Chemically amplified positive-type resist composition and method for forming a resist pattern

Abstract

To provide a chemically amplified positive resist composition which improves resolution during pattern formation and can give a resist pattern improved in LER, resolution, pattern fidelity, and dose margin, and to provide a resist pattern forming method.SOLUTION: The chemically amplified positive resist composition contains: (A) a quencher represented by the following formula (A1); and (B) a base polymer containing a repeating unit represented by the following formula (B1).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a chemically amplified positive-type resist composition and a resist pattern formation method. [Background technology]

[0002] In recent years, with the increasing integration and speed of LSIs, the miniaturization of pattern rules has been progressing rapidly. For processing patterns smaller than 0.2 μm, chemically amplified resist compositions using acid as a catalyst are primarily used. Furthermore, high-energy beams such as ultraviolet light, far-ultraviolet light, and electron beams (EB) are used as exposure sources. EB lithography, in particular, which is used as an ultra-fine processing technique, has become indispensable as a method for processing photomask blanks when creating photomasks for semiconductor manufacturing.

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

[0004] Typically, the base polymers used in positive-type EB lithography resist compositions and EUV lithography resist compositions are materials that, when irradiated with high-energy rays, use the acid generated from a photoacid generator as a catalyst to deprotect the acid-degradable protecting groups (acid-unstable groups) that mask the acidic functional groups of the phenol side chains of the base polymer, thereby making them solubilizable in alkaline developers.

[0005] As the aforementioned acid-degradable protecting groups, tertiary alkyl groups, tert-butoxycarbonyl groups, and acetal groups have been mainly used. While using protecting groups such as acetal groups, which require relatively low activation energy for deprotection, has the advantage of obtaining highly sensitive resist films, if the diffusion of the generated acid is not sufficiently suppressed, the deprotection reaction can occur even in the unexposed areas of the resist film, leading to problems such as deterioration of line edge roughness (LER) and a decrease in pattern line width dimensional uniformity (CDU). Furthermore, in the processing of photomask blanks, which is a particularly important application, some photomask substrates have surface materials such as chromium oxide and other chromium compound films that are easily affected by the pattern shape of the chemically amplified resist film. In order to maintain high resolution and shape after etching, it is important to maintain a rectangular pattern profile of the resist film regardless of the type of substrate. Furthermore, in recent years, MBMW (Multi-Beam Mask Lighting) lithography processes are sometimes used to process mask blanks in order to achieve miniaturization. In such cases, a low-sensitivity resist composition (high-dose region) that is advantageous for roughness is used as the resist composition, and the optimization of resist compositions in this high-dose region has also attracted attention.

[0006] Various improvements have been made to control sensitivity and pattern profiles by selecting and combining materials used in the resist composition, as well as by adjusting process conditions. One of these improvements addresses the issue of acid diffusion. This acid diffusion has been extensively studied because it significantly affects the sensitivity and resolution of chemically amplified resist compositions.

[0007] Patent documents 1 and 2 describe examples of reducing roughness by increasing the bulk of benzenesulfonic acid generated from a photoacid generator upon exposure, thereby suppressing acid diffusion. However, the suppression of acid diffusion by the aforementioned acid generators is still insufficient, so there has been a need for the development of an acid generator with even lower diffusion.

[0008] Patent Document 3 describes an example of controlling acid diffusion by binding sulfonic acid generated by exposure to a polymer used in the resist composition to suppress diffusion. This method of suppressing acid diffusion by incorporating repeating units that generate acid upon exposure into the base polymer is effective in obtaining a small LER pattern. However, depending on the structure and introduction rate of such repeating units, problems may arise with the solubility of the base polymer to which the repeating units that generate acid upon exposure are bound in organic solvents.

[0009] Furthermore, when using a sulfonium salt that generates a highly acidic acid, such as fluorinated alkanesulfonic acid, as described in Patent Document 4, and a polymer containing repeating units having an acetal group, there was a problem in that a large LER pattern was formed. This is because the acid strength of fluorinated alkanesulfonic acid is too high for the deprotection of acetal groups, which have a relatively low activation energy for deprotection. Even if acid diffusion is suppressed, the deprotection reaction proceeds due to trace amounts of acid diffused into the unexposed areas. The same is true for sulfonium salts that generate benzenesulfonic acid, as described in Patent Documents 1 and 2. Therefore, there is a need for the development of an acid generator that generates an acid of a more suitable strength for the deprotection of acetal groups.

[0010] To suppress acid diffusion, in addition to the aforementioned method of increasing the volume of generated acid, another possible method is to improve the quencher (acid diffusion control agent). Quenchers suppress acid diffusion and are virtually essential components for improving the performance of resist compositions. Various quenchers have been studied, and generally amines or weak onium acids are used. As an example of a weak onium acid, Patent Document 5 describes that the addition of triphenylsulfonium acetate can form T-tops, a difference in line width between isolated and dense patterns, and a good resist pattern without standing waves. Patent Document 6 describes that the addition of ammonium sulfonate or ammonium carboxylate improved sensitivity, resolution, and exposure margin. Furthermore, Patent Document 7 describes that a resist composition for KrF lithography and EB lithography containing a photoacid generator that generates fluorine atom-containing carboxylic acid exhibits excellent resolution and improved process tolerances such as exposure margin and depth of field. These are used in KrF lithography, EB lithography, or F2 lithography.

[0011] Patent Document 8 describes a positive-type photosensitive composition for ArF lithography containing an onium carboxylic acid salt. These compositions work by exchanging a strong acid (sulfonic acid) generated from a photoacid generator upon exposure with a weak onium acid salt, forming a weak acid and a strong onium acid salt. This replaces the highly acidic strong acid (sulfonic acid) with a weak acid (carboxylic acid), thereby suppressing the acid decomposition reaction of acid-unstable groups and reducing (controlling) the acid diffusion distance, thus seemingly functioning as a quencher.

[0012] Patent document 9 describes the use of a sulfonium salt of a carboxylic acid containing a nitrogen-containing heterocycle as a quencher, but detailed studies have not been conducted on low-sensitivity resist compositions (high-dose region) with a C of 50 μC or higher.

[0013] However, when patterning is performed using the resist compositions containing onium carboxylates or onium fluorocarboxylates mentioned above, the LER (Laser Error Rate) and resolution are still insufficient in recent years as miniaturization has progressed. Therefore, there has been a demand for the development of quenchers that can further reduce the LER and improve resolution, pattern fidelity, and dose margin. [Prior art documents] [Patent Documents]

[0014] [Patent Document 1] Japanese Patent Publication No. 2009-53518 [Patent Document 2] Japanese Patent Publication No. 2010-100604 [Patent Document 3] Japanese Patent Publication No. 2011-22564 [Patent Document 4] Patent No. 5083528 [Patent Document 5] Patent No. 3955384 [Patent Document 6] Japanese Patent Application Publication No. 11-327143 [Patent Document 7] Patent No. 4231622 [Patent Document 8] Patent No. 4226803 [Patent Document 9] Patent No. 6512049 [Overview of the project] [Problems that the invention aims to solve]

[0015] The present invention has been made in view of the above circumstances, and aims to provide a chemically amplified positive-type resist composition and a resist pattern formation method that improves resolution during pattern formation and allows for the acquisition of resist patterns with improved LER, resolution, pattern fidelity, and dose margin. [Means for solving the problem]

[0016] As a result of intensive studies to achieve the above object, the inventors of the present invention have found that when a quencher composed of an onium salt in which a conjugate acid of an anion moiety decomposes into carbon dioxide and an organic compound having 12 or less carbon atoms by the action of an acid and heat is introduced into a resist composition, a pattern showing good resolution and pattern shape can be obtained, and a pattern with improved LER, pattern fidelity, and dose margin can be obtained, and thus the present invention has been completed.

[0017] That is, the present invention provides the following chemically amplified positive resist composition and resist pattern forming method. 1. A chemically amplified positive resist composition comprising: (A) a quencher composed of an onium salt represented by the following formula (A1), and (B) a base polymer containing a repeating unit represented by the following formula (B1) and decomposing by the action of an acid to increase solubility in an alkali developer. [Chemical formula] (In the formula, X is a single bond, -O-, or -S-. R 1 and R 2 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms, and a part of -CH2- of the hydrocarbyl group may be substituted with -O- or -C(=O)-. Also, R 1 and R 2 may combine with each other to form a ring together with the carbon atom to which they are attached. R 3 is a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms when X is a single bond or -S-, and is a hydrogen atom, a hydrocarbyl group having 1 to 10 carbon atoms other than an acid-labile group, or an acid-labile group when X is -O-. A part or all of hydrogen atoms of the hydrocarbyl group may be substituted with halogen atoms, and a part of -CH2- of the hydrocarbyl group may be substituted with -O- or -C(=O)-. R 1 and R 3 may combine with each other to form a ring together with the atom to which they are attached and the atoms therebetween. However, when R 3 is other than an acid-labile group, R 1 ~R3 The upper limit for the number of carbon atoms contained in is 10. Z + This is an onium cation. [ka] (In the formula, a1 is 0 or 1. a2 is an integer between 0 and 2. a3 is an integer satisfying 0 ≤ a3 ≤ 5 + 2(a2) - a4. a4 is an integer between 1 and 3.) R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 11 This is a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. A 1 (This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the -CH2- of the saturated hydrocarbylene group may be substituted with -O-.) 2. A chemically amplified positive resist composition of 1, where X is -O-. 3.R 3 However, it is a chemically amplified positive-type resist composition of group 2, which is an acid-unstable group. 4. A chemically amplified positive resist composition of any of 1 to 3, wherein the acid-unstable group is represented by the following formula (AL-1) or (AL-2). [ka] (In the formula, X a It is either -O- or -S-. R 4 , R 5 and R 6Each of these is independently a C1-C12 hydrocarbyl group, and some of the -CH2- of the hydrocarbyl group may be substituted with -O- or -S-, and if the hydrocarbyl group includes an aromatic ring, some or all of the hydrogen atoms of the aromatic ring may be substituted with a halogen atom, a cyano group, a nitro group, a C1-C4 alkyl group which may contain a halogen atom, or a C1-C4 alkoxy group which may contain a halogen atom. 4 , R 5 and R 6 Any two of these may be bonded together to form a ring, and some of the -CH2- in the ring may be substituted with -O- or -S-. R 7 and R 8 Each of these is independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. 9 is a hydrocarbyl group having 1 to 20 carbon atoms, and some of the -CH2- groups of the hydrocarbyl group may be substituted with -O- or -S-. Also, R 8 and R 9 and are bonded to each other, and the carbon atoms and X that they bond to are bonded to. a Together, they may form a heterocyclic group having 3 to 20 carbon atoms, and some of the -CH2- in the heterocyclic group may be substituted with -O- or -S-. n1 and n2 are independently either 0 or 1. * represents a bond with an adjacent -O-. 5.Z + However, a chemically amplified positive resist composition of any of 1 to 4, which is an onium cation represented by any of the following formulas (cation-1) to (cation-3). [ka] (In the formula, R c1 ~R c9 Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain a halogen atom or a heteroatom. Also, R c1 and R c2 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. 6. A chemically amplified positive resist composition of any one of 1 to 5, wherein the polymer further comprises repeating units represented by the following formula (B2-1). [ka] (In the formula, b1 is 0 or 1. b2 is an integer between 0 and 2. b3 is an integer satisfying 0 ≤ b3 ≤ 5 + 2(b2) - b4. b4 is an integer between 1 and 3. b5 is 0 or 1.) R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 12 This is a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom. A 2 This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the -CH2- of the saturated hydrocarbylene group may be substituted with -O-. When b4 is 1, X is an acid-unstable group. When b4 is 2 or 3, X is independently either a hydrogen atom or an acid-unstable group, but at least one of them is an acid-unstable group. 7. A chemically amplified positive resist composition of any one of 1 to 6, wherein the polymer further comprises repeating units represented by the following formula (B2-2). [ka] (In the formula, c1 is an integer between 0 and 2. c2 is an integer between 0 and 2. c3 is an integer between 0 and 5. c4 is an integer between 0 and 2.) R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 13 and R 14 Each of these is independently a hydrocarbyl group having 1 to 10 carbon atoms, which may contain heteroatoms, and R 13 and R 14These elements may bond with each other to form a ring with the carbon atoms to which they are bonded. R 15 Each of these is independently a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, or a fluorinated alkoxy group having 1 to 5 carbon atoms. R 16 Each of these is independently a hydrocarbyl group having 1 to 10 carbon atoms, which may contain heteroatoms. A 3 This refers to a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OA 31 - is A 31 This is an aliphatic hydrocarbylene group having 1 to 20 carbon atoms, which may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring, or a phenylene group or naphthylene group. * indicates a bond with a carbon atom of the main chain. 8. Any one of 1 to 7 chemically amplified positive resist compositions, wherein the polymer further comprises at least one selected from repeating units represented by the following formula (B3), repeating units represented by the following formula (B4), and repeating units represented by the following formula (B5). [ka] (In the formula, d and e are each an integer between 0 and 4, independently of each other. f1 is either 0 or 1. f2 is an integer between 0 and 2. f3 is an integer between 0 and 5.) R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 21 and R 22 These are, independently, a hydroxyl group, a halogen atom, a saturated hydrocarbyl group having 1 to 8 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 8 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom. R 23These are saturated hydrocarbyl groups having 1 to 20 carbon atoms, saturated hydrocarbyloxy groups having 1 to 20 carbon atoms, saturated hydrocarbylcarbonyloxy groups having 2 to 20 carbon atoms, saturated hydrocarbyloxyhydrocarbyl groups having 2 to 20 carbon atoms, saturated hydrocarbylthiohydrocarbyl groups having 2 to 20 carbon atoms, halogen atoms, nitro groups, cyano groups, saturated hydrocarbylsulfinyl groups having 1 to 20 carbon atoms, or saturated hydrocarbylsulfonyl groups having 1 to 20 carbon atoms. A 4 (This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the -CH2- of the saturated hydrocarbylene group may be substituted with -O-.) 9. Any one of 1 to 8 chemically amplified positive resist compositions, wherein the polymer further comprises at least one selected from the repeating units represented by the following formulas (B6), (B7), (B8), (B9), (B10), (B11), (B12), and (B13). [ka] (In the formula, R B Each of these is independently either a hydrogen atom or a methyl group. Y 1 This refers to a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, or *-OY 11 -, *-C(=O)-OY 11 -or *-C(=O)-NH-Y 11 - and Y 11 This is an aliphatic hydrocarbylene group, phenylene group, naphthylene group having 1 to 6 carbon atoms, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. Y 2 is a single bond or **-Y 21 -C(=O)-O- and Y 21This is a hydrocarbylene group having 1 to 20 carbon atoms, which may contain heteroatoms. Y 3 This includes single bonds, methylene groups, ethylene groups, phenylene groups, fluorinated phenylene groups, trifluoromethyl groups, and phenylene groups substituted with *-OY 31 -, *-C(=O)-OY 31 - or *-C(=O)-NH-Y 31 - is Y 31 This refers to a C1-C6 aliphatic hydrocarbylene group, phenylene group, fluorinated phenylene group, phenylene group substituted with a trifluoromethyl group, or a C7-C20 group obtained by combining these, which may contain a carbonyl group, ester bond, ether bond, or hydroxyl group. * represents a bond with a carbon atom in the main chain, and ** represents a bond with an oxygen atom in the formula. Y 4 This is a hydrocarbylene group having 1 to 30 carbon atoms, which may contain single bonds or heteroatoms. g1 and g2 are independently either 0 or 1, but Y 4 When it is a single bond, g1 and g2 are 0. R 31 ~R 48 Each of these is independently a C1-C20 hydrocarbyl group which may contain a halogen atom or a heteroatom. 31 and R 32 However, they may bond to each other and form a ring with the sulfur atom to which they are bonded, R 33 and R 34 , R 36 and R 37 , or R 39 and R 40 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. R HF This is either a hydrogen atom or a trifluoromethyl group. Xa - (It is a non-nucleophilic counterion.) 10. A chemically amplified positive resist composition according to any one of 1 to 9, wherein the content of repeating units having an aromatic ring skeleton among all repeating units of the polymer contained in the base polymer is 60 mol% or more. 11. Furthermore, any of the chemically amplified positive resist compositions 1 to 10 comprising (C) a photoacid generator. 12. The chemically amplified positive resist composition according to 11, wherein the acid strength (pKa) of the anion of the photoacid generator is -3.0 or higher. 13. A chemically amplified positive resist composition of 11 or 12, wherein the ratio of (C) photoacid generator to (A) quencher is less than 6 by mass. 14. A chemically amplified positive resist composition of any of 1 to 13, further comprising (D) a fluorine atom-containing polymer which comprises at least one selected from the repeating units represented by the following formula (D1), the repeating units represented by the following formula (D2), the repeating units represented by the following formula (D3), and the repeating units represented by the following formula (D4), and which may further comprise at least one selected from the repeating units represented by the following formula (D5) and the repeating units represented by the following formula (D6). [ka] (In the equation, x is an integer between 1 and 3. y is an integer satisfying 0 ≤ y ≤ 5 + 2z - x. z is either 0 or 1. h is an integer between 1 and 3.) R C These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R D Each of these is independently either a hydrogen atom or a methyl group. R 101 , R 102 , R 104 and R 105 Each of these is independently either a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 103 , R 106 , R 107 and R 108 Each of these is independently a hydrogen atom, a C1-C15 hydrocarbyl group, a C1-C15 fluorinated hydrocarbyl group, or an acid-unstable group, and R103 , R 106 , R 107 and R 108 When R, R, and R are hydrocarbyl groups or fluorinated hydrocarbyl groups, an ether bond or a carbonyl group may be interposed between the carbon-carbon bonds. R 109 is a hydrogen atom or a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, in which a group containing a heteroatom may be interposed between the carbon-carbon bonds. R 110 is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, in which a group containing a heteroatom may be interposed between the carbon-carbon bonds. R 111 is a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, and a part of -CH2- of the saturated hydrocarbyl group may be substituted with an ester bond or an ether bond. Z 1 is a (h + 1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (h + 1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. Z 2 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is a bond to a carbon atom of the main chain. Z 3 is a single bond, -O-, *-C(=O)-O-Z 31 -Z 32 - or *-C(=O)-NH-Z 31 -Z 32 -. Z 31 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. Z 32 is a single bond, an ester bond, an ether bond or a sulfonamide bond. * is a bond to a carbon atom of the main chain.) 15. Further, (E) a chemically amplified positive resist composition containing an organic solvent and any one of 1 to 14. A method for forming a resist pattern, comprising the steps of: forming a resist film on a substrate using any of the chemically amplified positive-type resist compositions from 16.1 to 15; irradiating the resist film with a pattern using high-energy rays; and developing the resist film irradiated with the pattern using an alkaline developer. 17. A resist pattern formation method 16 wherein the high-energy beam is EUV or EB. 18. 16 resist pattern forming methods wherein the outermost surface of the substrate is made of a material containing at least one selected from chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten, and tin. 19. A method for forming a resist pattern 16 or 17, wherein the substrate is a transmissive or reflective mask blank. A transmissive or reflective mask blank coated with any of the chemically amplified positive resist compositions described in 20.1 to 20.15. [Effects of the Invention]

[0018] The chemically amplified positive resist composition of the present invention effectively controls acid diffusion due to exposure during pattern formation through the action of the onium salt represented by formula (A1). When a resist film is formed using this composition to create a pattern, it is possible to obtain a pattern with extremely high resolution, high pattern fidelity, and improved LER and dose margin. Furthermore, the repeating unit represented by formula (B1) exhibits good solubility in alkaline developers and improves adhesion to the substrate when forming the resist film.

[0019] The resist pattern formation method using the chemically amplified positive resist composition of the present invention can form patterns with high resolution and pattern fidelity while improving LER and dose margin, and is therefore suitable for use in microfabrication technologies, particularly EUV lithography and EB lithography. [Modes for carrying out the invention]

[0020] The present invention will be described in detail below. In the following description, depending on the structure represented by the chemical formula, an asymmetric carbon may be present, and enantiomers or diastereomers may exist. In such cases, a single formula will represent all of these isomers. These isomers may be used individually or as a mixture.

[0021] [Chemically amplified positive-type resist composition] The chemically amplified positive resist composition of the present invention is characterized by comprising (A) a quencher consisting of an onium salt in which the conjugate acid of the anionic portion decomposes into carbon dioxide and an organic compound having 12 or fewer carbon atoms by the action of acid and heat, and (B) a base polymer containing a predetermined polymer.

[0022] [(A) Quencher] The onium salt, which is the quencher of component (A), is represented by the following formula (A1). [ka]

[0023] formula( A 1) In this case, X is a single bond, -O-, or -S-. Of these, a single bond or -O- is preferred, and -O- is more preferred.

[0024] formula( A 1) Medium, R 1 and R 2Each of these is independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms, and some of the -CH2- in the hydrocarbyl group may be substituted with -O- or -C(=O)-. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C10 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl groups; C3-C10 cyclic saturated hydrocarbyl groups such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; C2-C10 alkenyl groups such as vinyl, allyl, propenyl, butenyl, and hexenyl groups; C3-C10 cyclic unsaturated hydrocarbyl groups such as cyclohexenyl groups; C2-C10 aryl groups such as phenyl and naphthyl groups; C7-C10 aralkyl groups such as benzyl, 1-phenylethyl, and 2-phenylethyl groups; and groups obtained by combining these. Furthermore, some of the -CH2- in the hydrocarbyl groups may be substituted with -O- or -C(=O)-.

[0025] Also, R 1 and R 2 However, they may bond to each other and form a ring with the carbon atoms to which they are bonded. In this case, the ring is preferably a ring having 3 to 10 carbon atoms, and more preferably a saturated ring. Specifically, cyclopropane rings, cyclobutane rings, cyclopentane rings, cyclohexane rings, norbornane rings, adamantane rings, etc. are preferred. In addition, some of the -CH2- in the ring may be substituted with -O- or -C(=O)-.

[0026] R 1 and R 2 Examples include hydrogen atoms, saturated hydrocarbyl groups with 1 to 6 carbon atoms, or R 1 and R 2 Preferably, these are saturated rings having 3 to 8 carbon atoms formed by bonding with each other and the carbon atoms to which they are bonded, and include hydrogen atoms, saturated hydrocarbyl groups having 1 to 4 carbon atoms, or R 1 and R2 It is more preferable that these atoms bond to each other, forming a saturated ring with 3 to 6 carbon atoms, together with the carbon atoms to which they bond.

[0027] formula( A 1) Medium, R 3 When X is a single bond or -S-, it is a hydrogen atom or a C1-C10 hydrocarbyl group; when X is -O-, it is a hydrogen atom, a C1-C10 hydrocarbyl group other than an acid-unstable group, or an acid-unstable group. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C10 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl groups; C3-C10 cyclic saturated hydrocarbyl groups such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; C2-C10 alkenyl groups such as vinyl, allyl, propenyl, butenyl, and hexenyl groups; C3-C10 cyclic unsaturated hydrocarbyl groups such as cyclohexenyl; and C3-C10 groups such as phenyl and naphthyl groups. 6 Examples include aryl groups with up to 10 carbon atoms; aralkyl groups with 7 to 10 carbon atoms such as benzyl groups, 1-phenylethyl groups, and 2-phenylethyl groups; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with halogen atoms such as fluorine, chlorine, bromine, or iodine, and some of the -CH2- groups of the hydrocarbyl group may be substituted with -O- or -C(=O)-.

[0028] Also, R 1 and R 3 These are carbon atoms that bond to each other. and the atoms between themA ring may be formed together with X. If X is a single bond, the resulting ring will be the corresponding cycloalkyl ketone; if X is -O-, it will be the corresponding lactone ring; and if X is -S-, it will be the corresponding thiolactone ring. The ring is preferably a 3- to 8-membered ring, and more preferably a 5- to 7-membered ring. Some or all of the hydrogen atoms in the ring may be substituted with halogen atoms, and some of the -CH2- in the ring may be substituted with -O- or -C(=O)-.

[0029] Note, R 3 If R is not an acid-unstable group, 1 ~R 3 The upper limit for the number of carbon atoms contained in is 10.

[0030] R 3 The acid-unstable group represented by is preferably one represented by the following formula (AL-1) or (AL-2). [ka]

[0031] In formula (AL-1), R 4 , R 5 and R 6 Each of these is independently a C1-C12 hydrocarbyl group, and some of the -CH2- groups of the hydrocarbyl group may be substituted with -O- or -S-. If the hydrocarbyl group includes an aromatic ring, some or all of the hydrogen atoms of the aromatic ring may be substituted with a halogen atom, a cyano group, a nitro group, a C1-C4 alkyl group which may contain a halogen atom, or a C1-C4 alkoxy group which may contain a halogen atom. n1 is 0 or 1. * represents a bond with an adjacent -O-.

[0032] R 4 , R 5 and R 6The C1-C12 hydrocarbyl group represented by can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include C1-C12 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl, and n-dodecyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, norbornylmethyl, adamantyl, adamantylmethyl, and tricyclo[5.2.1.0 2,6 ] Decyl group, tetracyclo[6.2.1.1 3,6 .0 2,7 Examples include: cyclic saturated hydrocarbyl groups with 3 to 12 carbon atoms, such as the dodecyl group; alkenyl groups with 2 to 12 carbon atoms, such as the vinyl group, allyl group, propenyl group, butenyl group, pentenyl group, and hexenyl group; alkynyl groups with 2 to 12 carbon atoms, such as the ethynyl group, propynyl group, butynyl group, pentynyl group, and hexynyl group; cyclic unsaturated aliphatic hydrocarbyl groups with 3 to 12 carbon atoms, such as the cyclopentenyl group and cyclohexenyl group; aryl groups with 6 to 12 carbon atoms, such as the phenyl group, naphthyl group, and indanyl group; and aralkyl groups with 7 to 12 carbon atoms, such as the benzyl group, 1-phenylethyl group, and 2-phenylethyl group: and groups obtained by combining these.

[0033] Also, R 4 , R 5 and R 6 Any two of these may bond to each other to form a ring. The ring formed in this case may be a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, a cyclooctane ring, a norbornane ring, an adamantane ring, or a tricyclo[5.2.1.0 2,6 ] Decane ring, tetracyclo[6.2.1.1 3,6 .0 2,7Examples include dodecane rings. In addition, some of the -CH2- in the ring may be substituted with -O- or -S-.

[0034] In formula (AL-2), X a It is -O- or -S-. 7 and R 8 Each of these is independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. 7 and R 8 The hydrocarbyl group, represented by , having 1 to 10 carbon atoms, can be saturated or unsaturated, and can be linear, branched, or cyclic. A specific example is R 1 and R 2 Examples of hydrocarbyl groups with 1 to 10 carbon atoms, as shown in the example, are similar to those exemplified above.

[0035] In formula (AL-2), R 9 This is a hydrocarbyl group having 1 to 20 carbon atoms, and some of the -CH2- groups of the hydrocarbyl group may be substituted with -O- or -S-. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C20 alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, n-octyl group, n-nonyl group, n-decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, heptadecyl group, octadecyl group, nonadecyl group, and eicosyl group; cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclopropylmethyl group, 4-methylcyclohexyl group, cyclohexylmethyl group, norbornyl group, norbornylmethyl group, adamantyl group, adamantylmethyl group, and tricyclo[5.2.1.0 2,6 ] Decyl group, tetracyclo[6.2.1.1 3,6 .0 2,7] Cyclic saturated hydrocarbyl groups with 3 to 20 carbon atoms, such as dodecyl group; alkenyl groups with 2 to 20 carbon atoms, such as vinyl group, propenyl group, butenyl group, pentenyl group, hexenyl group; alkynyl groups with 2 to 20 carbon atoms, such as ethynyl group, propynyl group, butynyl group, pentynyl group, hexynyl group; cyclic unsaturated aliphatic hydrocarbyl groups with 3 to 20 carbon atoms, such as cyclopentenyl group, cyclohexenyl group, norbornenyl group; phenyl group, methylphenyl group, ethylphenyl group, n-propylphenyl group, isopropyl Examples include aryl groups having 6 to 20 carbon atoms, such as propylphenyl, n-butylphenyl, isobutylphenyl, sec-butylphenyl, tert-butylphenyl, naphthyl, methylnaphthyl, ethylnaphthyl, n-propylnaphthyl, isopropylnaphthyl, n-butylnaphthyl, isobutylnaphthyl, sec-butylnaphthyl, and tert-butylnaphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl and phenethyl; and groups obtained by combining these. Also, R 8 and R 9 and are bonded to each other, and the carbon atoms and X that they bond to are bonded to. a Together with these, a heterocyclic group having 3 to 20 carbon atoms may be formed, and some of the -CH2- in the heterocyclic group may be substituted with -O- or -S-. n2 is 0 or 1. * represents a bond with an adjacent -O-.

[0036] Examples of acid-unstable groups represented by formula (AL-1) include, but are not limited to, those listed below. In the following formulas, * represents a bond with an adjacent -O-. [ka]

[0037] [ka]

[0038] [ka]

[0039] [ka]

[0040] [ka]

[0041] [ka]

[0042] [ka]

[0043] [ka]

[0044] [ka]

[0045] [ka]

[0046] [ka]

[0047] Examples of acid-unstable groups represented by formula (AL-2) include, but are not limited to, those listed below. In the following formulas, * represents a bond with an adjacent -O-. [ka]

[0048] [ka]

[0049] R 3 When X is a single bond or -S-, a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkyl group substituted with a halogen atom, or a C3-C6 cyclic saturated hydrocarbyl group is preferred, and a hydrogen atom, a C1-C3 alkyl group, a C1-C3 alkyl group substituted with a halogen atom, or a C3-C6 cyclic saturated hydrocarbyl group is more preferred. When X is -O-, a hydrogen atom, a C1-C4 alkyl group other than an acid-unstable group, a C1-C4 alkyl group other than an acid-unstable group substituted with a halogen atom, or an acid-unstable group represented by formula (AL-1) or (AL-2) is preferred, and a hydrogen atom, a C1-C3 hydrocarbyl group other than an acid-unstable group, a C1-C3 alkyl group other than an acid-unstable group substituted with a halogen atom, or an acid-unstable group represented by formula (AL-1) or (AL-2) is more preferred.

[0050] formula( A Preferred examples of anions for the onium salt represented in 1) include, but are not limited to, the following. [ka]

[0051] [ka]

[0052] [ka]

[0053] [ka]

[0054] [ka]

[0055]

change

[0056]

change

[0057]

change

[0058]

change

[0059]

change

[0060]

change

[0061]

change

[0062]

change

[0063]

change

[0064]

change

[0065]

change

[0066]

change

[0067]

change

[0068]

change

[0069]

change

[0070]

change

[0071]

change

[0072]

change

[0073]

change

[0074]

change

[0075]

change

[0076]

change

[0077]

change

[0078]

change

[0079]

change

[0080]

change

[0081]

change

[0082]

change

[0083]

change

[0084]

change

[0085]

change

[0086]

change

[0087] [Chemistry]

[0088] [Chemistry]

[0089] [Chemistry]

[0090] [Chemistry]

[0091] In formula ( A 1), Z + is an onium cation. As the onium cation, a sulfonium cation represented by the following formula (cation-1), an iodonium cation represented by the following formula (cation-2), or an ammonium cation represented by the following formula (cation-3) is preferable. [Chemistry]

[0092] In formulas (cation-1) to (cation-3), R c1 ~R c9 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a hetero atom.

[0093] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.

[0094] The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C30 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl groups; C3-C30 cyclic saturated hydrocarbyl groups such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; C2-C30 alkenyl groups such as vinyl, allyl, propenyl, butenyl, and hexenyl groups; C3-C30 cyclic unsaturated hydrocarbyl groups such as cyclohexenyl groups; C6-C30 aryl groups such as phenyl, naphthyl, and thienyl groups; C7-C30 aralkyl groups such as benzyl, 1-phenylethyl, and 2-phenylethyl groups; and groups obtained by combining these, but aryl groups are preferred. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing heteroatoms such as oxygen, sulfur, nitrogen, or halogen atoms, and some of the -CH2- groups of the hydrocarbyl group may be substituted with a group containing heteroatoms such as oxygen, sulfur, or nitrogen atoms, and as a result, the material may contain hydroxyl groups, cyano groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, carbonyl groups, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic acid anhydrides (-C(=O)-OC(=O)-), haloalkyl groups, etc.

[0095] Also, R c1 and R c2 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. In this case, examples of sulfonium cations represented by formula (cation-1) include those represented by the following formula. [ka] (In the formula, the dashed line represents R c3 (This is a combination of the two.)

[0096] Examples of sulfonium cations represented by formula (cation-1) include, but are not limited to, those listed below. [ka]

[0097] [ka]

[0098] [ka]

[0099] [ka]

[0100] [ka]

[0101] [ka]

[0102] [ka]

[0103] [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] [ka]

[0118] [ka]

[0119] [ka]

[0120] [ka]

[0121] [ka]

[0122] Examples of iodonium cations represented by formula (cation-2) include, but are not limited to, those listed below. [ka]

[0123] [ka]

[0124] Examples of ammonium cations represented by formula (cation-3) include, but are not limited to, those listed below. [ka]

[0125] Specific examples of onium salts represented by formula (A1) include any combination of the anion and cation mentioned above.

[0126] The onium salt represented by formula (A1) can be produced, for example, according to the following scheme. The synthesis of the onium salt (A1') where X is an oxygen atom is described below as an example, but the synthesis method is not limited to this. [ka] (In the formula, R 1 ~R 3 and Z + This is the same as above. Et is an ethyl group. M + X is a metal cation. - (This is an anion.)

[0127] First, the starting alcohol (SM-A) and acid chloride (SM-B) are reacted to carry out esterification. The starting alcohol (SM-A) is dissolved in a solvent such as tetrahydrofuran (THF) or acetonitrile, and the acid chloride (SM-B) is added dropwise in the presence of a base such as pyridine or 2,6-lutidine. The reaction can be carried out by heating as needed. For optimal yield, it is desirable to monitor the reaction using gas chromatography (GC) or silica gel thin-layer chromatography (TLC) to complete the reaction, but it is usually around 2 to 24 hours. The intermediate (In-A) can be obtained from the reaction mixture by conventional aqueous work-up, and if necessary, it can be purified by conventional methods such as distillation, chromatography, or recrystallization.

[0128] Next, intermediate (In-B) is synthesized by alkaline hydrolysis of the obtained intermediate (In-A) using a metal hydroxide represented by M-OH. Alkaline hydrolysis is carried out by dissolving the intermediate in a solvent such as THF or acetonitrile and adding an aqueous solution of the metal hydroxide represented by M-OH dropwise. Examples of metal hydroxides that can be used include sodium hydroxide, potassium hydroxide, and lithium hydroxide. The reaction can be carried out by heating as needed. The reaction time is usually around 2 to 24 hours, although it is desirable to complete the reaction by monitoring it with silica gel thin-layer chromatography (TLC) for better yield. Intermediate (In-B) can be obtained from the reaction mixture by conventional aqueous work-up, and if necessary, it can be purified by conventional methods such as chromatography and recrystallization.

[0129] The final step is to use the obtained intermediate (In-B) in Z + X - Onium salt (1') is synthesized by salt exchange with the onium salt represented by . Note that X - Bicarbonate ions, chloride ions, and bromide ions are preferred because the exchange reaction proceeds quantitatively easily.

[0130] In the above scheme, the third step of ion exchange can be easily carried out by known methods, for example, by referring to Japanese Patent Publication No. 2007-145797.

[0131] The manufacturing method according to the above scheme is merely an example, and the method for producing the onium salt is not limited to this.

[0132] Another example of a method for synthesizing the onium salt represented by formula (A1) is to exchange the carboxylic acid having the anion in formula (A1) with an onium salt that is a weaker acid than the carboxylic acid. Carbonic acid is an example of such a weaker acid than the carboxylic acid. Alternatively, the onium salt can also be synthesized by ion-exchanging the sodium salt of the carboxylic acid having the anion in formula (A1) with a sulfonium chloride.

[0133] The onium salt represented by formula (A1) functions very effectively as a quencher when applied to a chemically amplified positive resist composition.

[0134] Onium salts having these structures act as quenchers, effectively trapping strong acids generated from acid generators to form 1,3-dicarboxylic acid monoesters or 1,3-ketocarboxylic acid structures. In formula (A1), R 3 When the onium salt forms an acid-unstable group with an adjacent oxygen atom, it reacts with a strong acid to remove the acid-unstable group, improving the sensitivity of the resist film and resulting in a 1,3-dicarboxylic acid (e.g., malonic acid) structure. In the subsequent PEB step, the 1,3-dicarboxylic acid monoester, 1,3-ketocarboxylic acid, and 1,3-dicarboxylic acid undergo a thermal decarboxylation reaction, decomposing into carbon dioxide and corresponding acetic acid or ketone derivatives, which then volatilize from the film. During subsequent development with an alkaline developer, the absence of carboxylic acid, which has a high affinity for the alkaline developer, suppresses swelling and prevents the collapse of the resist pattern, which was a problem during fine pattern formation. Therefore, the onium salt represented by formula (A1) is suitable for application to chemically amplified positive-type resist compositions.

[0135] In the chemically amplified positive resist composition of the present invention, the content of the quencher consisting of an onium salt represented by formula (A1) is preferably 0.1 to 20 parts by mass, and more preferably 1 to 15 parts by mass, relative to 80 parts by mass of the base polymer (B) described later. If the content of the onium salt represented by formula (A1) is within the above range, it functions sufficiently as a quencher and there is no risk of performance degradation such as decreased sensitivity or generation of foreign matter due to insufficient solubility. The onium salt represented by formula (A1) may be used alone or in combination of two or more types.

[0136] [(B) Base polymer] The base polymer of component (B) contains a repeating unit represented by the following formula (B1) (hereinafter also referred to as repeating unit B1), which decomposes upon the action of an acid and contains a polymer whose solubility in an alkaline developer increases. [ka]

[0137] In formula (B1), a1 is 0 or 1. a2 is an integer between 0 and 2, where 0 represents the benzene skeleton, 1 represents the naphthalene skeleton, and 2 represents the anthracene skeleton. a3 is an integer satisfying 0 ≤ a3 ≤ 5 + 2(a2) - a4. a4 is an integer between 1 and 3. When a2 is 0, preferably a3 is an integer between 0 and 3 and a4 is an integer between 1 and 3. When a2 is 1 or 2, preferably a3 is an integer between 0 and 4 and a4 is an integer between 1 and 3.

[0138] In formula (B1), R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0139] In formula (B1), R 11 This is a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom. The saturated hydrocarbyl group, and the saturated hydrocarbyl portion of the saturated hydrocarbyloxy group and saturated hydrocarbylcarbonyloxy group, may be linear, branched, or cyclic. Specific examples include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, butyl, pentyl, hexyl, and their structural isomers; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl; and groups obtained by combining these. If the number of carbon atoms is below the upper limit, solubility in alkaline developer is good. When a3 is 2 or more, each R 11 They may be the same as or different from each other.

[0140] In formula (B1), A 1This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and some of the -CH2- in the saturated hydrocarbylene group may be substituted with -O-. The saturated hydrocarbylene group may be linear, branched, or cyclic, and specific examples include alkanediyl groups having 1 to 10 carbon atoms such as methylene group, ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, and structural isomers thereof; cyclic saturated hydrocarbylene groups having 3 to 10 carbon atoms such as cyclopropanediyl group, cyclobutanediyl group, cyclopentanediyl group, and cyclohexanediyl group; and groups obtained by combining these. If the saturated hydrocarbylene group contains an ether bond, when a1 in formula (B1) is 1, it may be placed at any position other than between the α-carbon atom and the β-carbon atom with respect to the ester oxygen atom. Furthermore, when a1 is 0, the atom bonded to the main chain becomes an etheric oxygen atom, and the second ether bond may be inserted at any position other than between the α-carbon and β-carbon atoms relative to the etheric oxygen atom. It is preferable that the saturated hydrocarbylene group has 10 or fewer carbon atoms, as this allows for sufficient solubility in alkaline developing solutions.

[0141] a1 is 0 and A 1 When it is a single bond, that is, the aromatic ring is directly bonded to the main chain of the polymer (i.e., a linker (-C(=O)-OA) 1 If the repeating unit B1 does not have the -), preferred examples of the repeating unit B1 include units derived from 3-hydroxystyrene, 4-hydroxystyrene, 5-hydroxy-2-vinylnaphthalene, 6-hydroxy-2-vinylnaphthalene, etc. In particular, the repeating unit represented by the following formula (B1-1) is preferred. [ka] (In the formula, R A (and a4 are the same as above.)

[0142] a1 is 1 (i.e., -C(=O)-OA as the linker) 1When R has -, preferred examples of repeating unit B1 are, but are not limited to, those shown below. Note that in the following formula, A This is the same as described above. [ka]

[0143] The content of repeating unit B1 is preferably 10 to 95 mol%, and more preferably 40 to 90 mol%, of the total repeating units constituting the polymer. However, if the polymer described later includes at least one of the repeating units represented by formula (B3) and formula (B4) that provide high etching resistance, and that unit has a phenolic hydroxyl group as a substituent, it is preferable to include the ratio of that unit as well within the above range. Repeating unit B1 may be used alone or in combination of two or more types.

[0144] The polymer preferably contains repeating units having acidic functional groups protected by acid-unstable groups, i.e., repeating units protected by acid-unstable groups that become alkali-soluble upon the action of acid (hereinafter also referred to as repeating unit B2), in order to provide the positive-type resist composition with the property that the exposed area dissolves in an alkaline developer. In this case, the acid-unstable groups (protecting groups) in the repeating units undergo a deprotection reaction upon the action of acid, so that the polymer exhibits better solubility in an alkaline developer.

[0145] The most preferred repeating unit B2 is the one represented by the following formula (B2-1) (hereinafter also referred to as repeating unit B2-1). [ka]

[0146] In formula (B2-1), b1 is 0 or 1. b2 is an integer between 0 and 2, where 0 represents the benzene skeleton, 1 represents the naphthalene skeleton, and 2 represents the anthracene skeleton. b3 is an integer satisfying 0 ≤ b3 ≤ 5 + 2(b2) - b4. b4 is an integer between 1 and 3. b5 is 0 or 1. When b2 is 0, preferably b3 is an integer between 0 and 3 and b4 is an integer between 1 and 3. When b2 is 1 or 2, preferably b3 is an integer between 0 and 4 and b4 is an integer between 1 and 3.

[0147] In formula (B2-1), R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0148] In formula (B2-1), R 12 This is a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom. The saturated hydrocarbyl group, and the saturated hydrocarbyl portion of the saturated hydrocarbyloxy group and saturated hydrocarbylcarbonyloxy group may be linear, branched, or cyclic. Specific examples include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, butyl, pentyl, hexyl, and their structural isomers; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl; and groups obtained by combining these. If the number of carbon atoms is below the upper limit, solubility in alkaline developer is good. When b3 is 2 or more, each R 12 They may be the same as or different from each other.

[0149] In formula (B2-1), A 2This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and some of the -CH2- in the saturated hydrocarbylene group may be substituted with -O-. The saturated hydrocarbylene group may be linear, branched, or cyclic, and specific examples include alkanediyl groups having 1 to 10 carbon atoms such as methylene group, ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, and structural isomers thereof; cyclic saturated hydrocarbylene groups having 3 to 10 carbon atoms such as cyclopropanediyl group, cyclobutanediyl group, cyclopentanediyl group, and cyclohexanediyl group; and groups obtained by combining these. When the saturated hydrocarbylene group contains an ether bond, when b1 in formula (B2-1) is 1, it may be placed at any position other than between the α-carbon and β-carbon atoms relative to the ester oxygen atom. Furthermore, when b1 is 0, the atom bonded to the main chain becomes an etheric oxygen atom, and the second ether bond may be inserted at any position other than between the α-carbon and β-carbon atoms relative to the etheric oxygen atom. It is preferable that the saturated hydrocarbylene group has 10 or fewer carbon atoms, as this allows for sufficient solubility in alkaline developing solutions.

[0150] In formula (B2-1), X is an acid-unstable group when b4 is 1, and a hydrogen atom or an acid-unstable group when b4 is 2 or more, but at least one is an acid-unstable group. That is, the repeating unit B2-1 is a phenolic hydroxyl group attached to an aromatic ring, at least one of which is protected by an acid-unstable group, or a carboxyl group attached to an aromatic ring is protected by an acid-unstable group. The acid-unstable group can be any that is removed by acid to give an acidic group, which has been used in many chemically amplified resist compositions that are already known, and is not particularly limited. A specific example of the acid-unstable group is R in the explanation of formula (A1). 1Examples of acid-unstable groups represented by the formula are similar to those exemplified above. Furthermore, other examples of acid-unstable groups include those in which the hydrogen atom of a phenolic hydroxyl group is substituted with -CH2COO- (tertiary saturated hydrocarbyl group). In this case, the same tertiary saturated hydrocarbyl group used for protecting the phenolic hydroxyl group as described above can be used.

[0151] Furthermore, as a repeating unit B2, a repeating unit represented by the following formula (B2-2) (hereinafter also referred to as repeating unit B2-2) can be mentioned. Repeating unit B2-2 is a useful option as an acid-unstable group-containing unit that provides good performance against line width fluctuations during development loading because it increases the dissolution rate of the exposed area. [ka]

[0152] In equation (B2-2), c1 is an integer between 0 and 2. c2 is an integer between 0 and 2. c3 is an integer between 0 and 5. c4 is an integer between 0 and 2.

[0153] In formula (B2-2), R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0154] In formula (B2-2), R 13 and R 14 Each of these is independently a hydrocarbyl group having 1 to 10 carbon atoms, which may contain heteroatoms, and R 13 and R 14 These elements may bond with each other to form a ring with the carbon atoms to which they are bonded.

[0155] In formula (B2-2), R 15 Each of these is independently a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, or a fluorinated alkoxy group having 1 to 5 carbon atoms.

[0156] In formula (B2-2), R 16Each of these is independently a hydrocarbyl group having 1 to 10 carbon atoms, which may contain heteroatoms.

[0157] In formula (B2-2), A 3 This refers to a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OA 31 - is A 31 This is an aliphatic hydrocarbylene group having 1 to 20 carbon atoms, which may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring, or a phenylene group or naphthylene group. * indicates a bond with a carbon atom of the main chain.

[0158] Preferred examples of repeating unit B2-2 are, but are not limited to, those shown below. Note that in the following formula, R A This is the same as described above. [ka]

[0159] The content of repeating unit B2 is preferably 5 to 50 mol% of the total repeating units constituting the polymer. Repeating unit B2 may be used alone or in combination of two or more types.

[0160] The polymer may further contain at least one repeating unit selected from the following formulas: (B3) (hereinafter also referred to as repeating unit B3), (B4) (hereinafter also referred to as repeating unit B4), and (B5) (hereinafter also referred to as repeating unit B5). [ka]

[0161] In equations (B3) and (B4), d and e are each independent integers between 0 and 4.

[0162] In formulas (B3) and (B4), R 21 and R 22Each of these is independently a hydroxyl group, a halogen atom, a saturated hydrocarbyl group having 1 to 8 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 8 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, and saturated hydrocarbylcarbonyloxy group may be linear, branched, or cyclic. When d is 2 or more, each R 21 They may be the same or different from each other. When e is 2 or greater, each R 22 They may be the same as or different from each other.

[0163] In formula (B5), f1 is 0 or 1. f2 is an integer between 0 and 2, where 0 represents a benzene skeleton, 1 represents a naphthalene skeleton, and 2 represents an anthracene skeleton. f3 is an integer between 0 and 5. When f2 is 0, f3 is preferably an integer between 0 and 3, and when f2 is 1 or 2, f3 is preferably an integer between 0 and 4.

[0164] In formula (B5), R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0165] In formula (B5), R 23The saturated hydrocarbyl group is a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbyloxyhydrocarbyl group having 2 to 20 carbon atoms, a saturated hydrocarbylthiohydrocarbyl group having 2 to 20 carbon atoms, a halogen atom, a nitro group, a cyano group, a saturated hydrocarbylsulfinyl group having 1 to 20 carbon atoms, or a saturated hydrocarbylsulfonyl group having 1 to 20 carbon atoms. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, saturated hydrocarbyloxyhydrocarbyl group, saturated hydrocarbylthiohydrocarbyl group, saturated hydrocarbylsulfinyl group, and saturated hydrocarbylsulfonyl group may be linear, branched, or cyclic. When f3 is 2 or more, each R 23 They may be the same as or different from each other.

[0166] R 23 Preferred groups include halogen atoms such as chlorine, bromine, and iodine; saturated hydrocarbyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopentyl, and cyclohexyl groups, and their structural isomers; and saturated hydrocarbyl groups such as methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, cyclopentyloxy, and cyclohexyloxy groups, and their structural isomers of the hydrocarbon portion. Of these, methoxy and ethoxy groups are particularly useful.

[0167] Furthermore, saturated hydrocarbyl carbonyloxy groups can be easily introduced by chemical modification even after polymer polymerization and can be used to fine-tune the solubility of the base polymer in alkaline developers. Examples of saturated hydrocarbyl carbonyloxy groups include methyl carbonyloxy, ethyl carbonyloxy, propyl carbonyloxy, butyl carbonyloxy, pentyl carbonyloxy, hexyl carbonyloxy, cyclopentyl carbonyloxy, cyclohexyl carbonyloxy, benzoyloxy, and structural isomers of their hydrocarbon portions. If the number of carbon atoms is 20 or less, the effect of controlling and adjusting the solubility of the base polymer in alkaline developers (mainly reducing it) can be appropriately achieved, and the occurrence of scum (development defects) can be suppressed.

[0168] Among the preferred substituents mentioned above, those that are particularly easy to prepare as monomers and are useful include chlorine atoms, bromine atoms, iodine atoms, methyl groups, ethyl groups, and methoxy groups.

[0169] In formula (B5), A 4This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and some of the -CH2- in the saturated hydrocarbylene group may be substituted with -O-. The saturated hydrocarbylene group may be linear, branched, or cyclic, and specific examples include alkanediyl groups having 1 to 10 carbon atoms such as methylene group, ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, and structural isomers thereof; cyclic saturated hydrocarbylene groups having 3 to 10 carbon atoms such as cyclopropanediyl group, cyclobutanediyl group, cyclopentanediyl group, and cyclohexanediyl group; and groups obtained by combining these. If the saturated hydrocarbylene group contains an ether bond, when f1 in formula (B5) is 1, it may be placed at any position other than between the α-carbon and β-carbon atoms relative to the ester oxygen atom. Furthermore, when f1 is 0, the atom bonded to the main chain becomes an etheric oxygen atom, and the second ether bond may be inserted at any position other than between the α-carbon and β-carbon atoms relative to the etheric oxygen atom. It is preferable that the saturated hydrocarbylene group has 10 or fewer carbon atoms, as this allows for sufficient solubility in alkaline developing solutions.

[0170] f1 is 0 and A 4 If it is a single bond, that is, the aromatic ring is directly bonded to the main chain of the polymer (i.e., a linker (-C(=O)-OA) 4 If the repeating unit B5 does not have a (-), preferred examples of the repeating unit B5 include units derived from styrene, 4-chlorostyrene, 4-methylstyrene, 4-methoxystyrene, 4-bromostyrene, 4-acetoxystyrene, 2-hydroxypropylstyrene, 2-vinylnaphthalene, 3-vinylnaphthalene, etc.

[0171] Also, when f1 is 1 (i.e., -C(=O)-OA as the linker), 4 (If - is present), preferred examples of repeating unit B5 are, but are not limited to, those listed below. Note that in the following formula, R A This is the same as described above. [ka]

[0172] [ka]

[0173] When at least one of the repeating units B3 to B5 is used as a constituent unit of the polymer, in addition to the etching resistance of the aromatic ring, the addition of a ring structure to the main chain enhances etching resistance and EB irradiation resistance during pattern inspection.

[0174] To obtain the effect of improving etching resistance, the content of repeating units B3 to B5 is preferably 5 mol% or more of the total repeating units constituting the polymer. Furthermore, the content of repeating units B3 to B5 is preferably 35 mol% or less, and more preferably 30 mol% or less of the total repeating units constituting the polymer. If the amount introduced when there is no functional group or when the functional group is not a hydroxyl group is 35 mol% or less, it is preferable because there is no risk of development defects occurring. Repeating units B3 to B5 may be used individually or in combination of two or more types.

[0175] The polymer preferably contains at least one repeating unit selected from repeating units B1, B2, and B3 to B5, as this is advantageous in achieving both high etching resistance and high resolution. In this case, it is preferable that these repeating units make up 60 mol% or more of the total repeating units constituting the polymer, more preferably 70 mol% or more, and even more preferably 80 mol% or more.

[0176] The polymer may further contain at least one selected from the repeating units represented by the following formula (B6) (hereinafter also referred to as repeating unit B6), the following formula (B7) (hereinafter also referred to as repeating unit B7), the following formula (B8) (hereinafter also referred to as repeating unit B8), the following formula (B9) (hereinafter also referred to as repeating unit B9), the following formula (B10) (hereinafter also referred to as repeating unit B10), the following formula (B11) (hereinafter also referred to as repeating unit B11), the following formula (B12) (hereinafter also referred to as repeating unit B12), and the following formula (B13) (hereinafter also referred to as repeating unit B13). In this case, acid diffusion can be effectively suppressed, and a pattern with improved resolution and reduced LER can be obtained. [ka]

[0177] In formulas (B6) to (B13), R B Each of these is independently either a hydrogen atom or a methyl group. 1 This refers to a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, or *-OY 11 -, *-C(=O)-OY 11 -or *-C(=O)-NH-Y 11 - and Y 11 This is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. 2 is a single bond or **-Y 21 -C(=O)-O- and Y 21 This is a hydroxylene group having 1 to 20 carbon atoms, which may contain heteroatoms. 3This includes single bonds, methylene groups, ethylene groups, phenylene groups, fluorinated phenylene groups, trifluoromethyl groups, and phenylene groups substituted with *-OY 31 -, *-C(=O)-OY 31 - or *-C(=O)-NH-Y 31 - is Y 31 This is a C1-C6 aliphatic hydrocarbylene group, phenylene group, fluorinated phenylene group, phenylene group substituted with a trifluoromethyl group, or a C7-C20 group obtained by combining these, and may contain a carbonyl group, ester bond, ether bond, or hydroxyl group. * represents a bond with a carbon atom of the main chain, and ** represents a bond with an oxygen atom in the formula. Y 4 This is a hydroxylene group having 1 to 30 carbon atoms, which may contain single bonds or heteroatoms. g1 and g2 are independently 0 or 1, but Y 4 When it is a single bond, g1 and g2 are 0.

[0178] In equations (B6) and (B10), Xa - Xa is a non-nucleophilic counterion. - Examples of non-nucleophilic counterions represented by include those described in Japanese Patent Publication No. 2010-113209 and Japanese Patent Publication No. 2007-145797.

[0179] In formulas (B7) and (B11), Y 2 ga-Y 21 When -C(=O)-O-, Y 21 Examples of hydrocarbylene groups that may contain a heteroatom represented by the following are, but are not limited to, those listed below. [ka] (In the equation, dashed lines represent connections.)

[0180] In formulas (B7) and (B11), R HF is a hydrogen atom or a trifluoromethyl group. In repeating units B7 and B11, R HFA specific example of the case where is a hydrogen atom is described in Japanese Patent Publication No. 2010-116550, and R HF Specific examples of cases where is a trifluoromethyl group include those described in Japanese Patent Publication No. 2010-77404. Examples of repeating units B8 and B12 include those described in Japanese Patent Publication No. 2012-246265 and Japanese Patent Publication No. 2012-246426.

[0181] Preferred examples of monomer anions that give repeating units B9 or B13 include, but are not limited to, those listed below. [ka]

[0182] [ka]

[0183] In formulas (B6) to (B13), R 31 ~R 48 Each of these is a hydrocarbyl group having 1 to 20 carbon atoms, which may independently contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples of the halogen atom and hydrocarbyl group are given in the explanation of formulas (cation-1) to (cation-3) as R c1 ~R c9Examples of halogen atoms and hydrocarbyl groups represented by the symbols are similar to those exemplified. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the -CH2- groups of the hydrocarbyl group may be substituted with a group containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, the group may contain hydroxyl groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, nitro groups, carbonyl groups, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic acid anhydrides (-C(=O)-OC(=O)-), haloalkyl groups, etc.

[0184] Also, R 31 and R 32 However, they may bond to each other and form a ring with the sulfur atom to which they are bonded, R 33 and R 34 , R 36 and R 37 , or R 39 and R 40 However, these may bond with each other and form a ring together with the sulfur atom to which they are bonded. In this case, the ring formed is R as described in the explanation of formula (cation-1). c1 and R c2 Examples similar to those exemplified include rings that can be formed when these elements bond to each other, together with the sulfur atoms to which they bond.

[0185] Furthermore, specific examples of sulfonium cations in repeating units B7 to B9 are the same as those exemplified as the sulfonium cation represented by formula (cation-1). Specific examples of iodonium cations in repeating units B11 to B13 are the same as those exemplified as the iodonium cation represented by formula (cation-2).

[0186] Repeating units B6 to B13 are units that generate acid upon irradiation with high-energy rays. It is believed that the inclusion of these units in the polymer moderately suppresses acid diffusion, resulting in patterns with improved LER and CDU. Furthermore, the inclusion of these units in the polymer suppresses the phenomenon of acid volatilizing from the exposed areas and re-adhering to the unexposed areas during baking in a vacuum, which is thought to be effective in improving LER and CDU, and reducing pattern defects by suppressing unwanted deprotection reactions in the unexposed areas.

[0187] If the polymer contains repeating units B6 to B13, the content of these units is preferably 0.5 to 30 mol% of the total repeating units constituting the polymer. Repeating units B6 to B13 may be used individually or in combination of two or more types.

[0188] (B) The base polymer may be a mixture of a polymer containing repeating unit B1 and at least one selected from repeating units B6 to B13, and a polymer containing repeating unit B1 but not repeating units B6 to B13. In this case, the content of the polymer not containing repeating units B6 to B13 is preferably 2 to 5000 parts by mass, and more preferably 10 to 1000 parts by mass, per 100 parts by mass of the polymer containing repeating units B6 to B13.

[0189] The polymer may contain commonly used (meth)acrylic acid ester units protected by acid-unstable groups, or (meth)acrylic acid ester units having adhesive groups such as lactone structures or hydroxyl groups other than phenolic hydroxyl groups. While these repeating units allow for fine-tuning of the properties of the resist film, they are not required to be included.

[0190] Examples of (meth)acrylic acid ester units having the aforementioned adhesive group include the repeating unit represented by the following formula (B14) (hereinafter also referred to as repeating unit B14), the repeating unit represented by the following formula (B15) (hereinafter also referred to as repeating unit B15), and the repeating unit represented by the following formula (B16) (hereinafter also referred to as repeating unit B16). These units do not exhibit acidity and can be used auxiliaryly as units that provide adhesion to the substrate or as units that adjust solubility. [ka]

[0191] In formulas (B14) to (B16), R A These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 51 R is either an -O- or a methylene group. 52 R is a hydrogen atom or a hydroxyl group. 53 k is a saturated hydrocarbyl group having 1 to 4 carbon atoms. k is an integer from 0 to 3.

[0192] When repeating units B14 to B16 are included, their content is preferably 0 to 30 mol%, and more preferably 0 to 20 mol%, of the total repeating units constituting the polymer. Repeating units B14 to B16 may be used individually or in combination of two or more types.

[0193] The aforementioned polymer can be synthesized by copolymerizing each monomer, which is optionally protected with a protecting group, using known methods, and then performing a deprotection reaction as necessary. The copolymerization reaction is not particularly limited, but radical polymerization and anionic polymerization are preferred. For these methods, refer to Japanese Patent Application Publication No. 2004-115630.

[0194] The polymer preferably has a weight-average molecular weight (Mw) of 1,000 to 50,000, and more preferably 2,000 to 20,000. If Mw is 1,000 or more, there is no risk of phenomena such as the pattern heads becoming rounded, reducing resolution, and LER and CDU degrading, as is conventionally known. On the other hand, if Mw is 50,000 or less, there is no risk of LER and CDU degradation, especially when forming patterns with a pattern line width of 100 nm or less. In this invention, Mw is a polystyrene-converted measurement value obtained by gel permeation chromatography (GPC) using tetrahydrofuran (THF) or dimethylformamide (DMF) as a solvent.

[0195] The polymer preferably has a narrow dispersion with a molecular weight distribution (Mw / Mn) of 1.0 to 2.0, and particularly 1.0 to 1.8. When the dispersion is narrow in this way, after development, no foreign matter will be generated on the pattern, and the shape of the pattern will not deteriorate.

[0196] [(C) Photoacid Generator] The chemically amplified positive resist composition of the present invention may contain a photoacid generator as component (C). The photoacid generator is not particularly limited as long as it is a compound that generates acid upon irradiation with high-energy rays. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxiimide, oxime-O-sulfonate type acid generators, and the like.

[0197] Specific examples of the photoacid generator include nonafluorobutanesulfonate, partially fluorinated sulfonates described in paragraphs

[0247] to

[0251] of Japanese Patent Publication No. 2012-189977, partially fluorinated sulfonates described in paragraphs

[0261] to

[0265] of Japanese Patent Publication No. 2013-101271, paragraphs

[0122] to

[0142] of Japanese Patent Publication No. 2008-111103, and those described in paragraphs

[0080] to

[0081] of Japanese Patent Publication No. 2010-215608. Among these, aryl sulfonate type or alkanesulfonate type photoacid generators are preferred because they generate an acid of appropriate strength for deprotecting the acid-unstable group of repeating unit B2.

[0198] Furthermore, in order to obtain the effect of improving LER and CDU by combining the photoacid generator with the quencher of component (A), the pKa of the acid generated from the photoacid generator is -3.0 or higher, preferably in the range of -3.0 to 2.0, and more preferably in the range of -2.0 to 1.5.

[0199] As the photoacid generator, salt compounds having the anions shown below are preferred. [ka]

[0200] [ka]

[0201] [ka]

[0202] [ka]

[0203] [ka]

[0204] [ka]

[0205] [ka]

[0206] [ka]

[0207] Examples of cations that pair with the aforementioned anion include the sulfonium cation represented by formula (cation-1) and the iodonium cation represented by formula (cation-2).

[0208] If the chemically amplified positive resist composition of the present invention contains (C) a photoacid generator, its content is preferably 1 to 30 parts by mass, and more preferably 2 to 20 parts by mass, per 80 parts by mass of (B) the base polymer. If the base polymer contains repeating units B6 to B13 (i.e., if it is a polymer-bound type acid generator), the inclusion of (C) the photoacid generator may be omitted. (C) The photoacid generator may be used alone or in combination of two or more types.

[0209] When the chemically amplified positive resist composition of the present invention contains a quencher of component (A) and a photoacid generator of component (C), it is preferable that the content ratio of the photoacid generator to the quencher ((C) / (A)) is less than 6 by mass, more preferably less than 5, and even more preferably less than 4. If the content ratio of the photoacid generator to the quencher in the chemically amplified positive resist composition is within the above range, it becomes possible to sufficiently suppress acid diffusion and obtain excellent resolution and dimensional uniformity.

[0210] [(D) Fluorine atom-containing polymer] The chemically amplified positive resist composition of the present invention may contain a fluorine atom-containing polymer as component (D) for the purpose of increasing contrast, suppressing chemical flare of acids during high-energy ray irradiation, shielding from acid mixing from the antistatic film during the process of coating the resist film with an antistatic film material, and suppressing unexpected and unwanted pattern degradation. This polymer may further contain at least one selected from repeating units represented by the following formula (D1) (hereinafter also referred to as repeating unit D1), repeating units represented by the following formula (D2) (hereinafter also referred to as repeating unit D2), repeating units represented by the following formula (D3) (hereinafter also referred to as repeating unit D3), and repeating units represented by the following formula (D4) (hereinafter also referred to as repeating unit D4), and may further contain at least one selected from repeating units represented by the following formula (D5) (hereinafter also referred to as repeating unit D5) and repeating units represented by the following formula (D6) (hereinafter also referred to as repeating unit D6). Since the fluorine atom-containing polymer also functions as a surfactant, it can prevent the re-adhesion of insoluble substances to the substrate that may occur during the development process, thus also exhibiting an effect against development defects. [ka]

[0211] In equations (D1) to (D6), x is an integer between 1 and 3. y is an integer satisfying 0 ≤ y ≤ 5 + 2z - x. z is either 0 or 1. h is an integer between 1 and 3. R C These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. D Each of these is independently either a hydrogen atom or a methyl group. 101 , R 102 , R 104 and R 105 Each of these is independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. 103 , R 106 , R 107 and R 108 Each of these is independently a hydrogen atom, a C1-C15 hydrocarbyl group, a C1-C15 fluorinated hydrocarbyl group, or an acid-unstable group, and R103 , R 106 , R 107 and R 108 When is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be interposed between the carbon-carbon bonds. 109 This is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, which may have a hydrogen atom or a group containing a heteroatom between the carbon-carbon bonds. 110 This is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, which may have a heteroatom interposed between the carbon-carbon bonds. 111 This is a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, and a portion of the -CH2- of the saturated hydrocarbyl group may be substituted with an ester bond or an ether bond. 1 This is a (h+1) valent hydrocarbon group having 1 to 20 carbon atoms or a (h+1) valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. 2 The bond is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond with a carbon atom in the main chain. 3 This is a single bond, -O-, *-C(=O)-OZ 31 -Z 32 -or *-C(=O)-NH-Z 31 -Z 32 - is Z 31 This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. 32 A is a single bond, ester bond, ether bond, or sulfonamide bond. * indicates a bond with a carbon atom of the main chain.

[0212] In equations (D1) and (D2), R 101 , R 102 , R 104 and R 105The saturated hydrocarbyl group having 1 to 10 carbon atoms, represented by , may be linear, branched, or cyclic. Specific examples 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 groups; and cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, and norbornyl groups. Of these, saturated hydrocarbyl groups having 1 to 6 carbon atoms are preferred.

[0213] In formulas (D1) to (D4), R 103 , R 106 , R 107 and R 108 The C1-C15 hydrocarbyl group represented by can be linear, branched, or cyclic. Specific examples include C1-C15 alkyl groups, C2-C15 alkenyl groups, and C2-C15 alkynyl groups, but C1-C15 alkyl groups are preferred. Examples of alkyl groups include, in addition to those mentioned above, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, and n-pentadecyl groups. Fluorinated hydrocarbyl groups include groups in which some or all of the hydrogen atoms bonded to the carbon atoms of the hydrocarbyl group mentioned above are substituted with fluorine atoms.

[0214] In formula (D4), Z 1 Examples of (h+1) valent hydrocarbon groups having 1 to 20 carbon atoms, represented by , include alkyl groups having 1 to 20 carbon atoms or cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms from which h hydrogen atoms have been removed. Also, Z 1Examples of (h+1) valent fluorinated hydrocarbon groups having 1 to 20 carbon atoms, as represented by the formula, include groups in which at least one hydrogen atom of the aforementioned (h+1) valent hydrocarbon group is substituted with a fluorine atom.

[0215] Specific examples of repeating units D1 to D4 are shown below, but are not limited to these. Note that in the following formula, R C This is the same as described above. [ka]

[0216] [ka]

[0217] [ka]

[0218] In formula (D5), R 109 and R 110 Examples of C1-C5 hydrocarbyl groups represented by include alkyl groups, alkenyl groups, and alkynyl groups, but alkyl groups are preferred. Examples of alkyl groups include methyl groups, ethyl groups, n-propyl groups, isopropyl groups, n-butyl groups, isobutyl groups, sec-butyl groups, and n-pentyl groups. In addition, a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom may be interposed between the carbon-carbon bonds of the hydrocarbyl group.

[0219] In formula (D5), -OR 109 It is preferable that R is a hydrophilic group. In this case, R 109 Preferred elements include hydrogen atoms, C1-C5 alkyl groups with oxygen atoms interposed between carbon-carbon bonds, etc.

[0220] In formula (D5), Z 2 It is preferable that *-C(=O)-O- or *-C(=O)-NH-. Furthermore, R DIt is preferable that it is a methyl group. 2 The presence of a carbonyl group improves the acid trapping ability derived from the antistatic film. Also, R D When the group is a methyl group, a more rigid polymer with a higher glass transition temperature (Tg) is formed, thus suppressing acid diffusion. This results in good temporal stability of the resist film, and the resolution and pattern shape do not deteriorate.

[0221] The repeating unit D5 can be, but is not limited to, the following. Note that in the following formula, R D This is the same as described above. [ka]

[0222] [ka]

[0223] In formula (D6), Z 3 The saturated hydrocarbylene group having 1 to 10 carbon atoms, represented by , may be linear, branched, or cyclic. Specific examples include methanediyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, propane-1,3-diyl group, propane-2,2-diyl group, butane-1,1-diyl group, butane-1,2-diyl group, butane-1,3-diyl group, butane-2,3-diyl group, butane-1,4-diyl group, and 1,1-dimethylethane-1,2-diyl group.

[0224] In formula (D6), R 111 A saturated hydrocarbyl group having 1 to 20 carbon atoms, represented by , in which at least one hydrogen atom is substituted with a fluorine atom, may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 20 carbon atoms or cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom.

[0225] The repeating unit D6 can be, but is not limited to, the following. Note that in the following formula, R D This is the same as described above. [ka]

[0226] [ka]

[0227] [ka]

[0228] [ka]

[0229] The content of repeating units D1 to D4 is preferably 15 to 95 mol%, and more preferably 20 to 85 mol%, of the total repeating units of the fluorine atom-containing polymer. The content of repeating units D5 and / or D6 is preferably 5 to 85 mol%, and more preferably 15 to 80 mol%, of the total repeating units of the fluorine atom-containing polymer. Repeating units D1 to D6 may be used individually or in combination of two or more types.

[0230] The fluorine atom-containing polymer may contain other repeating units besides those described above. Examples of such repeating units include those described in paragraphs

[0046] to

[0078] of Japanese Patent Application Publication No. 2014-177407. If the fluorine atom-containing polymer contains other repeating units, the content thereof is preferably 50 mol% or less of the total repeating units of the fluorine atom-containing polymer.

[0231] The aforementioned fluorine atom-containing polymer can be synthesized by copolymerizing each monomer, which is optionally protected with a protecting group, using known methods, and then performing a deprotection reaction as necessary. The copolymerization reaction is not particularly limited, but radical polymerization and anionic polymerization are preferred. For these methods, refer to Japanese Patent Application Publication No. 2004-115630.

[0232] The Mw of the fluorine atom-containing polymer is preferably 2000 to 50000, and more preferably 3000 to 20000. If the Mw is less than 2000, it may promote acid diffusion, leading to a deterioration in resolution and impaired stability over time. If the Mw is too high, the solubility in the solvent will decrease, potentially causing coating defects. Furthermore, the Mw / Mn of the fluorine atom-containing polymer is preferably 1.0 to 2.2, and more preferably 1.0 to 1.7.

[0233] When the chemically amplified positive resist composition of the present invention contains (D) a fluorine atom-containing polymer, its content is preferably 0.01 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, and even more preferably 0.5 to 10 parts by mass, based on 80 parts by mass of (B) the base polymer. The (D) fluorine atom-containing polymer may be used alone or in combination of two or more types.

[0234] [(E) Organic solvents] The chemically amplified positive resist composition of the present invention may contain an organic solvent as component (E). The organic solvent is not particularly limited as long as it can dissolve each component. Examples of such organic solvents include ketones such as cyclohexanone, cyclopentanone, methyl-2-n-pentyl ketone, and 2-heptanone, as described in paragraphs

[0144] to

[0145] of Japanese Patent Application Publication No. 2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol; propylene glycol monomethyl ether (PGME), ethylene glycol monomethyl ether, propylene glycol monoethyl ether, and ethylene glycol monoethyl ether. Examples include ethers such as hydrate ethers, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate, ethyl lactate (EL), 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 γ-butyrolactone; and mixed solvents thereof. When using acetal-based acid-unstable groups, high-boiling point alcohol-based solvents, specifically diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, and 1,3-butanediol, can be added to accelerate the deprotection reaction of the acetal.

[0235] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, PGME, cyclohexanone, EL, γ-butyrolactone, and mixtures thereof are preferred.

[0236] If the chemically amplified positive resist composition of the present invention contains (E) an organic solvent, its content is preferably 200 to 10,000 parts by mass, and more preferably 400 to 5,000 parts by mass, per 80 parts by mass of the (B) base polymer. The (E) organic solvent may be used alone or as a mixture of two or more types.

[0237] [(F) Basic compounds] The chemically amplified positive resist composition of the present invention may also contain a basic compound (F) as a quencher other than component (A) for purposes such as correcting the shape of the pattern. By adding a basic compound, acid diffusion can be effectively controlled, and even when a substrate is used in which the outermost surface is made of a material containing chromium, tantalum, or silicon, the influence of the acid generated in the resist film on the substrate can be suppressed.

[0238] Numerous basic compounds are known, including primary, secondary, or tertiary aliphatic amines, hybrid amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxyl group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxyl group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amides, imides, carbamates, ammonium salts, and the like. Many specific examples of these are illustrated in Patent Document 9, but basically all of them can be used. Particularly preferred examples include tris[2-(methoxymethoxy)ethyl]amine, tris[2-(methoxymethoxy)ethyl]amine-N-oxide, dibutylaminobenzoic acid, morpholine derivatives, and imidazole derivatives.

[0239] If the chemically amplified positive resist composition of the present invention contains (F) a basic compound, its content is preferably 0 to 10 parts by mass, and more preferably 0 to 5 parts by mass, per 80 parts by mass of the (B) base polymer. The (F) basic compound may be used alone or in combination of two or more types.

[0240] [(G) Surfactants] The chemically amplified positive resist composition of the present invention may contain a commonly used surfactant to improve its applicability to the substrate. Many surfactants are known, as numerous examples are described in Japanese Patent Application Publication No. 2004-115630, and can be selected by referring to them. When the chemically amplified positive resist composition of the present invention contains a surfactant (G), its content is preferably 0 to 5 parts by mass per 80 parts by mass of the base polymer (B). The surfactant (G) may be used alone or in combination of two or more types.

[0241] [Method for forming a resist pattern] The resist pattern formation method of the present invention includes the steps of forming a resist film on a substrate using the chemically amplified positive-type resist composition described above, irradiating the resist film with a pattern using high-energy rays (i.e., exposing the resist film with high-energy rays), and developing the resist film irradiated with the pattern using an alkaline developer.

[0242] As the substrate, for example, substrates for integrated circuit manufacturing (Si, SiO, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective coatings, etc.) or substrates for transmissive or reflective mask circuit manufacturing (Cr, CrO, CrON, MoSi2, Si, SiO, SiO2, SiON, SiONC, CoTa, NiTa, TaBN, SnO2, etc.) can be used. The chemically amplified positive resist composition is applied to the substrate by a method such as spin coating to a film thickness of 0.03 to 2 μm, and this is pre-baked on a hot plate, preferably at 60 to 150°C for 1 to 20 minutes, more preferably at 80 to 140°C for 1 to 10 minutes, to form a resist film.

[0243] Next, the resist film is exposed using high-energy rays to irradiate a pattern. Examples of high-energy rays include ultraviolet light, far-ultraviolet light, excimer laser light (KrF, ArF, etc.), EUV, X-rays, gamma rays, synchrotron radiation, and EB. In the present invention, exposure using EUV or EB is preferred.

[0244] When using ultraviolet light, far ultraviolet light, excimer laser light, EUV, X-rays, gamma rays, or synchrotron radiation as the high-energy rays, a mask is used to form the desired pattern, and the exposure amount is preferably 1 to 500 mJ / cm². 2 More preferably 10 to 400 mJ / cm² 2 Irradiate in such a manner. When using an EB, direct exposure is preferred to form the desired pattern, with an exposure dose of 1 to 500 μC / cm². 2 More preferably 10-400 μC / cm² 2 Irradiate in such a way that it results in the following.

[0245] In addition to conventional exposure methods, immersion methods, which involve immersing the mask and the resist film in liquid, can also be used in some cases. In such cases, a water-insoluble protective film can be used.

[0246] Next, post-exposure baking (PEB) is performed on a hot plate, preferably at 60-150°C for 1-20 minutes, more preferably at 80-140°C for 1-10 minutes.

[0247] Subsequently, the substrate is developed using a developer solution of an alkaline aqueous solution such as tetramethylammonium hydroxide (TMAH) in an amount of 0.1 to 5% by mass, preferably 2 to 3% by mass, by conventional methods such as the dip method, puddle method, or spray method, preferably for 0.1 to 3 minutes, more preferably for 0.5 to 2 minutes, thereby forming the desired pattern on the substrate.

[0248] Furthermore, the chemically amplified positive resist composition of the present invention is particularly useful because it can form patterns with good resolution and low LER. In addition, the chemically amplified positive resist composition of the present invention is particularly useful for pattern formation on substrates having a surface material that is prone to pattern peeling or pattern collapse because it is difficult to achieve good adhesion of the resist pattern. Suitable substrates for this purpose include substrates in which a chromium compound containing one or more light elements selected from metallic chromium, oxygen, nitrogen, and carbon is sputtered onto the outermost surface, SiO, SiO x Examples include substrates containing tantalum compounds, molybdenum compounds, cobalt compounds, nickel compounds, tungsten compounds, and tin compounds in their outermost layer. The chemically amplified positive resist composition of the present invention is particularly useful for pattern formation using a photomask blank as the substrate. In this case, the photomask blank may be either a transmissive or reflective type.

[0249] As a transmissive mask blank, a photomask blank having a light-shielding film made of a chromium-based material may be a photomask blank for binary masks or a photomask blank for phase-shift masks. In the case of a photomask blank for binary masks, the light-shielding film may consist of an anti-reflective layer and a light-shielding layer made of a chromium-based material, or the entire anti-reflective film on the surface side, or only the surface side of the anti-reflective film on the surface side, may be made of a chromium-based material, and the remaining part may consist of a silicon-based compound material which may contain, for example, a transition metal. In the case of a photomask blank for phase-shift masks, a photomask blank for phase-shift masks having a chromium-based light-shielding film on the phase-shift film may be considered.

[0250] The aforementioned photomask blank having a chromium-based material on the outermost layer is very well known, as exemplified in Japanese Patent Publication No. 2008-26500, Japanese Patent Publication No. 2007-302873, or as prior art in those publications. A detailed explanation will be omitted, but for example, when constructing a light-shielding film having an anti-reflective layer and a light-shielding layer using a chromium-based material, the following film configuration can be used.

[0251] When forming a light-shielding film having an anti-reflective layer and a light-shielding layer using a chromium-based material, the layer configuration may be such that the anti-reflective layer and the light-shielding layer are laminated in that order from the surface side, or the anti-reflective layer, light-shielding layer, and anti-reflective layer are laminated in that order. Furthermore, the anti-reflective layer and the light-shielding layer may each be multilayered, and the composition may change discontinuously or continuously between layers with different compositions. As for the chromium-based material to be used, metallic chromium and materials containing light elements such as oxygen, nitrogen, and carbon in metallic chromium can be used. Specifically, metallic chromium, chromium oxide, chromium nitride, chromium carbide, chromium oxide nitride, chromium carbide nitride, chromium oxide nitride, chromium oxide nitride, etc. can be used.

[0252] Furthermore, a reflective mask blank comprises a substrate, a multilayer reflective film formed on one of the main surfaces (front side) of the substrate, specifically a multilayer reflective film that reflects exposure light such as EUV light, and an absorber film formed on the multilayer reflective film, specifically an absorber film that absorbs exposure light such as EUV light and reduces reflectivity. A reflective mask (EUV reflective mask) having an absorber pattern (pattern of the absorber film) formed by patterning the absorber film is manufactured from the reflective mask blank (EUV reflective mask blank). The wavelength of EUV light used in EUV lithography is 13-14 nm, and is usually light with a wavelength of about 13.5 nm.

[0253] The multilayer reflective film is usually preferably provided in contact with one of the main surfaces of the substrate, but it is also possible to provide an underlayer film between the substrate and the multilayer reflective film, provided that the effects of the present invention are not lost. The absorber film may be formed in contact with the multilayer reflective film, but a protective film (protective film for the multilayer reflective film) may be provided between the multilayer reflective film and the absorber film, preferably in contact with the multilayer reflective film, and more preferably in contact with both the multilayer reflective film and the absorber film. The protective film is used to protect the multilayer reflective film during processing such as cleaning and correction. Furthermore, it is preferable that the protective film has the function of protecting the multilayer reflective film when the absorber film is patterned by etching, and preventing oxidation of the multilayer reflective film. On the other hand, a conductive film used for electrostatically chucking the reflective mask to the exposure apparatus may be provided under the other main surface (back surface), which is the surface opposite to one of the main surfaces of the substrate, preferably in contact with the other main surface. Here, one main surface of the substrate is referred to as the front and upper side, and the other main surface as the back and lower side. However, the front and back sides and top and bottom are defined for convenience only, and the one main surface and the other main surface are either of the two main surfaces (film-forming surfaces) on the substrate, and the front and back sides and top and bottom are interchangeable. More specifically, it can be formed by methods such as those exemplified as prior art in Japanese Patent Application Publication No. 2021-139970 or therein.

[0254] According to the resist pattern formation method of the present invention, even when a substrate (e.g., a photomask blank) is used in which the outermost surface is made of a material that easily affects the resist pattern shape, such as a material containing chromium or silicon, the chemically amplified positive resist composition of the present invention efficiently controls acid diffusion at the substrate interface, thereby forming a pattern with high resolution and pattern fidelity, while improving LER and dose margin. [Examples]

[0255] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0256] [1] Preparation of chemically amplified positive resist compositions [Examples 1-1 to 1-40, Comparative Examples 1-1 to 1-8] Each component is dissolved in an organic solvent in the compositions shown in Tables 1-3 below, and the resulting solutions are filtered through UPE filters and / or nylon filters selected from sizes of 10 nm, 5 nm, 3 nm, and 1 nm to obtain chemically amplified positive resist compositions (R-1 to R-40, CR-1 to CR- 8 A mixture of 900 parts by mass of PGMEA, 1800 parts by mass of EL, and 1800 parts by mass of PGME was prepared.

[0257] [Table 1]

[0258] [Table 2]

[0259] [Table 3]

[0260] In Tables 1-3, the quenchers Q-1-Q-8, comparative quenchers cQ-1-cQ-3, polymers A-1-A-14, polymers P-1-P-5, photoacid generators PAG-A-PAG-D, and fluorine atom-containing polymers FP-1-FP-5 are as follows. Note that the copolymerization composition ratio of the polymers is expressed as a molar ratio, and Mw is the polystyrene equivalent measurement value obtained by GPC using THF or DMF as a solvent. [ka]

[0261] [ka]

[0262] [ka]

[0263] [ka]

[0264] [ka]

[0265] [ka]

[0266] [ka]

[0267] [ka]

[0268] [ka]

[0269] [2] EB lithography evaluation [Examples 2-1 to 2-40, Comparative Examples 2-1 to 2-8] Each chemically amplified positive resist composition (R-1 to R-40, CR-1 to CR-8) was spin-coated onto a 152 mm square mask blank, whose outermost surface was a silicon oxide film, which had been treated with hexamethyldisilazane (HMDS) vapor priming using ACT-M (manufactured by Tokyo Electron Limited). The blanks were then pre-baked on a hot plate at 110°C for 600 seconds to produce a resist film with a thickness of 80 nm. The thickness of the obtained resist films was measured using an optical measuring instrument, NanoSpec (manufactured by Nanometrics). Measurements were taken at 81 locations within the plane of the blank substrate, excluding the outer edge portion from the outer edge of the blank to 10 mm inward, and the average thickness and thickness range were calculated.

[0270] The images were exposed using an electron beam lithography system (EBM-5000plus, manufactured by Newflare Technology Co., Ltd., with an acceleration voltage of 50kV), subjected to PEB at 120°C for 600 seconds, and developed with a 2.38 mass% TMAH aqueous solution to obtain a positive-type pattern.

[0271] The obtained resist patterns were evaluated as follows: The fabricated patterned mask blanks were observed using an overhead SEM (scanning electron microscope), and the optimal exposure amount (μC / cm²) was determined to resolve 200 nm 1:1 line-and-space (LS) lines at a 1:1 ratio. 2 The resolution (limiting resolution) was defined as the minimum dimension at the exposure dose that resolves a 200nm LS at a 1:1 ratio. For the 200nm LS pattern obtained by irradiation with the optimal exposure dose, 80 edge detection points were performed on each of the 32 edges of the 200nm LS pattern using a SEM, and the value of three times the variation (standard deviation, σ) (3σ) was calculated and defined as LER (nm). In addition, the amount of CD change per 1 μC was determined from the dose curve when the exposure dose that resolves at a 1:1 ratio was used as the reference. The results are shown in Tables 4 to 6.

[0272] [Table 4]

[0273] [Table 5]

[0274] [Table 6]

[0275] The chemically amplified positive-type resist compositions (R-1 to R-40) of the present invention, which contain an onium salt represented by formula (A1), exhibited good resolution and good LER and dose margins compared to the comparative resist compositions (CR-1 to CR-8) due to effective acid diffusion control.

[0276] As described above, the chemically amplified positive resist composition of the present invention can be used to form patterns with extremely high resolution and good LER and dose margins. The resist pattern formation method using the chemically amplified positive resist composition of the present invention is useful for photolithography in semiconductor device manufacturing, particularly in the processing of transmissive or reflective mask blanks.

Claims

1. A chemically amplified positive resist composition comprising (A) a quencher consisting of an onium salt represented by the following formula (A1), and (B) a base polymer containing repeating units represented by the following formula (B1), which decomposes upon the action of an acid and increases in solubility in an alkaline developer. 【Chemistry 1】 (In the formula, X is a single bond, -O-, or -S-.) R 1 and R 2 Each of these is independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms, and the -CH of the hydrocarbyl group 2 A portion of the - may be replaced by -O- or -C(=O)-. Also, R 1 and R 2 However, they may bond with each other to form a ring with the carbon atoms to which they are bonded. R 3 is a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms when X is a single bond or -S-, and is a hydrocarbyl group having 1 to 10 carbon atoms other than an acid-labile group or an acid-labile group when X is -O-. Part or all of the hydrogen atoms of the hydrocarbyl group may be substituted with halogen atoms, and part of -CH 2 - of the hydrocarbyl group may be substituted with -O- or -C(=O)-, R 1 and R 3 may be bonded to each other to form a ring together with the atoms to which they are bonded and the atoms therebetween. However, when R 3 is other than an acid-labile group, the upper limit of the number of carbon atoms contained in R 1 to R 3 is 10. Z + This is an onium cation. 【Chemistry 2】 (In the formula, a1 is 0 or 1. a2 is an integer between 0 and 2. a3 is an integer satisfying 0 ≤ a3 ≤ 5 + 2(a2) - a4. a4 is an integer between 1 and 3.) R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 11 This is a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. A 1 This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the saturated hydrocarbylene group is -CH 2 (The - can be replaced with -O-.)

2. The chemically amplified positive resist composition according to claim 1, wherein X is -O-.

3. R 3 The chemically amplified positive resist composition according to claim 2, wherein the group is acid-unstable.

4. The chemically amplified positive resist composition according to claim 1, wherein the acid-unstable group is represented by the following formula (AL-1) or (AL-2). 【Transformation 3】 (In the formula, X a It is either -O- or -S-. R 4 , R 5 and R 6 Each of these is independently a hydrocarbyl group having 1 to 12 carbon atoms, and the -CH of the hydrocarbyl group 2 A portion of the - may be substituted with -O- or -S-, and if the hydrocarbyl group includes an aromatic ring, some or all of the hydrogen atoms of the aromatic ring may be substituted with a halogen atom, a cyano group, a nitro group, a C1-C4 alkyl group which may contain a halogen atom, or a C1-C4 alkoxy group which may contain a halogen atom. Also, R 4 , R 5 and R 6 Any two of these may bond to each other to form a ring, and the -CH of the ring 2 Some of the hyphens may be replaced with -O- or -S-. R 7 and R 8 Each of these is independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. 9 This is a hydrocarbyl group having 1 to 20 carbon atoms, and the -CH of the hydrocarbyl group 2 A portion of the - may be replaced with -O- or -S-. Also, R 8 and R 9 and are bonded to each other, and the carbon atoms and X that they are bonded to are bonded to each other. a Together, a heterocyclic group having 3 to 20 carbon atoms may be formed, and the -CH of the heterocyclic group 2 Some of the hyphens may be replaced with -O- or -S-. n1 and n2 are independently either 0 or 1. * represents a bond with an adjacent -O-.

5. Z + The chemically amplified positive resist composition according to claim 1, wherein the onium cation is represented by any of the following formulas (caten-1) to (caten-3). 【Chemistry 4】 (In the formula, R c1 ~R c9 Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain a halogen atom or a heteroatom. Also, R c1 and R c2 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded.

6. The chemically amplified positive resist composition according to claim 1, wherein the polymer further comprises repeating units represented by the following formula (B2-1). 【Transformation 5】 (In the formula, b1 is 0 or 1. b2 is an integer between 0 and 2. b3 is an integer satisfying 0 ≤ b3 ≤ 5 + 2(b2) - b4. b4 is an integer between 1 and 3. b5 is 0 or 1.) R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 12 This is a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom. A 2 This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the saturated hydrocarbylene group is -CH 2 The minus sign may be replaced by -O-. When b4 is 1, X is an acid-unstable group. When b4 is 2 or 3, X is independently either a hydrogen atom or an acid-unstable group, but at least one of them is an acid-unstable group.

7. The chemically amplified positive resist composition according to claim 1, wherein the polymer further comprises repeating units represented by the following formula (B2-2). 【Transformation 6】 (In the formula, c1 is an integer between 0 and 2. c2 is an integer between 0 and 2. c3 is an integer between 0 and 5. c4 is an integer between 0 and 2.) R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 13 and R 14 Each of these is independently a hydrocarbyl group having 1 to 10 carbon atoms, which may contain heteroatoms, and R 13 and R 14 These elements may bond with each other to form a ring with the carbon atoms to which they are bonded. R 15 Each of these is independently a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, or a fluorinated alkoxy group having 1 to 5 carbon atoms. R 16 Each of these is independently a hydrocarbyl group having 1 to 10 carbon atoms, which may contain heteroatoms. A 3 This refers to a single bond, a phenylene group, a naphthylene group, or *-C(=O)-O-A 31 - is true. A 31 This is an aliphatic hydrocarbylene group having 1 to 20 carbon atoms, which may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring, or a phenylene group or naphthylene group. * indicates a bond with a carbon atom of the main chain.

8. The chemically amplified positive resist composition according to claim 1, wherein the polymer further comprises at least one selected from repeating units represented by the following formula (B3), repeating units represented by the following formula (B4), and repeating units represented by the following formula (B5). 【Transformation 7】 (In the formula, d and e are each independent integers from 0 to 4. f1 is 0 or 1. f2 is an integer from 0 to 2. f3 is an integer from 0 to 5.) R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 21 and R 22 These are, independently, a hydroxyl group, a halogen atom, a saturated hydrocarbyl group having 1 to 8 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 8 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom. R 23 These are saturated hydrocarbyl groups having 1 to 20 carbon atoms, saturated hydrocarbyloxy groups having 1 to 20 carbon atoms, saturated hydrocarbylcarbonyloxy groups having 2 to 20 carbon atoms, saturated hydrocarbyloxyhydrocarbyl groups having 2 to 20 carbon atoms, saturated hydrocarbylthiohydrocarbyl groups having 2 to 20 carbon atoms, halogen atoms, nitro groups, cyano groups, saturated hydrocarbylsulfinyl groups having 1 to 20 carbon atoms, or saturated hydrocarbylsulfonyl groups having 1 to 20 carbon atoms. A 4 This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the saturated hydrocarbylene group is -CH 2 (The - can be replaced with -O-.)

9. The chemically amplified positive resist composition according to claim 1, wherein the polymer further comprises at least one selected from repeating units represented by the following formula (B6), repeating units represented by the following formula (B7), repeating units represented by the following formula (B8), repeating units represented by the following formula (B9), repeating units represented by the following formula (B10), repeating units represented by the following formula (B11), repeating units represented by the following formula (B12), and repeating units represented by the following formula (B13). 【Transformation 8】 (In the formula, R B Each of these is independently either a hydrogen atom or a methyl group. Y 1 This is a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, or *-O-Y 11 -, *-C(=O)-O-Y 11 - or * - C (= O) - NH - Y 11 - and Y 11 This is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. Y 2 is a single bond or **-Y 21 -C(=O)-O- and Y 21 This is a hydrocarbylene group having 1 to 20 carbon atoms, which may contain heteroatoms. Y 3 This includes single bonds, methylene groups, ethylene groups, phenylene groups, fluorinated phenylene groups, trifluoromethyl groups, and phenylene groups substituted with *-O-Y. 31 -, *-C(=O)-O-Y 31 - or * - C (= O) - NH - Y 31 - is Y 31 This refers to a C1-C6 aliphatic hydrocarbylene group, phenylene group, fluorinated phenylene group, phenylene group substituted with a trifluoromethyl group, or a C7-C20 group obtained by combining these, which may contain a carbonyl group, ester bond, ether bond, or hydroxyl group. * represents a bond with a carbon atom in the main chain, and ** represents a bond with an oxygen atom in the formula. Y 4 This is a hydroxylene group having 1 to 30 carbon atoms, which may contain single bonds or heteroatoms. g1 and g2 are independently either 0 or 1, but Y 4 When it is a single bond, g1 and g2 are 0. R 31 ~R 48 Each of these is independently a C1-C20 hydrocarbyl group which may contain a halogen atom or a heteroatom. 31 and R 32 However, they may bond to each other and form a ring with the sulfur atom to which they are bonded, R 33 and R 34 , R 36 and R 37 , or R 39 and R 40 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. R HF This is either a hydrogen atom or a trifluoromethyl group. Xa - (It is a non-nucleophilic counterion.)

10. The chemically amplified positive resist composition according to claim 1, wherein the content of repeating units having an aromatic ring skeleton among all repeating units of the polymer contained in the base polymer is 60 mol% or more.

11. Furthermore, the chemically amplified positive resist composition according to claim 1, further comprising (C) a photoacid generator.

12. The chemically amplified positive resist composition according to claim 11, wherein the acid strength (pKa) of the anion of the photoacid generator is -3.0 or higher.

13. The chemically amplified positive resist composition according to claim 11, wherein the content ratio of (C) photoacid generator to (A) quencher is less than 6 by mass.

14. Furthermore, the chemically amplified positive resist composition according to claim 1, comprising (D) a fluorine atom-containing polymer which comprises at least one selected from the repeating units represented by the following formula (D1), the repeating units represented by the following formula (D2), the repeating units represented by the following formula (D3), and the repeating units represented by the following formula (D4), and which may further comprise at least one selected from the repeating units represented by the following formula (D5) and the repeating units represented by the following formula (D6). 【Chemistry 9】 (In the formula, x is an integer between 1 and 3. y is an integer satisfying 0 ≤ y ≤ 5 + 2z - x. z is 0 or 1. h is an integer between 1 and 3.) R C These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R D is, independently of each other, a hydrogen atom or a methyl group. R 101 , R 102 , R 104 and R 105 Each of these is independently either a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 103 、 R 106 、 R 107 and R 108 are each independently a hydrogen atom, a hydrocarbyl group having 1 to 15 carbon atoms, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms or an acid-labile group, and when R 103 、 R 106 、 R 107 and R 108 are a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be interposed between carbon-carbon bonds. R 109 This is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, which may have a hydrogen atom or a group containing a heteroatom between the carbon-carbon bonds. R 110 This is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, which may have a group containing a heteroatom interposed between the carbon-carbon bonds. R 111 This is a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, and the saturated hydrocarbyl group is -CH 2 A portion of the - may be substituted with an ester bond or an ether bond. Z 1 This is a (h+1) valent hydrocarbon group having 1 to 20 carbon atoms or a (h+1) valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. Z 2 The bond is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. The asterisk (*) is a bond with a carbon atom in the main chain. Z 3 This is a single bond, -O-, *-C(=O)-O-Z 31 -Z 32 - or * - C (= O) - NH - Z 31 -Z 32 - is Z 31 This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. 32 A is a single bond, ester bond, ether bond, or sulfonamide bond. * indicates a bond to a carbon atom in the main chain.

15. Furthermore, the chemically amplified positive resist composition according to claim 1, further comprising (E) an organic solvent.

16. A method for forming a resist pattern, comprising the steps of: forming a resist film on a substrate using a chemically amplified positive-type resist composition according to any one of claims 1 to 15; irradiating the resist film with a pattern using a high-energy beam; and developing the resist film irradiated with the pattern using an alkaline developer.

17. The resist pattern formation method according to claim 16, wherein the high-energy ray is an extreme ultraviolet ray or an electron ray.

18. The resist pattern forming method according to claim 16, wherein the outermost surface of the substrate is made of a material containing at least one selected from chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten, and tin.

19. The resist pattern forming method according to claim 16, wherein the substrate is a transmissive or reflective mask blank.

20. A transmissive or reflective mask blank coated with the chemically amplified positive resist composition according to claim 1.

Images