Resist material and pattern forming method

Abstract

To provide a resist material having small edge roughness and dimensional variations, excellent resolution, a good pattern shape after exposure, and good storage stability, and to provide a pattern forming method.SOLUTION: The resist material contains: (Ia) a polymer which contains a repeating unit (A) containing a hydroxyl group or a carboxy group; (II) a crosslinking agent having a structure represented by the following formula (1); and (III) a quencher having a structure represented by the following formula (2).SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

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

[0003] In lithography using DUV light sources, i.e., KrF and ArF excimer lasers, chemically amplified resists, which change the solubility in the developer by causing a reaction of the base polymer resin using the acid generated from the photosensitizer upon exposure as a catalyst, have achieved high-sensitivity, high-resolution lithography and have led the way in miniaturization as the main resist used in actual production processes.

[0004] Chemically amplified resists continue to be widely studied for next-generation lithography, such as EUV, and have been commercialized. Meanwhile, demand for improved resist performance is increasing as miniaturization advances. In particular, line edge roughness (LER) in resist pattern dimensions affects pattern dimensional variations after substrate processing, which ultimately impacts device operational stability, so it is essential to minimize this.

[0005] Various factors that contribute to LER in chemically amplified resists include the characteristics of the dissolution rate change curve (dissolution contrast) versus exposure dose, acid diffusion length, and compatibility of the mixed composition, but in addition to these, the effects of the chain length, molecular size, and molecular weight of the polymer resin have recently been attracting attention. It is thought that reducing the molecular weight of the polymer to make the dissolution unit during development smaller is effective in reducing LER.

[0006] However, as the molecular weight of the base polymer decreases, problems such as pattern collapse due to reduced strength, promotion of acid diffusion due to a drop in the glass transition temperature, and reduced resolution due to increased solubility in the developer of unexposed areas have been encountered. To solve these problems, attempts have been made to crosslink polymer chains using acid-decomposable crosslinking groups. Crosslinking can increase the molecular weight in advance, and the crosslinks in exposed areas can be decomposed by the acid generated during exposure. Patent Document 1 discloses a crosslinked polymer obtained by reacting a unit having a carboxyl group or a hydroxyl group with a divinyl ether unit.

[0007] On the other hand, crosslinked polymers formed by crosslinking between polymer chains have very large molecular weights, and when stored for a long time as a resist solution, the polymers aggregate, causing a problem of an increase in the number of defects.

[0008] Patent Document 2 discloses a resist material containing a polymer having a reactive site and a monomer crosslinking agent.

[0009] However, there are problems in that the crosslinking reaction between the crosslinker and the polymer does not proceed sufficiently during the baking process after coating on the substrate, and the remaining monomeric components adversely affect lithography performance. In addition, there is also the problem that the acid generated in the exposed area by the action of the photoacid generator diffuses to the unexposed area, easily decomposing the crosslinked structure. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 5562651 [Patent Document 2] International Publication No. WO2018 / 079449 Summary of the Invention [Problem to be solved by the invention]

[0011] In resists containing compounds with vinyl ether groups as crosslinkers, acetal structures are formed by addition reactions with carboxyl and hydroxyl groups. The resulting acetal structures are easily decomposed by the action of strong acids generated by photoacid generators, resulting in a resist film with low molecular weight in exposed areas and high molecular weight in unexposed areas, thereby enhancing dissolution contrast.

[0012] However, in conventional resists containing crosslinkers, the crosslinking reaction does not proceed sufficiently during a short baking process, resulting in the crosslinker remaining unreacted. Furthermore, because the acetal structure is highly decomposable, it easily decomposes to form monomer components due to the diffusion of strong acid components generated in the exposed areas. These components act like plasticizers in the resist film, lowering the glass transition temperature of the film and promoting the diffusion of acid generated by exposure, resulting in poor lithography performance. Furthermore, adding acid to a resist solution to promote the crosslinking reaction poses storage stability problems due to the progression of undesired crosslinking reactions during solution storage.

[0013] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resist material and a pattern forming method which have small edge roughness and dimensional variation, excellent resolution, a good pattern shape after exposure, and good storage stability. [Means for solving the problem]

[0014] In order to solve the above problems, the present invention provides: (Ia) a polymer containing a repeating unit (A) containing a hydroxyl group or a carboxyl group; (II) a crosslinking agent having a structure represented by the following formula (1): (III) a quencher having a structure represented by the following formula (2): (IV) an organic solvent; (V) a component that decomposes upon exposure to actinic rays or radiation to generate an acid; The present invention provides a resist material containing [ka] [In the formula, R represents an n-valent organic group which may have a substituent.] L 1 is a linking group selected from a single bond, an ester bond, and an ether bond. R 1 represents a single bond or a divalent organic group, and n is an integer of 1 to 4. [ka] [In the formula, R 31 R is a monovalent organic group which may have a substituent. 33 ~R 35 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. 33 , R 34 and R 35 Any two of may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

[0015] Such a resist material can provide a resist material that exhibits small edge roughness and dimensional variation, excellent resolution, a good pattern shape after exposure, and good storage stability.

[0016] The present invention also provides (Ib) a polymer containing a repeating unit (A) containing a hydroxyl group or a carboxyl group and a repeating unit (C) having a structural moiety that decomposes upon irradiation with actinic rays or radiation to generate an acid; (II) a crosslinking agent having a structure represented by the following formula (1): (III) a quencher having a structure represented by the following formula (2): (IV) an organic solvent; The present invention provides a resist material containing [ka] [In the formula, R represents an n-valent organic group which may have a substituent.] L 1 is a linking group selected from a single bond, an ester bond, and an ether bond. R 1 represents a single bond or a divalent organic group, and n is an integer of 1 to 4. [ka] [In the formula, R 31 R is a monovalent organic group which may have a substituent. 33 ~R 35 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. 33 , R 34 and R 35 Any two of may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

[0017] Such a resist material can provide a resist material that exhibits small edge roughness and dimensional variation after exposure, has excellent resolution, produces a good pattern shape after exposure, and also has good storage stability.

[0018] The repeating unit (C) contained in the polymer is preferably represented by the following formula (c). [ka] [In the formula, R c1 is a hydrogen atom or a methyl group. Z 1 is a single bond or an ester bond. 2 is a single bond or a divalent organic group having 1 to 25 carbon atoms, and may contain one or more of an ester bond, an ether bond, a lactone ring, an amide bond, a sultone ring, and an iodine atom. Rf c1 ~Rf c4 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 c2 ~R c4 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, and R c2 , R c3 and R c4 Any two of may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

[0019] Such a resist material can provide a resist material that has good solubility in an alkaline developer.

[0020] The resist material preferably further contains (V) a component that decomposes upon irradiation with actinic rays or radiation to generate an acid.

[0021] Such a resist material can improve the dissolution contrast with the unexposed area.

[0022] The repeating unit (A) contained in the polymer is preferably represented by the following formula (a1) and / or (a2). [ka] [In the formula, R A are each independently a hydrogen atom or a methyl group. a1 are each independently a single bond or a divalent linking group having 1 to 15 carbon atoms and at least one of a phenylene group, a naphthylene group, an ester bond, an ether bond, a lactone ring, an amide group, and a hetero atom. a2 R are each independently a single bond or a divalent linking group having 1 to 12 carbon atoms and at least one of a phenylene group, a naphthylene group, an ester bond, an ether bond, a lactone ring, an amide group, and a hetero atom. a1is a hydrogen atom, a fluorine atom, or an alkyl group, and R a1 and Y a2 may be bonded to form a ring. k is 1 or 2, l is an integer of 0 to 4, and 1≦k+l≦5. m is 0 or 1.]

[0023] Such a resist material can suppress the diffusion of acid generated in exposed areas by the action of the photoacid generator.

[0024] In addition, R in the formula (2) 31 Preferably, contains an iodine atom.

[0025] Such a resist material can suppress the diffusion of acid generated in exposed areas by the action of the photoacid generator.

[0026] Furthermore, R in the formula (1) preferably contains an aromatic hydrocarbon group.

[0027] Such a resist material can improve the contrast between exposed and unexposed areas.

[0028] The present invention also provides a pattern forming method, comprising the steps of: (i) applying the resist material onto a substrate to form a resist film; (ii) exposing the resist film to high-energy radiation; (iii) developing the exposed resist film using a developer; The present invention provides a pattern formation method comprising the steps of:

[0029] Such a pattern forming method makes it possible to obtain a pattern with little edge roughness and dimensional variation, excellent resolution, and a good pattern shape after exposure.

[0030] Preferably, the step (i) further comprises a step of pre-baking the resist film at 130° C. or higher.

[0031] Such a pattern formation method allows the crosslinking reaction caused by the crosslinking agent to proceed efficiently. [Effects of the Invention]

[0032] The resist material of the present invention contains a polymer having reactive groups, a vinyl ether crosslinker, and a weak acid sulfonium salt quencher. The conjugate acid of this weak acid anion is weaker in acidity than the strong acid component generated by the photoacid generator and undergoes salt exchange with the strong acid generated upon exposure to form a weak acid and a strong acid-sulfonium salt. In this way, by replacing the strong acid generated in the exposed areas with the weak acid, the quencher functions to inhibit decomposition of the acetal structure and acid-labile groups. On the other hand, in areas with a sufficiently high exposure dose, the sulfonium cation after salt exchange also decomposes to generate a strong acid, which does not inhibit the decomposition of the acetal, rapidly disintegrating the crosslinked structure and lowering the molecular weight.

[0033] Due to the effect of the above-mentioned quencher component, the resist material of the present invention maintains a neutral environment in the solution state, but a weakly acidic environment in the micro-exposure region. After extensive investigation, it was confirmed that alkanesulfonates and other salts have high acidity and induce decomposition of the acetal structure even in the micro-exposure region, while carboxylates suppress acetal decomposition. Furthermore, surprisingly, it was found that a system using a quencher with increased acidity due to the inclusion of a fluorine atom at the α-position of the carboxylic acid did not induce acetal decomposition in the micro-exposure region, but rather had an acidity suitable for catalyzing the crosslinking reaction of vinyl ether with hydroxyl and carboxyl groups.

[0034] That is, the resist material of the present invention, which contains a specific quencher component and a vinyl ether crosslinker, efficiently promotes the crosslinking reaction of polymer chains and effectively suppresses acid diffusion due to the above-mentioned effects, resulting in excellent pattern shape, roughness, and resolution after exposure, as well as good storage stability. Therefore, due to these excellent properties, the resist material is highly practical and is particularly useful as a material for forming fine patterns in photomasks for VLSI manufacturing or EB lithography, and as a pattern-forming material for EB or EUV lithography. The positive resist material 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]

[0035] [Figure 1] 1 is a graph comparing contrast between an example of the present invention and a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0036] As described above, there has been a demand for the development of a resist material that exhibits small edge roughness and dimensional variation, excellent resolution, a good pattern shape after exposure, and good storage stability.

[0037] As a result of extensive investigations into solving the above-mentioned problems, the present inventors have discovered that a resist containing a polymer compound having a specific functional group, a specific vinyl-ether crosslinking agent, and a specific carboxylate-type quencher component enables the formation of patterns with small LER and excellent resolution, while also overcoming the problem of storage stability, and have completed the present invention.

[0038] That is, the first aspect of the present invention is (Ia) a polymer containing a repeating unit (A) containing a hydroxyl group or a carboxyl group; (II) a crosslinking agent having a structure represented by the following formula (1): (III) a quencher having a structure represented by the following formula (2): (IV) an organic solvent; (V) a component that decomposes upon exposure to actinic rays or radiation to generate an acid; The resist material contains [ka] [In the formula, R represents an n-valent organic group which may have a substituent.] L 1 is a linking group selected from a single bond, an ester bond, and an ether bond. R 1 represents a single bond or a divalent organic group, and n is an integer of 1 to 4. [ka] [In the formula, R 31 R is a monovalent organic group which may have a substituent. 33 ~R 35 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. 33 , R 34 and R 35 Any two of may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

[0039] Also, a second aspect of the present invention is (Ib) a polymer containing a repeating unit (A) containing a hydroxyl group or a carboxyl group and a repeating unit (C) having a structural moiety that decomposes upon irradiation with actinic rays or radiation to generate an acid; (II) a crosslinking agent having a structure represented by the following formula (1): (III) a quencher having a structure represented by the following formula (2): (IV) A resist material containing an organic solvent. [ka] [In the formula, R represents an n-valent organic group which may have a substituent.] L 1 is a linking group selected from a single bond, an ester bond, and an ether bond. R 1 represents a single bond or a divalent organic group, and n is an integer of 1 to 4. [ka] [In the formula, R 31 R is a monovalent organic group which may have a substituent. 33 ~R 35 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. 33 , R 34 and R 35 Any two of may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

[0040] The present invention will be described in detail below, but the present invention is not limited thereto.

[0041] [First aspect] A first aspect of the present invention is a resist material containing the above-mentioned components (Ia), (II), (III), (IV), and (V). Each component will be described in detail below.

[0042] [(Ia) Base polymer] The base polymer (P) in the present invention includes a polymer containing a repeating unit (A) containing a hydroxyl group or a carboxyl group. The repeating unit (A) functions as a reaction site with the crosslinking agent (II) described below, forming a polymer on the substrate, thereby suppressing the diffusion of acid generated in exposed areas by the action of a photoacid generator.

[0043] The repeating unit (A) is preferably one represented by the following formula (a1) or (a2). [ka]

[0044] In formulas (a1) and (a2), R A is a hydrogen atom or a methyl group.

[0045] In formula (a1), Y a1 are each independently a single bond or a divalent linking group having 1 to 15 carbon atoms and at least one of a phenylene group, a naphthylene group, an ester bond, an ether bond, a lactone ring, an amide group, and a hetero atom.

[0046] In formula (a2), Y a2 are each independently a single bond or a divalent linking group having 1 to 12 carbon atoms and having at least one of a phenylene group, a naphthylene group, an ester bond, an ether bond, a lactone ring, an amide group, and a hetero atom.

[0047] In formula (a2), R a1 is a hydrogen atom, a fluorine atom, or an alkyl group, and R a1 and Y a2 may be bonded to form a ring.

[0048] In formula (a2), k is 1 or 2. l is an integer of 0 to 4, provided that 1≦k+l≦5. m is an integer of 0 or 1.

[0049] Examples of monomers that provide the repeating unit (a1) include, but are not limited to, the following. [ka]

[0050] Examples of monomers that provide the repeating unit (a2) include, but are not limited to, the following. [ka]

[0051] The content of the repeating unit (A) contained in the base polymer (P) is preferably 5 mol % or more, and more preferably 10 mol % to 80 mol %.

[0052] As the repeating unit (A), repeating units other than the repeating units (a1) and (a2) can also be used.

[0053] The base polymer (P) preferably further contains a repeating unit (B) in which the hydrogen atom of the carboxyl group in the repeating unit (A) is substituted with an acid labile group. The main methods for changing the solubility of the resist film in a developer include changing the molecular weight and changing the polarity. The crosslinking agent (II) acts to change the molecular weight, while the repeating unit (B) changes the polarity, significantly improving the contrast.

[0054] The repeating unit (B) is preferably represented by the following formula (b): [ka]

[0055] In formula (b), R b is a hydrogen atom or a methyl group. b R is a single bond or a divalent linking group having 1 to 15 carbon atoms and at least one of a phenylene group, a naphthylene group, an ester bond, an ether bond, a lactone ring, an amide group, and a hetero atom. b1 is an acid labile group.

[0056] Examples of monomers that provide the repeating unit (b) include, but are not limited to, the following. [ka]

[0057] [ka]

[0058] Also, R b1Examples of the acid labile group represented by the formula (AL-3) include, but are not limited to, groups represented by the following formulae (AL-3)-1 to (AL-3)-19. [ka] (In the formula, the dashed lines represent bonds.)

[0059] In formulas (AL-3)-1 to (AL-3)-19, R L14 are each independently a saturated hydrocarbyl group having 1 to 8 carbon atoms or an aryl group having 6 to 20 carbon atoms. L15 and R L17 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 20 carbon atoms. L16 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 g is an integer of 1 to 5.

[0060] The content of the repeating unit (B) contained in the base polymer (P) is preferably 90 mol % or less, and more preferably 70 mol % or less and 20 mol % or more.

[0061] [(II) Crosslinking Agent] The crosslinking agent (II) in the present invention has a vinyl ether group that undergoes an addition reaction with a carboxyl group or a hydroxyl group in the structural unit (A) of the base polymer (P). Crosslinking between base polymers on the substrate significantly increases the molecular weight, suppressing acid diffusion and dissolution in the developer. Furthermore, the acetal structure formed after the crosslinking reaction is decomposed by a strong acid component generated from the component (V) that generates acid upon exposure (described below). This results in a low molecular weight in the exposed area, improving the contrast between the exposed and unexposed areas.

[0062] The crosslinking agent (II) has a structure represented by the following formula (1): [ka]

[0063] In formula (1), L 1 is a linking group selected from a single bond, an ester bond, and an ether bond.

[0064] In formula (1), R 1 is a single bond or a divalent organic group.

[0065] In formula (1), R is an n-valent organic group which may have a substituent. R preferably contains a cyclic structure, and more preferably the cyclic structure is an aromatic hydrocarbon group.

[0066] In formula (1), n ​​is an integer of 1 to 4. Preferably, n is 2 or more.

[0067] Examples of the crosslinking agent (II) include, but are not limited to, the following: [ka]

[0068] [ka]

[0069] The content of the crosslinking agent (II) is preferably 0.1 to 50 parts by mass, more preferably 1 to 40 parts by mass, relative to 100 parts by mass of the base polymer. The crosslinking agent (II) may be used singly or in combination of two or more.

[0070] [(III) Quencher] The quencher (III) in the present invention is a component that traps the acid generated in the exposed area and suppresses its diffusion. The quencher (III) is a weak acid salt consisting of a carboxylate anion and a sulfonium cation, and also functions as a catalyst that promotes the crosslinking reaction of the crosslinker (II).

[0071] The weak acid thus generated in the system does not contribute to the decomposition of the acetal bond formed by the crosslinking agent (II), but rather functions as an acid catalyst that promotes crosslinking of the remaining unreacted vinyl ether structures.

[0072] The quencher (III) has a structure represented by the following formula (2). [ka]

[0073] In formula (2), R 31 R is a monovalent organic group which may have a substituent. The organic group may have an ether bond, an ester bond, an amide bond, a lactone ring, or a sultone ring. 31 Preferably, the alkyl group contains an aromatic hydrocarbon group, and more preferably, the alkyl group contains an iodine atom.

[0074] In formula (2), R 33 ~R 35 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. 33 , R 34 and R 35 Any two of these may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

[0075] Examples of the anion structure of the quencher (III) include, but are not limited to, those shown below. [ka]

[0076] [ka]

[0077] [ka]

[0078] [ka]

[0079] Examples of the cation structure of the quencher (III) include the same as those exemplified as the sulfonium cation in the repeating unit (C) described below.

[0080] The content of the quencher (III) in the resist material of the present invention is preferably 0.1 to 50 parts by mass, more preferably 1 to 40 parts by mass, relative to 100 parts by mass of the base polymer (P). The quencher (III) can be used alone or in combination of two or more.

[0081] [(IV) Organic solvent] The resist material of the present invention contains an organic solvent. The organic solvent is not particularly limited as long as it can dissolve each component contained in the resist material 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.

[0082] In the resist composition of the present invention, the content of the organic solvent is preferably 100 to 10,000 parts by mass, more preferably 200 to 8,000 parts by mass, per 100 parts by mass of the base polymer. The organic solvents may be used singly or in combination of two or more.

[0083] [(V) Component that decomposes upon exposure to actinic rays or radiation to generate an acid] The resist material of the present invention further contains a photoacid generator. The acid generated from the photoacid generator upon patterned exposure is a strong acid with a stronger acidity than the quencher (III), and decomposes the acid labile groups in the repeating unit (B) and the acetal bond formed by the crosslinker (II). This causes a change in polarity and a decrease in molecular weight in the exposed areas of the resist film, thereby improving the dissolution contrast with the unexposed areas.

[0084] Examples of the photoacid generator include compounds that generate an acid in response to actinic rays or radiation. The photoacid generator may be any compound that generates an acid upon exposure to high-energy rays, but is preferably one that generates a sulfonic acid, an imide acid, or a methide acid. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, and oxime-O-sulfonate-type acid generators. Specific examples of photoacid generators include those described in paragraphs

[0122] to

[0142] of JP 2008-111103 A.

[0085] The content of the photoacid generator (V) in the resist material of the present invention is preferably 0.1 to 50 parts by mass, more preferably 1 to 40 parts by mass, per 100 parts by mass of the base polymer (P). The photoacid generator (V) may be used singly or in combination of two or more.

[0086] As the photoacid generator, a sulfonium salt represented by the following formula (3) can be suitably used.

[0087] [ka]

[0088] In formula (3), R 21 ~R 23 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. The hydrocarbyl group may be linear, branched or cyclic. Specific examples thereof include R c2 ~R c4 Examples include the same groups as those exemplified in the description of R. In addition, some or all of the hydrogen atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH- groups of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in the group containing 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 acid anhydride, a haloalkyl group, or the like. 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 may be any of the groups represented by R c2 , R c3 and R c4 Examples of the ring that can be formed by combining any two of the above with the sulfur atom to which they are attached include the same as those exemplified above.

[0089] Examples of the cation of the sulfonium salt represented by formula (3) include the same sulfonium cations as those exemplified as the sulfonium cations of the monomer that gives the repeating unit (C) described below.

[0090] In formula (3), Xa - is an anion selected from the following formulae (3A) to (3D). [ka]

[0091] In formula (3A), 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 (3A') described below. 111 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0092] The anion represented by formula (3A) is preferably one represented by the following formula (3A'). [ka]

[0093] In formula (3A'), 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. In order to obtain high resolution in the formation of a fine pattern, the hydrocarbyl group is particularly preferably one having 6 to 30 carbon atoms.

[0094] R 111The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 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.

[0095] In addition, some or all of the hydrogen atoms in these groups may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, nitrogen atom, or halogen atom, and some of the -CH2- groups in these groups may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, or nitrogen atom, resulting in the group containing 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 acid anhydride, a haloalkyl group, etc. Examples of hydrocarbyl groups containing heteroatoms include a tetrahydrofuryl group, a methoxymethyl group, an ethoxymethyl group, a methylthiomethyl group, an acetamidomethyl group, a trifluoroethyl group, a (2-methoxyethoxy)methyl group, an acetoxymethyl group, a 2-carboxy-1-cyclohexyl group, a 2-oxopropyl group, a 4-oxo-1-adamantyl group, and a 3-oxocyclohexyl group.

[0096] Synthesis of sulfonium salts containing anions represented by formula (3A') is described in detail in JP-A Nos. 2007-145797, 2008-106045, 2009-7327, and 2009-258695. Sulfonium salts described in JP-A Nos. 2010-215608, 2012-41320, 2012-106986, and 2012-153644 are also suitable.

[0097] Examples of the anion represented by formula (3A) include the same anions as those exemplified as the anion represented by formula (1A) in JP 2018-197853 A.

[0098] In formula (3B), 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 (3A'). 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.

[0099] In formula (3C), 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 (3A').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 fluorinated 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.

[0100] In formula (3D), 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 (3A'). 111 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0101] The synthesis of sulfonium salts containing anions represented by formula (3D) is described in detail in JP-A-2010-215608 and JP-A-2014-133723.

[0102] Examples of the anion represented by formula (3D) include the same anions as those exemplified as the anion represented by formula (1D) in JP 2018-197853 A.

[0103] Although the photoacid generator containing the anion represented by formula (3D) 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.

[0104] [Surfactants] The positive resist composition of the present invention may contain a surfactant in addition to the above-mentioned components.

[0105] Examples of the surfactant include those described in paragraphs

[0165] and

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

[0106] [Second mode] The second aspect of the present invention is a resist material containing the above-mentioned components (Ib), (II), (III), and (IV). While the first aspect of the present invention uses an additive-type photoacid generator as component (V) separately from the base polymer (Ia), the second aspect of the present invention uses the base polymer (Ib) itself as a photoacid generator. Each component will be described in detail below.

[0107] [(Ib) Base polymer] The base polymer (P) in the present invention is a polymer containing a repeating unit (A) containing a hydroxyl group or a carboxyl group and a repeating unit (C) having a structural moiety that decomposes upon irradiation with actinic rays or radiation to generate an acid.

[0108] The repeating unit (A) can be the same as that described above in the base polymer (Ia).

[0109] The base polymer contains a repeating unit (C) having a structural moiety that decomposes upon exposure to actinic rays or radiation to generate an acid. Because the repeating unit (C) is highly polar, polymers containing the repeating unit (C) and having a low molecular weight have high solubility in alkaline developers. However, increasing the molecular weight of such readily soluble components through crosslinking significantly reduces the developer solubility. This effect can significantly change the solubility contrast between the crosslinked and non-crosslinked portions.

[0110] As the repeating unit (C), a repeating unit (C) represented by the following formula (c) can be used. [ka]

[0111] In formula (c), R c1 is a hydrogen atom or a methyl group.

[0112] In formula (c), Z 1 is a single bond or an ester bond. 2 is a single bond or a divalent organic group having 1 to 25 carbon atoms, and may contain an ester bond, an ether bond, a lactone ring, an amide bond, a sultone ring, or an iodine atom. It may be linear, branched, or cyclic, and specific examples thereof include a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,2-diyl group, a propane-1,3-diyl group, a propane-2,2-diyl group, a butane-1,2-diyl group, a butane-1,3-diyl group, a butane-1,4-diyl group, a butane-2,2-diyl group, a butane-2,3-diyl group, a 2-methylpropane-1,3-diyl group, a pentaerythritol-2,4-diyl group, a methylpropane-1,3-diyl group, a methylpropane-1,4-diyl group, a methylpropane-2,4-diyl group, a methylpropane-1,3 ... Examples of the alkyl group include alkanediyl groups having 1 to 20 carbon atoms, such as hexane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, and decane-1,10-diyl group; cyclic saturated hydrocarbylene groups having 3 to 20 carbon atoms, such as cyclopentanediyl group, cyclohexanediyl group, norbornanediyl group, and adamantanediyl group; and groups obtained by combining these groups.

[0113] In formula (c), Rf c1 ~Rf c4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, provided that at least one is a fluorine atom.

[0114] In formula (c), R c2 ~R c4 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom.

[0115] Also, R c2 , R c3 and R c4 Any two of the above 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 c4 )

[0116] Examples of the anionic structure of the monomer that provides the repeating unit (C) include, but are not limited to, those shown below. [ka]

[0117] [ka]

[0118] [ka]

[0119] [ka]

[0120] [ka]

[0121] [ka]

[0122] [ka]

[0123] [ka]

[0124] [ka]

[0125] [ka]

[0126] [ka]

[0127] [ka]

[0128] [ka]

[0129] [ka]

[0130] Examples of the sulfonium cation of the monomer that provides the repeating unit (C) include, but are not limited to, those shown below. [ka]

[0131] [ka]

[0132] In addition to the repeating units (A) and (C), the base polymer (P) preferably contains a repeating unit (B) in which the hydrogen atom of the carboxyl group in the repeating unit (A) is substituted with an acid labile group. The repeating unit (B) can be the same as that described above for the base polymer (Ia).

[0133] The content of the repeating unit (C) contained in the base polymer (P) is preferably 50 mol % or less, and more preferably 30 mol % or less and 5 mol % or more.

[0134] [(II) Crosslinking Agent] (II) The crosslinking agent may be the same as that described in the first embodiment above.

[0135] [(III) Quencher] (III) The quencher may be the same as that described in the first embodiment above.

[0136] [(IV) Organic solvent] (IV) The organic solvent may be the same as that explained in the first embodiment above.

[0137] [(V) Component that decomposes upon exposure to actinic rays or radiation to generate an acid] The resist composition of the second aspect of the present invention may contain an additive-type photoacid generator as component (V), which may be the same as those described above for the first aspect.

[0138] [Surfactants] The resist material of the second aspect of the present invention may contain a surfactant, which may be the same as those described above in connection with the first aspect.

[0139] [Pattern formation method] When the positive resist material of the present invention is used in the manufacture of various integrated circuits, known lithography techniques can be applied. For example, the pattern formation method may be (i) applying the resist material onto a substrate to form a resist film; (ii) exposing the resist film to high-energy radiation; (iii) developing the exposed resist film using a developer; The method includes the steps of:

[0140] [Process (i)] First, the positive resist material 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., to a coating thickness of 0.01 to 2 μm. This is then prebaked on a hot plate for 30 seconds to 20 minutes to form a resist film. To efficiently promote the crosslinking reaction by the crosslinking agent, the prebaking temperature is preferably 130°C or higher.

[0141] [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 positive resist material of the present invention is particularly suitable for fine patterning using high-energy rays such as KrF excimer laser light, ArF excimer laser light, EB, EUV, X-rays, soft X-rays, γ-rays, and synchrotron radiation, and is particularly suitable for fine patterning using EB or EUV.

[0142] After exposure, PEB (post-exposure bake) 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. PEB is a heating step performed after the exposure of the resist film.

[0143] [Step (iii)] After exposure or PEB, the exposed resist film is developed using a developer, such as an aqueous alkaline solution of 0.1 to 10 mass %, preferably 2 to 5 mass %, of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetrabutylammonium hydroxide (TBAH), or the like, for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes, by a conventional method such as dipping, puddling, or spraying. The irradiated portions dissolve in the developer, while the unexposed portions do not, forming the desired positive pattern on the substrate.

[0144] The resist material can also be developed by organic solvent development.The developer used in this case includes 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, 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 can be used alone or in combination of two or more.

[0145] After the development is completed, the resist film is rinsed. A solvent that is miscible with the developer but does not dissolve the resist film is preferred as the rinse solution. Preferred examples of such solvents include alcohols having 3 to 10 carbon atoms, ether compounds having 8 to 12 carbon atoms, alkanes, alkenes, alkynes, and aromatic solvents having 6 to 12 carbon atoms.

[0146] Specific examples of alcohols having 3 to 10 carbon atoms include n-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-pentyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, and 3-hexanol. , 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol, 1-octanol, and the like.

[0147] 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.

[0148] Examples of alkanes having 6 to 12 carbon atoms include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, cyclononane, etc. Examples of alkenes having 6 to 12 carbon atoms include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, cyclooctene, etc. Examples of alkynes having 6 to 12 carbon atoms include hexyne, heptine, octyne, etc.

[0149] Examples of aromatic solvents include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, and mesitylene.

[0150] 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.

[0151] 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]

[0152] EXAMPLES The present invention will be specifically explained below using examples and comparative examples, but the present invention is not limited to these.

[0153] [Preparation and evaluation of resist materials] (1) Preparation of resist material Resist materials (Examples: R1 to R16, Comparative Examples: cR1 to cR18) were prepared by dissolving each component in a solvent containing 50 ppm of Omnova's PolyFox PF-636 surfactant at the compositions shown in Tables 1 and 2. The resulting solution was filtered through a 0.2 μm filter. The details of each resist material are shown in Tables 1 and 2.

[0154] The contents of each component in Tables 1 and 2 are as follows: Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) DAA (diacetone alcohol) EL (Ethyl lactate)

[0155] Base polymer: P-1 to P-11, cP-1, cP-2 [ka]

[0156] [ka]

[0157] Photoacid generators: PAG-1 to PAG-4 [ka]

[0158] Quencher: Q-1 to Q-8, cQ-1 to cQ-9 [ka]

[0159] [ka]

[0160] Crosslinking agents: X-1, X-2, X-3, X-4 [ka]

[0161] Thermal acid generator: T-1, T-2 [ka]

[0162] Other additives: A-1 [ka]

[0163] [Table 1]

[0164] [Table 2]

[0165] (2) Crosslinking Reactivity Evaluation (Examples 1-1 to 1-21, Comparative Examples 1-1 to 1-13) Resist materials R1 to R15 and cR3 to cR15 were spin-coated onto Si substrates and prebaked for 60 seconds using a hot plate to produce 50 nm thick resist films. The resist films were then peeled off from the substrate, dissolved in an organic solvent, and their polystyrene-equivalent weight-average molecular weights were measured by gel permeation chromatography (GPC) using dimethylformamide as the solvent. Resist films formed from R1 to R15 and cR3 to cR15 were subjected to a full-surface exposure of 1.0 mJ using a KrF exposure system (Nikon Corporation; S206D) followed by 60 seconds of PEB, and the molecular weights were also measured in the same manner. Table 3 shows the prebaking and PEB temperatures used to prepare the resist films of Examples 1-1 to 1-21, as well as the molecular weights after prebaking and PEB. Similar to Table 3, Table 4 shows the results of Comparative Examples 1-1 to 1-13.

[0166] (3) Dissolution contrast evaluation (Examples 2-1 to 2-20, Comparative Examples 2-1 to 2-13) Resist materials R1 to R15 and cR3 to cR15 were spin-coated onto an anti-reflective coating (DUV-42, manufactured by Nissan Chemical Co., Ltd.) with a thickness of 61 nm on an 8-inch wafer. The resist was then pre-baked for 60 seconds on a hot plate to form a 50 nm thick resist film. The resist was then exposed using a KrF exposure machine (Nikon Corporation; S206D), subjected to PEB for 60 seconds on a hot plate at 95°C, and developed for 30 seconds. Examples 2-1 to 2-19 were developed using a 2.38% by mass TMAH aqueous solution, and Example 2-20 was developed using butyl acetate. The resist film thickness after this development process was measured, and the relationship between exposure dose and resist film thickness after development was plotted to analyze the dissolution contrast. Furthermore, contrast was evaluated according to the following criteria, resulting in Examples 2-1 to 2-20 and Comparative Examples 2-1 to 2-13. A film thickness meter VM-2210 manufactured by Hitachi High-Tech Corporation was used to measure the film thickness. The results of Examples 2-1 to 2-20 are shown in Table 5, and the results of Comparative Examples 2-1 to 2-13 are shown in Table 6.

[0167] As representative compositions for the dissolution contrast evaluation, the contrast curves of the resist films of Example 2-5 and Comparative Example 2-1 are shown in Figure 1. The vertical axis in Figure 1 represents the film thickness after development normalized by the film thickness before development. The contrast values ​​in Table 5 represent the slope of the film thickness change with exposure dose, at the point where the solubility of the resist film in the developer changes rapidly. The contrast value is the slope, where the horizontal axis represents the logarithm of the exposure dose and the vertical axis represents the normalized film thickness, from the point where the film thickness becomes 80% or less of the initial film thickness until the film is completely dissolved. The contrast of the resist film formed from each resist composition was evaluated based on the absolute value of the contrast value as follows. (Judgment criteria) ◎: The absolute value of the contrast value is 10 or more ○: The absolute value of the contrast value is 5 or more and less than 10 ×: Absolute contrast value is less than 5

[0168] (4) Evaluation of storage stability (Examples 3-1 to 3-15, Comparative Examples 3-1 to 3-2) The resist materials listed in Tables 1 and 2 were stored at 40°C and 23°C for two weeks, and then spin-coated onto an anti-reflective coating (DUV-42, manufactured by Nissan Chemical Co., Ltd.) with a thickness of 61 nm on an 8-inch wafer. The wafer was pre-baked for 60 seconds using a hot plate to form a resist film with a thickness of approximately 50 nm. A film thickness meter VM-2210 manufactured by Hitachi High-Tech Corporation was used to measure the film thickness. The samples stored at 40°C and 23°C were evaluated under the same conditions, and the difference in film thickness was evaluated according to the following criteria. The results of Examples 3-1 to 3-15 are shown in Table 7, and the results of Comparative Examples 3-1 and 3-2 are shown in Table 8. (Judgment criteria) ○: Film thickness difference is less than 5 Å ×: Film thickness difference is 5 Å or more

[0169] (5) Lithography Evaluation (Examples 4-1 to 4-15, Comparative Examples 4-1 to 4-13) Resist materials R1 to R15 and cR3 to cR15 listed in Tables 1 and 2 were spin-coated onto a 61-nm-thick anti-reflective coating (DUV-42, manufactured by Nissan Chemical Co., Ltd.) on an 8-inch wafer. The coating was then prebaked for 60 seconds on a hot plate to produce a resist film with a thickness of approximately 50 nm. This resist film was exposed using an electron beam lithography system (ELS-F125, accelerating voltage 125 kV) manufactured by Elionix, subjected to PEB for 60 seconds at 95°C on a hot plate, and developed for 30 seconds in a 2.38% by weight aqueous TMAH solution. The developed patterns were observed using a critical dimension scanning electron microscope (S9380, manufactured by Hitachi High-Technologies Corporation). The standard deviation (σ) calculated from the results was tripled (3σ) to determine the pattern width variation (LWR). Furthermore, the pattern width variation was evaluated based on the following criteria. The results of Examples 4-1 to 4-15 are shown in Table 9, and the results of Comparative Examples 4-1 to 4-13 are shown in Table 10. (Judgment criteria) ◎: LWR value is less than 3.0 ○: LWR value is 3.0 or more and less than 4.0 ×: LWR value is 4.0 or more

[0170] [Table 3]

[0171]

Table 4

[0172]

Table 5

[0173]

Table 6

[0174]

Table 7

[0175]

Table 8

[0176]

Table 9

[0177]

Table 10

[0178] As shown in Tables 3 and 4, in Examples 1-1 to 1-21 containing a vinyl ether crosslinker, the average molecular weight increased after prebaking, suggesting the progress of the crosslinking reaction. Furthermore, a further increase in molecular weight was observed after short exposure and PEB, confirming that the weak acid derived from the quencher (Q-1 to Q-8) acted as a catalyst to promote the crosslinking reaction. In Example 1-18, the resist film after short exposure and PEB was found to be sufficiently crosslinked to be insoluble in GPC solvents. On the other hand, no increase in molecular weight was observed after short exposure and PEB in resists containing a carboxylate-type quencher or a nitrogen-containing quencher. On the other hand, in resists containing a sulfonate-type quencher, the molecular weight after short exposure and PEB was lower than that after prebaking. This is due to the decomposition of the acetal crosslinked structure formed during the prebaking process by sulfonic acid. It was revealed that the acidity of the quencher is important for promoting the crosslinking reaction.

[0179] As shown in Figure 1, Example 2-5 exhibited a significant difference in solubility between the exposed and unexposed regions compared to Comparative Example 2-1, confirming a steeper change in film thickness after development relative to the exposure dose. The contrast values ​​in Tables 5 and 6 represent the slope of this film thickness change, with larger absolute values ​​indicating better dissolution contrast. All of Example Groups 2-1 to 2-20, which contained a polymer with a reactive group, a crosslinker, and a fluorocarboxylate-type quencher, exhibited good contrast. This is believed to be due to the acid generated in the weakly exposed areas from the quencher promoting the crosslinking reaction. Furthermore, it was revealed that resist compositions containing a structural unit (C) that generates acid under light exposure in the base polymer exhibited particularly excellent contrast. Because the structural unit (C) is highly polar and hydrophilic, uncrosslinked low-molecular-weight compounds containing (C) have high developer solubility. On the other hand, increasing the molecular weight of such readily soluble components by crosslinking significantly reduces developer solubility. Because this effect can significantly change the dissolution contrast between the exposed and unexposed areas, it is preferable for the base polymer to contain the structural unit (C).

[0180] Resist films made using resist compositions cR1 and cR2, which did not contain a photoacid generator but contained a trace amount of acid A-1 as a crosslinking accelerator, showed a significant increase in film thickness during long-term storage, as shown in Comparative Examples 3-1 and 3-2 in Table 8. This is thought to be due to the fact that Comparative Examples 3-1 and 3-2 contain acid A-1 as a crosslinking accelerator, and the crosslinking reaction progressed during storage as a solution, resulting in a polymer with a high molecular weight. Therefore, resist materials that do not contain structural unit (C) or a photoacid generator were shown to have poor storage stability.

[0181] All of Examples 4-1 to 4-15, which contained a polymer having a reactive group, a crosslinking agent, and a fluorocarboxylate-type quencher, exhibited good LWR. Furthermore, the resist composition having a structural unit (C) that generates acid when exposed to light in the base polymer exhibited particularly excellent LWR.

[0182] The above results demonstrate that the resist material of the present invention has high dissolution contrast and good LWR, and therefore has small edge roughness and dimensional variation, excellent resolution, good pattern shape after exposure, and good storage stability.

[0183] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention.

Claims

1. A resist material, (Ia) a polymer containing a repeating unit (A) containing a hydroxyl group or a carboxyl group; (II) a crosslinking agent having a structure represented by the following formula (1): (III) A quencher having a structure represented by the following formula (2), wherein R 31 in the formula (2) contains an iodine atom, or the anion moiety in the formula (2) is any one of those represented by the following formula (T): (IV) an organic solvent; (V) a component that decomposes upon irradiation with actinic rays or radiation to generate an acid; A resist material comprising: 【Chemical 1】 [In the formula, R represents an n-valent organic group which may have a substituent. L １ is a linking group selected from a single bond, an ester bond, and an ether bond. R １ represents a single bond or a divalent organic group, and n represents an integer of 1 to 4. 【Chemistry 2】 [In the formula, R ３１ R is a monovalent organic group which may have a substituent. ３３ ~R ３５ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. ３３ , R ３４ and R ３５ Any two of these may be bonded to each other to form a ring together with the sulfur atom to which they are attached. 【Chemistry 3】

2. A resist material, (Ib) a polymer containing a repeating unit (A) containing a hydroxyl group or a carboxyl group and a repeating unit (C) having a structural moiety that decomposes upon irradiation with actinic rays or radiation to generate an acid; (II) a crosslinking agent having a structure represented by the following formula (1): (III) A quencher having a structure represented by the following formula (2), wherein R 31 in the formula (2) contains an iodine atom, or the anion moiety in the formula (2) is any one of those represented by the following formula (T): (IV) an organic solvent; A resist material comprising: 【Chemistry 4】 [In the formula, R represents an n-valent organic group which may have a substituent. L １ is a linking group selected from a single bond, an ester bond, and an ether bond. R １ represents a single bond or a divalent organic group, and n represents an integer of 1 to 4. 【Chemistry 5】 [In the formula, R ３１ R is a monovalent organic group which may have a substituent. ３３ ~R ３５ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. ３３ , R ３４ and R ３５ Any two of these may be bonded to each other to form a ring together with the sulfur atom to which they are attached. 【Chemistry 6】

3. 3. The resist material according to claim 2, wherein the repeating unit (C) contained in the polymer is represented by the following formula (c): 【Chemistry 7】 [In the formula, R ｃ１ is a hydrogen atom or a methyl group. Z １ is a single bond or an ester bond. ２ is a single bond or a divalent organic group having 1 to 25 carbon atoms, and may contain one or more of an ester bond, an ether bond, a lactone ring, an amide bond, a sultone ring, and an iodine atom. Rf ｃ１ ~Rf ｃ４ 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 ｃ２ ~R ｃ４ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, and R ｃ２ , R ｃ３ and R ｃ４ Any two of these may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

4. 4. The resist material according to claim 2, further comprising (V) a component that decomposes upon irradiation with actinic rays or radiation to generate an acid.

5. 5. The resist material according to claim 1, wherein the repeating unit (A) contained in the polymer is represented by the following formula (a1) and / or (a2): 【Chemistry 8】 [In the formula, R Ａ are each independently a hydrogen atom or a methyl group. ａ１ are each independently a single bond or a divalent linking group having 1 to 15 carbon atoms and at least one of a phenylene group, a naphthylene group, an ester bond, an ether bond, a lactone ring, an amide group, and a hetero atom. ａ２ R are each independently a single bond or a divalent linking group having 1 to 12 carbon atoms and at least one of a phenylene group, a naphthylene group, an ester bond, an ether bond, a lactone ring, an amide group, and a hetero atom. ａ１ is a hydrogen atom, a fluorine atom, or an alkyl group, and R ａ１ and Y ａ２ may be bonded to form a ring. k is 1 or 2, l is an integer of 0 to 4, and 1≦k+l≦5. m is 0 or 1.

6. 6. The resist material according to claim 1, wherein R in formula (1) contains an aromatic hydrocarbon group.

7. A pattern formation method, comprising: (i) applying the resist material according to any one of claims 1 to 6 onto a substrate to form a resist film; (ii) exposing the resist film to high-energy radiation; (iii) developing the exposed resist film using a developer; A pattern forming method comprising the steps of:

8. 8. The pattern formation method according to claim 7, wherein the step (i) further comprises a step of pre-baking the resist film at 130[deg.] C. or higher.

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