Method for forming a resist pattern and radiation-sensitive resin composition

Abstract

Provided are: a method for forming a resist pattern that, when a next-generation exposure technology is applied, demonstrates excellent performance such as sensitivity, resolution, etc. in the exposure step; and a radiation-sensitive resin composition. (C) The method for forming a resist pattern includes: a step (1) for forming a resist film in which the content of a radiation-sensitive acid-generating agent is 0.1 mass% or less; a step (2) for radiation exposure in which the resist film is irradiated with extreme ultra violet (EUV) or an electron beam (EB); and a step (3) for developing the resist film that has been subjected to radiation exposure in the step (2).

Description

Technical Field

[0001] The present invention relates to a method for forming a resist pattern and a radiation-sensitive resin composition that can be used therefor.

Background Art

[0002] Photolithography technology using a resist composition is utilized for forming fine circuits in semiconductor elements. As a typical procedure, for example, acid is generated by exposure of a resist composition film through a mask pattern to radiation, and a difference in solubility of the resin in an alkaline or organic developer between the exposed portion and the unexposed portion is caused by a reaction using the acid as a catalyst, thereby forming a resist pattern on a substrate.

[0003] In the above photolithography technology, pattern miniaturization is promoted by using short-wavelength radiation such as an ArF excimer laser or by combining this radiation with a liquid immersion exposure method (liquid immersion lithography). As a next-generation technology, utilization of even shorter-wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet rays) is being considered, and resist materials containing styrene-based resins with enhanced absorption efficiency of such radiation are also being studied. (For example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Even in the above next-generation technology, resist performance equivalent to or better than that of the prior art in terms of sensitivity, resolution, etc. is required. However, in existing radiation-sensitive resin compositions, those characteristics have not been obtained at a sufficient level.

[0006] An object of the present invention is to provide a radiation-sensitive resin composition and a method for forming a resist pattern capable of exhibiting sufficient levels of sensitivity and resolution when applying next-generation technologies.

Means for Solving the Problems

[0007] As a result of intensive studies to solve this problem, the present inventors have found that the above object can be achieved by adopting the following configuration, and have completed the present invention.

[0008] That is, in one embodiment, the present invention is (1) A step of forming a resist film in which the content of a radiation-sensitive acid generator (C) is 0.1% by mass or less, (2) A step of exposing the resist film to EUV or electron beam (EB), and (3) A step of developing the resist film exposed in the above step (2), and relates to a method for forming a resist pattern.

[0009] Since the method for forming a resist pattern of the present invention includes a step (1) of forming a resist film in which the content of a radiation-sensitive acid generator (C) is 0.1% by mass or less, it is possible to exhibit excellent levels of sensitivity and resolution in the exposure step. As the mechanism of action for expressing the above effects, although the scope of the present invention is not necessarily limited by this speculation, by setting the content of the radiation-sensitive acid generator (C) in the resist film to 0.1% by mass or less, the components of the resist film are simplified, resulting in improved uniformity, and the adverse effects at the interface between the exposed and unexposed portions due to the acid generated during the exposure step are suppressed. As a result, it is speculated that various resist performances are improved.

[0010] Also, in one embodiment, the method for forming a resist pattern of the present invention is In the above step (1), the resist film is formed from (A) a radiation-sensitive resin composition, and it is preferable that the radiation-sensitive resin composition contains (A1) a resin whose solubility changes upon EUV or electron beam (EB) exposure in the absence of a radiation-sensitive acid generator. By having the above configuration, it is possible to function as a resist film in a conventional exposure process or the like without substantially containing a conventional (C) radiation-sensitive acid generator. As a result, various resist performances can be more reliably improved.

[0011] Further, in one embodiment, the method for forming a resist pattern of the present invention In the above step (1), the resist film is formed from (A) a radiation-sensitive resin composition, and in the above (A) radiation-sensitive resin composition, it is preferable that the (C) radiation-sensitive acid generator is 0.1% by mass or less based on the total of components other than the (B) solvent. By having the above configuration, a resist film substantially free of the (C) radiation-sensitive acid generator can be formed more simply, and various resist performances can be more reliably improved.

[0012] Further, in one embodiment, the method for forming a resist pattern of the present invention In the above step (1), the resist film is formed from (A) a radiation-sensitive resin composition, and it is preferable that the above (A) radiation-sensitive resin composition does not contain a radiation-sensitive acid generator. By having the above configuration, a resist film substantially free of the (C) radiation-sensitive acid generator can be formed more simply, and various resist performances can be more reliably improved.

[0013] Further, in one embodiment, the method for forming a resist pattern of the present invention It is preferable that the above (A1) resin whose solubility changes is a resin that changes to water-soluble or alkali-soluble. By having the above configuration, various resist performances can be more reliably improved.

[0014] On the other hand, as another embodiment of the present invention, (A2) A resin containing a group dissociable by EUV or electron beam (EB) exposure, (B) a solvent, and (C) a radiation-sensitive acid generator, wherein in the above radiation-sensitive resin composition, the content of the above (C) radiation-sensitive acid generator is 0.1% by mass or less based on the total of components other than (B) the solvent, relates to a radiation-sensitive resin composition.

[0015] The radiation-sensitive resin composition of the present invention contains (A2) a resin containing a group dissociable by EUV or electron beam (EB) exposure, and in the above radiation-sensitive resin composition, the content of the above (C) radiation-sensitive acid generator is 0.1% by mass or less based on the total of components other than (B) the solvent. Therefore, it is possible to exhibit excellent levels of sensitivity, resolution, etc. in the exposure process. As the mechanism of action for the manifestation of the above effects, although the scope of the rights of the present invention is not necessarily limited by this speculation, in the above radiation-sensitive resin composition, by setting the content of the (C) radiation-sensitive acid generator to 0.1% by mass or less based on the total of components other than (B) the solvent, the constituent components of the resist film are simplified, improving uniformity, and the adverse effects at the interface between the exposed and unexposed portions due to the acid generated during the exposure process are suppressed. As a result, it is speculated that various resist performances are improved.

[0016] Further, in one embodiment, the radiation-sensitive resin composition of the present invention preferably consists only of (A2) a resin containing a group dissociable by EUV or electron beam (EB) exposure and (B) a solvent. By having the above configuration, it is possible to function as a resist film in a conventional exposure process etc. without substantially containing a (C) radiation-sensitive acid generator as in the prior art. As a result, it is possible to more surely improve various resist performances.

[0017] Further, in one embodiment, the radiation-sensitive resin composition of the present invention The resin containing the group that dissociates in the above (A2) is preferably a resin containing a group that dissociates to form a carboxylic acid structure. By having the above configuration, it can function as a resist film in a conventional exposure process or the like without substantially containing a conventional (C) radiation-sensitive acid generator. As a result, various resist performances can be more reliably improved.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.

[0019] <(A) Radiation-Sensitive Resin Composition> The (A) radiation-sensitive resin composition (hereinafter, also simply referred to as "composition") according to the present embodiment contains a predetermined resin (A0) and a (B) solvent. The above composition may contain other optional components as long as the effects of the present invention are not impaired.

[0020] (Resin (A0)) The resin (A0) in the present invention can be used as a resist film in an exposure process or a development process by changing its solubility in a developer by EUV or electron beam (EB) exposure or the like without substantially containing a radiation-sensitive acid generator. By using the resin (A0), it can be used as a resist film in an exposure process or a development process without substantially depending on the acid generated by exposure from a conventional exposure-sensitive radiation-sensitive acid generator. And as the constituent components of the resist film are simplified, the uniformity is improved, and the adverse effects at the interface between the exposed part and the unexposed part due to the acid generated during the exposure process are suppressed. As a result, various resist performances can be improved.

[0021] In the present invention, examples of the resin (A0) include a resin whose solubility changes by EUV or electron beam (EB) exposure in the absence of a (A1) radiation-sensitive acid generator.

[0022] In the present invention, the resin whose solubility changes upon EUV or electron beam (EB) exposure in the absence of (A1) a radiation-sensitive acid generator refers to a resin whose solubility in a developer changes upon EUV or electron beam (EB) exposure, substantially without depending on an acid generated by exposure from a conventional radiation-sensitive acid generator. Further, the above "change in solubility" refers to the property of increasing or decreasing the solubility in a developer.

[0023] Further, as the resin (A1) whose solubility changes, for example, a resin that changes to water-soluble or alkali-soluble can be given. Examples of the resin that changes to water-soluble or alkali-soluble include resins that regenerate or generate, upon exposure, for example, a hydroxyl group, a carboxyl group, an amino group, an ionic group, a sulfo group, etc. in the resin structure.

[0024] Further, in the present invention, as the resin (A0), for example, a resin (A2) containing a group that dissociates upon EUV or electron beam (EB) exposure can be given.

[0025] In the present invention, the resin (A2) containing a group that dissociates upon EUV or electron beam (EB) exposure refers to a resin containing a group that dissociates by a desorption reaction or the like in the resin structure upon EUV or electron beam (EB) exposure, substantially without depending on an acid generated by exposure from a conventional radiation-sensitive acid generator. Further, the above "dissociating group" can include, for example, a group that can generate a hydroxyl group, a carboxyl group, an amino group, an ionic group, a sulfo group, etc. when the group dissociates upon the above exposure.

[0026] Further, as the resin (A2) containing a group that dissociates upon EUV or electron beam (EB) exposure, for example, a resin containing a group that dissociates to form a carboxylic acid structure or a resin containing a group that dissociates to form a hydroxyl group structure can be given. Further, the above carboxylic acid structure formed by dissociation includes, for example, a carboxyl group (-COOH) and its salt (carboxylate group, -COO -) can be given. Further, the hydroxyl group structure generated by dissociation includes alcoholic hydroxyl groups, phenolic hydroxyl groups (-OH), and their salts (-O - ) and the like can be given.

[0027] In addition, examples of the resin containing the dissociating group (A2) include those containing a structural unit having a group that dissociates to generate a carboxylic acid structure, and those containing a structural unit having a group that dissociates to generate a hydroxyl group structure. Preferred examples include those containing at least one structural unit selected from a structural unit having a group that dissociates to generate a carboxylic acid structure, a structural unit having a phenolic hydroxyl group, and a structural unit having a polar group.

[0028] In addition, preferred examples of the structural unit having the polar group include those containing at least one selected from a structural unit having an alcoholic hydroxyl group, a structural unit having a lactone structure, a structural unit having a cyclic carbonate structure, and a structural unit having a sultone structure.

[0029] In the present invention, examples of the resin (A0) include an aggregate of polymers having a structural unit (a1) containing a phenolic hydroxyl group and a structural unit (a2) containing a group that dissociates upon EUV or electron beam (EB) exposure in the absence of a radiation-sensitive acid generator. (Hereinafter, this resin is also referred to as a "base resin".).

[0030] The resin (A0) serving as the base resin may have other structural units other than the structural unit (a1) and the structural unit (a2). Hereinafter, each structural unit will be described.

[0031] [Structural unit (a1)] The structural unit (a1) is a structural unit containing a phenolic hydroxyl group. By having the structural unit (a1) and, if necessary, other structural units, the resin (A0) can more appropriately adjust its solubility in the developer. As a result, various resist properties such as the sensitivity and resolution of the above-mentioned radiation-sensitive resin composition can be further improved. In addition, when using EUV, electron beam, etc. as the radiation irradiated in the exposure step in the resist pattern forming method, since the resin (A0) has the structural unit (a1), the structural unit (a1) contributes to the improvement of etching resistance and the improvement of the difference in developer solubility (dissolution contrast) between the exposed part and the unexposed part. In particular, it can be suitably applied to pattern formation using exposure with radiation having a wavelength of 50 nm or less such as an electron beam or EUV.

[0032] Examples of the above structural unit (a1) include structural units represented by the following formula (af).

[0033] [Chemical formula]

[0034] In the above formula (af), R AF1 is a hydrogen atom or a methyl group. L AF is a single bond, -COO-, -O- or -CONH-. R AF2 is a monovalent organic group having 1 to 20 carbon atoms. n f1 is an integer of 0 to 3. n f1 When n is 2 or 3, a plurality of R AF2 may be the same or different. n f2 is an integer of 1 to 3. However, n f1 + n f2 is 5 or less. n af is an integer of 0 to 2.

[0035] L AF is preferably a single bond and -COO-.

[0036] From the viewpoint of the copolymerizability of the monomer that gives the structural unit (a1), L AFWhen it is a single bond, the above R AF1 is preferably a hydrogen atom. L AF When L is -COO-, the above R AF1 is preferably a methyl group.

[0037] The organic group in the resin (A0) refers to a group containing at least one carbon atom.

[0038] The above R AF2 Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group containing a divalent heteroatom-containing group at the carbon-carbon bond or the terminal on the bond side of this hydrocarbon group, and a group in which part or all of the hydrogen atoms of the group and the above hydrocarbon group are substituted with a monovalent heteroatom-containing group.

[0039] The above R AF2 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R include alkyl groups such as methyl group, ethyl group, propyl group, and butyl group; alkenyl groups such as ethenyl group, propenyl group, and butenyl group; chain hydrocarbon groups such as ethynyl group, propynyl group, and butynyl group; cycloalkyl groups such as cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclooctyl group, norbornyl group, and adamantyl group; alicyclic hydrocarbon groups such as cyclopropenyl group, cyclopentenyl group, cyclohexenyl group, and norbornenyl group; aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group, and anthryl group; aromatic hydrocarbon groups such as benzyl group, phenethyl group, and naphthylmethyl group, etc.

[0040] The above R AF2Examples thereof preferably include a chain hydrocarbon group and a cycloalkyl group, more preferably an alkyl group and a cycloalkyl group, and still more preferably a methyl group, an ethyl group, a propyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, and an adamantyl group.

[0041] Examples of the divalent heteroatom-containing group include, for example, -O-, -CO-, -CO-O-, -S-, -CS-, -SO2-, -NR'- and groups formed by combining two or more of these, where R' is a hydrogen atom or a monovalent hydrocarbon group.

[0042] Examples of the monovalent heteroatom-containing group include, for example, a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, a hydroxy group, a carboxy group, a cyano group, an amino group, a sulfanyl group (-SH), and the like.

[0043] Among these, a monovalent chain hydrocarbon group is preferable, an alkyl group is more preferable, and a methyl group is still more preferable.

[0044] The above n f1 is preferably an integer of 0 to 2, more preferably 0 and 1, and still more preferably 0.

[0045] The above n f2 is preferably 1 and 2, more preferably 1.

[0046] The above n af is preferably 0 and 1, more preferably 0.

[0047] In the radiation-sensitive resin composition of the present invention, the structural unit (a1) can be a structural unit derived from hydroxystyrene.

[0048] The structural unit (a1) is preferably a structural unit represented by the following formulas (a1-1) to (a1-6) or the like.

[0049]

Chemical formula

[0050] In the above formulas (a1-1) to (a1-6), R AF1 is the same as in the above formula (af).

[0051] Among these, the structural units (a1-1) and (a1-2) are preferred, and (a1-1) is more preferred.

[0052] Regarding the structural unit (a1) in the resin (A0), as the lower limit of the content ratio of the structural unit (a1), 10 mol% is preferred, 15 mol% is more preferred, 20 mol% is further preferred, and 25 mol% is particularly preferred with respect to all the structural units constituting the resin (A0). As the upper limit of the above content ratio, 90 mol% is preferred, 80 mol% is more preferred, 70 mol% is further preferred, and 60 mol% is particularly preferred. By setting the content ratio of the structural unit (a1) within the above range, the above radiation-sensitive resin composition can further improve various resist performances such as sensitivity and resolution.

[0053] When attempting to directly radical polymerize a monomer having a phenolic hydroxyl group such as hydroxystyrene, the polymerization may be inhibited by the influence of the phenolic hydroxyl group. In this case, it is possible to polymerize in a state where the phenolic hydroxyl group is protected by a protecting group such as an alkali dissociable group, and then perform hydrolysis for deprotection to obtain the structural unit (a1). As the structural unit that gives the structural unit (a1) by hydrolysis, it is preferably represented by the following formula (1).

[0054] [Chemical formula]

[0055] In the above formula (1), 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, or an alkoxy group. R 12Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include monovalent hydrocarbon groups having 1 to 20 carbon atoms. Examples of the alkoxy group include methoxy group, ethoxy group, tert-butoxy group and the like.

[0056] The above R 12 is preferably an alkyl group or an alkoxy group, and more preferably a methyl group or a tert-butoxy group.

[0057] [Structural unit (a2)] The structural unit (a2) is a group whose solubility changes by EUV or electron beam (EB) exposure in the absence of a radiation-sensitive acid generator, and a group that dissociates by EUV or electron beam (EB) exposure in the absence of a radiation-sensitive acid generator, etc.

[0058] In the present invention, "in the absence of a radiation-sensitive acid generator" means a situation where a radiation-sensitive acid generator is absent or substantially absent. Examples of the structural unit (a2) include a structural unit having a tertiary alkyl ester moiety, a structural unit having a structure in which a hydrogen atom of a phenolic hydroxyl group is substituted with a tertiary alkyl group, a structural unit having an acetal bond, etc. From the viewpoint of improving the pattern formability of the above radiation-sensitive resin composition, a structural unit represented by the following formula (2) (hereinafter, also referred to as "structural unit (a2-1)") is preferable.

[0059] The structural units exemplified in the previous paragraph are structures known as acid dissociable groups in the art. In the present invention, the "acid dissociable group" is a group that substitutes a hydrogen atom of a carboxy group, a phenolic hydroxyl group, an alcoholic hydroxyl group, a sulfo group, etc., and has a property of dissociating by the action of an acid. As described above, in the present invention, it is not necessary for the above structural unit (a2) to undergo dissociation or solubility change such as elimination by the presence of an acid during the exposure step or by the acid generated from the radiation-sensitive acid generator by exposure. The above radiation-sensitive resin composition is excellent in pattern formability because the resin has the structural unit (a2).

[0060] [Chemical]

[0061] In the above formula (2), R 7 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 8 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. R 9 and R 10 each independently represent a monovalent linear hydrocarbon group having 1 to 20 carbon atoms which may or may not be substituted with a fluorine atom, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms which may or may not be substituted with a fluorine atom, or a monovalent aromatic hydrocarbon group having 5 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms which may or may not be substituted with a fluorine atom, formed by combining these groups together with the carbon atoms to which they are attached. Further, any one of R 8 to R 10 and / or, in the case where the above alicyclic group is present, the alicyclic group may have an unsaturated bond. Also, the case where a plurality of any of R 8 to R 10 together form one alicyclic structure is also included.

[0062] As the above R 7 , from the viewpoint of the copolymerizability of the monomer giving the structural unit (a2-1), a hydrogen atom and a methyl group are preferable, and a methyl group is more preferable.

[0063] Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the above R 8 include a linear hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, and the like.

[0064] Examples of the monovalent linear hydrocarbon group having 1 to 20 carbon atoms represented by the above R 9 and R 10 include a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms or a linear or branched unsaturated hydrocarbon group having 1 to 20 carbon atoms.

[0065] The above R 9 and R 10 Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by include monocyclic or polycyclic saturated hydrocarbon groups, or monocyclic or polycyclic unsaturated hydrocarbon groups. Preferred examples of the monocyclic saturated hydrocarbon group include cyclopentyl group, cyclohexyl group, cycloheptyl group, and cyclooctyl group. Preferred examples of the polycyclic cycloalkyl group include bridged alicyclic hydrocarbon groups such as norbornyl group, adamantyl group, tricyclodecyl group, and tetracyclododecyl group. Note that the bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms among the carbon atoms constituting the alicyclic ring are bonded by a bonding chain containing one or more carbon atoms.

[0066] The above R 9 and R 10 Examples of the monovalent aromatic hydrocarbon group having 5 to 20 carbon atoms represented by include aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group, and anthryl group; aralkyl groups such as benzyl group, phenethyl group, and naphthylmethyl group, and the like.

[0067] The above R 8 is preferably a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, or an alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0068] Also, any one of R 8 to R 10 and / or, in the case where the above alicyclic group is present, the alicyclic group may have an unsaturated bond.

[0069] Also, the case where a plurality of any one of R 8 to R 10 together form one alicyclic structure is also included.

[0070] The above R 8 to R 10When any of the above-mentioned plural ones are combined with each other and have at least one or more cyclic structures, the divalent alicyclic group having 3 to 20 carbon atoms, which is formed by combining an aliphatic hydrocarbon group or an alicyclic hydrocarbon group with each other together with the carbon atoms to which they are bonded, is not particularly limited as long as it is a group obtained by removing two hydrogen atoms from the same carbon atom constituting the carbon ring of the monocyclic or polycyclic alicyclic hydrocarbon having the above number of carbon atoms. It may be either a monocyclic hydrocarbon group or a polycyclic hydrocarbon group. As the polycyclic hydrocarbon group, it may be either a bridged alicyclic hydrocarbon group or a condensed alicyclic hydrocarbon group, and may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group. The condensed alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group formed by sharing sides (bonds between two adjacent carbon atoms) of a plurality of alicyclic rings.

[0071] Among the monocyclic alicyclic hydrocarbon groups, as the saturated hydrocarbon group, a cyclopentanediyl group, a cyclohexanediyl group, a cycloheptanediyl group, a cyclooctanediyl group, etc. are preferable, and as the unsaturated hydrocarbon group, a cyclopentenediyl group, a cyclohexenediyl group, a cycloheptenediyl group, a cyclooctenediyl group, a cyclodecenediyl group, etc. are preferable. As the polycyclic alicyclic hydrocarbon group, a bridged alicyclic saturated hydrocarbon group is preferable. For example, a bicyclo[2.2.1]heptane-2,2-diyl group (norbornane-2,2-diyl group), a bicyclo[2.2.2]octane-2,2-diyl group, a tricyclo[3.3.1.1 3,7 decane-2,2-diyl group (adamantane-2,2-diyl group), etc. are preferable.

[0072] The divalent linking group represented by the above L 1 includes, for example, an alkanediyl group, a cycloalkanediyl group, an alkenediyl group, * -R LA O-, * -R LB COO-, etc. (* represents a bond on the oxygen side). Some or all of the hydrogen atoms of these groups may be substituted with a halogen atom such as a fluorine atom or a chlorine atom, or a cyano group, etc.

[0073] As the above-mentioned alkanediyl group, an alkanediyl group having 1 to 8 carbon atoms is preferable.

[0074] Examples of the above-mentioned cycloalkanediyl group include monocyclic cycloalkanediyl groups such as a cyclopentanediyl group and a cyclohexanediyl group; polycyclic cycloalkanediyl groups such as a norbornanediyl group and an adamantanediyl group. As the above-mentioned cycloalkanediyl group, a cycloalkanediyl group having 5 to 12 carbon atoms is preferable.

[0075] Examples of the above-mentioned alkenediyl group include an ethenediyl group, a propenediyl group, and a butenediyl group. As the above-mentioned alkenediyl group, an alkenediyl group having 2 to 6 carbon atoms is preferable.

[0076] The above * -R LA in -R LA O- can include the above-mentioned alkanediyl group, the above-mentioned cycloalkanediyl group, the above-mentioned alkenediyl group, etc. The above * -R LB in -R LB COO- can include the above-mentioned alkanediyl group, the above-mentioned cycloalkanediyl group, the above-mentioned alkenediyl group, an arenediyl group, etc. Examples of the arenediyl group include a phenylene group, a tolylene group, and a naphthylene group. As the above-mentioned arenediyl group, an arenediyl group having 6 to 15 carbon atoms is preferable.

[0077] Among these, R 8 is an alkyl group having 1 to 4 carbon atoms, and it is preferable that R 9 and R 10 are combined with each other and the alicyclic structure formed together with the carbon atom to which they are attached is a polycyclic or monocyclic cycloalkane structure. L 1 is preferably a single bond or * -R LA O-. R LA is preferably an alkanediyl group.

[0078] As the above structural unit (a2-1), for example, structural units represented by the following formulas (2-1) to (2-6) (hereinafter, also referred to as "structural units (a2-1-1) to (a2-1-6)") and the like can be mentioned.

[0079]

Chemical formula

Chemical formula

[0080] In the above formulas (a2-1-1) to (a2-1-6), R 7 ~R 10 are the same as in the above formula (2). i and j are each independently an integer from 1 to 4. Also, the cycloalkyl ring in formula (a2-1-3) may be substituted with a halogen atom.

[0081] In the above formulas (a2-1-5) to (a2-1-6), n A is 0 or 1.

[0082] As for i and j, 1 is preferable. As R 8 ~R 10 a methyl group, an ethyl group, an isopropyl group, a t-butyl group, or a phenyl group is preferable.

[0083] Also, as the above structural unit (a2-1), structural units represented by the following formulas (2-7) to (2-8) (hereinafter, also referred to as "structural units (a2-1-7) to (a2-1-8)") and the like can be mentioned.

[0084]

Chemical formula

[0085] In the above formulas (2-7) to (2-8), each R αf is independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R βfEach is independently a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms. h1 is an integer of 1 to 4.

[0086] The above R βf is preferably a hydrogen atom, a methyl group, or an ethyl group. h1 is preferably 1 or 2.

[0087] Also, a plurality of the above R βf may together form one alicyclic structure. For example, examples can be given where two R βf together form one cyclohexane structure or benzene ring structure.

[0088] As the structural unit (a2-1), among these, the structural units (a2-1-1), (a2-1-2), (a2-1-3), (a2-1-4), (a2-1-7) are preferable, and a structural unit having a 1-alkylcycloalkyl group, a structural unit having a 1-arylcycloalkyl group, a structural unit having a cycloalkenyl group, a structural unit having a 1-alkyladamantyl group, a structural unit having an arylalkyl group, and a structural unit having a substituted or unsubstituted cycloalkylalkyl group are more preferable.

[0089] The resin (A0) may contain one or a combination of two or more of the structural units (a2).

[0090] The lower limit of the content ratio of the structural unit (a2) is preferably 10 mol%, more preferably 15 mol%, still more preferably 20 mol%, and particularly preferably 30 mol% with respect to all the structural units constituting the resin (A0) as the base resin. The upper limit of the above content ratio is preferably 90 mol%, more preferably 80 mol%, still more preferably 75 mol%, and particularly preferably 70 mol%. By setting the content ratio of the structural unit (a2) within the above range, the pattern forming property of the above radiation-sensitive resin composition can be further improved.

[0091] [Structural unit (a3)] The structural unit (a3) is a structural unit containing a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof. When the resin (A0) further has the structural unit (a3) in addition to the structural units (a1) and (a2), the polarity can be made appropriate. As a result, the above-mentioned radiation-sensitive resin composition can form a resist pattern that is finer and has an excellent rectangularity in cross-sectional shape as a chemically amplified resist material. Here, the lactone structure refers to a structure having one ring (lactone ring) containing a group represented by -O-C(O)-. The cyclic carbonate structure refers to a structure having one ring (cyclic carbonate ring) containing a group represented by -O-C(O)-O-. The sultone structure refers to a structure having one ring (sultone ring) containing a group represented by -O-S(O)2-.

[0092] Examples of the structural unit (a3) include structural units represented by the following formulas.

[0093]

Chemical formula

[0094]

Chemical formula

[0095]

Chemical formula

[0096]

Chemical formula

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

[0098] The above R ALFrom the viewpoint of the copolymerizability of the monomer that provides the structural unit (a3), a hydrogen atom and a methyl group are preferable, and a methyl group is more preferable.

[0099] Among these, as the structural unit (a3), a structural unit containing a norbornane lactone structure, a structural unit containing an oxanorbornane lactone structure, a structural unit containing a γ-butyrolactone structure, a structural unit containing an ethylene carbonate structure, and a structural unit containing a norbornane sultone structure are preferable, and a structural unit derived from norbornane lactone-yl (meth)acrylate, a structural unit derived from oxanorbornane lactone-yl (meth)acrylate, a structural unit derived from cyano-substituted norbornane lactone-yl (meth)acrylate, a structural unit derived from norbornane lactone-yloxycarbonylmethyl (meth)acrylate, a structural unit derived from butyrolactone-3-yl (meth)acrylate, a structural unit derived from butyrolactone-4-yl (meth)acrylate, a structural unit derived from 3,5-dimethylbutyrolactone-3-yl (meth)acrylate, a structural unit derived from 4,5-dimethylbutyrolactone-4-yl (meth)acrylate, a structural unit derived from 1-(butyrolactone-3-yl)cyclohexane-1-yl (meth)acrylate, a structural unit derived from ethylene carbonate-ylmethyl (meth)acrylate, a structural unit derived from cyclohexene carbonate-ylmethyl (meth)acrylate, a structural unit derived from norbornane sultone-yl (meth)acrylate, and a structural unit derived from norbornane sultone-yloxycarbonylmethyl (meth)acrylate are more preferable.

[0100] When the resin (A0) has the structural unit (a3), the lower limit of the content ratio of the structural unit (a3) to all the structural units constituting the resin (A0) is preferably 1 mol%, more preferably 10 mol%, still more preferably 20 mol%, and particularly preferably 25 mol%. On the other hand, as the upper limit of the above content ratio, 70 mol% is preferable, 65 mol% is more preferable, 60 mol% is still more preferable, and 55 mol% is particularly preferable. By setting the above content ratio within the above range, a resist pattern that is finer and has excellent rectangularity in cross-sectional shape can be formed.

[0101] [Structural unit (a4)] The resin (A0) may appropriately have other structural units other than the above structural units (a1) to (a3) (also referred to as structural unit (a4)). Examples of the structural unit (a4) include structural units having a fluorine atom, an alcoholic hydroxyl group, a carboxy group, a cyano group, a nitro group, a sulfonamide group, etc. Among these, a structural unit having a fluorine atom, a structural unit having an alcoholic hydroxyl group, and a structural unit having a carboxy group are preferable, and a structural unit having a fluorine atom and a structural unit having an alcoholic hydroxyl group are more preferable.

[0102] When the resin (A0) has the structural unit (a4), the lower limit of the content ratio of the structural unit (a4) to all the structural units constituting the resin (A0) is preferably 1 mol%, more preferably 5 mol%, and still more preferably 10 mol%. On the other hand, as the upper limit of the above content ratio, 50 mol% is preferable, 40 mol% is more preferable, and 30 mol% is still more preferable. By setting the content ratio of other structural units within the above range, the solubility of the resin (A0) in the developer can be made more appropriate. If the content ratio of other structural units exceeds the above upper limit, the pattern formability may decrease.

[0103] Also, in the resin (A0) of the present invention, for example, (i) a repeating structure of hydroxystyrene obtained by polymerizing a hydroxystyrene monomer protected with an alkali-hydrolyzable group and then hydrolyzing it, and (ii) a repeating structure obtained by polymerizing a hydroxystyrene monomer as it is can both correspond to the above structural unit (a1). Further, (iii) a repeating structure obtained by polymerizing a hydroxystyrene monomer in which a hydroxyl group is protected with a group dissociable by EUV or electron beam (EB) exposure can correspond to the above "structural unit (a2)".

[0104] The content of the resin (A0) is usually 85% by mass or more in the total solid content of the above radiation-sensitive resin composition. Among them, 95% by mass or more is preferable, 99% by mass or more is more preferable, 99.9% by mass or more is further preferable, and 99.99% by mass or more is particularly preferable. Here, the "solid content" refers to all the components contained in the above radiation-sensitive resin composition excluding the (B) solvent.

[0105] (Synthesis method of resin (A0)) The resin (A0) as the base resin can be synthesized, for example, by carrying out a polymerization reaction of monomers giving each structural unit in a suitable solvent using a radical polymerization initiator or the like.

[0106] Examples of the above radical polymerization initiators include azo-based 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), dimethyl 2,2'-azobisisobutyrate; peroxide-based radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, etc. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferable, and AIBN is more preferable. These radical initiators can be used alone or in combination of two or more.

[0107] Examples of the solvent used in the above polymerization reaction 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; alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol. These solvents used in the polymerization reaction may be used alone or in combination of two or more.

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

[0109] The molecular weight of the resin (A0) as the base resin is not particularly limited, but the polystyrene-equivalent weight average molecular weight (Mw) by gel permeation chromatography (GPC) is preferably 1,000 or more and 50,000 or less, more preferably 2,000 or more and 30,000 or less, still more preferably 3,000 or more and 15,000 or less, and particularly preferably 4,000 or more and 12,000 or less. If the Mw of the resin (A0) is less than the above lower limit, the heat resistance of the obtained resist film may decrease. If the Mw of the resin (A0) exceeds the above upper limit, the developability of the resist film may decrease.

[0110] The ratio (Mw / Mn) of Mw to the polystyrene-equivalent number average molecular weight (Mn) by GPC of the resin (A0) as the base resin 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. GPC column: 2 pieces of G2000HXL, 1 piece of G3000HXL, 1 piece of G4000HXL (all manufactured by Tosoh Corporation) Column temperature: 40 °C Elution solvent: Tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0 mass% Sample injection volume: 100 μL Detector: Differential refractometer Standard substance: Monodisperse polystyrene

[0112] (Other resins) The radiation-sensitive resin composition of this embodiment may contain, as another resin, a resin having a higher mass content of fluorine atoms than the above base resin (hereinafter, also referred to as "high-fluorine content resin"). When the radiation-sensitive resin composition contains a high-fluorine content resin, it can be unevenly distributed on the surface layer of the resist film with respect to the above base resin. As a result, the state of the resist film surface and the component distribution in the resist film can be controlled to a desired state.

[0113] The high-fluorine content resin preferably has, for example, a structural unit represented by the following formula (3) (hereinafter, also referred to as "structural unit (a5)"). [Chemical formula]

[0114] In the above formula (3), R 13 is a hydrogen atom, a methyl group, or a trifluoromethyl group. G is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2ONH-, -CONH-, or -OCONH-. R 14 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.

[0115] The above R13 From the viewpoint of the copolymerizability of the monomer that provides the structural unit (a5), a hydrogen atom and a methyl group are preferable, and a methyl group is more preferable.

[0116] The above G L From the viewpoint of the copolymerizability of the monomer that provides the structural unit (a5), a single bond and -COO- are preferable, and -COO- is more preferable.

[0117] The above R 14 Examples of the monovalent fluorinated chain hydrocarbon group represented by the above R having 1 to 20 carbon atoms include those in which part or all of the hydrogen atoms of a linear or branched alkyl group having 1 to 20 carbon atoms are substituted by fluorine atoms.

[0118] The above R 14 Examples of the monovalent fluorinated alicyclic hydrocarbon group represented by the above R having 3 to 20 carbon atoms include those in which part or all of the hydrogen atoms of a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms are substituted by fluorine atoms.

[0119] The above R 14 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.

[0120] When the high fluorine content resin has the structural unit (a5), the lower limit of the content ratio of the structural unit (a5) is preferably 10 mol%, more preferably 15 mol%, even more preferably 20 mol%, and particularly preferably 25 mol% with respect to all the structural units constituting the high fluorine content resin. The upper limit of the above content ratio is preferably 60 mol%, more preferably 50 mol%, and even more preferably 40 mol%. By setting the content ratio of the structural unit (a5) within the above range, the mass content ratio of fluorine atoms in the high fluorine content resin can be adjusted more appropriately, and the uneven distribution on the surface layer of the resist film can be further promoted.

[0121] In addition to the structural unit (a5), 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 the structural unit (a6)). 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. [Chemical formula]

[0122] The structural unit (a6) is roughly classified into two cases: (x) having an alkali-soluble group and (y) having a group that dissociates by the action of an alkali and increases solubility in an alkaline developer (hereinafter also simply referred to as an "alkali-dissociable group"). Commonly to both (x) and (y), in the above formula (f-2), R C is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R D is a single bond, an (s + 1)-valent hydrocarbon group having 1 to 20 carbon atoms, a structure in which an oxygen atom, a sulfur atom, -NR E -, a carbonyl group, -COO- or -CONH- is bonded to the terminal on the R dd side, or a structure in which a part of the hydrogen atoms of this hydrocarbon group is substituted by an organic group having a heteroatom. R dd is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer of 1 to 3.

[0123] When the structural unit (a6) has an (x) alkali-soluble group, R F is a hydrogen atom, and A 1 is an oxygen atom, -COO-* or -SO2O-*. * indicates the bonding site to R F . W 1 is a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group. When A 1 is an oxygen atom, W 1 is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group at the carbon atom to which A 1 is bonded. R Eis a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, a plurality of R E , W 1 , A 1 and R F may be the same or different from each other. By having the structural unit (a6) having the (x) alkali-soluble group, the affinity for the alkali developer can be increased and development defects can be suppressed. As the structural unit (a6) having the (x) alkali-soluble group, A 1 is an oxygen atom and W 1 is particularly preferably a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.

[0124] When the structural unit (a6) has the (y) alkali-dissociable group, 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. * indicates the bonding site to R F . W 1 is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R E is a single bond or a divalent organic group having 1 to 20 carbon atoms. When A 1 is -COO-* or -SO2O-*, W 1 or R F has a fluorine atom on the carbon atom bonded to A 1 or the carbon atom adjacent thereto. When A 1 is an oxygen atom, W 1 , R E is a single bond, and R D is a structure in which a carbonyl group is bonded to the end on the R E side of a hydrocarbon group having 1 to 20 carbon atoms, and R F is an organic group having a fluorine atom. When s is 2 or 3, a plurality of R E , W 1 , A 1 and R FThey may be the same or different from each other. Since the structural unit (a6) has a (y) alkali-dissociable group, the surface of the resist film changes from hydrophobic to hydrophilic in the alkali development process. As a result, the affinity for the developer is significantly increased, and development defects can be suppressed more efficiently. As the structural unit (a6) having a (y) alkali-dissociable group, A 1 is -COO-*, and R F or W 1 or both of them having a fluorine atom are particularly preferred.

[0125] R C From the viewpoint of the copolymerizability of the monomer that gives the structural unit (a6), a hydrogen atom and a methyl group are preferred, and a methyl group is more preferred.

[0126] R E When it is a divalent organic group, a group having a lactone structure is preferred, a group having a polycyclic lactone structure is more preferred, and a group having a norbornane lactone structure is more preferred.

[0127] When the high-fluorine content resin has the structural unit (a6), the lower limit of the content ratio of the structural unit (a6) is preferably 10 mol%, more preferably 20 mol%, still more preferably 30 mol%, and particularly preferably 35 mol% with respect to all the structural units constituting the high-fluorine content resin. The upper limit of the above content ratio is preferably 90 mol%, more preferably 75 mol%, and still more preferably 60 mol%. By setting the content ratio of the structural unit (a6) within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0128] The lower limit of the Mw of the high-fluorine content resin is preferably 1,000, more preferably 2,000, still more preferably 3,000, and particularly preferably 5,000. The upper limit of the above Mw is preferably 50,000, more preferably 30,000, still more preferably 20,000, and particularly preferably 15,000.

[0129] 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 above Mw / Mn is usually 5, preferably 3, more preferably 2, and even more preferably 1.7.

[0130] As the lower limit of the content of the high fluorine content resin, 0.1% by mass is preferable, 0.5% by mass is more preferable, 1% by mass is even more preferable, and 1.5% by mass is even more preferable with respect to the total solid content in the above radiation-sensitive resin composition. The upper limit of the above content is preferably 20% by mass, more preferably 15% by mass, even more preferably 10% by mass, and particularly preferably 7% by mass.

[0131] As the lower limit of the content of the high fluorine content resin, 0.1 part by mass is preferable, 0.5 part by mass is more preferable, 1 part by mass is even more preferable, and 1.5 parts by mass is particularly preferable with respect to 100 parts by mass of the above base resin. The upper limit of the above content is preferably 15 parts by mass, more preferably 10 parts by mass, even more preferably 8 parts by mass, and particularly preferably 5 parts by mass.

[0132] By setting the content of the high fluorine content resin within the above range, the high fluorine content resin can be more effectively unevenly distributed on the surface layer of the resist film. As a result, the water repellency of the surface of the resist film during immersion exposure can be further enhanced. The above radiation-sensitive resin composition may contain one or more high fluorine content resins.

[0133] (Synthesis method of high fluorine content resin) The high fluorine content resin can be synthesized by the same method as the synthesis method of the above base resin.

[0134] ((B) Solvent) The above radiation-sensitive resin composition contains a solvent. The solvent is not particularly limited as long as it can dissolve or disperse at least a resin, a radiation-sensitive acid generator, and optional components contained as desired.

[0135] Examples of the solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents, and the like.

[0136] Examples of the alcohol solvents include monohydric alcohol 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; polyhydric alcohol partial ether solvents in which a part of the hydroxy groups of the above polyhydric alcohol solvents are etherified, and the like.

[0137] Examples of the 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); polyhydric alcohol ether solvents in which the hydroxy groups of the above polyhydric alcohol solvents are etherified, and the like.

[0138] Examples of the ketone solvents include chain ketone solvents such as acetone, butanone, and methyl-iso-butyl ketone: cyclic ketone solvents such as cyclopentanone, cyclohexanone, and methylcyclohexanone: 2,4-pentanedione, acetonylacetone, acetophenone, and the like.

[0139] Examples of amide solvents include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; and chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0140] Examples of ester solvents include, for example, 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; and polycarboxylic acid diester solvents such as propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, ethyl lactate, and diethyl phthalate.

[0141] Examples of hydrocarbon solvents include, for example, aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, di-iso-propylbenzene, and n-amylnaphthalene.

[0142] Among these, ester solvents and ketone solvents are preferred, polyhydric alcohol partial ether acetate solvents, cyclic ketone solvents, and lactone solvents are more preferred, and propylene glycol monomethyl ether acetate, cyclohexanone, and γ-butyrolactone are even more preferred. The above radiation-sensitive resin composition may contain one or more solvents.

[0143] ((C) Radiation-sensitive acid generator) The radiation-sensitive resin composition of the present invention may contain a radiation-sensitive acid generator. As the (C) radiation-sensitive acid generator, an onium salt compound is preferable, and a sulfonium salt compound and an iodonium salt are more preferable. As such an onium salt compound, known compounds can be used.

[0144] Also, in the present invention, when the (C) radiation-sensitive acid generator is contained in the above (A) radiation-sensitive resin composition, it is desirable that the amount of the (C) radiation-sensitive acid generator is small. In the above (A) radiation-sensitive resin composition, for example, the (C) radiation-sensitive acid generator is preferably 0.1% by mass or less, more preferably 0.05% by mass or less, and even more preferably 0.01% by mass or less based on the total of the components other than the (B) solvent. As examples of the lower limit of the above blending amount, 0.0001% by mass and 0.00001% by mass can be mentioned, but it is desirable that the (C) radiation-sensitive acid generator is not contained (0% by mass).

[0145] As described above, in the present invention, it is not necessary that dissociation such as elimination or a change in solubility of the above structural unit (a2) occurs due to the presence of an acid during the exposure process or an acid generated from the radiation-sensitive acid generator by exposure. Further, in the radiation-sensitive resin composition and the resist film of the present invention, by making the (C) radiation-sensitive acid generator not contained or substantially not present, the components of the resist film are simplified, so that the uniformity is improved, and the adverse effects at the interface between the exposed portion and the unexposed portion due to the acid generated during the exposure process are suppressed. As a result, the various resist performances can be more surely improved. Therefore, it is particularly desirable that the above (C) radiation-sensitive acid generator is not contained or substantially not present in the radiation-sensitive resin composition and the resist film of the present invention.

[0146] (Other optional components) In addition to the above components, the radiation-sensitive resin composition may contain other optional components. Examples of the other optional components include an acid diffusion controller, a crosslinking agent, a phase separation accelerator, a surfactant, an alicyclic skeleton-containing compound, a sensitizer, and the like. These other optional components may be used alone or in combination of two or more thereof.

[0147] ((D) Acid diffusion controller) The radiation-sensitive resin composition may contain an acid diffusion controller as necessary. The acid diffusion controller controls the diffusion phenomenon of the acid generated from the radiation-sensitive acid generator by exposure in the resist film, and has the effect of suppressing an undesirable chemical reaction in the unexposed region. In addition, the storage stability of the resulting radiation-sensitive resin composition is improved. Furthermore, the resolution of the resist pattern is further improved, and the line width change of the resist pattern due to the variation in the standing time from exposure to development processing can be suppressed, and a radiation-sensitive resin composition excellent in process stability can be obtained.

[0148] (Crosslinking agent) The crosslinking agent is a compound having two or more functional groups, and in the baking step after the batch exposure step, it causes a crosslinking reaction in the polymer component by an acid-catalyzed reaction, increases the molecular weight of the polymer component, and thereby reduces the solubility of the pattern-exposed portion in the developer. Examples of the above functional groups include a (meth)acryloyl group, a hydroxymethyl group, an alkoxymethyl group, an epoxy group, a vinyl ether group, and the like.

[0149] (Phase separation accelerator) The segregation promoter has the effect of more efficiently segregating the high-fluorine content resin on the resist film surface. By incorporating this segregation promoter into the above-described radiation-sensitive resin composition, the addition amount of the high-fluorine content resin can be made less than before. Therefore, while maintaining the lithography performance of the radiation-sensitive resin composition, elution of components from the resist film into the immersion medium can be further suppressed, or immersion exposure can be performed at a higher speed by high-speed scanning, and as a result, the hydrophobicity of the resist film surface that suppresses immersion-derived defects such as watermark defects can be improved. Examples of such a segregation promoter that can be used include low-molecular compounds having a relative dielectric constant of 30 or more and 200 or less and a boiling point of 100°C or more at 1 atm. Specific examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, polyhydric alcohols, and the like.

[0150] (Surfactant) Surfactants have the effect of improving coatability, striation, developability, and the like. 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, No. 95 (manufactured by Kyoeisha Chemical Co., Ltd.), F-Top EF301, EF303, EF352 (manufactured by Tocem Products Co., Ltd.), Megafac F171, F173 (manufactured by DIC Corporation), Fluorad FC430, FC431 (manufactured by Sumitomo 3M Limited), Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (manufactured by Asahi Glass Co., Ltd.), and the like. The content of the surfactant in the above-described radiation-sensitive resin composition is usually 2 parts by mass or less with respect to 100 parts by mass of the resin.

[0151] (Alicyclic skeleton-containing compound) The alicyclic skeleton-containing compound has the effect of improving dry etching resistance, pattern shape, adhesion to the substrate, etc.

[0152] Examples of the alicyclic skeleton-containing compound include adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and t-butyl 1-adamantanecarboxylate; deoxycholic acid esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholate, and 2-ethoxyethyl deoxycholate; lithocholic acid esters such as t-butyl lithocholate, t-butoxycarbonylmethyl lithocholate, and 2-ethoxyethyl lithocholate; 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. can be mentioned. The content of the alicyclic skeleton-containing compound in the above radiation-sensitive resin composition is usually 5 parts by mass or less with respect to 100 parts by mass of the resin.

[0153] (Sensitizer) The sensitizer exhibits the action of increasing the amount of acid generated from a radiation-sensitive acid generator or the like, and has the effect of improving the "apparent sensitivity" of the above radiation-sensitive resin composition.

[0154] Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines, etc. These sensitizers may be used alone or in combination of two or more. The content of the sensitizer in the above radiation-sensitive resin composition is usually 2 parts by mass or less with respect to 100 parts by mass of the resin.

[0155] <Method for preparing a radiation-sensitive resin composition> The above-mentioned (A) radiation-sensitive resin composition can be prepared, for example, by mixing a resin (A0), a (B) solvent, and, if necessary, other components at a predetermined ratio. After mixing, the above-mentioned radiation-sensitive resin composition is preferably filtered, for example, through a filter with a pore size of about 0.05 μm. The solid content concentration of the above-mentioned radiation-sensitive resin composition is usually 0.1% by mass to 50% by mass, preferably 0.5% by mass to 30% by mass, and more preferably 1% by mass to 20% by mass.

[0156] <Resist Pattern Formation Method> The resist pattern formation method in the present invention includes a step (1) of forming a resist film in which the content of a (C) radiation-sensitive acid generator is 0.1% by mass or less (hereinafter, also referred to as the "resist film formation step"), a step (2) of exposing the above-mentioned resist film to EUV or an electron beam (EB) (hereinafter, also referred to as the "exposure step"), and a step (3) of developing the resist film exposed in the above-mentioned step (2) (hereinafter, also referred to as the "development step").

[0157] According to the above-mentioned resist pattern formation method, since a resist film or the like in which the content of the (C) radiation-sensitive acid generator formed using the above-mentioned radiation-sensitive resin composition or the like is 0.1% by mass or less is used, a resist pattern capable of exhibiting excellent sensitivity and resolution levels in the exposure step can be formed. Hereinafter, each step will be described.

[0158] [Resist Film Formation Step] In this step (the above step (1)), a resist film is formed using the above radiation-sensitive resin composition or the like. Examples of the substrate on which this resist film is formed include conventionally known ones such as silicon wafers, silicon dioxide, and wafers coated with aluminum. Further, for example, an organic or inorganic antireflection film disclosed in Japanese Patent Publication No. 6-12452, Japanese Patent Application Laid-Open No. 59-93448, etc. may be formed on the substrate. Examples of the coating method include spin coating, casting coating, roll coating, etc. After coating, pre-baking (PB) may be performed as necessary to volatilize the solvent in the coating film. The PB temperature is usually 60°C to 140°C, preferably 80°C to 120°C. The PB time is usually 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds. The film thickness of the formed resist film is preferably 10 nm to 1,000 nm, more preferably 10 nm to 500 nm.

[0159] When performing liquid immersion exposure, regardless of the presence or absence of a water-repellent polymer additive such as the high-fluorine content resin in the above radiation-sensitive resin composition, for the purpose of avoiding direct contact between the liquid immersion medium and the resist film, a liquid immersion protective film insoluble in the liquid immersion medium may be provided on the formed resist film. As the liquid immersion protective film, a solvent peelable protective film that peels off with a solvent before the development process (see, for example, Japanese Patent Application Laid-Open No. 2006-227632), or a developer peelable protective film that peels off simultaneously with the development in the development process (see, for example, WO2005-069076, WO2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer peelable liquid immersion protective film.

[0160] Further, when the next exposure step is performed with radiation having a wavelength of 50 nm or less, it is preferable to use a resin having the structural units (a1) and (a2) as the base resin in the above composition.

[0161] Further, the above step (1) is a step of forming a resist film in which the content of the (C) radiation-sensitive acid generator is 0.1% by mass or less, and for forming the above resist film, known methods can be appropriately used. The above resist film can be formed, for example, by using the above resin (A0) or the like. More specifically, for example, the above resist film can be easily formed by an (A) radiation-sensitive resin composition in which the (C) radiation-sensitive acid generator is 0.1% by mass or less based on the total of components other than the (B) solvent in the (A) radiation-sensitive resin composition. Alternatively, for example, the above resist film can be easily formed by an (A) radiation-sensitive resin composition that does not contain a radiation-sensitive acid generator.

[0162] Further, in the resist film formed in the above step (1), the content of the (C) radiation-sensitive acid generator is 0.1% by mass or less. When the (C) radiation-sensitive acid generator is contained in the resist film, it is desirable that the amount of the (C) radiation-sensitive acid generator is small. For example, in the resist film, the above (C) radiation-sensitive acid generator is more preferably 0.05% by mass or less, and even more preferably 0.01% by mass or less. On the other hand, as the lower limit of the above blending amount, it is desirable that the (C) radiation-sensitive acid generator is not contained (0% by mass).

[0163] As described above, in the present invention, for example, it is not necessary that dissociation or solubility change such as elimination of the above structural unit (a2) occurs due to the presence of an acid during the exposure step or an acid generated from the radiation-sensitive acid generator by exposure. Further, in the resist film in the present invention, by making the (C) radiation-sensitive acid generator not contained or substantially not present, the components of the resist film are simplified, so that the uniformity is improved, and the adverse effects at the interface between the exposed portion and the unexposed portion due to the acid generated during the exposure step are suppressed. As a result, the various resist performances can be more reliably improved. Therefore, it is particularly desirable that the above (C) radiation-sensitive acid generator is not contained or substantially not present in the resist film in the present invention.

[0164] [Exposure step] In this step (the above step (2)), radiation is irradiated and the resist film formed in the resist film formation step which is the above step (1) is exposed through a photomask (in some cases, through an immersion medium such as water). As the radiation used for exposure, for example, EUV (extreme ultraviolet rays) or electron beam (EB) can be mentioned according to the line width of the target pattern.

[0165] When exposure is performed by immersion exposure, examples of the immersion medium that can be used include water, fluorine-based inert liquids, etc. The immersion medium is preferably a liquid that is transparent to the exposure wavelength and has a temperature coefficient of refractive index as small as possible so as to minimize the distortion of the optical image projected onto the film. When using water, an additive that reduces the surface tension of water and increases the interfacial activity may be added in a small proportion. This additive is preferably one that does not dissolve the resist film on the wafer and has a negligible effect on the optical coating on the lower surface of the lens. Distilled water is preferred as the water to be used.

[0166] In the present invention, after the above exposure, a difference in solubility in the developer occurs between the exposed portion and the unexposed portion. In the present invention, since it does not contain or substantially does not contain a radiation-sensitive acid generator, basically, post-exposure baking (PEB) for the purpose of promoting the dissociation of acid-dissociable groups of resins and the like by the acid generated from the radiation-sensitive acid generator is not necessary after the above exposure. However, in all embodiments of the present invention, it does not exclude performing PEB as a heat treatment for a purpose different from the purpose of generating acid from the radiation-sensitive acid generator after exposure. The PEB temperature as the above heat treatment is, for example, 50°C to 180°C, and 80°C to 130°C can be mentioned. Also, the PEB time as the above heat treatment is, for example, 5 seconds to 600 seconds, and 10 seconds to 300 seconds can be mentioned.

[0167] [Development step] In this step (the above step (3)), the resist film exposed in the above exposure step (step (2)) is developed. Thereby, a predetermined resist pattern can be formed. After development, it is common to wash with a rinse solution such as water or alcohol and then dry.

[0168] In addition, in the above step (3), in one embodiment, development can be performed with an organic solvent to form a negative pattern.

[0169] In addition, in the above step (3), in one embodiment, development can be performed with an alkaline developer to form a positive pattern.

[0170] As the developer used for the above development, in the case of alkaline development, for example, an alkaline aqueous solution in which at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, 1,5-diazabicyclo-[4.3.0]-5-nonene is dissolved can be mentioned. Among these, an aqueous TMAH solution is preferable, and an aqueous 2.38 mass% TMAH solution is more preferable.

[0171] In the case of organic solvent development, examples of the organic solvent include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, and solvents containing an organic solvent. Examples of the above organic solvent include one or more of the solvents listed as the solvent of the above radiation-sensitive resin composition. Among these, ester solvents and ketone solvents are preferred. As the ester solvent, an acetate ester solvent is preferred, and n-butyl acetate and amyl acetate are more preferred. As the ketone solvent, a chain ketone is preferred, and 2-heptanone is 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, further preferably 95% by mass or more, and particularly preferably 99% by mass or more. Examples of the components other than the organic solvent in the developer include water, silicone oil, and the like.

[0172] Examples of the development method include a method of immersing a substrate in a tank filled with a developer for a certain period of time (dip method), a method of developing by raising the developer on the substrate surface by surface tension and allowing it to stand for a certain period of time (paddle method), a method of spraying the developer on the substrate surface (spray method), and a method of continuously ejecting the developer while scanning a developer ejection nozzle at a constant speed on a substrate rotating at a constant speed (dynamic dispense method).

[0173] <Substrate processing method, method for manufacturing a metal film pattern> The substrate processing method in the present invention is further includes a step (4-1) of forming a pattern on the substrate using the resist pattern formed by any of the above methods as a mask.

[0174] The method for manufacturing a metal film pattern in the present invention is further includes a step (4-2) of forming a metal film using the resist pattern formed by any of the methods described above as a mask.

[0175] Since the method for processing the substrate and the method for manufacturing the metal film pattern use the radiation-sensitive resin composition or the resist film, they can function as a resist film in a conventional exposure process or the like without substantially containing a conventional radiation-sensitive acid generator (C). As a result, it is possible to process a high-quality substrate pattern and a high-quality metal film pattern, respectively.

[0176] The above step (4-1) is a step of forming a pattern on a substrate using a resist pattern formed by any of the described methods as a mask. Examples of the method of forming a pattern on a substrate using a resist pattern as a mask include, for example, a method of forming a pattern on the substrate by a method such as dry etching on the portion without resist after forming a resist pattern on the substrate, or a method of depositing substrate constituent components by CVD or the like or attaching a metal by electroless plating or the like on the portion without resist after forming a resist pattern to form part or all of the substrate.

[0177] The above step (4-2) is a step of forming a metal film using a resist pattern formed by any of the described methods as a mask. Examples of the method of forming a metal film using a resist pattern as a mask include, for example, a method of forming a metal film by attaching a metal by electroless plating or the like on the portion without resist after forming a resist pattern, or a method of forming a resist pattern on the metal film and removing the metal film on the portion without resist by a method such as dry etching to form a metal film.

Examples

[0178] Next, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples. The measurement methods for various physical property values are shown below.

[0179] [Measurement of weight average molecular weight (Mw), number average molecular weight (Mn), and dispersity (Mw / Mn)] The Mw and Mn of the polymers used in the examples were measured by gel permeation chromatography (GPC) using Tosoh GPC columns (two G2000HXL columns, one G3000HXL column, and one G4000HXL column), a flow rate of 1.0 mL / min, a elution solvent of tetrahydrofuran, a sample concentration of 1.0 mass%, a sample injection volume of 100 μL, a column temperature of 40 °C, and a differential refractometer as the detector, with monodisperse polystyrene as the standard. Also, the dispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[0180] <[A] Synthesis of Polymer> The monomers used in the synthesis of each polymer in each example and comparative example are shown below. In the following synthesis examples, unless otherwise specified, parts by mass mean the value when the total mass of the monomers used is 100 parts by mass, and mol% means the value when the total number of moles of the monomers used is 100 mol%.

[0181]

Chemical Formula

[0182] [Synthesis Example 1] (Synthesis of Polymer (A-1)) Compound (M-1) and compound (M-4) were dissolved in 1-methoxy-2-propanol (200 parts by mass relative to the total monomer amount) so that the molar ratio was 40 / 60. Next, azobisisobutyronitrile was added as an initiator at 6 mol% relative to the total monomers to prepare a monomer solution. On the other hand, 1-methoxy-2-propanol (100 parts by mass relative to the total monomer amount) was added to an empty reaction vessel and heated to 85 °C with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours, and then further heated at 85 °C for 3 hours to carry out a polymerization reaction for a total of 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to room temperature.

[0183] Thereafter, the polymer solution cooled was poured into hexane (500 parts by mass with respect to the polymer solution), and the precipitated white powder was filtered off. The filtered white powder was washed twice with 100 parts by mass of hexane with respect to the polymer solution, then filtered off and dissolved in 1-methoxy-2-propanol (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass) and ultrapure water (10 parts by mass) were added, and a hydrolysis reaction was carried out at 70 °C for 6 hours while stirring.

[0184] After completion of the reaction, the residual solvent was distilled off, and the obtained solid was dissolved in acetone (100 parts by mass). It was dropped into 500 parts by mass of water to coagulate the resin, and the obtained solid was filtered off. It was dried at 50 °C for 12 hours to synthesize a white powdery polymer (A-1).

[0185] The Mw of the obtained polymer (A-1) was 5,700, and Mw / Mn was 1.61.

[0186] [Synthesis Examples 2 to 18] (Synthesis of Polymers (A-2) to (A-12)) According to the formulations in Table 1, monomers were each selected, and by performing the same operations as in Synthesis Example 1, polymers (A-2) to (A-12), (A-14) were synthesized. Also, the Mw and Mw / Mn of the obtained polymers (A-2) to (A-12) are shown in Table 1.

[0187] The formulation details and preparation results of each synthesis example are shown in Table 1 below.

[0188]

Table 1

[0189] [Preparation of Radiation-Sensitive Resin Composition] The [C] acid generator, [D] acid diffusion controller, and [B] solvent used for the preparation of the radiation-sensitive resin compositions in Examples and Comparative Examples are shown below.

[0190] [[C] Acid Generator] The structural formula of the acid generator is shown below. [Chemical formula]

[0191] [D] Acid diffusion control agent The structural formula of the acid diffusion control agent is shown below. [Chemical formula]

[0192] [B] Organic solvent The organic solvents are shown below. B-1: Propylene glycol monomethyl ether acetate B-2: Propylene glycol 1-monomethyl ether

[0193] [Example 1] [A] 100 parts by mass of (A-1) as a polymer, and [B] 12,200 parts by mass of (B-1) and 5,200 parts by mass of (B-2) as organic solvents were mixed and filtered through a 20 nm membrane filter to prepare a radiation-sensitive resin composition (R-1).

[0194] [Examples 2 to 18 and Comparative Example 1] (Radiation-sensitive resin compositions (R-2) to (R-18) and (CR-1)) Each radiation-sensitive resin composition was prepared in the same manner as in Example 1, except that the components of the types and blending amounts shown in Table 2 below were used.

[0195] [Table 2]

[0196] [Formation of resist pattern by EUV exposure and alkali development] On the surface of a 12-inch silicon wafer on which a lower layer film (AL412, manufactured by Brewer Science) with a film thickness of 20 nm was formed, each radiation-sensitive resin composition described in Table 2 was applied using a spin coater (CLEAN TRACK ACT12, manufactured by Tokyo Electron), and pre-baked (PB) at 100 °C for 60 seconds. Then, it was cooled at 23 °C for 30 seconds to form a resist film with a film thickness of 20 nm.

[0197] Next, the obtained resist film was irradiated with EUV light using an EUV exposure machine (model "NXE3300", manufactured by ASML, NA = 0.33, illumination condition: Dipole). After irradiation, the resist film was developed at 23 °C for 30 seconds using a 2.38 wt% TMAH aqueous solution, then washed with water and further dried to form a positive line-and-space resist pattern.

[0198] [Evaluation] For each of the above-formed resist patterns, the sensitivity and resolution of each radiation-sensitive resin composition were evaluated by measuring according to the following method. A scanning electron microscope ("CG-4100" of Hitachi High-Technologies Corporation) was used for measuring the length of the resist pattern. The evaluation results are shown in Table 3 below.

[0199] [Sensitivity] In the formation of the above resist pattern, the exposure dose for forming an 18 nm line-and-space pattern was defined as the optimum exposure dose, and this optimum exposure dose was defined as the sensitivity (mJ / cm 2 ). When the sensitivity was 100 mJ / cm 2 or less, it was determined as "good", and when it exceeded 100 mJ / cm2, it was determined as "bad".

[0200] [Resolution] At the above optimum exposure dose, when the size of the mask pattern for forming a line-and-space (1L / 1S) was changed, the dimension of the smallest resist pattern that could be resolved was measured, and this measured value was defined as the resolution (nm). The smaller the value of the resolution, the better. When the resolution was less than 18 nm, it was evaluated as good, and when it was 18 nm or more, it was evaluated as bad.

[0201] The formation results of each resist pattern are shown in Table 3 below.

[0202]

Table 3

[0203] [Synthesis Example 19] (Synthesis of Polymer (A-19)) Compound (M-5) and (M-13) were dissolved in 2-butanone (200 parts by mass) so that the molar ratio was 60 / 40 (mol%), and AIBN (azobisisobutyronitrile) (8 mol% based on 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 inside of the reaction vessel was set to 80°C, and the above monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled with water to 30°C or lower. 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, then filtered and dried at 50°C for 10 hours to obtain a white powder polymer (A-19). The Mw of polymer (A-19) was 5,700, and Mw / Mn was 1.61. Also, 13 As a result of C-NMR analysis, the content ratios of the respective structural units derived from (M-5) and (M-13) were 58.5 mol% and 41.5 mol%, respectively.

[0204] [Synthesis Example 20] (Synthesis of Polymer (A-20)) According to the formulation in Table 4, monomers were each selected, and a polymer (A-20) was synthesized by performing the same operations as in Synthesis Example 1. Also, the Mw and Mw / Mn of the obtained polymer (A-20) are shown in Table 4.

[0205] The formulation details and preparation results of each synthesis example are shown in Table 4 below.

[0206]

Table 4

[0207] <Preparation of Radiation-Sensitive Resin Composition> [Example 19] (Radiation-Sensitive Resin Composition (R-19)) [A] 100 parts by mass of (A-19) as a polymer, and [B] 12,200 parts by mass of (B-1) and 5,200 parts by mass of (B-2) as organic solvents were mixed and filtered through a 20 nm membrane filter to prepare a radiation-sensitive resin composition (R-19).

[0208] [Example 20] (Radiation-Sensitive Resin Composition (R-20)) Except for using each component of the types and blending amounts shown in Table 5 below, the same operations as in Example 19 were performed to prepare each radiation-sensitive resin composition.

[0209] [Table 5]

[0210] [Formation of Resist Pattern by EUV Exposure and Alkaline Development] Using the radiation-sensitive resin composition (R-19) or (R-20), a positive line-and-space resist pattern was formed in the same manner as described above.

[0211] [Evaluation] For each of the resist patterns formed above, the sensitivity and resolution were evaluated in the same manner as described above. The evaluation results are shown in Table 6 below.

[0212] [Table 6]

[0213] As shown in Tables 3 and 6, in any of the examples, the radiation-sensitive resin composition had good sensitivity and resolution in the exposure process. On the other hand, the radiation-sensitive resin composition in the comparative examples was not as good as the results of the examples in the above-described performance. Thus, it was found that the radiation-sensitive resin composition of the examples of the present invention is excellent in sensitivity and resolution.

Industrial Applicability

[0214] As described above, according to the radiation-sensitive resin composition and the resist pattern forming method of the present invention, it is possible to exhibit excellent performance in sensitivity, resolution, etc. compared to the prior art. The radiation-sensitive resin composition and the resist pattern forming method of the present invention can be suitably used for forming fine resist patterns in lithography processes of various electronic devices such as semiconductor devices and liquid crystal devices.

Claims

1. (C) A step (1) of forming a resist film that does not contain a radiation-sensitive acid generator, A step (2) of exposing the resist film to EUV or an electron beam (EB), and A method for forming a resist pattern, comprising a step (3) of developing the resist film exposed in the step (2), In the step (1), the resist film is formed of (A) a radiation-sensitive resin composition, The radiation-sensitive resin composition contains a resin having a structural unit (a2) containing a group that dissociates by exposure to EUV or an electron beam (EB) in the absence of (A1) a radiation-sensitive acid generator, The structural unit (a2) is a structural unit having a tertiary alkyl ester moiety, A method for forming a resist pattern.

2. The structural unit (a2) is a structural unit represented by the following formula (2), 【Chemical 1】 (In the above formula (2), R 7 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 8 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. R 9 and R 10 each independently represents a monovalent linear hydrocarbon group having 1 to 20 carbon atoms which may or may not be substituted with a fluorine atom, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms which may or may not be substituted with a fluorine atom, or a monovalent aromatic hydrocarbon group having 5 to 20 carbon atoms, or these groups are combined with each other and together with the carbon atom to which they are attached, represent a divalent alicyclic group having 3 to 20 carbon atoms which may or may not be substituted with a fluorine atom. Also, R 8 to R 10 Any of them, and / or in the case where the above alicyclic group is present, the alicyclic group may have an unsaturated bond. Also, R 8 to R 10 including the case where a plurality of any of them together form one alicyclic structure.), The method for forming a resist pattern according to claim 1.

3. In the step (1), the resist film is formed of (A) a radiation-sensitive resin composition, and in the (A) radiation-sensitive resin composition, the (C) radiation-sensitive acid generator is not contained. The method for forming a resist pattern according to claim 1 or 2.

4. In the step (1), the resist film is formed of (A) a radiation-sensitive resin composition, and the (A) radiation-sensitive resin composition does not contain a radiation-sensitive acid generator. The method for forming a resist pattern according to claim 1 or 2.

5. The resin (A1) whose solubility changes is a resin that changes to water-soluble or alkali-soluble. The method for forming a resist pattern according to any one of claims 2 to 4.

6. In the step (3), developing with an organic solvent to form a negative pattern. The method for forming a resist pattern according to any one of claims 1 to 5.

7. In the step (3), developing with an alkaline developer to form a positive pattern. The method for forming a resist pattern according to any one of claims 1 to 5.

8. A method for processing a substrate, comprising a step (4-1) of forming a pattern on the substrate using the resist pattern formed by the method according to any one of claims 1 to 7 as a mask.

9. A method for manufacturing a metal film pattern, comprising a step (4-2) of forming a metal film using the resist pattern formed by the method according to any one of claims 1 to 7 as a mask.

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