Radiation-sensitive composition, pattern forming method, and compound

Abstract

Provided are a radiation-sensitive composition capable of exhibiting LWR and suppression of development defects at sufficient levels at the time of pattern formation, a pattern forming method, and a compound. A radiation-sensitive composition comprising: a compound represented by formula (1); a polymer including a structural unit having an acid-dissociable group; and a solvent. In the formula, W is a condensed ring structure having a substituted or unsubstituted bridged alicyclic ring and two or more substituted or unsubstituted aromatic rings, each of which is condensed with the bridged alicyclic ring. L is a single bond or a divalent linking group. R1 is -CN, -NO2, -F, -SO2Ra, or -CORb. R2 is a hydrogen atom, -CN, -NO2, -F, -CF2H, -SO2Ra, -CORb, or -Rc. When R1 is -F, R2 does not contain fluorine atom. In R1 and R2, Ra, Rb and Rc are each independently a C1-20 monovalent organic group not containing -CF2- or -CF3. 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 in terms of LWR (Line Width Roughness) and development defect suppression is required to be equivalent to or better than conventional products.

[0007] The present invention aims to provide a radiation-sensitive composition, a pattern-forming method, and a compound that can exhibit sufficient LWR and development defect suppression 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 (1) (hereinafter also referred to as "compound (1)"), a polymer containing a structural unit having an acid dissociable group, and a solvent. (In formula (1), W is a condensed ring structure having a bridged or unbridged alicyclic ring and two or more substituted or unsubstituted aromatic rings each condensed with the bridged or unbridged alicyclic ring. L is a single bond or a divalent linking group. R １ is -CN, -NO ２ ,, -F, -SO ２ R ａ or -COR ｂ is. R ２ is a hydrogen atom, -CN, -NO ２ ,, -F, -CF ２ H, -SO ２ R ａ or -COR ｂ or -R ｃ is. However, when R １ is -F, R ２ does not contain a fluorine atom. In R １ and R ２ , R ａ , R ｂ and R ｃ are each independently a monovalent organic group having 1 to 20 carbon atoms that does not contain -CF ２ - or -CF ３ . Z ＋ is a monovalent organic cation.)

[0010] According to the radiation-sensitive composition, excellent LWR and development defect suppression can be exhibited during pattern formation. Although the reason for this is not clear, it is speculated as follows.

[0011] In compound (1), a predetermined electron-withdrawing group is bonded to the carbon atom adjacent to the sulfur atom of the sulfonate anion. This allows compound (1) to generate a sufficiently strong acid and exhibit the given resist properties. Furthermore, reducing the fluorine atom content improves the dispersibility of compound (1) in the resist film and its solubility in the developer. Moreover, because compound (1) has a bulky condensed ring structure in which an aromatic ring and a bridged alicyclic ring are condensed, the diffusion length of the generated acid and electron diffusion can be appropriately controlled. It is presumed that the above resist properties are 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, which exhibits excellent LWR and development defect suppression during pattern formation, is used, 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 (1). (In formula (1), W is a fused ring structure having a bridged alicyclic ring and two or more aromatic rings that are fused with the bridged alicyclic ring. L is a single bond or a divalent linking group. R １ -CN, -NO ２ -F, -SO ２ R ａ , or -COR ｂ That is. R ２ These are hydrogen atoms, -CN, and -NO ２ -F, -CF ２ H, -SO ２ R ａ ,-COR ｂ , or -R ｃ However, R １ If it is -F, then R ２ It does not contain fluorine atoms. １ and R２ In R ａ , R ｂ and R ｃ Each of these is independently of -CF ２ - or -CF ３ It is a monovalent organic group with 1 to 20 carbon atoms that does not contain Z. ＋ (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, carboxyl groups, formyl groups, carbonyl groups, etc., which can function or be characteristic groups on their own as organic groups are excluded. "Fused ring structure" means a structure in which adjacent rings share one edge (two adjacent atoms). "Bridged alicyclic ring" means a polycyclic structure in which two non-adjacent carbon atoms constituting an aliphatic cyclic structure that does not have aromaticity are linked by a bridge containing one or more atoms, or a structure in which two or more such polycyclic structures are fused together. As abbreviations for substituents, "Me" represents a methyl group and "Ph" represents 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 (1), 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 (1)) is the compound represented by the above formula (1), 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] The condensed ring structure represented by W has a substituted or unsubstituted bridged alicyclic ring and two or more substituted or unsubstituted aromatic rings that condense with the bridged alicyclic ring. In other words, the condensed ring structure is a structure in which, when focusing on one bridged alicyclic ring, two or more aromatic rings condense with the bridged alicyclic ring at different edges of the bridged alicyclic ring. The number of aromatic rings that condense with one bridged alicyclic ring is not particularly limited as long as there are two or more, it may be three, four, or five or more. The number of aromatic rings is preferably two or more and four or less, more preferably two or three, and even more preferably two. The number of bridged alicyclic rings in the condensed ring structure is also not limited to one, and may be two, three, four or more. The number of bridged alicyclic rings is preferably one or more and three or less, more preferably one or two, and even more preferably one. When there are two or more bridged alicyclic rings, the condensed ring structure can be, for example, a structure in which one aromatic ring a, which is condensed with two or more aromatic rings, is condensed with another bridged alicyclic ring b. Bridged alicyclic ring b is condensed with aromatic ring a, as well as other aromatic rings b (and possibly even more aromatic rings). Therefore, when focusing on one bridged alicyclic ring a, two or more aromatic rings, including aromatic ring a, are condensed with bridged alicyclic ring a. Similarly, when focusing on one bridged alicyclic ring b, two or more aromatic rings, including aromatic rings a and aromatic ring b, are condensed with bridged alicyclic ring b.

[0021] The bridged alicyclic ring is not particularly limited as long as it has a basic structure that is an aliphatic polycyclic structure with crosslinks, and may have a bicyclic alicyclic structure (having one crosslink) or a tricyclic alicyclic structure (having two crosslinks). From the viewpoint of ease of forming a condensation structure with an aromatic ring, it is preferable that the bridged alicyclic ring has a bicyclic alicyclic structure. The bridged alicyclic ring may have one aliphatic polycyclic structure with crosslinks, or it may have two or more. When the bridged alicyclic ring has two or more aliphatic polycyclic structures with crosslinks, these aliphatic polycyclic structures are condensed.

[0022] The above-mentioned bridged alicyclic ring is preferably a bridged ring having a bridge of 1 to 4 carbon atoms between two non-adjacent ring constituent atoms in a monocyclic cycloalkane or cycloalkene having 6 to 10 carbon atoms, or a bridged polycyclic ring formed by the fusion of two or more such bridged rings. The number of carbon atoms in the above-mentioned cycloalkane or cycloalkene is preferably 6 to 8. The number of carbon atoms in the above-mentioned bridge is preferably 1 to 3, and more preferably 1 or 2. Some of the carbon atoms constituting the bridge may be replaced with oxygen atoms.

[0023] Specific examples of bridged alicyclic rings include structures represented by the following formula.

[0024]

[0025] If the above-mentioned bridged alicyclic ring has substituents, examples of substituents include halogen atoms such as fluorine, chlorine, bromine, and iodine atoms; hydroxyl groups; carboxyl groups; cyano groups; nitro groups; amino groups; monovalent organic groups having 1 to 20 carbon atoms; and oxo groups (=O).

[0026] Examples of monovalent organic groups having 1 to 20 carbon atoms in the substituents of the bridged alicyclic ring 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] Examples of divalent heteroatom-containing linking groups include -CO-, -CS-, -NR'-, -O-, -S-, and -SO ２ -Examples of groups combining these elements are shown. R' is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.

[0033] 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.

[0034] The aromatic ring that condenses with the bridged alicyclic ring is not particularly limited as long as it has an aromatic ring structure. Examples of aromatic rings include aromatic hydrocarbon rings such as benzene rings, naphthalene rings, anthracene rings, phenalene rings, phenanthrene rings, pyrene rings, fluorene rings, perylene rings, and coronene rings; aromatic heterocyclic rings such as furan rings, pyrrole rings, thiophene rings, phosphole rings, pyrazole rings, oxazole rings, isoxazole rings, thiazole rings, pyridine rings, pyrazine rings, pyrimidine rings, pyridazine rings, triazine rings, carbazole rings, and dibenzofuran rings; or combinations thereof. In particular, the above aromatic rings are preferably aromatic hydrocarbon rings having 6 to 20 carbon atoms or aromatic heterocyclic rings having 3 to 20 carbon atoms, with benzene rings and naphthalene rings being more preferred, and benzene rings being even more preferred. Two or more aromatic rings may be the same or different from each other.

[0035] If the aromatic ring has substituents, substituents that the bridged alicyclic ring may have can be preferably adopted as substituents.

[0036] Specific examples of the above-mentioned condensed ring structure include, for example, the structure represented by the following formula.

[0037]

[0038] Examples of divalent linking groups represented by L include substituted or unsubstituted alkanediyl groups, substituted or unsubstituted cycloalkanediyl groups, substituted or unsubstituted arenediyl groups, divalent heteroatom-containing linking groups, or groups that combine these groups.

[0039] Examples of alkanediyl groups represented by L include alkanediyl groups having 1 to 10 carbon atoms, such as methanediyl, ethanediyl, 1,3-propanediyl, and 2,2-propanediyl groups. Methanediyl and ethanediyl groups are preferred as alkanediyl groups.

[0040] As the cycloalkanediyl group represented by L, a group obtained by removing one hydrogen atom from a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, as shown in the substituent of the bridged alicyclic ring above, can be suitably adopted.

[0041] Examples of the allenediyl group represented by L include divalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, such as benzenediyl groups and naphthalenediyl groups. The benzenediyl group is preferred as the allenediyl group.

[0042] As the divalent heteroatom-containing linking group represented by L, the divalent heteroatom-containing linking group shown in the substituent of the bridged alicyclic ring can be suitably adopted.

[0043] When the divalent linking group represented by L has substituents, substituents that the above-mentioned bridged alicyclic ring may have can be suitably adopted as substituents. When L is an arenediyl group, halogen atoms are preferred as substituents, and iodine atoms are more preferred.

[0044] As L, an alkanediyl group, an arenediyl group, or a divalent group formed by combining these groups with a divalent heteroatom-containing linking group is preferred; a methanediyl group, an ethanediyl group, a benzenediyl group, or a divalent group formed by combining these groups with -COO- or -OCO- is more preferred; and a methanediyl group, an ethanediyl group, or a divalent group formed by combining these groups with -COO- or -OCO- is even more preferred.

[0045] R ａ , R ｂ and R ｃ -CF ２ - or -CF ３ As for monovalent organic groups with 1 to 20 carbon atoms that do not contain -CF ２ - or -CF ３ Except for not including the above-mentioned bridging alicyclic substituent, monovalent organic groups having 1 to 20 carbon atoms can be suitably adopted. ａ Preferably, alkyl groups having 1 to 10 carbon atoms are preferred, linear alkyl groups having 1 to 5 carbon atoms are more preferred, and methyl groups and ethyl groups are even more preferred. ｂ Preferably, the group is an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms; more preferably, a linear alkyl group having 1 to 5 carbon atoms or a linear alkoxy group having 1 to 5 carbon atoms; and even more preferably, a methyl group, an ethyl group, a methoxy group, or an ethoxy group. ａPreferably, the group is a monofluorinated alkyl group having 1 to 10 carbon atoms, more preferably a linear monofluorinated alkyl group having 1 to 5 carbon atoms, and even more preferably a fluoromethyl group or a fluoroethyl group.

[0046] R １ From the viewpoint of reducing hydrophobicity and acid strength, -CN is preferable.

[0047] Specific examples of the anion of compound (1) include structures represented by the following formulas (1-1-1) to (1-1-24).

[0048]

[0049]

[0050]

[0051] 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.

[0052] Z ＋ It is preferable that the cation is a radiation-sensitive onium cation. Examples of radiation-sensitive onium cations include sulfonium cations, tetrahydrothiophenium cations, and iodonium cations. Among these, radiation-sensitive sulfonium cations or radiation-sensitive iodonium cations are preferred, and radiation-sensitive sulfonium cations are more preferred.

[0053] The above organic cation preferably has at least one selected from the group consisting of an iodine group and a fluoro group. The above organic cation preferably contains an iodine group-containing aromatic ring structure as the form of iodine group content. An iodine group-containing aromatic ring structure is a structure in which some or all of the hydrogen atoms of the aromatic ring are replaced by iodine groups. In the organic cation, it is preferable that the fluoro group is contained in the form of a fluoro group-containing aromatic ring structure. A fluoro group-containing aromatic ring structure is a structure in which some or all of the hydrogen atoms of the aromatic ring are replaced by fluoro groups. As the aromatic ring in the iodine group-containing aromatic ring structure and the fluoro group-containing aromatic ring structure, the aromatic ring shown in the above fused ring structure can be suitably adopted. By introducing an iodine group or a fluoro group, the radiation absorption efficiency can be increased, thereby improving sensitivity.

[0054] The sulfonium cation or iodonium cation is preferably represented by the following formulas (X-1) to (X-6).

[0055]

[0056] In the above equation (X-1), R ａ１ , R ａ２ and R ａ３ Each of these independently comprises 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, or -OSO ２ -R Ｐ , -SO ２ -R Ｑ , -S-R Ｔ R 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 Ｔis, independently of one another, 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 an integer of 0 to 5. R ａ１ ~R ａ３ as well as R Ｐ , R Ｑ and R Ｔ when there are a plurality of each of them, the plurality of R ａ１ ~R ａ３ as well as R Ｐ , R Ｑ and R Ｔ may be the same or different from each other.

[0057] In the above formula (X-2), R ｂ１ is a substituted or unsubstituted linear or branched alkyl group 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, a halogen atom, or a hydroxy group. n ｋ is 0 or 1. n ｋ when n is 0, k4 is an integer of 0 to 4, and when n ｋ is 1, k4 is an integer of 0 to 7. R ｂ１ when there are a plurality of them, the plurality of R ｂ１ may be the same or different from each other, and the plurality of R ｂ１ may represent a ring structure formed by combining with each other. R ｂ２ 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. L Ｃ is a single bond or a divalent linking group. k5 is an integer of 0 to 4. R ｂ２ when there are a plurality of them, the plurality of R ｂ２ may be the same or different from each other, and the plurality of R ｂ２ may represent a ring structure formed by combining with each other. q is an integer of 0 to 3. In the formula, the ring structure containing S ＋ may contain heteroatoms such as O and S between the carbon-carbon bonds forming the skeleton.

[0058] In the above formula (X-3), R ｃ１ , R ｃ２ and R ｃ３ are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms.

[0059] In the above formula (X-4), R ｇ１ is a substituted or unsubstituted linear or branched alkyl group 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, a halogen atom, or a hydroxy group. n ｋ２ is 0 or 1. n ｋ２ When n is 0, k10 is an integer from 0 to 4, and n ｋ２ When n is 1, k10 is an integer from 0 to 7. When R ｇ１ is plural, the plurality of R ｇ１ may be the same or different, and the plurality of R ｇ１ may represent a ring structure formed by combining with each other. R ｇ２ and R ｇ３ 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, or these groups represent a ring structure formed by combining with each other. k11 and k12 are each independently an integer from 0 to 4. When R ｇ２ and R ｇ３ are each plural, the plurality of R ｇ２ and R ｇ３ may be the same or different from each other.

[0060] In the above formula (X-5), R ｄ１ and R ｄ２Each 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.

[0061] 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.

[0062] Specific examples of organic cations used as the above-mentioned radiation-sensitive onium cations include, but are not limited to, the structures shown in formulas (1-2-1) to (1-2-54) and (1-3-1) to (1-3-21) below.

[0063]

[0064]

[0065]

[0066]

[0067] Compound (1) can be obtained by appropriately combining the above anion and the above 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 (1-24) below.

[0068]

[0069]

[0070]

[0071] Compound (1) may be used alone or in combination of two or more types. The lower limit of the content of compound (1) (total in the case of multiple types) is preferably 5 parts by mass, more preferably 10 parts by mass, even more preferably 15 parts by mass, and particularly preferably 20 parts by mass, per 100 parts by mass of the base polymer described later. The upper limit of the above content is preferably 100 parts by mass, more preferably 80 parts by mass, even more preferably 60 parts by mass, and particularly preferably 40 parts by mass. This allows for the excellent resist properties described above to be exhibited.

[0072] <Synthesis Method for Compound (1)> It is clear that compound (1) can be synthesized based on the description in the examples and common technical knowledge. Typically, the basic reaction involves cycloaddition of anthracene and an ethylenically unsaturated bond-containing compound via a Diels-Alder reaction to form a fused ring structure. Then, it can be synthesized by cycloaddition using a sulfonic acid or sulfonate (including onium salts with organic cations; the same applies hereafter in this synthesis method section) and an ethylenically unsaturated bond-containing compound having a predetermined electron-withdrawing group, or by introducing a carboxyl group or the like into the fused ring structure via a cycloaddition reaction using an ethylenically unsaturated bond-containing compound having a carboxyl group, and then reacting this with a sulfonic acid or sulfonate and a compound that gives a predetermined electron-withdrawing group, followed by salt exchange with a compound having a predetermined organic cation as needed. Other structures can also be synthesized by appropriately selecting the type of starting material and reaction substrate.

[0073] <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.

[0074] [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).

[0075] 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.

[0076]

[0077] 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.

[0078] The above R １７From 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.

[0079] 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.

[0080] 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.

[0081] L １１ａ As substituents that the arenediyl group represented by can have, substituents that the above-mentioned bridged alicyclic ring can have can be preferably adopted.

[0082] The above R １８ As the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the above, the monovalent hydrocarbon group having 1 to 20 carbon atoms shown in the substituent of the bridged alicyclic ring can be suitably adopted.

[0083] 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.

[0084] The above R １９ and R ２０ The divalent alicyclic groups having 3 to 20 carbon atoms, which are formed by combining these atoms with the carbon atoms to which they are bonded, can preferably be groups obtained by removing one hydrogen atom from the monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms shown in the substituents of the bridged alicyclic groups described above.

[0085] Among these, R １８ R is an alkyl group, alkenyl group, or phenyl group having 1 to 4 carbon atoms. １９ and R ２０It 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.

[0086] 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.

[0087] 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)").

[0088]

[0089]

[0090] In the above equations (3-1) to (3-15), R １７ ~R ２０ This is equivalent to equation (3) above. R Ｌ１１ R 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.

[0091] 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).

[0092] Furthermore, the polymer may contain structural units (I) represented by the following formulas (1f) to (2f).

[0093]

[0094] 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.

[0095] The above R βｆ Preferably, it is a hydrogen atom, a methyl group, or an ethyl group. １ 1 or 2 is preferred.

[0096] 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.

[0097] [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.

[0098] The structural unit having a phenolic hydroxyl group is preferably represented by the following formula (4).

[0099] (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 １０２R 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.)

[0100] 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.

[0101] L ＣＡ For example, a single bond or -COO- ＊ It is preferable.

[0102] R １０２ In this mixture, fluorine or iodine atoms are preferred as halogen atoms.

[0103] The above n ３ 0 or 1 is more preferable, and 0 is even more preferable.

[0104] The above m ３ Preferably, the integer is between 1 and 3, and more preferably 1 or 2.

[0105] The above m ４ Preferably, the integer is between 0 and 3, and more preferably between 0 and 2.

[0106] 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 80 mol%, and more preferably 70 mol%.

[0107] [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.

[0108] Examples of structural units (III) include those represented by the following formulas (T-1) to (T-11).

[0109]

[0110] 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.

[0111] 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.

[0112] The above L ２Examples 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-.

[0113] 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.

[0114] 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 4 mol%, more preferably 8 mol%, and even more preferably 12 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 (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.

[0115] [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.

[0116] Examples of structural units (IV) include structural units represented by the following formula.

[0117]

[0118]

[0119] In the above formula, R Ｋ This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0120] 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 2 mol%, more preferably 5 mol%, and even more preferably 8 mol%. The upper limit of the content is preferably 40 mol%, more preferably 30 mol%, and even more preferably 25 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.

[0121] [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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] Examples of ring structures include structures corresponding to monovalent aliphatic hydrocarbon groups having 3 to 20 carbon atoms as substituents in the bridged alicyclic rings, aromatic rings as shown in the fused ring structures, aliphatic heterocycles, or combinations thereof. Examples of aliphatic heterocycles include oxygen-containing aliphatic heterocycle structures such as oxiranes, tetrahydrofurans, tetrahydropyrans, dioxolanes, and dioxanes; nitrogen-containing aliphatic heterocycle structures such as aziridines, pyrrolidines, piperidines, and piperazines; sulfur-containing aliphatic heterocycle structures such as thiethanes, thiolanes, and thianes; and aliphatic heterocycle structures containing multiple heteroatoms such as morpholines, 1,2-oxathiolanes, and 1,3-oxathiolanes. Examples of aliphatic heterocycle structures include lactone structures, cyclic carbonate structures, sultone structures, cyclic acetals, and cyclic ketones.

[0126] As the chain-like structure, the substituted or unsubstituted alkanediyl group shown in L of formula (1) above can be suitably adopted.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] The structural unit (V) can efficiently perform the above-mentioned functions by combining the above-mentioned structures.

[0132] The structural unit (V) is preferably a structural unit represented by the following formula (a1) (hereinafter also referred to as "structural unit (V-1)").

[0133]

[0134] 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. ３This 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. X １ ＋ This is a sulfonium cation or an iodonium cation.

[0135] 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.

[0136] Preferably, the structural unit (V-1) is a structural unit represented by the following formula (a1-1).

[0137]

[0138] In the formula, R Ｖ , Rf １ ~Rf ２ , V １ ,kk and X １ ＋ This is equivalent to the above formula (a1). R ４８m 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.

[0139] 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 bridged alicyclic ring may have.

[0140]

[0141]

[0142]

[0143]

[0144]

[0145] In the above formula, R Ｖ This is equivalent to equation (a1) above.

[0146] X in the above formula (a1) １ ＋ As for Z in equation (1) above... ＋ A sulfonium cation or an iodonium cation can be suitably used in the organic cation represented by [the formula].

[0147] 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.

[0148] [Structural Unit (VI)] The base polymer may include a structural unit (VI) having a second organic acid anion and a second onium cation, which generates an acid by exposure that does not dissociate 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-generating structure) functions as an acid diffusion control structure. Specifically, under pattern-forming conditions using the above radiation-sensitive composition, the second acid-generating 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 (1) or structural unit (V) (if included) in the unexposed area by salt exchange. The acid generated from the second acid-generating structure can be said to be a relatively weaker acid (an acid with a high pKa) than the acid generated from compound (1) 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.

[0149] 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.

[0150] 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.

[0151] 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).

[0152] 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.

[0153] As the second onium cation mentioned above, the organic cation of compound (1) can be suitably used.

[0154] 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.

[0155] 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.

[0156] The structural unit (VI) can efficiently perform the above-mentioned functions by combining the above-mentioned structures.

[0157] The structural unit (VI) is preferably a structural unit represented by the following formula (p1) (hereinafter also referred to as "structural unit (VI-1)").

[0158]

[0159] In formula (p1), R A This is either a hydrogen atom or a methyl group.

[0160] In formula (p1), X 1 These are single bonds, ester bonds, ether bonds, phenylene groups, naphthylene groups, or combinations thereof.

[0161] 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.

[0162] In formula (p1), X 3 These are single bonds, ester bonds, or ether bonds.

[0163] In formula (p1), X 1 ~X ２ Some or all of the hydrogen atoms in the bridged alicyclic ring may be substituted with substituents. Preferably, substituents that the bridged alicyclic ring 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.

[0164] 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.

[0165] In formula (p1), Z ２ ＋ This is a secondary onium cation. The organic cation shown in compound (1) can be suitably used as the secondary onium cation.

[0166] 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 formula, the iodine group or hydroxyl group may be substituted with a hydrogen atom or a substituent that the above-mentioned bridged alicyclic ring may have. In the following formula, 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.

[0167]

[0168]

[0169]

[0170] 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.

[0171] [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.)

[0172] In the above formula (6), R ２αAs the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above, the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms shown in the substituent of the bridged alicyclic can be suitably adopted.

[0173] 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%.

[0174] (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.

[0175] 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.

[0176] 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, methyl ethyl ketone, 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.

[0177] 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.

[0178] 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 12,000, and even more preferably 8,000. 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.

[0179] 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.

[0180] The methods for measuring Mw and Mn of polymers in this specification are as described in the examples.

[0181] The base polymer content is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, based on the total solid content of the radiation-sensitive composition.

[0182] <Other Polymers> The radiation-sensitive composition of this embodiment may also contain, as other polymers, a polymer with a higher mass content of fluorine atoms than the base polymer (hereinafter also referred to as a "high-fluorine content polymer"). When the radiation-sensitive composition contains a high-fluorine content polymer, it can be unevenly distributed on the surface of the resist film relative to the base polymer, and as a result, it is possible to improve the water repellency of the surface of the resist film during immersion exposure, or to modify the surface of the resist film and control the distribution of the composition within the film during EUV exposure.

[0183] High-fluorine-content polymers may have, for example, a structural unit represented by the following formula (5) (hereinafter also referred to as "structural unit (VIII)").

[0184]

[0185] 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.

[0186] 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.

[0187] 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.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] When a high-fluorine-content polymer has structural unit (VIII), the lower limit of the content of structural unit (VIII) is preferably 10 mol%, more preferably 20 mol%, and even more preferably 25 mol%, relative to the total structural units constituting the high-fluorine-content polymer. The upper limit of the above content is preferably 50 mol%, more preferably 40 mol%, and even more preferably 35 mol%. By setting the content of structural unit (VIII) within the above range, the mass content of fluorine atoms in the high-fluorine-content polymer can be more appropriately adjusted, further promoting the uneven distribution on the surface of the resist film, and as a result, the film quality controllability of the resist film can be further improved.

[0192] High-fluorine-content polymers 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 or in place of structural unit (VIII). The presence of structural unit (IX) in high-fluorine-content polymers improves solubility in alkaline developers and suppresses the occurrence of development defects.

[0193]

[0194] 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.

[0195] If the structural unit (IX) has (x) an alkali-soluble group, RＦ A is a hydrogen atom, １ The 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.

[0196] 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.

[0197] 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.

[0198] When a high-fluorine-content polymer has structural units (IX), the lower limit of the content of structural units (IX) is preferably 30 mol%, more preferably 40 mol%, and even more preferably 50 mol%, relative to the total structural units constituting the high-fluorine-content 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 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, thereby suppressing the occurrence of development defects.

[0199] [Other structural units] High-fluorine polymers may, if necessary, include structural units other than those listed above, such as structural unit (I) and structural unit (IV) in the base polymer.

[0200] When a high-fluorine-content polymer contains structural unit (I), the content of structural unit (I) is preferably 4 mol%, and more preferably 8 mol%, relative to the total structural units constituting the high-fluorine-content polymer. Furthermore, the upper limit of the above content is preferably 30 mol%, and more preferably 15 mol%.

[0201] When a high-fluorine-content polymer contains structural units (IV), the content of structural units (IV) is preferably 10 mol%, and more preferably 20 mol%, relative to the total structural units constituting the high-fluorine-content polymer. Furthermore, the upper limit of the above content is preferably 50 mol%, and more preferably 40 mol%.

[0202] The lower limit of Mw for the high-fluorine-content polymer is preferably 3,000, more preferably 4,000, and even more preferably 5,000. The upper limit of Mw is preferably 20,000, more preferably 10,000, and even more preferably 7,000.

[0203] The lower limit of Mw / Mn for high-fluorine-content polymers 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.

[0204] If the radiation-sensitive composition contains a high-fluorine-content polymer, the lower limit of the high-fluorine-content polymer content 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.

[0205] By setting the content of the high-fluorine polymer within the above range, the high-fluorine 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 internal composition during EUV exposure. The radiation-sensitive composition may contain one or more high-fluorine polymers.

[0206] (Method for synthesizing high-fluorine content polymers) High-fluorine content polymers can be synthesized by the same method as the base polymer synthesis method described above.

[0207] <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 (1) 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.

[0208] 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.

[0209]

[0210] In the above formula (7), R ２２ , R ２３ and R ２４ Each of these is 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.

[0211] Examples of nitrogen-containing compounds (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; and aromatic amines such as aniline and 2,6-di-i-propylaniline.

[0212] Examples of nitrogen-containing compounds (II) include ethylenediamine and N,N,N',N'-tetramethylethylenediamine.

[0213] Examples of nitrogen-containing compounds (III) include polyamine compounds such as polyethyleneimine and polyallylamine; and polymers such as dimethylaminoethylacrylamide.

[0214] Examples of amide group-containing compounds include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, pyrrolidone, and N-methylpyrrolidone.

[0215] Examples of urea compounds include urea, methyl urea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, and tributylthiourea.

[0216] Examples of nitrogen-containing heterocyclic compounds include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N-(undecylcarbonyloxyethyl)morpholine; and pyrazines and pyrazoles.

[0217] Furthermore, compounds having an acid-dissociable group can also be used as the nitrogen-containing organic compound. Examples of 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, and N-t-amyloxycarbonyl-4-hydroxypiperidine.

[0218] Furthermore, a radiation-sensitive weak acid generator that generates a weak acid upon exposure can be suitably used as an acid diffusion control agent. The acid generated from the above-mentioned radiation-sensitive weak acid generator is a weak acid that does not cause the acid-dissociable groups in the polymer to dissociate under conditions that cause the acid-dissociable groups in the polymer to dissociate.

[0219] Examples of radiation-sensitive weak acid generators include onium salt compounds that decompose upon exposure and lose their ability to control acid diffusion. Examples of onium salt compounds include sulfonium salt compounds represented by the following formula (8-1) and iodonium salt compounds represented by the following formula (8-2). Also, examples include compounds containing a sulfonium cation and anion in the same molecule, represented by the following formula (8-3), and compounds containing an iodonium cation and anion in the same molecule, represented by the following formula (8-4).

[0220]

[0221] In the above formulas (8-1) to (8-4), J ＋ It is a sulfonium cation, U ＋ This is an iodonium cation. ＋ Examples of sulfonium cations represented by the above formulas (X-1) to (X-4) include 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 , groups obtained by extending the monovalent organic group having 1 to 20 carbon atoms shown in the substituents that the above-mentioned bridged alicyclic ring can have up to 30 carbon atoms can be suitably adopted. The anion is R α -SO ３ - When expressed as R α -SO３ - Neither the α-position nor the β-position carbon atom of the sulfur atom has an electron-withdrawing group bonded to it. In this case, the electron-withdrawing group shown in structural unit (VI) of the base polymer can be suitably adopted.

[0222] 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.

[0223]

[0224]

[0225] As the onium cation in the above acid diffusion control agent, the structure of the organic cation of compound (1) can be suitably adopted.

[0226] The above-mentioned acid diffusion control agents can also be synthesized by known methods, particularly by salt exchange reactions.

[0227] 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 20 mol%, more preferably 30 mol%, and even more preferably 40 mol%, relative to the total number of moles of the above compound (1) and monomers that give structural units (V) of the base polymer (collectively referred to as "acid generators") that are optionally included. The upper limit of the above content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 60 mol%.

[0228] (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 (1), the base polymer, and any optional components that may be contained therein.

[0229] Examples of solvents include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0230] 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.

[0231] 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.

[0232] 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.

[0233] 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.

[0234] Examples of ester solvents include monocarboxylic acid ester solvents such as n-butyl acetate; 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; 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.

[0235] 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.

[0236] Among these, alcohol-based solvents and ester-based solvents are preferred, monoalcohol-based solvents having 1 to 18 carbon atoms, polyhydric alcohol partial ether acetate-based solvents, and polyhydric alcohol partial ether-based solvents are more preferred, and diacetone alcohol, propylene glycol monomethyl ether acetate, and propylene glycol monomethyl ether are even more preferred. The radiation-sensitive composition may contain one or more solvents.

[0237] (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.

[0238] <Method for preparing a radiation-sensitive composition> The above radiation-sensitive composition can be prepared by mixing, for example, compound (1), a polymer and additives as needed, and a solvent in predetermined proportions. 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.

[0239] <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").

[0240] According to the pattern formation method described above, since the above-mentioned radiation-sensitive composition, which exhibits excellent LWR and development defect suppression, is used during pattern formation, high-quality resist patterns can be efficiently formed. The following describes each step.

[0241] [Resist Film Formation Process] In this process (step (1) above), a resist film is formed using the above-mentioned 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 disclosed in, for example, 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, soft baking (SB) may be performed as needed to volatilize the solvent in the coating film. The SB temperature is usually 60°C to 170°C, with 80°C to 150°C being preferred. The SB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred.

[0242] 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.

[0243] When performing immersion exposure, regardless of the presence or absence of water-repellent polymer additives such as the high-fluorine-content polymer in the above-mentioned radiation-sensitive composition, an immersion-insoluble protective film may be provided on the formed resist film to avoid direct contact between the immersion liquid and the resist film. As the immersion-protective 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 immersion-protective film.

[0244] [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 electron beams and EUV are even more preferred.

[0245] 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.

[0246] 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 (1) or structural unit (V) by exposure in the exposed portion of the resist film. 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.

[0247] [Development Process] In this process (step (3) above), the resist film exposed in the exposure process, which is step (2) above, is developed. This allows a predetermined resist pattern to be formed. After development, it is common to wash with a rinsing solution such as water or alcohol and then dry it.

[0248] Examples of developers used in the above development process include, in the case of alkaline development, an alkaline aqueous solution containing 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, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, an aqueous TMAH solution is preferred, and a 2.38% by mass aqueous TMAH solution is more preferred.

[0249] Furthermore, in the case of organic solvent development, examples of organic solvents include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, etc., or solvents containing organic solvents. Examples of the above organic solvents include one or more of the solvents listed above as solvents for the radiation-sensitive composition. Among these, ether solvents, ester solvents, and ketone solvents are preferred. As for ether solvents, glycol ether solvents are preferred, and ethylene glycol monomethyl ether and propylene glycol monomethyl ether are more preferred. As for ester solvents, acetate ester solvents are preferred, and n-butyl acetate and amyl acetate are more preferred. As for ketone solvents, chain ketones are preferred, and 2-heptanone is more preferred. The content of organic solvents in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. Examples of components other than organic solvents in the developer include water and silicone oil.

[0250] 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.

[0251] 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).

[0252] The compound in question is represented by the following formula (1). (In formula (1), W is a fused ring structure having a bridged alicyclic ring and two or more aromatic rings that are fused with the bridged alicyclic ring. L is a single bond or a divalent linking group. R １ -CN, -NO ２ -F, -SO ２ R ａ , or -COR ｂ That is. R ２ These are hydrogen atoms, -CN, and -NO ２ -F, -CF ２ H, -SO ２ R ａ ,-COR ｂ , or -R ｃ However, R １ If it is -F, then R ２ It does not contain fluorine atoms. １ and R ２ In R ａ , R ｂ and R ｃ Each of these is independently of -CF ２ - or -CF ３ It is a monovalent organic group with 1 to 20 carbon atoms that does not contain Z. ＋ (This is a monovalent organic cation.)

[0253] As such a compound, compound (1) in the above-mentioned radiation-sensitive composition can be suitably used.

[0254] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the following examples, "parts" and "%" refer to mass unless otherwise specified. The measurement methods for each physical property are shown below.

[0255] [Weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polymers] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polymers were measured by gel permeation chromatography (GPC) using Tosoh Corporation's GPC columns (two "G2000HXL" columns, one "G3000HXL" column, and one "G4000HXL" column) under the following conditions: Eluent: Tetrahydrofuran (Wako Pure Chemical Industries, Ltd.) Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Column temperature: 40°C Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0256] <[B] Synthesis of Compound> [Example B-1] Synthesis of Compound (B-1) Compound (B-1) as an acid generator was synthesized according to the following reaction scheme.

[0257]

[0258] 50 mmol of methyl cyanoacetate, 50 mmol of bromine, and 50 mmol of phosphorus tribromide were added to a reaction vessel and stirred at 90°C for 12 hours. Then, saturated sodium thiosulfate aqueous solution was added to stop the reaction, and dichloromethane was added for extraction, after which the organic layer was separated. The layer was dried over anhydrous sodium sulfate to remove the solvent. Purification by silica gel chromatography yielded (p3B-1-1).

[0259] 40 mmol of (p3B-1-1), 20 mL of acetonitrile, 20 mL of ultrapure water, 40 mmol of sodium dithionite, and 60 mmol of sodium bicarbonate were added to a reaction vessel and stirred at 70°C for 4 hours. The solvent was removed by extraction with acetonitrile. Then, 60 mL of acetonitrile, 20 mL of ultrapure water, 60 mmol of hydrogen peroxide solution, and 2 mmol of sodium tungstate were added and stirred at 50°C for 12 hours. The solvent was removed by extraction with acetonitrile. Then, 100 mL of dichloromethane, 100 mL of ultrapure water, and 44 mmol of the compound represented by the above formula (Z-1) were added and stirred at room temperature for 3 hours. The organic layer was separated and washed twice with ultrapure water. Then, it was dried over anhydrous sodium sulfate to remove the solvent. Purification by silica gel chromatography yielded (p2B-1-1).

[0260] 30 mmol of (p2B-1-1), 30 mmol of lithium borohydride, and 50 mL of tetrahydrofuran were added to a reaction vessel and stirred at 70°C for 12 hours. Then, 100 mL of ultrapure water and 100 mL of dichloromethane were added, and the organic layer was separated. The organic layer was washed twice with 50 mL of ultrapure water. After drying over anhydrous sodium sulfate, the solvent was removed to obtain (p1B-1-1).

[0261] 30 mmol of anthracene, 30 mmol of acrylic acid, and 150 mL of toluene were added to a reaction vessel and stirred at 120°C for 10 hours. The resulting solid was filtered and washed with toluene cooled to 0°C to 5°C to obtain (p1B-1-2).

[0262] 20 mmol of (p1B-1-1), 20 mmol of (p1B-1-2), 22 mmol of EDC ((1-(3-dimethylaminopropyl)-3-ethylcarbodiimide)), 4 mmol of DMAP (4-dimethylaminopyridine), and 50 mL of tetrahydrofuran were added to a reaction vessel and stirred at room temperature for 2 hours. 100 mL of dichloromethane was added and the organic layer was separated. The organic layer was washed twice with 50 mL of 2 M hydrochloric acid and twice with 50 mL of ultrapure water. The layer was then dried over anhydrous sodium sulfate to remove the solvent. The compound (B-1) was obtained by purification by silica gel chromatography.

[0263] [Examples B-2 to B-6] Synthesis of Compounds (B-2) to (B-6) Compounds (B-2) to (B-6) were synthesized in the same manner as in Example B-1, except that the substrates used were appropriately selected.

[0264]

[0265] [Example B-7] Synthesis of Compound (B-7) Compound (B-7) was synthesized according to the following reaction scheme.

[0266]

[0267] 50 mmol of anthracene, 50 mmol of maleic anhydride, and 200 mL of toluene were added to a reaction vessel and stirred at 120°C for 10 hours. After filtering the obtained solid, it was washed with toluene cooled to 0°C to 5°C to obtain (p2B-7).

[0268] 40 mmol of (p2B-7), 40 mmol of α-hydroxy-γ-butyrolactone, 60 mmol of triethylamine, 8 mmol of DMAP (4-dimethylaminopyridine), and 50 mL of tetrahydrofuran were added to a reaction vessel and stirred at room temperature for 2 hours. 100 mL of 2M hydrochloric acid was added to separate the organic layer. The organic layer was washed twice with 50 mL of 2M hydrochloric acid and twice with 50 mL of ultrapure water. Then, it was dried over anhydrous sodium sulfate and the solvent was removed. The obtained solid was washed with n-hexane to obtain (p1B-7).

[0269] Next, Compound (B-7) was obtained in the same manner as in Example B-1, except that (p1B-7) was used instead of (p1B-1-2) in Example B-1.

[0270] [Examples B-8 to B-10] Synthesis of Compounds (B-8) to (B-10) Compounds (B-8) to (B-10) were synthesized in the same manner as in Example B-7, except that the substrates used were appropriately selected.

[0271]

[0272] [Example B-11] Synthesis of Compound (B-11) Compound (B-11) was synthesized according to the following reaction scheme.

[0273]

[0274] 50 mmol of tert-butylmethyl malonate, 100 mL of dichloromethane, and 50 mmol of chlorosulfate were added to a reaction vessel and stirred at 50°C for 10 hours. After cooling to room temperature, 100 mL of ultrapure water, 55 mmol of sodium bicarbonate, and 55 mmol of (Z-1) were added and stirred at room temperature for 3 hours. The organic layer was separated, dried over anhydrous sodium sulfate, and the solvent was removed. Purification by silica gel chromatography yielded (p1B-11-1).

[0275] 50 mmol of (p1B-1-2), 100 mL of acetone, 50 mmol of 2-bromoethanol, and 55 mmol of potassium carbonate were added to a reaction vessel and stirred at room temperature for 5 hours. After removing the solvent, 100 mL of dichloromethane and 100 mL of ultrapure water were added, and the organic layer was separated. The organic layer was washed twice with 50 mL of ultrapure water, dried over anhydrous sodium sulfate, and the solvent was removed. Purification by silica gel chromatography yielded (p1B-11-2).

[0276] Next, compound (B-11) was obtained in the same manner as in Example B-1, except that (p1B-11-2) was used instead of (p1B-1-1) and (p1B-11-1) was used instead of (p1B-1-2).

[0277] [Examples B-12 to B-16] Synthesis of compounds (B-12) to (B-16) Compounds (B-12) to (B-16) were synthesized in the same manner as in Example B-11, except that the substrate to be used was appropriately selected.

[0278]

[0279] [Example B-17] Synthesis of compound (B-17) Compound (B-17) was synthesized according to the following reaction scheme.

[0280]

[0281] 50 mmol of anthracene, 50 mmol of methyl acrylate, and 200 mL of toluene were added to a reaction vessel and stirred at 120°C for 10 hours. The resulting solid was filtered and washed with toluene cooled to 0°C to 5°C to obtain (p2B-17).

[0282] 40 mmol of (p2B-17), 40 mmol of lithium borohydride, and 50 mL of tetrahydrofuran were added to a reaction vessel and stirred at 70°C for 12 hours. Then, 100 mL of ultrapure water and 100 mL of dichloromethane were added, and the organic layer was separated. The organic layer was washed twice with 50 mL of ultrapure water. After drying over anhydrous sodium sulfate, the solvent was removed to obtain (p1B-17).

[0283] Next, compound (B-17) was obtained in the same manner as in Example B-1, except that (p1B-17) was used instead of (p1B-1-1) and (p1B-11-1) was used instead of (p1B-1-2).

[0284] [Example B-18] Synthesis of compound (B-18) Compound (B-18) was synthesized according to the following reaction scheme.

[0285]

[0286] 50 mmol of 1-cyano-3-methyl-2-butene, 50 mmol of bromine, and 50 mmol of phosphorus tribromide were added to a reaction vessel and stirred at 90°C for 12 hours. Then, saturated sodium thiosulfate aqueous solution was added to stop the reaction, and dichloromethane was added for extraction, after which the organic layer was separated. The layer was dried over anhydrous sodium sulfate to remove the solvent. Purification by silica gel chromatography yielded (p2B-18).

[0287] 40 mmol of (p2B-18), 20 mL of acetonitrile, 20 mL of ultrapure water, 40 mmol of sodium dithionite, and 60 mmol of sodium bicarbonate were added to a reaction vessel and stirred at 70°C for 4 hours. The solvent was removed by extraction with acetonitrile. Then, 60 mL of acetonitrile, 20 mL of ultrapure water, 60 mmol of hydrogen peroxide solution, and 2 mmol of sodium tungstate were added and stirred at 50°C for 12 hours. The solvent was removed by extraction with acetonitrile. Then, 100 mL of dichloromethane, 100 mL of ultrapure water, and 44 mmol of the compound represented by the above formula (Z-1) were added and stirred at room temperature for 3 hours. The organic layer was separated and washed twice with ultrapure water. Then, it was dried over anhydrous sodium sulfate to remove the solvent. Purification by silica gel chromatography yielded (p1B-18).

[0288] 30 mmol of anthracene, 30 mmol of (p1B-18), and 150 mL of toluene were added to a reaction vessel and stirred at 120 °C for 10 hours. The organic layer was washed twice with 50 mL of ultrapure water, dried over anhydrous sodium sulfate, and the solvent was removed. Purification by silica gel chromatography gave compound (B-18).

[0289] [Example B-19] Synthesis of Compound (B-19) Compound (B-19) was synthesized in the same manner as in Example B-18, except that the substrate used was appropriately selected.

[0290]

[0291] <[A] Synthesis of Polymer> [Synthesis Examples A-1 to A-23] Synthesis of Polymers (A-1) to (A-23) The respective monomers were combined in the compositions shown in Table 1 below, and a copolymerization reaction was carried out in a tetrahydrofuran (THF) solvent. Crystallization was carried out in methanol, and after washing with hexane a predetermined number of times, isolation and drying were carried out to obtain polymers (A-1) to (A-23).

[0292]

[0293] The monomers used for the synthesis of the polymer are shown below.

[0294] <[F] Synthesis of High Fluorine Content Polymer> [Synthesis Example F-1] Synthesis of High Fluorine Content Polymer (F-1) A high fluorine content polymer (F-1) was synthesized in the same manner as in Synthesis Example A-1, except that the types and amounts of monomers used were changed as shown in Table 2 below.

[0295]

[0296] The monomers used for the synthesis of the high fluorine content polymer are shown below.

[0297] <Preparation of Radiation-Sensitive Composition> The [B] compound (acid generator), [C] acid diffusion controller, and [D] solvent used for the preparation of the radiation-sensitive composition are shown below.

[0298] [[B] Acid Generator] In addition to (B-1) to (B-19), the acid generators used for the preparation of the radiation-sensitive composition are shown below.

[0299]

[0300] [C] Acid diffusion control agent: As an acid diffusion control agent, compounds represented by the following formulas (C-1) to (C-5) (hereinafter also referred to as "acid diffusion control agents (C-1) to (C-5)") were used.

[0301]

[0302] [D] Solvent The following solvents were used as solvent [D]: (D-1): Propylene glycol monomethyl ether acetate (D-2): Propylene glycol monomethyl ether (D-3): Diacetone alcohol

[0303] [Examples 1-53 and Comparative Examples 1-2] Preparation of Radiation-Sensitive Compositions [A] Polymer, [F] High-Fluorine Content Polymer, [B] Compound (Acid Generator), [C] Acid Diffusion Control Agent, and [D] Solvent were combined in the amounts shown in Tables 3-1 and 3-2. The amount of [C] Acid Diffusion Control Agent is expressed as a mole percent relative to the total amount of [B] Compound (Acid Generator) and, if present, monomers that give structural units (V) of the [A] Polymer (hereinafter, both are collectively referred to as "Acid Generator" in the table). The resulting mixture was filtered through a membrane filter with a pore size of 0.20 μm to prepare radiation-sensitive compositions. The prepared radiation-sensitive compositions (R-1) to (R-53) and (CR-1) to (CR-2) are shown in Table 2 below.

[0304]

[0305]

[0306] <Formation of Resist Pattern> Each of the radiation-sensitive compositions prepared above was applied to the surface of a 12-inch silicon wafer on which a 40 nm thick underlayer film (AL412 (manufactured by Brewer Science)) had been formed, using a spin coater (CLEAN TRACK ACT12, manufactured by Tokyo Electron). After soft baking at 130°C for 60 seconds, the wafer was cooled at 23°C for 30 seconds to form a 50 nm thick resist film. Next, this resist film was irradiated with EUV light using an EUV exposure machine (model "NXE3300", manufactured by ASML, NA = 0.33, illumination conditions: Conventional s = 0.89, mask: imecDEFECT32FFR02). Subsequently, the resist film was subjected to PEB at 110°C for 60 seconds. Next, a 2.38% by mass aqueous TMAH solution was used to develop the image at 23°C for 30 seconds, forming a positive-type 32 nm line-and-space pattern.

[0307] <Evaluation> The LWR and number of development defects of each radiation-sensitive composition were evaluated by measuring each resist pattern formed as described above according to the method below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-4100") was used to measure the length of the resist patterns. The evaluation results are shown in Tables 4-1 and 4-2 below.

[0308] [LWR Performance] The formed resist pattern was observed from above using the scanning electron microscope described above. The line width was measured at 50 arbitrary points, and the 3-sigma value was determined from the distribution of these measurements. This was defined as the LWR (unit: nm). A smaller LWR value indicates less line jitter and therefore better LWR performance.

[0309] [Development Defect Count] A resist film was exposed and developed at the optimal exposure level to form a 32 nm line-and-space pattern. The number of defects on this wafer was measured using a defect inspection device (KLA-Tencor's "KLA2810"). The measured defects were then classified into those determined to be originating from the resist film and those originating from the external environment. The development defect count was judged as follows: less than 40 defects determined to be originating from the resist film were classified as "A" (excellent), 40 or more but less than 50 as "B" (good), 51 or more but less than 60 as "C" (fairly good), and 60 or more as "D" (poor).

[0310]

[0311]

[0312] As is clear from the results in Tables 4-1 and 4-2, all of the radiation-sensitive compositions in Examples 1 to 53 showed good LWR compared to Comparative Example 1 and good development defect count compared to Comparative Example 2.

[0313] The radiation-sensitive composition of the present invention exhibits excellent low wave rate (LWR) and development defect suppression during pattern formation. Therefore, the radiation-sensitive composition of the present invention, the resist pattern formation method using the same, and the compounds of the present invention are suitable for 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 (1), a polymer containing a structural unit having an acid-dissociable group, and a solvent. (In formula (1), W is a condensed ring structure having a bridged or unbridged alicyclic ring and two or more substituted or unsubstituted aromatic rings each condensed with the bridged or unbridged alicyclic ring. L is a single bond or a divalent linking group. R １ is -CN, -NO ２ , -F, -SO ２ R ａ , or -COR ｂ . R ２ is a hydrogen atom, -CN, -NO ２ , -F, -CF ２ H, -SO ２ R ａ , -COR ｂ , or -R ｃ . However, when R １ is -F, R ２ does not contain a fluorine atom. In R １ and R ２ , R ａ , R ｂ and R ｃ are each independently a monovalent organic group having 1 to 20 carbon atoms that does not contain -CF ２ - or -CF ３ . Z ＋ is a monovalent organic cation.) 2. The radiation-sensitive composition according to claim 1, wherein in formula (1) above, the bridged alicyclic ring is a bridged ring having a bridge of 1 to 4 carbon atoms between two non-adjacent ring constituent atoms in a monocyclic cycloalkane or cycloalkene having 6 to 10 carbon atoms, or a bridged polycyclic ring formed by the condensation of two or more such bridged rings.

3. The radiation-sensitive composition according to claim 1, wherein in formula (1) above, the aromatic ring is each an aromatic hydrocarbon ring having 6 to 20 carbon atoms or an aromatic heterocycle having 3 to 20 carbon atoms.

4. In the above formula (1), R １ The radiation-sensitive composition according to claim 1, wherein is -CN.

5. The radiation-sensitive composition according to claim 1, wherein L is an alkanediyl group, an arenediyl group, or a divalent group formed by combining these groups with a divalent heteroatom-containing linking group.

6. Z ＋ The radiation-sensitive composition according to any one of claims 1 to 5, wherein is a radiation-sensitive sulfonium cation or a radiation-sensitive iodonium cation.

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

8. The radiation-sensitive composition according to any one of claims 1 to 5, wherein the polymer further comprises structural units having phenolic hydroxyl groups.

9. 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.

10. The pattern forming method according to claim 9, wherein the exposure is performed using extreme ultraviolet light or an electron beam.

11. A compound represented by the following formula (1). (In formula (1), W is a fused ring structure having a bridged alicyclic ring and two or more aromatic rings that are fused with the bridged alicyclic ring. L is a single bond or a divalent linking group. R １ -CN, -NO ２ -F, -SO ２ R ａ , or -COR ｂ That is. R ２ These are hydrogen atoms, -CN, and -NO ２ -F, -CF ２ H, -SO ２ R ａ ,-COR ｂ , or -R ｃ However, R １ If it is -F, then R ２ It does not contain fluorine atoms. １ and R ２ In R ａ , R ｂ and R ｃ Each of these is independently of -CF ２ - or -CF ３ It is a monovalent organic group with 1 to 20 carbon atoms that does not contain Z. ＋ (This is a monovalent organic cation.)

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