Resist composition and pattern forming method

Abstract

To provide a resist composition containing a photosensitive compound having an iodonium cation good in sensitivity, excellent in resolution, small in edge roughness and dimensional variation, and further good in storage stability also, and a method of forming a pattern.SOLUTION: A resist composition includes an acid compound (I) represented by the following formula (A), a specific iodonium salt-type photoacid generator (II) and / or a specific iodonium salt-type photodegradable quencher (III), and a base polymer (IV) whose dissolution rate to a developer changes by action of an acid, or an acid compound (I) represented by the following formula (A), and a base polymer (IV') including a specific iodonium salt-type acid-generating unit whose dissolution rate to a developer changes by action of an acid. In the formula, R1 is a 1-20C hydrocarbyl group which may have a fluorine atom, a hydroxyl group, or a hetero atom, and Rf1 and Rf2 are each independently a fluorine atom, or a trifluoromethyl group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resist composition 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] In lithography using DUV light sources, i.e., KrF excimer lasers or ArF excimer lasers, chemically amplified resist compositions, which change the solubility in the developer by causing a reaction of the base polymer using the acid generated from a photosensitive compound (photoacid generator) upon exposure as a catalyst, have enabled high-sensitivity, high-resolution lithography and driven miniaturization as the main resist composition used in actual production processes.

[0004] Chemically amplified resist compositions continue to be widely studied for next-generation lithography, such as EUV, and have been commercialized. Meanwhile, demands for improved resist performance are increasing as miniaturization advances. In particular, resist pattern dimensional variations (e.g., line width roughness (LWR)) affect pattern dimensional variations after substrate processing, which ultimately can affect device operational stability, and therefore must be minimized. Resist compositions are also required to have good storage stability.

[0005] Recently used EUV light sources have low output but high energy due to their short wavelength, resulting in a very small number of photons during exposure. As a result, the amount of photoacid generator that is exposed to EUV light is smaller than that during DUV exposure, resulting in uneven acid distribution within the resist film. This photon shot noise is known to cause a deterioration in LWR performance (Non-Patent Document 1).

[0006] To overcome the shot noise problem, it is effective to increase the acid generation efficiency of the photoacid generator and enhance the sensitivity of the resist. Iodonium salt-type photoacid generators, which consist of an iodonium cation and a counter anion, are known as materials with high acid generation efficiency because they have high EUV light absorption efficiency and also high electron acceptance (Non-Patent Document 2).

[0007] Although iodonium salt-type photoacid generators have the above advantages, they suffer from the problem of poor storage stability. For example, Patent Documents 1 and 2 attempt to improve the storage stability by modifying the molecular structure of the iodonium salt. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2019 / 130866 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-175893 [Non-patent literature]

[0009] [Non-Patent Document 1] SPIE Vol. 3331 p531 (1998) [Non-patent document 2] SPIE Vol. 9779 97790A (2016) Summary of the Invention [Problem to be solved by the invention]

[0010] There is a need for the development of chemically amplified resist compositions for EUV lithography that have good sensitivity and excellent LWR performance. Photosensitive compounds containing iodonium cations have high sensitivity but suffer from poor storage stability. Methods of improving stability by modifying the molecular structure, as described in Patent Documents 1 and 2, impose restrictions on molecular design and raise concerns about reduced electron-accepting ability and solvent solubility.

[0011] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resist composition containing a photosensitive compound having an iodonium cation, which has good sensitivity, little edge roughness and dimensional variation, excellent resolution, and good storage stability, and a pattern forming method thereof. [Means for solving the problem]

[0012] As a result of extensive investigations aimed at solving the above-mentioned problems, the present inventors discovered that the problems of sensitivity and storage stability can be overcome by adding an acid compound having a specific structure to a resist composition containing a photosensitive compound having an iodonium cation structure, and thus completed the present invention.

[0013] That is, the present invention provides the following resist composition and pattern forming method. 1. A resist composition comprising: (I) an acid compound represented by the following formula (A), (II) a photoacid generator represented by the following formula (1) and / or (III) a photodegradable quencher represented by the following formula (2), and (IV) a base polymer whose dissolution rate in a developer changes upon the action of an acid. [ka] (In the formula, R 1 Rf is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a fluorine atom, a hydroxy group, or a heteroatom. 1 and Rf 2 are each independently a fluorine atom or a trifluoromethyl group. [ka] (In the formula, Ar 1 and Ar 2 are each independently an aryl group having 6 to 18 carbon atoms which may contain a heteroatom. n- is the anion of a strong acid with a valence of n, where n is an integer of 1 or greater. [ka] (In the formula, Ar 3 and Ar 4 are each independently an aryl group having 6 to 18 carbon atoms which may contain a heteroatom. m- is the anion of a weak acid with a valence of m, where m is an integer equal to or greater than 1. 2. A resist composition comprising (I) an acid compound represented by the following formula (A), and (IV') a base polymer containing a repeating unit represented by the following formula (b1), and whose dissolution rate in a developer changes under the action of an acid: [ka] (In the formula, R 1 Rf is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a fluorine atom, a hydroxy group, or a heteroatom. 1 and Rf 2 are each independently a fluorine atom or a trifluoromethyl group. [ka] (In the formula, R A is a hydrogen atom or a methyl group. Y 1 is a single bond or an ester bond. Y 2 is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms, and the hydrocarbylene group may contain at least one bond selected from an ester bond, an ether bond, a lactone ring, an amide bond, a sultone ring, and an iodine atom. Y 3 is a single bond, an ether bond or an ester bond. Rf 11 ~Rf 14 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, provided that at least one is a fluorine atom or a trifluoromethyl group. Ar 5 and Ar 6 are each independently an aryl group having 6 to 18 carbon atoms which may contain a heteroatom. 3. The resist composition of 2, further comprising (III) a photodecomposable quencher represented by the following formula (2): [ka] (In the formula, Ar 3 and Ar 4 are each independently an aryl group having 6 to 18 carbon atoms which may contain a heteroatom. m- is the anion of a weak acid with a valence of m, where m is an integer equal to or greater than 1. 4. The resist composition of any one of 1 to 3, wherein the acid compound represented by formula (A) is represented by any one of the following formulae (A-1) to (A-3): [ka] (In the formula, R 1A R is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom. 2 and R 3 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms. 2 and R 3 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. L is a single bond, an ether bond, or an ester bond. 5. The resist composition of any one of 1 to 4, wherein the base polymer contains a repeating unit represented by the following formula (a): [ka] (In the formula, R A is a hydrogen atom or a methyl group. X 1is a single bond, an ester bond or an amide bond, or a divalent linking group having 1 to 12 carbon atoms and containing at least one bond selected from a phenylene group, a naphthylene group, an ester bond, an ether bond, a lactone ring and an amide bond. R 11 is a hydrogen atom, a fluorine atom, or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and R 11 and X 1 may be bonded to each other to form a ring together with the carbon atoms on the aromatic ring to which they are attached. p is 1 or 2, q is an integer of 0 to 4, and 1≦p+q≦5. r is 0 or 1. 6. The resist composition of 1, wherein the base polymer contains a repeating unit having a structural moiety that decomposes upon irradiation with actinic rays or radiation to generate an acid. 7. The resist composition of 6, wherein the repeating unit having a structural moiety that decomposes upon irradiation with actinic rays or radiation to generate an acid is represented by the following formula (b2): [ka] (In the formula, R A is a hydrogen atom or a methyl group. Y 1 is a single bond or an ester bond. Y 2 is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms, and the hydrocarbylene group may contain at least one bond selected from an ester bond, an ether bond, a lactone ring, an amide bond, a sultone ring, and an iodine atom. Y 3 is a single bond, an ether bond or an ester bond. Rf 11 ~Rf 14 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, provided that at least one is a fluorine atom or a trifluoromethyl group. R 21 ~R 23 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, and R 21 and R22 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. 8. The resist composition according to any one of claims 1 to 7, wherein the base polymer contains a repeating unit c in which the hydrogen atom of the carboxy group is substituted with an acid labile group. 9. The resist composition of 8, wherein the repeating unit c is represented by the following formula (c): [ka] (In the formula, R A is a hydrogen atom or a methyl group. Z 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 AL is an acid labile group. 10. The resist composition of any one of 1 to 7, wherein the base polymer does not contain any repeating unit substituted with an acid labile group. 11. The resist composition of 10 further comprising a crosslinking agent. 12. A pattern forming method comprising: (i) forming a resist film on a substrate using a resist composition according to any one of 1 to 11; (ii) exposing the resist film to high-energy rays; and (iii) developing the exposed resist film using a developer. [Effects of the Invention]

[0014] The resist composition of the present invention, which contains an iodonium salt-type photosensitive compound and a specific acid compound, exhibits high sensitivity, small edge roughness and dimensional variation, excellent resolution, and good storage stability because the acid compound inhibits decomposition of the iodonium salt-type photosensitive compound. These excellent properties make the resist composition highly practical, and it is particularly useful as a material for forming fine patterns on photomasks used in VLSI manufacturing or electron beam (EB) writing, and as a pattern-forming material for EB or EUV lithography. The resist composition of the present invention can be used, for example, not only in lithography for semiconductor circuit formation, but also in the formation of mask circuit patterns, micromachines, and thin-film magnetic head circuits. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a graph showing the change in sensitivity over time when the storage period is extended in Example 2-2 and Comparative Example 2-4. DETAILED DESCRIPTION OF THE INVENTION

[0016] [Resist composition] The resist composition of the present invention comprises (I) a specific acid compound, (II) a specific iodonium salt-type photoacid generator and / or (III) a specific iodonium salt-type photodegradable quencher, and (IV) a base polymer whose dissolution rate in a developer solution changes upon the action of acid; or (I) a specific acid compound and (IV') a base polymer containing a specific iodonium salt-type acid-generating unit and whose dissolution rate in a developer solution changes upon the action of acid. As mentioned above, iodonium salts are unstable compounds that gradually decompose during storage in a resist solution, resulting in fluctuations in resist sensitivity and deterioration of lithography performance. One possible mechanism for the decomposition of iodonium salts during storage is the reaction between nucleophilic components contained in the resist solution and iodonium cations. Nucleophilic components include hydroxide ions, carboxylate ions, amines, etc., and include polymers, quenchers, solvents, and other components essential to resist compositions.

[0017] Iodonium salts have high absorption efficiency for EUV light and high electron-accepting ability, which allows them to increase the sensitivity of resists. However, due to the aforementioned instability of iodonium salts, the systems that can be stably handled are very limited.

[0018] After investigating various additives to inhibit the decomposition of iodonium salts, we found that adding a specific acid compound was effective. The specific acid compound in this invention is a Brønsted acid, which dissociates in the resist solution and releases a proton. It is believed that the addition of an acid donates a proton to the nucleophilic component, weakening its nucleophilicity and thereby inhibiting the decomposition of iodonium salts. Further investigation revealed that fluorocarboxylic acids, which have a fluorine atom or a trifluoromethyl group at the α-position of the carboxyl group, are the optimal additives for improving storage stability. While strong acids such as sulfonic acid and fluorosulfonic acid are effective in inhibiting the decomposition of iodonium salts, they are thought to promote reactions with resins whose dissolution rate changes due to the action of the acid. Therefore, weak acids, such as carboxylic acids without fluorine atoms, are insufficient to inhibit the decomposition of iodonium salts.

[0019] The acid compound is preferably a carboxylic acid having a fluorine atom or a trifluoromethyl group at the α-position, since stronger acids would cause denaturation of the base polymer, while carboxylic acids without fluorine atoms are insufficient in inhibiting the decomposition of the iodonium salt.

[0020] [(I) acid compound] The acid compound of component (I) is represented by the following formula (A). [ka]

[0021] In formula (A), R 1 Rf is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a fluorine atom, a hydroxy group, or a heteroatom. 1 and Rf 2are each independently a fluorine atom or a trifluoromethyl group. 1 The hydrocarbyl group having 1 to 20 carbon atoms and represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Some or all of the hydrogen atoms in the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- groups in the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, so that the hydrocarbyl group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a mercapto 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, or the like.

[0022] The acid compound is preferably one represented by any one of the following formulas (A-1) to (A-3). [ka]

[0023] In formula (A-3), R 1Ais a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom. The hydrocarbyl group having 1 to 20 carbon atoms 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 ethynyl groups. alkynyl groups having 2 to 20 carbon atoms such as a propynyl group or a butynyl group; cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 20 carbon atoms such as a cyclohexenyl group or a norbornenyl group; aryl groups having 6 to 20 carbon atoms such as a phenyl group, a methylphenyl group, an ethylphenyl group, an n-propylphenyl group, an isopropylphenyl group, an n-butylphenyl group, an isobutylphenyl group, a sec-butylphenyl group, a tert-butylphenyl group, a naphthyl group, a methylnaphthyl group, an ethylnaphthyl group, an n-propylnaphthyl group, an isopropylnaphthyl group, an n-butylnaphthyl group, an isobutylnaphthyl group, a sec-butylnaphthyl group or a tert-butylnaphthyl group; aralkyl groups having 7 to 20 carbon atoms such as a benzyl group or a phenethyl group; and groups obtained by combining these.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 mercapto 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, or the like.

[0024] In formula (A-3), R 2 and R 3 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms. The hydrocarbyl group having 1 to 20 carbon atoms may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 1A Examples of the hydrocarbyl group having 1 to 20 carbon atoms and represented by the formula (I) include the same as those exemplified above. 2 and R 3 However, they may be bonded to each other to form a ring together with the carbon atom to which they are bonded, and the ring formed in this case is preferably an alicyclic ring having 3 to 12 carbon atoms.

[0025] In formula (A-3), L is a single bond, an ether bond, or an ester bond.

[0026] Examples of the acid compound include, but are not limited to, the following: [ka]

[0027] [ka]

[0028] In the resist composition of the present invention, the content of the acid compound of component (I) is preferably 0.1 to 20 parts by mass, and more preferably 0.5 to 10 parts by mass, per 80 parts by mass of the base polymer of component (IV), which will be described later. The acid compound of component (I) may be used alone, or two or more different compounds may be used in combination.

[0029] [(II) Photoacid generator] The photoacid generator (II), component (II), decomposes upon exposure to generate a strong acid component, which acts on the base polymer (IV), described below, changing the dissolution rate of the resist film in the developer. The photoacid generator (II), component (II), is an iodonium salt consisting of an anion of a strong acid, such as fluorosulfonic acid or methide acid, and an iodonium cation. Iodonium salt-type photoacid generators have high EUV light absorption efficiency and high electron-accepting properties, resulting in high acid generation efficiency.

[0030] The photoacid generator is represented by the following formula (1). [ka]

[0031] In formula (1), Ar 1 and Ar 2are each independently an aryl group having 6 to 18 carbon atoms which may contain a heteroatom. Examples of the aryl group include a phenyl group, a methylphenyl group, an ethylphenyl group, an n-propylphenyl group, an isopropylphenyl group, an n-butylphenyl group, an isobutylphenyl group, a sec-butylphenyl group, a tert-butylphenyl group, a cyclohexylphenyl group, a naphthyl group, a methylnaphthyl group, an ethylnaphthyl group, an n-propylnaphthyl group, an isopropylnaphthyl group, an n-butylnaphthyl group, an isobutylnaphthyl group, a sec-butylnaphthyl group, a tert-butylnaphthyl group, and a cyclohexylnaphthyl group. Furthermore, some or all of the hydrogen atoms of the aryl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- groups of the aryl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in the aryl group containing a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano 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, or the like.

[0032] Examples of the cation of the photoacid generator include, but are not limited to, the following. [ka]

[0033] In formula (1), Xa n- is an anion of a strong acid having a valence of n, where n is an integer of 1 or greater. n is preferably an integer of 1 to 3, more preferably 1 or 2, and even more preferably 1.

[0034] The anion of the strong acid is preferably one represented by any one of the following formulas (1a) to (1d). [ka]

[0035] In formula (1a), R fa is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in formula (1a') described below. 111 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0036] The anion represented by formula (1a) is preferably one represented by the following formula (1a'). [ka]

[0037] In formula (1a'), R HF is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. 111 is a hydrocarbyl group having 1 to 38 carbon atoms which may contain a heteroatom. The heteroatom is preferably an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, or the like, and more preferably an oxygen atom. From the viewpoint of obtaining high resolution in fine pattern formation, the hydrocarbyl group is particularly preferably one having 6 to 30 carbon atoms.

[0038] R 111The hydrocarbyl group having 1 to 38 carbon atoms and 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 38 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, a nonyl group, an undecyl group, a tridecyl group, a pentadecyl group, a heptadecyl group, and an icosanyl group; a cyclopentyl group, a cyclohexyl group, a 1-adamantyl group, a 2-adamantyl group, a 1-adamantylmethyl group, and a norbornyl group. cyclic saturated hydrocarbyl groups having 3 to 38 carbon atoms such as a norbornylmethyl group, a tricyclodecanyl group, a tetracyclododecanyl group, a tetracyclododecanylmethyl group, or a dicyclohexylmethyl group; unsaturated aliphatic hydrocarbyl groups having 2 to 38 carbon atoms such as an allyl group or a 3-cyclohexenyl group; aryl groups having 6 to 38 carbon atoms such as a phenyl group, a 1-naphthyl group, or a 2-naphthyl group; aralkyl groups having 7 to 38 carbon atoms such as a benzyl group or a diphenylmethyl group; and groups obtained by combining these.

[0039] 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. Examples of hydrocarbyl groups containing hetero atoms include tetrahydrofuryl, methoxymethyl, ethoxymethyl, methylthiomethyl, acetamidomethyl, trifluoroethyl, (2-methoxyethoxy)methyl, acetoxymethyl, 2-carboxy-1-cyclohexyl, 2-oxopropyl, 4-oxo-1-adamantyl, and 3-oxocyclohexyl groups.

[0040] In formula (1b), R fb1 and R fb2 are each independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in formula (1a'). 111 Examples of the hydrocarbyl group represented by R include the same as those exemplified above. fb1 and R fb2 is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fb1 and R fb2 means that the groups to which they are bonded (-CF2-SO2-N - -SO2-CF2-) together to form a ring, in which case, R fb1 and R fb2 The group obtained by bonding together is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0041] In formula (1c), R fc1 , R fc2 and R fc3 are each independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in formula (1a'). 111 Examples of the hydrocarbyl group represented by R include the same as those exemplified above. fc1 , R fc2 and R fc3 is preferably a fluorine atom or a linear alkyl group having 1 to 4 carbon atoms. fc1 and R fc2 are groups that are bonded together and bonded to each other (-CF2-SO2-C - -SO2-CF2-) together to form a ring, in which case, R fc1 and R fc2 The group obtained by bonding together is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0042] In formula (1d), R fd is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in formula (1a'). 111 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0043] Examples of the anion represented by formula (1d) include the same anions as those exemplified as the anion represented by formula (1D) in JP 2018-197853 A.

[0044] Although the photoacid generator containing the anion represented by formula (1d) does not have a fluorine atom at the α-position of the sulfo group, it has two trifluoromethyl groups at the β-position, and therefore has sufficient acidity to cleave the acid labile groups in the base polymer, making it suitable for use as a photoacid generator.

[0045] Examples of the anion of the photoacid generator include, but are not limited to, the following: In the following formula, Ac is an acetyl group. [ka]

[0046] [ka]

[0047] [ka]

[0048] [ka]

[0049] [ka]

[0050] [ka]

[0051] [ka]

[0052] [ka]

[0053] In the resist composition of the present invention, the content of the photoacid generator (II), component, is preferably 1 to 40 parts by mass, and more preferably 5 to 35 parts by mass, per 80 parts by mass of the base polymer (IV), component (II), which will be described later. The photoacid generators (II) may be used alone or in combination of two or more.

[0054] [(III) Photodegradable quencher] The photodegradable quencher (III) is an iodonium salt that generates a weaker acid than the photoacid generator (II). The anion of this weak acid undergoes salt exchange with the strong acid generated upon exposure to form a weak acid and a strong acid-iodonium salt. In this way, the strong acid generated in the exposed areas is replaced with the weak acid, thereby suppressing acid-induced denaturation of the base polymer (described below). Meanwhile, in areas with a sufficiently high exposure dose, the iodonium cation after salt exchange also decomposes to generate a strong acid, which changes the dissolution rate of the resist film in the developer, allowing pattern formation.

[0055] The photodegradable quencher is represented by the following formula (2). [ka]

[0056] In formula (2), Ar 3 and Ar 4are each independently an aryl group having 6 to 18 carbon atoms which may contain a heteroatom. Examples of the aryl group include a phenyl group, a methylphenyl group, an ethylphenyl group, an n-propylphenyl group, an isopropylphenyl group, an n-butylphenyl group, an isobutylphenyl group, a sec-butylphenyl group, a tert-butylphenyl group, a cyclohexylphenyl group, a naphthyl group, a methylnaphthyl group, an ethylnaphthyl group, an n-propylnaphthyl group, an isopropylnaphthyl group, an n-butylnaphthyl group, an isobutylnaphthyl group, a sec-butylnaphthyl group, a tert-butylnaphthyl group, and a cyclohexylnaphthyl group. Furthermore, some or all of the hydrogen atoms of the aryl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- groups of the aryl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in the aryl group containing a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano 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, or the like.

[0057] Examples of the cation of the photodegradable quencher include the same cations as those given as examples of the cation of the photoacid generator of component (II).

[0058] In formula (2), Xq m- is an anion of a weak acid having a valence of m, where m is an integer of 1 or greater. m is preferably an integer of 1 to 3, more preferably 1 or 2, and even more preferably 1.

[0059] Examples of the anion of the photodegradable quencher include, but are not limited to, the following: [ka]

[0060] [ka]

[0061] [ka]

[0062] [ka]

[0063] [ka]

[0064] In the resist composition of the present invention, the content of the photodegradable quencher (component (III)) is preferably 5 to 20 parts by mass, and more preferably 10 to 15 parts by mass, relative to 80 parts by mass of the base polymer (component (IV)) described below. The photodegradable quencher (component (III)) may be used alone or in combination of two or more different types.

[0065] [(IV) Base polymer] The base polymer of component (IV) is a polymer whose dissolution rate in a developer changes with the action of an acid. This dissolution rate may increase or decrease. Examples of such polymers include those whose molecular weight changes due to crosslinking or decomposition of polymer chains, and those whose polarity changes due to decomposition of acid-labile groups. Crosslinking of polymer chains may also be induced by a crosslinking agent.

[0066] The base polymer preferably contains a repeating unit represented by the following formula (a) (hereinafter also referred to as repeating unit a). [ka]

[0067] In formula (a), R A is a hydrogen atom or a methyl group. 1R is a single bond, an ester bond, an amide bond, or a divalent linking group having 1 to 12 carbon atoms and containing at least one bond selected from a phenylene group, a naphthylene group, an ester bond, an ether bond, a lactone ring, and an amide bond. 11 is a hydrogen atom, a fluorine atom, or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and R 11 and X 1 and may be bonded to each other to form a ring together with the carbon atoms on the aromatic ring to which they are bonded. p is 1 or 2, q is an integer of 0 to 4, and 1≦p+q≦5. r is 0 or 1.

[0068] The repeating unit a has a phenolic hydroxy group and exhibits a sensitizing effect that increases the efficiency of acid generation from the photoacid generator, making it effective in improving sensitivity. However, it is believed that the repeating unit a generates a highly nucleophilic phenoxide anion in the resist solution, which accelerates the decomposition of the iodonium salt. The resist composition of the present invention has improved storage stability due to the inclusion of the acid compound of component (I), making it possible to use an iodonium salt-type photosensitive compound in combination with the repeating unit a.

[0069] Examples of monomers that provide the repeating unit a include, but are not limited to, the following: [ka]

[0070] [ka]

[0071] Furthermore, the base polymer may contain a repeating unit (hereinafter also referred to as an acid-generating unit) having a structural moiety that decomposes upon irradiation with actinic rays or radiation to generate an acid. The inclusion of the acid-generating unit in the polymer is thought to have the effect of suppressing aggregation of acid generators and achieving a uniform acid concentration distribution within the resist film.

[0072] The acid-generating unit is preferably one represented by the following formula (b1) (hereinafter also referred to as repeating unit b1) or one represented by the following formula (b2) (hereinafter also referred to as repeating unit b2). [ka]

[0073] In formulas (b1) and (b2), R A is a hydrogen atom or a methyl group. 1 is a single bond or an ester bond. 2 Y is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms, and the hydrocarbylene group may contain at least one bond selected from an ester bond, an ether bond, a lactone ring, an amide bond, a sultone ring, and an iodine atom. 3 is a single bond, an ether bond or an ester bond. 11 ~Rf 14 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, provided that at least one is a fluorine atom or a trifluoromethyl group.

[0074] Y 2 The hydrocarbylene group having 1 to 20 carbon atoms represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkanediyl groups having 1 to 20 carbon atoms, such as a methylene group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,1-diyl group, a propane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a nonane-1,9-diyl group, a decane-1,10-diyl group, and a 2,2-dimethylpropane-1,3-diyl group; and alkanediyl groups having 1 to 20 carbon atoms, such as a cyclopentanediyl group, a cyclohexanediyl group, a norbornanediyl group, and an adamantanediyl group. 3Cyclic saturated hydrocarbylene groups having up to 20 carbon atoms; ethene-1,2-diyl group, 1-propene-1,3-diyl group, 2-butene-1,4-diyl group, 1-methyl-1-butene-1,4-diyl group, etc. 2 Alkenediyl groups with up to 20 carbon atoms; 2-cyclohexene-1,4-diyl groups, etc. 3 Cyclic unsaturated aliphatic hydrocarbylene groups with carbon atoms of up to 20; phenylene groups, naphthylene groups, etc. 6 aryl groups having 1 to 20 carbon atoms; groups obtained by combining these; and the like.

[0075] Examples of the anion of the monomer that provides the repeating unit b1 or b2 include, but are not limited to, the following. [ka]

[0076] [ka]

[0077] [ka]

[0078] [ka]

[0079] [ka]

[0080] [ka]

[0081] In formula (b1), Ar 5 and Ar 6are each independently an aryl group having 6 to 18 carbon atoms which may contain a heteroatom. Examples of the aryl group include a phenyl group, a methylphenyl group, an ethylphenyl group, an n-propylphenyl group, an isopropylphenyl group, an n-butylphenyl group, an isobutylphenyl group, a sec-butylphenyl group, a tert-butylphenyl group, a cyclohexylphenyl group, a naphthyl group, a methylnaphthyl group, an ethylnaphthyl group, an n-propylnaphthyl group, an isopropylnaphthyl group, an n-butylnaphthyl group, an isobutylnaphthyl group, a sec-butylnaphthyl group, a tert-butylnaphthyl group, and a cyclohexylnaphthyl group. Furthermore, some or all of the hydrogen atoms of the aryl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- groups of the aryl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in the aryl group containing a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano 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, or the like.

[0082] Examples of the cation of the monomer that provides the repeating unit b1 include, but are not limited to, the following. [ka]

[0083] In formula (b2), R 21 ~R 23 R are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 21 ~R 23The hydrocarbyl group having 1 to 20 carbon atoms 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 ethynyl groups. alkynyl groups having 2 to 20 carbon atoms such as a propynyl group or a butynyl group; cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 20 carbon atoms such as a cyclohexenyl group or a norbornenyl group; aryl groups having 6 to 20 carbon atoms such as a phenyl group, a methylphenyl group, an ethylphenyl group, an n-propylphenyl group, an isopropylphenyl group, an n-butylphenyl group, an isobutylphenyl group, a sec-butylphenyl group, a tert-butylphenyl group, a naphthyl group, a methylnaphthyl group, an ethylnaphthyl group, an n-propylnaphthyl group, an isopropylnaphthyl group, an n-butylnaphthyl group, an isobutylnaphthyl group, a sec-butylnaphthyl group or a tert-butylnaphthyl group; aralkyl groups having 7 to 20 carbon atoms such as a benzyl group or a phenethyl group; and groups obtained by combining these. 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 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.

[0084] Also, R 21 and R 22 and may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, the ring preferably has the following structure: [ka] (In the formula, the dashed line indicates R 23 )

[0085] Examples of the cation of the monomer that provides the repeating unit b2 include, but are not limited to, the following. [ka]

[0086] [ka]

[0087] [ka]

[0088] When the base polymer contains the repeating unit b1, the resist composition of the present invention may or may not contain a photoacid generator (component (II)). When the base polymer does not contain the repeating unit b1, the resist composition of the present invention will contain one or both of a photoacid generator (component (II)) and a photodegradable quencher (component (III)).

[0089] The base polymer may contain a repeating unit c in which the hydrogen atom of a carboxy group is substituted with an acid labile group. Examples of the repeating unit c include those represented by the following formula (c). [ka]

[0090] In formula (c), 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. AL is an acid labile group.

[0091] Examples of monomers that provide the repeating unit c include, but are not limited to, those shown below. A and R AL is the same as above. [ka]

[0092] [ka]

[0093] R AL Examples of the acid labile group represented by the formula (AL-1) include, but are not limited to, groups represented by the following formulas (AL-1) to (AL-19). [ka] (In the formula, the dashed lines represent bonds.)

[0094] In formulas (AL-1) to (AL-19), R L1 are each independently a saturated hydrocarbyl group having 1 to 8 carbon atoms or an aryl group having 6 to 20 carbon atoms. L2 and R L4 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 20 carbon atoms. L3 is an aryl group having 6 to 20 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic. The aryl group is preferably a phenyl group. R F is a fluorine atom or a trifluoromethyl group, and a is an integer of 1 to 5.

[0095] The base polymer may contain repeating units other than repeating units a to c (hereinafter also referred to as repeating unit d). As the repeating unit d, known ones used in the base polymer of the resist composition can be used. Specific examples thereof include (meth)acrylate units having an adhesion group such as a lactone structure, a hydroxy group other than a phenolic hydroxy group, and a carboxy group, and (meth)acrylic acid units.

[0096] When the base polymer contains the repeating unit c, the resist composition of the present invention is a positive resist composition. At this time, the content ratios of the repeating units a, b1, b2, c, and d are preferably 0 ≦ a < 1.0, 0 ≦ b1 ≦ 0.5, 0 ≦ b2 ≦ 0.5, 0 ≦ b1 + b2 ≦ 0.5, 0 < c < 1.0, and 0 ≦ d < 1.0, more preferably 0 ≦ a ≦ 0.9, 0 ≦ b1 ≦ 0.4, 0 ≦ b2 ≦ 0.4, 0 ≦ b1 + b2 ≦ 0.4, 0.1 ≦ c ≦ 0.9, and 0 ≦ d ≦ 0.9, and still more preferably 0 ≦ a ≦ 0.8, 0 ≦ b1 ≦ 0.3, 0 ≦ b2 ≦ 0.3, 0 ≦ b1 + b2 ≦ 0.3, 0.2 ≦ c ≦ 0.8, and 0 ≦ d ≦ 0.8. Note that a + b1 + b2 + c + d ≦ 1.0, but a + b1 + b2 + c + d = 1.0 is preferred.

[0097] On the other hand, when the base polymer does not contain a repeating unit substituted with an acid-labile group, the resist composition of the present invention is a negative resist composition. At this time, the content ratios of the repeating units a, b1, b2, and d are preferably 0 < a ≦ 1.0, 0 ≦ b1 ≦ 0.5, 0 ≦ b2 ≦ 0.5, 0 ≦ b1 + b2 ≦ 0.5, and 0 ≦ d < 1.0, more preferably 0.1 ≦ a ≦ 0.9, 0 ≦ b1 ≦ 0.4, 0 ≦ b2 ≦ 0.4, 0 ≦ b1 + b2 ≦ 0.4, and 0 ≦ d ≦ 0.9, and still more preferably 0.2 ≦ a ≦ 0.8, 0 ≦ b1 ≦ 0.3, 0 ≦ b2 ≦ 0.3, 0 ≦ b1 + b2 ≦ 0.3, and 0 ≦ d ≦ 0.8. Note that a + b1 + b2 ≦ 1.0, but a + b1 + b2 = 1.0 is preferred.

[0098] [[ID= [(V) Organic solvent] The resist composition of the present invention may further comprise an organic solvent as component (V). There are no particular limitations on the organic solvent, so long as it is capable of dissolving the components of the resist composition of the present invention. 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 No. 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 esters include propylene glycol monoethyl 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, propylene glycol mono-tert-butyl ether acetate, and lactones such as γ-butyrolactone.

[0099] When the resist composition of the present invention contains an organic solvent as component (V), the amount thereof is preferably 100 to 10,000 parts by mass, and more preferably 200 to 8,000 parts by mass, per 80 parts by mass of the base polymer as component (IV).The organic solvent as component (V) may be used alone, or two or more types may be mixed and used.

[0100] [(VI) Surfactants] The resist composition of the present invention may further comprise a surfactant as component (VI). Examples of such surfactants 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 composition. When the resist composition of the present invention comprises a surfactant as component (VI), the amount of the surfactant is preferably 0.0001 to 10 parts by mass per 80 parts by mass of the base polymer as component (IV). The surfactant as component (IV) may be used alone, or two or more different surfactants may be used in combination.

[0101] [(VII) Crosslinking Agent] When the resist composition of the present invention is a negative resist, it is preferable to further add a crosslinking agent as component (VII), which crosslinks the base polymer in the exposed areas and reduces the dissolution rate, thereby obtaining a negative pattern.

[0102] Specific examples of the crosslinking agent include compounds containing a double bond, such as epoxy compounds, melamine compounds, guanamine compounds, glycoluril compounds or urea compounds, isocyanate compounds, azide compounds, and alkenyloxy groups, all of which are substituted with at least one group selected from a methylol group, an alkoxymethyl group, and an acyloxymethyl group.

[0103] Examples of the epoxy compound include tris(2,3-epoxypropyl)isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, and triethylolethane triglycidyl ether.

[0104] Examples of the melamine compound include compounds in which 1 to 6 methylol groups are methoxymethylated, such as hexamethylol melamine, hexamethoxymethyl melamine, and hexamethylol melamine, and mixtures thereof; and compounds in which 1 to 6 methylol groups are acyloxymethylated, such as hexamethoxyethyl melamine, hexaacyloxymethyl melamine, and hexamethylol melamine, and mixtures thereof.

[0105] Examples of the guanamine compound include compounds in which 1 to 4 methylol groups are methoxymethylated, such as tetramethylolguanamine, tetramethoxymethylguanamine, and tetramethylolguanamine, and mixtures thereof; and compounds in which 1 to 4 methylol groups are acyloxymethylated, such as tetramethoxyethylguanamine, tetraacyloxyguanamine, and tetramethylolguanamine, and mixtures thereof.

[0106] Examples of the glycoluril compound include compounds in which 1 to 4 methylol groups are methoxymethylated, such as tetramethylol glycoluril, tetramethoxyglycoluril, tetramethoxymethyl glycoluril, and tetramethylol glycoluril, or mixtures thereof; and compounds in which 1 to 4 methylol groups are acyloxymethylated in tetramethylol glycoluril, or mixtures thereof.

[0107] Examples of the urea compound include tetramethylol urea, tetramethoxymethyl urea, compounds in which 1 to 4 methylol groups are methoxymethylated, such as tetramethylol urea, or mixtures thereof, and tetramethoxyethyl urea.

[0108] Examples of the isocyanate compound include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and cyclohexane diisocyanate.

[0109] Examples of the azide compound include 1,1'-biphenyl-4,4'-bisazide, 4,4'-methylidenebisazide, and 4,4'-oxybisazide.

[0110] Examples of the compound 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.

[0111] When the resist composition of the present invention contains a crosslinking agent (VII), the amount thereof is preferably 0.1 to 50 parts by mass, and more preferably 1 to 30 parts by mass, per 80 parts by mass of the base polymer (IV).The crosslinking agents (VII) may be used alone, or two or more different crosslinking agents may be used in combination.

[0112] [Pattern formation method] When the resist composition of the present invention is used in the manufacture of various integrated circuits, known lithography techniques can be applied. For example, the following pattern formation methods can be used: (i) forming a resist film on a substrate using the resist composition; (ii) exposing the resist film to high-energy radiation; (iii) developing the exposed resist film using a developer; The method includes the steps of:

[0113] [Step (i)] The resist composition of the present invention is applied to a substrate for integrated circuit manufacturing (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective 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., so as to give a coating thickness of 0.01 to 2 μm. This is then pre-baked on a hot plate for 30 seconds to 20 minutes to form a resist film.

[0114] [Step (ii)] 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 100 μC / cm 2 approximately, more preferably 0.5 to 50 μC / cm 2 The resist composition 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.

[0115] After exposure, post-exposure baking (PEB) may be performed on a hot plate or in an oven, preferably at 50 to 150° C. for 10 seconds to 30 minutes, more preferably at 60 to 120° C. for 30 seconds to 20 minutes.

[0116] [Step (iii)] After exposure or PEB, the exposed resist film is developed using a developer of an alkaline aqueous solution of 0.1 to 10% by mass, preferably 2 to 5% by mass, such as tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or tetrabutylammonium hydroxide, for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes, by a conventional method such as dipping, puddling, or spraying, to form the desired pattern. In the case of a positive resist composition, the irradiated portions dissolve in the developer, while the unexposed portions remain insoluble, forming a positive pattern on the substrate. In the case of a negative resist composition, the opposite occurs; that is, the irradiated portions become insoluble in the developer, while the unexposed portions dissolve.

[0117] A positive resist composition containing a base polymer having an acid labile group can be used to obtain a negative pattern by organic solvent development. Examples of the organic solvent developer 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, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonate, ethyl crotonate, propyl cyclohexanone ... Examples of the organic solvent include 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.

[0118] After the development is completed, it is preferable to rinse the resist film. As a rinse solution, a solvent that is miscible with the developer but does not dissolve the resist film is preferable. As such a solvent, alcohols having 3 to 10 carbon atoms, ether compounds having 8 to 12 carbon atoms, alkanes, alkenes, alkynes having 6 to 12 carbon atoms, and aromatic solvents are preferably used.

[0119] 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, Examples of such an alcohol include 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, and 1-octanol.

[0120] 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.

[0121] Examples of the 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 the alkenes having 6 to 12 carbon atoms include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, cyclooctene, etc. Examples of the alkynes having 6 to 12 carbon atoms include hexyne, heptine, octyne, etc.

[0122] Examples of the aromatic solvent include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, and mesitylene.

[0123] 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.

[0124] 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]

[0125] EXAMPLES The present invention will be specifically explained below using examples and comparative examples, but the present invention is not limited to these.

[0126] [Examples 1-1 to 1-21, Comparative Examples 1-1 to 1-13] Preparation of resist composition Resist compositions (Examples: R-1 to R-21, Comparative Examples: cR-1 to cR-13) were prepared by dissolving each component in the composition shown in Tables 1 and 2 in a solvent containing 50 ppm of Omnova surfactant PolyFox PF-636. The resulting solution was filtered through a 0.2 μm filter. The contents of each resist composition are shown in Tables 1 and 2.

[0127] In Tables 1 and 2, the components are as follows: Organic solvent: PD (propylene glycol monomethyl ether acetate) 2800 parts by mass and a mixed solvent of 1,200 parts by mass of diacetone alcohol) PDE (propylene glycol monomethyl ether acetate) 1600 mass parts by mass, 400 parts by mass of diacetone alcohol, and 2,000 parts by mass of ethyl lactate Solvent)

[0128] Base polymer: P-1 to P-14 [ka]

[0129] [ka]

[0130] [ka]

[0131] Photoacid generator: PAG-1 to PAG-4, cPAG-1 [ka]

[0132] Quencher: Q-1 to Q-8, cQ-1, cQ-2 [ka]

[0133] ·Acid compounds: a-1~a-4, ca-1, ca-2 [ka]

[0134] Crosslinking agent: X-1, X-2 [ka]

[0135] [Table 1]

[0136] [Table 2]

[0137] [Examples 2-1 to 2-21, Comparative Examples 2-1 to 2-9] Evaluation of storage stability Resist compositions R-1 to R-21 and cR-1 to cR-9 were stored at 40°C for two weeks, then spin-coated onto an anti-reflective coating DUV-42 manufactured by Nissan Chemical Co., Ltd., which had been prepared to a thickness of 61 nm on an 8-inch wafer, and pre-baked on a hot plate for 60 seconds to produce a resist film with a thickness of approximately 50 nm. Resist compositions R-1 to R-21 and cR-1 to cR-9 were also stored at -10°C for two weeks, then spin-coated onto an anti-reflective coating DUV-42 manufactured by Nissan Chemical Co., Ltd., which had been prepared to a thickness of 61 nm on an 8-inch wafer, and pre-baked on a hot plate for 60 seconds to produce a resist film with a thickness of approximately 50 nm. Film thickness measurements were performed using a film thickness meter VM-2210 manufactured by Hitachi High-Tech Corporation. The resist film was exposed using a KrF exposure machine (Nikon Corporation S206D, NA 0.68, σ 0.75, 2 / 3 axial illumination, 6% halftone phase shift) and subjected to PEB on a hot plate at 95°C for 60 seconds. After PEB, resist compositions R-1 to R-7, R-10 to R-21, and cR-1 to cR-9 were developed for 30 seconds with a 2.38% by mass aqueous solution of TMAH. Resist compositions R-8 and R-9 were developed with butyl acetate. The developed patterns were observed with a Hitachi High-Technologies Corporation critical dimension SEM (S9380) to evaluate sensitivity.

[0138] The sensitivity of the resist film was defined as the exposure dose at which the pattern line width became 90 nm, and the sensitivity fluctuation range when stored at 40°C and when stored at -10°C are shown in Tables 3 and 4. Furthermore, storage stability was evaluated based on the following criteria. The results of Examples 2-1 to 2-21 are shown in Table 3, and the results of Comparative Examples 2-1 to 2-9 are shown in Table 4. Furthermore, Example 2-2 and Comparative Example 2-4 were selected as representative compositions for the storage stability evaluation, and a graph showing the change in sensitivity over time as the storage period was extended is shown in Figure 1. The sensitivity fluctuation was calculated using the following formula: Sensitivity fluctuation = (D -10 -D 40 ) / D -10 ×100 [where D -10 The sensitivity of the sample stored at -10°C for 2 weeks was 40 is the sensitivity after storage at 40°C for 2 weeks.] (Judgment criteria) ○: Sensitivity fluctuation is less than 3% ×: Sensitivity fluctuation is 3% or more

[0139] [Table 3]

[0140] [Table 4]

[0141] The results shown in Tables 3, 4, and Figure 1 indicate that resist compositions containing an iodonium salt-type photoacid generator and / or photodegradable quencher but not an acid compound gradually become more sensitive when stored at 40°C, resulting in a significant difference in sensitivity compared to the composition stored at -10°C. On the other hand, resist compositions containing an acid compound showed a smaller range of sensitivity fluctuation. This is thought to be because the addition of an acid compound suppresses decomposition of the iodonium salt during storage.

[0142] [Examples 3-1 to 3-17, Comparative Examples 3-1 to 3-4] EUV Lithography Evaluation Resist compositions R-1 to R-17 and cR-10 to cR-13 were spin-coated onto a Si substrate on which a 20 nm thick silicon-containing spin-on hard mask SHB-A940 (43% silicon by mass) manufactured by Shin-Etsu Chemical Co., Ltd. had been formed, and the substrate was pre-baked at 105°C for 60 seconds using a hot plate to produce a 50 nm thick resist film. The resist film was exposed to an LS pattern with an on-wafer dimension of 18 nm and a pitch of 36 nm using an ASML EUV scanner NXE3300 (NA 0.33, σ 0.9 / 0.6, dipole illumination) while varying the exposure dose and focus of EUV with a wavelength of 13.5 nm (exposure dose pitch: 1 mJ / cm). 2The exposure was performed with a focus pitch of 0.020 μm, and post-exposure bake (PEB) was performed at 95°C for 60 seconds. After PEB, resist compositions R-1 to R-7, R-10 to R-17, and cR-10 to cR-13 were subjected to puddle development with a 2.38 mass% aqueous TMAH solution for 30 seconds, followed by spin drying to obtain positive patterns. Resist compositions R-8 and R-9 were developed with butyl acetate to obtain negative patterns. The developed LS patterns were observed with a critical dimension SEM (CG6300) manufactured by Hitachi High-Tech Corporation, and the optimal exposure dose Eop (mJ / cm) required to obtain LS patterns with a line width of 18 nm and a pitch of 36 nm was determined. 2 ) was calculated and used as the sensitivity. In addition, three times the standard deviation (σ) calculated from the measurement results of the pattern dimensions (3σ) was calculated as the pattern width variation (LWR). The results of Examples 3-1 to 3-17 are shown in Table 5, and the results of Comparative Examples 3-1 to 3-4 are shown in Table 6. (Judgment criteria) ◎: Eop is 30mJ / cm 2 and LWR is less than 4.0 ○: Eop is 30 mJ / cm 2 and LWR is 4.0 or more and less than 4.5 ×: Eop is 30 mJ / cm 2 or more and LWR value is 4.5 or more

[0143] [Table 5]

[0144] [Table 6]

[0145] The results shown in Tables 5 and 6 demonstrate that the resist composition of the present invention has small edge roughness and dimensional variation, and has good storage stability.

Claims

1. A resist composition comprising: (I) an acid compound represented by the following formula (A), (II) a photoacid generator represented by the following formula (1) and / or (III) a photodegradable quencher represented by the following formula (2), and (IV) a base polymer that contains a repeating unit represented by the following formula (a), and whose dissolution rate in a developer is changed by the action of an acid: 【Chemistry 1】 (In the formula, R 1 Rf is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a fluorine atom, a hydroxy group, or a heteroatom. 1 and Rf 2 are each independently a fluorine atom or a trifluoromethyl group. 【Chemistry 2】 (In the formula, Ar 1 and Ar 2 are each independently an aryl group having 6 to 18 carbon atoms which may contain a heteroatom. n- is an anion of a strong acid having a valence of n, where n is an integer of 1 or more. 【Transformation 3】 (In the formula, Ar 3 and Ar 4 are each independently an aryl group having 6 to 18 carbon atoms which may contain a heteroatom. m- is an anion of a weak acid having a valence of m, where m is an integer of 1 or more. 【Chemistry 4】 (wherein R A is a hydrogen atom or a methyl group. X 1 is a single bond, an ester bond or an amide bond, or a divalent linking group having 1 to 12 carbon atoms and containing at least one bond selected from a phenylene group, a naphthylene group, an ester bond, an ether bond, a lactone ring and an amide bond. R 11 is a hydrogen atom, a fluorine atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and R 11 and X 1 may be bonded to each other to form a ring together with the carbon atoms on the aromatic ring to which they are bonded. p is 1 or 2, q is an integer of 0 to 4, and 1≦p+q≦5. r is 0 or 1.

2. A resist composition comprising: (I) an acid compound represented by the following formula (A); and (IV') a base polymer which contains a repeating unit represented by the following formula (b1), and whose dissolution rate in a developer changes under the action of an acid: 【Transformation 5】 (In the formula, R 1 Rf is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a fluorine atom, a hydroxy group, or a heteroatom. 1 and Rf 2 are each independently a fluorine atom or a trifluoromethyl group. 【Transformation 6】 (In the formula, R A is a hydrogen atom or a methyl group. Y 1 is a single bond or an ester bond. Y 2 is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms, and the hydrocarbylene group may contain at least one bond selected from an ester bond, an ether bond, a lactone ring, an amide bond, a sultone ring, and an iodine atom. Y 3 is a single bond, an ether bond or an ester bond. Rf 11 ~Rf 14 are each independently a hydrogen atom, a fluorine atom or a trifluoromethyl group, provided that at least one is a fluorine atom or a trifluoromethyl group. Ar 5 and Ar 6 are each independently an aryl group having 6 to 18 carbon atoms which may contain a heteroatom.

3. 3. The resist composition according to claim 2, further comprising (III) a photodecomposable quencher represented by the following formula (2): 【Transformation 7】 (In the formula, Ar 3 and Ar 4 are each independently an aryl group having 6 to 18 carbon atoms which may contain a heteroatom. m- is an anion of a weak acid having a valence of m, where m is an integer of 1 or more.

4. 3. The resist composition according to claim 1, wherein the acid compound represented by formula (A) is represented by any one of the following formulae (A-1) to (A-3): 【Transformation 8】 (In the formula, R 1A is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom. 2 and R 3 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms. 2 and R 3 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. L is a single bond, an ether bond, or an ester bond.

5. 3. The resist composition according to claim 2, wherein the base polymer contains a repeating unit represented by the following formula (a): 【Chemistry 9】 (In the formula, R A is a hydrogen atom or a methyl group. X 1 is a divalent linking group having 1 to 12 carbon atoms which is a single bond, an ester bond, an amide bond, or at least one bond selected from a phenylene group, a naphthylene group, an ester bond, an ether bond, a lactone ring, and an amide bond. R 11 is a hydrogen atom, a fluorine atom, or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and R 11 and X 1 may be bonded to each other to form a ring together with the carbon atoms on the aromatic ring to which they are attached. p is 1 or 2, q is an integer of 0 to 4, and 1≦p+q≦5. r is 0 or 1.

6. 2. The resist composition according to claim 1, wherein the base polymer contains a repeating unit having a structural moiety that decomposes upon irradiation with actinic rays or radiation to generate an acid.

7. 7. The resist composition according to claim 6, wherein the repeating unit having a structural moiety that decomposes upon irradiation with actinic rays or radiation to generate an acid is represented by the following formula (b2): 【Chemistry 10】 (In the formula, R A is a hydrogen atom or a methyl group. Y 1 is a single bond or an ester bond. Y 2 is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms, and the hydrocarbylene group may contain at least one bond selected from an ester bond, an ether bond, a lactone ring, an amide bond, a sultone ring, and an iodine atom. Y 3 is a single bond, an ether bond or an ester bond. Rf 11 ~Rf 14 are each independently a hydrogen atom, a fluorine atom or a trifluoromethyl group, provided that at least one is a fluorine atom or a trifluoromethyl group. R 21 ~R 23 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, and R 21 and R 22 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.)

8. 3. The resist composition according to claim 1, wherein the base polymer comprises a repeating unit c in which the hydrogen atom of the carboxy group is substituted with an acid labile group.

9. 9. The resist composition according to claim 8, wherein the repeating unit c is represented by the following formula (c): 【Chemistry 11】 (In the formula, R A is a hydrogen atom or a methyl group. Z 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 AL is an acid labile group.

10. 3. The resist composition according to claim 1, wherein the base polymer does not contain any repeating units substituted with an acid labile group.

11. The resist composition according to claim 10, further comprising a crosslinking agent.

12. 3. A pattern forming method comprising: (i) forming a resist film on a substrate using the resist composition according to claim 1; (ii) exposing the resist film to high-energy rays; and (iii) developing the exposed resist film using a developer.

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