Radiation-sensitive resin composition and pattern-forming method

Abstract

Provided are a radiation-sensitive resin composition that has suitable storage stability and makes it possible to form a resist film with excellent sensitivity, LWR performance, water repellency, and development defect-suppressing performance, and a pattern formation method. The radiation-sensitive resin composition contains: a first resin including a structural unit (I) represented by formula (1), a structural unit (II) represented by formula (2) (excluding the structural unit represented by formula (1)), and a structural unit (III) having an acid-cleavable group; and a solvent. (In formula (1), RK1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L1 is an alkanediyl group having 1-5 carbon atoms. Rf1 is a monovalent fluorinated hydrocarbon group having 2-10 carbon atoms and 5-7 fluorine atoms. In formula (2), RK2 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Lf is a fluorine-substituted or unsubstituted divalent organic group having 1-20 carbon atoms. L2 is *-COO- or *-OCO-. * is a bond on the Lf side. p is an integer of 0-2. When a plurality of Lf and L2 are present, the plurality of Lf and L2 may be the same or different from each other. Rf2 is a fluorine-substituted or unsubstituted monovalent organic group having 1-20 carbon atoms. Lf and Rf2 have a total of one or more fluorine atoms.)

Description

[Technical Field]

[0001] The present invention relates to a radiation-sensitive resin composition and a pattern-forming method. [Background technology]

[0002] Photolithography, which uses resist compositions, is employed to form fine circuits in semiconductor devices. A typical procedure involves, for example, generating acid by irradiating a resist composition film with radiation through a mask pattern. This acid then acts as a catalyst, creating a difference in the solubility of the resin in alkaline or organic solvent-based developers between the exposed and unexposed areas, thereby forming a resist pattern on the substrate.

[0003] The above-mentioned photolithography techniques utilize short-wavelength radiation such as ArF excimer lasers, or combine ArF exposure with liquid immersion lithography to advance pattern miniaturization.

[0004] In immersion lithography, attempts have been made to add water-repellent compounds to resist compositions used in the resist method with the aim of improving process efficiency by modifying the surface of the resist film. For example, a technique has been proposed to add water-repellent compounds to the resist composition that maintain hydrophobicity while being soluble in alkaline developers in order to improve resist performance and defect prevention (see Japanese Patent No. 6774214). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 6774214 [Overview of the project] [Problems that the invention aims to solve]

[0006] As a next-generation technology following ArF lithography, the use of even shorter wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet) is being explored. Even in the aforementioned next-generation technologies, resist compositions with added water-repellent compounds require sensitivity, LWR (Line Width Roughness) performance (reducing variations in the line width of the resist pattern), water repellency, and suppression of development defects.

[0007] However, increasing the solubility of water-repellent compounds in the developer to enhance the suppression of development defects can sometimes make them unsuitable for long-term storage due to their reactivity. Storage stability and the suppression of development defects are in a trade-off relationship, and both must be achieved.

[0008] The present invention aims to provide a radiation-sensitive resin composition and pattern-forming method that can form a resist film with excellent sensitivity, LWR performance, water repellency, and development defect suppression, and that has good storage stability. [Means for solving the problem]

[0009] The inventors of this invention conducted extensive research to solve this problem and, as a result, found that the above objective can be achieved by adopting the following configuration, thus completing the present invention.

[0010] For example, in one embodiment, the present invention A first resin comprising a structural unit (I) represented by the following formula (1), a structural unit (II) represented by the following formula (2) (excluding the structural unit represented by the following formula (1)), and a structural unit (III) having an acid-dissociable group, Solvent and This relates to a radiation-sensitive resin composition containing [a specific substance]. [ka] (In the above formula (1), R K1 These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L 1 This is an alkanediyl group having 1 to 5 carbon atoms. Rf1 is a monovalent fluorinated hydrocarbon group having 2 to 10 carbon atoms and 5 to 7 fluorine atoms. In the above formula (2), R K2 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. L f is a fluorine-substituted or unsubstituted divalent organic group having 1 to 20 carbon atoms. L 2 is * -COO- or * -OCO-. * is a bond on the L f side. p is an integer of 0 to 2. When a plurality of L f and L 2 are present, the plurality of L f and L 2 may each be the same or different from each other. R f2 is a fluorine-substituted or unsubstituted monovalent organic group having 1 to 20 carbon atoms. provided that L f and R f2 have a total of 1 or more fluorine atoms.)

[0011] The radiation-sensitive resin composition in question provides excellent storage stability and allows for the construction of a resist film that satisfies the requirements for sensitivity, LWR performance, water repellency, and development defect suppression. Although the reason for this is not certain and is not limited to this, it is presumed to be as follows: The first resin exhibits high water repellency due to the fluorine atoms contained in structural units (I) and (II). Furthermore, during the development process, a dissociation reaction occurs in one or both of structural units (I) and (II) in the first resin, improving the solubility of the first resin in the developer solution, and consequently improving the development defect suppression. On the other hand, the relatively bulky structure introduced around the parts of structural units (I) and (II) where the developer dissociation reaction occurs (mainly the ester bonds at the end of the side chains) acts as a reaction barrier, suppressing unintended dissociation reactions caused by moisture during storage of the radiation-sensitive resin composition. It is presumed that these combined effects enable the simultaneous achievement of the conflicting requirements of storage stability and development defect suppression. Furthermore, it is presumed that sensitivity and LWR performance can be ensured by the inclusion of structural unit (III), which has an acid-dissociable group, along with structural units (I) and (II) in the first resin.

[0012] In this specification, "organic group" is a group having at least one carbon atom. Unless otherwise specified, "hydrocarbon group" includes linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. The above "hydrocarbon group" includes both saturated hydrocarbon groups and unsaturated hydrocarbon groups. The above "linear hydrocarbon group" refers to a hydrocarbon group that does not include a cyclic structure and consists only of a linear structure, and includes both straight-chain hydrocarbon groups and branched-chain hydrocarbon groups. The above "alicyclic hydrocarbon group" refers to a hydrocarbon group that includes only an alicyclic structure as its ring structure and does not include an aromatic ring structure, and includes both monocyclic alicyclic hydrocarbon groups and polycyclic alicyclic hydrocarbon groups. However, it is not necessary to consist only of an alicyclic structure, and it may include a linear structure as part of it. The above "aromatic hydrocarbon group" refers to a hydrocarbon group that includes an aromatic ring structure as its ring structure. However, it is not necessary to consist only of an aromatic ring structure, and it may include a linear structure or an alicyclic structure as part of it.

[0013] In another embodiment, the present invention is A step of applying the radiation-sensitive resin composition directly or indirectly to a substrate to form a resist film, The process of exposing the above-mentioned resist film, The process involves developing the exposed resist film with a developer solution. This relates to a pattern formation method that includes [specific details].

[0014] According to this pattern formation method, it is possible to form a resist film with excellent sensitivity, LWR performance, water repellency, and development defect suppression, and since the above-mentioned radiation-sensitive resin composition has good storage stability, high-quality resist patterns can be efficiently formed. [Modes for carrying out the invention]

[0015] The embodiments of the present invention will be described in detail below, but the present invention is not limited to these embodiments. A preferred combination of embodiments is also preferable.

[0016] 《Radiation-sensitive resin composition》 The radiation-sensitive resin composition according to this embodiment (hereinafter also simply referred to as "the composition") comprises a first resin and a solvent. Preferably, the composition contains, in addition to the first resin, a second resin which comprises structural units having acid-dissociable groups and has a lower mass content of fluorine atoms than the first resin. Preferably, the composition further comprises a radiation-sensitive acid generator and an acid diffusion control agent. The composition may contain other optional components as long as they do not impair the effects of the present invention.

[0017] <First Resin> The first resin contains structural unit (I) represented by formula (1) above, structural unit (II) represented by formula (2) above (excluding structural unit (I)), and structural unit (III) having an acid-dissociable group. The first resin may contain other structural units in addition to structural units (I) to (III) as long as the effects of the present invention are not impaired. Each structural unit will be described below.

[0018] (Structural Unit (I)) The structural unit (I) is represented by the following formula (1). [ka] (In the above formula (1), R K1 These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L 1 This is an alkanediyl group having 1 to 5 carbon atoms. R f1 (It is a monovalent fluorinated hydrocarbon group with 2 to 10 carbon atoms and containing 5 to 7 fluorine atoms.)

[0019] R K1 From the viewpoint of copolymerization of the monomer that gives structural unit (I), a hydrogen atom or a methyl group is preferred.

[0020] L 1 Alkanediyl groups with 1 to 5 carbon atoms, represented by , include groups obtained by removing two hydrogen atoms from the corresponding chain-like or branched alkane. The two hydrogen atoms may be removed from the same carbon atom or from different carbon atoms. Specific examples include methanediyl group, 1,1-ethanediyl group, 1,2-ethanediyl group, 1,1-dimethyl-1,2-ethanediyl group, 1,1-propanediyl group, 1,2-propanediyl group, 1,3-propanediyl group, 2,2-propanediyl group, 1,1-butanediyl group, 2,2-butanediyl group, 1,2-butanediyl group, 1,3-butanediyl group, 1,4-butanediyl group, 2,3-butanediyl group, etc. Among these, L 1 It is preferable that this is a methanediyl group or an ethanediyl group (1,1-ethanediyl group or 1,2-ethanediyl group).

[0021] R f1 Examples of monovalent fluorinated hydrocarbon groups having 2 to 10 carbon atoms and 5 to 7 fluorine atoms, as represented by [the formula], include monovalent fluorinated linear hydrocarbon groups having 2 to 10 carbon atoms and 5 to 7 fluorine atoms, and monovalent fluorinated alicyclic hydrocarbon groups having 3 to 10 carbon atoms and 5 to 7 fluorine atoms.

[0022] Examples of the above monovalent fluorinated chain hydrocarbon groups having 5 to 7 fluorine atoms and 2 to 10 carbon atoms include, for example, Fluorinated alkyl groups such as pentafluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, heptafluoropropyl group, 1,1,1,3,3,3-hexafluoro-2-propyl group, 1,1,1,3,3,3-hexafluoro-2-fluoropropyl group, and heptafluoro-n-propyl group; Fluorinated alkenyl groups such as pentafluoropropenyl groups; Examples include fluorinated alkynyl groups such as pentafluorobutynyl groups.

[0023] Examples of the above-mentioned monovalent fluorinated alicyclic hydrocarbon groups having 5 to 7 fluorine atoms and 3 to 10 carbon atoms include: Fluorinated cycloalkyl groups such as pentafluorocyclobutyl group, hexafluorocyclobutyl group, pentaolocyclopentyl group, hexafluorocyclopentyl group, heptafluorocyclopentyl group, pentafluorocyclohexyl group, hexaolocyclohexyl group, pentafluorocyclohexylmethyl group, pentafluoronorbornyl group, pentafluoroadamantyl group, pentafluorobornyl group, and pentafluoroisobornyl group; Examples include fluorinated cycloalkenyl groups such as pentafluorocyclopentenyl groups and pentafluorocyclohexenyl groups.

[0024] R f1 Preferably, the group is a monovalent fluorinated linear hydrocarbon group having 2 to 8 carbon atoms and containing 5 to 7 fluorine atoms; more preferably, a monovalent fluorinated linear hydrocarbon group having 2 to 6 carbon atoms and containing 5 to 7 fluorine atoms; even more preferably, a monovalent linear hydrocarbon group having 2 to 4 carbon atoms and containing 5 fluorine atoms; and particularly preferably, a monovalent linear saturated hydrocarbon group having 2 to 4 carbon atoms and containing 5 fluorine atoms.

[0025] Examples of monomers that give structural unit (I) include compounds represented by the following formulas (1-1) to (1-18). [ka]

[0026] The lower limit of the content of structural unit (I) in the total structural units constituting the first resin (total if there are multiple types of structural unit (I)) is preferably 5 mol%, more preferably 10 mol%, even more preferably 15 mol%, and particularly preferably 20 mol%. The upper limit of the above content is preferably 80 mol%, more preferably 70 mol%, even more preferably 60 mol%, and particularly preferably 50 mol%. By setting the content of structural unit (I) within the above range, the above radiation-sensitive resin composition can be made to further improve water repellency, storage stability, and development defect suppression.

[0027] (Method for synthesizing monomers that give structural units (I)) The monomer (i) that gives structural unit (I) can be synthesized by a condensation reaction between a polymerizable alcohol and a fluorine-containing carboxylic acid, as shown in the scheme below. Other structures can also be synthesized by changing the structure of the alcohol or carboxylic acid.

[0028] [ka] (In the scheme, R K1 , L 1 and R f1 This is equivalent to equation (1) above.

[0029] (Structural Unit (II)) The structural unit (II) is represented by the following formula (2). [ka] (In the above formula (2), R K2 These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Lf This refers to a fluorine-substituted or unsubstituted divalent organic group having 1 to 20 carbon atoms. L 2 teeth, * -COO- or * -OCO-. * is L f It is a side joint. p is an integer between 0 and 2. f and L 2 If there are multiple L f and L 2 They are either identical or different from one another. R f2 This refers to a monovalent organic group having 1 to 20 carbon atoms, either fluorine-substituted or unsubstituted. However, L f and R f2 It has a total of one or more fluorine atoms.

[0030] R K2 From the viewpoint of copolymerization of the monomer that gives structural unit (II), a hydrogen atom or a methyl group is preferred.

[0031] L f L is a divalent organic group having 1 to 20 carbon atoms, and some or all of the hydrogen atoms may be substituted with fluorine atoms, or they may not be substituted with fluorine atoms (they may be unsubstituted). f As a fluorine-substituted or unsubstituted divalent organic group having 1 to 20 carbon atoms represented by the above formula (2), R f2 Since a fluorine-substituted or unsubstituted monovalent organic group having 1 to 20 carbon atoms, from which one hydrogen atom has been removed, can be suitably adopted, first R f2 Explain.

[0032] R f2The group is a monovalent organic group having 1 to 20 carbon atoms, and some or all of its hydrogen atoms may be substituted with fluorine atoms, or may not be substituted with fluorine atoms (it may be unsubstituted). The monovalent organic group having 1 to 20 carbon atoms is not particularly limited and may have a chain structure, a cyclic structure, or a combination thereof. Examples of the chain structure include chain hydrocarbon groups that are saturated or unsaturated, linear or branched. Examples of the cyclic structure include cyclic hydrocarbon groups that are alicyclic, aromatic, or heterocyclic. Among these, preferred monovalent organic groups are substituted or unsubstituted monovalent chain hydrocarbon groups having 1 to 20 carbon atoms, substituted or unsubstituted monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, substituted or unsubstituted monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, or combinations thereof. Other examples include groups in which some or all of the hydrogen atoms in a chain-like or cyclic structure are substituted with substituents, and groups containing a divalent linking group selected from -CO-, -CS-, -O-, -S-, -SO2-, or -NR'-, or a combination of two or more of these, between carbon atoms or at the carbon chain ends of these groups. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Preferred divalent linking groups are -COO-, -OCO-, -OCOO-, -OCOCOO-, -CS-, -O-, -S-, or -SO2-.

[0033] Examples of substituents that substitute for some or all of the hydrogen atoms of the above organic group include halogen atoms such as fluorine, chlorine, bromine, and iodine; hydroxyl groups; carboxyl groups; cyano groups; nitro groups; alkyl groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, acyloxy groups, or groups in which the hydrogen atoms of these groups are substituted with halogen atoms; and oxo groups (=O).

[0034] Examples of the monovalent chain hydrocarbon groups having 1 to 20 carbon atoms include linear or branched saturated hydrocarbon groups having 1 to 20 carbon atoms, or linear or branched unsaturated hydrocarbon groups having 1 to 20 carbon atoms.

[0035] Examples of monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms include monocyclic or polycyclic saturated hydrocarbon groups, or monocyclic or polycyclic unsaturated hydrocarbon groups. Preferred monocyclic saturated hydrocarbon groups are cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Preferred polycyclic cycloalkyl groups are bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl groups. Examples of monocyclic unsaturated hydrocarbon groups include monocyclic cycloalkenyl groups such as cyclopropenyl, cyclobutenyl, cyclopentenyl, and cyclohexenyl groups. Examples of polycyclic unsaturated hydrocarbon groups are polycyclic cycloalkenyl groups such as norborneyl, tricyclodecenyl, and tetracyclododecenyl groups. A bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two carbon atoms constituting the alicyclic ring that are not adjacent to each other are bonded together by a bond chain containing one or more carbon atoms.

[0036] Examples of the above-mentioned monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xyl, naphthyl, and anthyl groups; and aralkyl groups such as benzyl, phenethyl, and naphthylmethyl groups.

[0037] Examples of the heterocyclic cyclic hydrocarbon groups mentioned above include groups obtained by removing one hydrogen atom from an aromatic heterocyclic structure and groups obtained by removing one hydrogen atom from an alicyclic heterocyclic structure. Aromatic structures with five membered rings that acquire aromaticity by introducing heteroatoms are also included in heterocyclic structures. Examples of heteroatoms include oxygen atoms, nitrogen atoms, and sulfur atoms.

[0038] Examples of the above aromatic heterocyclic structures include, for example, Oxygen atom-containing aromatic heterocyclic structures such as furan, pyran, benzofuran, and benzopyran; Nitrogen-containing aromatic heterocyclic structures such as pyrrole, imidazole, pyridine, pyrimidine, pyrazine, indole, quinoline, isoquinoline, acridine, phenazine, and carbazole; Sulfur atom-containing aromatic heterocyclic structures such as thiophene; Examples include aromatic heterocyclic structures containing multiple heteroatoms such as thiazole, benzothiazole, thiazine, and oxazine.

[0039] Examples of the above alicyclic heterocyclic structures include, for example, Oxygen atom-containing alicyclic heterocyclic structures such as oxiranes, tetrahydrofurans, tetrahydropyrans, dioxolanes, and dioxanes; Nitrogen-containing alicyclic heterocyclic structures such as aziridine, pyrrolidine, piperidine, and piperazine; Sulfur atom-containing alicyclic heterocyclic structures such as thiethane, thiolane, and thian; Examples include alicyclic heterocyclic structures containing multiple heteroatoms such as morpholine, 1,2-oxathiolane, and 1,3-oxathiolane.

[0040] Examples of cyclic structures include lactone structures, cyclic carbonate structures, sultone structures, and structures containing cyclic acetals.

[0041] As mentioned above, L f As a fluorine-substituted or unsubstituted divalent organic group having 1 to 20 carbon atoms, the above R f2 A group obtained by removing one hydrogen atom from a fluorine-substituted or unsubstituted monovalent organic group having 1 to 20 carbon atoms, represented by [formula], can be suitably adopted.

[0042] p is preferably 1 or 2, and more preferably 1.

[0043] L f and R f2 L has a total of one or more fluorine atoms. f and R f2 The lower limit of the total number of fluorine atoms it may have is 2 or 3. The upper limit of the above total number may be 10, 8 or 6.

[0044] In the above equation (2), L 2It is preferable that one or two fluorine atoms or a trifluoromethyl group are bonded to at least one carbon atom adjacent to the carbonyl group in the compound.

[0045] Examples of monomers that give structural unit (II) include compounds represented by the following formulas (2-1) to (2-33). [ka]

[0046] [ka]

[0047] The lower limit of the content of structural unit (II) in the total structural units constituting the first resin (total if there are multiple types of structural unit (II)) is preferably 5 mol%, more preferably 10 mol%, even more preferably 15 mol%, and particularly preferably 20 mol%. The upper limit of the above content is preferably 80 mol%, more preferably 70 mol%, even more preferably 60 mol%, and particularly preferably 50 mol%. By setting the content of structural unit (II) within the above range, the above radiation-sensitive resin composition can be made to further improve water repellency, storage stability, and development defect suppression.

[0048] (Structural Unit (III)) The first resin contains a structural unit (III) having an acid-dissociable group. An "acid-dissociable group" is a group that substitutes a hydrogen atom in alkali-soluble groups such as carboxyl groups, phenolic hydroxyl groups, sulfo groups, and sulfonamide groups, and dissociates upon the action of an acid. Therefore, the acid-dissociable group is bonded to the oxygen atom that was bonded to the hydrogen atom in these functional groups. The structural unit (III) is preferably represented by the following formula (3).

[0049] [ka]

[0050] In the above equation (3), R 7 R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 8 R is a monovalent hydrocarbon group having 1 to 20 carbon atoms. 9 and R 10 Each of these independently represents a monovalent linear hydrocarbon group having 1 to 10 carbon atoms, 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 with the carbon atoms to which they are bonded.

[0051] The above R 7 From the viewpoint of copolymerization of the monomer that gives structural unit (III), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0052] The above R 8 Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms, represented by , include monovalent linear hydrocarbon groups having 1 to 10 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms.

[0053] The above R 8 ~R 10 As a monovalent chain hydrocarbon group having 1 to 10 carbon atoms represented by the above formula (2), R f2 Among the monovalent chain hydrocarbon groups having 1 to 20 carbon atoms, groups corresponding to those having 1 to 10 carbon atoms can be suitably adopted.

[0054] The above R 8 ~R 10 As a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above formula (2), R f2 A monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms can be suitably used in this material.

[0055] The above R 8 As a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by the above formula (2), R f2 Monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms can be suitably used in this material.

[0056] The above R 8 Preferably, the group consists of a monovalent linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0057] The above R 9 and R 10 The divalent alicyclic groups having 3 to 20 carbon atoms, which are formed by combining these atoms with the carbon atoms to which they are bonded, are not particularly limited as long as they are groups obtained by removing two hydrogen atoms from the same carbon atoms that constitute the carbon ring of a monocyclic or polycyclic alicyclic hydrocarbon of the above carbon number. They may be monocyclic or polycyclic hydrocarbon groups, and as polycyclic hydrocarbon groups, they may be bridged alicyclic hydrocarbon groups or condensed alicyclic hydrocarbon groups, and may be saturated or unsaturated hydrocarbon groups. A condensed alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which multiple alicyclics share an edge (a bond between two adjacent carbon atoms).

[0058] Among monocyclic alicyclic hydrocarbon groups, preferred saturated hydrocarbon groups include cyclopentanediyl, cyclohexanediyl, cycloheptanediyl, and cyclooctanediyl groups, while preferred unsaturated hydrocarbon groups include cyclopentenediyl, cyclohexenediyl, cycloheptenediyl, cyclooctenediyl, and cyclodecenediyl groups. Among polycyclic alicyclic hydrocarbon groups, bridged alicyclic saturated hydrocarbon groups are preferred, such as bicyclo[2.2.1]heptane-2,2-diyl (norbornane-2,2-diyl), bicyclo[2.2.2]octane-2,2-diyl, and tricyclo[3.3.1.1 3,7 A decane-2,2-diyl group (adamantane-2,2-diyl group) is preferred.

[0059] Among these, R 8 R is an alkyl group or phenyl group having 1 to 4 carbon atoms. 9 and R 10 It is preferable that the alicyclic structure formed by combining these elements with the carbon atoms to which they are bonded is a polycyclic or monocyclic cycloalkane structure.

[0060] Examples of structural units (III) include structural units represented by the following formulas (3-1) to (3-7) (hereinafter also referred to as "structural units (III-1) to (III-7)").

[0061] [ka]

[0062] In the above equations (3-1) to (3-7), R 7 ~R 10 This is equivalent to equation (3) above. i and j are independent integers between 1 and 4. k and l are 0 or 1.

[0063] i and j are preferably 1. 8 The preferred group is a methyl group, ethyl group, isopropyl group, or phenyl group. 9 and R 10 A methyl group or an ethyl group is preferred.

[0064] The first resin may contain one or more structural units (III) in combination.

[0065] The lower limit of the content of structural unit (III) in the total structural units constituting the first resin (total if there are multiple types of structural unit (III)) is preferably 5 mol%, more preferably 8 mol%, even more preferably 10 mol%, and particularly preferably 15 mol%. The upper limit of the above content is preferably 80 mol%, more preferably 70 mol%, even more preferably 60 mol%, and particularly preferably 50 mol%. By setting the content of structural unit (III) within the above range, the sensitivity, LWR performance, and development defect suppression of the radiation-sensitive resin composition can be further improved.

[0066] (Other structural units) The first resin may include structural units other than those listed above, such as structural units having an alicyclic structure represented by the following formula (6). [ka] (In the above formula (6), R 1α R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 2α (It is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.)

[0067] In the above formula (6), R 2α As a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above formula (3), R 8 ~R 10 A monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, represented by [the formula shown], can be suitably used.

[0068] When the first resin contains structural units having the above-mentioned alicyclic structure, the lower limit of the content of structural units having the above-mentioned alicyclic structure is preferably 5 mol%, more preferably 10 mol%, and even more preferably 15 mol%, relative to the total structural units constituting the first resin. The upper limit of the above content is preferably 40 mol%, more preferably 30 mol%, and even more preferably 20 mol%.

[0069] (Method for synthesizing the first resin) The first resin can be synthesized, for example, by carrying out a polymerization reaction in a suitable solvent using monomers that give each structural unit, with the help of a radical polymerization initiator or the like.

[0070] Examples of the radical polymerization initiators mentioned above include azo-based radical initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl-2,2'-azobisisobutyrate; and peroxide-based radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Among these, AIBN and dimethyl-2,2'-azobisisobutyrate are preferred, and AIBN is more preferred. These radical initiators can be used individually or in combination of two or more.

[0071] Examples of solvents used in the above polymerization reaction include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, and norbornane; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene; halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylenedibromide, and chlorobenzene; saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate, and methyl propionate; ketones such as acetone, methyl ethyl ketone, 4-methyl-2-pentanone, and 2-heptanone; ethers such as tetrahydrofuran, dimethoxyethanes, and diethoxyethanes; and alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol. These solvents used in the polymerization reaction may be used individually or in combination of two or more.

[0072] The reaction temperature in the above polymerization reaction is usually 40°C to 150°C, with 50°C to 120°C being preferred. The reaction time is usually 1 hour to 48 hours, with 1 hour to 24 hours being preferred.

[0073] The molecular weight of the first resin is not particularly limited, but the lower limit of the polystyrene-equivalent weight-average molecular weight (Mw) determined by gel permeation chromatography (GPC) is preferably 1,000, more preferably 2,000, even more preferably 3,000, and particularly preferably 3,500. The upper limit of the above Mw is preferably 50,000, more preferably 30,000, even more preferably 20,000, and particularly preferably 18,000 or less. By setting the Mw of the first resin within the above range, the storage stability and development defect suppression of the radiation-sensitive resin composition can be improved.

[0074] The ratio of Mw to the polystyrene-equivalent number-average molecular weight (Mn) (Mw / Mn) of the first resin, calculated by GPC, is usually between 1 and 5, preferably between 1 and 3, and more preferably between 1 and 2.

[0075] The methods for measuring Mw and Mn of the first resin and the second resin described later are as described in the examples.

[0076] The lower limit of the content of the first resin is preferably 0.1 parts by mass, more preferably 0.5 parts by mass, even more preferably 1 part by mass, and particularly preferably 2 parts by mass, per 100 parts by mass of the second resin (base resin) described later. The upper limit of the above content is preferably 15 parts by mass, more preferably 12 parts by mass, even more preferably 10 parts by mass, and particularly preferably 8 parts by mass.

[0077] <Second resin> The second resin is a resin containing a structural unit having an acid-dissociable group and having a lower mass content of fluorine atoms than the first resin (hereinafter, this resin is also referred to as the "base resin"). The structural unit having an acid-dissociable group in the base resin is preferably the structural unit (III) contained in the first resin (hereinafter, this is also referred to as "structural unit (III)" in the second resin). The radiation-sensitive resin composition exhibits excellent pattern-forming properties because the second resin, as the base resin, contains structural unit (III).

[0078] The lower limit of the content of structural unit (III) in the total structural units constituting the base resin (total if multiple types of structural units exist) is preferably 10 mol%, more preferably 20 mol%, even more preferably 25 mol%, and particularly preferably 30 mol%. The upper limit of the above content is preferably 80 mol%, more preferably 70 mol%, even more preferably 65 mol%, and particularly preferably 60 mol%. By setting the content of structural unit (III) in the base resin within the above range, the pattern-forming properties of the radiation-sensitive resin composition can be further improved.

[0079] In addition to structural units having acid-dissociable groups, the base resin may also have structural units (IV) that include at least one selected from the group consisting of lactone structures, cyclic carbonate structures, and sultone structures, as described later, as well as other structural units other than structural units (III) and structural unit (IV). Each structural unit will be described below.

[0080] (Structural Unit (IV)) Structural Unit (IV) 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. When the base resin further comprises Structural Unit (IV), the solubility in a developer can be adjusted, and as a result, the radiation-sensitive resin composition can improve lithography performance such as resolution. In addition, the adhesion between the resist pattern formed from the base resin and a substrate can be improved.

[0081] Examples of Structural Unit (IV) include structural units represented by the following formulas (T-1) to (T-10).

[0082]

Chemical Formula

[0083] In the above formula, R L1 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R L2 to R L5 each independently represent 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 combined with each other to form a divalent alicyclic group having 3 to 8 carbon atoms that is constituted together with the carbon atom to which these groups are bonded. L T is a single bond or a divalent linking group. X is an oxygen atom or a methylene group. k is an integer from 0 to 3. m is an integer from 1 to 3.

[0084] The above R L4 and R L5 are combined with each other to form a divalent alicyclic group having 3 to 8 carbon atoms that is constituted together with the carbon atom to which these groups are bonded, examples of said divalent alicyclic group include the same ones as the divalent alicyclic group constituted by R 9 and R 10Examples include divalent alicyclic groups with 3 to 20 carbon atoms, where these groups are combined with the carbon atoms to which they are bonded, and which have 3 to 8 carbon atoms. One or more hydrogen atoms on this alicyclic group may be substituted with hydroxyl groups.

[0085] The above L T Examples of divalent linking groups represented by include divalent linear or branched hydrocarbon groups having 1 to 10 carbon atoms, divalent alicyclic hydrocarbon groups having 4 to 12 carbon atoms, or groups composed of one or more of these hydrocarbon groups and at least one of the groups -CO-, -O-, -NH-, and -S-.

[0086] Among these, structural units (IV) are preferably those containing a lactone structure, more preferably those containing a norbornane lactone structure, and even more preferably those derived from norbornane lactone-yl (meth)acrylate.

[0087] The lower limit of the content of structural unit (IV) is preferably 20 mol%, more preferably 25 mol%, and even more preferably 30 mol%, relative to the total structural units constituting the base resin. The upper limit of the above content is preferably 80 mol%, more preferably 75 mol%, and even more preferably 70 mol%. By setting the content of structural unit (IV) 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.

[0088] (Structural unit (V)) The base resin may optionally contain other structural units in addition to structural units (III) and (IV) described above. Examples of these other structural units include structural unit (V) containing a polar group (excluding those corresponding to structural unit (IV)). By further containing structural unit (V), the solubility in the developer can be adjusted, and as a result, the lithographic performance such as resolution of the radiation-sensitive resin composition can be improved. Examples of these polar groups include hydroxyl groups, carboxyl groups, cyano groups, nitro groups, sulfonamide groups, etc. Among these, hydroxyl groups and carboxyl groups are preferred, and hydroxyl groups are more preferred.

[0089] Examples of structural units (V) include structural units represented by the following formula.

[0090] [ka]

[0091] In the above formula, R A This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0092] When the base resin has structural units (V) having the polar groups described above, the lower limit of the content of structural units (V) is preferably 5 mol%, more preferably 8 mol%, and even more preferably 10 mol%, relative to the total structural units constituting the base resin. The upper limit of the content is preferably 40 mol%, more preferably 30 mol%, and even more preferably 25 mol%. By setting the content of structural units (V) within the above range, the lithographic performance, such as resolution, of the radiation-sensitive resin composition can be further improved.

[0093] (Structural Unit (VI)) Structural unit (VI) is a structural unit derived from hydroxystyrene or a structural unit having a phenolic hydroxyl group. The base resin optionally contains structural unit (VI) as another structural unit, in addition to the structural unit (V) having the polar group described above. Structural unit (VI) contributes to improving etching resistance and improving the difference in developer solubility (dissolution contrast) between exposed areas and unexposed areas. In particular, it can be suitably applied to pattern formation using exposure with radiation having a wavelength of 50 nm or less such as electron beams or EUV. In this case, the resin preferably has the above structural unit (III) together with structural unit (VI), and optionally structural unit (V).

[0094] The structural unit derived from hydroxystyrene is represented, for example, by the following formulas (4-1) to (4-2), and the structural unit having a phenolic hydroxyl group is represented, for example, by the following formulas (4-3) to (4-4).

[0095]

Chemical Formula

[0096] In the above formulas (4-1) to (4-4), R 11 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0097] When obtaining structural unit (VI), it is preferable to perform polymerization in a state where the phenolic hydroxyl group is protected by a protecting group such as an alkali-dissociable group (for example, an acyl group) during polymerization, then perform hydrolysis to conduct deprotection, thereby obtaining structural unit (VI).

[0098] In the case of a base resin for exposure with radiation having a wavelength of 50 nm or less, the lower limit of the content ratio of structural unit (VI) is preferably 10 mol%, and more preferably 20 mol%, relative to all structural units constituting the base resin. Further, the upper limit of the above content ratio is preferably 70 mol%, and more preferably 60 mol%.

[0099] The molecular weight of the base resin is not particularly limited, but the lower limit of the polystyrene-equivalent weight-average molecular weight (Mw) determined by gel permeation chromatography (GPC) is preferably 1,000, more preferably 2,000, even more preferably 3,000, and particularly preferably 4,000. The upper limit of Mw is preferably 30,000, more preferably 20,000, even more preferably 15,000, and particularly preferably 10,000. If the Mw of the base resin is below 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.

[0100] The ratio of Mw (Mw / Mn) to the polystyrene-equivalent number-average molecular weight (Mn) of the base resin, calculated by GPC, is usually between 1 and 5, preferably between 1 and 3, and more preferably between 1 and 2.

[0101] (Method for synthesizing the second resin) The second resin can be synthesized by the same method as the synthesis method for the first resin described above.

[0102] <Radiation-sensitive acid generator> A radiation-sensitive acid generator is a component that generates acid upon exposure. The acid generated upon exposure is thought to perform two functions in the radiation-sensitive resin composition, depending on its strength. The first function is that, if the first and second resins contain structural unit (III) having an acid-dissociable group, the acid generated upon exposure dissociates the acid-dissociable group of said structural unit (III), generating carboxyl groups, etc. A radiation-sensitive acid generator having this first function is called radiation-sensitive acid generator (I). The second function is that, under pattern-forming conditions using the above-mentioned radiation-sensitive resin composition, the acid-dissociable group of structural unit (III) is not substantially dissociated, and the diffusion of the acid generated from the radiation-sensitive acid generator (I) in the unexposed areas is suppressed. A radiation-sensitive acid generator having this second function is called radiation-sensitive acid generator (II). The acid generated from radiation-sensitive acid generator (II) can be said to be a relatively weaker acid (an acid with a higher pKa) than the acid generated from radiation-sensitive acid generator (I). Whether a radiation-sensitive acid generator functions as a radiation-sensitive acid generator (I) or a radiation-sensitive acid generator (II) depends on the energy required for the dissociation of the acid-dissociable groups in the structural units (III) of the first and second resins, and the thermal energy conditions applied when forming a pattern using the radiation-sensitive resin composition. The radiation-sensitive acid generator may be contained in the radiation-sensitive resin composition as a compound on its own (liberated from the polymer), incorporated as part of the polymer, or both, but the form in which it exists as a compound on its own is preferred.

[0103] The radiation-sensitive resin composition contains the above-mentioned radiation-sensitive acid generator (I), which increases the polarity of the resin in the exposed area. As a result, the resin in the exposed area becomes soluble in the developer in the case of alkaline aqueous solution development, while it becomes sparingly soluble in the developer in the case of organic solvent development.

[0104] By containing the above-mentioned radiation-sensitive acid generator (II), the radiation-sensitive resin composition can form a resist pattern with superior pattern developability and LWR performance.

[0105] Examples of radioactive acid generators include onium salt compounds, sulfonimide compounds, halogen-containing compounds, and diazoketone compounds. Examples of onium salt compounds include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, and pyridinium salts. Of these, sulfonium salts and iodonium salts are preferred.

[0106] Acids produced by exposure include sulfonic acids, carboxylic acids, and sulfonimides. (1) A compound in which one or more fluorine atoms or fluorinated hydrocarbon groups are substituted on carbon atoms adjacent to a sulfo group. (2) Compounds in which the carbon atoms adjacent to the sulfo group are not substituted with a fluorine atom or a fluorinated hydrocarbon group. Examples of carboxylic acids generated by exposure include: (3) Compounds in which one or more fluorine atoms or fluorinated hydrocarbon groups are substituted on carbon atoms adjacent to a carboxyl group, (4) Compounds in which the carbon atoms adjacent to the carboxyl group are not substituted with a fluorine atom or a fluorinated hydrocarbon group. These can be listed. Of these, the radiation-sensitive acid generator (I) is preferably one that falls under (1) above, and one that has a cyclic structure is particularly preferred. The radiation-sensitive acid generator (II) is preferably one that falls under (2), (3), or (4) above, and one that falls under (2) or (4) is particularly preferred.

[0107] These radiation-sensitive acid generators may be used alone or in combination of two or more. From the viewpoint of ensuring sensitivity and developability as a resist, the lower limit of the radiation-sensitive acid generator (I) content is preferably 2 parts by mass, more preferably 5 parts by mass, and even more preferably 8 parts by mass per 100 parts by mass of the base resin. From the viewpoint of ensuring transparency to radiation, the upper limit of the radiation-sensitive acid generator (I) content is preferably 30 parts by mass, more preferably 25 parts by mass, and even more preferably 20 parts by mass per 100 parts by mass of the resin.

[0108] <Acid diffusion control agent> The radiation-sensitive resin composition may optionally contain an acid diffusion control agent. Among the above-mentioned radiation-sensitive acid generators, radiation-sensitive acid generator (II) can be suitably used as the acid diffusion control agent. The acid diffusion control agent controls the diffusion phenomenon of acid generated from the radiation-sensitive acid generator in the resist film upon exposure, thereby suppressing undesirable chemical reactions in the non-exposed areas. Furthermore, the storage stability of the resulting radiation-sensitive resin composition is improved. In addition, the resolution of the resist pattern is further improved, and changes in the line width of the resist pattern due to variations in the setting time from exposure to development can be suppressed, resulting in a radiation-sensitive resin composition with excellent process stability.

[0109] Other acid diffusion control agents include, for example, nitrogen-containing compounds having 1 to 3 nitrogen atoms in the same molecule, amide group-containing compounds, urea compounds, and nitrogen-containing heterocyclic compounds. Among these nitrogen-containing organic compounds, compounds having acid-dissociable groups can also be used.

[0110] The lower limit of the acid diffusion control agent content is preferably 0.5 parts by mass, more preferably 1 part by mass, and even more preferably 1.5 parts by mass, per 100 parts by mass of the total amount of the radiation-sensitive acid generator. The upper limit of the above content is preferably 20 parts by mass, more preferably 10 parts by mass, and even more preferably 5 parts by mass.

[0111] By setting the content of the acid diffusion control agent within the above range, the lithography performance of the radiation-sensitive resin composition can be further improved. The radiation-sensitive resin composition may contain one or more types of acid diffusion control agents.

[0112] <Solvent> The radiation-sensitive resin composition contains a solvent. The solvent is not particularly limited as long as it is capable of dissolving or dispersing at least the first resin, and optionally the second resin, radiation-sensitive acid generator, and acid diffusion control agent, etc., together with the first resin.

[0113] Examples of solvents include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0114] Examples of alcohol-based solvents include, Monoalcohol solvents with 1 to 18 carbon atoms, such as iso-propanol, 4-methyl-2-pentanol, 3-methoxybutanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, and diacetone alcohol; Polyhydric alcohol solvents with 2 to 18 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; Examples include polyhydric alcohol partial ether solvents, in which some of the hydroxyl groups of the above-mentioned polyhydric alcohol solvents have been etherified.

[0115] Examples of ether-based 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 (methylphenyl ether); Examples include polyhydric alcohol ether solvents, which are obtained by etherifying the hydroxyl groups of the above-mentioned polyhydric alcohol solvents.

[0116] Examples of ketone solvents include chain-like ketone solvents such as acetone, butanone, and methyl-iso-butyl ketone: Cyclopentanone, cyclohexanone, methylcyclohexanone, and other cyclic ketone solvents: Examples include 2,4-pentanedione, acetonylacetone, and acetophenone.

[0117] Examples of amide solvents include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; Examples include chain-like amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0118] Examples of ester-based solvents include, Monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate; Polyhydric alcohol partial ether acetate solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; Lactone-based solvents such as γ-butyrolactone and valerolactone; Carbonate-based solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; Examples of polycarboxylic acid diester solvents include propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, ethyl lactate, and diethyl phthalate.

[0119] Examples of hydrocarbon solvents include Aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; Examples include aromatic hydrocarbon solvents such as benzene, toluene, di-iso-propylbenzene, and n-amylnaphthalene.

[0120] Among these, ester solvents, ether solvents, and ketone solvents are preferred, polyhydric alcohol partial ether acetate solvents, polyhydric alcohol ether solvents, polyhydric carboxylic acid diester solvents, cyclic ketone solvents, and lactone solvents are more preferred, and propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, ethyl lactate, cyclohexanone, and γ-butyrolactone are even more preferred. The radiation-sensitive resin composition may contain one or more solvents.

[0121] <Other optional ingredients> The above-mentioned radiation-sensitive resin composition may contain other optional components in addition to the components listed above. Examples of these other optional components include crosslinking agents, segregation promoters, surfactants, alicyclic skeleton-containing compounds, sensitizers, and the like. These other optional components may be used individually or in combination of two or more types.

[0122] <Method for preparing a radiation-sensitive resin composition> The above radiation-sensitive resin composition can be prepared, for example, by mixing a first resin with a second resin, a radiation-sensitive acid generator, an acid diffusion control agent, and a solvent in predetermined proportions as needed. After mixing, the above radiation-sensitive resin composition is preferably filtered using a filter with a pore size of approximately 0.05 μm to 0.2 μm. The solid content concentration of the above radiation-sensitive resin composition is usually 0.1% to 50% by mass, preferably 0.5% to 30% by mass, and more preferably 1% to 20% by mass.

[0123] <Pattern Formation Method> A pattern forming method according to one embodiment of the present invention is: The above radiation-sensitive resin composition is applied directly or indirectly to a substrate to form a resist film (1) (hereinafter also referred to as the "resist film formation step"), The above resist film is exposed in step (2) (hereinafter also referred to as the "exposure step"), The process includes (3) developing the exposed resist film (hereinafter also referred to as the "development step").

[0124] According to the above resist pattern formation method, since the above-mentioned radiation-sensitive resin composition, which has excellent sensitivity, LWR performance, storage stability, and development defect suppression is used, high-quality resist patterns can be efficiently formed. The following describes each step.

[0125] [Resist film formation process] In this step (step (1) above), a resist film is formed using the radiation-sensitive resin composition. Examples of substrates for forming this resist film include conventionally known materials such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective film, such as those disclosed in Japanese Patent Publication No. 6-12452 or Japanese Patent Publication No. 59-93448, may be formed on the substrate. Examples of coating methods include spin coating, casting, and roll coating. After coating, pre-baking (PB) may be performed as needed to volatilize the solvent in the coating film. The PB temperature is usually 60°C to 140°C, with 80°C to 120°C being preferred. The PB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred. The thickness of the formed resist film is preferably 10 nm to 1,000 nm, and more preferably 10 nm to 500 nm.

[0126] The recessed contact angle of the resist film after pre-baking is preferably 70° or higher, more preferably 72° or higher, and even more preferably 74° or higher. The method for measuring the recessed contact angle is as described in the examples.

[0127] When performing immersion exposure, a protective film insoluble in the immersion solution may be provided on the formed resist film to avoid direct contact between the immersion solution and the resist film. The protective film may be either a solvent-peelable protective film that is peeled off with a solvent before the development process (see, for example, Japanese Patent Application Publication No. 2006-227632) or a developer-peelable protective film that is peeled off simultaneously with development in the development process (see, for example, Japanese Patent Application Publication Nos. WO2005-069076 and WO2006-035790). However, from the viewpoint of throughput, it is preferable to use a developer-peelable protective film for immersion exposure.

[0128] Furthermore, when the subsequent exposure process is carried out with radiation of a wavelength of 50 nm or less, it is preferable to use a resin having structural unit (III) and structural unit (VI), and optionally structural unit (V), as the base resin in the above composition.

[0129] [Synthesis process] In this step (step (2) above), the resist film formed in the resist film formation step (1) above is exposed by irradiating it with radiation through a photomask (and, in some cases, through an immersion medium such as water). The radiation used for exposure can be electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet light), X-rays, and gamma rays, depending on the line width of the desired pattern; or charged particle beams such as electron beams and alpha rays. Among these, far ultraviolet light, electron beams, and EUV are preferred, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV are more preferred, and electron beams and EUV with wavelengths of 50 nm or less, which are positioned as next-generation exposure technologies, are even more preferred.

[0130] When exposure is performed by immersion lithography, the immersion liquid used can be, for example, water or a fluorinated inert liquid. The immersion liquid is preferably transparent to the exposure wavelength and has the smallest possible temperature coefficient of refractive index to minimize distortion of the optical image projected onto the film. In particular, when the exposure light source is ArF excimer laser light (wavelength 193 nm), in addition to the above considerations, water is preferred due to its availability and ease of handling. When water is used, a small amount of an additive that reduces the surface tension of the water and increases its surfactant properties may be added. This additive is preferably one that does not dissolve the resist film on the wafer and has negligible effect on the optical coating on the underside of the lens. Distilled water is preferred as the water used.

[0131] After the exposure described above, it is preferable to perform a post-exposure bake (PEB) to promote the dissociation of acid-dissociable groups in the resin, etc., by the acid generated from the radiation-sensitive acid generator during exposure in the exposed portion of the resist film. This PEB creates a difference in solubility in the developer between the exposed and unexposed portions. The PEB temperature is usually 50°C to 180°C, with 80°C to 130°C being preferred. The PEB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred.

[0132] [Development process] In this step (step (3) above), the resist film exposed in the exposure step (step (2) above) is developed. This allows a predetermined resist pattern to be formed. After development, it is common to wash with a rinsing solution such as water or alcohol and then dry it.

[0133] Examples of developers used in the above development process include, in the case of alkaline development, an alkaline aqueous solution containing at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, or 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, an aqueous TMAH solution is preferred, and a 2.38% by mass aqueous TMAH solution is more preferred.

[0134] In addition, in the case of organic solvent development, examples of organic solvents include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, or solvents containing organic solvents. Examples of the above organic solvents include one or more of the solvents listed above as solvents for the radiation-sensitive resin composition. Among these, ether solvents, ester solvents, and ketone solvents are preferred. As for ether solvents, glycol ether solvents are preferred, and ethylene glycol monomethyl ether and propylene glycol monomethyl ether are more preferred. As for ester solvents, acetate ester solvents are preferred, and n-butyl acetate and amyl acetate are more preferred. As for ketone solvents, chain ketones are preferred, and 2-heptanone is more preferred. The content of organic solvents in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. Examples of components other than organic solvents in the developer include water and silicone oil.

[0135] As described above, the developer can be either an alkaline developer or an organic solvent developer, but it is preferable that the developer contains an alkaline aqueous solution and that the resulting pattern is a positive type pattern.

[0136] Examples of development methods include immersing the substrate in a tank filled with developer solution for a certain period of time (dip method), developing by piling up the developer solution on the substrate surface using surface tension and letting it remain still for a certain period of time (paddle method), spraying the developer solution onto the substrate surface (spray method), and continuously dispensing the developer solution while scanning a developer solution dispensing nozzle at a constant speed onto a substrate rotating at a constant speed (dynamic dispensing method). [Examples]

[0137] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. The methods for measuring various physical properties are shown below.

[0138] [Weight-average molecular weight (Mw) and number-average molecular weight (Mn)] The Mw and Mn of the first and second resins were measured by gel permeation chromatography (GPC) using GPC columns from Tosoh Corporation (two "G2000HXL" columns, one "G3000HXL" column, and one "G4000HXL" column) under the following conditions. The degree of dispersion (Mw / Mn) was calculated from the measured results of Mw and Mn. Leaching solvent: Tetrahydrofuran Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Column temperature: 40℃ Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0139] [ 13 C-NMR analysis] First resin and second resin 13 ¹

[0140] <[F] Synthesis of compound (monomer)> [Synthesis Example 1] (Synthesis of compound (F-1)) Compound (F-1) was synthesized according to the following synthesis scheme.

[0141] [ka]

[0142] 20 mmol of 2-hydroxyethyl methacrylate, 20.0 mmol of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 4.0 mmol of 1-dimethylaminopyridine, and 50 g of dichloromethane were mixed in a reaction vessel and cooled to 0°C. 20.0 mmol of pentafluoropropionic acid was added dropwise to this solution and stirred for 1 hour. After dilution with water, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was washed with saturated sodium chloride aqueous solution, and then with water. After drying over sodium sulfate, the solvent was removed by distillation, and the compound (F-1) was obtained in good yield by column chromatography.

[0143] [Synthesis Examples 2-9] (Synthesis of Compounds (F-2) to (F-9)) Compounds represented by the following formulas (F-2) to (F-9) were synthesized in the same manner as in Synthesis Example 1, except that the raw materials and precursors were changed as appropriate (hereinafter, the compounds represented by formulas (F-2) to (F-9) may be referred to as "compound (F-2)" to "compound (F-9)" or "monomer (F-2)" to "monomer (F-9)" respectively).

[0144] [ka]

[0145] The monomers used in the synthesis of the first and second resins, other than monomers (F-1) to monomers (F-9) listed above, are shown below. In the following synthesis examples, unless otherwise specified, parts by mass refers to the value when the total mass of the monomers used is 100 parts by mass, and mol% refers to the value when the total number of moles of the monomers used is 100 mol%.

[0146] [ka]

[0147] [ka]

[0148] [ka]

[0149] [ka]

[0150] [Synthesis Example 10] (Synthesis of the second resin (A-1)) Monomers (M-1), (M-2), and (M-10) were dissolved in 200 parts by mass of 2-butanone in a molar ratio of 35 / 20 / 45 (mol%), and AIBN (azobisisobutyronitrile) (5 mol% of the total monomers used, per 100 mol%) was added as an initiator to prepare monomer solutions. 100 parts by mass of 2-butanone was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solutions were 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 the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The cooled polymerization solution was added to methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with methanol, filtered again, and dried at 50°C for 24 hours to obtain a white powdery second resin (A-1) (yield: 74%). The Mw of the second resin (A-1) was 5,800, and the Mw / Mn ratio was 1.53. 13 13C-NMR analysis revealed that the content of each structural unit derived from (M-1), (M-2), and (M-10) was 34.8 mol%, 19.4 mol%, and 45.8 mol%, respectively.

[0151] [Synthesis Examples 11-20] (Synthesis of second resin (A-2) to second resin (A-11)) Second resins (A-2) to (A-11) were synthesized in the same manner as in Synthesis Example 10, except that the monomers used were of the types and proportions shown in Table 1 below. The content percentage (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained second resins are also shown in Table 1 below. In Table 1 below, "-" indicates that the corresponding monomer was not used (the same applies to subsequent tables).

[0152] [Table 1]

[0153] [Synthesis Example 21] (Synthesis of the second resin (A-12)) Monomer (M-1) and monomer (M-18) were dissolved in 1-methoxy-2-propanol (200 parts by mass) to a molar ratio of 50 / 50 (mol%), and AIBN (5 mol%) was added as an initiator to prepare a monomer solution. 100 parts by mass of 1-methoxy-2-propanol was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours 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 the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The cooled polymerization solution was added to hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane, filtered again, 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 the hydrolysis reaction was carried out at 70°C for 6 hours with stirring. After the reaction was complete, the residual solvent was removed by distillation, and the obtained solid was dissolved in acetone (100 parts by mass) and added dropwise to water (500 parts by mass) to solidify the resin. The obtained solid was filtered off and dried at 50°C for 13 hours to obtain a white powdery second resin (A-12) (yield: 75%). The Mw of the second resin (A-12) was 6,100, and the Mw / Mn ratio was 1.49. 131C-NMR analysis revealed that the content of each structural unit derived from (M-1) and (M-18) was 49.2 mol% and 50.8 mol%, respectively.

[0154] [Synthesis Examples 22-24] (Synthesis of second resin (A-13) to second resin (A-15)) Second resins (A-13) to (A-15) were synthesized in the same manner as in Synthesis Example 21, except that monomers of the types and proportions shown in Table 2 below were used. The content percentage (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained resins are also shown in Table 2 below.

[0155] [Table 2]

[0156] [Synthesis Example 25] (Synthesis of the first resin (E-1)) Monomers (F-1), (fa-4), and (M-1) were dissolved in 200 parts by mass of 2-butanone in a molar ratio of 45 / 45 / 10 (mol%), and AIBN (2 mol%) was added as an initiator to prepare monomer solutions. 200 parts by mass of 2-butanone was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the temperature inside the reaction vessel was raised to 80°C, and the monomer solutions were 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 the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The solvent was replaced with acetonitrile (400 parts by mass), and hexane (100 parts by mass) was added and stirred, and the acetonitrile layer was recovered. This process was repeated three times. By replacing the solvent with propylene glycol monomethyl ether acetate, a solution of the first resin (E-1) was obtained (yield: 69%). The Mw of the first resin (E-1) was 10,600, and the Mw / Mn ratio was 1.54. Also, 13 1C-NMR analysis revealed that the content of each structural unit derived from (F-1), (fa-4), and (M-1) was 44.6 mol%, 45.8 mol%, and 9.6 mol%, respectively.

[0157] [Synthesis Examples 26-83] (Synthesis of the first resin lipids (E-2) to (E-47) and (CE-1) to (CE-12)) The first resins (E-2) to (E-47) and (CE-1) to (CE-12) were synthesized in the same manner as in Synthesis Example 25, except that the types, monomer proportions, and polymerization initiator proportions shown in Tables 3 and 4 below were changed. The content percentage (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained first resins are shown in accordance with Tables 3 and 4 below.

[0158] [Table 3]

[0159] [Table 4]

[0160] <Preparation of radiation-sensitive resin composition> The components other than [A] second resin and [E] first resin used in the preparation of each radiation-sensitive resin composition are shown below.

[0161] [[B] Radiation-sensitive acid generator] B-1 to B-8: Compounds represented by the following formulas (B-1) to (B-8)

[0162] [ka]

[0163] [[C] Acid diffusion inhibitor] C-1 to C-7: Compounds represented by the following formulas (C-1) to (C-7).

[0164] [ka]

[0165] [[D] Solvent] D-1: Propylene glycol monomethyl ether acetate D-2: Propylene glycol monomethyl ether D-3: γ-butyrolactone D-4: Ethyl lactate

[0166] [Preparation of Positive-Type Radiation-Sensitive Resin Composition for ArF Exposure] [Example 1] 100 parts by mass of (A-1) as the [A] second resin, 10.0 parts by mass of (B-1) as the [B] radiation-sensitive acid generator, 2.0 parts by mass of (C-1) as the [C] acid diffusion controller, 5.0 parts by mass (solid content) of (E-1) as the [E] first resin, and 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) as the [D] solvent were mixed, and the mixture was filtered through a membrane filter with a pore size of 0.2 µm, thereby preparing a radiation-sensitive resin composition (J-1).

[0167] [Examples 2 to 75 and Comparative Examples 1 to 12] Radiation-sensitive resin compositions (J-2) to (J-75) and (CJ-1) to (CJ-12) were prepared in the same manner as in Example 1, except that each component of the type and content shown in the following Tables 5-1 and 5-2 was used.

[0168]

Table 5-1

[0169]

Table 5-2

[0170] <Formation of Resist Pattern Using Positive-Type Radiation-Sensitive Resin Composition for ArF Exposure> On a 12-inch silicon wafer, a base layer anti-reflective coating composition (Brewer Science's "ARC66") was applied using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 100 nm. On this base layer anti-reflective coating, the ArF exposure positive-type radiation-sensitive resin composition (J-1) prepared above was applied using the same spin coater, and pre-bake (PB) was performed at 100°C for 60 seconds. Subsequently, a resist film with an average thickness of 90 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an ArF excimer laser immersion lithography system (ASML's "TWINSCAN XT-1900i") under optical conditions of NA=1.35 and Dipole (σ=0.9 / 0.7) through a 40 nm line-and-space mask pattern. After exposure, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was alkaline developed using a 2.38% by mass aqueous TMAH solution as the alkaline developer. After development, it was washed with water and then dried to form a positive-type resist pattern (40 nm line and space pattern).

[0171] <Rating> The sensitivity, LWR performance, storage stability, and number of defects after development of resist patterns formed using the above-described positive-type radiation-sensitive resin composition for ArF exposure were evaluated according to the methods described below. Furthermore, the receding contact angle of the resist film before ArF exposure was evaluated according to the methods described below. The results are shown in Tables 6-1 and 6-2 below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns.

[0172] [sensitivity] In forming a resist pattern using the above-mentioned positive-type radiation-sensitive resin composition for ArF exposure, the exposure amount for forming a 40 nm line-and-space pattern is defined as the optimal exposure amount, and this optimal exposure amount is set to the sensitivity (mJ / cm²). 2 The sensitivity was set to 30 mJ / cm². 2 The following cases are considered "good" and 30 mJ / cm².2 If it exceeded this value, it was rated as "poor."

[0173] [LWR performance] The mask size was adjusted to form a 40 nm line-and-space pattern by irradiating with the optimal exposure amount determined in the sensitivity evaluation above, and a resist pattern was formed. The formed resist pattern was observed from the top of the pattern using the scanning electron microscope described above. The line width variation was measured at a total of 500 points, and the 3-sigma value was determined from the distribution of these measurements. This 3-sigma value was defined as LWR (nm). A smaller LWR value indicates less line roughness and better performance. LWR performance was evaluated as "good" if it was 3.0 nm or less, and "poor" if it was greater than 3.0 nm.

[0174] [Receding contact angle after pre-bake (PB)] For the resist film before ArF exposure in the resist pattern formation method described above, the receding contact angle was measured using a KRUS DSA-10 under the following procedure in an environment of room temperature (23°C), relative humidity (40%), and atmospheric pressure.

[0175] Water was discharged from the DSA-10 needle to form a 25 μL droplet on the resist film. The droplet was then aspirated at a rate of 10 μL / min for 90 seconds using the needle, while the contact angle was measured every second (90 times in total). In this measurement, the average value of the contact angles at a total of 20 points from the point where the contact angle stabilized was calculated and defined as the post-PB recession contact angle (°). A post-PB recession contact angle of 70° or higher was evaluated as "good," and a value below 70° was evaluated as "poor."

[0176] [Storage stability] The above-mentioned radiation-sensitive resin composition for ArF exposure was stored at 40°C for one month, and the receding contact angle after PB was evaluated in the same manner as described above. If the rate of change expressed by the following formula was 0.5% or less, it was evaluated as "A" (excellent); if it was between 0.5% and 1.0%, it was evaluated as "B" (good); and if it was greater than 1.0%, it was evaluated as "C" (poor). Rate of change (%) = {(θ0 - θ1) / θ0} × 100 (where θ0 is the receding contact angle before storage, and θ1 is the receding contact angle after storage for 1 month.)

[0177] [Number of development defects] A resist film was exposed at an optimal exposure dose to form a line-and-space pattern with a line width of 40 nm, which was used as a wafer for defect inspection. The number of defects on this wafer for defect inspection was measured using a defect inspection apparatus ("KLA2810" manufactured by KLA-Tencor). Defects with a diameter of 50 µm or less were determined to be derived from the resist film, and the number of such defects was calculated. The number of defects after development was evaluated as "Good" when the number of defects determined to be derived from the resist film was 50 or less, and as "Poor" when the number exceeded 50.

[0178] [Table 6-1]

[0179] [Table 6-2]

[0180] As is clear from the results of Table 6-1 and Table 6-2, when the radiation-sensitive resin compositions of the Examples were used for ArF exposure, the sensitivity, LWR performance, receding contact angle after PB, storage stability, and number of development defects were all favorable. In contrast, each characteristic of the Comparative Examples was inferior to that of the Examples. Therefore, when the radiation-sensitive resin composition of the Example is used for ArF exposure, a resist pattern with high sensitivity, excellent water repellency, storage stability, and defect performance can be formed.

[0181] [Preparation of Positive-Type Radiation-Sensitive Resin Composition for Extreme Ultraviolet (EUV) Exposure] [Example 76] 100 parts by mass of (A-12) as the [A] second resin, 15.0 parts by mass of (B-5) as the [B] radiation-sensitive acid generator, 10.0 parts by mass of (C-5) as the [C] acid diffusion controller, 3.0 parts by mass (solid content) of (E-1) as the [E] first resin, and 6,110 parts by mass of a mixed solvent of (D-1) / (D-4) as the [D] solvent were mixed, and filtered through a membrane filter with a pore diameter of 0.2 μm to prepare a radiation-sensitive resin composition (J-76).

[0182] [Examples 77 to 91 and Comparative Examples 13 to 19] Radiation-sensitive resin compositions (J-77) to (J-91) and (CJ-13) to (CJ-19) were prepared in the same manner as in Example 76, except that each component of the type and content shown in Table 7 below was used.

[0183]

Table 7

[0184] <Formation of resist pattern using positive-type radiation-sensitive resin composition for EUV exposure> On a 12-inch silicon wafer, a base layer anti-reflective coating composition (Brewer Science's "ARC66") was applied using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 105 nm. The radiation-sensitive resin composition for EUV exposure prepared above was applied to this base layer anti-reflective coating using the same spin coater, and PB was performed at 130°C for 60 seconds. Subsequently, a resist film with an average thickness of 55 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an EUV exposure apparatus (ASML's "NXE3300") with NA=0.33, illumination conditions: Conventional s=0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120°C for 60 seconds. Subsequently, the resist film was alkaline-developed using a 2.38% by mass aqueous TMAH solution as the alkaline developer. After development, it was washed with water and then dried to form a positive-type resist pattern (32 nm line and space pattern).

[0185] <Rating> The resist patterns formed using the above-mentioned positive-type radiation-sensitive resin composition for EUV exposure were evaluated for sensitivity, LWR performance, storage stability, receding contact angle, and number of defects after development according to the method described below. The results are shown in Table 8 below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns.

[0186] [sensitivity] In forming a resist pattern using the above-mentioned positive-type radiation-sensitive resin composition for EUV exposure, the exposure amount for forming a 32nm line-and-space pattern is defined as the optimal exposure amount, and this optimal exposure amount is set to the sensitivity (mJ / cm²). 2 The sensitivity was set to 25 mJ / cm². 2 The following cases are considered "good" and 25 mJ / cm². 2 If it exceeded this value, it was rated as "poor."

[0187] [LWR performance] The mask size was adjusted to form a 32nm line-and-space pattern by irradiating with the optimal exposure amount determined in the sensitivity evaluation described above, and a resist pattern was formed. The formed resist pattern was observed from the top of the pattern using the scanning electron microscope described above. The line width variation was measured at a total of 500 points, and the 3-sigma value was determined from the distribution of these measurements. This 3-sigma value was defined as LWR (nm). A smaller LWR value indicates less line roughness and better performance. LWR performance was evaluated as "good" if it was 3.0nm or less, and "poor" if it was greater than 3.0nm.

[0188] [Receding contact angle after pre-bake (PB)] For the resist film before EUV exposure in the resist pattern formation method described above, the receding contact angle was measured using a KRUS DSA-10 under the following procedure in an environment of room temperature (23°C), relative humidity (40%), and atmospheric pressure.

[0189] Water was discharged from the DSA-10 needle to form a 25 μL droplet on the resist film. The droplet was then aspirated at a rate of 10 μL / min for 90 seconds using the needle, while the contact angle was measured every second (90 times in total). In this measurement, the average value of the contact angles at a total of 20 points from the point where the contact angle stabilized was calculated and defined as the post-PB recession contact angle (°). A post-PB recession contact angle of 70° or higher was evaluated as "good," and a value below 70° was evaluated as "poor."

[0190] [Storage stability] The above radiation-sensitive resin composition for EUV exposure was stored at 40°C for one month, and the receding contact angle after PB was evaluated in the same manner as described above. If the rate of change expressed by the following formula was 0.5% or less, it was evaluated as "A" (excellent); if it was between 0.5% and 1.0%, it was evaluated as "B" (good); and if it was greater than 1.0%, it was evaluated as "C" (poor). Rate of change (%) = {(θ0 - θ1) / θ0} × 100 (θ0 is the receding contact angle before storage, and θ1 is the receding contact angle after one month of storage.)

[0191] [Number of development defects] A resist film was exposed at the optimum exposure dose to form a 32 nm line-and-space pattern, which was used as a defect inspection wafer. The number of defects on this defect inspection wafer was measured using a defect inspection apparatus ("KLA2810" manufactured by KLA-Tencor). Defects with a diameter of 50 µm or less were determined to be derived from the resist film, and the number thereof was calculated. The number of post-development defects was evaluated as "Good" when the number of defects determined to be derived from the resist film was 50 or less, and "Poor" when the number exceeded 50.

[0192] Table 8

[0193] As is clear from the results in Table 8, when the radiation-sensitive resin composition of the Examples was used for EUV exposure, sensitivity, LWR performance, receding contact angle after PB, storage stability and the number of development defects were all favorable, whereas each property in the Comparative Examples was inferior to that in the Examples. Therefore, when the radiation-sensitive resin composition of the Examples is used for EUV exposure, a resist pattern having high sensitivity, good water repellency, good storage stability and good defect performance can be formed.

[0194] [Preparation of negative-type radiation-sensitive resin composition for ArF exposure, formation and evaluation of resist pattern using the composition] [Example 92] [A] 100 parts by mass of (A-1) as a second resin, [B] 10.0 parts by mass of (B-7) as a radiation-sensitive acid generator, [C] 4.0 parts by mass of (C-3) as an acid diffusion controller, [E] 5.0 parts by mass (solid content) of (E-6) as a first resin, and [D] 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) as a solvent (mass ratio: 2240 parts / 960 parts / 30 parts) were mixed, and filtered through a membrane filter with a pore diameter of 0.2 µm to prepare a radiation-sensitive resin composition (J-92).

[0195] On a 12-inch silicon wafer, a base layer anti-reflective coating composition (Brewer Science's "ARC66") was applied using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 100 nm. On this base layer anti-reflective coating, the ArF exposure negative-type radiation-sensitive resin composition (J-92) prepared above was applied using the same spin coater, and pre-bake (PB) was performed at 100°C for 60 seconds. Subsequently, a resist film with an average thickness of 90 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an ArF excimer laser immersion lithography system (ASML's "TWINSCAN XT-1900i") under optical conditions of NA=1.35 and Annular (σ=0.8 / 0.6) through a mask pattern with 40 nm holes and a 105 nm pitch. After exposure, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was developed using n-butyl acetate as the organic solvent developer and dried to form a negative-type resist pattern (40 nm holes, 105 nm pitch).

[0196] The sensitivity, receding contact angle after PB, number of defects after development, and storage stability of the resist pattern and the resist film before ArF exposure using the above-mentioned negative-type radiation-sensitive resin composition for ArF exposure were evaluated in the same manner as the evaluation of the resist pattern using the above-mentioned positive-type radiation-sensitive resin composition for ArF exposure. As a result, the radiation-sensitive resin composition of Example 92 showed high sensitivity, good receding contact angle after PB, number of defects after development, and good storage stability, even when a negative-type resist pattern was formed by ArF exposure.

[0197] [Preparation of negative-type radiation-sensitive resin composition for EUV exposure, formation and evaluation of resist patterns using this composition] [Example 93] A radiation-sensitive resin composition (J-93) was prepared by mixing [A] 100 parts by mass of (A-12) as a second resin, [B] 21.0 parts by mass of (B-8) as a radiation-sensitive acid generator, [C] 5.0 parts by mass of (C-6) as an acid diffusion control agent, [E] 3.0 parts by mass (solids) of (E-10) as a first resin, and [D] 6,110 parts by mass (mass ratio 4280 parts / 1830 parts) of a mixed solvent of (D-1) / (D-4) as a solvent, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0198] On a 12-inch silicon wafer, a base layer anti-reflective coating composition (Brewer Science's "ARC66") was applied using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 105 nm. On this base layer anti-reflective coating, the prepared EUV exposure negative-type radiation-sensitive resin composition (J-93) was applied using the same spin coater, and PB was performed at 130°C for 60 seconds. Subsequently, a resist film with an average thickness of 55 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an EUV exposure apparatus (ASML's "NXE3300") with NA=0.33, illumination conditions: Conventional s=0.89, and mask: imecDEFECT32FFR15. After exposure, PEB was performed at 120°C for 60 seconds. Subsequently, the resist film was developed using n-butyl acetate as the organic solvent developer and dried to form a negative-type resist pattern (40 nm holes, 105 nm pitch).

[0199] The resist patterns using the above-mentioned negative-type radiation-sensitive resin composition for EUV exposure were evaluated in the same manner as the resist patterns using the above-mentioned negative-type radiation-sensitive resin composition for ArF exposure. As a result, the radiation-sensitive resin composition of Example 93 showed good sensitivity, receding contact angle after PB, number of defects after development, and storage stability even when a negative-type resist pattern was formed by EUV exposure. [Industrial applicability]

[0200] According to the radiation-sensitive resin composition and pattern-forming method of the present invention, the composition exhibits excellent storage stability, good sensitivity to exposure light, excellent LWR performance and water repellency, and can form a resist pattern with few defects. Therefore, these can be suitably used in the processing of semiconductor devices, which are expected to become even more miniaturized in the future.

Claims

1. A first resin comprising a structural unit (I) represented by the following formula (1), a structural unit (II) represented by the following formula (2) (excluding the structural unit represented by the following formula (1)), and a structural unit (III) having an acid-dissociable group represented by the following formula (3), A second resin containing a structural unit having an acid-dissociable group, and having a lower mass content of fluorine atoms than the first resin, A radiation-sensitive acid generator, Solvent and A radiation-sensitive resin composition containing [a specific substance]. 【Chemistry 1】 (In the above formula (1), R Ｋ１ These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L １ This is an alkanediyl group having 1 to 5 carbon atoms. R ｆ１ This is a monovalent fluorinated hydrocarbon group having 2 to 10 carbon atoms and containing 5 to 7 fluorine atoms. In the above formula (2), R Ｋ２ These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L ｆ This is a fluorine-substituted or unsubstituted divalent organic group having 1 to 20 carbon atoms. L ２ teeth, ＊ -COO-. * is L ｆ It is a side joint. p is 1 or 2. When L ｆ and L ２ exist in plurality, the plurality of L ｆ and L ２ are each the same as or different from each other. R ｆ２ This is a fluorine-substituted or unsubstituted monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a fluorine-substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, or a combination thereof. However, L ｆ and R ｆ２ It has a total of one or more fluorine atoms, L ２ (At least one carbon atom adjacent to the carbonyl group in the compound is bonded to one or two fluorine atoms or trifluoromethyl groups.) 【Chemistry 2】 (In the above formula (3), R ７ These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ８ It is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ９ and R １０ (This represents a divalent monocyclic alicyclic hydrocarbon group with 3 to 20 carbon atoms, which can be combined with other carbon atoms to which they are bonded.)

2. In the above formula (1), R ｆ１ The radiation-sensitive resin composition according to claim 1, wherein is a monovalent fluorinated linear hydrocarbon group having 2 to 4 carbon atoms and having 5 fluorine atoms.

3. In the above formula (1), L １ The radiation-sensitive resin composition according to claim 1, wherein is a methanediyl group or an ethanediyl group.

4. A radiation-sensitive resin composition according to any one of claims 1 to 3, further comprising an acid diffusion control agent.

5. 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 3 to a substrate, The process of exposing the above-mentioned resist film, The process involves developing the exposed resist film with a developer solution. A pattern formation method including the following.

6. The pattern formation method according to claim 5, wherein the development is carried out using an alkaline aqueous solution.

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