Chemically amplified negative resist composition and method for forming resist pattern

Abstract

To provide a chemically amplified negative resist composition which improves resolution during pattern formation and can give a resist pattern having good LER and pattern fidelity, and to provide a resist pattern forming method.SOLUTION: The chemically amplified negative resist composition contains: (A) a photoacid generator comprising an onium salt represented by the following formula (A); and (B) a base polymer which contains a polymer containing a repeating unit of a specific structure having a hydroxyphenyl group in a side chain.SELECTED DRAWING: None

Description

[Technical Field]

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

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

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

[0004] In the processing of photomask blanks, some photomask substrates contain surface materials that can easily affect the pattern shape of the chemically amplified resist film, such as chromium oxide and other chromium compound films. To maintain high resolution and post-etching shape, maintaining a rectangular resist film pattern profile regardless of the type of substrate is an important performance requirement. In recent years, the MBMW (multi-beam mask writing) writing process has been used in the processing of mask blanks to achieve miniaturization. In this process, a low-sensitivity resist composition (high-dose range) that is advantageous for roughness is used as the resist composition, and optimization of resist compositions in this high-dose range has also been attracting attention.

[0005] Resist compositions used in photolithography include positive-type resists that dissolve exposed areas to form a pattern, and negative-type resists that leave exposed areas to form a pattern, with the type that is easiest to use being selected depending on the type of resist pattern required. Chemically amplified negative-type resist compositions typically contain a polymer that dissolves in an aqueous alkaline developer, an acid generator that decomposes in the presence of exposure light to generate acid, and a crosslinking agent that uses acid as a catalyst to form crosslinks between the polymers, making the polymer insoluble in the developer (in some cases, the polymer and crosslinking agent are integrated), and typically also contain a quencher to control the diffusion of the acid generated by exposure.

[0006] Examples of alkali-soluble units constituting the polymer that dissolves in the aqueous alkaline developer include units derived from phenols. Many negative resist compositions of this type have been developed, particularly for exposure with KrF excimer laser light. However, these have not been used for ArF excimer laser light because the phenol-derived units do not transmit light when the exposure light has a wavelength of 150 to 220 nm. However, in recent years, negative resist compositions have once again attracted attention as negative resist compositions for use with short-wavelength exposure light such as EB and EUV, which are exposure methods for obtaining finer patterns. For example, Patent Documents 1, 2, and 3 have been reported.

[0007] Furthermore, one type of acid generator is a sulfonium salt that generates a sulfonic acid having an aromatic group containing an iodine atom, as described in Patent Document 4. However, this is intended to have a sensitizing effect on sensitivity in EUV lithography, and its main role is to be used as a quencher for fluorinated alkanesulfonic acids. Therefore, this acid generator has not been investigated as an acid generator, particularly as an acid generator for use in negative resist compositions that use polyhydroxystyrene as a base polymer for the EB writing process in mask blank processing.

[0008] In photolithography, various improvements have been made to control sensitivity and pattern profile by selecting and combining materials used in resist compositions, changing process conditions, etc. One focus of these improvements has been the problem of acid diffusion, which has a significant impact on the resolution of chemically amplified resist compositions.

[0009] Quenchers suppress acid diffusion and are essentially essential components for improving the performance of resist compositions, particularly resolution. Various quenchers have been investigated, with amines and weak acid onium salts typically being used. Patent Document 5, which describes an example of a weak acid onium salt, describes the formation of a favorable resist pattern free of T-top formation, linewidth differences between isolated and dense patterns, and standing waves by adding triphenylsulfonium acetate. Patent Document 6 describes the improvement of sensitivity, resolution, and exposure margin by adding an ammonium sulfonate salt or an ammonium carboxylate salt. Patent Document 7 also describes the improvement of process tolerances, such as exposure margin and depth of focus, in KrF lithography and EB lithography resist compositions containing a photoacid generator that generates a fluorine-containing carboxylic acid, with excellent resolution and improved process tolerances. Furthermore, Patent Document 8 also describes that a resist composition for F2 lithography using an F2 laser, which contains a photoacid generator that generates a fluorine atom-containing carboxylic acid, has excellent line edge roughness (LER) and improves the problem of footing. These compositions are used in KrF lithography, EB lithography, or F2 lithography.

[0010] Patent Document 9 describes a positive-tone photosensitive composition for ArF lithography containing a carboxylic acid onium salt. In this composition, a strong acid (sulfonic acid) generated from a photoacid generator upon exposure is exchanged with a weak acid onium salt to form a weak acid and a strong acid onium salt, thereby replacing a highly acidic strong acid (sulfonic acid) with a weak acid (carboxylic acid), thereby suppressing the acid decomposition reaction of acid-labile groups and reducing (controlling) the acid diffusion distance, and apparently functioning as a quencher.

[0011] However, in recent years, there has been a demand for resist compositions that not only further improve roughness but also have excellent dot pattern shapes in addition to line and space (LS), isoline (IL), and isospace (IS).Patent Document 10 describes a photoacid generator that generates bulky acid and suppresses acid diffusion, and it has been possible to obtain patterns with good resolution and roughness, but it has the drawback of exhibiting corner rounding in dot patterns. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-201532 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-215180 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-249762 [Patent Document 4] Patent No. 6645464 [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. 4116340 [Patent Document 9] Patent No. 4226803 [Patent Document 10] Patent No. 6248882 Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a chemically amplified negative resist composition that improves resolution during pattern formation and is capable of obtaining a resist pattern with excellent LER and pattern fidelity, and a method of forming a resist pattern. [Means for solving the problem]

[0014] As a result of extensive research into achieving the above-mentioned object, the present inventors have found that when an aromatic sulfonic acid-type onium salt is introduced as an acid generator into a resist composition, the acid generated thereby has an optimal structure, which inhibits acid diffusion, thereby enabling a pattern with small LER. Furthermore, in the case of a dot pattern, the appropriate dissolution-inhibiting properties enable a pattern with good rectangularity to be obtained. This finding led to the completion of the present invention.

[0015] That is, the present invention provides the following chemically amplified negative resist composition and method of forming a resist pattern. 1. A chemically amplified negative resist composition comprising: (A) a photoacid generator comprising an onium salt represented by the following formula (A); and (B) a base polymer comprising a polymer containing a repeating unit represented by the following formula (B1): [ka] (In the formula, n1 and n2 are each independently an integer of 0 to 2. When n1=0, n3 is an integer of 1≦n3≦5. When n1=1, n3 is an integer of 1≦n3≦7. When n1=2, n4 is an integer of 0≦n4≦5. When n2=0, n4 is an integer of 0≦n4≦5. 2 When n = 1, it is an integer of 0≦n4≦7, and n 2 When n4 is 2, it is an integer of 0≦n4≦9. L is a single bond, an ether bond, an ester bond, a sulfonate ester bond, an amide bond, a carbonate bond or a carbamate bond. R1 are each independently an iodine atom or a branched or cyclic hydrocarbyl group having 3 to 20 carbon atoms which may contain a heteroatom, and at least one R 1 is bonded to the carbon atom adjacent to the carbon atom to which L is bonded. When n3 is 2 or more, multiple R 1 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 2 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. When n4 is 2 or more, a plurality of R 2 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. W 1 is the carbon atom C of the adjacent aromatic ring. 1 and C 2 and a part of the carbon atoms forming the ring may be substituted with a group containing a hetero atom. W 2 is the carbon atom C of the adjacent aromatic ring. 3 and C 4 and a part of the carbon atoms forming the ring may be substituted with a group containing a hetero atom. 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 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. A 1represents 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. A chemically amplified negative resist composition according to 1, wherein the component (A) is an onium salt represented by the following formula (A1): [ka] (In the formula, n2, n3, n4, W 1 , W 2 , L, R 1 , R 2 and Z + is the same as above.) 3. The chemically amplified negative resist composition of 2, wherein the component (A) is an onium salt represented by the following formula (A2): [ka] (In the formula, n3, n4, W 1 , R 1 , R 2 and Z + is the same as above.) 4.Z + is an onium cation represented by the following formula (cation-1) or (cation-2): [ka] (In the formula, R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. ct1 and R ct2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. 5. The chemically amplified negative resist composition of any one of 1 to 4, wherein the polymer further comprises a repeating unit represented by the following formula (B2): [ka] (In the formula, b1 is 0 or 1. b2 is an integer of 0 to 2. b3 is an integer that satisfies 0≦b3≦5+2(b2)−b4. b4 is an integer of 1 to 3. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 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. R 13 and R 14 are each independently a hydrogen atom, a saturated hydrocarbyl group having 1 to 15 carbon atoms which may be substituted with a hydroxy group or a saturated hydrocarbyloxy group, or an aryl group which may have a substituent, provided that R 13 and R 14 cannot be hydrogen atoms at the same time. 13 and R 14 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. 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-. W 1 is a hydrogen atom, an aliphatic hydrocarbyl group having 1 to 10 carbon atoms, or an aryl group which may have a substituent. 6. The chemically amplified negative resist composition of any one of 1 to 5, 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, c and d each independently represent an integer of 0 to 4. e1 is 0 or 1. e 2 is an integer between 0 and 2. 3 is an integer between 0 and 5. R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 21 and R 22 are 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. R 23 represents a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbyloxyhydrocarbyl group having 2 to 20 carbon atoms, a saturated hydrocarbylthiohydrocarbyl group having 2 to 20 carbon atoms, a halogen atom, a nitro group, 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 3 represents 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—. 7. The chemically amplified negative resist composition of 5, wherein the polymer further comprises at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (B6), a repeating unit represented by the following formula (B7), a repeating unit represented by the following formula (B8), 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 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, *-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. * indicates a bond to a carbon atom in the main chain, and ** indicates 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 hetero atom. f1 and f2 are each independently 0 or 1, but Y 4 When is a single bond, f1 and f2 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, and R 33 and R 34 , R 36and 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. 8. The chemically amplified negative resist composition of 7, wherein the polymer comprises a repeating unit represented by the following formula (B1-1), a repeating unit represented by the following formula (B2-1) or a repeating unit represented by the following formula (B2-2), and a repeating unit represented by the following formula (B7). [ka] (In the formula, a4, b4, R A , R B , Y 2 , R 13 , R 14 , R 33 , R 34 , R 35 and R HF is the same as above.) 9. The chemically amplified negative resist composition of 7 or 8, further comprising a polymer in which the (B) base polymer further comprises a repeating unit represented by formula (B1) and a repeating unit represented by formula (B2), but does not contain any of the repeating units represented by formulas (B6) to (B13). 10. The chemically amplified negative resist composition of any one of 1 to 9, wherein the content of repeating units having an aromatic ring skeleton among all repeating units of the polymer contained in the base polymer is 60 mol % or more. 11. The chemically amplified negative resist composition of any one of 1 to 10, further comprising (C) a crosslinking agent. 12. The chemically amplified negative resist composition of 5, which does not contain a crosslinking agent. 13. The chemically amplified negative resist composition according to any one of 1 to 12, 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. g is an integer of 1 to 3. R C are each independently 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, and R 103 , R 106 , R 107 and R 108 When is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bonds. R 109 is a hydrogen atom or a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a group containing a heteroatom interposed between its carbon-carbon bond. R 110is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a group containing a hetero atom interposed between its carbon-carbon bond. R 111 is a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom has been substituted with a fluorine atom, and some of the -CH2- groups in the saturated hydrocarbyl group may be substituted with an ester bond or an ether bond. Z 1 is a (g+1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (g+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. Z 31 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. 32 is a single bond, an ester bond, an ether bond, or a sulfonamide bond. * is a bond to a carbon atom in the main chain. 14. The negative resist composition according to any one of 1 to 13, further comprising (E) a quencher. 15. The chemically amplified negative resist composition of 14, wherein the content ratio of the acid generator (A) to the quencher (E) is less than 6 by mass. 16. A chemically amplified negative resist composition according to any one of 1 to 15, further comprising (F) an organic solvent. 17. A method for forming a resist pattern, comprising the steps of: forming a resist film on a substrate using the chemically amplified negative resist composition according to any one of 1 to 16; irradiating the resist film with a pattern using high-energy rays; and developing the resist film irradiated with the pattern using an alkaline developer. 18. The method for forming a resist pattern according to 17, wherein the high-energy radiation is EUV or EB. 19. The method for forming a resist pattern according to 17 or 18, 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. 20. The method for forming a resist pattern according to any one of 17 to 19, wherein the substrate is a transmission or reflection mask blank. 21. A transmission or reflection mask blank coated with any one of the chemically amplified negative resist compositions set forth in 1 to 16. [Effects of the Invention]

[0016] The chemically amplified negative resist composition of the present invention can effectively control acid diffusion due to exposure during pattern formation due to the action of the onium salt represented by formula (A), and when a resist film is formed using this composition to form a pattern, it is possible to obtain a pattern with extremely high resolution, high pattern fidelity, and reduced LER. Furthermore, the action of the repeating unit represented by formula (B1) can improve adhesion to the substrate during resist film formation and control solubility in an alkaline developer. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described in detail below. In the following description, some structures represented by chemical formulas may have asymmetric carbon atoms, and enantiomers or diastereomers may exist. In such cases, a single formula will be used to represent all isomers. These isomers may be used alone or as a mixture.

[0018] [Chemically amplified negative resist composition] The chemically amplified negative resist composition of the present invention is characterized by comprising: (A) a photoacid generator consisting of an aromatic sulfonic acid-type onium salt having a ring structure further condensed with an aromatic ring bonded to a sulfo group of an anion and another aromatic ring structure containing a bulky substituent, wherein the degree of rotational freedom between these two aromatic rings is restricted by steric hindrance; and (B) a base polymer containing a predetermined polymer.

[0019] [(A) Acid generator] The onium salt serving as the acid generator of component (A) is represented by the following formula (A). [ka]

[0020] In formula (A), n1 and n2 each independently represent an integer of 0 to 2. When n1=0, it represents a benzene ring, when n1=1 it represents a naphthalene ring, and when n1= 2 represents an anthracene ring, but from the viewpoint of solvent solubility, it is preferably a benzene ring where n1 = 0. Also, from the viewpoint of solvent solubility, n2 is preferably 0.

[0021] In formula (A), n3 is an integer of 1≦n3≦5 when n1=0, an integer of 1≦n3≦7 when n1=1, and an integer of 1≦n3≦9 when n1=2. n4 is an integer of 0≦n4≦5 when n2=0, and n 2 When n = 1, it is an integer of 0≦n4≦7, and n 2 When n4 is 2, it is an integer of 0≦n4≦9.

[0022] In formula (A), L is a single bond, an ether bond, an ester bond, a sulfonate ester bond, an amide bond, a carbonate bond, or a carbamate bond. Of these, an ether bond, an ester bond, or a sulfonate ester bond is preferred, and a sulfonate ester bond is more preferred.

[0023] In formula (A), R 1 are each independently an iodine atom or a branched or cyclic hydrocarbyl group having 3 to 20 carbon atoms which may contain a heteroatom, and at least one R 1is bonded to the carbon atom adjacent to the carbon atom to which L is bonded. Specific examples of the hydrocarbyl group include an isopropyl group, a sec-butyl group, a tert-butyl group, a tert-pentyl group, a cyclopentyl group, a cyclohexyl group, a 2-ethylhexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, an oxanorbornyl group, a tricyclo[5.2.1.0] group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclohexylbutyl group, a norbornyl group, an oxanorbornyl group, a tricyclo[5.2.1.0] group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclohexylbutyl group, a norbornyl group, an oxanorbornyl group, a tricyclo[5.2.1.0] group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclohexylbutyl group, a norbornyl group, a cyclohexylmethyl group, a cyclohex ... 2,6 Examples of suitable hydrocarbyl groups include, but are not limited to, aliphatic cyclic hydrocarbon groups having 3 to 20 carbon atoms, such as a decyl group or an adamantyl group; aryl groups, such as a phenyl group, a naphthyl group, or an anthracenyl group; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms in the hydrocarbyl group may be substituted with a group containing a heteroatom, such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- groups in the hydrocarbyl group may be substituted with a group containing a heteroatom, such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in the hydrocarbyl group containing a hydroxy group, a cyano group, a halogen 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. Examples of suitable halogen atoms include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, with a fluorine atom or an iodine atom being preferred.

[0024] Also, when n3 is 2 or more, multiple R 1 However, they may be bonded to each other to form a ring together with the carbon atoms to which they are bonded. The ring is preferably a 5- to 8-membered ring.

[0025] In formula (A), R 2is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0]. 2,6

[0033] Examples of the hydrocarbyl group include cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as a decyl group, an adamantyl group, and an adamantylmethyl group; and aryl groups having 6 to 20 carbon atoms, such as a phenyl group, a naphthyl group, and an anthracenyl group. Some or all of the hydrogen atoms in 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. Alternatively, some of the -CH- groups in the hydrocarbyl group may be substituted with a group containing a heteroatom, such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, the hydrocarbyl group may contain a hydroxy group, a cyano group, a halogen 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. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, with a fluorine atom or an iodine atom being preferred.

[0026] Also, when n4 is 2 or more, multiple R 2 However, they may be bonded to each other to form a ring together with the carbon atoms to which they are bonded. The ring is preferably a 5- to 8-membered ring.

[0027] In formula (A), W 1 is the carbon atom C of the adjacent aromatic ring. 1 and C 2and a part of the carbon atoms forming the ring may be substituted with a group containing a hetero atom. The ring may be monocyclic or polycyclic. 2 is the carbon atom C of the adjacent aromatic ring. 3 and C 4 and a part of the carbon atoms forming the ring may be substituted with a group containing a hetero atom. The ring may be monocyclic or polycyclic.

[0028] W in formula (A) 1 and W 2 Examples of the structure in which an aromatic ring is fused with an adjacent aromatic ring include, but are not limited to, those shown below: In the following formula, the dashed line represents a bond to L. [ka]

[0029] R in formula (A) 1 Examples of the structure in which an aromatic ring is bonded to an aromatic ring include, but are not limited to, those shown below: In the following formula, the dashed line represents the bond to L. [ka]

[0030] [ka]

[0031] [ka]

[0032] [ka]

[0033] [ka]

[0034] [ka]

[0035] The onium salt represented by formula (A) is preferably one represented by the following formula (A1). [ka] (In the formula, n2, n3, n4, W 1 , W 2 , L, R 1 , R 2 and Z + is the same as above.)

[0036] The onium salt represented by formula (A1) is preferably one represented by the following formula (A2). [ka] (In the formula, n3, n4, W 1 , R 1 , R 2 and Z + is the same as above.)

[0037] Particularly preferred examples of the anion of the onium salt represented by formula (A) include, but are not limited to, those shown below. [ka]

[0038] [ka]

[0039] [ka]

[0040] [ka]

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[0061] In formula (A), Z +is an onium cation. The onium cation is preferably a sulfonium cation represented by the following formula (cation-1) or an iodonium cation represented by the following formula (cation-2). [ka]

[0062] In formulas (cation-1) and (cation-2), R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom.

[0063] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0064] 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; saturated cyclic hydrocarbyl groups having 3 to 30 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups having 2 to 30 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl; unsaturated cyclic hydrocarbyl groups having 3 to 30 carbon atoms, such as cyclohexenyl; aryl groups having 6 to 30 carbon atoms, such as phenyl, naphthyl, and thienyl; aralkyl groups having 7 to 30 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl; and groups obtained by combining these, with aryl groups being preferred. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a cyano group, a 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.

[0065] Also, R ct1 and R ct2 However, they may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, examples of the sulfonium cation represented by formula (cation-1) include those represented by the following formula: [ka] (In the formula, the dashed line indicates R ct3 )

[0066] Examples of the sulfonium cation represented by formula (cation-1) include, but are not limited to, those shown below. [ka]

[0067] [ka]

[0068] [ka]

[0069] [ka]

[0070] [ka]

[0071] [ka]

[0072] [ka]

[0073] [ka]

[0074] [ka]

[0075] [ka]

[0076]

change

[0077]

change

[0078]

change

[0079]

change

[0080]

change

[0081]

change

[0082]

change

[0083]

change

[0084]

change

[0085]

change

[0086]

change

[0087] [ka]

[0088] [ka]

[0089] [ka]

[0090] [ka]

[0091] [ka]

[0092] Examples of the iodonium cation represented by formula (cation-2) include, but are not limited to, those shown below. [ka]

[0093] [ka]

[0094] Specific examples of the onium salt represented by formula (A) include any combination of the above-mentioned anions and cations.

[0095] The onium salt represented by formula (A) can be synthesized by a known method. As an example, a method for producing an onium salt represented by the following formula (PAG-1-ex), in which L in formula (A) is a sulfonate ester bond, will be described. [ka] (In the formula, n1~n4, W 1 , W 2 , R 1 , R 2 and Z + is the same as above.)

[0096] The reaction is a sulfonate esterification reaction between an aromatic sulfonic acid chloride (S-1) and a hydroxyaromatic sulfonate (S-2) to obtain an aromatic sulfonic acid onium salt (PAG-1-ex). The reaction can be carried out according to a conventional method, and is preferably carried out by sequentially or simultaneously adding the aromatic sulfonic acid chloride (S-1), the hydroxyaromatic sulfonate (S-2), and a base to a solvent, and cooling or heating as necessary. It is desirable to monitor the progress of the reaction by TLC in terms of yield. The onium salt (PAG-1-ex) can be obtained from the resulting reaction solution by conventional aqueous work-up. If necessary, the product can be purified by conventional methods such as chromatography or recrystallization.

[0097] Examples of solvents that can be used in the reaction include water, ethers such as tetrahydrofuran (THF), diethyl ether, diisopropyl ether, di-n-butyl ether, and 1,4-dioxane, hydrocarbons such as n-hexane, n-heptane, benzene, toluene, and xylene, aprotic polar solvents such as acetonitrile, dimethyl sulfoxide (DMSO), and N,N-dimethylformamide (DMF), and chlorine-based organic solvents such as methylene chloride, chloroform, and carbon tetrachloride. These solvents may be appropriately selected depending on the reaction conditions, and may be used alone or in combination of two or more.

[0098] Examples of bases that can be used in the reaction include ammonia; amines such as triethylamine, pyridine, lutidine, collidine, and N,N-dimethylaniline; hydroxides such as sodium hydroxide, potassium hydroxide, and tetramethylammonium hydroxide; carbonates such as potassium carbonate and sodium hydrogen carbonate, etc. These bases may be used alone or in combination of two or more.

[0099] The onium salt represented by formula (A) is an onium salt of sulfonic acid that is not substituted with fluorine atoms, and thus can generate an acid of appropriate strength upon irradiation with high-energy radiation. Furthermore, it has a structural feature in that it has a ring structure further condensed with the aromatic ring bonded to the sulfo group of the anion and another aromatic ring structure containing a bulky substituent. The steric hindrance between these two aromatic rings reduces the degree of rotational freedom of the bond connecting the aromatic rings, thereby limiting excessive acid diffusion of the generated acid. Furthermore, the onium salt represented by formula (A) has sufficient liposolubility, making it easy to manufacture and handle. These effects enable the generation of an acid in a resist film with excessive acid strength and controlled acid diffusion, thereby producing patterns with good resolution and small LER even in fine patterns. Even in negative resist compositions using alkaline developers, the appropriate dissolution inhibition properties enable the production of patterns with good rectangularity.

[0100] In the chemically amplified negative resist composition of the present invention, the content of the onium salt represented by formula (A) is preferably 0.001 to 50 parts by mass, and more preferably 0.01 to 40 parts by mass, relative to 80 parts by mass of the base polymer (B) described below, from the viewpoints of sensitivity and acid diffusion suppression effect.

[0101] The chemically amplified negative resist composition of the present invention may further contain an acid generator other than the onium salt represented by formula (A) (hereinafter also referred to as "other acid generator") for the purpose of correcting the shape of a pattern, etc. As the other acid generator, any known acid generator for use in resist compositions can be used. From the viewpoints of sensitivity and acid diffusion suppression effect, the content of the other acid generator is preferably 0 to 40 parts by mass, and more preferably 0 to 30 parts by mass, relative to 80 parts by mass of the (B) base polymer described below. The other acid generators may be used alone, or two or more types may be used in combination.

[0102] [(B) Base polymer] The base polymer of component (B) contains a polymer (hereinafter also referred to as polymer B) containing a repeating unit represented by the following formula (B1) (hereinafter also referred to as repeating unit B1). Repeating unit B1 is a repeating unit that imparts etching resistance, adhesion to substrates, and solubility in alkaline developers. [ka]

[0103] 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.

[0104] In formula (B1), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0105] In formula (B1), R 11is 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 moiety of the saturated hydrocarbyloxy group and saturated hydrocarbylcarbonyloxy group may be linear, branched, or cyclic. Specific examples include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, butyl, pentyl, hexyl, and structural isomers thereof; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl; and groups obtained by combining these. When the number of carbon atoms is equal to or less than the upper limit, the solubility in an alkaline developer is good. When a3 is 2 or more, each R 11 may be the same as or different from each other.

[0106] In formula (B1), A 1is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a portion of the -CH2- in the saturated hydrocarbylene group may be substituted with -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, and 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, the ether bond may be located anywhere 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 bonding 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 relative to the etheric oxygen atom. Note that 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.

[0107] 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 When 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.)

[0108] a1 is 1 (i.e., -C(=O)-OA as a linker) 1In the case where R A is the same as above. [ka]

[0109] The repeating unit B1 may be used alone or in combination of two or more.

[0110] Polymer B may contain a repeating unit represented by the following formula (B2) (hereinafter also referred to as repeating unit B2) (hereinafter, polymer B that further contains repeating unit B2 will also be referred to as polymer B'). [ka]

[0111] When the repeating unit B2 is irradiated with high-energy rays, it converts to -OW by the action of the acid generated from the acid generator. 1 This repeating unit undergoes an elimination reaction, which makes the compound insoluble in alkaline developers and induces crosslinking reactions between polymers. The effect of repeating unit B2 is to promote the negative conversion reaction more efficiently, thereby improving resolution.

[0112] In formula (B2), b1 is 0 or 1. b2 is an integer of 0 to 2. b3 is an integer that satisfies 0≦b3≦5+2(b2)−b4. b4 is an integer of 1 to 3.

[0113] In formula (B2), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0114] In formula (B2), R 12is 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 moiety of the saturated hydrocarbyloxy group and saturated hydrocarbylcarbonyloxy group may be linear, branched, or cyclic, and specific examples thereof include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, and structural isomers thereof; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl; and groups obtained by combining these. When b3 is 2 or more, each R 12 may be the same as or different from each other.

[0115] In formula (B2), R 13 and R 14 are each independently a hydrogen atom, a saturated hydrocarbyl group having 1 to 15 carbon atoms which may be substituted with a hydroxy group or a saturated hydrocarbyloxy group, or an aryl group which may have a substituent, provided that R 13 and R 14 cannot be hydrogen atoms at the same time. 13 and R 14 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. 13 and R 14 Preferred examples of the alkyl group include alkyl groups such as methyl, ethyl, propyl, and butyl groups, and structural isomers thereof, as well as alkyl groups in which some of the hydrogen atoms have been substituted with hydroxy groups or saturated hydrocarbyloxy groups.

[0116] In formula (B2), A 2is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and -CH2- of the saturated hydrocarbylene group may be replaced with -O-. The saturated hydrocarbylene group may be linear, branched, or cyclic, and specific examples thereof include alkanediyl groups such as methylene, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, and hexane-1,6-diyl, and structural isomers thereof; cyclic saturated hydrocarbylene groups 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) is 1, it may be located anywhere 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 bonding to the main chain is an ether oxygen atom, and the second ether bond may be inserted anywhere except between the carbon atom at the α-position and the carbon atom at the β-position relative to the ether oxygen atom.

[0117] In formula (B2), W 1 is a hydrogen atom, an aliphatic hydrocarbyl group having 1 to 10 carbon atoms, or an aryl group which may have a substituent. The aliphatic hydrocarbyl group may be linear, branched, or cyclic, and specific examples thereof include alkyl groups such as methyl, ethyl, propyl, and isopropyl; and cyclic aliphatic hydrocarbyl groups such as cyclopentyl, cyclohexyl, and adamantyl. Examples of the aryl group include a phenyl group. In addition, -CH2- in the aliphatic hydrocarbyl group may be substituted with -O-, -C(=O)-, -OC(=O)-, or -C(=O)-O-. In addition, -CH2- in the hydrocarbyl group may be bonded to the oxygen atom in formula (B2). Examples of such substituted groups include a methylcarbonyl group.

[0118] The repeating unit B2 is preferably one represented by the following formula (B2-1) or (B2-2). [ka] (In the formula, b4, R A , R 13 and R 14 is the same as above.)

[0119] Preferred examples of the repeating unit B2 include, but are not limited to, the following: A is the same as above, Me is a methyl group, and Ac is an acetyl group. [ka]

[0120] [ka]

[0121] [ka]

[0122] [ka]

[0123] [ka]

[0124] The repeating unit B2 may be used alone or in combination of two or more.

[0125] For the purpose of improving etching resistance, polymers B and B' may contain at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (B3) (hereinafter also referred to as repeating unit B3), a repeating unit represented by the following formula (B4) (hereinafter also referred to as repeating unit B4), and a repeating unit represented by the following formula (B5) (hereinafter also referred to as repeating unit B5). [ka]

[0126] In the formulae (B3) and (B4), c and d each independently represent an integer of 0 to 4.

[0127] In formulas (B3) and (B4), R 21 and R 22 are 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 c is 2 or more, each R 21 may be the same or different. When d is 2 or more, each R 22 may be the same as or different from each other.

[0128] In formula (B5), e1 is 0 or 1. e2 is an integer of 0 to 2, and when e2 is 0, it represents a benzene skeleton, when e2 is 1, it represents a naphthalene skeleton, and when e2 is 2, it represents an anthracene skeleton. e3 is an integer of 0 to 5. When e2 is 0, e3 is preferably an integer of 0 to 3, and when e2 is 1 or 2, e3 is preferably an integer of 0 to 4.

[0129] In formula (B5), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0130] 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 e3 is 2 or more, each R 23 may be the same as or different from each other.

[0131] R 23 Preferred examples of the alkyl group include halogen atoms such as chlorine, bromine, and iodine; saturated hydrocarbyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopentyl, and cyclohexyl groups, and structural isomers thereof; and saturated hydrocarbyloxy groups such as methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, cyclopentyloxy, and cyclohexyloxy groups, and structural isomers of the hydrocarbon moiety thereof. Of these, methoxy and ethoxy groups are particularly useful.

[0132] Furthermore, saturated hydrocarbyl carbonyloxy groups can be easily introduced by chemical modification even after polymer polymerization and can be used to finely adjust the solubility of the base polymer in alkaline developers. Examples of the saturated hydrocarbyl carbonyloxy group include methyl carbonyloxy groups, ethyl carbonyloxy groups, propyl carbonyloxy groups, butyl carbonyloxy groups, pentyl carbonyloxy groups, hexyl carbonyloxy groups, cyclopentyl carbonyloxy groups, cyclohexyl carbonyloxy groups, benzoyloxy groups, and structural isomers of the hydrocarbon moieties thereof. If the number of carbon atoms is 20 or less, the effect of controlling and adjusting (mainly the effect of reducing) the solubility of the base polymer in alkaline developers can be made appropriate, and the occurrence of scum (development defects) can be suppressed.

[0133] Among the above-mentioned preferred substituents, examples of substituents that 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.

[0134] In formula (B5), A 3 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a portion of the -CH2- in the saturated hydrocarbylene group may be substituted with -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, and hexane-1,6-diyl groups, and structural isomers thereof; cyclic saturated hydrocarbylene groups having 3 to 10 carbon atoms, such as cyclopropanediyl, cyclobutanediyl, cyclopentanediyl, and cyclohexanediyl groups; and groups obtained by combining these. When the saturated hydrocarbylene group contains an ether bond, e When 1 is 1, it may be located anywhere except between the carbon atom at the α-position and the carbon atom at the β-position relative to the ester oxygen atom. eWhen 1 is 0, the atom bonding 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 relative to the etheric oxygen atom. Note that 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.

[0135] e1 is 0 and A 3 is a single bond, that is, the aromatic ring is directly bonded to the main chain of the polymer (i.e., the linker (-C(=O)-OA 3 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.

[0136] Also, when e1 is 1 (i.e., -C(=O)-OA as a linker 3 In the case where R A is the same as above. [ka]

[0137] [ka]

[0138] 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 the effect of improving the etching resistance of the aromatic ring as well as the resistance to EB irradiation during pattern inspection.

[0139] The repeating units B3 to B5 may be used alone or in combination of two or more.

[0140] Polymer B' may further contain at least one selected from the group consisting of a repeating unit represented by formula (B6) (hereinafter also referred to as repeating unit B6), a repeating unit represented by formula (B7) (hereinafter also referred to as repeating unit B7), a repeating unit represented by formula (B8) (hereinafter also referred to as repeating unit B8), a repeating unit represented by formula (B9) (hereinafter also referred to as repeating unit B9), a repeating unit represented by formula (B10) (hereinafter also referred to as repeating unit B10), a repeating unit represented by formula (B11) (hereinafter also referred to as repeating unit B11), a repeating unit represented by formula (B12) (hereinafter also referred to as repeating unit B12), and a repeating unit represented by formula (B13) (hereinafter also referred to as repeating unit B13). In this case, acid diffusion can be effectively suppressed, resolution can be improved, and a pattern with reduced LER can be obtained. [ka]

[0141] In formulas (B6) to (B13), R B are each 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 hydroxy 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. 3represents 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 hetero atom. f1 and f2 each independently represent 0 or 1, but Y 4 When is a single bond, f1 and f2 are 0.

[0142] In formulas (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.

[0143] In formulas (B7) and (B11), Y 2 Ga-Y 21 -C(=O)-O-, Y 21 Examples of the hydrocarbylene group represented by the formula (I) which may contain a heteroatom include, but are not limited to, those shown below. [ka] (In the formula, the dashed lines represent bonds.)

[0144] In formulas (B7) and (B11), R HF is a hydrogen atom or a trifluoromethyl group. HFSpecific examples of when R is a hydrogen atom include those described in JP-A-2010-116550. HF Specific examples of repeating units B8 and B12 in which is a trifluoromethyl group include those described in JP-A-2010-77404. Examples of repeating units B8 and B12 include those described in JP-A-2012-246265 and JP-A-2012-246426.

[0145] Preferred examples of the anion of the monomer that provides the repeating unit B9 or B13 include, but are not limited to, the following. [ka]

[0146] [ka]

[0147] 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 those of formula (cation-1): and (cation- 2 ) in the explanation of R ct1 ~R ct5Examples include the same halogen atoms and hydrocarbyl groups as those exemplified above. Some or all of the hydrogen atoms in the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- groups in the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, so that 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 acid anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0148] 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, and 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. The ring formed in this case is the same as that of R in the explanation of formula (cation-1). ct1 and R ct2 are bonded to each other to form a ring together with the sulfur atom to which they are bonded, the same as those exemplified above.

[0149] Specific examples of the sulfonium cations in 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 in the repeating units B11 to B13 include the same as those exemplified as the iodonium cations represented by formula (cation-2).

[0150] The repeating units B6 to B13 are units that generate acid upon irradiation with high-energy rays. It is believed that the inclusion of these units in the polymer appropriately suppresses acid diffusion, resulting in a pattern with reduced LER. Furthermore, the inclusion of these units in the polymer suppresses the phenomenon in which acid volatilizes from the exposed areas and reattaches to the unexposed areas during baking in a vacuum, which is believed to be effective in reducing LER and reducing defects due to the suppression of unwanted negative reactions in the unexposed areas.

[0151] The repeating units B6 to B13 may be used alone or in combination of two or more.

[0152] Polymers B and B' may contain a lactone structure, a (meth)acrylic acid ester unit having an adhesive group such as a hydroxy group other than a phenolic hydroxy group, or other repeating units in order to finely adjust the properties of the resist film.

[0153] 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 substrates or units that adjust solubility. [ka]

[0154] In formulas (B14) to (B16), R A are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 51 is —O— or a methylene group. 52 is a hydrogen atom or a hydroxy group. 53 is a saturated hydrocarbyl group having 1 to 4 carbon atoms. k is an integer of 0 to 3.

[0155] In polymer B, the content of repeating unit B1 is preferably 30 to 95 mol %, more preferably 50 to 85 mol %, to achieve high contrast between the area negatively irradiated by high-energy radiation and the area not irradiated (non-negative area) for the purpose of achieving high resolution. The content of repeating unit B2 is preferably 5 to 70 mol %, more preferably 10 to 60 mol %, to achieve the effect of accelerating the negative reaction. The content of repeating units B3 to B5 is preferably 0 to 30 mol %, more preferably 3 to 20 mol %, to achieve the effect of improving etching resistance. Other repeating units may be contained in an amount of 0 to 30 mol %, preferably 0 to 20 mol %.

[0156] When polymer B' does not contain repeating units B6 to B13, the content of repeating unit B1 in polymer B' is preferably 25 to 95 mol %, more preferably 40 to 85 mol %. The content of repeating units B3 to B5 is preferably 0 to 30 mol %, more preferably 3 to 20 mol %. Repeating unit B 2 The content of is preferably 5 to 70 mol %, more preferably 10 to 60 mol %. Other repeating units may be contained in an amount of 0 to 30 mol %, preferably 0 to 20 mol %.

[0157] When polymer B' contains repeating units B6 to B13, the content of repeating unit B1 in polymer B' is preferably 25 to 94.5 mol %, more preferably 36 to 85 mol %. The content of repeating units B3 to B5 is preferably 0 to 30 mol %, more preferably 3 to 20 mol %. Repeating units B 2 The content of repeating units B1 to B5 is preferably 5 to 70 mol %, more preferably 10 to 60 mol %. The total content of repeating units B1 to B5 is preferably 60 to 99.5 mol %. The content of repeating units B6 to B13 is preferably 0.5 to 20 mol %, more preferably 1 to 10 mol %. Other repeating units may be contained in an amount of 0 to 30 mol %, preferably 0 to 20 mol %.

[0158] Of all the repeating units constituting the polymer, the repeating units B1 to B5 preferably account for 60 mol % or more, more preferably 70 mol % or more, and even more preferably 80 mol % or more, which ensures that the properties required for the chemically amplified negative resist composition of the present invention are obtained.

[0159] In this case, polymer B' preferably contains a repeating unit represented by the following formula (B1-1), a repeating unit represented by the following formula (B2-1) or (B2-2), and a repeating unit represented by the following formula (B7). [ka] (In the formula, a4, b4, R A , R B , Y 2 , R 13 , R 14 , R 33 , R 34 , R 35 and R HF is the same as above.)

[0160] When polymer B' is used as the (B) base polymer, one that does not contain repeating units B6 to B13 may be used in combination with one that does contain repeating units B6 to B13. In this case, the content of the polymer that does not contain repeating units B6 to B13 in the chemically amplified negative resist composition of the present invention is preferably 2 to 5000 parts by mass, and more preferably 10 to 1000 parts by mass, per 100 parts by mass of the polymer that contains repeating units B6 to B13.

[0161] When a chemically amplified negative resist composition is used to fabricate a mask, the coating film thickness in the most advanced generation is 150 nm or less, preferably 100 nm or less. The dissolution rate of the base polymer constituting the chemically amplified negative resist composition in an alkaline developer (e.g., a 2.38% by mass tetramethylammonium hydroxide (TMAH) aqueous solution) is preferably 80 nm / sec or less, more preferably 50 nm / sec or less, in order to form a fine pattern, which is generally achieved through a strong development process to minimize defects caused by resist residues. Furthermore, when using the chemically amplified negative resist composition of the present invention in an EUV exposure process, for example, when fabricating an LSI chip from a wafer, the coating film thickness is often 100 nm or less because it is necessary to pattern fine lines of 50 nm or less. Because the film is thin, pattern degradation due to development is anticipated. Therefore, the dissolution rate of the polymer used is preferably 80 nm / sec or less, more preferably 50 nm / sec or less.

[0162] The polymer can be synthesized by copolymerizing monomers protected with protecting groups as needed using a known method, followed by deprotection as needed. The copolymerization reaction is not particularly limited, but is preferably radical polymerization or anionic polymerization. For these methods, reference can be made to WO 2006 / 121096, JP 2008-102383 A, JP 2008-304590 A, and JP 2004-115630 A.

[0163] The polymer preferably has a weight-average molecular weight (Mw) of 1,000 to 50,000, more preferably 2,000 to 20,000. If Mw is 1,000 or more, there is no risk of the conventionally known phenomenon of pattern heads becoming rounded, resulting in reduced resolution and LER degradation. On the other hand, if Mw is 50,000 or less, there is no risk of LER increasing, particularly when forming a pattern with a line width of 100 nm or less. In the present invention, Mw is a value measured in terms of polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran (THF) or dimethylformamide (DMF) as a solvent.

[0164] The polymer preferably has a narrow molecular weight distribution (Mw / Mn) of 1.0 to 2.0, particularly 1.0 to 1.8, such that foreign matter does not appear on the pattern after development and the pattern shape does not deteriorate.

[0165] [(C) Crosslinking agent] When the (B) base polymer does not contain polymer B', the chemically amplified negative resist composition of the present invention preferably contains a crosslinking agent as component (C). On the other hand, when the (B) base polymer contains polymer B', it does not necessarily need to contain a crosslinking agent.

[0166] Specific examples of crosslinking agents that can be used in the present invention include epoxy compounds, melamine compounds, guanamine compounds, glycoluril compounds or urea compounds, isocyanate compounds, azide compounds, and compounds containing double bonds, such as alkenyloxy groups, all of which are substituted with at least one group selected from a methylol group, an alkoxymethyl group, and an acyloxymethyl group. These may be used as additives or may be introduced as pendant groups into polymer side chains. Compounds containing hydroxy groups may also be used as crosslinking agents.

[0167] Examples of the epoxy compound include tris(2,3-epoxypropyl)isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, and triethylolethane triglycidyl ether.

[0168] Examples of the melamine compound include compounds in which 1 to 6 methylol groups are methoxymethylated, such as hexamethylol melamine, hexamethoxymethyl melamine, and hexamethylol melamine, and mixtures thereof; and compounds in which 1 to 6 methylol groups are acyloxymethylated, such as hexamethoxyethyl melamine, hexaacyloxymethyl melamine, and hexamethylol melamine, and mixtures thereof.

[0169] Examples of the guanamine compound include compounds in which 1 to 4 methylol groups are methoxymethylated, such as tetramethylolguanamine, tetramethoxymethylguanamine, and tetramethylolguanamine, and mixtures thereof; and compounds in which 1 to 4 methylol groups are acyloxymethylated, such as tetramethoxyethylguanamine, tetraacyloxyguanamine, and tetramethylolguanamine, and mixtures thereof.

[0170] Examples of the glycoluril compound include compounds in which 1 to 4 methylol groups are methoxymethylated, such as tetramethylol glycoluril, tetramethoxyglycoluril, tetramethoxymethyl glycoluril, and tetramethylol glycoluril, or mixtures thereof; and compounds in which 1 to 4 methylol groups are acyloxymethylated in tetramethylol glycoluril, or mixtures thereof.

[0171] Examples of the urea compound include tetramethylol urea, tetramethoxymethyl urea, compounds in which 1 to 4 methylol groups are methoxymethylated, such as tetramethylol urea, or mixtures thereof, and tetramethoxyethyl urea.

[0172] Examples of the isocyanate compound include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and cyclohexane diisocyanate.

[0173] Examples of the azide compound include 1,1'-biphenyl-4,4'-bisazide, 4,4'-methylidenebisazide, and 4,4'-oxybisazide.

[0174] Examples of the compound containing an alkenyloxy group include ethylene glycol divinyl ether, triethylene glycol divinyl ether, 1,2-propanediol divinyl ether, 1,4-butanediol divinyl ether, tetramethylene glycol divinyl ether, neopentyl glycol divinyl ether, trimethylolpropane trivinyl ether, hexanediol divinyl ether, 1,4-cyclohexanediol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, sorbitol tetravinyl ether, sorbitol pentavinyl ether, and trimethylolpropane trivinyl ether.

[0175] In the chemically amplified negative resist composition of the present invention, the content of the (C) crosslinking agent is preferably 0.1 to 50 parts by mass, more preferably 1 to 30 parts by mass, relative to 80 parts by mass of the (B) base polymer. Within this range, there is little risk of patterns being connected together and resolution decreasing. The (C) crosslinking agents may be used alone or in combination of two or more.

[0176] [(D) Fluorine atom-containing polymer] The chemically amplified negative resist composition of the present invention, for the purposes of achieving high contrast, suppressing acid chemical flare upon high-energy radiation irradiation, shielding acid from mixing from the antistatic coating during the process of applying an antistatic coating material onto the resist film, and suppressing unexpected and unnecessary pattern degradation, may comprise, as component (D), a fluorine-containing polymer that includes at least one repeating unit 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 that may further include at least one repeating unit 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 in preventing insoluble matter from re-adhering to the substrate during the development process, thereby preventing development defects. [ka]

[0177] In the formulas (D1) to (D6), x is an integer of 1 to 3. y is an integer that satisfies 0≦y≦5+2z−x. z is 0 or 1. g is an integer of 1 to 3. R C are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. D are each independently a hydrogen atom or a methyl group. 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. 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, and 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 bond. 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 its carbon-carbon bond. 110 R is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, which may have a heteroatom-containing group interposed between its carbon-carbon bond. 111 is a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom has been substituted with a fluorine atom, and some of the -CH2- groups in the saturated hydrocarbyl group may be substituted with an ester bond or an ether bond. 1 is a (g+1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (g+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. Z 31 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. 32 is a single bond, an ester bond, an ether bond, or a sulfonamide bond. * is a bond to a carbon atom of the main chain.

[0178] 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 methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl; and cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, and norbornyl. Of these, saturated hydrocarbyl groups having 1 to 6 carbon atoms are preferred.

[0179] 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, with an alkyl group having 1 to 15 carbon atoms being preferred. Examples of the alkyl group include those mentioned above, as well as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, and n-pentadecyl. Examples of the fluorinated hydrocarbyl group include groups in which some or all of the hydrogen atoms bonded to carbon atoms in the hydrocarbyl group mentioned above have been substituted with fluorine atoms.

[0180] In formula (D4), Z 1 Examples of the (g+1)-valent hydrocarbon group having 1 to 20 carbon atoms and represented by the formula (I) include a group in which g hydrogen atoms have been further removed from an alkyl group having 1 to 20 carbon atoms or a cyclic saturated hydrocarbyl group having 3 to 20 carbon atoms. 1Examples of the (g+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms and represented by the formula (I) include groups in which at least one hydrogen atom of the aforementioned (g+1)-valent hydrocarbon group has been substituted with a fluorine atom.

[0181] Specific examples of the repeating units D1 to D4 include, but are not limited to, the following: C is the same as above. [ka]

[0182] [ka]

[0183] [ka]

[0184] In formula (D5), R 109 and R 110 Examples of the hydrocarbyl group having 1 to 5 carbon atoms represented by the formula (I) include an alkyl group, an alkenyl group, and an alkynyl group, with an alkyl group being preferred. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and an n-pentyl group. In addition, a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom may be present between the carbon-carbon bonds of the hydrocarbyl group.

[0185] In formula (D5), -OR 109 is preferably a hydrophilic group. In this case, R 109 As the alkyl group, a hydrogen atom, an alkyl group having 1 to 5 carbon atoms and an oxygen atom intervening between the carbon-carbon bonds, and the like are preferred.

[0186] 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 acid diffusion, resulting in good stability of the resist film over time and preventing degradation of resolution and pattern shape.

[0187] Examples of the repeating unit D5 include, but are not limited to, those shown below. D is the same as above. [ka]

[0188] [ka]

[0189] 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.

[0190] In formula (D6), R 111 The saturated hydrocarbyl group having 1 to 20 carbon atoms, represented by the formula (I) above, in which at least one hydrogen atom has been substituted with a fluorine atom, may be linear, branched, or cyclic, and specific examples thereof include an alkyl group having 1 to 20 carbon atoms or a cyclic saturated hydrocarbyl group having 3 to 20 carbon atoms in which at least one hydrogen atom has been substituted with a fluorine atom.

[0191] Examples of the repeating unit D6 include, but are not limited to, those shown below. D is the same as above. [ka]

[0192] [ka]

[0193] [ka]

[0194] [ka]

[0195] The content of repeating units D1 to D4 is preferably 15 to 95 mol %, more preferably 20 to 85 mol %, of all repeating units in the fluorine atom-containing polymer. The content of repeating units D5 and / or D6 is preferably 5 to 85 mol %, more preferably 15 to 80 mol %, of all repeating units in the fluorine atom-containing polymer. The repeating units D1 to D6 may be used alone or in combination of two or more.

[0196] The fluorine atom-containing polymer may contain repeating units other than the repeating units described above. Examples of such repeating units include those described in paragraphs

[0046] to

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

[0197] The fluorine atom-containing polymer can be synthesized by copolymerizing each monomer, optionally protected with a protecting group, according to a known method, followed by a deprotection reaction as needed. The copolymerization reaction is not particularly limited, but is preferably radical polymerization or anionic polymerization. For these methods, reference can be made to JP 2004-115630 A.

[0198] 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 a deterioration in resolution and a loss of stability over time. If the Mw is too large, the solubility in the solvent decreases, which may cause coating defects. Furthermore, the fluorine atom-containing polymer preferably has an Mw / Mn ratio of 1.0 to 2.2, more preferably 1.0 to 1.7.

[0199] When the chemically amplified negative resist composition of the present invention contains (D) a fluorine atom-containing polymer, 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 (B) base polymer. The (D) fluorine atom-containing polymer may be used alone, or two or more types may be used in combination.

[0200] [(E) Quencher] The chemically amplified negative resist composition of the present invention preferably contains a quencher as component (E). In this invention, a quencher is a material that traps the acid generated by the photoacid generator in the chemically amplified resist composition, thereby preventing it from diffusing to unexposed areas and allowing the desired pattern to be formed.

[0201] Examples of the quencher include conventional basic compounds. Examples of conventional basic compounds include primary, secondary, and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxy group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxy group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amides, imides, and carbamates. In particular, the primary, secondary, and tertiary amine compounds described in paragraphs

[0146] to

[0164] of JP 2008-111103 A are preferred, including amine compounds having a hydroxy group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonate ester bond, and compounds having a carbamate group described in JP 3790649 A. Preferred examples include tris[2-(methoxymethoxy)ethyl]amine, tris[2-(methoxymethoxy)ethyl]amine-N-oxide, dibutylaminobenzoic acid, morpholine derivatives, imidazole derivatives, etc. Addition of such basic compounds can, for example, further suppress the diffusion rate of acid in the resist film or correct the shape.

[0202] Further, examples of the quencher include onium salts such as sulfonium salts, iodonium salts, and ammonium salts of carboxylic acids not fluorinated at the α-position, as described in JP-A-2008-158339. Sulfonic acids, imide acids, or methide acids fluorinated at the α-position are necessary for deprotecting acid labile groups, and salt exchange with onium salts not fluorinated at the α-position releases carboxylic acids not fluorinated at the α-position. Carboxylic acids not fluorinated at the α-position hardly undergo deprotection reactions, and therefore function as quenchers.

[0203] Examples of onium salts of carboxylic acids that are not fluorinated at the α-position include those represented by the following formula (E1). [ka]

[0204] In formula (E1), R 201 represents a hydrocarbyl group having 1 to 40 carbon atoms which may contain a hydrogen atom or a heteroatom, but excludes those in which the hydrogen atom bonded to the carbon atom at the α-position of the carboxy group is substituted with a fluorine atom or a fluoroalkyl group.

[0205] R 201 The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 40 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0]. 2,6 ]Cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms such as a decyl group, an adamantyl group, and an adamantylmethyl group; alkenyl groups having 2 to 40 carbon atoms such as a vinyl group, an allyl group, a propenyl group, a butenyl group, and a hexenyl group; cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 40 carbon atoms such as a cyclohexenyl group; phenyl group, naphthyl group, alkylphenyl groups (2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert aryl groups having 6 to 40 carbon atoms such as aryl groups having 6 to 40 carbon atoms (e.g., 4-n-butylphenyl group, 4-n-butylphenyl group), dialkylphenyl groups (e.g., 2,4-dimethylphenyl group, 2,4,6-triisopropylphenyl group), alkylnaphthyl groups (e.g., methylnaphthyl group, ethylnaphthyl group), and dialkylnaphthyl groups (e.g., dimethylnaphthyl group, diethylnaphthyl group); and aralkyl groups having 7 to 40 carbon atoms such as benzyl group, 1-phenylethyl group, and 2-phenylethyl group.

[0206] Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a cyano group, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like. Examples of the hydrocarbyl group containing a heteroatom include heteroaryl groups such as a thienyl group; alkoxyphenyl groups such as a 4-hydroxyphenyl group, a 4-methoxyphenyl group, a 3-methoxyphenyl group, a 2-methoxyphenyl group, a 4-ethoxyphenyl group, a 4-tert-butoxyphenyl group, and a 3-tert-butoxyphenyl group; alkoxynaphthyl groups such as a methoxynaphthyl group, an ethoxynaphthyl group, an n-propoxynaphthyl group, and an n-butoxynaphthyl group; dialkoxynaphthyl groups such as a dimethoxynaphthyl group and a diethoxynaphthyl group; and aryloxoalkyl groups such as a 2-aryl-2-oxoethyl group, a 2-(1-naphthyl)-2-oxoethyl group, and a 2-(2-naphthyl)-2-oxoethyl group.

[0207] In formula (E1), Mq A + is an onium cation. The onium cation is preferably a sulfonium cation, an iodonium cation, or an ammonium cation, and more preferably a sulfonium cation or an iodonium cation. Specific examples of the sulfonium cation include those exemplified as the sulfonium cation represented by formula (cation-1). Specific examples of the iodonium cation include those exemplified as the iodonium cation represented by formula (cation-2).

[0208] Examples of the anion of the onium salt represented by formula (E1) include, but are not limited to, those shown below. [ka]

[0209] [ka]

[0210] [ka]

[0211] As the quencher, a sulfonium salt of an iodinated benzene ring-containing carboxylic acid represented by the following formula (E2) can also be suitably used. [ka]

[0212] In formula (E2), s is an integer of 1 to 5. t is an integer of 0 to 3, provided that 1≦s+t≦5. u is an integer of 1 to 3.

[0213] In formula (E2), R 211 represents a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an amino group, a nitro group, a cyano group, or a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms, or a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms, in which some or all of the hydrogen atoms may be substituted with halogen atoms, or -N(R 211A )-C(=O)-R 211B or -N(R 211A )-C(=O)-OR 211B R 211A is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 211B is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. When t and / or u is 2 or more, each R 211 may be the same or different from each other.

[0214] In formula (E2), L 11 is a single bond or a (u+1)-valent linking group having 1 to 20 carbon atoms, and may contain at least one selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxy group, and a carboxy group. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, and saturated hydrocarbylsulfonyloxy group may be linear, branched, or cyclic.

[0215] In formula (E2), R 212 , R 213 and R 214 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples thereof include an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms. Some or all of the hydrogen atoms in the hydrocarbyl group may be substituted with a hydroxy group, a carboxy group, a halogen atom, an oxo group, a cyano group, a nitro group, a sultone ring, a sulfo group, or a sulfonium salt-containing group. Some of the -CH2- groups in the hydrocarbyl group may be substituted with an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate bond, or a sulfonate ester bond. Furthermore, R 212 and R 213 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

[0216] Specific examples of the compound represented by formula (E2) include those described in JP 2017-219836 A. The compound represented by formula (E2) has high absorption, a high sensitizing effect, and a high acid diffusion control effect.

[0217] As the quencher, a nitrogen atom-containing carboxylate compound represented by the following formula (E3) can also be used. [ka]

[0218] In formula (E3), R 221 ~R 224 are each independently a hydrogen atom, -L 12 -CO2 - or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. 221 and R 222 and R 222 and R 223 and, or R 223 and R 224 and may be bonded to each other to form a ring together with the carbon atoms to which they are attached. 12 R is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 225 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom.

[0219] In formula (E3), ring R r is a ring containing carbon atoms and nitrogen atoms and having 2 to 6 carbon atoms, and some or all of the hydrogen atoms bonded to the carbon atoms of the ring are hydrocarbyl groups having 1 to 20 carbon atoms, or -L 12 -CO2 - and some of the carbon atoms of the ring may be substituted with sulfur atoms, oxygen atoms, or nitrogen atoms. The ring may be an alicyclic ring or an aromatic ring, and is preferably a 5- or 6-membered ring, specific examples of which include a pyridine ring, a pyrrole ring, a pyrrolidine ring, a piperidine ring, a pyrazole ring, an imidazoline ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, an imidazoline ring, an oxazole ring, a thiazole ring, a morpholine ring, a thiazine ring, and a triazole ring.

[0220] The onium carboxylic acid salt represented by formula (E3) has at least one -L 12 -CO2 - group, i.e., R 221 ~R 224 At least one of the -L 12-CO2 - and / or at least one of the hydrogen atoms bonded to the carbon atom of the ring R is -L 12 -CO2 - is replaced by

[0221] In formula (E3), Mq B + is a sulfonium cation, an iodonium cation, or an ammonium cation, and is preferably a sulfonium cation. Specific examples of the sulfonium cation include the same as those exemplified as the sulfonium cation represented by formula (cation-1).

[0222] Examples of the anion of the compound represented by formula (E3) include, but are not limited to, those shown below. [ka]

[0223] [ka]

[0224] [ka]

[0225] [ka]

[0226] [ka]

[0227] [ka]

[0228] Furthermore, a weak acid betaine type compound can also be used as the quencher. Specific examples thereof include, but are not limited to, the following: [ka]

[0229] Further examples of the quencher include the polymer-type quencher described in JP 2008-239918 A. This quencher enhances the rectangularity of the resist pattern by orienting on the surface of the resist film. The polymer-type quencher also has the effect of preventing pattern film loss and pattern top rounding when a protective film for immersion lithography is applied.

[0230] When the chemically amplified negative resist composition of the present invention contains a quencher (E), the content thereof is preferably 0 to 50 parts by mass, and more preferably 0.1 to 40 parts by mass, relative to 80 parts by mass of the base polymer (B). The quenchers (E) may be used singly or in combination of two or more.

[0231] When the chemically amplified negative resist composition of the present invention contains a photoacid generator as component (A) and a quencher as component (E), the content ratio of the photoacid generator to the quencher ((A) / (E)) is preferably less than 6 by mass, 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 negative resist composition is within the above range, acid diffusion can be sufficiently suppressed, and excellent resolution and dimensional uniformity can be obtained.

[0232] [(F) Organic solvent] The chemically amplified negative resist composition of the present invention may contain an organic solvent as component (F). The organic solvent is not particularly limited 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 No. 2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol; propylene glycol monomethyl ether (PGME), ethylene glycol monomethyl ether, propylene glycol monoethyl ether, and ethylene glycol monoethyl ether. Examples 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, and propylene glycol mono-tert-butyl ether acetate; lactones such as γ-butyrolactone; and mixed solvents thereof.

[0233] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, PGME, cyclohexanone, EL, γ-butyrolactone, and mixed solvents thereof are preferred.

[0234] When the chemically amplified negative resist composition of the present invention contains an organic solvent (F), the content thereof is preferably 200 to 10,000 parts by mass, and more preferably 400 to 6,000 parts by mass, relative to 80 parts by mass of the base polymer (B). The organic solvent (F) may be used alone or in combination of two or more types.

[0235] [(G) Surfactant] The chemically amplified negative resist composition of the present invention may contain a commonly used surfactant to improve its coatability onto a substrate. Examples of such surfactants include PF-636 (manufactured by OMNOVA SOLUTIONS) and FC-4430 (manufactured by 3M). Many surfactants are known, as described in JP-A-2004-115630, and these surfactants can be used in conjunction with other known surfactants. When the chemically amplified negative resist composition of the present invention contains a surfactant (G), the content of the surfactant is preferably 0 to 5 parts by mass per 80 parts by mass of the base polymer (B). The surfactant (G) may be used alone or in combination of two or more types.

[0236] [Method for forming resist pattern] The method for forming a resist pattern of the present invention includes the steps of: forming a resist film on a substrate using the aforementioned chemically amplified negative resist composition; irradiating the resist film with a pattern using high-energy rays (i.e., exposing the resist film using high-energy rays); and developing the resist film irradiated with the pattern using an alkaline developer.

[0237] The substrate may be, for example, a substrate for manufacturing integrated circuits (Si, SiO, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective coating, etc.), or a substrate for manufacturing transmission or reflection mask circuits (Cr, CrO, CrON, MoSi2, Si, SiO, SiO2, SiON, SiONC, CoTa, NiTa, TaBN, SnO2, etc.). The chemically amplified negative resist composition is applied to the substrate by a method such as spin coating to a film thickness of 0.03 to 2 μm, and the composition is 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.

[0238] Next, the resist film is exposed to high-energy rays to form a pattern. Examples of the high-energy rays include ultraviolet rays, far ultraviolet rays, excimer laser light (KrF, ArF, etc.), EUV, X-rays, gamma rays, synchrotron radiation, and EB. In the present invention, exposure using EUV or EB is preferred.

[0239] 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

[0240] 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.

[0241] Next, post-exposure baking (PEB) is carried out on a hot plate, preferably at 60 to 150° C. for 1 to 20 minutes, more preferably at 80 to 140° C. for 1 to 10 minutes.

[0242] Thereafter, the substrate is developed using a developer such as an aqueous alkaline solution of 0.1 to 5 mass %, preferably 2 to 3 mass %, TMAH, etc., by a conventional method such as dipping, puddling, or spraying for preferably 0.1 to 3 minutes, more preferably 0.5 to 2 minutes, to form a desired pattern on the substrate.

[0243] The chemically amplified negative resist composition of the present invention is useful because it can form a pattern with particularly good resolution and small LER. Furthermore, the chemically amplified negative 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, since 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 by sputtering a film of metallic chromium or a chromium compound containing one or more light elements selected from oxygen, nitrogen, and carbon, SiO , SiO x Examples of the chemically amplified negative resist composition include a substrate containing, as an outermost layer, a tantalum compound, a molybdenum compound, a cobalt compound, a nickel compound, a tungsten compound, or a tin compound. The chemically amplified negative resist composition of the present invention is particularly useful for pattern formation using a photomask blank as the substrate. In this case, the photomask blank may be either a transmissive or reflective type.

[0244] As a transmission mask blank, a photomask blank having a light-shielding film made of a chromium-based material may be a photomask blank for a binary mask or a photomask blank for a phase shift mask. In the case of a photomask blank for a binary mask, the light-shielding film may have an antireflection layer and a light-shielding layer made of a chromium-based material, or the entire antireflection film on the surface layer side or only the layer further above the antireflection film on the surface layer side may be made of a chromium-based material, with the remaining portion being made of a silicon-based compound material that may contain, for example, a transition metal. In addition, in the case of a photomask blank for a phase shift mask, the target photomask blank may be a photomask blank for a phase shift mask having a chromium-based light-shielding film on a phase shift film.

[0245] The above-mentioned photomask blank having a chromium-based material in the outermost layer is very well known, as is disclosed in JP-A Nos. 2008-26500 and 2007-302873, or as examples of prior art therein. Therefore, detailed description will be omitted. However, for example, when a light-shielding film having an antireflection layer and a light-shielding layer is formed using a chromium-based material, the following film configuration can be used.

[0246] When a light-shielding film having an anti-reflection layer and a light-shielding layer is formed using a chromium-based material, the layer structure may be such that the anti-reflection layer and the light-shielding layer are laminated in this order from the surface side, or the anti-reflection layer, the light-shielding layer, and the anti-reflection layer are laminated in this order. The anti-reflection layer and the light-shielding layer may each be multi-layered, and the composition between layers with different compositions may change discontinuously or continuously. The chromium-based material used includes metallic chromium and metallic chromium containing light elements such as oxygen, nitrogen, and carbon. Specifically, metallic chromium, chromium oxide, chromium nitride, chromium carbide, chromium oxide nitride, chromium carbide oxide, chromium nitride carbonitride, chromium oxynitride carbonitride, etc. may be used.

[0247] A reflective mask blank includes a substrate, a multilayer reflective film formed on one main surface (front surface) of the substrate, specifically a multilayer reflective film that reflects exposure light such as EUV light, and an absorber film formed on the multilayer reflective film, specifically an absorber film that absorbs exposure light such as EUV light and reduces reflectance. From the reflective mask blank (EUV reflective mask blank), a reflective mask (EUV reflective mask) 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 typically light with a wavelength of about 13.5 nm.

[0248] Although the multilayer reflective film is preferably provided in contact with one main surface of the substrate, a base film may be provided between the substrate and the multilayer reflective film as long as the effects of the present invention are not lost. The absorber film may be formed in contact with the multilayer reflective film, but a protective film (protective film for the multilayer reflective film) may be provided between the multilayer reflective film and the absorber film, preferably in contact with the multilayer reflective film, and more preferably in contact with both the multilayer reflective film and the absorber film. The protective film is used to protect the multilayer reflective film during processing such as cleaning and repair. Furthermore, the protective film preferably has the function of protecting the multilayer reflective film when the absorber film is patterned by etching and preventing oxidation of the multilayer reflective film. Meanwhile, a conductive film used for electrostatically chucking the reflective mask to an exposure device may be provided under the other main surface (back surface) of the substrate, which is the surface opposite to the one main surface, preferably in contact with the other main surface. Here, one main surface of the substrate is the front surface and the upper side, and the other main surface is the back surface and the lower side, but the front and back and top and bottom of both are defined for convenience, and the one main surface and the other main surface are either of the two main surfaces (film formation surfaces) of the substrate, and the front and back and top and bottom are interchangeable. More specifically, it can be formed by a method such as that described in JP 2021-139970 A or exemplified as prior art therein.

[0249] According to the method for forming a resist pattern of the present invention, even when a substrate (for example, a transmission type or a reflection type mask blank) is used whose outermost surface is made of a material that is likely to affect the shape of the resist pattern, such as a material containing chromium, silicon, or tantalum, it is possible to obtain a pattern that has extremely high resolution, small LER, excellent rectangularity, and excellent pattern fidelity. [Example]

[0250] 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.

[0251] The structures of polymers P-1 to P-30 used in the resist compositions are shown in the following Table 1. Note that Mw is a value measured in terms of polystyrene by GPC using THF or DMF as a solvent.

[0252] [Table 1]

[0253] In Table 1, the structure of each unit is as follows: [ka]

[0254] [ka]

[0255] [ka]

[0256] [ka]

[0257] [ka]

[0258] [1] Preparation of chemically amplified negative resist composition [Examples 1-1 to 1-54, Comparative Examples 1-1 to 1-10] Chemically amplified negative resist compositions (R-1 to R-54, CR-1 to CR-10) were prepared by dissolving each component in an organic solvent according to the composition shown in Tables 2 to 4 below, and filtering the resulting solutions through UPE filters and / or nylon filters selected from 10 nm, 5 nm, 3 nm, and 1 nm sizes. The organic solvent was a mixed solvent of 790 parts by weight of PGMEA, 1580 parts by weight of EL, and 1580 parts by weight of PGME. Some compositions also contained fluorine-containing polymers (polymers FP-1 to FP-5) as additives, tetramethoxymethylglycoluril (TMGU) as a crosslinker, and PF-636 (manufactured by OMNOVA SOLUTIONS) as a surfactant.

[0259] [Table 2]

[0260] [Table 3]

[0261] [Table 4]

[0262] In Tables 2 to 4, the photoacid generators PAG-1 to PAG-9, comparative photoacid generators cPAG-1 to cPAG-4, quenchers Q-1 to Q-4, and fluorine atom-containing polymers FP-1 to FP-5 are as follows. [ka]

[0263] [ka]

[0264] [ka] [ka]

[0265] [ka]

[0266] [2] EB lithography evaluation [Examples 2-1 to 2-54, Comparative Examples 2-1 to 2-10] Each chemically amplified negative resist composition (R-1 to R-54, CR-1 to CR-10) was spin-coated onto a 152 mm square mask blank with a silicon oxide outer surface that had been vapor primed with hexamethyldisilazane (HMDS) using ACT-M (Tokyo Electron Limited), and the resulting mask blank was pre-baked on a hot plate at 110°C for 600 seconds to produce an 80 nm thick resist film. The thickness of the resulting resist film was measured using an optical measuring device, Nanospec (Nanometrics). Measurements were performed at 81 locations on the blank substrate surface, excluding the outer edge extending 10 mm inward from the outer periphery, and the average thickness and thickness range were calculated.

[0267] The film was exposed using an electron beam exposure system (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% by mass TMAH aqueous solution to obtain a negative pattern.

[0268] The obtained resist patterns were evaluated as follows: The prepared patterned mask blanks were observed with a top-down SEM (scanning electron microscope), and the exposure dose required to resolve 200 nm 1:1 line and space (LS) at 1:1 was determined as the optimal exposure dose (μC / cm 2), and the minimum dimension at the exposure dose required to resolve a 200 nm LS at a 1:1 ratio was defined as the resolution (limiting resolution). For a 200 nm LS pattern obtained by irradiation at the optimal exposure dose, 80 edge detection points were performed on each of the 32 edges of the 200 nm LS pattern using an SEM. The standard deviation (σ) was tripled (3σ) to determine the LER (nm). The pattern shape was visually determined to be rectangular. Furthermore, pattern fidelity was evaluated by calculating the area loss value (%) of one corner of a dot pattern when a 120 nm square dot pattern was arranged at a density of 36%. The smaller the value, the better the rectangularity of the dot shape. The results are shown in Tables 5 to 7.

[0269] [Table 5]

[0270] [Table 6]

[0271] [Table 7]

[0272] The chemically amplified negative resist compositions of the present invention (R-1 to R-54) all exhibited good resolution, LER, pattern rectangularity, and pattern fidelity. On the other hand, the comparative resist compositions (CR-1 to CR-10) had insufficient acid generator design and exhibited insufficient performance in terms of resolution, LER, and pattern rectangularity.

[0273] The method for forming a resist pattern using the chemically amplified negative resist composition of the present invention is useful for the production of semiconductor devices, particularly for photolithography in the processing of transmission or reflection type photomask blanks.

Claims

1. A chemically amplified negative resist composition comprising: (A) a photoacid generator comprising an onium salt represented by the following formula (A); and (B) a base polymer comprising a polymer including a repeating unit represented by the following formula (B1): 【Chemistry 1】 (In the formula, n1 and n2 are each independently an integer of 0 to 2. When n1 = 0, n3 is an integer that satisfies 1 ≦ n3 ≦ 5, when n1 = 1, n3 is an integer that satisfies 1 ≦ n3 ≦ 7, and when n1 = 2, n3 is an integer that satisfies 1 ≦ n3 ≦ 9. When n2 = 0, n4 is an integer that satisfies 0 ≦ n4 ≦ 5, when n2 = 1, n4 is an integer that satisfies 0 ≦ n4 ≦ 7, and when n2 = 2, n4 is an integer that satisfies 0 ≦ n4 ≦ 9. L is a single bond, an ether bond, an ester bond, a sulfonate ester bond, an amide bond, a carbonate bond, or a carbamate bond. R 1 are each independently an iodine atom or a branched or cyclic hydrocarbyl group having 3 to 20 carbon atoms which may contain a heteroatom, and at least one R 1 is bonded to the carbon atom adjacent to the carbon atom to which L is bonded. 1 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 2 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 2 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. W 1 is a carbon atom C of an adjacent aromatic ring 1 and C 2 and a part of the carbon atoms forming the ring may be substituted with a group containing a hetero atom. W 2 is a carbon atom C of an adjacent aromatic ring 3 and C 4 and a part of the carbon atoms forming the ring may be substituted with a group containing a hetero atom. Z + is an onium cation. 【Chemistry 2】 (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 the —CH 2 - may be replaced by -O-.

2. 2. The chemically amplified negative resist composition according to claim 1, wherein the component (A) is an onium salt represented by the following formula (A1): 【Transformation 3】 (In the formula, n2, n3, n4, W 1 , W 2 , L, R 1 , R 2 and Z + is the same as above.)

3. 3. The chemically amplified negative resist composition according to claim 2, wherein the component (A) is an onium salt represented by the following formula (A2): 【Chemistry 4】 (In the formula, n3, n4, W 1 , R 1 , R 2 and Z + is the same as above.)

4. Z + 2. The chemically amplified negative resist composition according to claim 1, wherein is an onium cation represented by the following formula (cation-1) or (cation-2): 【Transformation 5】 (In the formula, R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. ct1 and R ct2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.)

5. 2. The chemically amplified negative resist composition according to claim 1, wherein the polymer further comprises a repeating unit represented by the following formula (B2): 【Transformation 6】 (In the formula, b1 is 0 or 1. b2 is an integer of 0 to 2. b3 is an integer that satisfies 0≦b3≦5+2(b2)−b4. b4 is an integer of 1 to 3. 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. R 13 and R 14 are each independently a hydrogen atom, a saturated hydrocarbyl group having 1 to 15 carbon atoms which may be substituted with a hydroxy group or a saturated hydrocarbyloxy group, or an aryl group which may have a substituent. 13 and R 14 cannot be a hydrogen atom at the same time. 13 and R 14 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. 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-. W 1 is a hydrogen atom, an aliphatic hydrocarbyl group having 1 to 10 carbon atoms, or an aryl group which may have a substituent.

6. 2. The chemically amplified negative 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): 【Transformation 7】 (In the formula, c and d each independently represent an integer of 0 to 4. e1 is 0 or 1. e2 is an integer of 0 to 2. e3 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 are 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. 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 3 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the —CH 2 - may be replaced by -O-.

7. 6. The chemically amplified negative resist composition according to claim 5, wherein the polymer further comprises at least one selected from the group consisting of a repeating unit represented by the following formula (B6), a repeating unit represented by the following formula (B7), a repeating unit represented by the following formula (B8), 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): 【Transformation 8】 (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. 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. * indicates a bond to a carbon atom in the main chain, and ** indicates 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. f1 and f2 are each independently 0 or 1, but Y 4 is a single bond, f1 and f2 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, and 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.)

8. 8. The chemically amplified negative resist composition according to claim 7, wherein the polymer comprises a repeating unit represented by the following formula (B1-1), a repeating unit represented by the following formula (B2-1), or a repeating unit represented by the following formula (B2-2), and a repeating unit represented by the following formula (B7): 【Chemistry 9】 (In the formula, a4, b4, R A , R B , Y 2 , R 13 , R 14 , R 33 , R 34 , R 35 and R HF is the same as above.)

9. 8. The chemically amplified negative resist composition according to claim 7, wherein the base polymer (B) further comprises a polymer that contains a repeating unit represented by formula (B1) and a repeating unit represented by formula (B2), but does not contain any repeating unit represented by formulas (B6) to (B13).

10. 2. The chemically amplified negative 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 negative resist composition according to claim 1, further comprising (C) a crosslinking agent.

12. 6. The chemically amplified negative resist composition according to claim 5, which does not contain a crosslinking agent.

13. 2. The chemically amplified negative resist composition according to claim 1, further comprising (D) a fluorine atom-containing polymer that 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 that may further contain at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (D5) and a repeating unit represented by the following formula (D6): 【Chemistry 10】 (In the formula, x is an integer of 1 to 3. y is an integer that satisfies 0≦y≦5+2z−x. z is 0 or 1. g is an integer of 1 to 3.) R C are each independently 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 bond. R 109 is a hydrogen atom or a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a heteroatom-containing group interposed between its 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 interposed 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 —CH 2 A portion of the - may be substituted with an ester bond or an ether bond. Z 1 is a (g+1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (g+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. Z 31 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. 32 is a single bond, an ester bond, an ether bond, or a sulfonamide bond. * is a bond to a carbon atom in the main chain.)

14. 2. The negative resist composition according to claim 1, further comprising (E) a quencher.

15. 15. The chemically amplified negative resist composition according to claim 14, wherein the content ratio of the acid generator (A) to the quencher (E) is less than 6 in terms of mass ratio.

16. 2. The chemically amplified negative resist composition according to claim 1, further comprising (F) an organic solvent.

17. 17. A method for forming a resist pattern, comprising: forming a resist film on a substrate using the chemically amplified negative resist composition according to claim 1; irradiating the resist film with a pattern using high-energy rays; and developing the resist film that has been irradiated with the pattern using an alkaline developer.

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

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

20. 18. The method for forming a resist pattern according to claim 17, wherein the substrate is a transmission or reflection mask blank.

21. A transmission or reflection mask blank coated with the chemically amplified negative resist composition according to any one of claims 1 to 16.

Images