Radiation-sensitive resin composition, and pattern forming method

Abstract

To provide a radiation-sensitive resin composition and a pattern forming method capable of exhibiting defect-suppression performance, sensitivity, and CDU performance at a sufficient level.SOLUTION: A radiation-sensitive resin composition includes a radiation-sensitive acid generating resin including a structural unit having a radiation-sensitive acid generating structure, and a structural unit in which a tertiary hydrocarbon forms a cyclic structure, and a solvent. The solvent contains at least propylene glycol monomethyl ether and alkyl lactate, and a content of propylene glycol monomethyl ether acetate in the solvent is 5 mass% or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a radiation-sensitive resin composition and a patterning method.

Background Art

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

[0003] In the above photolithography technology, radiation with a short wavelength such as an ArF excimer laser is used, or this radiation is combined with a liquid immersion exposure method (liquid immersion lithography) to promote pattern miniaturization. As a next-generation technology, utilization of radiation with an even shorter wavelength such as an electron beam, X-ray, and EUV (extreme ultraviolet ray) is being considered, and a resist material containing an acid generator having a benzene ring with enhanced absorption efficiency of such radiation is also being studied (Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Among such efforts towards next-generation technologies, resist performances equivalent to or better than those of the conventional ones are required in terms of defect suppression of patterns, sensitivity, critical dimension uniformity (CDU) performance, and the like.

[0006] An object of the present invention is to provide a radiation-sensitive resin composition and a patterning method capable of exhibiting sufficient levels of defect suppression, sensitivity, and CDU performance.

Means for Solving the Problems

[0007] As a result of intensive studies to solve this problem, the present inventors have found that the above object can be achieved by adopting the following configuration, and have completed the present invention.

[0008] In one embodiment of the present invention (hereinafter, also referred to as "the first embodiment" for convenience), a radiation-sensitive acid generator, a resin containing a structural unit represented by the following formula (1) (hereinafter, also referred to as "structural unit A"), a solvent and relates to a radiation-sensitive resin composition in which the solvent contains at least propylene glycol monomethyl ether and alkyl lactate, and the content of propylene glycol monomethyl ether acetate in the solvent is 5% by mass or less.

Chemical formula

[0009] In another embodiment of the present invention (hereinafter, also referred to as "the second embodiment" for convenience), a radiation-sensitive acid-generating resin containing a structural unit having a radiation-sensitive acid-generating structure and a structural unit represented by the following formula (1), a solvent and The present invention relates to a radiation-sensitive resin composition in which the solvent contains at least propylene glycol monomethyl ether and alkyl lactate, and the content of propylene glycol monomethyl ether acetate in the solvent is 5% by mass or less. [Chemical formula] (In the above formula (1), R T is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R X is a monovalent hydrocarbon group having 1 to 20 carbon atoms. Cy represents an alicyclic structure having 3 to 20 ring members formed together with the carbon atom to which it is bonded.)

[0010] In the radiation-sensitive resin composition according to any of the above embodiments, as the solvent, it contains at least propylene glycol monomethyl ether and alkyl lactate, and the content of propylene glycol monomethyl ether acetate in the solvent is 5% by mass or less. Therefore, excellent defect suppression performance can be exhibited. Although the reason for this is not clear, it is presumed as follows. The present inventors considered that pattern defects are caused by the solvent that penetrates into the resist film during solvent removal acting on the surrounding resist film. The hydroxy groups of propylene glycol monomethyl ether and alkyl lactate in the resist film enhance the hydrophilicity and suppress the penetration of the solvent into the resist film. Also, by reducing the content of more hydrophobic propylene glycol monomethyl ether acetate, the penetration of the solvent into the resist film is suppressed, and it is presumed that defect suppression performance is exhibited. In addition, the acid dissociable group of structural unit A in the resin or the radiation-sensitive acid-generating resin has high acid dissociation efficiency upon exposure, so the contrast between the exposed part and the unexposed part is increased, and excellent pattern formability is exhibited. It is presumed that the above resist performance can be exhibited by these combined actions.

[0011] The present invention further provides another embodiment (hereinafter, also referred to as "the third embodiment" for convenience). A step of forming a resist film by applying the above radiation-sensitive resin composition directly or indirectly on a substrate; A step of exposing the above resist film; A step of developing the exposed resist film with a developer and relates to a pattern forming method including the above steps.

[0012] In the said pattern forming method, since the above radiation-sensitive resin composition excellent in defect suppressibility, sensitivity and CDU performance is used, a high-quality resist pattern can be efficiently formed.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.

[0014] [First Embodiment] 《Radiation-Sensitive Resin Composition》 The radiation-sensitive resin composition according to the first embodiment (hereinafter, also simply referred to as "composition") contains a radiation-sensitive acid generator, a resin and a solvent. The resin according to the first embodiment or the radiation-sensitive acid-generating resin according to the second embodiment described later, which are the main components of the radiation-sensitive resin composition, are also collectively referred to as the base resin. The above composition may contain other optional components as long as the effects of the present invention are not impaired. By containing a predetermined solvent and a base resin, the radiation-sensitive resin composition can impart high-level defect suppressibility, sensitivity and CDU performance to the resulting resist film.

[0015] <Radiation-Sensitive Acid Generator> A radiation-sensitive acid generator is a component that generates an acid upon exposure. The acid generated upon exposure is considered to perform two functions in the radiation-sensitive resin composition depending on the strength of the acid. As the first function, there is a function in which the acid generated upon exposure dissociates the acid-dissociable group that the structural unit A in the resin has, and generates a carboxy group or the like. The radiation-sensitive acid generator having this first function is referred to as a radiation-sensitive acid generator (I). As the second function, under the pattern formation conditions using the above-described radiation-sensitive resin composition, the acid-dissociable group that the structural unit A of the resin has is not substantially dissociated, and the diffusion of the acid generated from the above-described radiation-sensitive acid generator (I) in the unexposed portion is suppressed. The radiation-sensitive acid generator having this second function is referred to as a radiation-sensitive acid generator (II). It can be said that the acid generated from the radiation-sensitive acid generator (II) is a relatively weaker acid (an acid having a larger pKa) than the acid generated from the radiation-sensitive acid generator (I). Whether the radiation-sensitive acid generator functions as the radiation-sensitive acid generator (I) or the radiation-sensitive acid generator (II) is determined by the energy required for the acid-dissociable group that the structural unit A of the resin has to dissociate, the acidity of the acid generated from the radiation-sensitive acid generator, and the like. As the form of inclusion of the radiation-sensitive acid generator in the radiation-sensitive resin composition, it may be present as a compound alone (released from the polymer), incorporated as a part of the polymer, or both of these forms. Regarding the form in which the radiation-sensitive acid generator is incorporated as a part of the polymer, it will be described later as a radiation-sensitive acid resin.

[0016] When the radiation-sensitive resin composition contains the above-described radiation-sensitive acid generator (I), the polarity of the resin in the exposed portion increases, and the resin in the exposed portion becomes soluble in the developer in the case of alkali aqueous solution development, while it becomes hardly soluble in the developer in the case of organic solvent development.

[0017] By containing the above-described 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.

[0018] Examples of the radiation-sensitive acid generator include onium salts, sulfonimide compounds, halogen-containing compounds, diazoketone compounds, etc. Examples of the onium salt include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, etc. Among these, sulfonium salts and iodonium salts are preferred.

[0019] 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).

[0020] The radiation-sensitive acid generator preferably contains one or more onium salts each containing an organic acid anion moiety and an onium cation moiety.

[0021] The organic acid anion portion preferably has at least one anion selected from the group consisting of a sulfonate anion, a carboxylate anion, and a sulfonimide anion, corresponding to the acid generated by exposure.

[0022] The onium cation moiety is preferably at least one selected from the group consisting of sulfonium cations and iodonium cations corresponding to the above-mentioned sulfonium salts and iodonium salts.

[0023] The above-mentioned onium salt is a radiation-sensitive strong acid generator containing the above-mentioned organic acid anion moiety and the above-mentioned onium cation moiety, and an acid diffusion control agent containing the above-mentioned organic acid anion moiety and the above-mentioned onium cation moiety and generating an acid having a higher pKa than the acid generated from the above-mentioned radiation-sensitive strong acid generator upon irradiation with radiation is preferably at least one selected from the group consisting of.

[0024] The radiation-sensitive acid generator (I) corresponds to a radiation-sensitive strong acid generator, and the radiation-sensitive acid generator (II) corresponds to an acid diffusion control agent. By appropriately designing the structures of the organic acid anion moiety and the onium cation moiety, the radiation-sensitive acid generator can function as both a radiation-sensitive strong acid generator and an acid diffusion control agent.

[0025] (Radiation-sensitive strong acid generator) The onium salt as the above-mentioned radiation-sensitive strong acid generator is preferably represented by the following formula (pd-1) or the following formula (pd-2).

[0026]

Chemical formula

[0027] In formulas (pd-1) and (pd-2), L pd1 is a single bond, an ether bond or an ester bond, or an alkylene group having 1 to 6 carbon atoms which may contain an ether bond or an ester bond. The alkylene group may be linear, branched or cyclic.

[0028] R pd1is a hydroxy group, a carboxy group, a fluorine atom, a chlorine atom, a bromine atom, an amino group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkoxycarbonyl group having 2 to 10 carbon atoms, an acyloxy group having 2 to 20 carbon atoms, an alkylsulfonyloxy group having 1 to 20 carbon atoms, -NR pd6 -C(=O)-R pd7 or -NR pd6 -C(=O)-O-R pd7 wherein. These alkyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms or fluorine atoms may be substituted with a chlorine atom, a bromine atom, a hydroxy group, an amino group or an alkoxy group having 1 to 10 carbon atoms. R pd6 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may contain a halogen atom, a hydroxy group, an alkoxy group having 1 to 6 carbon atoms, an acyl group having 2 to 6 carbon atoms or an acyloxy group having 2 to 6 carbon atoms. R pd7 is an alkyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and these groups may contain a halogen atom, a hydroxy group, an alkoxy group having 1 to 6 carbon atoms, an acyl group having 2 to 6 carbon atoms, or an acyloxy group having 2 to 6 carbon atoms. The alkyl group, alkoxy group, alkoxycarbonyl group, acyloxy group, acyl group and alkenyl group may be linear, branched or cyclic.

[0029] Among these, as R pd1 , a hydroxy group, -NR pd6 -C(=O)-R pd7 , a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group and the like are preferable.

[0030] p pd is an integer satisfying 0 ≦ p pd ≦ 3. L pd2 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms when p pd is 0. When p pd is 1, it is a single bond or a divalent linking group having 1 to 20 carbon atoms, and when p pdWhen it is 2 or 3, it is a trivalent or tetravalent linking group having 1 to 20 carbon atoms, and the linking group may contain an oxygen atom, a sulfur atom or a nitrogen atom. Examples of the monovalent organic group when p is 0 include the same groups as those listed as the hydrocarbon groups constituting the fluorinated hydrocarbon group, and in addition, a monovalent group in which a part of the methylene groups constituting the hydrocarbon group is substituted with an ether group or an ester group.

[0031] R fpd1 ~R fpd4 are each independently a hydrogen atom, a fluorine atom or a trifluoromethyl group, and at least one of these is a fluorine atom or a trifluoromethyl group. In particular, it is preferable that both R fpd3 and R fpd4 are fluorine atoms.

[0032] R pd2 、R pd3 、R pd4 、R pd5 and R pd6 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom. R pd2 、R pd3 and R pd4 may contain one or more fluorine atoms, and R pd5 and R pd6 may contain one or more fluorine atoms. Further, any two of R pd2 、R pd3 and R pd4 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. The monovalent hydrocarbon group may be linear, branched or cyclic, and specific examples thereof include the same groups as those listed as the hydrocarbon groups constituting the fluorinated hydrocarbon group. Further, some or all of the hydrogen atoms of these groups may be substituted with a hydroxy group, a carboxy group, a halogen atom, a cyano group, an amide group, a nitro group, a mercapto group, a sultone group, a sulfone group or a sulfonium salt-containing group.

[0033] q pd and r pd are such that 0 ≦ q pd ≦ 5, 0 ≦ rpd ≤ 3, and 0 ≤ q pd + r pd ≤ 5, where q is an integer satisfying this condition. q pd is preferably an integer satisfying 1 ≤ q pd ≤ 3, more preferably 2 or 3. r pd is preferably an integer satisfying 0 ≤ r pd ≤ 2.

[0034] Examples of the organic acid anion moiety of the radiation-sensitive strong acid generator represented by the above formulas (pd-1) and (pd-2) include, but are not limited to, those shown below. The organic acid anion moiety preferably contains an iodine-substituted aromatic ring structure. Note that although all of the following are organic acid anion moieties having an iodine-substituted aromatic ring structure, as an organic acid anion moiety not having an iodine-substituted aromatic ring structure, a structure in which the iodine atom in the following formula is substituted with an atom or group other than an iodine atom such as a hydrogen atom or another substituent can be preferably adopted.

[0035]

Chemical formula

[0036]

Chemical formula

[0037]

Chemical formula

[0038]

Chemical formula

[0039]

Chemical formula

[0040]

Chemical formula

[0041]

Chem.

[0042]

Chem.

[0043]

Chem.

[0044]

Chem.

[0045]

Chem.

[0046]

Chem.

[0047]

Chem.

[0048]

Chem.

[0049]

Chem.

[0050]

Chem.

[0051]

Chem.

[0052] [ka]

[0053] [ka]

[0054] [ka]

[0055] [ka]

[0056] [ka]

[0057] [ka]

[0058] Specific examples of the onium cation moiety in the radiation-sensitive strong acid generator represented by formula (pd-1) above include the following: The onium cation moiety preferably contains a fluorine-substituted aromatic ring structure. Note that all of the following are sulfonium cations containing a fluorine-substituted aromatic ring structure, but as an onium cation moiety that does not contain an aromatic ring structure having a fluorine atom, a structure in which the fluorine atom or CF3 in the following formula is substituted with an atom or group other than a fluorine atom, such as a hydrogen atom or other substituent, can be suitably used.

[0059] [ka]

[0060] [Chem.]

[0061] Specific examples of the onium cation moiety in the radiation-sensitive strong acid generator represented by the above formula (pd-2) include the following. The onium cation moiety preferably contains a fluorine-substituted aromatic ring structure. Note that although those shown below are all iodonium cations containing a fluorine-substituted aromatic ring structure, as the onium cation moiety that does not contain an aromatic ring structure having a fluorine atom, a structure in which the fluorine atom or CF3 in the following formula is substituted with an atom or group other than a hydrogen atom or a fluorine atom such as another substituent can be preferably employed.

[0062] [Chem.]

[0063] The radiation-sensitive acid generators represented by the above formulas (pd-1) and (pd-2) can also be synthesized by known methods, particularly by salt exchange reactions.

[0064] 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 is preferably 5 parts by mass, more preferably 10 parts by mass, and even more preferably 15 parts by mass with respect to 100 parts by mass of the base resin (the total amount when including at least one combination of the resin and the radiation-sensitive acid-generating resin described later). Also, the upper limit of the above content is preferably 50 parts by mass, more preferably 40 parts by mass, and even more preferably 30 parts by mass. Thereby, excellent sensitivity and CDU performance can be exhibited during resist pattern formation.

[0065] (Acid diffusion controller) The onium salt as the above acid diffusion controller is preferably represented by the following formula (ps-1) or the following formula (ps-2).

[0066]

Chem.

[0067] In formulas (ps-1) and (ps-2), R ps1 is a hydrogen atom, a hydroxy group, a fluorine atom, a chlorine atom, an amino group, a nitro group, a cyano group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an acyloxy group having 2 to 6 carbon atoms, an alkylsulfonyloxy group having 1 to 4 carbon atoms, -NR ps1A -C(=O)-R ps1B 、-NR ps1A -C(=O)-O-R ps1B wherein the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms, the acyloxy group having 2 to 6 carbon atoms, and the alkylsulfonyloxy group having 1 to 4 carbon atoms may be substituted with a halogen atom. R ps1A is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R ps1B is an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.

[0068] The alkyl group having 1 to 6 carbon atoms may be linear, branched, or cyclic. Specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a cyclopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a cyclobutyl group, an n-pentyl group, a cyclopentyl group, an n-hexyl group, a cyclohexyl group, and the like. Further, as the alkyl moiety of the alkoxy group having 1 to 6 carbon atoms, the acyloxy group having 2 to 7 carbon atoms, and the alkoxycarbonyl group having 2 to 7 carbon atoms, the same ones as the specific examples of the alkyl group described above can be mentioned. As the alkyl moiety of the alkylsulfonyloxy group having 1 to 4 carbon atoms, those having 1 to 4 carbon atoms among the specific examples of the alkyl group described above can be mentioned. The alkenyl group having 2 to 8 carbon atoms may be linear, branched, or cyclic. Specific examples thereof include a vinyl group, a 1-propenyl group, a 2-propenyl group, and the like. Among these, R ps1include a hydrogen atom, a fluorine atom, a chlorine atom, a hydroxy group, an amino group, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an acyloxy group having 2 to 4 carbon atoms, -NR ps1A -C(=O)-R ps1B 、-NR ps1A -C(=O)-O-R ps1B are preferred.

[0069] R ps2 、R ps3 、R ps4 、R ps5 and R ps6 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom. R ps2 、R ps3 and R ps4 contain one or more fluorine atoms, and R ps5 and R ps6 contain one or more fluorine atoms. Further, any two of R ps2 、R ps3 and R ps4 [[ID=…]] may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. The monovalent hydrocarbon group may be linear, branched or cyclic, and specific examples thereof include an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, and the like. Further, some or all of the hydrogen atoms of these groups may be substituted with a hydroxy group, a carboxy group, a halogen atom, a cyano group, an amide group, a nitro group, a mercapto group, a sultone group, a sulfone group or a sulfonium salt-containing group, and some of the carbon atoms of these groups may be substituted with an ether bond, an ester bond, a carbonyl group, a carbonate group or a sulfonic acid ester bond.

[0070] L ps1is a single bond or a divalent linking group having 1 to 20 carbon atoms. Examples of the divalent linking group include a group formed by combining an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a carboxy group, and a divalent hydrocarbon group. The divalent hydrocarbon group may be substituted with a halogen atom, a hydroxy group, or a carboxy group. Examples of the divalent hydrocarbon group include an alkylene group having 1 to 12 carbon atoms, a cycloalkylene group having 3 to 12 carbon atoms, or an arylene group having 6 to 10 carbon atoms.

[0071] m ps and n ps are integers satisfying 0 ≦ m ps ≦ 5, 0 ≦ n ps ≦ 3, and 0 ≦ m ps + n ps ≦ 5, but integers satisfying 1 ≦ m ps ≦ 3, 0 ≦ n ps ≦ 2 are preferred.

[0072] Examples of the organic acid anion moiety of the acid diffusion controller represented by the above formula (ps-1) or (ps-2) include, but are not limited to, those shown below. Note that all of the ones shown below are organic acid anion moieties having an iodine-substituted aromatic ring structure. As the organic acid anion moiety having no iodine-substituted aromatic ring structure, a structure in which the iodine atom in the following formula is substituted with an atom or group other than an iodine atom such as a hydrogen atom or another substituent can be preferably employed.

[0073]

Chemical formula

[0074]

Chemical formula

[0075]

Chemical formula

[0076] [Chem.]

[0077] [Chem.]

[0078] As the onium cation moiety in the acid diffusion control agent represented by the above formulas (ps-1) and (ps-2), the onium cation moiety in the radiation-sensitive strong acid generator can be preferably adopted.

[0079] The acid diffusion control agent represented by the above formulas (ps-1) and (ps-2) can also be synthesized by a known method, particularly by a salt exchange reaction.

[0080] These acid diffusion control agents may be used alone or in combination of two or more. The lower limit of the content ratio of the acid diffusion control agent is preferably 5% by mass, more preferably 10% by mass, and even more preferably 15% by mass with respect to 100 parts by mass of the content of the radiation-sensitive acid generator (the total of the content of the structural unit in 100 parts by mass of the radiation-sensitive acid generating resin when including the radiation-sensitive acid generating resin). Also, the upper limit of the above content ratio is preferably 100% by mass, more preferably 80% by mass, and even more preferably 60% by mass. Thereby, excellent sensitivity and CDU performance can be exhibited during resist pattern formation.

[0081] (Structure of other organic acid anion moieties) The radiation-sensitive acid generator (including both the radiation-sensitive strong acid generator and the acid diffusion control agent) may contain, together with or in place of the organic acid anion moiety of the radiation-sensitive strong acid generator represented by the above formulas (pd-1) and (pd-2) and the organic acid anion moiety of the acid diffusion control agent represented by the above formula (ps-1) or (ps-2), a structure represented by the following formula (bd1).

[0082] [Chem.]

[0083] In the above formula (bd1), R x1 ~R x4 each independently represents a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or a ring structure formed by combining two or more of these. R y1 ~R y2 each independently represents a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or a ring structure formed by combining with each other.

Chemical formula

[0084] R x1 ~R x4 、R y1 ~R y2 and R z1 ~R z4 The hydrocarbon groups in may each be an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a cyclic hydrocarbon group, or a chain hydrocarbon group. For example, R x1 ~R x4 、R y1 ~R y2 and R z1 ~R z4In the formula (I), examples of the hydrocarbon group which may have a substituent include a cyclic group which may have a substituent, a chain alkyl group which may have a substituent, and a chain alkenyl group which may have a substituent.

[0085] The cyclic group which may have a substituent is preferably a cyclic hydrocarbon group, and the cyclic hydrocarbon group may be an aromatic hydrocarbon group or an aliphatic hydrocarbon group. The aliphatic hydrocarbon group means a hydrocarbon group which does not have aromaticity. The aliphatic hydrocarbon group may be saturated or unsaturated, and is usually preferably saturated. Furthermore, R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4 The cyclic hydrocarbon group in may contain a heteroatom, such as a heterocyclic ring.

[0086] In the formula (bd1), R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4 At least one of the above has an acid anion structure, and the organic acid anion moiety as a whole forms an n-valent anion, where n is an integer of 1 or greater. By selecting the acid anion structure within the molecule, the organic acid anion moiety represented by formula (bd1) can function in the composition as a radiation-sensitive strong acid generator that generates an acid that acts on acid-dissociable groups in the base resin, or as an acid diffusion controller that traps the acid (controls the diffusion of the acid) generated from the radiation-sensitive strong acid generator upon exposure.

[0087] R x1 ~R x4 , R y1 ~R y2 and R z1 ~R z4Examples of the acid anion structure include those having a sulfonic acid anion structure, a carboxylic acid anion structure, an imide anion structure, a methide anion structure, a carbanion structure, a borate anion structure, a halogen anion structure, a phosphate anion structure, an antimonate anion structure, an arsenate anion structure, and the like. Among these, those having a sulfonic acid anion structure and those having a carboxylic acid anion structure are preferred.

[0088] In the organic anion moiety represented by the above formula (bd1), R x1 ~R x4 、R y1 ~R y2 and R z1 ~R z4 may each be the above acid anion structure. When two or more of R x1 ~R x4 are bonded to each other to form a ring structure, the carbon atom forming the ring structure or the hydrogen atom bonded to this carbon atom may be substituted with the above acid anion structure. When two or more of R y1 ~R y2 are bonded to each other to form a ring structure, the carbon atom forming the ring structure or the hydrogen atom bonded to this carbon atom may be substituted with the acid anion structure. When two or more of R z1 ~R z4 are bonded to each other to form a ring structure, the carbon atom forming the ring structure or the hydrogen atom bonded to this carbon atom may be substituted with the above acid anion structure.

[0089] The organic acid anion moiety preferably contains a partial structure represented by the following formula (b1) or (b2).

[0090]

Chemical formula

Chemical formula

[0091] Specific examples of the organic anion moiety represented by the above formula (bd1) include, but are not limited to, those shown below.

[0092]

Chemical formula

[0093]

Chemical formula

[0094] <Resin> The resin contains a structural unit A having an acid dissociable group. In addition to the structural unit A, the resin may contain a structural unit B having a phenolic hydroxyl group, a structural unit C containing a lactone structure, etc. Each structural unit will be described below.

[0095] (Structural unit A) The structural unit A is represented by the following formula (1).

Chemical formula

[0096] R X Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by include a chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, etc.

[0097] Examples of the chain hydrocarbon group having 1 to 10 carbon atoms include a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, or a linear or branched unsaturated hydrocarbon group having 1 to 10 carbon atoms.

[0098] Examples of the alicyclic hydrocarbon group having 3 to 20 carbon atoms include a monocyclic or polycyclic saturated hydrocarbon group, or a monocyclic or polycyclic unsaturated hydrocarbon group. Preferred examples of the monocyclic saturated hydrocarbon group include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Preferred examples of the polycyclic cycloalkyl group include a bridged alicyclic hydrocarbon group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, and a tetracyclododecyl group. The bridged alicyclic hydrocarbon group means a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms among the carbon atoms constituting the alicyclic ring are bonded by a bonding chain containing one or more carbon atoms.

[0099] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms 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.

[0100] R X is preferably a linear or branched saturated hydrocarbon group having 1 to 5 carbon atoms, or an alicyclic hydrocarbon group having 3 to 12 carbon atoms.

[0101] The alicyclic structure having 3 to 20 ring members in Cy is not particularly limited as long as it has an alicyclic structure, and may have a monocyclic, bicyclic, tricyclic, tetracyclic or more polycyclic structure, and may be any of a bridged ring structure, a spiro ring structure, a ring assembly structure in which a plurality of rings are directly bonded by a single bond or a double bond, or a combination thereof. Among them, it is preferably a monocyclic, bicyclic, tricyclic, or tetracyclic bridged ring structure, and cyclopentane, cyclohexane, norbornane, adamantane, tricyclo[5.2.1.0 2,6 decane, tetracyclo[4.4.0.1 2,5 .1 7,10It is more preferable that it is any ring structure of dodecane, perhydronaphthalene or perhydroanthracene or a derivative thereof.

[0102] The structural unit A is preferably represented by, for example, the following formulas (A-1) to (A-8). [Chemical formula]

[0103] In the above formulas (A-1) to (A-8), R T and R X have the same meaning as in the above formula (1). Among them, the structural unit A is preferably represented by, for example, the above formulas (A-1), (A-4), (A-5), (A-6), (A-8).

[0104] In the resin, the lower limit of the content ratio of the structural unit A (the total when there are multiple types of structural unit A) is preferably 20 mol%, more preferably 30 mol%, and even more preferably 40 mol% with respect to all the structural units constituting the resin. The upper limit of the above content ratio is preferably 80 mol%, more preferably 75 mol%, and even more preferably 65 mol%. By setting the content ratio of the structural unit A within the above range, the above radiation-sensitive resin composition can further improve the sensitivity and CDU performance.

[0105] (Structural unit B) Structural unit B is a structural unit having a phenolic hydroxyl group or a structural unit that provides a phenolic hydroxyl group by the action of an acid. In the present invention, a phenolic hydroxyl group generated by deprotection by the action of an acid generated by exposure is also included as the phenolic hydroxyl group of structural unit B. By including structural unit B in the resin, the solubility in the developer can be adjusted more appropriately, and as a result, the sensitivity and the like of the above-described radiation-sensitive resin composition can be further improved. Further, when KrF excimer laser light, EUV, electron beam, etc. are used as the radiation irradiated in the exposure step in the resist pattern forming method, structural unit B contributes to the improvement of etching resistance and the improvement of the difference in developer solubility (dissolution contrast) between the exposed portion and the unexposed portion. In particular, it can be suitably applied to pattern formation using exposure with radiation having a wavelength of 50 nm or less such as an electron beam or EUV. Structural unit B is preferably represented by the following formula (B).

[0106] [Chemical formula] (In the above formula (B), R α is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. L CA is a single bond, -COO- * or -O-. * is a bond on the aromatic ring side. R 101 is a hydrogen atom or a protecting group that is deprotected by the action of an acid. When there are a plurality of R 101 , the plurality of R 101 are the same as or different from each other. R 102 is a cyano group, a nitro group, an alkyl group, a fluorinated alkyl group, an alkoxycarbonyloxy group, an acyl group or an acyloxy group. n d3 is an integer of 0 to 2, and m d3 is an integer of 1 to 8, and m d4 is an integer of 0 to 8. However, 1 ≦ m d3 + m d4 ≦ 2n d3 + 5 is satisfied.)

[0107] The above R α is preferably a hydrogen atom or a methyl group from the viewpoint of the copolymerizability of the monomer that provides the structural unit B.

[0108] L CA is preferably a single bond or -COO- * is preferred.

[0109] The above R 101 Examples of the protecting group that is deprotected by the action of the acid represented by include groups represented by the following formulas (AL-1) to (AL-3). [Chemical formula]

[0110] In the above formulas (AL-1) and (AL-2), R M1 and R M2 are monovalent hydrocarbon groups, which may contain heteroatoms such as an oxygen atom, a sulfur atom, a nitrogen atom, and a fluorine atom. The monovalent hydrocarbon group may be linear, branched, or cyclic, and is preferably an alkyl group having 1 to 40 carbon atoms, more preferably an alkyl group having 1 to 20 carbon atoms. In formula (AL-1), a is an integer of 0 to 10, preferably an integer of 1 to 5. In the above formulas (AL-1) to (AL-3), * is a bond to another part.

[0111] In the above formula (AL-2), R M3 and R M4 are each independently a hydrogen atom or a monovalent hydrocarbon group, which may contain heteroatoms such as an oxygen atom, a sulfur atom, a nitrogen atom, and a fluorine atom. The monovalent hydrocarbon group may be linear, branched, or cyclic, and is preferably an alkyl group having 1 to 20 carbon atoms. Also, R M2 , R M3 and R M4Any two of them may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atoms to which they are bonded or carbon atoms and oxygen atoms. As the above ring, a ring having 4 to 16 carbon atoms is preferable, and an alicyclic ring is particularly preferable.

[0112] In the above formula (AL-3), R M5 , R M6 and R M7 are each independently a monovalent hydrocarbon group, and may contain heteroatoms such as an oxygen atom, a sulfur atom, a nitrogen atom, and a fluorine atom. As the above monovalent hydrocarbon group, any of linear, branched, and cyclic forms may be used, and an alkyl group having 1 to 20 carbon atoms is preferable. Also, any two of R M5 , R M6 and R M7 may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atoms to which they are bonded. As the above ring, a ring having 5 to 16 carbon atoms is preferable, and an alicyclic ring is particularly preferable.

[0113] Among these, as the protecting group that is deprotected by the action of an acid, the group represented by the above formula (AL-3) is preferable.

[0114] R 102 Examples of the alkyl group in include linear or branched alkyl groups having 1 to 8 carbon atoms such as a methyl group, an ethyl group, and a propyl group. Examples of the fluorinated alkyl group include linear or branched fluorinated alkyl groups having 1 to 8 carbon atoms such as a trifluoromethyl group and a pentafluoroethyl group. Examples of the alkoxycarbonyloxy group include chain or alicyclic alkoxycarbonyloxy groups having 2 to 16 carbon atoms such as a methoxycarbonyloxy group, a butoxycarbonyloxy group, and an adamantylmethyloxycarbonyloxy group. Examples of the acyl group 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.

[0115] The above n d3 is more preferably 0 or 1, and still more preferably 0.

[0116] The above m d3 is preferably an integer of 1 to 3, and more preferably 1 or 2.

[0117] The above m d4 is preferably an integer of 0 to 3, and more preferably an integer of 0 to 2.

[0118] The above structural unit B is preferably a structural unit represented by the following formulas (B-1) to (B-10) (hereinafter, also referred to as "structural units (B-1) to structural units (B-10)").

[0119]

Chemical formula

[0120] In the above formulas (B-1) to (B-10), R α is the same as in the above formula (B).

[0121] Among these, the above structural units (B-1) to (B-4), (B-6) and (B-8) are preferable.

[0122] When the base resin contains the structural unit B, the lower limit of the content ratio of the structural unit B (when there are a plurality of types of structural unit B, the total) is preferably 10 mol%, more preferably 15 mol%, still more preferably 20 mol%, and particularly preferably 25 mol% with respect to all the structural units constituting the resin. The upper limit of the above content ratio is preferably 80 mol%, more preferably 70 mol%, still more preferably 60 mol%, and particularly preferably 55 mol%. By setting the content ratio of the structural unit B within the above range, the above radiation-sensitive resin composition can further improve sensitivity, CDU performance and resolution.

[0123] When polymerizing a monomer having a phenolic hydroxyl group such as hydroxystyrene, it is preferable to carry out the polymerization in a state where the phenolic hydroxyl group is protected by a protecting group such as an alkali-dissociable group, and then to carry out hydrolysis for deprotection to obtain the structural unit B.

[0124] (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. By further having the structural unit C, the base resin can adjust the solubility in the developer, and as a result, the radiation-sensitive resin composition can improve lithography performance such as resolution. In addition, the adhesion between the resist pattern formed from the base resin and the substrate can be improved.

[0125] Among these, as the structural unit C, a structural unit containing a lactone structure is preferable, a structural unit containing a norbornane lactone structure is more preferable, and a structural unit derived from norbornane lactone-yl (meth) acrylate is even more preferable.

[0126] When the base resin contains the structural unit C, the lower limit of the content ratio of the structural unit C is preferably 3 mol%, more preferably 8 mol%, and even more preferably 10 mol% with respect to all the structural units constituting the base resin. The upper limit of the above content ratio is preferably 40 mol%, more preferably 30 mol%, and even more preferably 20 mol%. By setting the content ratio of the structural unit C within the above range, the radiation-sensitive resin composition can further improve lithography performance such as resolution and the adhesion between the formed resist pattern and the substrate.

[0127] (Structural unit D) The base resin may optionally have other structural units in addition to the above structural units A to C. Examples of the other structural units include a structural unit D containing a polar group (however, those corresponding to structural units B and C are excluded). By further having the structural unit D, the base resin can adjust its solubility in a developer, and as a result, the lithography performance such as the resolution of the radiation-sensitive resin composition can be improved. Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a nitro group, a sulfonamide group, etc. Among these, a hydroxy group and a carboxy group are preferred, and a hydroxy group is more preferred.

[0128] Examples of the structural unit D include a structural unit represented by the following formula.

[0129] [Chemical formula]

[0130] In the above formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0131] When the base resin has the structural unit D, the lower limit of the content ratio of the structural unit D is preferably 1 mol%, more preferably 2 mol%, and still more preferably 3 mol% with respect to all the structural units constituting the base resin. Also, the upper limit of the above content ratio is preferably 30 mol%, more preferably 20 mol%, and still more preferably 15 mol%. By setting the content ratio of the structural unit D within the above range, the lithography performance such as the resolution of the radiation-sensitive resin composition can be further improved.

[0132] (Synthesis method of resin) The resin serving as the base resin can be synthesized, for example, by performing a polymerization reaction on monomers providing each structural unit in a suitable solvent using a known radical polymerization initiator or the like.

[0133] The molecular weight of the resin as the base resin is not particularly limited, but in terms of the polystyrene-equivalent weight average molecular weight (Mw) by gel permeation chromatography (GPC), 1,000 or more is preferable, 2,000 or more is more preferable, 3,000 or more is further preferable, and 4,000 or more is particularly preferable. Also, 50,000 or less is preferable, 30,000 or less is more preferable, 15,000 or less is further preferable, and 12,000 or less is particularly preferable. When the Mw of the resin is within the above range, the heat resistance and developability of the resist film are further improved.

[0134] The ratio (Mw / Mn) of the Mw of the resin as the base resin to the number average molecular weight (Mn) in terms of polystyrene 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.

[0135] The Mw and Mn of the resin in this specification are values measured using gel permeation chromatography (GPC) under the following conditions. GPC column: 2 columns of G2000HXL, 1 column of G3000HXL, 1 column of 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 substance: Monodisperse polystyrene

[0136] The content of the resin is preferably 70 mass% or more, more preferably 80 mass% or more, and further preferably 85 mass% or more based on the total solid content of the above radiation-sensitive resin composition.

[0137] <Other resin> The radiation-sensitive resin composition of this embodiment may contain, as another resin, a resin having a higher mass content of fluorine atoms than the above base resin (hereinafter, also referred to as "high-fluorine content resin"). When the radiation-sensitive resin composition contains a high-fluorine content resin, it can be unevenly distributed on the surface layer of the resist film with respect to the base resin. As a result, the state of the resist film surface and the component distribution in the resist film can be controlled to a desired state.

[0138] As the high-fluorine content resin, for example, it preferably has any one or more of structural units A to D in the above base resin as necessary, and has a structural unit represented by the following formula (E) (hereinafter, also referred to as "structural unit E").

Chemical formula

[0139] In the above formula (E), 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 linear hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0140] As the above R 13 from the viewpoint of the copolymerizability of the monomer that gives the structural unit E, a hydrogen atom and a methyl group are preferred, and a methyl group is more preferred.

[0141] As the above G L from the viewpoint of the copolymerizability of the monomer that gives the structural unit E, a single bond and -COO- are preferred, and -COO- is more preferred.

[0142] Examples of the monovalent fluorinated linear hydrocarbon group having 1 to 20 carbon atoms represented by the above R 14 include those in which some or all of the hydrogen atoms of a linear or branched alkyl group having 1 to 20 carbon atoms are substituted by fluorine atoms.

[0143] The above R 14 Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by 14 include those in which some or all of the hydrogen atoms of a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms are substituted by fluorine atoms.

[0144] The above R 14 is preferably a fluorinated chain hydrocarbon group, more preferably a fluorinated alkyl group, and even more preferably a 2,2,2-trifluoroethyl group, a 1,1,1,3,3,3-hexafluoropropyl group, a 5,5,5-trifluoro-1,1-diethylpentyl group, and a 1,1,1,2,2,3,3-heptafluoro-6-methylheptan-4-yl group.

[0145] When the high fluorine content resin has the structural unit E, the lower limit of the content ratio of the structural unit E is preferably 5 mol%, more preferably 10 mol%, and even more preferably 15 mol% with respect to all the structural units constituting the high fluorine content resin. Further, the upper limit of the above content ratio is preferably 100 mol%, more preferably 95 mol%, and even more preferably 90 mol%. By setting the content ratio of the structural unit E within the above range, the mass content ratio of fluorine atoms in the high fluorine content resin can be more appropriately adjusted, and the uneven distribution on the surface layer of the resist film can be further promoted.

[0146] In addition to the structural unit E, the high fluorine content resin may have a fluorine atom-containing structural unit represented by the following formula (f-1) (hereinafter also referred to as the structural unit F). By having the structural unit F, the high fluorine content resin has improved solubility in an alkaline developer and can suppress the occurrence of development defects. [Chemical formula]

[0147] The structural unit F is roughly classified into two cases: (x) having an alkali-soluble group and (y) having a group that dissociates by the action of an alkali to increase solubility in an alkali developer (hereinafter also simply referred to as an "alkali-dissociable group"). In common to both (x) and (y), in the above formula (f-1), R C is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R D is a single bond, an (s + 1)-valent hydrocarbon group having 1 to 20 carbon atoms, and the R of this hydrocarbon group E side has a structure in which an oxygen atom, a sulfur atom, -NR dd -, a carbonyl group, -COO- or -CONH- is bonded, or a structure in which a part of the hydrogen atoms of this hydrocarbon group is substituted by an organic group having a hetero atom. R dd is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer from 1 to 3.

[0148] When the structural unit F has an (x) alkali-soluble group, R F is a hydrogen atom, and A 1 is an oxygen atom, -COO-* or -SO2O-*. * indicates the bonding site to R F . W 1 is a single bond, a hydrocarbon group having 1 to 20 carbon atoms or a divalent fluorinated hydrocarbon group. When A 1 is an oxygen atom, W 1 is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group at the carbon atom to which A 1 is bonded. R E is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, a plurality of R E , W 1 , A 1 and R F may be the same or different from each other. By the structural unit F having an (x) alkali-soluble group, the affinity for the alkali developer can be increased and development defects can be suppressed. As the structural unit F having an (x) alkali-soluble group, A 1 is an oxygen atom and W 1 is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group is particularly preferred.

[0149] When the structural unit F has a (y) alkali-dissociable group, R F is a monovalent organic group having 1 to 30 carbon atoms, and A 1 is an oxygen atom, -NR aa -, -COO-* or -SO2O-*. R aa is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * indicates the bonding site to R F W 1 is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R E is a single bond or a divalent organic group having 1 to 20 carbon atoms. When A 1 is -COO-* or -SO2O-*, W 1 or R F has a fluorine atom on the carbon atom bonded to A 1 or the carbon atom adjacent thereto. When A 1 is an oxygen atom, W 1 , R E is a single bond, R D is a structure in which a carbonyl group is bonded to the end on the R E side of a hydrocarbon group having 1 to 20 carbon atoms, and R F is an organic group having a fluorine atom. When s is 2 or 3, a plurality of R E , W 1 , A 1 and R F may be the same or different from each other. Since the structural unit F has a (y) alkali-dissociable group, the surface of the resist film changes from hydrophobic to hydrophilic in the alkali development process. As a result, the affinity for the developer is significantly increased, and development defects can be suppressed more efficiently. As the structural unit f having a (y) alkali-dissociable group, A 1 is -COO-*, and R F or W 1 or both of them having a fluorine atom are particularly preferred.

[0150] R C is preferably a hydrogen atom and a methyl group, and more preferably a methyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit F and the like.

[0151] R E When R is a divalent organic group, a group having a lactone structure is preferable, a group having a polycyclic lactone structure is more preferable, and a group having a norbornane lactone structure is even more preferable.

[0152] When the high fluorine content resin has the structural unit F, the lower limit of the content ratio of the structural unit F is preferably 5 mol%, more preferably 10 mol%, and even more preferably 15 mol% with respect to all the structural units constituting the high fluorine content resin. Further, as the upper limit of the above content ratio, 90 mol% is preferable, 80 mol% is more preferable, and 70 mol% is even more preferable. By setting the content ratio of the structural unit F within the above range, the water repellency of the resist film during liquid immersion exposure can be further improved.

[0153] The Mw of the high fluorine content resin is preferably 1,000 or more, more preferably 2,000, even more preferably 3,000, and particularly preferably 5,000. The Mw is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 20,000 or less, and particularly preferably 15,000 or less.

[0154] The Mw / Mn of the high fluorine content resin is usually 1 or more, and more preferably 1.1 or more. The Mw / Mn is usually 5 or less, preferably 3 or less, more preferably 2.5, and even more preferably 2.2 or less.

[0155] As the upper limit of the content of the high-fluorine content resin, 1 part by mass is preferable, 2 parts by mass is more preferable, and 3 parts by mass is even more preferable with respect to 100 parts by mass of the base resin. As the upper limit of the content, 20 parts by mass is preferable, 15 parts by mass is more preferable, and 10 parts by mass is even more preferable. By setting the content of the high-fluorine content resin within the above range, the high-fluorine content resin can be more effectively unevenly distributed on the surface layer of the resist film. As a result, elution at the upper part of the pattern during development is suppressed, and the rectangularity of the pattern can be enhanced. The above radiation-sensitive resin composition may contain one or more high-fluorine content resins.

[0156] (Synthesis method of high-fluorine content resin) The high-fluorine content resin can be synthesized by the same method as the synthesis method of the above base resin.

[0157] (Solvent) The radiation-sensitive resin composition according to this embodiment contains a solvent. The solvent contains at least propylene glycol monomethyl ether and alkyl lactate, and the content of propylene glycol monomethyl ether acetate in the solvent is 5% by mass or less. The content of propylene glycol monomethyl ether acetate in the above solvent is preferably 3% by mass or less, more preferably 1% by mass or less, and more preferably the solvent does not contain propylene glycol monomethyl ether acetate. By setting the solvent in the radiation-sensitive resin composition to a predetermined composition, the pattern defect suppressibility can be improved.

[0158] Examples of the alkyl lactate include ester compounds of lactic acid and a linear or branched aliphatic alcohol having 1 to 10 carbon atoms, such as methyl lactate, ethyl lactate, n-propyl lactate, i-propyl lactate, n-butyl lactate, i-butyl lactate, and t-butyl lactate. Among them, ester compounds of lactic acid and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms are preferable, and ethyl lactate is more preferable.

[0159] As the lower limit of the total content of propylene glycol monomethyl ether and alkyl lactate, 50% by mass is preferable, 70% by mass is more preferable, and 90% by mass is even more preferable in all the solvents. The upper limit of the above total content may be 100% by mass. By setting the total content of propylene glycol monomethyl ether and alkyl lactate within the above range, the pattern defect suppression property can be further enhanced.

[0160] As the lower limit of the content of propylene glycol monomethyl ether in the total mass of propylene glycol monomethyl ether and alkyl lactate, 5% by mass is preferable, 10% by mass is more preferable, and 15% by mass is even more preferable. The upper limit of the above content is preferably 99% by mass, more preferably 95% by mass, and even more preferably 90% by mass. By setting the content of propylene glycol monomethyl ether within the above range, the pattern defect suppression property can be further enhanced.

[0161] Examples of the solvents other than propylene glycol monomethyl ether and alkyl lactate include alcohol solvents, ether solvents (excluding propylene glycol monomethyl ether), ketone solvents, amide solvents, ester solvents (excluding alkyl lactate), hydrocarbon solvents, etc. The radiation-sensitive resin composition may contain two or more solvents.

[0162] Examples of the alcohol solvents include monohydric alcohol solvents having 1 to 18 carbon atoms such as iso-propanol, 4-methyl-2-pentanol, 3-methoxybutanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, 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, tripropylene glycol; Polyhydric alcohol partial ether solvents in which some of the hydroxy groups of the above polyhydric alcohol solvents are etherified (however, propylene glycol monomethyl ether is excluded), etc.

[0163] Examples of ether solvents include Dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, etc.; Cyclic ether solvents such as tetrahydrofuran, tetrahydropyran, etc.; Aromatic ring-containing ether solvents such as diphenyl ether, anisole (methyl phenyl ether), etc.; Polyhydric alcohol ether solvents in which the hydroxy groups of the above polyhydric alcohol solvents are etherified, etc.

[0164] Examples of ketone solvents include chain ketone solvents such as acetone, butanone, methyl-iso-butyl ketone, etc. Cyclic ketone solvents such as cyclopentanone, cyclohexanone, methylcyclohexanone, etc. 2,4-pentanedione, acetonylacetone, acetophenone, etc.

[0165] Examples of amide solvents include cyclic amide solvents such as N,N'-dimethylimidazolidinone, N-methylpyrrolidone, etc. Chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpropionamide, etc.

[0166] Examples of ester solvents include Monocarboxylic acid ester solvents such as n-butyl acetate (however, alkyl lactate is excluded); Polyhydric alcohol partial ether acetate solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, etc. (however, the content of propylene glycol monomethyl ether acetate is 5% by mass or less); Lactone solvents such as γ-butyrolactone and valerolactone; Carbonate solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; Examples of polyvalent carboxylic acid diester solvents include propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, ethyl lactate, and diethyl phthalate.

[0167] Examples of hydrocarbon solvents include Aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; Aromatic hydrocarbon solvents such as benzene, toluene, di-iso-propylbenzene, and n-amylnaphthalene, etc.

[0168] <Other optional components> The above radiation-sensitive resin composition may contain other optional components in addition to the above components. Examples of the other optional components include crosslinking agents, uneven distribution promoters, surfactants, alicyclic skeleton-containing compounds, sensitizers, etc. These other optional components may be used alone or in combination of two or more.

[0169] <Method for preparing the radiation-sensitive resin composition> The above radiation-sensitive resin composition can be prepared, for example, by mixing a base resin, a solvent, and, if necessary, other optional components in a predetermined ratio. After mixing, the above 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 solid content concentration of the above radiation-sensitive resin composition is usually 0.1% by mass to 50% by mass, preferably 0.5% by mass to 30% by mass, and more preferably 1% by mass to 20% by mass.

[0170] [Second Embodiment] 《Radiation-Sensitive Resin Composition》 The radiation-sensitive resin composition according to the second embodiment contains a radiation-sensitive acid-generating resin and a solvent. The radiation-sensitive acid-generating resin corresponds to a form in which a radiation-sensitive acid generator is incorporated as a part of a polymer. Therefore, the radiation-sensitive resin composition according to this embodiment may or may not contain a radiation-sensitive strong acid generator as a radiation-sensitive acid generator, but preferably contains an acid diffusion control agent. The radiation-sensitive resin composition according to the second embodiment is the same as the radiation-sensitive resin composition according to the first embodiment, except that it contains a radiation-sensitive acid-generating resin instead of the resin of the radiation-sensitive resin composition according to the first embodiment and optionally contains a radiation-sensitive acid generator. Hereinafter, the radiation-sensitive acid-generating resin different from the first embodiment will be described.

[0171] <Radiation-Sensitive Acid-Generating Resin> The radiation-sensitive acid-generating resin contains a structural unit having a radiation-sensitive acid-generating structure (hereinafter, also referred to as "structural unit G"), and a structural unit represented by the following formula (1). As the structural unit represented by the following formula (1), the structural unit A contained in the resin in the first embodiment can be preferably adopted. The radiation-sensitive acid-generating resin as a base resin may contain, in addition to the structural units A and G, the structural units B, C, D, etc. contained in the resin in the first embodiment.

[0172] [Chemical Formula] (In the above formula (1), R T is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R X is a monovalent hydrocarbon group having 1 to 20 carbon atoms. Cy represents an alicyclic structure having 3 to 20 ring members formed together with the carbon atom to which it is bonded.)

[0173] (Structural Unit G) The structural unit G has a radiation-sensitive acid-generating structure. As the radiation-sensitive acid-generating structure, the structure of the radiation-sensitive acid generator according to the first embodiment can be preferably adopted, and in particular, it preferably has the structure of a radiation-sensitive strong acid generator.

[0174] The radiation-sensitive acid-generating structure preferably contains one or more kinds of onium salts including an organic acid anion part and an onium cation part. The organic acid anion part preferably has at least one selected from the group consisting of a sulfonic acid anion, a carboxylic acid anion, and a sulfonimide anion. Further, the onium cation part is preferably at least one selected from the group consisting of a sulfonium cation and an iodonium cation.

[0175] The radiation-sensitive acid-generating resin preferably contains a structural unit represented by the following formula (g1) (hereinafter, also referred to as "structural unit G1") or a structural unit represented by the following formula (g2) (hereinafter, also referred to as "structural unit G2").

[0176] [Chemical formula]

[0177] In the formula, R A is a hydrogen atom or a methyl group. X 1 is a single bond or an ester group. X 2 is a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms, or an arylene group having 6 to 10 carbon atoms, and a part of the methylene groups constituting the alkylene group may be substituted with an ether group, an ester group or a lactone ring-containing group. Also, at least one hydrogen atom contained in X 2 may be substituted with an iodine atom. X 3 is a single bond, an ether group, an ester group, or a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms, and a part of the methylene groups constituting the alkylene group may be substituted with an ether group or an ester group. Rf 1 ~Rf 4is independently a hydrogen atom, a fluorine atom or a trifluoromethyl group, provided that at least one of them is a fluorine atom or a fluorinated hydrocarbon group. R 3 ~R 7 is independently a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, and R 3 and R 4 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded.

[0178] R 3 ~R 7 The monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom in R

[0179] ~R

[0180]

Chemical formula

[0181] In the formula, R A 、R 3 ~R 7 、Rf 1 ~Rf 4 and X 1 have the same meanings as in the above formula (g1) or (g2). R 8is a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms, a halogen atom other than iodine, a hydroxy group, a linear, branched or cyclic alkoxy group having 1 to 4 carbon atoms, or a linear, branched or cyclic alkoxycarbonyl group having 2 to 5 carbon atoms. m is an integer of 0 to 4. n is an integer of 0 to 3.

[0182] Examples of the organic acid anion moiety of the monomer that gives the structural unit G1 or the structural unit G2 include, but are not limited to, those shown below. Note that all of the following are organic acid anion moieties having an iodine-substituted aromatic ring structure. As the organic acid anion moiety having no iodine-substituted aromatic ring structure, a structure in which the iodine atom in the following formula is substituted with an atom or group other than an iodine atom such as a hydrogen atom or another substituent can be preferably adopted.

[0183]

Chemical formula

[0184]

Chemical formula

[0185]

Chemical formula

[0186]

Chemical formula

[0187]

Chemical formula

[0188]

Chemical formula

[0189]

Chemical formula

[0190] The onium cation moiety of the structural unit G1 is preferably represented by the following formula (Q-1).

[0191]

Chemical formula

[0192] In the above formula (Q-1), Ra1 and Ra2 each independently represent a substituent. n1 represents an integer from 0 to 5. When n1 is 2 or more, a plurality of Ra1 may be the same or different. n2 represents an integer from 0 to 5. When n2 is 2 or more, a plurality of Ra2 may be the same or different. n3 represents an integer from 0 to 5. When n3 is 2 or more, a plurality of Ra3 may be the same or different. Ra3 represents a fluorine atom or a group having one or more fluorine atoms. Ra1 and Ra2 may be linked to each other to form a ring. When n1 is 2 or more, a plurality of Ra1 may be linked to each other to form a ring. When n2 is 2 or more, a plurality of Ra2 may be linked to each other to form a ring.

[0193] Preferred examples of the substituents represented by Ra1 and Ra2 include an alkyl group, a cycloalkyl group, an alkoxy group, a cycloalkyloxy group, an alkoxycarbonyl group, an alkylsulfonyl group, a hydroxyl group, a halogen atom, and a halogenated hydrocarbon group.

[0194] The alkyl group of Ra1 and Ra2 may be a linear alkyl group or a branched alkyl group. The alkyl group preferably has 1 to 10 carbon atoms. Examples include 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, a neopentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, and an n-decyl group. Among these, a methyl group, an ethyl group, an n-butyl group, and a t-butyl group are particularly preferred.

[0195] Examples of the cycloalkyl groups for Ra1 and Ra2 include monocyclic or polycyclic cycloalkyl groups (preferably cycloalkyl groups having 3 to 20 carbon atoms), such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclododecanyl, cyclopentenyl, cyclohexenyl, and cyclooctadienyl groups. Among these, cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups are particularly preferred.

[0196] Examples of the alkyl group portion of the alkoxy groups for Ra1 and Ra2 include those listed above as the alkyl groups for Ra1 and Ra2. Particularly preferred as this alkoxy group are methoxy, ethoxy, n-propoxy, and n-butoxy groups.

[0197] Examples of the cycloalkyl group portion of the cycloalkyloxy groups for Ra1 and Ra2 include those listed above as the cycloalkyl groups for Ra1 and Ra2. Particularly preferred as this cycloalkyloxy group are cyclopentyloxy and cyclohexyloxy groups.

[0198] Examples of the alkoxy group portion of the alkoxycarbonyl groups for Ra1 and Ra2 include those listed above as the alkoxy groups for Ra1 and Ra2. Particularly preferred as this alkoxycarbonyl group are methoxycarbonyl, ethoxycarbonyl, and n-butoxycarbonyl groups.

[0199] Examples of the alkyl group moiety of the alkylsulfonyl groups Ra1 and Ra2 include those enumerated above as the alkyl groups of Ra1 and Ra2. Examples of the cycloalkyl group moiety of the cycloalkylsulfonyl groups Ra1 and Ra2 include those enumerated above as the cycloalkyl groups of Ra1 and Ra2. Particularly preferred as these alkylsulfonyl groups or cycloalkylsulfonyl groups are methanesulfonyl group, ethanesulfonyl group, n-propanesulfonyl group, n-butanessulfonyl group, cyclopentanesulfonyl group and cyclohexanesulfonyl group.

[0200] Each of the groups Ra1 and Ra2 may further have a substituent.

[0201] Examples of the halogen atom of Ra1 and Ra2 include fluorine atom, chlorine atom, bromine atom and iodine atom, with fluorine atom being preferred.

[0202] As the halogenated hydrocarbon group of Ra1 and Ra2, a halogenated alkyl group is preferred. Examples of the alkyl group and halogen atom constituting the halogenated alkyl group are the same as those described above. Among them, a fluorinated alkyl group is preferred, and CF3 is more preferred.

[0203] As described above, Ra1 and Ra2 may be connected to each other to form a ring (i.e., a heterocyclic ring containing a sulfur atom). In this case, Ra1 and Ra2 preferably form a single bond or a divalent linking group. Examples of the divalent linking group include, for example, -COO-, -OCO-, -CO-, -O-, -S-, -SO-, -SO2-, an alkylene group, a cycloalkylene group, an alkenylene group, or a combination of two or more thereof, and those having a total carbon number of 20 or less are preferred. When Ra1 and Ra2 are connected to each other to form a ring, Ra1 and Ra2 preferably form -COO-, -OCO-, -CO-, -O-, -S-, -SO--SO2- or a single bond, more preferably form -O-, -S- or a single bond, and particularly preferably form a single bond. Further, when n1 is 2 or more, a plurality of Ra1 may be connected to each other to form a ring, and when n2 is 2 or more, a plurality of Ra2 may be connected to each other to form a ring. Examples of such a case include, for example, a mode in which two Ra1 are connected to each other and form a naphthalene ring together with the benzene ring to which they are bonded.

[0204] Ra3 is a fluorine atom or a group having a fluorine atom. Examples of the group having a fluorine atom include groups in which the alkyl group, cycloalkyl group, alkoxy group, cycloalkyloxy group, alkoxycarbonyl group, and alkylsulfonyl group as Ra1 and Ra2 are substituted with a fluorine atom. Among them, a fluorinated alkyl group can be preferably mentioned, and CF3, C2F5, C3F7, C4F9, C5F 11 、C6F 13 、C7F 15 、C8F 17 、CH2CF3, CH2CH2CF3, CH2C2F5, CH2CH2C2F5, CH2C3F7, CH2CH2C3F7, CH2C4F9 and CH2CH2C4F9 can be more preferably mentioned, and CF3 can be particularly preferably mentioned.

[0205] Ra3 is preferably a fluorine atom or CF3, and more preferably a fluorine atom.

[0206] n1 and n2 are each independently preferably an integer of 0 to 3, more preferably an integer of 0 to 2.

[0207] n3 is preferably an integer of 1 to 3, more preferably 1 or 2.

[0208] (n1 + n2 + n3) is preferably an integer of 1 to 15, more preferably an integer of 1 to 9, still more preferably an integer of 2 to 6, and particularly preferably an integer of 3 to 6. When (n1 + n2 + n3) is 1, it is preferable that n3 = 1 and Ra3 is a fluorine atom or CF3. When (n1 + n2 + n3) is 2, a combination where n1 = n3 = 1 and Ra1 and Ra3 are each independently a fluorine atom or CF3, and a combination where n3 = 2 and Ra3 is a fluorine atom or CF3 are preferable. When (n1 + n2 + n3) is 3, a combination where n1 = n2 = n3 = 1 and Ra1 to Ra3 are each independently a fluorine atom or CF3 is preferable. When (n1 + n2 + n3) is 4, a combination where n1 = n3 = 2 and Ra1 and Ra3 are each independently a fluorine atom or CF3 is preferable. When (n1 + n2 + n3) is 5, a combination where n1 = n2 = 1 and n3 = 3 and Ra1 to Ra3 are each independently a fluorine atom or CF3, a combination where n1 = n2 = 2 and n3 = 1 and Ra1 to Ra3 are each independently a fluorine atom or CF3, and a combination where n3 = 5 and Ra3 is each independently a fluorine atom or CF3 are preferable. When (n1 + n2 + n3) is 6, a combination where n1 = n2 = n3 = 2 and Ra1 to Ra3 are each independently a fluorine atom or CF3 is preferable.

[0209] As specific examples of the onium cation moiety represented by the above formula (Q-1), the structures exemplified as the sulfonium cation moiety in the radiation-sensitive strong acid generator according to the first embodiment can be preferably employed. Note that all of the above are sulfonium cation moieties having a fluorine-substituted aromatic ring structure, but as an onium cation moiety not having a fluorine-substituted aromatic ring structure, a structure in which the fluorine atoms or CF3 in the above formula are substituted with atoms or groups other than fluorine atoms such as hydrogen atoms or other substituents can be preferably employed.

[0210] When the onium cation moiety of the structural unit G2 contains a fluorine-substituted aromatic ring structure, the onium cation moiety is preferably a diaryliodonium cation having one or more fluorine atoms. Among them, it is preferably represented by the following formula (Q-2).

[0211]

Chemical formula

[0212] In the formula, R d1 and R d2 are each independently a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyl group having 1 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, or a nitro group. R d3 and R d4 are each independently a fluorine atom or a group having a fluorine atom. k1 and k2 are each independently an integer from 0 to 5. k3 and k4 are each independently an integer from 0 to 5. However, (k1 + k3) and (k2 + k4) are each 5 or less, and (k3 + k4) is an integer from 1 to 10. When R d1 to R d4 are each plural, the plural R d1 to R d4 may be the same or different from each other.

[0213] R d1 and R d2 The alkyl group, alkoxy group and alkoxycarbonyl group represented by, and the group having a fluorine atom represented by R d3 and R d4 are the same as those in the above formula (Q-1), respectively.

[0214] Examples of the monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms include aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group; aralkyl groups such as benzyl group, phenethyl group, etc.

[0215] Examples of the substituent of each group include halogen atoms such as fluorine atom, chlorine atom, bromine atom, iodine atom; hydroxy group; carboxy group; cyano group; nitro group; alkyl group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, acyloxy group, or a group in which a hydrogen atom of these groups is substituted with a halogen atom; oxo group (=O), etc.

[0216] k1 and k2 are each preferably 0 to 2, more preferably 0 or 1. k3 and k4 are each preferably 1 to 3, more preferably 1 or 2. (k3 + k4) is an integer of 1 to 10, preferably an integer of 1 to 6, more preferably an integer of 1 to 4, and still more preferably 1 or 2.

[0217] As specific examples of such an onium cation moiety represented by the above formula (Q-2), the structures exemplified as the iodonium cation moiety in the radiation-sensitive strong acid generator according to the first embodiment can be preferably employed. It should be noted that all of those shown above are iodonium cation moieties having a fluorine-substituted aromatic ring structure. As an onium cation moiety not having a fluorine-substituted aromatic ring structure, a structure in which a fluorine atom or CF3 in the above formula is substituted with an atom or group other than a fluorine atom such as a hydrogen atom or another substituent can be preferably employed.

[0218] The lower limit of the content ratio of the structural unit G1 or the structural unit G2 (when a plurality of types are included, the total content ratio) is preferably 5 mol% with respect to all the structural units constituting the radiation-sensitive acid-generating resin, more preferably 10 mol%, and still more preferably 15 mol%. The upper limit of the above content ratio is preferably 50 mol%, more preferably 40 mol%, and still more preferably 30 mol%. By setting the content ratio of the structural unit G1 or the structural unit G2 within the above range, the function as an acid generator can be sufficiently exhibited.

[0219] The monomer that provides the structural unit G1 or the structural unit G2 can be synthesized, for example, in the same manner as the sulfonium salt having a polymerizable anion described in Japanese Patent No. 5201363.

[0220] [Embodiment 3] 《Pattern Formation Method》 The pattern formation method in this embodiment is as follows A step of forming a resist film by applying the above radiation-sensitive resin composition directly or indirectly on a substrate (hereinafter, also referred to as "resist film formation step"), A step of exposing the above resist film (hereinafter, also referred to as "exposure step"), and A step of developing the exposed resist film (hereinafter, also referred to as "development step").

[0221] The pattern formation method may further include a step of forming a resist underlayer film by applying a composition for forming a resist underlayer film directly or indirectly on the substrate before the resist film formation step (hereinafter, also referred to as "resist underlayer film formation step").

[0222] According to the above pattern formation method, since the radiation-sensitive resin composition excellent in pattern defect suppression property, sensitivity, and CDU performance is used, a high-quality resist pattern can be formed. Hereinafter, each step will be described including the resist underlayer film formation step which is an optional step.

[0223] [Resist Underlayer Film Formation Step] This step is performed before the resist film formation step. The resist underlayer film can be formed by applying a composition for forming a resist underlayer film directly or indirectly on a substrate. The composition for forming a resist underlayer film typically contains a novolak polymer obtained by polycondensation of an aromatic ring and an aldehyde and a solvent. The above polymer may have an acidic group or a basic group.

[0224] Also, together with or instead of the resist underlayer film, an organic or inorganic antireflection film disclosed in, for example, Japanese Patent Laid-Open No. 59-93448 may be formed on the substrate before the resist formation step.

[0225] [Resist Film Formation Step] In this process, a resist film is formed using the above-described radiation-sensitive resin composition. Examples of the substrate on which the resist film is formed include conventionally known ones such as silicon wafers, silicon dioxide, and wafers coated with aluminum. A film of a dielectric material such as SiO2, SiC, SiN, SiOC, SiNO, SiCNO, or SiCN may be formed on the substrate. Examples of the coating method of the radiation-sensitive resin composition include spin coating, casting, roll coating, and the like. After coating, pre-baking (PB) may be performed as necessary to volatilize the solvent in the coating film. The PB temperature is usually 60°C to 140°C, preferably 80°C to 120°C. The PB time is usually 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds. The film thickness of the resist film to be formed is preferably 10 nm to 1,000 nm, more preferably 10 nm to 500 nm.

[0226] When performing immersion lithography, regardless of the presence or absence of a water-repellent polymer additive such as the high fluorine content resin in the above-described radiation-sensitive resin composition, for the purpose of avoiding direct contact between the immersion liquid and the resist film, an immersion protective film insoluble in the immersion liquid may be provided on the formed resist film. As the immersion protective film, a solvent peelable protective film that is peeled off by a solvent before the development process (see, for example, JP-A-2006-227632), or a developer peelable protective film that is peeled off simultaneously with the development in the development process (see, for example, WO2005-069076, WO2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer peelable immersion protective film.

[0227] When the exposure process, which is the next process, is performed using radiation with a wavelength of 50 nm or less, it is preferable to use a resin having the structural unit A and the structural unit B, and, as necessary, the structural units C and D as the base resin in the above-described composition.

[0228] [Exposure Process] In this process, the resist film formed in the above resist film forming process is irradiated with radiation (in some cases, through an immersion medium such as water) through a photomask to be exposed. As the radiation used for exposure, electromagnetic waves such as visible light, ultraviolet light, deep ultraviolet light, EUV (extreme ultraviolet light), X-rays, and γ-rays; charged particle beams such as electron beams and α-rays can be mentioned according to the line width of the target pattern. Among these, deep ultraviolet light, electron beams, and EUV are preferred, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV are more preferred, and electron beams and EUV with a wavelength of 50 nm or less positioned as the next-generation exposure technology are even more preferred.

[0229] When exposure is performed by immersion exposure, examples of the immersion liquid used include water, fluorine-based inert liquids, and the like.

[0230] After the above exposure, post-exposure baking (PEB) is performed, and it is preferable to promote the dissociation of the acid dissociable groups of the resin or the like by the acid generated from the radiation-sensitive acid generator by exposure in the exposed portion of the resist film. By this PEB, a difference in solubility in the developer occurs between the exposed portion and the unexposed portion. The PEB temperature is usually 50°C to 180°C, and preferably 80°C to 130°C. The PEB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.

[0231] [Development Process] In this process, the resist film exposed in the above exposure process is developed. Thereby, a predetermined resist pattern can be formed. After development, it is common to wash with a rinse liquid such as water or alcohol and then dry.

[0232] As the developer used for the above development, in the case of alkaline development, for example, an alkaline aqueous solution in which 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, 1,5-diazabicyclo-[4.3.0]-5-nonene is dissolved can be mentioned. Among these, an aqueous TMAH solution is preferable, and a 2.38 mass% aqueous TMAH solution is more preferable.

[0233] In addition, in the case of organic solvent development, organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, or solvents containing an organic solvent can be mentioned. Examples of the above organic solvent include one or more of the solvents listed as the solvent of the above radiation-sensitive resin composition. Among these, ester solvents and ketone solvents are preferable. As the ester solvent, an acetic acid ester solvent is preferable, and n-butyl acetate and amyl acetate are more preferable. As the ketone solvent, a chain ketone is preferable, and 2-heptanone is more preferable. The content of the organic solvent in the developer is preferably 80 mass% or more, more preferably 90 mass% or more, still more preferably 95 mass% or more, and particularly preferably 99 mass% or more. Examples of the components other than the organic solvent in the developer include water, silicone oil, etc.

[0234] Examples of the development 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 developing by raising the developer on the substrate surface by surface tension and allowing it to stand for a certain period of time (paddle method), a method of spraying the developer on the substrate surface (spray method), a method of continuously discharging the developer while scanning a developer discharge nozzle at a constant speed on a substrate rotating at a constant speed (dynamic dispense method), etc.

Example

[0235] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. The measurement methods of various physical property values are shown below.

[0236] The structures of onium salts (hereinafter also referred to as "PAG1", etc.) as radiation-sensitive acid generators (PAG) used in the radiation-sensitive resin composition are shown below.

[0237]

Chemical formula

[0238]

Chemical formula

[0239] [Synthesis example] Synthesis of base resin Each monomer was combined and copolymerized under a tetrahydrofuran (THF) solvent, crystallized in methanol, and further washed repeatedly with hexane, and then isolated and dried to obtain P-1 to P-7 as base resins having the following compositions. The composition of the obtained base resin was 1 confirmed by 1H-NMR. The Mw and dispersity (Mw / Mn) of the resin were measured by gel permeation chromatography (GPC) using GPC columns (two "G2000HXL", one "G3000HXL", and one "G4000HXL") manufactured by Tosoh Corporation under the following conditions. Eluent: Tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd.) Flow rate: 1.0 mL / min Sample concentration: 1.0 mass% Sample injection volume: 100 μL Column temperature: 40 °C Detector: Differential refractometer Standard substance: Monodisperse polystyrene

[0240] P-1: Mw = 8,600, Mw / Mn = 1.88 P-2: Mw = 6,900, Mw / Mn = 1.72 P-3: Mw = 7,000, Mw / Mn = 1.76 P-4: Mw = 7,200, Mw / Mn = 1.69 P-5: Mw = 7,300, Mw / Mn = 1.65 P-6: Mw = 6,900, Mw / Mn = 1.76 P-7: Mw = 8,600, Mw / Mn = 1.88

[0241]

Chem.

[0242]

Chem.

[0243] [Examples 1 - 25, Comparative Examples 1 - 21] Each component shown in Tables 1 - 5 was dissolved in a solvent in which 100 ppm of FC - 4430 manufactured by 3M was dissolved, and then filtered through a 0.2 - μm - sized filter to prepare a radiation - sensitive resin composition.

[0244] Solvent: PGMEA (propylene glycol monomethyl ether acetate) CHN (cyclohexanone) PGME (propylene glycol monomethyl ether) EL (ethyl lactate)

[0245] Acid diffusion controller: Q - 1 to Q - 15 (refer to the following structural formula)

Chem.

[0246]

Chem.

[0247] [Chemistry]

[0248] [Evaluation] The defect suppression property, sensitivity, and CDU performance of the radiation-sensitive resin composition were evaluated by the following method. For the measurement of the resist pattern length in sensitivity and CDU performance, a high-resolution FEB length measurement device ("CG5000" of Hitachi High-Technologies Corporation) was used. The results are shown in Tables 1 to 5.

[0249] [Formation of line and space pattern (EUV exposure, alkali development)] The radiation-sensitive resin composition prepared above was coated on the surface of a 12-inch silicon wafer deposited with SiC using a spin coater ("CLEAN TRACK ACT8" of Tokyo Electron Limited), and PB was performed at 130°C for 60 seconds, followed by cooling at 23°C for 30 seconds to form a resist film with a thickness of 55 nm. Next, this resist film was irradiated with EUV light using an EUV exposure machine (model "NXE3300", manufactured by ASML, NA = 0.33, illumination condition: Conventional s = 0.89, mask imecDEFECT32FFR02). Then, PEB was performed at 110°C for 60 seconds, followed by cooling at 23°C for 30 seconds, and a positive 32-nm line and space pattern was formed by developing at 23°C for 30 seconds using a 2.38 mass% aqueous solution of tetramethylammonium hydroxide (TMAH).

[0250] [Defect suppression property] Regarding the line and space pattern formed above, the number of defects (pieces / cm 2 ) was measured with a defect inspection device ("KLA2925" of KLA-Tencor Corporation). The defect suppression property can be evaluated as "good" when it is 20 pieces / cm 2 or less, and "bad" when it exceeds 20 pieces / cm 2 .

[0251] [Sensitivity] In the formation of the resist pattern, the exposure dose for forming a 32 nm line and space pattern was defined as the optimum exposure dose, and this optimum exposure dose was defined as the sensitivity (mJ / cm 2 ).

[0252] <Formation of Hole Pattern (EUV Exposure, Alkaline Development)> Each of the above radiation-sensitive resin compositions was spin-coated on a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content: 43% by mass) was formed with an average thickness of 20 nm, and prebaked at 105 °C for 60 seconds using a hot plate to produce a resist film with an average thickness of 60 nm. This was then exposed using an EUV scanner "NXE3300" manufactured by ASML (NA 0.33, σ 0.9 / 0.6, quadrupole illumination, mask for a hole pattern with a pitch of 46 nm and a +20% bias in the on-wafer dimension), PEB was performed on a hot plate at 110 °C for 60 seconds, and development was carried out for 30 seconds using a 2.38% by mass TMAH aqueous solution to obtain a hole pattern with a dimension of 23 nm.

[0253] <Evaluation> The following evaluations were performed on the obtained resist pattern.

[0254] [CDU Performance] Using a length-measuring SEM (CG5000) manufactured by Hitachi High-Technologies Corporation, the exposure dose when the hole dimension was formed to be 23 nm was determined and defined as the sensitivity. At this time, the dimensions of 50 holes were measured, and the CDU (dimension variation 3σ) (nm) was determined. For the CDU performance, the smaller the value, the smaller the variation in the hole diameter in the long period and the better the performance.

[0255]

Table 1

[0256]

Table 2

[0257]

Table 3

[0258]

Table 4

[0259]

Table 5

[0260] [Example 26] In Example 25, before spin-coating the radiation-sensitive resin composition, the composition for forming a resist underlayer film in Example 1 of JP-A-2012-215842 was spin-coated so as to have an average thickness of 300 nm to form a resist underlayer film, and the operation was the same as in Example 25 except for this. Then, the evaluation of defect suppressibility, sensitivity, and CDU performance was performed. As a result, the same results as in Example 25 were obtained. The above composition for forming an underlayer film contained 10 parts by mass of a polymer which is a condensate of 1-naphthol and formaldehyde, and 90 parts by mass of propylene glycol monomethyl ether acetate.

[0261] From the results shown in Tables 1 to 5 and Example 26, it was confirmed that according to the resist composition of the examples to which the present invention was applied, a resist pattern with few defects and good CDU performance can be obtained with high sensitivity.

Industrial Applicability

[0262] According to the radiation-sensitive resin composition and the resist pattern forming method described above, a resist pattern with few defects and good CDU performance can be formed with high sensitivity. Therefore, these can be suitably used in the processing process of semiconductor devices and the like, which are expected to further progress in miniaturization in the future.

Claims

1. A radiation-sensitive acid-generating resin composition comprising a structural unit having a radiation-sensitive acid-generating structure and a structural unit represented by the following formula (1), a solvent, wherein the solvent contains at least propylene glycol monomethyl ether and alkyl lactate, and the content of propylene glycol monomethyl ether acetate in the solvent is 5% by mass or less, the total content of propylene glycol monomethyl ether and alkyl lactate in the solvent is 50% by mass or more, and the content of the propylene glycol monomethyl ether is 5% by mass or more and 99% by mass or less based on the total mass of propylene glycol monomethyl ether and alkyl lactate. 【Chemical 1】 (In the above formula (1), R Ｔ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R Ｘ is a monovalent hydrocarbon group having 1 to 20 carbon atoms. Cy represents an alicyclic structure having 3 to 20 ring members formed together with the carbon atom to which it is bonded.)

2. The radiation-sensitive resin composition according to claim 1, wherein the content of propylene glycol monomethyl ether acetate in the solvent is 1% by mass or less.

3. The radiation-sensitive resin composition according to claim 1 or 2, wherein the solvent does not contain propylene glycol monomethyl ether acetate.

4. The radiation-sensitive resin composition according to claim 1, wherein the radiation-sensitive acid-generating structure contains an organic acid anion part and an onium cation part.

5. The radiation-sensitive resin composition according to claim 4, wherein the organic acid anion part contains an iodine-substituted aromatic ring structure.

6. The radiation-sensitive resin composition according to claim 4, wherein the onium cation part contains a fluorine-substituted aromatic ring structure.

7. The radiation-sensitive resin composition according to claim 1, wherein the radiation-sensitive acid-generating resin further contains a structural unit having a phenolic hydroxyl group.

8. The radiation-sensitive resin composition according to any one of claims 4 to 6, wherein the organic acid anion part has at least one selected from the group consisting of a sulfonate anion, a carboxylate anion, and a sulfonimide anion.

9. The radiation-sensitive resin composition according to any one of claims 4 to 6 or 8, wherein the onium cation part is at least one selected from the group consisting of a sulfonium cation and an iodonium cation.

10. The radiation-sensitive resin composition according to any one of claims 1 to 9, wherein the structural unit represented by the formula (1) is represented by the following formula (A-1). [Chemical Formula 2] (In the above formula (A-1), R Ｔ and R Ｘ are synonymous with the above formula (1).)

11. The radiation-sensitive resin composition according to any one of claims 4 to 9, wherein the organic acid anion moiety contains a partial structure represented by the following formula (b1) or (b2). 【Chemical Formula 3】 (In the above formula, 【Chemical Formula 4】 represents a single bond or a double bond.)

12. A step of forming a resist film by applying the radiation-sensitive resin composition according to any one of claims 1 to 11 directly or indirectly onto a substrate; A step of exposing the resist film; A step of developing the exposed resist film with a developer And a pattern forming method comprising the steps of:

13. The pattern forming method according to claim 12, wherein the exposure is performed using extreme ultraviolet rays or electron beams.

14. The pattern forming method according to claim 12 or 13, further comprising a step of forming a resist underlayer film by applying a composition for forming a resist underlayer film directly or indirectly onto the substrate before the resist film forming step.

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