Acetal modifier, polymer, chemically amplified positive resist composition, and resist pattern forming method

Abstract

The invention relates to an acetal modifier, a polymer, a chemically amplified positive resist composition and a resist pattern forming method. The present invention provides a chemically amplified positive resist composition, and provides an acetal modifier used for manufacturing a base polymer used in the resist composition, a polymer modified by the acetal modifier, and a resist pattern forming method using the chemically amplified positive resist composition. Acetal modifier having oxygen atom or sulfur atom-containing cyclosaturated heterocyclic ring for imparting protecting group to aliphatic or aromatic hydroxyl group, said acetal modifier containing aromatic hydroxyl group in side chain represented by formula (AL-1) or (AL-2) The present invention relates to a polymer which is a repeating unit A1 having a structure protected by an acid-labile group and which is deprotected to be alkali-soluble due to the action of an acid, and a chemically amplified positive resist composition containing a base polymer containing the polymer. # imgabs0 #

Description

Technical Field

[0001] The invention relates to an acetal modifier, a polymer, a chemically amplified positive resist composition and a resist pattern forming method. Background Art

[0002] In recent years, with the high integration of integrated circuits, it is required to form finer patterns. For processing patterns below 0.2μm, chemically amplified resist compositions using acids as catalysts are mainly used. In addition, high-energy rays such as ultraviolet rays, far ultraviolet rays, extreme ultraviolet rays (EUV), and electron beams (EB) are used as exposure sources at this time. However, in EB lithography, which is particularly used as an ultra-fine processing technology, the processing method of blank photomasks when making photomasks for semiconductor manufacturing has become indispensable.

[0003] In EB lithography, the drawing performed by EB is generally performed without using a mask. If it is a positive type, a method of sequentially irradiating a minute area of ​​EB to the portion other than the area to be retained of the resist film is adopted. If it is a negative type, a method of sequentially irradiating a minute area of ​​EB to the area to be retained of the resist film is adopted. That is, the entire area of ​​the processed surface is scanned, which is divided into fine areas, so it is more time-consuming than batch exposure using a photomask. In order not to reduce the production capacity, a high-sensitivity resist film is required. In particular, in the processing of blank photomasks for important purposes, some of them have surface materials that are easy to affect the pattern shape of chemically amplified resist films such as chromium compound films such as chromium oxide that have been formed on the photomask substrate. In order to maintain high resolution and the shape after etching, it is not dependent on the type of substrate. Keeping the pattern outline of the resist film rectangular is also one of the important properties. In addition, a small line edge roughness (LER) is also considered to be one of the important properties. In recent years, in order to achieve miniaturization, multi-beam mask writing (MBMW) drawing processing is sometimes used in the processing of blank masks. At this time, the resist composition uses a low-sensitivity resist composition (high dose range) that is beneficial for roughness, and the optimization of this high dose range of resist composition is also given attention.

[0004] Various improvements have been made to control sensitivity and pattern profiles by utilizing the selection, combination, and processing conditions of materials used in resist compositions. One of these improvements is to suppress the diffusion of acid, which has a significant impact on the resolution of the resist film. During photomask processing, it is hoped that the shape of the resist pattern obtained will not change due to the time between exposure and heating. A major cause of the time-dependent change in the shape of the resist pattern is the diffusion of acid generated by exposure. This acid diffusion problem is not limited to photomask processing, but also has a significant impact on sensitivity and resolution in general resist compositions, so many people have explored it.

[0005] Patent Documents 1 and 2 describe examples of reducing LER by increasing the volume of acid generated from an acid generator to suppress acid diffusion. However, these acid generators are not ideal for suppressing acid diffusion, and it is desired to develop an acid generator with a smaller acid diffusion.

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

[0007] There are many polymers with an aromatic skeleton having an acidic side chain, such as polyhydroxystyrene, which are useful as base polymers for KrF lithography resist compositions, but they show strong absorption for light with a wavelength of around 200 nm, so they are not used as base polymers for ArF lithography resist compositions. However, they are important materials for obtaining high etching resistance in EB lithography resist compositions and EUV lithography resist compositions, which are powerful technologies for forming patterns with a smaller processing limit than those prepared using ArF excimer lasers.

[0008] For the base polymer of positive EB photolithography resist composition and EUV photolithography resist composition, a material that is soluble in an alkaline developer is mainly used, which uses an acid generated by irradiating a photoacid generator with high-energy radiation as a catalyst to deprotect the acid-labile group that masks the acidic functional group of the phenol side chain of the base polymer. The acid-labile group may be a tertiary alkyl group or a tert-butoxycarbonyl group, or an acetal group having a relatively low activation energy (Patent Documents 4 to 8).

[0009] Although the acetal group has the advantage of obtaining a highly sensitive resist film, the MBMW drawing process of EB lithography, which is used to make advanced photomasks finer than the 10nm node, draws in a thin film range such as a resist film thickness of less than 100nm and a high-dose range with a large irradiation energy. Therefore, when the reactivity and structural volume of the acetal are large, deprotection reactions will occur even in the unexposed portions of the resist film, and residues will remain even in the exposed portions. In particular, positive resist compositions are considered to have important problems such as isolated pitch resolution, LER degradation, and defect generation.

[0010] In the development step of photomask manufacturing, it is known that the phenomenon of so-called development load occurs, in which the pattern finished size of the dense pattern area and the loose pattern area on the photomask is different. That is, due to the development load, the finished size of the pattern will be unevenly distributed in response to the surrounding pattern distribution. As for the reasons, for example, the energy difference of EB causes a difference in the release reaction when the acid is generated, and the dissolution rate of the dense pattern drawing part to the alkaline developer is different. As for the improvement method, Patent Document 9 has a method for adjusting the incident dose in the EB drawing device and irradiating EB to draw the pattern on the photomask in order to correct the development load. However, the known correction method is not corrected by fully considering the development load. Therefore, the correction accuracy of the development load in the previous correction method is poor. In order to solve this problem, the drawing method when drawing the resist film and the method of improving the development method after patterning have been developed, but in the advanced generation, it is not perfect to make the dense and fine patterns evenly distributed. It is hoped that there will be an improvement in the resist composition that can achieve high resolution and reduce the development load and residue defects in the advanced generation.

[0011] Prior art literature

[0012] Patent Literature

[0013] [Patent Document 1] Japanese Patent Application Publication No. 2009-53518

[0014] [Patent Document 2] Japanese Patent Application Publication No. 2010-100604

[0015] [Patent Document 3] Japanese Patent Application Publication No. 2011-22564

[0016] [Patent Document 4] Japanese Patent No. 3981830

[0017] [Patent Document 5] Japanese Patent No. 5385017

[0018] [Patent Document 6] International Publication No. 2019 / 167419

[0019] [Patent Document 7] Japanese Patent No. 6987873

[0020] [Patent Document 8] Japanese Patent No. 5696254

[0021] [Patent Document 9] Japanese Patent Application Publication No. 2007-150243

[0022] [Patent Document 10] Japanese Patent No. 5443548

[0023] [Patent Document 11] Japanese Patent No. 6281244 Summary of the invention

[0024] [Problems to be solved by the invention]

[0025] The present invention is to solve the above-mentioned problems, and its purpose is to provide a chemically amplified positive resist composition that can form a resist film having extremely high isolated pitch resolution, small LER, excellent rectangularity, suppressed influence of development load and residue defects, and high etching resistance and suppressed pattern collapse, and to provide an acetal modifier for a base polymer used in the manufacture of the resist composition, a polymer modified by the acetal modifier, and a resist pattern forming method using the chemically amplified positive resist composition.

[0026] [Methods for solving problems]

[0027] The inventors of the present application have made great efforts to study in order to achieve the above-mentioned purpose, and as a result, they have found that by using a resist composition containing a base polymer having an acid-labile group derived from an acetal modifier having a cyclic saturated heterocycle containing an oxygen atom or a sulfur atom, good isolated spacing resolution, pattern shape and LER can be exhibited even in a high dose range, and a pattern in which the influence of development load and residue defects is suppressed can be obtained, thereby completing the present invention.

[0028] That is, the present invention provides the following acetal modifier, polymer, chemically amplified positive resist composition and resist pattern forming method.

[0029] 1. An acetal modifier which provides a group having a cyclic saturated heterocyclic ring containing an oxygen atom or a sulfur atom as a protective group for an aliphatic or aromatic hydroxyl group.

[0030] 2. The acetal modifier according to 1., which provides a group that serves as a protecting group for an aromatic hydroxyl group.

[0031] 3. The acetal modifier according to 1. or 2., which is a compound represented by the following formula (AC-1) or (AC-2),

[0032] [Chemistry 1]

[0033]

[0034] In the formula, R L1 , R L2 , R L5 , R L6 and R L7 are each independently a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms. L1 With R L2 They can also bond to each other and to the carbon atoms to which they are bonded to form a ring, R L5 ~R L7Any two of them may also be bonded to each other and together with the carbon atoms to which they are bonded form a ring.

[0035] R L3 , R L4 , R L8 and R L9 are each independently a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom. L3 With R L4 They can also bond to each other and to the carbon atoms to which they are bonded to form a ring, R L8 With R L9 They may also be bonded to each other and to the carbon atoms to which they are bonded to form a ring.

[0036] W 1 Each is independently a group containing a cyclic saturated heterocyclic ring containing an oxygen atom or a sulfur atom.

[0037] X is a chlorine atom, a bromine atom or an iodine atom.

[0038] m1 and m2 are each independently an integer of 0-3.

[0039] 4. A polymer comprising a repeating unit A1 having a structure in which a side chain aromatic hydroxyl group is protected by an acid-labile group represented by the following formula (AL-1) or (AL-2), which is deprotected by an acid to become alkali-soluble,

[0040] [Chemistry 2]

[0041]

[0042] In the formula, R L1 , R L2 , R L5 , R L6 and R L7 are each independently a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms. L1 With R L2 They can also bond to each other and to the carbon atoms to which they are bonded to form a ring, R L5 ~R L7 Any two of them may also be bonded to each other and together with the carbon atoms to which they are bonded form a ring.

[0043] R L3 , R L4 , R L8 and R L9 are each independently a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom. L3 With R L4 They can also bond to each other and to the carbon atoms to which they are bonded to form a ring, R L8 With R L9They may also be bonded to each other and to the carbon atoms to which they are bonded to form a ring.

[0044] W 1 Each is independently a group containing a cyclic saturated heterocyclic ring containing an oxygen atom or a sulfur atom.

[0045] m1 and m2 are each independently an integer of 0-3.

[0046] The chain line represents the atomic bond with the oxygen atom of the aforementioned aromatic hydroxyl group.

[0047] 5. The polymer according to 4., wherein the repeating unit A1 is represented by the following formula (A1),

[0048] [Chemistry 3]

[0049]

[0050] In the formula, a1 is 0 or 1. a2 is an integer of 0 to 4 when a1=0, and an integer of 0 to 6 when a1=1. a3 is an integer of 1 to 3. However, when a1=0, 1≤a2+a3≤5, and when a1=1, 1≤a2+a3≤7.

[0051] R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0052] X 1 It is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is an atomic bond between the carbon atoms of the main chain.

[0053] X 2 It is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate bond, a carbonate bond or a carbamate bond.

[0054] A 1 It is a single bond or a saturated alkylene group having 1 to 10 carbon atoms, and a part of -CH2- in the saturated alkylene group may be substituted by -O-.

[0055] R 1 It is a halogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom.

[0056] R is an acid-labile group represented by the formula (AL-1) or (AL-2).

[0057] 6. The polymer of 4. or 5. further comprises a repeating unit A2 containing a phenolic hydroxyl group represented by the following formula (A2):

[0058] [Chemistry 4]

[0059]

[0060] In the formula, b1 is 0 or 1. b2 is an integer of 0 to 4 when b1=0, and an integer of 0 to 6 when b1=1. b3 is an integer of 1 to 3. However, when b1=0, 1≤b2+b3≤5, and when b1=1, 1≤b2+b3≤7.

[0061] R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0062] X 3 It is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is an atomic bond between the carbon atoms of the main chain.

[0063] X 4 It is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate bond, a carbonate bond or a carbamate bond.

[0064] A 2 It is a single bond or a saturated alkylene group having 1 to 10 carbon atoms, and a part of -CH2- in the saturated alkylene group may be substituted by -O-.

[0065] R 2 It is a halogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom.

[0066] 7. The polymer according to 6., wherein the repeating unit A2 is represented by the following formula (A2-1),

[0067] [Chemistry 5]

[0068]

[0069] In the formula, R A and b3 are the same as described above.

[0070] 8. The polymer according to any one of 4. to 7., further comprising at least one selected from the group consisting of a repeating unit represented by the following formula (A3-1) and a repeating unit represented by the following formula (A3-2),

[0071] [Chemistry 6]

[0072]

[0073] In the formula, c1 is 0 or 1. c2 is an integer from 0 to 2. c3 is an integer satisfying 0≤c3≤5+2(c2)-c4. c4 is an integer from 1 to 3. c5 is 0 or 1.

[0074] d1 is an integer of 0 to 2. d2 is an integer of 0 to 2. d3 is an integer of 0 to 5. d4 is an integer of 0 to 2.

[0075] R A Each is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0076] A 3 It is a single bond or a saturated alkylene group having 1 to 10 carbon atoms, wherein -CH2- of the saturated alkylene group may be substituted by -O-.

[0077] A 4 is a single bond, phenylene, naphthylene or *-C(=O)-OA 41 -.A 41 It may also contain a hydroxyl group, an ether bond, an ester bond, or an aliphatic alkylene group having 1 to 20 carbon atoms in a lactone ring, or a phenylene group or a naphthylene group. * is an atomic bond between the carbon atoms of the main chain.

[0078] R 3 It is a halogen atom, a saturated hydrocarbon group having 1 to 6 carbon atoms which may be substituted by a halogen atom, a saturated hydrocarbonoxy group having 1 to 6 carbon atoms which may be substituted by a halogen atom, or a saturated hydrocarboncarbonyloxy group having 2 to 8 carbon atoms which may be substituted by a halogen atom.

[0079] R 4 and R 5 Each independently represents a hydrocarbon group having 1 to 10 carbon atoms which may contain a hetero atom, R 4 With R 5 They may also be bonded to each other and to the carbon atoms to which they are bonded to form a ring.

[0080] R 6 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.

[0081] R 7 Each independently represents a hydrocarbon group having 1 to 10 carbon atoms which may contain a hetero atom.

[0082] X A When c4 is 1, it is an acid-labile group, and when c4 is 2 or more, it is a hydrogen atom or an acid-labile group, but at least one of them is an acid-labile group.

[0083] 9. The polymer according to any one of 4 to 8, further comprising at least one selected from the group consisting of a repeating unit represented by the following formula (B1), a repeating unit represented by the following formula (B2), and a repeating unit represented by the following formula (B3),

[0084] [Chemistry 7]

[0085]

[0086] In the formula, e and f are each independently an integer of 0 to 4. g1 is an integer of 0 to 5. g2 is an integer of 0 to 2.

[0087] R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0088] X 5It is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is an atomic bond between the carbon atoms of the main chain.

[0089] A 5 It is a single bond or a saturated alkylene group having 1 to 10 carbon atoms, and a part of -CH2- in the saturated alkylene group may be substituted by -O-.

[0090] R 11 and R 12 Each is independently a hydroxyl group, a halogen atom, a saturated hydrocarbon carbonyloxy group having 2 to 8 carbon atoms which may be substituted by a halogen atom, a saturated hydrocarbon group having 1 to 8 carbon atoms which may be substituted by a halogen atom, or a saturated hydrocarbonoxy group having 1 to 8 carbon atoms which may be substituted by a halogen atom.

[0091] R 13 It is an acetyl group, a saturated hydrocarbon group having 1 to 20 carbon atoms, a saturated hydrocarbon oxy group having 1 to 20 carbon atoms, a saturated hydrocarbon carbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbon oxyalkyl group having 2 to 20 carbon atoms, a saturated hydrocarbon thialkyl group having 2 to 20 carbon atoms, a halogen atom, a nitro group or a cyano group. When g2 is 1 or 2, it may also be a hydroxyl group.

[0092] 10. The polymer according to any one of 4 to 9, further comprising at least one selected from the group consisting of a repeating unit represented by the following formula (C1), a repeating unit represented by the following formula (C2), a repeating unit represented by the following formula (C3), and a repeating unit represented by the following formula (C4),

[0093] [Chemistry 8]

[0094]

[0095] In the formula, R A Each is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0096] Z 1 It is a single bond or a phenylene group.

[0097] Z 2 for* 1 -C(=O)-OZ 21 -, * 1 -C(=O)-NH-Z 21 -or* 1 -OZ 21 -.Z 21 It is an aliphatic alkylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining them, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. 1 Represents and Z 1 of atomic bonds.

[0098] Z 3 Each independently represents a single bond, phenylene, naphthylene or *2 -C(=O)-OZ 31 -.Z 31 It is an aliphatic alkylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, and the aliphatic alkylene group may also contain a hydroxyl group, an ether bond, an ester bond or a lactone ring. 2 Represents the atomic bonds between the carbon atoms in the main chain.

[0099] Z 4 Each is independently a single bond, * 3 -Z 41 -C(=O)-O-,* 3 -C(=O)-NH-Z 41 -or* 3 -OZ 41 -.Z 41 It is a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom. 3 For and Z 3 of atomic bonds.

[0100] Z 5 Each is independently a single bond, * 4 -Z 51 -C(=O)-O-,* 4 -C(=O)-NH-Z 51 -or* 4 -OZ 51 -.Z 51 It is a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom. 4 Represents and Z 4 of atomic bonds.

[0101] Z 6 is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, phenylene substituted with trifluoromethyl, * 2 -C(=O)-OZ 61 -, * 2 -C(=O)-N(H)-Z 61 -or* 2 -OZ 61 -.Z 61 It is an aliphatic alkylene 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 hydroxyl group. 2 Represents the atomic bonds between the carbon atoms in the main chain.

[0102] *Indicates atomic bonds to carbon atoms in the main chain.

[0103] R 31 and R 32 are each independently a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom.31 and R 32 They may also bond to each other and to the sulfur atom to which they are bonded to form a ring.

[0104] L is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate bond, a carbonate bond, or a carbamate bond.

[0105] R 1 and Rf 2 Each independently represents a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms.

[0106] R 3 and Rf 4 Each is independently a hydrogen atom, a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms.

[0107] R 5 and Rf 6 Each independently represents a hydrogen atom, a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms. 5 and Rf 6 At the same time it becomes a hydrogen atom.

[0108] M - It is a non-nucleophilic relative ion.

[0109] A + It is an onium cation.

[0110] k1 and k2 are each independently an integer of 0-3.

[0111] 11. A chemically amplified positive resist composition comprising a base polymer comprising the polymer according to any one of 4. to 10.

[0112] 12. The chemically amplified positive resist composition of 11. further contains an organic solvent.

[0113] 13. The chemically amplified positive resist composition of 11. or 12. further contains a photoacid generator that generates an acid with an acid strength (pKa) of -2.0 or more.

[0114] 14. The chemically amplified positive resist composition of 13., wherein the photoacid generator contains an anion represented by the following formula (P1):

[0115] [Chemistry 9]

[0116]

[0117] In the formula, m1 is 0 or 1. p is an integer of 1 to 3. q is an integer of 1 to 5. r is an integer of 0 to 3.

[0118] L 1It is a single bond, an ether bond, an ester bond, a sulfonate bond, a carbonate bond or a carbamate bond.

[0119] L 2 It is an ether bond, an ester bond, a sulfonate bond, a carbonate bond or a carbamate bond.

[0120] L A When p is 1, it is a single bond or an alkylene group having 1 to 20 carbon atoms; when p is 2 or 3, it is a (p+1)-valent hydrocarbon group having 1 to 20 carbon atoms. The alkylene group and the (p+1)-valent hydrocarbon group may also contain at least one selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxyl group and a carboxyl group.

[0121] R 1 and Rf 2 Each is independently a hydrogen atom, a fluorine atom or a trifluoromethyl group, and at least one is a fluorine atom or a trifluoromethyl group.

[0122] R 101 is a hydroxyl group, a carboxyl group, a saturated hydrocarbon group having 1 to 6 carbon atoms, a saturated hydrocarbon oxy group having 1 to 6 carbon atoms, a saturated hydrocarbon carbonyloxy group having 2 to 6 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, -N(R 101A )(R 101B )、-N(R 101C )-C(=O)-R 101D or -N(R 101C )-C(=O)-OR 101D . R 101A and R 101B Each R is independently a hydrogen atom or a saturated hydrocarbon group having 1 to 6 carbon atoms. 101C is a hydrogen atom or a saturated hydrocarbon group having 1 to 6 carbon atoms. 101D It is a saturated hydrocarbon group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbon group having 2 to 8 carbon atoms.

[0123] R 102 It is a saturated alkylene group having 1 to 20 carbon atoms or an arylene group having 6 to 20 carbon atoms, and a part or all of the hydrogen atoms of the saturated alkylene group may be substituted by halogen atoms other than fluorine atoms, and a part or all of the hydrogen atoms of the arylene group may be substituted by a substituent selected from a saturated alkyl group having 1 to 20 carbon atoms, a saturated alkoxy group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogen atom and a hydroxyl group.

[0124] 15. The chemically amplified positive resist composition according to any one of 11. to 14. further comprises a quencher.

[0125] 16. The chemically amplified positive resist composition according to any one of 11. to 15., further comprising a fluorine-containing polymer, wherein the fluorine-containing polymer comprises 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),

[0126] [Chemistry 10]

[0127]

[0128] In the formula, R B Each is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0129] R 301 , R 302 , R 304 and R 305 Each is independently a hydrogen atom or a saturated hydrocarbon group having 1 to 10 carbon atoms.

[0130] R 303 , R 306 , R 307 and R 308 are each independently a hydrogen atom, a hydrocarbon group having 1 to 15 carbon atoms, a fluorinated hydrocarbon group having 1 to 15 carbon atoms, or an acid-labile group, and R 303 , R 306 , R 307 and R 308 In the case of a hydrocarbon group or a fluorinated hydrocarbon group, an ether bond or a carbonyl group may be inserted between carbon-carbon bonds.

[0131] n is an integer of 1 to 3.

[0132] Z 1 It is an (n+1)-valent hydrocarbon group having 1 to 20 carbon atoms or an (n+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms.

[0133] 17. The chemically amplified positive resist composition of 16., wherein the fluorine-containing polymer further contains 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),

[0134] [Chemistry 11]

[0135]

[0136] In the formula, R C Each is independently a hydrogen atom or a methyl group.

[0137] R 309 It is a hydrogen atom or a linear or branched hydrocarbon group having 1 to 5 carbon atoms which may contain a hetero atom inserted between carbon-carbon bonds.

[0138] R 310 It is a linear or branched hydrocarbon group having 1 to 5 carbon atoms, which may contain a hetero atom inserted between carbon-carbon bonds.

[0139] R 311 It is a saturated hydrocarbon group having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted by a fluorine atom, and a part of the -CH2- of the saturated hydrocarbon group may be substituted by an ester bond or an ether bond.

[0140] x is an integer of 1 to 3. y is an integer satisfying 0≤y≤5+2z-x. z is 0 or 1.

[0141] Z 2 It is a single bond, *-C(=O)-O- or *-C(=O)-NH-.

[0142] Z 3 is a single bond, -O-, *-C(=O)-OZ 31 -Z 32 - or *-C(=O)-NH-Z 31 -Z 32 -.Z 31 Z is a single bond or a saturated alkylene group having 1 to 10 carbon atoms. 32 It is a single bond, an ester bond, an ether bond or a sulfonamide bond.

[0143] * is the atomic bond between the carbon atoms in the main chain.

[0144] 18. The chemically amplified positive resist composition according to any one of 11. to 17., wherein the dissolution rate of the polymer in an alkaline developer is 10 nm / min or less.

[0145] 19. The chemically amplified positive resist composition according to any one of 11. to 18., wherein the dissolution rate of the unexposed portion of the resist film obtained from the chemically amplified positive resist composition in an alkaline developer is 10 nm / min or less.

[0146] 20. The chemically amplified positive resist composition according to any one of 11. to 19., wherein the dissolution rate of an exposed portion of a resist film obtained from the chemically amplified positive resist composition in an alkaline developer is 50 nm / sec or more.

[0147] 21. A method for forming a resist pattern, comprising the following steps:

[0148] Using any one of the chemically amplified positive resist compositions of 11. to 20. to form a resist film on a substrate,

[0149] irradiating the resist film with a pattern of high energy rays, and

[0150] The resist film having the irradiated pattern is developed using an alkaline developer.

[0151] 22. The resist pattern forming method according to 21., wherein the high-energy ray is KrF excimer laser, ArF excimer laser, electron beam or extreme ultraviolet ray with a wavelength of 3 to 15 nm.

[0152] 23. The resist pattern forming method according to 21. or 22., wherein the outermost surface of the substrate is composed of a material containing at least one selected from the group consisting of chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten and tin.

[0153] 24. The resist pattern forming method according to any one of 21. to 23., wherein the substrate is a transmission type or reflection type blank mask.

[0154] 25. A transmission or reflection blank mask obtained by coating the chemically amplified positive resist composition as described in any one of 11. to 20.

[0155] [Effects of the Invention]

[0156] The chemically amplified positive resist composition comprising a polymer modified by the acetal modifier of the present invention can form a pattern with high resolution, low LER, good shape after exposure, excellent rectangularity, and a pattern with suppressed influence of residual defects, and is suitable as a resist composition for forming an EB-induced resist film used for processing semiconductors, blank photomasks, etc. In addition, the pattern forming method using the chemically amplified positive resist composition of the present invention has high resolution and etching resistance, and can form a pattern with reduced LER and a pattern with suppressed influence of residual defects, so it is suitable for use in micro-processing technology, especially EUV lithography and EB lithography. DETAILED DESCRIPTION

[0157] The present invention is described in detail below. In addition, in the following description, depending on the structure represented by the chemical formula, there is an asymmetric carbon, and there may be mirror image isomers and non-mirror image isomers. In this case, these isomers are represented by one formula. These isomers can be used alone or in the form of a mixture.

[0158] [Acetal modifier]

[0159] The acetal modifier of the present invention provides a group having a cyclic saturated heterocyclic ring containing an oxygen atom or a sulfur atom, which serves as a protective group for an aliphatic or aromatic hydroxyl group.

[0160] The acetal modifier is preferably represented by the following formula (AC-1) or (AC-2).

[0161] [Chemistry 12]

[0162]

[0163] In formula (AC-1) and (AC-2), R L1 , R L2 , R L5 , R L6 and R L7 Each independently represents a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms. The aforementioned hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 15 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl; cyclic saturated hydrocarbon groups having 3 to 15 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, and cyclopropylmethyl; alkenyl groups having 2 to 15 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl; and cyclic unsaturated hydrocarbon groups having 3 to 15 carbon atoms, such as cyclohexenyl, but are not limited thereto.

[0164] Again, R L1 With R L2 They can also bond to each other and to the carbon atoms to which they are bonded to form a ring, R L5 ~R L7 Any two of the above may be bonded to each other and form a ring together with the carbon atoms to which they are bonded. Specific examples of the above ring include, but are not limited to, a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, and an adamantane ring.

[0165] R L1 , R L2 , R L5 , R L6 and R L7 , can be appropriately selected according to the design of the sensitivity of the decomposable group to acid. For example, if a design that can be decomposed by strong acid is used to ensure relatively high stability, a hydrogen atom can be selected; if a design that is relatively highly reactive and highly sensitive to pH changes and suppresses residual defects is used, a straight-chain alkyl group can be selected. L1 , R L2 , R L5 , R L6 and R L7 Specific examples include methyl, ethyl, propyl, isopropyl, cyclopentyl, cyclohexyl and tert-butyl. From the viewpoint of having the most suitable acid-releasing performance, methyl is preferred.

[0166] In the acetal modifier represented by formula (AC-2), if R L5 , R L6 and R L7 It is particularly preferred that the bonded carbon atom is a secondary carbon atom from the viewpoint of polymer stability and reactivity with an acid.

[0167] In formula (AC-1) and (AC-2), R L3, R L4 , R L8 and R L9 Each independently represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom. The hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include and L1 , R L2 , R L5 , R L6 and R L7 The hydrocarbon groups represented are exemplified by the same examples.

[0168] Again, R L3 With R L4 They can also bond to each other and to the carbon atoms to which they are bonded to form a ring, R L8 With R L9 They may also be bonded to each other and to form a ring together with the carbon atoms to which they are bonded. L1 With R L2 The same examples are exemplified for the rings that can be formed together with the carbon atoms to which they are bonded.

[0169] In formula (AC-1) and (AC-2), W 1 The group is a group containing a cyclic saturated heterocyclic ring containing an oxygen atom or a sulfur atom. The aforementioned cyclic saturated heterocyclic ring is preferably a cyclic ether, a cyclic thioether, a cyclic sulfoxide, a cyclic sulfone, etc., and more preferably a cyclic ether, a cyclic thioether, etc. In addition, a lactone structure or a sulfone structure is not preferred because the acid diffusion inhibition ability is too high, thereby significantly reducing the sensitivity of the resist film.

[0170] W 1 The specific structure of the group containing a cyclic saturated heterocyclic ring containing an oxygen atom or a sulfur atom represented by is exemplified below, but is not limited thereto.

[0171] [Chemistry 13]

[0172]

[0173] In formula (AC-2), X is a chlorine atom, a bromine atom or an iodine atom. From the viewpoint of synthesis, X is preferably a chlorine atom.

[0174] In formulae (AC-1) and (AC-2), m1 and m2 are each independently an integer of 0 to 3. From the viewpoint of facilitating the modification reaction of the base polymer described below, m1 and m2 are preferably 1 or 2, and more preferably 1.

[0175] Specific examples of the acetal modifier represented by formula (AC-1) include the following, but are not limited thereto.

[0176] [Chemistry 14]

[0177]

[0178] [Chemistry 15]

[0179]

[0180] [Chemistry 16]

[0181]

[0182] [Chemistry 17]

[0183]

[0184] [Chemistry 18]

[0185]

[0186] [Chemistry 19]

[0187]

[0188] [Chemistry 20]

[0189]

[0190] [Chemistry 21]

[0191]

[0192] [Chemistry 22]

[0193]

[0194] [Chemistry 23]

[0195]

[0196] [Chemistry 24]

[0197]

[0198] [Chemistry 25]

[0199]

[0200] [Chemistry 26]

[0201]

[0202] [Chemistry 27]

[0203]

[0204] [Chemistry 28]

[0205]

[0206] [Chemistry 29]

[0207]

[0208] [Chemistry 30]

[0209]

[0210] [Chemistry 31]

[0211]

[0212] [Chemistry 32]

[0213]

[0214] [Chemistry 33]

[0215]

[0216] [Chemistry 34]

[0217]

[0218] [Chemistry 35]

[0219]

[0220] [Chemistry 36]

[0221]

[0222] [Chemistry 37]

[0223]

[0224] [Chemistry 38]

[0225]

[0226] [Chemistry 39]

[0227]

[0228] [Chemistry 40]

[0229]

[0230] [Chemistry 41]

[0231]

[0232] [Chemistry 42]

[0233]

[0234] [Chemistry 43]

[0235]

[0236] [Chemistry 44]

[0237]

[0238] [Chemistry 45]

[0239]

[0240] [Chemistry 46]

[0241]

[0242] [Chemistry 47]

[0243]

[0244] [Chemistry 48]

[0245]

[0246] [Chemistry 49]

[0247]

[0248] [Chemistry 50]

[0249]

[0250] [Chemistry 51]

[0251]

[0252] [Chemistry 52]

[0253]

[0254] [Chemistry 53]

[0255]

[0256] [Chemistry 54]

[0257]

[0258] [Chemistry 55]

[0259]

[0260] [Chemistry 56]

[0261]

[0262] [Chemistry 57]

[0263]

[0264] [Chemistry 58]

[0265]

[0266] [Chemistry 59]

[0267]

[0268] [Chemistry 60]

[0269]

[0270] [Chemistry 61]

[0271]

[0272] [Chemistry 62]

[0273]

[0274] [Chemistry 63]

[0275]

[0276] [Chemistry 64]

[0277]

[0278] [Chemistry 65]

[0279]

[0280] Specific examples of the acetal modifier represented by formula (AC-2) include the following, but are not limited thereto.

[0281] [Chemistry 66]

[0282]

[0283] [Chemistry 67]

[0284]

[0285] [Chemistry 68]

[0286]

[0287] [Chemistry 69]

[0288]

[0289] [Chemistry 70]

[0290]

[0291] [Chemistry 71]

[0292]

[0293] [Chemistry 72]

[0294]

[0295] [Chemistry 73]

[0296]

[0297] [Chemistry 74]

[0298]

[0299] [Chemistry 75]

[0300]

[0301] [Chemistry 76]

[0302]

[0303] [Chemistry 77]

[0304]

[0305] [Chemistry 78]

[0306]

[0307] [Chemistry 79]

[0308]

[0309] [Chemistry 80]

[0310]

[0311] [Chemistry 81]

[0312]

[0313] [Chemistry 82]

[0314]

[0315] [Chemistry 83]

[0316]

[0317] [Chemistry 84]

[0318]

[0319] [Chemistry 85]

[0320]

[0321] [Chemistry 86]

[0322]

[0323] [Chemistry 87]

[0324]

[0325] [Chemistry 88]

[0326]

[0327] [Chemistry 89]

[0328]

[0329] [Chemistry 90]

[0330]

[0331] [Chemistry 91]

[0332]

[0333] [Chemistry 92]

[0334]

[0335] [Chemistry 93]

[0336]

[0337] [Chemistry 94]

[0338]

[0339] [Chemistry 95]

[0340]

[0341] [Chemistry 96]

[0342]

[0343] [Chemistry 97]

[0344]

[0345] [Chemistry 98]

[0346]

[0347] [Chemistry 99]

[0348]

[0349] [Chemical 100]

[0350]

[0351] [Chemistry 101]

[0352]

[0353] [Chemistry 102]

[0354]

[0355] [Chemistry 103]

[0356]

[0357] [Chemistry 104]

[0358]

[0359] [Chemistry 105]

[0360]

[0361] [Chemistry 106]

[0362]

[0363] [Chemistry 107]

[0364]

[0365] [Chemistry 108]

[0366]

[0367] [Chemistry 109]

[0368]

[0369] [Chemistry 110]

[0370]

[0371] [Chemistry 111]

[0372]

[0373] [Chemistry 112]

[0374]

[0375] [Chemistry 113]

[0376]

[0377] [Chemistry 114]

[0378]

[0379] [Chemistry 115]

[0380]

[0381] [Chemistry 116]

[0382]

[0383] [Chemistry 117]

[0384]

[0385] [Chemistry 118]

[0386]

[0387] [Chemistry 119]

[0388]

[0389] [Chemistry 120]

[0390]

[0391] [Chemistry 121]

[0392]

[0393] [Chemistry 122]

[0394]

[0395] [Chemistry 123]

[0396]

[0397] [Chemistry 124]

[0398]

[0399] [Chemistry 125]

[0400]

[0401] [Chemistry 126]

[0402]

[0403] [Chemistry 127]

[0404]

[0405] [Chemistry 128]

[0406]

[0407] [Chemistry 129]

[0408]

[0409] [polymer]

[0410] The polymer of the present invention comprises a repeating unit A1 having a structure in which a side chain aromatic hydroxyl group is protected by an acid-labile group represented by the following formula (AL-1) or (AL-2), and is deprotected by acid to become alkali-soluble.

[0411] [Chemistry 130]

[0412]

[0413] In the formula, R L1 ~R L9 , W 1 , m1 and m2 are the same as described above. The chain line represents the atomic bond between the oxygen atom of the aromatic hydroxyl group.

[0414] The repeating unit A1 is preferably represented by the following formula (A1).

[0415] [Chemistry 131]

[0416]

[0417] In formula (A1), a1 is 0 or 1. a2 is an integer of 0 to 4 when a1=0, and an integer of 0 to 6 when a1=1. a3 is an integer of 1 to 3. However, when a1=0, 1≤a2+a3≤5, and when a1=1, 1≤a2+a3≤7.

[0418] In formula (A1), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0419] In formula (A1), X 1 It is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is an atomic bond between the carbon atoms of the main chain.

[0420] In formula (A1), X 2 It is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate bond, a carbonate bond or a carbamate bond. Among these, a single bond, an ether bond or an ester bond is preferred, and a single bond or an ester bond is more preferred.

[0421] In formula (A1), A 1 It is a single bond or a saturated alkylene group having 1 to 10 carbon atoms, and a part of -CH2- of the saturated alkylene group may be substituted by -O-. The saturated alkylene group may be straight chain, branched or cyclic, and specific examples thereof include alkanediyl groups having 1 to 10 carbon atoms such as methanediyl, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, and their structural isomers; cyclic saturated alkylene groups having 3 to 10 carbon atoms such as cyclopropanediyl, cyclobutanediyl, cyclopentanediyl, and cyclohexanediyl; and groups obtained by combining them.

[0422] In formula (A1), R 1 is a halogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom. The aforementioned saturated hydrocarbon 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 methyl, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl; cyclic saturated hydrocarbon groups having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups having 2 to 20 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl; cyclic unsaturated hydrocarbon groups having 3 to 20 carbon atoms, such as cyclohexenyl; aryl groups having 2 to 20 carbon atoms, such as phenyl and naphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl; groups obtained by combining them, etc. Among these, aryl groups are preferred. Furthermore, part or all of the hydrogen atoms of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and part of the -CH2- of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, it may contain a hydroxyl 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 bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, and the like.

[0423] In formula (A1), R is an acid-labile group represented by formula (AL-1) or (AL-2).

[0424] Specific examples of the repeating unit A1 include, but are not limited to, the following: In the following formula, R is the same as described above.

[0425] [Chemistry 132]

[0426]

[0427] [Chemistry 133]

[0428]

[0429] [Chemistry 134]

[0430]

[0431] [Chemistry 135]

[0432]

[0433] [Chemistry 136]

[0434]

[0435] [Chemistry 137]

[0436]

[0437] [Chemistry 138]

[0438]

[0439] [Chemistry 139]

[0440]

[0441] [Chemistry 140]

[0442]

[0443] The content of the repeating unit A1 in all the repeating units of the above polymer is preferably 10 to 40 mol %, more preferably 10 to 35 mol %, and even more preferably 20 to 30 mol %. The repeating unit A1 may be used alone or in combination of two or more.

[0444] The aforementioned polymer may further contain a phenolic hydroxyl group-containing repeating unit A2 represented by the following formula (A2).

[0445] [Chemistry 141]

[0446]

[0447] In formula (A2), b1 is 0 or 1. b2 is an integer of 0 to 4 when b1=0, and an integer of 0 to 6 when b1=1. b3 is an integer of 1 to 3. However, when b1=0, 1≤b2+b3≤5, and when b1=1, 1≤b2+b3≤7.

[0448] In formula (A2), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0449] In formula (A2), X 3 It is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is an atomic bond between the carbon atoms of the main chain.

[0450] In formula (A2), X 4 It is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate bond, a carbonate bond or a carbamate bond. Among these, a single bond, an ether bond or an ester bond is preferred, and a single bond or an ester bond is more preferred.

[0451] In formula (A2), A 2 is a single bond or a saturated alkylene group having 1 to 10 carbon atoms, and a portion of the -CH2- in the saturated alkylene group may be substituted by -O-. The saturated alkylene group may be linear, branched, or cyclic. Specific examples thereof include and 1 The saturated alkylene groups represented by are exemplified by the same examples.

[0452] In formula (A2), R 2 is a halogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom. The saturated hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include and 1 The hydrocarbon groups represented are exemplified by the same examples.

[0453] X 3 , X 4 and A 2 When all of them are single bonds, the repeating unit A2 is preferably a unit derived from 3-hydroxystyrene, 4-hydroxystyrene, 5-hydroxy-2-vinylnaphthalene, 6-hydroxy-2-vinylnaphthalene, etc. Among these, the repeating unit represented by the following formula (A2-1) is more preferred.

[0454] [Chemistry 142]

[0455]

[0456] In the formula, R A and b3 are the same as described above.

[0457] X 1 When it is other than a single bond, preferred examples of the repeating unit A2 include those in which R in the specific examples of the repeating unit A1 is substituted with a hydrogen atom, but the present invention is not limited thereto.

[0458] When the aforementioned polymer contains repeating unit A2, its content is preferably 30 to 90 mol % of all repeating units of the aforementioned polymer, and more preferably 40 to 85 mol %. However, when the polymer described later contains at least one of the repeating units represented by formula (B1) and the repeating units represented by formula (B2) that provide higher etching resistance and this unit has a phenolic hydroxyl group as a substituent, it is preferable to also add this ratio and it is preferably within the aforementioned range. Repeating unit A2 can be used alone or in combination of two or more.

[0459] The polymer may further contain at least one selected from the group consisting of a repeating unit represented by the following formula (A3-1) (hereinafter also referred to as repeating unit A3-1) and a repeating unit represented by the following formula (A3-2) (hereinafter also referred to as repeating unit A3-2).

[0460] [Chemistry 143]

[0461]

[0462] In formula (A3-1), c1 is 0 or 1. c2 is an integer of 0 to 2, and when 0 is 0, it represents a benzene skeleton, when 1 is 1, it represents a naphthalene skeleton, and when 2 is 2, it represents an anthracene skeleton. c3 is an integer satisfying 0≤c3≤5+2(c2)-c4. c4 is an integer of 1 to 3. c5 is 0 or 1. When c2 is 0, it is preferably that c3 is an integer of 0 to 3 and c4 is an integer of 1 to 3. When c2 is 1 or 2, it is preferably that c3 is an integer of 0 to 4 and c4 is an integer of 1 to 3.

[0463] In formula (A3-2), d1 is an integer of 0 to 2. d2 is an integer of 0 to 2. d3 is an integer of 0 to 5. d4 is an integer of 0 to 2.

[0464] In formula (A3-1) and (A3-2), R A Each is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0465] In formula (A3-1), A 3 It is a single bond or a saturated alkylene group having 1 to 10 carbon atoms, and the -CH2- of the saturated alkylene group may be substituted by -O-. The saturated alkylene group may be straight-chain, branched or cyclic, and specific examples thereof include methylene, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, and their structural isomers; cyclic saturated alkylene groups such as cyclopropanediyl, cyclobutanediyl, cyclopentanediyl, and cyclohexanediyl; and groups obtained by combining them. When the saturated alkylene group contains an ether bond, when c1 in formula (A3-1) is 1, it may be inserted at any position other than between the carbon atom at the α position and the carbon atom at the β position with respect to the ester oxygen atom. When c1 is 0, the atom bonded to the main chain becomes an etheric oxygen atom, and the second ether bond can be inserted at any position except between the carbon atom at the α position and the carbon atom at the β position relative to the etheric oxygen atom. It is also preferable that the carbon number of the saturated alkylene group is 10 or less, because sufficient solubility in an alkaline developer can be obtained.

[0466] In formula (A3-2), A 4 is a single bond, phenylene, naphthylene or *-C(=O)-OA 41 -.A 41It is an aliphatic alkylene group having 1 to 20 carbon atoms, or a phenylene group or a naphthylene group which may contain a hydroxyl group, an ether bond, an ester bond or a lactone ring. * is an atomic bond between the carbon atoms of the main chain.

[0467] In formula (A3-1), R 3 It is a halogen atom, a saturated hydrocarbon group having 1 to 6 carbon atoms which may be substituted by a halogen atom, a saturated hydrocarbon oxy group having 1 to 6 carbon atoms which may be substituted by a halogen atom, or a saturated hydrocarbon carbonyloxy group having 2 to 8 carbon atoms which may be substituted by a halogen atom. The saturated hydrocarbon group, the saturated hydrocarbon oxy group, and the saturated hydrocarbon carbonyloxy group may be straight-chain, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, pentyl, and hexyl; cycloalkyl groups having 3 to 6 carbon atoms such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl; and groups obtained by combining them. If the number of carbon atoms is below the upper limit, the solubility in the alkaline developer is good. When c3 is 2 or more, each R 3 They may be the same as or different from each other.

[0468] In formula (A3-2), R 4 and R 5 Each independently represents a hydrocarbon group having 1 to 10 carbon atoms which may contain a hetero atom, R 4 With R 5 They may also be bonded to each other and to the carbon atoms to which they are bonded to form a ring.

[0469] In formula (A3-2), R 6 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.

[0470] In formula (A3-2), R 7 Each independently represents a hydrocarbon group having 1 to 10 carbon atoms which may contain a hetero atom.

[0471] In formula (A3-1), X A When c4 is 1, it is an acid-labile group; when c4 is 2 or 3, it is a hydrogen atom or an acid-labile group, but at least one of them is an acid-labile group. That is, in the repeating unit A3-1, at least one of the phenolic hydroxyl groups bonded to the aromatic ring is protected by an acid-labile group, or the carboxyl group bonded to the aromatic ring is protected by an acid-labile group. Such an acid-labile group can be any one that provides an acidic group by acid detachment used in a plurality of known chemically amplified positive resist compositions, and any one can be used without particular limitation.

[0472] If a tertiary saturated hydrocarbon group is selected as the acid-labile group, it is ideal because it can provide a pattern with a small LER even when a fine pattern with a resist film thickness of, for example, 10 to 100 nm and a line width of 45 nm or less is formed. The tertiary alkyl group is preferably a group with 4 to 18 carbon atoms in order to obtain a monomer for polymerization by distillation. In addition, the group bonded to the tertiary carbon atom of the tertiary saturated hydrocarbon group may be a saturated hydrocarbon group with 1 to 15 carbon atoms containing a functional group containing an oxygen atom such as an ether bond or a carbonyl group, and the groups bonded to the tertiary carbon atom may be bonded to each other to form a ring.

[0473] Specific examples of the group bonded to the tertiary carbon atom include methyl, ethyl, propyl, adamantyl, norbornyl, tetrahydrofuran-2-yl, 7-oxanorbornane-2-yl, cyclopentyl, 2-tetrahydrofuranyl, tricyclo[5.2.1.0 2,6 ]decyl, tetracyclic [4.4.0.1 2,5 .1 7,10 ] dodecyl, 3-oxo-1-cyclohexyl.

[0474] and tertiary saturated hydrocarbon groups having the same as substituents, such as tert-butyl, tert-amyl, 1-ethyl-1-methylpropyl, 1,1-diethylpropyl, 1,1,2-trimethylpropyl, 1-adamantyl-1-methylethyl, 1-methyl-1-(2-norbornyl)ethyl, 1-methyl-1-(tetrahydrofuran-2-yl)ethyl, 1-methyl-1-(7-oxanorbornan-2-yl)ethyl, 1-methylcyclopentyl, 1-ethyl cyclopentyl, 1-propylcyclopentyl, 1-isopropylcyclopentyl, 1-cyclopentylcyclopentyl, 1-cyclohexylcyclopentyl, 1-(2-tetrahydrofuranyl)cyclopentyl, 1-(7-oxanorbornan-2-yl)cyclopentyl, 1-methylcyclohexyl, 1-ethylcyclohexyl, 1-cyclopentylcyclohexyl, 1-cyclohexylcyclohexyl, 2-methyl-2-norbornyl, 2-ethyl-2-norbornyl, 8-methyl-8-tricyclo[5.2.1.0 2,6 ]decyl, 8-ethyl-8-tricyclo[5.2.1.0 2,6 ]decyl, 3-methyl-3-tetracyclo[4.4.0.1 2,5 .1 7,10 ] dodecyl, 3-ethyl-3-tetracyclo[4.4.0.1 2,5 .1 7,10 ] dodecyl, 2-methyl-2-adamantyl, 2-ethyl-2-adamantyl, 1-methyl-3-oxo-1-cyclohexyl, 1-methyl-1-(tetrahydrofuran-2-yl)ethyl, 5-hydroxy-2-methyl-2-adamantyl, 5-hydroxy-2-ethyl-2-adamantyl, but are not limited to these.

[0475] In addition, the aforementioned acid-labile group is, for example, a group represented by the following formula (A3-1-1). The group represented by formula (A3-1-1) is often used as an acid-labile group and is a useful option for an acid-labile group that provides a relatively rectangular pattern at the interface between the pattern and the substrate. When X is a group represented by formula (A3-1-1), an acetal structure is formed.

[0476] [Chemistry 144]

[0477]

[0478] In formula (A3-1-1), R L11 R is a hydrogen atom or a saturated hydrocarbon group having 1 to 10 carbon atoms. L12 It is a saturated hydrocarbon group having 1 to 30 carbon atoms. The saturated hydrocarbon group may be linear, branched or cyclic.

[0479] R L11 , can be appropriately selected according to the design of the sensitivity of the decomposable group to acid. For example, in order to ensure relatively high stability, if it is designed to be decomposed by strong acid, a hydrogen atom can be selected. If it is designed to be highly sensitive to pH changes with relatively high reactivity, a straight-chain alkyl group can be selected. It also depends on the combination of the acid generator and the basic compound mixed in the resist composition, but when R L12 When a relatively large alkyl group is selected at the end and the solubility change due to decomposition is large, R L11 In particular, the carbon atom bonded to the acetal carbon is preferably a secondary carbon atom. L11 Examples include isopropyl, sec-butyl, cyclopentyl, cyclohexyl and the like.

[0480] Among the above acetal groups, in order to obtain higher resolution, R L12 It is preferably a polycyclic alkyl group having 7 to 30 carbon atoms. L12 When it is a polycyclic alkyl group, it is preferred to form a bond between a secondary carbon atom constituting the polycyclic ring structure and the acetal oxygen. When it is bonded to a secondary carbon atom of the ring structure, the polymer becomes a more stable compound than when it is bonded to a tertiary carbon atom, and the storage stability of the resist composition becomes good, and the resolution does not deteriorate. L12 When it is bonded to a primary carbon atom via a linear alkyl group having 1 or more carbon atoms, the glass transition temperature (Tg) of the polymer becomes good, and the resist pattern after development does not change shape due to baking.

[0481] Preferred examples of the group represented by formula (A3-1-1) include, but are not limited to, the following. L11 Same as above.

[0482] [Chemistry 145]

[0483]

[0484] Preferred examples of repeating unit A3-2 include, but are not limited to, the following. A Same as above.

[0485] [Chemistry 146]

[0486]

[0487] As for other acid-labile groups, an acid-labile group in which the hydrogen atom of the phenolic hydroxyl group is replaced by -CH2COO- (tertiary saturated hydrocarbon group) can also be used. In this case, the tertiary saturated hydrocarbon group mentioned above can be the same as the tertiary saturated hydrocarbon group used for the protection of the phenolic hydroxyl group.

[0488] When the polymer contains at least one selected from repeating units A3-1 and A3-2, its content is preferably 2 to 40 mol% of all repeating units of the polymer, and the combined repeating units A1, A3-1 and A3-2 are preferably 10 to 60 mol%, more preferably 10 to 50 mol%, and more preferably 10 to 40 mol% of all repeating units of the polymer. Repeating units A3-1 and A3-2 may be used alone or in combination of two or more.

[0489] The aforementioned polymer may further contain at least one selected from the repeating unit represented by the following formula (B1) (hereinafter also referred to as repeating unit B1), the repeating unit represented by the following formula (B2) (hereinafter also referred to as repeating unit B2), and the repeating unit represented by the following formula (B3) (hereinafter also referred to as repeating unit B3).

[0490] [Chemistry 147]

[0491]

[0492] In formulae (B1) and (B2), e and f are each independently an integer of 0-4.

[0493] In formula (B3), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. g1 is an integer of 0 to 5. g2 is an integer of 0 to 2.

[0494] In formula (B3), X 5 It is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is an atomic bond between the carbon atoms of the main chain.

[0495] In formula (B3), A 5is a single bond or a saturated alkylene group having 1 to 10 carbon atoms, and a portion of the -CH2- in the saturated alkylene group may be substituted by -O-. The saturated alkylene group may be linear, branched or cyclic, and specific examples thereof include A in formula (A1): 1 The description exemplifies the same example.

[0496] In formula (B1) and (B2), R 11 and R 12 Each independently represents a hydroxyl group, a halogen atom, a saturated hydrocarbon carbonyloxy group having 2 to 8 carbon atoms which may be substituted by a halogen atom, a saturated hydrocarbon group having 1 to 8 carbon atoms which may be substituted by a halogen atom, or a saturated hydrocarbonoxy group having 1 to 8 carbon atoms which may be substituted by a halogen atom. The saturated hydrocarbon carbonyloxy group, saturated hydrocarbon group, and saturated hydrocarbonoxy group may be straight-chain, branched, or cyclic. When e is 2 or more, each R 11 They may be the same or different. When f is 2 or more, each R 12 They may be the same as or different from each other.

[0497] In formula (B3), R 13 is an acetyl group, a saturated hydrocarbon group having 1 to 20 carbon atoms, a saturated hydrocarbon oxy group having 1 to 20 carbon atoms, a saturated hydrocarbon carbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbon oxyalkyl group having 2 to 20 carbon atoms, a saturated hydrocarbon thioalkyl group having 2 to 20 carbon atoms, a halogen atom, a nitro group or a cyano group. When g2 is 1 or 2, it may also be a hydroxyl group. The saturated hydrocarbon group, saturated hydrocarbon oxyalkyl group, saturated hydrocarbon carbonyloxyalkyl group, saturated hydrocarbon oxyalkyl group and saturated hydrocarbon thioalkyl group may be straight-chain, branched or cyclic. When g1 is 2 or more, each R 13 They may be the same as or different from each other.

[0498] When repeating units B1 to B3 are used, in addition to the etching resistance provided by the aromatic ring, an effect of improving the resistance to EB irradiation during etching and pattern inspection due to the addition of a ring structure to the main chain can be obtained.

[0499] When the aforementioned polymer contains repeating units B1 to B3, in order to obtain the effect of improving etching resistance, its content is preferably 5 mol% or more of all repeating units of the aforementioned polymer. In addition, the upper limit of the content of repeating units B1 to B3 is preferably 25 mol% or less of all repeating units of the aforementioned polymer, and 20 mol% or less is more preferred. If the amount introduced is 25 mol% or less when there is no functional group or the functional group is other than hydroxyl, there is no risk of developing defects, so it is ideal. Repeating units B1 to B3 can be used alone or in combination of two or more.

[0500] The content of the repeating unit A2 and at least one selected from the repeating units B1 to B3 in all the repeating units of the polymer is preferably 50 mol% or more, more preferably 60 mol% or more.

[0501] The aforementioned polymer may also contain a commonly used (meth)acrylate unit protected by an acid-labile group, a (meth)acrylate unit having a lactone structure, a hydroxyl group other than a phenolic hydroxyl group, or other adhesion groups. These repeating units can be used to fine-tune the properties of the resist film, but these units may not be present.

[0502] Examples of the aforementioned (meth)acrylate units having an adhesion group include repeating units represented by the following formula (B4) (hereinafter also referred to as repeating units B4), repeating units represented by the following formula (B5) (hereinafter also referred to as repeating units B5), and repeating units represented by the following formula (B6) (hereinafter also referred to as repeating units B6). These units do not show acidity and can be used as units that provide adhesion to a substrate or units that adjust solubility.

[0503] [Chemistry 148]

[0504]

[0505] In formulas (B4) to (B6), R A R is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 14 is -O- or methylene. 15 is a hydrogen atom or a hydroxyl group. 16 is a saturated hydrocarbon group having 1 to 4 carbon atoms. h is an integer of 0 to 3.

[0506] When the polymer contains repeating units B4 to B6, the content thereof is preferably 0 to 20 mol%, more preferably 0 to 10 mol%, of all repeating units of the polymer. The repeating units B4 to B6 may be used alone or in combination of two or more.

[0507] The aforementioned polymer may also contain at least one selected from the repeating unit represented by the following formula (C1) (hereinafter also referred to as repeating unit C1), the repeating unit represented by the following formula (C2) (hereinafter also referred to as repeating unit C2), the repeating unit represented by the following formula (C3) (hereinafter also referred to as repeating unit C3), and the repeating unit represented by the following formula (C4) (hereinafter also referred to as repeating unit C4).

[0508] [Chemistry 149]

[0509]

[0510] In formulas (C1) to (C4), 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 for* 1 -C(=O)-OZ 21 -, *1 -C(=O)-NH-Z 21 -or* 1 -OZ 21 -.Z 21 It is an aliphatic alkylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining them, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. 1 Represents and Z 1 Atomic bonds between Z 3 Each independently represents a single bond, phenylene, naphthylene or * 2 -C(=O)-OZ 31 -.Z 31 It is an aliphatic alkylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, and the aliphatic alkylene group may also contain a hydroxyl group, an ether bond, an ester bond or a lactone ring. 2 Represents the atomic bond between the carbon atoms of the main chain. 4 Each is independently a single bond, * 3 -Z 41 -C(=O)-O-,* 3 -C(=O)-NH-Z 41 -or* 3 -OZ 41 -.Z 41 It is a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom. 3 Represents and Z 3 Atomic bonds between Z 5 Each is independently a single bond, * 4 -Z 51 -C(=O)-O-,* 4 -C(=O)-NH-Z 51 -or* 4 -OZ 51 -.Z 51 It is a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom. 4 Represents and Z 4 Atomic bonds between Z 6 is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, phenylene substituted with trifluoromethyl, * 2 -C(=O)-OZ 61 -, * 2 -C(=O)-N(H)-Z 61 -or* 2 -OZ 61 -.Z 61 It is an aliphatic alkylene 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 hydroxyl group. 2 Represents the atomic bonds between the carbon atoms in the main chain.

[0511] Z 21 , Z 31 and Z 61 The aliphatic alkylene group represented may be straight-chain, branched or cyclic, and specific examples thereof include methanediyl, ethane-1,1-diyl, ethane-1,2-diyl, propane-1,1-diyl, propane-1,2-diyl, propane-1,3-diyl, propane-2,2-diyl, butane-1,1-diyl, butane-1,2-diyl, butane-1,3-diyl, butane-2,3-diyl, butane-1,4-diyl, 1,1-dimethylethane-1,2-diyl, pentane-1,5-diyl, 2-methylbutane-1,2-diyl, hexane-1,6-diyl; cycloalkanediyl such as cyclopropanediyl, cyclobutanediyl, cyclopentanediyl and cyclohexanediyl; and groups obtained by combining them.

[0512] Z 41 and Z 51 The alkylene group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include the following, but are not limited thereto.

[0513] [Chemistry 150]

[0514]

[0515] In the formula, the chain lines are atomic bonds.

[0516] In formula (C1), R 31 and R 32Each is independently a hydrocarbon group having 1 to 20 carbon atoms which may contain heteroatoms. The aforementioned hydrocarbon 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 methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl; cyclic saturated hydrocarbon groups having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups having 2 to 20 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl; cyclic unsaturated hydrocarbon groups having 3 to 20 carbon atoms, such as cyclohexenyl; aryl groups having 6 to 20 carbon atoms, such as phenyl, naphthyl, and thienyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl; and groups obtained by combining them, among which aryl groups are preferred. Furthermore, a part or all of the hydrogen atoms of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and a part of the -CH2- of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, the hydrocarbon group may contain a hydroxyl 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 bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, and the like.

[0517] Again, R 31 With R 32 They may also be bonded to each other and to form a ring together with the sulfur atom to which they are bonded. In this case, the aforementioned ring, for example, is the same as in the description of the formula (cation-1) described later. ct1 and R ct2 The same examples are exemplified as the ring that can be formed together with the sulfur atom to which they are bonded.

[0518] The cation of the repeating unit C1 can be listed below, but is not limited thereto. In the following formula, R A Same as above.

[0519] [Chemistry 151]

[0520]

[0521] [Chemistry 152]

[0522]

[0523] [Chemistry 153]

[0524]

[0525] [Chemistry 154]

[0526]

[0527] [Chemistry 155]

[0528]

[0529] [Chemistry 156]

[0530]

[0531] [Chemistry 157]

[0532]

[0533] In formula (C1), M - It is a non-nucleophilic relative ion. The aforementioned non-nucleophilic relative ion is preferably a halide ion, a sulfonic acid anion, an imidic acid anion and a methylated acid anion. Specific examples of the aforementioned halide ion include chloride ion, bromide ion, etc. Specific examples of the aforementioned sulfonic acid anion (sulfonate ion) include fluoroalkylsulfonate ions such as trifluoromethanesulfonate ion, 1,1,1-trifluoroethanesulfonate ion, nonafluorobutanesulfonate ion; arylsulfonate ions such as toluenesulfonate ion, benzenesulfonate ion, 4-fluorobenzenesulfonate ion, 1,2,3,4,5-pentafluorobenzenesulfonate ion; alkylsulfonate ions such as methanesulfonate ion and butanesulfonate ion, etc. Specific examples of the aforementioned imidic acid anion (imide ion) include, for example, bis(trifluoromethylsulfonyl)imide ion, bis(perfluoroethylsulfonyl)imide ion, bis(perfluorobutylsulfonyl)imide ion, etc. Specific examples of the aforementioned methylated acid anion (methide ion) include, for example, tris(trifluoromethylsulfonyl)methide ion, tris(perfluoroethylsulfonyl)methide ion, etc.

[0534] Other examples of the non-nucleophilic counter ion include an anion represented by any one of the following formulae (C1-1) to (C1-4).

[0535] [Chemistry 158]

[0536]

[0537] In formula (C1-1), R fa is a fluorine atom or a hydrocarbon group having 1 to 40 carbon atoms which may contain a hetero atom. The hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include: fa1 The hydrocarbon groups represented are exemplified by the same examples.

[0538] The anion represented by the formula (C1-1) is preferably represented by the following formula (C1-1-1).

[0539] [Chemistry 159]

[0540]

[0541] In formula (C1-1-1), Q 11 and Q 12 Each independently represents a hydrogen atom, a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms. In order to improve the solvent solubility, at least one of them is preferably a trifluoromethyl group. m is an integer of 0 to 4, and 1 is particularly preferred. fa1 The hydrocarbon group may contain a hetero atom and has 1 to 35 carbon atoms. The hetero atom is preferably an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, etc., and an oxygen atom is more preferably. The hydrocarbon group preferably has 6 to 30 carbon atoms from the viewpoint of obtaining a high resolution when forming a fine pattern.

[0542] In formula (C1-1-1), R fa1 The hydrocarbon group having 1 to 35 carbon atoms 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 methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, 2-ethylhexyl, nonyl, undecyl, tridecyl, pentadecyl, heptadecanyl and eicosyl; cyclic saturated hydrocarbon groups having 3 to 35 carbon atoms, such as cyclopentyl, cyclohexyl, 1-adamantyl, 2-adamantyl, 1-adamantylmethyl, norbornyl, norbornylmethyl, tricyclodecanyl, tetracyclododecyl, tetracyclododecylmethyl and dicyclohexylmethyl; unsaturated aliphatic hydrocarbon groups having 2 to 35 carbon atoms, such as allyl and 3-cyclohexenyl; aryl groups having 6 to 35 carbon atoms, such as phenyl, 1-naphthyl, 2-naphthyl and 9-fluorenyl; aralkyl groups having 7 to 35 carbon atoms, such as benzyl and diphenylmethyl; groups obtained by combining these groups, etc.

[0543] In addition, part or all of the hydrogen atoms of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and part of the -CH2- of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc. Examples of the hydrocarbon group containing a hetero atom include a tetrahydrofuranyl 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.

[0544] In formula (C1-1-1), L a1 It is a single bond, an ether bond, an ester bond, a sulfonate bond, a carbonate bond or a carbamate bond. From the viewpoint of synthesis, an ether bond or an ester bond is preferred, and an ester bond is more preferred.

[0545] The anions represented by formula (C1-1) include, but are not limited to, the following. 11 As mentioned above, Ac is acetyl.

[0546] [Chemistry 160]

[0547]

[0548] [Chemistry 161]

[0549]

[0550] [Chemistry 162]

[0551]

[0552] [Chemistry 163]

[0553]

[0554] [Chemistry 164]

[0555]

[0556] [Chemistry 165]

[0557]

[0558] [Chemistry 166]

[0559]

[0560] [Chemistry 167]

[0561]

[0562] [Chemistry 168]

[0563]

[0564] [Chemistry 169]

[0565]

[0566] In formula (C1-2), R fb1 and R fb2 Each is independently a fluorine atom or a hydrocarbon group having 1 to 40 carbon atoms which may contain a hetero atom. The hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include: fa1 The hydrocarbon groups represented by are exemplified by the same examples. fb1 and R fb2 Preferably, it is a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms.fb1 and R fb2 They can also bond to each other and to the groups to which they are bonded (-CF2-SO2-N - -SO2-CF2-) together to form a ring. In this case, R fb1 and R fb2 The group obtained by bonding to each other is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0567] In formula (C1-3), R fc1 , R fc2 and R fc3 Each is independently a fluorine atom or a hydrocarbon group having 1 to 40 carbon atoms which may contain a hetero atom. The hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include: fa1 The hydrocarbon groups represented by are exemplified by the same examples. fc1 , R fc2 and R fc3 Preferably, it is a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fc1 and R fc2 They can also bond to each other and to the groups to which they are bonded (-CF2-SO2-C - -SO2-CF2-) together to form a ring. In this case, R fc1 and R fc2 The group obtained by bonding to each other is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0568] In formula (C1-4), R fd is a hydrocarbon group having 1 to 40 carbon atoms which may contain heteroatoms. The hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include: fa1 The hydrocarbon groups represented are exemplified by the same examples.

[0569] The anion represented by the formula (C1-4) may be exemplified by the following, but is not limited thereto.

[0570] [Chemistry 170]

[0571]

[0572] [Chemistry 171]

[0573]

[0574] 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 (C1-5).

[0575] [Chemistry 172]

[0576]

[0577] In formula (C1-5), x is an integer satisfying 1≤x≤3. y and z are integers satisfying 1≤y≤5, 0≤z≤3 and 1≤y+z≤5. y is preferably an integer satisfying 1≤y≤3, more preferably 2 or 3. z is preferably an integer satisfying 0≤z≤2.

[0578] In formula (C1-5), X BI is an iodine atom or a bromine atom, and when x and / or y is 2 or more, they may be the same as or different from each other.

[0579] In formula (C1-5), L 11 It is a saturated alkylene group having 1 to 6 carbon atoms which may contain a single bond, an ether bond or an ester bond. The saturated alkylene group may be linear, branched or cyclic.

[0580] In formula (C1-5), L 12 When x is 1, it is a single bond or a divalent linking group having 1 to 20 carbon atoms. When x is 2 or 3, it is a (x+1)-valent linking group having 1 to 20 carbon atoms. The linking group may contain an oxygen atom, a sulfur atom or a nitrogen atom.

[0581] In formula (C1-5), R fe is a hydroxyl group, a carboxyl group, a fluorine atom, a chlorine atom, a bromine atom or an amino group, or a hydrocarbon group having 1 to 20 carbon atoms, a hydrocarbonoxy group having 1 to 20 carbon atoms, a hydrocarboncarbonyl group having 2 to 20 carbon atoms, a hydrocarbonoxycarbonyl group having 2 to 20 carbon atoms, a hydrocarboncarbonyloxy group having 2 to 20 carbon atoms or a hydrocarbonsulfonyloxy group having 1 to 20 carbon atoms which may contain a fluorine atom, a chlorine atom, a bromine atom, a hydroxyl group, an amino group or an ether bond, or -N(R feA )(R feB )、-N(R feC )-C(=O)-R feD or -N(R feC )-C(=O)-OR feD . R feA and R feB Each R is independently a hydrogen atom or a saturated hydrocarbon group having 1 to 6 carbon atoms. feC R is a hydrogen atom or a saturated hydrocarbon group having 1 to 6 carbon atoms, and may contain a halogen atom, a hydroxyl group, a saturated hydrocarbon oxy group having 1 to 6 carbon atoms, a saturated hydrocarbon carbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbon carbonyloxy group having 2 to 6 carbon atoms. feDIt is an aliphatic hydrocarbon 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 also contain a halogen atom, a hydroxyl group, a saturated hydrocarbon oxy group having 1 to 6 carbon atoms, a saturated hydrocarbon carbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbon carbonyloxy group having 2 to 6 carbon atoms. The aforementioned aliphatic hydrocarbon group may be saturated or unsaturated, and may be straight-chain, branched, or cyclic. The aforementioned hydrocarbon group, hydrocarbonoxy group, hydrocarbon carbonyl group, hydrocarbon oxycarbonyl group, hydrocarbon carbonyloxy group, and hydrocarbon sulfonyloxy group may be straight-chain, branched, or cyclic. When x and / or z is 2 or more, each R fe They may be the same as or different from each other.

[0582] Among these, R fe Hydroxyl, -N(R feC )-C(=O)-R feD 、-N(R feC )-C(=O)-OR feD , fluorine atom, chlorine atom, bromine atom, methyl group, methoxy group and the like are preferred.

[0583] In formula (C1-5), Rf 11 ~Rf 14 Each independently represents a hydrogen atom, a fluorine atom or a trifluoromethyl group, and at least one of these is a fluorine atom or a trifluoromethyl group. 11 With Rf 12 They can also be combined to form a carbonyl group. 13 and Rf 14 All of them are preferably fluorine atoms.

[0584] The anions represented by formula (C1-5) include, but are not limited to, the following. BI Same as above.

[0585] [Chemistry 173]

[0586]

[0587] [Chemistry 174]

[0588]

[0589] [Chemistry 175]

[0590]

[0591] [Chemistry 176]

[0592]

[0593] [Chemistry 177]

[0594]

[0595] [Chemistry 178]

[0596]

[0597] [Chemistry 179]

[0598]

[0599] [Chemistry 180]

[0600]

[0601] [Chemistry 181]

[0602]

[0603] [Chemistry 182]

[0604]

[0605] [Chemistry 183]

[0606]

[0607] [Chemistry 184]

[0608]

[0609] [Chemistry 185]

[0610]

[0611] [Chemistry 186]

[0612]

[0613] [Chemistry 187]

[0614]

[0615] [Chemistry 188]

[0616]

[0617] [Chemistry 189]

[0618]

[0619] [Chemistry 190]

[0620]

[0621] [Chemistry 191]

[0622]

[0623] [Chemistry 192]

[0624]

[0625] [Chemistry 193]

[0626]

[0627] [Chemistry 194]

[0628]

[0629] [Chemistry 195]

[0630]

[0631] The aforementioned non-nucleophilic counter ion can use a fluorobenzenesulfonic acid 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 No. 2021-70692, an anion having a cyclic ether group as described in Japanese Patent Application No. 2018-180525 and Japanese Patent Application No. 2021-35935, and an anion as described in Japanese Patent Application No. 2018-92159.

[0632] The aforementioned non-nucleophilic counter ions may further include anions of bulky benzenesulfonic acid derivatives not containing fluorine atoms as described in Japanese Patent Application Publication Nos. 2006-276759, 2015-117200, 2016-65016, and 2019-202974, 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.

[0633] The aforementioned non-nucleophilic counter ion may further include anions of disulfonic acids described in JP-A-2015-206932, anions of sulfonic acids on one side and sulfonamides or sulfonimides different therefrom described in WO2020 / 158366, and anions of sulfonic acids on one side and carboxylic acids on the other side described in JP-A-2015-24989.

[0634] In formula (C2) and (C3), L is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate bond, a carbonate bond or a carbamate bond. Among these, an ether bond, an ester bond and a carbonyl group are more preferred from the viewpoint of synthesis, and an ester bond and a carbonyl group are more preferred.

[0635] In formula (C2), Rf 1 and Rf 2Each independently represents a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms. 1 and Rf 2 In order to increase the acid strength of the generated acid, it is preferred that they are all fluorine atoms. 3 and Rf 4 Each independently represents a hydrogen atom, a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms. Among these, Rf 3 and Rf 4 Preferably, at least one of them is trifluoromethyl.

[0636] In formula (C3), Rf 5 and Rf 6 Each independently represents a hydrogen atom, a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms. 5 and Rf 6 At the same time, it becomes a hydrogen atom. Among these, in order to improve the solvent solubility, Rf 5 and Rf 6 Preferably, at least one of them is trifluoromethyl.

[0637] In formulae (C2) and (C3), k1 and k2 are each independently an integer of 0 to 3, and 1 is preferably an integer.

[0638] Specific examples of anions of the repeating unit C2 include, but are not limited to, the following. A Same as above.

[0639] [Chemistry 196]

[0640]

[0641] [Chemistry 197]

[0642]

[0643] [Chemistry 198]

[0644]

[0645] [Chemistry 199]

[0646]

[0647] [Chemistry 200]

[0648]

[0649] [Chemistry 201]

[0650]

[0651] [Chemistry 202]

[0652]

[0653] Specific examples of anions of the repeating unit C3 include, but are not limited to, the following. A Same as above.

[0654] [Chemistry 203]

[0655]

[0656] [Chemistry 204]

[0657]

[0658] [Chemistry 205]

[0659]

[0660] [Chemistry 206]

[0661]

[0662] [Chemistry 207]

[0663]

[0664] [Chemistry 208]

[0665]

[0666] [Chemistry 209]

[0667]

[0668] Specific examples of anions of the repeating unit represented by formula (C4) include, but are not limited to, the following. A Same as above.

[0669] [Chemistry 210]

[0670]

[0671] In formulas (C2) to (C4), A + 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).

[0672] [Chemistry 211]

[0673]

[0674] In formula (cation-1) and (cation-2), Rct1 ~R ct5 Each is independently a halogen atom or a hydrocarbon group having 1 to 30 carbon atoms which may contain a hetero atom.

[0675] R ct1 ~R ct5 Examples of the halogen atom represented by include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0676] R ct1 ~R ct5 The hydrocarbon group represented by may be saturated or unsaturated, and may be straight-chain, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 30 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl; cyclic saturated hydrocarbon groups having 3 to 30 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups having 2 to 30 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl; cyclic unsaturated hydrocarbon groups having 3 to 30 carbon atoms, such as cyclohexenyl; aryl groups having 6 to 30 carbon atoms, such as phenyl, naphthyl, and thienyl; aralkyl groups having 7 to 30 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl; and groups obtained by combining them, among which aryl groups are preferred. Furthermore, a part of the hydrogen atoms of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and a part of the -CH2- of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, the hydrocarbon group may contain a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, and the like.

[0677] Again, R ct1 and R ct2 They may be bonded to each other and form a ring together with the sulfur atom to which they are bonded. In this case, the structure of the ring may be represented by the following formula.

[0678] [Chemistry 212]

[0679]

[0680] In the formula, the chain line is and R ct3 of atomic bonds.

[0681] Specific examples of the sulfonium cation represented by the formula (cation-1) include the following, but are not limited thereto.

[0682] [Chemistry 213]

[0683]

[0684] [Chemistry 214]

[0685]

[0686] [Chemistry 215]

[0687]

[0688] [Chemistry 216]

[0689]

[0690] [Chemistry 217]

[0691]

[0692] [Chemistry 218]

[0693]

[0694] [Chemistry 219]

[0695]

[0696] [Chemistry 220]

[0697]

[0698] [Chemistry 221]

[0699]

[0700] [Chemistry 222]

[0701]

[0702] [Chemistry 223]

[0703]

[0704] [Chemistry 224]

[0705]

[0706] [Chemistry 225]

[0707]

[0708] [Chemistry 226]

[0709]

[0710] [Chemistry 227]

[0711]

[0712] [Chemistry 228]

[0713]

[0714] [Chemistry 229]

[0715]

[0716] [Chemistry 230]

[0717]

[0718] [Chemistry 231]

[0719]

[0720] [Chemistry 232]

[0721]

[0722] [Chemistry 233]

[0723]

[0724] [Chemistry 234]

[0725]

[0726] [Chemistry 235]

[0727]

[0728] [Chemistry 236]

[0729]

[0730] [Chemistry 237]

[0731]

[0732] [Chemistry 238]

[0733]

[0734] Specific examples of the iodonium cation represented by the formula (cation-2) include the following, but are not limited thereto.

[0735] [Chemistry 239]

[0736]

[0737] [Chemistry 240]

[0738]

[0739] The specific structure of the repeating units C1 to C4 is, for example, any combination of the aforementioned anions and cations.

[0740] Among the repeating units C1 to C4, the unit that is more ideal for processing the blank photomask is, for example, the repeating unit C2 or C3, from the viewpoint of the optimum acid strength in designing the acid-labile group of the polymer.

[0741] Repeating units C1 to C4 are units that generate acid when exposed to high-energy rays. By including these units in the polymer, it is believed that acid diffusion is moderately suppressed, and a pattern with reduced LER can be obtained. In addition, by including these units in the polymer, when baking in a vacuum, the phenomenon that the acid volatilizes from the exposed part and re-attaches to the unexposed part is suppressed, which is believed to be effective in reducing LER and reducing the shape degradation caused by the unexpected film loss in the unexposed part.

[0742] When the polymer contains repeating units C1 to C4, the content thereof is preferably 0.1 to 30 mol %, more preferably 0.5 to 20 mol % of all repeating units of the polymer. The repeating units C1 to C4 may be used alone or in combination of two or more.

[0743] The content of repeating units having an aromatic ring skeleton in all repeating units of the above polymer is preferably 65 mol% or more, more preferably 75 mol% or more, and even more preferably 85 mol% or more. When repeating units C1 to C4 are not contained, all units preferably have an aromatic ring skeleton.

[0744] Among all the repeating units of the aforementioned polymer, the content of repeating unit A1 and at least one selected from repeating unit A2, repeating unit A3-1, repeating unit A3-2 and repeating units B1 to B3 is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more.

[0745] The aforementioned polymer can be synthesized by copolymerizing the monomers that give the aforementioned repeating unit using a known method. In addition, the aforementioned monomer can also be protected by a protecting group. In this case, the aforementioned polymer can be synthesized by performing a deprotection reaction after polymerization. The copolymerization reaction is not particularly limited, and is preferably free radical polymerization or anionic polymerization. For these methods, reference can be made to Japanese Patent Publication No. 2004-115630.

[0746] Furthermore, the aforementioned polymer can also be synthesized by copolymerizing monomers that do not contain a monomer that gives repeating unit a1 but contain a monomer that gives repeating unit A2 to synthesize a polymer, and then protecting the aromatic hydroxyl group of the polymer with an acetal group. This method includes a method using vinyl ether and an acid catalyst, a method using an acetalizing agent having a haloalkoxy group and a base, etc., which are known and can be used here.

[0747] For example, when the method uses an acetal modifier (vinyl ether) represented by formula (AC-1) and an acid catalyst, specific examples of the acid catalyst include hydrochloric acid, sulfuric acid, nitric acid, methanesulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, trifluoroacetic acid, oxalic acid, pyridinium methanesulfonate, etc. The reaction temperature is preferably 5°C to 30°C, and the reaction time is preferably 0.2 to 10 hours, more preferably 0.5 to 6 hours.

[0748] In addition, in the method of using the acetal modifier represented by formula (AC-2) (acetalizing agent having a haloalkoxy group) and a base simultaneously, the acetalizing agent having a haloalkoxy group is added dropwise in the presence of a basic compound such as triethylamine, diisopropylethylamine, pyridine, 2,6-lutidine, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, cesium carbonate, etc. The reaction temperature is preferably -20 to 50°C, and the reaction time is preferably 0.2 to 10 hours, more preferably 0.5 to 6 hours.

[0749] However, the method of using an acetalizing agent having a haloalkoxy group and a base simultaneously may generate a corrosive strong acid such as hydrochloric acid and corrode a metal manufacturing kettle and piping, thereby causing metal component contamination that may cause defects in semiconductor products. In particular, the advanced generation requires that the metal impurities in the raw materials used in the resist composition be less than 10 ppb, so the method using vinyl ether and an acid catalyst is preferred.

[0750] The weight average molecular weight (Mw) of the aforementioned polymer is preferably 1000 to 50000, and more preferably 2000 to 20000. If the Mw is 1000 or more, there will be no risk of the phenomenon that the top of the pattern becomes rounded, the resolution is reduced, and the LER deteriorates as is known in the past. On the other hand, if the Mw is 50000 or less, there is no risk of LER deterioration, especially when forming a pattern with a line width of 100 nm or less. In addition, in the present invention, Mw is a polystyrene-converted measurement value obtained by gel permeation chromatography (GPC) using tetrahydrofuran (THF) or dimethylformamide (DMF) as a solvent.

[0751] 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. As described above, when the molecular weight distribution is narrow, no foreign matter will appear on the pattern after development, and the shape of the pattern will not deteriorate.

[0752] [Chemically amplified positive resist composition]

[0753] The chemically amplified positive resist composition of the present invention contains a base polymer including the above-mentioned polymer. In the above-mentioned polymer, when a deprotection reaction caused by an acid proceeds, an aromatic hydroxyl group is generated. Since the acidity of the aromatic hydroxyl group is higher than that of the aliphatic hydroxyl group, when a resist film is formed using the positive resist composition and developed with an alkaline developer, the dissolution contrast between the exposed part and the unexposed part is high, thereby obtaining good resolution.

[0754] The aforementioned base polymer may contain only the aforementioned polymer, or may contain the aforementioned polymer and further contain other polymers. For example, the other polymers include repeating units A3-1 and / or A3-2, and at least one selected from repeating units A2, B1 to B3, and C1 to C4, repeating units having known acid-labile groups such as tertiary alkyl groups and tert-butoxycarbonyl groups, and at least one selected from repeating units A2, B1 to B3, and C1 to C4. In order to exert the effect of the present invention, it is preferred that the proportion of polymers containing repeating units A1 in all the base polymers contained in the resist composition is 30% or more.

[0755] When the aforementioned base polymer contains the aforementioned polymer and further contains other polymers, the content of repeating unit A1 is preferably 10 to 40 mol% of all repeating units of the polymer contained in the entire base polymer, more preferably 10 to 35 mol%, and more preferably 20 to 30 mol%. The content of repeating unit A2 is preferably 30 to 90 mol% of all repeating units of the polymer contained in the entire base polymer, and more preferably 40 to 85 mol%. However, when at least one of the repeating units represented by formula (B1) and the repeating unit represented by formula (B2) is contained and this unit has a phenolic hydroxyl group as a substituent, it is preferable to also add this ratio and it is preferably within the aforementioned range. The content of repeating units B1 to B3 is preferably 5 mol% or more of all repeating units of the polymer contained in the entire base polymer, and the upper limit is preferably 25 mol% or less, and more preferably 20 mol% or less. The content of repeating units B4 to B6 is preferably 0 to 20 mol% of all repeating units of the polymer contained in the aforementioned base polymer, and more preferably 0 to 10 mol%. The content of the repeating units C1 to C4 is preferably 0.1 to 30 mol%, more preferably 0.5 to 20 mol%, based on all the repeating units of the polymer contained in the entire base polymer.

[0756] The content of repeating units having an aromatic ring skeleton in all repeating units of the polymer contained in the entire base polymer is preferably 65 mol% or more, more preferably 75 mol% or more, and even more preferably 85 mol% or more. When repeating units C1 to C4 are not contained, it is preferred that all units have an aromatic ring skeleton.

[0757] Among all the repeating units of the polymer contained in the entire base polymer, the content of repeating unit A1 and at least one selected from repeating unit A2, repeating unit A3-1, repeating unit A3-2 and repeating units B1 to B3 is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more.

[0758] In terms of the above-mentioned base polymer design, the dissolution rate of the base polymer in the 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 range (less than 100 nm), the influence of the pattern film loss on the alkaline development is increased. When the alkaline dissolution rate of the polymer is greater than 10 nm / min, the pattern will collapse and it is impossible to form a fine pattern. In particular, in the production of photomasks requiring zero defects, the development process has a strong tendency and is therefore significant. In addition, in the present invention, the dissolution rate of the base polymer in the alkaline developer is the value calculated from the film loss amount when the 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, and a film with a film thickness of 1000 nm is formed, and then developed at 23°C for 100 seconds with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution.

[0759] The reason why the present invention obtains high resolution due to the acid-labile group derived from the acetal modifier having a cyclic saturated heterocycle containing an oxygen atom or a sulfur atom is that in the unexposed part, the heteroatom derived from the oxygen atom or the sulfur atom in the cyclic saturated heterocycle has a moderate affinity with the proton generating the acid, and thus acts as an acid diffusion inhibiting group, and the etching resistance after pattern formation is improved due to the cyclic structure. On the other hand, in the exposed part, the acid-detaching reactivity is high due to the acetal structure showing sensitive reactivity to the acid, and the alcohol having the cyclic saturated heterocycle generated after the acid-detaching reaction is hydrophilic, so that the exposed part can be developed without leaving residue during alkali development, thereby improving the contrast between the exposed part and the unexposed part. Due to these synergistic effects, good resolution can be obtained even in positive fine pattern formation by alkali development, and it can be advantageously used in photomask processing of a generation finer than the 10nm node.

[0760] [Organic solvents]

[0761] The chemically amplified positive resist composition of the present invention may also contain an organic solvent. The organic solvent is not particularly limited as long as it can dissolve the components. Such organic solvents include, for example, ketones such as cyclohexanone and methyl-2-n-pentyl ketone described in paragraphs

[0144] to

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

[0762] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, PGME, cyclohexanone, EL, γ-butyrolactone, and mixed solvents thereof are preferred.

[0763] When the chemically amplified positive resist composition of the present invention contains the organic solvent, its content is preferably 200 to 10,000 parts by mass, more preferably 400 to 5,000 parts by mass, relative to 80 parts by mass of the base polymer. The organic solvent may be used alone or in combination of two or more.

[0764] [Photoacid generator]

[0765] The chemically amplified positive resist composition of the present invention may also contain a photoacid generator. The photoacid generator is not particularly limited as long as it is a compound that generates acid when irradiated with high-energy rays. Preferred photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, oxime-O-sulfonate type acid generators, and the like.

[0766] Specific examples of the photoacid generator include nonafluorobutane sulfonate, partially fluorinated sulfonates described in paragraphs

[0247] to

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

[0261] to

[0265] of Japanese Patent Application Laid-Open No. 2013-101271, paragraphs

[0122] to

[0142] of Japanese Patent Application Laid-Open No. 2008-111103, and paragraphs

[0080] to

[0081] of Japanese Patent Application Laid-Open No. 2010-215608. Among the above specific examples, aryl sulfonate-type or alkane sulfonate-type photoacid generators are preferred because they generate an acid of moderate strength to deprotect the acid-labile group of the repeating unit A1.

[0767] Such a photoacid generator is preferably a salt compound containing the following anions, for example.

[0768] [Chemistry 241]

[0769]

[0770] [Chemistry 242]

[0771]

[0772] [Chemistry 243]

[0773]

[0774] [Chemistry 244]

[0775]

[0776] [Chemistry 245]

[0777]

[0778] [Chemistry 246]

[0779]

[0780] [Chemistry 247]

[0781]

[0782] [Chemistry 248]

[0783]

[0784] [Chemistry 249]

[0785]

[0786] [Chemistry 250]

[0787]

[0788] [Chemistry 251]

[0789]

[0790] [Chemistry 252]

[0791]

[0792] [Chemistry 253]

[0793]

[0794] [Chemistry 254]

[0795]

[0796] [Chemistry 255]

[0797]

[0798] [Chemistry 256]

[0799]

[0800] [Chemistry 257]

[0801]

[0802] [Chemistry 258]

[0803]

[0804] [Chemistry 259]

[0805]

[0806] [Chemistry 260]

[0807]

[0808] [Chemistry 261]

[0809]

[0810] [Chemistry 262]

[0811]

[0812] [Chemistry 263]

[0813]

[0814] [Chemistry 264]

[0815]

[0816] [Chemistry 265]

[0817]

[0818] [Chemistry 266]

[0819]

[0820] [Chemistry 267]

[0821]

[0822] [Chemistry 268]

[0823]

[0824] [Chemistry 269]

[0825]

[0826] [Chemistry 270]

[0827]

[0828] [Chemistry 271]

[0829]

[0830] [Chemistry 272]

[0831]

[0832] [Chemistry 273]

[0833]

[0834] [Chemistry 274]

[0835]

[0836] [Chemistry 275]

[0837]

[0838] [Chemistry 276]

[0839]

[0840] [Chemistry 277]

[0841]

[0842] [Chemistry 278]

[0843]

[0844] [Chemistry 279]

[0845]

[0846] [Chemistry 280]

[0847]

[0848] [Chemistry 281]

[0849]

[0850] [Chemistry 282]

[0851]

[0852] [Chemistry 283]

[0853]

[0854] [Chemistry 284]

[0855]

[0856] [Chemistry 285]

[0857]

[0858] [Chemistry 286]

[0859]

[0860] [Chemistry 287]

[0861]

[0862] [Chemistry 288]

[0863]

[0864] [Chemistry 289]

[0865]

[0866] [Chemistry 290]

[0867]

[0868] [Chemistry 291]

[0869]

[0870] [Chemistry 292]

[0871]

[0872] [Chemistry 293]

[0873]

[0874] [Chemistry 294]

[0875]

[0876] [Chemistry 295]

[0877]

[0878] [Chemistry 296]

[0879]

[0880] [Chemistry 297]

[0881]

[0882] [Chemistry 298]

[0883]

[0884] [Chemistry 299]

[0885]

[0886] [Chemistry 300]

[0887]

[0888] [Chemistry 301]

[0889]

[0890] Furthermore, the photoacid generator is preferably a salt compound containing an anion represented by the following formula (P1).

[0891] [Chemistry 302]

[0892]

[0893] In formula (P1), m1 is 0 or 1. p is an integer of 1 to 3. q is an integer of 1 to 5. r is an integer of 0 to 3.

[0894] In formula (P1), L 1 It is a single bond, an ether bond, an ester bond, a sulfonate bond, a carbonate bond or a carbamate bond.

[0895] In formula (P1), L 2 It is an ether bond, an ester bond, a sulfonate bond, a carbonate bond or a carbamate bond.

[0896] In formula (P1), L A When p is 1, it is a single bond or an alkylene group having 1 to 20 carbon atoms; when p is 2 or 3, it is a (p+1)-valent hydrocarbon group having 1 to 20 carbon atoms. The alkylene group and the (p+1)-valent hydrocarbon group may also contain at least one selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxyl group and a carboxyl group.

[0897] L A The alkylene group having 1 to 20 carbon atoms may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkanediyl groups having 1 to 20 carbon atoms, such as methanediyl, ethane-1,1-diyl, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, nonane-1,9-diyl, decane-1,10-diyl, undecane-1,11-diyl, and dodecane-1,12-diyl; cyclic saturated alkylene groups having 3 to 20 carbon atoms, such as cyclopentanediyl, cyclohexanediyl, norbornanediyl, and adamantanediyl; unsaturated aliphatic alkylene groups having 2 to 20 carbon atoms, such as vinylene and propylene-1,3-diyl; arylene groups having 6 to 20 carbon atoms, such as phenylene and naphthylene; and groups obtained by combining these. In addition, L A The (p+1)-valent hydrocarbon group having 1 to 20 carbon atoms represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include groups obtained by removing one or two hydrogen atoms from the above-mentioned specific examples of the hydrocarbon group having 1 to 20 carbon atoms.

[0898] In formula (P1), Rf 1 and Rf 2 Each is independently a hydrogen atom, a fluorine atom or a trifluoromethyl group, and at least one is a fluorine atom or a trifluoromethyl group.

[0899] In formula (P1), R 101 is a hydroxyl group, a carboxyl group, a saturated hydrocarbon group having 1 to 6 carbon atoms, a saturated hydrocarbon oxy group having 1 to 6 carbon atoms, a saturated hydrocarbon carbonyloxy group having 2 to 6 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, -N(R 101A )(R 101B )、-N(R 101C )-C(=O)-R 101D or -N(R 101C )-C(=O)-OR 101D . R 101A and R 101B Each R is independently a hydrogen atom or a saturated hydrocarbon group having 1 to 6 carbon atoms. 101C is a hydrogen atom or a saturated hydrocarbon group having 1 to 6 carbon atoms. 101DIt is a saturated hydrocarbon group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbon group having 2 to 8 carbon atoms.

[0900] R 101 , R 101A , R 101B and R 101C The saturated hydrocarbon group having 1 to 6 carbon atoms represented by may be straight-chain, 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; and cyclic saturated hydrocarbon groups having 3 to 6 carbon atoms such as cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl. 101 The saturated hydrocarbon group of the saturated hydrocarbonoxy group having 1 to 6 carbon atoms represented by the formula (R) is the same as the specific examples of the saturated hydrocarbon group described above. 101 The saturated hydrocarbon group part of the saturated hydrocarbon carbonyloxy group having 2 to 6 carbon atoms represented by is, for example, the one having 1 to 5 carbon atoms among the specific examples of the saturated hydrocarbon group having 1 to 6 carbon atoms.

[0901] R 101D The unsaturated aliphatic hydrocarbon group having 2 to 8 carbon atoms represented may be straight-chain, branched or cyclic, and specific examples thereof include alkenyl groups having 2 to 8 carbon atoms such as ethenyl, propenyl, butenyl and hexenyl; alkynyl groups having 2 to 8 carbon atoms such as ethynyl, propynyl and butynyl; and cyclic unsaturated aliphatic hydrocarbon groups having 3 to 8 carbon atoms such as cyclohexenyl and norbornyl.

[0902] In formula (P1), R 102 It is a saturated alkylene group having 1 to 20 carbon atoms or an arylene group having 6 to 20 carbon atoms, and a part or all of the hydrogen atoms of the saturated alkylene group may be substituted by halogen atoms other than fluorine atoms, and a part or all of the hydrogen atoms of the arylene group may be substituted by a substituent selected from a saturated alkyl group having 1 to 20 carbon atoms, a saturated alkoxy group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogen atom and a hydroxyl group.

[0903] R 102 The alkylene group having 1 to 20 carbon atoms represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. A The alkylene groups having 1 to 20 carbon atoms shown in the above-mentioned examples are the same as those exemplified above.

[0904] R 102Specific examples of the arylene group having 6 to 20 carbon atoms include phenylene, naphthylene, phenanthrenediyl, anthracenediyl, etc. The hydrocarbon radical of the saturated hydrocarbon group having 1 to 20 carbon atoms and the hydrocarbonoxy group having 1 to 20 carbon atoms of the arylene group substituent may be straight chain, branched, or cyclic, and specific examples thereof include alkyl groups having 1 to 20 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, undecyl, dodecanyl, tridecyl, tetradecyl, pentadecyl, heptadecanyl, octadecyl, nonadecanyl, eicosyl, etc.; and cyclic saturated hydrocarbon groups having 3 to 20 carbon atoms such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl. Specific examples of the substituent of the arylene group include arylene groups having 6 to 14 carbon atoms, such as phenylene, naphthylene, phenanthrenediyl, and anthracenediyl.

[0905] The anion represented by the formula (P1) is preferably an anion represented by the following formula (P2).

[0906] [Chemistry 303]

[0907]

[0908] In formula (P2), p, q, r, L 1 , L A and R 101 Same as above. m2 is an integer from 1 to 4. 102A is a saturated hydrocarbon group having 1 to 20 carbon atoms, a saturated hydrocarbonoxy group having 1 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, a halogen atom or a hydroxyl group. 102A They may be the same as or different from each other.

[0909] The anion represented by the formula (P1) may be exemplified by the following, but is not limited thereto.

[0910] [Chemistry 304]

[0911]

[0912] [Chemistry 305]

[0913]

[0914] [Chemistry 306]

[0915]

[0916] [Chemistry 307]

[0917]

[0918] [Chemistry 308]

[0919]

[0920] [Chemistry 309]

[0921]

[0922] [Chemistry 310]

[0923]

[0924] [Chemistry 311]

[0925]

[0926] [Chemistry 312]

[0927]

[0928] [Chemistry 313]

[0929]

[0930] [Chemistry 314]

[0931]

[0932] [Chemistry 315]

[0933]

[0934] [Chemistry 316]

[0935]

[0936] [Chemistry 317]

[0937]

[0938] [Chemistry 318]

[0939]

[0940] [Chemistry 319]

[0941]

[0942] [Chemistry 320]

[0943]

[0944] [Chemistry 321]

[0945]

[0946] [Chemistry 322]

[0947]

[0948] [Chemical Formula 323]

[0949]

[0950] [Chemical Formula 324]

[0951]

[0952] [Chemical Formula 325]

[0953]

[0954] [Chemical Formula 326]

[0955]

[0956] [Chemical Formula 327]

[0957]

[0958] [Chemical Formula 328]

[0959]

[0960] [Chemical Formula 329]

[0961]

[0962] [Chemical Formula 330]

[0963]

[0964] [Chemical Formula 331]

[0965]

[0966] [Chemical Formula 332]

[0967]

[0968] [Chemical Formula 333]

[0969]

[0970] [Chemical Formula 334]

[0971]

[0972] [Chemical Formula 335]

[0973]

[0974] [Chemical Formula 336]

[0975]

[0976] [Chemical formula 337]

[0977]

[0978] [Chemical formula 338]

[0979]

[0980] [Chemical formula 339]

[0981]

[0982] [Chemical formula 340]

[0983]

[0984] The cation paired with the aforementioned anion is preferably a sulfonium cation represented by the following formula (P3) or an iodonium cation represented by the following formula (P4).

[0985] [Chemical formula 341]

[0986]

[0987] In formulas (P3) and (P4), R 111 ~R 115 are each independently a halogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may also contain a heteroatom.

[0988] R 111 ~R 115 Examples of the halogen atom represented include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.

[0989] R 111 ~R 115 The hydrocarbon group having 1 to 20 carbon atoms represented 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, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, a tert-pentyl group, a n-hexyl group, a n-octyl group, a 2-ethylhexyl group, a n-nonyl group, a 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, tricyclo[5.2.1.0 2,6] cyclic saturated hydrocarbon groups having 3 to 20 carbon atoms, such as decyl, adamantyl, and adamantylmethyl; aryl groups having 6 to 20 carbon atoms, such as phenyl, naphthyl, and anthracenyl. In addition, part or all of the hydrogen atoms of the aforementioned hydrocarbon groups may be substituted by groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and part of -CH2- of the aforementioned hydrocarbon groups may be substituted by groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms. As a result, hydroxyl groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, carbonyl groups, ether bonds, ester bonds, sulfonate bonds, carbonate bonds, lactone rings, sultone rings, carboxylic anhydride (-C(=O)-OC(=O)-), haloalkyl groups, and the like may be contained.

[0990] Again, R 111 and R 112 They may also be bonded to each other and form a ring together with the sulfur atom to which they are bonded. The ring formed in this case is, for example, the ring shown below. For example, in the description of formula (cation-1), R ct1 and R ct2 The same examples are exemplified as those that can be bonded to each other and to form a ring together with the sulfur atom to which they are bonded.

[0991] Specific examples of the sulfonium cation represented by formula (P3) are the same as those exemplified for the sulfonium cation represented by formula (cation-1), but are not limited thereto. Specific examples of the iodonium cation represented by formula (P4) are the same as those exemplified for the iodonium cation represented by formula (cation-2), but are not limited thereto.

[0992] The acid generated by the photoacid generator preferably has a pKa of -2.0 or more, and 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 of the software ACD / Chemsketch ver: 9.04 manufactured by Advanced Chemistry Development, Inc. If the chemically amplified positive resist composition contains such a photoacid generator, it will catalyze the deprotection reaction of the acid-labile group of the polymer, and the resolution will become good.

[0993] When the chemically amplified positive resist composition of the present invention contains a photoacid generator, its content is preferably 1 to 30 parts by weight, more preferably 2 to 20 parts by weight, relative to 80 parts by weight of the base polymer. The photoacid generator may be used alone or in combination of two or more.

[0994] [Quencher]

[0995] The chemically amplified positive resist composition of the present invention preferably contains a quencher (acid diffusion inhibitor). The quencher is, for example, a known basic compound. Known basic compounds include, for example, primary, secondary, and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having carboxyl groups, nitrogen-containing compounds having sulfonyl groups, nitrogen-containing compounds having hydroxyl groups, nitrogen-containing compounds having hydroxyphenyl groups, alcoholic nitrogen-containing compounds, amides, imides, and carbamates. In particular, the primary, secondary, and tertiary amine compounds described in paragraphs

[0146] to

[0164] of Japanese Patent Publication No. 2008-111103, especially amine compounds having hydroxyl groups, ether bonds, ester bonds, lactone rings, cyano groups, and sulfonate ester bonds, or compounds having carbamate groups described in Japanese Patent Publication No. 3790649 are preferred. For example, tris[2-(methoxymethoxy)ethyl]amine, tris[2-(methoxymethoxy)ethyl]amine-N-oxide, dibutylaminobenzoic acid, morpholine derivatives, imidazole derivatives, etc. are preferred. By adding such a basic compound, for example, the diffusion rate of the acid in the resist film can be further suppressed or the shape can be corrected.

[0996] The quencher is, for example, 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 Japanese Patent Application Laid-Open No. 2008-158339. The sulfonic acid, imidic acid, or methylated acid fluorinated at the α-position is necessary for deprotecting the acid-labile group, but the carboxylic acid not fluorinated at the α-position is released by salt exchange with the onium salt not fluorinated at the α-position. The carboxylic acid not fluorinated at the α-position hardly undergoes a deprotection reaction, and thus acts as a quencher.

[0997] The onium salt of carboxylic acid which is not fluorinated at the α-position is, for example, an onium salt represented by the following formula (Q1).

[0998] [Chemistry 342]

[0999] R 201 —CO2 - Mq A 十 (Q1)

[1000] In formula (Q1), R 201 It is a hydrocarbon group having 1 to 40 carbon atoms which may contain a hydrogen atom or a heteroatom, but does not include a case where the hydrogen atom bonded to the carbon atom at the α-position of the carboxyl group is substituted by a fluorine atom or a fluoroalkyl group.

[1001] R 201The hydrocarbon group represented by may be saturated or unsaturated, and may be straight-chain, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 40 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, tricyclo[5.2.1.0 2,6 ] Cyclic saturated hydrocarbon groups having 3 to 40 carbon atoms, such as decyl, adamantyl, and adamantylmethyl; alkenyl groups having 2 to 40 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl; cyclic unsaturated aliphatic hydrocarbon groups having 3 to 40 carbon atoms, such as cyclohexenyl; aryl groups having 6 to 40 carbon atoms, such as phenyl, naphthyl, alkylphenyl (2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 4-ethylphenyl, 4-tert-butylphenyl, 4-n-butylphenyl, etc.), di- or trialkylphenyl (2,4-dimethylphenyl, 2,4,6-triisopropylphenyl, etc.), alkylnaphthyl (methylnaphthyl, ethylnaphthyl, etc.), dialkylnaphthyl (dimethylnaphthyl, diethylnaphthyl, etc.); aralkyl groups having 7 to 40 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl, etc.

[1002] Furthermore, a part or all of the hydrogen atoms of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and a part of the -CH2- of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, it may contain a hydroxyl group, a cyano group, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonate bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, and the like. A hydrocarbon group containing a heteroatom, for example, a heteroaryl group such as a thienyl group; an alkoxyphenyl group such as 4-hydroxyphenyl, 4-methoxyphenyl, 3-methoxyphenyl, 2-methoxyphenyl, 4-ethoxyphenyl, 4-tert-butoxyphenyl, 3-tert-butoxyphenyl; an alkoxynaphthyl group such as a methoxynaphthyl, ethoxynaphthyl, n-propoxynaphthyl, n-butoxynaphthyl; a dialkoxynaphthyl group such as a dimethoxynaphthyl, diethoxynaphthyl; an aryloxyalkyl group such as a 2-aryl-2-oxoethyl group such as a 2-phenyl-2-oxoethyl group, a 2-(1-naphthyl)-2-oxoethyl group, a 2-(2-naphthyl)-2-oxoethyl group, and the like.

[1003] In formula (Q1), Mq A +is an onium cation. It is preferable that the onium cation is a sulfonium cation, an iodonium cation or an ammonium cation, and more preferably a sulfonium cation or an iodonium cation. Specific examples of the sulfonium cation are the same as those exemplified for the sulfonium cation represented by the formula (cation-1). Specific examples of the iodonium cation are the same as those exemplified for the iodonium cation represented by the formula (cation-2).

[1004] The anions of the onium salt represented by the formula (Q1) are exemplified below, but are not limited thereto.

[1005] [Chemical formula 343]

[1006]

[1007] [Chemical formula 344]

[1008]

[1009] [Chemical formula 345]

[1010]

[1011] The quencher is also preferably a sulfonium salt of a benzenecarboxylic acid containing an iodobenzene ring represented by the following formula (Q2).

[1012] [Chemical formula 346]

[1013]

[1014] In the formula (Q2), s is an integer of 1 to 5. t is an integer of 0 to 3. However, 1 ≤ s + t ≤ 5. u is an integer of 1 to 3.

[1015] In the formula (Q2), R 211 is a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an amino group, a nitro group, a cyano group, or a saturated hydrocarbon group having 1 to 6 carbon atoms, a saturated hydrocarbon oxy group having 1 to 6 carbon atoms, a saturated hydrocarbon carbonyloxy group having 2 to 6 carbon atoms, or a saturated hydrocarbon sulfonyloxy group having 1 to 4 carbon atoms, in which part or all of the hydrogen atoms may be substituted by halogen atoms, or -N(R 211A )-C(=O)-R 211B or -N(R 211A )-C(=O)-O-R 211B . R 211A is a hydrogen atom or a saturated hydrocarbon group having 1 to 6 carbon atoms. R 221B is a saturated hydrocarbon group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbon 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.

[1016] In the formula (Q2), L 21It is a single bond or a (u+1)-valent linking group having 1 to 20 carbon atoms, and may contain at least one selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxyl group, and a carboxyl group. The saturated hydrocarbon group, saturated hydrocarbon oxy group, saturated hydrocarbon carbonyloxy group, and saturated hydrocarbon sulfonyloxy group may be straight-chain, branched, or cyclic.

[1017] In formula (Q2), R 212 , R 213 and R 214 Each is independently a halogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. The aforementioned hydrocarbon group may be saturated or unsaturated, and may be straight-chain, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms, alkenyl groups having 2 to 20 carbon atoms, aryl groups having 6 to 20 carbon atoms, and aralkyl groups having 7 to 20 carbon atoms. Furthermore, a part or all of the hydrogen atoms of the aforementioned hydrocarbon group may be substituted by a hydroxyl group, a carboxyl group, a halogen atom, an oxo group, a cyano group, a nitro group, a sultone ring, a sulfonium group, or a group containing a sulfonium salt, and a part of the -CH2- of the aforementioned hydrocarbon group may be substituted by an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate bond, or a sulfonate bond. Furthermore, R 212 and R 213 They may also bond to each other and to the sulfur atom to which they are bonded to form a ring.

[1018] Specific examples of the compound represented by formula (Q2) include examples described in Japanese Patent Application Laid-Open No. 2017-219836. The compound represented by formula (Q2) has high absorption, high sensitization effect, and high acid diffusion control effect.

[1019] As the quencher, a carboxylate type compound containing a nitrogen atom represented by the following formula (Q3) may be used.

[1020] [Chemistry 347]

[1021]

[1022] In formula (Q3), R 221 ~R 224 are each independently a hydrogen atom, -L 22 -CO2 - , or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom. 221 With R 222 , R 222 With R 223 , or R 223 With R 224 They may also bond to each other and to the carbon atoms to which they are bonded to form a ring. 22 R is a single bond or an alkylene group having 1 to 20 carbon atoms which may contain a hetero atom. 225 It is a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom.

[1023] In formula (Q3), ring R r The carbon atoms and nitrogen atoms in the formula are included in a ring having 2 to 6 carbon atoms, and some or all of the hydrogen atoms bonded to the carbon atoms of the ring may be replaced by a hydrocarbon group having 1 to 20 carbon atoms, or -L 22 -CO2 - The ring may be substituted, and part of the carbon atoms of the ring may be substituted by sulfur atoms, oxygen atoms or nitrogen atoms. The aforementioned ring may be an alicyclic ring or an aromatic ring, and a 5-membered ring or a 6-membered ring is preferred, 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, a triazole ring, and the like.

[1024] The carboxylic acid onium salt represented by formula (Q3) has at least one -L 22 -CO2 - That is, R 221 ~R 224 At least one of them is -L 22 -CO2 - , and / or ring R r At least one of the hydrogen atoms bonded to the carbon atom is replaced by -L 22 -CO2 - replace.

[1025] In formula (Q3), Mq B + It is a sulfonium cation, an iodonium cation or an ammonium cation, and the sulfonium cation is preferred. Specific examples of the sulfonium cation are the same as those exemplified for the specific examples of the sulfonium cation in formulas (C2) to (C4).

[1026] The anion of the compound represented by the formula (Q3) can be exemplified by the following, but is not limited thereto.

[1027] [Chemistry 348]

[1028]

[1029] [Chemistry 349]

[1030]

[1031] [Chemistry 350]

[1032]

[1033] [Chemistry 351]

[1034]

[1035] [Chemistry 352]

[1036]

[1037] [Chemistry 353]

[1038]

[1039] Furthermore, the aforementioned quencher may also be a weakly acidic betaine-type compound, and specific examples thereof include the following, but are not limited thereto.

[1040] [Chemistry 354]

[1041]

[1042] The aforementioned quencher may further include polymer quenchers described in Japanese Patent Application Publication No. 2008-239918. By being aligned on the surface of the resist film, the rectangularity of the resist pattern is improved. The polymer quencher also has the effect of preventing film loss of the pattern and rounding of the pattern top when a protective film for wet exposure is used.

[1043] When the chemically amplified positive resist composition of the present invention contains a quencher, its content is preferably 0 to 50 parts by weight, more preferably 0.1 to 40 parts by weight, relative to 80 parts by weight of the base polymer. The quencher may be used alone or in combination of two or more.

[1044] 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 more preferably less than 2 in terms of mass ratio. If 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 controlled, and excellent resolution and dimensional uniformity can be obtained.

[1045] [Fluorine-containing polymer]

[1046] The chemically amplified positive resist composition of the present invention may contain at least one fluorine-containing polymer selected from the group consisting of a repeating unit represented by the following formula (D1) (hereinafter also referred to as repeating unit D1), a repeating unit represented by the following formula (D2) (hereinafter also referred to as repeating unit D2), a repeating unit represented by the following formula (D3) (hereinafter also referred to as repeating unit D3) and a repeating unit represented by the following formula (D4) (hereinafter also referred to as repeating unit D4) in order to achieve high contrast, shield chemical flash of acid during high-energy ray irradiation, and mixing of acid from the antistatic film during the process of coating the antistatic film material on the resist film, and suppress unexpected and undesirable pattern degradation. The fluorine-containing polymer also has a surfactant effect, so it can prevent the insoluble matter that may be generated during the development process from re-attaching to the substrate, and thus it also has an effect on development defects.

[1047] [Chemistry 355]

[1048]

[1049] In formulas (D1) to (D4), R B R is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 301 , R 302 , R 304 and R 305 Each R is independently a hydrogen atom or a saturated hydrocarbon group having 1 to 10 carbon atoms. 303 , R 306 , R 307 and R 308 are each independently a hydrogen atom, a hydrocarbon group having 1 to 15 carbon atoms, a fluorinated hydrocarbon group having 1 to 15 carbon atoms, or an acid-labile group, and R 303 , R 306 , R 307 and R 308 When it is a hydrocarbon group or a fluorinated hydrocarbon group, an ether bond or a carbonyl group may be inserted between carbon-carbon bonds. n is an integer of 1 to 3. 1 It is an (n+1)-valent hydrocarbon group having 1 to 20 carbon atoms or an (n+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms.

[1050] R 301 , R 302 , R 304 and R 305 The saturated hydrocarbon group having 1 to 10 carbon atoms represented by , for example, alkyl groups having 1 to 10 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl; cyclic saturated hydrocarbon groups having 3 to 10 carbon atoms such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, and norbornyl. Among these, saturated hydrocarbon groups having 1 to 6 carbon atoms are preferred.

[1051] R303 , R 306 , R 307 and R 308 The hydrocarbon group having 1 to 15 carbon atoms represented by , for example, alkyl having 1 to 15 carbon atoms, alkenyl having 2 to 15 carbon atoms, alkynyl having 2 to 15 carbon atoms, etc., but alkyl having 1 to 15 carbon atoms is preferred. The aforementioned alkyl group, in addition to the aforementioned, may be methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, etc. In addition, a fluorinated hydrocarbon group may be a group in which a part or all of the hydrogen atoms bonded to the carbon atoms of the aforementioned hydrocarbon group are substituted with fluorine atoms.

[1052] Z 1 The (n+1)-valent hydrocarbon group having 1 to 20 carbon atoms represented by is a group obtained by removing n hydrogen atoms from an alkyl group having 1 to 20 carbon atoms or a cyclic saturated hydrocarbon group having 3 to 20 carbon atoms. 1 The (n+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by is, for example, a group in which at least one hydrogen atom of the aforementioned (n+1)-valent hydrocarbon group is substituted with a fluorine atom.

[1053] Specific examples of repeating units D1 to D4 are listed below, but are not limited thereto. B Same as above.

[1054] [Chemistry 356]

[1055]

[1056] [Chemistry 357]

[1057]

[1058] [Chemistry 358]

[1059]

[1060] Furthermore, the fluorine atom-containing polymer preferably further contains at least one selected from the group consisting of a repeating unit represented by the following formula (D5) (hereinafter also referred to as repeating unit D5) and a repeating unit represented by the following formula (D6) (hereinafter also referred to as repeating unit D6).

[1061] [Chemistry 359]

[1062]

[1063] In formula (D5) and (D6), R C Each is independently a hydrogen atom or a methyl group. 309 R is a hydrogen atom or a linear or branched hydrocarbon group having 1 to 5 carbon atoms, which may contain a hetero atom inserted between carbon-carbon bonds.310 It is a linear or branched hydrocarbon group having 1 to 5 carbon atoms, which may contain a hetero atom inserted between carbon-carbon bonds. 311 A saturated hydrocarbon group having 1 to 20 carbon atoms in which at least one hydrogen atom is replaced by a fluorine atom, and a portion of the -CH2- of the saturated hydrocarbon group may be replaced by an ester bond or an ether bond. x is an integer of 1 to 3. y is an integer satisfying 0≤y≤5+2z-x. z is 0 or 1. Z 2 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. 3 is a single bond, -O-, *-C(=O)-OZ 31 -Z 32 - or *-C(=O)-NH-Z 31 -Z 32 -.Z 31 Z is a single bond or a saturated alkylene group having 1 to 10 carbon atoms. 32 It is a single bond, ester bond, ether bond or sulfonamide bond. * It is an atomic bond between the carbon atoms of the main chain.

[1064] R 309 and R 310 The hydrocarbon group having 1 to 5 carbon atoms represented by is, for example, an alkyl group, an alkenyl group, an alkynyl group, etc., and an alkyl group is preferred. The aforementioned alkyl group is, for example, 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, etc. In addition, a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, etc. may be inserted between the carbon-carbon bonds of these groups.

[1065] Again, -OR 309 In this case, R 309 Preferred are hydrogen atoms, alkyl groups having 1 to 5 carbon atoms with an oxygen atom inserted between carbon-carbon bonds, and the like.

[1066] Z 2 It is preferably *-C(=O)-O- or *-C(=O)-NH-. C Preferably, Z is methyl. 2 The presence of carbonyl groups in the antistatic film improves the ability to capture acid from the antistatic film. C When the methyl group is present, a rigid polymer having a higher glass transition temperature (Tg) is formed, and diffusion of acid is suppressed, thereby improving the stability of the resist film over time and preventing degradation of resolution and pattern shape.

[1067] The repeating unit D5 can be listed below, but is not limited thereto. In the following formula, R C Same as above.

[1068] [Chemistry 360]

[1069]

[1070] [Chemistry 361]

[1071]

[1072] Z 3 The saturated alkylene group having 1 to 10 carbon atoms may be straight-chain, branched or cyclic, and specific examples thereof include methanediyl, ethane-1,1-diyl, ethane-1,2-diyl, propane-1,1-diyl, propane-1,2-diyl, propane-1,3-diyl, propane-2,2-diyl, butane-1,1-diyl, butane-1,2-diyl, butane-1,3-diyl, butane-2,3-diyl, butane-1,4-diyl, 1,1-dimethylethane-1,2-diyl and the like.

[1073] R 311 The saturated hydrocarbon group having 1 to 20 carbon atoms in which at least one hydrogen atom is replaced by a fluorine atom may be linear, branched or cyclic, and specific examples thereof include an alkyl group having 1 to 20 carbon atoms or a cyclic saturated hydrocarbon group having 3 to 20 carbon atoms in which at least one hydrogen atom is replaced by a fluorine atom.

[1074] The repeating unit D6 can be listed as follows, but is not limited thereto. In the following formula, R C Same as above.

[1075] [Chemistry 362]

[1076]

[1077] [Chemistry 363]

[1078]

[1079] [Chemistry 364]

[1080]

[1081] [Chemistry 365]

[1082]

[1083] The content of repeating units D1 to D4 is preferably 15 to 95 mol %, more preferably 20 to 85 mol %, of all repeating units of the aforementioned fluorine-containing polymer. The content of repeating units D5 and / or D6 is preferably 5 to 85 mol %, more preferably 15 to 80 mol %, of all repeating units of the aforementioned fluorine-containing polymer. Repeating units D1 to D6 may be used alone or in combination of two or more.

[1084] The fluorine-containing polymer may contain other repeating units other than the above-mentioned repeating units. Such repeating units are described in paragraphs

[0046] to

[0078] of Japanese Patent Publication No. 2014-177407. When the fluorine-containing polymer contains other repeating units, it is preferred that the content of the other repeating units is 50 mol% or less of all the repeating units of the fluorine-containing polymer.

[1085] The fluorine-containing polymer can be synthesized by copolymerizing monomers protected by protective groups as needed using a known method, and then performing a deprotection reaction as needed. The copolymerization reaction is not particularly limited, and is preferably free radical polymerization or anionic polymerization. For these methods, reference can be made to Japanese Patent Publication No. 2004-115630.

[1086] The Mw of the fluorine-containing polymer is preferably 2000 to 50000, more preferably 3000 to 20000. If the Mw is 2000 or more, the acid does not diffuse, the resolution does not deteriorate, and the stability over time is not impaired. If the Mw is 50000 or less, the solubility in the solvent is sufficient and coating defects do not occur. In addition, the Mw / Mn of the fluorine-containing polymer is preferably 1.0 to 2.2, more preferably 1.0 to 1.7.

[1087] When the chemically amplified positive resist composition of the present invention contains the fluorine-containing polymer, its content is preferably 0.01 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, and even more preferably 0.5 to 10 parts by mass based on 80 parts by mass of the base polymer.

[1088] [Surfactant]

[1089] The chemically amplified positive resist composition of the present invention may also contain a conventional surfactant in order to improve the coating properties on the substrate. When a surfactant is used, there are a number of examples as described in Japanese Patent Gazette No. 2004-115630, and a number of examples are known and can be selected with reference to them. The content of the aforementioned surfactant is preferably 0 to 5 parts by mass relative to 80 parts by mass of the aforementioned base polymer. In addition, when the aforementioned fluorine atom-containing polymer is contained in the chemically amplified positive resist composition of the present invention, the aforementioned fluorine atom-containing polymer also plays the role of a surfactant, so the aforementioned surfactant may not be contained.

[1090] The chemically amplified positive resist composition of the present invention can be prepared by dissolving a base polymer and components other than the base polymer as needed in an organic solvent simultaneously or in any order to form a uniform resist solution. The obtained resist solution is preferably filtered. By using nylon or polyethylene (PE) products as filters for filtration, gel components and particles contained in the aforementioned resist solution can be effectively removed. In addition, if the aforementioned filter uses a filter with a pore size of less than 20 nm, it is more ideal in maintaining the quality of the advanced generation.

[1091] The dissolution rate of the resist film obtained from the chemically amplified positive resist composition of the present invention in the unexposed part to the alkaline developer is preferably 10 nm / min or less, more preferably 9 nm / min or less, and even more preferably 8 nm / min or less. When the resist film is a thin film (film thickness is 100 nm or less), the alkaline developer has a great influence on the pattern film loss. Therefore, if the dissolution rate of the unexposed part is 10 nm / min or less, the pattern does not collapse and a fine pattern can be formed. In particular, when a photomask requiring zero defects is produced, the dissolution rate is significant because the development process has a strong tendency. In addition, the dissolution rate of the unexposed part is a value calculated from the film loss amount when the chemically amplified positive resist composition of the present invention is spin-coated on a 150 mm (6 inch) silicon wafer, baked at 110° C. for 240 seconds to form a resist film with a film thickness of 80 nm, and then developed with a 2.38 mass % TMAH aqueous solution at 23° C. for 80 seconds.

[1092] In addition, the dissolution rate of the resist film obtained by the chemically amplified positive resist composition of the present invention in the exposed part to the alkaline developer is preferably 50 nm / sec or more, and more preferably 80 nm / sec or more, from the viewpoint of improving the development load. By being 50 nm / sec or more, even if the pattern layout of the dense and sparse patterns is different, it can still be uniformly dissolved in the alkaline developer, and the line width variation can be small. In addition, the exposure part dissolution rate is a value calculated from the film loss amount when the chemically amplified positive resist composition of the present invention is spin-coated on a 200 mm (8-inch) silicon wafer, baked at 110° C. for 60 seconds to form a resist film with a film thickness of 90 nm, exposed with a KrF excimer laser with energy to complete the deprotection reaction of the polymer, baked at 110° C. for 60 seconds, and developed at 23° C. using a resist development analyzer using a 2.38 mass % TMAH aqueous solution.

[1093] The acetal acid unstable group of the present invention also has the effect of suppressing the influence of backscattering during electron beam drawing, so in the sensitivity range above 50μC, preferably above 80μC, and more preferably above 100μC, the pattern shape will not become reverse-pull-out but will exert rectangular performance.

[1094] [Resist pattern forming method]

[1095] The resist pattern forming method of the present invention comprises the following steps: forming a resist film on a substrate using the aforementioned chemically amplified positive resist composition, irradiating the aforementioned resist film with a pattern using high-energy rays (i.e., exposing the aforementioned resist film with high-energy rays), and developing the aforementioned resist film with the irradiated pattern using an alkaline developer.

[1096] The aforementioned substrate may be, for example, a substrate for integrated circuit manufacturing (Si, SiO, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflection film, etc.), or a substrate for transmissive or reflective mask circuit manufacturing (Cr, CrO, CrON, MoSi2, Si, SiO, SiO2, SiON, SiONC, CoTa, NiTa, TaBN, SnO2, etc.). The aforementioned chemically amplified positive resist composition is applied to the aforementioned substrate by spin coating or the like to make the film thickness 0.03 to 2 μm, and 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.

[1097] Next, the resist film is exposed to light using high-energy radiation and the pattern is irradiated. The high-energy radiation may be, for example, KrF excimer laser, ArF excimer laser, EB or EUV with a wavelength of 3 to 15 nm. In the present invention, EB is preferably used for exposure. In order to form the target pattern, the exposure amount of EB is preferably 50 to 400 μC / cm 2 The resist composition of the present invention, wherein the aforementioned polymer containing an acetal-type acid-labile group also has the effect of suppressing the influence of backscattering during EB drawing, can preferably be irradiated at 50 μC / cm 2 Above, preferably 80μC / cm 2 More than 100 μC / cm 2 In the above sensitivity range, the pattern shape does not become reverse pull-out and exhibits rectangular performance.

[1098] Exposure may be performed by a normal exposure method or, if necessary, by a wetting method in which the space between the mask and the resist film is wetted. In this case, a water-insoluble protective film may be used.

[1099] Next, a post-exposure bake (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.

[1100] Afterwards, a developer containing an alkaline aqueous solution such as TMAH at a concentration of 0.1 to 5% by mass, preferably 2 to 3% by mass, is used, preferably for 0.1 to 3 minutes, more preferably 0.5 to 2 minutes, using conventional methods such as dipping, puddle, and spraying to form a target pattern on the substrate.

[1101] The chemically amplified positive resist composition of the present invention is particularly useful because it can form patterns with good isolated pitch resolution and low LER. In addition, the chemically amplified positive resist composition of the present invention is particularly useful for pattern formation on substrates of materials whose surfaces are difficult to adhere to with resist patterns, and thus pattern peeling and pattern collapse are prone to occur. Such a substrate is preferably one whose outermost layer contains at least one material selected from chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten and tin. Such a substrate is, for example, a substrate on which a film of metallic chromium, a chromium compound containing one or more light elements selected from oxygen, nitrogen and carbon is sputtered on the outermost layer, and a substrate whose outermost layer contains SiO, SiO x , tantalum compounds, molybdenum compounds, cobalt compounds, nickel compounds, tungsten compounds, tin compounds, etc. The chemically amplified positive resist composition of the present invention is particularly useful for pattern formation using a blank photomask as a substrate. In this case, the blank photomask can be either a transmissive or reflective type. That is, a transmissive or reflective blank mask coated with the chemically amplified positive resist composition is preferred.

[1102] Regarding the transmission type blank photomask, the blank photomask with a light shielding film made of a chromium-based material may be either a blank photomask for a binary mask or a blank photomask for a phase shift mask. In the case of a blank photomask for a binary mask, the light shielding film may be one having an anti-reflection layer and a light shielding layer made of a chromium-based material, or the entire anti-reflection film on the surface side or only the more surface side of the anti-reflection film on the surface side may be made of a chromium-based material, and the remaining part may be made of, for example, a silicon-based compound material that may also contain a transition metal. In addition, in the case of a blank photomask for a phase shift mask, a blank photomask for a phase shift mask having a chromium-based light shielding film on the phase shift film may be used as an object.

[1103] The aforementioned blank photomask having a chromium-based material on the outermost layer is very well known, as exemplified in Japanese Patent Gazette No. 2008-026500, Japanese Patent Gazette No. 2007-302873 or any of them in terms of current technology, and a detailed description is omitted. For example, when forming a light-shielding film having an anti-reflection layer and a light-shielding layer made of a chromium-based material, the following film composition can be used.

[1104] When a light-shielding film having an anti-reflection layer and a light-shielding layer made of a chromium-based material is formed, the layer structure may be a layered anti-reflection layer and a light-shielding layer in order from the surface side, or an anti-reflection layer, a light-shielding layer, and an anti-reflection layer in order. In addition, the anti-reflection layer and the light-shielding layer may be a plurality of layers, or the composition may be discontinuously changed between layers with different compositions, or the composition may be changed continuously. As the chromium-based material used, metallic chromium and a material containing light elements such as oxygen, nitrogen, and carbon in metallic chromium may be used. Specifically, metallic chromium, chromium oxide, chromium nitride, chromium carbide, chromium oxide nitride, chromium oxide carbide, chromium nitride carbide, chromium oxide nitride carbide, chromium oxide nitride carbide, and chromium oxide nitride carbide.

[1105] Furthermore, the reflective blank mask comprises: a substrate; a multilayer reflective film formed on one main surface (surface side) of the substrate, specifically, a multilayer reflective film that reflects exposure light such as EUV light; and an absorber film formed on the multilayer reflective film, specifically, an absorber film that absorbs exposure light such as EUV light and reduces reflectivity. From the reflective blank mask (reflective blank mask for EUV), a reflective mask (reflective mask for EUV) having an absorber pattern (absorber film pattern) formed by patterning the absorber film can be manufactured. The wavelength of EUV light used in EUV lithography is 13 to 14 nm, and is usually light with a wavelength of about 13.5 nm.

[1106] The multilayer reflective film is usually preferably provided in contact with one main surface of the substrate, but a base film may be provided between the substrate and the multilayer reflective film without losing the effect of the present invention. The absorber film may be formed in contact with the multilayer reflective film, but it is preferred that the multilayer reflective film and the absorber film are in contact with the multilayer reflective film, and it is more preferred that a protective film (a protective film of the multilayer reflective film) is provided in contact with the multilayer reflective film and the absorber film. The protective film is used to protect the multilayer reflective film during processing such as cleaning and correction. In addition, the protective film preferably has the function of protecting the multilayer reflective film when the absorber film is patterned by etching and preventing the multilayer reflective film from being oxidized. On the other hand, under the other main surface (back side) which is the opposite side to one main surface of the substrate, it is preferred that a conductive film is provided in contact with the other main surface for electrostatically clamping the reflective mask in the exposure device. Here, one main surface of the substrate is referred to as the front side and the upper side, and the other main surface is referred to as the back side and the lower side, but the front and back and the top and bottom of the two are determined for convenience, and one main surface and the other main surface are any of the two main surfaces (film forming surfaces) of the substrate, and the front and back and the top and bottom can be replaced. More specifically, it can be formed by the method exemplified as the current technology in Japanese Patent Publication No. 2021-139970 or therein.

[1107] According to the resist pattern forming method of the present invention, even when using a substrate (e.g., a transmissive or reflective blank mask) made of a material such as a material having chromium, silicon, or tantalum on the outermost surface, which is likely to affect the shape of the resist pattern, a pattern with high resolution, suppressing the influence of development load and residue defects, and having a small size difference independent of pattern density can be obtained.

[1108] [Examples]

[1109] The following presents synthesis examples, examples, and comparative examples for specific illustration of the present invention. However, the present invention is not limited to the following examples. Also, in the following synthesis examples, the copolymerization composition ratio is a molar ratio, and Mw is the polystyrene-equivalent weight-average molecular weight measured by GPC. Also, the apparatuses used are as follows.

[1110] ·IR: NICOLET 6700 manufactured by Thermofisher Scientific

[1111] · 1 1H-NMR: ECA-500 manufactured by JEOL Ltd.

[1112] [1] Synthesis of acetal modifier

[1113] [Example 1-1] Synthesis of acetal modifier AC-1

[1114] [Chemical formula 366]

[1115]

[1116] (1) Synthesis of intermediate In-1

[1117] Under a nitrogen atmosphere, sodium hydride (purity 55 mass%, 91.6 g) was suspended in THF (530 g) in a reaction vessel. The temperature inside the reaction vessel was raised to 50 °C, and a solution composed of tetrahydrofurfuryl alcohol (224.7 g) and THF (90 g) was added dropwise. After the addition, the mixture was stirred at 50 °C inside the reaction vessel for 2 hours. After stirring, sodium iodide (30.0 g) was added, and methacryloyl chloride (180.7 g) was added dropwise while maintaining the temperature inside the reaction vessel at 50 - 60 °C. After the addition, the temperature inside the reaction vessel was raised to 65 °C, and aging was carried out for 5 hours. After aging, the reaction solution was cooled, and water (620 g) was added to stop the reaction. The target product was extracted with hexane (620 g), subjected to a usual aqueous work-up, the solvent was distilled off, and then distillation purification was carried out to obtain 281.2 g of intermediate In-1 (yield 90%).

[1118] (2) Synthesis of acetal modifier AC-1

[1119] Under nitrogen atmosphere, the intermediate In-1 (281.2 g) and potassium tert-butoxide (20.2 g) were dissolved in DMSO (300 g) in a reaction vessel. The temperature in the reaction vessel was raised to 80°C and the mixture was aged for 12 hours. After the aging, the reaction solution was cooled and water (300 g) was added to stop the reaction. The target product was extracted with hexane (500 g), and the usual aqueous work-up was performed. After the solvent was distilled off, the target product, the acetal modifier AC-1, was purified by distillation to obtain 268.1 g of a colorless oil (yield 95%).

[1120] IR spectrum data and NMR spectrum of acetal modifier AC-1 ( 1 The results of H-NMR / DMSO-d6) are shown below.

[1121] IR(D-ATR): ν=2959,2918,2871,1692,1452,1376,1339,1290,1226,1167,1076,1052,1023,922,824,444cm -1

[1122] 1 H-NMR (600MHz, in DMSO-d6): δ=5.90(1H,m),3.93(1H,m),3.71(1H,m),3.60(3H,m),1.89-1.75(3H,m),1.55(1H,m),1.49(3H,s),1.47(3H,s)ppm

[1123] [Examples 1-2 to 1-8] Synthesis of acetal modifiers AC-2 to AC-8

[1124] Acetal modifiers AC-2 to AC-8 were synthesized using corresponding raw materials and known organic synthesis methods.

[1125] [Chemistry 367]

[1126]

[1127] [2] Synthesis of polymers

[1128] [Example 2-1] Synthesis of polymer P-1

[1129] Add 20 g of polyhydroxystyrene-vinylnaphthalene copolymer and 46.7 g of THF as a solvent to a 100 mL flask. Then, add 0.5 g of methanesulfonic acid near 25°C under a nitrogen atmosphere, and dropwise add 4.4 g of acetal modifier AC-1. React at room temperature for 4.5 hours. After the reaction is completed, add 1.0 g of triethylamine, and drop the obtained reaction solution into 500 g of hexane. Filter the precipitated copolymer. Wash the filtered copolymer twice with 120 g of hexane. Dissolve the obtained copolymer in a mixed solvent of 60 g of ethyl acetate and 20 g of water, transfer the obtained solution to a separatory funnel, add 0.7 g of acetic acid, and perform a liquid separation operation. Remove the lower layer, add 20 g of water and 0.9 g of pyridine to the obtained organic layer, and perform a liquid separation operation. Remove the lower layer, and then add 20 g of water to the obtained organic layer for washing and liquid separation (washing and liquid separation are performed 5 times in total). Concentrate the liquid-separated organic layer, dissolve it in 40 g of PGME, drop the obtained solution into 600 g of water, filter the obtained precipitate, wash it with water and dry it to obtain 20.3 g of the target polymer P-1, a white polymer. Polymer P-1 was characterized by 1 1H-NMR, 13 13C-NMR and GPC measurements, and the following analysis results were obtained.

[1130] [Chemical formula 368]

[1131]

[1132] [Examples 2-2 to 2-15] Synthesis of Polymers P-2 to P-15

[1133] Change the polymer and / or acetal modifier used as raw materials. Otherwise, synthesize the following polymers P-2 to P-15 in the same manner as in Synthesis Example 1 or by a known method.

[1134] [Chemical formula 369]

[1135]

[1136] [Chemical formula 370]

[1137]

[1138] [Chemical formula 371]

[1139]

[1140] [Comparative Examples 1-1 to 1-6] Synthesis of Polymers cP-1 to cP-6 Combine each monomer combination and synthesize the following polymers cP-1 to cP-6 by a known method.

[1141] [Chemical formula 372]

[1142]

[1143] [Reference Synthesis Examples 1 to 6] Synthesis of Polymers AP-1 to AP-6 The following polymers AP-1 to AP-6 were synthesized by combining respective monomers using a known method.

[1144] [Chemistry 373]

[1145]

[1146] The dissolution rate of the above-mentioned polymer in the alkaline developer was calculated by spin coating a polymer solution (polymer concentration: 16.7 mass %, solvent: PGMEA) on an 8-inch silicon wafer, baking at 100°C for 90 seconds to form a film with a thickness of 1000 nm, and then developing with a 2.38 mass % TMAH aqueous solution at 23°C for 100 seconds, and measuring the film loss. As a result, the dissolution rates of polymers P-1 to P-15, AP-1 to AP-6, and cP-2 to cP-6 were 5 nm / min or less, and the dissolution rate of the comparative polymer cP-1 was 14 nm / min.

[1147] [3] Preparation of chemically amplified positive resist composition

[1148] [Examples 3-1 to 3-41, Comparative Examples 2-1 to 2-10]

[1149] The components were dissolved in an organic solvent according to the compositions shown in Tables 1 to 3, and the obtained solution was filtered through a nylon filter with a size of 5 nm and a UPE filter with a size of 1 nm to prepare a chemically amplified positive resist composition. 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.

[1150] [Table 1]

[1151]

[1152]

[1153] [Table 2]

[1154]

[1155] [Table 3]

[1156]

[1157]

[1158] Further, in Tables 1 to 3, the structures of photoacid generators PAG-1 to PAG-5, quenchers Q-1 to Q-4, and fluorine atom-containing polymers FP-1 to FP-5 are as shown below.

[1159] [Chemical formula 374]

[1160]

[1161] [Chemical formula 375]

[1162]

[1163] [Chemical formula 376]

[1164]

[1165] [3] EB Lithography Evaluation

[1166] [Examples 4-1 to 4-41, Comparative Examples 3-1 to 3-10]

[1167] Each chemically amplified positive resist composition (R-1 to R-41, CR-1 to CR-10) was spin-coated on a blank mask having a 6-inch low-thermal-expansion glass substrate with a 284-nm-thick Mo / Si40 layer multi-layer reflective film formed on one side, a 3.5-nm-thick Ru film formed thereon as a protective film, a 70-nm-thick TaN film formed thereon as an absorption layer, and a 6-nm-thick CrN film formed thereon as a hard mask, using ACT-M (manufactured by Tokyo Electron Limited). Pre-baking was performed on a hot plate at 110°C for 600 seconds to obtain a resist film with a thickness of 80 nm, which was used as a reflective blank mask for EUV exposure mask. The film thickness of the obtained resist film was measured using an optical measuring instrument NANOSPEC (manufactured by NANOMETRICS, Inc.). The measurement was performed at 81 points in the plane of the blank substrate other than the outer edge portion 10 mm inside from the outer periphery, and the average film thickness and the film thickness range were calculated.

[1168] Then, the aforementioned resist film was exposed using an electron beam exposure apparatus (EBM-5000plus manufactured by NUFLARE TECHNOLOGY, Inc., acceleration voltage 50 kV), PEB was performed at 110°C for 600 seconds, and development was performed with a 2.38 mass% TMAH aqueous solution to obtain a positive pattern.

[1169] The obtained resist pattern was evaluated as follows. The blank mask with the pattern was observed by top-down SEM (scanning electron microscope), and the exposure dose at which a 1:1 line and space (LS) of 200 nm was resolved at 1:1 was defined as the optimum exposure dose (μC / cm 2), the minimum size of the isolated spacing of 200nm with a 9:1 resolution exposure is the resolution (limit IS resolution), and the LER of 200nmLS is measured by SEM. For the evaluation of the development load, the SEM is used to measure the substrate surface, and the exposure (μC / cm2) of 200nm 1:1LS is designed to be resolved at a ratio of 1:1. 2 ) and the pitch size of the 200nmLS pattern formed by dummy patterns with densities of 15%, 25%, 33%, 45%, 50%, 55%, 66%, 75%, 85%, and 95% arranged around the pattern, and the difference in the size of the sparse and dense patterns was compared. The pattern shape was visually determined to be rectangular.

[1170] The exposure dissolution rate is calculated by spin coating the resist solution on an 8-inch silicon wafer, baking it at 110°C for 60 seconds, forming a 90nm thick resist film, and then irradiating it with a KrF excimer laser with a 1:1 line and space (LS) of 200nm and a 1:1 resolution (mJ / cm 2 ) was exposed, baked at 110°C for 60 seconds, and then developed with a 2.38 mass % TMAH aqueous solution at 23°C using a resist development analyzer (RDA-800 manufactured by Litho Tech Japan Co., Ltd.). The results are shown in Tables 4 to 6.

[1171] [Table 4]

[1172]

[1173]

[1174] [Table 5]

[1175]

[1176] [Table 6]

[1177]

[1178] The chemically amplified positive resist compositions (R-1 to R-41) of the present invention all show good isolated spacing (IS) resolution, LER and pattern rectangularity compared to the resist compositions of the comparative examples (CR-1 to CR-10), and show values ​​in which the development load is suppressed.

[1179] [4] Residue defect evaluation

[1180] [Examples 5-1 to 5-41, Comparative Examples 4-1 to 4-10]

[1181] The substrates coated with the resist compositions (R-1 to R-41, CR-1 to CR-10) on the reflective blank mask for EUV exposure mask were fully drawn with the optimum exposure amount of each resist composition using an electron beam exposure device (EBM-5000plus manufactured by NUFLARE TECHNOLOGY Co., Ltd., accelerating voltage 50 kV), PEB was performed at 110° C. for 600 seconds, and developed with a 2.38 mass % TMAH aqueous solution. The evaluation of the development residue was performed using a mask defect inspection device (M9650 manufactured by LASERTECH Co., Ltd.). The total number of defects after development is shown in Tables 7 to 9.

[1182] [Table 7]

[1183]

[1184]

[1185] [Table 8]

[1186] Resist composition Total number of defects after development Example 5-29 R-29 250 Example 5-30 R-30 270 Example 5-31 R-31 280 Example 5-32 R-32 250 Example 5-33 R-33 270 Example 5-34 R-34 280 Example 5-35 R-35 270 Example 5-36 R-36 260 Example 5-37 R-37 250 Example 5-38 R-38 280 Example 5-39 R-39 260 Embodiment 5-40 R-40 270 Example 5-41 R-41 260

[1187] [Table 9]

[1188] Resist composition Total number of defects after development Comparative Example 4-1 CR-1 420 Comparative Example 4-2 CR-2 960 Comparative Example 4-3 CR-3 680 Comparative Example 4-4 CR-4 570 Comparative Examples 4-5 CR-5 680 Comparative Examples 4-6 CR-6 970 Comparative Examples 4-7 CR-7 520 Comparative Examples 4-8 CR-8 580 Comparative Examples 4-9 CR-9 560 Comparative Examples 4-10 CR-10 870

[1189] The chemically amplified positive resist compositions (R-1 to R-41) of the present invention all showed a smaller total defect count after development than the resist compositions of the comparative examples (CR-1 to CR-10).

[1190] [5] Dry etching resistance evaluation

[1191] [Examples 6-1 to 6-41, Comparative Examples 5-1 to 5-10]

[1192] 2 g of each polymer (P-1 to P-41, CP-1 to CP-10) shown in Tables 1 and 2 was dissolved in 10 g of cyclohexanone and the polymer solution was filtered with a filter of size 0.2 μm, and then spin-coated on a blank mask of 152 mm square with a Cr film on the outermost surface to form a film with a thickness of 300 nm, which was then evaluated under the following conditions.

[1193] Etching test with chlorine gas:

[1194] Using a mask dry etching apparatus Gen-4 manufactured by PLASMA-THERM, the difference in film thickness of the polymer film before and after etching was determined.

[1195] The etching conditions are as follows.

[1196]

[1197]

[1198] In this evaluation, a film with a small film thickness difference, that is, a small reduction, indicates good etching resistance. The results of dry etching resistance are shown in Tables 10 to 12.

[1199] [Table 10]

[1200]

[1201] [Table 11]

[1202]

[1203] [Table 12]

[1204]

[1205] From the results shown in Tables 10 to 12, it can be confirmed that the polymer of the present invention has excellent dry etching resistance in Cl2 / O2 gas.

[1206] The polymer, chemically amplified positive resist composition and resist pattern forming method of the present invention are useful in semiconductor device manufacturing, especially in optical lithography for transmissive and reflective blank photomask processing.

Claims

1. An acetal modifier which provides a group having a cyclic saturated heterocyclic ring containing an oxygen atom or a sulfur atom as a protective group for an aliphatic or aromatic hydroxyl group. 2 . The acetal modifier according to claim 1 , which provides a group that serves as a protecting group for an aromatic hydroxyl group.

3. The acetal modifier according to claim 1, which is a compound represented by the following formula (AC-1) or (AC-2): In the formula, R L1 , R L2 , R L5 , R L6 and R L7 are each independently a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms, and R L1 With R L2 They can also bond to each other and to the carbon atoms to which they are bonded to form a ring, R L5 ~R L7 Any two of them may also be bonded to each other and together with the carbon atoms to which they are bonded form a ring, R L3 , R L4 , R L8 and R L9 are each independently a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom, and R L3 With R L4 They can also bond to each other and to the carbon atoms to which they are bonded to form a ring, R L8 With R L9 They can also bond to each other and to the carbon atoms to which they are bonded to form rings. W 1 are each independently a group of a cyclic saturated heterocyclic ring containing an oxygen atom or a sulfur atom, X is a chlorine atom, a bromine atom or an iodine atom, m1 and m2 are each independently an integer of 0-3.

4. A polymer comprising a repeating unit A1 having a structure in which a side chain aromatic hydroxyl group is protected by an acid-labile group represented by the following formula (AL-1) or (AL-2), which is deprotected by an acid to become alkali-soluble, In the formula, R L1 , R L2 , R L5 , R L6 and R L7 are each independently a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms, and R L1 With R L2 They can also bond to each other and to the carbon atoms to which they are bonded to form a ring, R L5 ~R L7 Any two of them may also be bonded to each other and together with the carbon atoms to which they are bonded form a ring, R L3 , R L4 , R L8 and R L9 are each independently a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom, and R L3 With R L4 They can also bond to each other and to the carbon atoms to which they are bonded to form a ring, R L8 With R L9 They can also bond to each other and to the carbon atoms to which they are bonded to form rings. W 1 are each independently a group of a cyclic saturated heterocyclic ring containing an oxygen atom or a sulfur atom, m1 and m2 are each independently an integer of 0 to 3, The chain line represents the atomic bond to the oxygen atom of the aromatic hydroxyl group.

5. The polymer according to claim 4, wherein The repeating unit A1 is represented by the following formula (A1), In the formula, a1 is 0 or 1, a2 is an integer of 0 to 4 when a1=0, and an integer of 0 to 6 when a1=1, and a3 is an integer of 1 to 3, but when a1=0, 1≤a2+a3≤5, when a1=1, 1≤a2+a3≤7, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group, X 1 is a single bond, *-C(=O)-O- or *-C(=O)-NH-, * is an atomic bond between the carbon atoms of the main chain, X 2 is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate bond, a carbonate bond or a carbamate bond, A 1 is a single bond or a saturated alkylene group having 1 to 10 carbon atoms, wherein a part of -CH2- in the saturated alkylene group may be substituted by -O-, R 1 is a halogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom, R is an acid-labile group represented by the formula (AL-1) or (AL-2).

6. The polymer according to claim 4, further comprising a phenolic hydroxyl group-containing repeating unit A2 represented by the following formula (A2): Wherein, b1 is 0 or 1, b2 is an integer of 0 to 4 when b1=0, and an integer of 0 to 6 when b1=1, and b3 is an integer of 1 to 3, but when b1=0, 1≤b2+b3≤5, and when b1=1, 1≤b2+b3≤7, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group, X 3 is a single bond, *-C(=O)-O- or *-C(=O)-NH-, * is an atomic bond between the carbon atoms of the main chain, X 4 is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate bond, a carbonate bond or a carbamate bond, A 2 is a single bond or a saturated alkylene group having 1 to 10 carbon atoms, wherein a part of -CH2- in the saturated alkylene group may be substituted by -O-, R 2 It is a halogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom.

7. The polymer according to claim 6, wherein The repeating unit A2 is represented by the following formula (A2-1), In the formula, R A and b3 are the same as described above.

8. The polymer according to claim 4, further comprising at least one selected from the group consisting of a repeating unit represented by the following formula (A3-1) and a repeating unit represented by the following formula (A3-2), In the formula, c1 is 0 or 1, c2 is an integer from 0 to 2, c3 is an integer satisfying 0≤c3≤5+2(c2)-c4, c4 is an integer from 1 to 3, c5 is 0 or 1, d1 is an integer of 0 to 2, d2 is an integer of 0 to 2, d3 is an integer of 0 to 5, d4 is an integer of 0 to 2, R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group, A 3 is a single bond or a saturated alkylene group having 1 to 10 carbon atoms, wherein -CH2- of the saturated alkylene group may be substituted by -O-, A 4 is a single bond, phenylene, naphthylene or *-C(=O)-OA 41 -, A 41 is an aliphatic alkylene group having 1 to 20 carbon atoms which may contain a hydroxyl group, an ether bond, an ester bond or a lactone ring, or a phenylene group or a naphthylene group, * is an atomic bond with a carbon atom of the main chain, R 3 is a halogen atom, a saturated hydrocarbon group having 1 to 6 carbon atoms which may be substituted by a halogen atom, a saturated hydrocarbonoxy group having 1 to 6 carbon atoms which may be substituted by a halogen atom, or a saturated hydrocarboncarbonyloxy group having 2 to 8 carbon atoms which may be substituted by a halogen atom, R 4 and R 5 Each independently represents a hydrocarbon group having 1 to 10 carbon atoms which may contain a hetero atom, R 4 With R 5 They can also bond to each other and to the carbon atoms to which they are bonded to form rings. R 6 are each independently a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, or a fluorinated alkoxy group having 1 to 5 carbon atoms, R 7 are each independently a hydrocarbon group having 1 to 10 carbon atoms which may contain a hetero atom, X A When c4 is 1, it is an acid-labile group, and when c4 is 2 or 3, it is a hydrogen atom or an acid-labile group, but at least one of them is an acid-labile group.

9. The polymer according to claim 4, further comprising at least one selected from the group consisting of a repeating unit represented by the following formula (B1), a repeating unit represented by the following formula (B2), and a repeating unit represented by the following formula (B3), In the formula, e and f are each independently an integer of 0 to 4, g1 is an integer of 0 to 5, g2 is an integer of 0 to 2, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group, X 5 is a single bond, *-C(=O)-O- or *-C(=O)-NH-, * is an atomic bond between the carbon atoms of the main chain, A 5 is a single bond or a saturated alkylene group having 1 to 10 carbon atoms, wherein a part of -CH2- in the saturated alkylene group may be substituted by -O-, R 11 and R 12 each independently represents a hydroxyl group, a halogen atom, a saturated hydrocarbon carbonyloxy group having 2 to 8 carbon atoms which may be substituted by a halogen atom, a saturated hydrocarbon group having 1 to 8 carbon atoms which may be substituted by a halogen atom, or a saturated hydrocarbonoxy group having 1 to 8 carbon atoms which may be substituted by a halogen atom, R 13 It is an acetyl group, a saturated hydrocarbon group having 1 to 20 carbon atoms, a saturated hydrocarbon oxy group having 1 to 20 carbon atoms, a saturated hydrocarbon carbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbon oxyalkyl group having 2 to 20 carbon atoms, a saturated hydrocarbon thialkyl group having 2 to 20 carbon atoms, a halogen atom, a nitro group or a cyano group, and when g2 is 1 or 2, it may also be a hydroxyl group.

10. The polymer according to claim 4, further comprising at least one selected from the group consisting of a repeating unit represented by the following formula (C1), a repeating unit represented by the following formula (C2), a repeating unit represented by the following formula (C3), and a repeating unit represented by the following formula (C4), In the formula, R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group, Z 1 is a single bond or a phenylene group, Z 2 for* 1 -C(=O)-OZ 21 -, * 1 -C(=O)-NH-Z 21 -or* 1 -OZ 21 -, Z 21 It is a divalent group obtained by aliphatic alkylene group having 1 to 6 carbon atoms, phenylene group or a combination thereof, and may contain a carbonyl group, an ester bond, an ether bond or a hydroxyl group, 1 Represents and Z 1 The atomic bonds Z 3 Each independently represents a single bond, phenylene, naphthylene or * 2 -C(=O)-OZ 31 -, Z 31 is an aliphatic alkylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, the aliphatic alkylene group may also contain a hydroxyl group, an ether bond, an ester bond or a lactone ring, * 2 represents the atomic bonds between the carbon atoms of the main chain, Z 4 Each is independently a single bond, * 3 -Z 41 -C(=O)-O-,* 3 -C(=O)-NH-Z 41 -or* 3 -OZ 41 -, Z 41 is an alkylene group having 1 to 20 carbon atoms which may contain a hetero atom, * 3 Represents and Z 3 The atomic bonds Z 5 Each is independently a single bond, * 4 -Z 51 -C(=O)-O-,* 4 -C(=O)-NH-Z 51 -or* 4 -OZ 51 -, Z 51 is an alkylene group having 1 to 20 carbon atoms which may contain a hetero atom, * 4 Represents and Z 4 The atomic bonds Z 6 is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, phenylene substituted with trifluoromethyl, * 2 -C(=O)-OZ 61 -, * 2 -C(=O)-N(H)-Z 61 -or* 2 -OZ 61 -, Z 61 is an aliphatic alkylene 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 also contain a carbonyl group, an ester bond, an ether bond or a hydroxyl group,* 2 represents the atomic bonds between the carbon atoms of the main chain, R 31 and R 32 are each independently a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom, and R 31 and R 32 They can also bond to each other and to the sulfur atoms to which they are bonded to form a ring. L is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate bond, a carbonate bond or a carbamate bond, R 1 and Rf 2 are each independently a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms, R 3 and Rf 4 are each independently a hydrogen atom, a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms, R 5 and Rf 6 Each independently represents a hydrogen atom, a fluorine atom or a fluorinated saturated hydrocarbon group having 1 to 6 carbon atoms, but not all Rf 5 and Rf 6 At the same time, it becomes a hydrogen atom, M - is a non-nucleophilic counter ion, A + is an onium cation, k1 and k2 are each independently an integer of 0-3. 11 . A chemically amplified positive resist composition comprising a base polymer comprising the polymer according to claim 4 .

12. The chemically amplified positive resist composition according to claim 11, further comprising an organic solvent.

13. The chemically amplified positive resist composition according to claim 11, further comprising a photoacid generator that generates an acid with an acid strength (pKa) of -2.0 or more.

14. The chemically amplified positive resist composition according to claim 13, wherein: The photoacid generator contains an anion represented by the following formula (P1): In the formula, m1 is 0 or 1, p is an integer from 1 to 3, q ​​is an integer from 1 to 5, and r is an integer from 0 to 3. L 1 is a single bond, an ether bond, an ester bond, a sulfonate bond, a carbonate bond or a carbamate bond, L 2 is an ether bond, an ester bond, a sulfonate bond, a carbonate bond or a carbamate bond, L A When p is 1, it is a single bond or an alkylene group having 1 to 20 carbon atoms; when p is 2 or 3, it is a (p+1)-valent hydrocarbon group having 1 to 20 carbon atoms; the alkylene group and the (p+1)-valent hydrocarbon group may contain at least one selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxyl group and a carboxyl group, R 1 and Rf 2 are each independently a hydrogen atom, a fluorine atom or a trifluoromethyl group, but at least one is a fluorine atom or a trifluoromethyl group, R 101 is a hydroxyl group, a carboxyl group, a saturated hydrocarbon group having 1 to 6 carbon atoms, a saturated hydrocarbon oxy group having 1 to 6 carbon atoms, a saturated hydrocarbon carbonyloxy group having 2 to 6 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, -N(R 101A )(R 101B )、-N(R 101C )-C(=O)-R 101D or -N(R 101C )-C(=O)-OR 101D , R 101A and R 101B are each independently a hydrogen atom or a saturated hydrocarbon group having 1 to 6 carbon atoms, R 101C is a hydrogen atom or a saturated hydrocarbon group having 1 to 6 carbon atoms, R 101D is a saturated hydrocarbon group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbon group having 2 to 8 carbon atoms, R 102 It is a saturated alkylene group having 1 to 20 carbon atoms or an arylene group having 6 to 20 carbon atoms, and a part or all of the hydrogen atoms of the saturated alkylene group may be substituted by halogen atoms other than fluorine atoms, and a part or all of the hydrogen atoms of the arylene group may be substituted by a substituent selected from a saturated alkyl group having 1 to 20 carbon atoms, a saturated alkoxy group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogen atom and a hydroxyl group.

15. The chemically amplified positive resist composition according to claim 11, further comprising a quencher.

16. The chemically amplified positive resist composition according to claim 11, further comprising a fluorine-containing polymer, wherein the fluorine-containing polymer comprises 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), In the formula, R B are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group, R 301 , R 302 , R 304 and R 305 are each independently a hydrogen atom or a saturated hydrocarbon group having 1 to 10 carbon atoms, R 303 , R 306 , R 307 and R 308 are each independently a hydrogen atom, a hydrocarbon group having 1 to 15 carbon atoms, a fluorinated hydrocarbon group having 1 to 15 carbon atoms, or an acid-labile group, and R 303 , R 306 , R 307 and R 308 When it is a hydrocarbon group or a fluorinated hydrocarbon group, an ether bond or a carbonyl group may be inserted between the carbon-carbon bonds. n is an integer from 1 to 3, Z 1 It is an (n+1)-valent hydrocarbon group having 1 to 20 carbon atoms or an (n+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms.

17. The chemically amplified positive resist composition according to claim 16, wherein: The fluorine-containing polymer further contains 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), In the formula, R C are each independently a hydrogen atom or a methyl group, R 309 is a hydrogen atom, or a linear or branched hydrocarbon group having 1 to 5 carbon atoms, which may contain a hetero atom inserted between carbon-carbon bonds, R 310 It is a straight-chain or branched hydrocarbon group having 1 to 5 carbon atoms, which may contain a heteroatom group inserted between carbon-carbon bonds. R 311 is a saturated hydrocarbon group having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted by a fluorine atom, and a part of the -CH2- of the saturated hydrocarbon group may be substituted by an ester bond or an ether bond, x is an integer from 1 to 3, y is an integer satisfying 0≤y≤5+2z-x, z is 0 or 1, Z 2 is a single bond, *-C(=O)-O- or *-C(=O)-NH-, Z 3 is a single bond, -O-, *-C(=O)-OZ 31 -Z 32 - or *-C(=O)-NH-Z 31 -Z 32 -, Z 31 is a single bond or a saturated alkylene group having 1 to 10 carbon atoms, Z 32 is a single bond, an ester bond, an ether bond or a sulfonamide bond, * is the atomic bond between the carbon atoms in the main chain.

18. The chemically amplified positive resist composition according to claim 11, wherein: The dissolution rate of the polymer in the alkaline developer is 10 nm / min or less.

19. The chemically amplified positive resist composition according to claim 11, wherein: The dissolution rate of the unexposed portion of the resist film obtained from the chemically amplified positive resist composition in an alkaline developer is 10 nm / min or less.

20. The chemically amplified positive resist composition according to claim 11, wherein: The dissolution rate of the exposed portion of the resist film obtained from the chemically amplified positive resist composition in an alkaline developer is 50 nm / sec or more.

21. A method for forming a resist pattern, comprising the following steps: forming a resist film on a substrate using the chemically amplified positive resist composition according to claim 11, The resist film is irradiated with a pattern of high energy rays, and The resist film having the irradiated pattern is developed using an alkaline developer.

22. The resist pattern forming method according to claim 21, wherein: The high-energy ray is KrF excimer laser, ArF excimer laser, electron beam or extreme ultraviolet ray with a wavelength of 3 to 15 nm.

23. The resist pattern forming method according to claim 21, wherein: The outermost surface of the substrate is made of a material containing at least one selected from the group consisting of chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten and tin.

24. The resist pattern forming method according to claim 21, wherein: The substrate is a transmission type or reflection type blank mask.

25. A transmission or reflection blank mask obtained by coating the chemically amplified positive resist composition according to claim 11.

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