Chemically amplified positive-type resist composition and resist pattern formation method

Abstract

To provide a chemically amplified positive resist composition containing an acid generator capable of generating an acid which has moderate acid strength and exhibits small diffusion.SOLUTION: The resist composition contains: an acid generator of (A1) or (A2); and a polymer which contains a repeating unit having a phenol skeleton and increases its solubility in an alkali developer by an acid.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] One example of an acid generator is a sulfonium salt that generates sulfonic acid having an aromatic group containing an iodine atom, as described in Patent Document 5. However, this is intended to enhance sensitivity in EUV lithography, and its role is primarily as a quencher for fluorinated alkanesulfonic acid. Acid generators, particularly those used in resist compositions with polyhydroxystyrene as the base polymer for EB writing processes in mask blanking, have not been sufficiently studied.

[0011] 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 6 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 7 describes that the addition of ammonium sulfonate or ammonium carboxylate improved sensitivity, resolution, and exposure margin. Furthermore, Patent Document 8 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.

[0012] Patent Document 9 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.

[0013] However, in recent years, there has been a demand for resist compositions that not only offer further improvements in roughness, but also excel in line-and-space (LS), isoline (IL), isospace (IS), and hole pattern shape. Patent Document 10 describes a photoacid generator that produces a bulky acid and suppresses acid diffusion, which yielded patterns with good resolution and roughness, but had the drawback of exhibiting corner rounding in the hole pattern. [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. 6645464 [Patent Document 6] Patent No. 3955384 [Patent Document 7] Japanese Patent Application Publication No. 11-327143 [Patent Document 8] Patent No. 4231622 [Patent Document 9] Patent No. 4226803 [Patent Document 10] Patent No. 6248882 [Overview of the Initiative] [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 containing an acid generator capable of generating an acid having appropriate acid strength and low diffusion, and a pattern formation method using the resist composition. [Means for solving the problem]

[0016] As a result of diligent research to achieve the above objective, the present inventors have found that when at least one selected from the sulfonium salt represented by the following formula (A1) and the iodonium salt represented by the following formula (A2) is introduced into the resist composition, the generated acid has an optimal structure, suppressing acid diffusion, thereby obtaining a pattern with a small LER, and furthermore, in the hole pattern, a good rectangular pattern can be obtained due to appropriate dissolution inhibition, leading to the present invention.

[0017] In other words, the present invention provides the following chemically amplified positive-type resist composition and resist pattern formation method. 1. A chemically amplified positive resist composition comprising (A) an acid generator comprising at least one selected from a sulfonium salt represented by the following formula (A1) and an iodonium salt represented by the following formula (A2), and (B) a base polymer comprising a polymer that contains repeating units represented by the following formula (B1), decomposes upon the action of acid, and whose solubility in an alkaline developer increases. [ka] (In the formula, m is 0 or 1, p is an integer between 1 and 3, q ​​is an integer between 1 and 5, and r is an integer between 0 and 3.) L 1 These are single bonds, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, or carbamate bonds. L 2 These are ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, or carbamate bonds. X 1When p is 1, it is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms, and when p is 2 or 3, it is a (p + 1)-valent hydrocarbon group having 1 to 20 carbon atoms. The hydrocarbylene group and the (p + 1)-valent hydrocarbon group may contain at least one selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxy group, and a carboxy group. Rf 1 and Rf 2 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, provided that at least one of them is a fluorine atom or a trifluoromethyl group. R 1 is a hydroxy group, a carboxy group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, an amino group, -N(R 1A )-C(=O)-R 1B or -N(R 1A )-C(=O)-O-R 1B where R 1A is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and R 1B is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. R 2 is a saturated hydrocarbylene group having 1 to 20 carbon atoms or an arylene group having 6 to 14 carbon atoms. A part or all of the hydrogen atoms of the saturated hydrocarbylene group may be substituted with a halogen atom other than a fluorine atom, and a part or all of the hydrogen atoms of the arylene group may be substituted with a substituent selected from a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, a halogen atom, and a hydroxy group. R 3 ~R 7 are each independently a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or a hydrocarbyl group having 1 to 20 carbon atoms. The hydrocarbyl group may contain at least one selected from an oxygen atom, a sulfur atom, a nitrogen atom, and a halogen atom. Also, R3 and R 4 These may bond with each other to form a ring with the sulfur atom to which they are bonded. [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 + 2a2 - 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 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 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 type 1, wherein component (A) is an onium salt represented by the following formula (A3). [ka] (In the formula, p, q, r, X 1 , R 1 , R 3 , R 4 and R 5 The same applies as above. n is an integer between 1 and 4. R 2A (These are saturated hydrocarbyl groups with 1 to 20 carbon atoms, saturated hydrocarbyloxy groups with 1 to 20 carbon atoms, aryl groups with 6 to 14 carbon atoms, halogen atoms, or hydroxyl groups.) 3. One or two chemically amplified positive resist compositions wherein the polymer further comprises repeating units represented by the following formula (B2-1). [ka] (In the formula, R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. b1 is either 0 or 1. b2 is an integer between 0 and 2. b3 is an integer satisfying 0 ≤ b3 ≤ 5 + 2b2 - b4. b4 is an integer between 1 and 3. b5 is either 0 or 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. 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-. X is an acid-unstable group when b4 is 1, and when b4 is 2 or more, it is a hydrogen atom or an acid-unstable group, but at least one of them is an acid-unstable group. 4. Any of the 1 to 3 chemically amplified positive resist compositions 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. 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 a naphthylene 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 R13 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 These are, independently, hydrocarbyl groups having 1 to 10 carbon atoms, which may contain heteroatoms. 5. One of 1 to 4 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 5. f3 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 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, sulfinyl groups, or sulfonyl groups. 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-.) 6. Any one of 1 to 5 chemically amplified positive resist compositions, wherein the polymer further comprises at least one repeating unit selected from the following formulas (B6) to (B13). [ka] (In the formula, R B Each of these is independently either a hydrogen atom or a methyl group. Y 1 This includes single bonds, aliphatic hydrocarbylene groups with 1 to 6 carbon atoms, phenylene groups, naphthylene groups, or groups with 7 to 18 carbon atoms obtained by combining these, -OY 11 -, -C(=O)-OY 11 -or -C(=O)-NH-Y 11 - and Y 11 This refers to 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 21 This is a hydroxylene 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 -OY 31 -, -C(=O)-OY 31 -or -C(=O)-NH-Y 31 - and 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. Y 4This 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. R 31 ~R 48 Each of these is independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. 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, 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.) 7. A chemically amplified positive resist composition according to any one of 1 to 6, 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. 8. Furthermore, any of the chemically amplified positive resist compositions 1 to 7, comprising (C) a quencher. 9. A chemically amplified positive resist composition of type 8, wherein the ratio of (A) acid generator to (C) quencher is less than 6 by mass. 10. A chemically amplified positive resist composition of any of 1 to 9, 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 formula, R CEach is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R D Each is independently a hydrogen atom or a methyl group. R 101 R 102 R 104 and R 105 Each is independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 103 R 106 R 107 and R 108 Each is 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 is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be interposed between 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 hetero atom may be interposed between carbon-carbon bonds. R 110 is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms in which a group containing a hetero atom may be interposed between 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. x is an integer from 1 to 3. y is an integer satisfying 0 ≦ y ≦ 5 + 2z - x. z is 0 or 1. h is an integer from 1 to 3. 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.) 11. Further, a chemically amplified positive resist composition containing (E) an organic solvent and any one of 1 to 10. 12. A resist pattern forming method including a step of forming a resist film on a substrate using a chemically amplified positive resist composition of any one of 1 to 11, a step of irradiating the resist film with a high energy ray, and a step of developing the resist film irradiated with the pattern using an alkali developer. 13. The resist pattern forming method according to 12, wherein the high energy ray is EUV or EB. 14. The resist pattern forming method according to 12 or 13, 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. 15. The resist pattern forming method according to any one of 12 to 14, wherein the substrate is a transmissive or reflective mask blank. 16. A transmissive or reflective mask blank coated with a chemically amplified positive resist composition of any one of 1 to 11.

Advantages 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 sulfonium salt represented by formula (A1) and / or the iodonium salt represented by formula (A2). When a resist film is formed using this composition to create a pattern, it is possible to obtain a pattern with extremely high resolution, low LER, excellent rectangularity, and excellent pattern fidelity. Furthermore, the repeating unit represented by formula (B1) provides good solubility in alkaline developers and improves adhesion to the substrate when forming the resist film. [Modes for carrying out the invention]

[0019] 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.

[0020] [Chemically amplified positive-type resist composition] The chemically amplified positive resist composition of the present invention is characterized by comprising (A) an acid generator comprising at least one selected from a predetermined sulfonium salt and an iodonium salt, and (B) a base polymer comprising a predetermined polymer.

[0021] [(A) Acid Generator] The acid generator of component (A) contains at least one selected from a sulfonium salt represented by the following formula (A1) and an iodonium salt represented by the following formula (A2). [ka]

[0022] In equations (A1) and (A2), m is either 0 or 1. p is an integer between 1 and 3. q is an integer between 1 and 5. r is an integer between 0 and 3.

[0023] In formulas (A1) and (A2), L 1 These are single bonds, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, or carbamate bonds.

[0024] In formulas (A1) and (A2), L 2 These are ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, or carbamate bonds.

[0025] In equations (A1) and (A2), X 1 When p is 1, it is a single bond or a hydroxylene group having 1 to 20 carbon atoms, and when p is 2 or 3, it is a (p+1) valent hydrocarbon group having 1 to 20 carbon atoms. The hydroxylene group and the (p+1) valent hydrocarbon group may contain at least one selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxyl group, and a carboxyl group.

[0026] X 1 The hydroxylene group, represented by , having 1 to 20 carbon atoms, can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include methanediyl group, ethane-1,1-diyl 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, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group, etc. Examples include alkanediyl groups with 1 to 20 carbon atoms; cyclic saturated hydrocarbylene groups with 3 to 20 carbon atoms such as cyclopentanediyl, cyclohexanediyl, norbornanediyl, and adamantanediyl; unsaturated aliphatic hydrocarbylene groups with 2 to 20 carbon atoms such as vinylene and propene-1,3-diyl; arylene groups with 6 to 20 carbon atoms such as phenylene and naphthylene; and groups obtained by combining these. Also, X 1The (p+1) valent hydrocarbon group having 1 to 20 carbon atoms, represented by , may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include groups obtained by removing one or two hydrogen atoms from the aforementioned specific examples of the 1 to 20 carbon atom hydrocarbylene group.

[0027] In formulas (A1) and (A2), Rf 1 and Rf 2 Each of these is independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one is either a fluorine atom or a trifluoromethyl group.

[0028] In formulas (A1) and (A2), R 1 This includes a hydroxyl group, a carboxyl group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, an amino group, and -N(R 1A )-C(=O)-R 1B or -N(R 1A )-C(=O)-OR 1B And R 1A R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 1B This is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms.

[0029] R 1 , R 1A and R 1B The saturated hydrocarbyl group having 1 to 6 carbon atoms, represented by R, may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, and n-hexyl groups; and cyclic saturated hydrocarbyl groups having 3 to 6 carbon atoms such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl groups. 1The saturated hydrocarbyl portion of the saturated hydrocarbyloxy group having 1 to 6 carbon atoms, as represented by R, is the same as the specific examples of saturated hydrocarbyl groups mentioned above. 1 Represented by Etan Examples of saturated hydrocarbyl groups with 2 to 6 prime numbers include those with 1 to 5 carbon atoms among the aforementioned saturated hydrocarbyl groups with 1 to 6 carbon atoms.

[0030] R 1B The carbon-2-carbon unsaturated aliphatic hydrocarbyl groups represented by can be linear, branched, or cyclic. Specific examples include carbon-2-carbon alkenyl groups such as vinyl, propenyl, butenyl, and hexenyl groups; carbon-2-carbon alkynyl groups such as ethynyl, propynyl, and butynyl groups; and carbon-3-carbon cyclic unsaturated aliphatic hydrocarbyl groups such as cyclohexenyl and norbornenyl groups.

[0031] In formulas (A1) and (A2), R 2 This is a saturated hydrocarbylene group having 1 to 20 carbon atoms or an arylene group having 6 to 14 carbon atoms, wherein some or all of the hydrogen atoms of the saturated hydrocarbylene group may be substituted with halogen atoms other than fluorine atoms, and some or all of the hydrogen atoms of the arylene group may be substituted with substituents selected from a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, a halogen atom, and a hydroxyl group.

[0032] R 2 A carbon number of 1 to 20 represented saturation The hydrocarbylene group is ,straight It can be chain-like, branched, or annular. A specific example is X 1 Examples of hydrocarbylene groups having 1 to 20 carbon atoms, as shown in the example, are similar to those exemplified above.

[0033] R 2Specific examples of arylene groups with 6 to 14 carbon atoms, represented by , include phenylene groups, naphthylene groups, phenanthrendiyl groups, and anthracenediyl groups. The hydrocarbyl portion of the saturated hydrocarbyl group having 1 to 20 carbon atoms and the hydrocarbyloxy group having 1 to 20 carbon atoms, which are substituents on the arylene group, may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 20 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, heptadecyl, octadecyl, nonadecyl, and eicosyl groups; and cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups. Specific examples of arylene groups having 6 to 14 carbon atoms that are substituents on the aforementioned arylene group include phenylene group, naphthylene group, phenanthrendiyl group, anthracenediyl group, and the like.

[0034] In formulas (A1) and (A2), R 3 ~R 7 Each of these is independently a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or a hydrocarbyl group having 1 to 20 carbon atoms, and the hydrocarbyl group may contain at least one selected from an oxygen atom, a sulfur atom, a nitrogen atom, and a halogen atom.

[0035] R 3 ~R 7The hydrocarbyl group, represented by , having 1 to 20 carbon atoms, may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C20 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, heptadecyl, octadecyl, nonadecyl, and eicosyl groups; C3-C20 cyclic saturated hydrocarbyl groups such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; C2-C20 alkenyl groups such as vinyl, propenyl, butenyl, and hexenyl groups; and cyclohexyl Examples include cyclic unsaturated aliphatic hydrocarbyl groups with 3 to 20 carbon atoms, such as cenyl and norbornenyl groups; alkynyl groups with 2 to 20 carbon atoms, such as ethynyl, propynyl, and butynyl groups; aryl groups with 6 to 20 carbon atoms, such as phenyl, methylphenyl, ethylphenyl, n-propylphenyl, isopropylphenyl, n-butylphenyl, isobutylphenyl, sec-butylphenyl, tert-butylphenyl, naphthyl, methylnaphthyl, ethylnaphthyl, n-propylnaphthyl, isopropylnaphthyl, n-butylnaphthyl, isobutylnaphthyl, sec-butylnaphthyl, and tert-butylnaphthyl groups; aralkyl groups with 7 to 20 carbon atoms, such as benzyl and phenethyl groups; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, nitrogen atom, or halogen atom, and some of the -CH2- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, or nitrogen atom, and as a result, it may contain a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc.

[0036] Also, R 3 and R 4 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. Examples of rings formed in this case include those shown below. [ka] (In the equation, dashed lines represent connections.)

[0037] As the acid generator for component (A), an onium salt represented by the following formula (A3) is preferred. [ka]

[0038] In formula (A3), p, q, r, X 1 , R 1 , R 3 , R 4 and R 5 The same as above. n is an integer from 1 to 4. 2A These are saturated hydrocarbyl groups with 1 to 20 carbon atoms, saturated hydrocarbyloxy groups with 1 to 20 carbon atoms, aryl groups with 6 to 14 carbon atoms, halogen atoms, or hydroxyl groups. When n is 2 to 4, each R 2A They may be the same as or different from each other.

[0039] The anions of the sulfonium salt represented by formula (A1) and the iodonium salt represented by formula (A2) include, but are not limited to, the following. [ka]

[0040] [ka]

[0041] [ka]

[0042]

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[0043]

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[0044]

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[0045]

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[0046]

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[0047]

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[0048]

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[0049]

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[0050]

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[0051]

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[0052]

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[0053]

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[0054]

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[0055]

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[0056]

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[0057]

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[0058]

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[0059]

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[0060]

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[0061]

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[0062]

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[0063] [ka]

[0064] [ka]

[0065] [ka]

[0066] [ka]

[0067] The cations of the sulfonium salt represented by formula (A1) include, but are not limited to, those listed below. [ka]

[0068] [ka]

[0069] [ka]

[0070] [ka]

[0071] [ka]

[0072] [ka]

[0073]

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[0074]

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[0075]

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[0076]

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[0077]

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[0078]

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[0079]

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[0080]

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[0081]

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[0082]

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[0083] [Chemistry]

[0084] [Chemistry]

[0085] [Chemistry]

[0086] [Chemistry]

[0087] [Chemistry]

[0088] [Chemistry]

[0089] Examples of the cation of the iodonium salt represented by formula (A2) include, but are not limited to, those shown below. [Chemistry]

[0090] [Chemistry]

[0091] The sulfonium salt represented by formula (A1) and the iodonium salt represented by formula (A2) function extremely effectively as an optimal acid generator (photoacid generator) when applied to a chemically amplified positive resist composition.

[0092] A method for synthesizing the sulfonium salt represented by formula (A1) and the iodonium salt represented by formula (A2) is described in Japanese Patent Publication No. 2010-155824. For example, they can be synthesized by esterifying the hydroxyl group of a sulfonium salt or iodonium salt of a sulfonic acid having a hydroxyl group, such as isethionic acid, with iodized benzoic acid.

[0093] In the chemically amplified positive resist composition of the present invention, the content of (A) a sulfonium salt represented by formula (A1) and / or an iodonium salt represented by formula (A2) is preferably 0.001 to 50 parts by mass, and more preferably 0.01 to 40 parts by mass, relative to 80 parts by mass of the (B) base polymer described later, from the viewpoint of sensitivity and acid diffusion suppression effect.

[0094] The chemically amplified positive resist composition of the present invention may further contain an acid generator other than the sulfonium salt represented by formula (A1) and the iodonium salt represented by formula (A2) (hereinafter also referred to as "other acid generators") for the purpose of correcting the shape of the pattern. As the other acid generators, those known as acid generators for resist compositions can be used. The content of the other acid generators is preferably 0 to 30 parts by mass, and more preferably 0 to 20 parts by mass, relative to 80 parts by mass of the (B) base polymer described later, from the viewpoint of sensitivity and acid diffusion suppression effect. The other acid generators may be used alone or in combination of two or more.

[0095] [(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]

[0096] 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 + 2a2 - a4, and 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.

[0097] In formula (B1), R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0098] 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, propyl, isopropyl, butyl, pentyl, and hexyl groups; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl groups; 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.

[0099] In formula (B1), A 1This 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-. The saturated hydrocarbylene group may be linear, branched, or cyclic, and specific examples include alkanediyl groups 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 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-position carbon atom and the β-position 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.

[0100] 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.)

[0101] Also, a1 is 1 (i.e., -C(=O)-OA as the linker). 1If (-) then preferred examples of repeating unit B1 are, but are not limited to, those listed below. [ka] (In the formula, R A (This is the same as above.)

[0102] 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 used in the present invention, as described later, contains at least one of the repeating units represented by formula (B3) and formula (B4) that provide high etching resistance, and the unit has a phenolic hydroxyl group as a substituent, then it is preferable that the ratio of the repeating unit is also included within the above range. Repeating unit B1 may be used alone or in combination of two or more types.

[0103] The polymer preferably contains repeating units having acidic functional groups protected by acid-unstable groups (repeating units protected by acid-unstable groups that become alkali-soluble upon the action of acid) in order to provide the positive-type resist composition with the property that the exposed area dissolves in an alkaline aqueous solution. 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.

[0104] The most preferred example of such a repeating unit is the one represented by the following formula (B2-1) (hereinafter also referred to as repeating unit B2-1). [ka]

[0105] In formula (B2-1), R AThe same applies as above. 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 + 2b2 - 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, and when b2 is 1 or 2, preferably b3 is an integer between 0 and 4 and b4 is an integer between 1 and 3.

[0106] In formula (B2-1), R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0107] 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, propyl, isopropyl, butyl, pentyl, and hexyl groups; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl groups; and groups obtained by combining these. If the number of carbon atoms is below the upper limit, the 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.

[0108] In formula (B2-1), A 2b1 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-. The saturated hydrocarbylene group may be linear, branched, or cyclic, and specific examples include alkanediyl groups 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 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 b1 in formula (B2-1) 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 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.

[0109] 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 of them 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. Such an acid-unstable group can be any that is removed by acid to give an acidic group, as has been used in many chemically amplified positive resist compositions that are already known, and is not particularly limited.

[0110] Selecting a tertiary saturated hydrocarbyl group as the acid-unstable group is preferable because it allows for the formation of a resist film thickness of, for example, 10 to 100 nm, and even when forming a fine pattern with a line width of 45 nm or less, the LER (Low Linear Emission) is small, thus providing a small pattern. The tertiary alkyl group is preferably one having 4 to 18 carbon atoms in order to obtain the resulting monomer for polymerization by distillation. Furthermore, the group bonded to the tertiary carbon atom of the tertiary saturated hydrocarbyl group may be a saturated hydrocarbyl group having 1 to 15 carbon atoms, which may contain oxygen-containing functional groups such as ether bonds or carbonyl groups, and the groups bonded to the tertiary carbon atom may bond to each other to form a ring.

[0111] Specific examples of groups bonded to the tertiary carbon atom include methyl group, ethyl group, propyl group, adamantyl group, norbornyl group, tetrahydrofuran-2-yl group, 7-oxanorbornan-2-yl group, cyclopentyl group, 2-tetrahydrofuryl group, tricyclo[5.2.1.0 2,6 ] Decyl group, tetracyclo[4.4.0.1 2,5 .1 7,10 Examples include the dodecyl group and the 3-oxo-1-cyclohexyl group.

[0112] Furthermore, tertiary saturated hydrocarbyl groups having these as substituents include tert-butyl group, tert-pentyl group, 1-ethyl-1-methylpropyl group, 1,1-diethylpropyl group, 1,1,2-trimethylpropyl group, 1-adamantyl-1-methylethyl group, 1-methyl-1-(2-norbornyl)ethyl group, 1-methyl-1-(tetrahydrofuran-2-yl)ethyl group, 1-methyl-1-(7-oxanorbornan-2-yl)ethyl group, 1-methylcyclopentyl group, 1-ethylcyclopentyl group, 1 -Propylcyclopentyl group, 1-isopropylcyclopentyl group, 1-cyclopentylcyclopentyl group, 1-cyclohexylcyclopentyl group, 1-(2-tetrahydrofuryl)cyclopentyl group, 1-(7-oxanorbornan-2-yl)cyclopentyl group, 1-methylcyclohexyl group, 1-ethylcyclohexyl group, 1-cyclopentylcyclohexyl group, 1-cyclohexylcyclohexyl group, 2-methyl-2-norbonyl group, 2-ethyl-2-norbonyl group, 8-methyl-8-tricyclo[5.2.1.0 2,6 ]decyl group, 8-ethyl-8-tricyclo[5.2.1.0 2,6 ]decyl group, 3-methyl-3-tetracyclo[4.4.0.1 2,5 .1 7,10 ]dodecyl group, 3-ethyl-3-tetracyclo[4.4.0.1 2,5 .1 7,10 Examples include, but are not limited to, the dodecyl group, 2-methyl-2-adamantyl group, 2-ethyl-2-adamantyl group, 1-methyl-3-oxo-1-cyclohexyl group, 1-methyl-1-(tetrahydrofuran-2-yl)ethyl group, 5-hydroxy-2-methyl-2-adamantyl group, and 5-hydroxy-2-ethyl-2-adamantyl group.

[0113] Furthermore, the group represented by the following formula (B2-1') can be cited as the acid-unstable group. The group represented by formula (B2-1') is commonly used as an acid-unstable group and is a useful choice as an acid-unstable group that stably gives patterns where the interface between the pattern and the substrate is relatively rectangular. When X is the group represented by formula (B2-1'), an acetal structure is formed. [ka]

[0114] In formula (B2-1'), R L1 R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. L2 This is a saturated hydrocarbyl group having 1 to 30 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic.

[0115] R L1 The choice of R depends on the design of the sensitivity of the decomposition group to acid. For example, if the design requires decomposition with a strong acid while ensuring relatively high stability, a hydrogen atom is chosen, while if the design requires high sensitivity to pH changes using relatively high reactivity, a linear alkyl group is chosen. The choice of R also depends on the combination with the acid generator and basic compound incorporated into the resist composition. L2 If a relatively large alkyl group is selected at the terminal and the change in solubility due to decomposition is designed to be significant, then R L1 Preferably, the carbon atom bonded to the acetal carbon is a secondary carbon atom. L1 Examples of these groups include isopropyl, sec-butyl, cyclopentyl, and cyclohexyl groups.

[0116] Of the aforementioned acetal groups, R is used to obtain higher resolution. L2 It is preferable that R is a polycyclic alkyl group having 7 to 30 carbon atoms. L2 When is a polycyclic alkyl group, it is preferable that a bond is formed between the secondary carbon atom constituting the polycyclic ring structure and the acetal oxygen. When the bond is on the secondary carbon atom of the ring structure, the polymer becomes a more stable compound compared to when the bond is on the tertiary carbon atom, resulting in better storage stability as a resist composition and no deterioration in resolution. L2Compared to cases where the polymer is bonded on primary carbon atoms with a linear alkyl group having one or more carbon atoms interposed, the polymer exhibits a better glass transition temperature (Tg), and the resist pattern after development does not suffer from shape defects due to baking.

[0117] Preferred examples of the group represented by formula (B2-1') are, but are not limited to, those listed below. Note that in the following formula, R L1 This is the same as described above. [ka]

[0118] Furthermore, as a repeating unit having an acidic functional group protected by the aforementioned acid-unstable group, a repeating unit represented by the following formula (B2-2) (hereinafter also referred to as repeating unit B2-2) can be mentioned. The repeating unit represented by formula (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]

[0119] 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.

[0120] In formula (B2-2), R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0121] 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 a naphthylene group.

[0122] 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.

[0123] 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.

[0124] In formula (B2-2), R 16 Each of these is independently a hydrocarbyl group having 1 to 10 carbon atoms, which may contain heteroatoms.

[0125] 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]

[0126] Other acid-unstable groups can also be used 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.

[0127] The content of repeating units B2-1 and B2-2 is preferably 5 to 50 mol% of the total repeating units constituting the polymer. Repeating units B2-1 and B2-2 may be used individually or in combination of two or more types.

[0128] 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]

[0129] In equations (B3) and (B4), d and e are each independent integers between 0 and 4.

[0130] In formulas (B3) and (B4), R 21 and R 22 Each 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.

[0131] In formula (B5), f1 is 0 or 1. f2 is an integer between 0 and 5. f3 is an integer between 0 and 2, where 0 represents a benzene skeleton, 1 represents a naphthalene skeleton, and 2 represents an anthracene skeleton. When f3 is 0, f2 is preferably an integer between 0 and 3, and when f3 is 1 or 2, f2 is preferably an integer between 0 and 4.

[0132] In formula (B5), R A This is the same as above. 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 sulfinyl group, or a sulfonyl group. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, saturated hydrocarbyloxyhydrocarbyl group, and saturated hydrocarbylthiohydrocarbyl group may be linear, branched, or cyclic. When f2 is 2 or more, each R 23 They may be the same as or different from each other.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] In formula (B5), A 4This 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-. The saturated hydrocarbylene group may be linear, branched, or cyclic, and specific examples include alkanediyl groups 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 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.

[0137] 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.

[0138] 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]

[0139] [ka]

[0140] When at least one of the repeating units B3 to B5 is used as a constituent unit, 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.

[0141] 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. It is preferable that the amount introduced when there are no functional groups or when there are neither functional groups is 35 mol% or less, as this does not increase the risk of development defects. Repeating units B3 to B5 may be used individually or in combination of two or more types.

[0142] The polymer preferably contains repeating unit B1, repeating units B2-1 and / or B2-2, and at least one selected from repeating units B3 to B5 as constituent units, as this is preferable in terms of achieving both high etching resistance and resolution. In this case, it is preferable that these repeating units are present in 60 mol% or more of the total repeating units, more preferably 70 mol% or more, and even more preferably 80 mol% or more.

[0143] 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]

[0144] In formulas (B6) to (B13), R B Each of these is independently either a hydrogen atom or a methyl group. 1 This includes single bonds, aliphatic hydrocarbylene groups with 1 to 6 carbon atoms, phenylene groups, naphthylene groups, or groups with 7 to 18 carbon atoms obtained by combining these, -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. 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. 3 This includes single bonds, methylene groups, ethylene groups, phenylene groups, fluorinated phenylene groups, trifluoromethyl groups, and -OY31 -, -C(=O)-OY 31 -or -C(=O)-NH-Y 31 - and Y 31 This is a group having 1 to 6 carbon atoms, an aliphatic hydrocarbylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, or a group having 7 to 20 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. 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.

[0145] 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.)

[0146] In formulas (B7) and (B11), R HF is a hydrogen atom or a trifluoromethyl group. In repeating units B7 and B11, R HF A 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.

[0147] 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.

[0148] Preferred examples of monomer anions that give repeating units B9 and B13 are, but are not limited to, those listed below. [ka]

[0149] [ka]

[0150] In formulas (B6) to (B13), R 31 ~R 48 Each of these is independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. For example, in the explanation of formula (A1), R 3 , R 4 and R 5 Examples of hydrocarbyl groups represented by the above 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- 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, it may contain a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc.

[0151] 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 R34 , 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 3 and R 4 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.

[0152] Furthermore, specific examples of sulfonium cations in repeating units B7 to B9 are the same as those exemplified as cations of sulfonium salts represented by formula (A1). Specific examples of iodonium cations in repeating units B11 to B13 are the same as those exemplified as cations of iodonium salts represented by formula (A2).

[0153] 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 considered effective in improving LER and CDU, and reducing pattern defects by suppressing unwanted deprotection reactions in the unexposed areas. When repeating units B6 to B13 are included, their content 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.

[0154] (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.

[0155] 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.

[0156] 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]

[0157] In formulas (B14) to (B16), R A This is the same as above. R 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.

[0158] 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.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] [(C) Quencher] The chemically amplified positive resist composition of the present invention preferably contains a quencher as component (C). Examples of the quencher include conventional basic compounds. Examples of conventional basic compounds include primary, secondary, and tertiary aliphatic amines, hybrid amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a 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, and the like. In particular, primary, secondary, and tertiary amine compounds described in paragraphs

[0146] to

[0164] of Japanese Patent Application Publication No. 2008-111103, especially amine compounds having a hydroxyl group, ether bond, ester bond, lactone ring, cyano group, or sulfonic acid ester bond, or compounds having a carbamate group described in Japanese Patent No. 3790649, are preferred. Preferred examples include tris[2-(methoxymethoxy)ethyl]amine, tris[2-(methoxymethoxy)ethyl]amine-N-oxide, dibutylaminobenzoic acid, morpholine derivatives, and imidazole derivatives. By adding such basic compounds, it is possible to further suppress the diffusion rate of the acid in the resist film or correct its shape, for example.

[0163] Furthermore, examples of the quencher include onium salts such as sulfonium salts, iodonium salts, and ammonium salts of carboxylic acids whose α-position is not fluorinated, as described in Japanese Patent Publication No. 2008-158339. Sulfonic acids, imido acids, or methidic acids with α-position fluorinated are necessary for deprotecting acid-unstable groups, but salt exchange with onium salts whose α-position is not fluorinated releases carboxylic acids whose α-position is not fluorinated. Carboxylic acids whose α-position is not fluorinated hardly undergo deprotection reactions and therefore function as quenchers.

[0164] Examples of onium salts of carboxylic acids whose α-position is not fluorinated include those represented by the following formula (C1). [ka]

[0165] In formula (C1), R 61 This refers to a hydrocarbyl group having 1 to 40 carbon atoms, which may contain hydrogen atoms or heteroatoms, but excludes those in which the hydrogen atom bonded to the carbon atom at the α position of the carboxyl group is substituted with a fluorine atom or a fluoroalkyl group.

[0166] The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 40 carbon atoms 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, and n-decyl groups; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0 2,6 ] Cyclic saturated hydrocarbyl groups with 3 to 40 carbon atoms, such as decanyl group, adamantyl group, and adamantylmethyl group; alkenyl groups with 2 to 40 carbon atoms, such as vinyl group, allyl group, propenyl group, butenyl group, and hexenyl group; cyclic unsaturated aliphatic hydrocarbyl groups with 3 to 40 carbon atoms, such as cyclohexenyl group; phenyl group, naphthyl group, alkylphenyl group (2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-methylmethylphenyl group, 4-methylphenyl group, methylphenyl group, methylphenyl group, 4-methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, Examples include aryl groups with 6 to 40 carbon atoms, such as t-butylphenyl group, 4-n-butylphenyl group, dialkylphenyl group (2,4-dimethylphenyl group, 2,4,6-triisopropylphenyl group, etc.), alkylnaphthyl group (methylnaphthyl group, ethylnaphthyl group, etc.), and dialkylnaphthyl group (dimethylnaphthyl group, diethylnaphthyl group, etc.); and aralkyl groups with 7 to 40 carbon atoms, such as benzyl group, 1-phenylethyl group, and 2-phenylethyl group.

[0167] Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, nitrogen atom, or halogen atom, and some of the -CH2- of the hydrocarbyl group may be substituted with a heteroatom-containing group such as an oxygen atom, sulfur atom, or nitrogen atom, and as a result, it may contain a hydroxyl group, a cyano group, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc. Examples of hydrocarbyl groups containing heteroatoms include heteroaryl groups such as thienyl groups; alkoxyphenyl groups such as 4-hydroxyphenyl, 4-methoxyphenyl, 3-methoxyphenyl, 2-methoxyphenyl, 4-ethoxyphenyl, 4-tert-butoxyphenyl, and 3-tert-butoxyphenyl groups; alkoxynaphthyl groups such as methoxynaphthyl, ethoxynaphthyl, n-propoxynaphthyl, and n-butoxynaphthyl groups; dialkoxynaphthyl groups such as dimethoxynaphthyl and diethoxynaphthyl groups; and aryloxoalkyl groups such as 2-aryl-2-oxoethyl groups such as 2-phenyl-2-oxoethyl, 2-(1-naphthyl)-2-oxoethyl, and 2-(2-naphthyl)-2-oxoethyl groups.

[0168] In formula (C1), Mq + This is an onium cation. The onium cation is preferably a sulfonium cation, an iodonium cation, or an ammonium cation, and more preferably a sulfonium cation or an iodonium cation. Specific examples of the sulfonium cation are the same as those exemplified as the cation of the sulfonium salt represented by formula (A1). Specific examples of the iodonium cation are the same as those exemplified as the cation of the iodonium salt represented by formula (A2).

[0169] The anions of the onium salt represented by formula (C1) include, but are not limited to, those listed below. [ka]

[0170] [ka]

[0171] [ka]

[0172] As the quencher, a sulfonium salt of an iodized benzene ring-containing carboxylic acid represented by the following formula (C2) can also be suitably used. [ka]

[0173] In equation (C2), s is an integer between 1 and 5, t is an integer between 0 and 3, and u is an integer between 1 and 3.

[0174] In formula (C2), R 71 This may be a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms, or a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms, or -N(R 71A )-C(=O)-R 71B Or -N(R 71A )-C(=O)-OR 71B That is. R 71A R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 71B is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. When t and / or u are 2 or more, each R 71 They may be the same or different from one another.

[0175] In formula (C2), L11 This is a single bond or a (u+1) valent linking group having 1 to 20 carbon atoms, and may contain at least one selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxyl group, and a carboxyl group. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, and saturated hydrocarbylsulfonyloxy group may be linear, branched, or cyclic.

[0176] In formula (C2), R 72 , R 73 and R 74 Each of these is a C1-C20 hydrocarbyl group 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 include C1-C20 alkyl groups, C2-C20 alkenyl groups, C6-C20 aryl groups, C7-C20 aralkyl groups, etc. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a hydroxyl group, carboxyl group, halogen atom, oxo group, cyano group, nitro group, sultone ring, sulfo group, or sulfonium salt-containing group, and some of the -CH2- of the hydrocarbyl group may be substituted with an ether bond, ester bond, carbonyl group, amide bond, carbonate bond, or sulfonic acid ester bond. 72 and R 73 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded.

[0177] A specific example of the compound represented by formula (C2) is the one described in Japanese Patent Publication No. 2017-219836. The compound represented by formula (C2) exhibits high absorption, high sensitization effect, and high acid diffusion control effect.

[0178] As the quencher, a nitrogen atom-containing carboxylate compound represented by the following formula (C3) can also be used. [ka]

[0179] In formula (C3), R 81 ~R 84 These are, independently, hydrogen atoms and -L 12 -CO2 - or a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. 81 and R 82 And, R 82 and R 83 or R 83 and R 84 These may bond with each other to form a ring with the carbon atom to which they are bonded. 12 R is a hydroxylene group having 1 to 20 carbon atoms, which may contain single bonds or heteroatoms. 85 This is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a hydrogen atom or a heteroatom.

[0180] In formula (C3), ring R is a ring having 2 to 6 carbon atoms, including the carbon and nitrogen atoms in the formula, and some or all of the hydrogen atoms bonded to the carbon atoms of the ring are a hydrocarbyl group having 1 to 20 carbon atoms, or -L 12 -CO2 - The ring may be substituted with a sulfur atom, oxygen atom, or nitrogen atom. The ring may be an alicyclic ring or an aromatic ring, and is preferably a 5-membered or 6-membered ring. Specific examples include pyridine rings, pyrrole rings, pyrrolidine rings, piperidine rings, pyrazole rings, imidazoline rings, pyridazine rings, pyrimidine rings, pyrazine rings, imidazoline rings, oxazole rings, thiazole rings, morpholine rings, thiazine rings, triazole rings, and the like.

[0181] The onium carboxylate salt represented by formula (C3) contains at least one -L 12 -CO2 - It has a group. That is, R 81 ~R 84 At least one of them is -L 12 -CO2 - is and / or at least one hydrogen atom bonded to a carbon atom of ring R is -L12 -CO2 - It has been replaced with this.

[0182] In formula (C3), Q + This is a sulfonium cation, an iodonium cation, or an ammonium cation, but a sulfonium cation is preferred. Specific examples of the sulfonium cation include those similar to those exemplified as the cation of the sulfonium salt represented by formula (A1).

[0183] The anions of the compound represented by formula (C3) include, but are not limited to, those listed below. [ka]

[0184] [ka]

[0185] [ka]

[0186] [ka]

[0187] [ka]

[0188] [ka]

[0189] Furthermore, a weak acidic betaine-type compound can also be used as the quencher. Specific examples are listed below, but are not limited to these. [ka]

[0190] As an example of the aforementioned quencher, a polymer-type quencher described in Japanese Patent Publication No. 2008-239918 can be cited. This enhances the rectangularity of the resist pattern by oriented on the surface of the resist film. The polymer-type quencher also has the effect of preventing film thinning of the pattern and rounding of the pattern top when a protective film for immersion lithography is applied.

[0191] If the chemically amplified positive resist composition of the present invention contains (C) quencher, its content is preferably 0 to 50 parts by mass, and more preferably 0.1 to 40 parts by mass, per 80 parts by mass of (B) base polymer. (C) quencher may be used alone or in combination of two or more types.

[0192] When the chemically amplified positive resist composition of the present invention contains both an acid generator component (A) and a quencher component (C), it is preferable that the ratio of the photoacid generator to the quencher ((A) / (C)) is less than 6 by mass, more preferably less than 5, and even more preferably less than 4. If the ratio of the acid generator to the quencher contained in the chemically amplified positive resist composition is within the above range, acid diffusion can be sufficiently suppressed, and excellent resolution and dimensional uniformity can be obtained.

[0193] [(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, shielding against chemical flares of acids during high-energy ray irradiation and mixing of acids from the antistatic film during the process of coating the resist film with an antistatic film material, thereby suppressing unexpected and unwanted pattern degradation. This polymer may further contain at least one repeating unit selected from the following formulas (D1), (D2), (D3), and (D4) (hereinafter also referred to as repeating units D1, D2, D3, and D4, respectively), and may also contain at least one repeating unit selected from the following formulas (D5) and (D6, respectively). 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]

[0194] In formulas (D1) to (D6), 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 R 103 , 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 x 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. x is an integer from 1 to 3. y is an integer satisfying 0 ≤ y ≤ 5 + 2z - x. z is 0 or 1. h is an integer from 1 to 3. 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. 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.

[0195] In equations (D1) and (D2), R 101 , R 102 , R 104 and R 105Examples of saturated hydrocarbyl groups having 1 to 10 carbon atoms, represented by , 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.

[0196] In formulas (D1) to (D4), R 103 , R 106 , R 107 and R 108 Examples of C1-C15 hydrocarbyl groups represented by include C1-C15 alkyl groups, C2-C15 alkenyl groups, C2-C15 alkynyl groups, etc., but C1-C15 alkyl groups are preferred. Examples of alkyl groups include, in addition to those mentioned above, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, etc. Examples of alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, n-pentyl group, n-hexyl group, n-hexyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, etc. Examples of 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.

[0197] 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 1 Examples 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.

[0198] 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]

[0199] [ka]

[0200] [ka]

[0201] 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.

[0202] 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.

[0203] In formula (D5), Z 2 It is preferable that *-C(=O)-O- or *-C(=O)-NH-. Furthermore, R D It 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 DWhen 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.

[0204] 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]

[0205] [ka]

[0206] 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.

[0207] 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.

[0208] 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]

[0209] [ka]

[0210] [ka]

[0211] [ka]

[0212] 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.

[0213] 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.

[0214] 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.

[0215] 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.

[0216] 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.

[0217] [(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 acid-unstable acetal groups, high-boiling point alcoholic 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.

[0218] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, PGME, cyclohexanone, EL, γ-butyrolactone, and mixtures thereof are preferred.

[0219] In the chemically amplified positive resist composition of the present invention, the content of (E) organic solvent 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 (B) base polymer. (E) organic solvent may be used alone or as a mixture of two or more types.

[0220] [(F) 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. In the chemically amplified positive resist composition of the present invention, the content of (F) surfactant is preferably 0 to 5 parts by mass per 80 parts by mass of (B) base polymer. (F) surfactant may be used alone or in combination of two or more types.

[0221] [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.

[0222] 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.

[0223] 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.

[0224] 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 for forming the desired pattern is used, 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.

[0225] In addition to conventional exposure methods, immersion exposure, which involves 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.

[0226] Next, the food is subjected to PEB (Periodic Emission Breaking) on ​​a hot plate, preferably at 60-150°C for 1-20 minutes, more preferably at 80-140°C for 1-10 minutes.

[0227] 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.

[0228] 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.

[0229] 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.

[0230] 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.

[0231] 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.

[0232] 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.

[0233] 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.

[0234] According to the resist pattern formation method of the present invention, even when the outermost surface is made of a material that easily affects the resist pattern shape, such as a material containing chromium, silicon, or tantalum (for example, a transmissive or reflective mask blank), it is possible to obtain a pattern with extremely high resolution, low LER, excellent rectangularity, and excellent pattern fidelity. [Examples]

[0235] 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. Note that the copolymerization composition ratio is expressed as a molar ratio, and Mw is the polystyrene equivalent measurement value obtained by GPC.

[0236] The structures of the acid generators PAG-1 to PAG-12 used in the chemically amplified positive-type resist composition of the present invention are shown below. [ka]

[0237] [ka]

[0238] [ka]

[0239] The structures of the acid generators cPAG-1 to cPAG-4 used in the comparative example are shown below. [ka]

[0240] The structures of polymers A-1 to A-14 and polymers P-1 to P-5 used in the resist composition are shown below. [ka]

[0241] [ka]

[0242] [ka]

[0243] [ka]

[0244] [ka]

[0245] The structures of the quenchers Q-1 to Q-3 and fluorine atom-containing polymers D-1 to D-5 used in the resist composition are shown below. [ka]

[0246] [ka]

[0247] [1] Preparation of chemically amplified positive resist compositions [Examples 1-1 to 1-44, Comparative Examples 1-1 to 1-4] Chemically amplified positive resist compositions (R-1 to R-44, CR-1 to CR-4) were prepared by dissolving each component in an organic solvent in the compositions shown in Tables 1 to 3 below, and filtering the resulting solutions through UPE filters and / or nylon filters selected from sizes of 10 nm, 5 nm, 3 nm, and 1 nm. The organic solvent was a mixed solvent consisting of 900 parts by mass of PGMEA, 1800 parts by mass of EL, and 1800 parts by mass of PGME.

[0248] [Table 1]

[0249] [Table 2]

[0250] [Table 3]

[0251] [2] EB lithography evaluation [Examples 2-1 to 2-44, Comparative Examples 2-1 to 2-4] Each chemically amplified positive resist composition (R-1 to R-44, CR-1 to CR-4) was spin-coated onto a 152 mm square mask blank with a chromium film on its outermost surface 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 resist films 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. 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 110°C for 600 seconds, and developed with a 2.38 mass% TMAH aqueous solution to obtain a positive-type pattern.

[0252] 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. Using a SEM, 80 edge detection points were performed on each of the 32 edges of the 200nm LS pattern, and the value three times the variation (standard deviation, σ) (3σ) was calculated and defined as LER (nm). For pattern fidelity evaluation, the area loss value (%) of one corner of the hole pattern was calculated when a 120nm size square hole pattern was placed at a density of 36%. A smaller value indicates better rectangularity of the hole shape. The pattern shape was determined visually whether it was rectangular or not. The results are shown in Tables 4-6.

[0253] [Table 4]

[0254] [Table 5]

[0255] [Table 6]

[0256] The chemically amplified positive resist compositions (R-1 to R-44) of the present invention all exhibited good resolution, LER, pattern rectangularity, and pattern fidelity. Furthermore, when comparing R-43 and R-44, good resolution performance was obtained in the region of 50 μC or higher. On the other hand, the comparative resist compositions (CR-1 to CR-4) had an insufficient design of the acid generator, resulting in insufficient performance in terms of resolution, LER, and pattern rectangularity. It is believed that the improvement in resolution, LER, pattern rectangularity, and pattern fidelity was achieved by the acid diffusion suppression effect of the combination of a base polymer having a hydroxystyrene skeleton and an iodine atom-containing acid generator in the design of the present invention.

[0257] The resist pattern formation method using the chemically amplified positive resist composition of the present invention is useful for semiconductor device manufacturing, particularly for photolithography in the processing of transmissive or reflective photomask blanks.

Claims

1. (A) An acid generator comprising at least one selected from a sulfonium salt represented by the following formula (A1) and an iodonium salt represented by the following formula (A2), (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, and (C) Quencher A chemically amplified positive-type resist composition comprising, The base polymer contains a base polymer in which the content of repeating units having an aromatic ring skeleton is 60 mol% or more of the total repeating units of the polymer. (C) A chemically amplified positive resist composition in which the quencher is at least one selected from the following: an onium salt of a carboxylic acid whose α-position is not fluorinated, represented by the following formula (C1); a sulfonium salt of an iodized benzene ring-containing carboxylic acid, represented by the following formula (C2); a nitrogen atom-containing carboxylate-type compound, represented by the following formula (C3); and a betaine-type compound of a weak acid. 【Chemistry 1】 (In the formula, m is 0 or 1, p is an integer from 1 to 3, q ​​is an integer from 1 to 5, and r is an integer from 0 to 3.) L 1 These are single bonds, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, or carbamate bonds. L 2 These are ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, or carbamate bonds. X 1 When p is 1, it is a single bond or a hydroxylene group having 1 to 20 carbon atoms, and when p is 2 or 3, it is a (p+1) valent hydrocarbon group having 1 to 20 carbon atoms. The hydroxylene group and the (p+1) valent hydrocarbon group may contain at least one selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxyl group, and a carboxyl group. Rf 1 and Rf 2 Each of these is independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one is either a fluorine atom or a trifluoromethyl group. R 1 is a hydroxy group, a carboxy group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, an amino group, -N(R 1A )-C(=O)-R 1B or -N(R 1A )-C(=O)-O-R 1B where R 1A is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and R 1B is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. R 2 This is a saturated hydrocarbylene group having 1 to 20 carbon atoms or an arylene group having 6 to 14 carbon atoms, wherein some or all of the hydrogen atoms of the saturated hydrocarbylene group may be substituted with halogen atoms other than fluorine atoms, and some or all of the hydrogen atoms of the arylene group may be substituted with substituents selected from a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, and a hydroxyl group. R 3 ~R 7 Each of these is independently a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or a hydrocarbyl group having 1 to 20 carbon atoms, and the hydrocarbyl group may contain at least one selected from an oxygen atom, a sulfur atom, a nitrogen atom, and a halogen atom. Also, R 3 and R 4 These may bond with each other to form a ring with the sulfur atom to which they are bonded. 【Chemistry 2】 (In the formula, a1 is 0 or 1. a2 is an integer between 0 and 2. a3 is an integer that satisfies 0 ≤ a3 ≤ 5 + 2a2 - 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 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 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 - may be replaced by -O-.) 【Transformation 3】 (In the formula, R 61 is a C1 to C40 hydrocarbyl group which may contain a hydrogen atom or a heteroatom, but excludes those in which the hydrogen atom bonded to the carbon atom at the α position of the carboxyl group is substituted with a fluorine atom or a fluoroalkyl group.) Mq+ is an onium cation. 【Chemistry 4】 (In the formula, s is an integer from 1 to 5, t is an integer from 0 to 3, and u is an integer from 1 to 3.) R 71 is a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms, or a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms, or -N(R 71A)-C(=O)-R 71B or -N(R 71A)-C(=O)-O-R 71B. R 71A is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R 71B is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. When t and / or u are 2 or more, each R 71 may be the same as or different from each other. L11 is a single bond or a (u+1) valent linking group having 1 to 20 carbon atoms, and may include at least one selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxyl group, and a carboxyl group. R72, R73, and R74 are each independently a C1-C20 hydrocarbyl group which may contain a halogen atom or a heteroatom. Furthermore, R72 and R73 may bond to each other to form a ring with the sulfur atom to which they are bonded. ） 【Transformation 5】 (In the formula, R 81 to R 84 are each independently a C1 to C20 hydrocarbyl group which may contain a hydrogen atom, -L 12-CO 2-, or a heteroatom. R 81 and R 82, R 82 and R 83, or R 83 and R 84 may bond to each other to form a ring with the carbon atom to which they are bonded.) L12 is a hydroxylene group having 1 to 20 carbon atoms, which may contain single bonds or heteroatoms. R 85 is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a hydrogen atom or a heteroatom. Ring R is a ring having 2 to 6 carbon atoms, including carbon atoms and nitrogen atoms in the formula, and some or all of the hydrogen atoms bonded to the carbon atoms of the ring may be substituted with a hydrocarbyl group having 1 to 20 carbon atoms or -L 12-CO 2-, and some of the carbon atoms of the ring may be substituted with sulfur atoms, oxygen atoms or nitrogen atoms. However, at least one of R 81 to R 84 is -L 12-CO 2-, and / or at least one hydrogen atom bonded to the carbon atom of ring R is substituted with -L 12-CO 2-. Q+ is a sulfonium cation, iodonium cation, or ammonium cation.

2. The chemically amplified positive resist composition according to claim 1, wherein component (A) is an onium salt represented by the following formula (A3). 【Transformation 6】 (In the formula, p, q, r, X 1 , R 1 , R 3 , R 4 and R 5 The same applies as above. n is an integer between 1 and 4. R 2A (These are saturated hydrocarbyl groups having 1 to 20 carbon atoms, saturated hydrocarbyloxy groups having 1 to 20 carbon atoms, and aryl or hydroxyl groups having 6 to 14 carbon atoms.)

3. 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 (B2-1) and repeating units represented by the following formula (B2-2). 【Transformation 7】 (In the formula, R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. b1 is 0 or 1. b2 is an integer between 0 and 2. b3 is an integer that satisfies 0 ≤ b3 ≤ 5 + 2b2 - b4. b4 is an integer between 1 and 3. b5 is 0 or 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. 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-. X is an acid-unstable group when b4 is 1, and when b4 is 2 or more, it is a hydrogen atom or an acid-unstable group, but at least one of them is an acid-unstable group. 【Transformation 8】 (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. 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 a naphthylene 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 These are, independently, hydrocarbyl groups having 1 to 10 carbon atoms, which may contain heteroatoms.

4. The chemically amplified positive resist composition according to claim 3, wherein b5 is 0.

5. 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). 【Chemistry 9】 (In the formula, d and e are each an integer between 0 and 4, independently of each other. f1 is 0 or 1. f2 is an integer between 0 and 5. f3 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 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, sulfinyl groups, or sulfonyl groups. 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 - may be replaced by -O-.)

6. 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 formulas (B6) to (B13). 【Chemistry 10】 (In the formula, R B Each of these is independently either a hydrogen atom or a methyl group. Y 1 This includes single bonds, aliphatic hydrocarbylene groups with 1 to 6 carbon atoms, phenylene groups, naphthylene groups, or groups with 7 to 18 carbon atoms obtained by combining these, -O-Y 11 -, -C(=O)-O-Y 11 - or -C(=O)-NH-Y 11 - and Y 11 This refers to 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 -O-Y. 31 -, -C(=O)-O-Y 31 - or -C(=O)-NH-Y 31 - and 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. 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. R 31 ~R 48 Each of these is independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. 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, 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.)

7. The chemically amplified positive resist composition according to claim 1, wherein the content ratio of (A) acid generator to (C) quencher is less than 6 by mass ratio.

8. 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 11】 (In the formula, 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, R 103 , R 106 , R 107 and R 108 When the group is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be interposed between the carbon-carbon bonds. R 109 is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may contain a heteroatom between carbon-carbon bonds or may have a heteroatom-containing group intervening between carbon-carbon bonds. R 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. 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. 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. 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 to a carbon atom in 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.)

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

10. 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 9; 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.

11. The resist pattern formation method according to claim 10, wherein the high-energy ray is an extreme ultraviolet ray or an electron ray.

12. The resist pattern forming method according to claim 10, 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.

13. The resist pattern forming method according to claim 10, wherein the substrate is a transmissive or reflective mask blank.

14. A transmissive or reflective mask blank coated with a chemically amplified positive resist composition according to any one of claims 1 to 9.

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