Chemically amplified positive resist composition and resist pattern forming method

Abstract

To provide a chemically amplified positive resist composition that can give a resist film which has extremely high isolated space resolution, small LER, excellent rectangularity, and on which formation of a resist pattern with suppressed etching resistance or pattern collapse is possible, and a resist pattern forming method using the chemically amplified positive resist composition.SOLUTION: A chemically amplified positive resist composition contains: (A) a base polymer which includes a repeating unit derived from hydroxystyrene or hydroxynaphthalene and a repeating unit derived from hydroxystyrene in which a hydroxy group is protected by acid-labile group or hydroxynaphthalene in which a hydroxy group is protected by acid-labile group, and in which dissolubility to alkali aqueous solution increases by acid action, and a dispersion degree is 1.0 to 1.19; (B) photo-acid generator expressed by the following formula (B); and (C) organic solvent.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] In recent years, the increasing integration density of integrated circuits has led to a demand for finer pattern formation, and chemically amplified resist compositions using acids as catalysts are primarily used for processing patterns of 0.2 μm or less. High-energy radiation, such as ultraviolet, far ultraviolet, extreme ultraviolet (EUV), and electron beam (EB), is used as the exposure source for this process. EB lithography, which is particularly used as an ultrafine processing technology, has also become essential as a method for processing photomask blanks when producing photomasks for semiconductor manufacturing.

[0003] In EB lithography, EB writing is typically performed without a mask. In positive-tone lithography, EBs are sequentially irradiated onto the resist film in areas other than the desired area, while in negative-tone lithography, EBs are sequentially irradiated onto the desired area. Because the EBs sweep across the entire finely divided area of ​​the processing surface, this process takes longer than one-shot exposure using a photomask. To maintain throughput, highly sensitive resist films are required. In particular, photomask blank processing, which is an important application, can involve surface materials, such as chromium oxide and other chromium compound films deposited on photomask substrates, that can easily affect the pattern shape of chemically amplified resist films. Maintaining a rectangular resist pattern profile, regardless of substrate type, is also an important performance requirement for maintaining high resolution and post-etching shape. Low line-edge roughness (LER) is also a key performance requirement. In recent years, in order to achieve miniaturization, a multi-beam mask writing (MBMW) drawing process is sometimes used to process mask blanks. In this case, a low-sensitivity resist composition (high dose region) that is advantageous for roughness is used, and optimization of the resist composition in this high dose region has also been attracting attention.

[0004] Various improvements have been made to control sensitivity and pattern profile by varying the selection and combination of materials used in resist compositions, process conditions, etc. One such improvement is the suppression of acid diffusion, which has a significant impact on the resolution of resist films. In photomask processing, it is required that the shape of the resulting resist pattern does not change depending on the time between exposure and heating. The main cause of time-dependent changes in resist pattern shape is the diffusion of acid generated by exposure. This issue of acid diffusion has been extensively studied, not only in photomask processing but also in general resist compositions, as it has a significant impact on sensitivity and resolution.

[0005] Patent Documents 1 and 2 describe examples in which acid diffusion is suppressed and LER is reduced by increasing the bulkiness of the acid generated from an acid generator. However, these acid generators still do not sufficiently suppress acid diffusion, and therefore, there has been a demand for the development of an acid generator with even smaller acid diffusion.

[0006] Patent Document 3 describes an example of controlling acid diffusion by introducing a repeating unit having a sulfonium structure that generates sulfonic acid upon exposure into a polymer used in a resist composition. This method of suppressing acid diffusion by introducing a repeating unit that generates acid upon exposure into a base polymer is effective as a method for obtaining a pattern with small LER. However, base polymers containing such repeating units that generate acid upon exposure can sometimes have problems with solubility in organic solvents, depending on the structure and introduction rate of the unit.

[0007] Polymers containing a large amount of aromatic skeletons with acidic side chains, such as substituted polyhydroxystyrenes obtained by partially functionalizing polyhydroxystyrenes, are useful as base polymers for KrF lithography resist compositions (Patent Documents 4 and 5). Radical polymerization and anionic polymerization are used to produce such base polymers, and several methods for producing substituted polystyrenes using anionic polymerization have been reported (Patent Documents 6 to 8). Because the aromatic rings in the base polymers exhibit high absorption at wavelengths around 200 nm, such substituted polyhydroxystyrenes have not been used as base polymers for next-generation ArF lithography resist compositions. However, they are important materials for resist compositions for EB lithography and EUV lithography, which are effective techniques for forming patterns smaller than the processing limit of ArF excimer laser light, because they provide high etching resistance.

[0008] The base polymers used in positive resist compositions for EB lithography and EUV lithography are primarily materials that are soluble in alkaline developers by deprotecting acid-labile groups that mask acidic functional groups on phenol side chains of the base polymer using an acid generated by irradiating a photoacid generator with high-energy rays as a catalyst. Examples of acid-labile groups that have been used include tertiary alkyl groups and tert-butoxycarbonyl groups, as well as acetal groups, which have a relatively low activation energy (Patent Documents 9 to 13).

[0009] Photoacid generators have also been improved. In particular, photoacid generators that generate aromatic sulfonic acids are used for positive EB lithography, and it has been confirmed that resolution can be improved by increasing the bulkiness of the molecular structure around the generated acid and of the entire anion in order to reduce excessive acid diffusion (Patent Documents 14 to 16).

[0010] In response to the recent demand for finer patterns, the development of these materials has resulted in some improvements in performance, but satisfactory results have not yet been achieved. In the future, there is a need for the development of resist compositions with even better resolution and various lithography performances. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-53518 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-100604 [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-22564 [Patent Document 4] Patent No. 4645789 [Patent Document 5] Patent No. 4742884 [Patent Document 6] Patent No. 3870527 [Patent Document 7] Patent No. 5121045 [Patent Document 8] Japanese Patent Application Publication No. 6-32832 [Patent Document 9] Patent No. 3981830 [Patent Document 10] Patent No. 5385017 [Patent Document 11] International Publication No. 2019 / 167419 [Patent Document 12] Patent No. 6987873 [Patent Document 13] Patent No. 5696254 [Patent Document 14] Patent No. 7032549 [Patent Document 15] Patent No. 6248882 [Patent Document 16] Patent No. 7067271 Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a chemically amplified positive resist composition that is capable of providing a resist film that can form a resist pattern that has extremely high isolated space resolution, small LER, excellent rectangularity, and that exhibits etching resistance and suppressed pattern collapse, and a method of forming a resist pattern that uses the chemically amplified positive resist composition. [Means for solving the problem]

[0013] As a result of extensive research into achieving the above-mentioned object, the inventors have found that by using a chemically amplified positive resist composition comprising a base polymer that is a narrowly dispersed polymer having a polymer dispersity of 1.01 to 1.19, the base polymer comprising a repeating unit derived from hydroxystyrene or hydroxynaphthalene and a repeating unit derived from hydroxystyrene whose hydroxy group is protected with an acid labile group or a hydroxynaphthalene whose hydroxy group is protected with an acid labile group, a photoacid generator that generates a specified aromatic sulfonic acid, and an organic solvent, it is possible to obtain a fine pattern that exhibits good isolated space resolution, pattern shape, and LER, has few residual defects, and exhibits excellent etching resistance after pattern formation, even in a high dose region, thereby completing the present invention.

[0014] That is, the present invention provides the following chemically amplified positive resist composition and method of forming a resist pattern. 1. (A) A base polymer which contains a repeating unit derived from hydroxystyrene or hydroxynaphthalene and a repeating unit derived from hydroxystyrene in which the hydroxy group is protected with an acid labile group or a repeating unit derived from hydroxynaphthalene in which the hydroxy group is protected with an acid labile group, and which exhibits increased solubility in an alkaline aqueous solution due to the action of acid, and which has a dispersity of 1.0 to 1.19; (B) a photoacid generator represented by the following formula (B), and (C) Organic solvent A chemically amplified positive resist composition comprising: [ka] (In the formula, m1 is 0 or 1. m2 is 0, 1, 2, 3, or 4. m3 is 0, 1, 2, 3, 4, 5, or 6. However, when m1 is 0, 0≦m2+m3≦4, and when m1 is 1, 0≦m3+m4≦6. m4 is 0 or 1. When m4 is 0, m5 is 0, 1, 2, 3, or 4, and when m4 is 1, m6 is 0 or 1. R 11is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom other than a fluorine atom, a hydroxy group, a nitro group, a cyano group, or a heteroatom. 11 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 12 is a halogen atom, a hydroxy group, a nitro group, a cyano group, or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 12 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R F is a fluorine atom, a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, a fluorinated saturated hydrocarbyloxy group having 1 to 6 carbon atoms or a fluorinated saturated hydrocarbylthio group having 1 to 6 carbon atoms. L A and L B are each independently a single bond, an ether bond, an ester bond, a sulfonate ester bond, a sulfonate amide bond, a carbonate bond or a carbamate bond. X L is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a hetero atom. Z + is an onium cation. 2. The chemically amplified positive resist composition of 1, wherein the weight average molecular weight of the base polymer is in the range of 1,000 to 50,000. 3. The chemically amplified positive resist composition of 1 or 2, wherein the repeating unit derived from hydroxystyrene or hydroxynaphthalene is represented by the following formula (A1): [ka] (In the formula, a1 is 0 or 1. a2 is 1, 2, or 3. a3 is 0, 1, 2, 3, or 4. However, when a1 is 0, 1≦a2+a3≦4, and when a1 is 1, 1≦a2+a3≦6. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 1 is a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. 4. The chemically amplified positive resist composition of any one of 1 to 3, wherein the repeating unit derived from the hydroxystyrene in which the hydroxy group is protected with an acid labile group or the hydroxynaphthalene in which the hydroxy group is protected with an acid labile group is represented by the following formula (A2): [ka] (In the formula, b1 is 0 or 1. b2 is 1, 2, or 3. b3 is 0, 1, 2, 3, or 4. However, when b1 is 0, 1≦b2+b3≦4, and when b1 is 1, 1≦b2+b3≦6. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 2 is a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. R AL is an acid labile group when b2 is 1, and is a hydrogen atom or an acid labile group when b2 is 2 or 3, provided that at least one is an acid labile group. The acid labile group is represented by any of the following formulae (AL-1) to (AL-3). [ka] (In the formula, R L1 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. R L2 , R L3 and R L4are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. L2 , R L3 and R L4 Any two or three of may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R L5 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. L2 , R L3 and R L4 One of the following and R L5 may be bonded to each other to form a ring together with the carbon atom and oxygen atom to which they are attached. R L6 , R L7 and R L8 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. L6 , R L7 and R L8 Any two of may be bonded to each other to form a ring together with the carbon atoms to which they are attached. The dashed lines represent bonds to the oxygen atoms in the formula. 5. The chemically amplified positive resist composition according to any one of 1 to 4, wherein the base polymer further comprises at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (A3), a repeating unit represented by the following formula (A4), and a repeating unit represented by the following formula (A5): [ka] (In the formula, c1 is 0 or 1. c2 is 0, 1, 2, 3, 4, or 5. d is 0, 1, 2, 3, 4, 5, or 6. e is 0, 1, 2, 3, or 4. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 3represents 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, or a cyano group, and when c1 is 1, it may be a hydroxy group. R 4 and R 5 are each independently a hydroxy group, a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. 6. The chemically amplified positive resist composition of any one of 1 to 5, wherein the photoacid generator is represented by the following formula (B1): [ka] (In the formula, m1~m5, R 11 , R 12 , R F , L A and Z + is the same as above.) 7.Z + is a sulfonium cation represented by the following formula (cation-1) or an iodonium cation represented by the following formula (cation-2): [ka] (In the formula, R 101 ~R 105 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. 101 and R 102 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. 8. The chemically amplified positive resist composition according to any one of 1 to 7, further comprising (D) a quencher. 9. The chemically amplified positive resist composition according to any one of 1 to 8, further comprising a fluorine atom-containing polymer containing at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (E1), a repeating unit represented by the following formula (E2), a repeating unit represented by the following formula (E3), and a repeating unit represented by the following formula (E4): [ka] (In the formula, R B are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 301 , R 302 , R 304 and R 305 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 303 , R 306 , R 307 and R 308 are each independently a hydrogen atom, a hydrocarbyl group having 1 to 15 carbon atoms, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid labile group, and R 203 , R 206 , R 207 and R 208 When is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bonds. n is 1, 2 or 3. Z 1 is an (n+1)-valent hydrocarbon group having 1 to 20 carbon atoms or an (n+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. 10. The chemically amplified positive resist composition of any one of 1 to 9, wherein the fluorine atom-containing polymer further comprises at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (E5) and a repeating unit represented by the following formula (E6): [ka] (In the formula, R C are each independently a hydrogen atom or a methyl group. R 309is a hydrogen atom or a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a group containing a hetero atom interposed between its carbon-carbon bond. R 310 is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a group containing a hetero atom interposed between its carbon-carbon bond. R 311 is a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom has been substituted with a fluorine atom, and some of the -CH2- groups in the saturated hydrocarbyl group may be substituted with an ester bond or an ether bond. x is 1, 2, or 3. y is an integer satisfying 0≦y≦5+2z−x. z is 0 or 1. Z 2 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. Z 3 is a single bond, -O-, *-C(=O)-OZ 31 -Z 32 -or*-C(=O)-NH-Z 31 -Z 32 -It is. Z 31 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. 32 is a single bond, an ester bond, an ether bond or a sulfonamide bond. * indicates a bond to a carbon atom in the main chain.) 11. A method for forming a resist pattern, comprising the steps of: forming a resist film on a substrate using the chemically amplified positive resist composition according to any one of 1 to 10; irradiating the resist film with a pattern using high-energy rays; and developing the resist film irradiated with the pattern using an alkaline developer. 12. The method for forming a resist pattern according to 11, wherein the high-energy radiation is KrF excimer laser light, ArF excimer laser light, EUV, or EB. 13. The method for forming a resist pattern according to 11 or 12, wherein the outermost surface of the substrate is made of a material containing at least one element selected from the group consisting of chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten, and tin. 14. The method for forming a resist pattern according to any one of 11 to 13, wherein the substrate is a transmission or reflection mask blank. 15. A transmission or reflection mask blank coated with any one of the chemically amplified positive resist compositions set forth in any one of 1 to 10. [Effects of the Invention]

[0015] The chemically amplified positive resist composition of the present invention is capable of forming a pattern with high resolution, small LER, and excellent rectangularity with a good shape after exposure, as well as a pattern with reduced influence of residual defects, and is therefore suitable as a resist composition for forming an EB-sensitive resist film used in the processing of semiconductors, photomask blanks, etc. Furthermore, a pattern formation method using the chemically amplified positive resist composition of the present invention is capable of forming a pattern with high resolution, etching resistance, reduced LER, and a pattern with reduced influence of residual defects, and is therefore suitable for use in microfabrication techniques, in particular EUV lithography and EB lithography. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention will be described in detail below. In the following description, some structures represented by chemical formulas may have asymmetric carbon atoms, and enantiomers or diastereomers may exist. In such cases, a single formula will be used to represent all isomers. These isomers may be used singly or as a mixture.

[0017] [Chemically amplified positive resist composition] The chemically amplified positive resist composition of the present invention contains, as component (A), a base polymer that contains a repeating unit derived from hydroxystyrene or hydroxynaphthalene, and a repeating unit derived from hydroxystyrene in which the hydroxy group is protected with an acid labile group, or a repeating unit derived from hydroxynaphthalene in which the hydroxy group is protected with an acid labile group, and whose solubility in an alkaline aqueous solution increases under the action of acid.

[0018] [(A) Base polymer] When the base polymer undergoes a deprotection reaction with an acid to generate an aromatic hydroxy group, the aromatic hydroxy group has a higher acidity than an aliphatic hydroxy group. Therefore, when a resist film is formed using a positive resist composition containing this and developed with an alkaline developer, the dissolution contrast between the exposed and unexposed areas is increased, resulting in good resolution.

[0019] The repeating unit derived from hydroxystyrene or hydroxynaphthalene is preferably one represented by the following formula (A1) (hereinafter also referred to as repeating unit A1). [ka]

[0020] In formula (A1), a1 is 0 or 1, and when it is 0, it represents a benzene skeleton, and when it is 1, it represents a naphthalene skeleton. a2 is 1, 2, or 3. a3 is 0, 1, 2, 3, or 4. However, when a1 is 0, 1≦a2+a3≦4, and when a1 is 1, 1≦a2+a3≦6. When a1 is 0, q is preferably 1, 2, or 3, and r is preferably 0, 1, 2, or 3. When p is 1, q is preferably 1, 2, or 3, and r is preferably 0, 1, 2, 3, or 4.

[0021] In formula (A1), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Among these, a hydrogen atom or a methyl group is preferred, and a hydrogen atom is more preferred from the viewpoint of polymerizability.

[0022] In formula (A1), R 1is a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. Specific examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The saturated hydrocarbyl group and the saturated hydrocarbyl moiety of the saturated hydrocarbyloxy group and saturated hydrocarbylcarbonyloxy group may be linear, branched, or cyclic. Specific examples include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, butyl, pentyl, hexyl, and structural isomers thereof; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl; and groups obtained by combining these. When the number of carbon atoms is equal to or less than the upper limit, the solubility in an alkaline developer is good. When a3 is 2 or more, each R 1 may be the same as or different from each other.

[0023] Preferred examples of the repeating unit A1 include, but are not limited to, the following: A is the same as above. [ka]

[0024] [ka]

[0025] [ka]

[0026] The content of the repeating unit A1 in the base polymer is preferably 40 to 90 mol %, more preferably 40 to 85 mol %, and even more preferably 40 to 80 mol % of all repeating units. The repeating unit A1 may be used alone or in combination of two or more types.

[0027] The repeating unit derived from hydroxystyrene in which the hydroxy group is protected with an acid labile group or hydroxynaphthalene in which the hydroxy group is protected with an acid labile group is preferably one represented by the following formula (A2) (hereinafter also referred to as repeating unit A2): [ka]

[0028] In formula (A2), b1 is 0 or 1. b2 is 1, 2, or 3. b3 is 0, 1, 2, 3, or 4. However, when b1 is 0, 1≦b2+b3≦4, and when b1 is 1, 1≦b2+b3≦6.

[0029] In formula (A2), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Among these, a hydrogen atom or a methyl group is preferred, and a hydrogen atom is more preferred from the viewpoint of polymerizability.

[0030] In formula (A2), R 2is a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. Specific examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The saturated hydrocarbyl group and the saturated hydrocarbyl moiety of the saturated hydrocarbyloxy group and saturated hydrocarbylcarbonyloxy group may be linear, branched, or cyclic. Specific examples include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, butyl, pentyl, hexyl, and structural isomers thereof; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl; and groups obtained by combining these. When the number of carbon atoms is equal to or less than the upper limit, the solubility in an alkaline developer is good. When b3 is 2 or more, each R 2 may be the same as or different from each other.

[0031] In formula (A2), R AL is an acid labile group when b2 is 1, and is a hydrogen atom or an acid labile group when b2 is 2 or 3, provided that at least one is an acid labile group.

[0032] The acid labile group is preferably one represented by any one of the following formulae (AL-1) to (AL-3). [ka] (In the formula, the dashed lines represent bonds.)

[0033] The group represented by formula (AL-1) or (AL-2) forms an acetal structure together with the oxygen atom derived from the aromatic hydroxy group in the repeating unit A2, and is used as an acid labile group, and is a useful option as an acid labile group that gives a stable pattern in which the interface between the pattern and the substrate is relatively rectangular.

[0034] In formula (AL-1), R L1is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. L2 , R L3 and R L4 R are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. L5 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom.

[0035] R L1 ~R L5 The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl; saturated cyclic hydrocarbyl groups having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, and cyclopropylmethyl; alkenyl groups having 2 to 20 carbon atoms, such as vinyl, 1-propenyl, 2-propenyl, butenyl, and hexenyl; unsaturated cyclic hydrocarbyl groups having 3 to 20 carbon atoms, such as cyclohexenyl; and aryl groups having 6 to 20 carbon atoms, such as phenyl and naphthyl.

[0036] Also, R L2 , R L3 and R L4 Any two or three of these may be bonded to each other to form a ring together with the carbon atoms to which they are bonded. Specific examples of the ring include, but are not limited to, a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, an adamantane ring, a benzene ring, and a naphthalene ring.

[0037] Furthermore, R L2 , R L3 and R L4 One of the following and R L5 may be bonded to each other to form a ring together with the carbon atom or oxygen atom to which they are bonded. Specific examples of the ring include, but are not limited to, a tetrahydrofuran ring, a tetrahydropyran ring, and the like.

[0038] The group represented by formula (AL-1) or (AL-2) is appropriately selected depending on the design of the sensitivity of the decomposable group to acid. For example, if the design is to decompose with strong acid while ensuring relatively high stability, a methylene acetal structure in which a hydrogen atom, which is the group represented by formula (AL-1), is substituted is selected. If the design is to increase sensitivity to pH changes by using relatively high reactivity, a group represented by formula (AL-2) in which -C(R L2 )(R L3 )(R L4 ) is a linear alkyl group. Depending on the combination with the acid generator and quencher to be added to the resist composition, L5 When a relatively large hydrocarbyl group is selected at the end of the R L2 , R L3 and R L4 Preferably, one of the carbon atoms bonded to the acetal carbon is a hydrogen atom and the carbon atom bonded to the acetal carbon is a secondary carbon atom. L2 )(R L3 )(R L4 Examples of ) include an isopropyl group, a sec-butyl group, a cyclopentyl group, and a cyclohexyl group.

[0039] Among the acetal groups, R L1 or R L5 is preferably a polycyclic saturated hydrocarbyl group having 7 to 30 carbon atoms. L1 or R L5 When R is a polycyclic saturated hydrocarbyl group, it is preferable that a bond is formed between a secondary carbon atom constituting the polycyclic ring structure and the acetal oxygen. When R is bonded on a secondary carbon atom of the ring structure, the polymer becomes a stable compound compared to when R is bonded on a tertiary carbon atom, and the storage stability of the resist composition is improved and resolution is not deteriorated. L1 or R L5is bonded to a primary carbon atom via a linear alkyl group having one or more carbon atoms, the polymer has a good glass transition temperature (Tg), and the developed resist pattern does not suffer from shape defects due to baking.

[0040] Specific examples of the acid labile group represented by formula (AL-1) or (AL-2) include, but are not limited to, the following: In the following formula, * represents a bond to the adjacent oxygen atom. [ka]

[0041] [ka]

[0042] The acetal-type acid labile group also has the effect of suppressing the influence of backscattering during EB writing. 2 More than 80μC / cm 2 More preferably, 100 μC / cm 2 In the above sensitivity range, the pattern shape does not become inversely tapered and rectangular performance is exhibited.

[0043] The group represented by formula (AL-3) is a tertiary hydrocarbyl group, which forms a tertiary ether structure together with the oxygen atom derived from the aromatic hydroxy group in the repeating unit A2 and is used as an acid labile group. Using a base polymer having a group represented by formula (AL-3) is preferred because it allows the resist film to be formed to a thickness of, for example, 10 to 100 nm, and even when a fine pattern having a line width of 45 nm or less is formed, it still provides a pattern with a small LER. The tertiary hydrocarbyl group preferably has 4 to 18 carbon atoms, so that the resulting polymerization monomer can be obtained by distillation. Furthermore, the group bonded to the tertiary carbon atom of the tertiary hydrocarbyl group may be a saturated hydrocarbyl group having 1 to 15 carbon atoms, which may contain an ether bond or an oxygen-containing functional group such as a carbonyl group, and the groups bonded to the tertiary carbon atom may be bonded to each other to form a ring.

[0044] In formula (AL-3), R L6 , R L7 and R L8 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R L1 ~R L5 Examples of the hydrocarbyl group represented by R include the same as those exemplified above. L6 , R L7 and R L8 Any two of may be bonded to each other to form a ring together with the carbon atoms to which they are attached.

[0045] Specific structures of the acid labile group represented by formula (AL-3) include, but are not limited to, the following: * represents a bond to the adjacent oxygen atom. [ka]

[0046] [ka]

[0047]

change

[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] Other acid labile groups that can be used include those in which the hydrogen atom of a phenolic hydroxy group is substituted with -O(C=O)O- (a tertiary saturated hydrocarbyl group), in which case the tertiary saturated hydrocarbyl group can be the same as the tertiary saturated hydrocarbyl group used to protect the phenolic hydroxy group described above.

[0057] The content of the repeating unit A2 in all repeating units of the polymer is preferably 10 to 40 mol %, more preferably 10 to 35 mol %, and even more preferably 20 to 30 mol %. The repeating unit A2 may be used alone or in combination of two or more types.

[0058] The polymer may further contain at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (A3) (hereinafter also referred to as repeating unit A3), a repeating unit represented by the following formula (A4) (hereinafter also referred to as repeating unit A4), and a repeating unit represented by the following formula (A5) (hereinafter also referred to as repeating unit A5). [ka]

[0059] In formula (A3), c1 is 0 or 1, and when it is 0, it represents a benzene skeleton, and when it is 1, it represents a naphthalene skeleton. c2 is 0, 1, 2, 3, 4, or 5. When c1 is 0, c2 is preferably 0, 1, 2, or 3, and when c2 is 1, c2 is preferably 0, 1, 2, 3, or 4.

[0060] In formula (A3), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0061] In formula (A3), R 3is 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, or a cyano group, and when c1 is 1, it may be a hydroxy 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 c2 is 2 or more, each R 3 may be the same as or different from each other.

[0062] In the formulae (A4) and (A5), d is 0, 1, 2, 3, 4, 5, or 6. e is 0, 1, 2, 3, or 4.

[0063] In formulas (A4) and (A5), R 4 and R 5 are each independently a hydroxy group, a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. 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 4 may be the same or different. When e is 2 or more, each R 5 may be the same as or different from each other.

[0064] When at least one selected from the repeating units A3 to A5 is used as a structural unit of the base polymer, the addition of a ring structure to the main chain provides the effect of improving etching resistance and EB irradiation resistance during pattern inspection in addition to the etching resistance of the aromatic ring.

[0065] To obtain the effect of improving etching resistance, the content of repeating units A3 to A5 is preferably 5 mol % or more of all repeating units constituting the polymer. Furthermore, the content of repeating units A3 to A5 is preferably 25 mol % or less, more preferably 20 mol % or less, of all repeating units constituting the polymer. When no functional group is present or when the functional group is other than a hydroxy group, it is preferable that the amount introduced is 25 mol % or less, since this does not cause development defects. Repeating units A3 to A5 may be used singly or in combination of two or more.

[0066] The base polymer is designed to have a dissolution rate in an alkaline developer of preferably 10 nm / min or less, more preferably 7 nm / min or less, and even more preferably 5 nm / min or less. In advanced-generation devices, when the coating film on the substrate is thin (100 nm or less), pattern film loss due to alkaline development becomes significant. If the polymer's alkaline dissolution rate exceeds 10 nm / min, the pattern collapses, making it impossible to form fine patterns. This is particularly noticeable in the production of photomasks, which require defect-free operation, since the development process tends to be intense. In this invention, the dissolution rate of the base polymer in an alkaline developer was calculated from the film loss observed when an 8-inch silicon wafer was spin-coated with a polymer solution (polymer concentration: 16.7 wt %, solvent: propylene glycol monomethyl ether acetate (PGMEA)), baked at 100°C for 90 seconds to form a 1000 nm-thick film, and then developed at 23°C for 100 seconds with a 2.38 wt % aqueous solution of tetramethylammonium hydroxide (TMAH).

[0067] The base polymer can be synthesized by copolymerizing the monomers that provide the repeating units described above by a known method. The monomers may be protected with a protecting group, and in this case, the polymer can be synthesized by carrying out a deprotection reaction after polymerization.

[0068] Alternatively, the base polymer can be synthesized by copolymerizing monomers containing the repeating unit A1 but not the repeating unit A2 to synthesize a polymer, and then protecting the aromatic hydroxyl groups of the polymer with acetal groups. Known methods for this include using a vinyl ether and an acid catalyst, and using an acetalizing agent having a haloalkoxy group together with a base, and either method can be used here.

[0069] For example, in the case of a method using an acetal modifying agent having a vinyl ether structure and an acid catalyst, specific examples of the acid catalyst include hydrochloric acid, sulfuric acid, nitric acid, methanesulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, trifluoroacetic acid, oxalic acid, methanesulfonic acid pyridine salt, etc. The reaction temperature is preferably 5°C to 30°C, and the reaction time is preferably 0.2 to 10 hours, more preferably 0.5 to 6 hours.

[0070] Furthermore, examples of a method using an acetal modifying agent having a haloalkoxy group together with a base include a method in which the acetal modifying agent having a haloalkoxy group is added dropwise in the presence of a basic compound such as triethylamine, diisopropylethylamine, pyridine, 2,6-lutidine, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, cesium carbonate, etc. In this case, the reaction temperature is preferably −20 to 50° C., and the reaction time is preferably 0.2 to 10 hours, more preferably 0.5 to 6 hours.

[0071] However, in the method of using an acetalizing agent having a haloalkoxy group together with a base, a corrosive strong acid such as hydrochloric acid is generated, which corrodes metal production vessels and piping, and there is a risk of contamination with metal components that may cause defects in semiconductor products. In particular, in the advanced generation, metal impurities in the raw materials used in resist compositions are required to be 10 ppb or less, so the method of using a vinyl ether and an acid catalyst is preferred.

[0072] The copolymerization reaction can be carried out by known methods such as radical polymerization and anionic polymerization, but is preferably carried out by anionic polymerization. Patent Documents 6 to 8 can be referred to for the anionic polymerization method.

[0073] The base polymer preferably has a weight-average molecular weight (Mw) of 1,000 to 50,000, more preferably 2,000 to 20,000. When Mw is 1,000 or more, there is no risk of the conventionally known phenomenon of pattern heads becoming rounded, resulting in reduced resolution and deterioration of LER. On the other hand, when Mw is 50,000 or less, there is no risk of LER deterioration, particularly when forming a pattern with a line width of 100 nm or less. In the present invention, Mw is a value measured in terms of polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran (THF) or dimethylformamide (DMF) as a solvent.

[0074] The base polymer preferably has a narrow polydispersity. Specifically, the polydispersity (Mw / Mn) of the base polymer is preferably 1.0 to 1.19, more preferably 1.0 to 1.17, and even more preferably 1.01 to 1.15. When the base polymer has such a narrow polydispersity, foreign matter is not generated on the pattern after development, and the pattern shape is not deteriorated.

[0075] The chemically amplified positive resist composition of the present invention is characterized by the use of a base polymer with a narrow dispersity of 1.0 to 1.19. When using a base polymer with a dispersity exceeding this range during fine pattern formation, the effect of different polymer chain lengths in the base polymer becomes significant, resulting in development defects and pattern collapse. Furthermore, each copolymerization unit contains an aromatic vinyl structure and a fused ring structure of acenaphthylene or indene, which facilitates π-π stacking interactions between aromatic rings, resulting in extremely high etching resistance after pattern formation. Furthermore, by using an aromatic sulfonic acid containing an aromatic ring structure as a photoacid generator, a rigid acid with low acid diffusion is generated, thereby suppressing excessive acid diffusion and improving various lithography performances. These synergistic effects result in good resolution when forming positive fine patterns using alkaline development, which is particularly advantageous for photomask processing in the 10 nm node and below generation.

[0076] [(B) Photoacid generator] The chemically amplified positive resist composition of the present invention contains a photoacid generator as component (B). The photoacid generator is a compound that generates an acid upon exposure to high-energy rays and is represented by the following formula (B): [ka]

[0077] In formula (B), m1 is 0 or 1. m2 is 0, 1, 2, 3, or 4. m3 is 0, 1, 2, 3, 4, 5, or 6. However, when m1 is 0, 0≦m2+m3≦4, and when m1 is 1, 0≦m3+m4≦6.

[0078] In formula (B), m4 is 0 or 1. When m4 is 0, it is a benzene ring, and when m4 is 1, it is a naphthalene ring, but from the viewpoint of solvent solubility, m4 is preferably a benzene ring of 0. When m4 is 0, m5 is 0, 1, 2, 3, or 4, and when m4 is 1, it is 0, 1, 2, 3, 4, 5, or 6. m6 is 0 or 1. From the viewpoint of controlling acid diffusion and preventing dissolution in an alkaline developer, m6 is preferably 1.

[0079] In formula (B), L A and L B are each independently a single bond, an ether bond, an ester bond, a sulfonate ester bond, a sulfonate amide bond, a carbonate bond, or a carbamate bond. Of these, a single bond, an ether bond, an ester bond, or a sulfonate ester bond is preferred. A More preferably, L is an ether bond, an ester bond, or a sulfonate ester bond. B is more preferably a single bond, an ether bond or an ester bond.

[0080] In formula (B), X L is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom. The hydrocarbylene group may be linear, branched, or cyclic, and specific examples thereof include an alkanediyl group and a cyclic saturated hydrocarbylene group. Specific examples of the heteroatom include an oxygen atom, a nitrogen atom, and a sulfur atom.

[0081] X L Specific examples of the hydrocarbylene group having 1 to 40 carbon atoms and optionally containing a hetero atom, represented by the formula (I), include, but are not limited to, those shown below. In the formula (I), * represents L A and L B Represents a bond with . [ka]

[0082] [ka]

[0083] [ka]

[0084] [ka]

[0085] Of these, X L -0~X L -22 and X L -47~X L -58 is preferred.

[0086] In formula (B), R 11is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a halogen atom other than a fluorine atom, a hydroxy group, a nitro group, a cyano group, or a heteroatom. Specific examples of the halogen atom other than a fluorine atom include a chlorine atom, a bromine atom, and an iodine atom. The hydrocarbyl group may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 20 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, or an icosyl group; a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cyclopropylmethyl group, or a 4-methyl Examples of the alkyl group include saturated cyclic hydrocarbyl groups having 3 to 20 carbon atoms, such as a cyclohexyl group, a cyclohexylmethyl group, a norbornyl group, and an adamantyl group; alkenyl groups having 2 to 20 carbon atoms, such as a vinyl group, an allyl group, a propenyl group, a butenyl group, and a hexenyl group; unsaturated cyclic hydrocarbyl groups having 3 to 20 carbon atoms, such as a cyclohexenyl group; aryl groups having 2 to 20 carbon atoms, such as a phenyl group and a naphthyl group; aralkyl groups having 7 to 20 carbon atoms, such as a benzyl group, a 1-phenylethyl group, and a 2-phenylethyl group; and groups obtained by combining these groups. In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH2- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, resulting in the hydrocarbyl group containing a hydroxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc. 11 may be the same as or different from each other.

[0087] Also, when m3 is 2 or more, multiple R11 However, they may be bonded to each other to form a ring together with the carbon atoms to which they are bonded. The ring is preferably a 5- to 8-membered ring.

[0088] Also, when m3 is 2 or more, multiple R 11 At least one of the -SO3 - It is preferably attached to a carbon atom adjacent to the carbon atom to which the group is attached.

[0089] In formula (B), R 12 is a halogen atom, a hydroxy group, a nitro group, a cyano group, or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. The halogen atom is preferably a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and more preferably a fluorine atom or an iodine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 11 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0090] Also, when m5 is 2 or more, multiple R 12 However, they may be bonded to each other to form a ring together with the carbon atoms to which they are bonded. The ring is preferably a 5- to 8-membered ring.

[0091] Also, when m5 is 2 or more, multiple R 12 At least one of the A It is preferable that the divalent linking group bonded to the aromatic ring be bonded to a carbon atom adjacent to the carbon atom on the aromatic ring to which the divalent linking group bonded to the aromatic ring is bonded. This is preferable because it suppresses the rotation of the bond of the divalent linking group bonding the two aromatic rings in the formula and controls the acid diffusion.

[0092] In formula (B), R Fis a fluorine atom, a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, a fluorinated saturated hydrocarbyloxy group having 1 to 6 carbon atoms, or a fluorinated saturated hydrocarbylthio group having 1 to 6 carbon atoms. Among these, a fluorine atom, a trifluoromethyl group, a trifluoromethoxy group, or a trifluoromethylthio group is preferred, and a fluorine atom is more preferred. When m2 is 2, 3, or 4, each R F may be the same as or different from each other.

[0093] The photoacid generator represented by formula (B) is preferably one represented by the following formula (B1). [ka] (In the formula, m1~m5, R 11 , R 12 , R F , L A and Z + is the same as above.)

[0094] Specific examples of the anion of the photoacid generator are preferably those shown below, but are not limited to these. [ka]

[0095] [ka]

[0096] [ka]

[0097] [ka]

[0098] [ka]

[0099]

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[0100]

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[0173] [ka]

[0174] [ka]

[0175] [ka]

[0176] [ka]

[0177] [ka]

[0178] [ka]

[0179] [ka]

[0180] [ka]

[0181] [ka]

[0182] In formula (B), Z + is an onium cation. The onium cation is preferably a sulfonium cation represented by the following formula (cation-1) or an iodonium cation represented by the following formula (cation-2). [ka]

[0183] In formulas (cation-1) and (cation-2), R 101 ~R 105 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom.

[0184] R 101 ~R 105 Specific examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0185] R 101 ~R 105The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 30 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl; saturated cyclic hydrocarbyl groups having 3 to 30 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups having 2 to 30 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl; unsaturated cyclic hydrocarbyl groups having 3 to 30 carbon atoms, such as cyclohexenyl; aryl groups having 6 to 30 carbon atoms, such as phenyl, naphthyl, and thienyl; aralkyl groups having 7 to 30 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl; and groups obtained by combining these, with aryl groups being preferred. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a cyano group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0186] Also, R 101 and R 102 However, they may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, specific examples of the ring structure include those represented by the following formulas. [ka] (In the formula, the dashed line indicates R 103 )

[0187] Specific examples of the sulfonium cation represented by formula (cation-1) include, but are not limited to, those shown below. [ka]

[0188] [ka]

[0189] [ka]

[0190] [ka]

[0191] [ka]

[0192] [ka]

[0193] [ka]

[0194] [ka]

[0195] [ka]

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[0208] [ka]

[0209] [ka]

[0210] [ka]

[0211] [ka]

[0212] [ka]

[0213] [ka]

[0214] Specific examples of the iodonium cation represented by formula (cation-2) include, but are not limited to, those shown below. [ka]

[0215] [ka]

[0216] Specific examples of the photoacid generator include any combination of the above-mentioned anions and cations.

[0217] In the chemically amplified positive resist composition of the present invention, the content of the (B) photoacid generator is preferably 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass, relative to 80 parts by mass of the (A) base polymer. When the content of the (B) photoacid generator is within the above range, an amount of acid necessary for deprotecting the acid labile groups is generated, resulting in a good pattern shape. Furthermore, the composition also has good storage stability. The (B) photoacid generators may be used singly or in combination of two or more.

[0218] The chemically amplified positive resist composition of the present invention may further contain an acid generator other than the photoacid generator represented by formula (B) (hereinafter also referred to as "other acid generator") for the purpose of correcting the shape of a pattern, etc. As the other acid generator, any known acid generator for use in a resist composition can be used. From the viewpoints of sensitivity and acid diffusion suppression effect, the content of the other acid generator is preferably 0 to 40 parts by mass, and more preferably 0 to 30 parts by mass, relative to 80 parts by mass of the (A) base polymer. The other acid generators may be used alone, or two or more types may be used in combination.

[0219] [(C) Organic solvent] The chemically amplified positive resist composition of the present invention contains an organic solvent as component (C). There are no particular restrictions on the organic solvent, so long as it is capable of dissolving the individual components. Examples of such organic solvents include ketones such as cyclohexanone and methyl-2-n-pentyl ketone, as described in paragraphs

[0144] and

[0145] of Japanese Patent Application Laid-Open No. 2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol; ethers such as propylene glycol monomethyl ether (PGME), ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as PGMEA, ethyl lactate (EL), ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol mono-tert-butyl ether acetate; lactones such as γ-butyrolactone; and mixed solvents thereof. When an acetal-based acid labile group is used, a high-boiling alcohol solvent, specifically, diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, 1,3-butanediol, or the like may be added to accelerate the deprotection reaction of the acetal.

[0220] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, PGME, cyclohexanone, EL, γ-butyrolactone, and mixed solvents thereof are preferred.

[0221] In the chemically amplified positive resist composition of the present invention, the content of the (C) organic solvent is preferably 200 to 10,000 parts by mass, and more preferably 400 to 5,000 parts by mass, relative to 80 parts by mass of the (A) base polymer. The organic solvent may be used alone, or two or more types may be mixed and used.

[0222] [(D) Quencher] The chemically amplified positive resist composition of the present invention preferably contains a quencher (acid diffusion inhibitor). Examples of the quencher include conventional basic compounds. Examples of conventional basic compounds include primary, secondary, and tertiary aliphatic amines, mixed 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, and carbamates. In particular, the primary, secondary, and tertiary amine compounds described in paragraphs

[0146] to

[0164] of JP 2008-111103 A are preferred, including amine compounds having a hydroxyl group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonate ester bond, and compounds having a carbamate group described in Japanese Patent Publication No. 3790649 A. Preferred examples include tris[2-(methoxymethoxy)ethyl]amine, tris[2-(methoxymethoxy)ethyl]amine-N-oxide, dibutylaminobenzoic acid, morpholine derivatives, imidazole derivatives, etc. Addition of such basic compounds can, for example, further suppress the diffusion rate of acid in the resist film or correct the shape.

[0223] Further, examples of the quencher include onium salts such as sulfonium salts, iodonium salts, and ammonium salts of carboxylic acids not fluorinated at the α-position, as described in JP-A-2008-158339. Sulfonic acids, imide acids, or methide acids fluorinated at the α-position are necessary for deprotecting acid labile groups, and salt exchange with onium salts not fluorinated at the α-position releases carboxylic acids not fluorinated at the α-position. Carboxylic acids not fluorinated at the α-position hardly undergo deprotection reactions, and therefore function as quenchers.

[0224] Examples of onium salts of carboxylic acids that are not fluorinated at the α-position include those represented by the following formula (D1). [ka]

[0225] In formula (D1), R 201 represents a hydrocarbyl group having 1 to 40 carbon atoms 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 carboxy group is substituted with a fluorine atom or a fluoroalkyl group.

[0226] R 201 The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 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; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0]. 2,6 ]Cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms such as a decyl group, an adamantyl group, and an adamantylmethyl group; alkenyl groups having 2 to 40 carbon atoms such as a vinyl group, an allyl group, a propenyl group, a butenyl group, and a hexenyl group; cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 40 carbon atoms such as a cyclohexenyl group; phenyl group, naphthyl group, alkylphenyl groups (2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butylphenyl group, Examples of aryl groups include aryl groups having 6 to 40 carbon atoms such as arylphenyl groups (e.g., 2,4-n-butylphenyl group, 4-n-butylphenyl group), di- or trialkylphenyl groups (e.g., 2,4-dimethylphenyl group, 2,4,6-triisopropylphenyl group), alkylnaphthyl groups (e.g., methylnaphthyl group, ethylnaphthyl group), and dialkylnaphthyl groups (e.g., dimethylnaphthyl group, diethylnaphthyl group); and aralkyl groups having 7 to 40 carbon atoms such as benzyl group, 1-phenylethyl group, and 2-phenylethyl group.

[0227] Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a cyano group, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like. Examples of the hydrocarbyl group containing a heteroatom include heteroaryl groups such as a thienyl group; alkoxyphenyl groups such as a 4-hydroxyphenyl group, a 4-methoxyphenyl group, a 3-methoxyphenyl group, a 2-methoxyphenyl group, a 4-ethoxyphenyl group, a 4-tert-butoxyphenyl group, and a 3-tert-butoxyphenyl group; alkoxynaphthyl groups such as a methoxynaphthyl group, an ethoxynaphthyl group, an n-propoxynaphthyl group, and an n-butoxynaphthyl group; dialkoxynaphthyl groups such as a dimethoxynaphthyl group and a diethoxynaphthyl group; and aryloxoalkyl groups such as a 2-aryl-2-oxoethyl group, a 2-(1-naphthyl)-2-oxoethyl group, and a 2-(2-naphthyl)-2-oxoethyl group.

[0228] In formula (D1), Mq A + 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 include those exemplified as specific examples of the sulfonium cation represented by formula (cation-1). Specific examples of the iodonium cation include those exemplified as specific examples of the iodonium cation represented by formula (cation-2).

[0229] Examples of the anion of the onium salt represented by formula (D1) include, but are not limited to, those shown below. [ka]

[0230] [ka]

[0231] [ka]

[0232] As the quencher, a sulfonium salt of an iodinated benzene ring-containing carboxylic acid represented by the following formula (D2) can also be suitably used. [ka]

[0233] In formula (D2), s is an integer of 1 to 5. t is an integer of 0 to 3, provided that 1≦s+t≦5. u is an integer of 1 to 3.

[0234] In formula (D2), R 211 represents a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an amino group, a nitro group, a cyano group, or 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, in which some or all of the hydrogen atoms may be substituted with halogen atoms, or -N(R 211A )-C(=O)-R 211B or -N(R 211A )-C(=O)-OR 211B R 211A is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 221B 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 is 2 or more, each R 211 may be the same or different from each other.

[0235] In formula (D2), L 11 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 hydroxy group, and a carboxy group. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, and saturated hydrocarbylsulfonyloxy group may be linear, branched, or cyclic.

[0236] In formula (D2), R 212 , R 213 and R 214 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples thereof include an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms. Some or all of the hydrogen atoms in the hydrocarbyl group may be substituted with a hydroxy group, a carboxy group, a halogen atom, an oxo group, a cyano group, a nitro group, a sultone ring, a sulfo group, or a sulfonium salt-containing group. Some of the -CH2- groups in the hydrocarbyl group may be substituted with an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate bond, or a sulfonate ester bond. Furthermore, R 212 and R 213 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

[0237] Specific examples of the compound represented by formula (D2) include those described in JP 2017-219836 A. The compound represented by formula (D2) has high absorption, a high sensitizing effect, and a high acid diffusion control effect.

[0238] As the quencher, a nitrogen atom-containing carboxylate compound represented by the following formula (D3) can also be used. [ka]

[0239] In formula (D3), R 221 ~R 224 are each independently a hydrogen atom, -L 12 -CO2 - or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. 221 and R 222 and R 222 and R 223 and, or R 223 and R 224 and may be bonded to each other to form a ring together with the carbon atoms to which they are attached. 12 R is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 225 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom.

[0240] In formula (D3), ring R r is a ring containing carbon atoms and nitrogen atoms and having 2 to 6 carbon atoms, and some or all of the hydrogen atoms bonded to the carbon atoms of the ring are hydrocarbyl groups having 1 to 20 carbon atoms, or -L 12 -CO2 - and some of the carbon atoms of the ring may be substituted with sulfur atoms, oxygen atoms, or nitrogen atoms. The ring may be an alicyclic ring or an aromatic ring, and is preferably a 5- or 6-membered ring, specific examples of which include a pyridine ring, a pyrrole ring, a pyrrolidine ring, a piperidine ring, a pyrazole ring, an imidazoline ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, an imidazoline ring, an oxazole ring, a thiazole ring, a morpholine ring, a thiazine ring, and a triazole ring.

[0241] The onium carboxylic acid salt represented by formula (D3) has at least one -L 12 -CO2 - group, i.e., R 221 ~R 224 At least one of the12 -CO2 - and / or at least one of the hydrogen atoms bonded to the carbon atom of the ring R is -L 12 -CO2 - is replaced by

[0242] In formula (D3), Mq B + is a sulfonium cation, an iodonium cation, or an ammonium cation, and is preferably a sulfonium cation. Specific examples of the sulfonium cation include the same as those exemplified as specific examples of the sulfonium cation represented by formula (cation-1).

[0243] Examples of the anion of the compound represented by formula (D3) include, but are not limited to, those shown below. [ka]

[0244] [ka]

[0245] [ka]

[0246] [ka]

[0247] [ka]

[0248] [ka]

[0249] Furthermore, a weak acid betaine type compound can also be used as the quencher. Specific examples thereof include, but are not limited to, the following: [ka]

[0250] Further examples of the quencher include the polymer-type quencher described in JP 2008-239918 A. This quencher enhances the rectangularity of the resist pattern by orienting on the surface of the resist film. The polymer-type quencher also has the effect of preventing pattern film loss and pattern top rounding when a protective film for immersion lithography is applied.

[0251] When the chemically amplified positive resist composition of the present invention contains a quencher (E), the content thereof is preferably from 0 to 50 parts by mass, and more preferably from 0.1 to 40 parts by mass, relative to 80 parts by mass of the base polymer. The quenchers may be used singly or in combination of two or more.

[0252] When the chemically amplified positive resist composition of the present invention contains both a photoacid generator and a quencher, the content ratio of the photoacid generator to the quencher (photoacid generator / quencher) is preferably less than 3 by mass, more preferably less than 2.5, and even more preferably less than 2. When the content ratio of the photoacid 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.

[0253] [(E) Fluorine atom-containing polymer] The chemically amplified positive resist composition of the present invention may contain a fluorine atom-containing polymer containing at least one repeating unit selected from the group consisting of a repeating unit represented by formula (E1) (hereinafter also referred to as repeating unit E1), a repeating unit represented by formula (E2) (hereinafter also referred to as repeating unit E2), a repeating unit represented by formula (E3) (hereinafter also referred to as repeating unit E3), and a repeating unit represented by formula (E4) (hereinafter also referred to as repeating unit E4) for the purposes of achieving high contrast, suppressing the chemical flare phenomenon of acids caused by high-energy radiation exposure, shielding acid from mixing from an antistatic coating during the process of applying an antistatic coating material onto a resist film, and suppressing unexpected and unnecessary pattern degradation. The fluorine atom-containing polymer also functions as a surfactant, preventing insoluble matter from reattaching to the substrate during the development process, thereby effectively reducing development defects. [ka]

[0254] In formulas (E1) to (E4), R B are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 301 , R 302 , R 304 and R 305 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. 303 , R 306 , R 307 and R 308 are each independently a hydrogen atom, a hydrocarbyl group having 1 to 15 carbon atoms, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid labile group, and R 203 , R 206 , R 207 and R 208 When Z is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bonds. n is 1, 2 or 3. 1 is an (n+1)-valent hydrocarbon group having 1 to 20 carbon atoms or an (n+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms.

[0255] R 301 , R 302 , R 304 and R 305 The saturated hydrocarbyl group having 1 to 10 carbon atoms represented by the formula (I) may be linear, branched, or cyclic, and specific examples thereof include alkyl groups having 1 to 10 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl; and cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, and norbornyl. Of these, saturated hydrocarbyl groups having 1 to 6 carbon atoms are preferred.

[0256] R 303 , R 306 , R 307 and R 308 The hydrocarbyl group having 1 to 15 carbon atoms represented by the formula (I) may be linear, branched, or cyclic, and specific examples thereof include an alkyl group having 1 to 15 carbon atoms, an alkenyl group having 2 to 15 carbon atoms, and an alkynyl group having 2 to 15 carbon atoms, with an alkyl group having 1 to 15 carbon atoms being preferred. Examples of the alkyl group include those mentioned above, as well as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, and n-pentadecyl. Examples of the fluorinated hydrocarbyl group include groups in which some or all of the hydrogen atoms bonded to carbon atoms in the hydrocarbyl group mentioned above have been substituted with fluorine atoms.

[0257] Z 1 Examples of the (n+1)-valent hydrocarbon group having 1 to 20 carbon atoms and represented by the formula (I) include a group in which n hydrogen atoms have been further removed from an alkyl group having 1 to 20 carbon atoms or a cyclic saturated hydrocarbyl group having 3 to 20 carbon atoms. 1Examples of the (n+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include groups in which at least one hydrogen atom of the aforementioned (n+1)-valent hydrocarbon group has been substituted with a fluorine atom.

[0258] Specific examples of the repeating units E1 to E4 include, but are not limited to, the following: B is the same as above. [ka]

[0259] [ka]

[0260] [ka]

[0261] Furthermore, it is preferable that the fluorine atom-containing polymer further contains at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (E5) (hereinafter also referred to as repeating unit E5) and a repeating unit represented by the following formula (E6) (hereinafter also referred to as repeating unit E6). [ka]

[0262] In formulas (E5) and (E6), R C are each independently a hydrogen atom or a methyl group. 309 R is a hydrogen atom or a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a heteroatom-containing group interposed between its carbon-carbon bond. 310 R is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, which may have a heteroatom-containing group interposed between its carbon-carbon bond. 311is a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom has been substituted with a fluorine atom, and some of the -CH2- groups in the saturated hydrocarbyl group may be substituted with an ester bond or an ether bond. x is 1, 2, or 3. y is an integer satisfying the relationship 0≦y≦5+2z-x. z is 0 or 1. Z 2 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. 3 is a single bond, -O-, *-C(=O)-OZ 31 -Z 32 -or*-C(=O)-NH-Z 31 -Z 32 -It is. Z 31 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. 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.

[0263] R 309 and R 310 Examples of the hydrocarbyl group having 1 to 5 carbon atoms represented by the formula (I) include an alkyl group, an alkenyl group, and an alkynyl group, with an alkyl group being preferred. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and an n-pentyl group. In addition, a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom may be present between the carbon-carbon bonds of the hydrocarbyl group.

[0264] -OR in formula (E5) 309 is preferably a hydrophilic group. 309 As the alkyl group, a hydrogen atom, an alkyl group having 1 to 5 carbon atoms and an oxygen atom intervening between the carbon-carbon bonds, and the like are preferred.

[0265] R 311The saturated hydrocarbyl group having 1 to 20 carbon atoms, represented by the formula (I) above, in which at least one hydrogen atom has been substituted with a fluorine atom, may be linear, branched, or cyclic, and specific examples thereof include an alkyl group having 1 to 20 carbon atoms or a cyclic saturated hydrocarbyl group having 3 to 20 carbon atoms in which at least one hydrogen atom has been substituted with a fluorine atom.

[0266] Z 2 is preferably *-C(=O)-O- or *-C(=O)-NH-. C is preferably a methyl group. 2 The presence of a carbonyl group in R improves the acid trapping ability of the antistatic film. C When the methyl group is used, the polymer becomes more rigid with a higher glass transition temperature (Tg), which suppresses acid diffusion, resulting in good stability of the resist film over time and preventing degradation of resolution and pattern shape.

[0267] Z 3 The saturated hydrocarbylene group having 1 to 10 carbon atoms represented by the formula (I) may be linear, branched, or cyclic, and specific examples thereof include a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,1-diyl group, a propane-1,2-diyl group, a propane-1,3-diyl group, a propane-2,2-diyl group, a butane-1,1-diyl group, a butane-1,2-diyl group, a butane-1,3-diyl group, a butane-2,3-diyl group, a butane-1,4-diyl group, and a 1,1-dimethylethane-1,2-diyl group.

[0268] Specific examples of the repeating unit E5 include, but are not limited to, those shown below. C is the same as above. [ka]

[0269] [ka]

[0270] Specific examples of the repeating unit E6 include, but are not limited to, those shown below. C is the same as above. [ka]

[0271] [ka]

[0272] [ka]

[0273] [ka]

[0274] The content of repeating units E1 to E4 is preferably 15 to 95 mol %, more preferably 20 to 85 mol %, of all repeating units in the fluorine atom-containing polymer. The content of repeating units E5 and / or E6 is preferably 5 to 85 mol %, more preferably 15 to 80 mol %, of all repeating units in the fluorine atom-containing polymer. The repeating units E1 to E6 may be used alone or in combination of two or more.

[0275] The fluorine atom-containing polymer may contain repeating units other than the repeating units described above. Examples of such repeating units include those described in paragraphs

[0046] to

[0078] of JP 2014-177407 A. When the fluorine atom-containing polymer contains other repeating units, the content of such other repeating units is preferably 50 mol % or less of all repeating units of the fluorine atom-containing polymer.

[0276] The fluorine atom-containing polymer can be synthesized by copolymerizing each monomer, optionally protected with a protecting group, according to a known method, followed by a deprotection reaction as needed. The copolymerization reaction is not particularly limited, but is preferably radical polymerization or anionic polymerization. For these methods, reference can be made to JP 2004-115630 A.

[0277] The Mw of the fluorine atom-containing polymer is preferably 2000 to 50000, more preferably 3000 to 20000. When the Mw is 2000 or more, the acid does not diffuse, the resolution does not deteriorate, and the stability over time is not impaired. When the Mw is 50000 or less, the solubility in solvents is sufficient and coating defects do not occur. Furthermore, the fluorine atom-containing polymer preferably has an Mw / Mn ratio of 1.0 to 2.2, more preferably 1.0 to 1.7.

[0278] When the chemically amplified positive resist composition of the present invention contains (E) a fluorine atom-containing polymer, the content thereof is preferably from 0.01 to 30 parts by mass, more preferably from 0.1 to 20 parts by mass, and even more preferably from 0.5 to 10 parts by mass, relative to 80 parts by mass of the (A) base polymer. The (E) fluorine atom-containing polymer may be used alone, or two or more types may be used in combination.

[0279] [(F) Surfactant] The chemically amplified positive resist composition of the present invention may contain a commonly used surfactant to improve its coatability onto a substrate. When using a surfactant, many known surfactants are available, as described in JP-A-2004-115630, and the surfactant can be selected with reference to these. When the chemically amplified positive resist composition of the present invention contains the surfactant (F), the content is preferably 0 to 5 parts by mass per 80 parts by mass of the base polymer (A). The surfactant (F) may be used alone, or two or more types may be used in combination. When the chemically amplified positive resist composition of the present invention contains the fluorine atom-containing polymer, the fluorine atom-containing polymer also functions as a surfactant, so the surfactant need not be included.

[0280] The chemically amplified positive resist composition of the present invention can be prepared by dissolving the base polymer and, if necessary, components other than the base polymer in an organic solvent simultaneously or in any order to form a homogeneous resist solution. The resulting resist solution is preferably filtered. Using a filter made of nylon or polyethylene (PE) for filtration can effectively remove gel components and particles contained in the resist solution. Furthermore, it is preferable to use a filter with a pore size of 20 nm or less to maintain quality for advanced generations.

[0281] The dissolution rate of the unexposed portions of a resist film obtained from the chemically amplified positive resist composition of the present invention in an alkaline developer is preferably 10 nm / min or less, more preferably 9 nm / min or less, and even more preferably 8 nm / min or less. When the resist film is thin (thickness 100 nm or less), the pattern is significantly affected by loss of film thickness in the alkaline developer. Therefore, if the dissolution rate of the unexposed portions is 10 nm / min or less, the pattern will not collapse and fine patterns can be formed. This is particularly noticeable in the production of photomasks, which require a defect-free environment, because the development process tends to be intense. The dissolution rate of the unexposed portions was calculated from the amount of film loss when a 150 mm (6-inch) silicon wafer was spin-coated with the chemically amplified positive resist composition of the present invention, baked at 110°C for 240 seconds to form an 80 nm-thick resist film, and then developed at 23°C for 80 seconds in a 2.38 wt% TMAH aqueous solution.

[0282] In addition, the dissolution rate of the exposed portion of a resist film obtained from the chemically amplified positive resist composition of the present invention in an alkaline developer is preferably 50 nm / sec or more, more preferably 80 nm / sec or more, from the viewpoint of improving development loading. A dissolution rate of 50 nm / sec or more allows the resist film to dissolve uniformly in an alkaline developer, even if there are differences in the pattern layout of sparse and dense patterns, thereby reducing linewidth fluctuations. The dissolution rate of the exposed portion was calculated from the film loss amount when the chemically amplified positive resist composition of the present invention was spin-coated onto a 200 mm (8-inch) silicon wafer and baked at 110°C for 60 seconds to form a resist film with a thickness of 90 nm, exposed to KrF excimer laser light with an energy amount sufficient to complete the deprotection reaction of the polymer, baked at 110°C for 60 seconds, and then developed at 23°C in a 2.38 wt% TMAH aqueous solution using a resist development analyzer.

[0283] [Method for forming resist pattern] The method for forming a resist pattern of the present invention includes the steps of: forming a resist film on a substrate using the aforementioned chemically amplified positive resist composition; 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.

[0284] The substrate may be, for example, a substrate used for manufacturing integrated circuits (Si, SiO, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective coating, etc.), or a substrate used for manufacturing transmission or reflection mask circuits (Cr, CrO, CrON, MoSi2, Si, SiO, SiO2, SiON, SiONC, CoTa, NiTa, TaBN, SnO2, etc.). 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 the composition is then 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.

[0285] Next, the resist film is exposed to high-energy rays to form a pattern. Examples of the high-energy rays include KrF excimer laser light, ArF excimer laser light, EB, and EUV having a wavelength of 3 to 15 nm. In the present invention, exposure using EB is preferred. In order to form a desired pattern, the exposure dose of EB is preferably 50 to 400 μC / cm. 2 When the chemically amplified positive resist composition of the present invention contains a base polymer containing an acetal-type acid labile group, the radiation intensity is preferably 50 μC / cm because this also has the effect of suppressing the influence of backscattering during EB writing. 2 More preferably, 80 μC / cm 2 More preferably, 100 μC / cm 2 In the above-mentioned sensitivity region, the pattern shape does not become inversely tapered, and rectangular performance can be exhibited.

[0286] The exposure may be performed by a conventional exposure method or, in some cases, by an immersion method in which the space between the mask and the resist film is immersed in liquid. In this case, a water-insoluble protective film may be used.

[0287] Next, post-exposure baking (PEB) is carried out 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.

[0288] Thereafter, the substrate is developed using a developer such as an aqueous alkaline solution of 0.1 to 5 mass %, preferably 2 to 3 mass % TMAH or the like, for preferably 0.1 to 3 minutes, more preferably 0.5 to 2 minutes, by a conventional method such as dipping, puddling, or spraying, to form a desired pattern on the substrate.

[0289] The chemically amplified positive resist composition of the present invention is useful because it can form a pattern with particularly good isolated space resolution and small LER. Furthermore, the chemically amplified positive resist composition of the present invention is particularly useful for pattern formation on a substrate having a surface made of a material that is prone to pattern peeling or pattern collapse, due to the difficulty in achieving resist pattern adhesion. Such a substrate is preferably one whose outermost surface is made of a material containing at least one selected from chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten, and tin. Examples of such a substrate include a substrate having a sputtering film of metallic chromium or a chromium compound containing one or more light elements selected from oxygen, nitrogen, and carbon formed on its outermost surface, SiO , SiO X Examples of suitable substrates include substrates containing a tantalum compound, a molybdenum compound, a cobalt compound, a nickel compound, a tungsten compound, or a tin compound in the 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. In other words, a transmissive or reflective type mask blank coated with the above-mentioned chemically amplified positive resist composition is preferred.

[0290] As a transmission mask blank, a photomask blank having a light-shielding film made of a chromium-based material may be a photomask blank for a binary mask or a photomask blank for a phase shift mask. In the case of a photomask blank for a binary mask, the light-shielding film may have an antireflection layer and a light-shielding layer made of a chromium-based material, or the entire antireflection film on the surface layer side or only the layer further above the antireflection film on the surface layer side may be made of a chromium-based material, with the remaining portion being made of a silicon-based compound material that may contain, for example, a transition metal. In addition, in the case of a photomask blank for a phase shift mask, the target photomask blank may be a photomask blank for a phase shift mask having a chromium-based light-shielding film on a phase shift film.

[0291] The above-mentioned photomask blank having a chromium-based material in the outermost layer is very well known, as is disclosed in JP-A Nos. 2008-26500 and 2007-302873, or as examples of prior art therein. Therefore, detailed description will be omitted. However, for example, when a light-shielding film having an antireflection layer and a light-shielding layer is formed using a chromium-based material, the following film configuration can be used.

[0292] When a light-shielding film having an anti-reflection layer and a light-shielding layer is formed using a chromium-based material, the layer structure may be such that the anti-reflection layer and the light-shielding layer are laminated in this order from the surface side, or the anti-reflection layer, the light-shielding layer, and the anti-reflection layer are laminated in this order. The anti-reflection layer and the light-shielding layer may each be multi-layered, and the composition between layers with different compositions may change discontinuously or continuously. The chromium-based material used includes metallic chromium and metallic chromium containing light elements such as oxygen, nitrogen, and carbon. Specifically, metallic chromium, chromium oxide, chromium nitride, chromium carbide, chromium oxide nitride, chromium carbide oxide, chromium nitride carbonitride, chromium oxynitride carbonitride, etc. may be used.

[0293] A reflective mask blank includes a substrate, a multilayer reflective film formed on one main surface (front surface) 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 reflectance. From the reflective mask blank (EUV reflective mask blank), a reflective mask (EUV reflective mask) is manufactured having an absorber pattern (absorber film pattern) formed by patterning the absorber film. The wavelength of EUV light used in EUV lithography is 13 to 14 nm, and is typically light with a wavelength of about 13.5 nm.

[0294] Although the multilayer reflective film is preferably provided in contact with one main surface of the substrate, a base film may be provided between the substrate and the multilayer reflective film as long as 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 repair. Furthermore, the protective film preferably 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. Meanwhile, a conductive film used for electrostatically chucking the reflective mask to an exposure device may be provided under the other main surface (back surface) of the substrate, which is the surface opposite to the one main surface, preferably in contact with the other main surface. Here, one main surface of the substrate is the front surface and the upper side, and the other main surface is the back surface and the lower side, but the front and back and top and bottom of both are defined for convenience, and the one main surface and the other main surface are either of the two main surfaces (film formation surfaces) of the substrate, and the front and back and top and bottom are interchangeable. More specifically, it can be formed by a method such as that described in JP 2021-139970 A or exemplified as prior art therein.

[0295] According to the method for forming a resist pattern of the present invention, even when a substrate (e.g., a transmission or reflection type mask blank) is used whose outermost surface is made of a material that is likely to affect the shape of the resist pattern, such as a material containing chromium, silicon, or tantalum, it is possible to obtain a pattern with high resolution and small dimensional difference that is independent of pattern density and in which the effects of development loading and residue defects are suppressed. [Example]

[0296] The present invention will be specifically described below with reference to Synthesis Examples, Examples, and Comparative Examples, but the present invention is not limited to the following Examples. In the Synthesis Examples, the copolymer composition ratio is a molar ratio, and Mw is a weight average molecular weight in terms of polystyrene measured by GPC.

[0297] [1] Polymer synthesis [Synthesis Example 1] Synthesis of Polymer P-1 (1) Synthesis of poly(p-tert-butoxycarbonyloxystyrene) A 2L flask was charged with THF (1200mL) as a solvent and n-butyllithium (0.005 mole equivalent) as a polymerization initiator, and cooled to -78°C. 60g of p-tert-butoxycarbonyloxystyrene monomer (previously dissolved in 50mL of THF and cooled to -78°C) was added thereto, and living anionic polymerization was carried out for 1 hour, at which point the reaction solution turned red. 10g of methanol was added to the reaction solution to terminate the polymerization reaction. The resulting polymerization solution was poured into 1000mL of methanol to precipitate the polymer, and the precipitated solid was filtered and dried to obtain 60g of poly(p-tert-butoxycarbonyloxystyrene). The resulting polymer was 1 H-NMR, 13 Measurement by C-NMR and GPC gave the following analytical results. [ka]

[0298] (2) Synthesis of poly(p-hydroxystyrene) In a 2 L flask, 50 g of the poly(p-tert-butoxycarbonyloxystyrene) was dissolved in 1500 mL of acetone, and a small amount of hydrochloric acid was added at 60°C and stirred for 8 hours. After that, the reaction solution was cooled to room temperature and poured into 2000 mL of water to precipitate the polymer. The precipitated solid was filtered and dried to obtain 30 g of poly(p-hydroxystyrene). 1 H-NMR, 13 Measurement by C-NMR and GPC gave the following analytical results. [ka]

[0299] (3) Synthesis of polymer P-1 A 100 mL flask was charged with 20 g of the poly(p-hydroxystyrene) and 46.7 g of THF as a solvent. Then, under a nitrogen atmosphere, 0.5 g of methanesulfonic acid was added at approximately 25°C, followed by dropwise addition of 13.5 g of acetal modifier AC-1, and the reaction was allowed to proceed at room temperature for 4.5 hours. After completion of the reaction, 1.0 g of triethylamine was added, and the resulting reaction solution was added dropwise to 500 g of hexane, and the precipitated polymer was filtered off. The filtered polymer was washed twice with 120 g of hexane. The resulting polymer was dissolved in a mixed solvent of 60 g of ethyl acetate and 20 g of water, and the resulting solution was transferred to a separatory funnel, to which 0.7 g of acetic acid was added, followed by separation. The lower layer was distilled off, and 20 g of water and 0.9 g of pyridine were added to the resulting organic layer, followed by separation. The lower layer was distilled off, and 20 g of water was added to the resulting organic layer, followed by washing and separation (a total of five times). The organic layer after separation was concentrated and then dissolved in 40 g of PGME. The resulting solution was added dropwise to 600 g of water, and the resulting precipitate was filtered, washed with water, and dried to obtain 23.3 g of the target polymer P-1, which was a white polymer. 1 H-NMR, 13 Measurement by C-NMR and GPC gave the following analytical results. [ka]

[0300] [Synthesis Examples 2 to 20] Synthesis of Polymers P-2 to P-20 Polymers P-2 to P-20 shown below were synthesized by the same method as in Synthesis Example 1 or by known methods, except that the raw polymer and / or acetal modifying agent was changed. [ka]

[0301] [ka]

[0302] [ka]

[0303] [ka]

[0304] [Comparative Synthesis Examples 1 to 12] Synthesis of Polymers CP-1 to CP-12 Polymers CP-1 to CP-12 shown below were synthesized by combining the respective monomers and using a known radical polymerization method. [ka]

[0305] [ka]

[0306] [ka]

[0307] [3] Preparation of chemically amplified positive resist composition [Examples 1-1 to 1-50, Comparative Examples 1-1 to 1-36] Chemically amplified positive resist compositions were prepared by dissolving each component in an organic solvent according to the formulations shown in Tables 1 to 3 below, and filtering the resulting solution through a 5 nm nylon filter and a 1 nm UPE filter. The organic solvent was a mixed solvent of 940 parts by mass of PGMEA, 1870 parts by mass of EL, and 1870 parts by mass of PGME.

[0308] [Table 1]

[0309] [Table 2]

[0310] [Table 3]

[0311] In Tables 1 to 3, the structures of the photoacid generators PAG-1 to PAG-8, the quenchers Q-1 to Q-4, and the fluorine atom-containing polymers FP-1 to FP-5 are as follows: [ka]

[0312] [ka]

[0313] [ka]

[0314] [ka]

[0315] [3] EB lithography evaluation [Examples 2-1 to 2-50, Comparative Examples 2-1 to 2-36] Each chemically amplified positive resist composition (R-1 to R-50, CR-1 to CR-36) was spin-coated using an ACT-M (Tokyo Electron Limited) onto a reflective mask blank for EUV exposure. The mask blank consisted of a 6-inch low-thermal expansion glass substrate with a 284 nm thick Mo / Si 40-layer reflective multilayer film, a 3.5 nm thick Ru protective film, a 70 nm thick TaN absorber film, and a 6 nm thick CrN hard mask. The mask blank was then pre-baked on a hot plate at 110 °C for 600 seconds to produce an 80 nm thick resist film. The thickness of the resulting resist film was measured using an optical measuring instrument, Nanospec (Nanometrics). Measurements were performed at 81 locations on the blank substrate, excluding the outer edge, extending 10 mm inward from the outer periphery, and the average thickness and thickness range were calculated.

[0316] Next, the resist film was exposed using an electron beam exposure device (EBM-5000plus manufactured by NuFlare Technology Inc., acceleration voltage 50 kV), subjected to PEB at 110°C for 600 seconds, and developed with a 2.38% by mass TMAH aqueous solution to obtain a positive pattern.

[0317] The obtained resist patterns were evaluated as follows: The prepared patterned mask blanks were observed with a top-down SEM (scanning electron microscope), and the exposure dose required to resolve 200 nm 1:1 line and space (LS) at 1:1 was determined as the optimal exposure dose (μC / cm 2 ) was used. The limiting resolving power (the minimum line width at which lines and spaces (line:space = 1:1) can be resolved separately) at the above exposure dose was used as the resolving power (limiting IS resolution). The minimum dimension at the exposure dose at which a 200 nm isolated space can be resolved at a ratio of 9:1 was used as the resolution (limiting IS resolution), and the LER of 200 nm LS was measured using an SEM. The pattern shape was visually judged to be rectangular or not. The results are shown in Tables 4 to 6.

[0318] [Table 4]

[0319] [Table 5]

[0320] [Table 6]

[0321] The chemically amplified positive resist compositions (R-1 to R-50) of the present invention all exhibited good L / S resolution, isolated space (IS) resolution, LER, and pattern rectangularity compared to the comparative resist compositions (CR-1 to CR-36).

[0322] [4] Dry etching resistance evaluation [Examples 3-1 to 3-20, Comparative Examples 3-1 to 3-12] 2 g of each polymer (P-1 to P-20, CP-1 to CP-12) shown in Tables 1 and 2 was dissolved in 10 g of cyclohexanone and filtered through a 0.2 μm filter. The polymer solution was spin-coated onto a 152 mm square mask blank whose outermost surface was a Cr film to form a film with a thickness of 300 nm, which was then evaluated under the following conditions. Chlorine gas etching test: The difference in film thickness of the polymer film before and after etching was determined using a mask dry etching device Gen-4 manufactured by Plasma Thermo. The etching conditions are as follows: Chamber pressure 6.0mTorr RF power 700V Cl2 gas flow rate 185sccm O2 flow rate 55sccm He flow rate 9sccm Time 75sec In this evaluation, a film with a small difference in film thickness, that is, a film with a small reduction in film thickness, indicates that the film has etching resistance. The results of dry etching resistance are shown in Tables 7 and 8.

[0323] [Table 7]

[0324] [Table 8]

[0325] From the results shown in Tables 7 and 8, it was confirmed that the polymer of the present invention has excellent dry etching resistance in Cl2 / O2-based gases.

[0326] The chemically amplified positive resist composition and method for forming a resist pattern of the present invention are useful in the production of semiconductor devices, particularly in photolithography in the processing of transmission and reflection photomask blanks.

Claims

1. (A) a base polymer which contains a repeating unit derived from hydroxystyrene or hydroxynaphthalene, and a repeating unit derived from hydroxystyrene in which the hydroxy group is protected with an acid labile group, or a repeating unit derived from hydroxynaphthalene in which the hydroxy group is protected with an acid labile group, and which exhibits increased solubility in an alkaline aqueous solution due to the action of an acid, and which has a dispersity of 1.0 to 1.19; (B) a photoacid generator represented by the following formula (B), and (C) Organic solvent A chemically amplified positive resist composition comprising: 【Chemistry 1】 (In the formula, m1 is 0 or 1. m2 is 0, 1, 2, 3, or 4. m3 is 0, 1, 2, 3, 4, 5, or 6. However, when m1 is 0, 0≦m2+m3≦4, and when m1 is 1, 0≦m3+m4≦6. m4 is 0 or 1. When m4 is 0, m5 is 0, 1, 2, 3, or 4, and when m4 is 1, m6 is 0 or 1. R 11 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom other than a fluorine atom, a hydroxy group, a nitro group, a cyano group, or a heteroatom. 11 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 12 is a halogen atom, a hydroxy group, a nitro group, a cyano group, or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 12 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R F is a fluorine atom, a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, a fluorinated saturated hydrocarbyloxy group having 1 to 6 carbon atoms, or a fluorinated saturated hydrocarbylthio group having 1 to 6 carbon atoms. L A and L B are each independently a single bond, an ether bond, an ester bond, a sulfonate ester bond, a sulfonate amide bond, a carbonate bond or a carbamate bond. X L is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom. Z + is an onium cation.

2. 2. The chemically amplified positive resist composition according to claim 1, wherein the weight average molecular weight of the base polymer is in the range of 1,000 to 50,000.

3. 2. The chemically amplified positive resist composition according to claim 1, wherein the repeating unit derived from hydroxystyrene or hydroxynaphthalene is represented by the following formula (A1): 【Chemistry 2】 (In the formula, a1 is 0 or 1. a2 is 1, 2, or 3. a3 is 0, 1, 2, 3, or 4. However, when a1 is 0, 1≦a2+a3≦4, and when a1 is 1, 1≦a2+a3≦6. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 1 represents a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom.

4. 2. The chemically amplified positive resist composition according to claim 1, wherein the repeating unit derived from the hydroxystyrene in which the hydroxy group is protected with an acid labile group or the hydroxynaphthalene in which the hydroxy group is protected with an acid labile group is represented by the following formula (A2): 【Transformation 3】 (In the formula, b1 is 0 or 1. b2 is 1, 2, or 3. b3 is 0, 1, 2, 3, or 4. However, when b1 is 0, 1≦b2+b3≦4, and when b1 is 1, 1≦b2+b3≦6. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 2 represents a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. R AL is an acid labile group when b2 is 1, and is a hydrogen atom or an acid labile group when b2 is 2 or 3, provided that at least one is an acid labile group. The acid labile group is represented by any one of the following formulae (AL-1) to (AL-3). 【Chemistry 4】 (In the formula, R L1 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. R L2 , R L3 and R L4 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. L2 , R L3 and R L4 Any two or three of may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R L5 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. L2 , R L3 and R L4 and R L5 may be bonded to each other to form a ring together with the carbon atom and oxygen atom to which they are attached. R L6 , R L7 and R L8 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. L6 , R L7 and R L8 Any two of may be bonded to each other to form a ring together with the carbon atoms to which they are attached. The dashed lines represent bonds to the oxygen atoms in the formula.)

5. 2. The chemically amplified positive resist composition according to claim 1, wherein the base polymer further comprises at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (A3), a repeating unit represented by the following formula (A4), and a repeating unit represented by the following formula (A5): 【Transformation 5】 (In the formula, c1 is 0 or 1. c2 is 0, 1, 2, 3, 4, or 5. d is 0, 1, 2, 3, 4, 5, or 6. e is 0, 1, 2, 3, or 4. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 3 represents 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, or a cyano group, and when c1 is 1, it may also be a hydroxy group. R 4 and R 5 are each independently a hydroxy group, a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom.

6. 2. The chemically amplified positive resist composition according to claim 1, wherein the photoacid generator is represented by the following formula (B1): 【Transformation 6】 (In the formula, m1 to m5, R 11 , R 12 , R F , L A and Z + is the same as above.)

7. Z + 2. The chemically amplified positive resist composition according to claim 1, wherein is a sulfonium cation represented by the following formula (cation-1) or an iodonium cation represented by the following formula (cation-2): 【Transformation 7】 (In the formula, R 101 ~R 105 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. 101 and R 102 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.)

8. 2. The chemically amplified positive resist composition according to claim 1, further comprising (D) a quencher.

9. 2. The chemically amplified positive resist composition according to claim 1, further comprising a fluorine atom-containing polymer containing at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (E1), a repeating unit represented by the following formula (E2), a repeating unit represented by the following formula (E3), and a repeating unit represented by the following formula (E4): 【Transformation 8】 (In the formula, R B are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 301 , R 302 , R 304 and R 305 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 303 , R 306 , R 307 and R 308 are each independently a hydrogen atom, a hydrocarbyl group having 1 to 15 carbon atoms, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid labile group; R 203 , R 206 , R 207 and R 208 When is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bond. n is 1, 2 or 3. Z 1 is an (n+1)-valent hydrocarbon group having 1 to 20 carbon atoms or an (n+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms.

10. 2. The chemically amplified positive resist composition according to claim 1, wherein the fluorine atom-containing polymer further comprises at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (E5) and a repeating unit represented by the following formula (E6): 【Chemistry 9】 (In the formula, R C are each independently a hydrogen atom or a methyl group. R 309 is a hydrogen atom or a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a heteroatom-containing group interposed between its carbon-carbon bonds. R 310 is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a heteroatom-containing group interposed between its carbon-carbon bonds. R 311 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 —CH 2 A portion of the - may be substituted with an ester bond or an ether bond. x is 1, 2, or 3. y is an integer satisfying 0≦y≦5+2z−x. z is 0 or 1. Z 2 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. Z 3 is a single bond, -O-, *-C(=O)-O-Z 31 -Z 32 - or *-C(=O)-NH-Z 31 -Z 32 - is. Z 31 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. 32 is a single bond, an ester bond, an ether bond or a sulfonamide bond. * indicates a bond to a carbon atom in the main chain.)

11. 11. A method for forming a resist pattern, comprising: a step of forming a resist film on a substrate using the chemically amplified positive resist composition according to any one of claims 1 to 10; a step of irradiating the resist film with a pattern using high-energy rays; and a step of developing the resist film irradiated with the pattern using an alkaline developer.

12. 12. The method for forming a resist pattern according to claim 11, wherein the high-energy radiation is KrF excimer laser light, ArF excimer laser light, extreme ultraviolet light, or an electron beam.

13. 12. The method for forming a resist pattern according to claim 11, wherein the outermost surface of the substrate is made of a material containing at least one element selected from the group consisting of chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten, and tin.

14. 12. The method for forming a resist pattern according to claim 11, wherein the substrate is a transmission or reflection mask blank.

15. A transmission or reflection mask blank coated with the chemically amplified positive resist composition according to any one of claims 1 to 10.

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