Radiation-sensitive composition, pattern-forming method, and compound

Abstract

The purpose of the present invention is to provide: a radiation-sensitive composition from which it is possible to obtain a resist film that can exhibit, at sufficient levels, sensitivity, CDU, pattern circularity, pattern rectangularity, exposure latitude, and depth of focus; a pattern-forming method; and a compound. This radiation-sensitive composition includes: a polymer (A) including a structure unit (I) having a phenolic hydroxyl group; a compound (C) represented by formula (1); a crosslinking agent (Q); and a solvent (E). (In said formula (1), R1 represents a monovalent organic group having 1-40 carbon atoms (excluding a group including an aromatic hydrocarbon). R21 and R22 each independently represent a monovalent organic group having 1-40 carbon atoms. R23 and R24 each independently represent a monovalent organic group having 1-40 carbon atoms, or R23 and R24 are combined with each other to form, together with a nitrogen atom which is bonded thereto, a cyclic structure having 3-10 ring members.)

Description

Radiation-sensitive composition, pattern forming method, and compound

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

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

[0003] In the photolithography technology, g-line, i-line, and KrF excimer laser have been developed, and more recently, ArF excimer laser, EUV (extreme ultraviolet), and electron beam have been used to finely pattern, but depending on the application, patterning may be performed with a resist film thickness on the order of several μm and a pattern size on the order of several hundred nm. Among these, a technology has been proposed that uses a negative resist pattern containing a crosslinking agent with a specific structure (Patent No. 5927095).

[0004] Patent No. 5927095

[0005] When the resist film is thick, light does not sufficiently penetrate to the bottom of the resist film, which may cause problems in sensitivity, pattern formability, etc. Furthermore, when the resist film is thick, the film surface becomes a highly exposed region, and the concentration of acid generated from the radiation-sensitive acid generator becomes high on the resist film surface, resulting in non-uniformity of the acid concentration in the thickness direction, which may cause problems in sensitivity and pattern formability. Therefore, there is a demand for a radiation-sensitive composition that can form a pattern having sufficient resist properties such as CDU (Critical Dimension Uniformity), which is an index of sensitivity and uniformity of line width and hole diameter, pattern rectangularity, pattern circularity, exposure margin, and depth of focus, even when the resist film is thick.

[0006] An object of the present invention is to provide a radiation-sensitive composition, a pattern forming method, and a compound capable of forming a resist film that exhibits sufficient levels of sensitivity, CDU, pattern circularity, pattern rectangularity, exposure latitude, and depth of focus.

[0007] As a result of extensive research into solving the above problem, the present inventors have found that the above object can be achieved by employing the following configuration, and have thus completed the present invention.

[0008] That is, in one embodiment, the present invention relates to a radiation-sensitive composition comprising: a polymer (A) including a structural unit (I) having a phenolic hydroxyl group; a compound (C) represented by the following formula (1); a crosslinking agent (Q); and a solvent (E): (In formula (1), R １ is a monovalent organic group having 1 to 40 carbon atoms (excluding groups containing aromatic hydrocarbons). ２１ and R ２２ are each independently a monovalent organic group having 1 to 40 carbon atoms. ２３ and R ２４ are each independently a monovalent organic group having 1 to 40 carbon atoms, or R ２３ and R ２４ are bonded together with the nitrogen atom to which they are attached, forming a ring structure having 3 to 10 ring members.

[0009] The radiation-sensitive composition contains the compound (C) represented by formula (1), and thus can form a resist film that exhibits sufficient levels of sensitivity, CDU, pattern circularity, pattern rectangularity, exposure latitude, and depth of focus. Without being bound by any theory, the reason for this is presumed to be as follows.

[0010] When the resist film is thick, the film surface becomes a highly exposed region, and the concentration of the acid generated from the radiation-sensitive acid generator tends to be high on the resist film surface.As a result, the acid concentration varies in the thickness direction of the film, which may cause problems in sensitivity and pattern formability.Since the compound (C) contained in this composition has a highly hydrophobic cation, the compound (C) tends to be unevenly distributed on the resist film surface, and as a result, it is presumed that the compound (C) effectively captures the acid on the resist film surface and forms a pattern with a good cross-sectional shape.In addition, since the anion of the compound (C) does not contain an aromatic hydrocarbon, the light transmittance of the resist film is improved, and even when the resist film is thick, light can be sufficiently transmitted.As a result, it is presumed that the sensitivity, CDU, pattern circularity, pattern rectangularity, exposure margin, and depth of focus can be exhibited at sufficient levels.

[0011] In another embodiment, the present invention relates to a pattern forming method, comprising: a step of applying the radiation-sensitive composition directly or indirectly to a substrate to form a resist film; a step of exposing the resist film; and a step of developing the exposed resist film.

[0012] The pattern formation method uses the radiation-sensitive composition capable of forming a resist film that is excellent in sensitivity, CDU, pattern circularity, pattern rectangularity, exposure latitude, and depth of focus, and therefore can efficiently form a high-quality resist pattern.

[0013] In another embodiment, the present invention relates to a compound represented by the following formula (1-1): (In formula (1-1), R ２１１ is a monovalent chain organic group having 6 to 8 carbon atoms. ２２１ , R ２３１ and R ２４１ are each independently a monovalent chain hydrocarbon group having 2 to 8 carbon atoms. - is an anion represented by the following formula (1-1-a), (1-1-b), (1-1-c), or (1-1-d). (In formulas (1-1-a), (1-1-b), (1-1-c), and (1-1-d), W ａis a substituted or unsubstituted alicyclic hydrocarbon group having 3 to 20 carbon atoms. ｂ is an organic group having 3 to 20 carbon atoms. ｃ and W ｄ are each independently an organic group having 1 to 20 carbon atoms. ａ , W ｂ , W ｃ and W ｄ does not contain aromatic hydrocarbon groups.

[0014] A radiation-sensitive composition containing the compound can form a resist film that exhibits sufficient levels of sensitivity, CDU, pattern circularity, pattern rectangularity, exposure latitude, and depth of focus.

[0015] In this specification, the term "organic group" refers to a group containing at least one carbon atom. However, organic groups such as cyano, carboxy, formyl, and carbonyl groups, which are functional or characteristic groups by themselves, are excluded. In this specification, the term "hydrocarbon group" refers to a group consisting of only carbon atoms and hydrogen atoms, such as a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group, while the term "substituted hydrocarbon group" refers to a hydrocarbon group in which one or more hydrogen atoms have been substituted with a heteroatom-containing group.

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

[0017] <Radiation-Sensitive Composition> The radiation-sensitive composition according to this embodiment (hereinafter also simply referred to as "composition") contains the compound (C) represented by the above formula (1), the polymer (A) containing the structural unit (I) having a phenolic hydroxyl group, the crosslinking agent (Q), and the solvent (E). The composition may contain other optional components as long as the effects of the present invention are not impaired.

[0018] Compound (C) represented by the following formula (1) functions as an acid diffusion controller, controlling 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 the unexposed regions. 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 composition with excellent process stability. (In formula (1), R １ is a monovalent organic group having 1 to 40 carbon atoms (excluding groups containing aromatic hydrocarbons). ２１ and R ２２ are each independently a monovalent organic group having 1 to 40 carbon atoms. ２３ and R ２４ are each independently a monovalent organic group having 1 to 40 carbon atoms, or R ２３ and R ２４ are bonded together with the nitrogen atom to which they are attached, forming a ring structure having 3 to 10 ring members.

[0019] The above R １ The monovalent organic group having 1 to 40 carbon atoms and represented by the formula (I) excludes groups containing aromatic hydrocarbons, and examples thereof include monovalent hydrocarbon groups having 1 to 40 carbon atoms (excluding aromatic hydrocarbon groups), groups having a divalent heteroatom-containing group between carbon atoms of the hydrocarbon group or at the carbon chain terminal, groups in which some or all of the hydrogen atoms of the hydrocarbon group have been substituted with monovalent heteroatom-containing groups, and combinations thereof. １ However, by not containing aromatic hydrocarbons, the transmittance of the resist film is improved, and as a result, it is possible to form a resist film that is excellent in sensitivity, CDU, pattern circularity, pattern rectangularity, exposure latitude, and depth of focus.

[0020] The above R １ Examples of the monovalent hydrocarbon group having 1 to 40 carbon atoms in the formula include a monovalent chain hydrocarbon group having 1 to 40 carbon atoms and a monovalent alicyclic hydrocarbon group having 3 to 40 carbon atoms.

[0021] The above R １Examples of the monovalent linear hydrocarbon group having 1 to 40 carbon atoms represented by the formula (I) include a monovalent linear or branched saturated hydrocarbon group having 1 to 40 carbon atoms, or a monovalent linear or branched unsaturated hydrocarbon group having 2 to 40 carbon atoms. Examples of the monovalent linear or branched saturated hydrocarbon group having 1 to 40 carbon atoms include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a 2-methylpropyl group, a 1-methylpropyl group, a t-butyl group, an n-pentyl group, an isopentyl group, and a neopentyl group. Examples of the monovalent linear or branched unsaturated hydrocarbon group having 2 to 40 carbon atoms include alkenyl groups such as an ethenyl group, a propenyl group, and a butenyl group; and alkynyl groups such as an ethynyl group, a propynyl group, and a butynyl group.

[0022] The above R １ Examples of the monovalent alicyclic hydrocarbon group having 3 to 40 carbon atoms represented by the formula (I) include monocyclic or polycyclic saturated hydrocarbon groups, and monocyclic or polycyclic unsaturated hydrocarbon groups. Examples of the monocyclic saturated hydrocarbon group include cycloalkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Examples of the polycyclic saturated hydrocarbon group include bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl. Examples of the monocyclic unsaturated hydrocarbon group include monocyclic cycloalkenyl groups such as cyclopropenyl, cyclobutenyl, cyclopentenyl, and cyclohexenyl. Examples of the polycyclic unsaturated hydrocarbon group include polycyclic cycloalkenyl groups such as norbornenyl, tricyclodecenyl, and tetracyclododecenyl. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two carbon atoms that are not adjacent to each other among the carbon atoms that constitute the alicyclic ring are linked by a linking group containing one or more carbon atoms.

[0023] Examples of heteroatoms constituting the monovalent heteroatom-containing group and divalent heteroatom-containing group include oxygen atoms, nitrogen atoms, sulfur atoms, phosphorus atoms, silicon atoms, and halogen atoms. Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0024] Examples of the monovalent heteroatom-containing group include a hydroxy group, a carboxy group, a sulfanyl group, a cyano group, a nitro group, and a halogen atom. Of these, a halogen atom, a hydroxy group, and a carboxy group are preferred.

[0025] Examples of the divalent heteroatom-containing group include -CO-, -C(=O)O-, -CS-, -NH-, -O-, -S-, -SO-, and -SO ２ Among these, —CO— and —C(═O)O— are preferred.

[0026] As the anion of the above formula (1), from the viewpoints of sensitivity, CDU, exposure margin, and depth of focus, R １ is preferably a monovalent organic group having 4 to 20 carbon atoms, and R １ has an alicyclic structure, and is further preferably a structure represented by the following formula (a1).

[0027] (In formula (a1), R ｆ１１ and R ｆ１２ are each independently a hydrogen atom, a fluorine atom, or a monovalent fluorinated hydrocarbon group. ｆ１１ and R ｆ１２ If there are multiple R ｆ１１ and R ｆ１２ are the same or different. s1 is an integer of 0 to 5. L １ represents a single bond or a divalent linking group; s2 is 0 or 1; and W represents a substituted or unsubstituted alicyclic hydrocarbon group.

[0028] The above R ｆ１１ and R ｆ１２ The monovalent fluorinated hydrocarbon group represented by the formula (1) described below includes R ２１ and R ２２ and groups in which some or all of the hydrogen atoms of the monovalent hydrocarbon group having 1 to 40 carbon atoms have been substituted with fluorine atoms.

[0029] Examples of the divalent linking group include -CO-, -COO-, -OCO-, -O-, a divalent linear or branched hydrocarbon group having 1 to 10 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, and a group composed of one or more of these hydrocarbon groups and at least one group selected from -CO-, -O-, -NH-, and -S-.

[0030] The alicyclic hydrocarbon group in W is the same as R １ One or more hydrogen atoms on the alicyclic hydrocarbon group may be substituted with a substituent.

[0031] Examples of the substituent include substituents (T) such as halogen atoms such as fluorine atom, chlorine atom, bromine atom, and iodine atom; hydroxy group; carboxy group; cyano group; nitro group; alkyl group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, acyloxy group, or groups in which the hydrogen atom of these groups is substituted with a halogen atom; and oxo group (═O).

[0032] The anion of the above formula (1) may be an anion represented by the following formula (1-1-a), (1-1-b), (1-1-c), or (1-1-d). (In formulas (1-1-a), (1-1-b), (1-1-c), and (1-1-d), W ａ is a substituted or unsubstituted alicyclic hydrocarbon group having 3 to 20 carbon atoms. ｂ is an organic group having 3 to 20 carbon atoms. ｃ and W ｄ are each independently an organic group having 1 to 20 carbon atoms. ａ , W ｂ , W ｃ and W ｄ does not contain an aromatic hydrocarbon group.)

[0033] The above W ａ The alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above R １Among the monovalent alicyclic hydrocarbon groups having 3 to 40 carbon atoms in the above, those having the corresponding number of carbon atoms can be suitably used. One or more hydrogen atoms on this alicyclic hydrocarbon group may be substituted with a substituent. As the substituent, the above-mentioned substituent (T) can be suitably used.

[0034] The above W ｂ The organic group having 3 to 20 carbon atoms represented by the above R １ Among the monovalent organic groups having 1 to 40 carbon atoms represented by the following formula, those having the corresponding number of carbon atoms can be suitably used.

[0035] The above W ｃ and W ｄ The organic group having 1 to 20 carbon atoms represented by the above R １ Among the monovalent organic groups having 1 to 40 carbon atoms represented by the following formula, those having the corresponding number of carbon atoms can be suitably used.

[0036] Specific examples of the anion of compound (C) include, but are not limited to, structures of the following formulae:

[0037]

[0038]

[0039]

[0040]

[0041] The above R ２１ and R ２２ Examples of the monovalent organic group having 1 to 40 carbon atoms represented by the formula (I) include a monovalent hydrocarbon group having 1 to 40 carbon atoms, a group having a divalent heteroatom-containing group between carbon atoms of the hydrocarbon group or at the carbon chain terminal, a group in which some or all of the hydrogen atoms of the hydrocarbon group have been substituted with a monovalent heteroatom-containing group, and a combination thereof.

[0042] The above R ２１ and R ２２ Examples of the monovalent hydrocarbon group having 1 to 40 carbon atoms represented by the formula (I) include a monovalent chain hydrocarbon group having 1 to 40 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 40 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 40 carbon atoms.

[0043] The above R ２１ and R ２２ The monovalent chain hydrocarbon group having 1 to 40 carbon atoms and the monovalent alicyclic hydrocarbon group having 3 to 40 carbon atoms represented by the above R １ In the above formula, a monovalent chain hydrocarbon group having 1 to 40 carbon atoms and a monovalent alicyclic hydrocarbon group having 3 to 40 carbon atoms can be suitably used.

[0044] The above R ２１ and R ２２ Examples of the monovalent aromatic hydrocarbon group having 6 to 40 carbon atoms represented by the formula (I) include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; and aralkyl groups such as a benzyl group, a phenethyl group, and a naphthylmethyl group.

[0045] The monovalent heteroatom-containing group and the divalent heteroatom-containing group include the above-mentioned R １ The monovalent heteroatom-containing groups and divalent heteroatom-containing groups mentioned in the above can be suitably used.

[0046] The above R ２３ and R ２４ The monovalent organic group having 1 to 40 carbon atoms represented by the above R ２１ and R ２２ A monovalent organic group having 1 to 40 carbon atoms and represented by the following formula can be suitably used.

[0047] The above R ２３ and R ２４ Examples of the 3- to 10-membered ring structure formed by combining these together with the nitrogen atom to which they are bonded include nitrogen-containing heterocyclic structures such as aziridine, azetidine, diazetidine, pyrrolidine, pyrazolidine, imidazolidine, piperidine, piperazine, morpholine, thiomorpholine, and azocane, and among these, morpholine is preferred.

[0048] The above R ２１ , R ２２ , R ２３ , and R ２４ From the viewpoint of improving hydrophobicity and ensuring uneven distribution on the surface, it is preferable that each of the groups independently be a monovalent chain hydrocarbon group having 2 to 10 carbon atoms.

[0049] The cation of the compound (C) may be a cation represented by the following formula (1-1-a). (In formula (1-1-a), R ２１１ is a monovalent chain organic group having 6 to 8 carbon atoms. ２２１ , R ２３１ and R ２４１ are each independently a monovalent chain hydrocarbon group having 2 to 8 carbon atoms.

[0050] R ２１１ The monovalent chain organic group having 6 to 8 carbon atoms represented by the above R ２１ and R ２２ Among the monovalent organic groups having 1 to 40 carbon atoms represented by the following formula, those having only a chain structure and having the corresponding number of carbon atoms can be suitably used.

[0051] R ２２１ , R ２３１ and R ２４１ The monovalent chain hydrocarbon group having 2 to 8 carbon atoms in R ２１ and R ２２ Among the monovalent chain hydrocarbon groups having 1 to 40 carbon atoms represented by the following formula, those having the corresponding number of carbon atoms can be suitably used.

[0052] Specific examples of the cation of compound (C) include, but are not limited to, structures of the following formulae:

[0053]

[0054]

[0055] Examples of the compound (C) include compounds represented by the following formula:

[0056]

[0057]

[0058]

[0059]

[0060] The present composition may contain one or more types of compound (C) in combination.

[0061] The lower limit of the content of the compound (C) (total amount when multiple types are contained) is preferably 0.05 parts by mass, more preferably 0.1 parts by mass, and even more preferably 0.3 parts by mass, relative to 100 parts by mass of the polymer (A) described below. The upper limit of the content is preferably 10 parts by mass, more preferably 7 parts by mass, and even more preferably 5 parts by mass. By setting the content of the compound (C) within the above range, the pattern formability of the radiation-sensitive composition can be further improved.

[0062] <Polymer (A)> The polymer (A) is an aggregate of polymer chains containing a structural unit (I) having a phenolic hydroxyl group (hereinafter, this polymer will also be referred to as a "base polymer (A)"). Because the polymer (A) contains the structural unit (I), the crosslinking reaction of the polymer (A) proceeds sufficiently, and the radiation-sensitive composition has excellent pattern formability.

[0063] In addition to the structural unit (I), the base polymer (A) preferably contains a structural unit (II) having an aromatic ring, which will be described later, and may contain structural units other than the structural units (I) and (II). Each structural unit will be described below.

[0064] [Structural Unit (I)] The polymer (A) contains a structural unit (I) having a phenolic hydroxyl group. The structural unit (I) is preferably represented by the following formula (4).

[0065] (In the above formula (4), R Ａ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ＣＡ is a single bond, -COO- ＊ or -O-. * represents a bond on the aromatic ring side. X represents a halogen atom, a cyano group, a nitro group, an alkyl group, an alkoxy group, a carboxy group, a fluorinated alkyl group, an alkoxycarbonyl group, an acyl group, or an acyloxy group. When there are multiple Xs, the multiple Xs may be the same or different. p represents an integer of 0 to 2, n represents an integer of 1 to 8, and m represents an integer of 0 to 8, provided that 1≦n+m≦2p+5 is satisfied.)

[0066] The above R Ａ is preferably a hydrogen atom or a methyl group.

[0067] L ＣＡ is a single bond or -COO- ＊ is preferred.

[0068] The alkyl group in X is R １ The alkyl group in the following formula can be preferably used.

[0069] The alkyl group moiety of the alkoxy group and the alkyl group moiety of the alkoxycarbonyl group in X are R １ The alkyl group in the following formula can be preferably used.

[0070] Examples of the fluorinated alkyl group for X include linear or branched fluorinated alkyl groups having 1 to 8 carbon atoms, such as trifluoromethyl and pentafluoroethyl groups.

[0071] Examples of the acyl group for X include aliphatic or aromatic acyl groups having 2 to 12 carbon atoms, such as an acetyl group, a propionyl group, a benzoyl group, and an acryloyl group. Examples of the acyloxy group include aliphatic or aromatic acyloxy groups having 2 to 12 carbon atoms, such as an acetyloxy group, a propionyloxy group, a benzoyloxy group, and an acryloyloxy group.

[0072] Among these, X is preferably a halogen atom, more preferably an iodine atom or a fluorine atom.

[0073] The above-mentioned p is preferably 0 or 1, and more preferably 0.

[0074] The above n is preferably an integer of 1 to 3, and more preferably 1 or 2.

[0075] The above m is preferably an integer of 0 to 3, and more preferably an integer of 0 to 2.

[0076] The structural unit (I) is more preferably a structural unit represented by the following formula (4-1): (In formula (4-1), n1 is an integer of 1 to 5. m1 is an integer of 0 to 4. However, m1+n1 is 5 or less. R Ａ, X has the same meaning as in formula (4) above.

[0077] The above n1 is preferably an integer of 1 to 3, and more preferably 1 or 2.

[0078] The above m1 is preferably an integer of 0 to 3, and more preferably an integer of 0 to 2.

[0079] The structural unit (I) is preferably a structural unit represented by the following formula: Ａ is the same as the above formula (4).

[0080]

[0081] The base polymer (A) may contain one type of structural unit (I) or a combination of two or more types.

[0082] The lower limit of the content of the structural unit (I) (total content when multiple types of structural unit (I) are present) relative to all structural units constituting the polymer (A) is preferably 30 mol%, more preferably 40 mol%, and even more preferably 50 mol%. The upper limit of the content is preferably 95 mol%, more preferably 90 mol%, and even more preferably 85 mol%. By setting the content of the structural unit (I) within the above range, the sensitivity of the radiation-sensitive composition can be further improved.

[0083] [Structural Unit (II)] From the viewpoint of etching resistance, the polymer (A) preferably contains a structural unit (II) having an aromatic ring (excluding those corresponding to the structural unit (I) above).

[0084] The structural unit (II) is preferably a structural unit represented by the following formula (5).

[0085] (In the above formula (5), R Ａ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ＣＡ is a single bond, -COO- ＊ Or -O-. * is a bond on the aromatic ring side. X １X is a halogen atom, a cyano group, a nitro group, an alkyl group, an alkoxy group, a carboxy group, a fluorinated alkyl group, an alkoxycarbonyl group, an acyl group, or an acyloxy group. １ If there are multiple Xs, １ are the same or different. p1 is an integer of 0 to 2, and m2 is an integer of 0 to 8.

[0086] The above R A is preferably a hydrogen atom or a methyl group.

[0087] The above L ＣＡ is a single bond or -COO- ＊ is preferred, and a single bond is more preferred.

[0088] X １ As the alkyl group, alkoxy group, fluorinated alkyl group, alkoxycarbonyl group, acyl group, and acyloxy group in the above, those exemplified as X in the above formula (4) can be suitably used. １ is preferably an alkyl group or a carboxy group.

[0089] The above p1 is preferably 0 or 1, and more preferably 0.

[0090] The above m2 is preferably an integer of 0 to 3, and more preferably 0 or 1.

[0091] The structural unit (II) is preferably a structural unit represented by the following formula: Ａ is the same as the above formula (5).

[0092]

[0093] Among these, the structural unit (II) is preferably a structural unit derived from unsubstituted styrene.

[0094] The base polymer (A) may contain one type of structural unit (II) or a combination of two or more types.

[0095] When the base polymer (A) contains the structural unit (II), the lower limit of the content of the structural unit (II) (total content when multiple types of structural unit (II) are present) is preferably 1 mol %, more preferably 3 mol %, and even more preferably 5 mol %, based on all structural units constituting the polymer (A). 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 (II) within the above range, the etching resistance and sensitivity of the radiation-sensitive composition can be further improved.

[0096] [Structural Unit (III)] The polymer (A) may contain a structural unit (III) containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, a sultone structure, and a cyclic sulfone structure. The structural unit (III) in the base polymer (A) can adjust the solubility in a developer, thereby improving the lithography performance, such as resolution, of the radiation-sensitive composition. Furthermore, the adhesion between a resist pattern formed from the base polymer (A) and a substrate can be improved.

[0097] Examples of the structural unit (III) include structural units represented by the following formulae (T-1) to (T-11).

[0098]

[0099] In the above formula, R Ｌ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｌ２ ~R Ｌ５ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxy group, a hydroxymethyl group, a dimethylamino group, or -COOR Ｌ６ It is. Ｌ６ is a monovalent hydrocarbon group having 1 to 20 carbon atoms. Ｌ４ and R Ｌ５ may be combined with each other to form a divalent alicyclic hydrocarbon group having 3 to 8 carbon atoms together with the carbon atoms to which they are attached. ２is 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.

[0100] The above R Ｌ４ and R Ｌ５ Examples of the divalent alicyclic hydrocarbon group having 3 to 8 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded include R ２１ and R ２２ Among the monovalent alicyclic hydrocarbon groups having 3 to 40 carbon atoms in the above formula, a group in which one hydrogen atom has been removed from a group having the corresponding number of carbon atoms can be suitably used. One or more hydrogen atoms on this alicyclic hydrocarbon group may be substituted with a hydroxy group.

[0101] The above R Ｌ６ The monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (1) is ２１ and R ２２ Monovalent hydrocarbon groups having 1 to 40 carbon atoms, represented by the following formula (I) and having the corresponding carbon number, can be suitably used.

[0102] 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-.

[0103] The above L ２ As the divalent linear or branched hydrocarbon group having 1 to 10 carbon atoms in the formula (1), R ２１ and R ２２ A group in which one hydrogen atom has been removed from a monovalent chain hydrocarbon group having 1 to 40 carbon atoms, represented by the following formula:

[0104] The above L ２ As the divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, R ２１ and R ２２ A group in which one hydrogen atom has been removed from a monovalent alicyclic hydrocarbon group having 3 to 40 carbon atoms, represented by the following formula, can be suitably used.

[0105] Of these, the structural unit (III) 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.

[0106] The base polymer (A) may contain one type of structural unit (III) or a combination of two or more types.

[0107] When the base polymer (A) contains the structural unit (III), the lower limit of the content of the structural unit (III) (the total content when multiple types are contained) is preferably 3 mol%, more preferably 5 mol%, and even more preferably 8 mol%, based on all structural units constituting the base polymer (A). 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 (III) within the above range, the radiation-sensitive composition can further improve lithography performance such as resolution and adhesion of the formed resist pattern to the substrate.

[0108] [Structural Unit (IV)] The base polymer (A) can contain a structural unit (IV) containing a polar group (excluding those corresponding to the structural units (I) to (III)). By further containing the structural unit (IV), the base polymer (A) can adjust its solubility in a developer, thereby improving the lithography performance, such as resolution, of the radiation-sensitive composition. Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a nitro group, and a sulfonamide group. Of these, a hydroxy group and a carboxy group are preferred, and a hydroxy group is more preferred.

[0109] Examples of the structural unit (IV) include structural units represented by the following formula:

[0110]

[0111]

[0112] In the above formula, R Ｋis a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0113] The base polymer (A) may contain one type of structural unit (IV) or a combination of two or more types.

[0114] When the base polymer (A) contains the structural unit (IV), the lower limit of the content of the structural unit (IV) (the total content when multiple structural units are contained) is preferably 0.5 mol%, more preferably 1 mol%, and even more preferably 3 mol%, based on all structural units constituting the base polymer (A). 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 (IV) within the above range, the lithography performance, such as resolution, of the radiation-sensitive composition can be further improved.

[0115] [Structural Unit (V)] The base polymer (A) can contain, as a structural unit other than the structural units listed above, a structural unit having an aliphatic hydrocarbon group represented by the following formula (6) (hereinafter also referred to as "structural unit (V)"). (In the above formula (6), R １α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２α is a monovalent aliphatic hydrocarbon group having 1 to 40 carbon atoms.

[0116] In the above formula (6), R ２α The monovalent aliphatic hydrocarbon group having 1 to 40 carbon atoms represented by the formula (1) is ２１ and R ２２ In the above formula, a monovalent chain hydrocarbon group having 1 to 40 carbon atoms and a monovalent alicyclic hydrocarbon group having 3 to 40 carbon atoms can be suitably used.

[0117] The base polymer (A) may contain one type of structural unit (V) or a combination of two or more types.

[0118] When the base polymer (A) contains the structural unit (V), the content of the structural unit (V) (the total content when multiple structural units (V) are contained) is preferably 0.5 mol %, more preferably 1 mol %, and even more preferably 3 mol %, based on the total structural units constituting the base polymer (A). The upper limit of the content is preferably 50 mol %, more preferably 40 mol %, and even more preferably 35 mol %.

[0119] (Method for Synthesizing Base Polymer (A)) The base polymer (A) can be synthesized, for example, by polymerizing monomers that provide each structural unit in an appropriate solvent using a radical polymerization initiator or the like.

[0120] 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, and AIBN is more preferred. These radical initiators can be used alone or in combination of two or more.

[0121] 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; lactones such as γ-butyrolactone and δ-valerolactone; ketones such as acetone, 2-butanone, 4-methyl-2-pentanone, 2-heptanone, and cyclohexanone; ethers such as tetrahydrofuran, dimethoxyethanes, and diethoxyethanes; Examples of the solvent include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-methoxy-2-propanol, 4-methyl-2-pentanol, etc. These solvents used in the polymerization may be used alone or in combination of two or more.

[0122] The reaction temperature in the polymerization is usually 40° C. to 150° C., preferably 50° C. to 120° C. The reaction time is usually 1 hour to 48 hours, preferably 1 hour to 24 hours.

[0123] The molecular weight of the base polymer (A) is not particularly limited, but the lower limit of the weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) is preferably 2,000, more preferably 2,500, and even more preferably 3,000. The upper limit of Mw is preferably 30,000, more preferably 20,000, and even more preferably 15,000. By setting the Mw of the base polymer (A) within the above range, it is possible to impart good developability to the resulting resist film.

[0124] The ratio (Mw / Mn) of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the base polymer (A) 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.

[0125] The Mw and Mn of the polymer in this specification are values ​​measured using gel permeation chromatography (GPC) under the following conditions.

[0126] GPC columns: two G2000HXL, one G3000HXL, one G4000HXL (all manufactured by Tosoh Corporation) Column temperature: 40°C Elution solvent: tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0 mass% Sample injection volume: 100 μL Detector: differential refractometer Standard material: monodisperse polystyrene

[0127] The content of the base polymer (A) is preferably 60% by mass or more, more preferably 65% ​​by mass or more, and even more preferably 70% by mass or more, based on the total solid content of the radiation-sensitive composition.

[0128] <Crosslinking Agent (Q)> The present composition contains a crosslinking agent (Q). The type of crosslinking agent (Q) is not particularly limited, and examples thereof include crosslinking agents having two or more crosslinkable groups per molecule. The number of crosslinkable groups per molecule is two or more, preferably 2 to 10, and more preferably 2 to 6.

[0129] The crosslinkable group is not particularly limited, but preferably has at least one selected from the group consisting of a methylol group, an alkoxymethyl group, a glycidyl group, a (meth)acryloyl group, and a vinyl group, more preferably has a methylol group or an alkoxymethyl group, and even more preferably has an alkoxymethyl group.

[0130] By including a crosslinking agent (Q), the present composition can be made into a composition for forming a negative pattern. That is, in the exposed areas, an acid generated from the radiation-sensitive acid generator (B) described below promotes a crosslinking reaction of the polymer (A) with the crosslinking agent (Q), thereby curing the polymer, thereby making the polymer substantially insoluble in an alkaline developer. On the other hand, by removing the unexposed areas with an alkaline developer, a negative pattern can be formed.

[0131] The crosslinking agent (Q) is not particularly limited, but examples thereof include amino-based crosslinking agents having one or more nitrogen atoms, and phenolic hydroxyl group-containing crosslinking agents.

[0132] The amino-based crosslinking agent is not particularly limited as long as it has one or more nitrogen atoms, and examples thereof include glycoluril-type crosslinking agents having a glycoluril skeleton, melamine-type crosslinking agents having a melamine skeleton, and urea-type crosslinking agents having a cyclic alkylene urea skeleton.

[0133] Among these, as the crosslinking agent (Q), amino-based crosslinking agents are preferred, and glycoluril-type crosslinking agents and melamine-type crosslinking agents are more preferred.

[0134] An example of the glycoluril crosslinking agent is a compound (C1) represented by the following formula (2). (In formula (2), R ３１ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ３１ is *-R ３３ -OR ３４ (R ３３ is a divalent hydrocarbon group having 1 to 10 carbon atoms. ３４ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * represents a bond to the nitrogen atom. ３２ are each independently a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms.

[0135] The above R ３１ The monovalent organic group having 1 to 20 carbon atoms in the formula (1) is R ２１ and R ２２ Among the monovalent organic groups having 1 to 40 carbon atoms in the above, those having the corresponding number of carbon atoms can be suitably used.

[0136] The above R ３３ The divalent hydrocarbon group having 1 to 10 carbon atoms in the formula (1) is R ２１ and R ２２ Among the monovalent hydrocarbon groups having 1 to 40 carbon atoms in the above formula, groups in which one hydrogen atom has been removed from the group having the corresponding number of carbon atoms can be suitably used.

[0137] The above R ３２ , R ３４The monovalent hydrocarbon group having 1 to 10 carbon atoms in the formula (1) is R ２１ and R ２２ Among the monovalent hydrocarbon groups having 1 to 40 carbon atoms in the above, those having the corresponding number of carbon atoms can be suitably used.

[0138] The glycoluril crosslinking agent is preferably a compound (C1-1) represented by the following formula (2-1). (In formula (2-1), R ３２ are each independently a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms. ３３ are each independently a divalent hydrocarbon group having 1 to 10 carbon atoms. ３４ are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0139] R ３２ a monovalent organic group having 1 to 10 carbon atoms in ３３ a divalent hydrocarbon group having 1 to 10 carbon atoms in ３４ As the monovalent hydrocarbon group having 1 to 10 carbon atoms in the above formula (2), the monovalent organic groups having 1 to 10 carbon atoms, the divalent hydrocarbon groups having 1 to 10 carbon atoms, and the monovalent hydrocarbon groups having 1 to 10 carbon atoms can be suitably used.

[0140] Among these, the above R ３２ is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. ３３ As the R, an alkylene group having 1 to 5 carbon atoms is preferred, and a methylene group or an ethylene group is more preferred. ３４ As the alkyl group, an alkyl group having 1 to 5 carbon atoms is preferred, and a methyl group or a butyl group is more preferred.

[0141] Examples of glycoluril-type crosslinking agents include crosslinking agents of the following formula:

[0142] (wherein Et is an ethyl group, ｎ Bu is an n-butyl group, ｉ Pr represents an isopropyl group.

[0143] An example of the melamine-type crosslinking agent is a compound (C2) represented by the following formula (3). (In formula (3), R ４ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ４ is *-R ４１ -OR ４２ (R ４１ is a divalent hydrocarbon group having 1 to 10 carbon atoms. ４２ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * represents a bond to the nitrogen atom.

[0144] The above R ４ The monovalent organic group having 1 to 20 carbon atoms in the formula (1) is R ２１ and R ２２ Among the monovalent organic groups having 1 to 40 carbon atoms in the above, those having the corresponding number of carbon atoms can be suitably used.

[0145] The above R ４１ The divalent hydrocarbon group having 1 to 10 carbon atoms in the above R ２１ and R ２２ Among the monovalent hydrocarbon groups having 1 to 40 carbon atoms in the above formula, groups in which one hydrogen atom has been removed from the group having the corresponding number of carbon atoms can be suitably used.

[0146] The above R ４２ The monovalent hydrocarbon group having 1 to 10 carbon atoms in the formula (1) is R ２１ and R ２２ Among the monovalent hydrocarbon groups having 1 to 40 carbon atoms in the above, those having the corresponding number of carbon atoms can be suitably used.

[0147] The melamine-type crosslinking agent is preferably a compound (C2-1) represented by the following formula (3-1). (In formula (3-1), R ４１ are each independently a divalent hydrocarbon group having 1 to 10 carbon atoms. ４２ are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0148] R ４１ a divalent hydrocarbon group having 1 to 10 carbon atoms in ４２As the monovalent hydrocarbon group having 1 to 10 carbon atoms in the formula (3), the divalent hydrocarbon group having 1 to 10 carbon atoms and the monovalent hydrocarbon group having 1 to 10 carbon atoms listed above can be suitably used.

[0149] Among these, the above R ４１ As the R, an alkylene group having 1 to 5 carbon atoms is preferred, and a methylene group or an ethylene group is more preferred. ４２ As the alkyl group, an alkyl group having 1 to 5 carbon atoms is preferred, and a methyl group is more preferred.

[0150] Examples of the melamine-type crosslinking agent include crosslinking agents of the following formula:

[0151] (wherein Me is a methyl group, Et is an ethyl group, ｎ Bu is an n-butyl group, ｉ Pr represents an isopropyl group.

[0152] Examples of the urea-type crosslinking agent having a cyclic alkylene urea skeleton include the following crosslinking agents.

[0153]

[0154] Examples of the phenolic hydroxyl group-containing crosslinking agent include the following crosslinking agents.

[0155]

[0156] In the present invention, the crosslinking agent (Q) may be used alone or in combination of two or more.

[0157] The lower limit of the content of the crosslinking agent (Q) (the total amount of crosslinking agents (Q) when multiple types are contained) is preferably 0.5 parts by mass, more preferably 1 part by mass, and even more preferably 3 parts by mass, relative to 100 parts by mass of the polymer (A). The upper limit of the content is preferably 20 parts by mass, more preferably 10 parts by mass. The content of the crosslinking agent (Q) is appropriately selected depending on the type of polymer used, exposure conditions, required sensitivity, and the like. This allows excellent CDU, pattern circularity, and pattern rectangularity to be exhibited during resist pattern formation.

[0158] <Radiation-Sensitive Acid Generator (B)> The present composition may further contain a radiation-sensitive acid generator (B) that generates an acid upon exposure to light.

[0159] The radiation-sensitive acid generator (B) is a component that generates an acid upon exposure. The acid generated upon exposure promotes a crosslinking reaction of the base polymer (A) with the crosslinking agent (Q). Examples of the radiation-sensitive acid generator (B) include a nonionic radiation-sensitive acid generator (B1) and an ionic radiation-sensitive acid generator (B2).

[0160] Examples of the nonionic radiation-sensitive acid generator (B1) include a compound represented by the following formula (B1-1) and a compound represented by the following formula (B1-2).

[0161] (In the above formula (B1-1), R ５１ is a divalent hydrocarbon group having 1 to 10 carbon atoms, and R ５２ is a monovalent organic group having 1 to 20 carbon atoms.

[0162] (In the above formula (B1-2), R ５３ are each independently a monovalent organic group having 1 to 20 carbon atoms.

[0163] The above R ５１ The divalent hydrocarbon group having 1 to 10 carbon atoms is R ２１ and R ２２ Among the monovalent hydrocarbon groups having 1 to 40 carbon atoms in the above formula, groups in which one hydrogen atom has been removed from the group having the corresponding carbon number can be suitably used. ５１ As the alkylene group, an alkylene group having 1 to 3 carbon atoms and a cycloalkylene group containing a cyclic skeleton having an unsaturated bond are preferred.

[0164] The above R ５２ The monovalent organic group having 1 to 20 carbon atoms is R ２１ and R ２２ Among the monovalent organic groups having 1 to 40 carbon atoms in the above formula, those having the corresponding carbon number can be suitably used. ５２It is preferable that the alkyl group has at least one structure selected from the group consisting of an alicyclic structure, an ester bond, and a halogen atom.

[0165] The above R ５３ The monovalent organic group having 1 to 20 carbon atoms is R ２１ and R ２２ Among the monovalent organic groups having 1 to 40 carbon atoms in the above formula, those having the corresponding carbon number can be suitably used. ５３ It is preferable that the alkyl group has at least one structure selected from the group consisting of an alicyclic structure and an ether bond.

[0166] The alicyclic structure may be R ２１ and R ２２ A structure corresponding to the monovalent alicyclic hydrocarbon group having 3 to 40 carbon atoms in the above formula can be suitably employed.

[0167] Examples of the compound represented by the above formula (B1-1) or (B1-2) include the following structures.

[0168] Examples of the ionic radiation-sensitive acid generator (B2) include onium salt compounds (B2) represented by the following formula (B2). (In formula (B2), R ６０ is a monovalent organic group having 1 to 40 carbon atoms. ｆ１ and R ｆ２ are each independently a hydrogen atom, a fluorine atom, or a monovalent fluorinated hydrocarbon group. ｆ１ and R ｆ２ If there are multiple R ｆ１ and R ｆ２ are the same or different, and t is an integer of 0 to 4. Z ＋ is a radiation-sensitive onium cation.

[0169] R ６０ The monovalent organic group having 1 to 40 carbon atoms represented by the formula (1) is R ２１ and R ２２ Among these, monovalent organic groups having 1 to 40 carbon atoms such as R ６０From the viewpoint of being able to appropriately control the diffusion length of the generated acid, it is preferable that R is a structure containing an alicyclic structure. ２１ and R ２２ Examples of the structure include a structure corresponding to the monovalent alicyclic hydrocarbon group having 3 to 40 carbon atoms in the above formula.

[0170] R ｆ１ and R ｆ２ The monovalent fluorinated hydrocarbon group represented by the formula (1) is R ２１ and R ２２ and groups in which some or all of the hydrogen atoms of the monovalent hydrocarbon group having 1 to 40 carbon atoms have been substituted with fluorine atoms.

[0171] Specific examples of the anion of the onium salt compound (B2) include, but are not limited to, structures of the following formulae:

[0172]

[0173]

[0174]

[0175] The above Z of the onium salt compound (B2) ＋ The onium cation represented by the formula (X-1) is preferably a radiation-sensitive onium cation, and examples thereof include radiation-decomposable onium cations containing elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi. Examples of the radiation-decomposable onium cation include sulfonium cation, tetrahydrothiophenium cation, iodonium cation, phosphonium cation, diazonium cation, and pyridinium cation. Of these, sulfonium cation or iodonium cation is preferred. The sulfonium cation or iodonium cation is preferably represented by the following formulas (X-1) to (X-6).

[0176]

[0177] In the above formula (X-1), R ａ１ , R ａ２ and R ａ３are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyloxy group, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, or -OSO ２ -R Ｐ , -SO ２ -R Ｑ , -S-R Ｔ , -O-, -CO-, or a combination thereof, or a ring structure formed by combining two or more of these groups. The ring structure may contain a heteroatom such as O or S between the carbon-carbon bonds that form the skeleton. Ｐ , R Ｑ and R Ｔ are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2, and k3 are each independently an integer of 0 to 5. R ａ１ ~R ａ３ and R Ｐ , R Ｑ and R Ｔ If there are multiple R ａ１ ~R ａ３ and R Ｐ , R Ｑ and R Ｔ may be the same or different.

[0178] In the above formula (X-2), R ｂ１ is a substituted or unsubstituted linear or branched alkyl group or alkoxy group having 1 to 20 carbon atoms, an alkoxyalkyloxy group, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. ｋ is 0 or 1. ｋ When is 0, k4 is an integer from 0 to 4, and n ｋ When is 1, k4 is an integer from 0 to 7. ｂ１ If there are multiple R ｂ１may be the same or different, and multiple R ｂ１ may represent a ring structure formed by combining with each other. ｂ２ is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. Ｃ is a single bond or a divalent linking group. k5 is an integer of 0 to 4. R ｂ２ If there are multiple R ｂ２ may be the same or different, and multiple R ｂ２ may represent a ring structure formed by combining with each other, and q is an integer of 0 to 3. ＋ The ring structure containing the following may contain a heteroatom such as O or S between the carbon-carbon bonds that form the skeleton.

[0179] In the above formula (X-3), R ｃ１ , R ｃ２ and R ｃ３ are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms.

[0180] In the above formula (X-4), R ｇ１ is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. ｋ２ is 0 or 1. ｋ２ When is 0, k10 is an integer from 0 to 4, and n ｋ２ When is 1, k10 is an integer from 0 to 7. ｇ１ If there are multiple R ｇ１ may be the same or different, and multiple R ｇ１ may represent a ring structure formed by combining with each other. ｇ２ and R ｇ３are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyloxy group, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, or a ring structure formed by combining these groups together. k11 and k12 are each independently an integer of 0 to 4. R ｇ２ and R ｇ３ If there are multiple R ｇ２ and R ｇ３ may be the same or different.

[0181] In the above formula (X-5), R ｄ１ and R ｄ２ are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyl group, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a halogen atom, a halogenated alkyl group having 1 to 4 carbon atoms, a nitro group, or a ring structure formed by combining two or more of these groups. k6 and k7 are each independently an integer of 0 to 5. R ｄ１ and R ｄ２ If there are multiple R ｄ１ and R ｄ２ may be the same or different.

[0182] In the above formula (X-6), R ｅ１ and R ｅ２ are each independently a halogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k8 and k9 are each independently an integer of 0 to 4.

[0183] Specific examples of the radiation-sensitive onium cation include, but are not limited to, structures of the following formulas:

[0184]

[0185] (In the formula, tBu represents a t-butyl group, and Me represents a methyl group.)

[0186]

[0187]

[0188]

[0189] The radiation-sensitive acid generator (B2) can be obtained by appropriately combining the above-mentioned anion and the above-mentioned radiation-sensitive onium cation.

[0190] As the radiation-sensitive acid generator (B), a nonionic radiation-sensitive acid generator (B1) is preferred from the viewpoints of sensitivity, CDU, exposure latitude, and depth of focus.

[0191] In the present invention, the above-mentioned radiation-sensitive acid generator (B) can be used alone or in combination of two or more.

[0192] When the radiation-sensitive composition contains a radiation-sensitive acid generator (B), the lower limit of the content of the radiation-sensitive acid generator (B) (total content when multiple types are used) is preferably 1 part by mass, more preferably 5 parts by mass, and even more preferably 8 parts by mass, relative to 100 parts by mass of the polymer (A). The upper limit of the content is preferably 60 parts by mass, more preferably 50 parts by mass, and even more preferably 40 parts by mass. This allows excellent sensitivity to be exhibited during resist pattern formation.

[0193] <Solvent (E)> The radiation-sensitive composition according to this embodiment contains a solvent (E). The solvent (E) is not particularly limited as long as it is a solvent that can dissolve or disperse at least the polymer (A), the compound (C), the crosslinking agent (Q), and, optionally, the radiation-sensitive acid generator (B).

[0194] Examples of the solvent include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0195] Examples of alcohol-based solvents include monoalcohol-based 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-based 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; and polyhydric alcohol partially etherified solvents in which some of the hydroxy groups in the above-mentioned polyhydric alcohol-based solvents have been etherified. In this embodiment, alcoholic acid ester solvents such as methyl lactate, ethyl lactate, propyl lactate, butyl lactate, methyl 2-hydroxyisobutyrate, i-propyl 2-hydroxyisobutyrate, i-butyl 2-hydroxyisobutyrate, and n-butyl 2-hydroxyisobutyrate are also included in the alcoholic solvents.

[0196] Examples of ether-based solvents include dialkyl ether-based solvents such as diethyl ether, dipropyl ether, and dibutyl ether; cyclic ether-based solvents such as tetrahydrofuran and tetrahydropyran; aromatic ring-containing ether-based solvents such as diphenyl ether and anisole (methyl phenyl ether); and polyhydric alcohol ether-based solvents obtained by etherifying the hydroxy groups of the above-mentioned polyhydric alcohol-based solvents.

[0197] 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; 2,4-pentanedione, acetonylacetone, and acetophenone.

[0198] Examples of the amide solvent include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; and chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0199] Examples of ester-based solvents include monocarboxylic acid ester-based solvents such as n-butyl acetate; polyhydric alcohol partial ether acetate-based solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; lactone-based solvents such as γ-butyrolactone and valerolactone; carbonate-based solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; and polyvalent carboxylic acid diester-based solvents such as propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, and diethyl phthalate.

[0200] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, di-isopropylbenzene, and n-pentylnaphthalene.

[0201] Among these, ester-based solvents and ether-based solvents are preferred, polyhydric partial ether acetate-based solvents, lactone-based solvents, monocarboxylic acid ester-based solvents and ketone-based solvents are more preferred, and propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, γ-butyrolactone, ethyl lactate, cyclohexanone, cyclopentanone and propylene glycol monomethyl ether are even more preferred. The radiation-sensitive composition may contain one or more solvents.

[0202] (Other Optional Components) The radiation-sensitive composition may contain other optional components in addition to the components described above. Examples of the other optional components include a distribution promoter, a dissolution 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.

[0203] The surfactant is not particularly limited, but a non-fluorine-based surfactant or a non-silicone-based surfactant can be suitably used.

[0204] When the radiation-sensitive composition contains the optional component, the content of the optional component is preferably 0.05 parts by mass or more, more preferably 0.08 parts by mass or more, and preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 1 part by mass or less, relative to 100 parts by mass of the base polymer (A).

[0205] <Method for Preparing Radiation-Sensitive Composition> The radiation-sensitive composition can be prepared, for example, by mixing the polymer (A), the compound (C), the crosslinking agent (Q), the solvent (E), and, if necessary, the radiation-sensitive acid generator (B) in a predetermined ratio. After mixing, the radiation-sensitive composition is preferably filtered, for example, through a filter having a pore size of about 0.05 μm to 0.40 μm. The solids concentration of the radiation-sensitive composition is usually 0.1% by mass to 50% by mass, preferably 0.5% by mass to 30% by mass, and more preferably 1% by mass to 20% by mass.

[0206] <<Pattern Forming Method>> A pattern forming method according to one embodiment of the present invention includes: a step (1) of applying the radiation-sensitive composition directly or indirectly to a substrate to form a resist film (hereinafter also referred to as a "resist film forming step"); a step (2) of exposing the resist film (hereinafter also referred to as an "exposure step"); and a step (3) of developing the exposed resist film (hereinafter also referred to as a "development step").

[0207] According to the above-described resist pattern forming method, a high-quality resist pattern can be formed because the above-described radiation-sensitive composition is used, which is capable of forming a resist film that is excellent in sensitivity, CDU, pattern circularity, pattern rectangularity, exposure latitude, and depth of focus in the exposure step. Each step will be described below.

[0208] [Resist Film Forming Step] In this step (step (1) above), a resist film is formed from the radiation-sensitive 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 JP-B-6-12452 and JP-A-59-93448, may be formed on the substrate. Examples of coating methods include spin coating, casting coating, and roll coating. After coating, if necessary, pre-baking (PB) may be performed to volatilize the solvent in the coating film. The PB temperature is typically 60°C to 150°C, and preferably 80°C to 140°C. The PB time is typically 5 to 600 seconds, and preferably 10 to 300 seconds.

[0209] The lower limit of the thickness of the resist film to be formed is preferably 10 nm, more preferably 15 nm, and even more preferably 20 nm. The upper limit of the thickness is preferably 9000 nm, more preferably 4000 nm. In particular, when a thick resist film is exposed to KrF excimer laser light in the exposure step described below, the lower limit of the thickness may be 100 nm, 150 nm, or 200 nm.

[0210] [Exposure Step] In this step (step (2) above), the resist film formed in the resist film formation step (1) above is exposed to radiation through a photomask (or, in some cases, through an immersion liquid such as water). Examples of radiation used for exposure include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet), 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, a KrF excimer laser is suitable for use with the composition of the present invention.

[0211] After the exposure, it is preferable to perform post-exposure baking (PEB). This PEB causes a difference in solubility in a developer between the exposed and unexposed areas. The PEB temperature is usually 50°C to 180°C, preferably 80°C to 150°C. The PEB time is usually 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds.

[0212] [Development Step] In this step (step (3) above), the resist film exposed in the exposure step (step (2) above) is developed. This allows a predetermined resist pattern to be formed. After development, the resist film is generally washed with a rinse liquid such as water or alcohol, and then dried.

[0213] In the case of alkaline development, the developer used in the development may be, for example, an alkaline aqueous solution containing at least one alkaline compound dissolved therein, such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, or 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, an aqueous TMAH solution is preferred, and a 2.38% by mass aqueous TMAH solution is more preferred.

[0214] 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 solvents for the radiation-sensitive composition. Among these, ether solvents, ester solvents, and ketone solvents are preferred. As the ether solvent, glycol ether solvents are preferred, and ethylene glycol monomethyl ether and propylene glycol monomethyl ether are more preferred. As the ester solvent, acetate ester solvents are preferred, and n-butyl acetate and amyl acetate are more preferred. As the ketone solvent, chain ketones are preferred, and 2-heptanone is 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.

[0215] As mentioned above, the developer may be either an alkaline developer or an organic solvent developer. The radiation-sensitive composition of the present invention is preferably used to form a negative pattern.

[0216] Examples of the developing method include a method of immersing a substrate in a tank filled with a developer for a certain period of time (dip method), a method of piling up a developer on the surface of the substrate by surface tension and leaving it to stand for a certain period of time to develop (puddle method), a method of spraying the developer onto the surface of the substrate (spray method), and a method of continuously discharging the developer while scanning a developer discharging nozzle at a constant speed onto a substrate that is rotating at a constant speed (dynamic dispense method).

[0217] <Compound> A compound according to one embodiment of the present invention is represented by the following formula (1-1). (In formula (1-1), R ２１１ is a monovalent chain organic group having 6 to 8 carbon atoms. ２２１ , R ２３１ and R ２４１ are each independently a monovalent chain hydrocarbon group having 2 to 8 carbon atoms.- is an anion represented by the following formula (1-1-a), (1-1-b), (1-1-c), or (1-1-d). (In formulas (1-1-a), (1-1-b), (1-1-c), and (1-1-d), W ａ is a substituted or unsubstituted alicyclic hydrocarbon group having 3 to 20 carbon atoms. ｂ is an organic group having 3 to 20 carbon atoms. ｃ and W ｄ are each independently an organic group having 1 to 20 carbon atoms. ａ , W ｂ , W ｃ and W ｄ does not contain aromatic hydrocarbon groups.

[0218] Examples of the compound include those compounds (C) in the radiation-sensitive composition of the present invention that correspond to the above formula (1-1).

[0219] 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.

[0220] [Weight-average molecular weight (Mw) and number-average molecular weight (Mn)] The Mw and Mn of the polymer were measured under the conditions described above. The dispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[0221] [ １３ C-NMR analysis of polymer １３ C-NMR analysis was carried out using a nuclear magnetic resonance spectrometer (JNM-Delta400 manufactured by JEOL Ltd.).

[0222] <Synthesis of Polymer> The monomers used in the synthesis of each polymer in each Example and Comparative Example are shown below. In the following synthesis examples, unless otherwise specified, parts by mass refer to a value when the total mass of the monomers used is taken as 100 parts by mass, and mol % refers to a value when the total number of moles of the monomers used is taken as 100 mol %.

[0223]

[0224] Synthesis Example 1 Synthesis of Polymer (A-1) Monomer (M-1), monomer (M-5), monomer (M-9), and monomer (M-14) were dissolved in 1-methoxy-2-propanol (200 parts by mass) to a molar ratio of 70 / 10 / 10 / 10 (mol %), and AIBN (10 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, and the polymerization reaction 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 methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with methanol, filtered, and dissolved in 1-methoxy-2-propanol (300 parts by mass). Methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were then added, and a hydrolysis reaction was carried out at 70°C for 6 hours with stirring. After completion of the reaction, the residual solvent was distilled off, and the resulting solid was dissolved in acetone (100 parts by mass) and added dropwise to hexane (500 parts by mass) to coagulate the polymer. The resulting solid was filtered and dried at 50°C for 13 hours to obtain a white powdery polymer (A-1) (yield: 80%). The Mw of the polymer (A-1) was 3,500, and the Mw / Mn was 1.32. １３ As a result of C-NMR analysis, the content ratios of the structural units derived from (M-1), (M-5), (M-9) and (M-14) were 70.2 mol%, 11.0 mol%, 9.8 mol% and 9.0 mol%, respectively. １３ C-NMR measurement confirmed that the peaks of the carbonyl groups of the acetyl groups had disappeared, and substantially all of the alkali-dissociable groups had been hydrolyzed to phenolic hydroxyl groups.

[0225] [Synthesis Examples 2 to 9] (Synthesis of Polymers (A-2) to (A-9)) Polymers (A-2) to (A-9) were synthesized in the same manner as in Synthesis Example 1, except that the types and blending ratios of monomers shown in Table 1 below were used. Note that the monomer that gives the structural unit (I) in the polymers is１３ C-NMR analysis confirmed that the peaks of the carbonyl groups of the acetyl groups had disappeared, indicating that substantially all of the alkali-dissociable groups had been hydrolyzed to phenolic hydroxyl groups. The content (mol %) of each structural unit and physical properties (Mw and Mw / Mn) of the resulting polymer are also shown in Table 1 below. In Table 1 below, "-" indicates that the corresponding component was not used (the same applies to the following tables).

[0226]

[0227] <Synthesis of Acid Diffusion Controller> [Synthesis Example C1] (Synthesis of Compound (C-1)) Compound (C-1) was synthesized according to the following synthesis scheme.

[0228]

[0229] A reaction vessel was charged with 20.0 mmol of compound (C-1-1), 20.0 mmol of sodium bicarbonate, and 20.0 mmol of tetrabutylammonium chloride, and a mixture of water and dichloromethane (1:3 (mass ratio)) was added to prepare a 0.5 M solution. After vigorously stirring at room temperature for 3 hours, dichloromethane was added for extraction, and the organic layer was separated. The resulting organic layer was dried over sodium sulfate, and the solvent was then distilled off, yielding compound (C-1) represented by formula (C-1) in good yield.

[0230] [Examples C2 to C15] (Synthesis of Compounds (C-2) to (C-15)) Compounds represented by the following formulas (C-2) to (C-15) were synthesized in the same manner as in Synthesis Example C1, except that the raw materials and precursors were appropriately changed.

[0231]

[0232] The following compounds were used as components other than the components synthesized above.

[0233] [Acid diffusion controllers other than acid diffusion controllers (C-1) to (C-15)] cc-1 to cc-8: Compounds represented by the following formulas (cc-1) to (cc-8) (hereinafter, the compounds represented by formulas (cc-1) to (cc-8) may be referred to as "compound (cc-1)" to "compound (cc-8)", respectively).

[0234]

[0235] [Radiation-sensitive acid generators (B-1) to (B-8)] B-1 to B-8: Compounds represented by the following formulas (B-1) to (B-8) (hereinafter, the compounds represented by formulas (B-1) to (B-8) may be referred to as "compound (B-1)" to "compound (B-8)", respectively).

[0236]

[0237] [Crosslinking agent (Q)] Q-1 to Q-7: Compounds represented by the following formulas (Q-1) to (Q-7) (hereinafter, compounds (Q-1) to (Q-7) may be referred to as "compound (Q-1)" to "compound (Q-7)," respectively).

[0238]

[0239] [Other Additives (D)] D-1 to D-5: Compounds represented by the following formulas (D-1) to (D-3) and additive compounds (D-4) to (D-5) (hereinafter, compounds (D-1) to (D-5) may be referred to as "compound (D-1)" to "compound (D-5)," respectively).

[0240]

[0241] D-4: MEGAFACE EFS-321 (manufactured by DIC Corporation) (non-fluorine-based) D-5: BYK-399 (manufactured by BYK Japan Co., Ltd.) (non-silicone-based)

[0242] [Solvent (E)] E-1: Propylene glycol monomethyl ether acetate E-2: Propylene glycol monomethyl ether E-3: γ-butyrolactone E-4: Cyclohexanone

[0243] [Preparation of Negative Radiation-Sensitive Composition for KrF Exposure] [Example 1] 100 parts by mass of (A-1) as the polymer (A), 10.0 parts by mass of (B-1) as the radiation-sensitive acid generator (B), 1.0 part by mass of (C-1) as the acid diffusion controller (C), 5.0 parts by mass of (Q-1) as the crosslinking agent (Q), 0.10 parts by mass of (D-1) as the other additive (D), and 400 parts by mass of a mixed solvent of (E-1) / (E-2) as the solvent (E) were mixed and filtered through a membrane filter having a pore size of 0.2 μm, to prepare a radiation-sensitive composition (J-1).

[0244] [Examples 2 to 48 and Comparative Examples 1 to 8] Radiation-sensitive compositions (J-2) to (J-48) and (CJ-1) to (CJ-8) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Tables 2-1 and 2-2 below were used.

[0245]

[0246]

[0247] <Formation of Resist Pattern Using Negative Radiation-Sensitive Composition for KrF Exposure> The negative radiation-sensitive composition for KrF exposure prepared above was applied to a 12-inch silicon wafer that had been treated with hexamethyldisilazane using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT8"), and prebaked at 130°C for 60 seconds. The wafer was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 3.5 μm. Next, this resist film was exposed to light using a KrF excimer laser scanner (ASML's "PAS5500 / 850C wavelength 248 nm") under optical conditions of NA = 0.68 and σ = 0.60 through a mask pattern with 400 nm holes and an 800 nm pitch. After exposure, the wafer was subjected to post-exposure bake (PEB) at 130°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 further dried to form a negative resist pattern (400 nm holes, 800 nm pitch).

[0248] <Evaluation> The resist patterns formed using the negative radiation-sensitive compositions for KrF exposure were evaluated for sensitivity, CDU, pattern circularity, pattern rectangularity, exposure latitude, and depth of focus according to the methods described below. A scanning electron microscope (CG-5000 manufactured by Hitachi High-Technologies Corporation) was used to measure the resist patterns. The results are shown in Tables 3-1 and 3-2 below.

[0249] [Sensitivity] In forming a resist pattern using the negative radiation-sensitive composition for KrF exposure, the exposure dose required to form a 400 nm hole at an 800 nm pitch was defined as the optimum exposure dose, and this optimum exposure dose was determined as the sensitivity (mJ / cm ２ The sensitivity was 50 mJ / cm ２ The following cases are considered "good" and 50mJ / cm ２ If it exceeded this, it was rated as "poor".

[0250] [CDU] A total of 1,800 resist patterns with 400 nm holes and an 800 nm pitch were measured at arbitrary points from the top of the pattern using the scanning electron microscope. The dimensional variation (3σ) was determined and used as the CDU (nm). The smaller the CDU value, the smaller the variation in hole diameter over a long period, indicating better results. CDU was evaluated as "good" when it was 6.0 nm or less, and "poor" when it exceeded 6.0 nm.

[0251] [Pattern circularity] The 400 nm holes and 800 nm pitch contact holes formed by irradiating with the optimum exposure dose obtained in the sensitivity evaluation were observed in plan view using the scanning electron microscope described above, and their vertical and horizontal sizes were measured. If the ratio of the vertical size to the horizontal size was 0.90 or more and 1.10 or less, the pattern was evaluated as "A" (good), and if it was less than 0.90 or more than 1.10, the pattern was evaluated as "B" (poor).

[0252] [Pattern Rectangularity] The 400 nm holes and 800 nm pitch contact holes formed by irradiating with the optimum exposure dose obtained in the sensitivity evaluation were observed using the scanning electron microscope described above, and the cross-sectional shape of the contact hole pattern was evaluated. The rectangularity of the resist pattern was evaluated as "A" (very good) if the ratio of the bottom side length to the top side length in the cross-sectional shape of the hole portion was 1 or more and 1.05 or less, "B" (good) if it was more than 1.05 and 1.10 or less, and "C" (poor) if it was more than 1.10.

[0253] [EL (Exposure Latitude)] In the range of exposure amounts including the above-mentioned optimum exposure amount, the exposure amount is set to 1 mJ / cm ２ Resist patterns were formed at different exposure doses, and the diameters of the holes were measured using the scanning electron microscope. From the relationship between the resulting diameter and exposure dose, the exposure dose E(440) at which the diameter was 440 nm and the exposure dose E(360) at which the diameter was 360 nm were determined, and the exposure latitude (%) was calculated using the formula: exposure latitude (EL) = (E(360) - E(440)) x 100 / (optimum exposure dose). The larger the exposure latitude value, the smaller the fluctuation in the dimensions of the resulting pattern when the exposure dose fluctuates, thereby increasing the yield during device fabrication. EL was evaluated as "good" when it was 10% or more, and as "poor" when it was below 10%.

[0254] [Depth of Focus] In the resist pattern resolved at the optimum exposure dose determined in the above sensitivity evaluation, the dimensions were observed when the focus was changed in the depth direction, and the margin in the depth direction where the pattern dimensions were 90% to 110% of the standard without any bridges or residues was measured, and this measured value was taken as the depth of focus (nm). The larger the value of the depth of focus, the better. A depth of focus of 200 nm or more can be evaluated as "good," and a depth of focus of less than 200 nm can be evaluated as "poor."

[0255]

[0256]

[0257] As is clear from the results in Tables 3-1 and 3-2, when the radiation-sensitive compositions of the Examples were used for KrF negative exposure, the sensitivity, CDU, pattern circularity, pattern rectangularity, exposure latitude, and depth of focus were good, whereas the Comparative Examples were inferior in each property to the Examples. Therefore, when the radiation-sensitive compositions of the Examples are used for KrF negative exposure, resist patterns with optimal sensitivity and excellent roughness performance, pattern shape, and yield can be formed.

[0258] The radiation-sensitive composition, pattern forming method, and compound described above can form a resist pattern that has good sensitivity to exposure light and is excellent in CDU, pattern circularity, pattern rectangularity, exposure latitude, and depth of focus. Therefore, these can be suitably used in processing processes for semiconductor devices, which are expected to become even more miniaturized in the future.

Claims

1. A radiation-sensitive composition comprising: a polymer (A) containing a structural unit (I) having a phenolic hydroxyl group; a compound (C) represented by the following formula (1); a crosslinking agent (Q); and a solvent (E): (In formula (1), R １ is a monovalent organic group having 1 to 40 carbon atoms (excluding groups containing aromatic hydrocarbons). ２１ and R ２２ are each independently a monovalent organic group having 1 to 40 carbon atoms. ２３ and R ２４ are each independently a monovalent organic group having 1 to 40 carbon atoms, or R ２３ and R ２４ are bonded together with the nitrogen atom to which they are attached, forming a ring structure having 3 to 10 ring members.

2. The radiation-sensitive composition according to claim 1, wherein the crosslinking agent (Q) comprises at least one compound selected from the group consisting of a compound (Q1) represented by the following formula (2) and a compound (Q2) represented by the following formula (3): (In formula (2), R ３１ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ３１ is *-R ３３ -OR ３４ (R ３３ is a divalent hydrocarbon group having 1 to 10 carbon atoms. ３４ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * represents a bond to the nitrogen atom. ３２ are each independently a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms. (In formula (3), R ４ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ４ is *-R ４１ -OR ４２ (R ４１ is a divalent hydrocarbon group having 1 to 10 carbon atoms. ４２ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * represents a bond to the nitrogen atom.

3. In the above formula (1), R ２１ , R ２２ , R ２３ , and R ２４ and each independently represent a monovalent chain hydrocarbon group having 2 to 10 carbon atoms.

4. The radiation-sensitive composition according to claim 1, wherein the polymer (A) contains a structural unit derived from unsubstituted styrene.

5. The radiation-sensitive composition according to claim 1, wherein the crosslinking agent (Q) comprises at least one compound selected from the group consisting of a compound (Q1-1) represented by the following formula (2-1) and a compound (Q2-1) represented by the following formula (3-1): (In formula (2-1), R ３２ are each independently a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms. ３３ are each independently a divalent hydrocarbon group having 1 to 10 carbon atoms. ３４ are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms. (In formula (3-1), R ４１ are each independently a divalent hydrocarbon group having 1 to 10 carbon atoms. ４２ are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms.

6. The radiation-sensitive composition according to claim 1, wherein the structural unit (I) is represented by the following formula (4-1): (In formula (4-1), R Ａ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. n1 is an integer from 1 to 5. m1 is an integer from 0 to 4, provided that m1+n1 is 5 or less. X is a halogen atom, a cyano group, a nitro group, an alkyl group, an alkoxy group, a carboxy group, a fluorinated alkyl group, an alkoxycarbonyl group, an acyl group, or an acyloxy group. When there are multiple Xs, the multiple Xs may be the same or different.

7. The radiation-sensitive composition according to claim 1, wherein the content of the compound (C) is 0.05 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the polymer (A).

8. The radiation-sensitive composition according to claim 1, wherein the content of the crosslinking agent (Q) is 0.5 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the polymer (A).

9. The radiation-sensitive composition according to claim 1, further comprising a radiation-sensitive acid generator (B) that generates an acid upon exposure.

10. The radiation-sensitive composition according to claim 1, which is used for forming a negative pattern.

11. A pattern forming method comprising the steps of: applying the radiation-sensitive composition according to any one of claims 1 to 10 directly or indirectly to a substrate to form a resist film; exposing the resist film; and developing the exposed resist film.

12. The pattern forming method according to claim 11, wherein the exposure is carried out with a KrF excimer laser.

13. A compound represented by the following formula (1-1): (In formula (1-1), R ２１１ is a monovalent chain organic group having 6 to 8 carbon atoms. ２２１ , R ２３１ and R ２４１ are each independently a monovalent chain hydrocarbon group having 2 to 8 carbon atoms. - is an anion represented by the following formula (1-1-a), (1-1-b), (1-1-c), or (1-1-d). (In formulas (1-1-a), (1-1-b), (1-1-c), and (1-1-d), W ａ is a substituted or unsubstituted alicyclic hydrocarbon group having 3 to 20 carbon atoms. ｂ is an organic group having 3 to 20 carbon atoms. ｃ and W ｄ are each independently an organic group having 1 to 20 carbon atoms. ａ , W ｂ , W ｃ and W ｄ does not contain aromatic hydrocarbon groups.

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