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

Abstract

Provided are: a radiation-sensitive resin composition which can exhibit satisfactory levels of sensitivity, LWR performance and pattern rectangularity; and a pattern formation method.　This radiation-sensitive resin composition contains: a resin having a structural unit represented by formula (1); a radiation-sensitive acid generator; and a solvent. In formula (1), R1 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.　R2 and R3 are each independently a monovalent hydrocarbon group having 1-10 carbon atoms, or these groups combine with each other to form a C3-20 divalent cyclic hydrocarbon group together with the carbon atom to which these are bonded.　R4 is a hydrogen atom or a monovalent hydrocarbon group having 1-10 carbon atoms.　R5 and R6 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1-10 carbon atoms, or these groups combine with each other to form a C3-20 divalent cyclic hydrocarbon group together with the carbon atom to which these are bonded.　R7 and R8 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1-10 carbon atoms, or these groups combine with each other to form a C3-20 divalent cyclic hydrocarbon group together with the carbon atom to which these are bonded.　R9 and R10 are each independently a monovalent organic group having 1-10 carbon atoms, or these groups combine with each other to form a 3-30-membered divalent cyclic organic group together with the carbon atom to which these are bonded.　n1 is an integer between 1 and 4. If n1 is 2 or more, the plurality of R5 and R6 moieties may be the same as, or different from, each other.　n2 is an integer between 0 and 3. If n2 is 2 or more, the plurality of R7 and R8 moieties may be the same as, or different from, each other.

Description

[Technical Field]

[0001] The present invention relates to a radiation-sensitive resin composition, a pattern-forming method using the same, and polymers and compounds that can be used therein. [Background technology]

[0002] Photolithography techniques using resist compositions are used to form fine circuits in semiconductor elements. A typical procedure involves, for example, exposing a coating of the resist composition to radiation through a mask pattern to generate an acid, which is then catalyzed by a reaction that causes a difference in the solubility of the resin in an alkaline or organic developer between the exposed and unexposed areas, thereby forming a resist pattern on a substrate.

[0003] The photolithography technology mentioned above is promoting the miniaturization of patterns by using short-wavelength radiation such as ArF excimer lasers, and also by using liquid immersion lithography, in which exposure is performed with the space between the lens of the exposure device and the resist film filled with a liquid medium.

[0004] As efforts toward further technological advances continue, a technology has been proposed in which a quencher (diffusion control agent) is added to a resist composition to capture acid that has diffused to unexposed areas through a salt exchange reaction, thereby improving lithography performance with ArF exposure (Patent Document 1).In addition, lithography using shorter wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet) is also being considered as a next-generation technology. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5556765 Summary of the Invention [Problem to be solved by the invention]

[0006] In these efforts toward next-generation technologies, resist performance equivalent to or better than conventional ones is required in terms of sensitivity, line width roughness (LWR) performance indicating variation in line width of the resist pattern, rectangularity of the cross-sectional shape of the pattern (hereinafter also referred to as pattern rectangularity, etc.), etc. However, existing radiation-sensitive resin compositions do not provide these properties at a sufficient level.

[0007] An object of the present invention is to provide a radiation-sensitive resin composition that can exhibit sufficient levels of sensitivity, LWR performance, pattern rectangularity, etc., and a pattern forming method, etc. [Means for solving the problem]

[0008] As a result of extensive research into solving the above problem, the present inventors have found that the above object can be achieved by employing the following configuration, and have thus completed the present invention.

[0009] That is, in one embodiment, the present invention provides: A resin having a structural unit represented by the following formula (1) (hereinafter also referred to as "structural unit (α)"), a radiation-sensitive acid generator; Solvent and The present invention relates to a radiation-sensitive resin composition comprising: [ka] (In formula (1), R 1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 2 and R 3 are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. R 4 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. R 5 and R 6are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. R 7 and R 8 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. R 9 and R 10 are each independently a monovalent organic group having 1 to 10 carbon atoms, or a divalent cyclic organic group having 3 to 30 ring members formed by combining these groups together with the carbon atoms to which they are bonded. n1 is an integer of 1 to 4. When n1 is 2 or more, multiple R 5 and R 6 are the same or different from each other. n2 is an integer of 0 to 3. When n2 is 2 or more, multiple R 7 and R 8 are the same or different.)

[0010] The radiation-sensitive resin composition of the present invention contains a resin having the structural unit (α), and therefore can exhibit excellent sensitivity, LWR performance, pattern rectangularity, and the like during resist pattern formation. The structural unit (α) is presumed to contribute to the improvement of not only the excellent sensitivity and LWR performance but also the pattern rectangularity, since both the acrylate structural unit and the acetal structural unit can be dissociated by acid upon exposure. However, this presumption of the mechanism of action does not necessarily limit the scope of the present invention.

[0011] In the present invention, examples of the organic group include a monovalent hydrocarbon group, a group containing a divalent heteroatom-containing group between carbon atoms of the hydrocarbon group, and a group in which some or all of the hydrogen atoms contained in the hydrocarbon group or the group containing a divalent heteroatom-containing group have been substituted with a monovalent heteroatom-containing group.

[0012] In the present invention, unless otherwise specified, the term "hydrocarbon group" includes linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. The term "hydrocarbon group" includes both saturated and unsaturated hydrocarbon groups. The term "linear hydrocarbon group" refers to a hydrocarbon group that does not contain a cyclic structure and is composed only of a linear structure, and includes both linear and branched hydrocarbon groups. The term "alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic structure as a ring structure and does not contain an aromatic ring structure, and includes both monocyclic alicyclic hydrocarbon groups and polycyclic alicyclic hydrocarbon groups. However, it does not have to be composed only of an alicyclic structure, and may contain a linear structure as part of it. The term "aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as a ring structure. However, it does not have to be composed only of an aromatic ring structure, and may contain a linear structure or an alicyclic structure as part of it.

[0013] In another embodiment, the present invention provides a step of directly or indirectly applying the radiation-sensitive resin composition onto a substrate to form a resist film; a step of exposing the resist film to light; and The present invention also relates to a method for forming a resist pattern, which includes a step of developing the exposed resist film.

[0014] The method for forming a resist pattern of the present invention includes a step using the above-described radiation-sensitive resin composition, and therefore can be used to form a good pattern that is excellent in sensitivity, LWR performance, pattern rectangularity, etc.

[0015] On the other hand, in another embodiment, the present invention provides The present invention relates to a polymer (hereinafter also referred to as "polymer (1)") having a structural unit (structural unit (α)) represented by the following formula (1): [ka] (In formula (1), R 1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 2 and R3 are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. R 4 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. R 5 and R 6 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. R 7 and R 8 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. R 9 and R 10 are each independently a monovalent organic group having 1 to 10 carbon atoms, or a divalent cyclic organic group having 3 to 30 ring members formed by combining these groups together with the carbon atoms to which they are bonded. n1 is an integer of 1 to 4. When n1 is 2 or more, multiple R 5 and R 6 are the same or different from each other. n2 is an integer of 0 to 3. When n2 is 2 or more, multiple R 7 and R 8 are the same or different.)

[0016] Since the polymer (1) of the present invention has the structural unit (α), it is possible to produce the radiation-sensitive resin composition using the polymer (1).

[0017] On the other hand, in another embodiment, the present invention provides The present invention relates to a compound represented by the following formula (3) (hereinafter also referred to as "compound (1)"). [ka] (In formula (1), R 1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 2 and R 3 are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. R 4 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. R 5 and R 6 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. R 7 and R 8 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. R 9 and R 10 are each independently a monovalent organic group having 1 to 10 carbon atoms, or a divalent cyclic organic group having 3 to 30 ring members formed by combining these groups together with the carbon atoms to which they are bonded. n1 is an integer of 1 to 4. When n1 is 2 or more, multiple R 5 and R 6 are the same or different from each other. n2 is an integer of 0 to 3. When n2 is 2 or more, multiple R 7 and R 8 are the same or different.)

[0018] Since the compound (1) of the present invention has the above chemical structure, it is possible to produce the above polymer using it as a monomer component. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.

[0020] <Radiation sensitive resin composition> The radiation-sensitive resin composition according to this embodiment (hereinafter also simply referred to as "composition") contains a resin having a structural unit (α), a radiation-sensitive acid generator, and a solvent. The composition may contain other optional components as long as the effects of the present invention are not impaired. By including a resin having a structural unit (α), the radiation-sensitive resin composition can be endowed with high levels of sensitivity, LWR performance, and pattern rectangularity.

[0021] (Resin having structural unit (α)) The resin having the structural unit (α) is an aggregate of polymers having a structural unit containing an acid-dissociable group (hereinafter also referred to as "structural unit (I)") (hereinafter this resin will also be referred to as "base resin"). The structural unit (α) is also an acid-dissociable group. The resin contains the structural unit (α) as the acid-dissociable group (structural unit (I)), but may also contain other acid-dissociable groups in addition to this. The "acid-dissociable group" refers to a group that substitutes a hydrogen atom in a carboxy group, a phenolic hydroxyl group, an alcoholic hydroxyl group, a sulfo group, etc., and dissociates under the action of an acid. The radiation-sensitive resin composition of the present invention has excellent pattern formability because the resin contains the structural unit (I).

[0022] In addition to the structural unit (I), the base resin preferably has a structural unit (II) containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure, which will be described later, and may also have structural units other than the structural units (I) and (II). Each structural unit will be described below.

[0023] Structural Units The structural unit (I) is a structural unit containing an acid-dissociable group, and the resin contains the structural unit (α). [Structural unit (α)] The structural unit (α) is represented by the above formula (1).

[0024] In the above formula (1), R 1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0025] In the above formula (1), R 2 and R 3 are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded.

[0026] In the above formula (1), the above R 2 and R 3 Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by the formula (I) include a chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms.

[0027] In the above formula (1), the above R 2 and R 3 Examples of the chain hydrocarbon group having 1 to 10 carbon atoms represented by the formula include a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, and a linear or branched unsaturated hydrocarbon group having 1 to 10 carbon atoms.

[0028] In the above formula (1), the above R 2 and R 3Examples of the monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms represented by the formula (I) include monocyclic or polycyclic saturated hydrocarbon groups, and monocyclic or polycyclic unsaturated hydrocarbon groups. Examples of the monocyclic saturated hydrocarbon group include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Examples of the polycyclic cycloalkyl group include a bridged alicyclic hydrocarbon group such as a norbornyl group and an adamantyl group. Examples of the monocyclic unsaturated hydrocarbon group include a monocyclic cycloalkenyl group such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, and a cyclohexenyl group. Examples of the polycyclic unsaturated hydrocarbon group include a polycyclic cycloalkenyl group such as a norbornenyl group. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms constituting the alicyclic ring are bonded by a bond chain containing one or more carbon atoms.

[0029] In the above formula (1), the above R 2 and R 3 Examples of the monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms represented by the formula (I) include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; and aralkyl groups such as a benzyl group, a phenethyl group, and a naphthylmethyl group.

[0030] In the above formula (1), the above R 2 and R 3 The divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups represented by the following formula together with the carbon atoms to which they are bonded is not particularly limited, as long as it is a group in which two hydrogen atoms have been removed from the same carbon atom constituting a carbon ring of an alicyclic hydrocarbon having the above carbon number.

[0031] In the above formula (1), R 4 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0032] In the above formula (1), the above R 4Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by the formula (I) include a chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms.

[0033] In the above formula (1), the above R 4 Examples of the chain hydrocarbon group having 1 to 10 carbon atoms represented by the formula include a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, and a linear or branched unsaturated hydrocarbon group having 1 to 10 carbon atoms.

[0034] In the above formula (1), the above R 4 Examples of the monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms represented by the formula (I) include monocyclic or polycyclic saturated hydrocarbon groups, and monocyclic or polycyclic unsaturated hydrocarbon groups. Examples of the monocyclic saturated hydrocarbon group include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Examples of the polycyclic cycloalkyl group include a bridged alicyclic hydrocarbon group such as a norbornyl group and an adamantyl group. Examples of the monocyclic unsaturated hydrocarbon group include a monocyclic cycloalkenyl group such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, and a cyclohexenyl group. Examples of the polycyclic unsaturated hydrocarbon group include a polycyclic cycloalkenyl group such as a norbornenyl group. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms constituting the alicyclic ring are bonded by a bond chain containing one or more carbon atoms.

[0035] In the above formula (1), the above R 4 Examples of the monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms represented by the formula (I) include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; and aralkyl groups such as a benzyl group, a phenethyl group, and a naphthylmethyl group.

[0036] In the above formula (1), R 5 and R 6are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded.

[0037] In the above formula (1), the above R 5 and R 6 Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by the formula (I) include a chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms.

[0038] In the above formula (1), the above R 5 and R 6 Examples of the chain hydrocarbon group having 1 to 10 carbon atoms represented by the formula include a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, and a linear or branched unsaturated hydrocarbon group having 1 to 10 carbon atoms.

[0039] In the above formula (1), the above R 5 and R 6 Examples of the monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms represented by the formula (I) include monocyclic or polycyclic saturated hydrocarbon groups, and monocyclic or polycyclic unsaturated hydrocarbon groups. Examples of the monocyclic saturated hydrocarbon group include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Examples of the polycyclic cycloalkyl group include a bridged alicyclic hydrocarbon group such as a norbornyl group and an adamantyl group. Examples of the monocyclic unsaturated hydrocarbon group include a monocyclic cycloalkenyl group such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, and a cyclohexenyl group. Examples of the polycyclic unsaturated hydrocarbon group include a polycyclic cycloalkenyl group such as a norbornenyl group. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms constituting the alicyclic ring are bonded by a bond chain containing one or more carbon atoms.

[0040] In the above formula (1), the above R5 and R 6 Examples of the monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms represented by the formula (I) include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; and aralkyl groups such as a benzyl group, a phenethyl group, and a naphthylmethyl group.

[0041] In the above formula (1), the above R 5 and R 6 The divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups represented by the following formula together with the carbon atoms to which they are bonded is not particularly limited, as long as it is a group in which two hydrogen atoms have been removed from the same carbon atom constituting a carbon ring of an alicyclic hydrocarbon having the above carbon number.

[0042] In the above formula (1), R 7 and R 8 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded.

[0043] In the above formula (1), the above R 7 and R 8 Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by the formula (I) include a chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms.

[0044] In the above formula (1), the above R 7 and R 8 Examples of the chain hydrocarbon group having 1 to 10 carbon atoms represented by the formula include a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, and a linear or branched unsaturated hydrocarbon group having 1 to 10 carbon atoms.

[0045] In the above formula (1), the above R 7 and R 8Examples of the monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms represented by the formula (I) include monocyclic or polycyclic saturated hydrocarbon groups, and monocyclic or polycyclic unsaturated hydrocarbon groups. Examples of the monocyclic saturated hydrocarbon group include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Examples of the polycyclic cycloalkyl group include a bridged alicyclic hydrocarbon group such as a norbornyl group and an adamantyl group. Examples of the monocyclic unsaturated hydrocarbon group include a monocyclic cycloalkenyl group such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, and a cyclohexenyl group. Examples of the polycyclic unsaturated hydrocarbon group include a polycyclic cycloalkenyl group such as a norbornenyl group. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms constituting the alicyclic ring are bonded by a bond chain containing one or more carbon atoms.

[0046] In the above formula (1), the above R 7 and R 8 Examples of the monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms represented by the formula (I) include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; and aralkyl groups such as a benzyl group, a phenethyl group, and a naphthylmethyl group.

[0047] In the above formula (1), the above R 7 and R 8 The divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups represented by the following formula together with the carbon atoms to which they are bonded is not particularly limited, as long as it is a group in which two hydrogen atoms have been removed from the same carbon atom constituting a carbon ring of an alicyclic hydrocarbon having the above carbon number.

[0048] In the above formula (1), R 9 and R 10 are each independently a monovalent organic group having 1 to 10 carbon atoms, or a divalent cyclic organic group having 3 to 30 ring members formed by combining these groups together with the carbon atoms to which they are bonded.

[0049] In the above formula (1), the above R 9 and R 10 Examples of the monovalent organic group having 1 to 10 carbon atoms represented by the formula (I) include a monovalent hydrocarbon group having 1 to 10 carbon atoms, a group containing a divalent heteroatom-containing group between carbon atoms of the hydrocarbon group, and a group in which some or all of the hydrogen atoms contained in the hydrocarbon group and the group containing a divalent heteroatom-containing group have been substituted with a monovalent heteroatom-containing group.

[0050] In the above formula (1), the above R 9 and R 10 Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by the formula (I) include a chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms.

[0051] In the above formula (1), the above R 9 and R 10 Examples of the chain hydrocarbon group having 1 to 10 carbon atoms represented by the formula include a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, and a linear or branched unsaturated hydrocarbon group having 1 to 10 carbon atoms.

[0052] In the above formula (1), the above R 9 and R 10Examples of the monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms represented by the formula (I) include monocyclic or polycyclic saturated hydrocarbon groups, and monocyclic or polycyclic unsaturated hydrocarbon groups. Examples of the monocyclic saturated hydrocarbon group include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Examples of the polycyclic cycloalkyl group include a bridged alicyclic hydrocarbon group such as a norbornyl group and an adamantyl group. Examples of the monocyclic unsaturated hydrocarbon group include a monocyclic cycloalkenyl group such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, and a cyclohexenyl group. Examples of the polycyclic unsaturated hydrocarbon group include a polycyclic cycloalkenyl group such as a norbornenyl group. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms constituting the alicyclic ring are bonded by a bond chain containing one or more carbon atoms.

[0053] In the above formula (1), the above R 9 and R 10 Examples of the monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms represented by the formula (I) include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; and aralkyl groups such as a benzyl group, a phenethyl group, and a naphthylmethyl group.

[0054] In the above formula (1), the above R 9 and R 10 The group containing a divalent heteroatom-containing group between carbon atoms of the hydrocarbon group represented by the formula (I) is not particularly limited as long as it contains a divalent heteroatom-containing group such as an oxygen atom or a sulfur atom between carbon atoms of the hydrocarbon group.

[0055] In the above formula (1), the above R 9 and R 10 There are no particular limitations on the group as long as some or all of the hydrogen atoms contained in the group containing the divalent heteroatom-containing group represented by the formula (I) are substituted with a monovalent heteroatom-containing group such as a fluorine atom or a chlorine atom.

[0056] In the above formula (1), the above R 9 and R 10 The divalent cyclic organic group having 3 to 30 carbon atoms formed by combining these groups represented by the formula (I) together with the carbon atoms to which they are bonded is not particularly limited as long as it is a group in which two hydrogen atoms have been removed from the same carbon atom that forms a cyclic structure having the above carbon number. Examples of the cyclic structure include an alicyclic structure, lactone structure, cyclic carbonate structure, sultone structure, etc., each having 3 to 30 carbon atoms. These cyclic structures may be substituted with a halogen atom, a hydroxyl group, a monovalent organic group, etc.

[0057] In the above formula (1), the above R 9 and R 10 Examples of the divalent cyclic organic group having 3 to 20 carbon atoms represented by the formula include groups represented by the formula below (* indicates the bonding site with each oxygen atom of the acetal ring structure). [ka] (In the formula, a is an integer of 1 to 6.)

[0058] In the above formula (1), n1 is an integer of 1 to 4. When n1 is 2 or more, multiple R 5 and R 6 are the same or different from each other.

[0059] In the above formula (1), n2 is an integer of 0 to 3. When n2 is 2 or more, a plurality of R 7 and R 8 are the same or different from each other.

[0060] Examples of the monomer component for obtaining the structural unit (α) represented by the above formula (1) include compounds represented by the following formulae (M-1) to (M-25).

[0061] [ka]

[0062] [ka]

[0063] [Structural unit (I) other than structural unit (α)] The structural unit (I) may contain an acid-dissociable group other than the structural unit (α). The other structural unit (I) is not particularly limited as long as it contains an acid-dissociable group, and examples thereof include a structural unit having a tertiary alkyl ester moiety, a structural unit having a structure in which the hydrogen atom of a phenolic hydroxyl group is substituted with a tertiary alkyl group, and a structural unit having an acetal bond. From the viewpoint of improving pattern formability, however, a structural unit represented by the following formula (2) (hereinafter also referred to as "structural unit (I-1)") is preferred.

[0064] [ka] (In formula (2), R 11 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 12 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R 13 and R 14 each independently represents a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded.

[0065] In the above formula (2), the above R 11 From the viewpoint of copolymerizability of the monomer that gives the structural unit (I), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0066] In the above formula (2), the above R 12 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0067] In the above formula (2), the above R 12 Examples of the chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula include a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, and a linear or branched unsaturated hydrocarbon group having 1 to 20 carbon atoms.

[0068] In the above formula (2), the above R 12 Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include monocyclic or polycyclic saturated hydrocarbon groups, and monocyclic or polycyclic unsaturated hydrocarbon groups. Examples of the monocyclic saturated hydrocarbon group include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cycloundecanyl group, and a cyclododecanyl group. Examples of the polycyclic cycloalkyl group include a bridged alicyclic hydrocarbon group such as a norbornyl group and an adamantyl group. Examples of the monocyclic unsaturated hydrocarbon group include a monocyclic cycloalkenyl group such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, a cyclohexenyl group, and a cyclooctenyl group. Examples of the polycyclic unsaturated hydrocarbon group include a polycyclic cycloalkenyl group such as a norbornenyl group. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two carbon atoms that are not adjacent to each other among the carbon atoms that constitute the alicyclic ring are bonded together by a bonding chain containing one or more carbon atoms.

[0069] In the above formula (2), the above R 12 Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by the formula (I) include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, an anthryl group, and a pyrenyl group; and aralkyl groups such as a benzyl group, a phenethyl group, and a naphthylmethyl group.

[0070] In the above formula (2), the above R 13 and R 14 Examples of the chain hydrocarbon group having 1 to 10 carbon atoms represented by the formula include a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, and a linear or branched unsaturated hydrocarbon group having 1 to 10 carbon atoms.

[0071] In the above formula (2), the above R 13 and R 14 Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include a monovalent monocyclic aliphatic hydrocarbon group having 3 to 20 carbon atoms and a monovalent bridged alicyclic hydrocarbon group having 6 to 20 carbon atoms.

[0072] In the above formula (2), the above R 13 and R 14 Examples of the monovalent monocyclic aliphatic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group.

[0073] In the above formula (2), the above R 13 and R 14 Examples of the monovalent bridged alicyclic hydrocarbon group having 6 to 20 carbon atoms represented by the formula (I) include a norbornyl group, an adamantyl group, a tricyclodecyl group, and a tetracyclododecyl group.

[0074] In the above formula (2), the above R 13 and R 14 The divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups represented by the following formula together with the carbon atoms to which they are bonded is not particularly limited, as long as it is a group in which two hydrogen atoms have been removed from the same carbon atom constituting a carbon ring of an alicyclic hydrocarbon having the above carbon number.

[0075] Examples of the structural unit (I) represented by the above formula (2) ("structural unit (I-1)") include structural units represented by the following formulas (2-1) to (2-7) (hereinafter also referred to as "structural units (I-2-1) to (I-2-7)").

[0076] [ka]

[0077] In the above formulas (2-1) to (2-7), R 11 ~R 14is synonymous with the above formula (2).

[0078] In the above formula (2-1), i is an integer of 0 to 16. i is preferably 1.

[0079] In the above formula (2-3), k is 0 to 1.

[0080] In the above formula (2-4), l is an integer of 0 to 2.

[0081] In the above formula (2-5), j is an integer of 0 to 16. Preferably, j is 1.

[0082] In the above formulas (2-1) to (2-7), R 12 is preferably a methyl group, an ethyl group or an isopropyl group.

[0083] In the above formulas (2-1) to (2-7), R 13 and R 14 are each independently preferably a methyl group or an ethyl group.

[0084] The base resin may contain one type of structural unit (I) or a combination of two or more types.

[0085] The content of the structural unit (I) (the total content when multiple types are included) relative to all structural units constituting the base resin is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 30 mol% or more, and particularly preferably 35 mol% or more. Also, it is preferably 80 mol% or less, more preferably 75 mol% or less, even more preferably 70 mol% or less, and particularly preferably 65 mol% or less. By ensuring that the content of the structural unit (I) falls within the above range, the pattern formability of the radiation-sensitive resin composition of the present invention can be further improved.

[0086] [Structural unit (II)] The structural unit (II) is a structural unit containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. By further including the structural unit (II), the base resin can adjust its solubility in a developer, thereby improving the lithography performance, such as the resolution, of a resist film obtained from the radiation-sensitive resin composition of the present invention. Furthermore, the adhesion between a resist pattern formed from the base resin and a substrate can be improved.

[0087] Examples of the structural unit (II) include structural units represented by the following formulae (T-1) to (T-10).

[0088] [ka]

[0089] In the above formula, R L1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L2 ~R L5 are each independently a hydrogen atom, an alkyl group having 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. L4 and R L5 and may be combined together to form a divalent alicyclic group having 3 to 8 carbon atoms, together with the carbon atoms to which they are bonded. 2 is a single bond or a divalent linking group. X is an oxygen atom or a methylene group. k is an integer of 0 to 3. m is an integer of 1 to 3.

[0090] Above R L4 and R L5 Examples of the divalent alicyclic group having 3 to 8 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded include R 11 and R 12Among divalent alicyclic groups having 3 to 20 carbon atoms, which are formed by combining chain hydrocarbon groups or alicyclic hydrocarbon groups represented by the following formula together with the carbon atoms to which they are bonded, groups having 3 to 8 carbon atoms can be mentioned. One or more hydrogen atoms on this alicyclic group may be substituted with a hydroxy group.

[0091] The above L 2 Examples of the divalent linking group represented by the formula (I) include a divalent linear or branched hydrocarbon group having 1 to 10 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, or a group composed of one or more of these hydrocarbon groups and at least one group selected from -CO-, -O-, -NH-, and -S-.

[0092] Of these, the structural unit (II) is preferably a structural unit containing a lactone structure, more preferably a structural unit containing a norbornane lactone structure, and even more preferably a structural unit derived from norbornane lactone-yl (meth)acrylate.

[0093] The content of the structural unit (II) is preferably 20 mol% or more, more preferably 25 mol% or more, and even more preferably 30 mol% or more, based on all structural units constituting the base resin. Also, it is preferably 80 mol% or less, more preferably 75 mol% or less, and even more preferably 70 mol% or less. By ensuring that the content of the structural unit (II) falls within the above range, the lithography performance, such as resolution, of the resist film obtained from the radiation-sensitive resin composition of the present invention and the adhesion of the formed resist pattern to the substrate can be further improved.

[0094] [Structural unit (III)] The base resin optionally contains other structural units in addition to the structural units (I) and (II). Examples of the other structural units include a structural unit (III) containing a polar group (excluding those corresponding to the structural unit (II)). By further containing the structural unit (III), the base resin can adjust its solubility in a developer, thereby improving the lithography performance, such as the resolution, of a resist film obtained from the radiation-sensitive resin composition of the present invention. Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a nitro group, and a sulfonamide group. Among these, a hydroxy group and a carboxy group are preferred, and a hydroxy group is more preferred.

[0095] Examples of the structural unit (III) include structural units represented by the following formula:

[0096] [ka]

[0097] In the above formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0098] When the base resin has the structural unit (III) having the polar group, the content of the structural unit (III) is preferably 5 mol % or more, more preferably 8 mol % or more, and even more preferably 10 mol % or more, based on the total structural units constituting the base resin, and is preferably 40 mol % or less, more preferably 35 mol % or less, and even more preferably 30 mol % or less.

[0099] Structural Unit (IV) The base resin optionally contains, as other structural units, a structural unit derived from hydroxystyrene or a structural unit having a phenolic hydroxyl group (hereinafter, both of these are collectively referred to as "structural unit (IV)"). The structural unit (IV) contributes to improving etching resistance and the difference in developer solubility (dissolution contrast) between exposed and unexposed areas. In particular, the base resin is suitable for pattern formation using exposure to radiation with a wavelength of 50 nm or less, such as electron beams or EUV.

[0100] In this case, it is preferable to carry out polymerization in a state in which the phenolic hydroxyl group is protected with a protecting group such as an alkali-labile group, and then to obtain structural unit (IV) by deprotection through hydrolysis. The structural unit that gives structural unit (IV) upon hydrolysis is preferably represented by the following formula (4-1) or (4-2).

[0101] [ka]

[0102] In the above formulas (4-1) and (4-2), R 15 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 16 R is a monovalent hydrocarbon group or alkoxy group having 1 to 20 carbon atoms. 16 The monovalent hydrocarbon group having 1 to 20 carbon atoms is R 12 Examples of the alkoxy group include a methoxy group, an ethoxy group, and a tert-butoxy group.

[0103] Above R 16 As the alkyl group, an alkyl group and an alkoxy group are preferred, and among these, a methyl group and a tert-butoxy group are more preferred.

[0104] In the case of a resin intended for exposure to radiation having a wavelength of 50 nm or less, the content of the structural unit (IV) is preferably 10 mol % or more, more preferably 20 mol % or more, based on the total structural units constituting the resin, and is preferably 70 mol % or less, more preferably 60 mol % or less.

[0105] (Method for synthesizing base resin) The base resin can be synthesized, for example, by polymerizing monomers that provide the respective structural units in an appropriate solvent using a radical polymerization initiator or the like.

[0106] Examples of the radical polymerization initiator include azo radical initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl 2,2'-azobisisobutyrate; and peroxide radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred, with AIBN being more preferred. These radical initiators can be used alone or in combination.

[0107] Examples of the solvent used in the polymerization include: Alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, and norbornane; Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene; Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, and chlorobenzene; Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate, and methyl propionate; Ketones such as acetone, methyl ethyl ketone, 4-methyl-2-pentanone, and 2-heptanone; ethers such as tetrahydrofuran, dimethoxyethanes, and diethoxyethanes; Examples include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2-pentanol, etc. These solvents used in the polymerization may be used alone or in combination of two or more.

[0108] The reaction temperature in the polymerization is usually 40° C. to 150° C., and preferably 50° C. to 120° C. The reaction time is usually 1 hour to 48 hours, and preferably 1 hour to 24 hours.

[0109] The molecular weight of the base resin is not particularly limited, but the weight average molecular weight (Mw) of the base resin as converted to polystyrene by gel permeation chromatography (GPC) is preferably 1,000 to 50,000, more preferably 2,000 to 30,000, even more preferably 3,000 to 15,000, and particularly preferably 4,000 to 12,000. If the Mw of the base resin is below the lower limit, the heat resistance of the resulting resist film may be reduced. If the Mw of the base resin is above the upper limit, the developability of the resist film may be reduced.

[0110] The ratio (Mw / Mn) of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the base resin as determined by GPC is usually 1 or more and 5 or less, preferably 1 or more and 3 or less, and more preferably 1 or more and 2 or less.

[0111] The Mw and Mn of the resin in this specification are values ​​measured using gel permeation chromatography (GPC) under the following conditions.

[0112] GPC columns: 2 G2000HXL, 1 G3000HXL, 1 G4000HXL (all manufactured by Tosoh) Column temperature: 40℃ Elution solvent: tetrahydrofuran Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Detector: differential refractometer Standard material: monodisperse polystyrene

[0113] The content of the base resin is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more, based on the total solid content of the radiation-sensitive resin composition.

[0114] (other resins) The radiation-sensitive resin composition of this embodiment may contain, as an additional resin, a resin having a higher mass content of fluorine atoms than the base resin (hereinafter also referred to as a "high-fluorine content resin"). When the radiation-sensitive resin composition contains a high-fluorine content resin, the high-fluorine content resin can be unevenly distributed in the surface layer of the resist film relative to the base resin, thereby improving the water repellency of the surface of the resist film during immersion exposure.

[0115] The high-fluorine content resin preferably has, for example, a structural unit represented by the following formula (5) (hereinafter also referred to as "structural unit (V)"), and may also have the structural unit (I) or the structural unit (II) in the above base resin, as necessary.

[0116] [ka]

[0117] In the above formula (5), R 17 is a hydrogen atom, a methyl group, or a trifluoromethyl group. L is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2ONH-, -CONH- or -OCONH-. 18 is a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0118] Above R 17As the alkyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (V), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0119] Above G L As the group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (V), a single bond and -COO- are preferred, and -COO- is more preferred.

[0120] Above R 18 Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a linear or branched alkyl group having 1 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.

[0121] Above R 18 Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.

[0122] Above R 18 As the alkyl group, a fluorinated chain hydrocarbon group is preferable, a fluorinated alkyl group is more preferable, and a 2,2,2-trifluoroethyl group, a 1,1,1,3,3,3-hexafluoropropyl group, and a 5,5,5-trifluoro-1,1-diethylpentyl group are even more preferable.

[0123] When the high-fluorine-content resin has the structural unit (V), the content of the structural unit (V) is preferably 30 mol% or more, more preferably 40 mol% or more, even more preferably 45 mol% or more, and particularly preferably 50 mol% or more, based on the total structural units constituting the high-fluorine-content resin. Also, the content is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less. By setting the content of the structural unit (V) within the above range, the mass content of fluorine atoms in the high-fluorine-content resin can be more appropriately adjusted, further promoting uneven distribution of fluorine atoms in the surface layer of the resist film, and as a result, the water repellency of the resist film during immersion exposure can be further improved.

[0124] The high-fluorine-content resin may have a fluorine atom-containing structural unit represented by the following formula (f-1) (hereinafter also referred to as structural unit (VI)) in addition to or instead of the structural unit (V): By having the structural unit (f-1), the high-fluorine-content resin has improved solubility in an alkaline developer, and can suppress the occurrence of development defects.

[0125] [ka]

[0126] The structural unit (VI) is roughly classified into two types: (x) a case having an alkali-soluble group, and (y) a case having a group that dissociates under the action of alkali to increase the solubility in an alkali developer (hereinafter simply referred to as an "alkali-dissociable group"). In both (x) and (y), R C R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. D is a single bond, a hydrocarbon group having 1 to 20 carbon atoms and a valence of (s+1), and R of this hydrocarbon group E Oxygen atom, sulfur atom, -NR dd -, a carbonyl group, -COO-, or -CONH- is bonded to the hydrocarbon group, or a structure in which some of the hydrogen atoms in the hydrocarbon group are substituted with an organic group having a hetero atom. dd is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer of 1 to 3.

[0127] When the structural unit (VI) has (x) an alkali-soluble group, R F is a hydrogen atom, and A 1 is an oxygen atom, -COO-* or -SO2O-*. * is R F The binding site of W is shown. 1 A is a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group. 1 is an oxygen atom, W 1 is A 1 is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group on the carbon atom to which R is bonded.E is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, multiple R E , W 1 , A 1 and R F may be the same or different. When the structural unit (VI) has (x) an alkali-soluble group, it is possible to increase the affinity for an alkaline developer and suppress development defects. As the structural unit (VI) having (x) an alkali-soluble group, A 1 is an oxygen atom and W 1 It is particularly preferred that is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.

[0128] When the structural unit (VI) has an alkali-dissociable group (y), R F is a monovalent organic group having 1 to 30 carbon atoms, and A 1 is an oxygen atom, -NR aa -, -COO-* or -SO2O-*. R aa is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * is R F The binding site of W is shown. 1 R is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. E A is a single bond or a divalent organic group having 1 to 20 carbon atoms. 1 When is -COO-* or -S02O-*, W 1 or R F is A 1 A has a fluorine atom on the carbon atom bonded to or adjacent to A. 1 is an oxygen atom, W 1 , R E is a single bond, and R D R is a hydrocarbon group with 1 to 20 carbon atoms E A carbonyl group is bonded to the end of the R F is an organic group having a fluorine atom. When s is 2 or 3, multiple R E , W 1 , A 1 and R Fmay be the same or different. When the structural unit (VI) has (y) an alkali-dissociable group, the surface of the resist film changes from hydrophobic to hydrophilic in the alkaline development step. As a result, the affinity to the developer is significantly increased, and development defects can be more efficiently suppressed. As the structural unit (VI) having (y) an alkali-dissociable group, A 1 is -COO-* and R F Or W 1 It is particularly preferred that both of them have a fluorine atom.

[0129] R C As the alkyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (VI), a hydrogen atom and a methyl group are preferred, and a methyl group is more preferred.

[0130] R E When is a divalent organic group, it is preferably a group having a lactone structure, more preferably a group having a polycyclic lactone structure, and more preferably a group having a norbornane lactone structure.

[0131] When the high-fluorine-content resin has the structural unit (VI), the content of the structural unit (VI) is preferably 50 mol% or more, more preferably 60 mol% or more, and even more preferably 70 mol% or more, based on all structural units constituting the high-fluorine-content resin. Also, it is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less. By setting the content of the structural unit (VI) within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0132] Other structural units The high fluorine content resin may contain a structural unit having an alicyclic structure represented by the following formula (6) as a structural unit other than the above structural units. [ka] (In the above formula (6), R 1α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 2αis a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0133] In the above formula (6), R 2α Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include monocyclic or polycyclic hydrocarbon groups having 3 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.

[0134] When the high-fluorine-content resin contains the structural unit having the alicyclic structure, the content of the structural unit having the alicyclic structure is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more, based on the total structural units constituting the high-fluorine-content resin, and is preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less.

[0135] The lower limit of Mw of the high fluorine content resin is preferably 1,000, more preferably 2,000, further preferably 3,000, and particularly preferably 5,000. The upper limit of Mw is preferably 50,000, more preferably 30,000, further preferably 20,000, and particularly preferably 15,000.

[0136] The lower limit of Mw / Mn of the high fluorine content resin is usually 1, and more preferably 1.1. The upper limit of the Mw / Mn is usually 5, and is preferably 3, more preferably 2, and even more preferably 1.9.

[0137] The content of the high-fluorine content resin is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and particularly preferably 1.5 parts by mass or more, relative to 100 parts by mass of the base resin, and is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 8 parts by mass or less.

[0138] By setting the content of the high-fluorine-containing resin within the above range, the high-fluorine-containing resin can be more effectively distributed unevenly on the surface layer of the resist film, thereby further improving the water repellency of the surface of the resist film during immersion lithography. The radiation-sensitive resin composition may contain one or more high-fluorine-containing resins.

[0139] (Method for synthesizing high fluorine content resin) The high fluorine content resin can be synthesized by the same method as the above-mentioned method for synthesizing the base resin.

[0140] (Radiation-sensitive acid generator) The radiation-sensitive resin composition of this embodiment further contains a radiation-sensitive acid generator that generates an acid upon irradiation (exposure) with radiation. When the base resin having the structural unit (I) and the resin A contain the structural unit (2), the acid generated from the radiation-sensitive acid generator upon exposure can dissociate the acid-dissociable groups in the structural unit (I) and the structural unit (2) to generate a carboxyl group or the like.

[0141] When the radiation-sensitive resin composition contains the radiation-sensitive acid generator, the polarity of the resin in the exposed area increases, and the resin in the exposed area becomes soluble in the developer in the case of development with an aqueous alkaline solution, while becoming poorly soluble in the developer in the case of development with an organic solvent.

[0142] Examples of the radiation-sensitive acid generator include onium salt compounds, sulfonimide compounds, halogen-containing compounds, diazoketone compounds, etc. Examples of the onium salt compounds include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, etc. Among these, sulfonium salts and iodonium salts are preferred.

[0143] Examples of the acid generated upon exposure include those that generate sulfonic acids upon exposure. Examples of such acids include compounds in which one or more fluorine atoms or fluorinated hydrocarbon groups are substituted on the carbon atom adjacent to the sulfo group. Among these, those having a cyclic structure are particularly preferred as radiation-sensitive acid generators.

[0144] These radiation-sensitive acid generators may be used alone or in combination of two or more. The content of the radiation-sensitive acid generator (when multiple types of radiation-sensitive acid generators are used in combination, the total content) is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the base resin. Furthermore, the content is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, even more preferably 30 parts by mass or less, and particularly preferably 20 parts by mass or less, per 100 parts by mass of the resin. This allows for excellent sensitivity, LWR performance, and CDU performance to be exhibited during resist pattern formation.

[0145] (acid diffusion control agent) The radiation-sensitive resin composition may optionally contain an acid diffusion controller. The acid diffusion controller controls the diffusion of acid generated from the radiation-sensitive acid generator upon exposure in the resist film, thereby suppressing undesirable chemical reactions in unexposed regions. The storage stability of the resulting radiation-sensitive resin composition is also improved. Furthermore, the resolution of the resist pattern is further improved, and changes in the line width of the resist pattern due to variations in the exposure time between exposure and development can be suppressed, resulting in a radiation-sensitive resin composition with excellent process stability.

[0146] Examples of the acid diffusion controller include a compound represented by the following formula (7) (hereinafter also referred to as "nitrogen-containing compound (I)"), a compound having two nitrogen atoms in the same molecule (hereinafter also referred to as "nitrogen-containing compound (II)"), a compound having three nitrogen atoms (hereinafter also referred to as "nitrogen-containing compound (III)"), an amide group-containing compound, a urea compound, and a nitrogen-containing heterocyclic compound.

[0147] [ka]

[0148] In the above formula (5), R 71 , R 72 and R 73 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.

[0149] Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; and aromatic amines such as aniline.

[0150] Examples of the nitrogen-containing compound (II) include ethylenediamine and N,N,N',N'-tetramethylethylenediamine.

[0151] Examples of the nitrogen-containing compound (III) include polyamine compounds such as polyethyleneimine and polyallylamine; polymers such as dimethylaminoethylacrylamide; and the like.

[0152] Examples of the amide group-containing compound include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, pyrrolidone, and N-methylpyrrolidone.

[0153] Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, and tributylthiourea.

[0154] Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N-(undecylcarbonyloxyethyl)morpholine; pyrazine, pyrazole, and the like.

[0155] In addition, a compound having an acid-dissociable group can also be used as the nitrogen-containing organic compound. Examples of such nitrogen-containing organic compounds having an acid-dissociable group include Nt-butoxycarbonylpiperidine, Nt-butoxycarbonylimidazole, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl-2-phenylbenzimidazole, N-(t-butoxycarbonyl)di-n-octylamine, N-(t-butoxycarbonyl)diethanolamine, N-(t-butoxycarbonyl)dicyclohexylamine, N-(t-butoxycarbonyl)diphenylamine, Nt-butoxycarbonyl-4-hydroxypiperidine, and Nt-amyloxycarbonyl-4-hydroxypiperidine.

[0156] Furthermore, a photodegradable base that generates a weak acid upon exposure can also be suitably used as the acid diffusion controller. Examples of the photodegradable base include a compound containing a radiation-sensitive onium cation that decomposes upon exposure and an anion of a weak acid. In the photodegradable base, a weak acid is generated from a proton generated by decomposition of the radiation-sensitive onium cation and an anion of the weak acid in the exposed area, resulting in a decrease in acid diffusion controllability.

[0157] Examples of the photodegradable base include sulfonium salt compounds represented by the following formula (7-1) and iodonium salt compounds represented by the following formula (7-2).

[0158] [ka]

[0159] In the above formula (7-1) and formula (7-2), J + is a sulfonium cation, and U+ is the iodonium cation. + Examples of the sulfonium cation represented by the formula (X-1) include sulfonium cations represented by the formula (X-1): + Examples of iodonium cations represented by the formula (X-2) include those represented by the following formula: E- and Q- are each independently anions represented by OH-, Rα-COO-, or Rα-SO3-. Rα is an alkyl group, an aryl group, or an aralkyl group. A hydrogen atom on the aromatic ring of the aryl group or aralkyl group represented by Rα may be substituted with a hydroxy group, a fluorine atom-substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.

[0160] [ka]

[0161] [ka]

[0162] In the above formula (X-1), R c1 , R c2 and R c3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms.

[0163] In the above formula (X-2), R e1 and R e2 are each independently a halogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k8 and k9 are each independently an integer of 0 to 4.

[0164] Examples of the substituent that may substitute the hydrogen atom of each of the above groups include a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkyl group (when substituting a hydrogen atom of a cycloalkyl group or an aromatic hydrocarbon group), an aryl group (when substituting a hydrogen atom of an alkyl group), an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, an acyloxy group, etc. Among these, a hydroxy group, an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, or an acyloxy group is preferred, and an alkoxy group or an alkoxycarbonyl group is more preferred.

[0165] Examples of the photodegradable base include compounds represented by the following formula:

[0166] [ka]

[0167] Of these, the photodegradable base is preferably a sulfonium salt, more preferably a triarylsulfonium salt, and even more preferably triphenylsulfonium salicylate and triphenylsulfonium 10-camphorsulfonate.

[0168] These acid diffusion controllers may be used alone or in combination of two or more.

[0169] The total content of the acid diffusion controller is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, based on the total moles of the radiation-sensitive acid generator. Furthermore, the total content of the acid diffusion controller is preferably 40 mol% or less, more preferably 30 mol% or less, and even more preferably 25 mol% or less, based on the total moles of the radiation-sensitive acid generator. By setting the content of the acid diffusion controller within the above range, the lithography performance of the radiation-sensitive resin composition can be further improved.

[0170] (solvent) The radiation-sensitive resin composition according to this embodiment contains a solvent. The solvent is not particularly limited as long as it can dissolve or disperse at least the resin having the structural unit (α) and the radiation-sensitive acid generator.

[0171] Examples of the solvent include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0172] Examples of alcohol-based solvents include: Monoalcohol solvents having 1 to 18 carbon atoms, such as iso-propanol, 4-methyl-2-pentanol, 3-methoxybutanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, and diacetone alcohol; polyhydric alcohol solvents having 2 to 18 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; Examples include polyhydric alcohol partially etherified solvents obtained by etherifying some of the hydroxy groups of the above polyhydric alcohol solvents.

[0173] Examples of ether solvents include: dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether; cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; Aromatic ring-containing ether solvents such as diphenyl ether and anisole (methyl phenyl ether); Examples include polyhydric alcohol ether solvents obtained by etherifying the hydroxy groups of the above polyhydric alcohol solvents.

[0174] Examples of ketone solvents include chain ketone solvents such as acetone, butanone, and methyl-iso-butyl ketone: Cyclic ketone solvents such as cyclopentanone, cyclohexanone, and methylcyclohexanone: Examples include 2,4-pentanedione, acetonylacetone, and acetophenone.

[0175] Examples of the amide solvent include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; Examples of the solvent include chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0176] Examples of ester solvents include: Monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate; polyhydric alcohol partial ether acetate solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; Lactone solvents such as γ-butyrolactone and valerolactone; Carbonate solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; Examples of suitable solvents include polycarboxylic acid diesters such as propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, ethyl lactate, and diethyl phthalate.

[0177] Examples of hydrocarbon solvents include: Aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; Examples of the solvent include aromatic hydrocarbon solvents such as benzene, toluene, di-isopropylbenzene, and n-amylnaphthalene.

[0178] Among these, ester-based solvents and ketone-based solvents are preferred, polyhydric alcohol partial ether acetate-based solvents, cyclic ketone-based solvents and lactone-based solvents are more preferred, and propylene glycol monomethyl ether acetate, cyclohexanone and γ-butyrolactone are even more preferred. The radiation-sensitive resin composition may contain one or more solvents.

[0179] (Other optional ingredients) The radiation-sensitive resin composition of the present invention may contain other optional components in addition to the above-mentioned components. Examples of the other optional components include a crosslinking agent, a localization promoter, a surfactant, an alicyclic skeleton-containing compound, and a sensitizer. These other optional components may be used alone or in combination of two or more.

[0180] (acid diffusion control agent) The radiation-sensitive resin composition of the present invention may contain an acid diffusion controller. The acid diffusion controller controls the diffusion phenomenon in the resist film of the acid generated from the radiation-sensitive acid generator upon exposure, thereby suppressing undesirable chemical reactions in unexposed regions. The storage stability of the resulting radiation-sensitive resin composition is also improved. Furthermore, the resolution of the resist pattern is further improved, and changes in the line width of the resist pattern due to variations in the exposure time between exposure and development can be suppressed, resulting in a radiation-sensitive resin composition with excellent process stability.

[0181] (Crosslinking agent) The crosslinking agent is a compound having two or more functional groups, which causes a crosslinking reaction in the resin component by an acid catalyst reaction in the bake step after the floodwise exposure step, thereby increasing the molecular weight of the resin component and reducing the solubility of the patternwise exposed areas in a developer. Examples of the functional groups include (meth)acryloyl groups, hydroxymethyl groups, alkoxymethyl groups, epoxy groups, and vinyl ether groups.

[0182] (Uneven distribution promoter) The uneven distribution promoter has the effect of more efficiently unevenly distributing the high-fluorine-content resin on the resist film surface. By incorporating this uneven distribution promoter into the radiation-sensitive resin composition, the amount of the high-fluorine-content resin added can be reduced compared to conventional methods. Therefore, while maintaining the lithography performance of the radiation-sensitive resin composition, it is possible to further suppress elution of components from the resist film into the immersion medium and perform immersion exposure at higher speeds through high-speed scanning. As a result, it is possible to improve the hydrophobicity of the resist film surface, which suppresses immersion-related defects such as watermark defects. Examples of compounds that can be used as such uneven distribution promoters include low-molecular-weight compounds having a dielectric constant of 30 to 200 and a boiling point of 100°C or higher at 1 atmosphere. Specific examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, and polyhydric alcohols.

[0183] Examples of the lactone compound include γ-butyrolactone, valerolactone, mevalonic lactone, and norbornane lactone.

[0184] Examples of the carbonate compound include propylene carbonate, ethylene carbonate, butylene carbonate, and vinylene carbonate.

[0185] The nitrile compound may, for example, be succinonitrile.

[0186] The polyhydric alcohol may, for example, be glycerin.

[0187] The content of the uneven distribution accelerator is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, and still more preferably 25 parts by mass or more, relative to 100 parts by mass of the total amount of resins in the radiation-sensitive resin composition. The content is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, even more preferably 100 parts by mass or less, and particularly preferably 80 parts by mass or less. The radiation-sensitive resin composition may contain one or more uneven distribution accelerators.

[0188] (surfactant) The surfactant has the effect of improving coating properties, striations, developability, etc. Examples of surfactants include nonionic surfactants such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, and polyethylene glycol distearate; commercially available products include KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, and Polyflow No. 95 (all manufactured by Kyoeisha Chemical), F-Top EF301, EF303, EF352 (all manufactured by Tochem Products), Megafac F171, F173 (all manufactured by DIC), Fluorad FC430, FC431 (all manufactured by Sumitomo 3M), Asahiguard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (all manufactured by Asahi Glass Co., Ltd.) The content of the surfactant in the radiation-sensitive resin composition is usually 2 parts by mass or less per 100 parts by mass of the resin.

[0189] (alicyclic skeleton-containing compounds) The alicyclic skeleton-containing compound has the effect of improving dry etching resistance, pattern shape, adhesion to the substrate, and the like.

[0190] Examples of the alicyclic skeleton-containing compound include: Adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and t-butyl 1-adamantanecarboxylate; deoxycholate esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholate, and 2-ethoxyethyl deoxycholate; Lithocholate esters such as t-butyl lithocholate, t-butoxycarbonylmethyl lithocholate, and 2-ethoxyethyl lithocholate; Examples include 3-[2-hydroxy-2,2-bis(trifluoromethyl)ethyl]tetracyclo[4.4.0.1(2,5).1(7,10)]dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo[4.2.1.0(3,7)]nonane, etc. The content of the alicyclic skeleton-containing compound in the radiation-sensitive resin composition is usually 5 parts by mass or less per 100 parts by mass of the resin.

[0191] (sensitizer) The sensitizer acts to increase the amount of acid generated from the radiation-sensitive acid generator or the like, and has the effect of improving the "apparent sensitivity" of the radiation-sensitive resin composition.

[0192] Examples of sensitizers include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, and phenothiazines. These sensitizers may be used alone or in combination of two or more. The content of the sensitizer in the radiation-sensitive resin composition is usually 2 parts by mass or less per 100 parts by mass of the resin.

[0193] <Method for preparing radiation-sensitive resin composition> The radiation-sensitive resin composition can be prepared, for example, by mixing a resin having the structural unit (α), a radiation-sensitive acid generator, and, if necessary, a high-fluorine-content resin, and a solvent in a predetermined ratio. After mixing, the radiation-sensitive resin composition is preferably filtered, for example, through a filter having a pore size of about 0.05 μm. The solids concentration of the radiation-sensitive resin composition is usually 0.1% to 50% by mass, preferably 0.5% to 30% by mass, and more preferably 1% to 20% by mass.

[0194] <Pattern formation method> A method for forming a resist pattern according to one embodiment of the present invention includes: a step (1) of directly or indirectly applying the radiation-sensitive resin composition onto a substrate to form a resist film (hereinafter also referred to as a "resist film forming step"); a step (2) of exposing the resist film to light (hereinafter also referred to as the "exposure step"); The method includes a step (3) of developing the exposed resist film (hereinafter also referred to as the "developing step").

[0195] According to the above-described resist pattern forming method, a high-quality resist pattern can be formed because the above-described radiation-sensitive resin composition is used, which has excellent sensitivity in the exposure step, CDU performance, and pattern rectangularity. Each step will be described below.

[0196] [Resist film formation process] In this step (step (1) above), a resist film is formed from the radiation-sensitive resin composition. Examples of substrates on which the resist film is formed include conventionally known substrates such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective coating, such as those disclosed in Japanese Patent Publication No. 6-12452 or Japanese Patent Application Laid-Open No. 59-93448, may be formed on the substrate. Examples of coating methods include spin coating, casting coating, and roll coating. After coating, pre-baking (PB) may be performed, if necessary, to volatilize the solvent in the coating film. The PB temperature is typically 60°C to 140°C, preferably 80°C to 120°C. The PB time is typically 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds. The thickness of the resist film formed is preferably 10 nm to 1,000 nm, more preferably 10 nm to 500 nm.

[0197] When performing immersion exposure, regardless of whether the radiation-sensitive resin composition contains a water-repellent polymer additive such as a high-fluorine-content resin, a protective film for immersion exposure that is insoluble in the immersion liquid may be provided on the formed resist film to prevent direct contact between the immersion liquid and the resist film. The protective film for immersion exposure may be either a solvent-removable protective film that is removed with a solvent before the development step (see, for example, JP-A No. 2006-227632), or a developer-removable protective film that is removed simultaneously with development in the development step (see, for example, WO2005-069076 and WO2006-035790). However, from the viewpoint of throughput, it is preferable to use a developer-removable protective film for immersion exposure.

[0198] When the next exposure step is carried out using radiation with a wavelength of 50 nm or less, it is preferable to use a resin having the structural units (I) and (IV) as the base resin in the composition.

[0199] [Exposure process] In this step (step (2) above), the resist film formed in step (1), the resist film formation step, is exposed to radiation through a photomask (or, in some cases, through an immersion medium such as water). The radiation used for exposure may be, depending on the line width of the desired pattern, electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet light), X-rays, and gamma rays; or charged particle beams such as electron beams and alpha rays. Among these, far ultraviolet light, electron beams, and EUV are preferred, with ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV being more preferred, and electron beams and EUV with wavelengths of 50 nm or less, which are positioned as next-generation exposure technologies, being even more preferred.

[0200] When exposure is performed by immersion exposure, examples of the immersion liquid used include water and fluorine-based inert liquids. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has as small a temperature coefficient of refractive index as possible so as to minimize distortion of the optical image projected onto the film. However, particularly when the exposure light source is an ArF excimer laser (wavelength 193 nm), water is preferred for its availability and ease of handling, in addition to the above considerations. When water is used, a small proportion of an additive that reduces the surface tension of water and increases its surfactant power may be added. This additive is preferably one that does not dissolve the resist film on the wafer and has negligible effect on the optical coating on the underside of the lens. Distilled water is preferred as the water used.

[0201] After the exposure, post-exposure baking (PEB) is preferably performed to promote dissociation of acid-dissociable groups in the resin or the like in the exposed portions of the resist film by the acid generated from the radiation-sensitive acid generator upon exposure. This PEB results in a difference in solubility in a developer between the exposed and unexposed portions. The PEB temperature is usually 50°C to 180°C, preferably 80°C to 130°C. The PEB time is usually 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds.

[0202] [Development process] In this step (step (3) above), the resist film exposed in the exposure step (step (2) above) is developed. This allows a predetermined resist pattern to be formed. After development, the resist film is generally washed with a rinse liquid such as water or alcohol, and then dried.

[0203] In the case of alkaline development, the developer used for the development may be, for example, an alkaline aqueous solution containing at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, or 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, a TMAH aqueous solution is preferred, and a 2.38 mass % TMAH aqueous solution is more preferred.

[0204] In the case of organic solvent development, examples of the organic solvent include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, and alcohol solvents, as well as solvents containing an organic solvent. Examples of the organic solvent include one or more of the solvents listed above as solvents for the radiation-sensitive resin composition. Among these, ether solvents, ester solvents, and ketone solvents are preferred. As ether solvents, glycol ether solvents are preferred, with ethylene glycol monomethyl ether and propylene glycol monomethyl ether being more preferred. As ester solvents, acetate ester solvents are preferred, with n-butyl acetate and amyl acetate being more preferred. As ketone solvents, chain ketones are preferred, with 2-heptanone being more preferred. The content of the organic solvent in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. Examples of components other than the organic solvent in the developer include water and silicone oil.

[0205] As mentioned above, the developer may be either an alkaline developer or an organic solvent developer.

[0206] Examples of development methods include a method in which a substrate is immersed in a tank filled with developer for a certain period of time (dip method), a method in which developer is piled up on the surface of the substrate by surface tension and left to stand for a certain period of time (puddle method), a method in which developer is sprayed onto the surface of the substrate (spray method), and a method in which developer is continuously dispensed onto a substrate rotating at a constant speed while a developer dispensing nozzle is scanned at a constant speed (dynamic dispense method).

[0207] <Polymer (1)> The polymer (1) of the present invention is a polymer having a structural unit (structural unit (α)) represented by the following formula (1): [ka] (In formula (1), R 1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 2 and R 3 are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. R 4 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. R 5 and R 6 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. R 7 and R 8are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. R 9 and R 10 are each independently a monovalent organic group having 1 to 10 carbon atoms, or a divalent cyclic organic group having 3 to 30 ring members formed by combining these groups together with the carbon atoms to which they are bonded. n1 is an integer of 1 to 4. When n1 is 2 or more, multiple R 5 and R 6 are the same or different from each other. n2 is an integer of 0 to 3. When n2 is 2 or more, multiple R 7 and R 8 are the same or different.)

[0208] The polymer (1) may be a resin having the structural unit (α) described above, and R 1 ~R 10 etc. shall conform to the description of the resin etc. having the structural unit (α) described above.

[0209] <Compound (1)> The compound (1) of the present invention is a compound represented by the following formula (3). [ka] (In formula (1), R 1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 2 and R 3 are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. R 4 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. R 5 and R 6are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. R 7 and R 8 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. R 9 and R 10 are each independently a monovalent organic group having 1 to 10 carbon atoms, or a divalent cyclic organic group having 3 to 30 ring members formed by combining these groups together with the carbon atoms to which they are bonded. n1 is an integer of 1 to 4. When n1 is 2 or more, multiple R 5 and R 6 are the same or different from each other. n2 is an integer of 0 to 3. When n2 is 2 or more, multiple R 7 and R 8 are the same or different.)

[0210] In the above formula (3), R 1 ~R 10 and n1, n2, etc. are as defined above for the resin having the structural unit (α).

[0211] Examples of the compound (1) include compounds represented by the following formulae (M-1) to (M-25).

[0212] [ka]

[0213] [ka] [Example]

[0214] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Measurement methods for various physical properties are shown below.

[0215] [Weight average molecular weight (Mw) and number average molecular weight (Mn)] The Mw and Mn of the polymer were measured by gel permeation chromatography (GPC) using Tosoh GPC columns (two "G2000HXL", one "G3000HXL", and one "G4000HXL") under the following conditions. The dispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn. Elution solvent: tetrahydrofuran Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Column temperature: 40℃ Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0216] [1H-NMR analysis and 13C-NMR analysis] 1H-NMR and 13C-NMR analyses were measured using a nuclear magnetic resonance spectrometer (JNM-Delta400 manufactured by JEOL Ltd.).

[0217] <Synthesis of [M] compound (monomer)> [Synthesis Example 1] (Synthesis of Compound (M-1)) 20.0 mmol of glyceric acid, 1.00 mmol of concentrated sulfuric acid, and 50 g of methanol were added to a reaction vessel and stirred at 100°C for 12 hours. The reaction was then terminated by adding saturated aqueous sodium bicarbonate, followed by extraction with ethyl acetate and separation of the organic layer. The resulting organic layer was washed with saturated aqueous sodium chloride and then with water. After drying over sodium sulfate, the solvent was removed by distillation, and the ester was purified by column chromatography to obtain it in good yield.

[0218] To the above ester, 20.0 mmol of 2-adamantanone, 1.00 mmol of concentrated sulfuric acid, and 50 g of toluene were added, and the mixture was stirred at 150°C for 4 hours. The reaction was then terminated by adding saturated aqueous sodium bicarbonate, followed by extraction with ethyl acetate and separation of the organic layer. The resulting organic layer was washed with saturated aqueous sodium chloride and then with water. After drying over sodium sulfate, the solvent was removed by distillation, and the residue was purified by column chromatography to obtain the acetal in good yield.

[0219] The acetal was dissolved in 50 g of tetrahydrofuran. After cooling the solution to 0°C, 40.0 mmol of methylmagnesium iodide was added dropwise and stirred at room temperature for 5 hours. The reaction was then terminated by adding saturated aqueous ammonium chloride solution, followed by extraction with ethyl acetate and separation of the organic layer. The resulting organic layer was washed with saturated aqueous sodium chloride solution. After drying over sodium sulfate, the solvent was removed by distillation, and the resulting mixture was purified by column chromatography to obtain the alcohol in good yield.

[0220] The alcohol was dissolved in 30.0 mmol of triethylamine, 4.00 mmol of 1,4-diazabicyclo[2.2.2]octane, and 70 g of acetonitrile. The solution was cooled to 0°C, and then 30.0 mmol of methacryloyl chloride was added dropwise. After the addition was complete, the solution was stirred at room temperature for 6 hours. The reaction was then terminated by adding saturated aqueous ammonium chloride, followed by extraction with ethyl acetate and separation of the organic layer. The resulting organic layer was washed with saturated aqueous sodium chloride. After drying with saturated sodium chloride, the solvent was removed by distillation, and the resulting mixture was purified by column chromatography to obtain the monomer (M-1) in good yield. The synthesis scheme for the monomer (M-1) is shown below.

[0221] [ka]

[0222] [Synthesis Examples 2 to 10] (Synthesis of Monomers (M-2) to (M-10)) Except for appropriately changing the raw materials and precursors, compounds represented by the following formulas (M-2) to (M-10) were synthesized in the same manner as in Synthesis Example 1. Hereinafter, the compounds represented by formulas (M-2) to (M-10) may be referred to as "compound (M-2)" to "compound (M-10)" or "monomer (M-2)" to "monomer (M-10)," respectively.

[0223] [ka]

[0224] <Synthesis of Polymer [A] and Polymer [E]> Among the monomers used in the synthesis of each polymer, monomers other than the above-mentioned monomers (M-1) to (M-10) are shown below. In the following synthesis examples, unless otherwise specified, parts by mass refer to a value when the total mass of the monomers used is taken as 100 parts by mass, and mol % refers to a value when the total number of moles of the monomers used is taken as 100 mol %. Furthermore, the present invention is not limited to the following structural units.

[0225] [ka]

[0226] [Synthesis Example 1] (Synthesis of Polymer (A-1)) Monomer (M-1), monomer (m-1), and monomer (m-6) were dissolved in 2-butanone (200 parts by mass) to a molar ratio of 15 / 50 / 35 (mol%), and AIBN (azobisisobutyronitrile) (5 mol% relative to 100 mol% of the total monomers used) was added as an initiator to prepare a monomer solution. 2-butanone (100 parts by mass) was placed in an empty reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C and the monomer solution was added dropwise over 3 hours with stirring. The start of the dropwise addition marked the start of the polymerization reaction, which was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to below 30°C using water. The cooled polymerization solution was poured into methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with methanol, filtered, and dried at 50°C for 10 hours to obtain polymer (A-1) as a white powder. The Mw of polymer (A-1) was 6,170, and the Mw / Mn was 1.62. Furthermore, as a result of C-NMR analysis, the contents of the structural units derived from (M-1), (m-1), and (m-6) were 15.6 mol%, 50.3 mol%, and 34.1 mol%, respectively.

[0227] [Synthesis Examples 2 to 13 and Synthesis Examples 17 to 21] (Synthesis of Polymers (A-2) to (A-13) and Polymers (A-17) to (A-21)) Polymers (A-2) to (A-13) and (A-17) to (A-21) were synthesized in the same manner as in Synthesis Example 1, except that the types and blending ratios of monomers shown in Table 1 below were used. The content (mol %) of each structural unit and physical properties (Mw and Mw / Mn) of the resulting polymers are also shown in Table 1 below. In Table 1 below, "-" indicates that the corresponding monomer was not used.

[0228] [Table 1]

[0229] [Table 2]

[0230] [Synthesis Example 14] (Synthesis of Polymer (A-14)) Monomers (M-1), (m-1), (m-4), and (m-12) were dissolved in 1-methoxy-2-propanol (200 parts by mass relative to the total monomers) in a molar ratio of 5 / 35 / 20 / 40 (mol %). Next, AIBN (5 mol %) was added as an initiator to prepare a monomer solution. 1-Methoxy-2-propanol (100 parts by mass relative to the total monomers) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C. The monomer solution was added dropwise over 3 hours with stirring. The polymerization reaction was initiated at the start of the dropwise addition and continued for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to below 30°C using water. The cooled polymerization solution was poured into hexane (500 parts by mass relative to the polymerization solution), and the precipitated white powder was filtered off. The white powder collected by filtration was washed twice with hexane, then filtered and dissolved in 1-methoxy-2-propanol (300 parts by mass). Methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were then added, and the mixture was stirred at 70°C for 6 hours to carry out a hydrolysis reaction. After the reaction was completed, the remaining solvent was distilled off. The resulting solid was dissolved in acetone (100 parts by mass) and added dropwise to water (500 parts by mass) to coagulate the resin. The resulting solid was collected by filtration and dried at 50°C for 13 hours to obtain a white powdery polymer (A-14) (yield: 72%). The Mw of the polymer (A-14) was 6,020, and the Mw / Mn was 1.61. Furthermore, as a result of C-NMR analysis, the content ratios of the structural units derived from (M-1), (m-1), (m-4) and (m-12) were 5.2 mol%, 35.5 mol%, 19.2 mol% and 40.1 mol%, respectively.

[0231] [Synthesis Examples 15 to 16 and Synthesis Examples 22 to 23] (Synthesis of Polymers (A-15) to (A-16) and Polymers (A-22) to (A-23)) Polymers (A-15) to (A-16) and polymers (A-22) to (A-23) were synthesized in the same manner as in Synthesis Example 14, except that the types and blending ratios of monomers shown in Table 1 below were used. Table 1 also shows the content (mol %) of each structural unit and physical properties (Mw and Mw / Mn) of the obtained polymers.

[0232] [Table 3]

[0233] [Table 4]

[0234] [Synthesis of Highly Fluorinated Polymer E] [Synthesis Example 32] (Synthesis of Polymer (E-1)) Monomer (m-1) and monomer (m-15) were dissolved in 2-butanone (200 parts by mass) to a molar ratio of 20 / 80 (mol%), and AIBN (5 mol%) was added as an initiator to prepare a monomer solution. 2-butanone (100 parts by mass) was added to the reaction vessel, followed by a 30-minute nitrogen purge. The reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours with stirring. The polymerization reaction was initiated at the start of the dropwise addition and continued for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to below 30°C with water. The solvent was replaced with acetonitrile (400 parts by mass), and then hexane (100 parts by mass) was added, stirred, and the acetonitrile layer was collected. This process was repeated three times. The solvent was replaced with propylene glycol monomethyl ether acetate to obtain a solution of polymer (E-1) (yield: 83%). The polymer (E-1) had an Mw of 6,320 and an Mw / Mn of 1.67. Furthermore, as a result of C-NMR analysis, the contents of the structural units derived from (m-1) and (m-15) were 19.7 mol % and 80.3 mol %, respectively.

[0235] [Synthesis Examples 33 to 35] (Synthesis of High Fluorine Content Resin (E-2) to High Fluorine Content Resin (E-4)) High fluorine content resins (E-2) to (E-4) were synthesized in the same manner as in Synthesis Example 32, except for using monomers of the types and blending ratios shown in Table 5. The content (mol %) of each structural unit and physical properties (Mw and Mw / Mn) of the obtained high fluorine content resins are also shown in Table 5.

[0236] [Table 5]

[0237] <Preparation of Radiation-Sensitive Resin Composition> The radiation-sensitive acid generator, acid diffusion inhibitor, and solvent constituting each radiation-sensitive resin composition are shown below.

[0238] [[B] Acid generator] B-1 to B-5: Compounds represented by the following formulae (B-1) to (B-5).

[0239] [ka]

[0240] [[C] Acid diffusion inhibitor] C-1 to C-5: Compounds represented by the following formulae (C-1) to (C-5)

[0241] [ka]

[0242] [[D] Solvent] D-1: Propylene glycol monomethyl ether acetate D-2: Cyclohexanone D-3: γ-butyrolactone D-4: Ethyl lactate

[0243] [Preparation of Positive Radiation-Sensitive Resin Composition for ArF Exposure] [Example 1] A radiation-sensitive resin composition (J-1) was prepared by mixing 100 parts by mass of (A-1) as the [A] polymer, 12.0 parts by mass of (B-4) as the [B] acid generator, 5.0 parts by mass of (C-1) as the [C] acid diffusion controller, 5.0 parts by mass (solids content) of (E-1) as the [E] polymer, and 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) as the [D] solvent, and filtering the mixture through a membrane filter having a pore size of 0.2 μm.

[0244] [Examples 2 to 21 and Comparative Examples 1 to 5] Except for using the components of the types and contents shown in Table 6 below, radiation-sensitive resin compositions (J-2) to (J-21), (J-35) to (J-37) and (CJ-1) to (CJ-5) were prepared in the same manner as in Example 1.

[0245]

Table 6

[0246] <Formation of resist pattern using positive-type ArF-exposure radiation-sensitive resin composition> On a 12-inch silicon wafer, using a spin coater (“CLEAN TRACK ACT12” manufactured by Tokyo Electron Limited), a composition for forming an underlayer antireflection film (“ARC66” manufactured by Brewer Science, Inc.) was applied, and then heated at 205 °C for 60 seconds to form an underlayer antireflection film with an average thickness of 105 nm. On this underlayer antireflection film, the positive-type ArF-exposure radiation-sensitive resin composition prepared above was applied using the spin coater, and PB (pre-bake) was performed at 90 °C for 60 seconds. Then, by cooling at 23 °C for 30 seconds, a resist film with an average thickness of 90 nm was formed. Next, with respect to this resist film, using an ArF excimer laser immersion exposure apparatus (“TWINSCAN XT-1900i” manufactured by ASML), exposure was performed through a mask pattern of 40 nm space and 86 nm pitch under optical conditions of NA = 1.35 and Annular (σ = 0.8 / 0.6). After exposure, PEB (post-exposure bake) was performed at 90 °C for 60 seconds. Then, the resist film was alkali-developed using a 2.38 mass% aqueous TMAH solution as an alkali developer, washed with water after development, and further dried to form a positive-type resist pattern (40 nm line and space pattern).

[0247] <Evaluation> The resist patterns formed using the radiation-sensitive resin composition for ArF exposure were evaluated for sensitivity, LWR performance, and resist pattern shape according to the methods described below. The results are shown in Table 7. The resist patterns were measured using a scanning electron microscope (CG-5000 manufactured by Hitachi High-Technologies Corporation).

[0248] [sensitivity] In forming a resist pattern using the radiation-sensitive resin composition for ArF exposure, the exposure dose for forming a 40 nm line and space pattern was defined as the optimum exposure dose (Eop), and this optimum exposure dose was determined as the sensitivity (mJ / cm 2 The sensitivity was 25mJ / cm 2 The following are considered "good" and 25mJ / cm 2 If it exceeded this, it was rated as "poor".

[0249] [LWR performance] A resist pattern was formed by adjusting the mask size so that a 40 nm line-and-space pattern was formed by irradiating the optimal exposure dose determined in the sensitivity evaluation above. The formed resist pattern was observed from above the pattern using the above-mentioned scanning electron microscope. A total of 500 points of line width variation were measured, and a 3 sigma value was calculated from the distribution of the measured values. This 3 sigma value was taken as the LWR (nm). The smaller the LWR value, the smaller the line roughness and the better the result. LWR performance was evaluated as "good" when it was 2.5 nm or less, and "poor" when it was more than 2.5 nm.

[0250] [Resist pattern shape] A 40 nm line and space pattern formed by irradiating with the optimum exposure dose obtained in the sensitivity evaluation was observed using the scanning electron microscope, and the cross-sectional shape of the line and space pattern was evaluated. The rectangularity of the resist pattern was evaluated as "A" if the ratio of the bottom side length to the top side length in the cross-sectional shape was 1 or more and 1.05 or less, "B" if it was more than 1.05 and 1.10 or less, and "C" if it was more than 1.10.

[0251]

Table 7

[0252] As is clear from the results in Table 7, when the radiation-sensitive resin composition of the example was used for ArF exposure, the sensitivity, LWR performance, and resist pattern shape were good. In contrast, in the comparative examples, each characteristic was inferior to that of the example. Therefore, when the radiation-sensitive resin composition of the example is used for ArF exposure, a resist pattern with high sensitivity, good LWR performance, and good resist pattern shape can be formed.

[0253] [Preparation of Radiation-Sensitive Resin Composition for Extreme Ultraviolet (EUV) Exposure] [Example 22] [A] 100 parts by mass of (A-14) as a polymer, [B] 11.0 parts by mass of (B-4) as an acid generator, [C] 5.0 parts by mass of (C-1) as an acid diffusion controller, [E] 5.0 parts by mass of (E-2) as a polymer, and 6,110 parts by mass of a mixed solvent of (D-1) / (D-4) as [D] a solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-22).

[0254] [Examples 22 to 32 and Comparative Examples 6 to 7] Radiation-sensitive resin compositions (J-22) to (J-32) and (CJ-6) to (CJ-7) were prepared in the same manner as in Example 22, except that the components of the types and contents shown in Table 8 below were used.

[0255]

Table 8

[0256] [Formation of Resist Pattern Using Radiation-Sensitive Resin Composition for EUV Exposure] A 12-inch silicon wafer was coated with a composition for forming a bottom anti-reflective coating (Brewer Science's ARC66) using a spin coater (Tokyo Electron Limited's CLEAN TRACK ACT12), followed by heating at 205°C for 60 seconds to form a bottom anti-reflective coating with an average thickness of 105 nm. The radiation-sensitive resin composition for EUV exposure prepared above was then coated onto this bottom anti-reflective coating using the spin coater, followed by post-baking at 130°C for 60 seconds. This 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 to light using an EUV exposure system (ASML's NXE3300) with NA=0.33, illumination conditions: Conventional s=0.89, and a mask: imecDEFECT32FFR02. After exposure, post-baking was performed at 120°C for 60 seconds. Thereafter, the resist film was subjected to alkaline development using a 2.38% by mass aqueous solution of TMAH as an alkaline developer, and after development, the resist film was washed with water and then dried to form a positive resist pattern (32 nm line and space pattern).

[0257] <Evaluation> The sensitivity and LWR performance of the resist patterns formed using the radiation-sensitive resin composition for EUV exposure were evaluated according to the following methods. The results are shown in Table 5. The resist patterns were measured using a scanning electron microscope (CG-5000 manufactured by Hitachi High-Technologies Corporation).

[0258] [sensitivity] In forming a resist pattern using the radiation-sensitive resin composition for EUV exposure, the exposure dose for forming a 32 nm line and space pattern was defined as the optimum exposure dose, and this optimum exposure dose was used as the sensitivity (mJ / cm 2 The sensitivity was 25mJ / cm 2 The following are considered "good" and 25mJ / cm 2 If it exceeded this, it was rated as "poor".

[0259] [LWR performance] A resist pattern was formed by irradiating the substrate with the optimal exposure dose determined in the sensitivity evaluation above, and adjusting the mask size to form a 32 nm line-and-space pattern. The formed resist pattern was observed from above using the scanning electron microscope described above. The line width variation was measured at a total of 500 points, and a 3 sigma value was calculated from the distribution of the measured values. This 3 sigma value was taken as the LWR (nm). The smaller the LWR value, the smaller the line wobble and the better the result. LWR performance was evaluated as "good" when it was 2.5 nm or less, and "poor" when it was greater than 2.5 nm.

[0260] [Resist pattern shape] A 40 nm line and space pattern formed by irradiating with the optimum exposure dose obtained in the sensitivity evaluation was observed using the scanning electron microscope, and the cross-sectional shape of the line and space pattern was evaluated. The rectangularity of the resist pattern was evaluated as "A" if the ratio of the bottom side length to the top side length in the cross-sectional shape was 1 or more and 1.05 or less, "B" if it was more than 1.05 and 1.10 or less, and "C" if it was more than 1.10.

[0261] [Table 9]

[0262] As is clear from the results in Table 8, when the radiation-sensitive resin compositions of the Examples were used for EUV exposure, the sensitivity, LWR performance, and resist pattern shape were good, whereas the Comparative Examples were inferior to the Examples in each of the properties.

[0263] [Preparation of a negative-tone radiation-sensitive resin composition for ArF exposure, and formation and evaluation of a resist pattern using this composition] [Example 33] A radiation-sensitive resin composition (J-33) was prepared by mixing 100 parts by mass of (A-2) as the [A] polymer, 12.0 parts by mass of (B-1) as the [B] acid generator, 5.0 parts by mass of (C-1) as the [C] acid diffusion controller, 5.0 parts by mass (solids content) of (E) polymer (E-3), and 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) as the [D] solvent, and filtering the mixture through a membrane filter having a pore size of 0.2 μm.

[0264] A 12-inch silicon wafer was coated with a bottom anti-reflective coating composition (Brewer Science's ARC66) using a spin coater (Tokyo Electron Limited's CLEAN TRACK ACT12), followed by heating at 205°C for 60 seconds to form a bottom anti-reflective coating with an average thickness of 105 nm. The negative radiation-sensitive resin composition for ArF exposure (J-33) prepared above was then coated onto the bottom anti-reflective coating using the spin coater, followed by pre-baking at 90°C for 60 seconds. The coating was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 90 nm. This resist film was then exposed to light using an ArF excimer laser immersion exposure system (ASML's TWINSCAN XT-1900i) under optical conditions of NA = 1.35 and annular (σ = 0.8 / 0.6) through a mask pattern with a 39 nm spacing and an 86 nm pitch. After the exposure, PEB (post-exposure bake) was performed for 60 seconds at 90° C. Then, the resist film was developed using n-butyl acetate as an organic solvent developer and dried to form a negative resist pattern (39 nm line and space pattern).

[0265] The resist pattern formed using the negative-tone radiation-sensitive resin composition for ArF exposure was evaluated in the same manner as the resist pattern formed using the positive-tone radiation-sensitive resin composition for ArF exposure. As a result, the radiation-sensitive resin composition of Example 33 exhibited good sensitivity, LWR performance, and resist pattern shape, even when a negative-tone resist pattern was formed by ArF exposure.

[0266] [Preparation of a negative-tone radiation-sensitive resin composition for EUV exposure, and formation and evaluation of a resist pattern using this composition] [Example 34] A radiation-sensitive resin composition (J-34) was prepared by mixing 100 parts by mass of (A-14) as the [A] polymer, 11.0 parts by mass of (B-2) as the [B] acid generator, 5.0 parts by mass of (C-1) as the [C] acid diffusion controller, 5.0 parts by mass of (E-4) as the [E] polymer, and 6,110 parts by mass of a mixed solvent of (D-1) / (D-4) as the [D] solvent, and filtering the mixture through a membrane filter having a pore size of 0.2 μm.

[0267] A 12-inch silicon wafer was coated with a composition for forming a bottom anti-reflective coating (Brewer Science's ARC66) using a spin coater (Tokyo Electron Limited's CLEAN TRACK ACT12), followed by heating at 205°C for 60 seconds to form a bottom anti-reflective coating with an average thickness of 105 nm. The radiation-sensitive resin composition for EUV exposure (J-34) prepared above was then coated onto this bottom anti-reflective coating using the spin coater, followed by post-baking at 130°C for 60 seconds. This 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 to light using an EUV exposure system (ASML's NXE3300) with NA=0.33, illumination conditions: Conventional s=0.89, and a mask: imecDEFECT32FFR02. After exposure, post-baking was performed at 120°C for 60 seconds. Thereafter, the resist film was developed with n-butyl acetate as an organic solvent developer and dried to form a negative resist pattern (32 nm line and space pattern).

[0268] The resist pattern formed using the negative-tone radiation-sensitive resin composition for EUV exposure was evaluated in the same manner as the resist pattern formed using the positive-tone radiation-sensitive resin composition for EUV exposure. As a result, the radiation-sensitive resin composition of Example 34 exhibited good sensitivity, LWR performance, and resist pattern shape, even when a negative-tone resist pattern was formed by EUV exposure. [Industrial Applicability]

[0269] The radiation-sensitive resin composition and resist pattern forming method of the present invention enable the formation of a resist pattern that has good sensitivity to exposure and is excellent in LWR performance and resist pattern shape. Furthermore, the polymer of the present invention can be suitably used as a polymer component of the radiation-sensitive resin composition. Furthermore, the compound of the present invention can be suitably used as a monomer component of the polymer. Therefore, these compounds can be suitably used in the processing of semiconductor devices, which are expected to become increasingly miniaturized in the future.

Claims

1. A resin having a structural unit represented by the following formula (1): a radiation-sensitive acid generator; Solvent and A radiation-sensitive resin composition comprising: 【Chemistry 1】 (In formula (1), R 1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 2 and R 3 are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. R 4 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. R 5 and R 6 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. R 7 and R 8 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a divalent cyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. R 9 and R 10 are each independently a monovalent organic group having 1 to 10 carbon atoms, or a divalent cyclic organic group having 3 to 30 ring members formed by combining these groups together with the carbon atoms to which they are bonded. n1 is an integer of 1 to 4. When n1 is 2 or more, a plurality of R 5 and R 6 are the same or different from each other. n2 is an integer of 0 to 3. When n2 is 2 or more, a plurality of R 7 and R 8 are the same or different.)

2. The radiation-sensitive resin composition according to claim 1 , further comprising a photodegradable base.

3. The radiation-sensitive resin composition according to claim 1 or 2, wherein the resin further has a structural unit represented by the following formula (2): 【Chemistry 2】 (In formula (2), R 11 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 12 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R 13 and R 14 each independently represents a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded.

4. The radiation-sensitive resin composition according to any one of claims 1 to 3, wherein the resin further has a structural unit containing at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure.

5. 5. The radiation-sensitive resin composition according to claim 1, wherein n1 is 1 or 2, and n2 is 0 or 1.

6. 6. The radiation-sensitive resin composition according to claim 1, wherein the structural unit represented by formula (1) accounts for 1 to 50 mol % of all structural units constituting the resin.

7. A step of directly or indirectly applying the radiation-sensitive resin composition according to any one of claims 1 to 6 onto a substrate to form a resist film; exposing the resist film to light; and a step of developing the exposed resist film;

8. 8. The method for forming a resist pattern according to claim 7, wherein the radiation used in the exposing step is extreme ultraviolet (EUV), X-rays, or electron beams (EB).

9. 9. The method for forming a resist pattern according to claim 7, wherein in the step of developing the resist film, the resist film is developed with an organic solvent to form a negative pattern.

10. 9. The method for forming a resist pattern according to claim 7, wherein in the step of developing the resist film, a positive pattern is formed by developing the resist film with an alkaline developer.

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