Sulfonium salt compounds and radiation-sensitive acid generators containing them

Abstract

The present invention provides a method for forming a resist pattern and a radiation-sensitive resin composition that exhibit excellent performance in terms of sensitivity, LWR performance, CDU performance, etc., during the exposure process, even when next-generation exposure technology is applied. [Solution] A sulfonium salt compound represented by the following formula (1), JPEG2026067953000035.jpg38170 A radiation-sensitive resin composition containing a resin having an acid-dissociable structural unit, and a solvent.

Description

[Technical Field]

[0001] The present invention relates to a radiation-sensitive resin composition and a method for forming a resist pattern using the same, as well as a sulfonium salt compound and a radiation-sensitive acid generator containing the same. [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 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, and further advance pattern miniaturization by employing liquid immersion lithography, a method in which exposure is performed with the space between the lens of the exposure apparatus and the resist film filled with a liquid medium. As next-generation technologies, lithography using even shorter-wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet) is also being considered.

[0004] With advancements in exposure technology, attempts are being made to improve the sensitivity and resolution of photoacid generators, which are the main components of resist compositions. A photosensitive composition has been proposed that has pattern resolution from micron units to submicron units, comprising a hydroxystyrene polymer with high plasma etching resistance and a photoacid generator in which the carbon bonded to the sulfonium group is a secondary or tertiary carbon (Patent Document 1).

[0005] Furthermore, in the ArF generation, resins with a less absorbent alicyclic structure as a protecting group are used instead of hydroxystyrene polymers. However, the photoacid generators used in combination with the above-mentioned hydroxystyrene polymers have insufficient acid strength to promote the deprotection of resins with alicyclic structures. Therefore, an acid generator in which the proximal carbon of the sulfonium group is substituted with fluorine has been put into practical use as a photoacid generator that provides an acid with sufficient acid strength for deprotection (Patent Document 2). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 10-10715 [Patent Document 2] Japanese Patent Publication No. 2002-214774 [Overview of the project] [Problems that the invention aims to solve]

[0007] In recent years, as resist patterns have become increasingly miniaturized, there is a growing demand for further improvements in the resolution mentioned above. This demand includes further improvements in various resist properties, such as sensitivity during the exposure process, line width roughness (LWR) performance (indicating variations in the line width of the resist pattern), and CDU performance. Furthermore, next-generation exposure technologies such as electron beam lithography require resist properties equivalent to or better than those mentioned above. However, conventional radiation-sensitive resin compositions have not been able to achieve all of these properties at a sufficient level. [Means for solving the problem]

[0008] The inventors of this invention conducted extensive research to solve this problem and, as a result, discovered that the above objective can be achieved by using a sulfonium salt compound with a specific structure, thus completing the present invention.

[0009] For example, in one embodiment, the present invention A sulfonium salt compound represented by the following formula (1) (hereinafter also referred to as "compound (1)"), [Chemical formula] (In the formula, R 2 , 8’ , 2 , 8 , f1 , 4 , 4 , 3 , 3 , f2 , 8 , 8’ , 7 , 7 is a monovalent hydrocarbon group having a cyclic structure, and the methylene groups constituting the hydrocarbon group may be replaced by ether bonds. R f1 and R f2 are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group. m1 is an integer from 1 to 4. When m1 is 2 to 4, a plurality of R f1 and R f2 are partly or wholly the same or different. R 2 and R 3 are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group, or a monovalent fluorinated hydrocarbon group. m2 is an integer from 0 to 3. When m2 is 2 to 3, a plurality of R 2 and R 3 are partly or wholly the same or different. X is a single bond or a linker containing a divalent heteroatom. R 4 ~R 7 are each independently a hydrogen atom, a hydroxyl group, a monovalent hydrocarbon group, or an ester group. n 1 and n 2 are each independently an integer from 1 to 3, and a plurality of R 4 ~R 7 are partly or wholly the same or different. R 8 is a monovalent chain hydrocarbon group, a monovalent alicyclic hydrocarbon group, a monovalent fluorinated hydrocarbon group, a halogen atom, a monovalent aromatic hydrocarbon group, or a monovalent group represented by -Y-R 8’ (Y represents -O-, -CO-, -COO-, -OCO-, and R 8’ is a monovalent hydrocarbon group having 1 to 20 carbon atoms.) l is an integer from 0 to 5. When l is 2 to 5, a plurality of R 8 are partly or wholly the same or different.) A resin containing a structural unit having an acid-dissociable group, and solvent This invention relates to a radiation-sensitive resin composition containing [a specific substance].

[0010] The radiation-sensitive resin composition contains a sulfonium salt compound represented by formula (1) above, a resin containing a structural unit having an acid-dissociable group, and a solvent. Therefore, resist films using this composition can exhibit excellent levels of sensitivity, LWR performance, CDU performance, and other properties during the exposure process. The mechanism by which the above effects are achieved is not clear, and this inference does not necessarily limit the scope of the present invention. However, it is presumed that the radiation-sensitive resin composition favorably improves various resist properties by containing a sulfonium salt compound of a specific structure with improved hydrophobicity and strong acidity.

[0011] Furthermore, in other embodiments, the present invention A step of forming a resist film by directly or indirectly applying the above radiation-sensitive resin composition onto a substrate. The steps of exposing the resist film and The present invention relates to a method for forming a resist pattern, which includes the step of developing the exposed resist film.

[0012] The resist pattern formation method includes a step of directly or indirectly applying a radiation-sensitive resin composition containing a sulfonium salt compound represented by formula (1) above, a resin containing a structural unit having an acid-dissociable group, and a solvent onto a substrate to form a resist film. As a result, excellent levels of sensitivity in the exposure process, line width roughness (LWR) performance (indicating variation in the line width of the resist pattern), and CDU performance can be achieved. The mechanism of action by which the above effects are manifested is not clear, and this inference does not necessarily limit the scope of the present invention. However, it is inferred that the resist pattern formation method suitably improves the resist performance by using a radiation-sensitive resin composition containing a sulfonium salt compound of a specific structure with improved hydrophobicity and strong acidity.

[0013] Furthermore, in other embodiments, the present invention This relates to sulfonium salt compounds represented by the following formula (1). [ka] (In the formula, R 1 This is a monovalent hydrocarbon group having a cyclic structure, and the methylene group constituting the hydrocarbon group may be replaced by an ether bond. R f1 and R f2 Each of these is independently either a fluorine atom or a monovalent fluorinated hydrocarbon group. m1 is an integer from 1 to 4, and if m1 is from 2 to 4, multiple R f1 and R f2 They are either identical or different in part or in whole. R 2 and R 3 Each of these is independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group, or a monovalent fluorinated hydrocarbon group. m2 is an integer between 0 and 3, and if m2 is between 2 and 3, multiple R 2 and R 3 They are either identical or different in part or in whole. X is a linker containing a single bond or a divalent heteroatom. R 4 ~R 7 Each of these is independently a hydrogen atom, a hydroxyl group, a monovalent hydrocarbon group, or an ester group. n1 and n2 are each independent integers between 1 and 3, and multiple R 4 ~R 7 They are either identical or different in part or in whole. R 8 This includes monovalent linear hydrocarbon groups, monovalent alicyclic hydrocarbon groups, monovalent fluorinated hydrocarbon groups, halogen atoms, monovalent aromatic hydrocarbon groups, or -YR 8’ It is a monovalent group represented by (Y represents -O-, -CO-, -COO-, -OCO-, R 8’ (It is a monovalent hydrocarbon group with 1 to 20 carbon atoms.) l is an integer from 0 to 5, and if l is from 2 to 5, multiple R 8(These are either identical or different in part or in whole.)

[0014] Since the sulfonium salt compound has the structure represented by formula (1) above, by using, for example, a radiation-sensitive resin composition or resist formation method containing it, it is possible to achieve excellent levels of sensitivity, LWR performance, CDU performance, etc., in the exposure process. The mechanism of action by which the above effect is achieved is not clear, and this inference does not necessarily limit the scope of the present invention, but it is inferred that the sulfonium salt compound acts as a suitable radiation-sensitive acid generator, for example, by using a radiation-sensitive resin composition containing a sulfonium salt compound of a specific structure with improved hydrophobicity and strong acidity, and as a result improves the various performances of the resist.

[0015] Furthermore, in other embodiments, the present invention This invention relates to a radiation-sensitive acid generator containing a sulfonium salt compound represented by the following formula (1). [ka] (In the formula, R 1 This is a monovalent hydrocarbon group having a cyclic structure, and the methylene group constituting the hydrocarbon group may be replaced by an ether bond. R f1 and R f2 Each of these is independently either a fluorine atom or a monovalent fluorinated hydrocarbon group. m1 is an integer from 1 to 4, and if m1 is from 2 to 4, multiple R f1 and R f2 They are either identical or different in part or in whole. R 2 and R 3 Each of these is independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group, or a monovalent fluorinated hydrocarbon group. m2 is an integer between 0 and 3, and if m2 is between 2 and 3, multiple R 2 and R 3 They are either identical or different in part or in whole. X is a linker containing a single bond or a divalent heteroatom. R 4 ~R 7 Each of these is independently a hydrogen atom, a hydroxyl group, a monovalent hydrocarbon group, or an ester group. n1 and n2 are each independent integers between 1 and 3, and multiple R 4 ~R 7 They are either identical or different in part or in whole. R 8 This includes monovalent linear hydrocarbon groups, monovalent alicyclic hydrocarbon groups, monovalent fluorinated hydrocarbon groups, halogen atoms, monovalent aromatic hydrocarbon groups, or -YR 8’ It is a monovalent group represented by (Y represents -O-, -CO-, -COO-, -OCO-, R 8’ (It is a monovalent hydrocarbon group with 1 to 20 carbon atoms.) l is an integer from 0 to 5, and if l is from 2 to 5, multiple R 8 (These are either identical or different in part or in whole.)

[0016] Since the radiation-sensitive acid generator has the structure represented by formula (1) above, by using, for example, a radiation-sensitive resin composition or resist formation method containing it, it is possible to achieve excellent levels of sensitivity, LWR performance, CDU performance, etc., in the exposure process. The mechanism of action by which the above effect is achieved is not clear, and this inference does not necessarily limit the scope of the present invention, but it is inferred that the above radiation-sensitive acid generator acts as a suitable radiation-sensitive acid generator by using a radiation-sensitive resin composition containing a sulfonium salt compound of a specific structure with improved hydrophobicity and strong acidity, and as a result improves the various performances of the resist. [Modes for carrying out the invention]

[0017] The embodiments of the present invention will be described in detail below, but the present invention is not limited to these embodiments.

[0018] <Radiation sensitive resin composition> The radiation-sensitive resin composition according to this embodiment (hereinafter also simply referred to as "the composition") comprises a resin (A), a sulfonium salt compound (B) (or a radiation-sensitive acid generator (B)), and a solvent (D). The above composition may contain other optional components as long as they do not impair the effects of the present invention.

[0019] (Resin (A)) Resin (A) is a resin containing a structural unit having an acid-dissociable group (hereinafter, this resin is also referred to as the "base resin"). Resin (A) is an aggregate of polymers having a structural unit containing an acid-dissociable group (hereinafter, also referred to as "structural unit (I)"). An "acid-dissociable group" is a group that substitutes a hydrogen atom, such as a carboxyl group, phenolic hydroxyl group, alcoholic hydroxyl group, or sulfo group, and dissociates upon the action of an acid. The radiation-sensitive resin composition exhibits excellent pattern-forming properties because the above resin contains structural unit (I).

[0020] The base resin preferably has structural unit (II) in addition to structural unit (I), which includes at least one selected from the group consisting of lactone structures, cyclic carbonate structures, and sultone structures, as described later, and may also have other structural units other than structural units (I) and (II). Each structural unit will be described below.

[0021] [Structural Unit (I)] Structural unit (I) is a structural unit containing an acid-dissociable group. Structural unit (I) is not particularly limited as long as it contains an acid-dissociable group, and examples include a structural unit having a tertiary alkyl ester moiety, a structural unit having a structure in which the hydrogen atom of a phenolic hydroxyl group is replaced by a tertiary alkyl group, and a structural unit having an acetal bond. However, from the viewpoint of improving the pattern-forming properties of the radiation-sensitive resin composition, a structural unit represented by the following formula (2) (hereinafter also referred to as "structural unit (I-1)") is preferred.

[0022] [ka] (In the formula, R 9This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 10 It is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R 11 and R 12 Each of these is independently a monovalent linear hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or R 11 and R 12 These are divalent alicyclic groups with 3 to 20 carbon atoms, formed by combining them with the carbon atoms to which they are bonded.

[0023] In the above equation (4), R 10 Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms, represented by this formula, include methyl groups and ethyl groups.

[0024] In the above equation (4), R 11 and R 12 Examples of monovalent chain hydrocarbon groups having 1 to 10 carbon atoms, represented by the formula, include, independently, a methyl group and an ethyl group.

[0025] In the above equation (4), R 11 and R 12 Examples of monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, represented by the formulas, include, independently, cyclopentyl groups and cyclohexyl groups.

[0026] In the above equation (4), R 11 and R 12 The divalent alicyclic group having 3 to 20 carbon atoms, which is formed when these are combined with each other and bonded together with the carbon atoms, is not particularly limited as long as it is a group obtained by removing two hydrogen atoms from the same carbon atom that constitutes the carbon ring of the hydrocarbon with the above number of carbon atoms.

[0027] Examples of structural units (I-1) include the structural units represented by the following formulas (3-1) to (3-6) (hereinafter also referred to as "structural units (I-1-1) to (I-1-6)").

[0028] [ka]

[0029] In the above equations (3-1) to (3-6), R 9 ~R 12 This is equivalent to equation (2) above. i' and j' are independent integers between 0 and 16. k' is between 0 and 1.

[0030] i' and j' are preferably 1. 10 A methyl group, an ethyl group, or an isopropyl group is preferred.

[0031] The base resin may contain one or more structural units (I) in combination.

[0032] The content of structural unit (I) (total content if multiple types are included) is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 30 mol% or more, and particularly preferably 35 mol% or more, relative to the total structural units constituting the base resin. Furthermore, it is preferably 80 mol% or less, more preferably 75 mol% or less, even more preferably 70 mol% or less, and particularly preferably 65 mol% or less. By setting the content of structural unit (I) within the above range, the pattern-forming properties of the radiation-sensitive resin composition can be further improved.

[0033] [Structural Units (II)] Structural unit (II) is a structural unit comprising at least one selected from the group consisting of lactone structures, cyclic carbonate structures, and sultone structures. By further comprising structural unit (II), the solubility of the base resin in the developer can be adjusted, and as a result, the radiation-sensitive resin composition can improve lithography performance such as resolution. Furthermore, the adhesion between the resist pattern formed from the base resin and the substrate can be improved.

[0034] Examples of structural units (II) include those represented by the following formulas (T-1) to (T-10).

[0035] [ka]

[0036] In the above formula, R L1 R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L2 ~R L5 These are, independently, a hydrogen atom, a C1-C4 alkyl group, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxyl group, a hydroxymethyl group, and a dimethylamino group. L4 and R L5 These may be divalent alicyclic groups having 3 to 8 carbon atoms, which can be combined with each other and formed together with the carbon atoms to which they are bonded. 2 is a single bond or a divalent linking group. X is an oxygen atom or a methylene group. k is an integer from 0 to 3. m is an integer from 1 to 3.

[0037] The above R L4 and R L5 When these are combined with each other, the divalent alicyclic group having 3 to 8 carbon atoms that is formed together with the carbon atoms to which they are bonded is R in formula (1) above. 8 Examples include divalent alicyclic groups with 3 to 8 carbon atoms, which are formed by combining chain-like hydrocarbon groups or alicyclic hydrocarbon groups represented by the formula, together with the carbon atoms to which they are bonded. One or more hydrogen atoms on this alicyclic group may be substituted with hydroxyl groups.

[0038] The above L 2 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-.

[0039] Among these, structural units (II) 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.

[0040] The content of structural unit (II) is preferably 20 mol% or more, more preferably 25 mol% or more, and even more preferably 30 mol% or more, relative to the total structural units constituting the base resin. Furthermore, it is preferably 80 mol% or less, more preferably 75 mol% or less, and even more preferably 70 mol% or less. By setting the content of structural unit (II) within the above range, the radiation-sensitive resin composition can further improve lithography performance such as resolution and the adhesion of the formed resist pattern to the substrate.

[0041] [Structural Unit (III)] The base resin may optionally contain other structural units in addition to the structural units (I) and (II) described above. Examples of these other structural units include structural unit (III) containing a polar group (excluding those corresponding to structural unit (II)). By further containing structural unit (III), the solubility of the base resin 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.

[0042] Examples of structural units (III) include structural units represented by the following formula.

[0043] [ka]

[0044] In the above formula, R A This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0045] When the base resin has structural unit (III) having the polar group described above, the content of structural unit (III) is preferably 5 mol% or more, more preferably 8 mol% or more, and even more preferably 10 mol% or more, relative to the total structural units constituting the base resin. Furthermore, it is preferably 40 mol% or less, more preferably 35 mol% or less, and even more preferably 30 mol% or less. By setting the content of structural unit (III) within the above range, the lithographic performance, such as resolution, of the radiation-sensitive resin composition can be further improved.

[0046] [Structural Units (IV)] The base resin may optionally contain structural units other than the polar group-containing structural unit (III) described above, such as structural units derived from hydroxystyrene or structural units containing phenolic hydroxyl groups (hereinafter, both are collectively referred to as "structural unit (IV)"). Structural unit (IV) contributes to improved etching resistance and improved difference in developer solubility between exposed and unexposed areas (dissolution contrast). In particular, it can be suitably applied to pattern formation using exposure with radiation of wavelengths of 50 nm or less, such as electron beams and EUV. In this case, it is preferable that the resin contains structural unit (I) along with structural unit (IV).

[0047] In this case, it is preferable to polymerize the phenolic hydroxyl group while protecting it with a protecting group such as an alkali-dissociable group, and then deprotect it by hydrolysis to obtain structural unit (IV). The structural unit that gives structural unit (IV) by hydrolysis is preferably represented by the following formulas (4-1) and (4-2).

[0048] [ka]

[0049] In the above equations (4-1) and (4-2), R 13 R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 14R is a monovalent hydrocarbon group or alkoxy group having 1 to 20 carbon atoms. 14 As monovalent hydrocarbon groups with 1 to 20 carbon atoms, R in structural unit (I) 10 Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms include alkoxy groups such as methoxy, ethoxy, and tert-butoxy groups.

[0050] The above R 14 Preferably, alkyl groups and alkoxy groups are used, with methyl groups and tert-butoxy groups being more preferred.

[0051] For resins used for exposure with radiation of wavelength 50 nm or less, the content of structural unit (IV) is preferably 10 mol% or more, more preferably 20 mol% or more, relative to the total structural units constituting the resin. Furthermore, it is preferably 70 mol% or less, and more preferably 60 mol% or less.

[0052] (Method of synthesizing resin (A)) The above resin (A) can be synthesized, for example, by polymerizing monomers that give each structural unit in a suitable solvent using a radical polymerization initiator or the like.

[0053] Examples of the radical polymerization initiators mentioned above include azo-based radical polymerization 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 polymerization initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Among these, AIBN and dimethyl-2,2'-azobisisobutyrate are preferred, with AIBN being more preferred. These radical polymerization initiators can be used individually or in combination of two or more.

[0054] Examples of solvents used in the polymerization described above include Alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, and norbornane; Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene; Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, and chlorobenzene; Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate, and methyl propionate; Ketones such as acetone, methyl ethyl ketone, 4-methyl-2-pentanone, and 2-heptanone; Ethers such as tetrahydrofuran, dimethoxyethanes, and diethoxyethanes; Examples of solvents include methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2-pentanol, and other alcohols. The solvent used in these polymerizations may be used alone or in combination of two or more.

[0055] The reaction temperature in the above polymerization is typically 40°C to 150°C, with 50°C to 120°C being preferred. The reaction time is typically 1 hour to 48 hours, with 1 hour to 24 hours being preferred.

[0056] The molecular weight of the base resin is not particularly limited, but the polystyrene-equivalent weight-average molecular weight (Mw) determined by gel permeation chromatography (GPC) is preferably 1,000 to 50,000, more preferably 2,000 to 30,000, even more preferably 3,000 to 15,000, and particularly preferably 4,000 to 12,000. If the Mw of the base resin is below the lower limit, the heat resistance of the resulting resist film may decrease. If the Mw of the base resin exceeds the upper limit, the developability of the resist film may decrease.

[0057] 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.

[0058] The Mw and Mn values ​​of resin A described above are measured using gel permeation chromatography (GPC) under the following conditions.

[0059] GPC columns: 2 x G2000HXL, 1 x G3000HXL, 1 x G4000HXL (all manufactured by Tosoh Corporation) Column temperature: 40℃ Leaching solvent: Tetrahydrofuran Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0060] The base resin content is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 75% by mass or more, relative to the total solid content of the radiation-sensitive resin composition.

[0061] (Other resins) The radiation-sensitive resin composition of this embodiment may also contain, as another resin, a resin with a higher mass content of fluorine atoms than the base resin (hereinafter also referred to as "high-fluorine content resin"). When the radiation-sensitive resin composition contains a high-fluorine content resin, it can be unevenly distributed on the surface of the resist film relative to the base resin, and as a result, the water repellency of the surface of the resist film during immersion exposure can be improved.

[0062] The high-fluorine-content resin preferably has a structural unit represented by the following formula (5) (hereinafter also referred to as "structural unit (V)"), and may also have structural unit (I) or structural unit (II) of the base resin as needed.

[0063] [Chemical]

[0064] In the above formula (5), R 15 is a hydrogen atom, a methyl group or a trifluoromethyl group. G L is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2ONH-, -CONH- or -OCONH-. R 16 is a monovalent fluorinated linear hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0065] As the above R 15 from the viewpoint of the copolymerizability of the monomer that gives the structural unit (V), a hydrogen atom and a methyl group are preferred, and a methyl group is more preferred.

[0066] As the above G L [[ID=2S]]from the viewpoint of the copolymerizability of the monomer that gives the structural unit (V), a single bond and -COO- are preferred, and -COO- is more preferred.

[0067] As the monovalent fluorinated linear hydrocarbon group having 1 to 20 carbon atoms represented by the above R 16 it is possible to give those in which some or all of the hydrogen atoms of a linear or branched alkyl group having 1 to 20 carbon atoms are substituted by fluorine atoms.

[0068] As the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above R 16 it is possible to give those in which some or all of the hydrogen atoms of a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms are substituted by fluorine atoms. [[ID=3N]]

[0069] As the above R 16 a fluorinated linear hydrocarbon group is preferred, a fluorinated alkyl group is more preferred, and a 2,2,2-trifluoroethyl group, a 1,1,1,3,3,3-hexafluoropropyl group and a 5,5,5-trifluoro-1,1-diethylpentyl group are even more preferred.

[0070] When a high-fluorine-content resin has structural units (V), the content of structural units (V) is preferably 30 mol% or more, more preferably 40 mol% or more, even more preferably 45 mol% or more, and particularly preferably 50 mol% or more, relative to the total structural units constituting the high-fluorine-content resin. Furthermore, it is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less. By setting the content of structural units (V) within the above range, the mass content of fluorine atoms in the high-fluorine-content resin can be more appropriately adjusted, further promoting the uneven distribution to the surface layer of the resist film, and as a result, the water repellency of the resist film during immersion exposure can be further improved.

[0071] High-fluorine content resins may have fluorine atom-containing structural units (hereinafter also referred to as structural unit (VI)) represented by the following formula (f-2), either together with or in place of structural unit (V). The presence of structural unit (f-2) in high-fluorine content resins improves solubility in alkaline developers and suppresses the occurrence of development defects.

[0072] [ka]

[0073] Structural units (VI) can be broadly classified into two types: (x) those having an alkali-soluble group, and (y) those having a group that dissociates upon the action of alkali, increasing its solubility in an alkaline developer (hereinafter also simply referred to as an "alkali-dissociable group"). In both (x) and (y), in the above formula (f-2), R C R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. D This is a single bond, a (s+1) valent hydrocarbon group with 1 to 20 carbon atoms, and the R of this hydrocarbon group E At the terminal end of the side are an oxygen atom, a sulfur atom, and -NR dd -, a structure to which a carbonyl group, -COO-, or -CONH- is bonded, or a structure in which some of the hydrogen atoms of this hydrocarbon group are replaced by an organic group having a heteroatom. ddis a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer of 1 to 3.

[0074] When the structural unit (VI) has an (x) alkali-soluble group, R F is a hydrogen atom, and A 1 is an oxygen atom, -COO-*, or -SO2O-*. * indicates the site bonded to R F W 1 is a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group. When A 1 is an oxygen atom, W 1 is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group at the carbon atom to which A 1 is bonded. R E is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, a plurality of R E W 1 A 1 and R F may be the same or different from each other. By having the (x) alkali-soluble group in the structural unit (VI), the affinity for the alkali developer can be increased, and development defects can be suppressed. As the structural unit (VI) having the (x) alkali-soluble group, it is particularly preferable when A 1 is an oxygen atom and W 1 is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.

[0075] When the structural unit (VI) has a (y) alkali-dissociable group, R F is a monovalent organic group having 1 to 30 carbon atoms, and A 1 is an oxygen atom, -NR aa -, -COO-*, or -SO2O-*. R aa is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * indicates the site bonded to R F W 1 is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R E is a single bond or a divalent organic group having 1 to 20 carbon atoms. When A 1 is -COO-* or -SO2O-*, W 1or R F is A 1 It has a fluorine atom on the carbon atom bonded to it or on an adjacent carbon atom. 1 If is an oxygen atom, then W 1 , R E It is a single bond, R D R is a hydrocarbon group with 1 to 20 carbon atoms. E It is a structure in which a carbonyl group is bonded to the terminal end, R F is an organic group containing a fluorine atom. When s is 2 or 3, multiple R E , W 1 , A 1 and R F These may be the same or different. The presence of (y) an alkali-dissociable group in structural unit (VI) causes the resist film surface to change from hydrophobic to hydrophilic during the alkali development process. As a result, the affinity for the developer is significantly increased, and development defects can be suppressed more efficiently. Examples of structural unit (VI) having (y) an alkali-dissociable group include A 1 is -COO-*, R F Or W 1 Alternatively, it is particularly preferable that both of these contain fluorine atoms.

[0076] R C From the viewpoint of copolymerizability of the monomer that gives structural unit (VI), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0077] R E When the group is a divalent organic group, a group having a lactone structure is preferred, a group having a polycyclic lactone structure is more preferred, and a group having a norbornane lactone structure is even more preferred.

[0078] When a high-fluorine-content resin has structural units (VI), the content of structural units (VI) is preferably 50 mol% or more, more preferably 60 mol% or more, and even more preferably 70 mol% or more, relative to the total structural units constituting the high-fluorine-content resin. Furthermore, it is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less. By setting the content of structural units (VI) within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0079] [Other structural units] High-fluorine resins may also contain structural units having an alicyclic structure represented by the following formula (6), in addition to the structural units listed above. [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.)

[0080] In the above formula (6), R 2α Examples of monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, represented by , include those in which some or all of the hydrogen atoms in a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms are substituted with fluorine atoms.

[0081] When a high-fluorine-content resin contains structural units having the above-mentioned alicyclic structure, the content of these structural units is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more, relative to the total structural units constituting the high-fluorine-content resin. Furthermore, it is preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less.

[0082] The lower limit of Mw for the high-fluorine-content resin is preferably 1,000, more preferably 2,000, even more preferably 3,000, and particularly preferably 5,000. The upper limit of Mw is preferably 50,000, more preferably 30,000, even more preferably 20,000, and particularly preferably 15,000.

[0083] The lower limit of the Mw / Mn ratio for high-fluorine-content resins is usually 1, with 1.1 being more preferred. The upper limit of the above Mw / Mn ratio is usually 5, with 3 being preferred, 2 being more preferred, and 1.9 being even more preferred.

[0084] The content of the high-fluorine resin is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and particularly preferably 1.5 parts by mass or more, per 100 parts by mass of the base resin. Furthermore, it is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 8 parts by mass or less.

[0085] The radiation-sensitive resin composition may contain one or more high-fluorine-content resins.

[0086] (Method for synthesizing high-fluorine content resins) High-fluorine-content resins can be synthesized by the same method as the base resin synthesis method described above.

[0087] (Sulfonium salt compound (B0)) The sulfonium salt compound (B0) in this invention is a compound represented by the following formula (1). [ka] (In the formula, R 1 This is a monovalent hydrocarbon group having a cyclic structure, and the methylene group constituting the hydrocarbon group may be replaced by an ether bond. R f1 and R f2 Each of these is independently either a fluorine atom or a monovalent fluorinated hydrocarbon group. m1 is an integer from 1 to 4, and if m1 is from 2 to 4, multiple R f1 and R f2 They are either identical or different in part or in whole. R 2 and R 3 Each of these is independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group, or a monovalent fluorinated hydrocarbon group. m2 is an integer between 0 and 3, and if m2 is between 2 and 3, multiple R 2 and R 3 They are either identical or different in part or in whole. X is a linker containing a single bond or a divalent heteroatom. R 4 ~R 7 Each of these is independently a hydrogen atom, a hydroxyl group, a monovalent hydrocarbon group, or an ester group. n1 and n2 are each independent integers between 1 and 3, and multiple R 4 ~R 7 They are either identical or different in part or in whole. R 8 This includes monovalent linear hydrocarbon groups, monovalent alicyclic hydrocarbon groups, monovalent fluorinated hydrocarbon groups, halogen atoms, monovalent aromatic hydrocarbon groups, or -YR 8’ It is a monovalent group represented by (Y represents -O-, -CO-, -COO-, -OCO-, R 8’ (It is a monovalent hydrocarbon group with 1 to 20 carbon atoms.) l is an integer from 0 to 5, and if l is from 2 to 5, multiple R 8 (These are either identical or different in part or in whole.)

[0088] In the above equation (1), R 1 Examples of monovalent hydrocarbon groups having a cyclic structure represented by include substituted or unsubstituted monovalent alicyclic hydrocarbon groups having 3 to 40 carbon atoms or monovalent hydrocarbon groups having a cyclic structure having 3 to 40 carbon atoms, and the methylene groups constituting these hydrocarbon groups may be replaced by ether bonds.

[0089] The above R 1Examples of alicyclic hydrocarbon groups or hydrocarbon groups having a cyclic structure represented by include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, bornyl group, norbornyl group, adamantyl group, pinanyl group, thuyoyl group, caryl group, camphanyl group, cyclopropylmethyl group, cyclobutylmethyl group, cyclopentylmethyl group, cyclohexylmethyl group, bornylmethyl group, norbornylmethyl group, and adamantylmethyl group.

[0090] Also, the above R 1 Examples of substituents on the alicyclic hydrocarbon group represented by and the hydrocarbon group having the above cyclic structure include halogen atoms such as fluorine, chlorine, bromine, and iodine, hydroxyl groups, carboxyl groups, cyano groups, nitro groups, alkyl groups (when substituting a hydrogen atom of a cycloalkyl group or aromatic hydrocarbon group), aryl groups (when substituting a hydrogen atom of an alkyl group), alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, and acyloxy groups. Among these, fluorine, alkyl groups, and aryl groups are preferred.

[0091] Examples of alicyclic hydrocarbon groups or hydrocarbon groups having a cyclic structure substituted with such substituents include 4-fluorocyclohexyl group, 4-hydroxycyclohexyl group, 4-methoxycyclohexyl group, 4-methoxycarbonylcyclohexyl group, 3-hydroxy-1-adamantyl group, 3-methoxycarbonyl-1-adamantyl group, 3-hydroxycarbonyl-1-adamantyl group, and 3-hydroxymethyl-1-adamantanmethyl group.

[0092] In the above equation (1), R f1 and R f2 Examples of monovalent fluorinated hydrocarbon groups represented by include, independently, monovalent fluorinated hydrocarbon groups having 1 to 10 carbon atoms.

[0093] The above R f1 and R f2Examples of monovalent fluorinated hydrocarbon groups having 1 to 10 carbon atoms, as represented by this formula, include monovalent fluorinated linear hydrocarbon groups having 1 to 10 carbon atoms and monovalent fluorinated alicyclic hydrocarbon groups having 3 to 10 carbon atoms.

[0094] The above R f1 and R f2 Examples of monovalent fluorinated chain hydrocarbon groups having 1 to 10 carbon atoms, represented by , include Fluorinated alkyl groups such as trifluoromethyl group, 2,2,2-trifluoroethyl group, pentafluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoropropyl group, and heptafluoron-propyl group; Fluorinated alkenyl groups such as trifluoroethenyl groups and pentafluoropropenyl groups; Examples include fluorinated alkynyl groups such as fluoroethynyl groups and trifluoropropynyl groups.

[0095] The above R f1 and R f2 Examples of monovalent fluorinated alicyclic hydrocarbon groups having 3 to 10 carbon atoms, represented by the formula, include: Fluorinated cycloalkyl groups such as fluorocyclopentyl group, difluorocyclopentyl group, nonafluorocyclopentyl group, fluorocyclohexyl group, difluorocyclohexyl group, undecafluorocyclohexylmethyl group, fluoronorbornyl group, fluoroadamantyl group, fluorobornyl group, and fluoroisobornyl group; Examples include fluorinated cycloalkenyl groups such as fluorocyclopentenyl groups and nonafluorocyclohexenyl groups.

[0096] The above R f1 and R f2 The fluorinated hydrocarbon group represented by is preferably a monovalent fluorinated linear hydrocarbon group having 1 to 10 carbon atoms, more preferably a monovalent fluorinated alkyl group having 1 to 8 carbon atoms, even more preferably a perfluoroalkyl group having 1 to 6 carbon atoms, and particularly preferably a linear perfluoroalkyl group having 1 to 6 carbon atoms.

[0097] In formula (1) above, m1 is an integer from 1 to 4, and may also be from 2 to 3. When m1 is from 2 to 4, multiple R f1 and R f2 They are either identical or different in part or in whole.

[0098] In the above equation (1), R 2 and R 3 Each of these is independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group, or a monovalent fluorinated hydrocarbon group.

[0099] The above R 2 and R 3 The monovalent hydrocarbon groups represented by are, independently, R 1 A monovalent hydrocarbon group similar to that used in [the original text] can be used.

[0100] The above R 2 and R 3 The monovalent fluorinated hydrocarbon groups represented by are, independently, R f1 and R f2 A monovalent fluorinated hydrocarbon group similar to that used in [the original text] can be used.

[0101] In the above formula (1), m2 is an integer between 0 and 3, and may also be between 1 and 2. When m2 is between 2 and 3, multiple R 2 and R 3 They are either identical or different in part or in whole.

[0102] In formula (1) above, X is a linker containing a single bond or a divalent heteroatom.

[0103] Examples of the divalent heteroatoms in X above include oxygen atoms and sulfur atoms.

[0104] Examples of linkers containing the divalent heteroatom represented by X above include -O-, -(C=O)-, -(C=O)O-, -S-, -SO2-, and combinations thereof.

[0105] In the above equation (1), R 4 ~R 7 Each of these is independently a hydrogen atom, a hydroxyl group, a monovalent hydrocarbon group, or an ester group.

[0106] The above R 4 ~R 7 The monovalent hydrocarbon groups represented by are, independently, R 1 A monovalent hydrocarbon group similar to that used in [the original text] can be used.

[0107] The above R 4 ~R 7 Examples of ester groups represented by these symbols include, independently, a methoxycarbonyl group and an ethoxycarbonyl group.

[0108] In the above equation (1), n1 and n2 are each independent integers from 1 to 3, and may be 2. 4 ~R 7 They are either identical or different in part or in whole.

[0109] In the above equation (1), R 8 This includes monovalent linear hydrocarbon groups, monovalent alicyclic hydrocarbon groups, monovalent fluorinated hydrocarbon groups, halogen atoms, monovalent aromatic hydrocarbon groups, or -YR 8’ It is a monovalent group represented by (Y represents -O-, -CO-, -COO-, -OCO-, R 8’ (It is a monovalent hydrocarbon group with 1 to 20 carbon atoms.)

[0110] The above R 8 Examples of monovalent chain hydrocarbon groups represented by these symbols include, independently, a methyl group and an ethyl group.

[0111] The above R 8 Examples of monovalent alicyclic hydrocarbon groups represented by these symbols include, independently, cyclopentyl groups and cyclohexyl groups.

[0112] The above R 8The monovalent fluorinated hydrocarbon groups represented by are, independently, R f1 and R f2 A monovalent fluorinated hydrocarbon group similar to that used in [the original text] can be used.

[0113] The above R 8 Examples of halogen atoms represented by this formula include chlorine, fluorine, bromine, and iodine atoms.

[0114] The above R 8 Examples of monovalent aromatic hydrocarbon groups represented by this formula include monovalent aromatic hydrocarbon groups having 6 to 12 carbon atoms.

[0115] The above R 8 Examples of monovalent aromatic hydrocarbon groups having 6 to 12 carbon atoms, represented by the formula, include, independently, aryl groups such as phenyl, tolyl, xyl, naphthyl, and anthryl groups, and aralkyl groups such as benzyl, phenethyl, and naphthylmethyl groups.

[0116] The above R 8 Examples of alkylsilyl groups represented by include trimethylsilyl group, triethylsilyl group, t-butyldimethylsilyl group, diethylisopropylsilyl group, triisopropylsilyl group, dimethylhexylsilyl group, t-butyldiphenylsilyl group, dimethylphenylsilyl group, triphenylsilyl group, and tris(trimethylsilyl)silyl group.

[0117] The above R 8 -YR in 8’ Examples of groups represented by this symbol include groups formed by bonding a hydrocarbon group having 1 to 20 carbon atoms via a bonding group selected from -O-, -CO-, -COO-, and -OCO-.

[0118] The above R 8’ Examples of hydrocarbon groups having 1 to 20 carbon atoms, represented by this formula, include methyl groups and ethyl groups.

[0119] In formula (1) above, l is an integer from 0 to 5, and may also be from 1 to 4. When l is from 2 to 5, multiple R 8 They are either identical or different in part or in whole.

[0120] In the above equation (1), R 8 At least one of the S in the formula is + It is preferable that it be located in the para position relative to the bonding position.

[0121] The above compound (1) is not limited to the following compounds, but examples include the following compounds. [ka] TIFF2026067953000014.tif147170TIFF2026067953000015.tif195170TIFF2026067953000016.tif84169

[0122] Furthermore, in the present invention, the total content of the sulfonium salt compound (B0) in the resin composition is preferably 0.5 to 30 parts by mass, can be 1 to 25 parts by mass, or 1.5 to 20 parts by mass per 100 parts by mass of the resin (A). In addition, the sulfonium salt compound (B0) may be used alone or in combination of two or more types.

[0123] (Solvent (D)) 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 resin, the radiation-sensitive acid generator, and optionally the acid diffusion control agent, etc.

[0124] Examples of solvents include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] Examples of amide solvents include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; Examples of chain-like amide solvents include N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0129] 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, dipropylene glycol monomethyl ether acetate, and propylene glycol acetate monomethyl ether; 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.

[0130] 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.

[0131] Among these, ester solvents and ketone solvents are preferred, polyhydric alcohol partial ether acetate solvents, cyclic ketone solvents, and lactone solvents are more preferred, and propylene glycol monomethyl ether acetate, cyclohexanone, and γ-butyrolactone are even more preferred. The above radiation-sensitive resin composition may contain one or more solvents.

[0132] (Other optional components) The radiation-sensitive resin composition may contain other optional components in addition to the components mentioned above. Examples of these other optional components include acid diffusion regulators, 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.

[0133] (Acid diffusion control agent) The radiation-sensitive resin composition may optionally contain an 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 unexposed areas. Furthermore, it improves the storage stability of the resulting radiation-sensitive resin composition. In addition, it further improves the resolution of the resist pattern and suppresses changes in the line width of the resist pattern due to variations in the holding time from exposure to development, resulting in a radiation-sensitive resin composition with excellent process stability.

[0134] Examples of acid diffusion control agents include compounds represented by the following formula (7) (hereinafter also referred to as "nitrogen-containing compounds (I)"), compounds having two nitrogen atoms in the same molecule (hereinafter also referred to as "nitrogen-containing compounds (II)"), compounds having three nitrogen atoms (hereinafter also referred to as "nitrogen-containing compounds (III)"), amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, and the like.

[0135] [ka]

[0136] In equation (7) above, R 22 , R 23 and R 24 Each of these is independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.

[0137] Examples of nitrogen-containing compounds (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; and aromatic amines such as aniline.

[0138] Examples of nitrogen-containing compounds (II) include ethylenediamine and N,N,N',N'-tetramethylethylenediamine.

[0139] Examples of nitrogen-containing compounds (III) include polyamine compounds such as polyethyleneimine and polyallylamine; and polymers such as dimethylaminoethylacrylamide.

[0140] Examples of amide group-containing compounds include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, pyrrolidone, and N-methylpyrrolidone.

[0141] Examples of urea compounds include urea, methyl urea, 1,1-dimethyl urea, 1,3-dimethyl urea, 1,1,3,3-tetramethyl urea, 1,3-diphenyl urea, and tributylthiourea.

[0142] Examples of nitrogen-containing heterocyclic compounds include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N-(undecylcarbonyloxyethyl)morpholine; and pyrazines and pyrazoles.

[0143] In addition, as the nitrogen-containing organic compound, a compound having an acid-dissociable group can also be used. Examples of such nitrogen-containing organic compounds having an acid-dissociable group include N-t-butoxycarbonylpiperidine, N-t-butoxycarbonylimidazole, N-t-butoxycarbonylbenzimidazole, N-t-butoxycarbonyl-2-phenylbenzimidazole, N-(t-butoxycarbonyl)di-n-octylamine, N-(t-butoxycarbonyl)diethanolamine, N-(t-butoxycarbonyl)dicyclohexylamine, N-(t-butoxycarbonyl)diphenylamine, N-t-butoxycarbonyl-4-hydroxypiperidine, N-t-amyloxycarbonyl-4-hydroxypiperidine, and the like.

[0144] In addition, as the acid diffusion controller, a photo-dissociable base that generates a weak acid upon exposure can also be preferably used. Examples of the photo-dissociable base include compounds containing a radiation-sensitive onium cation that decomposes upon exposure and an anion of a weak acid. In the exposed area, the photo-dissociable base generates a weak acid from the proton generated by the decomposition of the radiation-sensitive onium cation and the anion of the weak acid, so that the acid diffusion control property deteriorates.

[0145] Examples of the photo-dissociable base include sulfonium salt compounds represented by the following formula (8-1), iodonium salt compounds represented by the following formula (8-2), and the like.

[0146] [Chemical formula]

[0147] In the above formula (8-1) and formula (8-2), J + is a sulfonium cation, and U + is an iodonium cation. The sulfonium cation or iodonium cation is preferably represented by the following formulas (X-1) to (X-6). E- and Q- are each independently OH-, R α -COO - 、R α -SO3- This is an anion represented by R. α R is an alkyl group, an aryl group, or an aralkyl group. α The hydrogen atoms of the aromatic ring of the aryl or aralkyl group represented by may be substituted with a hydroxyl group, a fluorine-substituted or unsubstituted C1-C12 alkyl group, or a C1-C12 alkoxy group.

[0148] [ka]

[0149] In the above equation (X-1), R a1 , R a2 and R a3 Each of these independently comprises a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyloxy group having 1 to 12 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxyl group, a halogen atom, and -OSO2-R. P , -SO2-R Q Alternatively, -SR T This represents a ring structure formed by combining two or more of these groups. This ring structure may contain heteroatoms such as O or S between the carbon-carbon bonds that form the skeleton. P , R Q and R T Each of these is independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2, and k3 are each independently integers from 0 to 5. a1 ~R a3 R P , R Q and R T If each of them is multiple, then multiple R a1 ~R a3 R P , R Q and R TThese may be the same or different.

[0150] In the above equation (X-2), R b1 This is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxyl group. k n is either 0 or 1. k When is 0, k4 is an integer from 0 to 4, and n k When is 1, k4 is an integer from 0 to 7. b1 If there are multiple, then multiple R b1 They may be the same or different, and there may be multiple R b1 R may represent a ring structure formed by combining with other elements. b2 This is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. C k5 is a single bond or a divalent linking group. k5 is an integer from 0 to 4. b2 If there are multiple, then multiple R b2 They may be the same or different, and there may be multiple R b2 may represent a ring structure formed by combining with each other. q is an integer between 0 and 3. In the formula, S + The ring structure containing may include heteroatoms such as O and S between the carbon-carbon bonds that form the skeleton.

[0151] In the above equation (X-3), R c1 , R c2 and R c3 Each of these is independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms.

[0152] In the above equation (X-4), R g1 This is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxyl group.k2 n is either 0 or 1. k2 When k10 is 0, k10 is an integer from 0 to 4, and n k2 When k10 is 1, k10 is an integer from 0 to 7. g1 If there are multiple, then multiple R g1 They may be the same or different, and there may be multiple R g1 R may represent a ring structure formed by combining with other elements. g2 is and R g3 Each of these independently represents a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyloxy group having 1 to 12 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group, hydroxyl group, halogen atom having 6 to 12 carbon atoms, or a ring structure formed by combining these groups. k11 and k12 are each independently integers from 0 to 4. R g2 is and R g3 If each of them is multiple, then multiple R g2 is and R g3 These may be the same or different.

[0153] In the above equation (X-5), R d1 and R d2 Each of these independently represents a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or alkoxycarbonyl group, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a halogen atom, a halogenated alkyl group having 1 to 4 carbon atoms, a nitro group, or a ring structure formed by two or more of these groups being combined. k6 and k7 are each independently integers from 0 to 5. d1 and R d2 If each of them is multiple, then multiple R d1 and R d2 These may be the same or different.

[0154] In the above equation (X-6), R e1 and R e2k8 and k9 are each independently a halogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms.

[0155] Examples of substituents that may substitute for the hydrogen atoms of each of the above groups include halogen atoms such as fluorine, chlorine, bromine, and iodine, hydroxyl groups, carboxyl groups, cyano groups, nitro groups, alkyl groups (when substituting hydrogen atoms of cycloalkyl groups or aromatic hydrocarbon groups), aryl groups (when substituting hydrogen atoms of alkyl groups), alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, and acyloxy groups. Among these, hydroxyl groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, and acyloxy groups are preferred, and alkoxy groups or alkoxycarbonyl groups are more preferred.

[0156] Examples of the above-mentioned photodecayable bases include compounds represented by the following formula.

[0157] [ka]

[0158] Among the above photodecayable bases, sulfonium salts are preferred, triarylsulfonium salts are more preferred, and triphenylsulfonium salicylate and triphenylsulfonium 10-camphorsulfonate are even more preferred.

[0159] The lower limit of the acid diffusion control agent content is preferably 2 parts by mass, more preferably 3 parts by mass, and even more preferably 4 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 150 parts by mass, more preferably 120 parts by mass, and even more preferably 110 parts by mass.

[0160] By setting the content of the acid diffusion control agent within the above range, the lithography performance of the above radiation-sensitive resin composition can be further improved. The above radiation-sensitive resin composition may contain one or more acid diffusion control agents.

[0161] (Crosslinking agent) The crosslinking agent is a compound having two or more functional groups. In the baking step after the batch exposure step, it causes a crosslinking reaction in the polymer component by an acid-catalyzed reaction, increases the molecular weight of the polymer component, and thereby reduces the solubility of the pattern-exposed portion in the developer. Examples of the above functional groups include (meth)acryloyl group, hydroxymethyl group, alkoxymethyl group, epoxy group, vinyl ether group, etc.

[0162] (Phase separation promoter) The phase separation promoter has the effect of more efficiently causing the high-fluorine content resin to be unevenly distributed on the resist film surface. By including this phase separation promoter in the above radiation-sensitive resin composition, the addition amount of the above high-fluorine content resin can be made less than before. Therefore, while maintaining the lithography performance of the above radiation-sensitive resin composition, elution of components from the resist film into the immersion medium can be further suppressed, or immersion exposure can be performed at a higher speed by high-speed scanning, and as a result, the hydrophobicity of the resist film surface that suppresses immersion-derived defects such as watermark defects can be improved. Examples of those that can be used as such a phase separation promoter include, for example, low molecular weight compounds having a relative dielectric constant of 30 or more and 200 or less and a boiling point of 100°C or more at 1 atm. Specific examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, polyhydric alcohols, etc.

[0163] Examples of the above lactone compounds include γ-butyrolactone, valerolactone, mevalonic lactone, norbornane lactone, etc.

[0164] Examples of the carbonate compounds mentioned above include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, and the like.

[0165] Examples of the nitrile compounds mentioned above include succinonitrile.

[0166] Examples of the polyhydric alcohols mentioned above include glycerin.

[0167] The lower limit of the content of the segregation accelerator is preferably 10 parts by mass, more preferably 15 parts by mass, even more preferably 20 parts by mass, and even more preferably 25 parts by mass, per 100 parts by mass of the total amount of resin in the above radiation-sensitive resin composition. The upper limit of the above content is preferably 300 parts by mass, more preferably 200 parts by mass, even more preferably 100 parts by mass, and particularly preferably 80 parts by mass. The above radiation-sensitive resin composition may contain one or more types of segregation accelerators.

[0168] (Surfactants) Surfactants improve the properties of coating, striation, and development. Examples of surfactants include nonionic surfactants such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, and polyethylene glycol distearate; commercially available examples include KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, and No. 75. Examples include 95 (manufactured by Kyoeisha Chemical), F-Top EF301, EF303, EF352 (manufactured by Tochem Products), Megafac F171, F173 (manufactured by DIC), Florard FC430, FC431 (manufactured by Sumitomo 3M), Asahiguard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (manufactured by Asahi Glass Industries), etc. The surfactant content in the above radiation-sensitive resin composition is usually 2 parts by mass or less per 100 parts by mass of resin.

[0169] (Alicyclic skeleton-containing compounds) Compounds containing alicyclic skeletons have the effect of improving dry etching resistance, pattern shape, and adhesion to the substrate.

[0170] Examples of alicyclic skeleton-containing compounds include, Adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and t-butyl 1-adamantanecarboxylic acid; Deoxycholic acid esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholate, and 2-ethoxyethyl deoxycholate; Lithocholic acid esters such as t-butyl lithocholate, t-butoxycarbonylmethyl lithocholate, and 2-ethoxyethyl lithocholate; Examples include 3-[2-hydroxy-2,2-bis(trifluoromethyl)ethyl]tetracyclo[4.4.0.1(2,5).1(7,10)]dodecane and 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo[4.2.1.0(3,7)]nonane. The content of the alicyclic skeleton-containing compound in the above radiation-sensitive resin composition is usually 5 parts by mass or less per 100 parts by mass of resin.

[0171] (Sensitizer) The sensitizer increases the amount of acid produced from the radiation-sensitive acid generator, etc., and thus improves the "apparent sensitivity" of the above-mentioned radiation-sensitive resin composition.

[0172] Examples of sensitizers include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, and phenothiazines. These sensitizers may be used alone or in combination of two or more. The content of the sensitizer in the above-mentioned radiation-sensitive resin composition is usually 2 parts by mass or less per 100 parts by mass of resin.

[0173] (composition) The radiation-sensitive resin composition is particularly suitable for use in organic solvent development, that is, in the development process described above, when developing with an organic solvent to form a negative pattern.

[0174] <Method for preparing a radiation-sensitive resin composition> The radiation-sensitive resin composition can be prepared, for example, by mixing a resin, the above-mentioned sulfonium salt compound (or radiation-sensitive acid generator), an acid diffusion control agent, a high-fluorine content resin, and a solvent in predetermined proportions. After mixing, the radiation-sensitive resin composition is preferably filtered using, for example, a filter with a pore size of about 0.05 μm. The solid content concentration of the radiation-sensitive resin composition is usually 0.1% to 50% by mass, preferably 0.5% to 30% by mass, and more preferably 1% to 20% by mass.

[0175] <Method for forming a resist pattern> The method for forming a resist pattern in the present invention is: The above radiation-sensitive resin composition is applied directly or indirectly to a substrate to form a resist film (hereinafter also referred to as the "resist film formation step"), The process of exposing the resist film (hereinafter also referred to as the "exposure process"), and The process includes developing the exposed resist film.

[0176] According to the above method for forming a resist pattern, since the above radiation-sensitive resin composition is used, it is possible to form a resist pattern that exhibits excellent levels of sensitivity, LWR performance, and CDU performance in the exposure process. The following describes each step.

[0177] [Resist film formation process] In this process, a resist film is formed using the above-mentioned radiation-sensitive resin composition. More specifically, this process involves directly or indirectly coating a substrate with the above-mentioned radiation-sensitive resin composition to form a resist film. Examples of substrates on which this resist film is formed 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 resist film formed is preferably 10 nm to 1,000 nm, and more preferably 10 nm to 500 nm.

[0178] When performing immersion exposure, regardless of the presence or absence of water-repellent polymer additives such as the high-fluorine-content resin in the above-mentioned radiation-sensitive resin composition, a protective immersion film insoluble in the immersion liquid may be provided on the formed resist film to avoid direct contact between the immersion liquid and the resist film. As the protective immersion film, 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) may be used. However, from the viewpoint of throughput, it is preferable to use a developer-peelable protective immersion film.

[0179] 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 the above structural units (I) and (IV) as the base resin in the above composition.

[0180] [Synthesis process] In this process, the resist film formed in the resist film formation process described 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, with ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV being more preferred, and electron beams and EUV with wavelengths of 50 nm or less, which are positioned as next-generation exposure technologies, being even more preferred.

[0181] 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.

[0182] 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.

[0183] Furthermore, the exposure step may include a step of developing the exposed resist film (hereinafter also referred to as the "development step").

[0184] [Development process] In this step, the resist film exposed in the exposure step described above is developed. This allows for the formation of a predetermined resist pattern. After development, it is common to wash the film with a rinsing solution such as water or alcohol and then dry it.

[0185] 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.

[0186] 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, ester solvents and ketone solvents are preferred. As for ester solvents, acetic acid 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 solvent in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. Examples of components other than organic solvents in the developer include water and silicone oil.

[0187] The method for forming the resist pattern described above is particularly suitable for use when developing with an organic solvent to form a negative-type pattern in the development step described above.

[0188] 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 the developer solution onto 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 onto a substrate rotating at a constant speed while scanning the developer solution dispensing nozzle at a constant speed (dynamic dispensing method).

[0189] <Methods for processing substrates and manufacturing metal film patterns> The substrate processing method in the present invention is: Furthermore, the method includes a step of forming a pattern on a substrate using the resist pattern formed by the above method as a mask.

[0190] Because the above-described substrate processing method uses the above-described radiation-sensitive resin composition, it is possible to form a high-quality substrate pattern.

[0191] The above process involves forming a pattern on a substrate using a resist pattern formed by any of the methods described above as a mask. Examples of methods for forming a pattern on a substrate using a resist pattern as a mask include forming a resist pattern on the substrate and then forming a pattern on the substrate in areas without resist by methods such as dry etching, or forming a resist pattern and then depositing substrate components into areas without resist by methods such as CVD or electroless plating to form part or all of the substrate.

[0192] Furthermore, the method for manufacturing a metal film pattern in the present invention is Furthermore, the method includes a step of forming a metal film using the resist pattern formed by the above method as a mask.

[0193] Since the above-described method for manufacturing the metal film pattern uses the above-described radiation-sensitive resin composition, it is possible to process the metal film pattern.

[0194] The above process involves forming a metal film using a resist pattern formed by any of the methods described above as a mask. Examples of methods for forming a metal film using a resist pattern as a mask include forming a resist pattern and then depositing metal onto areas without resist using methods such as electroless plating to form a metal film, or forming a resist pattern on a metal film and then removing the metal film in areas without resist using methods such as dry etching to form a metal film.

[0195] (Radiation-sensitive acid generator (B)) The radiation-sensitive acid generator (B) in the present invention is a radiation-sensitive acid generator that contains a sulfonium salt compound represented by the above formula (1).

[0196] The above-mentioned radiation-sensitive acid generator (B) is a radiation-sensitive acid generator that generates acid upon irradiation with radiation.

[0197] Each component in formula (1) above is the same as that described in the section on (sulfonium salt compound (B0)) above.

[0198] Furthermore, in the present invention, the total content of the radiation-sensitive acid generator (B) in the resin composition is preferably 0.5 to 30 parts by mass, can be 1 to 25 parts by mass, and can be 1.5 to 20 parts by mass per 100 parts by mass of the resin (A). If the above blending amount or content ratio is less than the above lower limit, the sensitivity may decrease. Conversely, if the above blending amount or content ratio exceeds the above upper limit, it may become difficult to form a resist film, or the rectangularity of the cross-sectional shape of the resist pattern may decrease. Furthermore, the radiation-sensitive acid generator (B) may be used alone, or two or more may be used in combination. Furthermore, known radiation-sensitive acid generators may be used in combination as long as they do not impair the effects of the present invention.

[0199] The radiation-sensitive acid generator (B) can be used particularly suitably for organic solvent development, that is, in the development process described above, when developing with an organic solvent to form a negative-type pattern. [Examples]

[0200] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples. The methods for measuring various physical properties are shown below.

[0201] [Measurement of weight-average molecular weight (Mw), number-average molecular weight (Mn), and degree of dispersion (Mw / Mn)] The Mw and Mn of the polymer were measured under the conditions described above. The degree of dispersion (Mw / Mn) was calculated from the measured Mw and Mn values.

[0202] [ 13 C-NMR analysis] polymer 13 ¹

[0203] <[A]Synthesis of resin and [E] high-fluorine content resin> The monomers used in the synthesis of each resin and high-fluorine-content resin in each example and comparative example 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%.

[0204] [ka]

[0205] [Synthesis Example 1] (Synthesis of resin (A-1)) Monomers (M-1), (M-2), and (M-13) were dissolved in 200 parts by mass of 2-butanone in a molar ratio of 40 / 15 / 45 (mol%), and AIBN (azobisisobutyronitrile) (3 mol% of the total monomers used, 100 mol%) was added as an initiator to prepare a monomer solution. 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 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 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 powdered resin (A-1) (yield: 83%). The Mw of resin (A-1) was 8,800, and the Mw / Mn ratio was 1.50. 13 13C-NMR analysis revealed that the content of each structural unit derived from (M-1), (M-2), and (M-13) was 41.3 mol%, 13.8 mol%, and 44.9 mol%, respectively.

[0206] [Synthesis Examples 1-11] (Synthesis of resins (A-2) to (A-11)) Resins (A-2) to (A-11) were synthesized in the same manner as in Synthesis Example 1, except that the monomers used were of the types and proportions shown in Table 1 below. The content (mol%), yield (%), and physical properties (Mw and Mw / Mn) of each structural unit of the obtained 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).

[0207] [Table 1]

[0208] [Synthesis Example 12] (Synthesis of 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 powdered resin (A-12) (yield: 79%). The Mw of resin (A-12) was 5,200, and the Mw / Mn ratio was 1.60. 13 1C-NMR analysis revealed that the content of each structural unit derived from (M-1) and (M-18) was 51.3 mol% and 48.7 mol%, respectively.

[0209] [Synthesis Examples 13-15] (Synthesis of resin (A-13) to resin (A-15)) Resins (A-13) to (A-15) were synthesized in the same manner as in Synthesis Example 12, except that the monomers used were of the types and proportions shown in Table 2 below. The content (mol%), yield (%), and physical properties (Mw and Mw / Mn) of each structural unit of the obtained resins are also shown in Table 2 below.

[0210] [Table 2]

[0211] [Synthesis Example 16] (Synthesis of high-fluorine content resin (E-1)) Monomer (M-1) and monomer (M-20) were dissolved in 200 parts by mass of 2-butanone to a molar ratio of 20 / 80 (mol%), and AIBN (4 mol%) was added as an initiator to prepare a monomer solution. 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 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 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 high-fluorine content resin (E-1) was obtained (yield: 69%). The Mw of the high-fluorine-content resin (E-1) was 6,000, and the Mw / Mn ratio was 1.62. Furthermore, 13 13C-NMR analysis revealed that the content of each structural unit derived from (M-1) and (M-20) was 19.9 mol% and 80.1 mol%, respectively.

[0212] [Synthesis Examples 17-20] (Synthesis of high-fluorine content resins (E-2) to high-fluorine content resins (E-5)) High-fluorine-content resins (E-2) to (E-5) were synthesized in the same manner as in Synthesis Example 16, except that monomers of the types and proportions shown in Table 3 below were used. The content (mol%), yield (%), and physical properties (Mw and Mw / Mn) of each structural unit of the obtained high-fluorine-content resins are shown in accordance with Table 3 below.

[0213] [Table 3]

[0214] [B] Synthesis of radiation-sensitive acid generators [Synthesis Example 21] (Synthesis of compound (B-1)) Compound (B-1) was synthesized according to the following synthesis scheme.

[0215] [ka]

[0216] 20.0 mmol of iodine, 40.0 mmol of tert-amylbenzene, 40.0 mmol of metachloroperbenzoic acid, 40.0 mmol of tosylic acid monohydrate, and 100 g of chloroform were added to a reaction vessel and stirred at room temperature for 24 hours. After dilution with water, methylene chloride was added for extraction, and the organic layer was separated. The obtained organic layer was washed with saturated sodium chloride aqueous solution. After drying over sodium sulfate, the solvent was removed by distillation, and the salt represented by formula (B-1-a) was obtained in good yield by recrystallization with diethyl ether.

[0217] 20.0 mmol of a sodium sulfonate salt compound was added to the salt represented by formula (B-1-a) above, and a 0.5 M solution was prepared by adding a mixture of water and dichloromethane (1:1 by mass ratio). After vigorously stirring at room temperature for 3 hours, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was dried over sodium sulfate, the solvent was removed by distillation, and the salt represented by formula (B-1-b) above was obtained in good yield.

[0218] To the salt represented by the above formula (B-1-a), 20.0 mmol of 1,4-thioxane, 2.00 mmol of copper(II) acetate, and 50 g of chloroform were added and the mixture was stirred at room temperature for 24 hours. After removing impurities by Celite filtration, the solvent was removed by distillation, and the compound (B-1) represented by the above formula (B-1) was obtained in good yield by column chromatography.

[0219] [Synthesis Examples 22-41] (Synthesis of compounds (B-2) to (B-21)) A radiation-sensitive acid generator represented by the following formulas (B-2) to (B-21) was synthesized in the same manner as in Synthesis Example 21, except that the raw materials and precursors were changed as appropriate.

[0220] [ka]

[0221] [Radiation-sensitive acid generators other than compounds (B-1) to (B-16)] b-1 to b-19: Compounds represented by the following formulas (b-1) to (b-19) (Hereafter, compounds represented by formulas (b-1) to (b-19) may be referred to as "compound (b-1)" to "compound (b-19)," respectively.)

[0222] [ka]

[0223] [[C] Acid diffusion control agent] C-1 to C-5: Compounds represented by the following formulas (C-1) to (C-5).

[0224] [ka]

[0225] [[D] Solvent] D-1: Propylene glycol monomethyl ether acetate D-2: Propylene glycol monomethyl ether D-3: γ-Butyrolactone D-4: Ethyl lactate

[0226] [Preparation of negative-type radiation-sensitive resin composition for ArF exposure] [Example 1] 100 parts by mass of (A-1) as a resin, 12.0 parts by mass of (B-1) as a radiation-sensitive acid generator, 6.0 parts by mass of (C-1) as an acid diffusion controller, 3.0 parts by mass (solid content) of (E-1) as a high fluorine content resin, and 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) as a solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-1).

[0227] [Examples 2 to 46 and Comparative Examples 1 to 19] Except for using each component of the types and contents shown in Table 4 below, radiation-sensitive resin compositions (J-2) to (J-46) and (CJ-1) to (CJ-19) were prepared in the same manner as in Example 1.

[0228]

Table 4

[0229] <Formation of a resist pattern using a negative-type ArF exposure radiation-sensitive resin composition> On a 12-inch silicon wafer, a composition for forming an anti-reflection film for the lower layer ("ARC66" from Brewer Science) was applied using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Limited), and then heated at 205 °C for 60 seconds to form an anti-reflection film for the lower layer with an average thickness of 100 nm. The negative-type ArF exposure radiation-sensitive resin composition (J-63) prepared above was applied on this anti-reflection film for the lower layer using the spin coater, and PB (pre-bake) was performed at 100 °C for 60 seconds. Then, by cooling at 23 °C for 30 seconds, a resist film with an average thickness of 90 nm was formed.

[0230] 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).

[0231] <Rating> The sensitivity, CDU performance, pattern rectangularity, and etching resistance of resist patterns formed using the above-mentioned ArF exposure negative-type radiation-sensitive resin composition were evaluated according to the following method. The results are shown in Table 5 below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns.

[0232] [sensitivity] In forming a resist pattern using the above-described negative-type radiation-sensitive resin composition for ArF exposure, the exposure amount used to form a 40 nm hole pattern was defined as the optimal exposure amount, and this optimal exposure amount was defined as the sensitivity (mJ / cm2). Sensitivity was evaluated as "good" if it was 30 mJ / cm2 or less, and as "poor" if it exceeded 30 mJ / cm2.

[0233] [CDU performance] A resist pattern with 40 nm holes and a 105 nm pitch was measured at 1,800 arbitrary points from the top of the pattern using the scanning electron microscope described above. The dimensional variation (3σ) was determined and defined as the CDU performance (nm). A smaller CDU value indicates less variation in hole diameter over long periods, resulting in better performance. CDU performance was evaluated as "good" if it was 2.5 nm or less, and "poor" if it exceeded 2.5 nm.

[0234] [depth of focus] In the resist pattern resolved at the optimal exposure level determined by the sensitivity evaluation above, the dimensions were observed when the focus was changed in the depth direction. The margin in the depth direction where the pattern dimensions fall within 90% to 110% of the standard without bridging or residue was measured, and this measured value was defined as the depth of focus (nm). A larger depth of focus indicates a better result. A depth of focus of 50 nm or more is evaluated as "good," and a depth of focus of less than 50 nm is evaluated as "poor."

[0235] [Pattern Rectangle] The resist patterns with 40 nm hole spaces, formed by irradiating with the optimal exposure dose determined in the sensitivity evaluation above, were observed using the scanning electron microscope described above, and the cross-sectional shape of the hole patterns was evaluated. The rectangularity of the resist patterns was evaluated as follows: if the ratio of the length of the lower side to the length of the upper side in the cross-sectional shape was 1 or more and 1.05 or less, it was "A" (excellent); if it was greater than 1.05 and 1.10 or less, it was "B" (good); and if it was greater than 1.10, it was "C" (poor).

[0236] [Etching resistance] The resist composition prepared above was coated onto a silicon wafer substrate by spin coating. Next, it was heated at 100°C for 60 seconds in an air atmosphere to form a resist film with an average thickness of 100 nm, thereby obtaining a resist-coated substrate. The resist film on the obtained resist-coated substrate was processed using an etching apparatus (Tokyo Electron's "TACTRAS") under the conditions O2=100 sccm, PRESS.=100 mT, HF RF=200 W, LF RF=0 W, and DCS=0 V. The etching rate (nm / min) was calculated from the time required for the disappearance of the resist film, and the ratio to the etching rate in Comparative Example 1 was determined and used as a measure of etching resistance. Etching resistance was evaluated as follows: if the above ratio was 0.90 or more and 0.95 or less, it was "A" (very good); if it was greater than 0.95 and 1.00 or less, it was "B" (good); and if it was greater than 1.00, it was "C" (poor). In Table 5, the "-" indicates that Comparative Example 1 is the standard for evaluating etching resistance.

[0237] [Number of development defects] A resist film was exposed at the optimal exposure level to form a 40nm hole pattern, and this was used as a wafer for defect inspection. The number of defects on this wafer was measured using a defect inspection device (KLA-Tencor's "KLA2810"). The measured defects were then classified into those determined to be from the resist film and those determined to be from external foreign matter, and the number of defects determined to be from the resist film was calculated. After development, the number of defects determined to be from the resist film was evaluated as "good" if it was 50 or less, and as "bad" if it was more than 50.

[0238] [Table 5]

[0239] As is clear from the results in Table 5, the radiation-sensitive resin composition of the example exhibited good sensitivity, CDU performance, depth of field, pattern rectangularity, etching resistance, and development defect performance when used in ArF exposure, whereas the comparative example exhibited inferior characteristics compared to the example. Therefore, when the radiation-sensitive resin composition of the example is used in ArF exposure, it is possible to form a resist pattern with high sensitivity, good CDU performance, and good cross-sectional shape.

[0240] [Preparation of radiation-sensitive resin compositions for extreme ultraviolet (EUV) exposure] [Example 47] A radiation-sensitive resin composition (J-47) was prepared by mixing [A] 100 parts by mass of (A-12) as a resin, [B] 17.0 parts by mass of (B-1) as a radiation-sensitive acid generator, [C] 10.0 parts by mass of (C-2) as an acid diffusion control agent, [E] 3.0 parts by mass (solids) of (E-5) as a high-fluorine-content resin, and [D] 6,110 parts by mass 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.

[0241] [Examples 48-59 and Comparative Examples 20-27] Except for using the components of the types and contents shown in Table 6 below, radiation-sensitive resin compositions (J-48) to (J-59) and (CJ-20) to (CJ-27) were prepared in the same manner as in Example 42.

[0242]

Table 6

[0243] <Formation of Resist Pattern Using Radiation-Sensitive Resin Composition for EUV Exposure> On a 12-inch silicon wafer, using a spin coater ("CLEAN TRACK ACT12" of Tokyo Electron Limited), a composition for forming an underlying antireflection film ("ARC66" of Brewer Science, Inc.) was applied, and then heated at 205°C for 60 seconds to form an underlying antireflection film with an average thickness of 105 nm. On this underlying antireflection film, the prepared radiation-sensitive resin composition for EUV exposure was applied using the above spin coater, and PB was performed at 130°C for 60 seconds. Then, by cooling at 23°C for 30 seconds, a resist film with an average thickness of 55 nm was formed.

[0244] Next, this resist film was exposed using an EUV exposure apparatus ("NXE3300" of ASML) with NA = 0.33, illumination condition: Conventional s = 0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120°C for 60 seconds. Then, the resist film was alkali-developed using a 2.38 mass% aqueous TMAH solution as an alkali developer, washed with water after development, and further dried to form a positive resist pattern (32 nm line and space pattern).

[0245] <Evaluation> Regarding the resist patterns formed using the above radiation-sensitive resin composition for EUV exposure, sensitivity, LWR performance, pattern rectangularity, and etching resistance were evaluated according to the following methods. The results are shown in Table 7 below. For the length measurement of the resist pattern, a scanning electron microscope ("CG-5000" of Hitachi High-Technologies Corporation) was used.

[0246] [sensitivity] In forming a resist pattern using the above-described radiation-sensitive resin composition for EUV lithography, the exposure amount used to form a 32 nm line-and-space pattern was defined as the optimal exposure amount, and this optimal exposure amount was defined as the sensitivity (mJ / cm2). Sensitivity was evaluated as "good" if it was 30 mJ / cm2 or less, and as "poor" if it exceeded 30 mJ / cm2.

[0247] [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 jaggedness 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.

[0248] [Pattern Rectangle] The 32nm line-and-space resist patterns formed by irradiating with the optimal exposure dose determined in the sensitivity evaluation above were observed using the scanning electron microscope described above, and the cross-sectional shape of the line-and-space patterns was evaluated. The rectangularity of the resist pattern was evaluated as follows: if the ratio of the length of the lower side to the length of the upper side in the cross-sectional shape was 1 or more and 1.05 or less, it was "A" (excellent); if it was greater than 1.05 and 1.10 or less, it was "B" (good); and if it was greater than 1.10, it was "C" (poor).

[0249] [Etching resistance] The resist composition prepared above was coated onto a silicon wafer substrate by spin coating. Next, it was heated at 100°C for 60 seconds in an air atmosphere to form a resist film with an average thickness of 100 nm, thereby obtaining a resist-coated substrate. The resist film on the obtained resist-coated substrate was processed using an etching apparatus (Tokyo Electron's "TACTRAS") under the conditions O2=100 sccm, PRESS.=100 mT, HF RF=200 W, LF RF=0 W, and DCS=0 V. The etching rate (nm / min) was calculated from the time required for the disappearance of the resist film, and the ratio to the etching rate in Comparative Example 20 was determined and used as a measure of etching resistance. Etching resistance was evaluated as follows: if the above ratio was 0.90 or more and 0.95 or less, it was "A" (very good); if it was greater than 0.95 and 1.00 or less, it was "B" (good); and if it was greater than 1.00, it was "C" (poor). In Table 7, the "-" indicates that Comparative Example 20 is the standard for evaluating etching resistance.

[0250] [Table 7]

[0251] As is clear from the results in Table 7, the radiation-sensitive resin composition of the example showed good sensitivity, LWR performance, pattern rectangularity, and etching resistance when used in EUV exposure, whereas the comparative example exhibited inferior characteristics compared to the example.

[0252] [Preparation of positive-type radiation-sensitive resin composition for ArF exposure, formation and evaluation of resist patterns using this composition] [Example 60] A radiation-sensitive resin composition (J-60) was prepared by mixing [A] 100 parts by mass of (A-5) as a resin, [B] 11.0 parts by mass of (B-2) as a radiation-sensitive acid generator, [C] 3.0 parts by mass of (C-3) as an acid diffusion control agent, [E] 3.0 parts by mass of (E-2) as a high-fluorine-content resin (solids), and [D] 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) as a solvent, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0253] 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-60) 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.

[0254] 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 alkaline developed using a 2.38 mass% TMAH aqueous solution as the alkaline developer, washed with water after development, and then dried to form a positive-type resist pattern (32 nm line and space pattern).

[0255] The resist patterns using the above-mentioned positive-type radiation-sensitive resin composition for ArF exposure were evaluated in the same manner as the resist patterns using the above-mentioned positive-type radiation-sensitive resin composition for EUV exposure. As a result, the radiation-sensitive resin composition of Example 60 showed good sensitivity, LWR performance, pattern rectangularity, and etching resistance even when a positive-type resist pattern was formed by ArF exposure.

[0256] [Preparation of negative-type radiation-sensitive resin composition for EUV exposure, formation and evaluation of resist patterns using this composition] [Example 61] A radiation-sensitive resin composition (J-61) was prepared by mixing [A] 100 parts by mass of (A-15) as a resin, [B] 15.0 parts by mass of (B-4) as a radiation-sensitive acid generator, [C] 10.0 parts by mass of (C-2) as an acid diffusion control agent, [E] 3.0 parts by mass (solids) of (E-5) as a high-fluorine-content resin, and [D] 6,110 parts by mass 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.

[0257] 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 radiation-sensitive resin composition (J-61) was applied using the same spin coater, and PB (photovoltaic bombardment) 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.

[0258] Next, the resist film was exposed using an EUV lithography system (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 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).

[0259] 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 61 showed good sensitivity, CDU performance, depth of field, and pattern rectangularity even when a negative-type resist pattern was formed by EUV exposure. [Industrial applicability]

[0260] The radiation-sensitive resin composition and resist pattern formation method described above allow for the formation of resist patterns with good sensitivity to exposure light and excellent LWR and CDU performance. Therefore, these can be suitably used in semiconductor device processing processes and the like, where further miniaturization is expected in the future.

Claims

1. A sulfonium salt compound represented by the following formula (1). 【Chemistry 1】 (In the formula, R 1 This refers to a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 40 carbon atoms, or a group in which the methylene group constituting the alicyclic hydrocarbon group is replaced by an ether bond. R f1 and R f2 Each of these is independently a fluorine atom or a monovalent fluorinated hydrocarbon group. I understand 1 m is an integer between 1 and 4. 1 If the number is between 2 and 4, multiple R f1 and R f2 They are either identical or different in part or in whole. R 2 and R 3 are each independently a hydrogen atom, a monovalent hydrocarbon group, or a monovalent fluorinated hydrocarbon group. I understand 2 It is either 0 or 1. X is a linker containing a divalent heteroatom. R 4 ~R 7 Each of these is independently a hydrogen atom, a hydroxyl group, a monovalent hydrocarbon group, or an ester group. n 1 and n 2 Each of these is an integer between 1 and 3, and there are multiple R 4 ~R 7 They are either identical or different in part or in whole. R 8 This is a monovalent alicyclic hydrocarbon group, a monovalent fluorinated hydrocarbon group, a halogen atom, a monovalent aromatic hydrocarbon group, or -Y-R 8' It is a monovalent group represented by (Y represents -CO-, -COO-, -OCO-, R 8' (This refers to a monovalent hydrocarbon group having 1 to 20 carbon atoms.) l is an integer from 0 to 5, and if l is from 2 to 5, multiple R 8 (These are either identical or different in part or in whole.)

2. A radiation-sensitive acid generator comprising a sulfonium salt compound represented by the following formula (1). 【Chemistry 2】 (In the formula, R 1 This refers to a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 40 carbon atoms, or a group in which the methylene group constituting the alicyclic hydrocarbon group is replaced by an ether bond. R f1 and R f2 Each of these is independently a fluorine atom or a monovalent fluorinated hydrocarbon group. I understand 1 m is an integer between 1 and 4. 1 If the number is between 2 and 4, multiple R f1 and R f2 They are either identical or different in part or in whole. R 2 and R 3 Each of these is independently a hydrogen atom, a monovalent hydrocarbon group, or a monovalent fluorinated hydrocarbon group. I understand 2 It is either 0 or 1. X is a linker containing a divalent heteroatom. R 4 ~R 7 Each of these is independently a hydrogen atom, a hydroxyl group, a monovalent hydrocarbon group, or an ester group. n 1 and n 2 Each of these is an integer between 1 and 3, and there are multiple R 4 ~R 7 They are either identical or different in part or in whole. R 8 This is a monovalent alicyclic hydrocarbon group, a monovalent fluorinated hydrocarbon group, a halogen atom, a monovalent aromatic hydrocarbon group, or -Y-R 8' It is a monovalent group represented by (Y represents -CO-, -COO-, -OCO-, R 8' (This refers to a monovalent hydrocarbon group having 1 to 20 carbon atoms.) l is an integer from 0 to 5, and if l is from 2 to 5, multiple R 8 (These are either identical or different in part or in whole.)

3. A radiation-sensitive acid generator according to claim 2, for use in organic solvent development.

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