Radiation-sensitive composition, pattern formation method, and compound

Abstract

Provided is a radiation-sensitive composition or the like capable of exhibiting sensitivity, LWR, CDU, EL, DOF, number of development defects, pattern rectangularity, pattern circularity, and MEEF at sufficient levels during pattern formation. The radiation-sensitive composition contains a compound represented by formula (1), a polymer including a structural unit (I) having an acid-dissociable group, and a solvent.　(In the formula, Rz is -F, -CN, -SO2Ra, -CF2H, -SF5 or -CF3. Ra is a hydrogen atom or a monovalent organic group having 1-20 carbon atoms. R1 is -H, -CN, -SF5 or a monovalent organic group having 1-10 carbon atoms. Y is -O- or -NRb-. L is a single bond or a divalent organic group. However, when Rz is -F, the divalent organic group has at most four carbon atoms. W is a monovalent condensed cyclic group or a monovalent condensed cyclic group having a substituent. The condensed cyclic group or the substituent has a hetero atom. Z+ is a monovalent organic cation.)

Description

Radiation-sensitive composition, pattern-forming method, and compound

[0001] The present invention relates to radiation-sensitive compositions, pattern-forming methods, and compounds.

[0002] Photolithography, which uses resist compositions, is employed to form fine circuits in semiconductor devices. A typical procedure involves, for example, generating acid by irradiating a resist composition film with radiation through a mask pattern. This acid then acts as a catalyst, creating a difference in the solubility of the polymer in alkaline or organic developers between the exposed and unexposed areas, thereby forming a resist pattern on the substrate.

[0003] The above-mentioned photolithography techniques utilize short-wavelength radiation such as ArF excimer lasers, and further advance pattern miniaturization by employing liquid immersion lithography, a method in which exposure is performed with the space between the lens of the exposure apparatus and the resist film filled with a liquid medium. As next-generation technologies, lithography using even shorter-wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet) is also being considered.

[0004] Regarding photoacid generators, which are the main components of resist compositions, perfluoroalkyl sulfonic acid, which can impart strong acid, is widely used to improve sensitivity and resolution. On the other hand, in recent years, due to growing environmental awareness, photoacid generators with reduced fluorine atom content are being investigated (see Japanese Patent Publication No. 7015295).

[0005] Patent No. 7015295

[0006] Even with photoacid generators that have reduced fluorine atom content, resist performance is required to be equivalent to or better than conventional resists in terms of sensitivity, LWR, CDU, exposure margin (EL), depth of field (DOF), number of development defects, pattern rectangularity, pattern circularity, MEEF, etc.

[0007] The present invention aims to provide a radiation-sensitive composition, a pattern-forming method, and a compound that can exhibit sufficient levels of sensitivity, LWR, CDU, EL, DOF, development defect count, pattern rectangularity, pattern circularity, and MEEF during pattern formation.

[0008] As a result of intensive studies to solve this problem, the present inventors have found that the above object can be achieved by adopting the following configuration, and have completed the present invention.

[0009] In one embodiment, the present invention relates to a radiation-sensitive composition containing a compound represented by the following formula (A) (hereinafter also referred to as "compound (A)"), a polymer containing a structural unit (I) having an acid-dissociable group, and a solvent. (In the above formula (A), R ２ R ａ , -CF ２ H, -SF ５ or -CF ３ . R ａ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R １ is -H, -CN, -SF ５ or a monovalent organic group having 1 to 10 carbon atoms. Y is -O- or -NR ｂ -. R ｂ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. L is a single bond or a divalent organic group. However, when R ｚ is -F, the carbon number of the above divalent organic group is 4 or less. W is a monovalent condensed ring group or a monovalent condensed ring group having a substituent. However, at least the condensed ring group or the substituent has a hetero atom. Z ＋ is a monovalent organic cation.)

[0010] According to the radiation-sensitive composition, excellent sensitivity, LWR, CDU, exposure margin (EL), depth of focus (DOF), number of development defects, pattern rectangularity, pattern circularity, and MEEF can be exhibited during pattern formation. Although the reason for this is not clear, it is speculated as follows.

[0011] ​Compound (A) has a bulky fused cyclic group, which allows for the control and shortening of the diffusion length of the generated acid. In addition, polarity is imparted by incorporating a heteroatom into at least one of the fused cyclic group or its substituent, resulting in appropriate interaction with the polymer and adjustment of solubility. These factors allow for appropriate control of the diffusion length of the generated acid while simultaneously improving the solubility contrast. On the other hand, because compound (A) has a compact structure near the sulfonate anion, contact between the generated acid and the acid-dissociable group is facilitated, inducing sufficient acid dissociation and suppressing development defects. Furthermore, by reducing the fluorine atom content, the dispersibility of compound (A) in the resist film and its solubility in the developer can be controlled. It is presumed that the above resist performance can be achieved through the combined effects of these factors.

[0012] In another embodiment, the present invention relates to a pattern forming method comprising the steps of: applying the above-mentioned radiation-sensitive composition directly or indirectly to a substrate to form a resist film; exposing the resist film to light; and developing the exposed resist film with a developer.

[0013] In this pattern formation method, since the above-mentioned radiation-sensitive composition is used that exhibits excellent sensitivity, LWR, exposure margin (EL), depth of field (DOF), number of development defects, pattern rectangularity, CDU, MEEF, and pattern circularity during pattern formation, high-quality resist patterns can be efficiently formed.

[0014] In yet another embodiment, the present invention relates to a compound represented by the following formula (A'). (In the above formula (A'), R ｚ -F, -CN, -SO ２ R ａ , -CF ２ H, -SF ５ or -CF ３ That is. R ａ R is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. １ -H, -CN, -SF ５ Alternatively, it is a monovalent organic group having 1 to 10 carbon atoms. Y is -O- or -NRｂ - is R ｂ L is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. L is a single bond or a divalent organic group. However, R ｚ If is -F, the number of carbon atoms in the divalent organic group is 4 or less. W' is a monovalent fused cyclic group, or a monovalent fused cyclic group having a substituent. However, at least the fused cyclic group or the substituent has a heteroatom. R ｚ If is -F and W is a substituted monovalent fused cyclic group, then the substituent of W is a substituent other than a hydroxyl group. ＋ (This is a monovalent organic cation.)

[0015] This compound exhibits excellent dispersibility, developer solubility, and acid diffusion length control, in addition to the aforementioned strong acidity, making it suitable as an acid generator in radiation-sensitive compositions.

[0016] In this specification, "organic group" means a group containing at least one carbon atom. However, cyano groups (-CN), carboxyl groups (-COOH), formyl groups (-CHO), carbonyl groups (-CO-:-(C=O)-), etc., which can function as functional or characteristic groups on their own, are excluded as organic groups. "Fused ring" means a polycyclic structure composed of two or more rings, in which any two adjacent rings share two or more consecutive atoms. "Fused ring group" means a group obtained by removing one hydrogen atom from a fused ring. When three or more atoms are shared between two adjacent rings, the atoms or atomic chains excluding the atoms at both ends of the three or more shared atoms are called "bridges" or "bridged structures." "Bridged fused ring group" means a fused ring group having at least one bridge. "A fused ring group has heteroatoms" means that a fused ring group has heteroatoms as ring constituent atoms. The statement "the substituent has a heteroatom" includes not only cases where the substituent has a heteroatom as one of its constituent atoms, but also cases where the substituent itself is a heteroatom (such as an oxo group (O=) or a halogen atom). The abbreviations for substituents are "Me" for a methyl group and "Ph" for a phenyl group.

[0017] The embodiments of the present invention will be described in detail below, but the present invention is not limited to these embodiments. Preferred combinations of embodiments are also preferred.

[0018] Radiation-sensitive composition The radiation-sensitive composition according to this embodiment (hereinafter also simply referred to as "composition") contains compound (A), a polymer, and a solvent. The above composition may contain other optional components as long as they do not impair the effects of the present invention.

[0019] <Compound> The compound (i.e., compound (A)) is the compound represented by formula (1) above, and contains an anion (sulfonic acid anion) and an organic cation, and functions as an acid generator that generates an acid that dissociates the acid-dissociable group by exposure.

[0020] R １ -SO ２ R ａ In R ａ Examples of monovalent organic groups having 1 to 20 carbon atoms represented by include monovalent hydrocarbon groups having 1 to 20 carbon atoms, groups (a) having a divalent heteroatom-containing linking group between carbon atoms (between two adjacent or non-adjacent carbon atoms) or at the end of the hydrocarbon group, groups in which some or all of the hydrogen atoms of the hydrocarbon group or group (a) are replaced with monovalent heteroatom-containing groups, or combinations thereof.

[0021] Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms include monovalent linear hydrocarbon groups having 1 to 20 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, or combinations thereof.

[0022] Examples of monovalent chain hydrocarbon groups having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, and tert-butyl groups; alkenyl groups such as ethenyl, propenyl, and butenyl groups; and alkynyl groups such as ethynyl, propynyl, and butynyl groups.

[0023] Examples of monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms include cycloalkyl groups such as cyclopentyl and cyclohexyl groups; cycloalkenyl groups such as cyclopropenyl, cyclopentenyl, and cyclohexenyl groups; bridged ring saturated hydrocarbon groups such as norbornyl, adamantyl, and tricyclodecyl groups; and bridged ring unsaturated hydrocarbon groups such as norbornyl and tricyclodecenyl groups.

[0024] Examples of monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xyl, naphthyl, and anthryl groups, and aralkyl groups such as benzyl, phenethyl, naphthylmethyl, and anthrylmethyl groups.

[0025] Examples of heteroatoms that constitute a divalent heteroatom-containing linking group or a monovalent heteroatom-containing group include oxygen, nitrogen, sulfur, phosphorus, silicon, and halogen atoms. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms.

[0026] Examples of divalent heteroatom-containing linking groups include -CO-, -CS-, -NR'-, -O-, -S-, and -SO ２ - and combinations thereof are examples. R' is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.

[0027] Examples of monovalent heteroatom-containing groups include hydroxyl groups, carboxyl groups, sulfanyl groups, cyano groups, nitro groups, and halogen atoms. Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0028] R ａ Preferably, the group is a monovalent linear hydrocarbon group having 1 to 20 carbon atoms, more preferably a monovalent linear saturated hydrocarbon group having 1 to 10 carbon atoms, even more preferably a monovalent linear saturated hydrocarbon group having 1 to 5 carbon atoms, and particularly preferably a methyl group, an ethyl group, or an n-propyl group.

[0029] R ｚ -F, -CN, -SO ２ R ａ or -CF ２It is preferably H, -F, -CN or -CF ２ It is more preferable that it be H.

[0030] R １ As a monovalent organic group having 1 to 10 carbon atoms, R ａ Among the monovalent organic groups having 1 to 20 carbon atoms represented by [formula], groups corresponding to 1 to 10 carbon atoms can be suitably adopted.

[0031] R １ The most preferred group is -H or a monovalent linear hydrocarbon group having 1 to 5 carbon atoms, more preferably -H or a monovalent linear saturated hydrocarbon group having 1 to 5 carbon atoms, and even more preferably -H, a methyl group, or an ethyl group. １ It is preferable that it does not contain fluorine atoms.

[0032] Y as -NR ｂ -R in ｂ As a monovalent hydrocarbon group having 1 to 10 carbon atoms, R ａ Among the monovalent hydrocarbon groups having 1 to 20 carbon atoms shown above, groups corresponding to those having 1 to 10 carbon atoms can be suitably adopted.

[0033] R ｂ It is preferable that it be a hydrogen atom.

[0034] Y is preferably -O-.

[0035] As for divalent organic groups represented by L, R ａ A monovalent organic group having 1 to 20 carbon atoms, represented by the formula shown, can be suitably used, with one hydrogen atom removed.

[0036] L is preferably an alkanediyl group, a divalent heteroatom-containing linking group, a group combining these groups, or a single bond, and is preferably a methanediyl group, 1,1-ethanediyl group, 1,2-ethanediyl group, 1,3-propanediyl group, 2,2-propanediyl group, -OCO- ＊ (* indicates a bond on the Y side.) Or a group with 4 or fewer carbon atoms that is a combination of these groups, or a single bond is more preferable, and a single bond is even more preferable.

[0037] In W, the heteroatoms can be present in the following ways: if the fused ring group has no substituent, the fused ring group has a heteroatom; if the fused ring group has a substituent, the fused ring group has a heteroatom and the substituent does not; the fused ring group does not have a heteroatom and the substituent has a heteroatom; or both the fused ring group and the substituent have a heteroatom.

[0038] The rings constituting the above-mentioned fused ring group are preferably alicyclic hydrocarbon structures having 3 to 20 carbon atoms, aromatic hydrocarbon structures having 6 to 20 carbon atoms, aliphatic heterocyclic structures having 3 to 20 carbon atoms, or aromatic heterocyclic structures having 5 to 20 carbon atoms. Alternatively, these ring structures may be combined. The above-mentioned fused ring group may contain two or more rings of the same type, or two or more rings of different types.

[0039] As for the above alicyclic hydrocarbon structure with 3 to 20 carbon atoms, R ａ Examples of ring structures corresponding to the monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms shown in [reference] include [examples].

[0040] The above aromatic hydrocarbon structure with 6 to 20 carbon atoms is R ａ Structures corresponding to monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, as shown in the diagram, can be suitably adopted.

[0041] Examples of the above-mentioned aliphatic heterocyclic structures having 3 to 20 carbon atoms include oxygen-containing aliphatic heterocyclic structures such as oxirane, tetrahydrofuran, tetrahydropyran, dioxolane, and dioxane; nitrogen-containing aliphatic heterocyclic structures such as aziridine, pyrrolidine, piperidine, and piperazine; sulfur-containing aliphatic heterocyclic structures such as thiethane, thiolane, and thian; and aliphatic heterocyclic structures containing multiple heteroatoms such as morpholine, 1,2-oxathiolane, and 1,3-oxathiolane.

[0042] Examples of the above aliphatic heterocyclic structures include lactone structures, cyclic carbonate structures, sultone structures, cyclic acetals, and cyclic ketones.

[0043] Examples of the above-mentioned aromatic heterocyclic structures having 5 to 20 carbon atoms include: oxygen-containing aromatic heterocyclic structures such as furan, pyran, benzofuran, and benzopyran; nitrogen-containing aromatic heterocyclic structures such as pyrrole, imidazole, pyridine, pyrimidine, pyrazine, indole, quinoline, isoquinoline, acridine, phenazine, and carbazole; sulfur-containing aromatic heterocyclic structures such as thiophene and benzothiophene; and aromatic heterocyclic structures containing multiple heteroatoms such as thiazole, benzothiazole, thiazine, and oxazine.

[0044] The above-mentioned fused ring group is preferably a crosslinked fused ring group. The crosslinked fused ring group preferably has an aliphatic polycyclic structure with crosslinks as its basic structure. The above-mentioned aliphatic polycyclic structure may have a bicyclic alicyclic structure (having one crosslink) or a tricyclic alicyclic structure (having two crosslinks). The number of crosslinks in the crosslinked fused ring group may be at least one, but may be two, three, four or more. Examples of atoms constituting the crosslinks include carbon atoms, oxygen atoms, sulfur atoms, etc. The number of atoms constituting the crosslinks is not particularly limited, but is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. The ring constituting the crosslinked fused ring group may be not only an aliphatic polycyclic structure with crosslinks, but also a fused ring of the aliphatic polycyclic structure and an aliphatic monocyclic structure without crosslinks, or a fused ring of the above-mentioned aliphatic polycyclic structure and an aromatic ring structure.

[0045] As the aliphatic polycyclic structure having the above-mentioned bridge, a structure in which two or more cycloalkanes having 4 to 8 carbon atoms form a fused ring with a bridge is preferred. The number of cycloalkanes is not limited to two, but may be three, four, five or more. For example, if there are three cycloalkanes a to c, and cycloalkane a and cycloalkane b form a fused ring, and cycloalkane b and cycloalkane c form a fused ring, the covalent atoms of cycloalkane a and cycloalkane b may form a bridge, the covalent atoms of cycloalkane b and cycloalkane c may form a bridge, or both sets of covalent atoms may form a bridge. Alternatively, one of the three cycloalkanes may form a fused ring with either of the remaining two cycloalkanes. In this case, it is sufficient that at least one set of the three sets of covalent atoms forms a bridge. Among these, norbornane and adamantane are preferred as the aliphatic polycyclic structure having the above-mentioned bridge.

[0046] The above-mentioned fused ring group preferably includes a lactone structure, a sultone structure, or a cyclic carbonate structure as the structure that provides the heteroatom. These heteroatom-containing ring structures preferably form a fused ring with the ring constituting the above-mentioned fused ring group.

[0047] When the above fused ring group has substituents, the substituents are preferably halogen atoms, hydroxyl groups, nitro groups, cyano groups, carboxyl groups, amino groups, sulfanyl groups, oxo groups (O=), or monovalent organic groups having 1 to 20 carbon atoms. If there are multiple substituents, it is preferable that two of the substituents be combined with each other to form a ring structure together with the constituent atoms of the ring to which they are bonded. Preferably, the substituents are halogen atoms, hydroxyl groups, cyano groups, carboxyl groups, amino groups, oxo groups (O=), or monovalent organic groups having 1 to 20 carbon atoms, and more preferably halogen atoms, cyano groups, carboxyl groups, oxo groups (O=), or monovalent organic groups having 1 to 20 carbon atoms.

[0048] As for the above substituent, a monovalent organic group having 1 to 20 carbon atoms is R ａA monovalent organic group having 1 to 20 carbon atoms, represented by the formula, can be suitably used. Examples of monovalent organic groups having 1 to 20 carbon atoms as substituents include -O-, -CO-, NR'-, -S-, and -SO ２ -Or a combination thereof is preferable. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Among these, alkyl groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, alkylcycloalkyloxycarbonyl groups, aralkyloxycarbonyl groups, and carboxyalkyl groups are preferred.

[0049] R is a ring structure formed when two of the multiple substituents are combined with each other and together with the constituent atoms of the ring to which they are bonded. ａ A group obtained by removing one hydrogen atom from a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, as shown above, can be suitably adopted.

[0050] W does not contain an ionic structure, from the viewpoint of dispersing compound (A) and suppressing excessive interactions with polymers, etc.

[0051] In the above formula (A), W is preferably a group represented by any of the following formulas (a1) to (a5). (In the above equations (a1) to (a5), X is independently -C(R) ｂ ) ２ - or -O-. R ｂ R is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. n is an integer from 0 to 6. If n is 2 or greater, multiple R ｃ and R ｅ They are either identical or different from each other. ｃ Each of these is independently a halogen atom, a hydroxyl group, a nitro group, a cyano group, a carboxyl group, an amino group, a sulfanyl group, or a monovalent organic group having 1 to 20 carbon atoms, or R ｃ If multiple R ｃ Two of them can be combined with each other to form a ring structure together with the constituent atoms of the ring they bond to. ｄ R is a monovalent organic group having 1 to 20 carbon atoms or a hydrogen atom. ｅis a halogen atom, nitro group, cyano group, carboxyl group, amino group, sulfanyl group, or a monovalent organic group having 1 to 20 carbon atoms, or R ｄ and R ｅ These atoms can be combined with each other to form a heterocyclic structure along with the constituent atoms of the ring they bond to. ｆ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. * represents the bond with L in formula (A) above.

[0052] R ｂ , R ｃ , R ｄ , R ｅ and R ｆ As a monovalent organic group having 1 to 20 carbon atoms, R ａ A monovalent organic group having 1 to 20 carbon atoms, represented by [the formula shown], can be suitably used.

[0053] R ｂ It is preferable that it be a hydrogen atom.

[0054] R ｃ As the monovalent organic group having 1 to 20 carbon atoms represented by , the monovalent organic group having 1 to 20 carbon atoms shown as the substituent above is preferred.

[0055] Multiple R ｃ Two of these are combined with each other, and together with the constituent atoms of the ring they bond to, the ring structure formed is R ａ Groups obtained by removing one hydrogen atom from a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, as shown above, or groups obtained by removing two hydrogen atoms from the above aliphatic heterocyclic structure having 3 to 20 carbon atoms, can be suitably adopted.

[0056] From the viewpoint of acid diffusion length and developer solubility, R ｚ If -F, R ｄ The alkyl group and alkoxycarbonyl group are preferred, R ｚ -CN, -SO ２ R ａ , -CF ２ H or -CF ３ In the case of R ｄ The elements are preferably hydrogen atoms, alkyl groups, and alkoxycarbonyl groups.

[0057] Rｄ and R ｅ As a heterocyclic structure formed when these elements are combined with each other and bonded together with the constituent atoms of the ring, a group obtained by removing two hydrogen atoms from the above-mentioned aliphatic heterocyclic structure having 3 to 20 carbon atoms can be suitably adopted.

[0058] R ｆ Preferably, the element is a hydrogen atom, an alkyl group, an alkylcycloalkyl group, or an aralkyl group.

[0059] n is preferably an integer between 0 and 4, more preferably an integer between 0 and 2, and even more preferably 0 or 1.

[0060] Specific examples of the anion of compound (A) include structures represented by the following formulas (1-1-1) to (1-1-105).

[0061]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069] Z ＋ The organic cation represented by is not particularly limited, and examples include onium cations containing elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi. Examples of onium cations include sulfonium cations, tetrahydrothiophenium cations, iodonium cations, phosphonium cations, diazonium cations, pyridinium cations, and ammonium cations.

[0070] Z ＋It is preferably a radiation-sensitive onium cation. Examples of the radiation-sensitive onium cation include a sulfonium cation, a tetrahydrothiophenium cation, an iodonium cation, etc. Among them, a radiation-sensitive sulfonium cation or a radiation-sensitive iodonium cation is preferable, and a radiation-sensitive sulfonium cation is more preferable.

[0071] The above organic cation preferably has at least one selected from the group consisting of an iodine group and a fluoro group. As a mode of containing an iodine group in the above organic cation, it preferably contains an iodine group-containing aromatic ring structure. The iodine group-containing aromatic ring structure is a structure in which part or all of the hydrogen atoms of the aromatic ring are substituted with iodine groups. In the organic cation, as a mode of containing a fluoro group, it is preferably in the form of a fluoro group-containing aromatic ring structure. The fluoro group-containing aromatic ring structure is a structure in which part or all of the hydrogen atoms of the aromatic ring are substituted with fluoro groups. As the aromatic ring in the iodine group-containing aromatic ring structure and the fluoro group-containing aromatic ring structure, the aromatic rings shown in the above condensed ring structure can be preferably adopted. By introducing an iodine group or a fluoro group, the radiation absorption efficiency can be increased, and thus the sensitivity can be improved.

[0072] The sulfonium cation or iodonium cation is preferably represented by the following formulas (X-1) to (X-6).

[0073]

[0074] In the above formula (X-1), R ａ１ , R ａ２ and R ａ３ are each independently a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyloxy group having 1 to 12 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, -OSO ２ -R Ｐ , -SO ２ -R Ｑ , -S-R ＴR represents a ring structure consisting of -O-, -CO-, or a combination thereof, or two or more of these groups combined with each other. This ring structure may contain heteroatoms such as O or S between the carbon-carbon bonds forming the skeleton. Ｐ , R Ｑ and R Ｔ Each of these is independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2, and k3 are each independently integers from 0 to 5. R ａ１ ~R ａ３ And R Ｐ , R Ｑ and R Ｔ If each of them is multiple, then multiple R ａ１ ~R ａ３ And R Ｐ , R Ｑ and R Ｔ These may be the same or different.

[0075] In the above equation (X-2), R ｂ１ This is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, an alkoxyalkyloxy group, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxyl group. ｋ n is either 0 or 1. ｋ When is 0, k4 is an integer from 0 to 4, and n ｋ When k4 is 1, k4 is an integer from 0 to 7. ｂ１ If there are multiple R ｂ１ They may be the same or different, and there may be multiple R's. ｂ１ R may represent a ring structure formed by combining with other elements. ｂ２ This is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. Ｃ k5 is a single bond or a divalent linking group. k5 is an integer from 0 to 4. ｂ２ If there are multiple R ｂ２They may be the same or different, and there may be multiple R's. ｂ２ may represent a ring structure formed by combining with each other. q is an integer from 0 to 3. In the formula, S ＋ The ring structure containing may include heteroatoms such as O and S between the carbon-carbon bonds that form the skeleton.

[0076] In the above equation (X-3), R ｃ１ , R ｃ２ and R ｃ３ Each of these is independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms.

[0077] In the above equation (X-4), R ｇ１ This is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxyl group. ｋ２ n is either 0 or 1. ｋ２ When is 0, k10 is an integer from 0 to 4, and n ｋ２ When is 1, k10 is an integer from 0 to 7. ｇ１ If there are multiple R ｇ１ They may be the same or different, and there may be multiple R's. ｇ１ R may represent a ring structure formed by combining with other elements. ｇ２ and R ｇ３ Each of these independently represents a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyloxy group having 1 to 12 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group, hydroxyl group, halogen atom having 6 to 12 carbon atoms, or a ring structure formed by combining these groups. k11 and k12 are each independently integers from 0 to 4. R ｇ２ and R ｇ３ If each of them is multiple, then multiple R ｇ２ and R ｇ３ These may be the same or different.

[0078] In the above equation (X-5), R ｄ１and R ｄ２ Each of these independently represents a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or alkoxycarbonyl group, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a halogen atom, a halogenated alkyl group having 1 to 4 carbon atoms, a nitro group, or a ring structure formed by two or more of these groups combined. k6 and k7 are each independently integers from 0 to 5. R ｄ１ and R ｄ２ If each of them is multiple, then multiple R ｄ１ and R ｄ２ These may be the same or different.

[0079] In the above formula (X-6), R ｅ１ and R ｅ２ k8 and k9 are each independently a halogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms.

[0080] Specific examples of organic cations as the above-mentioned radiation-sensitive onium cations include, but are not limited to, the structures shown in formulas (1-2-1) to (1-2-55) and (1-3-1) to (1-3-21) below.

[0081]

[0082]

[0083]

[0084]

[0085] Compound (A) can be obtained by appropriately combining the above-mentioned anion and the above-mentioned organic cation (the anion and organic cation are not limited to the structures specifically shown). Specific examples, though not particularly limited, include structures of formulas (1-1) to (1-84) below.

[0086]

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094] Compound (A) may be used alone or in combination of two or more types. The lower limit of the content of compound (A) (total in the case of multiple types) is preferably 0.1 parts by mass, more preferably 1 part by mass, even more preferably 3 parts by mass, and particularly preferably 6 parts by mass, per 100 parts by mass of the base polymer described later. The upper limit of the above content is preferably 60 parts by mass, more preferably 55 parts by mass, even more preferably 50 parts by mass, and particularly preferably 45 parts by mass. This allows for the excellent resist properties described above to be exhibited.

[0095] <Method of Synthesis of Compound (A)> It is clear that compound (A) can be synthesized based on the description in the examples and common technical knowledge. As a representative example, in the above formula (A), L is a single bond and Y is -O-, it can be synthesized by the following scheme.

[0096] (In the scheme, R ｚ , R １ , W and Z ＋ This is equivalent to the above formula (A). E １ E is a halogen atom. - (This is a halide ion.)

[0097] A halogenated carboxylic acid ester having a structure near a predetermined sulfonic acid anion is subsequently reacted with sodium dithionite and hydrogen peroxide to introduce a sulfonic acid group, and an onium salt is produced through salt exchange with the halogenated product of the target organic cation. A carboxylic acid is generated with alkali, and finally, the target compound (1) can be synthesized by esterification with a compound having a predetermined fused ring group. Other structures can also be synthesized by appropriately selecting the starting materials and reaction substrates.

[0098] <Polymers> A polymer (i.e., a base polymer) is an aggregate of polymer chains having structural units containing acid-dissociable groups (hereinafter also referred to as "structural unit (I)"). In addition to structural unit (I), the base polymer may also contain structural units having phenolic hydroxyl groups (hereinafter also referred to as "structural unit (II)"), lactone structures, cyclic carbonate structures, and sultone structures (hereinafter also referred to as "structural unit (III)"). Each structural unit will be described below.

[0099] [Structural Unit (I)] Structural unit (I) is a structural unit having an acid-dissociable group. An "acid-dissociable group" is a hydrogen atom-substituting group such as a carboxyl group, phenolic hydroxyl group, alcoholic hydroxyl group, or sulfo group that dissociates upon the action of an acid. The radiation-sensitive composition exhibits excellent pattern-forming properties because the polymer has structural unit (I).

[0100] Structural unit (I) is not particularly limited as long as it has an acid-dissociable group. Examples include structural units having a tertiary alkyl ester moiety, structural units having a structure in which an aromatic group and an aliphatic group are bonded to the secondary carbon constituting the secondary alkyl ester moiety, structural units having a structure in which the hydrogen atom of a phenolic hydroxyl group is substituted with a tertiary alkyl group, and structural units having an acetal bond. However, from the viewpoint of improving the pattern-forming properties of the radiation-sensitive composition, a structural unit represented by the following formula (3) (hereinafter also referred to as "structural unit (I-1)") is preferred.

[0101]

[0102] In the above formula (3), R １７ R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １８ R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １９ and R ２０ Each of these independently represents a substituted or unsubstituted monovalent chain hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms formed by combining these groups with the carbon atoms to which they are bonded. １１ teeth, ＊ -COO-, ＊ -L １１ａ COO- or ＊ -COOL １１ａ Represents COO-. １１ａ * is a substituted or unsubstituted alkanediyl group or arenediyl group. １７ This is the bonding site with the carbon atom to which it is bonded.

[0103] The above R １７ From the viewpoint of copolymerization of the monomer that gives the structural unit (I-1), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0104] L １１ａ Examples of alkanediyl groups represented by include methylene groups, ethanediyl groups, 1,3-propanediyl groups, and 2,2-propanediyl groups, which have 1 to 10 carbon atoms. １１ａ Methylene groups and ethanediyl groups are preferred as the base group.

[0105] L １１ａ Examples of the arenediyl group represented by include divalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, such as benzenediyl groups and naphthalenediyl groups. １１ａ A benzenediyl group is preferred as the group.

[0106] L １１ａ As substituents that the arenediyl group represented by can have, substituents that the above-mentioned fused ring group can have can be suitably adopted.

[0107] The above R １８As the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by , the monovalent hydrocarbon group having 1 to 20 carbon atoms shown as a substituent of the above-mentioned fused ring group can be suitably adopted.

[0108] The above R １８ Preferably, the hydrocarbon group is a straight-chain or branched-chain saturated hydrocarbon group having 1 to 10 carbon atoms, or an alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0109] The above R １９ and R ２０ The divalent alicyclic group having 3 to 20 carbon atoms, which is formed by combining these atoms with the carbon atoms to which they are bonded, can preferably be a group obtained by removing one hydrogen atom from the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms shown as a substituent of the above-mentioned fused ring group.

[0110] Among these, R １８ R is an alkyl group, alkenyl group, or phenyl group having 1 to 4 carbon atoms. １９ and R ２０ It is preferable that the alicyclic structure formed by combining these elements with the carbon atoms to which they are bonded is a polycyclic or monocyclic cycloalkane structure.

[0111] The above R １８ ~R ２０ The substituents that can be present are L １１ａ The substituents that the arenediyl group represented by can have can be suitably adopted.

[0112] Examples of structural units (I-1) include those represented by the following formulas (3-1) to (3-15) (hereinafter also referred to as "structural units (I-1-1) to (I-1-15)").

[0113]

[0114]

[0115] In the above equations (3-1) to (3-15), R １７ ~R ２０ This is equivalent to equation (3) above. R Ｌ１１R is a halogen atom, hydroxyl group, carboxyl group, cyano group, nitro group, alkyl group, fluorinated alkyl group, alkoxycarbonyloxy group, acyl group, acyloxy group, or alkoxy group. i and j are each independently integers from 1 to 4. k and l are 0 or 1. 3a are each independently integers from 0 to 3. If 3a is 2 or more, multiple R Ｌ１１ They are either identical or different from each other. a4 is an integer between 1 and 3.

[0116] i and j are preferably 1 or 2. １８ Preferred groups include methyl, ethyl, isopropyl, t-butyl, cyclopentyl, ethenyl, phenyl, and iodophenyl groups. １９ and R ２０ Preferably, the group is a methyl group, an ethyl group, or an isopropyl group. Ｌ１１ By employing an iodine atom, an iodine group can be suitably introduced into the structural unit (I).

[0117] Furthermore, the polymer may contain structural units (I) represented by the following formulas (1f) to (2f).

[0118]

[0119] In the above equations (1f) to (2f), R αｆ Each of these is independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. βｆ Each of these is independently a hydrogen atom or a chain alkyl group having 1 to 5 carbon atoms. １ is an integer between 1 and 4.

[0120] The above R βｆ Preferably, the element is a hydrogen atom, a methyl group, or an ethyl group. H1 is preferably 1 or 2.

[0121] The lower limit of the content of structural unit (I) (total content if multiple types are included) is preferably 10 mol%, more preferably 20 mol%, and even more preferably 30 mol%, relative to the total structural units constituting the base polymer. The upper limit of the above content is preferably 90 mol%, more preferably 80 mol%, and even more preferably 70 mol%. By setting the content of structural unit (I) within the above range, the pattern-forming properties of the radiation-sensitive composition can be further improved.

[0122] [Structural Unit (II)] Structural unit (II) is a structural unit having a phenolic hydroxyl group. Structural unit (II) contributes to improved etching resistance and improved difference in developer solubility between exposed and unexposed areas (dissolution contrast). It can be suitably applied to pattern formation using exposure with radiation of wavelength 50 nm or less, such as KrF excimer lasers, electron beams, and EUV.

[0123] The structural unit having a phenolic hydroxyl group is preferably represented by the following formula (4).

[0124] (In the above formula (4), R β L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ＣＡ This is a single bond, -COO- ＊ Or -O-. * indicates a bond on the aromatic ring side. R １０２ R is a halogen atom, cyano group, nitro group, alkyl group, alkoxy group, alkoxycarbonyl group, acyl group, or acyloxy group. １０２ If multiple R １０２ They are either identical or different from each other. ３ m is an integer between 0 and 2. ３ m is an integer from 1 to 8. ４ m is an integer between 0 and 8, where 1 ≤ m ３ +m ４ ≤ 2n ３ (Saves +5.)

[0125] The above R β From the viewpoint of copolymerization of the monomer that gives structural unit (II), it is preferable that it be a hydrogen atom or a methyl group.

[0126] L ＣＡ For example, a single bond or -COO- ＊ It is preferable.

[0127] R １０２ In this mixture, fluorine or iodine atoms are preferred as halogen atoms.

[0128] The above n ３ 0 or 1 is more preferable, and 0 is even more preferable.

[0129] The above m ３ Preferably, the integer is between 1 and 3, and more preferably 1 or 2.

[0130] The above m ４ Preferably, the integer is between 0 and 3, and more preferably between 0 and 2.

[0131] When obtaining structural unit (II), the phenolic hydroxyl group of the corresponding monomer may be protected with a protecting group such as an alkali-dissociable group (e.g., an acyl group) during polymerization, and then deprotected by hydrolysis to obtain structural unit (II). Alternatively, the monomer may be polymerized without protecting the phenolic hydroxyl group.

[0132] When the base polymer contains structural unit (II), the lower limit of the content of structural unit (II) in relation to the total structural units constituting the base polymer (the total content if multiple types are included) is preferably 10 mol%, and more preferably 20 mol%. The upper limit of the above content is preferably 70 mol%, and more preferably 60 mol%.

[0133] [Structural Unit (III)] Structural unit (III) is a structural unit comprising at least one selected from the group consisting of lactone structures, cyclic carbonate structures, and sultone structures. By further comprising structural unit (III), the solubility of the base polymer in the developer can be adjusted, and as a result, the radiation-sensitive composition can improve lithography performance such as resolution. Furthermore, the adhesion between the resist pattern formed from the base polymer and the substrate can be improved.

[0134] Examples of structural units (III) include those represented by the following formulas (T-1) to (T-11).

[0135]

[0136] In the above formula, R Ｌ１ R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｌ２ ~R Ｌ５ These are, independently, a hydrogen atom, a C1-C4 alkyl group, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxyl group, a hydroxymethyl group, and a dimethylamino group. Ｌ４ and R Ｌ５ These may be divalent alicyclic groups having 3 to 8 carbon atoms, which can be combined with each other and bonded together with the carbon atoms. ２ is a single bond or a divalent linking group. X is an oxygen atom or a methylene group. k is an integer from 0 to 3. m is an integer from 1 to 3.

[0137] The above R Ｌ４ and R Ｌ５ When these are combined with each other, the divalent alicyclic group having 3 to 8 carbon atoms, formed together with the carbon atoms to which they are bonded, is R in formula (3) above. １９ and R ２０ Examples include divalent alicyclic groups with 3 to 20 carbon atoms, where these groups are combined with each other and formed together with the carbon atoms to which they are bonded, specifically groups with 3 to 8 carbon atoms. One or more hydrogen atoms on these alicyclic groups may be substituted with hydroxyl groups.

[0138] The above L ２ Examples of divalent linking groups represented by include divalent linear or branched hydrocarbon groups having 1 to 10 carbon atoms, divalent alicyclic hydrocarbon groups having 4 to 12 carbon atoms, or groups composed of one or more of these hydrocarbon groups and at least one of the groups -CO-, -O-, -NH-, and -S-.

[0139] Among these, structural units (III) are preferably those containing a lactone structure, more preferably those containing a γ-butyrolactone structure or a norbornane lactone structure, and even more preferably those derived from γ-butyrolactone-yl-(meth)acrylate or norbornane lactone-yl(meth)acrylate.

[0140] When the base polymer contains structural unit (III), the lower limit of the content of structural unit (III) in the total structural units constituting the base polymer (the total content if multiple types are included) is preferably 5 mol%, more preferably 15 mol%, and even more preferably 25 mol%. The upper limit of the content is preferably 90 mol%, more preferably 80 mol%, and even more preferably 75 mol%. By setting the content of structural unit (III) within the above range, the radiation-sensitive composition can further improve lithography performance such as resolution and the adhesion of the formed resist pattern to the substrate.

[0141] [Structural Unit (IV)] The base polymer may have structural unit (IV) containing a polar group (excluding those corresponding to structural units (I) to (III)). By further having structural unit (IV), the solubility of the base polymer in the developer can be adjusted, and as a result, the lithographic performance such as resolution of the radiation-sensitive composition can be improved. Examples of the above polar group include a hydroxyl group, a carboxyl group, a cyano group, a nitro group, a sulfonamide group, etc. Among these, a hydroxyl group and a carboxyl group are preferred, and a hydroxyl group is more preferred.

[0142] Examples of structural units (IV) include structural units represented by the following formula.

[0143]

[0144]

[0145] In the above formula, R Ｋ This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0146] When the base polymer has a structural unit (IV) having the polar group, the lower limit of the content of the structural unit (IV) in the total structural units constituting the base polymer (the total content if multiple types are included) is preferably 1 mol%, more preferably 3 mol%, and even more preferably 5 mol%. The upper limit of the content is preferably 40 mol%, more preferably 30 mol%, and even more preferably 20 mol%. By setting the content of structural unit (IV) within the above range, the lithographic performance, such as resolution, of the radiation-sensitive composition can be further improved.

[0147] [Structural Unit (V)] The base polymer may have a structural unit (V) that includes a first acid-generating structure. The first acid-generating structure has a first organic acid anion and a first onium cation, and generates an acid that dissociates the acid-dissociable group upon exposure. The onium salt structure formed by the first organic acid anion and the first onium cation (i.e., the first acid-generating structure) functions as a radiation-sensitive acid-generating structure. By containing the above radiation-sensitive acid-generating structure in the base polymer, the polarity of the base polymer in the exposed area increases, making it soluble in the developer in the case of alkaline aqueous solution development, while it becomes sparingly soluble in the developer in the case of organic solvent development.

[0148] Although the form in which the first organic acid anion and the first onium cation are contained in the structural unit (V) of the base polymer is not particularly limited, it is preferable that the base polymer has the first organic acid anion as a side chain portion from the viewpoint of controlling the acid diffusion length. Having it as a side chain portion means that the first organic acid anion is bonded (covalently bonded) to the main chain as a side chain structure of the base polymer.

[0149] The above-mentioned first organic acid anion preferably has at least one selected from the group consisting of sulfonic acid anions, carboxylic acid anions, and sulfonimide anions as the acid anion portion. As for the acid generated by exposure, sulfonic acid, carboxylic acid, and sulfonimide can be cited, corresponding to the above-mentioned acid anion portion.

[0150] The above-mentioned first organic acid anion can suitably employ structures other than the acid anion portion, such as a ring structure or a structure combining at least one of a ring structure or a chain structure with a divalent heteroatom-containing linking group.

[0151] As for the ring structure, the alicyclic hydrocarbon structure having 3 to 20 carbon atoms, the aromatic hydrocarbon structure having 6 to 20 carbon atoms, the aliphatic heterocyclic structure having 3 to 20 carbon atoms, or the aromatic heterocyclic structure having 5 to 20 carbon atoms, or a combination thereof, as shown in the above-mentioned fused ring group, can be suitably adopted.

[0152] As the chain-like structure, the substituted or unsubstituted alkanediyl group shown in L of formula (A) above can be suitably adopted.

[0153] In the above-described first acid generation structure, the first organic acid anion preferably has a sulfonic acid anion as the acid anion portion, and an electron-withdrawing group is preferably bonded to the carbon atom at the α or β position of the sulfur atom in the sulfonic acid anion. This allows the first acid generation structure to efficiently exhibit the above-described function. Examples of electron-withdrawing groups include fluorine atoms, fluorinated hydrocarbon groups, nitro groups, and cyano groups. As the fluorinated hydrocarbon group, a perfluoroalkyl group having 1 to 5 carbon atoms is preferred.

[0154] The first organic acid anion described above preferably has an iodine group. The first organic acid anion preferably contains the iodine group-containing aromatic ring structure described above as the form in which the iodine group is contained.

[0155] Examples of the first onium cation mentioned above include radiation-sensitive onium cations. Examples of radiation-sensitive onium cations include sulfonium cations, tetrahydrothiophenium cations, and iodonium cations. Among these, sulfonium cations or iodonium cations are preferred, and sulfonium cations are more preferred.

[0156] The first onium cation described above preferably has an iodine group or a fluoro group. The first onium cation preferably contains an iodine group-containing aromatic ring structure as an iodine group-containing configuration. The first onium cation preferably contains a fluoro group-containing aromatic ring structure as an fluoro group-containing configuration. These configurations increase radiation absorption efficiency, thereby improving sensitivity.

[0157] The structural unit (V) can efficiently perform the above-mentioned functions by combining the above-mentioned structures.

[0158] The structural unit (V) is preferably a structural unit represented by the following formula (a1) (hereinafter also referred to as "structural unit (V-1)").

[0159]

[0160] In the formula, R Ｖ This is a hydrogen atom or a methyl group. V １ This is a single bond or an ester group. V ２ This is a linear, branched, or cyclic alkylene group having 1 to 12 carbon atoms, a cycloalkylene group having 3 to 12 carbon atoms, or an arylene group having 6 to 10 carbon atoms, or a combination thereof, or an amide bond, and a portion of the methylene groups constituting the alkylene group, the cycloalkylene group, or the arylene group may be substituted with an ether group, an ester group, or a lactone ring-containing group. ３ This is a single bond, an ether group, an ester group, or a linear or branched alkylene group having 1 to 12 carbon atoms, or a cyclic cycloalkylene group having 3 to 12 carbon atoms, and a portion of the methylene groups constituting the alkylene group may be substituted with an ether group or an ester group. ２ and V ３ Some or all of the hydrogen atoms in the compound may be substituted with heteroatoms, or with monovalent hydrocarbon groups having 1 to 20 carbon atoms that may contain heteroatoms. Rf １ ~Rf ２ Each of these is independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one is a fluorine atom or a fluorinated hydrocarbon group. kk is an integer from 1 to 4. X１ ＋ This is a sulfonium cation or an iodonium cation.

[0161] V ２ and V ３ The C1-C20 monovalent hydrocarbon group in this is preferably a C1-C12 alkyl group, a C3-C12 cycloalkyl group, or a C6-C20 aryl group. Some or all of the hydrogen atoms in these groups may be substituted with heteroatom-containing groups such as hydroxyl groups, carboxyl groups, halogen atoms, oxo groups, cyano groups, amide groups, nitro groups, sultone groups, sulfone groups, or sulfonium salt-containing groups, alkoxy groups, or alkoxycarbonyl groups. Some of the methylene groups constituting these groups may be substituted with ether groups, ester groups, carbonyl groups, carbonate groups, or sulfonic acid ester groups.

[0162] Preferably, the structural unit (V-1) is a structural unit represented by the following formula (a1-1).

[0163]

[0164] In the formula, R Ｖ , Rf １ ~Rf ２ , V １ ,kk and X １ ＋ This is equivalent to the above formula (a1). R ４８ m is a linear, branched, or cyclic alkyl group having 1 to 4 carbon atoms, a halogen atom other than iodine, a hydroxyl group, a linear, branched, or cyclic alkoxy group having 1 to 4 carbon atoms, or a linear, branched, or cyclic alkoxycarbonyl group having 2 to 5 carbon atoms. m is an integer from 0 to 4. n is an integer from 0 to 3.

[0165] Examples of the first organic acid anion of the monomer that gives structural unit (V) (including structural unit (V-1)) include, but are not limited to, the structure shown in the following formula. In the following, the iodine group of the iodine group-containing aromatic ring structure may be substituted with a hydrogen atom or a substituent that the above-mentioned fused ring group may have. In the following formula, R Ｖ This is synonymous with the above.

[0166]

[0167]

[0168]

[0169]

[0170]

[0171] In the above formula, R Ｖ This is equivalent to equation (a1) above.

[0172] X in the above formula (a1) １ ＋ As for Z in the above formula (A) ＋ A sulfonium cation or an iodonium cation can be suitably used in the organic cation represented by [the formula].

[0173] When the base polymer has structural units (V), the lower limit of the content of structural units (V) (total content if multiple types are included) is preferably 1 mol%, and more preferably 3 mol%, relative to the total structural units constituting the base polymer. The upper limit of the above content is preferably 20 mol%, and more preferably 10 mol%. By setting the content of structural units (V) within the above range, the function as an acid-generating structure can be fully exhibited, and the above resist properties can be achieved.

[0174] [Structural Unit (VI)] The base polymer may include structural unit (VI), which has a second organic acid anion and a second onium cation, and contains a second acid generation structure that generates an acid by exposure without dissociating the acid-dissociable group. The onium salt structure formed by the second organic acid anion and the second onium cation (i.e., the second acid generation structure) functions as an acid diffusion control structure. Specifically, under pattern formation conditions using the above radiation-sensitive composition, the second acid generation structure substantially prevents the dissociation of the acid-dissociable group of structural unit (I), and has the function of suppressing the diffusion of acid generated from compound (A) or structural unit (V) (if included) in the unexposed area by salt exchange. The acid generated from the second acid generation structure can be said to be a relatively weaker acid (an acid with a high pKa) than the acid generated from compound (A) or structural unit (V). Whether an onium salt structure functions as a radiation-sensitive acid-generating structure or an acid-diffusion-controlling structure depends on the energy required to dissociate the acid-dissociable groups of the base polymer, and the acidity of the onium salt structure or the generated acid.

[0175] Regarding the inclusion of the second organic acid anion and the second onium cation in the structural unit (VI) of the base polymer, from the viewpoint of development contrast, it is preferable that the base polymer has the second organic acid anion as a side chain portion. Having it as a side chain portion means that the corresponding second organic acid anion is bonded (covalently bonded) to the main chain as a side chain structure of the base polymer.

[0176] The above-mentioned second organic acid anion preferably has a sulfonic acid anion or a carboxylic acid anion as the acid anion portion, and more preferably a carboxylic acid anion. However, when the above-mentioned second organic acid anion has the above-mentioned sulfonic acid anion, no electron-withdrawing group is bonded to either the α-position or the β-position carbon atom of the sulfur atom in the sulfonic acid anion. Examples of electron-withdrawing groups include fluorine atoms, fluorinated hydrocarbon groups, nitro groups, cyano groups, etc. The acid generated by exposure corresponds to the above-mentioned acid anion portion and is a carboxylic acid or sulfonic acid.

[0177] The above-mentioned second organic acid anion can preferably employ the structure shown as the structure other than the acid anion portion of structural unit (V).

[0178] The above-mentioned second organic acid anion preferably has an iodine group or a hydroxyl group. The above-mentioned second organic acid anion preferably contains the above-mentioned iodine group-containing aromatic ring structure as the form in which the iodine group is contained.

[0179] As the second onium cation mentioned above, the organic cation of compound (A) can be suitably used.

[0180] The above-mentioned second onium cation preferably has an iodine group. The above-mentioned second onium cation preferably contains the above-mentioned iodine group-containing aromatic ring structure as the form in which the iodine group is contained.

[0181] The secondary onium cation in structural unit (VI) preferably has the above-mentioned fluorogroup-containing aromatic ring structure. This can improve sensitivity by increasing the radiation absorption efficiency.

[0182] The structural unit (VI) can efficiently perform the above-mentioned functions by combining the above-mentioned structures.

[0183] The structural unit (VI) is preferably a structural unit represented by the following formula (p1) (hereinafter also referred to as "structural unit (VI-1)").

[0184]

[0185] In formula (p1), R A This is either a hydrogen atom or a methyl group.

[0186] In formula (p1), X 1 These are single bonds, ester bonds, ether bonds, phenylene groups, naphthylene groups, or combinations thereof.

[0187] In formula (p1), X ２ This is a single bond, a saturated hydrocarbylene group having 1 to 12 carbon atoms, or a phenylene group, and the saturated hydrocarbylene group may include an ether bond, an ester bond, an amide bond, a lactone ring, or a sultone ring.２ The hydrocarbylene group represented by can be linear, branched, or cyclic, and specific examples include methylene group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,2-diyl group, propane-1,3-diyl group, propane-2,2-diyl group, butane-1,2-diyl group, butane-1,3-diyl group, butane-1,4-diyl group, butane-2,2-diyl group, butane-2,3-diyl group, 2-methylpropane-1,3- Examples include C1-C12 alkanediyl groups such as diyl groups, pentane-1,5-diyl groups, hexane-1,6-diyl groups, heptane-1,7-diyl groups, octane-1,8-diyl groups, nonane-1,9-diyl groups, and decane-1,10-diyl groups; C3-C12 cyclic saturated hydrocarbylene groups such as cyclopentanediyl groups, cyclohexanediyl groups, norbornanediyl groups, and adamantanediyl groups; and groups obtained by combining these.

[0188] In formula (p1), X 3 These are single bonds, ester bonds, or ether bonds.

[0189] In formula (p1), X 1 ~X ２ Some or all of the hydrogen atoms in the group may be substituted with substituents. Preferably, substituents that the fused ring group may have can be used. 1 ~X ２ If the compound has a phenylene group, it is preferable that some or all of the hydrogen atoms of the phenylene group are substituted with fluorine atoms or iodine atoms.

[0190] In formula (p1), R ｘ These are halogen atoms; hydroxyl groups; carboxyl groups; cyano groups; nitro groups; alkyl groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, acyloxy groups, or groups in which the hydrogen atoms of these groups are substituted with halogen atoms.

[0191] In formula (p1), Z ２ ＋ This is a secondary onium cation. As the secondary onium cation, the organic cation shown in compound (A) can be suitably used.

[0192] Examples of the second organic acid anion of the monomer that gives structural unit (VI) (including structural unit (VI-1)) are, but are not limited to, those listed below. In the following formulas, the iodine group or hydroxyl group may be substituted with a hydrogen atom or a substituent that the above-mentioned fused ring group may have. In the following formulas, R Ａ The same applies as described above. It is preferable that the second organic acid anion has a carboxylate anion and a hydroxyl group. In this case, it is preferable that the carboxylate anion and the hydroxyl group are bonded to the same aromatic ring in the second organic acid anion, and it is more preferable that the carbon atom to which the carboxylate anion is bonded and the carbon atom to which the hydroxyl group is bonded are directly connected to each other on the same aromatic ring.

[0193]

[0194]

[0195]

[0196] When the base polymer contains structural unit (VI), the lower limit of the content of structural unit (VI) (or the total content if multiple types are included) is preferably 2 mol%, more preferably 5 mol%, and even more preferably 8 mol%, relative to the total structural units constituting the base polymer. The upper limit of the above content is preferably 20 mol%, more preferably 16 mol%, and even more preferably 12 mol%. By setting the content of structural unit (VI) within the above range, the structure can fully exhibit its function as an acid diffusion control structure.

[0197] [Other structural units] The base polymer may also contain structural units other than those listed above, such as structural units having an alicyclic structure represented by the following formula (6) (hereinafter also referred to as "structural unit (VII)"). (In the above formula (6), R １α R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２α (It is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.)

[0198] In the above formula (6), R ２αAs the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by , the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms shown as a substituent of the above-mentioned fused ring group can be suitably adopted.

[0199] When the base polymer contains structural unit (VII), the lower limit of the content of structural unit (VII) is preferably 2 mol%, more preferably 5 mol%, and even more preferably 8 mol%, relative to the total structural units constituting the base polymer. The upper limit of the above content is preferably 30 mol%, more preferably 20 mol%, and even more preferably 15 mol%.

[0200] (Method for synthesizing base polymers) Base polymers can be synthesized, for example, by polymerizing monomers that give each structural unit in a suitable solvent using a radical polymerization initiator or the like.

[0201] Examples of the radical polymerization initiators mentioned above include azo-based radical initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(isobutyrate)dimethyl (MAIB), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl 2,2'-azobisisobutyrate; and peroxide-based radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred. These radical initiators can be used individually or in combination of two or more.

[0202] Solvents used in the above polymerization include, for example, alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, and norbornane; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene; halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, and chlorobenzene; saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, isobutyl acetate, and methyl propionate; polyhydric alcohol partial ether acetate solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; and ketones such as acetone, 2-butanone, 4-methyl-2-pentanone, 2-heptanone, and cyclohexanone. Examples include linear ethers such as dimethoxyethanes and diethoxyethanes; cyclic ethers such as tetrahydrofurans and 1,4-dioxanes; polyhydric alcohol partial ethers such as 1-methoxy-2-propanol (propylene glycol monomethyl ether); alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol; and lactones such as γ-butyrolactone. The solvents used in these polymerizations may be used alone or in combination of two or more.

[0203] The reaction temperature in the polymerization described above is usually 40°C to 150°C, with 50°C to 120°C being preferred. The reaction time is usually 1 hour to 48 hours, with 1 hour to 24 hours being preferred.

[0204] The molecular weight of the base polymer is not particularly limited, but the lower limit of the polystyrene-equivalent weight-average molecular weight (Mw) determined by gel permeation chromatography (GPC) is preferably 1,500, more preferably 3,000, and even more preferably 4,500. The upper limit of Mw is preferably 20,000, more preferably 14,000, and even more preferably 10,000. By keeping the Mw of the base polymer within the above range, good heat resistance and developability can be obtained in the resulting resist film.

[0205] The ratio of Mw to the polystyrene-equivalent number-average molecular weight (Mn) of the base polymer (Mw / Mn) determined by GPC is usually between 1 and 5, preferably between 1 and 3, and more preferably between 1 and 2.

[0206] In this specification, the Mw and Mn values ​​of polymers are measured using gel permeation chromatography (GPC) under the following conditions.

[0207] GPC columns: 2 x G2000HXL, 1 x G3000HXL, 1 x G4000HXL (all manufactured by Tosoh) Column temperature: 40°C Elution solvent: Tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0208] The base polymer content is preferably 40% by mass or more, and more preferably 50% by mass or more, relative to the total solid content of the radiation-sensitive composition.

[0209] <Other Polymers> The radiation-sensitive composition of this embodiment may also contain a second polymer different from the base polymer as another polymer. Preferably, the second polymer has a higher mass content of fluorine atoms or a higher content of aliphatic hydrocarbon groups (lower content of heteroatoms) than the base polymer. When the radiation-sensitive composition contains the second polymer, it can be unevenly distributed on the surface of the resist film relative to the base polymer, and as a result, the water repellency of the surface of the resist film during immersion exposure can be improved, and the surface modification of the resist film and the distribution of the composition within the film can be controlled during EUV exposure.

[0210] The second polymer may have, for example, a structural unit represented by the following formula (5) (hereinafter also referred to as "structural unit (VIII)").

[0211]

[0212] In the above formula (5), R １３ This is a hydrogen atom, a methyl group, or a trifluoromethyl group. ＬIt consists of a single bond, an alkanediyl group with 1 to 5 carbon atoms, an oxygen atom, a sulfur atom, -COO-, and -SO ２ ONH-, -CONH-, -OCONH-, or a combination thereof. １４ This is a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0213] The above R １３ From the viewpoint of copolymerization of monomers that give structural unit (VIII), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0214] The above G Ｌ From the viewpoint of copolymerization of monomers that give structural unit (VIII), single bonds and -COO- are preferred, and -COO- is more preferred.

[0215] The above R １４ Examples of monovalent fluorinated linear hydrocarbon groups having 1 to 20 carbon atoms, represented by , include those in which some or all of the hydrogen atoms in a linear or branched alkyl group having 1 to 20 carbon atoms are substituted with fluorine atoms.

[0216] The above R １４ Examples of monovalent fluorinated alicyclic hydrocarbon groups having 3 to 20 carbon atoms, represented by , include those in which some or all of the hydrogen atoms in a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms are substituted with fluorine atoms.

[0217] The above R １４ Preferably, the group is a fluorinated chain hydrocarbon group, more preferably a fluorinated alkyl group, and even more preferably a 2,2,2-trifluoroethyl group, a 2,2,3,3,3-pentafluoropropyl group, a 1,1,1,3,3,3-hexafluoropropyl-2-yl group, and a 5,5,5-trifluoro-1,1-diethylpentyl group.

[0218] When the second polymer has structural unit (VIII), the lower limit of the content of structural unit (VIII) is preferably 30 mol%, more preferably 40 mol%, and even more preferably 50 mol%, relative to the total structural units constituting the second polymer. The upper limit of the above content is preferably 90 mol%, more preferably 80 mol%, and even more preferably 70 mol%. By setting the content of structural unit (VIII) within the above range, the water repellency of the second polymer can be more appropriately adjusted, further promoting the uneven distribution of the resist film on the surface, and as a result, the film quality controllability of the resist film can be further improved.

[0219] The second polymer may have a fluorine atom-containing structural unit (hereinafter also referred to as structural unit (IX)) represented by the following formula (f-2), either together with structural unit (VIII) or in place of structural unit (VIII). By having structural unit (IX), the second polymer's solubility in alkaline developer is improved, and the occurrence of development defects can be suppressed.

[0220]

[0221] Structural units (IX) can be broadly classified into two types: (x) those having an alkali-soluble group, and (y) those having a group that dissociates under the action of alkali, increasing its solubility in alkaline developer (hereinafter also simply referred to as an "alkali-dissociable group"). In both (x) and (y), in the above formula (f-2), R Ｃ R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｄ R is a single bond, a (s+1) valent hydrocarbon group with 1 to 20 carbon atoms, and this hydrocarbon group Ｅ At the end of the side are an oxygen atom, a sulfur atom, and -NR ｄｄ -A structure to which a carbonyl group, -COO-, -OCO-, or -CONH- is bonded, or a structure in which some of the hydrogen atoms of this hydrocarbon group are substituted by an organic group having a heteroatom. ｄｄ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer from 1 to 3.

[0222] If the structural unit (IX) has (x) an alkali-soluble group, R Ｆ A is a hydrogen atom, １The oxygen atom is -COO-* or -SO ２ It is O-*. * is R Ｆ This indicates the binding site. １ This is a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group. １ If is an oxygen atom, W １ is A １ It is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group at the carbon atom to which it is bonded. Ｅ is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, multiple R Ｅ , W １ A １ and R Ｆ These may be the same or different. Having an alkali-soluble group (x) in the structural unit (IX) increases its affinity for alkaline developer and suppresses development defects. A is an example of a structural unit (IX) having an alkali-soluble group. １ is an oxygen atom and W １ It is particularly preferable that the group is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.

[0223] If the structural unit (IX) has an alkali-dissociable group (y), R Ｆ A is a monovalent organic group having 1 to 30 carbon atoms. １ is an oxygen atom, -NR ａａ -, -COO-*, -OCO-*, or -SO ２ It is O-*. ａａ * is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Ｆ This indicates the binding site. １ R is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. Ｅ A is a single bond or a divalent organic group having 1 to 20 carbon atoms. １ -COO-*, -OCO-*, or -SO ２ If it is O-*, then W １ or R Ｆ is A １ It has a fluorine atom on the carbon atom bonded to it or on an adjacent carbon atom. １ If is an oxygen atom, W １, R Ｅ It is a single bond, R Ｄ R is a hydrocarbon group having 1 to 20 carbon atoms. Ｅ It is a structure in which a carbonyl group is bonded to the terminal end, R Ｆ is an organic group having a fluorine atom. When s is 2 or 3, multiple R Ｅ , W １ A １ and R Ｆ These may be the same or different. The presence of a (y) alkali-dissociable group in the structural unit (IX) causes the resist film surface to change from hydrophobic to hydrophilic during the alkali development process. As a result, the affinity for the developer is significantly increased, and development defects can be suppressed more efficiently. Examples of structural units (IX) having a (y) alkali-dissociable group include A １ is -COO-*, R Ｆ Or W １ Alternatively, it is particularly preferable that both of these contain fluorine atoms.

[0224] R Ｃ From the viewpoint of copolymerizability of monomers that provide structural units (IX), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0225] When the second polymer contains structural units (IX), the lower limit of the content of structural units (IX) (total content if multiple types are included) is preferably 30 mol%, more preferably 40 mol%, and even more preferably 50 mol%, relative to the total structural units constituting the second polymer. The upper limit of the above content is preferably 95 mol%, more preferably 90 mol%, and even more preferably 85 mol%. By setting the content of structural units (IX) within the above range, it is possible to improve the water repellency of the resist film during immersion exposure and improve solubility in alkaline developers to suppress the occurrence of development defects.

[0226] [Other structural units] The second polymer may, if necessary, include structural units other than those listed above, such as structural units (I), (IV), (VII), and structural units having an alkyl ester structure in the base polymer (excluding structures corresponding to structural units (I) to (IX); hereinafter also referred to as "structural unit (X)").

[0227] If the second polymer contains structural unit (I), the lower limit of the content of structural unit (I) is preferably 10 mol%, and more preferably 20 mol%, relative to the total structural units constituting the second polymer. The upper limit of the above content is preferably 80 mol%, and more preferably 60 mol%.

[0228] If the second polymer contains structural unit (IV), the lower limit of the content of structural unit (IV) is preferably 1 mol%, and more preferably 3 mol%, relative to the total structural units constituting the second polymer. The upper limit of the above content is preferably 40 mol%, and more preferably 30 mol%.

[0229] When the second polymer contains structural unit (VII), the lower limit of the content of structural unit (VII) is preferably 8 mol%, and more preferably 15 mol%, relative to the total structural units constituting the second polymer. The upper limit of the above content is preferably 60 mol%, and more preferably 50 mol%.

[0230] The structural unit (X) is preferably a structural unit derived from an alkyl ester of (meth)acrylic acid. The alkyl group constituting the alkyl ester portion is preferably a linear or branched alkyl group having 1 to 10 carbon atoms, and more preferably a branched alkyl group having 3 to 8 carbon atoms. The alkyl ester portion preferably has a secondary alkyl ester structure.

[0231] If the second polymer contains structural unit (X), the lower limit of the content of structural unit (X) is preferably 20 mol%, and more preferably 40 mol%, relative to the total structural units constituting the second polymer. The upper limit of the above content is preferably 80 mol%, and more preferably 60 mol%. If the second polymer contains structural unit (X), the second polymer does not have to contain structural unit (VIII) or (IX).

[0232] The lower limit of Mw for the second polymer is preferably 2,000, and more preferably 4,000. The upper limit of Mw is preferably 20,000, and more preferably 14,000.

[0233] The lower limit of Mw / Mn for the second polymer is usually 1, and 1.1 is more preferred. The upper limit of Mw / Mn is usually 5, 3 is preferred, and 2 is more preferred.

[0234] If the radiation-sensitive composition contains a second polymer, the lower limit of the content of the second polymer is preferably 0.1 parts by mass, more preferably 1 part by mass, and even more preferably 2 parts by mass, per 100 parts by mass of the base polymer. The upper limit of the content is preferably 15 parts by mass, more preferably 10 parts by mass, and even more preferably 8 parts by mass.

[0235] By setting the content of the second polymer within the above range, the second polymer can be more effectively distributed to the surface layer of the resist film. As a result, it is possible to improve the water repellency of the surface of the resist film during immersion exposure, and to control the surface modification of the resist film and the distribution of the composition within the film during EUV exposure. The radiation-sensitive composition may contain one or more types of the second polymer.

[0236] (Method for synthesizing the second polymer) The second polymer can be synthesized by the same method as the method for synthesizing the base polymer described above.

[0237] <Acid Diffusion Control Agent> The radiation-sensitive composition may optionally contain an acid diffusion control agent. The acid diffusion control agent controls the diffusion phenomenon of acid generated from the above compound (A) or structural unit (V) in the resist film upon exposure, and has the effect of suppressing undesirable chemical reactions in unexposed areas. In addition, the storage stability of the resulting radiation-sensitive composition is improved. Furthermore, the resolution of the resist pattern is further improved, and changes in the line width of the resist pattern due to variations in the holding time from exposure to development can be suppressed, resulting in a radiation-sensitive composition with excellent process stability.

[0238] Examples of acid diffusion control agents include compounds represented by the following formula (7) (hereinafter also referred to as "nitrogen-containing compounds (I)"), compounds having two nitrogen atoms in the same molecule (hereinafter also referred to as "nitrogen-containing compounds (II)"), compounds having three nitrogen atoms (hereinafter also referred to as "nitrogen-containing compounds (III)"), amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, and the like.

[0239]

[0240] In the above formula (7), R ２２ , R ２３ and R ２４ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted aralkyl group.

[0241] Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; aromatic amines such as aniline and 2,6-di-i-propylaniline, and the like.

[0242] Examples of the nitrogen-containing compound (II) include ethylenediamine, N,N,N',N'-tetramethylethylenediamine, and the like.

[0243] Examples of the nitrogen-containing compound (III) include polyamine compounds such as polyethyleneimine and polyallylamine; polymers such as dimethylaminoethylacrylamide, and the like.

[0244] Examples of the amide group-containing compound include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone, and the like.

[0245] Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tributylthiourea, and the like.

[0246] Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N-(undecylcarbonyloxyethyl)morpholine; pyrazine, pyrazole, and the like.

[0247] Also, as the nitrogen-containing organic compound, a compound having an acid-dissociable group can also be used. Examples of such nitrogen-containing organic compounds having an acid-dissociable group include N-t-butoxycarbonylpiperidine, N-t-butoxycarbonylimidazole, N-t-butoxycarbonylbenzimidazole, N-t-butoxycarbonyl-2-phenylbenzimidazole, N-(t-butoxycarbonyl)di-n-octylamine, N-(t-butoxycarbonyl)diethanolamine, N-(t-butoxycarbonyl)dicyclohexylamine, N-(t-butoxycarbonyl)diphenylamine, N-t-butoxycarbonyl-4-hydroxypiperidine, N-t-butoxycarbonyl-4-acetoxypiperidine, N-t-amyloxycarbonyl-4-hydroxypiperidine, and the like.

[0248] Further, as the acid diffusion controller, a radiation-sensitive weak acid generator that generates a weak acid upon exposure can also be preferably used. The acid generated from the radiation-sensitive weak acid generator is a weak acid that does not dissociate the acid-dissociable group under the conditions for dissociating the acid-dissociable group in the polymer.

[0249] Examples of the radiation-sensitive weak acid generator include onium salt compounds that decompose upon exposure and lose acid diffusion control properties. Examples of the onium salt compounds include sulfonium salt compounds represented by the following formula (8-1), iodonium salt compounds represented by the following formula (8-2), and the like. Also, compounds containing a sulfonium cation and an anion in the same molecule represented by the following formula (8-3) and compounds containing an iodonium cation and an anion in the same molecule represented by the following formula (8-4) are included.

[0250]

[0251] In the above formulas (8-1) to (8-4), J ＋ is a sulfonium cation, and U ＋ is an iodonium cation. Examples of the sulfonium cation represented by J ＋ include sulfonium cations represented by the above formulas (X-1) to (X-4), and U ＋Examples of iodonium cations represented by the above formulas (X-5) to (X-6) include iodonium cations represented by E. - and Q - Each of them is independent of OH - , R α -COO - , R α -SO ３ - This is an anion represented by R. α R is a single bond or a monovalent organic group having 1 to 30 carbon atoms. α As the monovalent organic group having 1 to 30 carbon atoms represented by the above-mentioned fused ring group, a group obtained by extending the monovalent organic group having 1 to 20 carbon atoms shown in the substituents that the above-mentioned fused ring group may have up to 30 carbon atoms can be suitably adopted.

[0252] Examples of anions for the above-mentioned acid diffusion control agent include, but are not limited to, those listed below. Compounds containing both an iodonium cation and anion within the same molecule, and compounds containing both a sulfonium cation and anion within the same molecule are also given as examples. The iodine group in the following formulas may be substituted with a hydrogen atom or other substituents.

[0253]

[0254]

[0255] As the onium cation in the above acid diffusion control agent, the structure of the organic cation of compound (A) can be suitably adopted.

[0256] The above-mentioned acid diffusion control agents can also be synthesized by known methods, particularly by salt exchange reactions.

[0257] These acid diffusion control agents may be used individually or in combination of two or more. When the radiation-sensitive composition contains an acid diffusion control agent, the lower limit of the acid diffusion control agent content (total in the case of multiple types) is preferably 1 part by mass, more preferably 5 parts by mass, and still more preferably 8 parts by mass, per 100 parts by mass of the base polymer. The upper limit of the above content is preferably 60 parts by mass, more preferably 50 parts by mass, and still more preferably 40 parts by mass.

[0258] (Solvent) The radiation-sensitive composition according to this embodiment contains a solvent. The solvent is not particularly limited as long as it is capable of dissolving or dispersing compound (A), the base polymer, and any optional components that may be contained therein.

[0259] Examples of solvents include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0260] Examples of alcohol-based solvents include monoalcohol solvents having 1 to 18 carbon atoms, such as isopropanol, 4-methyl-2-pentanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, and diacetone alcohol; polyhydric alcohol solvents having 2 to 18 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; and polyhydric alcohol partial ether solvents, such as 3-methoxybutanol and 1-methoxy-2-propanol (propylene glycol monomethyl ether), which are obtained by etherifying some of the hydroxyl groups in the above-mentioned polyhydric alcohol solvents. In this embodiment, alcohol acid ester solvents such as methyl lactate, ethyl lactate, propyl lactate, butyl lactate, methyl 2-hydroxyisobutyrate, isopropyl 2-hydroxyisobutyrate, isobutyl 2-hydroxyisobutyrate, and n-butyl 2-hydroxyisobutyrate are also included in the alcohol-based solvents.

[0261] Examples of ether-based solvents include dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether; cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; aromatic ring-containing ether solvents such as diphenyl ether and anisole (methylphenyl ether); and polyhydric alcohol ether solvents in which the hydroxyl groups of the above-mentioned polyhydric alcohol solvents, such as propylene glycol monomethyl ether, have been etherified.

[0262] Examples of ketone solvents include linear ketone solvents such as acetone, butanone, and methyl isobutyl ketone; cyclic ketone solvents such as cyclopentanone, cyclohexanone, and methylcyclohexanone; and 2,4-pentanedione, acetonylacetone, and acetophenone.

[0263] Examples of amide solvents include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; and chain-like amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0264] Examples of ester solvents include monocarboxylic acid ester solvents such as n-butyl acetate; polyhydric alcohol partial ether ester solvents such as diethylene glycol acetate mono-n-butyl ether, propylene glycol acetate monomethyl ether, and dipropylene glycol acetate monomethyl ether; lactone solvents such as γ-butyrolactone and valerolactone; carbonate solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; and polyhydric carboxylic acid diester solvents such as propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoethyl acetate, and diethyl phthalate.

[0265] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, diisopropylbenzene, and n-amylnaphthalene.

[0266] Among these, alcohol-based solvents, ester-based solvents, and ketone-based solvents are preferred, with C1-C18 monoalcohol-based solvents, alcoholic acid ester-based solvents, polyhydric alcohol partial ether-based solvents, polyhydric alcohol partial ether acetate-based solvents, lactone-based solvents, and cyclic ketone-based solvents being more preferred, and diacetone alcohol, methyl 2-hydroxyisobutyrate, propylene glycol acetate monomethyl ether, propylene glycol monomethyl ether, γ-butyrolactone, and cyclohexanone being even more preferred. The radiation-sensitive composition may contain one or more solvents.

[0267] (Other optional components) The above-mentioned radiation-sensitive composition may contain other optional components in addition to the components listed above. Examples of these other optional components include crosslinking agents, localization promoters, surfactants, alicyclic skeleton-containing compounds, sensitizers, etc. These other optional components may be used individually or in combination of two or more types.

[0268] <Method for preparing a radiation-sensitive composition> The above radiation-sensitive composition can be prepared by mixing, for example, compound (A), a polymer, and additives as needed, and a solvent in a predetermined ratio. After mixing, the above radiation-sensitive composition is preferably filtered using, for example, a filter with a pore size of about 0.05 μm to 0.40 μm. The solid content concentration of the above radiation-sensitive composition is usually 0.1% to 50% by mass, preferably 0.5% to 30% by mass, and more preferably 1% to 20% by mass.

[0269] <Pattern Forming Method> A pattern forming method according to one embodiment of the present invention includes a step (1) of applying the above-mentioned radiation-sensitive composition directly or indirectly to a substrate to form a resist film (hereinafter also referred to as the "resist film forming step"), a step (2) of exposing the resist film (hereinafter also referred to as the "exposure step"), and a step (3) of developing the exposed resist film with a developer solution (hereinafter also referred to as the "development step").

[0270] According to the pattern formation method described above, since the radiation-sensitive composition that exhibits excellent sensitivity, LWR, EL, DOF, development defect count, pattern rectangularity, CDU, MEEF, and pattern circularity is used during pattern formation, high-quality resist patterns can be efficiently formed. The following describes each step.

[0271] [Resist Film Formation Process] In this process (step (1) above), a resist film is formed using the radiation-sensitive composition. Examples of substrates for forming this resist film include conventionally known materials such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective film, such as those disclosed in Japanese Patent Publication No. 6-12452 or Japanese Patent Publication No. 59-93448, may be formed on the substrate. Examples of coating methods include spin coating, casting, and roll coating. After coating, pre-baking (PB) may be performed as needed to volatilize the solvent in the coating film. The PB temperature is usually 60°C to 170°C, with 80°C to 150°C being preferred. The PB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred.

[0272] The lower limit of the thickness of the formed resist film is preferably 10 nm, more preferably 15 nm, and even more preferably 20 nm. The upper limit of the thickness is preferably 500 nm, more preferably 350 nm, and even more preferably 200 nm.

[0273] When performing immersion exposure, regardless of whether or not the above-mentioned radiation-sensitive composition contains the above-mentioned water-repellent polymer additive such as the second polymer, a protective immersion film insoluble in the immersion liquid may be provided on the formed resist film to avoid direct contact between the immersion liquid and the resist film. As the protective immersion film, either a solvent-peelable protective film that is peeled off with a solvent before the development process (see, for example, Japanese Patent Application Publication No. 2006-227632) or a developer-peelable protective film that is peeled off simultaneously with development in the development process (see, for example, Japanese Patent Application Publication Nos. WO2005-069076 and WO2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer-peelable protective immersion film.

[0274] [Exposure Process] In this process (process (2) above), the resist film formed in the resist film formation process, which is process (1) above, is exposed by irradiating it with radiation through a photomask (and, in some cases, through an immersion liquid such as water). The radiation used for exposure can be electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet light), X-rays, and gamma rays, depending on the line width of the desired pattern; for example, electron beams and charged particle beams such as alpha rays. Among these, far ultraviolet light, electron beams, and EUV are preferred, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV are more preferred, and ArF excimer laser light (wavelength 193 nm), electron beams, and EUV are even more preferred.

[0275] When exposure is performed by immersion lithography, the immersion liquid used can be, for example, water or a fluorine-based inert liquid. The immersion liquid is preferably transparent to the exposure wavelength and has the smallest possible temperature coefficient of refractive index to minimize distortion of the optical image projected onto the film. In particular, when the exposure light source is ArF excimer laser light (wavelength 193 nm), in addition to the above considerations, water is preferred due to its availability and ease of handling. When water is used, a small amount of an additive that reduces the surface tension of the water and increases its surfactant properties may be added. This additive is preferably one that does not dissolve the resist film on the wafer and has negligible effect on the optical coating on the underside of the lens. Distilled water is preferred as the water used.

[0276] After the exposure described above, it is preferable to perform a post-exposure bake (PEB) to promote the dissociation of acid-dissociable groups of polymers, etc., by the acid generated from compound (A) or, if present, structural unit (V) in the exposed portion of the resist film due to exposure. This PEB creates a difference in solubility in the developer between the exposed and unexposed portions. The PEB temperature is usually 60°C to 160°C, with 80°C to 140°C being preferred. The PEB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred.

[0277] [Development Process] In this process (the above process (3)), the resist film exposed in the above exposure process (the above process (2)) is developed. Thereby, a predetermined resist pattern can be formed. After development, it is common to wash with a rinse solution such as water or alcohol and then dry.

[0278] As the developer used for the above development, in the case of alkali development, for example, at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, 1,5-diazabicyclo-[4.3.0]-5-nonene dissolved in an alkaline aqueous solution can be mentioned. Among these, an aqueous TMAH solution is preferable, and a 2.38 mass% aqueous TMAH solution is more preferable.

[0279] Further, in the case of organic solvent development, organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, or solvents containing an organic solvent can be mentioned. Examples of the above organic solvent include one or more of the solvents listed as the solvent of the above radiation-sensitive composition. Among these, ether solvents, ester solvents, and ketone solvents are preferable. As the ether solvent, a glycol ether solvent is preferable, and ethylene glycol monomethyl ether and propylene glycol monomethyl ether are more preferable. As the ester solvent, an acetate ester solvent is preferable, and n-butyl acetate and amyl acetate are more preferable. As the ketone solvent, a chain ketone is preferable, and 2-heptanone is more preferable. The content of the organic solvent in the developer is preferably 80 mass% or more, more preferably 90 mass% or more, further preferably 95 mass% or more, and particularly preferably 99 mass% or more. Examples of the components other than the organic solvent in the developer include water, silicone oil, etc.

[0280] As mentioned above, either an alkaline developer or an organic solvent developer may be used as the developer. The appropriate choice can be made depending on whether a positive or negative pattern is desired.

[0281] Examples of development methods include immersing the substrate in a tank filled with developer solution for a certain period of time (dip method), developing by piling the developer solution onto the substrate surface using surface tension and letting it remain still for a certain period of time (paddle method), spraying the developer solution onto the substrate surface (spray method), and continuously dispensing the developer solution while scanning a developer solution dispensing nozzle at a constant speed onto a substrate rotating at a constant speed (dynamic dispensing method).

[0282] 《Compound》 The compound in question is represented by the following formula (A'). (In the above formula (A'), R ｚ -F, -CN, -SO ２ R ａ , -CF ２ H, -SF ５ or -CF ３ That is. R ａ R is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. １ -H, -CN, -SF ５ Alternatively, it is a monovalent organic group having 1 to 10 carbon atoms. Y is -O- or -NR ｂ - is R ｂ L is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. L is a single bond or a divalent organic group. However, R ｚ If is -F, the number of carbon atoms in the divalent organic group is 4 or less. W' is a monovalent fused cyclic group, or a monovalent fused cyclic group having a substituent. However, at least the fused cyclic group or the substituent has a heteroatom. R ｚ If is -F and W is a substituted monovalent fused cyclic group, then the substituent of W is a substituent other than a hydroxyl group. ＋ (This is a monovalent organic cation.)

[0283] Examples of such compounds include R ｚWhen is -F and W is a substituted monovalent fused cyclic group, compound (A) in the above radiation-sensitive composition can be suitably adopted, except that the substituent of W is a substituent other than a hydroxyl group.

[0284] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. The methods for measuring various physical properties are shown below.

[0285] [Weight-average molecular weight (Mw) and number-average molecular weight (Mn)] The Mw and Mn of the polymer were measured under the conditions described above. The degree of dispersion (Mw / Mn) was calculated from the measured results of Mw and Mn.

[0286] [ １３ [C-NMR analysis] Polymer １３ C-NMR analysis was performed using a nuclear magnetic resonance spectrometer (JEOL Ltd.'s "JNM-Delta400").

[0287] <Synthesis of Polymers> The monomers used in the synthesis of each polymer in each example and comparative example are shown below. In the following synthesis examples, unless otherwise specified, parts by mass refers to the value when the total mass of the monomers used is 100 parts by mass, and mol% refers to the value when the total number of moles of the monomers used is 100 mol%.

[0288]

[0289] [Synthesis Example 1] (Synthesis of Polymer (A-1)) Monomers (M-1), (M-2), (M-5), (M-10), and (M-14) were dissolved in 200 parts by mass of 2-butanone in a molar ratio of 40 / 5 / 40 / 10 / 5 (mol%), and MAIB (dimethyl 2,2'-azobisisobutyrate) (10 mol%) relative to the total 100 mol% of the monomers used) was added as an initiator to prepare a monomer solution. 100 parts by mass of 2-butanone was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The cooled polymerization solution was added to methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with methanol, filtered again, and dried at 50°C for 24 hours to obtain a white powdery polymer (A-1) (yield: 75%). The Mw of polymer (A-1) was 4,900, and the Mw / Mn ratio was 1.58. Furthermore, １３ ¹³C-NMR analysis revealed that the content percentages of each structural unit derived from (M-1), (M-2), (M-5), (M-10), and (M-14) were 37.4 mol%, 3.8 mol%, 42.8 mol%, 10.2 mol%, and 5.8 mol%, respectively.

[0290] [Synthesis Examples 2-11] (Synthesis of Polymers (A-2) to (A-11)) Polymers (A-2) to (A-11) were synthesized in the same manner as in Synthesis Example 1, except that monomers of the types and proportions shown in Table 1 below were used. The content percentage (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained polymers are also shown in Table 1 below. Note that "-" in Table 1 below indicates that the corresponding monomer was not used (the same applies to subsequent tables).

[0291]

[0292] [Synthesis Example 12] (Synthesis of Polymer (A-12)) Monomer (M-4), monomer (M-5), and monomer (M-18) were dissolved in 1-methoxy-2-propanol (200 parts by mass) in a molar ratio of 60 / 10 / 30 (mol%), and AIBN (azobisisobutyronitrile) (8 mol%) was added as an initiator to prepare monomer solutions. 100 parts by mass of 1-methoxy-2-propanol was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solutions were added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The cooled polymerization solution was added to hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane, filtered again, and dissolved in 1-methoxy-2-propanol (300 parts by mass). Then, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and the hydrolysis reaction was carried out at 70°C for 6 hours with stirring. After the reaction was complete, the residual solvent was removed by distillation, and the resulting solid was dissolved in acetone (100 parts by mass) and added dropwise to water (500 parts by mass) to solidify the polymer. The resulting solid was filtered and dried at 50°C for 13 hours to obtain a white powdery polymer (A-12) (yield: 82%). The Mw of polymer (A-12) was 5,900, and the Mw / Mn ratio was 1.55. １３ ¹³C-NMR analysis revealed that the content of each structural unit derived from (M-4), (M-5), and (M-18) was 60.3 mol%, 10.3 mol%, and 29.4 mol%, respectively.

[0293] [Synthesis Examples 13-15] (Synthesis of Polymers (A-13) to (A-15)) Polymers (A-13) to (A-15) were synthesized in the same manner as in Synthesis Example 12, except that monomers of the types and proportions shown in Table 2 below were used. Note that the monomers that give structural unit (IV) in the polymer were, １３13C-NMR measurements confirmed the disappearance of the carbonyl group peak of the acetyl group, indicating that virtually all alkali-dissociable groups had been hydrolyzed to phenolic hydroxyl groups. The content percentage (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained polymer are shown in Table 2 below.

[0294]

[0295] [Synthesis Example 16] (Synthesis of the second polymer (F-1)) Monomer (M-4) and monomer (M-21) were dissolved in 2-butanone (200 parts by mass) to a molar ratio of 30 / 70 (mol%), and AIBN (5 mol%) was added as an initiator to prepare a monomer solution. 2-butanone (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the temperature inside the reaction vessel was set to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The solvent was replaced with acetonitrile (400 parts by mass), and hexane (100 parts by mass) was added and stirred, and the acetonitrile layer was recovered. This process was repeated three times. By replacing the solvent with propylene glycol monomethyl ether acetate, a solution of the second polymer (F-1) was obtained (yield: 75%). The Mw of the second polymer (F-1) was 8,700, and the Mw / Mn ratio was 1.67. Also, １３ 13C-NMR analysis revealed that the content of each structural unit derived from (M-4) and (M-21) was 29.8 mol% and 70.2 mol%, respectively.

[0296] [Synthesis Examples 17-20] (Synthesis of Second Polymer (F-2) to Second Polymer (F-5)) Second polymers (F-2) to second polymer (F-5) were synthesized in the same manner as in Synthesis Example 16, except that monomers of the types and proportions shown in Table 3 below were used. The content percentage (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained polymers are also shown in Table 3 below.

[0297]

[0298] <Synthesis of Radiation-Sensitive Acid Generator (B)> [Synthesis Example B1] (Synthesis of Compound (B-1)) Compound (B-1) as a radiation-sensitive acid generator (B) was synthesized according to the following synthesis scheme.

[0299]

[0300] In a reaction vessel, 20.0 mmol of ethyl bromofluoroethyl was added to a mixture of acetonitrile and water (1:1 by mass) to make a 1 M solution. Then, 40.0 mmol of sodium dithionite and 60.0 mmol of sodium bicarbonate were added, and the mixture was reacted at 70°C for 4 hours. After extraction with acetonitrile and removal of the solvent, a mixture of acetonitrile and water (3:1 by mass) was added to make a 0.5 M solution. 60.0 mmol of hydrogen peroxide and 2.00 mmol of sodium tungstate were added, and the mixture was heated and stirred at 50°C for 12 hours. The sodium sulfonate salt compound was obtained by extraction with acetonitrile and removal of the solvent. 20.0 mmol of triphenylsulfonium bromide was added to the above sodium sulfonate salt compound, and a mixture of water and dichloromethane (1:3 by mass) was added to make a 0.5 M solution. After vigorous stirring at room temperature for 3 hours, dichloromethane was added for extraction, and the organic layer was separated. The resulting organic layer was dried over sodium sulfate, the solvent was removed by distillation, and the onium salt (B-1-a) was purified by column chromatography to obtain it in good yield.

[0301] To the above onium salt (B-1-a), 50 g of 1 M aqueous sodium hydroxide solution and 50 g of ethanol were added and the mixture was stirred at room temperature for 3 hours. Then, 1 M aqueous hydrochloric acid solution was added to stop the reaction, and methylene chloride was added for extraction, after which the organic layer was separated. The obtained organic layer was dried over sodium sulfate, and the solvent was removed by distillation to obtain the carboxylic acid compound (B-1-b) in good yield.

[0302] To the above carboxylic acid compound (B-1-b), 20.0 mmol of oxalyl chloride and 50 g of acetonitrile were added and the mixture was stirred at room temperature for 1 hour. Then, 30.0 mmol of the above alcohol compound (B-1-c), 40.0 mmol of triethylamine, and 2.0 mmol of 4-dimethylaminopyridine were added and the mixture was stirred at 80°C for 3 hours. After that, an aqueous saturated ammonium chloride solution was added to stop the reaction, and then methylene chloride was added for extraction, and the organic layer was separated. The obtained organic layer was washed with an aqueous saturated sodium chloride solution, and then with water. After drying with sodium sulfate, the solvent was removed by distillation, and the compound (B-1) represented by the above formula (B-1) was purified by column chromatography to obtain compound (B-1) in good yield.

[0303] [Synthesis Examples B2 to B27] (Synthesis of compounds (B-2) to (B-27)) Compounds as radiation-sensitive acid generators represented by the following formulas (B-2) to (B-27) were synthesized in the same manner as in Synthesis Example B1, except that the raw materials and precursors were appropriately changed.

[0304]

[0305]

[0306]

[0307] In addition to the synthesized components mentioned above, the following compounds were used.

[0308] [Radiation-sensitive acid generators other than (B-1) to (B-24)] b-1 to b-13: Compounds represented by the following formulas (b-1) to (b-13) (Hereafter, compounds represented by formulas (b-1) to (b-13) may be referred to as "compound (b-1)" to "compound (b-13)," respectively.)

[0309]

[0310]

[0311] [Acid Diffusion Control Agent (C)] C-1 to C-8: Compounds represented by the following formulas (C-1) to (C-8) (Hereafter, compounds represented by formulas (C-1) to (C-8) may be referred to as "Compound (C-1)" to "Compound (C-8)," respectively.)

[0312]

[0313] [Solvent (E)] E-1: Propylene glycol monomethyl ether acetate E-2: Propylene glycol monomethyl ether E-3: γ-Butyrolactone E-4: Cyclohexanone E-5: Methyl 2-hydroxyisobutyrate E-6: Diacetone alcohol

[0314] [Other additive components (W)] W-1: MEGAFACE EFS-321 (manufactured by DIC Corporation) (non-fluorine type) W-2: BYK-399 (manufactured by Big Chemie Japan Co., Ltd.) (non-silicone type)

[0315] [Preparation of positive-type radiation-sensitive composition for ArF immersion exposure] [Example 1] 100 parts by mass of (A-1) as polymer (A), 15.0 parts by mass of (B-1) as radiation-sensitive acid generator (B), 12.0 parts by mass of (C-1) as acid diffusion control agent (C), 3.0 parts by mass (solids) of (F-1) as second polymer (F), 0.1 parts by mass of (W-1) as other additive component (W), and 3,500 parts by mass (mass ratio 2240 / 960 / 300) of a mixed solvent of (E-1) / (E-2) / (E-3) as solvent (E) were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive composition (J-1).

[0316] [Examples 2-53, 101-103 and Comparative Examples 1-8, 21-22] Radiation-sensitive compositions (J-2)-(J-53), (J-101)-(J-103), and (CJ-1)-(CJ-8), (CJ-21)-(CJ-22) were prepared in the same manner as in Example 1, except that the components of the types and amounts shown in Tables 4-1 and 4-2 below were used.

[0317]

[0318]

[0319] <Formation of a resist pattern using a positive-type radiation-sensitive composition for ArF immersion lithography> An anti-reflective underlayer film formation composition ("ARC66" from Brewer Science) was applied to a 12-inch silicon wafer using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Limited), and then heated at 205°C for 60 seconds to form an anti-reflective underlayer film with an average thickness of 100 nm. The positive-type radiation-sensitive composition for ArF immersion lithography prepared above was applied to this anti-reflective underlayer film using the same spin coater, and pre-bake (PB) was performed at 100°C for 60 seconds. Subsequently, a resist film with an average thickness of 90 nm was formed by cooling at 23°C for 30 seconds. Next, the resist film was exposed using an ArF excimer laser immersion lithography system (ASML's "TWINSCAN XT-1900i") under optical conditions of NA = 1.35 and Dipole (σ = 0.9 / 0.7) through a mask pattern with 50 nm lines and a 110 nm pitch. After exposure, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was alkaline developed using a 2.38 mass% TMAH aqueous solution as the alkaline developer. After development, it was washed with water and then dried to form a positive-type resist pattern (50 nm lines, 110 nm pitch).

[0320] <Evaluation> The resist patterns formed using the above ArF immersion exposure positive-type radiation-sensitive composition were evaluated for sensitivity, LWR, EL, DOF, number of development defects, and pattern rectangularity according to the following methods. The results are shown in Tables 5-1 and 5-2 below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns.

[0321] [Sensitivity] In forming a resist pattern using the above ArF immersion lithography positive-type radiation-sensitive composition, the exposure amount used to form a pattern with 50 nm lines and a 110 nm pitch is defined as the optimal exposure amount, and this optimal exposure amount is defined as the sensitivity (mJ / cm²). ２ The sensitivity was set to 30 mJ / cm². ２ The following conditions are considered "good": 30 mJ / cm² ２ If it exceeded this value, it was rated as "poor."

[0322] [LWR] A resist pattern with 50 nm lines and a 110 nm pitch was formed by irradiating with the optimal exposure amount determined in the sensitivity evaluation above. The formed resist pattern was observed from the top of the pattern using the scanning electron microscope described above. The variation in line width was measured at a total of 500 points, and the 3-sigma value was determined from the distribution of these measurements. This 3-sigma value was defined as LWR (nm). A smaller LWR value indicates less line roughness and better quality. An LWR of 3.0 nm or less was evaluated as "good," and an LWR greater than 3.0 nm was evaluated as "poor."

[0323] [EL (Exposure Margin)] Within the range of exposure amounts including the above optimal exposure amount, the exposure amount is 1 mJ / cm². ２ Each resist pattern was formed by varying the exposure dose, and the line width of each line pattern was measured using the scanning electron microscope described above. From the relationship between the obtained line width and exposure dose, the exposure dose E(55) at which the line width was 55 nm and the exposure dose E(45) at which the line width was 45 nm were determined, and the exposure margin (EL) was calculated using the formula {(E(45) - E(55)) / (optimal exposure dose)} × 100. The larger the exposure margin value, the smaller the variation in the dimensions of the pattern obtained when the exposure dose is varied, and the higher the yield during device fabrication. An EL of 10% or more was evaluated as "good," and a value below 10% was evaluated as "poor."

[0324] [DOF (Depth of Focus)] In the resist pattern resolved at the optimal exposure amount determined in the sensitivity evaluation above, the dimensions were observed when the focus was changed in the depth direction. The margin in the depth direction where the pattern dimensions fall within 90% to 110% of the standard without bridging or residue was measured, and this measured value was defined as the depth of focus (nm). A larger depth of focus indicates better performance. A depth of focus of 70 nm or more was evaluated as "good," and a depth of focus of less than 70 nm was evaluated as "poor."

[0325] [Development Defect Count] A resist film was exposed at the optimal exposure level to form a resist pattern with 50 nm lines and a 110 nm pitch, and this was used as a wafer for defect inspection. The number of defects on this wafer was measured using a defect inspection device (KLA-Tencor's "KLA2810"). Defects with a diameter of 5 μm or less were judged to be originating from the resist film, and their number was calculated. After development, the defect count was evaluated as "good" if the number of defects judged to be originating from the resist film was 150 or less, and as "poor" if it exceeded 150.

[0326] [Pattern Rectangularity] The resist patterns with 50 nm lines and 110 nm pitch, formed by irradiating with the optimal exposure amount determined in the sensitivity evaluation above, were observed using the scanning electron microscope described above, and the cross-sectional shape of the line patterns was evaluated. The rectangularity of the resist pattern was evaluated as follows: if the ratio of the length of the lower side to the length of the upper side in the cross-sectional shape of the line portion was 1 or more and 1.05 or less, it was evaluated as "A" (very good); if it was greater than 1.05 and 1.10 or less, it was evaluated as "B" (good); and if it was greater than 1.10, it was evaluated as "C" (poor).

[0327]

[0328]

[0329] As is clear from the results in Tables 5-1 and 5-2, the radiation-sensitive composition of the example exhibited good sensitivity, LWR, EL, DOF, development defect performance, and pattern shape when used in ArF immersion lithography, whereas the comparative example did not satisfy all of the characteristics compared to the example. Therefore, when the radiation-sensitive composition of the example is used in ArF immersion lithography, it is possible to form a resist pattern with high sensitivity and good roughness performance, yield, development defect performance, and pattern shape.

[0330] [Preparation of a negative-type radiation-sensitive composition for ArF immersion exposure, formation and evaluation of a resist pattern using this composition] [Example 54] A radiation-sensitive composition (J-54) was prepared by mixing 100 parts by mass of (A-8) as polymer (A), 3.0 parts by mass of (B-7) and (B-17) as radiation-sensitive acid generators (B), 2.0 parts by mass of (C-2) as acid diffusion control agent (C), 5.0 parts by mass of (F-3) as a second polymer (F) (solid content), and 3,400 parts by mass of a mixed solvent (E) of (E-1) / (E-2) / (E-3) (mass ratio 1,400 / 1,800 / 200) as solvent (E), and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0331] On a 12-inch silicon wafer, a base layer anti-reflective coating composition ("ARC66" from Brewer Science) was applied using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Limited), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 100 nm. On this base layer anti-reflective coating, the ArF immersion lithography negative-type radiation-sensitive composition (J-54) prepared above was applied using the same spin coater, and pre-bake (PB) was performed at 100°C for 60 seconds. Subsequently, a resist film with an average thickness of 85 nm was formed by cooling at 23°C for 30 seconds. Next, the resist film was exposed using an ArF excimer laser immersion lithography system (ASML's "TWINSCAN XT-1900i") under optical conditions of NA = 1.35 and Annular (σ = 0.8 / 0.6) through a mask pattern with 55 nm holes and a 125 nm pitch. After exposure, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was developed using n-butyl acetate as the organic solvent developer and dried to form a negative-type resist pattern (a contact hole pattern with 55 nm holes and a 125 nm pitch).

[0332] For resist patterns using the above-mentioned ArF immersion exposure negative-type radiation-sensitive composition, sensitivity, DOF, and pattern rectangularity were evaluated in the same manner as for resist patterns using the above-mentioned ArF immersion exposure positive-type radiation-sensitive composition. In addition, CDU and MEEF were evaluated according to the following method.

[0333] [CDU] A resist pattern was formed by adjusting the mask size to create a contact hole pattern with 55 nm holes and a 125 nm pitch by irradiating with the optimal exposure amount determined in the sensitivity evaluation above. The formed resist pattern was observed from the top of the pattern using the scanning electron microscope described above. The hole diameter was measured at 16 points in the range of 500 nm and the average value was calculated. This average value was then measured at a total of 500 points at arbitrary points, and the 3-sigma value was calculated from the distribution of the measured values, which was defined as CDU (nm). A smaller CDU value indicates less variation in hole diameter over long periods and is therefore better. A CDU of 2.0 nm or less was evaluated as "good," and a value greater than 2.0 nm was evaluated as "poor."

[0334] [MEEF] For resist hole patterns resolved by irradiating with the optimal exposure amount described above, the slope of the straight line was calculated when the diameter of the resist pattern formed using mask patterns with diameters of 57 nm, 59 nm, 61 nm, 63 nm, and 65 nm was plotted on the vertical axis and the size of the mask pattern on the horizontal axis, and this was defined as MEEF. A MEEF value closer to 1 indicates better mask reproducibility. An MEEF of 2 or less was evaluated as "good," and a value greater than 2 was evaluated as "poor."

[0335] As a result, the radiation-sensitive composition of Example 54 exhibited good sensitivity, CDU, DOF, MEEF, and pattern rectangularity even when a negative-type resist pattern was formed by ArF immersion exposure.

[0336] [Preparation of positive-type radiation-sensitive composition for ArF-Dry exposure, formation and evaluation of resist patterns using this composition] [Example 55] A radiation-sensitive composition (J-55) was prepared by mixing 100 parts by mass of (A-6) as a polymer (A), 2.0 parts by mass of (B-3), 2.0 parts by mass of (B-15), and 1.0 part by mass of (b-9) as radiation-sensitive acid generators (B), 2.5 parts by mass of (C-8) as an acid diffusion control agent (C), 0.05 parts by mass of (W-2) as other additive components (W), and 2,650 parts by mass of a mixed solvent (E) of (E-1) / (E-4) / (E-3) (mass ratio 1500 / 1000 / 150) as a solvent (E), and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0337] On an 8-inch silicon wafer, a base layer anti-reflective coating composition ("ARC29" from Brewer Sciences) was applied using a spin coater ("CLEAN TRACK ACT8" from Tokyo Electron Limited), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 77 nm. On this base layer anti-reflective coating, the ArF-Dry exposure positive-type radiation-sensitive composition (J-55) prepared above was applied using the same spin coater, and pre-bake (PB) was performed at 100°C for 60 seconds. Subsequently, a resist film with an average thickness of 130 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an ArF excimer laser exposure apparatus ("S306C" from Nikon Corporation) under optical conditions of NA = 0.75 and Annular (σ = 0.8 / 0.6) through a mask pattern with a 120 nm line and a 200 nm pitch. After exposure, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was alkaline developed using a 2.38% by mass aqueous solution of TMAH as the alkaline developer. After development, it was washed with water and then dried to form a positive-type resist pattern (120 nm line, 200 nm pitch).

[0338] <Evaluation> The resist patterns formed using the above-mentioned positive-type radiation-sensitive composition for ArF-Dry exposure were evaluated for sensitivity, LWR, DOF, EL, pattern rectangularity, and number of development defects in the same manner as the evaluation of the resist patterns using the above-mentioned positive-type radiation-sensitive composition for ArF immersion exposure. As a result, the radiation-sensitive composition of Example 55 showed good sensitivity, LWR, DOF, EL, pattern rectangularity, and development defect performance even when a positive-type resist pattern was formed by ArF-Dry exposure.

[0339] [Preparation of positive-type radiation-sensitive composition for extreme ultraviolet (EUV) exposure] [Example 56] 100 parts by mass of (A-12) as polymer (A), 40.0 parts by mass of (B-16) as radiation-sensitive acid generator (B), 35.0 parts by mass of (C-5) as acid diffusion control agent (C), 3.0 parts by mass (solids) of (F-5) as second polymer (F), 0.1 parts by mass of (W-1) as other additive component (W), and 6,200 parts by mass (mass ratio 2,000 / 4,200) of a mixed solvent of (E-1) / (E-2) as solvent (E) were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive composition (J-56).

[0340] [Examples 56-67 and Comparative Examples 9-13] Radiation-sensitive compositions (J-56) to (J-67) and (CJ-9) to (CJ-13) were prepared in the same manner as in Example 50, except that the components of the types and amounts shown in Table 6 below were used.

[0341]

[0342] <Formation of a resist pattern using a positive-type radiation-sensitive composition for EUV exposure> An anti-reflective underlayer film (ARC66 from Brewer Sciences) was applied to a 12-inch silicon wafer using a spin coater (CLEAN TRACK ACT12 from Tokyo Electron Limited), and then heated at 205°C for 60 seconds to form an anti-reflective underlayer film with an average thickness of 105 nm. The prepared positive-type radiation-sensitive composition for EUV exposure was applied to this anti-reflective underlayer film using the spin coater, and PB (plate blot) was performed at 130°C for 60 seconds. Subsequently, a resist film with an average thickness of 45 nm was formed by cooling at 23°C for 30 seconds. Next, the resist film was exposed using an EUV lithography system (ASML's "NXE3300") with NA = 0.33, illumination conditions: Conventional s = 0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120°C for 60 seconds. Subsequently, the resist film was alkaline developed using a 2.38 mass% TMAH aqueous solution as the alkaline developer. After development, it was washed with water and then dried to form a positive-type resist pattern (22 nm holes, 40 nm pitch contact hole pattern).

[0343] <Evaluation> The resist patterns formed using the above-mentioned positive-type radiation-sensitive composition for EUV exposure were evaluated for sensitivity, CDU, number of development defects, and pattern circularity according to the following method. The results are shown in Table 7 below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns.

[0344] [Sensitivity] In forming a resist pattern using the above-mentioned positive-type radiation-sensitive composition for EUV exposure, the exposure amount used to form a contact hole pattern with 22 nm holes and a 40 nm pitch is defined as the optimal exposure amount, and this optimal exposure amount is defined as the sensitivity (mJ / cm²). ２ The sensitivity was set to 50 mJ / cm². ２ The following conditions are considered "good" and 50 mJ / cm². ２ If it exceeded this value, it was rated as "poor."

[0345] [CDU] A resist pattern was formed by adjusting the mask size to create a contact hole pattern with 22 nm holes and a 40 nm pitch by irradiating with the optimal exposure amount determined in the sensitivity evaluation above. The formed resist pattern was observed from the top of the pattern using the scanning electron microscope described above. The hole diameter was measured at 16 points in the range of 500 nm and the average value was calculated. This average value was then measured at a total of 500 points at arbitrary points, and the 3-sigma value was calculated from the distribution of the measured values, which was defined as CDU (nm). A smaller CDU value indicates less variation in hole diameter over long periods and is considered better. A CDU of 4.0 nm or less was evaluated as "good," and a value greater than 4.0 nm was evaluated as "poor."

[0346] [Development Defect Count] A resist film was exposed at the optimal exposure level to form a contact hole pattern with 22 nm holes and a 40 nm pitch, and this was used as a wafer for defect inspection. The number of defects on this wafer was measured using a defect inspection device (KLA-Tencor's "KLA2810"). Defects with a diameter of 5 μm or less were judged to be originating from the resist film, and their number was calculated. After development, the defect count was evaluated as "good" if the number of defects judged to be originating from the resist film was 100 or less, and as "poor" if it exceeded 100.

[0347] [Pattern Circularity] The 22 nm hole, 40 nm pitch contact hole pattern formed by irradiating with the optimal exposure amount determined in the sensitivity evaluation above was observed in plan view using the scanning electron microscope described above, and the vertical and horizontal sizes were measured. If the ratio of vertical size to horizontal size was 0.90 or more and 1.10 or less, it was evaluated as "A" (good), and if it was less than 0.90 or greater than 1.10, it was evaluated as "C" (poor).

[0348]

[0349] As is clear from the results in Table 7, the radiation-sensitive compositions of the examples showed good sensitivity, CDU, development defect performance, and pattern circularity when used in EUV exposure, whereas the comparative examples did not simultaneously satisfy all of these characteristics compared to the examples.

[0350] [Preparation of a negative-type radiation-sensitive composition for EUV exposure, formation and evaluation of a resist pattern using this composition] [Example 68] A radiation-sensitive composition (J-68) was prepared by mixing 100 parts by mass of (A-14) as polymer (A), 40.0 parts by mass of (B-13) and 10.0 parts by mass of (b-9) as radiation-sensitive acid generators (B), 30.0 parts by mass of (C-1) as acid diffusion control agent (C), 2.0 parts by mass of (F-1) as a second polymer (F) (solid content), and 6,110 parts by mass of a mixed solvent of (E-1) / (E-2) (mass ratio 4,280 / 1,830) as solvent (E), and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0351] On a 12-inch silicon wafer, a base layer anti-reflective coating composition ("ARC66" from Brewer Science) was applied using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Limited), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 105 nm. On this base layer anti-reflective coating, the prepared negative-type radiation-sensitive composition for EUV exposure (J-68) was applied using the same spin coater, and PB (plate blot) was performed at 130°C for 60 seconds. Subsequently, a resist film with an average thickness of 40 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an EUV exposure apparatus ("NXE3300" from ASML) with NA = 0.33, illumination conditions: Conventional s = 0.89, and mask: imecDEFECT32FFR15. After exposure, PEB was performed at 120°C for 60 seconds. Subsequently, the resist film was developed using n-butyl acetate as the organic solvent developer and dried to form a negative-type resist pattern (a contact hole pattern with 20 nm holes and a 50 nm pitch).

[0352] The resist patterns using the above-mentioned negative-type radiation-sensitive composition for EUV exposure were evaluated in the same manner as the evaluation of the resist patterns using the above-mentioned positive and negative-type radiation-sensitive compositions for ArF immersion exposure. As a result, the radiation-sensitive composition of Example 68 showed good sensitivity, CDU, pattern circularity, and development defects even when a negative-type resist pattern was formed by EUV exposure.

[0353] The radiation-sensitive composition, pattern-forming method, and compound described above exhibit good sensitivity to exposure light during pattern formation, and can demonstrate excellent CDU, LWR, MEEF, EL, development defect suppression, pattern circularity, pattern rectangularity, and DOF. Therefore, these can be suitably used in semiconductor device processing processes and the like, where further miniaturization is expected in the future.

Claims

1. A radiation-sensitive composition containing a compound represented by the following formula (A), a polymer containing a structural unit (I) having an acid-dissociable group, and a solvent. (In the above formula (A), R is -F, -CN, -SO ２ R ａ , -CF ２ H, -SF ５ or -CF ３ . R ａ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R １ is -H, -CN, -SF ５ or a monovalent organic group having 1 to 10 carbon atoms. Y is -O- or -NR ｂ -. R ｂ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. L is a single bond or a divalent organic group. However, when R ｚ is -F, the carbon number of the above divalent organic group is 4 or less. W is a monovalent condensed ring group or a monovalent condensed ring group having a substituent. However, at least the above condensed ring group or the above substituent has a hetero atom. Z ＋ is a monovalent organic cation.)​ 2. The radiation-sensitive composition according to claim 1, wherein the condensed ring group is a crosslinked condensed ring group.

3. The radiation-sensitive composition according to claim 1, wherein the condensed ring group comprises a lactone structure, a sultone structure, or a cyclic carbonate structure.

4. The above substituents are -O-, -CO-, NR'-, -S-, -SO ２ -The radiation-sensitive composition according to claim 1, comprising a combination thereof, wherein R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

5. The radiation-sensitive composition according to claim 1, wherein W in formula (A) above is a group represented by any of the following formulas (a1) to (a5). (In the above equations (a1) to (a5), X is independently -C(R) ｂ ) ２ - or -O-. R ｂ R is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. n is an integer from 0 to 6. If n is 2 or greater, multiple R ｃ and R ｅ They are either identical or different from each other. ｃ Each of these is independently a halogen atom, a hydroxyl group, a nitro group, a cyano group, a carboxyl group, an amino group, a sulfanyl group, or a monovalent organic group having 1 to 20 carbon atoms, or R ｃ If multiple R ｃ Two of them can be combined with each other to form a ring structure together with the constituent atoms of the ring they bond to. ｄ R is a monovalent organic group having 1 to 20 carbon atoms or a hydrogen atom. ｅ is a halogen atom, nitro group, cyano group, carboxyl group, amino group, sulfanyl group, or a monovalent organic group having 1 to 20 carbon atoms, or R ｄ and R ｅ These atoms can be combined with each other to form a heterocyclic structure along with the constituent atoms of the ring they bond to. ｆ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. * represents the bond with L in formula (A) above.

6. The radiation-sensitive composition according to any one of claims 1 to 5, wherein L is a single bond.

7. The radiation-sensitive composition according to any one of claims 1 to 5, wherein Y is -O-.

8. R ｚ -F, -CN, -SO ２ R ａ or -CF ２ A radiation-sensitive composition according to any one of claims 1 to 5, wherein H.

9. R １ The radiation-sensitive composition according to any one of claims 1 to 5, wherein is -H or a monovalent chain hydrocarbon group having 1 to 5 carbon atoms.

10. The radiation-sensitive composition according to any one of claims 1 to 5, wherein the content of the above compound is 0.1 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the above polymer.

11. A pattern forming method comprising the steps of: applying a radiation-sensitive composition according to any one of claims 1 to 5 directly or indirectly to a substrate to form a resist film; exposing the resist film to light; and developing the exposed resist film with a developer.

12. The pattern formation method according to claim 11, wherein the exposure is performed using an ArF excimer laser or extreme ultraviolet light.

13. A compound represented by the following formula (A'). (In the above formula (A'), R ｚ -F, -CN, -SO ２ R ａ , -CF ２ H, -SF ５ or -CF ３ That is. R ａ R is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. １ -H, -CN, -SF ５ Alternatively, it is a monovalent organic group having 1 to 10 carbon atoms. Y is -O- or -NR ｂ - is R ｂ L is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. L is a single bond or a divalent organic group. However, R ｚ If is -F, the number of carbon atoms in the divalent organic group is 4 or less. W' is a monovalent fused cyclic group, or a monovalent fused cyclic group having a substituent. However, at least the fused cyclic group or the substituent has a heteroatom. R ｚ If is -F and W is a substituted monovalent fused cyclic group, then the substituent of W is a substituent other than a hydroxyl group. ＋ (This is a monovalent organic cation.)

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