Chemically amplified positive resist composition and resist pattern forming method

Abstract

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

Description

[Technical field]

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

[0002] In recent years, pattern rules have become finer with the increasing integration and speed of LSI. Chemically amplified resist compositions using acids as catalysts are used exclusively for processing patterns of 0.2 μm or less. High-energy rays such as ultraviolet rays, far ultraviolet rays, and electron beams (EB) are used as exposure sources. In particular, EB lithography, which is used as an ultrafine processing technology, is also indispensable as a processing method for photomask blanks when producing photomasks for semiconductor manufacturing.

[0003] Polymers having a large amount of aromatic skeletons with acidic side chains, such as polyhydroxystyrene, are useful as materials for resist compositions for KrF lithography using KrF excimer lasers, but have not been used as materials for resist compositions for ArF lithography using ArF excimer lasers because they exhibit high absorption for light with wavelengths of around 200 nm. However, they are important materials for resist compositions for EB lithography, which is a powerful technique for forming patterns smaller than the processing limit of ArF excimer lasers, and resist compositions for extreme ultraviolet (EUV) lithography, because they provide high etching resistance.

[0004] Typically, the base polymer used in positive-tone resist compositions for EB lithography and resist compositions for EUV lithography is a material that is soluble in an alkaline developer by irradiating the base polymer with high-energy rays and using the acid generated from a photoacid generator as a catalyst to deprotect the acid-decomposable protecting groups (acid-labile groups) that mask the acidic functional groups in the phenol side chains of the base polymer.

[0005] As the acid-decomposable protecting group, a tertiary alkyl group, a tert-butoxycarbonyl group, an acetal group, and the like have mainly been used. Here, when a protecting group such as an acetal group, which requires a relatively small activation energy for deprotection, is used, there is an advantage that a highly sensitive resist film can be obtained. However, if the diffusion of the generated acid is not sufficiently suppressed, the deprotection reaction occurs even in the unexposed parts of the resist film, which leads to a problem of deterioration of the line edge roughness (LER) and a decrease in the dimensional uniformity (CDU) of the pattern line width. In addition, in the processing of photomask blanks, which is a particularly important application, some photomask substrates have surface materials such as chromium oxide and other chromium compound films that are likely to affect the pattern shape of the chemically amplified resist film, and in order to maintain high resolution and the shape after etching, it is also important to maintain the pattern profile of the resist film in a rectangular shape regardless of the type of substrate. In recent years, in order to achieve miniaturization, a multi-beam mask writing (MBMW) drawing process is sometimes used to process mask blanks. In this case, a low-sensitivity resist composition (high dose region) that is advantageous in terms of roughness is used as the resist composition. However, the optimization of resist compositions in this high dose region has also been attracting attention.

[0006] Various improvements have been made to control sensitivity and pattern profile by selecting and combining materials used in resist compositions, process conditions, etc. One of these improvements is the problem of acid diffusion. This acid diffusion has been the subject of much study because it has a significant effect on the sensitivity and resolution of chemically amplified resist compositions.

[0007] Patent Documents 1 and 2 disclose examples of suppressing acid diffusion and reducing roughness by increasing the bulkiness of benzenesulfonic acid generated from a photoacid generator upon exposure. However, the suppression of acid diffusion by the above-mentioned acid generators is still insufficient, and therefore the development of an acid generator with smaller diffusion has been desired.

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

[0009] In addition, when a sulfonium salt that generates an acid with high acid strength, such as fluorinated alkanesulfonic acid, described in Patent Document 4, is used with a polymer containing a repeating unit having an acetal group, there is a problem that a pattern with large LER is formed. Since the acid strength of fluorinated alkanesulfonic acid is too high for deprotection of an acetal group, which has a relatively small activation energy for deprotection, even if the diffusion of the acid is suppressed, the deprotection reaction proceeds due to a small amount of acid diffused into the unexposed area. This is also true for the sulfonium salt that generates benzenesulfonic acid described in Patent Documents 1 and 2. Therefore, there is a demand for the development of an acid generator that generates an acid with a strength more suitable for deprotection of an acetal group.

[0010] In order to suppress the diffusion of acid, in addition to the above-mentioned method of increasing the volume of the generated acid, a method of improving the quencher (acid diffusion control agent) can also be considered. The quencher suppresses the diffusion of acid and is practically an essential component for improving the performance of the resist composition. Various studies have been conducted on quenchers, and amines and weak acid onium salts are generally used. As an example of a weak acid onium salt, Patent Document 5 describes that the addition of triphenylsulfonium acetate can form a good resist pattern without the formation of a T-top, the difference in line width between an isolated pattern and a dense pattern, and standing waves. Patent Document 6 describes that the addition of an ammonium sulfonate salt or an ammonium carboxylate salt improves the sensitivity, resolution, and exposure margin. Patent Document 7 also describes that a resist composition for KrF lithography and EB lithography, which is a combination containing a photoacid generator that generates a fluorine-containing carboxylic acid, has excellent resolution and improved process tolerance such as exposure margin and depth of focus. These are used in KrF lithography, EB lithography or F2 lithography.

[0011] Patent Document 8 describes a positive-type photosensitive composition for ArF lithography that contains a carboxylate onium salt. These compositions suppress the acid decomposition reaction of acid labile groups by replacing a strong acid (sulfonic acid) with a weak acid (carboxylic acid) by forming a weak acid and a strong acid onium salt, which replaces a strong acid (sulfonic acid) with a weak acid (carboxylic acid) by exposure to light, thereby reducing (controlling) the acid diffusion distance, and apparently functioning as a quencher.

[0012] Patent Document 9 describes the use of a sulfonium salt of a carboxylic acid containing a nitrogen-containing heterocycle as a quencher, but no detailed investigation has been conducted on a low-sensitivity resist composition (high dose region) of 50 μC or more.

[0013] However, when patterning is performed using a resist composition containing the above-mentioned onium carboxylate or onium fluorocarboxylate, LER and resolution are still insufficient in recent years, despite the progress in miniaturization. Therefore, there has been a demand for the development of a quencher that can further reduce LER and improve resolution, pattern fidelity, and dose margin. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] JP 2009-53518 A [Patent Document 2] JP 2010-100604 A [Patent Document 3] JP 2011-22564 A [Patent Document 4] Patent No. 5083528 [Patent Document 5] Patent No. 3955384 [Patent Document 6] Japanese Patent Application Publication No. 11-327143 [Patent Document 7] Patent No. 4231622 [Patent Document 8] Patent No. 4226803 [Patent Document 9] Patent No. 6512049 Summary of the Invention [Problem to be solved by the invention]

[0015] The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a chemically amplified positive resist composition that improves the resolution during pattern formation and that is capable of obtaining a resist pattern with improved LER, resolution, pattern fidelity, and dose margin, and a method of forming a resist pattern. [Means for solving the problem]

[0016] As a result of intensive research into achieving the above-mentioned object, the inventors have found that when a quencher consisting of an onium salt whose anion moiety is decomposed by the action of acid and heat into carbon dioxide and an organic compound having 12 or less carbon atoms is introduced into a resist composition, it is possible to obtain a pattern that exhibits good resolution and pattern shape as well as improved LER, pattern fidelity and dose margin, which has led to the completion of the present invention.

[0017] That is, the present invention provides the following chemically amplified positive resist composition and method of forming a resist pattern. 1. A chemically amplified positive resist composition comprising: (A) a quencher consisting of an onium salt represented by the following formula (A1); and (B) a base polymer containing a polymer that contains a repeating unit represented by the following formula (B1), and that decomposes under the action of an acid and has increased solubility in an alkaline developer. [ka] (In the formula, X is a single bond, -O- or -S-. R 1 and R 2 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms, and a part of -CH2- in the hydrocarbyl group may be substituted with -O- or -C(=O)-. 1 and R 2 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 3 When X is a single bond or -S-, it is a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms, and when X is -O-, it is a hydrogen atom, a hydrocarbyl group having 1 to 10 carbon atoms other than an acid labile group, or an acid labile group, in which some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with halogen atoms, and some of the -CH2- of the hydrocarbyl group may be substituted with -O- or -C(=O)-; R 1 and R 3 may be bonded to each other to form a ring together with the atoms to which they are bonded and the atoms between them. However, R 3 is other than an acid labile group, R 1 ~R3 The maximum number of carbon atoms contained is 10. Z + is an onium cation. [ka] (In the formula, a1 is 0 or 1. a2 is an integer of 0 to 2. a3 is an integer that satisfies 0≦a3≦5+2(a2)−a4. a4 is an integer of 1 to 3. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 11 represents a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. A 1 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and -CH2- of the saturated hydrocarbylene group may be substituted with -O-. 2. The chemically amplified positive resist composition of 1, wherein X is --O--. 3.R 3 The chemically amplified positive resist composition of claim 2, wherein the acid labile group is 4. The chemically amplified positive resist composition according to any one of 1 to 3, wherein the acid labile group is represented by the following formula (AL-1) or (AL-2): [ka] (In the formula, X a is -O- or -S-. R 4 , R 5 and R 6are each independently a hydrocarbyl group having 1 to 12 carbon atoms, a part of -CH2- in the hydrocarbyl group may be substituted with -O- or -S-, and when the hydrocarbyl group contains an aromatic ring, a part or all of the hydrogen atoms in the aromatic ring may be substituted with a halogen atom, a cyano group, a nitro group, an alkyl group having 1 to 4 carbon atoms which may contain a halogen atom, or an alkoxy group having 1 to 4 carbon atoms which may contain a halogen atom. 4 , R 5 and R 6 Any two of these may be bonded to each other to form a ring, and a portion of -CH2- in the ring may be substituted by -O- or -S-. R 7 and R 8 R are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. 9 is a hydrocarbyl group having 1 to 20 carbon atoms, and a part of the -CH2- in the hydrocarbyl group may be substituted with -O- or -S-. 8 and R 9 and are bonded to each other, and the carbon atom and X to which they are bonded a may form a heterocyclic group having 3 to 20 carbon atoms together, and a part of -CH2- in the heterocyclic group may be substituted with -O- or -S-. n1 and n2 each independently represent 0 or 1. * represents a bond to the adjacent -O-.) 5.Z + is an onium cation represented by any one of the following formulas (cation-1) to (cation-3): [ka] (In the formula, R c1 ~R c9 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. c1 and R c2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. 6. The chemically amplified positive resist composition according to any one of 1 to 5, wherein the polymer further contains a repeating unit represented by the following formula (B2-1): [ka] (In the formula, b1 is 0 or 1. b2 is an integer of 0 to 2. b3 is an integer satisfying 0≦b3≦5+2(b2)−b4. b4 is an integer of 1 to 3. b5 is 0 or 1. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 12 represents a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. A 2 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and -CH2- of the saturated hydrocarbylene group may be substituted with -O-. When b4 is 1, X is an acid labile group. When b4 is 2 or 3, X is each independently a hydrogen atom or an acid labile group, provided that at least one X is an acid labile group. 7. The chemically amplified positive resist composition according to any one of 1 to 6, wherein the polymer further contains a repeating unit represented by the following formula (B2-2): [ka] (In the formula, c1 is an integer of 0 to 2. c2 is an integer of 0 to 2. c3 is an integer of 0 to 5. c4 is an integer of 0 to 2. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 13 and R 14 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom, R 13 and R 14may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 15 each independently represents a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, or a fluorinated alkoxy group having 1 to 5 carbon atoms. R 16 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. A 3 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OA 31 -It is. 31 is an aliphatic hydrocarbylene group having 1 to 20 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond or a lactone ring, or a phenylene group or naphthylene group. * is a bond to a carbon atom of the main chain.) 8. The chemically amplified positive resist composition according to any one of 1 to 7, wherein the polymer further comprises at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (B3), a repeating unit represented by the following formula (B4), and a repeating unit represented by the following formula (B5): [ka] (In the formula, d and e each independently represent an integer of 0 to 4. f1 is 0 or 1. f2 is an integer of 0 to 2. f3 is an integer of 0 to 5.) R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 21 and R 22 each independently represents a hydroxy group, a halogen atom, a saturated hydrocarbyl group having 1 to 8 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 8 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. R 23represents a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbyloxyhydrocarbyl group having 2 to 20 carbon atoms, a saturated hydrocarbylthiohydrocarbyl group having 2 to 20 carbon atoms, a halogen atom, a nitro group, a cyano group, a saturated hydrocarbylsulfinyl group having 1 to 20 carbon atoms, or a saturated hydrocarbylsulfonyl group having 1 to 20 carbon atoms. A 4 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and -CH2- of the saturated hydrocarbylene group may be substituted with -O-. 9. The chemically amplified positive resist composition according to any one of 1 to 8, wherein the polymer further comprises at least one selected from a repeating unit represented by the following formula (B6), a repeating unit represented by the following formula (B7), a repeating unit represented by the following formula (B8), a repeating unit represented by the following formula (B9), a repeating unit represented by the following formula (B10), a repeating unit represented by the following formula (B11), a repeating unit represented by the following formula (B12), and a repeating unit represented by the following formula (B13). [ka] (In the formula, R B are each independently a hydrogen atom or a methyl group. Y 1 represents a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, or *-OY 11 -, *-C(=O)-OY 11 - or *-C(=O)-NH-Y 11 - and Y 11 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group obtained by combining these and having 7 to 18 carbon atoms, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. Y 2 is a single bond or **-Y 21 -C(=O)-O-, and Y 21is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. Y 3 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, *-OY 31 -, *-C(=O)-OY 31 - or -C(=O)-NH-Y 31 -It is. Y 31 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, or a group having 7 to 20 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. * represents a bond to a carbon atom in the main chain, and ** represents a bond to an oxygen atom in the formula. Y 4 represents a single bond or a hydrocarbylene group having 1 to 30 carbon atoms which may contain a heteroatom. g1 and g2 are each independently 0 or 1, but Y 4 When is a single bond, g1 and g2 are 0. R 31 ~R 48 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 31 and R 32 may be bonded to each other to form a ring together with the sulfur atom to which they are attached, R 33 and R 34 , R 36 and R 37 , or R 39 and R 40 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. R HF is a hydrogen atom or a trifluoromethyl group. Xa - is a non-nucleophilic counterion. 10. The chemically amplified positive resist composition according to any one of 1 to 9, wherein the content of repeating units having an aromatic ring skeleton in all repeating units of the polymer contained in the base polymer is 60 mol % or more. 11. The chemically amplified positive resist composition according to any one of 1 to 10, further comprising (C) a photoacid generator. 12. The chemically amplified positive resist composition according to 11, wherein the acid strength (pKa) of the anion of the photoacid generator is −3.0 or more. 13. The chemically amplified positive resist composition of 11 or 12, in which the content ratio of the photoacid generator (C) to the quencher (A) is less than 6 in terms of mass ratio. 14. Any of the chemically amplified positive resist compositions according to 1 to 13, further comprising (D) a fluorine atom-containing polymer which contains at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (D1), a repeating unit represented by the following formula (D2), a repeating unit represented by the following formula (D3), and a repeating unit represented by the following formula (D4), and which may further contain at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (D5) and a repeating unit represented by the following formula (D6). [ka] (In the formula, x is an integer of 1 to 3. y is an integer that satisfies 0≦y≦5+2z−x. z is 0 or 1. h is an integer of 1 to 3. R C each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R D are each independently a hydrogen atom or a methyl group. R 101 , R 102 , R 104 and R 105 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 103 , R 106 , R 107 and R 108 each independently represents a hydrogen atom, a hydrocarbyl group having 1 to 15 carbon atoms, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid labile group; R103 , R 106 , R 107 and R 108 When is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bonds. R 109 represents a hydrogen atom or a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a group containing a heteroatom interposed between the carbon-carbon bonds. R 110 is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a group containing a heteroatom interposed between the carbon-carbon bonds. R 111 represents a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, and a portion of the -CH2- in the saturated hydrocarbyl group may be substituted with an ester bond or an ether bond. Z 1 is a (h+1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (h+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. Z 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * is a bond to a carbon atom in the main chain. Z 3 is a single bond, -O-, *-C(=O)-OZ 31 -Z 32 - or -C(=O)-NH-Z 31 -Z 32 -It is. 31 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. 32 is a single bond, an ester bond, an ether bond, or a sulfonamide bond. * is a bond to a carbon atom in the main chain.) 15. Any one of the chemically amplified positive resist compositions according to 1 to 14, further comprising (E) an organic solvent. 16. A method for forming a resist pattern, comprising the steps of: forming a resist film on a substrate using the chemically amplified positive resist composition according to any one of 1 to 15; irradiating the resist film with a pattern using high-energy rays; and developing the resist film irradiated with the pattern using an alkaline developer. 17. The method for forming a resist pattern according to claim 16, wherein the high energy radiation is EUV or EB. 18. The method for forming a resist pattern according to claim 16, 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. 19. The method for forming a resist pattern according to 16 or 17, wherein the substrate is a transmission type or a reflection type mask blank. 20. A transmission or reflection mask blank coated with any one of the chemically amplified positive resist compositions 1 to 15. Effect of the Invention

[0018] The chemically amplified positive resist composition of the present invention can effectively control acid diffusion caused by exposure during pattern formation due to the action of the onium salt represented by formula (A1), and when a resist film is formed using this to form a pattern, a pattern having extremely high resolution, high pattern fidelity, and improved LER and dose margin can be obtained. In addition, due to the action of the repeating unit represented by formula (B1), the composition exhibits good solubility in an alkaline developer, and can improve adhesion to a substrate when forming a resist film.

[0019] The method of forming a resist pattern using the chemically amplified positive resist composition of the present invention is capable of forming a pattern that has high resolution and pattern fidelity, while also improving LER and dose margin, and can therefore be suitably used in microfabrication techniques, in particular EUV lithography and EB lithography. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The present invention will be described in detail below. In the following description, some structures represented by chemical formulas may have asymmetric carbons and may have enantiomers or diastereomers, but in such cases, one formula will be used to represent these isomers. These isomers may be used alone or as a mixture.

[0021] [Chemically amplified positive resist composition] The chemically amplified positive resist composition of the present invention is characterized by comprising: (A) a quencher consisting of an onium salt in which a conjugate acid in the anion moiety is decomposed by the action of acid and heat into carbon dioxide and an organic compound having 12 or less carbon atoms; and (B) a base polymer containing a predetermined polymer.

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

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

[0024] In formula (1), R 1 and R 2are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms, and a part of the -CH2- in the hydrocarbyl group may be substituted with -O- or -C(=O)-. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 10 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl; cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups having 2 to 10 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl; cyclic unsaturated hydrocarbyl groups having 3 to 10 carbon atoms, such as cyclohexenyl; aryl groups having 2 to 10 carbon atoms, such as phenyl and naphthyl; aralkyl groups having 7 to 10 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl; and groups obtained by combining these groups. In addition, a part of -CH2- in the hydrocarbyl group may be replaced with -O- or -C(=O)-.

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

[0026] R 1 and R 2 is a hydrogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms, or R 1 and R 2 are preferably a saturated ring having 3 to 8 carbon atoms formed by bonding together with the carbon atom to which they are bonded, and preferably a hydrogen atom, a saturated hydrocarbyl group having 1 to 4 carbon atoms, or R 1 and R 2are bonded to each other to form a saturated ring having 3 to 6 carbon atoms together with the carbon atom to which they are bonded.

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

[0028] Also, R 1 and R 3may be bonded to each other to form a ring together with the carbon atom to which they are bonded. The ring formed is a corresponding cycloalkyl ketone when X is a single bond, a corresponding lactone ring when X is -O-, and a corresponding thiolactone ring when X is -S-. The ring is preferably a 3- to 8-membered ring, and more preferably a 5- to 7-membered ring. In addition, some or all of the hydrogen atoms in the ring may be substituted with halogen atoms, and some of the -CH2- in the ring may be substituted with -O- or -C(=O)-.

[0029] In addition, R 3 is other than an acid labile group, R 1 ~R 3 The maximum number of carbon atoms contained is 10.

[0030] R 3 The acid labile group represented by the formula (AL-1) or (AL-2) below is preferable. [ka]

[0031] In formula (AL-1), R 4 , R 5 and R 6 are each independently a hydrocarbyl group having 1 to 12 carbon atoms, a part of -CH2- in the hydrocarbyl group may be substituted with -O- or -S-, and when the hydrocarbyl group contains an aromatic ring, a part or all of the hydrogen atoms in the aromatic ring may be substituted with a halogen atom, a cyano group, a nitro group, an alkyl group having 1 to 4 carbon atoms which may contain a halogen atom, or an alkoxy group having 1 to 4 carbon atoms which may contain a halogen atom. n1 is 0 or 1. * represents a bond to the adjacent -O-.

[0032] R 4 , R 5 and R 6The hydrocarbyl group having 1 to 12 carbon atoms represented by the formula (I) may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 12 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, n-decyl, n-undecyl and n-dodecyl groups; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, norbornylmethyl, adamantyl, adamantylmethyl, tricyclo[5.2.1.0 2,6 ]decyl group, tetracyclo[6.2.1.1 3,6 .0 2,7 ]Cyclic saturated hydrocarbyl groups having 3 to 12 carbon atoms, such as a dodecyl group; alkenyl groups having 2 to 12 carbon atoms, such as a vinyl group, an allyl group, a propenyl group, a butenyl group, a pentenyl group, or a hexenyl group; alkynyl groups having 2 to 12 carbon atoms, such as an ethynyl group, a propynyl group, a butynyl group, a pentynyl group, or a hexynyl group; cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 12 carbon atoms, such as a cyclopentenyl group, or a cyclohexenyl group; aryl groups having 6 to 12 carbon atoms, such as a phenyl group, a naphthyl group, or an indanyl group; aralkyl groups having 7 to 12 carbon atoms, such as a benzyl group, a 1-phenylethyl group, or a 2-phenylethyl group; and groups obtained by combining these.

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

[0034] In formula (AL-2), X a is -O- or -S-. 7 and R 8 R are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. 7 and R 8 The hydrocarbyl group having 1 to 10 carbon atoms represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 1 and R 2 Examples of the hydrocarbyl group having 1 to 10 carbon atoms represented by the following formula include the same as those exemplified above.

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

[0036] Examples of the acid labile group represented by formula (AL-1) include, but are not limited to, those shown below: In the following formula, * represents a bond to the adjacent -O-. [ka]

[0037] [ka]

[0038] [ka]

[0039] [ka]

[0040] [ka]

[0041] [ka]

[0042] [ka]

[0043] [ka]

[0044] [ka]

[0045] [ka]

[0046] [ka]

[0047] Examples of the acid labile group represented by formula (AL-2) include, but are not limited to, those shown below: In the following formula, * represents a bond to the adjacent -O-. [ka]

[0048] [ka]

[0049] R 3 When X is a single bond or -S-, it is preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms substituted with a halogen atom, or a cyclic saturated hydrocarbyl group having 3 to 6 carbon atoms, and more preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkyl group having 1 to 3 carbon atoms substituted with a halogen atom, or a cyclic saturated hydrocarbyl group having 3 to 6 carbon atoms. When X is -O-, it is preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms other than acid labile groups, an alkyl group having 1 to 4 carbon atoms other than acid labile groups substituted with a halogen atom, or an acid labile group represented by formula (AL-1) or (AL-2), and more preferably a hydrogen atom, a hydrocarbyl group having 1 to 3 carbon atoms other than acid labile groups, an alkyl group having 1 to 3 carbon atoms other than acid labile groups substituted with a halogen atom, or an acid labile group represented by formula (AL-1) or (AL-2).

[0050] Preferred examples of the anion of the onium salt represented by formula (1) include, but are not limited to, those shown below. [ka]

[0051] [ka]

[0052] [ka]

[0053] [ka]

[0054] [ka]

[0055]

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[0056]

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[0057]

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[0058]

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[0059]

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[0060]

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[0061]

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[0062]

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[0063]

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[0064]

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[0065]

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[0066]

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[0067]

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[0068]

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[0069]

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[0070]

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[0071]

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[0075]

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[0076]

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[0077]

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[0078]

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[0079]

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[0080]

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[0081]

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[0082]

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[0083]

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[0084]

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[0085]

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[0086]

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[0087] [ka]

[0088] [ka]

[0089] [ka]

[0090] [ka]

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

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

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

[0094] The hydrocarbyl groups may be saturated or unsaturated and may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 30 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl groups; cyclic saturated hydrocarbyl groups having 3 to 30 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; alkenyl groups having 2 to 30 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl groups; cyclic unsaturated hydrocarbyl groups having 3 to 30 carbon atoms, such as cyclohexenyl groups; aryl groups having 6 to 30 carbon atoms, such as phenyl, naphthyl, and thienyl groups; aralkyl groups having 7 to 30 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl groups; and groups obtained by combining these, with aryl groups being preferred. In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH2- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

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

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

[0097] [ka]

[0098] [ka]

[0099] [ka]

[0100] [ka]

[0101] [ka]

[0102] [ka]

[0103] [ka]

[0104] [ka]

[0105] [ka]

[0106]

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[0107]

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[0108]

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[0109]

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[0115]

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[0116]

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[0117] [ka]

[0118] [ka]

[0119] [ka]

[0120] [ka]

[0121] [ka]

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

[0123] [ka]

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

[0125] Specific examples of the onium salt represented by formula (A1) include any combination of the above-mentioned anions and cations.

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

[0127] First, the raw material alcohol (SM-A) is reacted with the acid chloride (SM-B) to perform esterification. The raw material alcohol (SM-A) is dissolved in a solvent such as tetrahydrofuran (THF) or acetonitrile, and the acid chloride (SM-B) is added dropwise in the presence of a base such as pyridine or 2,6-lutidine. The reaction can be carried out by heating, etc., as necessary. The reaction time is usually about 2 to 24 hours, although it is desirable to follow the reaction by gas chromatography (GC) or silica gel thin layer chromatography (TLC) in terms of yield and complete the reaction. The intermediate (In-A) can be obtained from the reaction mixture by a conventional aqueous work-up, and if necessary, it can be purified according to conventional methods such as distillation, chromatography, and recrystallization.

[0128] Next, the intermediate (In-A) obtained is subjected to alkaline hydrolysis using a metal hydroxide represented by M-OH to synthesize an intermediate (In-B). The intermediate (In-A) is dissolved in a solvent such as THF or acetonitrile, and an aqueous solution of a metal hydroxide represented by M-OH is dropped to perform alkaline hydrolysis. Examples of the metal hydroxide used include sodium hydroxide, potassium hydroxide, and lithium hydroxide. The reaction can be performed by heating, etc., as necessary. The reaction time is usually about 2 to 24 hours, although it is desirable to follow the reaction by silica gel thin layer chromatography (TLC) in terms of yield and complete the reaction. The intermediate (In-B) can be obtained from the reaction mixture by a normal aqueous work-up, and if necessary, it can be purified according to a normal method such as chromatography or recrystallization.

[0129] The final step is to convert the obtained intermediate (In-B) into Z + X - By salt exchange with an onium salt represented by the formula: - As the ions, hydrogen carbonate ions, chloride ions, and bromide ions are preferred since the exchange reaction easily proceeds quantitatively.

[0130] In the above scheme, the third step of ion exchange can be easily carried out by a known method, for example, see JP-A-2007-145797.

[0131] It should be noted that the production method according to the above scheme is merely an example, and the production method of the onium salt is not limited thereto.

[0132] Another example of the synthesis method of the onium salt represented by formula (A1) is a method of ion-exchanging a carboxylic acid having an anion in formula (A1) with an onium salt of an acid weaker than the carboxylic acid. An example of an acid weaker than the carboxylic acid is carbonic acid. Alternatively, the onium salt can be synthesized by ion-exchanging a sodium salt of a carboxylic acid having an anion in formula (A1) with a sulfonium chloride.

[0133] When the onium salt represented by formula (A1) is used in a chemically amplified positive resist composition, it functions extremely effectively as a quencher.

[0134] Onium salts having these structures act as quenchers and effectively trap the strong acid generated by the acid generator, forming a 1,3-dicarboxylic acid monoester or 1,3-ketocarboxylic acid structure. 3 When the acid labile group is formed with the adjacent oxygen atom, the acid labile group is eliminated by reacting with a strong acid, improving the sensitivity of the resist film and forming a 1,3-dicarboxylic acid (e.g., malonic acid) structure. In the next PEB process, the 1,3-dicarboxylic acid monoester, 1,3-ketocarboxylic acid, and 1,3-dicarboxylic acid undergo a decarboxylation reaction due to heat, decomposing them into carbon dioxide and the corresponding acetic acid derivative or ketone derivative, which volatilizes from the film. During the subsequent development with an alkaline developer, swelling is suppressed because the carboxylic acid having a high affinity with the alkaline developer is no longer present, and the collapse of the resist pattern, which has been a problem in forming fine patterns, can be suppressed. Therefore, the onium salt represented by formula (A1) is suitable for application to a chemically amplified positive resist composition.

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

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

[0137] In formula (B1), a1 is 0 or 1. a2 is an integer of 0 to 2, and when it is 0, it represents a benzene skeleton, when it is 1, it represents a naphthalene skeleton, and when it is 2, it represents an anthracene skeleton. a3 is an integer that satisfies 0≦a3≦5+2(a2)-a4. a4 is an integer of 1 to 3. When a2 is 0, a3 is preferably an integer of 0 to 3 and a4 is an integer of 1 to 3, and when a2 is 1 or 2, a3 is preferably an integer of 0 to 4 and a4 is an integer of 1 to 3.

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

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

[0140] In formula (B1), A 1is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- of the saturated hydrocarbylene group may be replaced by -O-. The saturated hydrocarbylene group may be linear, branched, or cyclic, and specific examples thereof include alkanediyl groups having 1 to 10 carbon atoms, such as methylene, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, and structural isomers thereof; cyclic saturated hydrocarbylene groups having 3 to 10 carbon atoms, such as cyclopropanediyl, cyclobutanediyl, cyclopentanediyl, and cyclohexanediyl; and groups obtained by combining these. When the saturated hydrocarbylene group contains an ether bond, when a1 in formula (B1) is 1, it may be located at any position except between the carbon atom at the α-position and the carbon atom at the β-position relative to the ester oxygen atom. When a1 is 0, the atom bonded to the main chain is an etheric oxygen atom, and the second ether bond may be inserted at any position except between the carbon atom at the α-position and the carbon atom at the β-position with respect to the etheric oxygen atom. If the number of carbon atoms in the saturated hydrocarbylene group is 10 or less, sufficient solubility in an alkaline developer can be obtained, which is preferable.

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

[0142] a1 is 1 (i.e., -C(=O)-OA as a linker 1In the case where R A is the same as above. [ka]

[0143] The content of the repeating unit B1 is preferably 10 to 95 mol %, more preferably 40 to 90 mol %, of all repeating units constituting the polymer. However, when the repeating unit contains at least one of the repeating units represented by formula (B3) and the repeating unit represented by formula (B4), which give the polymer higher etching resistance as described below, and the unit has a phenolic hydroxyl group as a substituent, it is preferable that the ratio of the unit is also within the above range. The repeating unit B1 may be used alone or in combination of two or more kinds.

[0144] In order to provide the polymer with the property of dissolving the exposed portion in an alkaline developer as a positive resist composition, it is preferable that the polymer contains a repeating unit having an acidic functional group protected by an acid labile group, i.e., a repeating unit that is protected by an acid labile group and becomes alkaline soluble by the action of an acid (hereinafter, also referred to as repeating unit B2). In this case, the acid labile group (protecting group) in the repeating unit undergoes a deprotection reaction by the action of an acid, so that the polymer exhibits better solubility in an alkaline developer.

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

[0146] In formula (B2-1), b1 is 0 or 1. b2 is an integer of 0 to 2, and when it is 0, it represents a benzene skeleton, when it is 1, it represents a naphthalene skeleton, and when it is 2, it represents an anthracene skeleton. b3 is an integer that satisfies 0≦b3≦5+2(b2)-b4. b4 is an integer of 1 to 3. b5 is 0 or 1. When b2 is 0, b3 is preferably an integer of 0 to 3 and b4 is an integer of 1 to 3, and when b2 is 1 or 2, b3 is preferably an integer of 0 to 4 and b4 is an integer of 1 to 3.

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

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

[0149] In formula (B2-1), A 2is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- of the saturated hydrocarbylene group may be replaced by -O-. The saturated hydrocarbylene group may be linear, branched, or cyclic, and specific examples thereof include alkanediyl groups having 1 to 10 carbon atoms, such as methylene, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, and structural isomers thereof; cyclic saturated hydrocarbylene groups having 3 to 10 carbon atoms, such as cyclopropanediyl, cyclobutanediyl, cyclopentanediyl, and cyclohexanediyl; and groups obtained by combining these. When the saturated hydrocarbylene group contains an ether bond, when b1 in formula (B2-1) is 1, it may be located at any position except between the carbon atom at the α position and the carbon atom at the β position relative to the ester oxygen atom. When b1 is 0, the atom bonded to the main chain is an ether oxygen atom, and the second ether bond may be inserted at any position except between the carbon atom at the α-position and the carbon atom at the β-position with respect to the ether oxygen atom. If the number of carbon atoms in the saturated hydrocarbylene group is 10 or less, sufficient solubility in an alkaline developer can be obtained, which is preferable.

[0150] In formula (B2-1), when b4 is 1, X is an acid labile group, and when b4 is 2 or more, X is a hydrogen atom or an acid labile group, with at least one of them being an acid labile group. That is, in the repeating unit B2-1, at least one of the phenolic hydroxy groups bonded to the aromatic ring is protected with an acid labile group, or the carboxy group bonded to the aromatic ring is protected with an acid labile group. The acid labile group is not particularly limited and any of those that have been used in many known chemically amplified resist compositions and that are released by an acid to give an acidic group can be used. Specific examples of the acid labile group include R 1Examples of the acid labile group include the same as those exemplified as the acid labile group represented by the formula: In addition, as another example of the acid labile group, a group in which the hydrogen atom of a phenolic hydroxyl group is substituted with -CH2COO- (a tertiary saturated hydrocarbyl group) can also be used. In this case, the tertiary saturated hydrocarbyl group can be the same as the tertiary saturated hydrocarbyl group used for protecting the phenolic hydroxyl group described above.

[0151] Further, the repeating unit B2 may be a repeating unit represented by the following formula (B2-2) (hereinafter, also referred to as repeating unit B2-2). The repeating unit B2-2 is a useful option as an acid labile group-containing unit that provides good performance against line width fluctuation in development loading because it increases the dissolution rate of the exposed area. [ka]

[0152] In formula (B2-2), c1 is an integer of 0 to 2. c2 is an integer of 0 to 2. c3 is an integer of 0 to 5. c4 is an integer of 0 to 2.

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

[0154] In formula (B2-2), R 13 and R 14 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom, R 13 and R 14 may be bonded to each other to form a ring together with the carbon atoms to which they are attached.

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

[0156] In formula (B2-2), R 16are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom.

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

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

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

[0160] The polymer may further include at least one selected from the group consisting of a repeating unit represented by the following formula (B3) (hereinafter also referred to as repeating unit B3), a repeating unit represented by the following formula (B4) (hereinafter also referred to as repeating unit B4), and a repeating unit represented by the following formula (B5) (hereinafter also referred to as repeating unit B5). [ka]

[0161] In the formulae (B3) and (B4), d and e each independently represent an integer of 0 to 4.

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

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

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

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

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

[0167] In addition, the saturated hydrocarbyl carbonyloxy group can be easily introduced by chemical modification even after polymerization of the polymer, and can be used to finely adjust the solubility of the base polymer in an alkaline developer. Examples of the saturated hydrocarbyl carbonyloxy group include methyl carbonyloxy group, ethyl carbonyloxy group, propyl carbonyloxy group, butyl carbonyloxy group, pentyl carbonyloxy group, hexyl carbonyloxy group, cyclopentyl carbonyloxy group, cyclohexyl carbonyloxy group, benzoyloxy group, and structural isomers of these hydrocarbon moieties. If the carbon number is 20 or less, the effect of controlling and adjusting (mainly the effect of reducing) the solubility of the base polymer in an alkaline developer can be made appropriate, and the occurrence of scum (development defects) can be suppressed.

[0168] Among the above-mentioned preferable substituents, examples of the substituents which are particularly easy to prepare as a monomer and are usefully used include a chlorine atom, a bromine atom, an iodine atom, a methyl group, an ethyl group, and a methoxy group.

[0169] In formula (B5), A 4is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- of the saturated hydrocarbylene group may be replaced by -O-. The saturated hydrocarbylene group may be linear, branched, or cyclic, and specific examples thereof include alkanediyl groups having 1 to 10 carbon atoms, such as methylene, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, and structural isomers thereof; cyclic saturated hydrocarbylene groups having 3 to 10 carbon atoms, such as cyclopropanediyl, cyclobutanediyl, cyclopentanediyl, and cyclohexanediyl; and groups obtained by combining these. When the saturated hydrocarbylene group contains an ether bond, when f1 in formula (B5) is 1, it may be located at any position except between the carbon atom at the α position and the carbon atom at the β position relative to the ester oxygen atom. When f1 is 0, the atom bonded to the main chain is an ether oxygen atom, and the second ether bond may be inserted at any position except between the carbon atom at the α-position and the carbon atom at the β-position with respect to the ether oxygen atom. If the number of carbon atoms in the saturated hydrocarbylene group is 10 or less, sufficient solubility in an alkaline developer can be obtained, which is preferable.

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

[0171] Also, when f1 is 1 (i.e., -C(=O)-OA as a linker 4 Preferred examples of the repeating unit B5, when R A is the same as above. [ka]

[0172] [ka]

[0173] When at least one of the repeating units B3 to B5 is used as a structural unit of the polymer, the addition of a ring structure to the main chain provides an effect of improving the etching resistance of the aromatic ring as well as the EB irradiation resistance during pattern inspection.

[0174] In order to obtain the effect of improving etching resistance, the content of the repeating units B3 to B5 is preferably 5 mol % or more of all the repeating units constituting the polymer. The content of the repeating units B3 to B5 is preferably 35 mol % or less, more preferably 30 mol % or less of all the repeating units constituting the polymer. When there is no functional group or when the functional group is other than a hydroxy group, it is preferable that the amount of introduction is 35 mol % or less, since there is no risk of development defects occurring. The repeating units B3 to B5 may be used alone or in combination of two or more.

[0175] The polymer preferably contains at least one selected from the group consisting of repeating units B1, B2, and B3 to B5, in that it is excellent in achieving both high etching resistance and high resolution. In this case, these repeating units are preferably contained in an amount of 60 mol % or more, more preferably 70 mol % or more, and even more preferably 80 mol % or more of all repeating units constituting the polymer.

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

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

[0178] In formulae (B6) and (B10), Xa - is a non-nucleophilic counterion. - Examples of non-nucleophilic counter ions represented by the formula (I) include those described in JP-A-2010-113209 and JP-A-2007-145797.

[0179] In formulas (B7) and (B11), Y 2 -Y 21 -C(=O)-O-, Y 21 Examples of the hydrocarbylene group which may contain a heteroatom and is represented by the following formula (I) include, but are not limited to, the following groups: [ka] (In the formula, the dashed lines represent bonds.)

[0180] In formulas (B7) and (B11), R HF is a hydrogen atom or a trifluoromethyl group. In the repeating units B7 and B11, R HFSpecific examples of when R is a hydrogen atom include those described in JP 2010-116550 A. HF Specific examples of the repeating units B8 and B12 when is a trifluoromethyl group include those described in JP-A-2010-77404. Examples of the repeating units B8 and B12 include those described in JP-A-2012-246265 and JP-A-2012-246426.

[0181] Preferred examples of the anion of the monomer that provides the repeating unit B9 or B13 include, but are not limited to, those shown below. [ka]

[0182] [ka]

[0183] In formulas (B6) to (B13), R 31 ~R 48 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated and may be linear, branched or cyclic. Specific examples of the halogen atom and hydrocarbyl group include R c1 ~R c9Examples of the halogen atom and hydrocarbyl group represented by the formula (I) include the same as those exemplified above. In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

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

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

[0186] The repeating units B6 to B13 are units that generate acid by irradiation with high energy rays. It is considered that the inclusion of these units in the polymer appropriately suppresses acid diffusion, and a pattern with improved LER and CDU can be obtained. In addition, the inclusion of these units in the polymer suppresses the phenomenon in which acid volatilizes from the exposed area and reattaches to the unexposed area during baking in a vacuum, and is therefore effective in improving LER and CDU, and reducing pattern defects due to the suppression of undesired deprotection reactions in the unexposed area.

[0187] When the polymer contains the repeating units B6 to B13, the content thereof is preferably 0.5 to 30 mol % of all the repeating units constituting the polymer. The repeating units B6 to B13 may be used alone or in combination of two or more.

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

[0189] The polymer may contain a commonly used (meth)acrylic acid ester unit protected by an acid labile group, or a (meth)acrylic acid ester unit having an adhesive group such as a lactone structure or a hydroxy group other than a phenolic hydroxy group. Although these repeating units allow fine adjustment of the properties of the resist film, they may not be included.

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

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

[0192] When the repeating units B14 to B16 are contained, the content thereof is preferably 0 to 30 mol %, more preferably 0 to 20 mol %, of all the repeating units constituting the polymer. The repeating units B14 to B16 may be used alone or in combination of two or more kinds.

[0193] The polymer can be synthesized by copolymerizing each monomer protected by a protecting group as necessary by a known method, and then carrying out a deprotection reaction as necessary. The copolymerization reaction is not particularly limited, but is preferably radical polymerization or anionic polymerization. For these methods, JP-A-2004-115630 can be referred to.

[0194] The polymer preferably has a weight average molecular weight (Mw) of 1000 to 50000, more preferably 2000 to 20000. If Mw is 1000 or more, there is no risk of the phenomenon that the head of the pattern becomes rounded, the resolution decreases, and LER and CDU deteriorate, as has been known in the past. On the other hand, if Mw is 50000 or less, there is no risk of LER and CDU deterioration, especially when forming a pattern with a pattern line width of 100 nm or less. In the present invention, Mw is a value measured in terms of polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran (THF) or dimethylformamide (DMF) as a solvent.

[0195] The polymer preferably has a narrow molecular weight distribution (Mw / Mn) of 1.0 to 2.0, particularly 1.0 to 1.8, in which case the polymer is free from foreign matter on the pattern and from deterioration of the pattern shape after development.

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

[0197] Specific examples of the photoacid generator include nonafluorobutanesulfonate, the partially fluorinated sulfonates described in JP-A-2012-189977, paragraphs

[0247] to

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

[0261] to

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

[0122] to

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

[0080] to

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

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

[0199] As the photoacid generator, a salt compound having the anion shown below is preferable. [ka]

[0200] [ka]

[0201] [ka]

[0202] [ka]

[0203] [ka]

[0204] [ka]

[0205] [ka]

[0206] [ka]

[0207] Examples of the cation paired with the anion include those exemplified as the sulfonium cation represented by formula (cation-1) and those exemplified as the iodonium cation represented by formula (cation-2).

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

[0209] When the chemically amplified positive resist composition of the present invention contains a quencher, component (A), and a photoacid generator, component (C), the content ratio of the photoacid generator to the quencher ((C) / (A)) is preferably less than 6, more preferably less than 5, and even more preferably less than 4. When the content ratio of the photoacid generator to the quencher contained in the chemically amplified positive resist composition is within the above range, acid diffusion can be sufficiently suppressed, and excellent resolution and dimensional uniformity can be obtained.

[0210] [(D) Fluorine atom-containing polymer] The chemically amplified positive resist composition of the present invention, for the purposes of increasing contrast, suppressing chemical flare of acid upon irradiation with high-energy rays, shielding mixing of acid from the antistatic film in the process of applying an antistatic film material onto the resist film, and suppressing unexpected and unnecessary pattern degradation, may contain, as the component (D), a fluorine-containing polymer that contains at least one selected from the group consisting of a repeating unit represented by formula (D1) below (hereinafter also referred to as repeating unit D1), a repeating unit represented by formula (D2) below (hereinafter also referred to as repeating unit D2), a repeating unit represented by formula (D3) below (hereinafter also referred to as repeating unit D3), and a repeating unit represented by formula (D4) below (hereinafter also referred to as repeating unit D4), and may further contain at least one selected from the group consisting of a repeating unit represented by formula (D5) below (hereinafter also referred to as repeating unit D5) and a repeating unit represented by formula (D6) below (hereinafter also referred to as repeating unit D6). The fluorine atom-containing polymer also functions as a surfactant, and is therefore effective against development defects since it can prevent insoluble matter from re-adhering to the substrate during the development process. [ka]

[0211] In the formulas (D1) to (D6), x is an integer of 1 to 3. y is an integer satisfying 0≦y≦5+2z−x. z is 0 or 1. h is an integer of 1 to 3. R C R are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. D R is each independently a hydrogen atom or a methyl group. 101 , R 102 , R 104 and R 105 R are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. 103 , R 106 , R 107 and R 108 each independently represents a hydrogen atom, a hydrocarbyl group having 1 to 15 carbon atoms, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid labile group; R103 , R 106 , R 107 and R 108 When R is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bonds. 109 R is a hydrogen atom or a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a heteroatom-containing group interposed between the carbon-carbon bonds. 110 R is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a heteroatom-containing group between its carbon-carbon bonds. 111 Z is a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, and a part of the -CH2- in the saturated hydrocarbyl group may be substituted with an ester bond or an ether bond. 1 Z is a (h+1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (h+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * is a bond to a carbon atom in the main chain. Z 3 is a single bond, -O-, *-C(=O)-OZ 31 -Z 32 - or -C(=O)-NH-Z 31 -Z 32 -It is. 31 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. 32 is a single bond, an ester bond, an ether bond or a sulfonamide bond. * is a bond to a carbon atom of the main chain.

[0212] In formulas (D1) and (D2), R 101 , R 102 , R 104 and R 105The saturated hydrocarbyl group having 1 to 10 carbon atoms represented by the formula (I) may be linear, branched or cyclic, and specific examples thereof include alkyl groups having 1 to 10 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group or an n-decyl group; and cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group or a norbornyl group. Of these, saturated hydrocarbyl groups having 1 to 6 carbon atoms are preferred.

[0213] In formulas (D1) to (D4), R 103 , R 106 , R 107 and R 108 The hydrocarbyl group having 1 to 15 carbon atoms represented by the formula (I) may be linear, branched, or cyclic, and specific examples thereof include an alkyl group having 1 to 15 carbon atoms, an alkenyl group having 2 to 15 carbon atoms, and an alkynyl group having 2 to 15 carbon atoms, and an alkyl group having 1 to 15 carbon atoms is preferred. In addition to the above, examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, and an n-pentadecyl group. Examples of the fluorinated hydrocarbyl group include a group in which some or all of the hydrogen atoms bonded to the carbon atoms of the above-mentioned hydrocarbyl group are substituted with fluorine atoms.

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

[0215] Specific examples of the repeating units D1 to D4 include, but are not limited to, those shown below. C is the same as above. [ka]

[0216] [ka]

[0217] [ka]

[0218] In formula (D5), R 109 and R 110 Examples of the hydrocarbyl group having 1 to 5 carbon atoms represented by the formula (1) include an alkyl group, an alkenyl group, and an alkynyl group, with an alkyl group being preferred. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and an n-pentyl group. In addition, a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom may be present between the carbon-carbon bonds of the hydrocarbyl group.

[0219] In formula (D5), -OR 109 is preferably a hydrophilic group. In this case, R 109 is preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms and an oxygen atom intervening between the carbon-carbon bonds, or the like.

[0220] In formula (D5), Z 2 is preferably *-C(=O)-O- or *-C(=O)-NH-. Dis preferably a methyl group. 2 The presence of a carbonyl group in R improves the acid trapping ability of the antistatic film. D When the methyl group is used, the polymer becomes more rigid with a higher glass transition temperature (Tg), which suppresses the diffusion of acid. This improves the stability of the resist film over time, and the resolution and pattern shape do not deteriorate.

[0221] Examples of the repeating unit D5 include, but are not limited to, those shown below. In the following formula, R D is the same as above. [ka]

[0222] [ka]

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

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

[0225] Examples of the repeating unit D6 include, but are not limited to, those shown below. In the following formula, R D is the same as above. [ka]

[0226] [ka]

[0227] [ka]

[0228] [ka]

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

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

[0046] to

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

[0231] The fluorine-containing polymer can be synthesized by copolymerizing each monomer protected by a protecting group as necessary by a known method, and then carrying out a deprotection reaction as necessary. The copolymerization reaction is not particularly limited, but is preferably radical polymerization or anionic polymerization. For these methods, JP-A-2004-115630 can be referred to.

[0232] The Mw of the fluorine atom-containing polymer is preferably 2000 to 50000, more preferably 3000 to 20000. If the Mw is less than 2000, the diffusion of the acid is promoted, which may result in deterioration of the resolution and deterioration of the stability over time. If the Mw is too large, the solubility in the solvent may decrease, which may cause coating defects. Furthermore, the Mw / Mn of the fluorine atom-containing polymer is preferably 1.0 to 2.2, more preferably 1.0 to 1.7.

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

[0234] [(E) Organic solvent] The chemically amplified positive resist composition of the present invention may contain an organic solvent as component (E). There are no particular limitations on the organic solvent as long as it is capable of dissolving each component. Examples of such organic solvents include ketones such as cyclohexanone, cyclopentanone, methyl-2-n-pentyl ketone, and 2-heptanone, as described in paragraphs

[0144] and

[0145] of JP-A-2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol; propylene glycol monomethyl ether (PGME), ethylene glycol monomethyl ether, propylene glycol monoethyl ether, and ethylene glycol monoethyl ether. Examples of suitable solvents include ethers such as propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate, ethyl lactate (EL), ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propylene glycol monotert-butyl ether acetate, esters such as lactones such as γ-butyrolactone, and mixed solvents thereof. When an acetal-based acid labile group is used, a high-boiling alcohol solvent, specifically diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, 1,3-butanediol, etc., can be added to accelerate the deprotection reaction of the acetal.

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

[0236] When the chemically amplified positive resist composition of the present invention contains an organic solvent (E), the content thereof is preferably 200 to 10,000 parts by mass, and more preferably 400 to 5,000 parts by mass, relative to 80 parts by mass of the base polymer (B). The organic solvent (E) may be used alone or in combination of two or more kinds.

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

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

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

[0240] [(G) Surfactant] The chemically amplified positive resist composition of the present invention may contain a commonly used surfactant in order to improve the coating properties on the substrate. Many of the surfactants are known, as described in JP-A-2004-115630, and the surfactant can be selected with reference to these. When the chemically amplified positive resist composition of the present invention contains the surfactant (G), the content thereof is preferably 0 to 5 parts by mass relative to 80 parts by mass of the base polymer (B). The surfactant (G) may be used alone or in combination of two or more kinds.

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

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

[0243] Next, the resist film is exposed to a high-energy ray to irradiate a pattern. Examples of the high-energy ray include ultraviolet ray, far ultraviolet ray, excimer laser light (KrF, ArF, etc.), EUV, X-ray, γ-ray, synchrotron radiation, EB, etc. In the present invention, it is preferable to use EUV or EB for exposure.

[0244] When ultraviolet rays, far ultraviolet rays, excimer laser light, EUV, X-rays, gamma rays or synchrotron radiation is used as the high energy rays, a mask for forming a desired pattern is used and the exposure dose is preferably 1 to 500 mJ / cm. 2 , more preferably 10 to 400 mJ / cm 2 When EB is used, the exposure dose is preferably 1 to 500 μC / cm 2 directly to form the desired pattern. 2 , more preferably 10 to 400 μC / cm 2 Irradiate so that

[0245] The exposure may be performed by a conventional exposure method, or in some cases by an immersion method in which the space between the mask and the resist film is immersed in liquid. In this case, a water-insoluble protective film may be used.

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

[0247] Thereafter, the substrate is developed using a developer of an alkaline aqueous solution such as 0.1 to 5 mass %, and preferably 2 to 3 mass %, tetramethylammonium hydroxide (TMAH) or the like by a standard method such as a dip method, a puddle method, or a spray method for preferably 0.1 to 3 minutes, and more preferably 0.5 to 2 minutes, to form a desired pattern on the substrate.

[0248] The chemically amplified positive resist composition of the present invention is useful because it can form a pattern with particularly good resolution and small LER. Also, the chemically amplified positive resist composition of the present invention is particularly useful for pattern formation on a substrate having a surface made of a material that is prone to pattern peeling or pattern collapse because it is difficult to obtain adhesion of the resist pattern. Examples of such substrates include substrates having a sputtering film formed on the outermost surface of a chromium compound containing one or more light elements selected from metallic chromium, oxygen, nitrogen, and carbon, SiO, SiO x , a tantalum compound, a molybdenum compound, a cobalt compound, a nickel compound, a tungsten compound, or a tin compound in the outermost layer. The chemically amplified positive resist composition of the present invention is particularly useful for pattern formation using a photomask blank as the substrate. In this case, the photomask blank may be either a transmission type or a reflection type.

[0249] As a transmission type mask blank, a photomask blank having a light-shielding film made of a chromium-based material may be a photomask blank for a binary mask or a photomask blank for a phase shift mask. In the case of a photomask blank for a binary mask, the light-shielding film may have an antireflection layer and a light-shielding layer made of a chromium-based material, and the entire antireflection film on the surface layer side or only the surface layer side of the antireflection film on the surface layer side may be made of a chromium-based material, and the remaining part may be made of a silicon-based compound material that may contain a transition metal, for example. In the case of a photomask blank for a phase shift mask, a photomask blank for a phase shift mask having a chromium-based light-shielding film on a phase shift film may be the target.

[0250] The above-mentioned photomask blank having a chromium-based material in the outermost layer is very well known, as exemplified in JP2008-26500A and JP2007-302873A or as prior art therein, and detailed description will be omitted. For example, when forming a light-shielding film having an antireflection layer and a light-shielding layer using a chromium-based material, the following film configuration can be used.

[0251] When a light-shielding film having an anti-reflection layer and a light-shielding layer is formed using a chromium-based material, the layer structure may be such that the anti-reflection layer and the light-shielding layer are laminated in this order from the surface layer side, or the anti-reflection layer, the light-shielding layer, and the anti-reflection layer are laminated in this order. The anti-reflection layer and the light-shielding layer may each be multi-layered, and the composition between layers having different compositions may change discontinuously or may change continuously. As the chromium-based material to be used, a material containing light elements such as oxygen, nitrogen, and carbon in metal chromium is used. Specifically, metal chromium, chromium oxide, chromium nitride, chromium carbide, chromium oxide nitride, chromium carbide oxide, chromium nitride, chromium oxynitride, etc. may be used.

[0252] The reflective mask blank includes a substrate, a multilayer reflective film formed on one main surface (front surface) of the substrate, specifically, a multilayer reflective film that reflects exposure light such as EUV light, and an absorber film formed on the multilayer reflective film, specifically, an absorber film that absorbs exposure light such as EUV light and reduces reflectance. From the reflective mask blank (EUV reflective mask blank), a reflective mask (EUV reflective mask) having an absorber pattern (absorber film pattern) formed by patterning the absorber film is 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.

[0253] The multilayer reflective film is usually preferably provided in contact with one main surface of the substrate, but it is also possible to provide an undercoat film between the substrate and the multilayer reflective film, provided that the effect of the present invention is not lost. The absorber film may be formed in contact with the multilayer reflective film, but a protective film (protective film for the multilayer reflective film) may be provided between the multilayer reflective film and the absorber film, preferably in contact with the multilayer reflective film, more preferably 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 is preferably one that has the function of protecting the multilayer reflective film when the absorber film is patterned by etching, and preventing the oxidation of the multilayer reflective film. On the other hand, a conductive film used for electrostatic chucking the reflective mask to the exposure device may be provided under the other main surface (back surface) that is the surface opposite to the one main surface of the substrate, preferably in contact with the other main surface. In this embodiment, one main surface of the substrate is the front surface and the upper side, and the other main surface is the back surface and the lower side, but the front and back and the top and bottom of both are defined for convenience, and the one main surface and the other main surface are either of the two main surfaces (film formation surfaces) of the substrate, and the front and back and the top and bottom are interchangeable. More specifically, it can be formed by a method such as that exemplified in JP 2021-139970 A or the prior art therein.

[0254] According to the method of forming a resist pattern of the present invention, even when using a substrate (e.g. a photomask blank) whose outermost surface is made of a material that is likely to affect the resist pattern shape, such as a material containing chromium or silicon, the chemically amplified positive resist composition of the present invention efficiently controls acid diffusion at the substrate interface, making it possible to form a pattern that has high resolution and pattern fidelity, as well as improved LER and dose margin. EXAMPLES

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

[0256] [1] Preparation of chemically amplified positive resist composition [Examples 1-1 to 1-40, Comparative Examples 1-1 to 1-8] Chemically amplified positive resist compositions (R-1 to R-40, CR-1 to CR-4) were prepared by dissolving each component in an organic solvent according to the composition shown in Tables 1 to 3 below, and filtering each of the resulting solutions through a UPE filter and / or a nylon filter selected from 10 nm, 5 nm, 3 nm, and 1 nm sizes. The organic solvent is a mixed solvent of 900 parts by mass of PGMEA, 1800 parts by mass of EL, and 1800 parts by mass of PGME.

[0257] [Table 1]

[0258] [Table 2]

[0259] [Table 3]

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

[0261] [ka]

[0262] [ka]

[0263] [ka]

[0264] [ka]

[0265] [ka]

[0266] [ka]

[0267] [ka]

[0268] [ka]

[0269] [2] EB lithography evaluation [Examples 2-1 to 2-40, Comparative Examples 2-1 to 2-8] Each chemically amplified positive resist composition (R-1 to R-40, CR-1 to CR-8) was spin-coated onto a 152 mm square mask blank, the outermost surface of which was a silicon oxide film, that had been vapor primed with hexamethyldisilazane (HMDS) using ACT-M (Tokyo Electron Ltd.), and pre-baked on a hot plate at 110°C for 600 seconds to produce a resist film with a thickness of 80 nm. The thickness of the resulting resist film was measured using an optical measuring device Nanospec (Nanometrics). Measurements were performed at 81 points on the surface of the blank substrate, excluding the outer edge portion from the outer periphery to the inside by 10 mm, and the average thickness and thickness range were calculated.

[0270] The film was exposed using an electron beam exposure device (EBM-5000plus, manufactured by NuFlare Technology, Inc., acceleration voltage 50 kV), subjected to PEB at 120° C. for 600 seconds, and developed with a 2.38 mass % TMAH aqueous solution to obtain a positive pattern.

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

[0272] [Table 4]

[0273] [Table 5]

[0274] [Table 6]

[0275] The chemically amplified positive resist compositions (R-1 to R-40) of the present invention containing the onium salt represented by formula (A1) effectively controlled acid diffusion and exhibited good resolution, as well as good values ​​for LER and dose margin, compared to the comparative resist compositions (CR-1 to CR-8).

[0276] As described above, by using the chemically amplified positive resist composition of the present invention, it is possible to form a pattern with extremely high resolution and excellent LER and dose margin. The method for forming a resist pattern using the chemically amplified positive resist composition of the present invention is useful for the production of semiconductor devices, particularly for photolithography in the processing of transmission or reflection mask blanks.

Claims

1. A chemically amplified positive resist composition comprising: (A) a quencher consisting of an onium salt represented by the following formula (A1); and (B) a base polymer containing a polymer that contains a repeating unit represented by the following formula (B1), and that decomposes under the action of an acid and has increased solubility in an alkaline developer. [Case 1] (In the formula, X is a single bond, —O—, or —S—. R 1 and R 2 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms, and the —CH 2 A part of - may be replaced by -O- or -C(=O)-. 1 and R 2 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 3 When X is a single bond or -S-, it is a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms, and when X is -O-, it is a hydrogen atom, a hydrocarbyl group having 1 to 10 carbon atoms other than an acid labile group, or an acid labile group, in which some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with halogen atoms, and -CH of the hydrocarbyl group is 2 A part of - may be replaced by -O- or -C(=O)-, R 1 and R 3 may be bonded to each other to form a ring together with the atoms to which they are bonded and the atoms therebetween. 3 is other than an acid labile group, R 1 ~R 3 The upper limit of the number of carbon atoms contained in the Z + is an onium cation. [Case 2] (In the formula, a1 is 0 or 1. a2 is an integer from 0 to 2. a3 is an integer that satisfies 0≦a3≦5+2(a2)−a4. a4 is an integer from 1 to 3. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 11 represents a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. A 1 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the —CH 2 - may be replaced by -O-.

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

3. R 3 3. The chemically amplified positive resist composition according to claim 2, wherein is an acid labile group.

4. 2. The chemically amplified positive resist composition according to claim 1, wherein the acid labile group is represented by the following formula (AL-1) or (AL-2): [C3] (In the formula, X a is —O— or —S—. R 4 , R 5 and R 6 are each independently a hydrocarbyl group having 1 to 12 carbon atoms, 2 A part of - may be substituted with -O- or -S-, and when the hydrocarbyl group contains an aromatic ring, a part or all of the hydrogen atoms of the aromatic ring may be substituted with a halogen atom, a cyano group, a nitro group, an alkyl group having 1 to 4 carbon atoms which may contain a halogen atom, or an alkoxy group having 1 to 4 carbon atoms which may contain a halogen atom. 4 , R 5 and R 6 may be bonded to each other to form a ring, and the -CH 2 A part of - may be substituted with -O- or -S-. R 7 and R 8are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. 9 is a hydrocarbyl group having 1 to 20 carbon atoms, and the —CH 2 A part of - may be replaced by -O- or -S-. 8 and R 9 and are bonded to each other, and the carbon atom and X a may form a heterocyclic group having 3 to 20 carbon atoms together with the heterocyclic group, and the —CH 2 A part of - may be substituted with -O- or -S-. n1 and n2 each independently represent 0 or 1. * represents a bond to the adjacent -O-.)

5. Z + 2. The chemically amplified positive resist composition according to claim 1, wherein is an onium cation represented by any one of the following formulas (category-1) to (category-3): [C4] (In the formula, R c1 ~R c9 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. c1 and R c2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.)

6. 2. The chemically amplified positive resist composition according to claim 1, wherein the polymer further contains a repeating unit represented by the following formula (B2-1): [C5] (In the formula, b1 is 0 or 1. b2 is an integer from 0 to 2. b3 is an integer satisfying 0≦b3≦5+2(b2)−b4. b4 is an integer from 1 to 3. b5 is 0 or 1. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 12represents a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. A 2 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the —CH 2 - may be replaced by -O-. When b4 is 1, X is an acid labile group. When b4 is 2 or 3, X is each independently a hydrogen atom or an acid labile group, provided that at least one X is an acid labile group.

7. 2. The chemically amplified positive resist composition according to claim 1, wherein the polymer further contains a repeating unit represented by the following formula (B2-2): [C6] (In the formula, c1 is an integer from 0 to 2. c2 is an integer from 0 to 2. c3 is an integer from 0 to 5. c4 is an integer from 0 to 2. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 13 and R 14 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom; R 13 and R 14 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 15 each independently represents a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, or a fluorinated alkoxy group having 1 to 5 carbon atoms. R 16 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. A 3 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-O-A 31 - is. 31is an aliphatic hydrocarbylene group having 1 to 20 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring, or a phenylene group or naphthylene group. * is a bond to a carbon atom of the main chain.)

8. 2. The chemically amplified positive resist composition according to claim 1, wherein the polymer further comprises at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (B3), a repeating unit represented by the following formula (B4), and a repeating unit represented by the following formula (B5): [C7] (In the formula, d and e each independently represent an integer of 0 to 4. f1 is 0 or 1. f2 is an integer of 0 to 2. f3 is an integer of 0 to 5. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 21 and R 22 each independently represents a hydroxy group, a halogen atom, a saturated hydrocarbyl group having 1 to 8 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 8 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. R 23 is a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbyloxyhydrocarbyl group having 2 to 20 carbon atoms, a saturated hydrocarbylthiohydrocarbyl group having 2 to 20 carbon atoms, a halogen atom, a nitro group, a cyano group, a saturated hydrocarbylsulfinyl group having 1 to 20 carbon atoms, or a saturated hydrocarbylsulfonyl group having 1 to 20 carbon atoms. A 4 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the —CH 2 - may be replaced by -O-.

9. 2. The chemically amplified positive resist composition according to claim 1, wherein the polymer further comprises at least one selected from a repeating unit represented by the following formula (B6), a repeating unit represented by the following formula (B7), a repeating unit represented by the following formula (B8), a repeating unit represented by the following formula (B9), a repeating unit represented by the following formula (B10), a repeating unit represented by the following formula (B11), a repeating unit represented by the following formula (B12), and a repeating unit represented by the following formula (B13): [C8] (In the formula, R B are each independently a hydrogen atom or a methyl group. Y 1 represents a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, or *-O-Y 11 -, *-C(=O)-O-Y 11 - or *-C(=O)-NH-Y 11 - and Y 11 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. Y 2 is a single bond or **-Y 21 -C(=O)-O-, and Y 21 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. Y 3 represents a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, *-O-Y 31 -, *-C(=O)-O-Y 31 - or *-C(=O)-NH-Y 31 - is. 31represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, or a group having 7 to 20 carbon atoms obtained by combining these, which may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. * represents a bond to a carbon atom in the main chain, and ** represents a bond to an oxygen atom in the formula. Y 4 is a single bond or a hydrocarbylene group having 1 to 30 carbon atoms which may contain a heteroatom. g1 and g2 each independently represent 0 or 1, and Y 4 When is a single bond, g1 and g2 are 0. R 31 ~R 48 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 31 and R 32 may be bonded to each other to form a ring together with the sulfur atom to which they are attached, R 33 and R 34 , R 36 and R 37 , or R 39 and R 40 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. R HF is a hydrogen atom or a trifluoromethyl group. Xa - is a non-nucleophilic counterion.)

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

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

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

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

14. The chemically amplified positive resist composition according to claim 1, further comprising (D) a fluorine atom-containing polymer which contains at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (D1), a repeating unit represented by the following formula (D2), a repeating unit represented by the following formula (D3), and a repeating unit represented by the following formula (D4), and which may further contain at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (D5) and a repeating unit represented by the following formula (D6): [C9] (In the formula, x is an integer of 1 to 3. y is an integer satisfying 0≦y≦5+2z−x. z is 0 or 1. h is an integer of 1 to 3. R C each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R D are each independently a hydrogen atom or a methyl group. R 101 , R 102 , R 104 and R 105 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 103 , R 106 , R 107 and R 108 are each independently a hydrogen atom, a hydrocarbyl group having 1 to 15 carbon atoms, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid labile group; R 103 , R 106 , R 107 and R 108 When is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bonds. R 109is a hydrogen atom or a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a heteroatom-containing group interposed between the carbon-carbon bonds. R 110 is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a heteroatom-containing group between its carbon-carbon bonds. R 111 is a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, and the —CH 2 A part of the - may be substituted with an ester bond or an ether bond. Z 1 is a (h+1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (h+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. Z 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * is a bond to a carbon atom in the main chain. Z 3 is a single bond, -O-, *-C(=O)-O-Z 31 -Z 32 - or -C(=O)-NH-Z 31 -Z 32 - is. 31 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. 32 is a single bond, an ester bond, an ether bond, or a sulfonamide bond. * is a bond to a carbon atom in the main chain.)

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

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

17. 17. The method for forming a resist pattern according to claim 16, wherein the high-energy radiation is extreme ultraviolet radiation or an electron beam.

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

19. 17. The method of forming a resist pattern according to claim 16, wherein the substrate is a transmission type or a reflection type mask blank.

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

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