Compound and resin

Abstract

To provide a radiation-sensitive resin composition capable of exhibiting excellent levels of sensitivity, LWR performance, and pattern rectangularity, and to provide a method for forming a resist pattern.SOLUTION: The radiation-sensitive resin composition contains: a resin containing a structural unit (A) represented by the following formula (1) and a structural unit (B) having an acid-dissociable group; a radiation-sensitive acid generator; and a solvent. (In the formula, R1 and La1 each represent a C1-20 hydrocarbon group unsubstituted or substituted with a halogen atom; X represents -O- or -S-; and RP represents a monovalent organic group having at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure.)SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Photolithography techniques using resist compositions are used to form fine circuits in semiconductor elements. In a typical procedure, for example, a resist composition coating is exposed to radiation through a mask pattern to generate an acid, and a difference in the solubility of the resin in alkaline or organic developers occurs between the exposed and unexposed areas through a reaction catalyzed by the acid, thereby forming a resist pattern on a substrate.

[0003] The photolithography technology mentioned above is promoting pattern miniaturization by using short-wavelength radiation such as ArF excimer lasers, and also by using liquid immersion lithography, in which exposure is performed with the space between the lens of the exposure device and the resist film filled with a liquid medium. Lithography using even shorter-wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet) is also being considered as a next-generation technology.

[0004] With the advancement of exposure technology, a technique is being developed that achieves pattern resolution on the order of microns to submicrons by utilizing a resist composition containing a resin having an alicyclic group (Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4073266 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, as resist patterns have become increasingly finer, there has been a demand for rectangular resist pattern shapes, along with sensitivity and line width roughness (LWR), which indicates variations in the line width of the resist pattern, and further improvements in resist performance are required. Furthermore, next-generation exposure technologies such as electron beam exposure require resist performance that is equal to or better than that of exposure technologies using ArF excimer lasers.

[0007] An object of the present invention is to provide a radiation-sensitive resin composition and a method for forming a resist pattern that are capable of exhibiting excellent levels of sensitivity, LWR performance, and pattern rectangularity. [Means for solving the problem]

[0008] As a result of extensive research into solving the above problems, the inventors of the present application have found that the above object can be achieved by employing the following configuration, and have thus completed the present invention.

[0009] In one embodiment, the present invention provides a polymerizable composition comprising a resin including a structural unit (A) represented by the following formula (1) and a structural unit (B) having an acid-dissociable group, a radiation-sensitive acid generator; Solvent and The present invention relates to a radiation-sensitive resin composition comprising: [ka] (In the above formula (1), R 1 is a halogen atom-substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. X is —O— or —S—. L a1 is a divalent hydrocarbon group having 1 to 10 carbon atoms and which is either substituted or unsubstituted with a halogen atom. R P is a monovalent organic group having at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure.

[0010] Since the radiation-sensitive resin composition contains a resin having the structural unit (A) represented by the above formula (1) as one structural unit, a resist film using the composition can exhibit sufficient levels of sensitivity, LWR performance, and resist pattern rectangularity not only when exposed to an ArF excimer laser or the like, but also when exposed to EUV (extreme ultraviolet) or the like. The reason for this is presumed to be as follows, without being bound by any theory. R in the above formula (1) P At least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure (hereinafter also referred to as "lactone structure, etc.") in the exposed area is ring-opened by the action of alkali to form a polar structure, thereby improving solubility in a developer. On the other hand, in the unexposed area, the lactone structure, etc. does not ring-open and maintains hydrophobicity, while R 1 The hydrophobicity of the hydrocarbon group represented by the formula (I) allows the structural unit (A) to exhibit hydrophobicity as a whole, thereby suppressing dissolution in the developer. It is believed that the synergistic effect of improving the solubility of the resin in the developer in the exposed areas and suppressing the dissolution of the resin in the developer in the unexposed areas improves the dissolution contrast between the two, thereby improving the rectangularity of the pattern. The organic group refers to a group containing at least one carbon atom.

[0011] In another embodiment, the present invention provides a method for producing a resist film from the radiation-sensitive resin composition, a step of exposing the resist film to light; and developing the exposed resist film The present invention relates to a method for forming a resist pattern, comprising the steps of:

[0012] According to this formation method, the radiation-sensitive resin composition having excellent resist properties is used, so that a high-quality resist pattern can be efficiently formed. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Radiation sensitive resin composition> The radiation-sensitive resin composition according to this embodiment (hereinafter also simply referred to as the "composition") contains a resin, a radiation-sensitive acid generator, and a solvent. The composition may contain other optional components as long as the effects of the present invention are not impaired.

[0014] [resin] (Structural unit (A)) The resin is an assembly of polymers containing a structural unit (A) represented by the following formula (1) and a structural unit (B) having an acid-dissociable group (hereinafter, this resin is also referred to as a "base resin"). [ka]

[0015] In the above formula (1), R 1 is a halogen atom-substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. X is —O— or —S—. L a1 is a divalent hydrocarbon group having 1 to 10 carbon atoms and which is either substituted or unsubstituted with a halogen atom. R P is a monovalent organic group having at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure.

[0016] The radiation-sensitive resin composition has excellent sensitivity, LWR performance, and pattern rectangularity because the resin contains the structural unit (A).

[0017] Above R 1 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, or a combination thereof.

[0018] Above R 1 Examples of the chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula include a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, and a linear or branched unsaturated hydrocarbon group having 1 to 20 carbon atoms.

[0019] Above R 1 Examples of the alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include monocyclic or polycyclic saturated hydrocarbon groups, and monocyclic or polycyclic unsaturated hydrocarbon groups. Preferred monocyclic saturated hydrocarbon groups are cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Preferred polycyclic cycloalkyl groups are bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl groups. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms constituting the alicyclic ring are bonded together by a bonding chain containing one or more carbon atoms.

[0020] Above R 1 Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by the formula: Examples thereof include aryl groups such as phenyl, tolyl, xylyl, naphthyl and anthryl groups; and aralkyl groups such as benzyl, phenethyl and naphthylmethyl groups.

[0021] Above R 1 Some or all of the hydrogen atoms in these monovalent hydrocarbon groups having 1 to 20 carbon atoms and represented by the following formula may be substituted with halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc. Of course, they may not be substituted with any halogen atoms at all.

[0022] Above R 1 It is preferable that the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) does not contain a heteroatom such as an oxygen atom or a sulfur atom (excluding the above-mentioned halogen atoms). 1 By suppressing the occurrence of polarization or polarity in the structure unit (A), the hydrophobicity of the unexposed area of ​​the structure unit (A) can be maintained, and excellent pattern rectangularity can be achieved.

[0023] The above L a1 As the divalent hydrocarbon group having 1 to 10 carbon atoms represented by the above R 1Among the monovalent hydrocarbon groups having 1 to 20 carbon atoms represented by the following formula, groups in which one hydrogen atom has been further removed from a group having 1 to 10 carbon atoms are preferred.

[0024] In particular, in terms of the balance between the hydrophobicity of the structural unit (A) in the exposed area and the hydrophilicity due to the generation of a polar structure, and the copolymerizability of the monomer that gives the structural unit (A) with other monomers, L a1 is preferably a divalent chain hydrocarbon group, and particularly preferably a methylene group.

[0025] Above R P The organic group represented by the formula (I) is not particularly limited as long as it has at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. The organic group may have a chain structure, a cyclic structure, or a combination thereof. Examples of the chain structure include chain hydrocarbon groups, whether saturated or unsaturated, linear or branched. Examples of the cyclic structure include cyclic hydrocarbon groups, whether alicyclic, aromatic, or heterocyclic. Other examples include groups in which some or all of the hydrogen atoms contained in groups having a chain structure or a cyclic structure have been substituted with substituents, and groups containing CO, CS, O, S, SO, or NR', or a combination of two or more of these, between the carbon atoms of these groups.

[0026] Examples of the substituent that substitutes some or all of the hydrogen atoms of the organic group include halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms; hydroxy groups; carboxy groups; cyano groups; nitro groups; alkyl groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, acyloxy groups, and groups in which the hydrogen atoms of these groups are substituted with halogen atoms; and oxo groups (=O).

[0027] R in the above formula (1) P is preferably represented by the following formula (A). [ka]

[0028] In the above formula (A), L a2 is a single bond or a substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms. Y is a single bond or a divalent linking group selected from -O-, -CO-, -NH-, -SO2- or a combination thereof. L a3 is a single bond or a substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms. R P1 is a substituted or unsubstituted lactone structure, cyclic carbonate structure or sultone structure. * is a bond to —O— in the above formula (1).

[0029] The above L a2 and L a3 As the divalent hydrocarbon group having 1 to 10 carbon atoms represented by the formula a1 Examples of the substituent that can substitute a part or all of the hydrogen atoms contained in this hydrocarbon group include the above-mentioned substituents. Examples of the substituent that can substitute a part or all of the hydrogen atoms contained in this hydrocarbon group include the above-mentioned substituents. Examples of the substituents that can be used include groups that contain CO, CS, O, S, SO, or NR', or a combination of two or more of these, between carbon atoms of these groups.

[0030] Above R P1 Examples of the lactone structure, cyclic carbonate structure and sultone structure represented by the formula (I) include structures represented by the following formulas (A-1) to (A-15). [ka]

[0031] In the above formula, R L2 ~R L4 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxy group, a hydroxymethyl group, or a dimethylamino group. L2 ~R L4 If there are multiple RL2 ~R L4 may be the same or different. X is an oxygen atom or a methylene group. k is an integer of 0 to 3. m is an integer of 1 to 3. * represents -L in the above formula (A). a3 - is a connecting hand with.

[0032] Specific examples of the structural unit (A) include structural units represented by the following formulas (1-1) to (1-20). [ka]

[0033] [ka]

[0034] The base resin may contain one type of structural unit (A) or a combination of two or more types.

[0035] The lower limit of the content of the structural unit (A) (the total content when multiple types of structural unit (A) are contained) relative to all structural units constituting the base resin is preferably 5 mol%, more preferably 6 mol%, even more preferably 8 mol%, and particularly preferably 10 mol%. The upper limit of the content is preferably 80 mol%, more preferably 70 mol%, even more preferably 65 mol%, and particularly preferably 60 mol%. By ensuring that the content of the structural unit (A) falls within the above range, the sensitivity, LWR performance, and pattern rectangularity of the resist film obtained from the radiation-sensitive resin composition can be further improved.

[0036] (Method for synthesizing a monomer that provides structural unit (A)) The monomer that provides the structural unit (A) can be synthesized, for example, according to the following scheme: An example in which X in the above formula (1) is an oxygen atom will be explained below. [ka] (In the above scheme, E is a halogen atom. R 1 , La1 and R P is the same as the above formula (1).

[0037] A halogenated raw material with a protected ester moiety and R in the above formula (1) 1 to form an ether derivative, followed by deprotection by alkaline hydrolysis, and finally by reacting with an alcohol having a structure corresponding to R P By reacting the alcohol having the structure corresponding to the formula (1), a monomer giving the structural unit (A) represented by formula (1') can be synthesized. For other structures, the linking group and R of the starting material can be used. 1 Alcohols having the structure R P The compound can be synthesized by appropriately changing an alcohol having the structure shown below.

[0038] In addition to the structural unit (A), the base resin preferably contains a structural unit having an acid-dissociable group (hereinafter also referred to as "structural unit (B)") and a structural unit (C) containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure (described below) (excluding structural units corresponding to the structural unit (A)). The base resin may also contain structural units other than the structural units (B) and (C). The term "acid-dissociable group" refers to a group that substitutes a hydrogen atom in a carboxy group, a phenolic hydroxyl group, an alcoholic hydroxyl group, a sulfo group, or the like, and dissociates under the action of an acid. The radiation-sensitive resin composition exhibits excellent pattern formability due to the presence of the structural unit (B). Each structural unit will be described below.

[0039] (Structural unit (B)) The structural unit (B) is a structural unit having an acid-dissociable group. The structural unit (B) is not particularly limited as long as it contains an acid-dissociable group, and examples thereof include a structural unit having a tertiary alkyl ester moiety, a structural unit having a structure in which the hydrogen atom of a phenolic hydroxyl group is substituted with a tertiary alkyl group, and a structural unit having an acetal bond. From the viewpoint of improving the pattern formability of the radiation-sensitive resin composition, a structural unit represented by the following formula (2) (hereinafter also referred to as "structural unit (B-1)") is preferred.

[0040] [ka]

[0041] In the above formula (2), R 7 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 8 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. 9 and R 10 are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded.

[0042] Above R 7 As the alkyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (I-1), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0043] Above R 8 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0044] Above R 8 ~R 10 Examples of the chain hydrocarbon group having 1 to 10 carbon atoms represented by the formula include a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, and a linear or branched unsaturated hydrocarbon group having 1 to 10 carbon atoms.

[0045] Above R 8 ~R 10Examples of the alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include monocyclic or polycyclic saturated hydrocarbon groups, and monocyclic or polycyclic unsaturated hydrocarbon groups. Preferred monocyclic saturated hydrocarbon groups are cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Preferred polycyclic cycloalkyl groups are bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl groups. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms constituting the alicyclic ring are bonded together by a bonding chain containing one or more carbon atoms.

[0046] Above R 8 Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by the formula: Examples thereof include aryl groups such as phenyl, tolyl, xylyl, naphthyl and anthryl groups; and aralkyl groups such as benzyl, phenethyl and naphthylmethyl groups.

[0047] Above R 8 As the alkyl group, a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, or an alicyclic hydrocarbon group having 3 to 20 carbon atoms is preferred.

[0048] Above R 9 and R 10 The divalent alicyclic group having 3 to 20 carbon atoms, which is formed by combining chain hydrocarbon groups or alicyclic hydrocarbon groups represented by the formula (I) together with the carbon atoms to which they are bonded, is not particularly limited as long as it is a group formed by removing two hydrogen atoms from the same carbon atom constituting a carbon ring of a monocyclic or polycyclic alicyclic hydrocarbon having the above carbon number. Either a monocyclic hydrocarbon group or a polycyclic hydrocarbon group may be used, and the polycyclic hydrocarbon group may be either a bridged alicyclic hydrocarbon group or a fused alicyclic hydrocarbon group, and may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group. Note that a fused alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group formed in such a way that multiple alicyclic rings share a side (a bond between two adjacent carbon atoms).

[0049] Among the monocyclic alicyclic hydrocarbon groups, preferred saturated hydrocarbon groups include cyclopentanediyl, cyclohexanediyl, cycloheptanediyl, and cyclooctanediyl groups, while preferred unsaturated hydrocarbon groups include cyclopentenediyl, cyclohexenediyl, cycloheptenediyl, cyclooctenediyl, and cyclodecenediyl groups. Preferred polycyclic alicyclic hydrocarbon groups include bridged alicyclic saturated hydrocarbon groups, such as bicyclo[2.2.1]heptane-2,2-diyl (norbornane-2,2-diyl), bicyclo[2.2.2]octane-2,2-diyl, and tricyclo[3.3.1.1]heptane-2,2-diyl. 3,7 ]Decane-2,2-diyl group (adamantane-2,2-diyl group) and the like are preferred.

[0050] Among these, R 8 is an alkyl group having 1 to 4 carbon atoms, and R 9 and R 10 The alicyclic structure formed by combining these together with the carbon atoms to which they are bonded is preferably a polycyclic or monocyclic cycloalkane structure.

[0051] Examples of the structural unit (B-1) include structural units represented by the following formulas (3-1) to (3-6) (hereinafter also referred to as "structural units (B-1-1) to (B-1-6)").

[0052] [ka]

[0053] In the above formulas (3-1) to (3-6), R 7 ~R 10 has the same meaning as in the above formula (2). i and j each independently represent an integer of 1 to 4. k and l are 0 or 1.

[0054] i and j are preferably 1. 8 R is preferably a methyl group, an ethyl group, or an isopropyl group. 9 and R 10 As the alkyl group, a methyl group or an ethyl group is preferred.

[0055] The base resin may contain one type of structural unit (B) or a combination of two or more types.

[0056] The lower limit of the content of the structural unit (B) (the total content when multiple types of structural unit (B) are contained) relative to all structural units constituting the base resin is preferably 10 mol%, more preferably 20 mol%, and even more preferably 25 mol%. The upper limit of the content is preferably 90 mol%, more preferably 80 mol%, even more preferably 75 mol%, and particularly preferably 70 mol%. By setting the content of the structural unit (B) within the above range, the pattern formability of the radiation-sensitive resin composition can be further improved.

[0057] (Structural unit (C)) The structural unit (C) is a structural unit containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure (excluding structural units corresponding to the structural unit (A)). By further including the structural unit (C), the base resin can adjust its solubility in a developer, thereby improving the lithography performance, such as resolution, of the radiation-sensitive resin composition. In addition, the adhesion between a resist pattern formed from the base resin and a substrate can be improved.

[0058] Examples of the structural unit (C) include structural units represented by the following formulae (T-1) to (T-10).

[0059] [ka]

[0060] In the above formula, R L1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L2 ~R L5are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxy group, a hydroxymethyl group, or a dimethylamino group. L4 and R L5 and may be combined together to form a divalent alicyclic group having 3 to 8 carbon atoms 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 of 0 to 3. m is an integer of 1 to 3.

[0061] Above R L4 and R L5 Examples of the divalent alicyclic group having 3 to 8 carbon atoms formed by combining these together with the carbon atoms to which they are bonded include R 9 and R 10 Examples include divalent alicyclic groups having 3 to 20 carbon atoms, which are formed by combining chain hydrocarbon groups or alicyclic hydrocarbon groups represented by the following formula (I) together with the carbon atoms to which they are bonded, and which have 3 to 8 carbon atoms. One or more hydrogen atoms on this alicyclic group may be substituted with a hydroxy group.

[0062] The above L 2 Examples of the divalent linking group represented by the formula (I) include a divalent linear or branched hydrocarbon group having 1 to 10 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, or a group composed of one or more of these hydrocarbon groups and at least one group selected from -CO-, -O-, -NH-, and -S-.

[0063] Of these, the structural unit (C) is preferably a structural unit containing a lactone structure, more preferably a structural unit containing a norbornane lactone structure, and even more preferably a structural unit derived from norbornane lactone-yl (meth)acrylate.

[0064] The lower limit of the content of the structural unit (C) is preferably 2 mol%, more preferably 4 mol%, and even more preferably 5 mol%, based on all structural units constituting the base resin. The upper limit of the content is preferably 50 mol%, more preferably 45 mol%, and even more preferably 40 mol%. By setting the content of the structural unit (C) within the above range, the radiation-sensitive resin composition can further improve lithography performance such as resolution and adhesion of the formed resist pattern to the substrate.

[0065] (Structural unit (D)) The base resin may contain other structural units in addition to the structural units (B) and (C). Examples of the other structural units include a structural unit (D) containing a polar group (excluding those corresponding to the structural unit (C)). By further containing a structural unit containing a polar group, the base resin can adjust its solubility in a developer, thereby improving the lithography performance, such as resolution, of the radiation-sensitive resin composition. Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a nitro group, and a sulfonamide group. Among these, a hydroxy group and a carboxy group are preferred, and a hydroxy group is more preferred.

[0066] Examples of the structural unit (D) having a polar group include structural units represented by the following formula:

[0067] [ka]

[0068] In the above formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0069] When the base resin has the structural unit having the polar group, the lower limit of the content of the structural unit (D) having the polar group, based on all structural units constituting the base resin, is preferably 2 mol%, more preferably 5 mol%, and even more preferably 8 mol%. The upper limit of the content is preferably 40 mol%, more preferably 30 mol%, and even more preferably 20 mol%. By setting the content of the structural unit (D) having a polar group within the above range, the lithography performance such as resolution of the radiation-sensitive resin composition can be further improved.

[0070] (Structural unit (E)) The base resin may contain, as another structural unit, a structural unit containing a phenolic hydroxyl group (hereinafter also referred to as "structural unit (E)") in addition to the structural unit (D) having the polar group. The structural unit (E) contributes to improving etching resistance and the difference in developer solubility (dissolution contrast) between exposed and unexposed areas. This is particularly suitable for pattern formation using exposure to radiation with a wavelength of 50 nm or less, such as electron beams or EUV. In this case, the resin preferably contains the structural unit (B) in addition to the structural unit (E).

[0071] Examples of the structural unit (E) include structural units represented by the following formula (af):

[0072] [ka]

[0073] In the above formula (af), R AF1 is a hydrogen atom or a methyl group. AF is a single bond, -COO-, -O- or -CONH-. AF2 is a monovalent organic group having 1 to 20 carbon atoms or a halogen atom. f1 is an integer from 0 to 3. f1 If is 2 or 3, multiple R AF2 may be the same or different. f2 is an integer between 1 and 3, where n f1+n f2 is less than or equal to 5. af is an integer between 0 and 2.

[0074] Above R AF1 is preferably a hydrogen atom from the viewpoint of copolymerizability of the monomer that gives the structural unit (E).

[0075] L AF is preferably a single bond or —COO—.

[0076] The organic group in the base resin refers to a group containing at least one carbon atom.

[0077] Above R AF2 Examples of the monovalent organic group having 1 to 20 carbon atoms represented by the formula (I) include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group containing a divalent heteroatom-containing group between carbon atoms of the hydrocarbon group or at the terminal on the bond side, and a group in which some or all of the hydrogen atoms in the group or the hydrocarbon group have been substituted with a monovalent heteroatom-containing group.

[0078] Above R AF2 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula: Alkyl groups such as methyl, ethyl, propyl, and butyl groups; alkenyl groups such as ethenyl, propenyl, and butenyl; chain hydrocarbon groups such as alkynyl groups such as ethynyl, propynyl, and butynyl; cycloalkyl groups such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, a norbornyl group, and an adamantyl group; alicyclic hydrocarbon groups such as cycloalkenyl groups such as cyclopropenyl, cyclopentenyl, cyclohexenyl, and norbornenyl; aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; Examples include aromatic hydrocarbon groups such as aralkyl groups such as benzyl, phenethyl, and naphthylmethyl groups.

[0079] Above R AF2 As the alkyl group, a chain hydrocarbon group or a cycloalkyl group is preferable, an alkyl group or a cycloalkyl group is more preferable, and a methyl group, an ethyl group, a propyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, and an adamantyl group are further preferable.

[0080] Examples of the divalent heteroatom-containing group include -O-, -CO-, -CO-O-, -S-, -CS-, -SO2-, -NR'-, and groups formed by combining two or more of these. Suitable examples of the divalent heteroatom-containing group include a methoxy group, an ethoxy group, and a propoxy group. R' is a hydrogen atom or a monovalent hydrocarbon group.

[0081] Examples of the monovalent heteroatom-containing group include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, hydroxy group, carboxy group, cyano group, amino group and sulfanyl group (-SH).

[0082] The halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom.

[0083] Above n f1 is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0084] Above n f2 As the group, 1 and 2 are preferred, and 1 is more preferred.

[0085] Above n af As the number, 0 and 1 are preferred, and 0 is more preferred.

[0086] The structural unit (E) is preferably a structural unit represented by any of the following formulae (a1-1) to (a1-9).

[0087] [ka]

[0088] In the above formulas (a1-1) to (a1-9), R AF1 is the same as the above formula (af).

[0089] Among these, the structural units represented by the above formulas (a1-1) to (a1-7) are preferred, with the structural unit represented by the above formula (a1-1) being more preferred.

[0090] When the base resin contains the structural unit (E), the lower limit of the content of the structural unit (E) is preferably 5 mol%, more preferably 10 mol%, and even more preferably 15 mol%, based on all structural units constituting the base resin. The upper limit of the content is preferably 50 mol%, more preferably 40 mol%, and even more preferably 30 mol%. By setting the content of the structural unit (E) within the above range, the sensitivity, LWR performance, and pattern rectangularity of the resist film obtained from the radiation-sensitive resin composition can be further improved.

[0091] However, since polymerization of hydroxystyrene is inhibited by the influence of the phenolic hydroxyl group, it is preferable to polymerize the phenolic hydroxyl group in a state where it is protected by a protecting group such as an alkali-dissociable group, and then to obtain the structural unit (E) by deprotection through hydrolysis. The structural unit that gives the structural unit (E) upon hydrolysis is preferably represented by the following formula (af-1):

[0092] [ka]

[0093] In the above formula (af-1), R AF1 , L AF , R AF2 , n f1 , n f2 and n af is the same as the above formula (af). 12 R is a monovalent hydrocarbon group or alkoxy group having 1 to 20 carbon atoms. 12The monovalent hydrocarbon group having 1 to 20 carbon atoms is R 8 Examples of the alkoxy group include a methoxy group, an ethoxy group, and a tert-butoxy group.

[0094] Above R 12 As the alkyl group, an alkyl group and an alkoxy group are preferred, and among these, a methyl group and a tert-butoxy group are more preferred.

[0095] The fluorine content in the base resin is preferably 10% by mass or less. The upper limit of the fluorine content is more preferably 9% by mass, further preferably 8% by mass, and particularly preferably 7% by mass. The lower limit of the fluorine content is preferably 0% by mass (i.e., no fluorine atoms are contained). By setting the fluorine content in the base resin within the above range, the dissolution contrast between exposed and unexposed areas can be improved, and desired resist performance can be exhibited.

[0096] (Method of synthesizing base resin) The base resin can be synthesized, for example, by polymerizing monomers that provide the respective structural units in an appropriate solvent using a radical polymerization initiator or the like.

[0097] Examples of the radical polymerization initiator include azo radical initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl 2,2'-azobisisobutyrate; and peroxide radical 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 initiators can be used alone or in combination of two or more.

[0098] Examples of the solvent used in the polymerization 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 the solvent include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2-pentanol, etc. These solvents used in the polymerization may be used alone or in combination of two or more.

[0099] The reaction temperature in the polymerization is usually 40° C. to 150° C., and preferably 50° C. to 120° C. The reaction time is usually 1 hour to 48 hours, and preferably 1 hour to 24 hours.

[0100] The molecular weight of the base resin is not particularly limited, but the weight average molecular weight (Mw) of the base resin as converted to polystyrene 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 be reduced. If the Mw of the base resin is above the upper limit, the developability of the resist film may be reduced.

[0101] The ratio (Mw / Mn) of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the base resin as determined by GPC is usually 1 or more and 5 or less, preferably 1 or more and 3 or less, and more preferably 1 or more and 2 or less.

[0102] The Mw and Mn of the resin in this specification are values ​​measured using gel permeation chromatography (GPC) under the following conditions.

[0103] GPC columns: 2 G2000HXL, 1 G3000HXL, 1 G4000HXL (all manufactured by Tosoh) Column temperature: 40℃ Elution 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

[0104] The content of the base resin is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more, based on the total solid content of the radiation-sensitive resin composition.

[0105] [Other resins] The radiation-sensitive resin composition of this embodiment may contain, as an additional resin, a resin having a higher mass content of fluorine atoms than the base resin (hereinafter also referred to as a "high-fluorine content resin"). When the radiation-sensitive resin composition contains a high-fluorine content resin, the high-fluorine content resin can be unevenly distributed in the surface layer of the resist film relative to the base resin, thereby improving the water repellency of the surface of the resist film during immersion exposure.

[0106] The high-fluorine content resin preferably has, for example, at least one of the structural unit (B) and the structural unit (C) in the base resin, and also has a structural unit represented by the following formula (5) (hereinafter also referred to as "structural unit (F)").

[0107] [ka]

[0108] In the above formula (5), R 13 is a hydrogen atom, a methyl group, or a trifluoromethyl group. G is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2ONH-, -CONH-, or -OCONH-. R 14 is a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0109] Above R 13 As the alkyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (F), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0110] Above G L As the group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (F), a single bond and -COO- are preferred, and -COO- is more preferred.

[0111] Above R 14 Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula include a linear or branched alkyl group having 1 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.

[0112] Above R 14 Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.

[0113] Above R 14 As the alkyl group, a fluorinated chain hydrocarbon group is preferable, a fluorinated alkyl group is more preferable, and a 2,2,2-trifluoroethyl group, a 1,1,1,3,3,3-hexafluoropropyl group, and a 5,5,5-trifluoro-1,1-diethylpentyl group are even more preferable.

[0114] When the high-fluorine-content resin has the structural unit (F), the lower limit of the content of the structural unit (F) is preferably 20 mol%, more preferably 30 mol%, and even more preferably 35 mol%, based on all structural units constituting the high-fluorine-content resin. The upper limit of this content is preferably 95 mol%, more preferably 90 mol%, and even more preferably 85 mol%. By setting the content of the structural unit (F) within this range, the mass content of fluorine atoms in the high-fluorine-content resin can be more appropriately adjusted, further promoting uneven distribution of fluorine atoms in 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.

[0115] The high-fluorine content resin may have a fluorine atom-containing structural unit represented by the following formula (f-2) (hereinafter also referred to as structural unit (G)) in addition to the structural unit (F): When the high-fluorine content resin has the structural unit (G), the solubility of the high-fluorine content resin in an alkaline developer is improved, and the occurrence of development defects can be suppressed.

[0116] [ka]

[0117] The structural unit (G) is roughly classified into two types: (x) a case having an alkali-soluble group, and (y) a case having a group that dissociates under the action of alkali to increase the solubility in an alkali developer (hereinafter simply referred to as an "alkali-dissociable group"). In both (x) and (y), R C R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. D is a single bond, a hydrocarbon group having 1 to 20 carbon atoms and a valence of (s+1), and R of this hydrocarbon group E Oxygen atom, sulfur atom, -NR dd -, a carbonyl group, -COO-, or -CONH- is bonded to the hydrocarbon group, or a structure in which some of the hydrogen atoms in the hydrocarbon group are substituted with an organic group having a hetero atom. dd is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer of 1 to 3.

[0118] When the structural unit (G) has an alkali-soluble group (x), R F is a hydrogen atom, and A 1 is an oxygen atom, -COO-* or -SO2O-*. * is R F The binding site of W is shown. 1 A is a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group. 1 is an oxygen atom, W 1 is A 1 is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group on the carbon atom to which R is bonded. E is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, multiple R E , W 1 , A 1 and R F may be the same or different. When the structural unit (G) has (x) an alkali-soluble group, it is possible to increase the affinity for an alkaline developer and suppress development defects. As the structural unit (G) having (x) an alkali-soluble group, A 1 is an oxygen atom and W 1 It is particularly preferred that is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.

[0119] When the structural unit (G) has an alkali-dissociable group (y), 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. * is R F The binding site of W is shown. 1 R is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. E A is a single bond or a divalent organic group having 1 to 20 carbon atoms. 1 When is -COO-* or -S02O-*, W 1 or R F is A 1A has a fluorine atom on the carbon atom bonded to or adjacent to A. 1 is an oxygen atom, W 1 , R E is a single bond, and R D R is a hydrocarbon group with 1 to 20 carbon atoms E A carbonyl group is bonded to the end of the R F is an organic group having a fluorine atom. When s is 2 or 3, multiple R E , W 1 , A 1 and R F may be the same or different. When the structural unit (G) has an alkali-dissociable group (y), the surface of the resist film changes from hydrophobic to hydrophilic in the alkaline development step. As a result, the affinity to the developer is significantly increased, and development defects can be more efficiently suppressed. As the structural unit (V) having an alkali-dissociable group (y), A 1 is -COO-* and R F Or W 1 It is particularly preferred that both of them have a fluorine atom.

[0120] R C As the alkyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (G), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0121] R E When is a divalent organic group, it is preferably a group having a lactone structure, more preferably a group having a polycyclic lactone structure, and more preferably a group having a norbornane lactone structure.

[0122] When the high-fluorine-content resin has the structural unit (G), the lower limit of the content of the structural unit (G) is preferably 40 mol%, more preferably 50 mol%, even more preferably 60 mol%, and particularly preferably 70 mol%, based on all structural units constituting the high-fluorine-content resin. The upper limit of this content is preferably 98 mol%, more preferably 95 mol%, and even more preferably 92 mol%. By setting the content of the structural unit (V) within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0123] The lower limit of Mw of the high fluorine content resin is preferably 1,000, more preferably 2,000, further preferably 3,000, and particularly preferably 5,000. The upper limit of Mw is preferably 50,000, more preferably 30,000, further preferably 20,000, and particularly preferably 15,000.

[0124] The lower limit of Mw / Mn of the high fluorine content resin is usually 1, and more preferably 1.1. The upper limit of the Mw / Mn is usually 5, and is preferably 3, more preferably 2, and even more preferably 1.9.

[0125] The lower limit of the content of the high-fluorine content resin is preferably 0.1 parts by mass, more preferably 1 part by mass, even more preferably 1.5 parts by mass, and particularly preferably 2 parts by mass, relative to 100 parts by mass of the base resin. The upper limit of the content is preferably 15 parts by mass, more preferably 12 parts by mass, even more preferably 10 parts by mass, and particularly preferably 8 parts by mass.

[0126] By setting the content of the high-fluorine-containing resin within the above range, the high-fluorine-containing resin can be more effectively distributed unevenly on the surface layer of the resist film, thereby further improving the water repellency of the surface of the resist film during immersion lithography. The radiation-sensitive resin composition may contain one or more high-fluorine-containing resins.

[0127] (Method for synthesizing high fluorine content resin) The high fluorine content resin can be synthesized by the same method as the above-mentioned method for synthesizing the base resin.

[0128] [Radiation-sensitive acid generator] A radiation-sensitive acid generator is a component that generates an acid upon exposure. The acid generated upon exposure is thought to have two functions in the radiation-sensitive resin composition depending on the strength of the acid. The first function is to dissociate the acid-dissociable group of the structural unit (B) in the resin containing the structural unit (B) having an acid-dissociable group, thereby generating a carboxyl group or the like. A radiation-sensitive acid generator having this first function is referred to as a radiation-sensitive acid generator (I). The second function is to suppress the diffusion of the acid generated from the radiation-sensitive acid generator (I) in unexposed areas by not substantially dissociating the acid-dissociable group of the structural unit (B) in the resin under pattern formation conditions using the radiation-sensitive resin composition. A radiation-sensitive acid generator having this second function is referred to as a radiation-sensitive acid generator (II). The acid generated from the radiation-sensitive acid generator (II) can be said to be a relatively weaker acid (an acid with a larger pKa) than the acid generated from the radiation-sensitive acid generator (I). Whether the radiation-sensitive acid generator functions as radiation-sensitive acid generator (I) or radiation-sensitive acid generator (II) is determined by the energy required for dissociation of the acid-dissociable group in the structural unit (B) of the resin, the thermal energy conditions applied when forming a pattern using the radiation-sensitive resin composition, etc. The radiation-sensitive acid generator may be contained in the radiation-sensitive resin composition in a form in which it exists as a compound alone (isolated from the polymer), in a form in which it is incorporated as part of the polymer, or in both of these forms, but a form in which it exists as a compound alone is preferred.

[0129] When the radiation-sensitive resin composition contains the radiation-sensitive acid generator (I), the polarity of the resin in the exposed area increases, and the resin in the exposed area becomes soluble in the developer in the case of alkaline aqueous solution development, while becoming poorly soluble in the developer in the case of organic solvent development.

[0130] By including the radiation-sensitive acid generator (II), the radiation-sensitive resin composition can form a resist pattern that is more excellent in pattern developability, LWR, and CDU performance.

[0131] Examples of the radiation-sensitive acid generator include onium salt compounds, sulfonimide compounds, halogen-containing compounds, diazoketone compounds, etc. Examples of the onium salt compounds include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, etc. Among these, sulfonium salts and iodonium salts are preferred.

[0132] Examples of acids that are generated upon exposure include those that generate sulfonic acids, carboxylic acids, and sulfonimides upon exposure. (1) A compound in which one or more fluorine atoms or fluorinated hydrocarbon groups are substituted on the carbon atom adjacent to a sulfo group, (2) Compounds in which the carbon atom adjacent to the sulfo group is not substituted with a fluorine atom or a fluorinated hydrocarbon group Examples of the carboxylic acid generated upon exposure include: (3) Compounds in which one or more fluorine atoms or fluorinated hydrocarbon groups are substituted on the carbon atom adjacent to the carboxy group, (4) Compounds in which the carbon atom adjacent to the carboxyl group is not substituted with a fluorine atom or a fluorinated hydrocarbon group Among these, the radiation-sensitive acid generator (I) is preferably one corresponding to the above (1), and particularly preferably one having a cyclic structure. The radiation-sensitive acid generator (II) is preferably one corresponding to the above (2), (3), or (4), and particularly preferably one corresponding to (2) or (4).

[0133] These radiation-sensitive acid generators may be used alone or in combination of two or more. The lower limit of the content of the radiation-sensitive acid generator (I) is preferably 2 parts by mass, more preferably 5 parts by mass, and even more preferably 8 parts by mass, per 100 parts by mass of the resin, from the viewpoint of ensuring sensitivity and developability as a resist. The upper limit of the content of the radiation-sensitive acid generator (I) is preferably 30 parts by mass, more preferably 25 parts by mass, and even more preferably 20 parts by mass, per 100 parts by mass of the resin, from the viewpoint of ensuring transparency to radiation.

[0134] [solvent] The radiation-sensitive resin composition contains a solvent. The solvent is not particularly limited as long as it can dissolve or disperse at least the resin, the radiation-sensitive acid generator, and the acid diffusion controller, which may be included if desired.

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

[0136] Examples of alcohol-based solvents include: Monoalcohol solvents having 1 to 18 carbon atoms, such as iso-propanol, 4-methyl-2-pentanol, 3-methoxybutanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, and diacetone alcohol; polyhydric alcohol solvents having 2 to 18 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; Examples of suitable polyhydric alcohol solvents include partially etherified polyhydric alcohol solvents in which some of the hydroxy groups of the above polyhydric alcohol solvents have been etherified.

[0137] Examples of ether solvents include: dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether; cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; Aromatic ring-containing ether solvents such as diphenyl ether and anisole (methyl phenyl ether); Examples of the polyhydric alcohol solvent include polyhydric alcohol ether solvents obtained by etherifying the hydroxy groups of the above polyhydric alcohol solvents.

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

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

[0140] Examples of ester solvents include: Monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate; polyhydric alcohol partial ether acetate solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; Lactone solvents such as γ-butyrolactone and valerolactone; Carbonate solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; Examples of the solvent include polycarboxylic acid diester solvents such as propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, ethyl lactate, and diethyl phthalate.

[0141] Examples of hydrocarbon solvents include Aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; Examples of the solvent include aromatic hydrocarbon solvents such as benzene, toluene, di-isopropylbenzene, and n-amylnaphthalene.

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

[0143] [Other optional ingredients] The radiation-sensitive resin composition may contain other optional components in addition to the above components. Examples of the other optional components include an acid diffusion controller, a localization promoter, a surfactant, an alicyclic skeleton-containing compound, and a sensitizer. These other optional components may be used alone or in combination of two or more.

[0144] (acid diffusion control agent) The radiation-sensitive resin composition may contain an acid diffusion controller, if necessary. Among the above-mentioned radiation-sensitive acid generators, radiation-sensitive acid generator (II) can be suitably used as the acid diffusion controller. The acid diffusion controller controls the diffusion phenomenon in the resist film of the acid generated from the radiation-sensitive acid generator upon exposure, thereby suppressing undesirable chemical reactions in unexposed regions. The storage stability of the resulting radiation-sensitive resin composition is also improved. Furthermore, the resolution of the resist pattern is further improved, and changes in the line width of the resist pattern due to variations in the delay time from exposure to development can be suppressed, resulting in a radiation-sensitive resin composition with excellent process stability.

[0145] The lower limit of the content of the acid diffusion controller is preferably 1 part by mass, more preferably 2 parts by mass, and even more preferably 4 parts by mass, relative to 100 parts by mass of the total amount of the radiation-sensitive acid generators, and the upper limit of the content is preferably 20 parts by mass, more preferably 15 parts by mass, and even more preferably 10 parts by mass.

[0146] By setting the content of the acid diffusion controller within the above range, the lithography performance of the radiation-sensitive resin composition can be further improved. The radiation-sensitive resin composition may contain one or more types of acid diffusion controller.

[0147] (Uneven distribution promoter) The uneven distribution promoter has the effect of more efficiently unevenly distributing the high-fluorine-content resin on the resist film surface. By incorporating this uneven distribution promoter into the radiation-sensitive resin composition, the amount of the high-fluorine-content resin added can be reduced compared to conventional methods. Therefore, while maintaining the lithography performance of the radiation-sensitive resin composition, it is possible to further suppress elution of components from the resist film into the immersion medium and perform immersion exposure at higher speeds through high-speed scanning. As a result, it is possible to improve the hydrophobicity of the resist film surface, which suppresses immersion-related defects such as watermark defects. Examples of compounds that can be used as such uneven distribution promoters include low-molecular-weight compounds with a dielectric constant of 30 to 200 and a boiling point of 100°C or higher at 1 atmosphere. Specific examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, and polyhydric alcohols.

[0148] Examples of the lactone compound include γ-butyrolactone, valerolactone, mevalonic lactone, and norbornane lactone. Examples of the carbonate compound include propylene carbonate, ethylene carbonate, butylene carbonate, and vinylene carbonate. Examples of the nitrile compound include succinonitrile. The polyhydric alcohol includes, for example, glycerin.

[0149] The lower limit of the content of the uneven distribution 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, relative to 100 parts by mass of the total amount of resin in the radiation-sensitive resin composition. The upper limit of the 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 radiation-sensitive resin composition may contain one or more uneven distribution accelerators.

[0150] (surfactant) The surfactant has the effect of improving coating properties, striations, developability, etc. Examples of surfactants include nonionic surfactants such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, and polyethylene glycol distearate; commercially available products include KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, and Polyflow No. 95 (all manufactured by Kyoeisha Chemical), F-Top EF301, EF303, EF352 (all manufactured by Tochem Products), Megafac F171, F173 (all manufactured by DIC), Fluorad FC430, FC431 (all manufactured by Sumitomo 3M), Asahiguard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (all manufactured by Asahi Glass Co., Ltd.). The content of the surfactant in the radiation-sensitive resin composition is usually 2 parts by mass or less per 100 parts by mass of the resin.

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

[0152] Examples of the alicyclic skeleton-containing compound include Adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and t-butyl 1-adamantanecarboxylate; deoxycholate esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholate, and 2-ethoxyethyl deoxycholate; Lithocholate esters such as t-butyl lithocholate, t-butoxycarbonylmethyl lithocholate, and 2-ethoxyethyl lithocholate; Examples of such compounds include 3-[2-hydroxy-2,2-bis(trifluoromethyl)ethyl]tetracyclo[4.4.0.12,5.17,10]dodecane and 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo[4.2.1.03,7]nonane. The content of the alicyclic skeleton-containing compound in the radiation-sensitive resin composition is usually 5 parts by mass or less per 100 parts by mass of the resin.

[0153] (sensitizer) The sensitizer acts to increase the amount of acid generated from the radiation-sensitive acid generator or the like, and has the effect of improving the "apparent sensitivity" of the radiation-sensitive resin composition.

[0154] 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 radiation-sensitive resin composition is usually 2 parts by mass or less per 100 parts by mass of the resin.

[0155] <Method for preparing radiation-sensitive resin composition> The radiation-sensitive resin composition can be prepared, for example, by mixing a resin, a radiation-sensitive acid generator, and optionally an acid diffusion controller, a high-fluorine-content resin, and a solvent in a predetermined ratio. After mixing, the radiation-sensitive resin composition is preferably filtered, for example, through a filter having a pore size of about 0.05 μm to 0.2 μm. The solids 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.

[0156] <Method for forming a resist pattern> The resist pattern forming method according to this embodiment includes: a step of forming a resist film from the radiation-sensitive resin composition (hereinafter also referred to as a "resist film forming step"); a step of exposing the resist film to light (hereinafter also referred to as an "exposure step"); and The method includes a step of developing the exposed resist film (hereinafter also referred to as a "developing step").

[0157] Furthermore, the resist pattern forming method may include a step of providing an upper layer film on the resist film (hereinafter also referred to as an "upper layer film forming step") after the step of forming the resist film and before the step of exposing the resist film.

[0158] According to this method of forming a resist pattern, since the above-mentioned radiation-sensitive resin composition is used, it is possible to form a resist pattern that is excellent in sensitivity, LWR performance, and pattern rectangularity. Each step will be described below.

[0159] [Resist film formation process] In this step, a resist film is formed from the radiation-sensitive resin composition. Examples of substrates on which the resist film is formed include conventionally known substrates such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective coating, such as those disclosed in Japanese Patent Publication No. 6-12452 or Japanese Patent Application Laid-Open No. 59-93448, may be formed on the substrate. Examples of coating methods include spin coating, casting coating, and roll coating. After coating, pre-baking (PB) may be performed, if necessary, to volatilize the solvent in the coating film. The PB temperature is typically 60°C to 140°C, preferably 80°C to 120°C. The PB time is typically 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds. The thickness of the resist film formed is preferably 10 nm to 1,000 nm, more preferably 10 nm to 500 nm.

[0160] When performing immersion exposure, regardless of whether the radiation-sensitive resin composition contains a water-repellent polymer additive such as a high-fluorine-content resin, a protective film for immersion exposure that is insoluble in the immersion liquid may be provided on the formed resist film in order to prevent direct contact between the immersion liquid and the resist film. The protective film for immersion exposure may be either a solvent-removable protective film that is removed with a solvent before the development step (see, for example, JP-A No. 2006-227632), or a developer-removable protective film that is removed simultaneously with development in the development step (see, for example, WO2005-069076 and WO2006-035790). However, from the viewpoint of throughput, it is preferable to use a developer-removable protective film for immersion exposure.

[0161] When the next exposure step is carried out using radiation with a wavelength of 50 nm or less, it is preferable to use a resin having the structural units (B) and (E) as the base resin in the composition.

[0162] [Upper layer film formation process] In this process, an upper layer film is formed on the resist film using a composition for forming an upper layer film. Examples of the composition for forming an upper layer film include conventional compositions disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-352384. The composition for forming an upper layer film is applied to the resist film to form an upper layer film. Examples of methods for applying the composition for forming an upper layer film include methods similar to the method for applying the radiation-sensitive resin composition in the resist film formation process. In this process, it is preferable to perform pre-baking (PB) after applying the composition for forming an upper layer film. By forming an upper layer film on the resist film in this manner, direct contact between the immersion medium and the resist film is eliminated, effectively preventing degradation of the lithography performance of the resist film due to penetration of the liquid medium into the resist film and contamination of the lens of a projection exposure apparatus by components eluted from the resist film into the liquid medium.

[0163] It is preferable that the thickness of the upper layer film be as close as possible to an odd multiple of λ / 4m (where λ is the wavelength of the radiation and m is the refractive index of the upper layer film). This can increase the anti-reflection effect at the upper interface of the resist film.

[0164] [Exposure process] In this step, the resist film formed in the resist film-forming step is exposed to radiation through a photomask (or, in some cases, through an immersion medium such as water). Examples of radiation used for exposure include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet light), X-rays, and gamma rays; and charged particle beams such as electron beams and alpha rays, depending on the line width of the desired pattern. 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 ArF excimer laser light and EUV being even more preferred.

[0165] When exposure is performed by immersion exposure, examples of the immersion liquid used include water and fluorine-based inert liquids. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has as small a temperature coefficient of refractive index as possible so as to minimize distortion of the optical image projected onto the film. However, particularly when the exposure light source is an ArF excimer laser (wavelength 193 nm), water is preferred for its availability and ease of handling, in addition to the above considerations. When water is used, a small proportion of an additive that reduces the surface tension of water and increases its surfactant power 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.

[0166] After the exposure, post-exposure baking (PEB) is preferably performed to promote dissociation of acid-dissociable groups in the resin or the like in the exposed portions of the resist film by the acid generated from the radiation-sensitive acid generator upon exposure. This PEB results in a difference in solubility in a developer between the exposed and unexposed portions. The PEB temperature is usually 50°C to 180°C, preferably 80°C to 130°C. The PEB time is usually 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds.

[0167] [Development process] In this step, the resist film exposed in the exposure step is developed. This allows a desired resist pattern to be formed. After development, the resist film is generally washed with a rinse solution such as water or alcohol, and then dried. The overlying film can be easily removed by the developer during development, or by the cleaning solution during cleaning if cleaning is performed after development.

[0168] In the case of alkaline development, the developer used for the development may be, for example, 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, a TMAH aqueous solution is preferred, and a 2.38 mass % TMAH aqueous solution is more preferred.

[0169] In the case of organic solvent development, examples of the organic solvent include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, and alcohol solvents, as well as solvents containing an organic solvent. Examples of the organic solvent include one or more of the solvents listed above as the solvents for the radiation-sensitive resin composition. Among these, ester solvents and ketone solvents are preferred. As the ester solvent, acetate ester solvents are preferred, with n-butyl acetate and amyl acetate being more preferred. As the ketone solvent, chain ketones are preferred, with 2-heptanone being more preferred. The content of the organic solvent in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. Examples of components other than the organic solvent in the developer include water and silicone oil.

[0170] Examples of development methods include the dip method, in which the substrate is immersed in a tank filled with developer for a certain period of time; the puddle method, in which developer is piled up on the surface of the substrate by surface tension and left to stand for a certain period of time to develop; the spray method, in which developer is sprayed onto the surface of the substrate; and the dynamic dispense method, in which developer is continuously dispensed while scanning a developer dispense nozzle at a constant speed over a substrate that is rotating at a constant speed. [Example]

[0171] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Measurement methods for various physical properties are shown below.

[0172] [Weight average molecular weight (Mw) and number average molecular weight (Mn)] The Mw and Mn of the resin were measured under the above conditions, and the dispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[0173] [ 13 C-NMR analysis] Resin 13 C-NMR analysis was carried out using a nuclear magnetic resonance spectrometer (JNM-Delta400 manufactured by JEOL Ltd.).

[0174] [Fluorine content] The fluorine content in the resin was calculated from the theoretical fluorine elemental analysis value of the fluorine-containing monomer, and then calculated from the ratio of the monomer present in the entire resin.

[0175] <Synthesis of Monomer Compounds> [Synthesis Example 1] (Synthesis of Compound (M-1)) 20.0 mmol of ethyl 2-(bromomethyl)acrylate, 30.0 mmol of isopropyl alcohol, 40.0 mmol of diisopropylethylamine, and 50 g of dimethyl sulfoxide were added to a reaction vessel and stirred at 60°C for 12 hours. The reaction solution was then cooled to below 30°C, diluted with water, and extracted with ethyl acetate to separate the organic layer. The resulting organic layer was washed with saturated aqueous sodium chloride and then with water. After drying over sodium sulfate, the solvent was distilled off. The ether derivative was obtained in good yield by purification using column chromatography.

[0176] A mixture of methanol and water (1:1 (mass ratio)) was added to the above ether derivative to prepare a 1M solution, and then 20.0 mmol of sodium hydroxide was added and the reaction was carried out at room temperature for 1 hour. Thereafter, the reaction solution was cooled to below 30°C, and 1M hydrochloric acid was added to make the system acidic. Dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was washed with a saturated aqueous sodium chloride solution and then with water. After drying with sodium sulfate, the solvent was distilled off, and the carboxylic acid was obtained in good yield.

[0177] To the carboxylic acid product, 30.0 mmol of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 3.0 mmol of 4-dimethylaminopyridine, 30.0 mmol of α-hydroxy-γ-butyrolactone, and 50 g of dichloromethane were added and stirred at room temperature for 2 hours. The reaction solution was then cooled to below 30°C, diluted with water, and extracted with dichloromethane to separate the organic layer. The resulting organic layer was washed with saturated aqueous sodium chloride and then with water. After drying over sodium sulfate, the solvent was removed by distillation. Purification by column chromatography afforded a compound represented by the following formula (M-1) (hereinafter sometimes referred to as "compound (M-1)" or "monomer (M-1)") in good yield. The synthesis scheme for compound (M-1) is shown below.

[0178] [ka]

[0179] [Synthesis Examples 2 to 18] (Synthesis of Monomers (M-2) to (M-18)) Except for appropriately changing the raw materials and precursors, compounds represented by the following formulas (M-2) to (M-18) were synthesized in the same manner as in Synthesis Example 1. Hereinafter, the compounds represented by formulas (M-2) to (M-18) may be referred to as "compound (M-2)" to "compound (M-18)" or "monomer (M-2)" to "monomer (M-18)", respectively.

[0180] [ka]

[0181] <Synthesis of [A] Resin and [E] High-Fluorine Content Resin> Among the monomers used in the synthesis of each resin, those other than the above-mentioned monomers (M-1) to (M-18) are shown below. In the following synthesis examples, unless otherwise specified, parts by mass refer to a value where the total mass of the monomers used is taken as 100 parts by mass, and mol % refers to a value where the total number of moles of the monomers used is taken as 100 mol %.

[0182] [ka]

[0183] [Synthesis Example 19] (Synthesis of Resin (A-1)) Monomer (M-1) and monomer (m-1) were dissolved in 2-butanone (200 parts by mass) at a molar ratio of 50 / 50 (mol %), and AIBN (azobisisobutyronitrile) (5 mol % relative to the total of 100 mol % of the monomers used) was added as an initiator to prepare a monomer solution. 2-butanone (100 parts by mass) was placed in an empty reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C and the monomer solution was added dropwise over 3 hours with stirring. The polymerization reaction was initiated at the start of the dropwise addition and continued for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to below 30°C with water. The cooled polymerization solution was poured into methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The white powder was washed twice with methanol, filtered off, and dried at 50°C for 10 hours to obtain white powdery resin (A-1) (yield: 80%). The Mw of resin (A-1) was 6,100, and the Mw / Mn was 1.61. 13 As a result of C-NMR analysis, the content ratios of the structural units derived from the monomer (M-1) and the monomer (m-1) were 49.0 mol % and 51.0 mol %, respectively, and the fluorine content was 0.0%.

[0184] [Synthesis Examples 20 to 50] (Synthesis of Resin (A-2) to Resin (A-32)) Resins (A-2) to (A-32) were synthesized in the same manner as in Synthesis Example 19, except that the types and blending ratios of monomers shown in Tables 1 and 2 below were used. The content (mol %) of each structural unit and physical properties (Mw, Mw / Mn, and fluorine content) of the resulting resins are also shown in Tables 1 and 2 below. In Tables 1 and 2 below, "-" indicates that the corresponding monomer was not used.

[0185] [Table 1]

[0186] [Table 2]

[0187] [Synthesis Example 51] (Synthesis of Resin (A-33)) Monomer (M-3), monomer (m-1), and monomer (m-18) were dissolved in 1-methoxy-2-propanol (200 parts by mass) to a molar ratio of 20 / 40 / 40 (mol%), and AIBN (5 mol%) was added as an initiator to prepare a monomer solution. 1-Methoxy-2-propanol (100 parts by mass) was placed in a reaction vessel, and 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 with stirring. The start of the dropwise addition marked the start of the polymerization reaction, which was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to below 30°C with water. The cooled polymerization solution was poured into hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane, filtered off, and dissolved in 1-methoxy-2-propanol (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and a hydrolysis reaction was carried out at 70°C for 6 hours while stirring. After the reaction was completed, the remaining solvent was distilled off. The obtained solid was dissolved in acetone (100 parts by mass) and added dropwise to water (500 parts by mass) to coagulate the resin. The obtained solid was filtered and dried at 50°C for 13 hours to obtain a white powdery polymer (A-33) (yield: 73%). The Mw of the resin (A-33) was 6,100, and the Mw / Mn was 1.60. 13 As a result of C-NMR analysis, the contents of the structural units derived from (M-3), (m-1) and (m-18) were 19.4 mol%, 40.7 mol% and 39.9 mol%, respectively, and the fluorine content was 0.0%.

[0188] [Synthesis Examples 52 to 57] (Synthesis of Polymers (A-34) to (A-39)) Resins (A-34) to (A-39) were synthesized in the same manner as in Synthesis Example 51, except that the types and blending ratios of monomers shown in Tables 3 and 4 were used. The content (mol %) of each structural unit and physical properties (Mw, Mw / Mn, and fluorine content) of the resulting resins are also shown in Tables 3 and 4.

[0189] [Table 3]

[0190] [Table 4]

[0191] Synthesis Example 58 (Synthesis of High Fluorine Content Resin (E-1)) Monomer (m-1) and monomer (m-20) were dissolved in 2-butanone (200 parts by mass) at a molar ratio of 10 / 90 (mol%), and AIBN (5 mol%) was added as an initiator to prepare a monomer solution. 2-butanone (100 parts by mass) 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 with stirring. The polymerization reaction was initiated at the start of the dropwise addition and continued for 6 hours. After completion of the polymerization reaction, the polymerized solution was cooled to below 30°C with water. The solvent was replaced with acetonitrile (400 parts by mass), and then hexane (100 parts by mass) was added, stirred, and the acetonitrile layer was collected. This process was repeated three times. The solvent was replaced with propylene glycol monomethyl ether acetate to obtain a solution of high-fluorine content resin (E-1) (yield: 81%). The high fluorine content resin (E-1) had an Mw of 6,300 and an Mw / Mn ratio of 1.67. 13 As a result of C-NMR analysis, the content ratios of the structural units derived from (m-1) and (m-20) were 10.8 mol % and 89.2 mol %, respectively, and the fluorine content was 14.5%.

[0192] [Synthesis Examples 59 to 61] (Synthesis of High Fluorine Content Resin (E-2) to High Fluorine Content Resin (E-4)) High fluorine content resins (E-2) to (E-4) were synthesized in the same manner as in Synthesis Example 58, except for using monomers of the types and blending ratios shown in Table 5. The content (mol %) of each structural unit and physical properties (Mw, Mw / Mn, and fluorine content) of the obtained high fluorine content resins are also shown in Table 5.

[0193] [Table 5]

[0194] <Preparation of Radiation-Sensitive Resin Composition> The components other than the resin [A] and the high-fluorine-content resin [E] used in preparing each radiation-sensitive resin composition are shown below.

[0195] [[B] Radiation-sensitive acid generator] B-1 to B-6: Compounds represented by the following formulas (B-1) to (B-6)

[0196] [ka]

[0197] [[C] Acid diffusion control agent] C-1 to C-5: Compounds represented by the following formulae (C-1) to (C-5)

[0198] [ka]

[0199] [[D] Solvent] D-1: Propylene glycol monomethyl ether acetate D-2: Cyclohexanone D-3: γ-butyrolactone D-4: Ethyl lactate

[0200] [Preparation of Positive Radiation-Sensitive Resin Composition for ArF Exposure] [Example 1] A radiation-sensitive resin composition (J-1) was prepared by mixing 100 parts by mass of (A-1) as the resin [A], 14.0 parts by mass of (B-4) as the radiation-sensitive acid generator [B], 8.0 parts by mass of (C-1) and (C-2) as the acid diffusion controller [C], 5.0 parts by mass (solids content) of (E-1) as the high-fluorine-content resin [E], and 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) as the solvent [D], and filtering the mixture through a membrane filter having a pore size of 0.2 μm.

[0201] [Examples 2 to 38 and Comparative Examples 1 to 12] Except for using the components of the types and contents shown in Table 6 below, radiation-sensitive resin compositions (J-2) to (J-38) and (CJ-1) to (CJ-12) were prepared in the same manner as in Example 1.

[0202]

Table 6

[0203] <Formation of a resist pattern using a positive-type ArF-exposure radiation-sensitive resin composition> On a 12-inch silicon wafer, using a spin coater ("CLEAN TRACK ACT12" manufactured by Tokyo Electron Limited), a composition for forming an underlayer antireflection film ("ARC66" manufactured by Brewer Science, Inc.) was applied, and then heated at 205°C for 60 seconds to form an underlayer antireflection film with an average thickness of 105 nm. On this underlayer antireflection film, the positive-type ArF-exposure radiation-sensitive resin composition prepared above was applied using the spin coater, and PB (pre-bake) was performed at 90°C for 60 seconds. Then, by cooling at 23°C for 30 seconds, a resist film with an average thickness of ninety nm was formed. Next, with respect to this resist film, using an ArF excimer laser immersion exposure apparatus ("TWINSCAN XT-1900i" manufactured by ASML), under the optical conditions of NA = 1.35 and Annular (σ = 0.8 / 0.6), exposure was performed through a mask pattern of 40 nm space and 105 nm pitch. After exposure, PEB (post-exposure bake) was performed at 90°C for 60 seconds. Then, the resist film was alkali-developed using a 2.38 mass% aqueous TMAH solution as an alkali developer, washed with water after development, and further dried to form a positive-type resist pattern (40 nm line and space pattern). Also, except for changing the mask pattern, a positive-type resist pattern (40 nm hole, 105 nm pitch) was formed in the same manner as the above operation.

[0204] <Evaluation> The resist patterns formed using the positive radiation-sensitive resin composition for ArF exposure were evaluated for sensitivity, LWR performance, and pattern rectangularity according to the following methods. The results are shown in Table 7. The resist patterns were measured using a scanning electron microscope (CG-5000 manufactured by Hitachi High-Technologies Corporation).

[0205] [sensitivity] In forming a resist pattern using the positive radiation-sensitive resin composition for ArF exposure, the exposure dose for forming a 40 nm line and space pattern was defined as the optimum exposure dose, and this optimum exposure dose was determined as the sensitivity (mJ / cm 2 The sensitivity was 20 mJ / cm 2 The following are considered "good" and 20mJ / cm 2 If it exceeded this, it was rated as "poor".

[0206] [LWR performance] A resist pattern was formed by adjusting the mask size so that a 40 nm line-and-space pattern was formed by irradiating the optimal exposure dose determined in the sensitivity evaluation above. The formed resist pattern was observed from above the pattern using the above-mentioned scanning electron microscope. A total of 500 points of line width variation were measured, and a 3 sigma value was calculated from the distribution of the measured values. This 3 sigma value was taken as the LWR (nm). The smaller the LWR value, the smaller the line roughness and the better the result. LWR performance was evaluated as "good" when it was 2.5 nm or less, and "poor" when it was more than 2.5 nm.

[0207] Pattern Rectangularity A 40 nm line and space pattern formed by irradiating with the optimum exposure dose obtained in the sensitivity evaluation was observed using the scanning electron microscope, and the cross-sectional shape of the line and space pattern was evaluated. The rectangularity of the resist pattern was evaluated as "Good" if the ratio of the bottom side length to the top side length in the cross-sectional shape was 1 or more and 1.05 or less, "Fair" if it was more than 1.05 and 1.10 or less, and "Poor" if it was more than 1.10.

[0208] [Table 7]

[0209] As is clear from the results in Table 7, the radiation-sensitive resin composition of the example had good sensitivity, LWR performance, and pattern rectangularity when used for ArF exposure, whereas in the comparative examples, each characteristic was inferior to that of the example. Therefore, when the radiation-sensitive resin composition of the example was used for ArF exposure, a resist pattern with high sensitivity, good LWR performance, and good pattern rectangularity could be formed.

[0210] [Preparation of Positive-Type Radiation-Sensitive Resin Composition for Extreme Ultraviolet (EUV) Exposure] [Example 39] [A] 100 parts by mass of (A-33) as a resin, [B] 12.0 parts by mass of (B-4) as a radiation-sensitive acid generator, [C] 6.0 parts by mass of (C-1) as an acid diffusion controller, [E] 5.0 parts by mass of (E-4) as a high fluorine content resin, and 6,110 parts by mass of a mixed solvent of (D-1) / (D-4) as [D] a solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-39). [[ID=X]]

[0211] [Examples 40 to 50 and Comparative Examples 13 to 15] Except for using the components of the types and contents shown in Table 8 below, radiation-sensitive resin compositions (J-40) to (J-50) and (CJ-13) to (CJ-15) were prepared in the same manner as in Example 39.

[0212]

Table 8

[0213] [Formation of Resist Pattern Using Positive-Type Radiation-Sensitive Resin Composition for EUV Exposure] A 12-inch silicon wafer was coated with a composition for forming a bottom anti-reflective coating (Brewer Science's ARC66) using a spin coater (Tokyo Electron Limited's CLEAN TRACK ACT12), followed by heating at 205°C for 60 seconds to form a bottom anti-reflective coating with an average thickness of 105 nm. The positive radiation-sensitive resin composition for EUV exposure prepared above was coated onto this bottom anti-reflective coating using the spin coater, followed by post-baking at 130°C for 60 seconds. This was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 55 nm. This resist film was then exposed to light using an EUV exposure system (ASML's NXE3300) with NA=0.33, illumination conditions: Conventional s=0.89, and a mask: imecDEFECT32FFR02. After exposure, post-baking was performed at 120°C for 60 seconds. Thereafter, the resist film was subjected to alkaline development using a 2.38% by mass aqueous solution of TMAH as an alkaline developer, and after development, the resist film was washed with water and then dried to form a positive resist pattern (32 nm line and space pattern).

[0214] <Evaluation> The resist patterns formed using the above-mentioned positive radiation-sensitive resin composition for EUV exposure were evaluated for sensitivity, LWR performance, and pattern rectangularity according to the following methods. The results are shown in Table 9. The resist patterns were measured using a scanning electron microscope ("CG-5000" manufactured by Hitachi High-Technologies Corporation).

[0215] [sensitivity] In forming a resist pattern using the positive-tone radiation-sensitive resin composition for EUV exposure, the exposure dose for forming a 32 nm line and space pattern was defined as the optimum exposure dose, and this optimum exposure dose was determined as the sensitivity (mJ / cm 2 The sensitivity was 25 mJ / cm 2 The following are considered "good" and 25mJ / cm 2 If it exceeded this, it was rated as "poor".

[0216] [LWR performance] A resist pattern was formed by irradiating the resist with the optimal exposure dose determined in the sensitivity evaluation above, and adjusting the mask size to form a 32 nm line-and-space pattern. The formed resist pattern was observed from above using the scanning electron microscope described above. The line width variation was measured at a total of 500 points, and a 3 sigma value was calculated from the distribution of the measured values. This 3 sigma value was taken as the LWR (nm). The smaller the LWR value, the smaller the line wobble and the better the result. LWR performance was evaluated as "good" when it was 3.0 nm or less, and "poor" when it exceeded 3.0 nm.

[0217] Pattern Rectangularity The 32 nm line and space pattern formed by irradiating with the optimum exposure dose determined in the sensitivity evaluation was observed using the scanning electron microscope, and the cross-sectional shape of the line and space pattern was evaluated. The rectangularity of the resist pattern was evaluated as "Good" if the ratio of the bottom side length to the top side length in the cross-sectional shape was 1 or more and 1.05 or less, "Fair" if it was more than 1.05 and 1.10 or less, and "Poor" if it was more than 1.10.

[0218] [Table 9]

[0219] As is clear from the results in Table 9, the radiation-sensitive resin compositions of the Examples exhibited good sensitivity, LWR performance, and pattern rectangularity when used for EUV exposure, whereas the Comparative Examples were inferior to the Examples in each of the properties.

[0220] [Preparation of a negative-tone radiation-sensitive resin composition for ArF exposure, and formation and evaluation of a resist pattern using this composition] [Example 51] A radiation-sensitive resin composition (J-51) was prepared by mixing 100 parts by mass of (A-3) as the resin [A], 15.0 parts by mass of (B-3) as the radiation-sensitive acid generator [B], 8.0 parts by mass of (C-2) as the acid diffusion controller [C], 2.0 parts by mass (solids content) of (E) as the high-fluorine-content resin [E-3], and 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) as the solvent [D], and filtering the mixture through a membrane filter having a pore size of 0.2 μm.

[0221] A 12-inch silicon wafer was coated with a composition for forming a bottom anti-reflective coating (Brewer Science's ARC66) using a spin coater (Tokyo Electron Limited's CLEAN TRACK ACT12), followed by heating at 205°C for 60 seconds to form a bottom anti-reflective coating with an average thickness of 105 nm. The negative radiation-sensitive resin composition for ArF exposure (J-51) prepared above was then coated onto the bottom anti-reflective coating using the spin coater, followed by pre-baking at 90°C for 60 seconds. This was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 90 nm. This resist film was then exposed to light using an ArF excimer laser immersion exposure system (ASML's TWINSCAN XT-1900i) under optical conditions of NA = 1.35 and annular (σ = 0.8 / 0.6) through a 40 nm space, 105 nm pitch mask pattern. After the exposure, PEB (post-exposure bake) was performed for 60 seconds at 90° C. Then, the resist film was developed using n-butyl acetate as an organic solvent developer and dried to form a negative resist pattern (40 nm line and space pattern).

[0222] The resist pattern formed using the negative-tone radiation-sensitive resin composition for ArF exposure was evaluated in the same manner as the resist pattern formed using the positive-tone radiation-sensitive resin composition for ArF exposure. As a result, the radiation-sensitive resin composition of Example 51 exhibited good sensitivity, LWR performance, and pattern rectangularity, even when a negative-tone resist pattern was formed by ArF exposure.

[0223] [Preparation of a negative-tone radiation-sensitive resin composition for EUV exposure, and formation and evaluation of a resist pattern using this composition] [Example 52] A radiation-sensitive resin composition (J-52) was prepared by mixing 100 parts by mass of (A-33) as the resin [A], 20.0 parts by mass of (B-4) as the radiation-sensitive acid generator [B], 12.0 parts by mass of (C-1) as the acid diffusion controller [C], 2.0 parts by mass of (E-4) as the high fluorine-content resin [E], and 6,110 parts by mass of a mixed solvent [D] with a (D-1) / (D-4)=70 / 30 (mass ratio) as the solvent, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0224] A 12-inch silicon wafer was coated with a composition for forming a bottom anti-reflective coating (Brewer Science's ARC66) using a spin coater (Tokyo Electron Limited's CLEAN TRACK ACT12), followed by heating at 205°C for 60 seconds to form a bottom anti-reflective coating with an average thickness of 105 nm. The radiation-sensitive resin composition for EUV exposure prepared above was then coated onto this bottom anti-reflective coating using the spin coater, followed by post-baking at 130°C for 60 seconds. This was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 55 nm. This resist film was then exposed to light using an EUV exposure system (ASML's NXE3300) with NA=0.33, illumination conditions: Conventional s=0.89, and a mask: imecDEFECT32FFR02. After exposure, post-baking was performed at 120°C for 60 seconds. Thereafter, the resist film was developed with n-butyl acetate as an organic solvent developer and dried to form a negative resist pattern (32 nm line and space pattern).

[0225] The resist pattern formed using the negative-tone radiation-sensitive resin composition for EUV exposure was evaluated in the same manner as the resist pattern formed using the positive-tone radiation-sensitive resin composition for EUV exposure. As a result, the radiation-sensitive resin composition of Example 52 exhibited good sensitivity, LWR performance, and pattern rectangularity, even when a negative-tone resist pattern was formed by EUV exposure. [Industrial Applicability]

[0226] The radiation-sensitive resin composition and the method for forming a resist pattern of the present invention can form a resist pattern that has good sensitivity to exposure and excellent LWR performance and pattern rectangularity, and therefore can be suitably used in the processing of semiconductor devices, which are expected to become increasingly miniaturized in the future.

Claims

1. A compound represented by the following formula (1'): 【Chemistry 1】 (In the above formula (1'), R １ is a halogen atom-substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. X is —O— or —S—. L ａ１ is a halogen atom-substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms. R Ｐ is a monovalent organic group having at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. Ｐ is a monovalent organic group having a lactone structure, R １ is a monovalent hydrocarbon group having 3 to 20 carbon atoms.

2. R in the above formula (1′) １ 2. The radiation-sensitive resin composition according to claim 1, wherein is a hydrocarbon group having 3 to 20 carbon atoms.

3. L in the above formula (1′) ａ１ 3. The radiation-sensitive resin composition according to claim 1, wherein is a methylene group, and X is —O—.

4. A resin containing a structural unit (A) represented by the following formula (1): 【Chemistry 2】 (In the above formula (1), R １ is a halogen atom-substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. X is —O— or —S—. L ａ１ is a halogen atom-substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms. R Ｐ is a monovalent organic group having at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. Ｐ is a monovalent organic group having a lactone structure, R １ is a monovalent hydrocarbon group having 3 to 20 carbon atoms.

5. The resin according to claim 4, further comprising a structural unit (B) having an acid-dissociable group.

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