Chemically amplified resist composition and pattern forming method

Abstract

To provide a chemically amplified resist composition that offers high sensitivity and high contrast, improved line width roughness (LWR) and critical dimension uniformity (CDU) of holes, and excellent etch resistance after patterning, as well as to provide a patterning method using the same.SOLUTION: A chemically amplified resist composition comprises (A) a polymer, which exhibits increased solubility in alkaline solutions due to the action of acid, comprising a repeating unit represented by formula (A1) and a specific repeating unit having phenol, excluding a repeating unit that generates acid due to exposure to light; and a specific photoacid generator that generates sulfonic acid due to the action of KrF and ArF excimer lasers, electron beams, or extreme ultraviolet radiation.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] In recent years, the increasing integration density of integrated circuits has led to a demand for finer pattern formation, and chemically amplified resist compositions using acid as a catalyst are now being used exclusively for processing patterns of 0.2 μm or less. High-energy beams such as ultraviolet light, far ultraviolet light, and electron beams (EB) are used as exposure sources, and EB lithography, which is used as an ultrafine processing technology, is also indispensable as a method for processing photomask blanks when producing photomasks for semiconductor manufacturing.

[0003] Polymers containing a large amount of aromatic skeletons with acidic side chains, such as polyhydroxystyrene, have been useful as materials for resist compositions for KrF lithography using KrF excimer lasers, but have not been used as materials for resist compositions for ArF lithography using ArF excimer lasers because they exhibit high absorption of light with wavelengths around 200 nm. However, they are important materials for resist compositions for EB lithography and extreme ultraviolet (EUV) lithography, which are effective techniques for forming patterns smaller than the processing limit of ArF excimer lasers, because they provide high etching resistance.

[0004] The base polymers used in positive-tone resist compositions for EB lithography and EUV lithography are typically made of materials that, upon exposure to high-energy radiation, use an acid generated from a photoacid generator as a catalyst to deprotect the acid-labile protecting groups (acid-labile groups) that mask the acidic functional groups on the phenol side chains of the base polymer, rendering the polymer soluble in an alkaline developer. Examples of the acid-labile protecting groups typically used include tertiary alkyl groups, tert-butoxycarbonyl groups, and acetal groups. While using a protecting group such as an acetal group, which requires a relatively low activation energy for deprotection, offers the advantage of producing highly sensitive resist films, insufficient suppression of the diffusion of the generated acid can lead to deprotection reactions even in unexposed areas of the resist film, resulting in problems such as poor line edge roughness (LWR) and poor dimensional uniformity (CDU) of the hole pattern.

[0005] Various improvements have been made to resist sensitivity and pattern profile control by selecting and combining materials used in resist compositions, process conditions, etc. One of the areas of improvement is acid diffusion, which has a significant impact on the resolution of chemically amplified resist compositions. Because acid diffusion has a significant impact on sensitivity and resolution, it has been the subject of extensive research.

[0006] Furthermore, in order to improve sensitivity, attempts have been made to introduce multiple bonds or aromatic rings into the acid labile groups of the base polymer of the resist composition. Although the introduction of these substituents has resulted in some improvement in performance, satisfactory results have yet to be obtained (Patent Documents 1 to 11). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-191262 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-53196 [Patent Document 3] Japanese Patent Application Publication No. 2018-92159 [Patent Document 4] Japanese Patent Application Laid-Open No. 2008-268741 [Patent Document 5] Japanese Patent Application Publication No. 2019-120759 [Patent Document 6] Japanese Patent Publication No. 2020-085917 [Patent Document 7] Patent No. 6782569 [Patent Document 8] Japanese Patent Application Publication No. 2019-214554 [Patent Document 9] Patent Publication No. 2021-50307 [Patent Document 10] Japanese Patent Publication No. 2022-100187 [Patent Document 11] Japanese Patent Publication No. 2022-100188 Summary of the Invention [Problem to be solved by the invention]

[0008] There is a need for the development of an acid-catalyzed chemically amplified resist composition that has high sensitivity and high contrast, is capable of improving line line write (LWR) and hole CDU, and also has excellent etching resistance after pattern formation.

[0009] The present invention has been made in view of the above circumstances, and aims to provide a chemically amplified resist composition that has high sensitivity and high contrast, improved line line write (LWR) and hole CDU (Continuously Durable Output) and also has excellent etching resistance after pattern formation, particularly in photolithography using EB or EUV with a wavelength of 13.5 nm, and a pattern formation method using the same. [Means for solving the problem]

[0010] As a result of extensive research to achieve the above object, the present inventors have found that by using a polymer containing a repeating unit having an acid labile group containing an aromatic triple bond and a repeating unit having a phenolic hydroxy group, and a photoacid generator having a specific structure, it is possible to obtain a chemically amplified resist composition that has high sensitivity and high contrast, improved line line write (LWR) and hole CDU (Continuous Durability) and also has excellent etching resistance after pattern formation, and have completed the present invention.

[0011] That is, the present invention provides the following chemically amplified resist composition and pattern forming method. 1. (A) A polymer whose solubility in an alkaline aqueous solution increases under the action of an acid, the polymer comprising a repeating unit represented by the following formula (A1) and a repeating unit represented by the following formula (B1), and not comprising a repeating unit that generates an acid upon exposure to light; and (B) A photoacid generator represented by the following formula (PAG-a) or (PAG-b), which generates an acid when exposed to KrF excimer laser light, ArF excimer laser light, electron beams, or extreme ultraviolet light: A chemically amplified resist composition comprising: [ka] (In the formula, a1 is 0 or 1, and a2 is an integer of 0 to 3. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX 11 -X 11 is a saturated hydrocarbylene group having 1 to 10 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond, a sulfide bond, a sulfonamide bond, a lactone ring or a sultone ring, or a phenylene group or naphthylene group. * represents a bond to a carbon atom in the main chain. R a1 and R a2 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, and Ra1 and R a2 cannot be hydrogen atoms at the same time. a1 and R a2 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R a3 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. When a2 ≥ 2, multiple R a3 may be bonded to each other to form a ring together with the carbon atoms to which they are attached.) [ka] (In the formula, b1 is an integer of 1 to 4, and b2 is an integer of 0 to 3, provided that 1≦b1+b2≦5. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 2 is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain. R b1 is a halogen atom, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. b1 may be bonded to each other to form a ring together with the carbon atoms to which they are attached.) [ka] (In the formula, R 0 represents a hydrogen atom or a hydrocarbyl group having 1 to 50 carbon atoms, and some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with halogen atoms, and some of the -CH2- groups of the hydrocarbyl group may be substituted with -O- or -C(=O)-. Xa +is an organic cation. [ka] (In the formula, R 1 and R 2 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 1 and R 2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. R 3 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. L A is a divalent linking group. L B is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 2.Xa + is an onium cation represented by the following formula (Xa-1) or (Xa-2): [ka] (In the formula, R 11 ~R 15 are each independently a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. 11 and R 12 and may be bonded to each other to form a ring together with the sulfur atom to which they are attached. 3. The chemically amplified resist composition of 1 or 2, wherein the polymer further contains a repeating unit represented by the following formula (a1) or (a2): [ka] (In the formula, R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y 1 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OY 11 -It is. Y 11is a saturated hydrocarbylene group having 1 to 10 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond or a lactone ring, or a phenylene group or a naphthylene group. Y 2 is a single bond or *-C(=O)-O-. * indicates a bond to a carbon atom in the main chain. AL 1 and AL 2 are each independently an acid labile group having no triple bond. R a4 is a halogen atom, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. a4 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. c is an integer from 0 to 4. 4. The chemically amplified resist composition according to any one of 1 to 3, wherein the polymer further contains a repeating unit represented by the following formula (C1): [ka] (In the formula, R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Z 1 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OZ 11 -It is. Z 11 is a saturated hydrocarbylene group having 1 to 10 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond or a lactone ring, or a phenylene group or naphthylene group. * represents a bond to a carbon atom in the main chain. R c1is a group having 1 to 20 carbon atoms and containing at least one structure selected from a hydrogen atom, a hydroxy group other than a phenolic hydroxy group, a cyano group, a carbonyl group, a carboxy group, an ether bond, an ester bond, a sulfonate ester bond, a sulfonamide bond, a carbonate bond, a lactone ring, a sultone ring, a sulfur atom, and a carboxylic anhydride (-C(=O)-OC(=O)-). 5. The chemically amplified resist composition according to any one of 1 to 4, further comprising an organic solvent. 6. The chemically amplified resist composition according to any one of 1 to 5, further comprising a quencher. 7. The chemically amplified resist composition according to any one of 1 to 6, further comprising a surfactant. 8. A pattern formation method comprising the steps of: forming a resist film on a substrate using any one of the chemically amplified resist compositions according to 1 to 7; exposing the resist film to KrF excimer laser light, ArF excimer laser light, electron beams, or extreme ultraviolet light having a wavelength of 3 to 15 nm; and developing the exposed resist film using a developer. [Effects of the Invention]

[0012] By using a polymer containing a repeating unit having an acid labile group containing an aromatic triple bond and a repeating unit having a phenolic hydroxy group, and a photoacid generator having a specific structure, it is possible to construct a chemically amplified resist composition that has high sensitivity and high contrast, improves line LWR and hole CDU, and also has excellent etching resistance after pattern formation. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Chemically amplified resist composition] The chemically amplified resist composition of the present invention comprises: (A) a polymer whose solubility in an aqueous alkaline solution increases under the action of an acid, the polymer not containing a repeating unit that generates an acid upon exposure, but containing a repeating unit having an acid labile group containing an aromatic triple bond and a repeating unit having a phenolic hydroxy group; and (B) a photoacid generator having a specific structure.

[0014] [(A) Polymer] The repeating unit having an acid labile group containing an aromatic triple bond contained in the polymer of component (A) (hereinafter also referred to as repeating unit A) is preferably represented by the following formula (A1). [ka]

[0015] In formula (A1), a1 is 0 or 1. When a1 is 0, it is a benzene ring, and when a1 is 1, it is a naphthalene ring, but from the viewpoint of solvent solubility, it is preferable that a1 is 0 and is a benzene ring. a2 is an integer of 0 to 3.

[0016] In formula (A1), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0017] In formula (A1), X 1 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX 11 -X 11 is a saturated hydrocarbylene group having 1 to 10 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond, a sulfide bond, a sulfonamide bond, a lactone ring or a sultone ring, or a phenylene group or naphthylene group. * represents a bond to a carbon atom in the main chain.

[0018] X 11The saturated hydrocarbylene group represented by the formula (I) 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-1,1-diyl group, a propane-1,2-diyl group, a propane-1,3-diyl group, a propane-2,2-diyl group, a butane-1,1-diyl group, a butane-1,2-diyl group, a butane-1,3-diyl group, a butane-2,3-diyl group, a butane-1,4-diyl group, a 1,1-dimethylethane-1,2-diyl group, a pentane-1,5-diyl group, a 2-methylbutane-1,2-diyl group, a alkanediyl groups having 1 to 10 carbon atoms, such as 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; cycloalkanediyl groups having 3 to 10 carbon atoms, such as cyclopropanediyl group, cyclobutane-1,1-diyl group, cyclobutanediyl group, cyclopentanediyl group, and cyclohexanediyl group; polycyclic saturated hydrocarbylene groups having 4 to 10 carbon atoms, such as adamantanediyl group and norbornanediyl group; and divalent groups obtained by combining these groups.

[0019] X in formula (A1) 1 Examples of structures in which R is changed include, but are not limited to, those shown below. A is the same as above, and the dashed line represents R in formula (A1). a1 and R a2 represents the bond to the carbon atom to which it is bonded. [ka]

[0020] [ka]

[0021] [ka]

[0022] [ka]

[0023] In formula (A1), R a1 and R a2 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, and R a1 and R a2 cannot be hydrogen atoms at the same time. a1 and R a2 and may be bonded to each other to form a ring together with the carbon atoms to which they are bonded. Examples of the ring include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, and an adamantane ring. Of these, a cyclopentane ring and a cyclohexane ring are preferred.

[0024] In formula (A1), R a3 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. When a2 ≥ 2, multiple R a3 may be bonded to each other to form a ring together with the carbon atoms to which they are attached.

[0025] R a1 , R a2 and R a3The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl; saturated cyclic hydrocarbyl groups having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups having 2 to 20 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl; unsaturated cyclic hydrocarbyl groups having 3 to 20 carbon atoms, such as cyclohexenyl; aryl groups having 2 to 20 carbon atoms, such as phenyl and naphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl; and groups obtained by combining these groups. Of these, aryl groups are preferred. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, 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.

[0026] Specific examples of the repeating unit A include, but are not limited to, those shown below. A is the same as above. [ka]

[0027] [ka]

[0028] [ka]

[0029] [ka]

[0030] [ka]

[0031] [ka]

[0032] The repeating unit having a phenolic hydroxy group contained in the polymer of component (A) (hereinafter also referred to as repeating unit B) is preferably one represented by the following formula (B1). [ka]

[0033] In formula (B1), b1 is an integer of 1 to 4, and b2 is an integer of 0 to 3, provided that 1≦b1+b2≦5.

[0034] In formula (B1), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0035] In formula (B1), X 2 is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain.

[0036] In formula (B1), R b1is a halogen atom, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. b1 may be bonded to each other to form a ring together with the carbon atoms to which they are attached.

[0037] R b1 The hydrocarbyl group represented by the formula (A1) and the hydrocarbyl moiety of the hydrocarbyloxy group, hydrocarbylcarbonyl group, hydrocarbylcarbonyloxy group and hydrocarbyloxycarbonyl group may be saturated or unsaturated, and may be linear, branched or cyclic. a1 , R a2 and R a3 Examples of the above-mentioned examples are the same as those given in the explanation of the above.

[0038] Specific examples of the repeating unit B include, but are not limited to, those shown below. A is the same as above. [ka]

[0039] [ka]

[0040] [ka]

[0041] The polymer of the present invention is characterized by comprising repeating units A and B each having an acid-labile group containing an aromatic triple bond. Upon exposure, secondary electrons are generated from repeating unit B, and the secondary electrons are transmitted to the cation of the photoacid generator, decomposing the sulfonium or iodonium cation and generating the corresponding acid. The generated acid acts on the acid-labile group attached to the polymer backbone, promoting a deprotection reaction in the exposed area. Furthermore, repeating unit A forms a stable conjugated ene-yne ​​after the elimination reaction. Furthermore, the aromatic ring attached to the triple bond further extends the conjugation, enhancing acid elimination reactivity. This results in a high solubility contrast in a developer and improved sensitivity of the resist film. Furthermore, triple bonds have a smaller excluded volume than single or double bonds, making them advantageous for forming fine patterns. Furthermore, the terminal aromatic rings are thought to be regularly arranged within and between the main chains due to a stacking effect (π-π stacking), which increases the glass transition temperature (Tg) of the polymer and enables the formation of patterns with excellent etching resistance. In addition, conjugated triple bonds and aromatic rings have high electron density, and are pseudo-δ - This is thought to electrostatically repel hydroxide ions in the alkaline developer. This reduces swelling in unexposed areas due to the alkaline developer, suppressing pattern collapse. Meanwhile, JP 2021-50307 A describes a polymer containing repeating units with triple-bond-containing acid-labile groups, repeating units with phenolic hydroxy groups, and repeating units that generate acid upon exposure. However, the introduction of these units increases the ionic nature of the polymer, making it easier for the alkaline developer to be attracted to unexposed areas. Furthermore, the stacking effect within and between the main chains is inhibited, potentially resulting in impaired pattern collapse and etching resistance. Therefore, resist compositions using the polymers of the present invention exhibit high sensitivity and high dissolution contrast, excellent CDU in hole patterns and LWR in line patterns, and excellent pattern collapse suppression and etching resistance, making them suitable for fine pattern formation.

[0042] The polymer of component (A) may further contain at least one repeating unit selected from the repeating units represented by the following formulas (a1) (hereinafter also referred to as repeating unit a1) and (a2) (hereinafter also referred to as repeating unit a2): [ka]

[0043] In formulas (a1) and (a2), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OY 11 -It is. Y 11 Y is a saturated hydrocarbylene group having 1 to 10 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond or a lactone ring, or a phenylene group or a naphthylene group. 2 is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain. AL 1 and AL 2 R is each independently an acid labile group having no triple bond. a4 is a halogen atom, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. a4 may be bonded to each other to form a ring together with the carbon atoms to which they are bonded. c is an integer of 0 to 4.

[0044] In the formulas (a1) and (a2), AL 1 and AL 2 Examples of acid labile groups having no triple bond and represented by the formula (I) include those described in JP-A Nos. 2013-80033 and 2013-83821.

[0045] Typical examples of the acid labile group include those represented by the following formulae (AL-1) to (AL-3). [ka] (In the formula, the dashed lines represent bonds.)

[0046] In formulas (AL-1) and (AL-2), R L1 and R L2 are each independently a saturated hydrocarbyl group having 1 to 40 carbon atoms, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The saturated hydrocarbyl group may be linear, branched, or cyclic. The saturated hydrocarbyl group preferably has 1 to 20 carbon atoms.

[0047] In formula (AL-1), d is an integer of 0 to 10, and an integer of 1 to 5 is preferable.

[0048] In formula (AL-2), R L3 and R L4 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 20 carbon atoms, and may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The hydrocarbyl group may be linear, branched, or cyclic. L2 , R L3 and R L4 Any two of these may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom or the carbon atom and oxygen atom to which they are bonded. As the ring, a ring having 4 to 16 carbon atoms is preferred, and an alicyclic ring is particularly preferred.

[0049] In formula (AL-3), R L5 , R L6 and R L7 are each independently a saturated hydrocarbyl group having 1 to 20 carbon atoms, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The hydrocarbyl group may be linear, branched, or cyclic. L5 , R L6and R L7 Any two of these may be bonded to each other together with the carbon atoms to which they are bonded to form a ring having 3 to 20 carbon atoms. As the ring, a ring having 4 to 16 carbon atoms is preferred, and an alicyclic ring is particularly preferred.

[0050] Specific examples of the repeating unit a1 include, but are not limited to, the following: A and AL 1 is the same as above. [ka]

[0051] [ka]

[0052] [ka]

[0053] [ka]

[0054] Specific examples of the repeating unit a2 include, but are not limited to, the following: A and AL 2 is the same as above. [ka]

[0055] [ka]

[0056] The polymer of component (A) may further contain a repeating unit represented by the following formula (C1) (hereinafter also referred to as repeating unit C). [ka]

[0057] In formula (C1), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OZ 11 -It is. Z 11 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, which may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring, or a phenylene group or naphthylene group. * represents a bond to a carbon atom in the main chain. R c1 is a group having 1 to 20 carbon atoms and containing at least one structure selected from a hydrogen atom, a hydroxy group other than a phenolic hydroxy group, a cyano group, a carbonyl group, a carboxy group, an ether bond, an ester bond, a sulfonate ester bond, a sulfonamide bond, a carbonate bond, a lactone ring, a sultone ring, a sulfur atom, and a carboxylic anhydride (-C(=O)-OC(=O)-).

[0058] Specific examples of the repeating unit C include, but are not limited to, those shown below. A is the same as above. [ka]

[0059] [ka]

[0060] [ka]

[0061] [ka]

[0062]

change

[0063]

change

[0064]

change

[0065]

change

[0066]

change

[0067]

change

[0068]

change

[0069]

change

[0070]

change

[0071]

change

[0072]

change

[0073] [Chemical formula]

[0074] The polymer of component (A) may further contain a repeating unit D derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene or derivatives thereof. Specific examples of the monomers that give the repeating unit D include, but are not limited to, those shown below. [Chemical formula]

[0075] The polymer of component (A) may further contain a repeating unit E derived from indane, vinylpyridine or vinylcarbazole.

[0076] In the polymer, the content ratios of the repeating units A, a1, a2, B, C, D and E are preferably 0 < A < 1.0, 0 ≤ a1 ≤ 0.8, 0 ≤ a2 ≤ 0.8, 0 ≤ a1 + a2 ≤ 0.8, 0 < B < 1.0, 0 ≤ C < 1.0, 0 ≤ D ≤ 0.8 and 0 ≤ E ≤ 0.4, more preferably 0.05 ≤ A ≤ 0.9, 0 ≤ a1 ≤ 0.7, 0 ≤ a2 ≤ 0.7, 0 ≤ a1 + a2 ≤ 0.7, 0.01 ≤ B ≤ 0.7, 0.0 ≤ C ≤ 0.55, 0 ≤ D ≤ 0.7 and 0 ≤ E ≤ 0.3, and still more preferably 0.1 ≤ A ≤ 0.8, 0 ≤ a1 ≤ 0.6, 0 ≤ a2 ≤ 0.6, 0 ≤ a1 + a2 ≤ 0.6, 0.05 ≤ B ≤ 0.6, 0 ≤ C ≤ 0.5, 0 ≤ D ≤ 0.5 and 0 ≤ E ≤ 0.2.

[0077] The weight-average molecular weight (Mw) of the polymer is preferably 1,000 to 500,000, more preferably 3,000 to 100,000. When Mw is within this range, sufficient etching resistance is obtained, and there is no risk of a decrease in resolution due to an inability to ensure a difference in dissolution rate before and after exposure. In the present invention, Mw is a value measured in terms of polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran (THF) or N,N-dimethylformamide (DMF) as a solvent.

[0078] Furthermore, since the influence of Mw / Mn on the molecular weight distribution of the polymer tends to become greater as the pattern rule becomes finer, in order to obtain a resist composition that is suitable for use with fine pattern dimensions, it is preferable that Mw / Mn be a narrow dispersity of 1.0 to 2.0. If it is within this range, there will be little low-molecular-weight or high-molecular-weight polymer, and there will be no risk of foreign matter being observed on the pattern or deterioration of the pattern shape after exposure.

[0079] The polymer can be synthesized, for example, by polymerizing a monomer that provides the repeating unit described above in an organic solvent with the addition of a radical polymerization initiator by heating.

[0080] Examples of organic solvents used during polymerization include toluene, benzene, THF, diethyl ether, dioxane, cyclohexane, cyclopentane, methyl ethyl ketone (MEK), propylene glycol monomethyl ether acetate (PGMEA), and γ-butyrolactone (GBL). Examples of the polymerization initiator include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), 1,1'-azobis(1-acetoxy-1-phenylethane), benzoyl peroxide, and lauroyl peroxide. The amount of these initiators added is preferably 0.01 to 25 mol% based on the total amount of monomers to be polymerized. The reaction temperature is preferably 50 to 150°C, more preferably 60 to 100°C. The reaction time is preferably 2 to 24 hours, and more preferably 2 to 12 hours from the viewpoint of production efficiency.

[0081] The polymerization initiator may be added to the monomer solution and then fed to the reaction vessel. Alternatively, an initiator solution may be prepared separately from the monomer solution and then fed to the reaction vessel independently. From the perspective of quality control, it is preferable to prepare the monomer solution and the initiator solution independently and then add them dropwise, since radicals generated from the initiator during the waiting time may cause the polymerization reaction to proceed, resulting in the formation of ultra-high molecular weight polymers. The acid labile group may be used as is after being introduced into the monomer, or may be protected or partially protected after polymerization. Furthermore, known chain transfer agents such as dodecyl mercaptan and 2-mercaptoethanol may be used in combination to adjust the molecular weight. In this case, the amount of the chain transfer agent added is preferably 0.01 to 20 mol % of the total amount of monomers to be polymerized.

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

[0083] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, hydroxystyrene or hydroxyvinylnaphthalene and other monomers may be polymerized by heating in an organic solvent with the addition of a radical polymerization initiator. Alternatively, acetoxystyrene or acetoxyvinylnaphthalene may be used, and after polymerization, the acetoxy group may be deprotected by alkaline hydrolysis to form polyhydroxystyrene or hydroxypolyvinylnaphthalene.

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

[0085] The amount of each monomer in the monomer solution may be appropriately set so as to achieve the preferred content ratio of the repeating units described above.

[0086] The polymer obtained by the above-described production method may be a reaction solution obtained by a polymerization reaction as a final product, or a powder obtained through a purification step such as a reprecipitation method in which a polymerization solution is added to a poor solvent to obtain a powder, and the resulting powder may be handled as a final product. However, from the viewpoint of work efficiency and quality stability, it is preferable to handle a polymer solution obtained by dissolving the powder obtained through the purification step in a solvent as a final product.

[0087] Specific examples of the solvent used in this case include ketones such as cyclohexanone and methyl-2-n-pentyl ketone, as described in paragraphs

[0144] to

[0145] of JP-A No. 2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; propylene glycol monomethyl ether (PGME), ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether. esters such as PGMEA, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol mono tert-butyl ether acetate; lactones such as GBL; alcohols such as diacetone alcohol (DAA); high-boiling alcohol solvents such as diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, and 1,3-butanediol; and mixed solvents thereof.

[0088] The concentration of the polymer in the polymer solution is preferably 0.01 to 30% by mass, more preferably 0.1 to 20% by mass.

[0089] The reaction solution and polymer solution are preferably filtered through a filter, which is effective in stabilizing quality by removing foreign matter and gels that may cause defects.

[0090] Examples of filter materials used in the filter filtration include fluorocarbon, cellulose, nylon, polyester, and hydrocarbon-based materials. However, in the filtration process of resist compositions, filters made of fluorocarbons, such as Teflon (registered trademark), hydrocarbons such as polyethylene and polypropylene, or nylon are preferred. The pore size of the filter can be selected appropriately depending on the target cleanliness, but is preferably 100 nm or less, more preferably 20 nm or less. These filters may be used alone or in combination. The filtration method may involve passing the solution through the filter only once, but it is more preferable to circulate the solution and filter it multiple times. The filtration process can be performed in any order and any number of times in the polymer production process. However, it is preferable to filter the reaction solution after the polymerization reaction, the polymer solution, or both.

[0091] The polymer may include two or more polymers having different composition ratios, Mw, or Mw / Mn.

[0092] [(B) Photoacid generator] The photoacid generator of component (B) is a compound (photoacid generator) represented by the following formula (PAG-a) or (PAG-b) that generates acid when exposed to KrF excimer laser light, ArF excimer laser light, EB, or EUV. [ka]

[0093] In formula (PAG-a), R 0 represents a hydrogen atom or a hydrocarbyl group having 1 to 50 carbon atoms, and some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with halogen atoms, and some of the -CH2- groups of the hydrocarbyl group may be substituted with -O- or -C(=O)-. + is an organic cation.

[0094] [ka]

[0095] In formula (PAG-b), R 1 and R 2 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 1 and R 2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. 3 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. A is a divalent linking group. B is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms which may contain a hetero atom.

[0096] R in formula (PAG-a) 0The 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 50 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl; saturated cyclic hydrocarbyl groups having 3 to 50 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups having 2 to 50 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl; unsaturated cyclic hydrocarbyl groups having 3 to 50 carbon atoms, such as cyclohexenyl; aryl groups having 6 to 50 carbon atoms, such as phenyl and naphthyl; aralkyl groups having 7 to 50 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl; hydrocarbyl groups having a steroid skeleton and having 20 to 38 carbon atoms, which may contain a heteroatom; 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.

[0097] Specific examples of the anion of the photoacid generator represented by formula (PAG-a) include, but are not limited to, those shown below. [ka]

[0098] [ka]

[0099] [ka]

[0100] Xa in formula (PAG-a) + The organic cation represented by the formula (Xa-1) is preferably a sulfonium cation represented by the formula (Xa-1) below or an iodonium cation represented by the formula (Xa-2) below. [ka]

[0101] In formulas (Xa-1) and (Xa-2), R 11 ~R 15 R are each independently a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. 11 ~R 15 may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 30 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a tert-pentyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, and an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, and a tricyclo[5.2.1.0] 2,6] cyclic saturated hydrocarbyl groups having 3 to 30 carbon atoms, such as a decyl group, an adamantyl group, or an adamantylmethyl group; aryl groups having 6 to 30 carbon atoms, such as a phenyl group, a naphthyl group, or an anthracenyl group; and groups obtained by combining these. In addition, some or all of the hydrogen atoms in the hydrocarbyl groups may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, or halogen atoms, and some of the -CH2- groups in the hydrocarbyl groups may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, or nitrogen atoms, so that the hydrocarbyl groups may contain hydroxy groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonate ester bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic anhydrides (-C(=O)-OC(=O)-), haloalkyl groups, or the like.

[0102] Also, R 11 and R 12 and may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, examples of the sulfonium cation represented by formula (Xa-1) include those represented by the following formulas: [ka] (In the formula, the dashed lines represent bonds.)

[0103] Specific examples of the sulfonium cation represented by formula (Xa-1) include, but are not limited to, the following: [ka]

[0104] [ka]

[0105] [ka]

[0106]

change

[0107]

change

[0108]

change

[0109]

change

[0110]

change

[0111]

change

[0112]

change

[0113]

change

[0114]

change

[0115]

change

[0116]

change

[0117]

change

[0118]

change

[0119]

change

[0120]

change

[0121]

change

[0122]

change

[0123]

change

[0124]

change

[0125]

change

[0126]

change

[0127] [ka]

[0128] [ka]

[0129] Specific examples of the iodonium cation represented by formula (Xa-2) include, but are not limited to, the following: [ka]

[0130] [ka]

[0131] Specific examples of the photoacid generator represented by formula (PAG-a) include any combination of the specific anions and specific cations described above.

[0132] In formula (PAG-b), R 1 and R 2 The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, and 2-ethylhexyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclohexylmethyl, cyclohexylethyl, norbornyl, oxanorbornyl, and tricyclo[5.2.1.0]. 2,6] cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as a decyl group or an adamantyl group; aryl groups having 6 to 20 carbon atoms, such as a phenyl group or a naphthyl group; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms in the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms, nitrogen atoms, or halogen atoms, and some of the -CH2- groups in the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms, or nitrogen atoms, resulting in the hydrocarbyl groups containing hydroxy groups, cyano groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, carbonyl groups, ether bonds, ester bonds, sulfonate ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic anhydrides (-C(=O)-OC(=O)-), haloalkyl groups, etc. Among these, R 1 and R 2 is preferably an aryl group in which a hydrogen atom may be substituted.

[0133] R 3The hydrocarbylene group 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 methanediyl, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, nonane-1,9-diyl, decane-1,10-diyl, undecane-1,11-diyl, dodecane-1,12-diyl, tridecane-1,13-diyl, tetradecane-1,14-diyl, pentadecane-1,15-diyl, hexadecane-1,16-diyl, and heptadecane-1,17-diyl; cyclopentanediyl, and cyclohexanediyl groups. cyclic saturated hydrocarbylene groups having 3 to 20 carbon atoms such as a norbornanediyl group or an adamantanediyl group; arylene groups having 6 to 20 carbon atoms such as a phenylene group, a methylphenylene group, an ethylphenylene group, an n-propylphenylene group, an isopropylphenylene group, an n-butylphenylene group, an isobutylphenylene group, a sec-butylphenylene group, a tert-butylphenylene group, a naphthylene group, a methylnaphthylene group, an ethylnaphthylene group, an n-propylnaphthylene group, an isopropylnaphthylene group, an n-butylnaphthylene group, an isobutylnaphthylene group, a sec-butylnaphthylene group or a tert-butylnaphthylene group; and groups obtained by combining these. In addition, some or all of the hydrogen atoms of the hydrocarbylene 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 hydrocarbylene 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 hydrocarbylene 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. 3 is preferably an aryl group in which a hydrogen atom may be substituted.

[0134] L in formula (PAG-b) A Specific examples of the divalent linking group represented by the formula (I) include an ether bond, an ester bond, a thioether bond, a sulfinate ester bond, a sulfonate ester bond, a carbonate bond, and a carbamate bond.

[0135] L in formula (PAG-b) B The hydrocarbylene group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 3 Examples of the hydrocarbylene group include the same as those exemplified above. In addition, some or all of the hydrogen atoms of the hydrocarbylene 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 hydrocarbylene 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 hydrocarbylene 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, or the like. Among these, L B is preferably a methanediyl group or a methanediyl group in which a hydrogen atom is substituted with a fluorine atom or a trifluoromethyl group.

[0136] Specific examples of the photoacid generator represented by formula (PAG-b) include, but are not limited to, those shown below. HF is a hydrogen atom, a fluorine atom or a trifluoromethyl group. [ka]

[0137] [ka]

[0138] [ka]

[0139] In the chemically amplified resist composition of the present invention, the content of (B) photoacid generator is preferably 1 to 50 parts by mass, more preferably 5 to 40 parts by mass, per 80 parts by mass of (A) polymer. A content of (B) photoacid generator within this range is preferable because it provides good resolution and there is no risk of problems with foreign matter occurring after development of the resist film or during stripping. The (B) photoacid generators may be used alone or in combination of two or more.

[0140] [(C) Organic solvent] The organic solvent for component (C) is not particularly limited as long as it can dissolve the components described above and below. Specific examples of such organic solvents include ketones such as cyclopentanone, cyclohexanone, and methyl 2-n-pentyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; ketoalcohols such as DAA; ethers such as PGME, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as PGMEA, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol monotert-butyl ether acetate; lactones such as GBL, and mixed solvents thereof. When a polymer containing an acetal-based acid-labile group is used, a high-boiling alcohol solvent, specifically, diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, 1,3-butanediol, or the like may be added to accelerate the deprotection reaction of the acetal.

[0141] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, cyclohexanone, GBL, DAA, and mixed solvents thereof are preferred because they have particularly excellent solubility for the polymer of component (A).

[0142] The amount of the organic solvent used is preferably 200 to 5000 parts by mass, more preferably 400 to 3500 parts by mass, relative to 80 parts by mass of the (A) polymer. The (C) organic solvent may be used alone or in combination of two or more.

[0143] [(D) Quencher] The chemically amplified resist composition of the present invention may further contain a quencher (acid diffusion controller). In the present invention, the quencher is a material that traps the acid generated by the photoacid generator in the chemically amplified resist composition, thereby preventing the acid from diffusing into unexposed areas and forming a desired pattern.

[0144] (D) The quencher includes an onium salt represented by the following formula (Qa) or (Qb). [ka]

[0145] In formula (Qa), R q1 represents a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom, but excludes those in which the hydrogen atom bonded to the carbon atom at the α-position of the sulfo group is substituted with a fluorine atom or a fluoroalkyl group. q2 is a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom.

[0146] R q1The 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 40 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, and an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, and a tricyclo[5.2.1.0] 2,6 ] cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms such as a decyl group or an adamantyl group; aryl groups having 6 to 40 carbon atoms such as a phenyl group, a naphthyl group or an anthracenyl group; hydrocarbyl groups having a steroid skeleton and having 20 to 38 carbon atoms which may contain a heteroatom; and groups obtained by combining these. Some or all of the hydrogen atoms in the hydrocarbyl groups may be substituted with groups 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 groups may be substituted with groups containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, so that the hydrocarbyl groups may contain hydroxy groups, cyano groups, carbonyl groups, ether bonds, ester bonds, sulfonate ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic anhydrides (-C(=O)-OC(=O)-), haloalkyl groups, etc.

[0147] R q2 The hydrocarbyl group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R q1 In addition to the specific examples of the substituents, examples include fluorinated alkyl groups such as a trifluoromethyl group and a trifluoroethyl group, and fluorinated aryl groups such as a pentafluorophenyl group and a 4-trifluoromethylphenyl group.

[0148] Specific examples of the anion of the onium salt represented by formula (Qa) include, but are not limited to, those shown below. [ka]

[0149] [ka]

[0150] [ka]

[0151] Specific examples of the anion of the onium salt represented by formula (Qb) include, but are not limited to, those shown below. [ka]

[0152] [ka]

[0153] [ka]

[0154] In formulas (Qa) and (Qb), Mq + is an onium cation. The onium cation is preferably one represented by the following formula (Mq-1), (Mq-2) or (Mq-3). [ka]

[0155] In formulas (Mq-1), (Mq-2) and (Mq-3), R q11 ~R q19are each independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. q11 and R q12 and may be bonded to each other to form a ring together with the sulfur atom to which they are attached, and R q16 and R q17 and may be bonded to each other to form a ring together with the nitrogen atom to which they are bonded. Specific examples of the hydrocarbyl group include R 11 ~R 15 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0156] Specific examples of the sulfonium cation represented by formula (Mq-1) include the same as those exemplified as specific examples of the sulfonium cation represented by formula (Xa-1). Specific examples of the iodonium cation represented by formula (Mq-2) include the same as those exemplified as specific examples of the iodonium cation represented by formula (Xa-2). Specific examples of the ammonium cation represented by formula (Mq-3) include, but are not limited to, the following: [ka]

[0157] Specific examples of the onium salts represented by formula (Qa) or (Qb) include any combination of the anions and cations described above. These onium salts can be easily prepared by ion exchange reactions using known organic chemistry methods. For information on ion exchange reactions, see, for example, JP 2007-145797 A.

[0158] The onium salts represented by formula (Qa) or (Qb) function as quenchers in the chemically amplified resist composition of the present invention. This is because the counter anions of the onium salts are the conjugate bases of weak acids. The term "weak acid" used here refers to an acidity that is insufficient to deprotect the acid labile groups in the acid labile group-containing units used in the base polymer.

[0159] The onium salt represented by formula (Qa) or (Qb) functions as a quencher when used in combination with an onium salt-type photoacid generator having a counter anion that is the conjugate base of a strong acid, such as a sulfonic acid fluorinated at the α-position. Specifically, when an onium salt that generates a strong acid, such as a sulfonic acid fluorinated at the α-position, is mixed with an onium salt that generates a weak acid, such as a non-fluorinated sulfonic acid or carboxylic acid, the strong acid generated from the photoacid generator upon irradiation with high-energy radiation collides with an onium salt having an unreacted weak acid anion, releasing the weak acid through salt exchange and generating an onium salt having a strong acid anion. In this process, the strong acid is exchanged for a weak acid with lower catalytic activity, apparently deactivating the acid and enabling control of acid diffusion.

[0160] Furthermore, as the (D) quencher, compounds having a sulfonium cation and a phenoxide anion moiety in the same molecule, as described in Japanese Patent No. 6848776, compounds having a sulfonium cation and a carboxylate anion moiety in the same molecule, as described in Japanese Patent No. 6583136 and JP-A-2020-200311, and compounds having an iodonium cation and a carboxylate anion moiety in the same molecule, as described in Japanese Patent No. 6274755, can also be used.

[0161] Here, when the photoacid generator that generates a strong acid is an onium salt, the strong acid generated by irradiation with high-energy rays can be exchanged for a weak acid as described above, but on the other hand, it is thought that the weak acid generated by irradiation with high-energy rays collides with the unreacted onium salt that generates the strong acid, making it difficult to carry out salt exchange. This is due to the phenomenon that the onium cation is more likely to form an ion pair with the anion of the strong acid.

[0162] When the onium salt quencher represented by formula (Qa) or (Qb) is contained as the (D) quencher, the content thereof is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, relative to 80 parts by mass of the (A) polymer. It is preferable that the onium salt quencher of component (D) is in the above range, since the resolution is good and there is no significant decrease in sensitivity. The onium salt represented by formula (Qa) or (Qb) may be used alone or in combination of two or more.

[0163] As the (D) quencher, a nitrogen-containing quencher can also be used. Examples of the nitrogen-containing quencher include those described in paragraphs

[0146] to

[0147] of JP-A-2008-111103.

[0164] Examples of the amine compounds include the primary, secondary, or tertiary amine compounds described in JP 2004-120901, in particular, amine compounds having a hydroxy group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonate ester bond. Examples also include compounds in which a primary or secondary amine is protected with a carbamate group, such as the compounds described in Japanese Patent No. 3790649.

[0164] Alternatively, a sulfonate sulfonium salt having a nitrogen-containing substituent may be used as a nitrogen-containing quencher. Such a compound functions as a quencher in unexposed areas and loses its quenching ability in exposed areas by neutralizing with the acid generated by the compound itself, functioning as a so-called photodegradable base. The use of a photodegradable base can further enhance the contrast between exposed and unexposed areas. For example, JP-A Nos. 2009-109595 and 2012-46501 can be used as references for the photodegradable base.

[0165] When a nitrogen-containing quencher is contained as the (D) quencher, the content thereof is preferably 0.001 to 12 parts by mass, more preferably 0.01 to 8 parts by mass, relative to 80 parts by mass of the (A) polymer. The nitrogen-containing quencher may be used alone or in combination of two or more types.

[0166] [(E) Surfactant] The chemically amplified resist composition of the present invention may further comprise a surfactant as component (E). The surfactant (E) is preferably a surfactant that is insoluble or slightly soluble in water but soluble in an alkaline developer, or a surfactant that is insoluble or slightly soluble in both water and an alkaline developer. Examples of such surfactants include those described in JP-A-2010-215608 and JP-A-2011-16746.

[0167] Among the surfactants described in the above publications, preferred surfactants that are insoluble or slightly soluble in water and alkaline developers include FC-4430 (manufactured by 3M), Surflon (registered trademark) S-381 (manufactured by AGC Seimi Chemical Co., Ltd.), Olfine (registered trademark) E1004 (manufactured by Nissin Chemical Industry Co., Ltd.), KH-20, KH-30 (manufactured by AGC Seimi Chemical Co., Ltd.), and oxetane ring-opening polymers represented by the following formula (surf-1): [ka]

[0168] Here, R, Rf, A, B, C, m, and n apply only to formula (surf-1), regardless of the above descriptions. R is a divalent to tetravalent aliphatic group having 2 to 5 carbon atoms. Examples of the divalent aliphatic group include an ethylene group, a 1,4-butylene group, a 1,2-propylene group, a 2,2-dimethyl-1,3-propylene group, and a 1,5-pentylene group, and examples of the trivalent or tetravalent aliphatic group include the following: [ka] (In the formula, the dashed lines represent bonds and are partial structures derived from glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol, respectively.)

[0169] Among these, a 1,4-butylene group, a 2,2-dimethyl-1,3-propylene group, and the like are preferred.

[0170] Rf is a trifluoromethyl group or a pentafluoroethyl group, preferably a trifluoromethyl group. m is an integer of 0 to 3, n is an integer of 1 to 4, and the sum of n and m is the valence of R, which is an integer of 2 to 4. A is 1. B is an integer of 2 to 25, preferably an integer of 4 to 20. C is an integer of 0 to 10, preferably 0 or 1. The order of the structural units in formula (surf-1) is not specified, and they may be bonded in blocks or randomly. The production of surfactants based on partially fluorinated oxetane ring-opening polymers is described in detail in the specification of U.S. Pat. No. 5,650,483, etc.

[0171] Surfactants that are insoluble or slightly soluble in water but soluble in alkaline developers have the function of reducing water penetration and leaching by orienting themselves on the surface of the resist film when a resist protective film is not used in ArF immersion lithography. Therefore, they are useful for suppressing the elution of water-soluble components from the resist film and reducing damage to the exposure equipment. They are also useful because they become soluble during alkaline aqueous development after exposure or post-exposure bake (PEB), making them less likely to become contaminants that cause defects. Such surfactants are insoluble or slightly soluble in water but soluble in alkaline developers. They are polymeric surfactants, also known as hydrophobic resins, and are particularly preferred because they have high water repellency and improve water slippage.

[0172] Such polymer surfactants include those containing at least one repeating unit selected from the repeating units represented by any one of the following formulae (SF-a) to (SF-e). [ka]

[0173] In formulas (SF-a) to (SF-e), R B is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 is -CH2-, -CH2CH2-, -O- or two -H groups separated from each other. s1are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. s2 R is a single bond or a linear or branched hydrocarbylene group having 1 to 5 carbon atoms. s3 R are each independently a hydrogen atom, a hydrocarbyl group or a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid labile group. s3 When R is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bonds. s4 is a hydrocarbon group or a fluorinated hydrocarbon group having 1 to 20 carbon atoms and a valence of (u+1). u is an integer of 1 to 3. R s5 are each independently a hydrogen atom or -C(=O)-OR sa R sa is a fluorinated hydrocarbyl group having 1 to 20 carbon atoms. s6 is a hydrocarbyl group or a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, and an ether bond or a carbonyl group may be present between the carbon-carbon bonds.

[0174] R s1 The hydrocarbyl group represented by the formula (I) is preferably a saturated hydrocarbyl group, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 10 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl; and cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, and norbornyl. Of these, those having 1 to 6 carbon atoms are preferred.

[0175] R s2 The hydrocarbylene group represented by the formula (I) is preferably a saturated hydrocarbylene group, which may be linear, branched, or cyclic. Specific examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group, and a pentylene group.

[0176] R s3 or R s6 The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include saturated hydrocarbyl groups and aliphatic unsaturated hydrocarbyl groups such as alkenyl groups and alkynyl groups, with saturated hydrocarbyl groups being preferred. Specific examples of the saturated hydrocarbyl group include R s1 In addition to the examples of the hydrocarbyl group represented by the formula (R), examples include an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, and a pentadecyl group. s3 or R s6 Specific examples of the fluorinated hydrocarbyl group represented by the formula (I) include groups in which some or all of the hydrogen atoms bonded to the carbon atoms of the aforementioned hydrocarbyl group have been substituted with fluorine atoms. As mentioned above, an ether bond or a carbonyl group may be present between these carbon-carbon bonds.

[0177] R s3 Examples of the acid labile group represented by the formula (AL-1) to (AL-3) include the groups represented by the formulas (AL-1) to (AL-3) above, trialkylsilyl groups in which each alkyl group has 1 to 6 carbon atoms, and oxoalkyl groups having 4 to 20 carbon atoms.

[0178] R s4 The (u+1)-valent hydrocarbon group or fluorinated hydrocarbon group represented by the formula (I) may be linear, branched, or cyclic, and specific examples thereof include groups obtained by further eliminating u hydrogen atoms from the aforementioned hydrocarbyl group or fluorinated hydrocarbyl group.

[0179] R saThe fluorinated hydrocarbyl group represented by the formula (I) is preferably saturated and may be linear, branched or cyclic. Specific examples thereof include those in which some or all of the hydrogen atoms of the hydrocarbyl groups have been substituted with fluorine atoms, and specific examples thereof include a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a 3,3,3-trifluoro-1-propyl group, a 3,3,3-trifluoro-2-propyl group, a 2,2,3,3-tetrafluoropropyl group, a 1,1,1,3,3,3-hexafluoroisopropyl group, a 2,2,3,3,4,4,4-heptafluorobutyl group, a 2,2,3,3,4,4,5,5-octafluoropentyl group, a 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl group, a 2-(perfluorobutyl)ethyl group, a 2-(perfluorohexyl)ethyl group, a 2-(perfluorooctyl)ethyl group, and a 2-(perfluorodecyl)ethyl group.

[0180] Specific examples of the repeating unit represented by any one of formulas (SF-a) to (SF-e) include, but are not limited to, those shown below. B is the same as above. [ka]

[0181] [ka]

[0182] [ka]

[0183] [ka]

[0184] [ka]

[0185] The polymer surfactant may further contain other repeating units in addition to the repeating units represented by formulae (SF-a) to (SF-e). Examples of such other repeating units include repeating units obtained from methacrylic acid and α-trifluoromethylacrylic acid derivatives. In the polymer surfactant, the content of the repeating units represented by formulae (SF-a) to (SF-e) is preferably 20 mol % or more, more preferably 60 mol % or more, and even more preferably 100 mol %, of all repeating units.

[0186] The Mw of the polymer surfactant is preferably from 1,000 to 500,000, and more preferably from 3,000 to 100,000. The Mw / Mn is preferably from 1.0 to 2.0, and more preferably from 1.0 to 1.6.

[0187] The polymer surfactant can be synthesized by heating a monomer containing an unsaturated bond that provides the repeating units represented by formulae (SF-a) to (SF-e) and, if necessary, other repeating units in an organic solvent with the addition of a radical initiator to polymerize the monomer. Examples of organic solvents used in polymerization include toluene, benzene, THF, diethyl ether, and dioxane. Examples of polymerization initiators include AIBN, 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The reaction temperature is preferably 50 to 100°C. The reaction time is preferably 4 to 24 hours. The acid labile group introduced into the monomer may be used as is, or may be protected or partially protected after polymerization.

[0188] When synthesizing the polymer surfactant, a known chain transfer agent such as dodecyl mercaptan or 2-mercaptoethanol may be used to adjust the molecular weight. In this case, the amount of the chain transfer agent added is preferably 0.01 to 10 mol % based on the total number of moles of the monomers to be polymerized.

[0189] When the chemically amplified resist composition of the present invention contains a surfactant (E), the content thereof is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 10 parts by mass, per 80 parts by mass of the polymer (A). When the surfactant (E) content is 0.1 part by mass or more, the receding contact angle between the resist film surface and water is sufficiently improved, while when the surfactant content is 50 parts by mass or less, the dissolution rate of the resist film surface in the developer is low, and the height of the formed fine pattern is sufficiently maintained. The surfactant (E) may be used alone or in combination of two or more.

[0190] [(F) Other ingredients] The chemically amplified resist composition of the present invention may contain, as other components (F), a compound that decomposes in the presence of acid to generate acid (acid amplifying compound), an organic acid derivative, a fluorine-substituted alcohol, or a compound with a Mw of 3000 or less whose solubility in a developer changes upon the action of acid (dissolution inhibitor). Examples of the acid amplifying compound include the compounds described in JP-A-2009-269953 and JP-A-2010-215608. When the acid amplifying compound is contained, its content is preferably 0 to 5 parts by mass, more preferably 0 to 3 parts by mass, per 80 parts by mass of the (A) polymer. If the content is too high, it may be difficult to control acid diffusion, resulting in degradation of resolution and pattern shape. Examples of the organic acid derivative, fluorine-substituted alcohol, and dissolution inhibitor include the compounds described in JP-A-2009-269953 and JP-A-2010-215608.

[0191] [Pattern formation method] The pattern forming method of the present invention includes the steps of forming a resist film on a substrate using the above-mentioned chemically amplified resist composition, exposing the resist film to KrF excimer laser light, ArF excimer laser light, EB, or EUV, and developing the exposed resist film using a developer.

[0192] The substrate may be, for example, 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.).

[0193] The resist film can be formed, for example, by applying the chemically amplified resist composition by a method such as spin coating to a film thickness of 0.05 to 2 μm, and then pre-baking the applied composition on a hot plate preferably at 60 to 150°C for 1 to 10 minutes, more preferably at 80 to 140°C for 1 to 5 minutes.

[0194] When KrF excimer laser light, ArF excimer laser light, or EUV is used to expose the resist film, a mask for forming a desired pattern is used, and the exposure dose is preferably 1 to 200 mJ / cm . 2 , more preferably 10 to 100 mJ / cm 2 When EB is used, the exposure dose is preferably 1 to 300 μC / cm 2 , either directly or through a mask for forming a desired pattern. 2 , more preferably 10 to 200 μC / cm 2 Irradiate so that

[0195] In addition to the usual exposure method, the immersion method can also be used, in which a liquid with a refractive index of 1.0 or higher is placed between the resist film and the projection lens. In this case, a water-insoluble protective film can also be used.

[0196] The water-insoluble protective film is used to prevent elution from the resist film and increase the water sliding property of the film surface. It can be broadly divided into two types. One is an organic solvent-removable type that requires stripping before alkaline aqueous development using an organic solvent that does not dissolve the resist film. The other is an alkaline aqueous solution-soluble type that is soluble in alkaline developer and removes the protective film along with removing the soluble portion of the resist film. The latter is particularly based on a polymer containing 1,1,1,3,3,3-hexafluoro-2-propanol residues that is insoluble in water but soluble in alkaline developer, and is preferably dissolved in an alcohol solvent with 4 or more carbon atoms, an ether solvent with 8 to 12 carbon atoms, or a mixed solvent thereof. Materials can also be prepared by dissolving the water-insoluble, alkaline developer-soluble surfactant described above in an alcohol solvent with 4 or more carbon atoms, an ether solvent with 8 to 12 carbon atoms, or a mixed solvent thereof.

[0197] After the exposure, PEB may be performed by heating on a hot plate, for example, preferably at 60 to 150° C. for 1 to 5 minutes, more preferably at 80 to 140° C. for 1 to 3 minutes.

[0198] Development can be carried out by a conventional method such as dipping, puddling, or spraying, using a developer such as an alkaline aqueous solution of tetramethylammonium hydroxide (TMAH) or the like, preferably at a concentration of 0.1 to 5% by mass, more preferably 2 to 3% by mass, for preferably 0.1 to 3 minutes, more preferably 0.5 to 2 minutes. The exposed area dissolves during development, forming the desired pattern on the substrate.

[0199] As a means for forming a pattern, after forming a resist film, a pure water rinse (post-soak) may be performed to extract an acid generator or the like from the film surface or to wash away particles, or a rinse (post-soak) may be performed to remove water remaining on the film after exposure.

[0200] Furthermore, the pattern may be formed by a double patterning method, such as a trench method in which a first exposure and etching process is performed to process an underlayer with a 1:3 trench pattern, and then a second exposure process is performed with a shifted position to form a 1:3 trench pattern, thereby forming a 1:1 pattern, or a line method in which a first underlayer with a 1:3 isolated leave pattern is processed by a first exposure and etching process, and then a second exposure process is performed with a shifted position to process a second underlayer with a 1:3 isolated leave pattern formed below the first underlayer, thereby forming a 1:1 pattern with half the pitch.

[0201] In the pattern forming method of the present invention, negative tone development can also be carried out by using an organic solvent as the developer instead of the alkaline aqueous solution to dissolve the unexposed areas.

[0202] The organic solvent development may be performed using the following developers: 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 methyl methyl valerate, methyl pentenoate, methyl crotonate, ethyl methyl crotonate, propyl methyl methyl valerate, propyl methyl methyl pentenoate, propyl methyl methyl crotonate, propyl methyl methyl methyl crotonate, propyl methyl methyl methyl valerate, propyl methyl methyl pentenoate, propyl methyl methyl methyl crotonate, propyl methyl methyl methyl hexano ... Examples of organic solvents that can be used 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, and 2-phenylethyl acetate. These organic solvents may be used alone or in combination of two or more. [Example]

[0203] The present invention will be specifically explained below by showing synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples. The apparatuses used are as follows. IR: Thermo Fisher Scientific, NICOLET 6700 · 1 H-NMR: ECA-500 manufactured by JEOL Ltd.

[0204] [1] Monomer synthesis [Synthesis Example 1-1] Synthesis of Monomer A-1 [ka]

[0205] (1) Synthesis of intermediate In-1 A Grignard reagent was prepared by placing a 2.0 mol / L THF solution (250 g), ethynylbenzene (51 g), and THF (50 mL) in a reaction vessel under a nitrogen atmosphere. A solution consisting of acetone (38 g) and THF (40 mL) was added dropwise while maintaining the temperature below 50°C. After stirring for 2 hours at 50°C, the reaction solution was ice-cooled and a mixture of ammonium chloride (50 g) and 3.0% by weight aqueous hydrochloric acid (300 g) was added dropwise to quench the reaction. Toluene (300 mL) was added, and the mixture was subjected to standard aqueous work-up. The solvent was removed by distillation under reduced pressure, yielding 76 g of intermediate In-1 as a colorless, transparent oil (yield 91%).

[0206] (2) Synthesis of Monomer A-1 Under a nitrogen atmosphere, a reaction vessel was charged with a solution of intermediate In-1 (114 g), triethylamine (152 g), dimethylaminopyridine (12.2 g), and acetonitrile (400 mL). To this solution, methacrylic acid chloride (136 g) was added dropwise at a temperature of 20°C or less. After aging for 3 hours at 45°C, the reaction mixture was cooled on ice and quenched by the dropwise addition of saturated aqueous sodium bicarbonate (200 mL). The mixture was extracted with hexane (500 mL), subjected to standard aqueous work-up, and the solvent was removed by evaporation. Vacuum distillation afforded 144 g of Monomer A-1 as a colorless, transparent oil (79% yield).

[0207] IR spectrum data of Monomer A-1 and 1 The results of H-NMR are shown below. IR(D-ATR): ν= 3057, 2987, 2928, 1723, 1638, 1599, 1491, 1468, 1444, 1401, 1381, 1363, 1327, 1293, 1175, 1123, 1070, 1007, 965, 941, 884, 858, 815, 757, 692, 652, 569, 549, 509 cm -1 . 1 H-NMR (600MHz in DMSO-d6): δ= 7.37(5H, m), 6.01(1H, s), 5.68(1H, s), 1.87(3H, s), 1.74(6H, m) ppm.

[0208] [Synthesis Example 1-2] Synthesis of Monomer A-2 [ka]

[0209] Monomer A-2 was obtained as a colorless, transparent oily product in the same manner as in Synthesis Example 1-1, except that 4-fluorophenylacetylene was used instead of ethynylbenzene (yield of 78% for two steps).

[0210] IR spectrum data of Monomer A-2 and 1The results of H-NMR are shown below. IR(D-ATR): ν= 2988, 2928, 2230, 1893, 1723, 1638, 1601, 1507, 1469, 1452, 1435, 1404, 1381, 1364, 1327, 1295, 1223, 1175, 1157, 1125, 1093, 1008, 966, 941, 886, 858, 837, 814, 780, 651, 626, 568, 548, 528, 483, 452 cm -1 . 1 H-NMR (600MHz in DMSO-d6): δ= 7.44(2H, dd), 7.20(2H, dd), 6.00(1H, s), 5.67(1H, s), 1.86(3H, s), 1.73(6H, m) ppm.

[0211] [Synthesis Example 1-3] Synthesis of Monomer A-3 [ka]

[0212] Monomer A-3 was obtained as a colorless, transparent oil (yield 77%) in the same manner as in Synthesis Example 1-1, except that cyclopentanone was used instead of acetone.

[0213] IR spectrum data of Monomer A-3 and 1 The results of H-NMR are shown below. IR(D-ATR): ν= 3056, 2959, 2875, 2232, 1723, 1637, 1599, 1573, 1491, 1444, 1401, 1377, 1327, 1299, 1151, 1070, 1008, 969, 944, 862, 815, 757, 692, 651, 535cm -1 . 1H-NMR (600MHz in DMSO-d6): δ= 7.37(5H, m), 6.02(1H, s), 5.68(1H, s), 2.27(2H, m), 2.17(2H, m), 1.87(3H, s), 1.75(4H, m) ppm.

[0214] [Synthesis Examples 1-4 to 1-7] Synthesis of Monomer A-4 to Monomer A-7 [ka]

[0215] Monomers A-4 to A-7 were synthesized using the corresponding raw materials and organic chemistry methods.

[0216] [Comparative Synthesis Examples 1-1 to 1-4] Synthesis of Comparative Monomers cA-1 to cA-4 [ka]

[0217] Comparative Monomers cA-1 to cA-4 were synthesized using the corresponding raw materials and organic chemistry methods.

[0218] [2] Polymer synthesis Of the monomers used in the synthesis of the polymer, those other than Monomers A-1 to A-7 and Comparative Monomers cA-1 to cA-4 are as follows. [ka]

[0219] [ka]

[0220] [ka]

[0221] [ka]

[0222] [Synthesis Example 2-1] Synthesis of Polymer P-1 A monomer-polymerization initiator solution was prepared by placing 32.8 g of Monomer A-1, 17.1 g of Monomer B-1, 3.3 g of V-601 (Fujifilm Wako Pure Chemical Industries, Ltd.), and 52 g of PGMEA in a flask under a nitrogen atmosphere. 23 g of PGMEA was placed in a separate flask under a nitrogen atmosphere and heated to 80°C with stirring. The monomer-polymerization initiator solution was then added dropwise over 4 hours. After the addition, the polymerization solution was stirred for 2 hours while maintaining the temperature at 80°C, and then cooled to room temperature. The resulting polymerization solution was added dropwise to 800 g of vigorously stirred hexane, and the precipitated polymer was filtered. The resulting polymer was washed twice with 300 g of hexane and then vacuum-dried at 50°C for 20 hours to obtain Polymer P-1 as a white powder (yield: 47.9 g, 96%). The Mw of Polymer P-1 was 5400, and the Mw / Mn ratio was 1.67. The Mw is a polystyrene-equivalent value measured by GPC using THF as a solvent. [ka]

[0223] [Synthesis Examples 2-2 to 2-25, Comparative Synthesis Examples 2-1 to 2-25] Synthesis of Polymer P-2 to Polymer P-25, Polymer CP-1 to Polymer CP-25 Polymers shown in Tables 1 and 2 were produced in the same manner as in Synthesis Example 2-1, except that the types and blending ratios of monomers were changed. Note that Mw is a polystyrene-equivalent value measured by GPC using THF or DMF as a solvent.

[0224] [Table 1]

[0225] [Table 2]

[0226] [3] Preparation of chemically amplified resist composition [Examples 1-1 to 1-25, Comparative Examples 1-1 to 1-25] Polymers of the present invention (P-1 to P-25), comparative polymers (CP-1 to CP-25), photoacid generators (PAG-1 to PAG-4), quenchers (SQ-1 to SQ-3, AQ-1), and alkali-soluble surfactant (SF-1) were dissolved in a solvent containing 100 ppm of FC-4430 (manufactured by 3M) as a surfactant, according to the compositions shown in Tables 3 and 4 below, to prepare solutions. Chemically amplified resist compositions were prepared by filtering the solutions through a 0.2 μm Teflon (registered trademark) filter.

[0227] In Tables 3 and 4, the components are as follows: Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) DAA (diacetone alcohol)

[0228] Photoacid generators: PAG-1 to PAG-4 [ka]

[0229] Quencher: SQ-1 to SQ-3, AQ-1 [ka]

[0230] Alkali-soluble surfactant SF-1: Poly(2,2,3,3,4,4,4-heptafluoro-1-isobutyl-1-butyl methacrylate)-9-(2,2,2-trifluoro-1-trifluoromethylethyloxycarbonyl)-4-oxatricyclo[4.2.1.0] methacrylate 3,7 ]nonan-5-on-2-yl) [ka] Mw=7700, Mw / Mn=1.82

[0231] [Table 3]

[0232] [Table 4]

[0233] [4] EUV Lithography Evaluation (1) [Examples 2-1 to 2-25, Comparative Examples 2-1 to 2-25] Each chemically amplified resist composition (R-1 to R-25, CR-1 to CR-25) shown in Tables 3 and 4 was spin-coated onto a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content: 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. had been formed to a thickness of 20 nm, and the substrate was pre-baked at 100°C for 60 seconds using a hot plate to produce a resist film with a thickness of 50 nm. 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 (exposure dose pitch: 1 mJ / cm). 2 After exposure, PEB was performed for 60 seconds at the temperatures shown in Tables 5 and 6. Thereafter, puddle development was performed with a 2.38 mass % TMAH aqueous solution for 30 seconds, followed by rinsing with a surfactant-containing rinse material and spin drying to obtain a positive pattern. The obtained LS patterns were observed with a critical dimension SEM (CG6300) manufactured by Hitachi High-Technologies Corporation, and the sensitivity, exposure latitude (EL), LWR, depth of focus (DOF), and tilt limit were evaluated according to the following methods. The results are shown in Tables 5 and 6.

[0234] [Sensitivity evaluation] The optimum exposure dose Eop (mJ / cm) to obtain an LS pattern with a line width of 18 nm and a pitch of 36 nm 2 The smaller this value, the higher the sensitivity.

[0235] [EL Evaluation] EL (unit: %) was calculated from the exposure amount formed within a range of ±10% (16.2 to 19.8 nm) of the 18 nm space width in the LS pattern using the following formula: The larger this value, the better the performance. EL(%)=(|E1-E2| / Eop)×100 E1: Optimal exposure dose for LS pattern with line width of 16.2 nm and pitch of 36 nm E2: Optimal exposure dose for LS pattern with line width of 19.8 nm and pitch of 36 nm Eop: Optimal exposure dose for LS pattern with line width of 18nm and pitch of 36nm

[0236] [LWR rating] The LS pattern obtained by irradiation with Eop was measured at 10 points along the line length, and the LWR was calculated as three times the standard deviation (σ) (3σ). The smaller this value, the less roughness and the more uniform the line width pattern obtained.

[0237] [DOF evaluation] For the evaluation of the depth of focus, the focus range formed within a range of ±10% (16.2 to 19.8 nm) of the 18 nm dimension of the LS pattern was determined. The larger this value, the wider the depth of focus.

[0238] [Line pattern collapse limit evaluation] The line dimension of the LS pattern at each exposure dose at the optimum focus was measured at 10 points in the longitudinal direction. The thinnest line dimension obtained without collapse was defined as the collapse limit dimension. The smaller this value, the better the collapse limit.

[0239] [Table 5]

[0240] [Table 6]

[0241] The results shown in Tables 5 and 6 demonstrate that the chemically amplified resist composition containing the photoacid generator of the present invention has good sensitivity and excellent EL, LWR, and DOF. It also demonstrates that the collapse limit is small, demonstrating resistance to pattern collapse even in the formation of fine patterns.

[0242] [5] EUV Lithography Evaluation (2) [Examples 3-1 to 3-25, Comparative Examples 3-1 to 3-25] Each chemically amplified resist composition (R-1 to R-25, CR-1 to CR-25) listed in Tables 3 and 4 was spin-coated onto a 20 nm thick silicon spin-on hard mask (SHB-A940, manufactured by Shin-Etsu Chemical Co., Ltd.) containing 43% silicon by weight. The resist was then prebaked at 105°C for 60 seconds using a hot plate to produce a 50 nm thick resist film. The resist film was exposed to light using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadruple-pole illumination, 46 nm pitch on the wafer, and a hole pattern mask with a +20% bias). The resist film was then subjected to PEB for 60 seconds using a hot plate at the temperatures listed in Tables 7 and 8, followed by development for 30 seconds in a 2.38% by weight aqueous TMAH solution to produce a 23 nm hole pattern. Using a critical dimension SEM (CG6300) manufactured by Hitachi High-Technologies Corporation, the exposure dose when a hole dimension of 23 nm was formed was measured and used as the sensitivity. The dimensions of 50 holes were also measured, and the standard deviation (σ) calculated from the results was tripled (3σ) to give the coefficient of dimension variation (CDU). The results are shown in Tables 7 and 8.

[0243] [Table 7]

[0244] [Table 8]

[0245] The results shown in Tables 7 and 8 confirm that the chemically amplified resist composition of the present invention has good sensitivity and excellent CDU.

[0246] Therefore, it was demonstrated that the chemically amplified resist composition of the present invention is suitable as a material for EUV lithography.

[0247] [6] Dry etching resistance evaluation [Examples 4-1 to 4-25, Comparative Examples 4-1 to 4-25] 2 g of each of the polymers (P-1 to P-25, CP-1 to CP-25) shown in Tables 1 and 2 was dissolved in 10 g of cyclohexanone, and the polymer solution was filtered through a 0.2 μm filter. The polymer solution was spin-coated onto a Si substrate to form a film with a thickness of 300 nm, and evaluated under the following conditions. Etching test with CHF3 / CF4 gas: The difference in film thickness of the polymer film before and after etching was determined using a dry etching apparatus TE-8500P manufactured by Tokyo Electron Limited. The etching conditions are as follows: Chamber pressure 40.0Pa RF power 1000W Gap 9mm CHF3 gas flow rate: 30 mL / min CF4 gas flow rate: 30 mL / min Ar gas flow rate: 100 mL / min Time 60sec In this evaluation, a film with a small difference in film thickness, that is, a film with a small reduction in film thickness, indicates that the film has etching resistance. The results of dry etching resistance are shown in Tables 9 and 10.

[0248] [Table 9]

[0249] [Table 10]

[0250] From the results shown in Tables 9 and 10, it was confirmed that the polymer used in the present invention has excellent dry etching resistance in CHF3 / CF4-based gases.

Claims

1. (A) a polymer whose solubility in an alkaline aqueous solution increases under the action of an acid, the polymer comprising a repeating unit represented by the following formula (A1) and a repeating unit represented by the following formula (B1), and not comprising a repeating unit that generates an acid upon exposure to light; and (B) A photoacid generator represented by the following formula (PAG-a) or (PAG-b), which generates an acid when exposed to KrF excimer laser light, ArF excimer laser light, electron beams, or extreme ultraviolet light: A chemically amplified resist composition comprising: 【Chemical 1】 (In the formula, a1 is 0 or 1, and a2 is an integer of 0 to 3. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1 represents a single bond, a phenylene group, a naphthylene group, or *-C(=O)-O-X 11 - is. X 11 is a saturated hydrocarbylene group having 1 to 10 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond, a sulfide bond, a sulfonamide bond, a lactone ring or a sultone ring, or a phenylene group or naphthylene group. * represents a bond to a carbon atom in the main chain. R a1 and R a2 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, and R a1 and R a2 cannot be hydrogen atoms at the same time. a1 and R a2 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R a3 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. a3 may be bonded to each other to form a ring together with the carbon atoms to which they are attached.) 【Chemistry 2】 (In the formula, b1 is an integer of 1 to 4, and b2 is an integer of 0 to 3, provided that 1≦b1+b2≦5. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 2 is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain. R b1 is a halogen atom, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. b1 may be bonded to each other to form a ring together with the carbon atoms to which they are attached.) 【Chemistry 3】 (In the formula, R 0 is a hydrogen atom or a hydrocarbyl group having 1 to 50 carbon atoms, and some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with halogen atoms, and the —CH 2 A portion of - may be substituted with -O- or -C(=O)-. Xa + is an organic cation. 【Chemistry 4】 (In the formula, R 1 and R 2 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 1 and R 2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. R 3 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. L A is a divalent linking group. L B is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom.

2. Xa + 2. The chemically amplified resist composition according to claim 1, wherein is an onium cation represented by the following formula (Xa-1) or (Xa-2): 【Chemistry 5】 (In the formula, R 11 ~R 15 are each independently a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. 11 and R 12 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

3. 2. The chemically amplified resist composition according to claim 1, wherein the polymer further contains a repeating unit represented by the following formula (a1) or (a2): 【Chemistry 6】 (In the formula, R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y 1 represents a single bond, a phenylene group, a naphthylene group, or *-C(=O)-O-Y 11 - is. Y 11 is a saturated hydrocarbylene group having 1 to 10 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond or a lactone ring, or a phenylene group or naphthylene group. Y 2 is a single bond or *-C(=O)-O-. * indicates a bond to a carbon atom in the main chain. AL 1 and AL 2 are each independently an acid labile group having no triple bond. R a4 is a halogen atom, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. a4 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. c is an integer from 0 to 4.

4. 2. The chemically amplified resist composition according to claim 1, wherein the polymer further contains a repeating unit represented by the following formula (C1): 【Chemistry 7】 (In the formula, R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Z 1 represents a single bond, a phenylene group, a naphthylene group, or *-C(=O)-O-Z 11 - is. Z 11 is a saturated hydrocarbylene group having 1 to 10 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond or a lactone ring, or a phenylene group or naphthylene group. * represents a bond to a carbon atom in the main chain. R c1 is a group having 1 to 20 carbon atoms and containing at least one structure selected from a hydrogen atom, a hydroxy group other than a phenolic hydroxy group, a cyano group, a carbonyl group, a carboxy group, an ether bond, an ester bond, a sulfonate ester bond, a sulfonamide bond, a carbonate bond, a lactone ring, a sultone ring, a sulfur atom, and a carboxylic anhydride (-C(=O)-O-C(=O)-).

5. 2. The chemically amplified resist composition according to claim 1, further comprising an organic solvent.

6. 2. The chemically amplified resist composition according to claim 1, further comprising a quencher.

7. 2. The chemically amplified resist composition according to claim 1, further comprising a surfactant.

8. A pattern forming method comprising the steps of: forming a resist film on a substrate using the chemically amplified resist composition according to any one of claims 1 to 7; exposing the resist film to KrF excimer laser light, ArF excimer laser light, an electron beam, or extreme ultraviolet light having a wavelength of 3 to 15 nm; and developing the exposed resist film using a developer.

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