 27 and R 28 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. M − is a non-nucleophilic counter ion.

11. The resist material described in Claim 7, characterized in that the base polymer contains a repeating unit represented by the following general formula (a1) or a repeating unit represented by the following formula (a2) as a repeating unit having an acid labile group: 【Chemistry 4】 (In the formula, R A is each independently a hydrogen atom or a methyl group. R 11 and R 12 are acid labile groups. Y 1 is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms containing at least one selected from an ester bond and a lactone ring. Y 2 is a single bond, an ester bond, or an amide bond. Y 3 is a single bond, an ether bond, or an ester bond. R 13 is a fluorine atom, a trifluoromethyl group, a cyano group, or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R 14 is a single bond or an alkanediyl group having 1 to 6 carbon atoms, some of whose carbon atoms may be substituted with an ether bond or an ester bond. a is 1 or 2. b is an integer of 0 to 4, with the proviso that 1≦a+b≦5.)

12. The resist material described in Claim 9, characterized in that the base polymer contains a repeating unit represented by the following general formula (a1) or a repeating unit represented by the following formula (a2) as a repeating unit having an acid labile group: 【Chemistry 5】 (In the formula, R A is each independently a hydrogen atom or a methyl group. R 11 and R 12 are acid labile groups. Y 1 is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms containing at least one selected from an ester bond and a lactone ring. Y 2 is a single bond, an ester bond, or an amide bond. Y 3 is a single bond, an ether bond, or an ester bond. R 13 is a fluorine atom, a trifluoromethyl group, a cyano group, or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R 14 is a single bond or an alkanediyl group having 1 to 6 carbon atoms, some of whose carbon atoms may be substituted with an ether bond or an ester bond. a is 1 or 2. b is an integer of 0 to 4, with the proviso that 1≦a+b≦5.) 13. The resist material of claim 11, which is a chemically amplified positive resist material.

14. The resist material of claim 7, wherein the base polymer does not contain an acid labile group.

15. The resist material of claim 9, wherein the base polymer does not contain an acid labile group.

16. The resist material of claim 14, which is a chemically amplified negative resist material.

17. A pattern forming method comprising the steps of: (1) forming a resist film on a substrate using a resist material described in any one of claims 1 to 16; (2) exposing the resist film to high-energy rays; and (3) developing the exposed resist film using a developer.

18. The pattern formation method described in Claim 17, characterized in that after step (1) and before step (2), (1') the entire surface of the resist film is exposed to light of a wavelength that does not decompose the sulfonium salt of the carboxylic acid bonded to the maleimide group.

19. The pattern formation method according to claim 18, wherein the wavelength at which the sulfonium salt does not decompose is longer than 300 nm.

20. The pattern formation method according to claim 17, wherein the high-energy beam is KrF excimer laser beam, ArF excimer laser beam, electron beam or extreme ultraviolet ray having a wavelength of 3 to 15 nm.

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