Radiation-sensitive resin composition, pattern forming method, and onium salt compound

Abstract

The present invention provides: a radiation sensitive resin composition which is capable of exhibiting sensitivity, CDU performance and LWR performance at sufficient levels; and a method for forming a resist pattern. A radiation sensitive resin composition which contains an onium salt compound, a resin that contains a structural unit having an acid cleavable group, and a solvent, wherein the onium salt compound is at least one compound that is selected from the group consisting of an onium salt compound (1) represented by formula (1) and an onium salt compound (2) represented by formula (2). (In formula (1), R1 represents a hydrogen atom or a monovalent organic group having from 1 to 40 carbon atoms;　each of R2 and R3 independently represents a hydrogen atom, a halogen atom, a carboxy group, an amino group or a monovalent organic group having from 1 to 40 carbon atoms, or alternatively, R2 and R3 combine with each other to form a ring structure having from 5 to 8 ring members together with two carbon atoms to which these moieties are bonded;　each of X1 and X2 independently represents an oxygen atom or a sulfur atom, provided that the X1 and X2 moieties are not sulfur atoms at the same time; and　Z1 + represents a monovalent radiation sensitive onium cation.　In formula (2), R1 represents a hydrogen atom, a halogen atom, or a monovalent organic group having from 1 to 40 carbon atoms;　each of R5 and R6 independently represents a hydrogen atom or a monovalent organic group having from 1 to 40 carbon atoms, or alternatively, R5 and R6 combine with each other to form a ring structure having from 3 to 8 ring members together with a nitrogen atom to which these moieties are bonded; and　Z2 + represents a monovalent radiation sensitive onium cation.)

Description

Technical Field

[0001] The present invention relates to a radiation-sensitive resin composition, a patterning method, and an onium salt compound.

Background Art

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

[0003] In the above photolithography technology, radiation with a short wavelength such as an ArF excimer laser is used, or a liquid immersion lithography method (liquid immersion lithography) in which the space between the lens of an exposure apparatus and the resist film is filled with a liquid medium and exposure is performed is used to promote pattern miniaturization.

[0004] While efforts are being made for further technological progress, a technique has been proposed in which a quencher (diffusion control agent) is blended in a resist composition to capture the acid diffused to the unexposed portion by a salt exchange reaction and improve the lithography performance by ArF exposure (Patent Document 1). Also, as a next-generation technology, lithography using radiation with a shorter wavelength such as an electron beam, X-ray, and EUV (extreme ultraviolet ray) is also being studied.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Among such efforts toward next-generation technologies, resist performances equivalent to or better than those of the prior art are required in terms of critical dimension uniformity (CDU) performance, which is an index of sensitivity, line width, and hole diameter uniformity, line width roughness (LWR) performance, which indicates the variation in the line width of the resist pattern, and other aspects. However, such characteristics have not been obtained at sufficient levels with existing radiation-sensitive resin compositions.

[0007] An object of the present invention is to provide a radiation-sensitive resin composition and a pattern forming method capable of exhibiting sensitivity, CDU performance, and LWR performance at sufficient levels.

Means for Solving the Problems

[0008] As a result of intensive studies to solve this problem, the present inventors have found that the above object can be achieved by adopting the following configuration, and have completed the present invention.

[0009] That is, in one embodiment, the present invention provides a radiation-sensitive resin composition comprising an onium salt compound, a resin containing a structural unit having an acid dissociable group, a solvent, and the onium salt compound is at least one selected from the group consisting of an onium salt compound (1) represented by the following formula (1) and an onium salt compound (2) represented by the following formula (2).

Chemical formula

[0010] Since the radiation-sensitive resin composition contains at least one of the onium salt compound (1) and the onium salt compound (2) as a quencher (acid diffusion controller), it can exhibit excellent sensitivity, CDU performance, and LWR performance during resist pattern formation. Although not bound by any theory, it is presumed that this is because both onium salt compounds have high transparency in the resist film, resulting in good sensitivity, and because they are relatively strongly basic, which affects their high acid-capturing ability in the unexposed areas. An organic group means a group containing at least one carbon atom.

[0011] In another embodiment, the present invention relates to a pattern formation method including a step of directly or indirectly applying the radiation-sensitive resin composition onto a substrate to form a resist film, a step of exposing the resist film, and a step of developing the exposed resist film with a developer and.

[0012] In this pattern formation method, since the radiation-sensitive resin composition excellent in sensitivity, CDU performance, and LWR performance is used, a high-quality resist pattern can be efficiently formed.

[0013] In still another embodiment, the present invention relates to an onium salt compound represented by the following formula (1) (that is, onium salt compound (1)).

Chemical formula

[0014] In yet another embodiment, the present invention relates to an onium salt compound represented by the following formula (2) (that is, onium salt compound (2)).

Chemical formula

[0015] Since both of the onium salt compounds (1) and (2) can exhibit transparency and strong basicity in the resist film, when they are blended in a radiation-sensitive resin composition, excellent sensitivity, CDU performance, and LWR performance during resist pattern formation can be imparted to the composition.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.

[0017] <Radiation-Sensitive Resin Composition> The radiation-sensitive resin composition according to the present embodiment (hereinafter, also simply referred to as "composition") contains a predetermined onium salt compound, a resin, and a solvent. Further, a radiation-sensitive acid generator is included as necessary. The above composition may contain other optional components as long as the effects of the present invention are not impaired. By containing a predetermined onium salt compound, the radiation-sensitive resin composition can be imparted with high levels of sensitivity, CDU performance, and LWR performance.

[0018] (Onium Salt Compound) The above onium salt compound can function as a quencher (also referred to as a "photodecomposable base" or "acid diffusion controller") that captures an acid in the pre-exposure or unexposed portion.

[0019] (Onium Salt Compound (1)) The onium salt compound (1) is represented by the following formula (1).

[0020]

Chemical Formula

[0021] In the above formula (1), R 1 , R 2 and R 3 The monovalent organic group having 1 to 40 carbon atoms represented by 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 are either saturated or unsaturated, linear or branched. Examples of the above cyclic structure include cyclic hydrocarbon groups that are either alicyclic, aromatic or heterocyclic. 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, a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms or a combination thereof is preferable. Further, a group 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, a group containing CO, CS, O, S, SO2 or NR', or a combination of two or more of these between carbon-carbon of these groups, etc. are also included. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0022] Examples of the substituent that substitutes for some or all of the hydrogen atoms of the above organic group include halogen atoms such as fluorine atom, chlorine atom, bromine atom, 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 a hydrogen atom of these groups is substituted with a halogen atom; oxo group (=O), etc.

[0023] Examples of the monovalent linear hydrocarbon group having 1 to 20 carbon atoms include a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, or a linear or branched unsaturated hydrocarbon group having 1 to 20 carbon atoms, etc.

[0024] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include a monocyclic or polycyclic saturated hydrocarbon group, or a monocyclic or polycyclic unsaturated hydrocarbon group, etc. Preferred examples of the monocyclic saturated hydrocarbon group include cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group. Preferred examples of the polycyclic cycloalkyl group include bridged alicyclic hydrocarbon groups such as norbornyl group, adamantyl group, tricyclodecyl group, tetracyclododecyl group. Examples of the monocyclic unsaturated hydrocarbon group include monocyclic cycloalkenyl groups such as cyclopropenyl group, cyclobutenyl group, cyclopentenyl group, cyclohexenyl group. Examples of the polycyclic unsaturated hydrocarbon group include polycyclic cycloalkenyl groups such as norbornenyl group, tricyclodecenyl group, tetracyclododecenyl group. Note that 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.

[0025] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group, anthryl group; aralkyl groups such as benzyl group, phenethyl group, naphthylmethyl group, etc.

[0026] Examples of the above-mentioned complex 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. Aromatic structures of 5-membered rings having aromaticity by introducing heteroatoms are also included in the heterocyclic structure. Examples of the heteroatom include an oxygen atom, a nitrogen atom, a sulfur atom, and the like.

[0027] Examples of the above-mentioned aromatic heterocyclic structure include Aromatic heterocyclic structures containing an oxygen atom such as furan, pyran, benzofuran, benzopyran, etc.; Aromatic heterocyclic structures containing a nitrogen atom such as pyrrole, imidazole, pyridine, pyrimidine, pyrazine, indole, quinoline, isoquinoline, acridine, phenazine, carbazole, etc.; Aromatic heterocyclic structures containing a sulfur atom such as thiophene, etc.; Aromatic heterocyclic structures containing a plurality of heteroatoms such as thiazole, benzothiazole, thiazine, oxazine, etc.

[0028] Examples of the above-mentioned alicyclic heterocyclic structure include Alicyclic heterocyclic structures containing an oxygen atom such as oxirane, tetrahydrofuran, tetrahydropyran, dioxolane, dioxane, etc.; Alicyclic heterocyclic structures containing a nitrogen atom such as aziridine, pyrrolidine, piperidine, piperazine, etc.; Alicyclic heterocyclic structures containing a sulfur atom such as thietane, thiolane, thiane, etc.; Alicyclic heterocyclic structures containing a plurality of heteroatoms such as morpholine, 1,2-oxathiolane, 1,3-oxathiolane, etc.

[0029] Examples of the cyclic structure include a lactone structure, a cyclic carbonate structure, a sultone structure, and a structure containing a cyclic acetal. Examples of such structures include structures represented by the following formulas (H-1) to (H-10).

[0030]

Chemical formula

[0031] In the above formula, m is an integer from 1 to 3.

[0032] In the above formula (1), the above R 2 and R 3 When combined with each other and together with the two carbon atoms to which they are attached to form a ring structure having 5 to 8 ring members, a preferred unsaturated cyclic hydrocarbon structure derived from a double bond between two carbon atoms can be mentioned. Examples of the unsaturated cyclic hydrocarbon structure include monocyclic cycloalkene structures having 5 to 8 carbon atoms such as cyclopentene, cyclohexene, and cycloheptene, and benzene rings.

[0033] In the above formula (1), R 2 and R 3 Examples of the halogen atom represented by include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.

[0034] In the above formula (1), R 2 and R 3 The amino group represented by may be substituted or unsubstituted. The unsubstituted amino group is represented by -NH2. Examples of the substituted amino group include alkylamino groups such as methylamino group and ethylamino group; dialkylamino groups such as dimethylamino group, diethylamino group, and dipropylamino group; cycloalkylamino groups such as cyclopropylamino group and cyclobutylamino group; dicycloalkylamino groups such as dicyclopropylamino group and dicyclobutylamino group; phenylamino group, diphenylamino group, etc.

[0035] X 1 and X 2 are each independently an oxygen atom or a sulfur atom. X 1 and X 2 are preferably both oxygen atoms from the viewpoints of compound stability, basicity, etc.

[0036] In the above formula (1), the above Z1 +Examples of the monovalent radiation-sensitive onium cation represented by 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 thereof include sulfonium cations, tetrahydrothiophenium cations, iodonium cations, phosphonium cations, diazonium cations, pyridinium cations, and the like. Among them, sulfonium cations or iodonium cations are preferable. The sulfonium cation or iodonium cation is preferably represented by the following formulas (X-1) to (X-6).

[0037] [Chemical formula]

[0038] [Chemical formula]

[0039] [Chemical formula]

[0040] [Chemical formula]

[0041] [Chemical formula]

[0042] [Chemical formula]

[0043] In the above formula (X-1), R a1 , R a2 and R a3is independently a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyloxy group having 1 to 12 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, -OSO2-R P , -SO2-R Q or -S-R T or represents a ring structure formed by combining two or more of these groups. 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 when each is plural, the plural R a1 ~R a3 as well as R P , R Q and R T may be the same or different from each other.

[0044] In the above formula (X-2), R b1 is a substituted or unsubstituted linear or branched alkyl group or alkoxy group having 1 to 20 carbon atoms, 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 is 0, k4 is an integer from 0 to 4, and n k when is 1, k4 is an integer from 0 to 7. R b1 when is plural, the plural R b1 may be the same or different, and also, the plural R b1may represent a ring structure that is configured to fit together 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 When there are a plurality of R b2 they may be the same or different, and a plurality of R b2 may represent a ring structure that is configured to fit together 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 or S between the carbon-carbon bonds forming the skeleton.

[0045] 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.

[0046] 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 k2 is 0, k10 is an integer from 0 to 4, and when n g1 is 1, k10 is an integer from 0 to 7. R g1 When there are a plurality of R g1 they may be the same or different, and a plurality of R g2 and R g3is, independently of each other, a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyloxy group having 1 to 12 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, or represents a ring structure formed by combining these groups with each other. k11 and k12 are each independently an integer of 0 to 4. R g2 and R g3 When there are a plurality of each of R g2 and R g3 may be the same as or different from each other.

[0047] In the above formula (X-5), R d1 and R d2 are, independently of each other, a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyl group having 1 to 12 carbon atoms, 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 represents a ring structure formed by combining two or more of these groups with each other. k6 and k7 are each independently an integer of 0 to 5. R d1 and R d2 When there are a plurality of each of R d1 and R d2 may be the same as or different from each other.

[0048] In the above formula (X-6), R e1 and R e2 are, independently of each other, 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.

[0049] The onium salt compound (1) is formed by a combination of an arbitrary anion moiety containing a group having the above chain structure, a group having the above cyclic structure, or a combination thereof, and the above monovalent radiation-sensitive onium cation. Specific examples of the onium salt compound (1) include, but are not limited to, the following formulas (1-1) to (1-19), etc.

[0050] [Chemical formula]

[0051] [Chemical formula]

[0052] Among them, the onium salt compound (1) represented by the above formulas (1-1) to (1-11) is preferable.

[0053] (Onium salt compound (2)) The onium salt compound (2) is represented by the following formula (2).

[0054] [Chemical formula] (In the above formula (2), R 4 is a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 40 carbon atoms. R 5 and R 6 are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms, or R 5 and R 6 are combined with each other and represent a ring structure having 3 to 8 ring members together with the nitrogen atom to which they are attached. Z2 + is a monovalent radiation-sensitive onium cation.)

[0055] In the above formula (2), R 4 , R 5 and R 6Examples of the monovalent organic group having 1 to 40 carbon atoms represented by the formula include R in the above formula (1). 1 R 2 and R 3 The monovalent organic group having 1 to 40 carbon atoms represented by the formula can preferably be adopted.

[0056] In the above formula (2), examples of the ring structure having 3 to 8 ring members formed by combining R 5 and R 6 together with the nitrogen atom to which they are bonded include nitrogen atom-containing alicyclic heterocyclic structures such as aziridine, pyrrolidine, piperidine, and piperazine.

[0057] In the above formula (2), examples of the monovalent radiation-sensitive onium cation represented by the above Z2 + include the monovalent radiation-sensitive onium cation represented by Z1 + in the above formula (1), which can preferably be adopted.

[0058] The onium salt compound (2) is formed by a combination of an arbitrary anion moiety containing a group having a chain structure similar to the above formula (1), a group having a cyclic structure, or a combination thereof, and the above monovalent radiation-sensitive onium cation. Specific examples of the onium salt compound (2) include, but are not limited to, the following formulas (2-1) to (2-8), etc.

[0059]

Chemical formula

[0060] Among them, the onium salt compounds (2) represented by the above formulas (2-1) to (2-4) are preferred.

[0061] The above radiation-sensitive resin composition contains at least one selected from the group consisting of an onium salt compound (1) and an onium salt compound (2) as an acid diffusion controller. The onium salt compound is preferably the onium salt compound (1) in terms of basicity (acid scavenging property), transparency, etc. As long as the effects of the present invention are not impaired, one or both of the onium salt compounds (1) and (2) and other known acid diffusion controllers other than the onium salt compounds (1) and (2) may be used in combination as the acid diffusion controller.

[0062] The content of the onium salt compound in the radiation-sensitive resin composition according to this embodiment (in the case of combined use of a plurality of types of onium salt compounds, the total thereof) is preferably 0.01 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the resin described later. The above content is more preferably 25 parts by mass or less, further preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less. Also, 0.05 part by mass or more is more preferably, 0.1 part by mass or more is further preferably, and 0.5 part by mass or more is particularly preferably. The content of the onium salt compound is appropriately selected according to the type of resin used, exposure conditions, required sensitivity, and the type and content of the radiation-sensitive acid generator described later. Thereby, excellent sensitivity, CDU performance, and LWR performance can be exhibited during resist pattern formation.

[0063] (Synthesis method of onium salt compound) Typically, as shown in the following scheme, the onium salt compound can be synthesized by reacting a pyrimidine base derivative (i) which is a precursor of the anion part with an onium cation halide corresponding to the onium cation part to proceed with salt exchange, thereby obtaining the target onium salt compound (onium salt compound (1) in the case of the following scheme). [Chemical formula] (In the formula, R 1 , R 2 , R 3 , X 1 , X 2 and Z1 + are synonymous with the above formula (1). M -is a halide ion.)

[0064] Similarly, onium salt compound (1) and onium salt compound (2) having other structures can be synthesized by appropriately selecting the respective precursors corresponding to the anion moiety and the onium cation moiety.)

[0065] (Resin) The resin is an aggregate of polymers having a structural unit containing an acid dissociable group (hereinafter also referred to as "structural unit (I)") (hereinafter, this resin is also referred to as "base resin"). The "acid dissociable group" is a group that substitutes a hydrogen atom of a carboxy group, a phenolic hydroxyl group, an alcoholic hydroxyl group, a sulfo group, etc., and dissociates by the action of an acid. The radiation-sensitive resin composition is excellent in pattern formability because the resin has structural unit (I).

[0066] In addition to structural unit (I), the base resin preferably has a structural unit (II) selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure described later, and may have other structural units other than structural units (I) and (II). Hereinafter, each structural unit will be described.)

[0067] [Structural unit (I)] Structural unit (I) is a structural unit containing an acid dissociable group. Structural unit (I) is not particularly limited as long as it contains an acid dissociable group, and examples thereof include a structural unit having a tertiary alkyl ester moiety, a structural unit having a structure in which a hydrogen atom of a phenolic hydroxyl group is substituted with a tertiary alkyl group, a structural unit having an acetal bond, etc. From the viewpoint of improving the pattern formability of the radiation-sensitive resin composition, the structural unit represented by the following formula (3) (hereinafter also referred to as "structural unit (I-1)") is preferable.)

[0068] [Chemical formula]

[0069] In the above formula (3), R 7is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 8 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R 9 and R 10 each independently represents a monovalent linear hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atom to which they are attached.

[0070] Regarding the above R 7 from the viewpoint of the copolymerizability of the monomer that gives the structural unit (I-1), a hydrogen atom or a methyl group is preferable, and a methyl group is more preferable.

[0071] Regarding the above R 8 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by include a linear hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, and the like.

[0072] Regarding the above R 8 ~R 10 Examples of the linear 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.

[0073] Regarding the above R 8 ~R 10 Examples of the alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by include a monocyclic or polycyclic saturated hydrocarbon group, or a monocyclic or polycyclic unsaturated hydrocarbon group. 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, a bridged alicyclic hydrocarbon group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, and a tetracyclododecyl group is preferable. 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.

[0074] The above R 8 Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by include aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group, anthryl group; aralkyl groups such as benzyl group, phenethyl group, naphthylmethyl group, etc.

[0075] 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.

[0076] 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 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 number of carbon atoms. 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 formed by sharing sides (bonds between two adjacent carbon atoms) of a plurality of alicyclic rings.

[0077] Among the monocyclic alicyclic hydrocarbon groups, preferred saturated hydrocarbon groups include cyclopentanediyl group, cyclohexanediyl group, cycloheptanediyl group, cyclooctanediyl group, etc., and preferred unsaturated hydrocarbon groups include cyclopentenediyl group, cyclohexenediyl group, cycloheptenediyl group, cyclooctenediyl group, cyclodecenediyl group, etc. As the polycyclic alicyclic hydrocarbon group, a bridged alicyclic saturated hydrocarbon group is preferred, for example, bicyclo[2.2.1]heptane-2,2-diyl group (norbornane-2,2-diyl group), bicyclo[2.2.2]octane-2,2-diyl group, tricyclo[3.3.1.1 3,7 decane-2,2-diyl group (adamantane-2,2-diyl group), etc. are preferred.

[0078] Among these, R 8 is an alkyl group having 1 to 4 carbon atoms, and R 9 and R 10 are preferably combined with each other and form a polycyclic or monocyclic cycloalkane structure together with the carbon atom to which they are bonded.

[0079] Examples of the structural unit (I-1) include structural units represented by the following formulas (3-1) to (3-6) (hereinafter, also referred to as "structural units (I-1-1) to (I-1-6)").

[0080]

Chemical formula

[0081] In the above formulas (3-1) to (3-6), R 7 to R 10 have the same meaning as in the above formula (3). i and j are each independently an integer of 1 to 4. k and l are 0 or 1.

[0082] As i and j, 1 is preferable. As R 8 , a methyl group, an ethyl group or an isopropyl group is preferable. As R 9 and R 10 , a methyl group or an ethyl group is preferable.

[0083] The base resin may contain one or a combination of two or more of the structural units (I).

[0084] The content ratio of the structural unit (I) (when including a plurality of types, the total content ratio) is preferably 10 mol% or more, more preferably 20 mol% or more, still more preferably 30 mol% or more, and particularly preferably 35 mol% or more with respect to all the structural units constituting the base resin. Also, it is preferably 80 mol% or less, more preferably 75 mol% or less, still more preferably 70 mol% or less, and particularly preferably 65 mol% or less. By setting the content ratio of the structural unit (I) within the above range, the pattern formability of the radiation-sensitive resin composition can be further improved.

[0085] [Structural unit (II)] The structural unit (II) is a structural unit containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. By further having the structural unit (II), the base resin can adjust its solubility in a developing solution. 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.

[0086] Examples of the structural unit (II) include structural units represented by the following formulas (T-1) to (T-10).

[0087] [Chemical formula]

[0088] In the above formulas, R L1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R L2 to 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.

[0089] Examples of the divalent alicyclic group having 3 to 8 carbon atoms formed together with the carbon atoms to which R L4 and R L5 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 the following formula 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.

[0090] The above L 2 Examples of the divalent linking group represented by the following formula 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-.

[0091] Among these, as the structural unit (II), 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.

[0092] The content ratio of the structural unit (II) is preferably 20 mol% or more, more preferably 25 mol% or more, and even more preferably 30 mol% or more with respect to all the structural units constituting the base resin. Also, it is preferably 80 mol% or less, more preferably 75 mol% or less, and even more preferably 70 mol% or less. By 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.

[0093] [Structural unit (III)] In addition to the above structural units (I) and (II), the base resin may optionally have other structural units. Examples of the other structural units include structural units (III) containing a polar group (excluding those corresponding to structural unit (II)). By further having structural unit (III), the solubility of the base resin in the developer can be adjusted, and as a result, the lithography performance such as the resolution of the radiation-sensitive resin composition can be improved. Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a nitro group, a sulfonamide group, etc. Among these, a hydroxy group and a carboxy group are preferred, and a hydroxy group is more preferred.

[0094] Examples of structural unit (III) include structural units represented by the following formula.

[0095]

Chemical formula

[0096] In the above formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0097] When the base resin has structural unit (III) having the polar group, the content ratio of structural unit (III) is preferably 5 mol% or more, more preferably 8 mol% or more, and even more preferably 10 mol% or more with respect to all the structural units constituting the base resin. Also, it is preferably 40 mol% or less, more preferably 35 mol% or less, and even more preferably 30 mol% or less. By setting the content ratio of structural unit (III) within the above range, the lithography performance such as the resolution of the radiation-sensitive resin composition can be further improved.

[0098] [Structural unit (IV)] The base resin, as other structural units, may optionally have a structural unit derived from hydroxystyrene or a structural unit having a phenolic hydroxyl group (hereinafter, both are also collectively referred to as "structural unit (IV)") in addition to the structural unit (III) having the above polar group. The structural unit (IV) 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 preferably applied to pattern formation using exposure with radiation having a wavelength of 50 nm or less, such as an electron beam or EUV. In this case, the resin preferably has the structural unit (I) together with the structural unit (IV).

[0099] In this case, at the time of polymerization, 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 to perform hydrolysis for deprotection to obtain the structural unit (IV). As the structural unit that gives the structural unit (IV) by hydrolysis, it is preferably represented by the following formulas (4-1) and (4-2).

[0100]

Chemical formula

[0101] In the above formulas (4-1) and (4-2), R 11 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 12 is a monovalent hydrocarbon group or an alkoxy group having 1 to 20 carbon atoms. Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms of R 12 include the monovalent hydrocarbon group having 1 to 20 carbon atoms of R 8 in the structural unit (I). Examples of the alkoxy group include a methoxy group, an ethoxy group, and a tert-butoxy group.

[0102] As the above R 12 , an alkyl group and an alkoxy group are preferable, and among them, a methyl group and a tert-butoxy group are more preferable.

[0103] In the case of a resin for exposure with radiation having a wavelength of 50 nm or less, the content ratio of the structural unit (IV) is preferably 10 mol% or more, more preferably 20 mol% or more, based on all the structural units constituting the resin. Further, it is preferably 70 mol% or less, more preferably 60 mol% or less.

[0104] (Synthesis method of the base resin) The base resin can be synthesized, for example, by polymerizing monomers that provide each structural unit in a suitable solvent using a radical polymerization initiator or the like.

[0105] 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), dimethyl 2,2'-azobisisobutyrate; peroxide-based radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, etc. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred, and AIBN is more preferred. These radical initiators can be used alone or in combination of two or more.

[0106] Examples of the solvent used in the polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane; cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene; halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, chlorobenzene; saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate, methyl propionate; Ketones such as acetone, methyl ethyl ketone, 4-methyl-2-pentanone, 2-heptanone; Ethers such as tetrahydrofuran, dimethoxyethanes, diethoxyethanes; Alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2-pentanol, etc. may be mentioned. The solvents used for this polymerization may be used singly or in combination of two or more.

[0107] As the reaction temperature in the above polymerization, 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.

[0108] The molecular weight of the base resin is not particularly limited, but the polystyrene-equivalent weight average molecular weight (Mw) by gel permeation chromatography (GPC) is preferably 1,000 or more and 50,000 or less, more preferably 2,000 or more and 30,000 or less, still more preferably 3,000 or more and 15,000 or less, and particularly preferably 4,000 or more and 12,000 or less. If the Mw of the base resin is less than the above lower limit, the heat resistance of the resulting resist film may decrease. If the Mw of the base resin exceeds the above upper limit, the developability of the resist film may decrease.

[0109] The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of 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.

[0110] The Mw and Mn of the resin in this specification are values measured using gel permeation chromatography (GPC) under the following conditions.

[0111] GPC column: 2 columns of G2000HXL, 1 column of G3000HXL, 1 column of G4000HXL (all manufactured by Tosoh) Column temperature: 40°C Elution solvent: Tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0 mass% Sample injection volume: 100 μL Detector: Differential refractometer Standard substance: Monodisperse polystyrene

[0112] As the content ratio of the base resin, 70 mass% or more, more preferably 80 mass% or more, and even more preferably 85 mass% or more, is preferable with respect to the total solid content of the radiation-sensitive resin composition.

[0113] (Other resin) The radiation-sensitive resin composition of the present embodiment may contain, as another resin, a resin having a higher mass content ratio of fluorine atoms than the above base resin (hereinafter, also referred to as "high-fluorine content resin"). When the radiation-sensitive resin composition contains a high-fluorine content resin, it can be unevenly distributed on the surface layer of the resist film with respect to the base resin, and as a result, the water repellency of the surface of the resist film during immersion exposure can be enhanced.

[0114] The high-fluorine content resin preferably has, for example, a structural unit represented by the following formula (5) (hereinafter, also referred to as "structural unit (V)"), and may have structural unit (I) or structural unit (II) in the above base resin as necessary.

[0115] [Chemical formula]

[0116] In the above formula (5), R 13 is a hydrogen atom, a methyl group or a trifluoromethyl group. G L is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2ONH-, -CONH- or -OCONH-. R 14 is a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0117] The above R 13From the viewpoint of the copolymerizability of the monomer that provides the structural unit (V), a hydrogen atom and a methyl group are preferable, and a methyl group is more preferable.

[0118] The above G L From the viewpoint of the copolymerizability of the monomer that provides the structural unit (V), a single bond and -COO- are preferable, and -COO- is more preferable.

[0119] The above R 14 Examples of the monovalent fluorinated chain hydrocarbon group represented by the above R having 1 to 20 carbon atoms include those in which 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.

[0120] The above R 14 Examples of the monovalent fluorinated alicyclic hydrocarbon group represented by the above R having 3 to 20 carbon atoms include those in which 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.

[0121] The above R 14 As the above R, a fluorinated chain hydrocarbon group is preferable, a fluorinated alkyl group is more preferable, and a 2,2,2-trifluoroethyl group, a 1,1,1,3,3,3-hexafluoropropyl group, and a 5,5,5-trifluoro-1,1-diethylpentyl group are even more preferable.

[0122] When the high fluorine content resin has the structural unit (V), the content ratio of the structural unit (V) is preferably 30 mol% or more, more preferably 40 mol% or more, even more preferably 45 mol% or more, and particularly preferably 50 mol% or more with respect to all the structural units constituting the high fluorine content resin. Also, it is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less. By setting the content ratio of the structural unit (V) within the above range, the mass content ratio of fluorine atoms in the high fluorine content resin can be adjusted more appropriately to further promote the uneven distribution on the surface layer of the resist film. As a result, the water repellency of the resist film during immersion exposure can be further improved.

[0123] The high fluorine content resin may have a fluorine atom-containing structural unit represented by the following formula (f-2) (hereinafter also referred to as structural unit (VI)) together with or in place of the structural unit (V). By having the structural unit (f-2), the high fluorine content resin can improve its solubility in an alkaline developer and suppress the occurrence of development defects.

[0124]

Chemical formula

[0125] The structural unit (VI) 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 solubility in an alkaline developer (hereinafter also simply referred to as an "alkali dissociable group"). Commonly to both (x) and (y), in the above formula (f-2), R C is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R D is a single bond, a (s + 1)-valent hydrocarbon group having 1 to 20 carbon atoms, an oxygen atom, a sulfur atom, -NR E - bonded to the end on the R dd side of this hydrocarbon group, a carbonyl group, -COO- or -CONH-, or a structure in which a part of the hydrogen atoms of this hydrocarbon group is substituted by 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.

[0126] When the structural unit (VI) has an (x) alkali-soluble group, R F is a hydrogen atom, and A 1 is an oxygen atom, -COO-* or -SO2O-*. * indicates the bonding site to R F . W 1 is a single bond, a hydrocarbon group having 1 to 20 carbon atoms or a divalent fluorinated hydrocarbon group. When A 1 is an oxygen atom, W 1 is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group on the carbon atom to which A 1 is bonded. R Eis a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, a plurality of R E , W 1 , A 1 and R F may be the same or different from each other. By having the structural unit (VI) with (x) an alkali-soluble group, the affinity for an alkali developer can be increased, and development defects can be suppressed. As the structural unit (VI) having (x) an alkali-soluble group, when A 1 is an oxygen atom and W 1 is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group, it is particularly preferable.

[0127] When the structural unit (VI) has (y) an alkali-dissociable group, R F is a monovalent organic group having 1 to 30 carbon atoms, A 1 is an oxygen atom, -NR aa -, -COO-*, or -SO2O-*. R aa is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * indicates the bonding site to R F . W 1 is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R E is a single bond or a divalent organic group having 1 to 20 carbon atoms. When A 1 is -COO-* or -SO2O-*, W 1 or R F has a fluorine atom on the carbon atom bonded to A 1 or the carbon atom adjacent thereto. When A 1 is an oxygen atom, W 1 , R E is a single bond, R D is a structure in which a carbonyl group is bonded to the end on the R E side of a hydrocarbon group having 1 to 20 carbon atoms, and R F is an organic group having a fluorine atom. When s is 2 or 3, a plurality of R E , W 1 , A 1 and R FThey may be the same or different. Since the structural unit (VI) has a (y) alkali-dissociable group, the surface of the resist film changes from hydrophobic to hydrophilic in the alkali development process. As a result, the affinity for the developer is significantly increased, and development defects can be suppressed more efficiently. As the structural unit (VI) having a (y) alkali-dissociable group, A 1 is -COO-*, and R F or W 1 or both of them having a fluorine atom are particularly preferred.

[0128] R C From the viewpoint of copolymerizability of the monomer that gives the structural unit (VI), a hydrogen atom and a methyl group are preferred, and a methyl group is more preferred.

[0129] 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.

[0130] When the high fluorine content resin has the structural unit (VI), the content ratio of the structural unit (VI) is preferably 40 mol% or more, more preferably 50 mol% or more, and still more preferably 60 mol% or more with respect to all the structural units constituting the high fluorine content resin. Also, 95 mol% or less is preferred, 90 mol% or less is more preferred, and 85 mol% or less is still more preferred. By setting the content ratio of the structural unit (VI) within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0131] [Other Structural Units] The high fluorine content resin may contain, as structural units other than the above-listed structural units, a structural unit having an alicyclic structure represented by the following formula (6). [Chemical Formula] (In the above formula (6), R 1α is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 2αis a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.)

[0132] In the above formula (6), R 2α As the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by, the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R in the above formula (1) can be preferably adopted. 8

[0133] When the high fluorine content resin contains a structural unit having the above alicyclic structure, the lower limit of the content ratio of the structural unit having the above alicyclic structure is preferably 10 mol%, more preferably 20 mol%, and further preferably 30 mol% with respect to all the structural units constituting the high fluorine content resin. The upper limit of the above content ratio is preferably 70 mol%, more preferably 60 mol%, and further preferably 50 mol%.

[0134] The lower limit of Mw of the high fluorine content resin is preferably 1,000, more preferably 2,000, further preferably 3,000, and particularly preferably 5,000. The upper limit of the above Mw is preferably 50,000, more preferably 30,000, further preferably 20,000, and particularly preferably 15,000.

[0135] The lower limit of Mw / Mn of the high fluorine content resin is usually 1, and more preferably 1.1. The upper limit of the above Mw / Mn is usually 5, preferably 3, more preferably 2, and further preferably 1.9.

[0136] The content of the high fluorine content resin is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, further preferably 1 part by mass or more, and particularly preferably 1.5 part by mass or more with respect to 100 parts by mass of the above base resin. Also, 15 parts by mass or less is preferable, 10 parts by mass or less is more preferable, 8 parts by mass or less is further preferable, and 5 parts by mass or less is particularly preferable.

[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 water repellency of the surface of the resist film during immersion exposure can be further enhanced. The 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 the same method as the synthesis method of the above base resin.

[0139] (Radiation-sensitive acid generator) The radiation-sensitive resin composition of the present embodiment preferably further contains a radiation-sensitive acid generator that generates an acid having a pKa smaller than that of the acid generated from the above-mentioned onium salt compound, that is, a relatively strong acid, upon irradiation (exposure) of radiation. When the resin contains a structural unit (I) having an acid dissociable group, the acid generated from the radiation-sensitive acid generator upon exposure can dissociate the acid dissociable group of the structural unit (I) to generate a carboxy group or the like. This function is different from the function of the above-mentioned onium salt compound that suppresses the diffusion of the acid generated from the radiation-sensitive acid generator in the unexposed portion without substantially dissociating the acid dissociable group or the like of the structural unit (I) of the resin under the pattern formation conditions using the above radiation-sensitive resin composition. The difference in the functions of the above-mentioned onium salt compound and the radiation-sensitive acid generator is determined by the energy required for the acid dissociable group of the structural unit (I) of the resin to dissociate and the thermal energy conditions given when forming a pattern using the radiation-sensitive resin composition. As the form of the radiation-sensitive acid generator in the radiation-sensitive resin composition, it may be present as a compound alone (released from the polymer), incorporated as a part of the polymer, or both of these forms, but the form present as a compound alone is preferred.

[0140] When the radiation-sensitive resin composition contains the above radiation-sensitive acid generator, the polarity of the resin in the exposed area increases, and the resin in the exposed area becomes soluble in the developer in the case of alkali aqueous solution development, while it becomes hardly soluble in the developer in the case of organic solvent development.

[0141] Examples of the radiation-sensitive acid generator include onium salt compounds (excluding the above onium salt compounds (1) and (2)), sulfonimide compounds, halogen-containing compounds, diazoketone compounds, etc. Examples of the onium salt compound include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, etc. Among these, sulfonium salts and iodonium salts are preferable.

[0142] Examples of the acid generated by exposure include those that generate sulfonic acid by exposure. Examples of such acids include compounds in which one or more fluorine atoms or fluorinated hydrocarbon groups are substituted on the carbon atom adjacent to the sulfonic group. Among them, those having a cyclic structure are particularly preferable as the radiation-sensitive acid generator.

[0143] These radiation-sensitive acid generators may be used alone or in combination of two or more. The content of the radiation-sensitive acid generator is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, still more preferably 5 part by mass or more, based on 100 parts by mass of the base resin. Also, based on 100 parts by mass of the resin, 40 parts by mass or less is preferable, 35 parts by mass or less is more preferable, 30 parts by mass or less is still more preferable, and 20 parts by mass or less is particularly preferable. Thereby, excellent sensitivity, CDU performance, and LWR performance can be exhibited during resist pattern formation.

[0144] (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 onium salt compound (1) and / or (2), the resin, and the radiation-sensitive acid generator and the like contained as desired.

[0145] Examples of the solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents, and the like.

[0146] Examples of the alcohol solvents include monohydric alcohol solvents having 1 to 18 carbon atoms such as iso-propanol, 4-methyl-2-pentanol, 3-methoxybutanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, and diacetone alcohol; polyhydric alcohol solvents having 2 to 18 carbon atoms such as ethylene glycol, 1,2-propylene glycol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; polyhydric alcohol partial ether solvents in which a part of the hydroxy groups of the above polyhydric alcohol solvents are etherified, and the like.

[0147] Examples of the ether solvents include dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether; cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; aromatic ring-containing ether solvents such as diphenyl ether and anisole (methyl phenyl ether); polyhydric alcohol ether solvents in which the hydroxy groups of the above polyhydric alcohol solvents are etherified, and the like.

[0148] Examples of the ketone solvents include chain ketone solvents such as acetone, butanone, and methyl-iso-butyl ketone: cyclic ketone solvents such as cyclopentanone, cyclohexanone, and methylcyclohexanone: 2,4-pentanedione, acetonylacetone, acetophenone, and the like.

[0149] Examples of amide solvents include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0150] Examples of ester solvents include, for example, monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate; polyhydric alcohol partial ether acetate solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; lactone solvents such as γ-butyrolactone and valerolactone; carbonate solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; polycarboxylic acid diester solvents such as propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, ethyl lactate, and diethyl phthalate.

[0151] Examples of hydrocarbon solvents include, for example aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; aromatic hydrocarbon solvents such as benzene, toluene, di-iso-propylbenzene, and n-amylnaphthalene.

[0152] 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.

[0153] (Other optional components) In addition to the above components, the radiation-sensitive resin composition may contain other optional components. Examples of the other optional components include crosslinking agents, phase separation accelerators, surfactants, alicyclic skeleton-containing compounds, sensitizers, and the like. These other optional components may be used alone or in combination of two or more thereof.

[0154] (Crosslinking agent) A crosslinking agent is a compound having two or more functional groups. In the baking step after the batch exposure step, it causes a crosslinking reaction in the resin component by an acid-catalyzed reaction, increases the molecular weight of the resin component, and thereby reduces the solubility of the pattern-exposed portion in the developer. Examples of the functional group include (meth)acryloyl group, hydroxymethyl group, alkoxymethyl group, epoxy group, vinyl ether group, and the like.

[0155] (Phase separation accelerator) The phase separation accelerator has the effect of more efficiently causing the high-fluorine content resin to be phase-separated on the resist film surface. By including this phase separation accelerator in the radiation-sensitive resin composition, the addition amount of the high-fluorine content resin can be made less than before. Therefore, while maintaining the lithography performance of the radiation-sensitive resin composition, elution of components from the resist film into the immersion medium can be further suppressed, or immersion exposure can be performed at a higher speed by high-speed scanning, and as a result, the hydrophobicity of the resist film surface that suppresses immersion-derived defects such as watermark defects can be improved. Examples of those that can be used as such a phase separation accelerator include 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, and the like.

[0156] Examples of the lactone compound include γ-butyrolactone, valerolactone, mevalonic lactone, norbornane lactone, and the like.

[0157] Examples of the carbonate compound include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, and the like.

[0158] Examples of the nitrile compound include succinonitrile and the like.

[0159] Examples of the polyhydric alcohol include glycerin and the like.

[0160] The content of the uneven distribution promoter is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, still more preferably 20 parts by mass or more, and even more preferably 25 parts by mass or more, with respect to 100 parts by mass of the total amount of the resin in the radiation-sensitive resin composition. Further, it is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, still more preferably 100 parts by mass or less, and particularly preferably 80 parts by mass or less. The radiation-sensitive resin composition may contain one or more uneven distribution promoters.

[0161] (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-octyl phenyl ether, polyoxyethylene n-nonyl phenyl 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), F-Top EF301, EF303, EF352 (manufactured by Tochem Products for all), Megafac F171, F173 (manufactured by DIC for both), Fluorad FC430, FC431 (manufactured by Sumitomo 3M 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.

[0162] (alicyclic skeleton-containing compound) The alicyclic skeleton-containing compound has the effect of improving dry etching resistance, pattern shape, adhesion to the substrate, etc.

[0163] 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.

[0164] (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.

[0165] 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.

[0166] <Method for preparing a radiation-sensitive resin composition> The above radiation-sensitive resin composition can be prepared, for example, by mixing an onium salt compound (1) and / or (2), a resin, a radiation-sensitive acid generator, a high fluorine content resin, etc. as required, and a solvent at 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 to 0.2 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.

[0167] <Pattern formation method> The pattern formation method according to one embodiment of the present invention is A step (1) of forming a resist film by applying the above-described radiation-sensitive resin composition directly or indirectly on a substrate (hereinafter, also referred to as "resist film formation step") A step (2) of exposing the above resist film (hereinafter, also referred to as "exposure step") And a step (3) of developing the exposed resist film (hereinafter, also referred to as "development step").

[0168] According to the above resist pattern forming method, since the above-described radiation-sensitive resin composition excellent in sensitivity, CDU performance, and LWR performance in the exposure step is used, a high-quality resist pattern can be formed. Hereinafter, each step will be described.

[0169] [Resist Film Formation Step] In this step (the above step (1)), a resist film is formed using the above-described 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 Unexamined Patent Application Publication 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.

[0170] When performing liquid immersion exposure, regardless of the presence or absence of a water-repellent polymer additive such as the high-fluorine content resin in the radiation-sensitive resin composition, for the purpose of avoiding direct contact between the liquid immersion liquid and the resist film, a liquid immersion protective film insoluble in the liquid immersion liquid may be provided on the formed resist film. As the liquid immersion protective film, a solvent peelable protective film that is peeled off with a solvent before the development process (see, for example, Japanese Patent Application Laid-Open No. 2006-227632), or a developer peelable protective film that is peeled off simultaneously with the development in the development process (see, for example, WO2005-069076, WO2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer peelable liquid immersion protective film.

[0171] Further, when the exposure process, which is the next process, is performed with radiation having a wavelength of 50 nm or less, it is preferable to use a resin having the structural unit (I) and the structural unit (IV) as the base resin in the composition.

[0172] [Exposure Process] In this process (the above process (2)), the resist film formed in the resist film forming process, which is the above process (1), is irradiated with radiation through a photomask (in some cases, through a liquid immersion medium such as water) for exposure. As the radiation used for exposure, depending on the line width of the target pattern, for example, electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet light), X-rays, γ-rays; charged particle beams such as electron beams, α-rays, etc. can be mentioned. Among these, far 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.

[0173] When performing exposure by liquid immersion exposure, examples of the liquid immersion liquid to be used include water, fluorine-based inert liquids, etc. The liquid immersion liquid is preferably a liquid that is transparent to the exposure light wavelength and has a temperature coefficient of refractive index as small as possible so as to minimize the distortion of the optical image projected onto the film. However, particularly 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 activity may be added in a small proportion. This additive is preferably one that does not dissolve the resist film on the wafer and has a negligible effect on the optical coat on the lower surface of the lens. Distilled water is preferred as the water to be used.

[0174] After the above exposure, post-exposure baking (PEB) is performed, and in the exposed portion of the resist film, it is preferable to promote the dissociation of the acid-dissociable groups of the resin, etc. by the acid generated from the radiation-sensitive acid generator by exposure. 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, and preferably 80°C to 130°C. The PEB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.

[0175] [Development process] In this step (the above step (3)), the resist film exposed in the above exposure step, which is 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.

[0176] As the developing solution used for the above development, in the case of alkaline development, for example, an alkaline aqueous solution in which at least one kind of alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, 1,5-diazabicyclo-[4.3.0]-5-nonene is dissolved can be mentioned. Among these, an aqueous TMAH solution is preferable, and a 2.38 mass% aqueous TMAH solution is more preferable.

[0177] In addition, in the case of organic solvent development, organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, or solvents containing an organic solvent can be mentioned. As the above organic solvent, for example, one or more of the solvents listed as the solvent of the above radiation-sensitive resin composition can be mentioned. Among these, ether solvents, ester solvents, and ketone solvents are preferable. As the ether solvent, a glycol ether solvent is preferable, and ethylene glycol monomethyl ether and propylene glycol monomethyl ether are more preferable. As the ester solvent, an acetate 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 developing solution is preferably 80 mass% or more, more preferably 90 mass% or more, further preferably 95 mass% or more, and particularly preferably 99 mass% or more. As components other than the organic solvent in the developing solution, for example, water, silicone oil, etc. can be mentioned.

[0178] As described above, the developing solution may be either an alkaline developing solution or an organic solvent developing solution, but it is preferable that the above developing solution contains an organic solvent and the obtained pattern is a negative pattern.

[0179] As developing methods, for example, there can be mentioned 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), etc.

Example

[0180] 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.

[0181] [Weight average molecular weight (Mw) and number average molecular weight (Mn)] The Mw and Mn of the polymer were measured under the above-described conditions. Also, the dispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[0182] 13 C-NMR analysis] For the polymer 13 C-NMR analysis was performed using a nuclear magnetic resonance apparatus (“JNM-Delta400” manufactured by JEOL Ltd.).

[0183] (Synthesis of resin and high fluorine content resin) The monomers used in the synthesis of each resin and high fluorine content resin in each example and each comparative example are shown below. In the following synthesis examples, unless otherwise specified, parts by mass mean values when the total mass of the monomers used is 100 parts by mass, and mol% means values when the total number of moles of the monomers used is 100 mol%.

[0184]

Chemical formula

[0185] [Synthesis Example 1] (Synthesis of resin (A-1)) ​The monomer (M-1), monomer (M-2), and monomer (M-13) were dissolved in 2-butanone (200 parts by mass) such that the molar ratio was 40 / 15 / 45 (mol %), and AIBN (azobisisobutyronitrile) (3 mol % with respect to 100 mol % of the total monomers used) was added as an initiator to prepare a monomer solution. 2-Butanone (100 parts by mass) was placed in a reaction vessel and purged with nitrogen for 30 minutes. Then, the inside of the reaction vessel was set to 80°C, and the above monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled with water to a temperature of 30°C or lower. The cooled polymerization solution was poured into methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with methanol, then filtered again, and dried at 50°C for 24 hours to obtain a white powder resin (A-1) (yield: 83%). The Mw of resin (A-1) was 8,800, and Mw / Mn was 1.50. Also, 13 As a result of C-NMR analysis, the content ratios of the respective structural units derived from (M-1), (M-2), and (M-13) were 41.3 mol %, 13.8 mol %, and 44.9 mol %, respectively.

[0186] [Synthesis Examples 2 to 11] (Synthesis of Resins (A-2) to (A-11)) Resins (A-2) to (A-11) were synthesized in the same manner as in Synthesis Example 1, except that monomers of the types and blending ratios shown in Table 1 below were used. The content ratios (mol %) of the respective structural units, yields (%), and physical property values (Mw and Mw / Mn) of the obtained resins are also shown in Table 1 below. Note that "-" in Table 1 below indicates that the corresponding monomer was not used (the same applies to the subsequent tables).

[0187]

Table 1

[0188] [Synthesis Example 12] (Synthesis of Resin (A-12)) The monomer (M-1) and the monomer (M-18) were dissolved in 1-methoxy-2-propanol (200 parts by mass) so that the molar ratio was 50 / 50 (mol%). AIBN (5 mol%) was added as an initiator to prepare a monomer solution. 1-Methoxy-2-propanol (100 parts by mass) was placed in a reaction vessel and purged with nitrogen for 30 minutes. Then, the inside of the reaction vessel was set to 80°C, and the above monomer solution was added dropwise over 3 hours with stirring. The start of the dropping was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled with water to 30°C or lower. The cooled polymerization solution was poured into hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane, then filtered and dissolved in 1-methoxy-2-propanol (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and a hydrolysis reaction was carried out at 70°C for 6 hours with stirring. After the reaction was completed, the residual solvent was distilled off, and the obtained solid was dissolved in acetone (100 parts by mass) and dropped into water (500 parts by mass) to solidify the resin. The obtained solid was filtered and dried at 50°C for 13 hours to obtain a white powdery resin (A-12) (yield: 79%). The Mw of the resin (A-12) was 5,200, and Mw / Mn was 1.60. Also, 13 As a result of C-NMR analysis, the content ratios of the respective structural units derived from (M-1) and (M-18) were 51.3 mol% and 48.7 mol%, respectively.

[0189] [Synthesis Examples 13 to 15] (Synthesis of Resins (A-13) to (A-15)) Resins (A-13) to (A-15) were synthesized in the same manner as in Synthesis Example 12, except that monomers of the types and blending ratios shown in Table 2 below were used. The content ratios (mol%) of the respective structural units, the yields (%), and the physical property values (Mw and Mw / Mn) of the obtained resins are also shown in Table 2 below.

[0190]

Table 2

[0191] [Synthesis Example 16] (Synthesis of High-Fluorine Content Resin (E-1)) Monomer (M-1) and monomer (M-20) were dissolved in 2-butanone (200 parts by mass) such that the molar ratio was 20 / 80 (mol%), and AIBN (4 mol%) was added as an initiator to prepare a monomer solution. 2-Butanone (100 parts by mass) was placed in a reaction vessel and purged with nitrogen for 30 minutes. Then, the inside of the reaction vessel was set to 80°C, and the above monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was taken as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled with water to 30°C or lower. After replacing the solvent with acetonitrile (400 parts by mass), hexane (100 parts by mass) was added and stirred, and the operation of recovering the acetonitrile layer was repeated 3 times. By replacing the solvent with propylene glycol monomethyl ether acetate, a solution of high-fluorine content resin (E-1) was obtained (yield: 69%). The Mw of the high-fluorine content resin (E-1) was 6,000, and Mw / Mn was 1.62. Also, 13 As a result of C-NMR analysis, the content ratios of the respective structural units derived from (M-1) and (M-20) were 19.9 mol% and 80.1 mol%, respectively.

[0192] [Synthesis Examples 17 to 20] (Synthesis of High-Fluorine Content Resins (E-2) to High-Fluorine Content Resin (E-5)) High-fluorine content resins (E-2) to high-fluorine content resin (E-5) were synthesized in the same manner as in Synthesis Example 16 except that monomers of the types and blending ratios shown in Table 3 below were used. The content ratios (mol%) of the respective structural units, yields (%), and physical property values (Mw and Mw / Mn) of the obtained high-fluorine content resins are shown together in Table 3 below.

[0193]

Table 3

[0194] (Synthesis of Acid Diffusion Controller C) [Synthesis Example 21] (Synthesis of Onium Salt Compound (C-1)) The onium salt compound (C-1) was synthesized according to the following synthetic scheme.

[0195] [Chemical formula]

[0196] 20.0 mmol of 5-(trifluoromethyl)uracil, 20.0 mmol of sodium hydrogen carbonate, and 20.0 mmol of triphenylsulfonium bromide were added to a reaction vessel, and a mixed solution of water:dichloromethane (1:1 (mass ratio)) was added to make a 0.5 M solution. After vigorously stirring at room temperature for 3 hours, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was dried over sodium sulfate, the solvent was distilled off, and purification by column chromatography gave the onium salt compound (C-1) represented by the above formula (C-1) in good yield.

[0197] [Synthesis Examples 22 to 35] (Synthesis of onium salt compounds (C-2) to (C-15)) Onium salt compounds represented by the following formulas (C-2) to (C-15) were synthesized in the same manner as in Synthesis Example 21 except that the raw materials and precursors were appropriately changed. Note that onium salt compounds (C-1) to (C-11) correspond to onium salt compound (1), and onium salt compounds (C-12) to (C-15) correspond to onium salt compound (2).

[0198] [Chemical formula]

[0199] [Acid diffusion control agents other than onium salt compounds (C-1) to (C-15)] cc-1 to cc-5: Compounds represented by the following formulas (cc-1) to (cc-5) (hereinafter, the compounds represented by formulas (cc-1) to (cc-5) may be referred to as "compound (cc-1)" to "compound (cc-5)", respectively).

[0200] [Chemical formula]

[0201] [[B] Radiation-sensitive acid generator] B-1 to B-6: Compounds represented by the following formulas (B-1) to (B-6) (hereinafter, the compounds represented by formulas (B-1) to (B-6) may be referred to as "Compound (B-1)" to "Compound (B-6)", respectively).)

[0202] [Chemical formula]

[0203] [[D] Solvent] D-1: Propylene glycol monomethyl ether acetate D-2: Cyclohexanone D-3: γ-Butyrolactone D-4: Ethyl lactate

[0204] [Preparation of negative-type radiation-sensitive resin composition for ArF lithography] [Example 1] [(A-1) 100 parts by mass as resin, (B-1) 12.0 parts by mass as radiation-sensitive acid generator, (C-1) 3.0 parts by mass as acid diffusion controller, (E-1) 3.0 parts by mass (solid content) as high fluorine content resin, and 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) as [D] solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-1).]

[0205] [Examples 2 to 42 and Comparative Examples 1 to 5] [Except for using each component of the types and contents shown in Table 4 below, in the same manner as in Example 1, radiation-sensitive resin compositions (J-2) to (J-42) and (CJ-1) to (CJ-5) were prepared.]

[0206] [Table 4]

[0207] <Formation of Resist Pattern Using Negative-Type Radiation-Sensitive Resin Composition for ArF Exposure> On a 12-inch silicon wafer, using a spin coater ("CLEAN TRACK ACT12" manufactured by Tokyo Electron Limited), a composition for forming an underlying antireflection film ("ARC66" manufactured by Brewer Science, Inc.) was applied, and then heated at 205°C for 60 seconds to form an underlying antireflection film with an average thickness of 100 nm. On this underlying antireflection film, the prepared negative-type radiation-sensitive resin composition for ArF exposure was applied using the above spin coater, and PB (pre-bake) was performed at 100°C for 60 seconds. Then, by cooling at 23°C for 30 seconds, a resist film with an average thickness of 90 nm was formed. Next, for this resist film, using an ArF excimer laser immersion exposure apparatus ("TWINSCAN XT-1900i" manufactured by ASML), under optical conditions of NA = 1.35 and Dipole (σ = 0.9 / 0.7), exposure was performed through a mask pattern of 40 nm line and space. After exposure, PEB (post-exposure bake) was performed at 100°C for 60 seconds. Then, using n-butyl acetate as an organic solvent developer, the above resist film was developed with an organic solvent and dried to form a negative-type resist pattern (40 nm hole, 105 nm pitch).

[0208] <Evaluation> Regarding the resist pattern formed using the above negative-type radiation-sensitive resin composition for ArF exposure, sensitivity and CDU performance were evaluated according to the following methods. The results are shown in Table 5 below. For measuring the length of the resist pattern, a scanning electron microscope ("CG-5000" manufactured by Hitachi High-Technologies Corporation) was used.

[0209] [Sensitivity] In the formation of the resist pattern using the above negative-type radiation-sensitive resin composition for ArF exposure, the exposure amount for forming a 40 nm hole pattern was defined as the optimum exposure amount, and this optimum exposure amount was defined as the sensitivity (mJ / cm 2 ). The sensitivity is considered "good" when it is 25 mJ / cm 2 or less, and 25 mJ / cm 2When it exceeded, it was evaluated as "defective".

[0210] [CDU performance] For a resist pattern with 40 nm holes and a 105 nm pitch, 1,800 measurements were taken at arbitrary points from the top of the pattern using the above scanning electron microscope. The variation (3σ) in dimensions was determined and taken 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 it is. When the CDU performance was 3.0 nm or less, it was evaluated as "good", and when it exceeded 3.0 nm, it was evaluated as "defective".

[0211]

Table 5

[0212] As is clear from the results in Table 5, the radiation-sensitive resin composition of the example had good sensitivity and CDU performance when used for ArF exposure, while in the comparative examples, each characteristic was inferior to that of the example. Therefore, when the radiation-sensitive resin composition of the example is used for ArF exposure, a resist pattern with high sensitivity and good CDU performance can be formed.

[0213] [Preparation of positive-type radiation-sensitive resin composition for extreme ultraviolet (EUV) exposure] [Example 43] [A] 100 parts by mass of (A-12) as a resin, [B] 15.0 parts by mass of (B-3) as a radiation-sensitive acid generator, [C] 3.0 parts by mass of (C-1) as an acid diffusion controller, [E] 3.0 parts by mass (solid content) of (E-5) as a high fluorine content resin, and 6,110 parts by mass of a mixed solvent of (D-1) / (D-4) as [D] a solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-43).

[0214] [Examples 44 to 53 and Comparative Examples 6 to 9] Except for using the components of the types and contents shown in Table 6 below, radiation-sensitive resin compositions (J-44) to (J-53) and (CJ-6) to (CJ-9) were prepared in the same manner as in Example 43.

[0215]

Table 6

[0216] <Formation of Resist Pattern Using EUV Exposure Positive-Type Radiation-Sensitive Resin Composition> On a 12-inch silicon wafer, using a spin coater ("CLEAN TRACK ACT12" manufactured by Tokyo Electron Limited), a composition for forming an underlying antireflective film ("ARC66" manufactured by Brewer Science, Inc.) was applied, and then heated at 205 °C for 60 seconds to form an underlying antireflective film with an average thickness of 105 nm. On this underlying antireflective film, the above-prepared EUV exposure positive-type radiation-sensitive resin composition was applied using the above spin coater, and PB was performed at 130 °C for 60 seconds. Then, by cooling at 23 °C for 30 seconds, a resist film with an average thickness of 55 nm was formed. Next, this resist film was exposed using an EUV exposure apparatus ("NXE3300" manufactured by ASML) with NA = 0.33, illumination condition: Conventional s = 0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120 °C for 60 seconds. Then, the resist film was alkali-developed using a 2.38 mass% aqueous solution of tetramethylammonium hydroxide (TMAH) as an alkali developer, washed with water after development, and further dried to form a positive-type resist pattern (32 nm line and space pattern).

[0217] <Evaluation> Regarding the resist pattern formed using the above EUV exposure positive-type radiation-sensitive resin composition, the sensitivity and LWR performance were evaluated according to the following methods. The results are shown in Table 7 below. For the length measurement of the resist pattern, a scanning electron microscope ("CG-5000" manufactured by Hitachi High-Technologies Corporation) was used.

[0218] [Sensitivity] In the formation of a resist pattern using the above positive radiation-sensitive resin composition for EUV lithography, the exposure dose for forming a 32 nm line-and-space pattern was defined as the optimum exposure dose, and this optimum exposure dose was defined as the sensitivity (mJ / cm 2 ²). When the sensitivity was 30 mJ / cm 2 or less, it was evaluated as "good", and when it exceeded 30 mJ / cm 2 , it was evaluated as "bad".

[0219] [LWR Performance] The mask size was adjusted to form a 32 nm line-and-space pattern by irradiating the optimum exposure dose obtained in the above sensitivity evaluation, and a resist pattern was formed. The formed resist pattern was observed from above the pattern using the above scanning electron microscope. The variation in line width was measured at 500 points in total, and the 3-sigma value was obtained from the distribution of the measured values, and this 3-sigma value was defined as LWR (nm). The smaller the value of LWR, the smaller the line wobbling and the better the performance. When the LWR performance was 3.0 nm or less, it was evaluated as "good", and when it exceeded 3.0 nm, it was evaluated as "bad".

[0220]

Table 7

[0221] As is clear from the results in Table 7, the radiation-sensitive resin composition of the example had good sensitivity and LWR performance when used for EUV lithography, whereas in the comparative example, each characteristic was inferior to that of the example.

[0222] [Preparation of a Positive Radiation-Sensitive Resin Composition for ArF Lithography, Formation and Evaluation of a Resist Pattern Using this Composition] [Example 54] 100 parts by mass of (A-5) as a resin, 12.0 parts by mass of (B-1) as a radiation-sensitive acid generator, 2.0 parts by mass of (C-1) as an acid diffusion controller, 3.0 parts by mass (solid content) of (E-2) as a high fluorine content resin, and 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) as a solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-54).

[0223] On a 12-inch silicon wafer, using a spin coater ("CLEAN TRACK ACT12" of Tokyo Electron Limited), after applying a composition for forming an underlying antireflection film ("ARC66" of Brewer Science), it was heated at 205°C for 60 seconds to form an underlying antireflection film with an average thickness of 100 nm. On this underlying antireflection film, the prepared positive-type radiation-sensitive resin composition (J-54) for ArF exposure was applied using the above spin coater, and PB (pre-bake) was performed at 100°C for 60 seconds. Then, by cooling at 23°C for 30 seconds, a resist film with an average thickness of 90 nm was formed. Next, for this resist film, using an ArF excimer laser immersion exposure apparatus ("TWINSCAN XT-1900i" of ASML), under optical conditions of NA = 1.35, Annular (σ = 0.8 / 0.6), it was exposed through a mask pattern of 40 nm holes and 105 nm pitch. After exposure, PEB (post-exposure bake) was performed at 100°C for 60 seconds. Then, the resist film was alkali-developed using a 2.38 mass% aqueous TMAH solution as an alkali developer, washed with water after development, and further dried to form a positive-type resist pattern (40 nm line and space pattern).

[0224] <Evaluation> Regarding the resist pattern formed using the above positive-type radiation-sensitive resin composition for ArF exposure, the LWR performance was evaluated according to the following method. For the length measurement of the resist pattern, a scanning electron microscope ("CG-5000" of Hitachi High-Technologies Corporation) was used.

[0225] [LWR Performance] A 40 nm line and space pattern and a resist pattern with a pitch of 105 nm were observed from above the pattern using the scanning electron microscope. Variations in line width were measured at a total of 500 points, and the 3-sigma value was determined from the distribution of the measured values. This 3-sigma value was defined as the LWR (nm). The smaller the value of the LWR, the smaller the line wobbling and the better the quality.

[0226] As a result of evaluating the resist pattern using the above positive radiation-sensitive resin composition for ArF exposure as described above, the radiation-sensitive resin composition of Example 54 had good LWR performance even when a positive resist pattern was formed by ArF exposure.

[0227] [Preparation of Negative Radiation-Sensitive Resin Composition for EUV Exposure, Formation and Evaluation of Resist Pattern Using this Composition] [Example 55] [A] 100 parts by mass of (A-15) as a resin, [B] 20.0 parts by mass of (B-5) as a radiation-sensitive acid generator, [C] 5.0 parts by mass of (C-7) as an acid diffusion controller, [E] 3.0 parts by mass (solid content) of (E-5) as a high fluorine content resin, and 6,110 parts by mass of a mixed solvent of (D-1) / (D-4) as [D] a solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-55).

[0228] On a 12-inch silicon wafer, using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Limited), a composition for forming an underlying antireflection film ("ARC66" from Brewer Science, Inc.) was applied, and then heated at 205 °C for 60 seconds to form an underlying antireflection film with an average thickness of 105 nm. On this underlying antireflection film, the above-prepared negative-type radiation-sensitive resin composition (J-55) for EUV exposure was applied using the above spin coater, and PB was performed at 130 °C for 60 seconds. Then, by cooling at 23 °C for 30 seconds, a resist film with an average thickness of 55 nm was formed. Next, this resist film was exposed using an EUV exposure apparatus ("NXE3300" from ASML) with NA = 0.33, illumination condition: Conventional s = 0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120 °C for 60 seconds. Then, the resist film was developed with an organic solvent developer, n-butyl acetate, and dried to form a negative-type resist pattern (40 nm hole, 105 nm pitch).

[0229] Regarding the resist pattern using the above negative-type radiation-sensitive resin composition for EUV exposure, it was evaluated in the same manner as the evaluation of the resist pattern using the above negative-type radiation-sensitive resin composition for ArF exposure. As a result, the radiation-sensitive resin composition of Example 55 had good sensitivity and CDU performance even when a negative-type resist pattern was formed by EUV exposure.

Industrial Applicability

[0230] According to the radiation-sensitive resin composition and the resist pattern forming method described above, a resist pattern with good sensitivity to exposure light and excellent LWR performance and CDU performance can be formed. Therefore, these can be suitably used in the processing process of semiconductor devices and the like, which are expected to further miniaturize in the future.

Claims

1. An onium salt compound, a resin containing a structural unit having an acid dissociable group, a solvent, and including, The onium salt compound is at least one selected from the group consisting of an onium salt compound (1) represented by the following formula (1) and an onium salt compound (2) represented by the following formula (2). A radiation-sensitive resin composition. 【Chemical 1】 (In the above formula (1), R １ is a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms. R ２ and R ３ are each independently a hydrogen atom, a halogen atom, a carboxy group, an amino group or a monovalent organic group having 1 to 40 carbon atoms, or R ２ and R ３ together represent a ring structure having 5 to 8 ring members formed together with two carbon atoms to which they are attached. X １ and X ２ are each independently an oxygen atom or a sulfur atom, provided that X １ and X ２ are not both sulfur atoms. Z １ ＋ is a monovalent radiation-sensitive onium cation. In the above formula (2), R ４ is a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 40 carbon atoms. R ５ and R ６ are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms, or R ５ and R ６ together represent a ring structure having 3 to 8 ring members formed together with the nitrogen atom to which they are attached. Z ２ ＋ is a monovalent radiation-sensitive onium cation.)

2. In the above formula (1), X １ and X ２ The radiation-sensitive resin composition according to claim 1, wherein both are oxygen atoms.

3. In the above formula (1), R ２ is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, a carboxy group, an amino group, or a monovalent organic group having 1 to 40 carbon atoms, and R ３ is a hydrogen atom, a halogen atom, a carboxy group, an amino group, or a monovalent organic group having 1 to 40 carbon atoms (excluding a methyl group), or R ２ and R ３ represent a ring structure having 5 to 8 ring members formed together with the two carbon atoms to which they are attached, the radiation-sensitive resin composition according to claim 1 or 2.

4. The radiation-sensitive onium cations in the above formula (1) and the above formula (2) are each independently a sulfonium cation or an iodonium cation. The radiation-sensitive resin composition according to any one of Claims 1 to 3.

5. The onium salt compound is the onium salt compound (1). The radiation-sensitive resin composition according to any one of Claims 1 to 4.

6. The content of the onium salt compound is 0.01 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the resin. The radiation-sensitive resin composition according to any one of Claims 1 to 5.

7. The content of the onium salt compound is 1.0 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the resin. The radiation-sensitive resin composition according to any one of Claims 1 to 6.

8. Further comprising a radiation-sensitive acid generator that generates an acid having a pKa smaller than the acid generated from the onium salt compound upon irradiation with radiation. The radiation-sensitive resin composition according to any one of Claims 1 to 7.

9. The molecular weight of the resin is such that the polystyrene-equivalent weight average molecular weight (Mw) by gel permeation chromatography (GPC) is 1,000 or more and less than 9,000. The radiation-sensitive resin composition according to any one of Claims 1 to 8.

10. The structural unit having an acid dissociable group is represented by the following formula (3). The radiation-sensitive resin composition according to any one of Claims 1 to 9. 【Chemical 2】 (In the above formula (3), R ７ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ８ is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ９ and R １０ each independently represents a monovalent linear hydrocarbon group having 1 to 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 atoms to which they are attached.)

11. A step of forming a resist film by directly or indirectly applying the radiation-sensitive resin composition according to any one of Claims 1 to 10 onto a substrate, a step of exposing the resist film, a step of developing the exposed resist film with a developer, and A pattern forming method including.

12. The pattern forming method according to Claim 11, wherein the development is performed with an organic solvent.

13. An onium salt compound represented by the following formula (1). 【Chemical Formula 3】 (In the above formula (1), R １ is a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms. R ２ and R ３ each independently represents a hydrogen atom, a halogen atom, a carboxy group, an amino group or a monovalent organic group having 1 to 40 carbon atoms, or R ２ and R ３ together represent a ring structure having 5 to 8 ring members formed together with two carbon atoms to which they are attached. X １ and X ２ are each independently an oxygen atom or a sulfur atom, provided that X １ and X ２ do not both become sulfur atoms. Z １ ＋ is a monovalent radiation-sensitive onium cation.)

14. In the above formula (1), X １ and X ２ are both oxygen atoms. The onium salt compound according to claim 13.

15. In the above formula (1), R ２ is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, a carboxy group, an amino group or a monovalent organic group having 1 to 40 carbon atoms, and R ３ is a hydrogen atom, a halogen atom, a carboxy group, an amino group or a monovalent organic group having 1 to 40 carbon atoms (excluding a methyl group), or R ２ and R ３ represent a ring structure having 5 to 8 ring members formed together with two carbon atoms to which they are attached, the onium salt compound according to claim 13 or 14.

16. An onium salt compound represented by the following formula (2). [Chemical Formula 4] (In the above formula (2), R ４ is a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 40 carbon atoms. R ５ and R ６ are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms, or R ５ and R ６ together represent a ring structure having 3 to 8 ring members formed together with the nitrogen atom to which they are attached. Z ２ ＋ is a monovalent radiation-sensitive onium cation.)

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