Onium salt, chemically amplified positive resist composition, and resist pattern forming process

Abstract

To provide an onium salt capable of generating an acid with low diffusion, a chemically amplified positive resist composition containing the same, and a process for forming a resist pattern using the resist composition.SOLUTION: An onium salt represented by the following formula (A) is disclosed.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] In recent years, the high integration of integrated circuits has led to a demand for finer pattern formation, and chemically amplified resist compositions using acid as a catalyst are used exclusively for processing patterns of 0.2 μm or less. In this case, high-energy rays such as ultraviolet rays, far ultraviolet rays, and electron beams (EB) are used as exposure sources, and EB lithography, which is particularly used as an ultrafine processing technology, is also indispensable as a processing method for photomask blanks when producing photomasks for semiconductor manufacturing. Resist compositions used in such photolithography include positive types that form patterns by dissolving exposed areas, and negative types that form patterns by leaving exposed areas, and the one that is easier to use is selected depending on the form of the resist pattern required.

[0003] Generally, EB writing does not use a mask. In the case of a positive type, the areas other than the area where the resist film is to be left are sequentially irradiated with fine-area EB. In the case of a negative type, the areas where the resist film is to be left are sequentially irradiated. This is a process of sweeping over the entire finely divided area of ​​the processing surface, so it takes time compared to one-time exposure using a photomask, and in order to avoid a drop in throughput, the resist film needs to be highly sensitive. In addition, since the writing time is long, differences are likely to occur between the areas written in the early stages and the areas written in the later stages, so the stability of the exposed areas over time in vacuum is an important performance requirement. Furthermore, in the processing of photomask blanks, which is a particularly important application, some photomask substrates have surface materials that easily affect the pattern shape of the chemically amplified resist film, such as chromium oxide and other chromium compound films formed on the photomask substrate. In order to maintain high resolution and the shape after etching, it is also important to maintain the rectangular pattern profile of the resist film regardless of the type of substrate.

[0004] The above-mentioned sensitivity and pattern profile of the resist film have been improved in various ways by selecting and combining materials used in the resist composition, process conditions, etc. One of these improvements is the problem of acid diffusion, which has a significant effect on the resolution of chemically amplified resist films. In photomask processing, it is required that the shape of the obtained resist pattern does not change depending on the time until post-exposure bake (PEB), and the main cause of time-dependent changes is the diffusion of acid generated by exposure. This problem of acid diffusion has been extensively studied not only in photomask processing but also in general resist compositions, as it has a significant effect on sensitivity and resolution.

[0005] Patent Documents 1 and 2 describe examples in which acid diffusion is suppressed and roughness is reduced by increasing the bulk of the acid generated from an acid generator. However, such acid generators are still insufficient in suppressing acid diffusion, and therefore, there has been a demand for the development of an acid generator with smaller diffusion.

[0006] Patent Document 3 also describes an example of controlling acid diffusion by binding sulfonic acid generated by exposure to a resin used in a resist composition. This method of suppressing acid diffusion by binding a repeating unit that generates acid by exposure to a base polymer is effective for obtaining a pattern with small line edge roughness (LER). However, depending on the structure and introduction rate of such a repeating unit, there have been cases where a problem has arisen in the solubility of the base polymer bound to the repeating unit that generates acid by exposure in an organic solvent.

[0007] Meanwhile, polymers having a large amount of aromatic skeletons with acidic side chains, such as polyhydroxystyrene, have been usefully used as resist compositions for KrF lithography, but have not been used as materials for resist compositions for ArF lithography because they exhibit high absorption for light with a wavelength of about 200 nm. However, they are important materials for resist compositions for EB lithography, which is a powerful technique for forming patterns smaller than the processing limit of ArF lithography, and for resist compositions for extreme ultraviolet (EUV) lithography, because they provide high etching resistance.

[0008] As the base polymer of a positive resist composition for EB lithography or EUV lithography, a material is mainly used that uses an acid generated from a photoacid generator by irradiation with high energy rays as a catalyst to deprotect an acid labile group (acid decomposable protecting group) that masks an acidic functional group of a phenol side chain of the base polymer, thereby making the base polymer soluble in an alkaline developer. In addition, tertiary alkyl groups, tert-butoxycarbonyl groups, acetal groups, etc. have mainly been used as the acid labile group. Here, the use of a protecting group such as an acetal group that requires a relatively small activation energy for deprotection has the advantage of providing a highly sensitive resist film, but if the diffusion of the generated acid is not sufficiently suppressed, a deprotection reaction will occur even in the unexposed parts of the resist film, leading to problems such as deterioration of LER and deterioration of the dimensional uniformity (CDU) of the pattern line width.

[0009] Furthermore, patent documents 4 and 5 propose photoacid generators that generate non-fluorinated aromatic sulfonic acids having multiple bulky alkyl substituents. Although the molecular weight of the generated acid is increased by the multiple alkyl substituents, the acid diffusion is reduced, in the case of the purpose of forming fine patterns, the inhibition of acid diffusion is still insufficient, and there is still room for further improvement.

[0010] Furthermore, in the formation of fine patterns by EB lithography, the shape of the resist pattern becomes inversely tapered due to the influence of back scattering caused by the reflection of EB on the substrate. The inversely tapered shape induces the resist pattern to collapse during development. In order to meet the demand for further miniaturization, it is desired to develop a photoacid generator that can solve the above problem and suppress acid diffusion while correcting the pattern shape. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2009-053518 A [Patent Document 2] JP 2010-100604 A [Patent Document 3] JP 2011-22564 A [Patent Document 4] Patent No. 6248882 [Patent Document 5] JP 2019-202974 A Summary of the Invention [Problem to be solved by the invention]

[0012] In recent years, there has been a demand for resist compositions that are excellent not only in line and space (LS), isoline (IL), and isospace (IS) but also in hole pattern shape. In the acid generator described in Patent Document 4, which generates a bulky acid and suppresses acid diffusion, acid diffusion is suppressed to a certain extent, but when a fine pattern is formed, the pattern shape becomes an inverse tapered shape, and there is a problem that the pattern collapses during development after alkaline development.

[0013] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide an onium salt capable of generating an acid that diffuses little, a chemically amplified positive resist composition containing the same, and a method of forming a resist pattern using the resist composition. [Means for solving the problem]

[0014] As a result of intensive research into achieving the above-mentioned object, the inventors have found that when an onium salt having an aromatic sulfonate anion which has a group containing an alkyl chain or a fluoroalkyl chain, and an aromatic ring substituted with an iodine atom, and a fluorine-containing substituent, is introduced into a resist composition as an acid generator, the onium salt is unevenly distributed in the upper layer of the resist film due to the effect of the alkyl chain or fluoroalkyl chain, and the pattern shape is corrected to give a pattern with good resolution and small CDU and LER, and further, due to moderate dissolution inhibition properties, a pattern with good rectangularity can be obtained, which has led to the completion of the present invention.

[0015] That is, the present invention provides the following onium salt, chemically amplified positive resist composition, and method of forming a resist pattern. 1. An onium salt represented by the following formula (A): [ka] (In the formula, n1 is 0 or 1. n2 is 1, 2 or 3. n3 is an integer from 0 to 4. n4 is an integer from 0 to 4. However, when n1 is 0, 1≦n2+n3+n4≦5, and when n1 is 1, 1≦n2+n3+n4≦7. n5 is 0, 1, or 2. n6 is an integer from 0 to 4 when n5 is 0, an integer from 0 to 6 when n5 is 1, and an integer from 0 to 8 when n5 is 2. n7 is an integer from 0 to 4 when n5 is 0, an integer from 0 to 6 when n5 is 1, and an integer from 0 to 8 when n5 is 2. However, n6+n7 is an integer from 0 to 4 when n5 is 0, an integer from 0 to 6 when n5 is 1, and an integer from 0 to 8 when n5 is 2. R alk R is an alkyl group having 6 to 18 carbon atoms or a fluorinated alkyl group having 4 to 18 carbon atoms. alk When R is an alkyl group having 6 to 18 carbon atoms, the alkyl group has at least one linear structure having 6 or more carbon atoms. alkis a fluorinated alkyl group having 4 to 18 carbon atoms, the fluorinated alkyl group has at least two groups selected from -CF2- and -CF3. In addition, the alkyl group and the fluorinated alkyl group may have a part of their -CH2- substituted with an ether bond or a carbonyl group, and may contain a ring structure selected from a cyclopentane ring, a cyclohexane ring, an adamantane ring, a norbornyl ring, and a benzene ring at the end or between the carbon-carbon bonds. R 1 represents a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom other than an iodine atom, or a heteroatom. R 2 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, and when n7 is 2 or more, a plurality of R 2 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R F1 is a fluorine atom, a fluorinated alkyl group having 1 to 6 carbon atoms, a fluorinated alkoxy group having 1 to 6 carbon atoms, or a fluorinated thioalkoxy group having 1 to 6 carbon atoms. When n6 is 2 or more, each R F1 may be the same as or different from each other. L A , L B and L C are each independently a single bond, an ether bond, an ester bond, a sulfonate ester 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. An onium salt of formula 1, which is represented by the following formula (A1): [ka] (In the formula, n1~n4, n6, n7, R alk , R 1 , R 2 , R F1 , L A , L B , L C, X L and Z + is the same as above.) 3. An onium salt of 2 represented by the following formula (A2): [ka] (In the formula, n1~n4, n6, n7, R alk , R 1 , R 2 , R F1 , L A , L C , X L and Z + is the same as above.) 4.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 ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. ct1 and R ct2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. 5. A photoacid generator comprising an onium salt according to any one of 1 to 4. 6.5 A chemically amplified positive resist composition containing a photoacid generator. 7. A chemically amplified positive resist composition according to claim 6, further comprising a base polymer which contains a polymer which is decomposed by the action of an acid and has increased solubility in an alkaline developer. 8. The chemically amplified positive resist composition according to 7, wherein the polymer contains a repeating unit represented by the following formula (B1): [ka] (In the formula, a1 is 0 or 1. a2 is an integer of 0 to 2. a3 is an integer that satisfies 0≦a3≦5+2(a2)−a4. a4 is an integer of 1 to 3. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 11 represents a halogen atom, a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom. A 1 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- in the saturated hydrocarbylene group may be substituted with -O-. 9. The chemically amplified positive resist composition according to 7 or 8, wherein the polymer contains a repeating unit represented by the following formula (B2-1): [ka] (In the formula, b1 is 0 or 1. b2 is an integer of 0 to 2. b3 is an integer satisfying 0≦b3≦5+2(b2)−b4. b4 is an integer of 1 to 3. b5 is 0 or 1. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 12 represents a halogen atom, a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom. A 2 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a portion of -CH2- in the saturated hydrocarbylene group may be substituted with -O-. When b4 is 1, X is an acid labile group. When b4 is 2 or 3, X is each independently a hydrogen atom or an acid labile group, provided that at least one X is an acid labile group. 10. The chemically amplified positive resist composition according to any one of 7 to 9, wherein the polymer contains a repeating unit represented by the following formula (B2-2): [ka] (In the formula, c1 is an integer of 0 to 2. c2 is an integer of 0 to 2. c3 is an integer of 0 to 5. c4 is an integer of 0 to 2. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 13 and R 14 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom, R 13 and R 14 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 15 each independently represents a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, or a fluorinated alkoxy group having 1 to 5 carbon atoms. R 16 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. A 3 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OA 31 -It is. 31 is an aliphatic hydrocarbylene group having 1 to 20 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond or a lactone ring, or a phenylene group or naphthylene group. * represents a bond to a carbon atom of the main chain.) 11. The chemically amplified positive resist composition of any of 7 to 10, wherein the polymer contains at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (B3), a repeating unit represented by the following formula (B4), and a repeating unit represented by the following formula (B5): [ka] (In the formula, d is an integer of 0 to 6. e is an integer of 0 to 4. f1 is 0 or 1. f2 is an integer of 0 to 2. f3 is an integer of 0 to 5.) R Ais a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 17 and R 18 each independently represents 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. R 19 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 f2 is 1 or 2, it may be a hydroxy group. A 4 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- in the saturated hydrocarbylene group may be substituted with -O-. 12. The chemically amplified positive resist composition according to any one of 7 to 11, wherein the polymer contains at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (B6), a repeating unit represented by the following formula (B7), a repeating unit represented by the following formula (B8), and a repeating unit represented by the following formula (B9). [ka] (In the formula, R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1 is a single bond or a phenylene group. X 2 teeth,* 1 -C(=O)-OX 21 -, * 1 -C(=O)-NH-X 21 -or* 1 -OX 21 -It is. X 21represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group.* 1 X 1 Represents a bond with . X 3 each independently represents a single bond, a phenylene group, a naphthylene group, or * 2 -C(=O)-OX 31 -It is. X 31 is an aliphatic hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the aliphatic hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring. 2 represents a bond to a carbon atom in the main chain. X 4 each independently represents a single bond, * 3 -X 41 -C(=O)-O-, * 3 -C(=O)-NH-X 41 -or* 3 -OX 41 -It is. X 41 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 3 X 3 Represents a bond with . X 5 each independently represents a single bond, * 4 -X 51 -C(=O)-O-, * 4 -C(=O)-NH-X 51 -or* 4 -OX 51 -It is. X 51 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 4 X 4 Represents a bond with . X 6 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, * 2 -C(=O)-OX 61 -, * 2-C(=O)-N(H)-X 61 -or* 2 -OX 61 -It is. X 61 is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. 2 represents a bond to a carbon atom in the main chain. R 21 and R 22 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 21 and R 22 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. L 1 is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate ester bond, a carbonate bond or a carbamate bond. Rf 1 and Rf 2 are each independently a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 3 and Rf 4 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 5 and Rf 6 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 5 and Rf 6 cannot simultaneously become a hydrogen atom. M - is a non-nucleophilic counterion. A + is an onium cation. g1 and g2 each independently represent an integer of 0 to 3. 13. Any one of the chemically amplified positive resist compositions according to 6 to 12, further comprising an organic solvent. 14. The chemically amplified positive resist composition according to any one of 6 to 13, further comprising a fluorine atom-containing polymer which contains at least one selected from the group consisting of a repeating unit represented by the following formula (D1), a repeating unit represented by the following formula (D2), a repeating unit represented by the following formula (D3), and a repeating unit represented by the following formula (D4), and which may further contain at least one selected from the group consisting of a repeating unit represented by the following formula (D5) and a repeating unit represented by the following formula (D6). [ka] (In the formula, j1 is an integer of 1 to 3. j2 is an integer that satisfies 0≦j2≦5+2(j3)−j1. j3 is 0 or 1. k is an integer of 1 to 3. R B each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R C are each independently a hydrogen atom or a methyl group. R 101 , R 102 , R 104 and R 105 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 103 , R 106 , R 107 and R 108 each independently represents 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 103 , R 106 , R 107 and R 108 When is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bonds. R 109 represents a hydrogen atom or a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a group containing a heteroatom interposed between the carbon-carbon bonds. R 110is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a group containing a heteroatom interposed between the carbon-carbon bonds. R 111 represents a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, and a portion of the -CH2- in the saturated hydrocarbyl group may be substituted with an ester bond or an ether bond. Z 1 is a (k+1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (k+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. Z 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. Z 3 is a single bond, -O-, *-C(=O)-OZ 31 -Z 32 - or -C(=O)-NH-Z 31 -Z 32 -It is. 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. * represents a bond to a carbon atom in the main chain.) 15. The chemically amplified positive resist composition according to any one of 6 to 14, further comprising a quencher. 16. A chemically amplified positive resist composition according to any one of 6 to 15, further comprising a photoacid generator other than the photoacid generator according to 5. 17. 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 claims 6 to 16, exposing the resist film to high-energy rays, and developing the exposed resist film using an alkaline developer to obtain a resist pattern. 18. The method for forming a resist pattern according to claim 17, wherein the high energy radiation is EUV or EB. 19. The method for forming a resist pattern according to claim 17 or 18, wherein the outermost surface of the substrate is made of a material containing chromium. 20. The method for forming a resist pattern according to any one of 17 to 19, wherein the substrate is a photomask blank. Effect of the Invention

[0016] The chemically amplified positive resist composition containing the onium salt of the present invention as a photoacid generator has extremely high resolution and can provide a pattern with small LER in microfabrication techniques, particularly EB lithography and EUV lithography. In addition, since it has a suitable dissolution inhibition property and can provide a pattern with good rectangularity, it is suitable as a chemically amplified positive resist material. [Brief description of the drawings]

[0017] [Figure 1] 1 is a nuclear magnetic resonance spectrum (1H-NMR / DMSO-d6) of the onium salt PAG-1 synthesized in Example 1-1. [Diagram 2] 1 is a nuclear magnetic resonance spectrum (1H-NMR / DMSO-d6) of the onium salt PAG-2 synthesized in Example 1-2. [Diagram 3] 1 is a nuclear magnetic resonance spectrum (1H-NMR / DMSO-d6) of the onium salt PAG-3 synthesized in Example 1-3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention will be described in detail below. In the following description, some structures represented by chemical formulas may have asymmetric carbons and may have enantiomers or diastereomers, but in such cases, one formula will be used to represent these isomers. These isomers may be used alone or as a mixture of two or more.

[0019] [Onium salts] The onium salt of the present invention is represented by the following formula (A). [ka]

[0020] In formula (A), n1 is 0 or 1. When n1 is 0, it represents a benzene ring, and when n1 is 1, it represents a naphthalene ring, but from the viewpoint of solvent solubility, it is preferable that n1 is a benzene ring of 0. n2 is 1, 2, or 3, but is preferably 1 or 2. n3 is an integer of 0 to 4, but is preferably 1, 2, or 3 from the viewpoint of solvent solubility and lithography performance. n4 is an integer of 0 to 4, but is preferably 0 or 1. However, when n1 is 0, 1≦n2+n3+n4≦5, and when n1 is 1, 1≦n2+n3+n4≦7.

[0021] In formula (A), n5 is 0, 1 or 2. When n5 is 0, it represents a benzene ring, when n5 is 1, it represents a naphthalene ring, and when n5 is 2, it represents an anthracene ring. From the viewpoint of solvent solubility and lithography performance, it is preferable that n5 is a benzene ring of 0 or a naphthalene ring of 1. When n5 is 0, n6 is an integer of 0 to 4, when n5 is 1, it is an integer of 0 to 6, and when n5 is 2, it is an integer of 0 to 8. When n5 is 0, n7 is an integer of 0 to 4, when n5 is 1, it is an integer of 0 to 6, and when n5 is 2, it is an integer of 0 to 8. However, n6+n7 is 0 to 4 when n5 is 0, 0 to 6 when n5 is 1, and 0 to 8 when n5 is 2.

[0022] In formula (A), R alk is an alkyl group having 6 to 18 carbon atoms or a fluorinated alkyl group having 4 to 18 carbon atoms.

[0023] R alk When R is an alkyl group having 6 to 18 carbon atoms, the alkyl group has at least one linear structure having 6 or more carbon atoms. alkSpecific examples of the alkyl group having 6 to 18 carbon atoms represented by the formula include 1-hexyl, 1-heptyl, 1-octyl, 1-nonyl, 1-decyl, 1-undecyl, 1-dodecyl, 1-tridecyl, 1-tetradecyl, 1-hexadecyl, 1-octadecyl, octan-2-yl, decan-2-yl, decan-4-yl, octadecane-8-yl, 7,7-dimethyloctyl, 7,7-diethylnonyl, and 4-butyldodecyl. In addition, the alkyl group may have a portion of its -CH2- substituted with an ether bond or a carbonyl group, and may have a ring structure, such as a cyclopentane ring, a cyclohexane ring, an adamantane ring, a norbornane ring, or a benzene ring, at its terminal or between carbon-carbon bonds as a partial structure. R alk is preferably a linear alkyl group or a linear glyme chain. When n2 is 2 or 3, each R alk may be the same or different.

[0024] R alk When R is a fluorinated alkyl group having 4 to 18 carbon atoms, the fluorinated alkyl group has at least two groups selected from -CF2- and -CF3. alk Specific examples of the fluorinated alkyl group having 4 to 18 carbon atoms represented by the formula (I) include groups in which some or all of the hydrogen atoms have been substituted with fluorine atoms, such as a 1-butyl group, a 1-pentyl group, a 1-hexyl group, a 1-heptyl group, a 1-octyl group, a 1-nonyl group, a 1-decyl group, a 1-undecyl group, a 1-dodecyl group, a 1-tridecyl group, a 1-tetradecyl group, a 1-hexadecyl group, a 1-octadecyl group, an octan-2-yl group, a decan-2-yl group, a decan-4-yl group, an octadecan-8-yl group, a 7,7-dimethyloctyl group, a 7,7-diethylnonyl group, and a 4-butyldodecyl group. In addition, the fluorinated alkyl group may have a portion of its -CH2- substituted with an ether bond or a carbonyl group, and may have a ring structure, such as a cyclopentane ring, a cyclohexane ring, an adamantane ring, a norbornyl ring or a benzene ring, at its terminal or between its carbon-carbon bonds.

[0025] R alkThe following are preferred as the alkyl group, but are not limited thereto. In the following formulae, the dashed lines represent bonds. [ka]

[0026] In formula (A), R 1 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom other than an iodine atom, or a heteroatom. Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom, with a fluorine atom being preferred.

[0027] R 1 The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and specific examples thereof include branched alkyl groups having 3 to 20 carbon atoms, such as an isopropyl group, a sec-butyl group, a tert-butyl group, a tert-pentyl group, and a 2-ethylhexyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, an oxanorbornyl group, a tricyclo[5.2.1.0 2,6 ] cycloaliphatic hydrocarbyl groups having 3 to 20 carbon atoms, such as decyl group and adamantyl group; aryl groups having 6 to 20 carbon atoms, such as phenyl group, naphthyl group and anthracenyl group; and groups obtained by combining these groups, but are not limited thereto. In addition, some or all of the hydrogen atoms of the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms, nitrogen atoms and halogen atoms, and some of -CH2- of the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms and nitrogen atoms, and as a result, the hydrocarbyl groups may contain hydroxyl groups, cyano groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, carbonyl groups, ether bonds, ester bonds, sulfonate ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic anhydrides (-C(=O)-OC(=O)-), haloalkyl groups and the like.

[0028] If n4 is 2 or more, two R1 may be bonded to each other to form a ring together with the carbon atom to which they are bonded. Examples of the ring formed in this case include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, and an adamantane ring. In addition, some or all of the hydrogen atoms in the ring 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- in the ring 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 ring may contain a hydroxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0029] In formula (A), R 2 is 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 1 When n7 is 2 or more, each R 2 may be the same as or different from each other.

[0030] Also, when n7 is 2 or more, multiple R 2 However, they may be bonded to each other to form a ring together with the carbon atom to which they are bonded. The ring is preferably a 5- to 8-membered ring.

[0031] In formula (A), R F1 R is a fluorine atom, a fluorinated alkyl group having 1 to 6 carbon atoms, a fluorinated alkoxy group having 1 to 6 carbon atoms, or a fluorinated thioalkoxy group having 1 to 6 carbon atoms. F1is preferably a fluorine atom, a trifluoromethyl group, a difluoromethyl group, a trifluoromethoxy group, a difluoromethoxy group, a trifluoromethylthio group, or a difluoromethylthio group, and more preferably a fluorine atom, a trifluoromethyl group, or a trifluoromethoxy group. By containing a fluorine atom, the acid strength of the generated acid is improved, so that the deprotection reaction proceeds smoothly. When n6 is 2 or more, each R F1 may be the same as or different from each other.

[0032] In formula (A), L A , L B and L C are each independently a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond or a carbamate bond. A and L B is preferably a single bond, an ether bond, an ester bond or a sulfonate ester bond, and more preferably a single bond, an ether bond or an ester bond. C is preferably a single bond, an ether bond or an ester bond, and more preferably a single bond or an ether bond.

[0033] In formula (A), 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, a cyclic saturated hydrocarbylene group, etc. Specific examples of the heteroatom include an oxygen atom, a nitrogen atom, a sulfur atom, etc.

[0034] X L Specific examples of the hydrocarbylene group having 1 to 40 carbon atoms and optionally containing a heteroatom, represented by the following formula, include, but are not limited to, those shown below. In the following formula, * represents L A and L B Represents a bond with . [ka]

[0035] [ka]

[0036] [ka]

[0037] [ka]

[0038] Of these, X L -0~X L -22 and X L -47~X L -58 is preferred.

[0039] The onium salt represented by formula (A) is preferably one represented by the following formula (A1). [ka] (In the formula, n1~n4, n6, n7, R alk , R 1 , R 2 , R F1 , L A , L B , L C , X L and Z + is the same as above.)

[0040] The onium salt represented by formula (A1) is preferably one represented by the following formula (A2). [ka] (In the formula, n1~n4, n6, n7, R alk , R 1 , R 2 , R F1 , L A , L C , X Land Z + is the same as above.)

[0041] Particularly preferred examples of the anion of the onium salt represented by formula (A) include, but are not limited to, those shown below: In the following formula, Me is a methyl group. [ka]

[0042] [ka]

[0043] [ka]

[0044] [ka]

[0045] [ka]

[0046] [ka]

[0047] [ka]

[0048] [ka]

[0049] [ka]

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[0137] [ka]

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[0141] [ka]

[0142] In formula (A), 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]

[0143] In formulas (cation-1) and (cation-2), R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom.

[0144] R ct1 ~R ct5 Examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0145] R ct1 ~R ct5 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 30 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group; cyclic saturated hydrocarbyl groups having 3 to 30 carbon atoms, such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cyclopropylmethyl group, a 4-methylcyclohexyl group, a cyclohexylmethyl group, a norbornyl group, and an adamantyl group; alkenyl groups having 2 to 30 carbon atoms, such as a vinyl group, an allyl group, a propenyl group, a butenyl group, and a hexenyl group; cyclic unsaturated hydrocarbyl groups having 3 to 30 carbon atoms, such as a cyclohexenyl group; aryl groups having 6 to 30 carbon atoms, such as a phenyl group, a naphthyl group, and a thienyl group; aralkyl groups having 7 to 30 carbon atoms, such as a benzyl group, a 1-phenylethyl group, and a 2-phenylethyl group; and groups obtained by combining these, with an aryl group being preferred. 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- 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.

[0146] Also, R ct1 and R ct2 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, examples of the ring structure include those represented by the following formulas: [ka] (In the formula, the dashed line represents R ct3 It represents a bond with .)

[0147] Examples of the sulfonium cation represented by formula (cation-1) include, but are not limited to, those shown below. [ka]

[0148] [ka]

[0149] [ka]

[0150] [ka]

[0151] [ka]

[0152] [ka]

[0153] [ka]

[0154] [ka]

[0155] [ka]

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[0166] [ka]

[0167] [ka]

[0168] [ka]

[0169] [ka]

[0170] [ka]

[0171] [ka]

[0172] [ka]

[0173] [ka]

[0174] The iodonium cation represented by formula (cation-2) is shown below. These include, but are not limited to: [ka]

[0175] [ka]

[0176] Specific examples of the onium salt of the present invention include any combination of the above-mentioned anions and cations.

[0177] The onium salt of the present invention can be synthesized by a known method. As an example, a method for producing an onium salt represented by the following formula (PAG-1-ex) will be described. [ka] (In the formula, n1~n7, R alk , R 1 , R 2 , R F1 , L A , X L and Z + is the same as above. X Hal R is a chlorine atom, a bromine atom, or an iodine atom. X is a group that forms a primary or secondary ester together with the adjacent -CO2-. + is the counter cation. X - is the counter anion.)

[0178] The first step is a step of obtaining intermediate In-1-ex by reacting a phenol compound (SM-1) that is commercially available or can be synthesized by a known synthesis method with a haloalkyl compound (SM-2). The reaction can be carried out by a known organic synthesis method. Specifically, the raw material SM-1 is dissolved in an aprotic polar solvent such as acetone, acetonitrile, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), etc., a base is further added, and the raw material SM-2 is dropped to carry out the reaction. Examples of the base to be used include hydroxides such as sodium hydroxide, potassium hydroxide, and tetramethylammonium hydroxide, and carbonates such as potassium carbonate and sodium hydrogen carbonate, and these bases may be used alone or in combination of two or more. It is preferable to carry out the reaction under heating as necessary. The reaction temperature is from room temperature to the boiling point of the solvent used, but it is preferable to carry out the reaction under heating conditions in order to smoothly proceed with the reaction. In addition, the reaction can be accelerated by adding an alkali metal iodide as a catalyst. Examples include sodium iodide and potassium iodide. The reaction time is usually about 4 to 12 hours, but it is desirable to follow the reaction by silica gel thin layer chromatography (TLC) to complete the reaction in terms of yield. Thereafter, the reaction is stopped using water, and the target product is extracted from the reaction mixture and subjected to a conventional aqueous work-up to obtain intermediate In-1-ex. If necessary, the obtained intermediate In-1-ex can be purified by conventional methods such as chromatography and recrystallization.

[0179] The second step is the reaction of -CO2-R in the intermediate In-1-ex xThis is a process in which the primary or secondary ester bond of In-2-ex is hydrolyzed with a base to obtain intermediate In-2-ex. The reaction can be carried out by a known organic synthesis method. Specifically, intermediate In-1-ex is suspended in an ether solvent such as water or tetrahydrofuran (THF), and a base is added to perform hydrolysis. The base used is preferably an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide. The reaction temperature is from room temperature to the boiling point of the solvent used, but it is preferable to carry out the reaction under heating conditions in order to smoothly proceed with the reaction. The reaction time is usually about 4 to 12 hours, although it is desirable to follow the reaction by TLC in terms of yield and complete the reaction. Thereafter, the reaction is stopped using dilute hydrochloric acid or the like, and the target product is extracted from the reaction mixture when the pH is made acidic, and the intermediate In-2-ex can be obtained by carrying out a normal aqueous work-up. The obtained intermediate In-2-ex can be purified according to a normal method such as chromatography or recrystallization, if necessary.

[0180] The third step is a step of obtaining intermediate In-3-ex by the reaction of intermediate In-2-ex with raw material SM-3. When directly forming an ester bond from the carboxy group of intermediate In-2-ex and the hydroxy group of raw material SM-3, various condensation agents can be used. Examples of the condensation agent to be used include N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride. From the viewpoint of ease of removal of the urea compound generated as a by-product after the reaction, it is preferable to use 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride. The reaction is carried out by dissolving intermediate In-2-ex and raw material SM-3 in a halogen-based solvent such as methylene chloride, and adding a condensation agent. The reaction rate can be improved by adding 4-dimethylaminopyridine (DMAP) as a catalyst. The reaction time is preferably about 12 to 24 hours, but it is desirable to complete the reaction by tracking the reaction with TLC in terms of yield. After the reaction is stopped, the by-product urea compound is removed by filtration or washing with water as necessary, and the reaction solution is subjected to a normal aqueous work-up to obtain intermediate In-3-ex. In addition, intermediate In-3-ex can be obtained by preparing an acid chloride from intermediate In-2-ex using oxalyl chloride or thionyl chloride, and then reacting it with raw material SM-3. In the reaction, it is preferable to use a base such as triethylamine, diisopropylethylamine, pyridine, or 2,6-lutidine. In addition, in order to accelerate the reaction, it is preferable to add 4-dimethylaminopyridine (DMAP) as a catalyst. If necessary, the obtained intermediate In-3-ex can be purified according to a normal method such as chromatography or recrystallization.

[0181] In the fourth step, the obtained intermediate In-3-ex is converted to Z + X - This is a process for obtaining the onium salt PAG-1-ex by salt exchange with an onium salt represented by the formula: -As the anion, chloride ion, bromide ion, iodide ion, or methyl sulfate anion is preferable because the exchange reaction easily proceeds quantitatively. It is preferable to confirm the progress of the reaction by TLC in terms of yield. The onium salt PAG-1-ex can be obtained by carrying out a normal aqueous work-up from the reaction mixture. If necessary, it can be purified by a normal method such as chromatography or recrystallization.

[0182] In the above scheme, the ion exchange in the fourth step can be easily carried out by a known method, for example, see JP-A-2007-145797.

[0183] The above-mentioned production method is merely one example, and the production method of the onium salt of the present invention is not limited thereto.

[0184] The onium salt represented by formula (A) is characterized by containing a group containing an alkyl chain or a fluoroalkyl chain on the aromatic ring of the anion. Since the alkyl chain or the fluoroalkyl chain acts as a hydrophobic group, it is considered that the onium salt is unevenly distributed in the surface layer of the resist film. In particular, in alkali development positive EB lithography, back scattering occurring between the EB and the substrate causes the pattern shape to become an inverse tapered shape, which causes the pattern to collapse after development, but by applying the onium salt of the present invention, the deprotection reaction of the base polymer proceeds effectively even in the upper layer part of the pattern, so that the pattern can be corrected to a rectangular pattern. In addition, the onium salt of the present invention preferably has an iodine atom in the anion, and the iodine atom on the aromatic ring improves the sensitivity in EB lithography and also has a moderate dissolution inhibition property. Due to these synergistic effects, it is considered that when a resist composition containing the onium salt of the present invention is used, a pattern with good resolution, high contrast, and small CDU and LER can be obtained, and further, due to the moderate dissolution inhibition property, a pattern with good rectangularity can be obtained. The onium salt of the present invention has sufficient fat solubility and is therefore easy to produce and handle.

[0185] The onium salt of the present invention can be suitably used as a photoacid generator.

[0186] [Chemically amplified positive resist composition] [(A) Photoacid generator] The chemically amplified positive resist composition of the present invention contains, as an essential component, a photoacid generator consisting of an onium salt represented by formula (A) as component (A).

[0187] In the chemically amplified positive resist composition of the present invention, the content of the photoacid generator (A) 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 base polymer (B) described below. If the content of the photoacid generator is within the above range, an amount of acid required for deprotection of the acid labile group is generated, and a good pattern shape is obtained. In addition, the storage stability is also good. The photoacid generator (A) may be used alone or in combination of two or more kinds.

[0188] [(B) Base polymer] The resist composition of the present invention contains, as the component (B), a base polymer which contains a polymer that decomposes under the action of an acid and has increased solubility in an alkaline developer.

[0189] The polymer is preferably a polymer containing a repeating unit represented by the following formula (B1) (hereinafter also referred to as repeating unit B1). [ka]

[0190] In formula (B1), a1 is 0 or 1. a2 is an integer of 0 to 2, and when a2 is 0, it represents a benzene skeleton, when a2 is 1, it represents a naphthalene skeleton, and when a2 is 2, it represents an anthracene skeleton. a3 is an integer that satisfies 0≦a3≦5+2(a2)-a4. a4 is an integer of 1 to 3. When a2 is 0, a3 is preferably an integer of 0 to 3 and a4 is preferably an integer of 1 to 3, and when a2 is 1 or 2, a3 is preferably an integer of 0 to 4 and a4 is preferably an integer of 1 to 3.

[0191] In formula (B1), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0192] In formula (B1), R 11 is a halogen atom, a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom. The saturated hydrocarbyl group, and the saturated hydrocarbyl carbonyloxy group and the saturated hydrocarbyloxy group may be linear, branched, or cyclic, and specific examples thereof 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 groups. 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 11 may be the same as or different from each other.

[0193] In formula (B1), A 1is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- of the saturated hydrocarbylene group may be replaced by -O-. The saturated hydrocarbylene group may be linear, branched, or cyclic, and specific examples thereof include alkanediyl groups having 1 to 10 carbon atoms, such as methylene, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, and structural isomers thereof; cyclic saturated hydrocarbylene groups having 3 to 10 carbon atoms, such as cyclopropanediyl, cyclobutanediyl, cyclopentanediyl, and cyclohexanediyl; and groups obtained by combining these. When the saturated hydrocarbylene group contains an ether bond, when a1 in formula (B1) is 1, it may be located at any position except between the carbon atom at the α-position and the carbon atom at the β-position relative to the ester oxygen atom. When a1 is 0, the atom bonded to the main chain is an etheric oxygen atom, and the second ether bond may be inserted at any position except between the carbon atom at the α-position and the carbon atom at the β-position with respect to the etheric oxygen atom. If the number of carbon atoms in the saturated hydrocarbylene group is 10 or less, sufficient solubility in an alkaline developer can be obtained, which is preferable.

[0194] a1 is 0 and A 1 is a single bond, i.e., the aromatic ring is directly attached to the polymer backbone (i.e., the linker (-C(=O)-OA 1 In the case where the repeating unit B1 does not have -), preferred examples of the repeating unit B1 include units derived from 3-hydroxystyrene, 4-hydroxystyrene, 5-hydroxy-2-vinylnaphthalene, 6-hydroxy-2-vinylnaphthalene, etc. Specific examples include, but are not limited to, those shown below. [ka]

[0195] [ka]

[0196] [ka]

[0197] a1 is 1 (i.e., -C(=O)-OA as a linker 1 In the case where R A is the same as above. [ka]

[0198] [ka]

[0199] [ka]

[0200] [ka]

[0201] The content of the repeating unit B1 is preferably 15 to 90 mol %, more preferably 15 to 80 mol %, of all repeating units constituting the polymer. However, when the repeating unit contains at least one of the repeating units represented by formula (B3) and the repeating unit represented by formula (B4), which give the polymer higher etching resistance as described below, and the unit has a phenolic hydroxyl group as a substituent, it is preferable that the ratio of the unit is also within the above range. The repeating unit B1 may be used alone or in combination of two or more types.

[0202] In order to provide the polymer as a positive resist composition with the property that the exposed area dissolves in an alkaline developer, it is preferable that the polymer contains a repeating unit having an acidic functional group protected by an acid labile group, i.e., a repeating unit that is protected by an acid labile group and becomes alkali-soluble by the action of acid (hereinafter, also referred to as repeating unit B2).

[0203] The most preferred repeating unit B2 is one represented by the following formula (B2-1) (hereinafter, also referred to as repeating unit B2-1). [ka]

[0204] In formula (B2-1), b1 is 0 or 1. b2 is an integer of 0 to 2, and when it is 0, it represents a benzene skeleton, when it is 1, it represents a naphthalene skeleton, and when it is 2, it represents an anthracene skeleton. b3 is an integer that satisfies 0≦b3≦5+2(b2)-b4. b4 is an integer of 1 to 3. b5 is 0 or 1. When b2 is 0, b3 is preferably an integer of 0 to 3 and b4 is an integer of 1 to 3, and when b2 is 1 or 2, b3 is preferably an integer of 0 to 4 and b4 is an integer of 1 to 3.

[0205] In formula (B2-1), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0206] In formula (B2-1), R 12is a halogen atom, a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom. The saturated hydrocarbyl group, and the saturated hydrocarbyl carbonyloxy group and the saturated hydrocarbyloxy group may be linear, branched, or cyclic, and specific examples thereof 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 groups. 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 12 may be the same as or different from each other.

[0207] In formula (B2-1), A 2is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- of the saturated hydrocarbylene group may be replaced by -O-. The saturated hydrocarbylene group may be linear, branched, or cyclic, and specific examples thereof include alkanediyl groups having 1 to 10 carbon atoms, such as methylene, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, and structural isomers thereof; cyclic saturated hydrocarbylene groups having 3 to 10 carbon atoms, such as cyclopropanediyl, cyclobutanediyl, cyclopentanediyl, and cyclohexanediyl; and groups obtained by combining these. When the saturated hydrocarbylene group contains an ether bond, when b1 in formula (B2-1) is 1, it may be located at any position except between the carbon atom at the α position and the carbon atom at the β position relative to the ester oxygen atom. When b1 is 0, the atom bonded to the main chain is an ether oxygen atom, and the second ether bond may be inserted at any position except between the carbon atom at the α-position and the carbon atom at the β-position with respect to the ether oxygen atom. If the number of carbon atoms in the saturated hydrocarbylene group is 10 or less, sufficient solubility in an alkaline developer can be obtained, which is preferable.

[0208] In formula (B2-1), when b4 is 1, X is an acid labile group. When b4 is 2 or 3, each X is independently a hydrogen atom or an acid labile group, and at least one of them is an acid labile group. That is, in the repeating unit B2-1, at least one of the phenolic hydroxyl groups bonded to the aromatic ring is protected with an acid labile group, or the carboxyl group bonded to the aromatic ring is protected with an acid labile group. The acid labile group is not particularly limited and any of those that have been used in many known chemically amplified positive resist compositions and that are detached by an acid to give an acidic group can be used.

[0209] The acid labile group may, for example, be a tertiary saturated hydrocarbyl group. The tertiary saturated hydrocarbyl group preferably has 4 to 18 carbon atoms so that the resulting monomer for polymerization is obtained by distillation.

[0210] The saturated hydrocarbyl group bonded to the tertiary carbon atom of the tertiary saturated hydrocarbyl group preferably has 1 to 15 carbon atoms. The saturated hydrocarbyl group having 1 to 15 carbon atoms may be linear, branched, or cyclic, and may contain an oxygen atom-containing functional group such as an ether bond or a carbonyl group between its carbon-carbon bonds. In addition, the saturated hydrocarbyl groups bonded to the tertiary carbon atom may be bonded to each other to form a ring together with the tertiary carbon atom to which they are bonded.

[0211] Examples of the alkyl substituent include a methyl group, an ethyl group, a propyl group, an adamantyl group, a norbornyl group, a tetrahydrofuran-2-yl group, a 7-oxanorbornan-2-yl group, a cyclopentyl group, a 2-tetrahydrofuryl group, a tricyclo[5.2.1.0 2,6 ]decyl group, 8-ethyl-8-tricyclo[5.2.1.0 2,6 ]decyl group, 3-methyl-3-tetracyclo[4.4.0.1 2,5 .1 7,10 ]dodecyl group, tetracyclo[4.4.0.1 2,5 .1 7,10 ]dodecyl group, 3-oxo-1-cyclohexyl group, and the like.

[0212] Examples of the tertiary saturated hydrocarbyl group include a tert-butyl group, a tert-pentyl group, a 1-ethyl-1-methylpropyl group, a 1,1-diethylpropyl group, a 1,1,2-trimethylpropyl group, a 1-adamantyl-1-methylethyl group, a 1-methyl-1-(2-norbornyl)ethyl group, a 1-methyl-1-(tetrahydrofuran-2-yl)ethyl group, a 1-methyl-1-(7-oxanorbornan-2-yl)ethyl group, a 1-methylcyclopentyl group, a 1-ethylcyclopentyl group, 1-propylcyclopentyl group, 1-cyclopentylcyclopentyl group, 1-cyclohexylcyclopentyl group, 1-(2-tetrahydrofuryl)cyclopentyl group, 1-(7-oxanorbornan-2-yl)cyclopentyl group, 1-methylcyclohexyl group, 1-ethylcyclohexyl group, 1-cyclopentylcyclohexyl group, 1-cyclohexylcyclohexyl group, 2-methyl-2-norbornyl group, 2-ethyl-2-norbornyl group, 8-methyl-8-tricyclo[5.2.1.0 2,6 ]decyl group, 8-ethyl-8-tricyclo[5.2.1.0 2,6 ]decyl group, 3-methyl-3-tetracyclo[4.4.0.1 2,5 .1 7,10 ]dodecyl group, 3-ethyl-3-tetracyclo[4.4.0.1 2,5 .1 7,10 ]dodecyl group, 2-methyl-2-adamantyl group, 2-ethyl-2-adamantyl group, 1-methyl-3-oxo-1-cyclohexyl group, 1-methyl-1-(tetrahydrofuran-2-yl)ethyl group, 5-hydroxy-2-methyl-2-adamantyl group, and 5-hydroxy-2-ethyl-2-adamantyl group.

[0213] The acid labile group may be a group represented by the following formula (B2-1-1). The group represented by formula (B2-1-1) is often used as an acid labile group, and is a useful option as an acid labile group that stably gives a pattern with a relatively rectangular interface between the pattern and the substrate. When X is a group represented by formula (B2-1-1), an acetal structure is formed. [ka] (In the formula, the dashed lines represent bonds.)

[0214] In formula (B2-1-1), R L1 is a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. The saturated hydrocarbyl group may be linear, branched or cyclic.

[0215] R L1 is appropriately selected depending on the design of the sensitivity of the decomposable group to acid. For example, if the design is to ensure relatively high stability while being decomposed by strong acid, a group in which the carbon atom bonded to the hydrogen atom or the acetal carbon is a tertiary carbon atom is preferred. R bonded to the acetal carbon by a tertiary carbon atom L1 Examples of R include, but are not limited to, a tert-butyl group, a tert-pentyl group, and a 1-adamantyl group. If the design is to achieve high sensitivity to pH changes by using a relatively high reactivity, a straight-chain alkyl group is preferred. Depending on the combination with the acid generator and quencher to be incorporated in the resist composition, R L2 In the case where a relatively large alkyl group is selected at the end of the alkyl group, and the solubility change due to decomposition is large, R L1 As for R, the carbon atom bonded to the acetal carbon is preferably a secondary carbon atom. L1 Examples of the aryl group include, but are not limited to, an isopropyl group, a sec-butyl group, a cyclopentyl group, a cyclohexyl group, and the like.

[0216] In formula (B2-1-1), R L2is a hydrocarbyl group having 1 to 30 carbon atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A part of -CH2- in the hydrocarbyl group may be substituted with a heteroatom such as an oxygen atom or a sulfur atom, and as a result, the hydrocarbyl group may contain an ether bond, a sulfide bond, or the like. Specific examples of the hydrocarbyl group include saturated hydrocarbyl groups having 1 to 30 carbon atoms and aryl groups having 6 to 30 carbon atoms. In particular, in order to obtain higher resolution in the formation of fine patterns, R L2 R is preferably a hydrocarbyl group having 1 to 6 carbon atoms. L2 When is a hydrocarbyl group having 1 to 6 carbon atoms, the alcohol generated after the deprotection reaction with an acid proceeds is water-soluble, and therefore dissolves in an alkaline developer when a positive pattern is formed using the developer, thereby making it possible to suppress residual defects in exposed areas.

[0217] Preferred examples of the group represented by formula (B2-1-1) include, but are not limited to, the following: L1 is the same as above, and the dashed line represents a bond. [ka]

[0218] [ka]

[0219] As another acid labile group, a phenolic hydroxyl group in which a hydrogen atom is replaced with -CH2COO- (a tertiary saturated hydrocarbyl group) can be used. In this case, the tertiary saturated hydrocarbyl group can be the same as the tertiary saturated hydrocarbyl group used for protecting the phenolic hydroxyl group described above.

[0220] Further, the repeating unit B2 may be a repeating unit represented by the following formula (B2-2) (hereinafter, also referred to as repeating unit B2-2). The repeating unit B2-2 is a useful option as an acid labile group-containing unit that provides good performance against line width fluctuation in development loading because it increases the dissolution rate of the exposed area. [ka]

[0221] In formula (B2-2), c1 is an integer of 0 to 2. c2 is an integer of 0 to 2. c3 is an integer of 0 to 5. c4 is an integer of 0 to 2.

[0222] In formula (B2-2), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0223] In formula (B2-2), R 13 and R 14 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom, R 13 and R 14 may be bonded to each other to form a ring together with the carbon atoms to which they are attached.

[0224] In formula (B2-2), R 15 each independently represents a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, or a fluorinated alkoxy group having 1 to 5 carbon atoms.

[0225] In formula (B2-2), R 16 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom.

[0226] In formula (B2-2), A 3 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OA 31 -It is. 31represents an aliphatic hydrocarbylene group having 1 to 20 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond or a lactone ring, or a phenylene group or naphthylene group. * represents a bond to a carbon atom of the main chain.

[0227] Preferred examples of the repeating unit B2-2 include, but are not limited to, those shown below. In the following formula, R A is the same as above. [ka]

[0228] [ka]

[0229] The content of the repeating unit B2 is preferably 5 to 95 mol %, more preferably 20 to 80 mol %, of all repeating units constituting the polymer. The repeating unit B2 may be used alone or in combination of two or more kinds.

[0230] The polymer may contain at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (B3) (hereinafter also referred to as repeating unit B3), a repeating unit represented by the following formula (B4) (hereinafter also referred to as repeating unit B4), and a repeating unit represented by the following formula (B5) (hereinafter also referred to as repeating unit B5). [ka]

[0231] In the formulas (B3) and (B4), d is an integer of 0 to 6. e is an integer of 0 to 4.

[0232] In formulas (B3) and (B4), R 17 and R 18are 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 17 may be the same or different. When e is 2 or more, each R 18 may be the same as or different from each other.

[0233] In formula (B5), f1 is 0 or 1. f2 is an integer of 0 to 2, and when f2 is 0, it represents a benzene skeleton, when f2 is 1, it represents a naphthalene skeleton, and when f2 is 2, it represents an anthracene skeleton. f3 is an integer of 0 to 5. When f2 is 0, f3 is preferably an integer of 0 to 3, and when f2 is 1 or 2, f3 is preferably an integer of 0 to 4.

[0234] In formula (B5), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0235] In formula (B5), R 19 is a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbyloxyhydrocarbyl group having 2 to 20 carbon atoms, a saturated hydrocarbylthiohydrocarbyl group having 2 to 20 carbon atoms, a halogen atom, a nitro group, or a cyano group, and may be a hydroxy group when f2 is 1 or 2. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, saturated hydrocarbyloxyhydrocarbyl group, and saturated hydrocarbylthiohydrocarbyl group may be linear, branched, or cyclic. When f3 is 2 or more, each R 19 may be the same as or different from each other.

[0236] In formula (B5), A 4 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- in the saturated hydrocarbylene group may be substituted with -O-. The saturated hydrocarbylene group may be linear, branched, or cyclic. Specific examples thereof include A in formula (B1): 1 Examples of the examples are similar to those given in the description of .

[0237] When at least one of the repeating units B3 to B5 is used as a structural unit of the polymer, the addition of a ring structure to the main chain provides an effect of improving the etching resistance and EB irradiation resistance during pattern inspection in addition to the etching resistance of the aromatic ring.

[0238] The content of the repeating units B3 to B5 is preferably 5 mol % or more of all repeating units constituting the polymer in order to obtain the effect of improving etching resistance. The content of the repeating units B3 to B5 is preferably 25 mol % or less, more preferably 20 mol % or less of all repeating units constituting the polymer. When there is no functional group or when the functional group is other than a hydroxy group, it is preferable that the amount of introduction is 25 mol % or less, since there is no risk of development defects occurring. The repeating units B3 to B5 may be used alone or in combination of two or more.

[0239] The polymer preferably contains at least one selected from the group consisting of repeating units B1, B2, and B3 to B5, in that it is excellent in achieving both high etching resistance and high resolution. In this case, these repeating units preferably account for 60 mol % or more, more preferably 70 mol % or more, even more preferably 80 mol % or more, and even more preferably 90 mol % or more of the total repeating units of the polymer.

[0240] The polymer may contain at least one selected from a repeating unit represented by the following formula (B6) (hereinafter also referred to as repeating unit B6), a repeating unit represented by the following formula (B7) (hereinafter also referred to as repeating unit B7), a repeating unit represented by the following formula (B8) (hereinafter also referred to as repeating unit B8), and a repeating unit represented by the following formula (B9) (hereinafter also referred to as repeating unit B9). [ka]

[0241] In formulas (B6) to (B9), R A are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 is a single bond or a phenylene group. 2 teeth,* 1 -C(=O)-OX 21 -, * 1 -C(=O)-NH-X 21 -or* 1 -OX 21 -It is. X 21 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group.* 1 X 1 X represents a bond with 3 each independently represents a single bond, a phenylene group, a naphthylene group, or * 2 -C(=O)-OX 31 -It is. X 31 is an aliphatic hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the aliphatic hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring. 2 represents a bond to a carbon atom in the main chain. X 4 each independently represents a single bond, * 3 -X 41 -C(=O)-O-, * 3 -C(=O)-NH-X 41 -or* 3-OX 41 -It is. X 41 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 3 X 3 X represents a bond with 5 each independently represents a single bond, * 4 -X 51 -C(=O)-O-, * 4 -C(=O)-NH-X 51 -or* 4 -OX 51 -It is. X 51 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 4 X 4 X represents a bond with 6 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, * 2 -C(=O)-OX 61 -, * 2 -C(=O)-N(H)-X 61 -or* 2 -OX 61 -It is. X 61 is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. 2 represents a bond to a carbon atom in the main chain.

[0242] X 21 , X 31 and X 61The aliphatic hydrocarbylene group represented by the formula (I) may be linear, branched or cyclic, and specific examples thereof include a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,1-diyl group, a propane-1,2-diyl group, a propane-1,3-diyl group, a propane-2,2-diyl group, a butane-1,1-diyl group, a butane-1,2-diyl group, a butane-1,3-diyl group, a butane- Examples of the alkanediyl groups include a 2,3-diyl group, a butane-1,4-diyl group, a 1,1-dimethylethane-1,2-diyl group, a pentane-1,5-diyl group, a 2-methylbutane-1,2-diyl group, and a hexane-1,6-diyl group; cycloalkanediyl groups such as a cyclopropanediyl group, a cyclobutanediyl group, a cyclopentanediyl group, and a cyclohexanediyl group; and groups obtained by combining these groups.

[0243] X 41 and X 51 The hydrocarbylene group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include, but are not limited to, those shown below. [ka] (In the formula, the dashed lines represent bonds.)

[0244] In formula (B6), R 21 and R 22are 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 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, and a tert-butyl group; cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cyclopropylmethyl group, a 4-methylcyclohexyl 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; cyclic unsaturated hydrocarbyl groups having 3 to 20 carbon atoms, such as a cyclohexenyl group; aryl groups having 6 to 20 carbon atoms, such as a phenyl group, a naphthyl group, and a thienyl 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, with an aryl group being preferred. 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- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0245] Also, R 21 and R 22 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, the ring is as defined in the description of formula (cation-1) as R ct1 and R ct2 Examples of the ring that can be formed by bonding with the sulfur atom to which they are bonded include the same as those exemplified above.

[0246] Specific examples of the cation of the repeating unit B6 include, but are not limited to, those shown below. A is the same as above. [ka]

[0247] [ka]

[0248] [ka]

[0249] [ka]

[0250] [ka]

[0251] [ka]

[0252] [ka]

[0253] In formula (B6), M -is a non-nucleophilic counter ion. The non-nucleophilic counter ion is preferably a halide ion, a sulfonate anion, an imide anion, or a methide anion. Specific examples of the halide ion include a chloride ion and a bromide ion. Specific examples of the sulfonate anion (sulfonate ion) include fluoroalkylsulfonate ions such as a triflate ion, a 1,1,1-trifluoroethanesulfonate ion, and a nonafluorobutanesulfonate ion; arylsulfonate ions such as a tosylate ion, a benzenesulfonate ion, a 4-fluorobenzenesulfonate ion, and a 1,2,3,4,5-pentafluorobenzenesulfonate ion; and alkylsulfonate ions such as a mesylate ion and a butanesulfonate ion. Specific examples of the imide anion (imide ion) include a bis(trifluoromethylsulfonyl)imide ion, a bis(perfluoroethylsulfonyl)imide ion, and a bis(perfluorobutylsulfonyl)imide ion. Specific examples of the methide acid anion (methide ion) include tris(trifluoromethylsulfonyl)methide ion, tris(perfluoroethylsulfonyl)methide ion, and the like.

[0254] Other examples of the non-nucleophilic counter ion include anions represented by any of the following formulas (B6-1) to (B6-4). [ka]

[0255] In formula (B6-1), R fa is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R fa1 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0256] The anion represented by formula (B6-1) is preferably one represented by the following formula (B6-1-1): [ka]

[0257] In formula (B6-1-1), Q 11 and Q 12 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, and in order to improve the solvent solubility, it is preferable that at least one of them is a trifluoromethyl group. m is an integer of 0 to 4, and is particularly preferably 1. R fa1 is a hydrocarbyl group having 1 to 35 carbon atoms which may contain a heteroatom. The heteroatom is preferably an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, or the like, and more preferably an oxygen atom. From the viewpoint of obtaining high resolution in the formation of a fine pattern, the hydrocarbyl group is preferably one having 6 to 30 carbon atoms.

[0258] In formula (B6-1-1), R fa1The hydrocarbyl group having 1 to 35 carbon atoms and 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 35 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, a nonyl group, an undecyl group, a tridecyl group, a pentadecyl group, a heptadecyl group, and an icosyl group; a cyclopentyl group, a cyclohexyl group, a 1-adamantyl group, a 2-adamantyl group, a 1-adamantylmethyl group, a norbornyl group, a norbornyl group, and a cyclohexyl group. Examples of the alkyl group include cyclic saturated hydrocarbyl groups having 3 to 35 carbon atoms, such as bornylmethyl group, tricyclodecyl group, tetracyclododecyl group, tetracyclododecylmethyl group, and dicyclohexylmethyl group; unsaturated aliphatic hydrocarbyl groups having 2 to 35 carbon atoms, such as allyl group and 3-cyclohexenyl group; aryl groups having 6 to 35 carbon atoms, such as phenyl group, 1-naphthyl group, 2-naphthyl group, and 9-fluorenyl group; aralkyl groups having 7 to 35 carbon atoms, such as benzyl group and diphenylmethyl group; and groups obtained by combining these groups.

[0259] 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- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like. Examples of hydrocarbyl groups containing a heteroatom include a tetrahydrofuryl group, a methoxymethyl group, an ethoxymethyl group, a methylthiomethyl group, an acetamidomethyl group, a trifluoroethyl group, a (2-methoxyethoxy)methyl group, an acetoxymethyl group, a 2-carboxy-1-cyclohexyl group, a 2-oxopropyl group, a 4-oxo-1-adamantyl group, and a 3-oxocyclohexyl group.

[0260] In formula (B6-1-1), L a1 is a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond or a carbamate bond, and from the viewpoint of synthesis, an ether bond or an ester bond is preferable, and an ester bond is more preferable.

[0261] Examples of the anion represented by formula (B6-1) include, but are not limited to, those shown below. In the following formula, Q 11 is the same as above, and Ac is an acetyl group. [ka]

[0262] [ka]

[0263] [ka]

[0264] [ka]

[0265] [ka]

[0266] [ka]

[0267] [ka]

[0268] [ka]

[0269] [ka]

[0270] [ka]

[0271] In formula (B6-2), R fb1 and R fb2 are each independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R fa1 Examples of the hydrocarbyl group represented by the formula R include the same as those exemplified above. fb1 and R fb2 is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fb1 and R fb2 are bonded to each other and the group to which they are bonded (-CF2-SO2-N - -SO2-CF2-) may form a ring, in which case R fb1 and R fb2 The group obtained by bonding together is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0272] In formula (B6-3), R fc1 , R fc2 and R fc3 are each independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R fa1 Examples of the hydrocarbyl group represented by the formula R include the same as those exemplified above. fc1 , R fc2 and R fc3is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fc1 and R fc2 are bonded to each other and the groups to which they are bonded (-CF2-SO2-C - -SO2-CF2-) may form a ring, in which case R fc1 and R fc2 The group obtained by bonding together is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0273] In formula (B6-4), R fd is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R fa1 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0274] Examples of the anion represented by formula (B6-4) include, but are not limited to, those shown below. [ka]

[0275] [ka]

[0276] Further examples of the non-nucleophilic counter ion include anions having an aromatic ring substituted with an iodine atom or a bromine atom. Specific examples of such anions include those represented by the following formula (B6-5). [ka]

[0277] In formula (B6-5), p is an integer satisfying 1≦p≦3. q and r are integers satisfying 1≦q≦5, 0≦r≦3, and 1≦q+r≦5. q is preferably 1, 2, or 3, and more preferably 2 or 3. r is preferably 0, 1, or 2.

[0278] In formula (B6-5), X BI represents an iodine atom or a bromine atom, and when p and / or q are 2 or more, they may be the same or different.

[0279] In formula (B6-5), L 1 is a single bond, an ether bond or an ester bond, or a saturated hydrocarbylene group having 1 to 6 carbon atoms which may contain an ether bond or an ester bond. The saturated hydrocarbylene group may be linear, branched or cyclic.

[0280] In formula (B6-5), L 2 represents a single bond or a divalent linking group having 1 to 20 carbon atoms when p is 1, and represents a (p+1)-valent linking group having 1 to 20 carbon atoms when p is 2 or 3, and the linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

[0281] In formula (B6-5), R fe is a hydroxy group, a carboxy group, a fluorine atom, a chlorine atom, a bromine atom or an amino group, or a hydrocarbyl group having 1 to 20 carbon atoms, a hydrocarbyloxy group having 1 to 20 carbon atoms, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms, a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms or a hydrocarbylsulfonyloxy group having 1 to 20 carbon atoms which may contain a fluorine atom, a chlorine atom, a bromine atom, a hydroxy group, an amino group or an ether bond, or feA )(R feB ), -N(R feC )-C(=O)-R feD Or -N(R feC )-C(=O)-OR feD R feA and R feBR are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. feC R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and may contain a halogen atom, a hydroxy group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. feD is an aliphatic hydrocarbyl group having 1 to 16 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 15 carbon atoms, and may contain a halogen atom, a hydroxy group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. The aliphatic hydrocarbyl group may be saturated or unsaturated and may be linear, branched, or cyclic. The hydrocarbyl group, hydrocarbyloxy group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, and hydrocarbylsulfonyloxy group may be linear, branched, or cyclic. When p and / or r is 2 or more, each R fe may be the same or different from each other.

[0282] Of these, R fe Examples of the hydroxyl group include -N(R feC )-C(=O)-R feD , -N(R feC )-C(=O)-OR feD , a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, and the like are preferred.

[0283] In formula (B6-5), Rf 11 ~Rf 14 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, at least one of which is a fluorine atom or a trifluoromethyl group. 11 and Rf 12 may combine to form a carbonyl group. 13 and Rf 14 are preferably both fluorine atoms.

[0284] Examples of the anion represented by formula (B6-5) include, but are not limited to, those shown below. In the following formula, X BI is the same as above. [ka]

[0285] [ka]

[0286] [ka]

[0287] [ka]

[0288] [ka]

[0289] [ka]

[0290] [ka]

[0291] [ka]

[0292] [ka]

[0293] [ka]

[0294]

change

[0295]

change

[0296]

change

[0297]

change

[0298]

change

[0299]

change

[0300]

change

[0301]

change

[0302]

change

[0303]

change

[0304] [ka]

[0305] [ka]

[0306] [ka]

[0307] As the non-nucleophilic counter ion, a fluorobenzenesulfonate anion bonded to an aromatic group containing an iodine atom as described in Japanese Patent No. 6648726, an anion having a mechanism of decomposition by acid as described in International Publication No. 2021 / 200056 and Japanese Patent Application Publication No. 2021-70692, an anion having a cyclic ether group as described in Japanese Patent Application Publication No. 2018-180525 and Japanese Patent Application Publication No. 2021-35935, and an anion as described in Japanese Patent Application Publication No. 2018-92159 can also be used.

[0308] Further, as the non-nucleophilic counter ion, anions of bulky benzenesulfonic acid derivatives not containing fluorine atoms, as described in JP 2006-276759 A, JP 2015-117200 A, JP 2016-65016 A, and JP 2019-202974 A, and benzenesulfonic acid anions and alkylsulfonic acid anions not containing fluorine atoms bonded to aromatic groups containing iodine atoms, as described in Japanese Patent No. 6645464, can also be used.

[0309] Further examples of the non-nucleophilic counter ion include an anion of bissulfonic acid described in JP 2015-206932 A, an anion of sulfonamide or sulfonimide having a sulfonic acid on one side and a different sulfonic acid on the other side described in WO 2020 / 158366 A, and an anion of sulfonic acid on one side and carboxylic acid on the other described in JP 2015-24989 A.

[0310] In formulas (B7) and (B8), L 1 is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate ester bond, a carbonate bond or a carbamate bond. Among these, from the viewpoint of synthesis, an ether bond, an ester bond or a carbonyl group is preferred, and an ester bond or a carbonyl group is more preferred.

[0311] In formula (B7), Rf 1 and Rf 2 are each independently a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 1 and Rf 2 In order to increase the acid strength of the generated acid, each of Rf is preferably a fluorine atom. 3 and Rf 4 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Of these, Rf 3 and Rf 4 At least one of these is preferably a trifluoromethyl group.

[0312] In formula (B8), Rf 5 and Rf 6 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 5 and Rf 6 Of these, Rf 5 and Rf 6 At least one of these is preferably a trifluoromethyl group.

[0313] In the formulae (B7) and (B8), g1 and g2 are integers of 0 to 3, with 1 being preferred.

[0314] Specific examples of the anion of the repeating unit B7 include, but are not limited to, those shown below. A is the same as above. [ka]

[0315] [ka]

[0316] [ka]

[0317] [ka]

[0318] [ka]

[0319] [ka]

[0320] [ka]

[0321] Specific examples of the anion of the repeating unit B8 include, but are not limited to, those shown below. A is the same as above. [ka]

[0322] [ka]

[0323] [ka]

[0324] [ka]

[0325] [ka]

[0326] [ka]

[0327] [ka]

[0328] Specific examples of the anion of the repeating unit B9 include, but are not limited to, those shown below. A is the same as above. [ka]

[0329] In formulas (B6) to (B9), A + is an onium cation. The onium cation may be a sulfonium cation, an iodonium cation, an ammonium cation, or the like, but is 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).

[0330] The repeating units B6 to B9 are units that generate acid by irradiation with high energy rays. It is believed that the inclusion of these units in the polymer appropriately suppresses acid diffusion, and thus makes it possible to obtain a pattern with reduced LER. In addition, the inclusion of these units in the polymer suppresses the phenomenon in which acid volatilizes from the exposed area during baking in a vacuum and reattaches to the unexposed area, and is therefore effective in reducing LER and reducing shape deterioration due to unwanted film loss in the unexposed area.

[0331] Among the repeating units B6 to B9, the repeating units B7 to B9 are preferable as units suitable for processing the photomask blank, because they have the optimum acid strength for suppressing acid diffusion and designing the acid labile groups of the polymer, and the repeating units B7 and B8 are more preferable.

[0332] The repeating units B6 to B9 are preferably incorporated in an amount of 0.1 to 30 mol %, more preferably 0.5 to 20 mol %, based on the total amount of repeating units in the polymer. The repeating units B6 to B9 may be used alone or in combination of two or more.

[0333] The content of repeating units having an aromatic ring skeleton in all repeating units of the polymer is preferably 65 mol % or more, more preferably 75 mol % or more, and even more preferably 85 mol % or more. When the repeating units B6 to B9 are not included, it is preferable that all units have an aromatic ring skeleton.

[0334] The polymer may contain a commonly used (meth)acrylic acid ester unit protected by an acid labile group, or a (meth)acrylic acid ester unit having an adhesive group such as a lactone structure or a hydroxy group other than a phenolic hydroxy group. Although these repeating units allow fine adjustment of the properties of the resist film, they may not be included.

[0335] Examples of the (meth)acrylic acid ester unit having the adhesive group include a repeating unit represented by the following formula (B10) (hereinafter also referred to as repeating unit B10), a repeating unit represented by the following formula (B11) (hereinafter also referred to as repeating unit B11), and a repeating unit represented by the following formula (B12) (hereinafter also referred to as repeating unit B12). These units do not exhibit acidity and can be used auxiliary as units that impart adhesion to a substrate or units that adjust solubility. [ka]

[0336] In formulas (B10) to (B12), R A R is each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 31 is -O- or a methylene group. 32 R is a hydrogen atom or a hydroxyl group. 33 is a saturated hydrocarbyl group having 1 to 4 carbon atoms. h is an integer of 0 to 3.

[0337] When the repeating units B10 to B12 are contained, the content thereof is preferably 0 to 20 mol %, more preferably 0 to 10 mol %, based on the total repeating units of the polymer. The repeating units B10 to B12 may be used alone or in combination of two or more kinds.

[0338] The polymer can be synthesized by copolymerizing each monomer protected by a protecting group as necessary by a known method, and then carrying out a deprotection reaction as necessary. The copolymerization reaction is not particularly limited, but is preferably radical polymerization or anionic polymerization. For these methods, JP-A-2004-115630 can be referred to.

[0339] The polymer preferably has a weight average molecular weight (Mw) of 1000 to 50000, more preferably 2000 to 20000. If Mw is 1000 or more, there is no risk of the phenomenon that the head of the pattern becomes rounded, the resolution decreases, and the LER deteriorates, as has been known in the past. On the other hand, if Mw is 50000 or less, there is no risk of the LER deteriorates, particularly when a pattern having a pattern line width of 100 nm or less is formed. In the present invention, Mw is a value measured in terms of polystyrene by gel permeation chromatography (GPC) using THF or DMF as a solvent.

[0340] The polymer preferably has a narrow molecular weight distribution (Mw / Mn) of 1.0 to 2.0, preferably 1.0 to 1.9, and more preferably 1.0 to 1.8. When the polymer has such a narrow molecular weight distribution, no foreign matter is generated on the pattern after development, and the shape of the pattern is not deteriorated.

[0341] In addition, as the base polymer design, the dissolution rate in an alkaline developer is preferably 10 nm / min or less, more preferably 7 nm / min or less, and even more preferably 5 nm / min or less. In the advanced generation, when the coating film on the substrate is in the thin film region (100 nm or less), the effect of pattern film loss due to alkaline development becomes large, and when the alkaline dissolution rate of the polymer is more than 10 nm / min, the pattern collapses and fine patterns cannot be formed. This is particularly noticeable in photomask production, which requires no defects, because the development process tends to be strong. In addition, in the present invention, the dissolution rate of the base polymer in an alkaline developer is a value calculated from the amount of film loss when a polymer solution (polymer concentration: 16.7 mass%, solvent: propylene glycol monomethyl ether acetate (PGMEA)) is spin-coated on an 8-inch silicon wafer, baked at 100°C for 90 seconds to form a film with a thickness of 1000 nm, and then developed at 23°C for 100 seconds with a 2.38 mass% aqueous solution of tetramethylammonium hydroxide (TMAH).

[0342] The base polymer of the component (B) may contain other polymers other than the above-mentioned polymer. As the other polymers, those conventionally known as base polymers for resist compositions can be used. The content of the other polymers is not particularly limited as long as it does not impair the effects of the present invention.

[0343] [(C) Organic solvent] The resist composition of the present invention may contain an organic solvent as component (C). The organic solvent is not particularly limited as long as it can dissolve each component. Examples of such organic solvents include ketones such as cyclohexanone, cyclopentanone, methyl-2-n-pentyl ketone, and 2-heptanone, as described in paragraphs

[0144] and

[0145] of JP-A-2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol; propylene glycol monomethyl ether (PGME), ethylene glycol monomethyl ether, and propylene glycol monoethyl ether. ethers such as ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as PGMEA, propylene glycol monoethyl ether acetate, ethyl lactate (EL), ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol 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, can be added to accelerate the deprotection reaction of the acetal.

[0344] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, PGME, cyclohexanone, EL, γ-butyrolactone, and mixed solvents thereof are preferable.

[0345] When the chemically amplified positive resist composition of the present invention contains an organic solvent (C), the content thereof 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 base polymer (B). The organic solvent (C) may be used alone or in combination of two or more kinds.

[0346] [(D) Fluorine atom-containing polymer] The chemically amplified positive resist composition of the present invention, for the purposes of increasing contrast, suppressing the chemical flare phenomenon of acid when irradiated with high-energy rays, shielding mixing of acid from the antistatic film in the process of applying an antistatic film material onto the resist film, and suppressing unexpected and unnecessary pattern degradation, may contain, as the component (D), a fluorine-containing polymer that contains at least one selected from the group consisting of a repeating unit represented by formula (D1) below (hereinafter also referred to as repeating unit D1), a repeating unit represented by formula (D2) below (hereinafter also referred to as repeating unit D2), a repeating unit represented by formula (D3) below (hereinafter also referred to as repeating unit D3), and a repeating unit represented by formula (D4) below (hereinafter also referred to as repeating unit D4), and may further contain at least one selected from the group consisting of a repeating unit represented by formula (D5) below (hereinafter also referred to as repeating unit D5) and a repeating unit represented by formula (D6) below (hereinafter also referred to as repeating unit D6). The fluorine atom-containing polymer also functions as a surfactant, and is therefore effective against development defects since it can prevent insoluble matter from re-adhering to the substrate during the development process. [ka]

[0347] In the formulas (D1) to (D6), j1 is an integer of 1 to 3. j2 is an integer that satisfies 0≦j2≦5+2(j3)−j1. j3 is 0 or 1. k is an integer of 1 to 3. R B R is each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. CR is each independently a hydrogen atom or a methyl group. 101 , R 102 , R 104 and R 105 R are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. 103 , R 106 , R 107 and R 108 each independently represents 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 103 , R 106 , R 107 and R 108 When R is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bonds. 109 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 the carbon-carbon bonds. 110 R is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a heteroatom-containing group between its carbon-carbon bonds. 111 Z is a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, and a part of the -CH2- in the saturated hydrocarbyl group may be substituted with an ester bond or an ether bond. 1 Z is a (k+1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (k+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. Z 3 is a single bond, -O-, *-C(=O)-OZ 31 -Z 32 - or -C(=O)-NH-Z 31 -Z 32 -It is. 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. * represents a bond to a carbon atom of the main chain.

[0348] In formulas (D1) and (D2), R 101 , R 102 , R 104 and R 105 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 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-heptyl group, an n-octyl group, an n-nonyl group or an n-decyl group; and cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group or a norbornyl group. Of these, saturated hydrocarbyl groups having 1 to 6 carbon atoms are preferred.

[0349] In formulas (D1) to (D4), R 103 , R 106 , R 107 and R 108 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, and an alkyl group having 1 to 15 carbon atoms is preferred. In addition to the above, 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, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, and an n-pentadecyl group. Examples of the fluorinated hydrocarbyl group include a group in which some or all of the hydrogen atoms bonded to the carbon atoms of the above-mentioned hydrocarbyl group are substituted with fluorine atoms.

[0350] In formula (D4), Z 1Examples of the (k+1)-valent hydrocarbon group having 1 to 20 carbon atoms and represented by the formula (1) include an alkyl group having 1 to 20 carbon atoms or a group in which k hydrogen atoms have been removed from a cyclic saturated hydrocarbyl group having 3 to 20 carbon atoms. 1 Examples of the (k+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by the following formula include groups in which at least one hydrogen atom of the above-mentioned (k+1)-valent hydrocarbon group has been substituted with a fluorine atom.

[0351] Specific examples of the repeating units D1 to D4 include, but are not limited to, those shown below. B is the same as above. [ka]

[0352] [ka]

[0353] [ka]

[0354] In formula (D5), R 109 and R 110 Examples of the hydrocarbyl group having 1 to 5 carbon atoms represented by the formula (1) 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.

[0355] In formula (D5), -OR 109 is preferably a hydrophilic group. In this case, R 109 is preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms and an oxygen atom intervening between the carbon-carbon bonds, or the like.

[0356] In formula (D5), 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 the diffusion of acid. This improves the stability of the resist film over time, and the resolution and pattern shape do not deteriorate.

[0357] Examples of the repeating unit D5 include, but are not limited to, those shown below. In the following formula, R C is the same as above. [ka]

[0358] [ka]

[0359] In formula (D6), 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.

[0360] In formula (D6), R 111The saturated hydrocarbyl group having 1 to 20 carbon atoms and at least one hydrogen atom of which is substituted with a fluorine atom, represented by the formula (I) 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 is substituted with a fluorine atom.

[0361] Examples of the repeating unit D6 include, but are not limited to, those shown below. In the following formula, R C is the same as above. [ka]

[0362] [ka]

[0363] [ka]

[0364] [ka]

[0365] The content of the repeating units D1 to D4 is preferably 15 to 95 mol %, more preferably 20 to 85 mol %, based on all repeating units of the fluorine atom-containing polymer. The content of the repeating units D5 and / or D6 is preferably 5 to 85 mol %, more preferably 15 to 80 mol %, based on all repeating units of the fluorine atom-containing polymer. The repeating units D1 to D6 may be used alone or in combination of two or more.

[0366] The fluorine atom-containing polymer (D) may contain other repeating units in addition to the repeating units described above. Examples of such repeating units include those described in paragraphs

[0046] to

[0078] of JP2014-177407A. When the fluorine atom-containing polymer (D) contains other repeating units, the content of such units is preferably 50 mol% or less of the total repeating units of the fluorine atom-containing polymer.

[0367] (D) The fluorine atom-containing polymer can be synthesized by copolymerizing each monomer protected by a protecting group as necessary by a known method, and then carrying out a deprotection reaction as necessary. The copolymerization reaction is not particularly limited, but is preferably radical polymerization or anionic polymerization. For these methods, JP-A-2004-115630 can be referred to.

[0368] The Mw of the fluorine atom-containing polymer (D) is preferably 2000 to 50000, more preferably 3000 to 20000. If the Mw is less than 2000, the diffusion of the acid is promoted, which may result in deterioration of the resolution and deterioration of the stability over time. If the Mw is too large, the solubility in the solvent may decrease, which may cause coating defects. In addition, the Mw / Mn of the fluorine atom-containing polymer (D) is preferably 1.0 to 2.2, more preferably 1.0 to 1.7.

[0369] When the chemically amplified positive resist composition of the present invention contains the fluorine atom-containing polymer (D), the content thereof is preferably 0.01 to 30 parts by mass, and more preferably 0.1 to 20 parts by mass, relative to 80 parts by mass of the base polymer (B). The fluorine atom-containing polymer (D) may be used alone or in combination of two or more kinds.

[0370] [(E) Quencher] The chemically amplified positive resist composition of the present invention may contain a quencher as component (E) as necessary. In the present invention, the quencher means a compound that traps the acid generated from the acid generator. This makes it possible to suppress the diffusion speed of the acid generated from the acid generator when it diffuses into the resist film, and even when a substrate is used whose outermost surface is made of a material containing chromium, it is possible to suppress the effect of the acid generated in the resist film on the material containing chromium.

[0371] The quencher may be a conventional basic compound. Examples of conventional basic compounds include primary, secondary, and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxy group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxy 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-A-2008-111103, particularly amine compounds having a hydroxy group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonic acid ester bond, or compounds having a carbamate group described in JP-A-3790649 are preferred. Preferable examples include tris[2-(methoxymethoxy)ethyl]amine, tris[2-(methoxymethoxy)ethyl]amine-N-oxide, dibutylaminobenzoic acid, morpholine derivatives, imidazole derivatives, etc. By adding such a basic compound, for example, it is possible to further suppress the diffusion rate of the acid in the resist film and correct the shape.

[0372] Further, the quencher may be an onium salt such as a sulfonium salt, an iodonium salt, or an ammonium salt of a carboxylic acid not fluorinated at the α-position, as described in JP-A-2008-158339. A sulfonic acid, an imide acid, or a methide acid fluorinated at the α-position is necessary for deprotecting an acid labile group, but a carboxylic acid not fluorinated at the α-position is released by salt exchange with an onium salt not fluorinated at the α-position. A carboxylic acid not fluorinated at the α-position hardly undergoes a deprotection reaction, and therefore functions as a quencher.

[0373] An example of an onium salt of a carboxylic acid not fluorinated at the α-position is one represented by the following formula (E1). [ka]

[0374] In formula (E1), 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.

[0375] R 201 The hydrocarbyl group represented by the formula (1) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 40 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, or an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, a 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; a phenyl group, a naphthyl group, an alkylphenyl group (2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butylphenyl group, 5-butylphenyl group, 6-butylphenyl group, 7-butylphenyl group, 8-butylphenyl group, 9-butylphenyl group, 10-butylphenyl group, 11-butylphenyl group, 12-butylphenyl group, 13-butylphenyl group, 14-butylphenyl group, 15-butylphenyl group, 16-butylphenyl group, 17-butylphenyl group, 18-butylphenyl group, 19-butylphenyl group, 20-butylphenyl group, 21-butylphenyl group, 22-butylphenyl group, 23-butylphenyl group, 24-butylphenyl group, 25-butylphenyl group, 26-butylphenyl group, 27-butylphenyl group, 28-butylphenyl group, 29-butylphenyl group, 30-butylphenyl group, 31-butylphenyl group, 32-butylphenyl group, 33-butylphenyl group, 34-butylphenyl group, 35-butylphenyl group, 36-butylphenyl group, 37-butylphenyl group, 38-butylphenyl group, 39-butylphenyl group, 40-butylphenyl group, 41-butylphenyl group, 42-butylphenyl group, 43-butylphenyl group, 44-butylphenyl group, 45-butylphenyl group, 46-butylphenyl group, 4 Examples of such aryl groups include aryl groups having 6 to 40 carbon atoms, such as arylphenyl groups (e.g., 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), 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.

[0376] 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- 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.

[0377] In formula (E1), Mq A + is an onium cation. The onium cation is preferably a sulfonium cation, an iodonium cation or an ammonium cation, more preferably a sulfonium cation or an iodonium 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). Specific examples of the iodonium cation include the same as those exemplified as specific examples of the iodonium cation represented by formula (cation-2).

[0378] Examples of the anion of the onium salt represented by formula (E1) include, but are not limited to, those shown below. [ka]

[0379] [ka]

[0380] [ka]

[0381] As the quencher, a sulfonium salt of an iodized benzene ring-containing carboxylic acid represented by the following formula (E2) can also be suitably used. [ka]

[0382] In formula (E2), 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.

[0383] In formula (E2), 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.

[0384] In formula (E2), 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.

[0385] In formula (E2), R 212 , R 213 and R 214 are each independently a halogen atom or 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 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. In addition, some or all of the hydrogen atoms of 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, and some of the -CH2- of 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. In addition, 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.

[0386] Specific examples of the compound represented by formula (E2) include those described in JP 2017-219836 A. The compound represented by formula (E2) has high absorption, a high sensitizing effect, and a high acid diffusion control effect.

[0387] As the quencher, a nitrogen-containing carboxylate compound represented by the following formula (E3) can also be used. [ka]

[0388] In formula (E3), R 221 ~R 224 Each independently represents a hydrogen atom, -L 12 -CO2 - or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 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.

[0389] In formula (E3), 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 a part of the carbon atoms of the ring may be substituted with a sulfur atom, an oxygen atom, or a nitrogen atom. The ring may be an alicyclic ring or an aromatic ring, and is preferably a 5-membered or 6-membered ring, and specific examples thereof 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.

[0390] The carboxylic acid onium salt represented by formula (E3) has at least one -L 12 -CO2 - That is, R 221 ~R 224 At least one of the following is -L12 -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

[0391] In formula (E3), 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).

[0392] Examples of the anion of the compound represented by formula (E3) include, but are not limited to, those shown below. [ka]

[0393] [ka]

[0394] [ka]

[0395] [ka]

[0396] [ka]

[0397] [ka]

[0398] Alternatively, a weak acid betaine type compound may be used as the quencher, specific examples of which include, but are not limited to, those shown below. [ka]

[0399] Further examples of the quencher include polymer-type quenchers described in JP 2008-239918 A. These improve the rectangularity of the resist pattern by being oriented on the surface of the resist film. Polymer-type quenchers also have the effect of preventing film loss of the pattern and rounding of the pattern top when a protective film for immersion exposure is applied.

[0400] When the chemically amplified positive resist composition of the present invention contains a quencher, 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 quencher may be used alone or in combination of two or more kinds.

[0401] 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, 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.

[0402] [(F) Other photoacid generators] The chemically amplified positive resist composition of the present invention may contain a photoacid generator other than the photoacid generator consisting of an onium salt represented by formula (A) and the polymer-bound photoacid generator represented by formulas (B6) to (B9). The other photoacid generator is not particularly limited as long as it is a compound that generates an acid upon irradiation with high-energy rays. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, and oxime-O-sulfonate-type acid generators.

[0403] Specific examples of the other photoacid generators include nonafluorobutanesulfonate, the partially fluorinated sulfonates described in JP-A-2012-189977, paragraphs

[0247] to

[0251] , the partially fluorinated sulfonates described in JP-A-2013-101271, paragraphs

[0261] to

[0265] , the partially fluorinated sulfonates described in JP-A-2008-111103, paragraphs

[0122] to

[0142] , and the ones described in JP-A-2010-215608, paragraphs

[0080] to

[0081] , etc. Among the specific examples, arenesulfonate-type or alkane sulfonate-type photoacid generators are preferred because they generate an acid of suitable strength for deprotecting the acid labile group of the repeating unit B2.

[0404] As such a photoacid generator, a salt compound containing the anion shown below is preferable. [ka]

[0405] [ka]

[0406] [ka]

[0407] [ka]

[0408]

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[0409]

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[0410]

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[0411]

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[0412]

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[0413]

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[0414]

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[0415]

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[0416]

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[0417]

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[0418]

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[0419]

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[0420]

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[0421]

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[0422]

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[0423]

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[0424]

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[0425]

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[0426]

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[0427]

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[0428]

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[0429]

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[0430]

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[0431]

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[0432]

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[0433]

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[0434]

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[0435]

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[0436]

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[0437]

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[0438]

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[0439]

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[0440]

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[0441]

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[0442]

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[0443]

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[0444]

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[0445]

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[0446]

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[0447]

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[0448]

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[0449]

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[0450]

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[0451]

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[0452]

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[0453]

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[0454]

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[0455]

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[0456]

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[0457]

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[0458]

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[0459]

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[0460]

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[0461] [ka]

[0462] [ka]

[0463] [ka]

[0464] [ka]

[0465] Furthermore, as the photoacid generator, a salt compound containing an anion represented by the following formula (F1) is also preferred. [ka]

[0466] In formula (F1), m1 is 0 or 1. x is an integer of 1 to 3. y is an integer of 1 to 5. z is an integer of 0 to 3, provided that 1≦y+z≦5.

[0467] In formula (F1), L 21 is a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond or a carbamate bond.

[0468] In formula (F1), L 22 is an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond or a carbamate bond.

[0469] In formula (F1), L Drepresents a single bond or a hydrocarbylene group having 1 to 20 carbon atoms when x is 1, and represents an (x+1)-valent hydrocarbon group having 1 to 20 carbon atoms when x is 2 or 3, and the hydrocarbylene group and the (x+1)-valent hydrocarbon group may contain at least one bond 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.

[0470] L D The hydrocarbylene group having 1 to 20 carbon atoms represented by the formula (1) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a nonane-1,9-diyl group, a decane-1,10-diyl group, an undecane-1,11-diyl group, and a dodecane-1,12-diyl group. alkanediyl groups having 1 to 20 carbon atoms; cyclic saturated hydrocarbylene groups having 3 to 20 carbon atoms, such as cyclopentanediyl group, cyclohexanediyl group, norbornanediyl group, and adamantanediyl group; unsaturated aliphatic hydrocarbylene groups having 2 to 20 carbon atoms, such as vinylene group and propene-1,3-diyl group; arylene groups having 6 to 20 carbon atoms, such as phenylene group and naphthylene group; and groups obtained by combining these. D The (x+1)-valent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (1) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include groups obtained by further removing one or two hydrogen atoms from the specific examples of the hydrocarbylene group having 1 to 20 carbon atoms described above.

[0471] In formula (F1), Rf 21 and Rf 22 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, provided that at least one of them is a fluorine atom or a trifluoromethyl group.

[0472] In formula (F1), R301 is a hydroxy group, a carboxy group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, -N(R 301A )(R 301B ), -N(R 301C )-C(=O)-R 301D Or -N(R 301C )-C(=O)-OR 301D R 301A and R 301B R are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 301C is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 301D is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms.

[0473] R 301 , R 301A , R 301B and R 301C The saturated hydrocarbyl group having 1 to 6 carbon atoms represented by the formula (I) may be linear, branched or cyclic, and specific examples thereof include alkyl groups having 1 to 6 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl and n-hexyl groups; and cyclic saturated hydrocarbyl groups having 3 to 6 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl groups. 301 Examples of the saturated hydrocarbyl moiety of the saturated hydrocarbyloxy group having 1 to 6 carbon atoms represented by the formula (I) include the same as the specific examples of the saturated hydrocarbyl group described above, and R 301 Examples of the saturated hydrocarbyl moiety of the saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms represented by the following formula include those having 1 to 5 carbon atoms among the specific examples of the saturated hydrocarbyl groups having 1 to 6 carbon atoms mentioned above.

[0474] R 301DThe unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms represented by the formula (I) may be linear, branched, or cyclic, and specific examples thereof include alkenyl groups having 2 to 8 carbon atoms, such as a vinyl group, a propenyl group, a butenyl group, or a hexenyl group; alkynyl groups having 2 to 8 carbon atoms, such as an ethynyl group, a propynyl group, or a butynyl group; and cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 8 carbon atoms, such as a cyclohexenyl group or a norbornenyl group.

[0475] In formula (F1), R 302 represents a saturated hydrocarbylene group having 1 to 20 carbon atoms or an arylene group having 6 to 20 carbon atoms, some or all of the hydrogen atoms of the saturated hydrocarbylene group may be substituted with halogen atoms other than fluorine atoms, and some or all of the hydrogen atoms of the arylene group may be substituted with a substituent selected from a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogen atom, and a hydroxy group.

[0476] R 302 The hydrocarbylene group having 1 to 20 carbon atoms represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include: D Examples of the hydrocarbylene group having 1 to 20 carbon atoms represented by the following formula include the same as those exemplified above.

[0477] R 302Specific examples of the arylene group having 6 to 20 carbon atoms represented by the following formula include a phenylene group, a naphthylene group, a phenanthrenediyl group, and an anthracenediyl group. The hydrocarbyl moiety of the saturated hydrocarbyl group having 1 to 20 carbon atoms and the hydrocarbyloxy group having 1 to 20 carbon atoms, which are substituents of the arylene group, may be any one of linear, branched, and cyclic, and specific examples thereof 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, and an icosyl group; and cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cyclopropylmethyl group, a 4-methylcyclohexyl group, a cyclohexylmethyl group, a norbornyl group, and an adamantyl group. Specific examples of the arylene group having 6 to 14 carbon atoms which is the substituent of the arylene group include a phenylene group, a naphthylene group, a phenanthrenediyl group, and an anthracenediyl group.

[0478] The anion represented by formula (F1) is preferably an anion represented by the following formula (F2). [ka]

[0479] In formula (F2), x, y, z, L 21 , L D and R 301 is the same as above. m2 is an integer of 1 to 4. R 302A is a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, a halogen atom, or a hydroxy group. 302A may be the same as or different from each other.

[0480] Specific examples of the anion represented by formula (F1) include, but are not limited to, those shown below. [ka]

[0481] [ka]

[0482] [ka]

[0483] [ka]

[0484] [ka]

[0485] [ka]

[0486] [ka]

[0487] [ka]

[0488] [ka]

[0489] [ka]

[0490]

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[0491]

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[0492]

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[0493]

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[0494]

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[0495]

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[0496]

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[0497]

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[0498]

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[0499]

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[0500]

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[0501]

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[0502]

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[0503]

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[0504]

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[0505]

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[0506]

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[0507]

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[0508]

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[0509]

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[0510]

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[0511]

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[0512] [ka]

[0513] [ka]

[0514] [ka]

[0515] [ka]

[0516] [ka]

[0517] (F) In other photoacid generators, the cation paired with the anion is preferably a sulfonium cation or an iodonium cation.Specific examples of the sulfonium cation include, but are not limited to, the same as those exemplified as the sulfonium cation represented by formula (cation-1).Specific examples of the iodonium cation include, but are not limited to, the same as those exemplified as the iodonium cation represented by formula (cation-2).

[0518] The acid generated by the other photoacid generator preferably has a pKa of -2.0 or more, more preferably -1.0 or more. The upper limit of the pKa is preferably 2.0. The pKa value is calculated using the pKa DB in the software ACD / Chemsketch ver:9.04 manufactured by Advanced Chemistry Development, Inc.

[0519] When the chemically amplified positive resist composition of the present invention contains (F) other photoacid generator, the content thereof is preferably 1 to 10 parts by mass, more preferably 1 to 5 parts by mass, relative to 80 parts by mass of the base polymer. By containing the other photoacid generator, the amount of acid generated in the exposed area and the dissolution inhibition property of the unexposed area can be appropriately adjusted. (F) Other photoacid generator may be used alone or in combination of two or more.

[0520] The chemically amplified positive resist composition of the present invention preferably contains, in addition to the photoacid generator (A), a polymer-bound photoacid generator containing a repeating unit represented by any one of formulas (B6) to (B9) or (F) another photoacid generator, which allows the deprotection reaction of the base polymer in the resist film to proceed sufficiently, resulting in a good pattern shape and improved resolution.

[0521] [(G) Surfactant] The chemically amplified positive resist composition of the present invention may contain a commonly used surfactant as component (G) in order to improve the coating properties onto a substrate. Many of the surfactants are known as described in International Publication No. 2006 / 121096, JP-A No. 2008-102383, JP-A No. 2008-304590, JP-A No. 2004-115630, and JP-A No. 2005-8766, and the surfactant can be selected with reference to these.

[0522] When the chemically amplified positive resist composition of the present invention contains a surfactant (G), the content thereof is preferably 2 parts by mass or less, more preferably 1 part by mass or less, and the lower limit thereof is preferably 0.01 part by mass or more, relative to 80 parts by mass of the base polymer (B). The surfactant (G) may be used alone or in combination of two or more kinds.

[0523] [Method of 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, exposing the resist film to high-energy rays, and developing the pattern-irradiated resist film using an alkaline developer to obtain a resist pattern.

[0524] The substrate may be, for example, a substrate for manufacturing integrated circuits (Si, SiO, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective film, etc.) or a substrate for manufacturing mask circuits (Cr, CrO, CrON, MoSi2, Si, SiO, SiO2, etc.) The chemically amplified positive resist composition is applied onto the substrate by a method such as spin coating to a film thickness of 0.03 to 2 μm, and this is pre-baked on a hot plate, preferably at 60 to 150° C. for 1 to 20 minutes, more preferably at 80 to 140° C. for 1 to 10 minutes, to form a resist film.

[0525] The resist film is then exposed to a pattern using high-energy radiation, such as ultraviolet radiation, far ultraviolet radiation, excimer laser light (KrF, ArF, etc.), EB, EUV, X-rays, gamma rays, and synchrotron radiation.

[0526] When ultraviolet rays, far ultraviolet rays, excimer laser light, EUV, X-rays, gamma rays, or synchrotron radiation is used as the high-energy radiation, a mask for forming a desired pattern is used, and the exposure dose is preferably 1 to 300 mJ / cm. 2 , more preferably 10 to 200 mJ / cm 2 When EB is used as the high energy beam, the exposure dose is preferably 1 to 300 μC / cm 2 , more preferably 10 to 200 μC / cm 2 The chemically amplified positive resist composition of the present invention is particularly useful for EUV or EB lithography.

[0527] The exposure can be performed by a conventional exposure method, or in some cases by an immersion method in which a liquid is inserted between the mask and the resist film. In that case, a water-insoluble protective film can be used.

[0528] Next, post-exposure baking (PEB) is performed 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.

[0529] Thereafter, the substrate is developed using a developer, preferably an aqueous alkaline solution of 0.1 to 5 mass %, more preferably 2 to 3 mass %, tetramethylammonium hydroxide (TMAH) or the like, for 0.1 to 3 minutes, preferably 0.5 to 2 minutes, by a conventional method such as a dip method, a puddle method or a spray method, to form a desired pattern on the substrate.

[0530] The chemically amplified positive resist composition of the present invention is particularly useful when used under conditions that require high etching resistance, small change in pattern line width even when the time until PEB after exposure is extended, and small LER. The resist composition of the present invention is particularly useful for application to a substrate having a surface made of a material that is prone to pattern peeling or pattern collapse because it is difficult to obtain adhesion of the resist pattern. Examples of such substrates include substrates formed by sputtering a film of a chromium compound containing metal chromium or one or more light elements selected from oxygen, nitrogen, and carbon. The chemically amplified positive resist composition of the present invention is particularly useful for pattern formation using a photomask blank as the substrate. EXAMPLES

[0531] 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. The apparatuses used are as follows. IR: Thermo Fisher Scientific NICOLET 6700 · 1 H-NMR: ECA-500 manufactured by JEOL Ltd. MALDI TOF-MS: JEOL S3000

[0532] [1] Synthesis of onium salts [Example 1-1] Synthesis of PAG-1 [ka]

[0533] (1) Synthesis of intermediate In-1 In a nitrogen atmosphere, 3,5-diiodosalicylic acid (195.0 g), potassium carbonate (105.9 g), and sodium iodide (7.5 g) were suspended in DMF (1000 g) in a reaction vessel. The temperature in the reaction vessel was raised to 50°C, and 1-bromooctane (212.4 g) was added dropwise. After the dropwise addition, the reaction vessel was aged for 12 hours at a temperature of 75°C. After aging, the reaction liquid was cooled and water (1000 g) was added to stop the reaction. The target product was extracted with a solution consisting of hexane (1000 g) and toluene (250 g), and the target product was subjected to a normal aqueous work-up, and the solvent was distilled off to obtain 306.3 g of intermediate In-1 as an oil (yield 100%). Intermediate In-1 was used in the next step without further purification.

[0534] (2) Synthesis of intermediate In-2 Under a nitrogen atmosphere, intermediate In-1 (306.3 g) was dissolved in THF (700 g) in a reaction vessel. The temperature in the reaction vessel was raised to 50°C, and 25% by mass aqueous sodium hydroxide solution (120.0 g) was added dropwise. After the dropwise addition, the reaction vessel was heated to reflux and aged for 12 hours at a temperature of 70°C. After aging, the reaction liquid was cooled, hexane (1000 g) was added, and the target sodium salt was extracted twice with water (1000 g). 20% by mass hydrochloric acid (145.5 g) was added to the aqueous layer after extraction to confirm that the pH was acidic, and the target product was extracted with ethyl acetate (2000 g), and the usual aqueous work-up was performed. After the solvent was distilled off, the product was recrystallized with hexane to obtain 162.3 g of intermediate In-2 as white crystals (yield 65%).

[0535] (3) Synthesis of onium salt PAG-1 In a nitrogen atmosphere, intermediate In-2 (10.1 g) and DMF (0.02 g) were dissolved in methylene chloride (40 g) in a reaction vessel. Then, oxalyl chloride (3.1 g) was added dropwise at room temperature. After the addition, the temperature in the reaction vessel was raised to 40°C, and the mixture was aged for 4 hours to prepare an acid chloride. After aging, the reaction solution was distilled to obtain 12.6 g of acid chloride. Then, the acid chloride (12.6 g), SM-2 (10.6 g), and 4-dimethylaminopyridine (0.3 g) were suspended in acetonitrile (60 g). The temperature in the reaction vessel was raised to 50°C, and a solution consisting of triethylamine (2.6 g) and acetonitrile (10 g) was added dropwise. After the addition, the temperature in the reaction vessel was raised to 70°C, and the mixture was aged for 12 hours. After aging, the reaction solution was cooled, and water (50 g) was added to stop the reaction. Thereafter, the target substance was extracted with methylene chloride, and a normal aqueous work-up was carried out, and the solvent was distilled off to obtain 17.0 g of the onium salt PAG-1 as an oily substance (yield 86%).

[0536] The IR spectrum data and TOF-MS results of PAG-1 are shown below. The nuclear magnetic resonance spectrum ( 1 The results of H-NMR / DMSO-d6) are shown in Figure 1. IR(D-ATR): ν= 3058, 3021, 2926, 2855, 1749, 1593, 1583, 1565, 1537, 1465, 1440, 1383, 1322, 1271, 1253, 1230, 1185, 1145, 1085, 1061, 1040, 997, 912, 885, 815, 765, 733, 714, 664, 639, 622, 593, 562, 526, 487, 439 cm -1 . MALDI TOF-MS: POSITIVE M + 277(C 18 H 13 OS + equivalent) NEGATIVE M - 713(C 25 H 31 I2O6S- equivalent)

[0537] [Examples 1-2 to 1-10] Synthesis of PAG-2 to PAG-10 Using the corresponding raw materials and known organic synthesis reactions, onium salts PAG-2 to PAG-10 represented by the following formulas were synthesized. [ka]

[0538] [ka]

[0539] The IR spectrum data and TOF-MS results of PAG-2 are shown below. The nuclear magnetic resonance spectrum ( 1 The results of H-NMR / DMSO-d6) are shown in Figure 2. IR(D-ATR): ν= 3063, 2927, 2856, 1737, 1593, 1574, 1534, 1466, 1440, 1371, 1322, 1269, 1251, 1148, 1100, 1041, 968, 911, 886, 761, 706, 682, 658, 636, 617, 562, 526, 488 cm -1 . MALDI TOF-MS: POSITIVE M + 277(C 18 H 13 OS + equivalent) NEGATIVE M - 713(C 25 H 31 I2O6S - equivalent)

[0540] The IR spectrum data and TOF-MS results of PAG-3 are shown below. The nuclear magnetic resonance spectrum ( 1 The results of H-NMR / DMSO-d6) are shown in Figure 3. IR(D-ATR): ν= 3059, 3020, 2927, 2857, 1729, 1605, 1581, 1510, 1465, 1441, 1392, 1318, 1271, 1250, 1216, 1168, 1150, 1088, 1066, 1040, 966, 910, 886, 846, 816, 765, 733, 716, 682, 655, 632, 587, 561, 524, 487 cm -1 . MALDI TOF-MS: POSITIVE M + 277(C 18 H 13 OS + equivalent) NEGATIVE M - 461(C 25 H 33 O6S - equivalent)

[0541] [2] Synthesis of base polymer [Synthesis Example] Synthesis of base polymers (P-1 to P-6) Each monomer was combined according to a known recipe and copolymerized in a solvent, the reaction solution was poured into hexane, and the precipitated solid was washed with hexane, isolated, and dried to obtain base polymers (P-1 to P-6) with the compositions shown below. The compositions of the obtained base polymers were as follows: 1 H-NMR, 13 Mw and Mw / Mn were confirmed by C-NMR and GPC (solvent: THF, standard: polystyrene). [ka]

[0542] [ka]

[0543] [3] Preparation of chemically amplified positive resist composition [Examples 2-1 to 2-50, Comparative Examples 1-1 to 1-31] Chemically amplified positive resist compositions were prepared by dissolving each component in an organic solvent according to the compositions 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.

[0544] [Table 1]

[0545] [Table 2]

[0546] [Table 3]

[0547] In Tables 1 to 3, the comparative photoacid generators cPAG-1 to cPAG-6, quenchers Q-1 to Q-4, and fluorine atom-containing polymers FP-1 to FP-5 are as follows.

[0548] [ka]

[0549] [ka]

[0550] [ka]

[0551] [4] EB lithography evaluation [Examples 3-1 to 3-50, Comparative Examples 2-1 to 2-31] Each chemically amplified positive resist composition (R-1 to R-50, CR-1 to CR-31) was spin-coated using ACT-M (Tokyo Electron Ltd.) onto a reflective mask blank for EUV exposure masks, which was a 6-inch-side low-thermal expansion glass substrate with a 284-nm-thick Mo / Si 40-layer multilayer reflective film, a 3.5-nm-thick Ru film as a protective film, a 70-nm-thick TaN film as an absorbing layer, and a 6-nm-thick CrN film as a hard mask. The mask blank was prebaked on a hot plate at 110°C for 600 seconds to produce a resist film with a thickness of 80 nm. The thickness of the obtained resist film was measured using an optical measuring instrument Nanospec (Nanometrics). Measurements were performed at 81 points on the surface of the blank substrate, excluding the outer edge portion from the outer periphery to the inside by 10 mm, and the average thickness and thickness range were calculated.

[0552] Furthermore, 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 mass % TMAH aqueous solution to obtain a positive pattern.

[0553] The obtained resist patterns were evaluated as follows. The prepared patterned mask blanks were observed with an overhead 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 The minimum dimension at the exposure dose at which a 200 nm isolated space is resolved at a ratio of 9:1 was taken as the resolution (limit IS resolution), and the LER of 200 nmLS 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.

[0554] [Table 4]

[0555] [Table 5]

[0556] [Table 6]

[0557] The results shown in Tables 4 to 6 demonstrate that the photoacid generators comprising the onium salts of the present invention, the chemically amplified positive resist compositions using the same, and the methods for forming resist patterns are useful for the production of semiconductor devices, in particular for photolithography in the processing of transmissive and reflective photomask blanks.

Claims

1. An onium salt represented by the following formula (A): 【Chemistry 1】 (In the formula, n1 is 0 or 1. n2 is 1, 2, or 3. n3 is an integer from 0 to 4. n4 is an integer from 0 to 4. However, when n1 is 0, 1≦n2+n3+n4≦5, and when n1 is 1, 1≦n2+n3+n4≦7. n5 is 0, 1 or 2. n6 is an integer from 0 to 4 when n5 is 0, an integer from 0 to 6 when n5 is 1, and an integer from 0 to 8 when n5 is 2. n7 is an integer from 0 to 4 when n5 is 0, an integer from 0 to 6 when n5 is 1, and an integer from 0 to 8 when n5 is 2. However, n6+n7 is 0 to 4 when n5 is 0, 0 to 6 when n5 is 1, and 0 to 8 when n5 is 2. R alk is an alkyl group having 6 to 18 carbon atoms or a fluorinated alkyl group having 4 to 18 carbon atoms. alk When R is an alkyl group having 6 to 18 carbon atoms, the alkyl group has at least one linear structure having 6 or more carbon atoms. alk is a fluorinated alkyl group having 4 to 18 carbon atoms, the fluorinated alkyl group is -CF 2 - and - CF 3 In addition, the alkyl group and the fluorinated alkyl group each have at least two groups selected from the group consisting of -CH 2 A part of the - may be substituted with an ether bond or a carbonyl group, and the terminal or carbon-carbon bond may contain a ring structure selected from a cyclopentane ring, a cyclohexane ring, an adamantane ring, a norbornyl ring and a benzene ring. R 1 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom other than iodine atom or a heteroatom. R 2 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, and when n7 is 2 or more, a plurality of R 2 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R F1 is a fluorine atom, a fluorinated alkyl group having 1 to 6 carbon atoms, a fluorinated alkoxy group having 1 to 6 carbon atoms, or a fluorinated thioalkoxy group having 1 to 6 carbon atoms. When n6 is 2 or more, each R F1 may be the same as or different from each other. L A , L B and L C are each independently a single bond, an ether bond, an ester bond, a sulfonate ester 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. The onium salt according to claim 1, which is represented by the following formula (A1): 【Chemistry 2】 (In the formula, n1 to n4, n6, n7, R alk , R 1 , R 2 , R F1 , L A , L B , L C , X L and Z + is the same as above.)

3. The onium salt according to claim 2, which is represented by the following formula (A2): 【Chemistry 3】 (In the formula, n1 to n4, n6, n7, R alk , R 1 , R 2 , R F1 , L A , L C , X L and Z + is the same as above.)

4. Z + The onium salt according to claim 1, wherein is a sulfonium cation represented by the following formula (category-1) or an iodonium cation represented by the following formula (category-2). 【Chemistry 4】 (In the formula, R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. ct1 and R ct2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.)

5. A photoacid generator comprising the onium salt according to claim 1.

6. A chemically amplified positive resist composition comprising the photoacid generator according to claim 5.

7. 7. The chemically amplified positive resist composition according to claim 6, further comprising a base polymer which contains a polymer which is decomposed by the action of an acid and has increased solubility in an alkaline developer.

8. 8. The chemically amplified positive resist composition according to claim 7, wherein the polymer contains a repeating unit represented by the following formula (B1): 【Chemistry 5】 (In the formula, a1 is 0 or 1. a2 is an integer from 0 to 2. a3 is an integer that satisfies 0≦a3≦5+2(a2)−a4. a4 is an integer from 1 to 3. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 11 is a halogen atom, a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom. A 1 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the —CH 2 A part of - may be replaced by -O-.

9. 8. The chemically amplified positive resist composition according to claim 7, wherein the polymer contains a repeating unit represented by the following formula (B2-1): 【Chemistry 6】 (In the formula, b1 is 0 or 1. b2 is an integer from 0 to 2. b3 is an integer satisfying 0≦b3≦5+2(b2)−b4. b4 is an integer from 1 to 3. b5 is 0 or 1. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 12 is a halogen atom, a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom. A 2 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the —CH 2 A part of - may be substituted with -O-. When b4 is 1, X is an acid labile group. When b4 is 2 or 3, X is each independently a hydrogen atom or an acid labile group, provided that at least one X is an acid labile group.

10. 8. The chemically amplified positive resist composition according to claim 7, wherein the polymer contains a repeating unit represented by the following formula (B2-2): 【Chemistry 7】 (In the formula, c1 is an integer from 0 to 2. c2 is an integer from 0 to 2. c3 is an integer from 0 to 5. c4 is an integer from 0 to 2. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 13 and R 14 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom; R 13 and R 14 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 15 each independently represents a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, or a fluorinated alkoxy group having 1 to 5 carbon atoms. R 16 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. A 3 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-O-A 31 - is. 31 is an aliphatic hydrocarbylene group having 1 to 20 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring, or a phenylene group or naphthylene group. * represents a bond to a carbon atom of the main chain.)

11. 8. The chemically amplified positive resist composition according to claim 7, wherein the polymer contains at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (B3), a repeating unit represented by the following formula (B4), and a repeating unit represented by the following formula (B5): 【Chemistry 8】 (In the formula, d is an integer of 0 to 6. e is an integer of 0 to 4. f1 is 0 or 1. f2 is an integer of 0 to 2. f3 is an integer of 0 to 5. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 17 and R 18 each independently represents 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. R 19 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 f2 is 1 or 2, it may be a hydroxy group. A 4 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the —CH 2 A part of - may be replaced by -O-.

12. 8. The chemically amplified positive resist composition according to claim 7, wherein the polymer contains at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (B6), a repeating unit represented by the following formula (B7), a repeating unit represented by the following formula (B8), and a repeating unit represented by the following formula (B9): 【Chemistry 9】 (In the formula, R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1 is a single bond or a phenylene group. X 2 teeth,* 1 -C(=O)-O-X 21 -, * 1 -C(=O)-NH-X 21 -or* 1 -O-X 21 - is. 21 is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group.* 1 , X 1 Represents a bond with . X 3 each independently represents a single bond, a phenylene group, a naphthylene group, or * 2 -C(=O)-O-X 31 - is. 31 is an aliphatic hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the aliphatic hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring. 2 represents a bond to a carbon atom in the main chain. X 4 each independently represents a single bond, * 3 -X 41 -C(=O)-O-, * 3 -C(=O)-NH-X 41 -or* 3 -O-X 41 - is. 41 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 3 , X 3 Represents a bond with . X 5 each independently represents a single bond, * 4 -X 51 -C(=O)-O-, * 4 -C(=O)-NH-X 51 -or* 4 -O-X 51 - is. 51 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 4 , X 4 Represents a bond with . X 6 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, * 2 -C(=O)-O-X 61 -, * 2 -C(=O)-N(H)-X 61 -or* 2 -O-X 61 - is. 61 is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group.* 2 represents a bond to a carbon atom in the main chain. R 21 and R 22 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 21 and R 22 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. L 1 is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate ester bond, a carbonate bond or a carbamate bond. Rf 1 and Rf 2 are each independently a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 3 and Rf 4 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 5 and Rf 6 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 5 and Rf 6 cannot simultaneously become a hydrogen atom. M - is a non-nucleophilic counterion. A + is an onium cation. g1 and g2 each independently represent an integer of 0 to 3.

13. 7. The chemically amplified positive resist composition according to claim 6, further comprising an organic solvent.

14. The chemically amplified positive resist composition according to claim 6, further comprising a fluorine atom-containing polymer which contains at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (D1), a repeating unit represented by the following formula (D2), a repeating unit represented by the following formula (D3), and a repeating unit represented by the following formula (D4), and which may further contain at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (D5) and a repeating unit represented by the following formula (D6): 【Chemistry 10】 (In the formula, j1 is an integer of 1 to 3. j2 is an integer satisfying 0≦j2≦5+2(j3)−j1. j3 is 0 or 1. k is an integer of 1 to 3. R B each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R C are each independently a hydrogen atom or a methyl group. R 101 , R 102 , R 104 and R 105 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 103 , R 106 , R 107 and R 108 are each independently a hydrogen atom, a hydrocarbyl group having 1 to 15 carbon atoms, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid labile group; R 103 , R 106 , R 107 and R 108 When is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bonds. R 109 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 the carbon-carbon bonds. R 110 is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a heteroatom-containing group between its carbon-carbon bonds. R 111 is a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, and the —CH 2 A part of the - may be substituted with an ester bond or an ether bond. Z 1 is a (k+1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (k+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. Z 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. Z 3 is a single bond, -O-, *-C(=O)-O-Z 31 -Z 32 - or *-C(=O)-NH-Z 31 -Z 32 - is. 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. * represents a bond to a carbon atom in the main chain.)

15. 7. The chemically amplified positive resist composition according to claim 6, further comprising a quencher.

16. 7. The chemically amplified positive resist composition according to claim 6, further comprising a photoacid generator other than the photoacid generator according to claim 5.

17. 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 claims 6 to 16; exposing the resist film to high-energy rays; and developing the exposed resist film using an alkaline developer to obtain a resist pattern.

18. 18. The method for forming a resist pattern according to claim 17, wherein the high-energy radiation is extreme ultraviolet radiation or an electron beam.

19. 18. The method for forming a resist pattern according to claim 17, wherein the outermost surface of the substrate is made of a material containing chromium.

20. 18. The method of forming a resist pattern according to claim 17, wherein the substrate is a photomask blank.

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