Radiation-sensitive linear resin composition and pattern formation method

Abstract

This invention provides a radiosensitive linear resin composition and a patterning method for forming a resist film with excellent sensitivity or CDU performance and residual film rate when applied to next-generation technologies. The radiosensitive linear resin composition comprises: a resin containing at least one of the structural units represented by formula (1) and formula (2), and a structural unit having a phenolic hydroxyl group; an acid diffusion control agent represented by formula (α); and a solvent. In formula (1), RT is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group, and RX is a monovalent hydrocarbon group having 1 to 20 carbon atoms. In formula (2), Rc is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group, Lc is a single bond or a divalent linker, and Rc1, Rc2, and Rc3 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms. In formula (α), Rw is a monovalent organic group, hydroxyl group, or amino group with 1 to 20 carbon atoms; Lq is a divalent linker; Z+ is a monovalent radiosensitive linear ononium cation; q1 is an integer from 1 to 4; q2 is an integer from 0 to 3; q3 is an integer from 1 to 3; and the upper limit of q1 + q2 + q3 is 6. When multiple Rw exist, they may be the same or different. When multiple Lq exist, they may be the same or different.

Description

Technical Field

[0001] This invention relates to a radiosensitive linear resin composition and a method for patterning. Prior Technology

[0002] Photolithography, which uses photoresist compositions, is used to form fine circuits in semiconductor devices. A typical procedure is to expose the resist composition film to radiation through a mask pattern, thereby generating an acid. By using the acid as a catalyst, a difference in the solubility of the resin in alkaline or organic solvent-based developers is created between the exposed and unexposed areas, thereby forming a resist pattern on the substrate.

[0003] The aforementioned photolithography techniques utilize short-wavelength radiation such as ArF excimer lasers, or combine this radiation with immersion lithography to promote pattern miniaturization. Next-generation technologies will utilize even shorter-wavelength radiation such as electron beams, X-rays, and extreme ultraviolet (EUV) radiation, and resist materials containing ring-structured resins that improve the absorption efficiency of these radiations are also under investigation (see Japanese Patent No. 6531723). [Existing Technical Documents] [Patent Literature]

[0004] Patent Document 1: Japanese Patent No. 6531723 Summary of the Invention

[0005] [The problem the invention aims to solve]

[0006] The aforementioned next-generation technology also requires that the resist properties be equal to or better than those of the previous ones in terms of sensitivity, critical size uniformity (CDU) performance (as an indicator of linewidth or aperture uniformity), and residual film rate (indicating the maintenance of pattern film thickness before and after exposure).

[0007] The purpose of this invention is to provide a radiosensitive linear resin composition and a patterning method that can form a resist film with excellent sensitivity or CDU performance and residual film rate even when applied to next-generation technologies. [Methods for solving problems]

[0008] The inventors repeatedly studied the problem to solve it, and found that the objective could be achieved by adopting the following structure, thus completing the present invention.

[0009] In one embodiment, the present invention relates to a radiosensitive linear resin composition comprising: The resin comprises at least one of the structural unit represented by formula (1) (hereinafter also referred to as "structural unit (I)") and the structural unit represented by formula (2) (hereinafter also referred to as "structural unit (II)"), and a structural unit having phenolic hydroxyl groups (hereinafter also referred to as "structural unit (III)"); Acid diffusion control agent, represented by the following formula (3); and Solvent. In formula (1), RT is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group, and RX is a monovalent hydrocarbon group with 1 to 20 carbon atoms. In formula (2), Rc is a hydrogen atom, fluorine atom, methyl or trifluoromethyl, Lc is a single bond or divalent linkage, and Rc1, Rc2 and Rc3 are each a monovalent hydrocarbon group with 1 to 20 carbon atoms. In formula (3), Rw is a monovalent organic group, hydroxyl group, or amino group with 1 to 20 carbon atoms, Lq is a divalent linker, Z+ is a monovalent radiosensitive linear ononium cation, q1 is an integer from 1 to 4, q2 is an integer from 0 to 3, q3 is an integer from 1 to 3, and the upper limit of q1+q2+q3 is 6. When multiple Rws exist, they may be the same or different. When multiple Lqs exist, they may be the same or different.

[0010] Using this radiosensitive linear resin composition, a resist film satisfying the requirements for sensitivity, CDU performance, and residual film yield can be constructed. While the reasons are uncertain and not limited, the following speculation is made: The acid-dissociating groups in structural units (I) and (II) of the resin exhibit high acid dissociation due to the steric hindrance of the substituents or the stability of the carbocations, thus increasing the contrast between the exposed and unexposed areas and resulting in excellent pattern formation. Furthermore, the iodine atoms in the acid diffusion control agent have very high absorption of EUV radiation at a wavelength of 13.5 nm, enhancing the sensitivity of the radiosensitive linear resin composition. Moreover, the benzene ring and carboxylate ion in the acid diffusion control agent form a linker group, thus exhibiting good acid-trapping properties. Additionally, the water-repellent properties of the iodine atoms reduce the solubility of the pattern in the unexposed area in the developer. It is speculated that the aforementioned resist properties are achieved through the combined effect of these factors.

[0011] In another embodiment, the present invention relates to a pattern forming method, comprising: The step of directly or indirectly coating the radiosensitive linear resin composition onto a substrate to form a resist film; The step of exposing the resist film; and The step of developing the exposed resist film using a developing solution.

[0012] In this pattern forming method, since the radiosensitive linear resin composition that can form a resist film with excellent sensitivity, CDU performance and residual film rate is used, high-quality resist patterns can be formed efficiently. Implementation

[0013] The following details the embodiments of the present invention, but the present invention is not limited thereto.

[0014] Radiation-sensitive linear resin composition The radiosensitive linear resin composition of this embodiment (hereinafter also referred to as the "composition") contains resin, acid diffusion control agent, and solvent, and may also contain other optional components, as long as they do not impair the effects of the present invention. Including the specified resin and acid diffusion control agent in the radiosensitive resin composition allows the resulting resist film to have a high level of sensitivity, CDU performance, and residual film yield.

[0015] <Resin> The resin is an aggregate of polymers containing at least one of structural units (I) and (II) and structural unit (III) (hereinafter also referred to as the "base resin"). In addition to structural units (I), (II), and (III), the base resin may also contain structural units (IV) containing lactone structures, etc. Each structural unit will be described below.

[0016] (Structural Unit (I)) The structural unit (I) is represented by the following equation (1). In the formula (1), RT is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group, and RX is a monovalent hydrocarbon group with 1 to 20 carbon atoms.

[0017] As for the copolymerization of the monomers that provide the structural unit (I), hydrogen atoms or methyl groups are preferred.

[0018] Examples of monovalent hydrocarbon groups with 1 to 20 carbon atoms represented by RX include chain hydrocarbon groups with 1 to 20 carbon atoms, monovalent alicyclic hydrocarbon groups with 3 to 20 carbon atoms, and monovalent aromatic hydrocarbon groups with 6 to 20 carbon atoms.

[0019] Examples of the aforementioned chain hydrocarbon groups with 1 to 20 carbon atoms include straight-chain or branched saturated hydrocarbon groups with 1 to 20 carbon atoms, or straight-chain or branched unsaturated hydrocarbon groups with 1 to 20 carbon atoms. Examples of the former include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-methylpropyl, 1-methylpropyl, and tributyl, while examples of the latter include alkenyl groups such as vinyl, propenyl, and butenyl; and alkynyl groups such as ethynyl, propynyl, and butynyl.

[0020] The aforementioned alicyclic hydrocarbon groups with 3 to 20 carbon atoms can be listed as monocyclic or polycyclic saturated hydrocarbon groups, or monocyclic or polycyclic unsaturated hydrocarbon groups. Monocyclic saturated hydrocarbon groups are preferably cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Polycyclic cycloalkyl groups are preferably bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, tricyclic decyl, and tetracyclic dodecyl. A bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms constituting the alicyclic ring are bonded together by a chain bond containing one or more carbon atoms.

[0021] Examples of monovalent aromatic hydrocarbon groups with 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthracene; and aralkyl groups such as benzyl, phenethyl, and naphthylmethyl.

[0022] The aforementioned RX is preferably a monovalent chain hydrocarbon group with 1 to 10 carbon atoms or an alicyclic hydrocarbon group with 3 to 12 carbon atoms, and more preferably a straight-chain saturated hydrocarbon group with 1 to 5 carbon atoms.

[0023] Structural unit (I) can be exemplified by the structural units represented by equations (1-1) to (1-4).

[0024] In equations (1-1) to (1-4), RT has the same meaning as in equation (1). Preferably, the structural unit (I) is represented by equation (1-1).

[0025] When the resin contains structural unit (I), the lower limit of the content ratio of structural unit (I) (total if multiple structural units (I) exist) among all structural units constituting the resin is preferably 5 mol%, more preferably 10 mol%, and even more preferably 15 mol%. The upper limit of the content ratio is preferably 80 mol%, more preferably 70 mol%, and even more preferably 60 mol%. By setting the content ratio of structural unit (I) within the above range, the radiosensitive linear resin composition can achieve further improvement in sensitivity and CDU performance.

[0026] (Structural Unit (II)) Structural unit (II) is represented by the following formula (2). In formula (2), Rc is a hydrogen atom, fluorine atom, methyl or trifluoromethyl, Lc is a single bond or divalent linkage, and Rc1, Rc2 and Rc3 are each independently monovalent hydrocarbon groups with 1 to 20 carbon atoms.

[0027] As for Rc, in terms of providing copolymerization of the monomer of structural unit (II), it is preferred to be a hydrogen atom or a methyl group.

[0028] Examples of divalent linkages represented by L c include: alkyldiyl, cycloalkyldiyl, alkenyl, -OR LA-*, -COOR LB-*, etc. (* indicates a bond on the carbonyl side).

[0029] The alkyl dienoyl group mentioned above is preferably an alkyl dienoyl group with 1 to 8 carbon atoms.

[0030] Examples of the aforementioned cycloalkyl diesters include: monocyclic cycloalkyl diesters such as cyclopentane diester and cyclohexane diester; and polycyclic cycloalkyl diesters such as norbornene diester and adamantane diester. Preferably, the aforementioned cycloalkyl diesters are those with 5 to 12 carbon atoms.

[0031] Examples of the aforementioned alkenyl groups include: ethylenediyl, propylenediyl, butenyldiyl, etc. Preferably, the alkenyl group has 2 to 6 carbon atoms.

[0032] Examples of R LA in the above-mentioned -OR LA-* include alkyldiyl, cycloalkyldiyl, and olefinic diyl. Examples of R LB in the above-mentioned -COOR LB-* include alkyldiyl, cycloalkyldiyl, olefinic diyl, and aromatic diyl. Examples of aromatic diyl include phenyldiyl, tolyl, and naphthyl. Preferably, the aromatic diyl has 6 to 15 carbon atoms.

[0033] Of these, Lc is preferably a single bond or -COOR LB-*. RLB is preferably an alkyl dienylate.

[0034] In Lc, some or all of the hydrogen atoms on the carbon atom can be substituted by halogen atoms such as fluorine or chlorine atoms, halogenated alkyl groups such as trifluoromethyl, alkoxy groups such as methoxy, cyano, etc.

[0035] The monovalent hydrocarbon groups with 1 to 20 carbons represented by Rc1, Rc2 and Rc3 can be represented by the groups shown as monovalent hydrocarbon groups with 1 to 20 carbons represented by RX in the above formula (1).

[0036] Preferably, Rc1 and Rc2 are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, and Rc3 is a monovalent alicyclic or aromatic hydrocarbon group having 6 to 12 carbon atoms.

[0037] Structural unit (II) can be exemplified by structural units represented by equations (2-1) to (2-18).

[0038]

[0039] In equations (2-1) to (2-18) above, Rc has the same meaning as in equation (2) above. Among them, structural unit (II) is preferably represented by equations (2-1) to (2-3) and equations (2-10) to (2-12) above.

[0040] When the resin contains structural unit (II), the lower limit of the content ratio of structural unit (II) (total when multiple structural units (II) exist) among all structural units constituting the resin is preferably 5 mol%, more preferably 10 mol%, and even more preferably 15 mol%. The upper limit of the content ratio is preferably 90 mol%, more preferably 80 mol%, and even more preferably 70 mol%. By setting the content ratio of structural unit (II) within the above range, the radiosensitive linear resin composition can achieve further improvement in sensitivity and CDU performance.

[0041] (Structural Unit (III)) Structural unit (III) is a structural unit with phenolic hydroxyl groups or provided with phenolic hydroxyl groups by acid action. The phenolic hydroxyl groups of structural unit (III) may also include those generated by deprotection using acid produced during exposure. Including structural unit (III) in the resin can further improve the sensitivity of the radiation-sensitive resin composition. In addition, when using KrF excimer laser, EUV, electron beam, or other methods for pattern formation with resists, structural unit (III) helps to improve etch resistance and the difference in developer solubility between exposed and unexposed areas (solution contrast). It is especially preferred for pattern formation using radiation with wavelengths below 50 nm, such as electron beam or EUV. Structural unit (III) is preferably represented by the following formula (3).

[0042] In the above formula (3), Rα is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L CA represents a single bond, -COO-*, or -O-. * represents a bonding bond on the aromatic ring side. R 101 is a hydrogen atom or a protecting group that has been deprotected by an acid. When multiple R 101s exist, they may be the same or different from each other. R 102 is cyano, nitro, alkyl, fluorinated alkyl, alkoxycarbonyloxy, acetyl, or acetoxy. When multiple R 102s are present, they may be identical or different from each other. n3 is an integer from 0 to 2, m3 is an integer from 1 to 8, and m4 is an integer from 0 to 8. Among them, 1 ≤ m3 + m4 ≤ 2n3 + 5.

[0043] As for R α, from the viewpoint of providing copolymerization of the monomer of structural unit (III), it is preferably a hydrogen atom or a methyl group.

[0044] L CA is preferably a single bond or -COO-*.

[0045] The protecting groups that are deprotected under acid conditions, as represented by R 101 above, can be exemplified by the groups represented by formulas (AL-1) to (AL-3).

[0046] In formulas (AL-1) and (AL-2) above, RM1 and RM2 are monovalent hydrocarbon groups, which may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The monovalent hydrocarbon group can be linear, branched, or cyclic, preferably an alkyl group with 1 to 40 carbon atoms, and more preferably an alkyl group with 1 to 20 carbon atoms. In formula (AL-1), a is an integer from 0 to 10, preferably an integer from 1 to 5. In formulas (AL-1) to (AL-3) above, * represents a bond with other parts.

[0047] In formula (AL-2), RM3 and RM4 are each independently a hydrogen atom or a monovalent hydrocarbon group, and may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The monovalent hydrocarbon group may be linear, branched, or cyclic, preferably an alkyl group with 1 to 20 carbon atoms. Furthermore, any two of RM2, RM3, and RM4 may be bonded to each other and form a ring with 3 to 20 carbon atoms together with the bonded carbon atoms or carbon atoms and oxygen atoms. The ring is preferably a ring with 4 to 16 carbon atoms, and particularly preferably an alicyclic ring.

[0048] In formula (AL-3), RM5, RM6, and RM7 are each independently a monovalent hydrocarbon group, which may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. This monovalent hydrocarbon group can be linear, branched, or cyclic, preferably an alkyl group with 1 to 20 carbon atoms. Furthermore, any two of RM5, RM6, and RM7 can bond to each other and form a ring with 3 to 20 carbon atoms together with the carbon atoms they are bonded to. The ring is preferably a ring with 4 to 16 carbon atoms, and particularly preferably an alicyclic ring.

[0049] Of these, the protecting group that is deprotected under the action of acid is preferably the group represented by the above formula (AL-3).

[0050] Examples of alkyl groups listed in R 102 include straight-chain or branched alkyl groups with 1 to 8 carbon atoms, such as methyl, ethyl, and propyl. Examples of fluorinated alkyl groups include straight-chain or branched fluorinated alkyl groups with 1 to 8 carbon atoms, such as trifluoromethyl and pentafluoroethyl. Examples of alkoxycarbonyloxy groups include chain or alicyclic alkoxycarbonyloxy groups with 2 to 16 carbon atoms, such as methoxycarbonyloxy, butoxycarbonyloxy, and adamantylmethoxycarbonyloxy. Examples of acetyl groups include aliphatic or aromatic acetyl groups with 2 to 12 carbon atoms, such as acetyloxy, propoxy, benzoyloxy, and propoxy. Examples of acetyloxy groups include aliphatic or aromatic acetyloxy groups with 2 to 12 carbon atoms, such as acetyloxy, propoxy, benzoyloxy, and propoxy.

[0051] The above n 3 is preferably 0 or 1, and even more preferably 0.

[0052] The above m 3 is preferably an integer from 1 to 3, and more preferably 1 or 2.

[0053] The above m 4 is preferably an integer from 0 to 3, and more preferably an integer from 0 to 2.

[0054] The above-mentioned structural unit (III) is preferably the structural unit represented by the following formulas (3-1) to (3-12) (hereinafter also referred to as "structural unit (3-1) to (3-12)").

[0055]

[0056] In equations (3-1) to (3-12) above, Rα is the same as in equation (3).

[0057] Of these, the structural unit (3-1) and structural unit (3-8) mentioned above are preferred.

[0058] Of all the structural units constituting the resin, the lower limit of the content ratio of structural unit (III) (total in the case of multiple structural units (III)) is preferably 5 mol%, more preferably 10 mol%, and even more preferably 15 mol%. The upper limit of the content ratio is preferably 60 mol%, more preferably 55 mol%, and even more preferably 50 mol%. By setting the content ratio of structural unit (III) within the aforementioned range, the radiosensitive linear resin composition can achieve further improvements in sensitivity, CDU performance, and residual film yield.

[0059] When polymerizing monomers such as hydroxystyrene that have phenolic hydroxyl groups, it is preferable to polymerize under the condition that the phenolic hydroxyl groups are protected by protecting groups such as base dissociation groups, and then perform hydrolysis to deprotect them, thereby obtaining structural unit (III).

[0060] (Structural Unit (IV)) The structural unit (IV) comprises at least one selected from the group consisting of lactone structures, cyclic carbonate structures, and sulfonyl lactone structures. Increasing the presence of structural units (IV) in the base resin can adjust its solubility in the developer, resulting in improved lithography properties such as resolution of the radiosensitive resin composition, and also improved adhesion between the formed resist pattern and the substrate.

[0061] Structural units (IV) can be exemplified by structural units represented by equations (T-1) to (T-10).

[0062]

[0063] In the above formula, RL1 is a hydrogen atom, a fluorine atom, a methyl or trifluoromethyl group, RL2 to RL5 are each independently a hydrogen atom, an alkyl group with 1 to 4 carbon atoms, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxy group, a hydroxymethyl group, or a dimethylamino group. RL4 and RL5 can also combine with the carbon atoms they are bonded to to form a divalent alicyclic group with 3 to 8 carbon atoms. L2 is a single bond or a divalent linker. 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.

[0064] The 3-8 carbon-numbered divalent alicyclic group formed by the combination of RL4 and RL5 and their bonded carbon atoms is not particularly limited, as long as it is formed by removing two hydrogen atoms from the same carbon atom of the carbon ring constituting the aforementioned monocyclic or polycyclic alicyclic hydrocarbon. It can be any type of monocyclic or polycyclic hydrocarbon group. The polycyclic hydrocarbon group can be any type of bridged alicyclic or condensed alicyclic hydrocarbon group, as well as any type of saturated or unsaturated hydrocarbon group. Furthermore, the so-called condensed alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group formed by multiple alicyclic rings sharing a common edge (the bond between two adjacent carbon atoms).

[0065] Among the monocyclic alicyclic hydrocarbon groups, saturated hydrocarbon groups are preferably cyclopentanediyl, cyclohexanediyl, cycloheptanediyl, and cyclooctanediyl, etc.; among the unsaturated hydrocarbon groups, cyclopentenidyl, cyclohexenidyl, cycloheptenidyl, cyclooctenidyl, and cyclodecenidyl, etc. Among the polycyclic alicyclic hydrocarbon groups, bridged alicyclic saturated hydrocarbon groups are preferred, such as bicyclic [2.2.1]heptane-2,2-diyl (norbornene-2,2-diyl), bicyclic [2.2.2]octane-2,2-diyl, and tricyclic [3.3.1.1 3,7]decane-2,2-diyl (adamantane-2,2-diyl), etc. One or more hydrogen atoms on this alicyclic group may also be substituted with hydroxyl groups.

[0066] Examples of divalent linkages represented by L 2 include divalent straight-chain or branched hydrocarbon groups with 1 to 10 carbon atoms, divalent alicyclic hydrocarbon groups with 4 to 12 carbon atoms, or groups composed of one or more of these hydrocarbon groups and at least one of the groups selected from -CO-, -O-, -NH- and -S-.

[0067] As structural units (IV), these are preferably structural units containing a lactone structure, more preferably structural units containing a norbornene lactone structure, and even more preferably structural units derived from norbornene lactone-based esters of (meth)acrylate.

[0068] Of all the structural units constituting the resin, the lower limit of the content of structural unit (IV) is preferably 3 mol%, more preferably 5 mol%, and even more preferably 8 mol%. The upper limit of the content is preferably 50 mol%, more preferably 45 mol%, and even more preferably 40 mol%. By setting the content of structural unit (IV) within the aforementioned range, the radiosensitive linear resin composition can further improve lithography properties such as resolution and the adhesion between the formed resist pattern and the substrate.

[0069] (Structural Unit (V)) The structural unit (V) is a structural unit containing an acid-dissociable group (except for those equivalent to structural unit (I)). From the viewpoint of improving the pattern-forming properties of the radiosensitive linear resin composition, the structural unit (V) is preferably the structural unit represented by the following formula (4) (hereinafter also referred to as "structural unit (V-1)").

[0070]

[0071] In formula (4), R P1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 8 is a monovalent hydrocarbon group with 1 to 20 carbon atoms. R 9 represents a divalent alicyclic group with 3 to 20 carbon atoms that together with the bonded carbon atom.

[0072] As for the R P1, from the viewpoint of providing the copolymerization of the monomer of the structural unit (V-1), it is preferably a hydrogen atom, a methyl group, and more preferably a methyl group.

[0073] As the monovalent hydrocarbon group with 1 to 20 carbons represented by R 8, the base shown as the monovalent hydrocarbon group with 1 to 20 carbons represented by RX in formula (1) can be used.

[0074] R8 is preferably a straight-chain or branched saturated hydrocarbon group with 1 to 10 carbon atoms, or an alicyclic hydrocarbon group with 3 to 20 carbon atoms.

[0075] The 3-20 carbon divalent alicyclic groups listed in R 9 above are not particularly limited as long as they are formed by removing two hydrogen atoms from the same carbon atom of a monocyclic or polycyclic alicyclic hydrocarbon ring with the same number of carbons. They can be any type of monocyclic or polycyclic hydrocarbon group. Polycyclic hydrocarbon groups can be any type of bridged alicyclic or condensed alicyclic hydrocarbon group, as well as any type of saturated or unsaturated hydrocarbon group. Condensed alicyclic hydrocarbon groups refer to polycyclic alicyclic hydrocarbon groups formed by multiple alicyclic rings sharing a common edge (the bond between two adjacent carbon atoms).

[0076] Among monocyclic alicyclic hydrocarbon groups, saturated hydrocarbon groups are preferably cyclopentanediyl, cyclohexanediyl, cycloheptanediyl, and cyclooctanediyl, while unsaturated hydrocarbon groups are preferably cyclopentenidyl, cyclohexenidyl, cycloheptenidyl, cyclooctenidyl, and cyclodecenidyl. Among polycyclic alicyclic hydrocarbon groups, bridged alicyclic saturated hydrocarbon groups are preferred, such as bicyclic [2.2.1]heptane-2,2-diyl (norbornene-2,2-diyl), bicyclic [2.2.2]octane-2,2-diyl, and tricyclic [3.3.1.1 3,7]decane-2,2-diyl (adamantane-2,2-diyl), etc.

[0077] In these, it is preferred that R8 is an alkyl group having 1 to 4 carbon atoms, and that the alicyclic structure in R9 is a monocyclic cycloalkane structure having 5 to 8 carbon atoms.

[0078] Structural unit (V-1) can be exemplified by the structural units represented by the following equations (4-1) to (4-3) (hereinafter also referred to as "structural units (V-1-1) to (V-1-3)").

[0079]

[0080] In each formula, R P1 and R 8 have the same meaning as in formula (4) above. i is an integer from 1 to 4.

[0081] i is preferably 1 or 2. R8 is preferably methyl, ethyl, isopropyl, or phenyl.

[0082] The base resin may contain one structural unit (V) or a combination of two or more thereof.

[0083] When the resin contains structural units (V), the lower limit of the content ratio of structural units (V) (the total content ratio when multiple structural units are included) among all structural units constituting the resin is preferably 1 mol%, more preferably 2 mol%, and even more preferably 3 mol%. Furthermore, the upper limit of the content ratio is preferably 30 mol%, more preferably 20 mol%, and even more preferably 15 mol%. By setting the content ratio of structural units (V) within the aforementioned range, the pattern-forming property of the radiosensitive linear resin composition can be further improved.

[0084] (Structural Unit (VI)) In addition to the structural units (I) to (V) described above, the base resin may selectively possess other structural units. Examples of these other structural units include structural units (VI) containing polar groups (excluding those equivalent to structural units (III) and (VI)). By further incorporating structural unit (VI), the base resin can adjust its solubility in the developer, thereby improving the lithography properties of the radiosensitive linear resin composition, such as resolution. Examples of these polar groups include hydroxyl, carboxyl, cyano, nitro, and sulfonamide groups, with hydroxyl and carboxyl groups being preferred, and hydroxyl being even more preferred.

[0085] Structural units (VI) can be exemplified by the structural units shown below.

[0086]

[0087] In the formula, RE is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0088] When the resin contains structural units (VI) having the polar groups, the lower limit of the content ratio of the structural unit (VI) among all structural units constituting the resin is preferably 3 mol%, more preferably 5 mol%, and even more preferably 8 mol%. Furthermore, the upper limit of the content ratio is preferably 40 mol%, more preferably 30 mol%, and even more preferably 25 mol%. By setting the content ratio of the structural unit (VI) within the aforementioned range, the lithography properties such as resolution of the radiosensitive linear resin composition can be further improved.

[0089] (Structural Unit (VII)) The resin may also contain structural units having an organic acid anion portion and an onium cation portion as further structural units (VII), which are preferably represented by the following formula (a1) or (a2).

[0090]

[0091] In the formula, RA is a hydrogen atom or a methyl group. X1 is a single bond or an ester group. X2 is a linear, branched, or cyclic alkyl group with 1 to 12 carbon atoms, or an aryl group with 6 to 10 carbon atoms. A portion of the methylene group constituting the alkyl group may be substituted with an ether group, an ester group, or a group containing an lactone ring. At least one hydrogen atom in X2 may be substituted with an iodine atom. X3 is a single bond, an ether group, an ester group, or a linear, branched, or cyclic alkyl group with 1 to 12 carbon atoms. A portion of the methylene group constituting the alkyl group may also be substituted with an ether group or an ester group. Rf1 to Rf4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one is a fluorine atom or a fluorinated hydrocarbon group. R43 to R47 are each independently a monovalent hydrocarbon group with 1 to 20 carbon atoms, which may contain heteroatoms. R43 and R44 may bond to each other and form a ring together with the sulfur atom they are bonded to.

[0092] The monovalent hydrocarbon group containing heteroatoms of R 43 to R 47, having 1 to 20 carbon atoms, is preferably an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an aryl group having 6 to 20 carbon atoms. Some or all of the hydrogen atoms of these groups may be substituted with hydroxyl, carboxyl, halogen, oxy, cyano, amide, nitro, sulopentalide, guanidine, or strontium salt-containing groups. The methylene portion constituting these groups may be substituted with ether, ester, carbonyl, carbonate, or sulfonate groups.

[0093] The above equations (a1) and (a2) are preferably represented by the following equations (a1-1) and (a2-1), respectively.

[0094]

[0095] In the formula, RA, R43~R47, Rf1~Rf4, and X1 have the same meaning as in formula (a1) or formula (a2). R48 is a straight-chain, branched, or cyclic alkyl group having 1 to 4 carbon atoms, a halogen atom other than iodine, a hydroxyl group, a straight-chain, branched, or cyclic alkoxy group having 1 to 4 carbon atoms, or a straight-chain, branched, or cyclic alkoxy carbonyl group having 2 to 5 carbon atoms. m is an integer from 0 to 4. n is an integer from 0 to 3.

[0096] The anionic moiety of the monomer providing structural unit (VII) can be listed below, but is not limited thereto. Furthermore, the following are all anionic moiety of organic acid radicals having an iodine-substituted aromatic ring structure, but as an anionic moiety of organic acid radicals without an iodine-substituted aromatic ring structure, it is preferable to adopt a structure in which the iodine atom in the following formula is substituted by an atom or group other than the iodine atom, such as a hydrogen atom or other substituent.

[0097]

[0098]

[0099]

[0100]

[0101]

[0102]

[0103]

[0104] The onium cation portion of formula (a1) is preferably represented by the following formula (Q-1).

[0105]

[0106] In the above formula (Q-1), Ra1 and Ra2 independently represent substituents. n1 represents an integer from 0 to 5; when n1 is 2 or more, multiple Ra1s can be the same or different. n2 represents an integer from 0 to 5; when n2 is 2 or more, multiple Ra2s can be the same or different. n3 represents an integer from 0 to 5; when n3 is 2 or more, multiple Ra3s can be the same or different. Ra3 represents a fluorine atom or a group having one or more fluorine atoms. When n1 is 1 or more and n2 is 1 or more, Ra1 and Ra2 can also be linked together to form a ring (i.e., a heterocycle containing a sulfur atom). When n1 is 2 or more, multiple Ra1s can be linked together to form a ring. When n2 is 2 or more, multiple Ra2s can be linked together to form a ring.

[0107] The substituents represented by Ra 1 and Ra 2 are preferably alkyl, cycloalkyl, alkoxy, cycloalkyloxy, alkoxycarbonyl, alkylsulfonyl, hydroxyl, halogen atom, or halogenated hydrocarbon group.

[0108] The alkyl groups of Ra 1 and Ra 2 can be straight-chain alkyl groups or branched-chain alkyl groups. Preferably, the alkyl group has 1 to 10 carbon atoms, and examples include: methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-methylpropyl, 1-methylpropyl, tributyl, n-pentyl, neopentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl. Among these, methyl, ethyl, n-butyl, and tributyl are particularly preferred.

[0109] The cycloalkyl groups of Ra 1 and Ra 2 can be monocyclic or polycyclic cycloalkyl groups (preferably those with 3 to 20 carbon atoms), and examples include: cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclododecyl, cyclopentenyl, cyclohexenyl, and cyclooctadienyl. Among these, cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl are particularly preferred.

[0110] The alkyl moiety of the alkoxy group in Ra 1 and Ra 2 can be exemplified by the groups previously exemplified as alkyl groups in Ra 1 and Ra 2. The alkoxy group is preferably methoxy, ethoxy, n-propoxy, and n-butoxy.

[0111] The cycloalkyl moiety of Ra 1 and Ra 2 can be exemplified by the groups previously exemplified as cycloalkyl groups of Ra 1 and Ra 2. The cycloalkyloxy group is particularly preferably cyclopentyloxy or cyclohexyloxy.

[0112] The alkoxy moiety of the alkoxy carbonyl group in Ra 1 and Ra 2 can be exemplified by the groups previously exemplified as alkoxy groups in Ra 1 and Ra 2. The alkoxy carbonyl group is particularly preferably methoxy carbonyl, ethoxy carbonyl, and n-butoxy carbonyl.

[0113] The alkyl moiety of the alkyl sulfonyl group in Ra 1 and Ra 2 can be exemplified by the groups previously exemplified as alkyl groups in Ra 1 and Ra 2. Similarly, the cycloalkyl moiety of the cycloalkyl sulfonyl group in Ra 1 and Ra 2 can be exemplified by the groups previously exemplified as cycloalkyl groups in Ra 1 and Ra 2. These alkyl sulfonyl or cycloalkyl sulfonyl groups are preferably methanesulfonyl, ethanesulfonyl, n-propanesulfonyl, n-butanesulfonyl, cyclopentanesulfonyl, and cyclohexanesulfonyl.

[0114] Each of the groups in Ra 1 and Ra 2 may also have substituents. Examples of substituents include halogen atoms such as fluorine atoms (preferably fluorine atoms), hydroxyl groups, carboxyl groups, cyano groups, nitro groups, alkoxy groups, cycloalkyloxy groups, alkoxyalkyl groups, cycloalkyloxyalkyl groups, alkoxycarbonyl groups, cycloalkyloxycarbonyl groups, alkoxycarbonyloxy groups, and cycloalkyloxycarbonyloxy groups.

[0115] Examples of halogen atoms that can be used for Ra 1 and Ra 2 include fluorine, chlorine, bromine, and iodine atoms, with fluorine being the preferred choice.

[0116] The halogenated hydrocarbon groups of Ra 1 and Ra 2 are preferably halogenated alkyl groups, and the alkyl and halogen atoms constituting them can be the same as those mentioned above, among which fluorinated alkyl groups are preferred, and CF 3 is even more preferred.

[0117] As mentioned above, Ra 1 and Ra 2 can also be linked together to form a ring (a heterocycle containing sulfur atoms). In this case, it is preferable that Ra 1 and Ra 2 are bonded together to form a single bond or a divalent linker. Examples of the latter include: -COO-, -OCO-, -CO-, -O-, -S-, -SO-, -SO 2-, alkylene, cycloalkylene, alkenylene, or combinations of two or more of these, preferably with a total carbon number of 20 or less. When Ra 1 and Ra 2 are linked together to form a ring, it is preferable that they are bonded together to form -COO-, -OCO-, -CO-, -O-, -S-, -SO-, -SO 2-, or a single bond, more preferably -O-, -S-, or a single bond, and especially preferably a single bond. Furthermore, when n 1 is 2 or more, multiple Ra 1s can be linked together to form a ring; when n 2 is 2 or more, multiple Ra 2s can be linked together to form a ring. This type of example can be illustrated by two Ra 1 rings linked together and forming a naphthalene ring together with the benzene rings they are bonded to.

[0118] Ra 3 is a fluorine atom or a group having one or more fluorine atoms. Examples of groups having fluorine atoms include alkyl, cycloalkyl, alkoxy, cycloalkyloxy, alkoxycarbonyl, and alkylsulfonyl groups of Ra 1 and Ra 2 that have been substituted with fluorine atoms. Among these, fluorinated alkyl groups are preferred examples, more preferred examples are CF 3, C 2F 5, C 3F 7, C 4F 9, C 5F 11, C 6F 13, C 7F 15, C 8F 17, CH 2CF 3, CH 2CH 2CF 3, CH 2C 2F 5, CH 2CH 2C 2F 5, CH 2C 3F 7, CH 2CH 2C 3F 7, CH 2C 4F 9, and CH 2CH 2C 4F 9, and a particularly preferred example is CF 3.

[0119] Ra 3 is preferably a fluorine atom or CF 3, and more preferably a fluorine atom.

[0120] n1 and n2 are each independent and preferably integers from 0 to 3, more preferably integers from 0 to 2.

[0121] n is preferably an integer from 1 to 3, and even better is 1 or 2.

[0122] (n1+n2+n3) is preferably an integer from 1 to 15, more preferably an integer from 1 to 9, even more preferably an integer from 2 to 6, and especially preferably an integer from 3 to 6. When (n1+n2+n3) is 1, it is preferable that n3=1 and Ra3 is a fluorine atom or CF3. When (n1+n2+n3) is 2, it is preferable that n1=n3=1 and Ra1 and Ra3 are each independently a combination of fluorine atoms or CF3, and n3=2 and Ra3 is a combination of fluorine atoms or CF3. When (n1+n2+n3) is 3, it is preferable that n1=n2=n3=1 and Ra1~Ra3 are each independently a combination of fluorine atoms or CF3. When (n1+n2+n3) is 4, it is preferable that n1=n3=2 and Ra1 and Ra3 are each independently a combination of fluorine atoms or CF3. When (n1+n2+n3) is 5, it is preferable that n1=n2=1, n3=3 and Ra1~Ra3 are each independently a combination of fluorine atoms or CF3, n1=n2=2, n3=1 and Ra1~Ra3 are each independently a combination of fluorine atoms or CF3, and n3=5 and Ra3 are each independently a combination of fluorine atoms or CF3. When (n1+n2+n3) is 6, it is preferable that n1=n2=n3=2 and Ra1~Ra3 are each independently a combination of fluorine atoms or CF3.

[0123] Specific examples of the onium cation moiety represented by the aforementioned formula (Q-1) are listed below. Furthermore, the following are all strontium cation moieties having a fluorinated aromatic ring structure (a structure containing a connecting group between the fluorine atom and the aromatic ring). However, as an onium cation moiety without a fluorinated aromatic ring structure, a structure in which the fluorine atom or CF3 is substituted with an atom or group other than a fluorine atom, such as a hydrogen atom or other substituent, is preferred.

[0124]

[0125]

[0126]

[0127] When the onium cation moiety in formula (a2) comprises a fluorine-substituted aromatic ring structure, the onium cation moiety is preferably a diaryl monazine cation having one or more fluorine atoms. Preferably, it is represented by the following formula (Q-2).

[0128]

[0129] In the formula, Rd1 and Rd2 are independently substituted or unsubstituted linear or branched alkyl, alkoxy or alkoxycarbonyl groups having 1 to 12 carbon atoms, substituted or unsubstituted aromatic hydrocarbon groups having 6 to 12 carbon atoms, or nitro groups. Rd3 and Rd4 are independently fluorine atoms or groups having fluorine atoms. k1 and k2 are independently integers from 0 to 5. k3 and k4 are independently integers from 0 to 5. Among them, (k1+k3) and (k2+k4) are each less than 5, and (k3+k4) is an integer from 1 to 10. When there are multiple Rd1 to Rd4, the multiple Rd1 to Rd4 can be the same or different.

[0130] The alkyl, alkoxy, and alkoxycarbonyl groups represented by Rd1 and Rd2, and the groups with fluorine atoms represented by Rd3 and Rd4, can be listed as the same as those in formula (Q-1) above.

[0131] Examples of monovalent aromatic hydrocarbon groups with 6 to 12 carbon atoms include aryl groups such as phenyl, tolyl, xylyl, and naphthyl; and aralkyl groups such as benzyl and phenethyl.

[0132] Examples of substituents for various groups include: halogen atoms such as fluorine, chlorine, bromine, and iodine; hydroxyl groups; carboxyl groups; cyano groups; nitro groups; alkyl groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acetyl groups, acetyloxy groups, or groups in which the hydrogen atom of these groups is replaced by a halogen atom; and side oxygen groups (=O).

[0133] k1 and k2 are preferably 0 to 2, more preferably 0 or 1. k3 and k4 are preferably 1 to 3, more preferably 1 or 2. (k3+k4) is an integer from 1 to 10, but is preferably an integer from 1 to 6, more preferably an integer from 1 to 4, and even more preferably 1 or 2.

[0134] Specific examples of the onium cation moiety represented by the aforementioned formula (Q-2) are listed below. Furthermore, the following are all onium cation moieties having a fluorinated aromatic ring structure (a structure containing a connecting group between the fluorine atom and the aromatic ring). However, as an onium cation moiety without a fluorinated aromatic ring structure, a structure in which the fluorine atom or CF3 is substituted with an atom or group other than a fluorine atom, such as a hydrogen atom or other substituent, is preferred.

[0135]

[0136]

[0137] When the resin contains structural unit (VII), the lower limit of the content ratio of structural unit (VII) (the total content ratio when multiple structural units are included) among all structural units constituting the resin is preferably 3 mol%, more preferably 5 mol%, and even more preferably 8 mol%. Furthermore, the upper limit of the content ratio is preferably 30 mol%, more preferably 25 mol%, and even more preferably 20 mol%. By setting the content ratio of structural unit (VII) within the aforementioned range, the function of the resin as an acid-generating agent can be fully utilized.

[0138] The monomer that provides the structural unit (VII) can be synthesized, for example, using the same method as that described in Japanese Patent No. 5201363 for strontium salts having polymerizable anions.

[0139] (Other structural units) In addition to the structural units (I) to (VII) described above, the resin may also contain structural units derived from styrene. Some or all of the hydrogen atoms in the benzene ring of styrene may be substituted with halogen atoms. Iodine atoms are preferred as halogen atoms.

[0140] When the resin contains structural units derived from styrene, the lower limit of the content of styrene-derived structural units in all structural units constituting the resin is preferably 1 mol%, more preferably 2 mol%, and even more preferably 3 mol%. Furthermore, the upper limit of the content is preferably 10 mol%, more preferably 8 mol% or less, and even more preferably 6 mol% or less.

[0141] (Methods for synthesizing resins) The resin used as the base resin can be synthesized by using known free radical polymerization initiators, etc., to polymerize the monomers that provide each structural unit in a suitable solvent.

[0142] The molecular weight of the resin used as the base resin is not particularly limited, but the equivalent weight average molecular weight (Mw) of the polystyrene obtained by gel permeation chromatography (GPC) is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more, and particularly preferably 4,000 or more. Furthermore, it is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 15,000 or less, and particularly preferably 12,000 or less. If the Mw of the resin is within the aforementioned range, the obtained resist film exhibits good heat resistance and developability.

[0143] The ratio (Mw / Mn) of the resin as the base resin to the equivalent number average molecular weight (Mn) of the polystyrene obtained by GPC is generally 1 or more and 5 or less, preferably 1 or more and 3 or less, and even more preferably 1 or more and 2 or less.

[0144] The methods for determining the Mw and Mn of the resin in this specification are as described in the examples.

[0145] The content of the total solids component of the relative radiosensitive linear resin composition is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more.

[0146] <Other Resins> The radiosensitive linear resin composition of this embodiment may also include a resin with a fluorine atom mass content greater than that of the aforementioned base resin (hereinafter also referred to as "high fluorine content resin") as other resins. When the radiosensitive linear resin composition contains a high fluorine content resin, it may be more concentrated on the surface of the resist film relative to the aforementioned base resin, and the state of the resist film surface or the component distribution in the resist film can be controlled to a desired state.

[0147] The high-fluorine content resin preferably has the structural unit represented by the following formula (6) (hereinafter also referred to as "structural unit (VIII)"). The high-fluorine content resin may also have the structural units (I), (II), (IV) and (V) of the aforementioned base resin as required.

[0148] In formula (6), R13 is a hydrogen atom, methyl or trifluoromethyl, GL is a single bond, oxygen atom, sulfur atom, -COO-, -SO2ONH-, -CONH- or -OCONH-, and R14 is a monovalent fluorinated chain hydrocarbon group with 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group with 3 to 20 carbon atoms.

[0149] As for R 13, from the viewpoint of providing copolymerization of the monomer of the structural unit (VIII), it is preferred to have hydrogen atoms and methyl groups, and more preferably methyl groups.

[0150] As for the GL, from the viewpoint of providing copolymerization of the monomer of the structural unit (VIII), it is preferred to have a single bond and -COO-, more preferably -COO-.

[0151] As the monovalent fluorinated chain hydrocarbon group with 1 to 20 carbon atoms represented by R 14, examples include those in which some or all of the hydrogen atoms of a straight-chain or branched alkyl group with 1 to 20 carbon atoms are replaced by fluorine atoms.

[0152] As the monovalent fluorinated alicyclic hydrocarbon group with 3 to 20 carbon atoms represented by R 14, examples include those monocyclic or polycyclic hydrocarbon groups with 3 to 20 carbon atoms in which some or all of the hydrogen atoms are replaced by fluorine atoms.

[0153] As R 14, it is preferably a fluorinated chain hydrocarbon group, more preferably a fluorinated alkyl group, and even more preferably 2,2,2-trifluoroethyl, 1,1,1,3,3,3-hexafluoropropyl, 5,5,5-trifluoro-1,1-diethylpentyl and 1,1,1,2,2,3,3-heptafluoro-6-methyl-4-octyl.

[0154] When the high-fluorine content resin has structural unit (VIII), the lower limit of the content ratio of structural unit (VIII) among all structural units constituting the high-fluorine content resin is preferably 50 mol%, more preferably 60 mol%, further preferably 70 mol%, and especially preferably 80 mol%. The upper limit of the content ratio is preferably 100 mol%, more preferably 98 mol%, and further preferably 95 mol%. By setting the content ratio of structural unit (VIII) within the aforementioned range, the mass content of fluorine atoms in the high-fluorine content resin can be adjusted more appropriately, further promoting its biased presence on the surface of the resist film.

[0155] In addition to structural unit (VIII), high-fluorine content resins may also have fluorine-containing structural units (hereinafter also referred to as structural units (IX)) as represented by the following formula (f-1). By having structural units (IX), the high-fluorine content resin has increased solubility in alkaline developing solutions, which can suppress the generation of developing defects.

[0156] Structural unit (IX) is broadly classified into two cases: one with a base-soluble group (x) and the other with a group (y) that dissociates under the action of a base and has increased solubility in alkaline developing solution (hereinafter also referred to as "base-dissociatable group"). Similar to (x) and (y), in the above formula (f-1), RC is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group; RD is a single bond, a (s+1) valent hydrocarbon group with 1 to 20 carbon atoms, with an oxygen atom, a sulfur atom, -NR dd-, a carbonyl group, -COO-, or -CONH- bonded to the RK side of the hydrocarbon group; or a structure in which a portion of the hydrogen atom of the hydrocarbon group is replaced by an organic group with a heteroatom. R dd is a hydrogen atom or a monovalent hydrocarbon group with 1 to 10 carbon atoms. s is an integer from 1 to 3.

[0157] When the structural unit (IX) has a base-soluble group (x), RF is a hydrogen atom, A1 is an oxygen atom, -COO-*, or -SO2O-*, where * indicates the bond with RF. W1 is a single bond, a hydrocarbon group with 1-20 carbon atoms, or a divalent fluorinated hydrocarbon group. When A1 is an oxygen atom, W1 is a fluorinated hydrocarbon group with a fluorine atom or fluoroalkyl group on the carbon atom bonded to A1. RK is a single bond or a divalent organic group with 1-20 carbon atoms. When s is 2 or 3, multiple RK, W1, A1, or RF can be the same or different. Having a base-soluble group (x) in the structural unit (IX) can improve the affinity for alkaline developers and suppress development defects. The structural unit (IX) with a base-soluble group (x) is preferably the case where A1 is an oxygen atom and W1 is 1,1,1,3,3,3-hexafluoro-2,2-methanediyl.

[0158] When structural unit (IX) has a base-dissociable group (y), RF is a monovalent organic group with 1-30 carbon atoms, A1 is an oxygen atom, -NR aa-, -COO-*, or -SO 2O-*, where Raaa is a hydrogen atom or a monovalent hydrocarbon group with 1-10 carbon atoms, and * indicates the bond with RF. W1 is a single bond or a divalent fluorinated hydrocarbon group with 1-20 carbon atoms. RK is a single bond or a divalent organic group with 1-20 carbon atoms. When A1 is -COO-* or -SO 2O-*, W1 or RF has a fluorine atom on the carbon atom bonded to A1 or on the adjacent carbon atom. When A1 is an oxygen atom, W1 and RK are single bonds, RD is a structure with a carbonyl group bonded to the RK side of a hydrocarbon group with 1-20 carbon atoms, and RF is an organic group with a fluorine atom. When s is 2 or 3, multiple RK, W1, A1, or RF can be the same or different. By having a (y) alkali-dissociative group in the structural unit (IX), the surface of the resist film changes from hydrophobic to hydrophilic during the alkaline development step, which can greatly improve the affinity for the developer and more effectively suppress development defects. The structural unit (IX) with the (y) alkali-dissociative group is preferably A1 is -COO-* and RF or W1 or both have fluorine atoms.

[0159] From the viewpoint of providing the copolymerization of the monomers of the structural unit (IX), hydrogen atoms and methyl groups are preferred as RC, and methyl groups are even more preferred.

[0160] When RK is a divalent organic group, it is preferably a group with a lactone structure, more preferably a polycyclic group with a lactone structure, and even more preferably a group with a norbornene lactone structure.

[0161] When a high-fluorine resin has structural units (IX), the lower limit of the proportion of structural unit (IX) among all the structural units constituting it is preferably 10 mol%, more preferably 20 mol%, even more preferably 30 mol%, and particularly preferably 35 mol%. The upper limit of this proportion is preferably 90 mol%, more preferably 75 mol%, and even more preferably 60 mol%. Setting the proportion of structural unit (IX) within the above range can further improve the water repellency of the resist film during immersion exposure.

[0162] The Mw of the high-fluorine content resin is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more, and particularly preferably 5,000 or more. The Mw is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 20,000 or less, and particularly preferably 15,000 or less.

[0163] High-fluorine-content resins typically have an Mw / Mn ratio of 1 or higher, preferably 1.1 or higher. The Mw / Mn ratio is typically 5 or lower, preferably 3 or lower, even better 2.5 or lower, and still more preferably 2.2 or lower.

[0164] The high-fluorine content resin, relative to 100 parts by weight of the base resin, preferably contains 0.1 parts by weight or more, more preferably 0.5 parts by weight or more, further preferably 1 part by weight or more, and particularly preferably 1.5 parts by weight or more. The content is preferably 12 parts by weight or less, more preferably 10 parts by weight or less, further preferably 8 parts by weight or less, and particularly preferably 5 parts by weight or less.

[0165] By setting the content of the high-fluorine resin within the aforementioned range, the high-fluorine resin can be more effectively concentrated on the surface of the resist film. As a result, during development, dissolution of the upper part of the pattern can be suppressed, and the rectangularity of the pattern can be improved. The radiosensitive linear resin composition may also contain one or more high-fluorine resins.

[0166] (Synthesis method of high fluorine content resin) The method for synthesizing high-fluorine-content resins is the same as the method for synthesizing the aforementioned basic resins.

[0167] <Acid diffusion control agent> The acid diffusion control agent is represented by the following formula (α).

[0168] In formula (α), Rw is a monovalent organic group, hydroxyl group, or amino group with 1 to 20 carbon atoms; Lq is a divalent linker; Z+ is a monovalent radiosensitive linear ononium cation; q1 is an integer from 1 to 4; q2 is an integer from 0 to 3; q3 is an integer from 1 to 3; and the upper limit of q1 + q2 + q3 is 6. When multiple Rw exist, they may be the same or different. When multiple Lq exist, they may be the same or different. Furthermore, an organic group refers to a group containing at least one carbon atom.

[0169] Examples of monovalent organic groups with 1 to 20 carbon atoms represented by R w include: monovalent hydrocarbon groups with 1 to 20 carbon atoms, groups containing divalent heteroatoms at the carbon-carbon inter-carbon or bond side of the hydrocarbon group, groups formed by substituting some or all of the hydrogen atoms of the hydrocarbon group with monovalent heteroatoms, or combinations of two or more of these.

[0170] Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms include: Alkyl groups such as methyl, ethyl, propyl, and butyl; vinyl, propylene, butenyl, and other alkenyl groups; Alynyl, propynyl, butynyl, and other chain hydrocarbon groups; Cyclopropyl, cyclopentyl, cyclohexyl, cyclooctyl, norbornyl, adamantyl, and other cycloalkyl groups; Cyclopropenyl, cyclopentenyl, cyclohexenyl, norbornenyl, and other cycloalkenyl alicyclic hydrocarbon groups; Aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthracene; Aromatic hydrocarbon groups such as benzyl, phenethyl, naphthylmethyl, and aralkyl groups.

[0171] Examples of divalent heteroatom-containing groups include: -O-, -CO-, -CO-O-, -S-, -CS-, -SO2-, -NR'-, and groups formed by combining two or more of these. R' is a hydrogen atom or a monovalent hydrocarbon group.

[0172] Examples of monovalent heteroatom-containing groups include halogen atoms such as fluorine, chlorine, bromine, and iodine, as well as hydroxyl, carboxyl, cyano, amino, and mercapto (-SH).

[0173] As a divalent linker represented by L q, examples include groups formed by further removing a hydrogen atom from monovalent organic groups with carbon numbers from 1 to 20 represented by R w.

[0174] In the given formula (α), q1 is preferably an integer from 1 to 3, more preferably 2 or 3. q2 is preferably 0 or 1. q3 is preferably 1 or 2, more preferably 1.

[0175] The anionic portion of the acid diffusion control agent represented by the formula (α) is not limited, but the following examples can be listed.

[0176]

[0177]

[0178]

[0179]

[0180]

[0181] The monovalent radiosensitive linear ononium cation represented by Z+ can preferably adopt the structure shown above as the ononium cation portion represented by (Q-1) and (Q-2) in the structural unit (VII) that can be included in the resin. Z+ preferably includes an aromatic ring structure having fluorine atoms.

[0182] The acid diffusion control agent represented by formula (α) can also be synthesized by known methods, especially salt exchange reaction.

[0183] The acid diffusion control agent represented by formula (α) can be used alone or in combination with two or more. The lower limit of the acid diffusion control agent content relative to 100 parts by weight of the base resin is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, and even more preferably 1.5 parts by weight or more. Furthermore, relative to 100 parts by weight of the resin, it is preferably 12 parts by weight or less, more preferably 8 parts by weight or less, and even more preferably 5 parts by weight or less. This allows for excellent sensitivity or CDU performance and residual film rate when forming resist patterns. Furthermore, other acid diffusion control agents can be used in combination with the acid diffusion control agent represented by formula (α) in the radiosensitive linear resin composition of this embodiment. Other acid diffusion control agents can be known substances.

[0184] <Radiosensitive linear acid generator> The radiosensitive linear resin composition preferably further includes a radiosensitive linear acid generator, which, upon irradiation (exposure) with radiation, produces an acid with a lower pKa than the acid produced by the acid diffusion control agent. Because the radiosensitive linear resin composition contains the radiosensitive linear acid generator, the acid generated during exposure causes the acid-dissociating groups in the resin to dissociate, thereby generating carboxyl groups, etc. As a result, the polarity of the resin in the exposed section increases; the resin in the exposed section is soluble in the developer when developed in an alkaline aqueous solution, but sparingly soluble in the developer when developed with an organic solvent.

[0185] The radiosensitive linear acid generator preferably comprises an organic acid anion moiety and an onium cation moiety. The organic acid anion moiety is preferably at least one selected from the group consisting of sulfonate anions and sulfadiazine anions. Examples of acids generated by exposure, corresponding to the organic acid anion moiety, include sulfonic acids and sulfadiazine. The organic acid anion moiety preferably comprises an iodine-substituted aromatic ring structure.

[0186] Among them, as a radiosensitive linear acid generator that provides sulfonic acid through exposure, a compound having one or more fluorine atoms or fluorinated hydrocarbon groups bonded to the carbon atom adjacent to the sulfonate anion is preferred.

[0187] The radiosensitive linear acid generator is preferably represented by the following formula (A-1) or (A-2).

[0188]

[0189] In formulas (A-1) and (A-2), L1 is a single bond, an ether bond, or an ester bond, or an alkyl group with 1 to 6 carbon atoms that may contain ether or ester bonds in the chain. The alkyl group may be linear, branched, or cyclic.

[0190] R1 is a hydroxyl, carboxyl, fluorine, chlorine, bromine, or amino group, or may contain a fluorine, chlorine, bromine, hydroxyl, amino, or an alkyl group with 1 to 20 carbon atoms that has 1 to 10 alkoxy groups, an alkoxy group with 1 to 20 carbon atoms, an alkoxycarbonyl group with 2 to 10 carbon atoms, an acetoxy group with 2 to 20 carbon atoms, or an alkylsulfonoxy group with 1 to 20 carbon atoms, or -NR 8-C(=O)-R 9 or -NR 8-C(=O)-OR 9. R8 is a hydrogen atom, or may contain a halogen atom, a hydroxyl group, an alkoxy group with 1 to 6 carbon atoms, an acetyl group with 2 to 6 carbon atoms, or an alkyl group with 2 to 6 carbon atoms that has 1 to 6 carbon atoms that has 2 to 6 carbon atoms. R 9 is an alkyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and may contain a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, a cellulose group having 2 to 6 carbon atoms, or a cellulose oxy group having 2 to 6 carbon atoms. The aforementioned alkyl, alkoxy, alkoxycarbonyl, cellulose oxy, cellulose, and alkenyl groups may be linear, branched, or cyclic.

[0191] Among these, R1 is preferably a hydroxyl group, -NR8-C(=O)-R9, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, etc.

[0192] R2 is a single bond or a divalent linker with 1 to 20 carbon atoms when p is 1, and a trivalent or tetravalent linker with 1 to 20 carbon atoms when p is 2 or 3. The linker may contain oxygen, sulfur or nitrogen atoms.

[0193] Rf1 through Rf4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one of them is a fluorine atom or a trifluoromethyl group. Additionally, Rf1 and Rf2 can combine to form a carbonyl group. Preferably, both Rf3 and Rf4 are fluorine atoms.

[0194] R3, R4, R5, R6, and R7 are each independently a monovalent hydrocarbon group with 1 to 20 carbon atoms, which may contain heteroatoms. When the onium cation moiety of the radiosensitive linear acid generator has fluorine, at least one of R3, R4, and R5 contains more than one fluorine atom, and at least one of R6 and R7 contains more than one fluorine atom. Furthermore, any two of R3, R4, and R5 can be bonded to each other and form a ring together with the bonded sulfur atoms. The monovalent hydrocarbon group can be linear, branched, or cyclic, and specific examples include alkyl groups with 1 to 12 carbon atoms, alkenyl groups with 2 to 12 carbon atoms, alkynyl groups with 2 to 12 carbon atoms, aryl groups with 6 to 20 carbon atoms, and aralkyl groups with 7 to 12 carbon atoms. In addition, some or all of the hydrogen atoms of these groups may be substituted with hydroxyl, carboxyl, halogen, cyano, amide, nitro, mercapto, sulopentalide, urethane or strontium salt-containing groups, and some of the carbon atoms of these groups may be substituted with ether, ester, carbonyl, carbonate or sulfonate bonds.

[0195] p is an integer satisfying 1 ≤ p ≤ 3. q and r are integers satisfying 0 ≤ q ≤ 5, 0 ≤ r ≤ 3, and 0 ≤ q + r ≤ 5. q is preferably an integer satisfying 1 ≤ q ≤ 3, more preferably 2 or 3. r is preferably an integer satisfying 0 ≤ r ≤ 2.

[0196] Examples of the organic acid anion moiety of the radiosensitive linear acid generator represented by formulas (A-1) and (A-2) are shown below, but are not limited thereto. Furthermore, the following are all organic acid anion moiety with an iodine-substituted aromatic ring structure, but organic acid anion moiety without an iodine-substituted aromatic ring structure may preferably adopt a structure in which the iodine atom in the following formula is substituted by an atom or group other than the iodine atom, such as a hydrogen atom or other substituent.

[0197]

[0198]

[0199]

[0200]

[0201]

[0202]

[0203]

[0204]

[0205]

[0206]

[0207]

[0208]

[0209]

[0210]

[0211]

[0212]

[0213]

[0214]

[0215]

[0216]

[0217]

[0218]

[0219]

[0220]

[0221] The onium cation portion in the radiosensitive linear acid generator represented by formula (A-1) can preferably be the structure shown in (Q-1) and (Q-2) as the onium cation portion in the structural unit (VII) that can be included in the resin.

[0222] (Structure of the anionic portion of other organic acid radicals (1)) The radiosensitive linear acid generator may also be based on the organic acid anion portion of the radiosensitive linear acid generator represented by formulas (A-1) and (A-2), or instead of those, include the structure represented by formula (bd1) as the organic acid anion portion.

[0223]

[0224] In the formula (bd1), R x1 to R x4 are each independently a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or represent a ring structure formed by the combination of two or more of these. Ry1 to Ry2 can each be a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or represent a ring structure formed by their combination. It can be a double bond or a single bond. R z1 to R z4 are each independently a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or represent a ring structure formed by the combination of two or more of these. Among them, at least one of R x1 to R x4, R y1 to R y2 and R z1 to R z4 has a sulfonate anion structure.

[0225] The hydrocarbon groups in Rx1~Rx4, Ry1~Ry2 and Rz1~Rz4 can be aliphatic hydrocarbon groups or aromatic hydrocarbon groups, and can be cyclic hydrocarbon groups or chain hydrocarbon groups, respectively. For example, the hydrocarbon groups that may have substituents among Rx1~Rx4, Ry1~Ry2 and Rz1~Rz4 can be listed as: cyclic groups that may have substituents, chain alkyl groups that may have substituents, or chain alkenyl groups that may have substituents.

[0226] As the hydrocarbon group among Rx1~Rx4, Ry1~Ry2 and Rz1~Rz4, the hydrocarbon group is preferably a cyclic group that may have substituents or a chain alkyl group that may have substituents.

[0227] In formula (bd1), Ry1 to Ry2 can also bond to each other to form a ring structure. The ring structure formed by Ry1 to Ry2 shares one side of the six-membered ring in formula (bd1) (the bonds between the carbon atoms bonded by Ry1 and Ry2 respectively). This ring structure can be an alicyclic hydrocarbon or an aromatic hydrocarbon. In addition, this ring structure can also form a polycyclic structure with other ring structures.

[0228] In terms of the short diffusion of acid generated by exposure and the diffusion control of acid, the ring structure formed by Ry1~Ry2 is preferably an aromatic hydrocarbon that can be substituted.

[0229] In formula (bd1), two or more of R z1 to R z4 can bond to each other to form a ring structure. For example, R z1 can form a ring structure with any one of R z2 to R z4. Specific examples include: ring structures formed by sharing one side of the six-membered ring in formula (bd1) (the bonds between the carbon atoms bonded by R z1 and R z2 and the carbon atoms bonded by R z3 and R z4), ring structures formed by the bond between R z1 and R z2, and ring structures formed by the bond between R z3 and R z4. The ring structures formed by two or more of R z1 to R z4 can be alicyclic hydrocarbons or aromatic hydrocarbons, preferably aromatic hydrocarbons. Furthermore, this ring structure can also form polycyclic structures with other ring structures.

[0230] In terms of the diffusion control of the acid generated by exposure, the ring structure formed by two or more of R z1 to R z4 is preferably a ring structure of one side of the six-membered ring in the common formula (bd1) (the carbon atoms bonded to R z1 and R z2, and the carbon atoms bonded to R z3 and R z4), and more preferably an aromatic ring structure.

[0231] In formula (bd1), two or more R x1 to R x4 can bond together to form a ring structure. For example, R x1 can form a ring structure with any one of R x2 to R x4. The ring structure formed by two or more of R x1 to R x4 can be an alicyclic hydrocarbon or an aromatic hydrocarbon. In addition, this ring structure can also form a polycyclic structure with other ring structures.

[0232] Regarding the diffusion control of the acid, the ring structure formed by two or more of R x1 to R x4 is preferably an alicyclic hydrocarbon. Furthermore, regarding the diffusion control of the acid, the ring structure formed by two or more of R x1 to R x4 is preferably a cross-linked ring structure formed by at least one of R x1 to R x2 and at least one of R x3 to R x4 bonded together, and more preferably the ring structure is an alicyclic hydrocarbon.

[0233] In the above formula (bd1), at least one of Rx1~Rx4, Ry1~Ry2, and Rz1~Rz4 has a sulfonate anion structure. When the number of sulfonate anion structures is n, the organic acid anion portion as a whole becomes an n-valent anion. n is an integer greater than or equal to 1.

[0234] In the organic anionic portion represented by formula (bd1), Rx1~Rx4, Ry1~Ry2, and Rz1~Rz4 can each be a sulfonate anion structure. When two or more of Rx1~Rx4 form a ring structure, the carbon atom forming the ring structure or the hydrogen atom bonded to the carbon atom can be replaced by a sulfonate anion structure. When two or more of Ry1~Ry2 form a ring structure, the carbon atom forming the ring structure or the hydrogen atom bonded to the carbon atom can be replaced by a sulfonate anion structure. When two or more of Rz1~Rz4 form a ring structure, the carbon atom forming the ring structure or the hydrogen atom bonded to the carbon atom can be replaced by a sulfonate anion structure.

[0235] Specific examples of the organic anionic portion represented by the above formula (bd1) are shown below, but are not limited thereto.

[0236]

[0237] These radiosensitive linear acid generators can be used alone or in combination of two or more. The lower limit of the content of the radiosensitive linear acid generator relative to 100 parts by weight of the base resin is preferably 0.5 parts by weight, more preferably 1 part by weight, even more preferably 1.5 parts by weight, and particularly preferably 2 parts by weight. The upper limit of the content relative to 100 parts by weight of the resin is preferably 20 parts by weight or less, more preferably 18 parts by weight or less, even more preferably 15 parts by weight or less, and particularly preferably 12 parts by weight or less. This allows for excellent sensitivity or CDU performance when forming resist patterns.

[0238] Solvent The radiosensitive linear resin composition of this embodiment contains a solvent. The solvent is not particularly limited as long as it is capable of dissolving or dispersing at least the base resin, the acid diffusion control agent, and any additives as needed.

[0239] Examples of solvents include: alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, and hydrocarbon solvents.

[0240] Examples of alcohol-based solvents include: Monool solvents with 1 to 18 carbon atoms, such as isopropanol, 4-methyl-2-pentanol, 3-methoxybutanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, and diacetone alcohol; Ethylene glycol, 1,2-propanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, and other polyol solvents with 2 to 18 carbon atoms; Polyol partial ether solvents, etc., are formed by etherifying a portion of the hydroxyl groups in the polyol solvent.

[0241] Examples of ether-based solvents include: Dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether; Tetrahydrofuran, tetrahydropyran, and other cyclic ether solvents; Ether solvents containing aromatic rings, such as diphenyl ether and anisole (methyl phenyl ether); Polyol ether solvents, etc., are formed by etherifying the hydroxyl groups of the polyol solvent.

[0242] Examples of ketone solvents include: acetone, butanone, methyl isobutyl ketone, and other chain-like ketone solvents. Cyclopentanone, cyclohexanone, methylcyclohexanone, and other cyclic ketone solvents; 2,4-Pentanedione, acetone, acetophenone, etc.

[0243] Examples of amide-based solvents include cyclic amide solvents such as N,N'-dimethylimidazolidineone and N-methylpyrrolidone. N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpropionic acid and other chain acetamide solvents.

[0244] Examples of ester-based solvents include: Monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate; Diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate are polyol partial ether acetate solvents; Lactone solvents such as γ-butyrolactone and valproic acid; Diethyl carbonate, ethyl carbonate, propyl carbonate, and other carbonate solvents; Solvents consisting of polycarboxylic acid diesters such as propylene glycol diacetate, methoxytriethylene glycol acetate, diethyl oxalate, ethyl acetate, ethyl lactate, and diethyl phthalate.

[0245] Examples of hydrocarbon solvents include: aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; Aromatic hydrocarbon solvents such as benzene, toluene, diisopropylbenzene, and n-pentylnaphthalene.

[0246] Among these, ester-based solvents and ketone-based solvents are preferred, more preferably polyol partial ether acetate-based solvents, cyclic ketone-based solvents, and lactone-based solvents, and even more preferably propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, cyclohexanone, γ-butyrolactone, and ethyl lactate. The radiosensitive linear resin composition may also contain one or more solvents.

[0247] <Other Selected Ingredients> In addition to the aforementioned components, the radiosensitive linear resin composition may also contain other optional components. Examples of such optional components include: crosslinking agents, accelerators, surfactants, compounds containing alicyclic skeletons, sensitizers, etc. These other optional components may also be used in combination, one or more at a time.

[0248] <Preparation Method of Radiation-Inducing Linear Resin Composition> The radiosensitive linear resin composition can be prepared, for example, by mixing resin, acid diffusion control agent, and solvent with other optional components as needed in a prescribed ratio. The resin composition is preferably filtered after mixing using, for example, a filter with a pore size of approximately 0.05 to 0.2 μm. The solid content concentration of the radiosensitive linear resin composition is typically 0.1 to 50% by mass, preferably 0.5 to 30% by mass, and more preferably 1 to 20% by mass.

[0249] Pattern Formation Methods The pattern forming method of this embodiment includes: Step (1) (hereinafter also referred to as "resist film formation step") involves directly or indirectly coating the radiosensitive linear resin composition onto a substrate to form a resist film. The step of exposing the resist film (2) (hereinafter also referred to as the "exposure step"); and Step (3) of developing the exposed resist film (hereinafter also referred to as the "development step").

[0250] According to the pattern forming method, high-quality resist patterns can be formed by using the radiosensitive linear resin composition with excellent sensitivity or CDU performance in the exposure step. The steps are described below.

[0251] [Resist Film Formation Steps] In this step (step (1) above), a resist film is formed using the aforementioned radiosensitive linear resin composition. Examples of substrates for forming this resist film include silicon wafers, silicon dioxide- or aluminum-coated wafers, and other previously known materials. Alternatively, organic or inorganic antireflective films disclosed in Japanese Patent Application Publication No. 6-12452 or Japanese Patent Application Publication No. 59-93448 may be formed on the substrate. Examples of coating methods include spin coating, cast coating, and roll coating. After coating, pre-baking (PB) may be performed as needed to allow the solvent in the coating to evaporate. The PB temperature is typically 60-150°C, preferably 80-140°C. The PB time is typically 5-600 seconds, preferably 10-300 seconds. The thickness of the formed resist film is preferably 10-1,000 nm, more preferably 10-500 nm.

[0252] In the case of immersion exposure, regardless of the presence or absence of water-repellent polymer additives such as high-fluorine content resin in the radiosensitive linear resin composition, a immersion protective film that is insoluble in the immersion liquid can 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-removable protective film that is peeled off by a solvent before the development step (e.g., see Japanese Patent Application Laid-Open No. 2006-227632) or a developer-removable protective film that is peeled off simultaneously with the development step (e.g., see WO2005-069076 and WO2006-035790) can be used. From the viewpoint of yield, a developer-removable immersion protective film is preferred.

[0253] [Exposure Steps] In this step (step (2) above), a photomask (which may be impregnated by a liquid medium such as water) exposes the resist film formed in step (1) to radiation. Depending on the linewidth of the target pattern, the radiation used in the exposure can be: visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), X-rays, gamma rays, and other electromagnetic waves; electron beams, alpha rays, and other charged particle beams. Among these, far ultraviolet light, electron beams, and EUV are preferred, ArF excimer laser (wavelength 193 nm), KrF excimer laser (wavelength 248 nm), electron beams, and EUV are more preferred, and electron beams and EUV with wavelengths below 50 nm, which are positioned as next-generation exposure technologies, are even more preferred.

[0254] When exposure is performed by immersion exposure, the immersion solution used can include, for example, water or a fluorine-based inert liquid. Preferably, the immersion solution is transparent to the exposure wavelength and has a temperature coefficient of refractive index that is as small as possible to minimize the strain of the optical image projected onto the film. However, especially when the exposure light source is an ArF excimer laser (wavelength 193 nm), in addition to the above points, water is preferred in terms of ease of acquisition and ease of operation. When using water, additives that reduce the surface tension of water and increase interfacial activity can be added in small proportions. These additives are preferably those that do not dissolve the resist film on the wafer and have no effect on the optical coating on the lower surface of the lens. Distilled water is preferred.

[0255] Preferably, post-exposure baking (PEB) is performed after the above exposure. In this method, the acid generated by the radiosensitive linear acid generator during exposure promotes the dissociation of acid-dissociating groups in the resin or similar materials on the exposed areas of the resist film. PEB creates a difference in solubility of the developer between the exposed and unexposed areas. The PEB temperature is typically 50–180°C, preferably 80–130°C. The PEB time is typically 5–600 seconds, preferably 10–300 seconds.

[0256] [Developing Steps] In this step (step (3)), the resist film exposed in step (2), i.e., the exposure step, is developed. This forms a predetermined resist pattern. Generally, after development, the film is rinsed with a solution such as water or alcohol and then dried.

[0257] As the developing solution used in the above-mentioned developing process, in the case of alkaline developing, examples include alkaline aqueous solutions prepared by dissolving at least one of the following alkaline compounds: sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyl diethylamine, ethyl dimethylamine, 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 solution of TMAH is preferred, and a 2.38% by mass aqueous solution of TMAH is even more preferred.

[0258] In addition, when developing with organic solvents, examples of organic solvents include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, etc., or solvents containing organic solvents. The organic solvents may include one or more solvents listed as solvents for the aforementioned radiosensitive linear resin composition. Among these, ester solvents and ketone solvents are preferred. Ester solvents are preferably acetate solvents, more preferably n-butyl acetate or amyl acetate. Ketone solvents are preferably chain ketones, more preferably 2-heptanone. The content of organic solvent in the developing solution is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, and particularly preferably 99% by mass or more. Components other than organic solvents in the developing solution may include water, silicone oil, etc.

[0259] Examples of development methods include: immersing the substrate in a tank filled with developer for a certain period of time (immersion method); using surface tension to cause the developer to accumulate on the substrate surface and remain still for a certain period of time for development (puddle method); spraying developer onto the substrate surface (spraying method); and continuously applying developer onto a substrate rotating at a certain speed while scanning the developer application nozzle at a certain speed (dynamic distribution method), etc. [Example]

[0260] The present invention is illustrated below with synthetic examples, embodiments, and comparative examples, but the invention is not limited thereto. Methods for determining various physical properties are shown below.

[0261] [Mw and Mn] The Mw and Mn of the polymers were determined by gel permeation chromatography (GPC) using GPC columns manufactured by Tosoh (two "G2000HXL", one "G3000HXL", and one "G4000HXL") under the following conditions. Dissolution solution: Tetrahydrofuran (manufactured by 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℃ Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0262] The following shows the structures of the radiosensitive linear acid generators PAG1 to PAG12, which are strontium salts or ferrous salts used in the radiosensitive linear resin compositions of the embodiments.

[0263]

[0264] [Synthesis Example] Synthesis of base resins (P-1) to (P-15) and base resin (Pc-1) The monomers were combined and copolymerized in tetrahydrofuran (THF) solvent, crystallized in methanol, and then repeatedly washed with hexane. Separation and drying were then performed to obtain base resins (P-1) to (P-15) and base resin (Pc-1) with the compositions shown below. The values ​​labeled for each structural unit represent its content proportion (totaling 1). The composition of the obtained base resins was confirmed by 1H nuclear magnetic resonance (NMR), and Mw and dispersion (Mw / Mn) were confirmed using the aforementioned GPC (solvent: THF, standard: polystyrene).

[0265] P-1: Mw=7,800, Mw / Mn=1.8 P-2: Mw=8,500, Mw / Mn=1.7 P-3: Mw=10, 100, Mw / Mn=1.6 P-4: Mw=8,300, Mw / Mn=1.7 P-5: Mw=9,400, Mw / Mn=1.7 P-6: Mw=7,200, Mw / Mn=1.8 P-7: Mw=8,000, Mw / Mn=1.7 P-8: Mw=9,800, Mw / Mn=1.7 P-9: Mw=9,200, Mw / Mn=1.7 P-10: Mw=8,900, Mw / Mn=1.6 P-11: Mw=7,500, Mw / Mn=1.7 P-12: Mw=8,700, Mw / Mn=1.7 P-13: Mw=8,200, Mw / Mn=1.7 P-14: Mw=9,500, Mw / Mn=1.7 P-15: Mw=8,800, Mw / Mn=1.7 Pc-1: Mw=9,300, Mw / Mn=1.7

[0266]

[0267]

[0268]

[0269]

[0270]

[0271] [Example, Comparative Example] The components shown in Table 1 were dissolved in 100 ppm of 3M FC-4430 as a surfactant to obtain a solution. The obtained solution was filtered through a 0.2 μm filter to prepare the radiosensitive linear resin composition.

[0272] In Table 1, the components are as follows.

[0273] Acid diffusion control agents (Q-1)~(Q-18) and acid diffusion control agents (Qc-1)~(Qc-2)

[0274]

[0275]

[0276] Solvent: Propylene glycol monomethyl ether acetate (PGMEA) γ-Butyrolactone (GBL) Cyclohexanone (CHN) Propylene glycol monomethyl ether (PGME) diacetone alcohol (DAA) Ethyl lactate (EL)

[0277] High-fluorine content resin F-1: Mw=8,900, Mw / Mn=2.0

[0278] [Evaluation of sensitivity based on EUV exposure] Using a spin coater (Tokyo Electron Limited CLEAN TRACK ACT12), the lower antireflective film forming composition (Brewer Science, Inc.'s ARC66) was applied to a 12-inch silicon wafer, followed by heating at 205°C for 60 seconds to form a lower antireflective film with an average thickness of 105 nm. The various radiosensitive linear resin compositions shown in Table 1 were then applied to this lower antireflective film using the same spin coater, and the wafer was heated at 130°C for 60 seconds (PB). The wafer was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 55 nm. This resist film was then exposed using an EUV scanner (ASML NXE3300 (NA 0.33, σ 0.9 / 0.6, quadrupole illumination, mask with a 46 nm pitch hole pattern on the wafer, +20% tolerance)). PEB was applied for 60 seconds on a 120°C heated plate, followed by development with a 2.38% (w / w) tetramethylammonium hydroxide (TMAH) aqueous solution for 30 seconds to form a resist pattern with 23 nm apertures and 46 nm spacing. The exposure value for forming this 23 nm aperture and 46 nm spacing resist pattern was set as the optimal exposure value (Eop), and the optimal exposure value was set as the sensitivity (mJ / cm²).

[0279] [CDU's Evaluation] The resist pattern with 23 nm apertures and a 46 nm spacing was formed by irradiating with the Eop value calculated above, following the same procedure as described above. The resist pattern was observed from the top of the pattern using a scanning electron microscope (Hitachi High-Technologies CG-5000). The aperture diameter at 16 points within a 500 nm range was measured and the average value was calculated. Additionally, the average value of a total of 500 points was measured at arbitrary points. The 3σ value was calculated from the distribution of the measured values, and this 3σ value was set as the evaluation value (nm) for CDU performance. Regarding CDU performance, the smaller the evaluation value, the smaller the aperture deviation over a long period, indicating better performance. The results are shown in Table 1.

[0280] [Evaluation of residual film in the exposed section] A resist film with an average thickness of 55 nm was formed in the same manner as described above, and then exposed using the aforementioned optimal exposure value (Eop). The wafer before and after exposure was cut, and its cross-section was observed using a scanning electron microscope (Hitachi High-Technologies S-5500) to measure the thickness of the resist film. The ratio of the film thickness after exposure to the film thickness before exposure was calculated and set as the residual film rate (%). Cases with a residual film rate of 70% or more were designated as "A", cases with a residual film rate of 60% or more but less than 70% were designated as "B", and cases with a residual film rate of less than 50% were designated as "C". Residual film yield (%) = (Film thickness after exposure at optimal exposure (nm) / Film thickness before exposure (nm)) × 100

[0281] [Reference Evaluation of Storage Stability] Test samples of the radiosensitive linear resin compositions obtained in the aforementioned examples and comparative examples were prepared after being stored at 35°C for one month and after being stored at -15°C for one month. The sensitivity of these test samples was evaluated in the same manner as described above. The sensitivity after storage at -15°C for one month and the sensitivity after storage at 35°C for one month were measured respectively. Cases where the difference between the two was within 1.0% were designated as "A", cases where the difference was greater than 1.0% but within 1.5% were designated as "B", and cases where the difference was greater than 1.5% were designated as "C".

[0282] Table 1 Base resin (parts by weight) PAG (parts by weight) Acid diffusion control agent (parts by weight) Solvent (parts by mass) Additives (parts by weight) Sensitivity [mJ / cm 2] CDU [nm] Residual film rate Preservation stability Example 1 P-1 (100) PAG1 (4.0) Q-1 (2.0) PGME / EL (2,000 / 500) F-1 (3.0) 13 2.2 A A Example 2 P-2 (100) PAG2 (5.5) Q-2 (2.0) PGMEA / PGME / EL (1,500 / 500 / 500) F-1 (3.0) 14 2.2 A B Example 3 P-3 (100) PAG3 (7.5) Q-3 (3.0) PGMEA / EL (2,000 / 500) F-1 (3.0) 15 2.2 A A Example 4 P-4 (100) PAG4 (7.0) Q-4 (3.0) PGMEA / EL (2,000 / 500) F-1 (3.0) 15 2.2 A B Example 5 P-5 (100) PAG5 (7.5) Q-5 (3.0) PGMEA / EL (2,000 / 500) F-1 (3.0) 13 2.2 A A Example 6 P-6 (100) PAG6 (8.0) Q-6 (3.0) PGMEA / EL (2,000 / 500) F-1 (3.0) 13 2.2 A B Example 7 P-7 (100) PAG1 (7.5) Q-7 (3.5) PGMEA / GBL (2,200 / 300) F-1 (3.0) 14 2.2 A A Example 8 P-8 (100) PAG7 (7.5) Q-8 (3.0) PGMEA / DAA (2,000 / 500) F-1 (3.0) 14 2.2 A A Example 9 P-9 (100) PAG3 (7.0) Q-9 (3.5) PGMEA / PGME (2,000 / 500) F-1 (3.0) 15 2.2 A A Example 10 P-10 (100) PAG8 (7.0) Q-10 (3.0) PGMEA / PGME (2,000 / 500) F-1 (3.0) 12 2.2 A A Example 11 P-1 (100) PAG9 (2.5) Q-11 (2.5) PGMEA / CHN / PGME (400 / 2,000 / 100) F-1 (3.0) 15 2.2 A B Example 12 P-5 (100) PAG9 (7.5) Q-12 (3.0) PGMEA / PGME (2,000 / 500) F-1 (3.0) 14 2.2 A B Example 13 P-11 (100) PAG10 (9.0) Q-13 (3.5) PGMEA / GBL / PGME (2,200 / 200 / 100) F-1 (3.0) 15 2.2 A B Example 14 P-12 (100) PAG3 (4.0) Q-14 (3.5) PGMEA / GBL (2,200 / 300) F-1 (3.0) 12 2.2 A A Example 15 P-13 (100) PAG11 (3.5) Q-15 (3.0) PGMEA / DAA (2,000 / 500) F-1 (3.0) 13 2.2 A A Example 16 P-4 (100) PAG12 (7.5) Q-16 (3.0) PGMEA / DAA (2,000 / 500) F-1 (3.0) 14 2.2 A A Example 17 P-14 (100) PAG9 (7.5) Q-17 (2.5) PGMEA / DAA (2,000 / 500) F-1 (3.0) 14 2.2 A B Example 18 P-15 (100) PAG8 (7.5) Q-18 (2.5) PGMEA / EL (2,000 / 500) F-1 (3.0) 12 2.2 A A Comparative Example 1 P-8 (100) PAG7 (7.5) Qc-1 (3.0) PGMEA / DAA (2,000 / 500) F-1 (3.0) 14 2.2 B A Comparative Example 2 P-8 (100) PAG7 (7.5) Qc-2 (3.0) PGMEA / DAA (2,000 / 500) F-1 (3.0) 14 2.4 C A Comparative Example 3 Pc-1 (100) PAG7 (7.5) Q-8 (3.0) PGMEA / DAA (2,000 / 500) F-1 (3.0) 16 2.2 A A

[0283] Regarding the evaluation results of the resist pattern formed by the EUV exposure, the sensitivity, CDU performance, and residual film rate of the radiosensitive linear resin composition of the examples were all good. Furthermore, regarding storage stability, the composition using strontium cations was better than that using monazine cations. [Industrial Applicability]

[0284] According to the described radiosensitive linear resin composition and patterning method, resist patterns with good sensitivity to exposure light, excellent CDU performance, and high residual film yield can be formed. Therefore, these are preferably used in the fabrication processes of semiconductor devices that are expected to be further miniaturized in the future.

Claims

1. A radiosensitive linear resin composition comprising: a resin comprising at least one of the structural units represented by formula (1) and formula (2) below, and a structural unit having a phenolic hydroxyl group; an acid diffusion control agent represented by formula (α) below, wherein the content of the acid diffusion control agent is 0.5 parts by mass or more and 12 parts by mass or less relative to 100 parts by mass of the resin; and a solvent, wherein in formula (1), RT is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group; RX is a monovalent hydrocarbon group having 1 to 20 carbon atoms; and in formula (2), Rc is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group; Lc is a single bond or a divalent linkage group; and Rc1, Rc2 and Rc3 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms. In the formula (α), Rw is a monovalent organic group, hydroxyl group, or amino group with 1 to 20 carbon atoms; if multiple Rws are present, they may be the same or different; Lq is a divalent linker; if multiple Lqs are present, they may be the same or different; Z+ is a monovalent radiosensitive linear ononium cation; q1 is an integer from 1 to 4; q2 is an integer from 0 to 3; q3 is an integer from 1 to 3; the upper limit of q1+q2+q3 is 6.

2. The radiosensitive linear resin composition as claimed in claim 1, wherein in formula (1), RX is a monovalent chain hydrocarbon group having 1 to 10 carbon atoms.

3. The radiosensitive linear resin composition as claimed in claim 1 or 2, wherein in formula (2), Rc1 and Rc2 are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, and Rc3 is a monovalent alicyclic or aromatic hydrocarbon group having 6 to 12 carbon atoms.

4. The radiosensitive linear resin composition as claimed in claim 1 or 2, wherein in the formula (α), q1 is 2 or 3, q2 is 0 or 1, and q3 is 1.

5. The radiosensitive linear resin composition as claimed in claim 1 or 2, wherein in the formula (α), Z+ comprises an aromatic ring structure having fluorine atoms.

6. The radiosensitive linear resin composition as claimed in claim 1 or 2 further comprises a radiosensitive linear acid generator, which generates an acid with a lower pKa than an acid generated from the acid diffusion control agent by irradiation with radiation.

7. The radiosensitive linear resin composition as claimed in claim 1 or 2, wherein the resin further comprises a structural unit containing at least one of the group consisting of lactone structures, cyclic carbonate structures and sulfonyl lactone structures.

8. The radiosensitive linear resin composition as claimed in claim 1 or 2, wherein the resin further comprises: structural units having an organic acid anion portion and an onium cation portion.

9. The radiosensitive linear resin composition as claimed in claim 1 or 2, further comprising a high-fluorine-content resin with a fluorine atom mass content greater than that of the resin.

10. A method for forming a pattern, comprising: The step of directly or indirectly coating a substrate with the radiosensitive linear resin composition as described in any one of claims 1 to 9 to form a resist film; The steps of exposing the resist film; and developing the exposed resist film using a developing solution.

11. The pattern forming method as claimed in claim 10, wherein the exposure is performed using extreme ultraviolet light or an electron beam.