Radiation-sensitive resin composition, pattern forming method, and method for producing monomer compound

Abstract

To provide a radiation-sensitive resin composition that can exhibit sensitivity, CDU performance, and resolution at sufficient levels when applied to next-generation technology, and a method for forming patterns.SOLUTION: A radiation-sensitive resin composition includes a resin containing a structural unit A represented by formula (1), a radiation-sensitive sulfonic acid generator with a specific structure, and a solvent.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a radiation-sensitive resin composition, a pattern forming method, and a method for producing a monomer compound.

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 having a short wavelength such as an ArF excimer laser, and a difference in solubility of the resin in an alkaline or organic solvent-based 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 radiation having a short wavelength 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 radiation having an even shorter wavelength such as an electron beam, X-ray, and EUV (extreme ultraviolet ray) is being considered, and resist materials containing a styrene-based resin with enhanced absorption efficiency of such radiation are also being studied (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-mentioned next-generation technology, resist performance equivalent to or better than that of the conventional technology in terms of sensitivity, critical dimension uniformity (CDU) performance, which is an index of the uniformity of line width and hole diameter, resolution, etc. is required. However, with 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, a pattern forming method, and a method for producing a monomer compound suitable for preparing a resin of the radiation-sensitive resin composition, which can exhibit sensitivity, CDU performance, and resolution at a sufficient level when applying next-generation technology.

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 relates to a resin containing a structural unit A represented by the following formula (1), at least one radiation-sensitive acid generator selected from the group consisting of a radiation-sensitive acid generator represented by the following formula (2-1) and a radiation-sensitive acid generator represented by the following formula (2-2), and a solvent and relates to a radiation-sensitive resin composition containing the same.

Chemical Formula

Chemical formula

[0009] Since the radiation-sensitive resin composition contains a resin containing the structural unit A, it can exhibit sensitivity, CDU performance, and resolution at sufficient levels. Although the reason for this is not clear, it is presumed as follows. In the structural unit A, a phenolic hydroxyl group or a protecting structure that generates a phenolic hydroxyl group by the action of an acid coexists with an acid-dissociable group. The presence of the former improves the energy absorption efficiency during exposure and increases the acid generation efficiency, while the presence of the latter increases the contrast between the exposed portion and the unexposed portion. On the other hand, in a conventional resin containing a structural unit having a protecting structure that generates a phenolic hydroxyl group by the action of a phenolic hydroxyl group or an acid and a structural unit having an acid-dissociable group, if the content ratio of one structural unit is increased, the content ratio of the other structural unit relatively decreases, and the action effects based on each structural unit also increase or decrease accordingly, that is, there is a so-called trade-off relationship. In the resin in the radiation-sensitive resin composition, the sensitivity and CDU performance can be improved by the synergistic effect due to the introduction of the structural unit A having both characteristics. Further, when a carboxy group is generated from the acid-dissociable group by the action of an acid, a phenolic hydroxyl group and a carboxy group coexist in the structural unit A. This increases the solubility of the resin in an alkaline developer, and as a result, the resolution can be improved.

[0010] The "acid-dissociable group" is a group that replaces a hydrogen atom of an alkali-soluble group such as a carboxy group, a phenolic hydroxyl group, a sulfo group, or a sulfonamide group, and is a group that dissociates by the action of an acid. Therefore, the acid-dissociable group is bonded to the oxygen atom that was bonded to the above hydrogen atom in these functional groups. The "organic group" is a group having at least one carbon atom.

[0011] In another embodiment of the present invention, a step of forming a resist film by applying the radiation-sensitive resin composition directly or indirectly on a substrate; a step of exposing the resist film; A step of developing the exposed resist film with a developer relates to a pattern forming method including the same.

[0012] In the pattern forming method, since the radiation-sensitive resin composition excellent in sensitivity, CDU performance, and resolution is used, a high-quality resist pattern can be efficiently formed by lithography applying next-generation exposure technology.

[0013] In still another embodiment, the present invention includes a step of reacting formylhydroxyaromatic carboxylic acid with an alcohol having an acid dissociable group structure to synthesize an ester compound, and further relates to a method for producing a monomer compound including, in any order, a step of protecting a hydroxy group of the ester compound and a step of converting a formyl group of the ester compound to an alkene.

[0014] By the production method, a monomer compound suitable for preparing the resin of the radiation-sensitive resin composition can be efficiently produced.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.

[0016] 《Radiation-Sensitive Resin Composition》 The radiation-sensitive resin composition according to the present embodiment (hereinafter, also simply referred to as "composition") includes a resin, a radiation-sensitive acid generator, and a solvent. The composition may include other optional components as long as the effects of the present invention are not impaired.

[0017] <Resin> The resin is an aggregate of polymers containing structural unit A (hereinafter, this resin is also referred to as "base resin"). In addition to structural unit A, the base resin may contain structural unit B derived from a (meth)acrylic acid ester monomer, structural unit C having a phenolic hydroxyl group, structural unit D having a polar group, structural unit E containing a lactone structure, etc. Hereinafter, each structural unit will be described.

[0018] (Structural unit A) Structural unit A is represented by the following formula (1). [Chemical formula]

[0019] In the above formula (1), R 1 and R 2 are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 3 is an acid dissociable group or a non-acid dissociable group. However, when one R 3 is present, R 3 is an acid dissociable group, and when a plurality of R 3 are present, at least one of the plurality of R 3 is an acid dissociable group. When a plurality of R 3 are present, the plurality of R 3 are the same as or different from each other. R 41 is a hydrogen atom or a protecting group that is deprotected by the action of an acid. When a plurality of R 41 are present, the plurality of R 41 are the same as or different from each other. R 51 is a cyano group, a nitro group, an alkyl group, a fluorinated alkyl group, an alkoxycarbonyloxy group, an acyl group or an acyloxy group. When a plurality of R 51 are present, the plurality of R 51 are the same as or different from each other. n1 is an integer from 0 to 2, m1 is an integer from 1 to 8, m2 is an integer from 1 to 8, and m3 is an integer from 0 to 6. However, 2 ≤ m1 + m2 + m3 ≤ 2n1 + 5 is satisfied.

[0020] The above R 3 The acid dissociable group represented by is not particularly limited. For example, R 3 forms a tertiary alkyl ester moiety together with -COO- to which it is bonded, R 3 forms a secondary unsaturated alkyl ester moiety having a double bond between the β-carbon and γ-carbon of the terminal oxygen atom of -COO- together with -COO- to which it is bonded, R 3 structures that form an acetal bond together with -COO- to which it is bonded, etc. can be mentioned. From the viewpoint of improving the pattern formability of the radiation-sensitive resin composition, the acid dissociable group is preferably represented by the following formula (2).

[0021] [Chemical formula]

[0022] In the above formula (2), R 8 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R 9 and R 10 are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or these groups are combined with each other to form a divalent alicyclic group having 3 to 20 carbon atoms together with the carbon atom to which they are bonded. * is a bond to an oxygen atom.

[0023] The above R 8 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by include a chain 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.

[0024] The above R 8 ~R 10 Examples of the monovalent chain hydrocarbon group having 1 to 10 carbon atoms represented by include a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, or a linear or branched unsaturated hydrocarbon group having 1 to 10 carbon atoms.

[0025] The above R 8 ~R10 Examples of the alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula include monocyclic or polycyclic saturated hydrocarbon groups, or monocyclic or polycyclic unsaturated hydrocarbon groups. Preferred examples of the monocyclic saturated hydrocarbon group include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Preferred examples of the polycyclic cycloalkyl group include bridged alicyclic hydrocarbon groups such as a norbornyl group, an adamantyl group, a tricyclodecyl group, and a tetracyclododecyl group. 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.

[0026] The above R 8 Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by the formula include, for example, aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; aralkyl groups such as a benzyl group, a phenethyl group, and a naphthylmethyl group, and the like.

[0027] 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.

[0028] The above R 9 and R 10 The divalent alicyclic group having 3 to 20 carbon atoms formed by combining the chain hydrocarbon group or alicyclic hydrocarbon group represented by the formula and the carbon atom 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 carbon number. Either a monocyclic hydrocarbon group or a polycyclic hydrocarbon group may be used. As the polycyclic hydrocarbon group, either a bridged alicyclic hydrocarbon group or a condensed alicyclic hydrocarbon group may be used, and either a saturated hydrocarbon group or an unsaturated hydrocarbon group may be used. The condensed alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which a plurality of alicyclic rings are formed in such a way that they share a side (bond between two adjacent carbon atoms).

[0029] Among the monocyclic alicyclic hydrocarbon groups, preferred saturated hydrocarbon groups include a cyclopentanediy group, a cyclohexanediy group, a cycloheptanediy group, a cyclooctanediy group, etc., and preferred unsaturated hydrocarbon groups include a cyclopentenediy group, a cyclohexenediy group, a cycloheptenediy group, a cyclooctenediy group, a cyclodecenediy group, etc. As the polycyclic alicyclic hydrocarbon group, a bridged alicyclic saturated hydrocarbon group is preferred, for example, a bicyclo[2.2.1]heptane-2,2-diy group (norbornane-2,2-diy group), a bicyclo[2.2.2]octane-2,2-diy group, a tricyclo[3.3.1.1 3,7 decane-2,2-diy group (adamantane-2,2-diy group), etc. are preferred.

[0030] 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.

[0031] Preferred acid dissociable groups include, for example, structures represented by the following formulas (3-1) to (3-8).

[0032]

Chemical formula

[0033] In the above formulas (3-1) to (3-8), R 8 to R 10 have the same meanings as in the above formula (2). i and j are each independently an integer of 1 to 4. g, k, and l are each 0 or 1. * is a bond to an oxygen atom.

[0034] As i and j, 1 is preferable. As R 8 , a methyl group, an ethyl group, an isopropyl group, or a phenyl group is preferable. As R 9 and R 10 , a methyl group or an ethyl group is preferable.

[0035] In addition, when the acid dissociable group contains a ring structure, some or all of the hydrogen atoms of the ring structure may be substituted with substituents. Examples of the substituents include halogen atoms such as fluorine atom and chlorine atom; alkyl groups such as methyl group, ethyl group and propyl group; alkoxy groups such as methoxy group and ethoxy group, etc.

[0036] Together with or instead of the above acid dissociable group, it may contain a structure represented by the following formulas (1f) to (3f) as the acid dissociable group.

[0037]

Chemical formula

[0038] In the above formulas (1f) to (3f), R βf is each independently a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms. h1 is an integer of 1 to 4. * is a bond to an oxygen atom.

[0039] As the above R βf a hydrogen atom, a methyl group or an ethyl group is preferable. As h1, 1 or 2 is preferable.

[0040] As the non-acid dissociable group represented by the above R 3 for example primary alkyl groups such as methyl group, ethyl group and propyl group; secondary cycloalkyl groups such as cyclopentyl group and cyclohexyl group; tertiary cycloalkyl groups such as 1-adamantyl group; primary cycloalkyl groups such as cyclopentylmethyl group and cyclohexylmethyl group; alkoxyalkyl groups such as methoxymethyl group, methoxyethyl group, ethoxymethyl group, ethoxyethyl group and propoxymethyl group; fluoroalkyl groups such as trifluoromethyl group, trifluoroethyl group and hexafluoropropyl group; acyl groups such as acetyl group and propionyl group; Examples thereof include aryl groups such as phenyl groups. Among these, secondary cycloalkyl groups and alkoxyalkyl groups are preferred.

[0041] R 3 When there is one R 3 is an acid dissociable group. When there are a plurality of R 3 at least one of the plurality of R 3 may be an acid dissociable group. When there are a plurality of R 3 it is preferable that all of the plurality of R 3 are acid dissociable groups. By having an acid dissociable group as R 3 the resolution of the resist film can be improved. When there are a plurality of R 3 the plurality of R 3 may be the same as or different from each other.

[0042] Examples of the protecting group that is deprotected by the action of the acid represented by the above R 41 include groups represented by the following formulas (AL-1) to (AL-3), etc.

Chemical formula

[0043] In the above formulas (AL-1) and (AL-2), R L1 and R L2 are monovalent hydrocarbon groups, and may contain heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and fluorine atoms. The monovalent hydrocarbon group may be linear, branched, or cyclic, and is preferably an alkyl group having 1 to 40 carbon atoms, more preferably an alkyl group having 1 to 20 carbon atoms. In formula (AL-1), a is an integer of 0 to 10, preferably an integer of 1 to 5. In the above formulas (AL-1) to (AL-3), * is a bond to another part.

[0044] In the above formula (AL-2), R L3 and R L4is, independently of each other, a hydrogen atom or a monovalent hydrocarbon group, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The monovalent hydrocarbon group may be linear, branched, or cyclic, and an alkyl group having 1 to 20 carbon atoms is preferred. Also, R L2 、R L3 and R L4 Any two of them may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom to which they are bonded or the carbon atom and the oxygen atom. As the above ring, a ring having 4 to 16 carbon atoms is preferred, and an alicyclic ring is particularly preferred.

[0045] In the above formula (AL-3), R L5 、R L6 and R L7 are, independently of each other, a monovalent hydrocarbon group, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The monovalent hydrocarbon group may be linear, branched, or cyclic, and an alkyl group having 1 to 20 carbon atoms is preferred. Also, R L5 、R L6 and R L7 Any two of them may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom to which they are bonded. As the above ring, a ring having 4 to 16 carbon atoms is preferred, and an alicyclic ring is particularly preferred.

[0046] Among these, as the protecting group that is deprotected by the action of an acid, the group represented by the above formula (AL-3) is preferred.

[0047] R 51is a cyano group, nitro group, alkyl group, fluorinated alkyl group, alkoxycarbonyloxy group, acyl group or acyloxy group. Examples of the alkyl group include linear or branched alkyl groups having 1 to 8 carbon atoms such as methyl group, ethyl group, propyl group and the like. Examples of the fluorinated alkyl group include linear or branched fluorinated alkyl groups having 1 to 8 carbon atoms such as trifluoromethyl group, pentafluoroethyl group and the like. Examples of the alkoxycarbonyloxy group include chain or alicyclic alkoxycarbonyloxy groups having 2 to 16 carbon atoms such as methoxycarbonyloxy group, butoxycarbonyloxy group and adamantylmethyloxycarbonyloxy group. Examples of the acyl group include aliphatic or aromatic acyl groups having 2 to 12 carbon atoms such as acetyl group, propionyl group, benzoyl group and acryloyl group. Examples of the acyloxy group include aliphatic or aromatic acyloxy groups having 2 to 12 carbon atoms such as acetyloxy group, propionyloxy group, benzoyloxy group and acryloyloxy group.

[0048] n1 is an integer from 0 to 2. n1 is preferably 0 or 1, more preferably 0. m1 is an integer from 1 to 8. m1 is preferably an integer from 1 to 3, more preferably 1 or 2. m2 is an integer from 1 to 8. m2 is preferably an integer from 1 to 3, more preferably 1 or 2. m3 is an integer from 0 to 6. m3 is preferably an integer from 0 to 2, more preferably 0 or 1.

[0049] In the above formula (1), COOR 3 is preferably adjacent to the carbon atom to which OR 41 is bonded. Thereby, a 6-membered ring hydrogen bond is formed between COOH derived from COOR 3 and OH derived from OR 41 to improve the acidity of COOH, so that the solubility in an alkaline developer is improved. As a result, sensitivity, CDU performance and resolution can be exhibited at a higher level.

[0050] The structural unit A is preferably represented by the following formulas (A-1) to (A-39).

Chemical formula

[0051]

Chemical formula

[0052] In the above formulas (A-1) to (A-39), R 2 has the same meaning as in the above formula (1).

[0053] Among these, the structural units represented by the above formulas (A-1) to (A-9), (A-14), (A-17), (A-20), (A-21), (A-24), (A-30), (A-32), (A-34) to (A-37) are preferred.

[0054] The structural unit A can be used alone or in combination of two or more.

[0055] In the above formula (1), when obtaining the structural unit A in which R 41 is a hydrogen atom, it is preferable to polymerize a monomer compound in which R 41 protects the phenolic hydroxyl group with a protecting group such as an alkali-dissociable group, and then perform hydrolysis for deprotection to obtain the structural unit A. Examples of the protecting group that gives a phenolic hydroxyl group by hydrolysis include an acyl group having 2 to 20 carbon atoms or an alkoxycarbonyl group having 2 to 20 carbon atoms. Among them, an acetyl group and a tert-butoxycarbonyl group are preferred.

[0056] (Method for producing a monomer compound that gives the structural unit A) Regarding the method for producing a monomer compound that gives the structural unit A, a monomer compound corresponding to the structural unit represented by the above formula (A-1), and a compound in which the hydroxy group is protected by an acetyl group will be described as a representative. The synthesis scheme is as follows.

[0057] [Chem.]

[0058] In the above scheme, Ar is a structure corresponding to the aromatic ring structure in the above formula (1). R 3 is synonymous with the above formula (1).

[0059] A formylhydroxyaromatic carboxylic acid is reacted with an alcohol having an acid dissociable group structure to synthesize an ester compound into which an acid dissociable group is introduced. Next, the ester compound is reacted with acetyl chloride to protect the hydroxy group, and further, in the presence of a metal complex formed from zinc and an alkyl halide, the formyl group is converted to an alkene by a Wittig-type olefination reaction to synthesize the target monomer compound (A-i). In the above scheme, although the olefination of the formyl group is carried out following the protection of the hydroxy group after obtaining the ester compound, it is not limited thereto, and the protection of the hydroxy group may be carried out following the olefination of the formyl group. Regarding the structures of other monomer compounds, they can be synthesized by appropriately changing the structure of the aromatic ring in the starting material compound, the types and numbers of substituents (carboxy group, hydroxy group, other substituents, etc.) on the aromatic ring, the structure of the alcohol having an acid dissociable group structure, and the like.

[0060] In the resin, the lower limit of the content ratio of structural unit A (total when there are multiple types of structural unit A) is preferably 5 mol%, more preferably 7 mol%, and even more preferably 10 mol% with respect to all the structural units constituting the resin. The upper limit of the above content ratio is preferably 100 mol%, more preferably 90 mol%, and even more preferably 80 mol%. By setting the content ratio of structural unit A within the above range, the above radiation-sensitive resin composition can further improve sensitivity, CDU performance, and resolution.

[0061] (Structural unit B) The structural unit B is a structural unit derived from a (meth)acrylate monomer. By including the structural unit B in the base resin, the sensitivity, CDU performance, and resolution of the resist film of the radiation-sensitive resin composition can be further improved, and good pattern formability can be obtained.

[0062] The structural unit B is preferably represented by the following formula (4).

Chemical formula

[0063] In the above formula (4), R 7 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 31 is an acid-dissociable group or a non-acid-dissociable group.

[0064] The structural unit B may be a structural unit B1 having an acid-dissociable group or a structural unit B2 having a non-acid-dissociable group according to the structure of R 31 in the above formula (4). When R 31 is an acid-dissociable group, R 31 is preferably an acid-dissociable group represented by the above formula (2). When R 31 is a non-acid-dissociable group, examples of R 31 include the non-acid-dissociable groups represented by R 3 in the above formula (1).

[0065] Examples of the structural unit B1 having an acid-dissociable group include structural units represented by the following formulas (4-1) to (4-6) (hereinafter, also referred to as "structural units (B1-1) to (B1-6)").

[0066]

Chemical formula

[0067] In the above formulas (4-1) to (4-6), R 7 has the same meaning as in the above formula (4), and R 8 ~R10 is synonymous with the above formula (2). i and j are each independently an integer from 1 to 4. k and l are 0 or 1.

[0068] As for i and j, 1 is preferable. R 8 is preferably a methyl group, an ethyl group or an isopropyl group. R 9 and R 10 are preferably a methyl group or an ethyl group.

[0069] Furthermore, the resin may contain, as the structural unit B1, together with or in place of the above structural units (B1-1) to (B1-6), structural units represented by the following formulas (4-7) to (4-9) (hereinafter also referred to as "structural units (B1-7) to (B1-9)").

[0070]

Chemical formula

[0071] In the above formulas (4-7) to (4-9), R 7 is synonymous with the above formula (4). R βf are each independently a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms. A plurality of R βf may be the same as or different from each other. h1 is an integer from 1 to 4.

[0072] As the above R βf a hydrogen atom, a methyl group or an ethyl group is preferable. As h1, 1 or 2 is preferable.

[0073] Examples of the structural unit B2 having a non-acid dissociable group include structural units represented by the following formulas (4-10) to (4-11) (hereinafter also referred to as "structural units (B2-1) to (B2-2)").

[0074]

Chemical formula

[0075] The above R 7 is preferably a hydrogen atom or a methyl group. n b1 is preferably an integer from 2 to 4, more preferably 2 or 3. n b2 is preferably an integer from 0 to 3, more preferably an integer from 0 to 2. n b3 is preferably an integer from 1 to 4, more preferably an integer from 2 to 4.

[0076] The base resin may contain one or a combination of two or more structural units B.

[0077] When the resin contains the structural unit B, the lower limit of the content ratio of the structural unit B (the total when there are multiple types of structural unit B) 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 base resin. The upper limit of the above content ratio is preferably 80 mol%, more preferably 70 mol%, and still more preferably 65 mol%. By setting the content ratio of the structural unit B within the above range, the pattern formability of the radiation-sensitive resin composition can be further improved.

[0078] (Structural unit C) The above resin preferably further contains a structural unit C represented by the following formula (5). [Chemical formula] (In the above formula (5), R α is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. L CA is a single bond, -COO- * or -O- * is. * is a bond on the aromatic ring side. R 42 and R 52 are the R in the above formula (1) 41 and R51 are synonymous with each other. n3 is an integer from 0 to 2, m3 is an integer from 1 to 8, and m4 is an integer from 0 to 8. However, 1 ≦ m3 + m4 ≦ 2n3 + 5 is satisfied.)

[0079] The structural unit C is a structural unit containing a phenolic hydroxyl group different from the structural unit A or a structural unit that gives a phenolic hydroxyl group by the action of an acid. By having the structural unit C and other structural units as necessary, the resin can more appropriately adjust its solubility in the developer, and as a result, the sensitivity and the like of the above-mentioned radiation-sensitive resin composition can be further improved. Further, when using KrF excimer laser light, EUV, electron beam, etc. as the radiation irradiated in the exposure step in the resist pattern forming method, the structural unit C contributes to the improvement of etching resistance and the improvement of the difference in developer solubility (dissolution contrast) between the exposed portion and the unexposed portion. 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.

[0080] The above R α is preferably a hydrogen atom or a methyl group from the viewpoint of the copolymerizability of the monomer that gives the structural unit C.

[0081] L CA is preferably a single bond or -COO- * is preferred.

[0082] The above R 42 As the protecting group that is deprotected by the action of the acid represented by, the protecting group that is deprotected by the action of the acid listed as R 42 in the above formula (1) can be preferably adopted.

[0083] Similarly, the substituent represented by the above R 52 can preferably adopt the substituents listed as R 51 in the above formula (1).

[0084] As the above n3, 0 or 1 is more preferable, and 0 is even more preferable.

[0085] As for the above m3, an integer of 1 to 3 is preferable, and 1 or 2 is more preferable.

[0086] As for the above m4, an integer of 0 to 3 is preferable, and an integer of 0 to 2 is more preferable.

[0087] As for the above structural unit C, it is preferably a structural unit represented by the following formulas (c1-1) to (c1-10) (hereinafter, also referred to as "structural units (C-1) to structural units (C-10)").

[0088]

Chemical formula

[0089] In the above formulas (c1-1) to (c1-10), R α is the same as the above formula (5).

[0090] Among these, the above structural units (C-1) to (C-4), (C-6) and (C-8) are preferable.

[0091] When the base resin contains the structural unit C, the lower limit of the content ratio of the structural unit C (the total when there are multiple types of structural unit C) is preferably 5 mol% with respect to all the structural units constituting the resin, more preferably 8 mol%, still more preferably 10 mol%, and particularly preferably 15 mol%. The upper limit of the above content ratio is preferably 70 mol%, more preferably 60 mol%, still more preferably 55 mol%, and particularly preferably 50 mol%. By setting the content ratio of the structural unit C within the above range, the above radiation-sensitive resin composition can further improve sensitivity, CDU performance and resolution.

[0092] When polymerizing a monomer having a phenolic hydroxyl group such as hydroxystyrene, it is preferable 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 to deprotect to obtain the structural unit C.

[0093] (Structural unit D) The base resin may appropriately contain a structural unit D having a polar group or an ionic functional group in addition to the above structural units A to C. Examples of the polar group include a fluorine atom, an alcoholic hydroxyl group, a carboxy group, a cyano group, a nitro group, a sulfonamide group, etc. Among the structural units D, 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. The ionic functional group includes an anionic group and a cationic group. As the anionic group, a group having a sulfonate anion is preferable, and as the cationic group, a group having a sulfonium cation is preferable.

[0094] Examples of the structural unit D include structural units represented by the following formulas.

[0095] [Chemical formula]

[0096] [Chemical formula]

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

[0098] When the resin has the structural unit D, the lower limit of the content ratio of the structural unit D to all the structural units constituting the resin (the total when there are a plurality of types of structural units D) is preferably 3 mol%, more preferably 5 mol%, and even more preferably 8 mol%. On the other hand, the upper limit of the above content ratio is preferably 40 mol%, more preferably 35 mol%, and even more preferably 30 mol%. By setting the content ratio of the structural unit D within the above range, the solubility of the resin in the developer can be made more appropriate.

[0099] (Structural unit E) The structural unit (II) is a structural unit containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. By further having the structural unit E, the base resin can adjust the solubility in the developer, and as a result, the radiation-sensitive resin composition can improve lithography performance such as resolution. In addition, the adhesion between the resist pattern formed from the base resin and the substrate can be improved.

[0100] Examples of the structural unit E include structural units represented by the following formulas (T-1) to (T-10).

[0101]

Chemical formula

[0102] In the above formulas, R L1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R L2 ~R L5 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxy group, a hydroxymethyl group, or a dimethylamino group. R L4 and R L5 may be a divalent alicyclic group having 3 to 8 carbon atoms formed together with the carbon atoms to which they are attached. L 2 is a single bond or a divalent linking group. X is an oxygen atom or a methylene group. k is an integer of 0 to 3. m is an integer of 1 to 3.

[0103] Examples of the divalent alicyclic group having 3 to 8 carbon atoms formed by combining R L4 and R L5 together with the carbon atoms to which they are attached include R 9 and R 10Examples of the divalent alicyclic group having 3 to 20 carbon atoms, which is composed of chained hydrocarbon groups or alicyclic hydrocarbon groups represented by and the carbon atoms to which they are bonded, include groups having 3 to 8 carbon atoms. One or more hydrogen atoms on this alicyclic group may be substituted with hydroxy groups.

[0104] The above L 2 Examples of the divalent linking group represented by include divalent linear or branched hydrocarbon groups having 1 to 10 carbon atoms, divalent alicyclic hydrocarbon groups having 4 to 12 carbon atoms, or groups composed of one or more of these hydrocarbon groups and at least one group selected from -CO-, -O-, -NH- and -S-.

[0105] Among these, as the structural unit E, a structural unit containing a lactone structure is preferable, a structural unit containing a norbornane lactone structure is more preferable, and a structural unit derived from norbornane lactone-yl (meth) acrylate is even more preferable.

[0106] The lower limit of the content ratio of the structural unit E is preferably 5 mol%, more preferably 15 mol%, and even more preferably 30 mol% with respect to all the structural units constituting the base resin. The upper limit of the above content ratio is preferably 80 mol%, more preferably 75 mol%, and even more preferably 70 mol%. By setting the content ratio of the structural unit (II) within the above range, the radiation-sensitive resin composition can further improve lithography performance such as resolution and the adhesion of the formed resist pattern to the substrate.

[0107] Regarding the above structural units B to E, those corresponding to the above structural unit A are excluded from these structural units.

[0108] The resin content is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more in the total solid content of the radiation-sensitive resin composition. Here, the "solid content" refers to all the components contained in the radiation-sensitive resin composition excluding the solvent.

[0109] (Method for synthesizing resin) The resin serving as the base resin can be synthesized, for example, by performing a polymerization reaction on monomers providing respective structural units in a suitable solvent using a radical polymerization initiator or the like.

[0110] Examples of the radical polymerization initiator 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), and dimethyl 2,2'-azobisisobutyrate; peroxide-based radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred, and AIBN is more preferred. These radical initiators can be used alone or in combination of two or more.

[0111] Examples of the solvent used in the 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; and 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.

[0112] As the reaction temperature in the above polymerization reaction, it is usually 40°C to 150°C, preferably 50°C to 120°C. As the reaction time, it is usually 1 hour to 48 hours, preferably 1 hour to 24 hours.

[0113] The molecular weight of the resin 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 resin (A) is less than the above lower limit, the heat resistance of the resulting resist film may decrease. If the Mw of resin (A) exceeds the above upper limit, the developability of the resist film may decrease.

[0114] The ratio (Mw / Mn) of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the resin as the base resin by GPC is usually 1 or more and 5 or less, preferably 1 or more and 3 or less, and more preferably 1 or more and 2 or less.

[0115] The Mw and Mn of the resin in this specification are values measured using gel permeation chromatography (GPC) under the following conditions. GPC column: Two G2000HXL, one G3000HXL, one 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

[0116] The content of the resin is preferably 70 mass% or more, more preferably 80 mass% or more, and still more preferably 85 mass% or more based on the total solid content of the above radiation-sensitive resin composition.

[0117] <Other resin> 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 in the surface layer of the resist film with respect to the 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.

[0118] As the high-fluorine content resin, for example, it preferably has structural units A to C in the base resin as required and has a structural unit represented by the following formula (6) (hereinafter, also referred to as "structural unit G").

Chemical formula

[0119] In the above formula (6), 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 linear hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0120] As the above R 13 from the viewpoint of the copolymerizability of the monomer that gives structural unit G, a hydrogen atom and a methyl group are preferred, and a methyl group is more preferred.

[0121] As the above G L from the viewpoint of the copolymerizability of the monomer that gives structural unit G, a single bond and -COO- are preferred, and -COO- is more preferred.

[0122] Examples of the monovalent fluorinated linear hydrocarbon group having 1 to 20 carbon atoms represented by the above R 14 include those in which some or all of the hydrogen atoms of a linear or branched alkyl group having 1 to 20 carbon atoms are substituted by fluorine atoms.

[0123] The above R 14 Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by 14 include those in which some or all of the hydrogen atoms of a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms are substituted by fluorine atoms.

[0124] The above R 14 is preferably a fluorinated chain hydrocarbon group, more preferably a fluorinated alkyl group, and even more preferably 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.

[0125] When the high-fluorine content resin has the structural unit G, the lower limit of the content ratio of the structural unit G 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 G 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.

[0126] In addition to the structural unit G, 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 H). By having the structural unit H, the high-fluorine content resin can improve the solubility in an alkaline developer and suppress the occurrence of development defects. [Chemical formula]

[0127] The structural unit H 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 to increase the solubility in an alkaline developer (hereinafter, also simply referred to as an "alkali-dissociable group"). In common to both (x) and (y), in the above formula (f-1), RC 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, or an oxygen atom, a sulfur atom, -NR E -, a carbonyl group, -COO- or -CONH- 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 with an organic group having a hetero atom. 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.

[0128] When the structural unit H 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. A 1 When A 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 E is 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 an (x) alkali-soluble group in the structural unit H, the affinity for an alkali developer can be increased and development defects can be suppressed. As the structural unit H having an (x) alkali-soluble group, A 1 is an oxygen atom and W 1 is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group is particularly preferable.

[0129] When the structural unit H has a (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 aais --COO--*, --SO2O--*, or --O--. 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. A 1 When A is --COO--* or --SO2O--*, W 1 or R F is A 1 has a fluorine atom on the carbon atom bonded to A or the carbon atom adjacent thereto. A 1 When A is an oxygen atom, W 1 , R E is a single bond, R D is a structure in which a carbonyl group is bonded to the end on the R side of a hydrocarbon group having 1 to 20 carbon atoms, and R E is an organic group having a fluorine atom. When s is 2 or 3, a plurality of R F , W E , A 1 , and R 1 and R F may be the same or different from each other. Since the structural unit H has a (y) alkali-dissociable group, the surface of the resist film changes from hydrophobic to hydrophilic in the alkali development step. As a result, the affinity for the developer is significantly increased, and development defects can be suppressed more efficiently. As the structural unit H having a (y) alkali-dissociable group, A 1 is --COO--*, R F or W 1 or both of them having a fluorine atom are particularly preferred.

[0130] R C is preferably a hydrogen atom or a methyl group, and more preferably a methyl group, from the viewpoint of copolymerizability of the monomer giving the structural unit H and the like.

[0131] 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.

[0132] When the high-fluorine content resin has the structural unit H, the lower limit of the content ratio of the structural unit H 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 H within the above range, the water repellency of the resist film during liquid immersion exposure can be further improved.

[0133] 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.

[0134] The lower limit of the 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 still more preferably 1.7.

[0135] The lower limit of the content of the high-fluorine content resin is preferably 0.1% by mass, more preferably 0.5% by mass, still more preferably 1% by mass, and still more preferably 1.5% by mass with respect to the total solid content in the radiation-sensitive resin composition. The upper limit of the above content is preferably 20% by mass, more preferably 15% by mass, still more preferably 10% by mass, and particularly preferably 7% by mass.

[0136] The lower limit of the content of the high-fluorine content resin is preferably 0.1 part by mass, more preferably 0.5 part by mass, still more preferably 1 part by mass, and particularly preferably 1.5 parts by mass with respect to 100 parts by mass of the base resin. The upper limit of the above content is preferably 15 parts by mass, more preferably 10 parts by mass, still more preferably 8 parts by mass, and particularly preferably 5 parts by mass.

[0137] 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 elution of the upper part of the pattern during development is suppressed, and the rectangularity of the pattern can be enhanced. The above radiation-sensitive resin composition may contain one or more high-fluorine content resins.

[0138] (Synthesis method of high-fluorine content resin) The high-fluorine content resin can be synthesized by a method similar to the synthesis method of the above base resin.

[0139] (Radiation-sensitive acid generator) The above radiation-sensitive resin composition contains at least one selected from the group consisting of a radiation-sensitive acid generator having a ring structure at the terminal (hereinafter, also referred to as "radiation-sensitive acid generator 1") and a radiation-sensitive acid generator having a monovalent onium cation in which the atom having a positive charge is not an atom forming a ring structure (hereinafter, also referred to as "radiation-sensitive acid generator 2"). As the form of the radiation-sensitive acid generator contained in the radiation-sensitive resin composition, it may be present alone as a low-molecular compound, incorporated as a part of the polymer, or both of these forms, but the form of being present alone as a low-molecular compound is preferred.

[0140] (Radiation-sensitive acid generator 1) The radiation-sensitive acid generator 1 is represented by the following formula (2-1).

Chemical formula

[0141] In the above formula (2-1), n2 is an integer from 1 to 5. R f1 and R f2 are each independently a hydrogen atom, a fluorine atom, or a fluoroalkyl group. However, when n2 is 1, at least one of R f1 and R f2 is a fluorine atom or a fluoroalkyl group. When n2 is 2 to 5, a plurality of Rf1 and R f2 At least one of them is a fluorine atom or a fluoroalkyl group, and when there are a plurality of Rs f1 and R f2 may be the same as or different from each other. L 1 is a divalent linking group. R 5a is a monovalent organic group having a ring structure. X1 + is a monovalent onium cation.

[0142] In the above formula (2-1), n2 is preferably an integer of 1 to 4, more preferably an integer of 1 to 3, and even more preferably 1 or 2.

[0143] In the above formula (2-1), R f1 and R f2 Examples of the fluoroalkyl group represented by include fluoroalkyl groups having 1 to 20 carbon atoms. R f1 and R f2 are preferably a fluorine atom and a fluoroalkyl group, more preferably a fluorine atom and a perfluoroalkyl group, even more preferably a fluorine atom and a trifluoromethyl group, and particularly preferably a fluorine atom.

[0144] In the above formula (2-1), L 1 Examples of the divalent linking group represented by include, for example, a divalent linear or branched hydrocarbon group having 1 to 10 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, -CO-, -O-, -NH-, -S-, and a group selected from a cyclic acetal structure, or a group formed by combining two or more of these groups.

[0145] Examples of the divalent linear or branched hydrocarbon group having 1 to 10 carbon atoms include, for example, a methanediyl group, an ethanediyl group, a propanediyl group, a butanediyl group, a hexanediyl group, an octanediyl group, etc. Among them, an alkanediyl group having 1 to 8 carbon atoms is preferable.

[0146] Examples of the divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms include monocyclic cycloalkane diyl groups such as cyclopentane diyl group and cyclohexane diyl group; polycyclic cycloalkane diyl groups such as norbornane diyl group and adamantane diyl group. Among them, cycloalkane diyl groups having 5 to 12 carbon atoms are preferred.

[0147] R 5a Examples of the monovalent organic group having a ring structure represented by include monovalent groups containing an alicyclic structure having 5 or more ring members, monovalent groups containing an aliphatic heterocyclic structure having 5 or more ring members, monovalent groups containing an aromatic ring structure having 6 or more ring members, monovalent groups containing an aromatic heterocyclic structure having 5 or more ring members, and the like. R 5a In the monovalent organic group represented by, a form in which it is bonded to a polymer and the radiation-sensitive acid generator 1 represented by the above formula (2-1) is incorporated as a part of the polymer is also included in the radiation-sensitive acid generator of the present embodiment.

[0148] Examples of the alicyclic structure having 5 or more ring members include, for example, monocyclic cycloalkane structures such as cyclopentane structure, cyclohexane structure, cycloheptane structure, cyclooctane structure, cyclononane structure, cyclodecane structure, cyclododecane structure; monocyclic cycloalkene structures such as cyclopentene structure, cyclohexene structure, cycloheptene structure, cyclooctene structure, cyclodecene structure; polycyclic cycloalkane structures such as norbornane structure, adamantane structure, tricyclodecane structure, tetracyclododecane structure; polycyclic cycloalkene structures such as norbornene structure, tricyclodecene structure, and the like can be mentioned.

[0149] Examples of the aliphatic heterocyclic structure having 5 or more ring members include, for example, lactone structures such as pentanolactone structure, hexanolactone structure, norbornanelactone structure; sultone structures such as pentanosultone structure, hexanosultone structure, norbornanesultone structure; Heterocyclic ring structures containing oxygen atoms such as oxacyclopentane structure, oxacycloheptane structure, oxanorbornane structure; Heterocyclic ring structures containing nitrogen atoms such as azacyclopentane structure, azacyclohexane structure, diazabicyclooctane structure; Examples thereof include heterocyclic ring structures containing sulfur atoms such as thiacyclopentane structure, thiacyclohexane structure, thianorbornane structure.

[0150] Examples of the aromatic ring structure having 6 or more ring members include benzene structure, naphthalene structure, phenanthrene structure, anthracene structure, etc.

[0151] Examples of the aromatic heterocyclic ring structure having 5 or more ring members include oxygen atom-containing heterocyclic ring structures such as furan structure, pyran structure, benzopyran structure, and nitrogen atom-containing heterocyclic ring structures such as pyridine structure, pyrimidine structure, indole structure, etc.

[0152] R 5a The lower limit of the number of ring members of the ring structure of R may be 5, preferably 6, more preferably 7, and even more preferably 8. On the other hand, as the upper limit of the number of ring members, 15 is preferable, 14 is more preferable, 13 is even more preferable, and 12 is particularly preferable. By setting the number of ring members within the above range, the diffusion length of the above acid can be further appropriately shortened, and as a result, various performances of the above chemically amplified resist material can be further improved.

[0153] R 5a Some or all of the hydrogen atoms of the ring structure of R may be substituted with substituents. Examples of the substituents include halogen atoms such as fluorine atom, chlorine atom, bromine atom, iodine atom, hydroxy group, carboxy group, cyano group, nitro group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, acyloxy group, etc. Among these, a hydroxy group is preferable.

[0154] R 5aAmong these, a monovalent group containing an alicyclic structure having 5 or more ring members and a monovalent group containing an aliphatic heterocyclic structure having 5 or more ring members are preferable, a monovalent group containing an alicyclic structure having 6 or more ring members and a monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members are more preferable, a monovalent group containing an alicyclic structure having 9 or more ring members and a monovalent group containing an aliphatic heterocyclic structure having 9 or more ring members are still more preferable, an adamantyl group, a hydroxyadamantyl group, a norbornanelactone-yl group, a norbornanesultone-yl group and a 5-oxo-4-oxatricyclo[4.3.1.13,8]undecane-yl group are still more preferable, and an adamantyl group is particularly preferable.

[0155] The above X1 + Examples of the monovalent onium cation represented by the above include radiation-decomposable onium cations containing elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi. Examples include sulfonium cations, tetrahydrothiophenium cations, iodonium cations, phosphonium cations, diazonium cations, pyridinium cations, and the like. Among them, a sulfonium cation or an iodonium cation is preferable. The sulfonium cation or iodonium cation is preferably represented by the following formulas (X-1) to (X-6).

[0156] [Chemical formula]

[0157] [Chemical formula]

[0158] [Chemical formula]

[0159] [Chemical formula]

[0160] [Chemistry]

[0161] [Chemistry]

[0162] In the above formula (X-1), R a1 , R a2 and R a3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyloxy group, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, -OSO2-R P , -SO2-R Q or -S-R T , or two or more of these groups are combined with each other to form a ring structure. The ring structure may contain a heteroatom such as O or S between the carbon-carbon bonds forming the skeleton. R P , R Q and R T are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2 and k3 are each independently an integer from 0 to 5. R a1 ~R a3 as well as R P , R Q and R T are each in plural, when there are plural R a1 ~R a3 as well as R P , R Q and R T may be the same or different from each other.

[0163] In the above formula (X-2), R b1is a substituted or unsubstituted linear or branched alkyl group or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. n k is 0 or 1. n k When n is 0, k4 is an integer from 0 to 4, and n k when n is 1, k4 is an integer from 0 to 7. R b1 In the case of a plurality of R b1 may be the same or different, and a plurality of R b1 may represent a ring structure formed by combining with each other. R b2 is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. L C is a single bond or a divalent linking group. k5 is an integer from 0 to 4. R b2 In the case of a plurality of R b2 may be the same or different, and a plurality of R b2 may represent a ring structure formed by combining with each other. q is an integer from 0 to 3. In the formula, S + The ring structure containing may contain heteroatoms such as O and S between the carbon-carbon bonds forming the skeleton.

[0164] In the above formula (X-3), R c1 , R c2 and R c3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms.

[0165] In the above formula (X-4), R g1 is a substituted or unsubstituted linear or branched alkyl group or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. n k is 0 or 1. n k2 When n is 0, k10 is an integer from 0 to 4, and n k2When it is 1, k10 is an integer from 0 to 7. R g1 When there are a plurality of R's g1 they may be the same or different, and a plurality of R's g1 may represent a ring structure formed by combining with each other. R g2 and R g3 each independently represents a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyloxy group, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, or a ring structure formed by combining these groups with each other. k11 and k12 are each independently an integer from 0 to 4. R g2 and R g3 When each is a plurality, a plurality of R's g2 and R g3 may be the same or different from each other.

[0166] In the above formula (X-5), R d1 and R d2 each independently represents a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyl group, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a halogen atom, a halogenated alkyl group having 1 to 4 carbon atoms, a nitro group, or a ring structure formed by combining two or more of these groups with each other. k6 and k7 are each independently an integer from 0 to 5. R d1 and R d2 When each is a plurality, a plurality of R's d1 and R d2 may be the same or different from each other.

[0167] In the above formula (X-6), R e1 and R e2is, independently, a halogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k8 and k9 are each independently an integer of 0 to 4.

[0168] Examples of the radiation-sensitive acid generator 1 represented by the above formula (2-1) include radiation-sensitive acid generators represented by the following formulas (2-1-1) to (2-1-41) (hereinafter, also referred to as "radiation-sensitive acid generators (1-1) to radiation-sensitive acid generators (1-41)").

[0169] [Chemical formula]

[0170] [Chemical formula]

[0171] [Chemical formula]

[0172] [Chemical formula]

[0173] In the above formulas (2-1-1) to (2-1-41), X1 + is a monovalent onium cation.

[0174] Among these, the radiation-sensitive acid generators represented by the above formulas (2-1-1), (2-1-11), (2-1-16), and (2-1-36) to (2-1-41) are preferred.

[0175] (Radiation-sensitive acid generator 2) The radiation-sensitive acid generator 2 is represented by the following formula (2-2). [Chemical formula]

[0176] In the above formula (2-2), R 5b is a monovalent organic group. X2 + is a monovalent onium cation in which the atom having a positive charge is not an atom forming a ring structure.

[0177] The monovalent organic group represented by the above R 5b is not particularly limited and may be any of a chain structure, a cyclic structure, or a combination thereof. Examples of the above chain structure include chain hydrocarbon groups that may be saturated or unsaturated, linear or branched. Examples of the above cyclic structure include cyclic hydrocarbon groups that may be alicyclic, aromatic, or heterocyclic. Further, groups in which some or all of the hydrogen atoms of a group having a chain structure or a group having a cyclic structure are substituted with a substituent, groups containing CO, CS, O, S, SO2, or NR', or a combination of two or more of these between carbon-carbon bonds of these groups, etc. may also be mentioned. R' is a hydrocarbon group having 1 to 10 carbon atoms. Among them, as the monovalent organic group, a substituted or unsubstituted monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms is preferable. R 5b In the monovalent organic group represented by, a form in which it is bonded to a polymer and the radiation-sensitive acid generator 2 represented by the above formula (2-2) is incorporated as a part of the polymer is also included in the radiation-sensitive acid generator of the present embodiment.

[0178] Examples of the substituent that substitutes some or all of the hydrogen atoms of the above organic group include halogen atoms such as fluorine atom, chlorine atom, bromine atom, and iodine atom; hydroxy group; carboxy group; cyano group; nitro group; alkyl group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, acyloxy group, or a group in which the hydrogen atom of these groups is substituted with a halogen atom; oxo group (=O), etc.

[0179] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include linear or branched saturated hydrocarbon groups having 1 to 20 carbon atoms, or linear or branched unsaturated hydrocarbon groups having 1 to 20 carbon atoms. Although the number of carbon atoms may be 1 or more, the lower limit is preferably 2, more preferably 3, still more preferably 4. As the upper limit of the number of carbon atoms, 18 is preferable, 16 is more preferable, 14 is still more preferable, and 12 is particularly preferable.

[0180] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monocyclic or polycyclic saturated hydrocarbon groups, or monocyclic or polycyclic unsaturated hydrocarbon groups. As the monocyclic saturated hydrocarbon group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group are preferable. As the polycyclic cycloalkyl group, bridged alicyclic hydrocarbon groups such as a norbornyl group, an adamantyl group, a tricyclodecyl group, and a tetracyclododecyl group are preferable. The bridged alicyclic hydrocarbon group means 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.

[0181] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; aralkyl groups such as a benzyl group, a phenethyl group, and a naphthylmethyl group.

[0182] Examples of the heterocyclic cyclic hydrocarbon group include a group obtained by removing one hydrogen atom from an aromatic heterocyclic structure and a group obtained by removing one hydrogen atom from an alicyclic heterocyclic structure. A 5-membered aromatic structure having aromaticity by introducing a heteroatom is also included in the heterocyclic structure. Examples of the heteroatom include an oxygen atom, a nitrogen atom, and a sulfur atom.

[0183] Examples of the aromatic heterocyclic structure include oxygen atom-containing aromatic heterocyclic structures such as furan, pyran, benzofuran, and benzopyran; Aromatic heterocyclic structures containing nitrogen atoms such as pyrrole, imidazole, pyridine, pyrimidine, pyrazine, indole, quinoline, isoquinoline, acridine, phenazine, carbazole, etc.; Aromatic heterocyclic structures containing sulfur atoms such as thiophene; Aromatic heterocyclic structures containing a plurality of heteroatoms such as thiazole, benzothiazole, thiazine, oxazine, etc. can be mentioned.

[0184] Examples of the above alicyclic heterocyclic structures include Alicyclic heterocyclic structures containing oxygen atoms such as oxirane, tetrahydrofuran, tetrahydropyran, dioxolane, dioxane, etc.; Alicyclic heterocyclic structures containing nitrogen atoms such as aziridine, pyrrolidine, piperidine, piperazine, etc.; Alicyclic heterocyclic structures containing sulfur atoms such as thietane, thiolane, thiane, etc.; Alicyclic heterocyclic structures containing a plurality of heteroatoms such as morpholine, 1,2-oxathiolane, 1,3-oxathiolane, etc.; Lactone structures, cyclic carbonate structures, sultone structures, etc. can be mentioned.

[0185] The above X2 + As the monovalent onium cation in which the atom having a positive charge represented by is not an atom forming a ring structure, the monovalent onium cations represented by the above formulas (X-1), (X-3) and (X-5) are preferably mentioned.

[0186] Examples of the radiation-sensitive acid generator 2 represented by the above formula (2-2) include radiation-sensitive acid generators represented by the following formulas (2-2-1) to (2-2-12) (hereinafter, also referred to as "radiation-sensitive acid generators (2-1) to radiation-sensitive acid generators (2-12)"). etc. can be mentioned.

[0187]

Chemical formula

[0188] When using KrF excimer laser light, EUV, electron beams, etc. as the radiation irradiated in the exposure process in the resist pattern formation method, the sulfonic acid anion of the radiation-sensitive acid generator 1 represented by the above formula (2-1) and the sulfonic acid anion of the radiation-sensitive acid generator 2 represented by the above formula (2-2) preferably have one or more iodine atoms.

[0189] The above X1 + monovalent onium cation represented by and the above X2 + monovalent onium cation represented by preferably have three or more fluorine atoms, and more preferably have five or more fluorine atoms. Examples of such onium cations include, for example, in the above formula (X-1), k1 = k2 = k3 = 1 and R a1 = R a2 = R a3 = a fluorine atom, a cation in the formula (X-1) where k1 = k2 = k3 = 1 and R a1 = R a2 = a fluorine atom and R a3 = a trifluoromethyl group, a cation where k1 = k2 = 1 and k3 = 0 and R a1 = R a2 = a trifluoromethyl group, etc.

[0190] The radiation-sensitive acid generator may be used alone or in combination of two or more. The lower limit of the content of the radiation-sensitive acid generator (the total when there are multiple types of radiation-sensitive acid generators) is preferably 0.1 part by mass, more preferably 1 part by mass, and even more preferably 3 parts by mass with respect to 100 parts by mass of the resin. The upper limit of the above content is preferably 50 parts by mass, more preferably 45 parts by mass, and even more preferably 40 parts by mass. Thereby, excellent sensitivity, CDU performance, and resolution can be exhibited during resist pattern formation.

[0191] <Acid diffusion control agent> 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 in the resist film by exposure, and has the effect of suppressing an undesirable chemical reaction in the unexposed area. 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 change in the line width 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.

[0192] Examples of the acid diffusion controller include a compound represented by the following formula (7) (hereinafter also referred to as "nitrogen-containing compound (I)"), a compound having two nitrogen atoms in the same molecule (hereinafter also referred to as "nitrogen-containing compound (II)"), a compound having three nitrogen atoms (hereinafter also referred to as "nitrogen-containing compound (III)"), an amide group-containing compound, a urea compound, a nitrogen-containing heterocyclic compound, and the like.

[0193]

Chemical formula

[0194] In the above formula (7), R 22 , R 23 and R 24 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.

[0195] Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; aromatic amines such as aniline, and the like.

[0196] Examples of the nitrogen-containing compound (II) include ethylenediamine, N,N,N',N'-tetramethylethylenediamine, and the like.

[0197] Examples of the nitrogen-containing compound (III) include polyamine compounds such as polyethyleneimine and polyallylamine; polymers such as dimethylaminoethyl acrylamide and the like.

[0198] Examples of the amide group-containing compound include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone and the like.

[0199] Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tributylthiourea and the like.

[0200] Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N-(undecylcarbonyloxyethyl)morpholine; pyrazines, pyrazoles and the like.

[0201] In addition, as the above nitrogen-containing organic compound, a compound having an acid dissociable group can also be used. Examples of such a nitrogen-containing organic compound having an acid dissociable group include N-t-butoxycarbonylpiperidine, N-t-butoxycarbonylimidazole, N-t-butoxycarbonylbenzimidazole, N-t-butoxycarbonyl-2-phenylbenzimidazole, N-(t-butoxycarbonyl)di-n-octylamine, N-(t-butoxycarbonyl)diethanolamine, N-(t-butoxycarbonyl)dicyclohexylamine, N-(t-butoxycarbonyl)diphenylamine, N-t-butoxycarbonyl-4-hydroxypiperidine, N-t-amyloxycarbonyl-4-hydroxypiperidine and the like.

[0202] In addition, as the acid diffusion controller, an onium salt compound that generates an acid having a higher pKa than the acid generated from the radiation-sensitive acid generator upon irradiation with radiation (hereinafter, also referred to as "radiation-sensitive weak acid generator" for convenience) can also be preferably used. The acid generated from the radiation-sensitive weak acid generator is a weak acid that does not induce dissociation of the acid dissociable group in the resin under the conditions for dissociating the acid dissociable group. In this specification, the "dissociation" of the acid dissociable group means dissociation when post-exposure baking is performed at 110 °C for 60 seconds.

[0203] Examples of the radiation-sensitive weak acid generator include sulfonium salt compounds represented by the following formula (8-1), iodonium salt compounds represented by the following formula (8-2), and the like.

[0204]

Chemical formula

[0205] In the above formulas (8-1) and (8-2), J + is a sulfonium cation, and U + is an iodonium cation. Examples of the sulfonium cation represented by J + include the sulfonium cations represented by the above formulas (X-1) to (X-4), and examples of the iodonium cation represented by U + include the iodonium cations represented by the above formulas (X-5) to (X-6). E - and Q - are each independently an anion represented by OH - , R αα -COO - , -N - -. R αα is an alkyl group, an aryl group, or an aralkyl group. The hydrogen atom of the alkyl group represented by R αα , or the hydrogen atom of the aromatic ring of the aryl group or aralkyl group may be substituted with a halogen atom, a hydroxy group, a nitro group, a halogen atom-substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.

[0206] Examples of the radiation-sensitive weak acid generator include compounds represented by the following formulae.

[0207]

Chemical formula

[0208] The lower limit of the content of the acid diffusion controller is preferably 5 mol%, more preferably 10 mol%, and even more preferably 15 mol% with respect to the total number of moles of the radiation-sensitive acid generator. The upper limit of the above content is preferably 60 mol%, more preferably 55 mol%, and even more preferably 50 mol%. By setting the content of the acid diffusion controller within the above range, the lithography performance of the radiation-sensitive resin composition can be further improved. The radiation-sensitive resin composition may contain one or more acid diffusion controllers.

[0209] <Solvent> The radiation-sensitive resin composition according to this embodiment contains a solvent. The solvent is not particularly limited as long as it can dissolve or disperse at least the resin, the radiation-sensitive acid generator, and additives contained as desired.

[0210] Examples of the solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents, and the like.

[0211] Examples of the alcohol solvent 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 with 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, tripropylene glycol, etc.; Examples include polyhydric alcohol partial ether solvents in which some of the hydroxy groups of the above polyhydric alcohol solvents are etherified.

[0212] As ether solvents, for example, Dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, etc.; Cyclic ether solvents such as tetrahydrofuran, tetrahydropyran, etc.; Aromatic ring-containing ether solvents such as diphenyl ether, anisole (methyl phenyl ether), etc.; Examples include polyhydric alcohol ether solvents in which the hydroxy groups of the above polyhydric alcohol solvents are etherified.

[0213] As ketone solvents, for example, chain ketone solvents such as acetone, butanone, methyl-iso-butyl ketone, etc.: Cyclic ketone solvents such as cyclopentanone, cyclohexanone, methylcyclohexanone, etc.: Examples include 2,4-pentanedione, acetonylacetone, acetophenone, etc.

[0214] As amide solvents, for example, cyclic amide solvents such as N,N'-dimethylimidazolidinone, N-methylpyrrolidone, etc.; Examples include chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpropionamide, etc.

[0215] As ester solvents, for example, Monocarboxylic acid ester solvents such as n-butyl acetate, ethyl lactate, etc.; Polyhydric alcohol partial ether acetate solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate; Lactone solvents such as γ-butyrolactone and valerolactone; Carbonate solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; Examples of polyvalent carboxylic acid diester solvents include propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, ethyl lactate, and diethyl phthalate.

[0216] Examples of hydrocarbon solvents include Aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; Aromatic hydrocarbon solvents such as benzene, toluene, di-iso-propylbenzene, and n-amylnaphthalene.

[0217] 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 radiation-sensitive resin composition may contain one or more solvents.

[0218] <Other optional components> In addition to the above components, the radiation-sensitive resin composition may also contain other optional components. Examples of the other optional components include crosslinking agents, uneven distribution accelerators, surfactants, alicyclic skeleton-containing compounds, sensitizers, etc. These other optional components may be used alone or in combination of two or more.

[0219] (Crosslinking agent) The crosslinking agent is a compound having two or more functional groups. In the baking process after the batch exposure process, it causes a crosslinking reaction in the polymer component by an acid-catalyzed reaction, and increases the molecular weight of the (1) polymer component, thereby reducing the solubility of the pattern-exposed portion in the developer. Examples of the above functional groups include (meth)acryloyl group, hydroxymethyl group, alkoxymethyl group, epoxy group, vinyl ether group, etc.

[0220] (Phase separation promoter) The phase separation promoter has the effect of more efficiently phase-separating the above high-fluorine content resin on the resist film surface. By including this phase separation promoter in the above radiation-sensitive resin composition, the addition amount of the above high-fluorine content resin can be made less than before. Therefore, while maintaining the lithography performance of the above 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 those that can be used as such a phase separation promoter include, for example, low molecular weight 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, etc.

[0221] (Surfactant) Surfactants have the effect of improving coatability, striation, developability, etc. Examples of surfactants include nonionic surfactants such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, and polyethylene glycol distearate; commercially available products include KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, No. 95 (manufactured by Kyoeisha Chemical Co., Ltd. for both), EFtop EF301, EF303, EF352 (manufactured by Tocem Products Co., Ltd. for all), Megafac F171, F173 (manufactured by DIC for both), Fluorad FC430, FC431 (manufactured by Sumitomo 3M Ltd. for both), Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (manufactured by Asahi Glass Co., Ltd. for all), etc. The content of the surfactant 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.

[0222] (alicyclic skeleton-containing compound) The alicyclic skeleton-containing compound has the effect of improving dry etching resistance, pattern shape, adhesion to the substrate, etc.

[0223] 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 and the like 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.

[0224] (Sensitizer) The sensitizer exhibits an action of increasing the amount of acid generated from a radiation-sensitive acid generator or the like, and has an effect of improving the "apparent sensitivity" of the above radiation-sensitive resin composition.

[0225] Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines and the like. 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.

[0226] <Method for preparing a radiation-sensitive resin composition> The above radiation-sensitive resin composition can be prepared, for example, by mixing a resin, a radiation-sensitive acid generator and a solvent, and, if necessary, other optional components in a predetermined ratio. After mixing, the above radiation-sensitive resin composition is preferably filtered, for example, with a filter having a pore size of about 0.05 μm. The solid content concentration of the above 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.

[0227] 《Pattern formation method》 The pattern formation method in this embodiment is a step (1) of directly or indirectly applying the above radiation-sensitive resin composition onto a substrate to form a resist film (hereinafter, also referred to as "resist film formation step"), The step of exposing the resist film (2) (hereinafter also referred to as the "exposure step"), and include the step of developing the exposed resist film (3) (hereinafter also referred to as the "development step").

[0228] According to the above pattern forming method, since the radiation-sensitive resin composition excellent in sensitivity, CDU performance, and resolution in the exposure step is used, a high-quality resist pattern can be formed. Hereinafter, each step will be described.

[0229] [Resist Film Formation Step] In this step (the above step (1)), a resist film is formed using the radiation-sensitive resin composition. 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, if necessary, pre-baking (PB) may be performed 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.

[0230] When performing immersion exposure, regardless of the presence or absence of a water-repellent polymer additive such as the high-fluorine content resin in the radiation-sensitive resin composition, for the purpose of avoiding direct contact between the immersion liquid and the resist film, an immersion protective film insoluble in the immersion liquid may be provided on the formed resist film. As the immersion protective film, a solvent-peeling type protective film that peels off with a solvent before the development process (see, for example, JP-A-2006-227632), or a developer-peeling type 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-peeling type immersion protective film.

[0231] Further, when performing the exposure process, which is the next process, with radiation having a wavelength of 50 nm or less, it is preferable to use a resin having the structural unit C as necessary together with the structural unit A as the base resin in the composition.

[0232] [Exposure Process] In this process (the above process (2)), the resist film formed in the resist film formation process, which is the above process (1), is irradiated with radiation (in some cases, through an immersion medium such as water) through a photomask for exposure. Examples of the radiation used for exposure include electromagnetic waves such as visible light, ultraviolet light, deep ultraviolet light, EUV (extreme ultraviolet light), X-rays, and γ-rays; and charged particle beams such as electron beams and α-rays, according to the line width of the target pattern. Among these, deep ultraviolet light, electron beams, and EUV are preferable, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV are more preferable, and electron beams and EUV having a wavelength of 50 nm or less, which are positioned as the next-generation exposure technology, are even more preferable.

[0233] When performing exposure by liquid immersion exposure, examples of the liquid immersion liquid to be used include water, fluorine-based inert liquids, and the like. The liquid immersion liquid is preferably a liquid that is transparent to the exposure light wavelength and has a temperature coefficient of refractive index that minimizes the distortion of the optical image projected onto the film as much as possible. In particular, when the exposure light source is ArF excimer laser light (wavelength 193 nm), in addition to the above viewpoints, it is preferable to use water from the viewpoints of easy availability and ease of handling. When using water, an additive that reduces the surface tension of water and increases the interfacial active force 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 preferably used as the water to be used.

[0234] After the above exposure, post-exposure baking (PEB) is preferably performed to promote the dissociation of the acid-dissociable groups of the resin and the like by the acid generated from the radiation-sensitive acid generator by exposure in the exposed portion of the resist film. By this PEB, a difference in solubility in the developer occurs between the exposed portion and the unexposed portion. The PEB temperature is usually 50°C to 180°C, preferably 80°C to 130°C. The PEB time is usually 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds.

[0235] [Development process] In this step (the above step (3)), the resist film exposed in the above exposure step (the above step (2)) is developed. Thereby, a predetermined resist pattern can be formed. After development, it is common to wash with a rinse liquid such as water or alcohol and then dry.

[0236] As the developer used for the above development, in the case of alkali 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, a TMAH aqueous solution is preferable, and a 2.38 mass% TMAH aqueous solution is more preferable.

[0237] In the case of organic solvent development, examples thereof include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents and other organic solvents, or 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 preferable. As the ester solvent, an acetic acid ester solvent is preferable, and n-butyl acetate and amyl acetate are more preferable. As the ketone solvent, a chain ketone is preferable, and 2-heptanone is more preferable. The content of the organic solvent in the developer is preferably 80 mass% or more, more preferably 90 mass% or more, still more preferably 95 mass% or more, and particularly preferably 99 mass% or more. Examples of components other than the organic solvent in the developer include water, silicone oil and the like.

[0238] 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), a method of continuously discharging the developer while scanning a developer discharge nozzle at a constant speed on a substrate rotating at a constant speed (dynamic dispense method), and the like.

Example

[0239] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. The measurement methods of various physical property values are shown below. In the polymerization reactions of the following synthesis examples, unless otherwise specified, parts by mass mean the values when the total mass of the monomers used is 100 parts by mass, and mol% means the values when the total number of moles of the monomers used is 100 mol%.

[0240] [Measurement of weight-average molecular weight (Mw), number-average molecular weight (Mn), and dispersity (Mw / Mn)] It was measured under the measurement conditions described in the resin section. Also, the dispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[0241] 1 1H-NMR analysis and 13 13C-NMR analysis] It was measured using "JNM-Delta400" manufactured by JEOL Ltd.

[0242] <Synthesis of [Z] monomer compound> [Synthesis Example 1: Synthesis of monomer compound (Z-1)] According to the following reaction scheme, monomer compound (Z-1) was synthesized.

[0243]

Chemical formula

[0244] ​A compound represented by (P1-1) (154 mmol), N,N-dimethylaminopyridine (15.4 mmol), and t-butyl alcohol (154 mL) were mixed in a reaction vessel and stirred at room temperature. Subsequently, a solution of N,N'-dicyclohexylcarbodiimide (169 mmol) in tetrahydrofuran (THF) (384 mL) was added dropwise over 1 hour. After completion of the addition, the mixture was stirred at room temperature for an additional 10 hours, then methylene chloride (500 mL) was added and the mixture was filtered. The solvent of the filtrate was evaporated. By purification using silica gel column chromatography, compound (P2-1) was obtained in a yield of 93%.

[0245] Compound (P2-1) (142 mmol) was dissolved in THF (284 mL), stirred at room temperature, and pyridine (355 mmol) was added dropwise. After completion of the addition, the reaction solution was cooled to 0 °C, and a solution of acetyl chloride (355 mmol) in THF (284 mL) was added dropwise over 1 hour. The temperature was raised to room temperature and the mixture was stirred for an additional 3 hours. After cooling, ultrapure water (500 mL) was added and the mixture was extracted three times with 300 mL of ethyl acetate. Subsequently, the organic layer was washed with saturated brine (500 mL), and the organic layer was dried over sodium sulfate. The solvent was evaporated, and by purification using silica gel column chromatography, compound (P3-1) was obtained in a yield of 99% or more.

[0246] Zinc powder (578 mmol) and N,N'-dimethylformamide (156 mL) were mixed and stirred at room temperature for 10 minutes, then acetyl chloride (14.2 mmol) was added dropwise, and the mixture was stirred at room temperature for 1 hour. Subsequently, a solution of compound (P3-1) (142 mmol) and dibromomethane (234 mmol) in N,N'-dimethylformamide (60 mL) was added dropwise over 2 hours. After completion of the addition, acetic anhydride (142 mmol) was added dropwise and the mixture was stirred for 1 hour, then 500 mL of saturated aqueous ammonium chloride solution was added. The mixture was extracted three times with 300 mL of ethyl acetate, and the organic layer was washed with saturated aqueous sodium hydrogen carbonate solution and then with saturated brine. The organic layer was dried over sodium sulfate and concentrated, and by purification using silica gel column chromatography, compound (Z-1) was obtained in a yield of 66%.

[0247] [Synthesis Examples 2 to 20: Synthesis of Monomer Compounds (Z-2) to (Z-20)] By appropriately selecting the precursors and choosing the same formulation as in Example 1, the [Z] monomer compounds represented by the following formulas (Z-2) to (Z-20) were synthesized.

Chemical formula

[0248]

Chemical formula

[0249] <Synthesis of [A] resin> The monomers used in the synthesis of each resin in each example and comparative example are shown below. Among the structural units B derived from (meth)acrylate monomers, (M-4), (M-5), and (M-6) were used as the compounds that give the structural unit B1 having an acid dissociable group, (M-9) was used as the compound that gives the structural unit B2 having a non-acid dissociable group, (M-1), (M-2), and (M-3) were used as the compounds that give the structural unit C having a phenolic hydroxyl group, (M-7) and (M-8) were used as the compounds that give the structural unit D having a polar group, and (M-10) was used as the compound that gives the structural unit G that forms a high fluorine content resin.

[0250]

Chemical formula

[0251] [Synthesis Example 21: Synthesis of Resin (A-1)] The compound (Z-1) as a monomer was dissolved in propylene glycol monomethyl ether (200 parts by mass). To this, 2,2'-azobis(isobutyric acid methyl) (10 mol%) was added as an initiator to prepare a monomer solution. On the other hand, propylene glycol monomethyl ether (100 parts by mass based on the total monomer amount) was added to an empty reaction vessel and heated to 85°C while stirring. Next, the monomer solution prepared above was dropped over 3 hours, and then further heated at 85°C for 3 hours, and the polymerization reaction was carried out for a total of 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to room temperature. The polymerization solution was dropped into n-hexane (1,000 parts by mass) to coagulate and purify the polymer. To the above polymer, propylene glycol monomethyl ether (150 parts by mass) was added again. Further, methanol (150 parts by mass), triethylamine (1.5 molar equivalents based on the amount of compound (Z-1) used), and water (1.5 molar equivalents based on the amount of compound (Z-1) used) were added, and a hydrolysis reaction was carried out for 8 hours while refluxing at the boiling point. After the reaction was completed, the solvent and triethylamine were distilled off under reduced pressure, and the obtained polymer was dissolved in acetone (150 parts by mass). This was dropped into water (2,000 parts by mass) to coagulate, and the generated white powder was filtered off. It was dried at 50°C for 17 hours to obtain a white powdery resin (A-1) in good yield.

[0252] [Synthesis Examples 22 to 60: Synthesis of Resins (A-2) to (A-38), (CA-1), and (CA-2)] By appropriately selecting monomers and performing the same operations as in Synthesis Example 21, resins (A-2) to (A-38), (CA-1), and (CA-2) were synthesized. The total amount of triethylamine and water used was 1.5 molar equivalents based on the amounts of compounds (Z-1) to (Z-20) and (M-1), (M-3) used, and 3.0 molar equivalents based on the amount of compound (M-2) used.

[0253] The amounts of use, Mw, and Mw / Mn values of each structural unit of the obtained resins are shown in accordance with Table 1.

[0254]

Table 1

[0255] [Synthesis Example 61: Synthesis of High-Fluorine Content Resin (B)] Compound (M-6) and Compound (M-10) as monomers were dissolved in 2-butanone (100 parts by mass) so that the molar ratio was 70 / 30. Azobisisobutyronitrile (5 mol%) was added thereto as an initiator to prepare a monomer solution. On the other hand, 2-butanone (50 parts by mass) was placed in an empty reaction vessel and purged with nitrogen for 30 minutes. The inside of the reaction vessel was set at 80°C, and while stirring, the above monomer solution was dropped over 3 hours. The start of dropping was taken 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 a temperature of 30°C or lower. After transferring the reaction solution to a separatory funnel, the reaction solution was uniformly diluted with hexane (150 parts by mass), and then methanol (600 parts by mass) and water (30 parts by mass) were added and mixed. After standing for 30 minutes, the lower layer was recovered, and the solvent was replaced with propylene glycol monomethyl ether acetate to obtain a propylene glycol monomethyl ether acetate solution containing high-fluorine content resin (B).

[0256] [Preparation of Radiation-Sensitive Resin Composition] [C] Radiation-Sensitive Acid Generator, [CC] Other Radiation-Sensitive Acid Generators, [D] Acid Diffusion Controller, and [E] Solvent used for the preparation of the radiation-sensitive resin compositions in the following Examples and Comparative Examples are shown below.

[0257] [C] Radiation-Sensitive Acid Generator Compounds represented by the following formulas (C-1) to (C-11) were used as the radiation-sensitive acid generator.

[0258] [Chemical Formula]

[0259] [CC] Other Radiation-Sensitive Acid Generators Compounds represented by the following formulas (CC-1) and (CC-2) were used as the other radiation-sensitive acid generators.

[0260] [Chemical Formula]

[0261] [D] Acid diffusion control agent As the acid diffusion control agent, the compounds represented by the following formulas (D-1) to (D-3) were used.

[0262]

Chemical formula

[0263] [E] Solvent E-1: Propylene glycol monomethyl ether acetate E-2: Propylene glycol monomethyl ether

[0264] [Example 1] [A] 100 parts by mass of resin (A-1), [B] 1 part by mass of high fluorine content resin (B), [C] 5 parts by mass of (C-1) as a radiation-sensitive acid generator, [D] 20 mol% of (D-1) as an acid diffusion inhibitor with respect to (C-1), [E] 7700 parts by mass of (E-1) and 3300 parts by mass of (E-2) as organic solvents were blended to prepare a radiation-sensitive resin composition (R-1).

[0265] [Examples 2 to 38 and Comparative Examples 1 to 5] Except for using the components of the types and blending amounts shown in Table 2 below, the same operations as in Example 1 were carried out to prepare radiation-sensitive resin compositions (R-2) to (R-38) and (CR-1) to (CR-5).

Table 2

[0266] <Formation of resist pattern> 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 of the above-prepared radiation-sensitive resin compositions was applied using a spin coater (CLEAN TRACK ACT12, manufactured by Tokyo Electron). After performing SB (soft bake) at 100 °C for 60 seconds, it was cooled at 23 °C for 30 seconds to form a resist film with a film thickness of 30 nm. Next, this resist film was irradiated with EUV light using an EUV exposure machine (model "NXE3300", manufactured by ASML, NA = 0.33, illumination condition: Conventional s = 0.89). PEB (post-exposure bake) was performed on the above resist film at 100 °C for 60 seconds. Then, development was carried out at 23 °C for 30 seconds using a 2.38 wt% aqueous solution of tetramethylammonium hydroxide to form a contact hole pattern (diameter 25 nm, 50 nm pitch).

[0267] <Evaluation> For each of the above-formed resist patterns, the sensitivity, CDU performance, and resolution of each radiation-sensitive resin composition were evaluated by measuring according to the following method. A scanning electron microscope ("CG-5000" of Hitachi High-Technologies) was used for measuring the length of the resist pattern. The evaluation results are shown in Table 3 below.

[0268] [Sensitivity] In the formation of the above resist pattern, the exposure amount for forming a contact hole pattern with a diameter of 25 nm was defined as the optimum exposure amount, and this optimum exposure amount was taken as the sensitivity (mJ / cm 2 ). The sensitivity was determined to be "good" when it was 60 mJ / cm 2 or less, and "bad" when it exceeded 60 mJ / cm 2 .

[0269] [CDU Performance] Using the above scanning electron microscope, the resist pattern was observed from above, and 800 length measurements were taken at arbitrary points. The dimensional variation (3σ) was determined and used as the CDU performance (nm). The smaller the value of CDU, the smaller the variation in hole diameter in the long period and the better the performance. The CDU performance was evaluated as "good" when it was 4.5 nm or less and "bad" when it exceeded 4.5 nm.

[0270] [Resolution] When the exposure dose was changed, the diameter of the smallest contact hole pattern that could be resolved was measured, and this measured value was used as the resolution (nm). The smaller the value of the resolution, the better the performance. The resolution was evaluated as "good" when it was 22 nm or less and "bad" when it exceeded 22 nm.

[0271]

Table 3

[0272] <Synthesis of [Z] Monomer Compound> [Synthesis Example 62: Synthesis of Monomer Compound (Z-21)] According to the following reaction scheme, monomer compound (Z-21) was synthesized.

[0273]

Chemical Formula

[0274] Zinc powder (578 mmol) and N,N'-dimethylformamide (156 mL) were mixed and stirred at room temperature for 10 minutes. Then, acetyl chloride (14.2 mmol) was added dropwise, and the mixture was stirred at room temperature for 1 hour. Subsequently, a solution of compound (P2-1) (142 mmol) and dibromomethane (234 mmol) in N,N'-dimethylformamide (60 mL) was added dropwise over 2 hours. After the addition was complete, 500 mL of saturated aqueous ammonium chloride solution was added. The mixture was extracted three times with 300 mL of ethyl acetate, and the organic layer was washed with saturated aqueous sodium hydrogen carbonate solution and then with saturated brine. The organic layer was dried over sodium sulfate and concentrated, and purified by silica gel column chromatography to obtain compound (Z-21) in a yield of 52%.

[0275] <[Synthesis of Resin]> The monomers used in the synthesis of each resin in each example and comparative example are shown below. (M-11) and (M-12) were used as the compounds that give the structural unit C having a phenolic hydroxyl group, and (M-13) and (M-14) were used as the compounds that give the structural unit having a radiation-sensitive acid-generating group.

[0276] [Chemical Formula]

[0277] [Synthesis Example 63: Synthesis of Resin (A-39)] The compounds (Z-21), (M-6), (M-12), and (M-13) as monomers were dissolved in tetrahydrofuran (200 parts by mass) so that the molar ratio was 10 / 45 / 30 / 15. 2,2'-Azobis(isobutyronitrile) (10 mol%) was added thereto as an initiator to prepare a monomer solution. On the other hand, tetrahydrofuran (100 parts by mass based on the total monomer amount) was added to an empty reaction vessel and refluxed with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours, and then refluxed for another 3 hours, and the polymerization reaction was carried out for a total of 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to room temperature. The polymerization solution was added dropwise into methanol (1,000 parts by mass) to coagulate and purify the polymer. After repeated washing with hexane, it was isolated and dried to obtain a white powdery resin (A-39) in a good yield.

[0278] [Synthesis Example 64: Synthesis of Resin (A-40)] Resin (A-40) was synthesized by appropriately selecting monomers and performing the same operations as in Synthesis Example 63.

[0279] The amounts of use, Mw, and Mw / Mn values of the respective structural units of the obtained resin are shown in accordance with Table 4.

[0280] [Table 4]

[0281] [Preparation of Radiation-Sensitive Resin Composition] [C] Radiation-Sensitive Acid Generator, [CC] Other Radiation-Sensitive Acid Generators, [D] Acid Diffusion Controller, and [E] Solvent used for the preparation of the radiation-sensitive resin compositions in the following Examples and Comparative Examples are shown below.

[0282] [C] Radiation-Sensitive Acid Generator Compounds represented by the following formulas (C-12) to (C-14) were used as the radiation-sensitive acid generator.

[0283] [Chemical Formula]

[0284] [Examples 39 to 43] Except for using each component of the types and compounding amounts shown in Table 5 below, the same operations as in Example 1 were carried out to prepare radiation-sensitive resin compositions (R-39) to (R-43).

[0285] [Table 5]

[0286] [Formation and Evaluation of Resist Pattern] Contact hole patterns (diameter 25 nm, 50 nm pitch) were formed in the same manner as in Examples 1 to 38 and Comparative Examples 1 to 5. Next, for each of the resist patterns formed above, the sensitivity, CDU performance, and resolution of each radiation-sensitive resin composition were evaluated in the same manner as in Examples 1 to 38 and Comparative Examples 1 to 5. The evaluation results are shown in Table 6 below.

[0287] [Table 6]

[0288] [Preparation of Radiation-Sensitive Resin Composition] The [D] acid diffusion control agent used in the preparation of the radiation-sensitive resin compositions in the following examples is shown below.

[0289] [D] Acid Diffusion Control Agent A compound represented by the following formula (D-4) was used as the acid diffusion control agent.

[0290] [Chemical Formula]

[0291] [Example 44] Except for using each component of the types and compounding amounts shown in Table 7 below, the same operations as in Example 1 were carried out to prepare a radiation-sensitive resin composition (R-44).

[0292] [Table 7]

[0293] <Formation and Evaluation of Resist Pattern> Contact hole patterns (diameter 25 nm, 50 nm pitch) were formed in the same manner as in Examples 1 to 38 and Comparative Examples 1 to 5. Next, for each of the resist patterns formed above, the sensitivity, CDU performance, and resolution of each radiation-sensitive resin composition were evaluated in the same manner as in Examples 1 to 38 and Comparative Examples 1 to 5. The evaluation results are shown in Table 8 below.

[0294]

Table 8

[0295] As is clear from the results of Tables 3 and 6, in all of the radiation-sensitive resin compositions of the examples, the sensitivity, CDU performance, and resolution were better than those of the radiation-sensitive resin compositions of the comparative examples. As is clear from the results of Table 8, in the radiation-sensitive resin compositions of the examples, the sensitivity, CDU performance, and resolution were good.

Industrial Applicability

[0296] According to the radiation-sensitive resin composition and the pattern forming method of the present invention, the sensitivity, CDU, and resolution can be improved as compared with the prior art. Therefore, these 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. A resin including a structural unit A represented by the following formula (1), at least one radiation-sensitive acid generator selected from the group consisting of a radiation-sensitive acid generator represented by the following formula (2-1) and a radiation-sensitive acid generator represented by the following formula (2-2); Solvent and A radiation-sensitive resin composition comprising: 【Chemistry 1】 (In the above formula (1), R １ and R ２ are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ３ is an acid dissociable group. ３ When there are multiple R ３ are the same or different from each other. R ４１ is a hydrogen atom or a protecting group which is deprotected by the action of an acid. ４１ When there are multiple R ４１ are the same or different from each other. R ５１ R is a cyano group, a nitro group, an alkyl group, a fluorinated alkyl group, an alkoxycarbonyloxy group, an acyl group, or an acyloxy group. ５１ When there are multiple R ５１ are the same or different from each other. n １ is an integer from 0 to 2, m １ is an integer from 1 to 8, m ２ is an integer from 1 to 8, m ３ is an integer from 0 to 6, provided that 2≦m １ +m ２ +m ３ ≦2n １ Meets +5. The above R ３ The acid-dissociable group is represented by the following formula (2). 【Chemistry 2】 In the above formula (2), R ８ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, R ９ and R １０ represents a divalent alicyclic group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atom to which they are bonded; or R ８ is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, R ９ and R １０ are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms. * indicates a bond to the oxygen atom.) 【Chemistry 3】 (In the above formula (2-1), n ２ is an integer from 1 to 5. R ｆ１ and R ｆ２ are each independently a hydrogen atom, a fluorine atom or a fluoroalkyl group. ２ If R is 1, ｆ１ and R ｆ２ At least one of n is a fluorine atom or a fluoroalkyl group. ２ When R is 2 to 5, there are multiple R ｆ１ and R ｆ２ At least one of R is a fluorine atom or a fluoroalkyl group, ｆ１ and R ｆ２ are the same or different from each other. L １ is a divalent linking group. R ５ａ is a monovalent organic group having a ring structure. X １ ＋ is a monovalent onium cation. In the above formula (2-2), R ５ｂ is a monovalent organic group. X ２ ＋ is a monovalent onium cation in which the positively charged atom is not one that forms a ring structure.

2. In the above formula (1), the R ３ 2. The radiation-sensitive resin composition according to claim 1, wherein the acid-dissociable group has a structure represented by any one of the following formulas (3-1) to (3-2) and (3-4) to (3-8): 【Chemistry 4】 (In the above formulas (3-1) to (3-2) and (3-4) to (3-8), R ８ ~R １０ is the same as in formula (2) above. i and j each independently represent an integer from 1 to 4. k and l each represent 0 or 1. * represents a bond to an oxygen atom.

3. 2. The radiation-sensitive resin composition according to claim 1, wherein the resin further comprises a structural unit B derived from a (meth)acrylic acid ester monomer.

4. 4. The radiation-sensitive resin composition according to claim 3, wherein the structural unit B comprises a structural unit B1 (excluding the structural unit A) having an acid-dissociable group.

5. The radiation-sensitive resin composition according to any one of claims 1 to 4, wherein the resin further comprises a structural unit C represented by the following formula (5): 【Chemistry 5】 (In the above formula (5), R α is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. L ＣＡ is a single bond, -COO- ＊ Or -O- ＊ * indicates a bond on the aromatic ring side. R ４２ and R ５２ is R in the above formula (1). ４１ and R ５１ are synonymous with each other. n ３ is an integer from 0 to 2, m ３ is an integer from 1 to 8, m ４ is an integer from 0 to 8, provided that 1≦m ３ +m ４ ≦2n ３ Meets +5.)

6. In the above formula (1), COOR ３ and the carbon atom to which OR ４１ The radiation-sensitive resin composition according to any one of claims 1 to 5, wherein the carbon atom to which is bonded is adjacent to the carbon atom to which is bonded.

7. 7. The radiation-sensitive resin composition according to claim 1, further comprising an onium salt compound that, upon irradiation with radiation, generates an acid having a higher pKa than the acid generated from the radiation-sensitive acid generator.

8. The radiation-sensitive resin composition according to any one of claims 1 to 7, wherein the onium cations in the formulas (2-1) and (2-2) are each independently a sulfonium cation or an iodonium cation.

9. A step of directly or indirectly applying the radiation-sensitive resin composition according to any one of claims 1 to 8 onto a substrate to form a resist film; exposing the resist film to light; developing the exposed resist film with a developer; A pattern forming method comprising the steps of:

10. The method for forming a pattern according to claim 9, wherein the exposure is carried out using extreme ultraviolet rays or electron beams.

Images