WO2015129832A1

WO2015129832A1 - Radiosensitive resin composition, method for forming resist pattern, polymer, and compound

Info

Publication number: WO2015129832A1
Application number: PCT/JP2015/055718
Authority: WO
Inventors: 準人生井
Original assignee: Jsr株式会社
Priority date: 2014-02-26
Filing date: 2015-02-26
Publication date: 2015-09-03
Also published as: JPWO2015129832A1; JP6493386B2

Abstract

　The present invention is a radiosensitive resin composition containing: a polymer having a structural unit that contains the group represented by formula (1); and a radiosensitive acid generator. In formula (1), R¹ is a substituted or unsubstituted divalent C1-10 hydrocarbon group. R² is a single-bond or substituted or unsubstituted divalent chain C1-5 hydrocarbon group. R¹ and one or more of R² may be combined and, together with the carbon atoms bound thereto, form a 3-20 membered ring structure. a is an integer of 1-3. A is a monovalent group having two or more heteroatoms, and is bonded to R² via a carbon atoms. The asterisk mark shows the binding site. A in formula (1) below is preferably a monovalent cyclic group having a heterocyclic structure.

Description

Radiation sensitive resin composition, resist pattern forming method, polymer and compound

The present invention relates to a radiation sensitive resin composition, a resist pattern forming method, a polymer and a compound.

For forming various electronic device structures such as semiconductor devices and liquid crystal devices, a resist pattern forming method by photolithography is used. In this resist pattern forming method, for example, a radiation sensitive resin composition for forming a resist pattern on a substrate is used. The radiation sensitive resin composition generates an acid in an exposed portion by irradiation with radiation such as deep ultraviolet rays such as ArF excimer laser light or an electron beam, and a developing solution for an exposed portion and an unexposed portion by the catalytic action of the acid. A difference in dissolution rate with respect to is formed, and a resist pattern is formed on the substrate.

Such a radiation-sensitive resin composition is excellent in resolution and not only in the rectangular shape of the cross-sectional shape of the resist pattern, but also in LWR (Line Width Roughness) performance, CDU (Critical Dimension Uniformity) performance, and the like. In addition, it is required to obtain a high-accuracy pattern with a high yield with excellent depth of focus, exposure margin, MEEF (Mask Error Enhancement Factor) performance, and the like. In response to this requirement, various structures of the polymer contained in the radiation-sensitive resin composition have been studied. By having a lactone structure such as a butyrolactone structure or a norbornane lactone structure, the resist pattern can be adhered to the substrate. It is known that these properties can be improved and these performances can be improved (see JP-A-11-212265, JP-A-2003-5375, and JP-A-2008-83370).

However, at present, when the miniaturization of the resist pattern has progressed to a level of 45 nm or less, the required level of the performance is further increased, and the conventional radiation-sensitive resin composition satisfies these requirements. I can't make it happen.

JP-A-11-212265 JP 2003-5375 A JP 2008-83370 A

The present invention has been made based on the above-described circumstances, and exhibits excellent MEEF performance, depth of focus, and exposure margin, and is excellent in LWR performance, CDU performance, resolution, and cross-sectional rectangularity. It aims at providing the radiation sensitive resin composition which can form a resist pattern.

The invention made to solve the above problems is also referred to as a structural unit (hereinafter referred to as “structural unit (I)”) containing a group represented by the following formula (1) (hereinafter also referred to as “group (1)”). ) Containing a polymer (hereinafter also referred to as “[A] polymer”) and a radiation-sensitive acid generator (hereinafter also referred to as “[B] acid generator”). is there.

(In formula (1), R ¹ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms. R ² is a single bond or a substituted or unsubstituted 2 having 1 to 5 carbon atoms. R ¹ and at least ^one of one or more R ² form a ring structure having 3 to 20 ring members composed of carbon atoms to which they are bonded together and to which they are bonded. A is an integer of 1 to 3. When a is 2 or more, a plurality of R ² may be the same or different, and A has two or more heteroatoms, (This is a monovalent group bonded to R ² by a carbon atom. * Indicates a bonding site.)

Another invention made in order to solve the above-mentioned problems comprises a step of forming a resist film, a step of exposing the resist film, and a step of developing the exposed resist film, It is the resist pattern formation method formed with a conductive resin composition.

Yet another invention made to solve the above problems is a polymer having a structural unit represented by the following formula (I).

(In the formula (I), R ¹ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms. R ² is a single bond or a substituted or unsubstituted 2 having 1 to 5 carbon atoms. R ¹ and at least ^one of one or more R ² form a ring structure having 3 to 20 ring members composed of carbon atoms to which they are bonded together and to which they are bonded. A is an integer of 1 to 3. When a is 2 or more, a plurality of R ² may be the same or different, and R ¹⁰ is a hydrogen atom, a fluorine atom, a methyl group or A is a trifluoromethyl group, and A is a monovalent group having two or more heteroatoms and bonded to R ² with a carbon atom.

Yet another invention made to solve the above problems is a compound represented by the following formula (i).

Here, “organic group” means a group containing at least one carbon atom.

The “hydrocarbon group” includes a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The “hydrocarbon group” may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The “chain hydrocarbon group” refers to a hydrocarbon group that does not include a cyclic structure but includes only a chain structure, and includes both a linear hydrocarbon group and a branched hydrocarbon group. The term “alicyclic hydrocarbon group” refers to a hydrocarbon group that includes only an alicyclic structure as a ring structure and does not include an aromatic ring structure, and includes a monocyclic alicyclic hydrocarbon group and a polycyclic alicyclic group. Includes both hydrocarbon groups. However, it is not necessary to be composed only of the alicyclic structure, and a part thereof may include a chain structure. “Aromatic hydrocarbon group” refers to a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it is not necessary to be composed only of an aromatic ring structure, and a part thereof may include a chain structure or an alicyclic structure.

In addition, the “number of ring members” means the number of atoms constituting the ring of the alicyclic structure and the aliphatic heterocyclic structure, and in the case of the polycyclic alicyclic structure and the polycyclic aliphatic heterocyclic structure, The number of atoms that make up.

According to the radiation sensitive resin composition and resist pattern forming method of the present invention, excellent MEEF performance, depth of focus and exposure margin are exhibited, and LWR performance, CDU performance, resolution, and cross-sectional rectangularity are obtained. An excellent resist pattern can be formed. The polymer of this invention is used suitably as a polymer component of the said radiation sensitive resin composition. Since the compound of the present invention has a structure represented by the above formula (i), it is suitably used as a monomer compound that incorporates the structural unit (I) into the polymer. Therefore, these can be suitably used for pattern formation in semiconductor device manufacturing or the like, where miniaturization is expected to progress further in the future.

<Radiation sensitive resin composition>
The radiation-sensitive resin composition contains a [A] polymer and a [B] acid generator. Moreover, the said radiation sensitive resin composition is also called fluorine atom containing polymer (henceforth "[D] polymer") other than [C] acid diffusion control body and [D] [A] polymer as a suitable component. ) And [E] may contain a solvent, and may contain other optional components as long as the effects of the present invention are not impaired. Hereinafter, each component will be described.

<[A] polymer>
[A] The polymer is a polymer having the structural unit (I). The radiation-sensitive resin composition exhibits excellent MEEF performance, depth of focus, and exposure margin due to the [A] polymer having the structural unit (I), LWR performance, CDU performance, and resolution. In addition, it is possible to form a resist pattern having a rectangular cross-sectional shape (these performances are also referred to as “lithographic performances” hereinafter). [A] The reason why the polymer exhibits the above-described effect by having the above-described configuration is not necessarily clear, but can be inferred as follows, for example. As shown in the above formula (1), the structural unit (I) has a monovalent group having two or more heteroatoms, and a ketone structure is formed between the monovalent group and the polymer chain. Since it has the specific structure connected with the spacer which has, it has high polarity. Therefore, [A] polymer can adjust the solubility with respect to a developing solution more appropriately. Furthermore, the radiation sensitive resin composition can shorten the diffusion length of the acid generated from the [B] acid generator more appropriately. As a result, according to the radiation sensitive resin composition, the lithography performance of the resist pattern to be formed can be improved.

[A] In addition to the structural unit (I), the polymer is a structural unit other than the structural unit (I) and includes an acid dissociable group (II); a lactone structure, a cyclic carbonate structure, and a sultone structure Or a structural unit (III) containing a combination thereof; a structural unit (IV) containing a polar group and a fluorine atom-containing structural unit (V), and other structural units other than the structural units (I) to (V) It may have a structural unit or the like.

[A] The polymer preferably has a structural unit (II) and a structural unit (III) in addition to the structural unit (I). [A] The polymer may have one or more of each structural unit. Hereinafter, each structural unit will be described.

[Structural unit (I)]
The structural unit (I) is a structural unit containing a group represented by the following formula (1).

In the above formula (1), R ¹ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms. R ² is a single bond or a substituted or unsubstituted divalent chain hydrocarbon group having 1 to 5 carbon atoms. R ¹ and at least ^one of one or a plurality of R ² may be combined with each other to form a ring structure having 3 to 20 ring members that is configured together with the carbon atom to which they are bonded. a is an integer of 1 to 3. When a is 2 or more, a plurality of R ² may be the same or different. A has two or more hetero atoms, a monovalent group having a carbon atom bonded to R ^2. * Indicates a binding site.

Examples of the divalent hydrocarbon group represented by R ¹ include a divalent chain hydrocarbon group having 1 to 10 carbon atoms, a divalent alicyclic hydrocarbon group having 3 to 10 carbon atoms, and a carbon number. Examples thereof include 6 to 10 divalent aromatic hydrocarbon groups.

Examples of the divalent chain hydrocarbon group having 1 to 10 carbon atoms include alkanediyl groups such as methanediyl group, ethanediyl group, propanediyl group, butanediyl group;
Alkenediyl groups such as ethenediyl group, propenediyl group, butenediyl group;
Examples include alkynediyl groups such as ethynediyl group, propynediyl group, and butynediyl group.

Examples of the divalent alicyclic hydrocarbon group having 3 to 10 carbon atoms include monocyclic cycloalkanediyl groups such as cyclopropanediyl group, cyclobutanediyl group, cyclopentanediyl group, and cyclohexanediyl group;
A polycyclic cycloalkanediyl group such as a norbornanediyl group or an adamantanediyl group;
Monocyclic cycloalkenediyl groups such as cyclopropenediyl group, cyclobutenediyl group, cyclopentenediyl group, cyclohexenediyl group;
And polycyclic cycloalkenediyl groups such as norbornenediyl group.

Examples of the divalent aromatic hydrocarbon group having 6 to 10 carbon atoms include arylene groups such as a phenylene group and a tolylene group.

Examples of the substituent that these groups may have include a hydroxy group, a halogen atom, and an organic group having 1 to 20 carbon atoms. Examples of the organic group having 1 to 20 carbon atoms include alkyl groups such as a methyl group and an ethyl group, and alkanediyl groups bonded to the same carbon atom that R ¹ has.

R ¹ is preferably a substituted or unsubstituted methanediyl group and an unsubstituted ethanediyl group, more preferably an unsubstituted methanediyl group and a methanediyl group substituted with an alkanediyl group bonded to the same carbon atom of R ¹ , An unsubstituted methanediyl group is more preferred.

Examples of the divalent chain hydrocarbon group represented by R ² include the same groups as those exemplified as the divalent chain hydrocarbon group for R ¹ . Examples of the substituent that these groups may have include the same groups as the substituents exemplified in R ¹ above.

R ² is preferably a single bond, an unsubstituted alkanediyl group or an alkanediyl group substituted with an alkyl group, and a single bond, an unsubstituted methanediyl group, an unsubstituted ethanediyl group or a methanediyl group substituted with a methyl group Is more preferable.

A is preferably 1 or 2 from the viewpoint of easiness of synthesis or the like, and more preferably 1.

Examples of the ring structure having 3 to 20 ring members composed of R ¹ and at least ^one of one or a plurality of R ² and the carbon atom to which they are bonded include a cyclopropane structure, a cyclobutane structure, and a cyclopentane. Examples thereof include alicyclic structures such as a structure, cyclohexane structure, norbornane structure, and adamantane structure; and aliphatic heterocyclic structures such as an oxacyclopentane structure, a thiacyclopentane structure, and an azacyclopentane structure. Among these, an alicyclic structure is preferable and a cyclohexane structure is more preferable.

Examples of the monovalent group having two or more heteroatoms represented by A include a monovalent group having a chain structure and a monovalent cyclic group having a heterocyclic structure.

Examples of the hetero atom include an oxygen atom, a sulfur atom, a nitrogen atom, a silicon atom, and a phosphorus atom. In these, an oxygen atom, a sulfur atom, and a nitrogen atom are preferable, and an oxygen atom is more preferable.

Examples of the chain structure include a chain structure having an ester group (—COO—); a chain structure having —SO ₂ O—; a chain structure having a sulfone group (—SO ₂ —); and a sulfoxide group (— Chain structure having SO—); chain structure having amide group (—CONH—); sulfonimide group (—N (SO ₂ R) ₂ ), carboximide group (—N (COR) ₂ ), carvone Examples include a chain structure having an imide group such as an acid sulfonimide group (—N (COR) (SO ₂ R)); a chain structure having a sulfonamide group (—NHSO ₂ —); and combinations thereof.

Examples of the heterocyclic structure include a lactone structure; a lactam structure, a sultone structure; a cyclic sulfone structure; a cyclic sulfoxide structure; a cyclic amine structure; a cyclic sulfonimide structure, a cyclic carboxylic acid imide structure, and a cyclic carboxylic acid sulfonimide structure. Structure; cyclic sulfonamide structure; and combinations thereof. The cyclic amine structure includes those in which a carbonyl group or a sulfonyl group is bonded to the nitrogen atom of the cyclic amine structure.

Examples of the monovalent cyclic group having a heterocyclic structure include a group consisting only of a heterocyclic structure, a group consisting of a heterocyclic structure and another structure, and the like.

Examples of the other group include a monovalent hydrocarbon group having 1 to 10 carbon atoms, —CO—, —COO—, a divalent hydrocarbon group having 1 to 10 carbon atoms, and a group composed of a combination thereof. Is mentioned.

Examples of the monovalent hydrocarbon group include a group in which one hydrogen atom is bonded to one of the bonds of the R ¹ divalent hydrocarbon group exemplified above. Among these, a chain hydrocarbon group and an aromatic hydrocarbon group are preferable, an alkyl group and an aryl group are more preferable, and a methyl group, a tert-butyl group, and a phenyl group are further preferable.

Examples of the divalent hydrocarbon group include the same groups as those exemplified as the divalent hydrocarbon group for R ¹ . Among these, a chain hydrocarbon group is preferable, an alkanediyl group is more preferable, and a methyl group is more preferable.

The other group may be bonded to the carbon atom bonded to R ^2. The other group may be bonded to the heterocyclic structure at a portion other than the carbon atom bonded to R ² .

The monovalent group having two or more heteroatoms represented by A is preferably a monovalent cyclic group having a heterocyclic structure.
As the heterocyclic structure, a lactone structure, a lactam structure, a sultone structure, a cyclic sulfone structure, a cyclic sulfoxide structure, a cyclic amine structure, a cyclic imide structure, a cyclic sulfonamide structure, and a combination thereof are preferable, and a lactone structure is more preferable.

[A] The polymer has, as the structural unit (I), a structural unit represented by the following formula (2-1) (hereinafter also referred to as “structural unit (I-1)”), a structural unit represented by the following formula (2-2): And a combination thereof (hereinafter also referred to as “structural unit (I-2)”). That is, as the structural unit (I), for example, a structural unit represented by at least one of the following formulas (2-1) and (2-2) is preferable.

In the above formulas (2-1) and (2-2), Z is a group represented by the above formula (1). R ¹⁰ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

In the above formula (2-2), L is a single bond, —O—, —COO— or —CONH—.

R ¹⁰ is preferably a hydrogen atom and a methyl group, more preferably a methyl group, from the viewpoint of copolymerization of the monomer that gives the structural unit (I).

As the structural unit (I), structural units represented by the following formulas (2-1-1) to (2-1-24) (hereinafter referred to as “structural units (I-1-1) to (I-1 -24) ")) and the like.

In the above formulas (2-1-1) to (2-1-24), R ¹⁰ has the same meaning as in the above formulas (2-1) and (2-2).

Of these, the structural units (I-1-1) to (I-1-21) are preferable.

[A] The lower limit of the content ratio of the structural unit (I) of the polymer is preferably 1 mol%, more preferably 3 mol%, more preferably 5 mol% with respect to all structural units constituting the [A] polymer. Is more preferable, and 10 mol% is particularly preferable. As an upper limit of the said content rate, 90 mol% is preferable, 70 mol% is more preferable, 50 mol% is further more preferable, 30 mol% is especially preferable.

[A] By making the content rate of the structural unit (I) in a polymer into the said range, the lithography performance of the said radiation sensitive resin composition can be improved.

Examples of the monomer that gives the structural unit (I) include a compound represented by the following formula (i) (hereinafter also referred to as “compound (i)”).

In the above formula (i), R ¹ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms. R ² is a single bond or a substituted or unsubstituted divalent chain hydrocarbon group having 1 to 5 carbon atoms. R ¹ and at least ^one of one or a plurality of R ² may be combined with each other to form a ring structure having 3 to 20 ring members that is configured together with the carbon atom to which they are bonded. a is an integer of 1 to 3. When a is 2 or more, a plurality of R ² may be the same or different. R ¹⁰ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. A has two or more hetero atoms, a monovalent group having a carbon atom bonded to R ^2.

For example, when R ¹⁰ is a methyl group, R ¹ is a methanediyl group, R ² is a single bond, A is a 3-methyl-γ-butyrolactone-3-yl group, and a is 1, It can be synthesized simply and with good yield.

A compound represented by the above formula (i′-b) is reacted with a compound represented by the above formula (i′-a) and iodomethane in a solvent such as acetone in the presence of a base such as potassium carbonate. Obtainable. Next, the compound represented by the above formula (i′-c) can be obtained by reacting this compound (i′-b) with sulfuryl chloride in a solvent such as hexane. Further, the compound (i′-c) and methacrylic acid are reacted in a solvent such as N, N-dimethylformamide (DMF) in the presence of potassium carbonate and potassium iodide to thereby give the compound (i′-c). ) Is generated. The resulting product can be isolated by purification by solvent washing, column chromatography, recrystallization, distillation and the like.

[Structural unit (II)]
The structural unit (II) is a structural unit other than the structural unit (I) and includes an acid dissociable group. The “acid-dissociable group” is a group that replaces a hydrogen atom of a polar group such as a carboxy group or a phenolic hydroxyl group, and is a group that dissociates by the action of an acid. [A] When the polymer has the structural unit (II), the sensitivity of the radiation-sensitive resin composition is improved, and as a result, the lithography performance can be improved.

Examples of the structural unit (II) include a structural unit represented by the following formula (3-1) (hereinafter also referred to as “structural unit (II-1)”) and a structure represented by the following formula (3-2). A unit (hereinafter also referred to as “structural unit (II-2)”).

In the above formula (3-1), R ¹² represents a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ¹³ is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ¹⁴ and R ¹⁵ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or 3 to 3 carbon atoms composed of these groups together with the carbon atom to which they are bonded. 20 alicyclic structures are represented.

In the above formula (3-2), R ¹⁶ represents a hydrogen atom or a methyl group. L ¹ is a single bond, —CCOO— or —CONH—. R ¹⁷ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ¹⁸ and R ¹⁹ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent oxyhydrocarbon group having 1 to 20 carbon atoms.

R ¹² is preferably a hydrogen atom and a methyl group, more preferably a methyl group, from the viewpoint of copolymerization of the monomer that gives the structural unit (II).

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁷ , R ¹⁸ and R ¹⁹ include monovalent chain carbonization having 1 to 20 carbon atoms. Examples thereof include a hydrogen group, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms represented by R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁷ , R ¹⁸ and R ¹⁹ include a methyl group, an ethyl group, and an n-propyl group. Alkyl groups such as i-propyl group;
An alkenyl group such as an ethenyl group, a propenyl group, a butenyl group;
Examples thereof include alkynyl groups such as ethynyl group, propynyl group and butynyl group.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁷ , R ¹⁸ and R ¹⁹ include monocyclic rings such as a cyclopentyl group and a cyclohexyl group. A cycloalkyl group of
A monocyclic cycloalkenyl group such as a cyclopentenyl group and a cyclohexenyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group and a tricyclodecyl group;
Examples thereof include polycyclic cycloalkenyl groups such as norbornenyl group and tricyclodecenyl group.

Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁷ , R ^18, and R ¹⁹ include a phenyl group, a tolyl group, a xylyl group, and a naphthyl group. Group, an aryl group such as an anthryl group;
Examples thereof include aralkyl groups such as benzyl group, phenethyl group, naphthylmethyl group and anthrylmethyl group.

Examples of the alicyclic structure having 3 to 20 carbon atoms composed of the above-described groups combined with the carbon atom to which they are bonded include, for example, a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, a cycloheptane structure, a cyclo Monocyclic cycloalkane structures such as octane structures;
Examples thereof include polycyclic cycloalkane structures such as a norbornane structure, an adamantane structure, a tricyclodecane structure, and a tetracyclododecane structure.

As the hydrocarbon group represented by R ¹³ , R ¹⁴ and R ¹⁵ , a chain hydrocarbon group and an alicyclic hydrocarbon group are preferable.

Examples of the monovalent oxyhydrocarbon group having 1 to 20 carbon atoms represented by R ¹⁸ and R ¹⁹ include, for example, 1 carbon atom of R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁷ , R ¹⁸ and R ^19. Examples of the monovalent hydrocarbon group of ˜20 include those containing an oxygen atom at the terminal on the bond side.

As the structural unit (II-1), structural units represented by the following formulas (3-1-1) to (3-1-5) (hereinafter referred to as “structural units (II-1-1) to (II-1) −5) ”) is preferred.

The structural unit (II-2) is preferably a structural unit represented by the following formula (3-2-1) (hereinafter also referred to as “structural unit (II-2-1)”).

In the above formulas (3-1-1) to (3-1-5), R ¹² to R ¹⁵ have the same meanings as the above formula (3-1). R ^{13 ′} , R ^{14 ′} and R ^{15 ′} are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms. np is each independently an integer of 1 to 4.

In the above formula (3-2-1), R ¹⁶ to R ¹⁹ have the same meaning as in the above formula (3-2).

Examples of the structural units (II-1-1) to (II-1-5) include structural units represented by the following formulas.

In the above formula, R ¹² has the same meaning as in the above formula (3-1).

Among these, structural units derived from 2-alkyl-2-adamantyl (meth) acrylate, structural units derived from 1-alkyl-1-cyclopentyl (meth) acrylate, 2- (1-adamantyl) -2-propyl Structural units derived from (meth) acrylate, structural units derived from 2-alkyl-2-tetracyclododecan-yl (meth) acrylate, structures derived from 2- (1-cyclohexyl) -2-propyl (meth) acrylate Preference is given to units, structural units derived from t-decane-yl (meth) acrylate and structural units derived from 1-alkyl-1-cyclooctyl (meth) acrylate.

Examples of the structural unit (II-2) include a structural unit represented by the following formula.

In the above formula, R ¹⁶ has the same meaning as in the above formula (3-2).

The structural unit (II-2) is preferably a structural unit derived from p- (1-cyclohexylethoxyethoxy) styrene.

[A] When the polymer has the structural unit (II), the lower limit of the content ratio of the structural unit (II) is preferably 10 mol% with respect to the total structural units constituting the [A] polymer, Mole% is more preferable, and 30 mol% is more preferable. As an upper limit of the said content rate, 90 mol% is preferable, 80 mol% is more preferable, and 75 mol% is further more preferable. By making the content rate of structural unit (II) into the said range, the sensitivity of the said radiation sensitive resin composition can be raised more, and, as a result, lithography performance can be improved more.

[Structural unit (III)]
The structural unit (III) is a structural unit containing a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof (excluding the structural unit (I)). [A] The polymer further has the structural unit (III), so that the solubility in the developer can be appropriately adjusted. As a result, the lithography performance of the radiation-sensitive resin composition is further improved. be able to. Moreover, the adhesiveness of the resist pattern formed from the said radiation sensitive resin composition and a board | substrate can be improved.

Examples of the structural unit (III) include a structural unit represented by the following formula.

In the above formula, R ^L1 represents a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

Among these, the structural unit (III) is preferably a structural unit containing a lactone structure, more preferably a structural unit containing a norbornane lactone structure, a structural unit containing an oxynorbornane lactone structure, or a structural unit containing a γ-butyrolactone structure. , A structural unit derived from norbornanelactone-yl (meth) acrylate, a structural unit derived from cyano-substituted norbornanelactone-yl (meth) acrylate, a structural unit derived from oxynorbornanelactone-yl (meth) acrylate, and γ-butyrolactone- More preferred are structural units derived from 3-yl (meth) acrylate.

[A] When the polymer has the structural unit (III), the lower limit of the content ratio of the structural unit (III) is preferably 5 mol% with respect to all the structural units constituting the [A] polymer, Mole% is more preferable, and 25 mol% is more preferable. As an upper limit of the said content rate, 80 mol% is preferable, 70 mol% is more preferable, 60 mol% is further more preferable, 50 mol% is especially preferable. [A] By setting the content ratio of the structural unit (III) in the polymer within the above range, the solubility in the developer can be adjusted more appropriately. As a result, the lithography of the radiation-sensitive resin composition can be performed. The performance can be further improved. Moreover, the adhesiveness of the resist pattern formed from the said radiation sensitive resin composition and a board | substrate can be improved more.

[Structural unit (IV)]
The structural unit (IV) is a structural unit containing a polar group. [A] By further having the structural unit (IV), the polymer can adjust the solubility in the developer more appropriately, and as a result, improves the lithography performance of the radiation-sensitive resin composition. be able to. Moreover, the adhesiveness of the resist pattern formed from the said radiation sensitive resin composition and a board | substrate can be improved.

Examples of the polar group include a hydroxy group, an oxo group (═O), a carboxy group, a nitro group, a cyano group, and a sulfonamide group. Among these, a hydroxy group and a keto group are preferable.

Examples of the structural unit containing the polar group include a structural unit represented by the following formula.

In the above formula, R ^L2 represents a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[A] When a polymer has a structural unit (IV), as a minimum of the content rate of a structural unit (IV), 5 mol% is preferable with respect to all the structural units which comprise a [A] polymer, 10 Mole% is more preferable. As an upper limit of the said content rate, 50 mol% is preferable, 30 mol% is more preferable, 25 mol% is further more preferable, and 20 mol% is especially preferable.

[A] By setting the content ratio of the structural unit (IV) in the polymer within the above range, the solubility in the developer can be adjusted more appropriately. As a result, the lithography of the radiation-sensitive resin composition can be performed. The performance can be further improved. Moreover, the adhesiveness of the resist pattern formed from the said radiation sensitive resin composition and a board | substrate can be improved more.

[Structural unit (V)]
The structural unit (V) is a structural unit containing a fluorine atom. [A] The polymer can further have a structural unit (V) in addition to the structural unit (I) to adjust the fluorine atom content, and as a result, the polymer is formed from the radiation-sensitive resin composition. The dynamic contact angle on the resist film surface can be improved.

Examples of the structural unit (V) include the following structural unit (V-1) and structural unit (V-2).

[Structural unit (V-1)]
The structural unit (V-1) is a structural unit represented by the following formula (4a).

In said formula (4a), ^RD is a hydrogen atom, a methyl group, or a trifluoromethyl group. G is a single bond, an oxygen atom, a sulfur atom, —CO—O—, —SO ₂ —O—NH—, —CO—NH— or —O—CO—NH—. R ^E is a monovalent chain hydrocarbon group having 1 to 6 carbon atoms having at least one fluorine atom or a monovalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms having at least one fluorine atom. It is.

The chain hydrocarbon group having 1 to 6 carbon atoms having at least one fluorine atom represented by R ^E, such as trifluoromethyl group, 2,2,2-trifluoroethyl group, perfluoroethyl group 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoropropyl group, perfluoro n-propyl group, perfluoro i-propyl group, perfluoro n -Butyl group, perfluoro i-butyl group, perfluoro t-butyl group, 2,2,3,3,4,4,5,5-octafluoropentyl group, perfluorohexyl group and the like.

Examples of the aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms having at least one fluorine atom represented by R ^E, for example mono-fluoro cyclopentyl group, difluorocyclopentyl groups, perfluorocyclopentyl group, monofluoromethyl cyclohexyl group, Examples thereof include a difluorocyclopentyl group, a perfluorocyclohexylmethyl group, a fluoronorbornyl group, a fluoroadamantyl group, a fluorobornyl group, a fluoroisobornyl group, a fluorotricyclodecyl group, and a fluorotetracyclodecyl group.

Examples of the monomer that gives the structural unit (V-1) include trifluoromethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, 2,2,2-trimethyl ester, and the like. Fluoroethyloxycarbonylmethyl (meth) acrylic acid ester, perfluoroethyl (meth) acrylic acid ester, perfluoro n-propyl (meth) acrylic acid ester, perfluoro i-propyl (meth) acrylic acid ester, perfluoro n- Butyl (meth) acrylic acid ester, perfluoro i-butyl (meth) acrylic acid ester, perfluoro t-butyl (meth) acrylic acid ester, 2- (1,1,1,3,3,3-hexafluoropropyl ) (Meth) acrylic acid ester, 1- (2,2,3,3,4,4,5,5-octaf) (Olopentyl) (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) acrylic acid ester, 1- (2,2,3,3,3-pentafluoropropyl) (meth) acrylic acid ester, monofluorocyclopentyl (meth) Acrylic acid ester, difluorocyclopentyl (meth) acrylic acid ester, perfluorocyclopentyl (meth) acrylic acid ester, monofluorocyclohexyl (meth) acrylic acid ester, difluorocyclopentyl (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) acrylic Acid ester, fluoronorbornyl (meth) acrylic acid ester, fluoroadamantyl (meth) acrylic acid ester, fluorobornyl (meth) acrylic acid ester, fluoroisobornyl (Meth) acrylic acid esters, fluoro tricyclodecyl (meth) acrylate, fluoro tetracyclododecene decyl (meth) acrylic acid ester.

[A] When the polymer has the structural unit (V-1), the lower limit of the content ratio of the structural unit (V-1) is 5 mol% with respect to all the structural units constituting the [A] polymer. Is preferable, and 8 mol% is more preferable. As an upper limit of the said content rate, 80 mol% is preferable, 50 mol% is more preferable, 30 mol% is further more preferable, 20 mol% is especially preferable.

[A] By setting the content ratio of the structural unit (V-1) in the polymer within the above range, a higher dynamic contact angle on the resist film surface can be expressed during immersion exposure.

[Structural unit (V-2)]
The structural unit (V-2) is a structural unit represented by the following formula (4b).

In said formula (4b), R ^<F> is a hydrogen atom, a methyl group, or a trifluoromethyl group. R ²⁰ is an (s + 1) -valent hydrocarbon group having 1 to 20 carbon atoms, and an oxygen atom, a sulfur atom, —NR′—, a carbonyl group, —CO—O—, or a terminal at the R ²¹ side of R ²⁰ Also includes a structure in which —CO—NH— is bonded. R ′ is a hydrogen atom or a monovalent organic group. R ²¹ is a single bond, a divalent chain hydrocarbon group having 1 to 10 carbon atoms, or a divalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms. X ² is a C 1-20 divalent chain hydrocarbon group having at least one fluorine atom. A ¹ is an oxygen atom, —NR ″ —, —CO—O— *, or —SO ₂ —O— *. R ″ is a hydrogen atom or a monovalent organic group. * ^Indicates a binding site that binds to ^{R 22.} R ²² is a hydrogen atom or a monovalent organic group. s is an integer of 1 to 3. However, when s is 2 or 3, a plurality of R ²¹ , X ² , A ¹ and R ²² may be the same or different.

When R ²² is a hydrogen atom, it is preferable in that the solubility of [A] polymer in an alkaline developer can be improved.

Examples of the monovalent organic group represented by R ²² include an acid-dissociable group, an alkali-dissociable group, or a hydrocarbon group having 1 to 30 carbon atoms which may have a substituent.

Examples of the structural unit (V-2) include structural units represented by the following formulas (4b-1) to (4b-3).

In the above formulas (4b-1) to (4b-3), R ^{20 ′} is a divalent linear, branched or cyclic saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms. R ^F , X ² , R ²² and s are as defined in the above formula (4b). When s is 2 or 3, the plurality of X ² and R ²² may be the same or different.

[A] When the polymer has a structural unit (V-2), the lower limit of the content ratio of the structural unit (V-2) is 5 mol% with respect to all structural units constituting the [A] polymer. Is preferred. As an upper limit of the said content rate, 80 mol% is preferable, 60 mol% is more preferable, and 40 mol% is further more preferable. [A] By setting the content of the structural unit (V-2) in the polymer within the above range, the resist film surface formed from the radiation-sensitive resin composition has a reduced degree of dynamic contact angle in alkali development. Can be further improved.

[Structural unit (VI)]
The structural unit (VI) is a structural unit containing a group (z) having a hydroxy group at the terminal and a carbon atom adjacent to the hydroxy group having at least one fluorine atom or fluorinated alkyl group (provided that the structure Except unit (I) and structural unit (V)). [A] By having the structural unit (VI), the polymer can adjust the solubility in the developer more appropriately, and as a result, the lithography performance of the radiation-sensitive resin composition is further improved. be able to. Moreover, the sensitivity of the radiation sensitive resin composition in the case of EUV exposure can be increased.

Examples of the group (z) include a group represented by the following formula (z-1).

In the above formula (z-1), R ^f1 and R ^f2 are each independently an alkyl group having 1 to 10 carbon atoms or a fluorinated alkyl group having 1 to 10 carbon atoms. However, at least one of R ^f1 and R ^f2 is a fluorinated alkyl group.

Examples of the fluorinated alkyl group having 1 to 10 carbon atoms represented by R ^f1 and R ^f2 include a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a fluoroethyl group, a difluoroethyl group, a trifluoroethyl group, Examples include a pentafluoroethyl group, a hexafluoropropyl group, a heptafluoropropyl group, and a nonafluorobutyl group. Among these, a trifluoromethyl group and a pentafluoroethyl group are preferable, and a trifluoromethyl group is more preferable.

The group (z) is preferably a hydroxy-di (trifluoromethyl) methyl group, a hydroxy-di (pentafluoroethyl) methyl group or a hydroxy-methyl-trifluoromethylmethyl group, preferably a hydroxy-di (trifluoromethyl) group. A methyl group is more preferred.

Examples of the structural unit (VI) include structural units represented by the following formulas (5-1) to (5-9) (hereinafter also referred to as “structural units (VI-1) to (VI-9)”), etc. Is mentioned.

In the above formulas (5-1) to (5-9), R ^L3 is independently a hydrogen atom or a methyl group.

[A] When the polymer has a structural unit (VI), the lower limit of the content ratio of the structural unit (VI) is preferably 20 mol% with respect to all the structural units constituting the polymer [A], 30 Mole% is more preferable. As an upper limit of the said content rate, 80 mol% is preferable, 70 mol% is more preferable, and 60 mol% is further more preferable. [A] By setting the content ratio of the structural unit (VI) in the polymer within the above range, the solubility in the developer can be further appropriately adjusted. As a result, the lithography of the radiation-sensitive resin composition can be performed. The performance can be further improved. Moreover, the sensitivity of the said radiation sensitive resin composition in the case of EUV exposure can be improved more.

[Other structural units]
[A] The polymer may have other structural units other than the structural units (I) to (VI). Examples of the other structural unit include a structural unit containing a non-dissociable alicyclic hydrocarbon group. [A] When the polymer has the above-mentioned other structural units, the upper limit of the content ratio of the above-mentioned other structural units is preferably 20 mol% with respect to all the structural units constituting the [A] polymer. Mole% is more preferable.

The lower limit of the content of the [A] polymer in the radiation-sensitive resin composition is preferably 70% by mass, more preferably 80% by mass, based on the total solid content in the radiation-sensitive resin composition. 85 mass% is more preferable.

The radiation sensitive resin composition may contain one or more [A] polymers.

<[A] Polymer Synthesis Method>
[A] The polymer can be synthesized, for example, by polymerizing monomers that give each structural unit in a suitable solvent using a radical polymerization initiator or the like.

Examples of the radical polymerization initiator include azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2-cyclopropylpropylene). Pionitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), azo radical initiators such as dimethyl 2,2′-azobisisobutyrate; benzoyl peroxide, t-butyl hydroperoxide, And peroxide radical initiators such as cumene hydroperoxide. Of these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred, and AIBN is more preferred. These radical initiators can be used alone or in combination of two or more.

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

The lower limit of the reaction temperature in the polymerization is usually 40 ° C., and preferably 50 ° C. The upper limit of the reaction temperature is usually 150 ° C, preferably 120 ° C. The lower limit of the reaction time is usually 1 hour. The upper limit of the reaction time is usually 48 hours, preferably 24 hours.

[A] The lower limit of the weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is not particularly limited, but is preferably 1,000, more preferably 2,000, and further 3,000. Preferably, 5,000 is particularly preferable. The upper limit of the Mw is not particularly limited, but is preferably 50,000, more preferably 30,000, still more preferably 20,000, and particularly preferably 15,000. [A] By making Mw of a polymer into the said range, the applicability | paintability and development defect inhibitory property of the said radiation sensitive resin composition improve. [A] If the Mw of the polymer is less than the lower limit, a resist film having sufficient heat resistance may not be obtained. [A] If the Mw of the polymer exceeds the above upper limit, the developability of the resist film may deteriorate.

[A] The lower limit of the ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC of the polymer is usually 1. The upper limit of Mw / Mn is usually 5, preferably 3 and more preferably 2.

Mw and Mn of the polymer in this specification are values measured using gel permeation chromatography (GPC) under the following conditions.
GPC column: 2 "G2000HXL" from Tosoh Corporation, 1 "G3000HXL", 1 "G4000HXL" Column temperature: 40 ° C
Elution solvent: Tetrahydrofuran (Wako Pure Chemical Industries)
Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene

<[B] Acid generator>
[B] The acid generator is a substance that generates an acid upon exposure. The acid-dissociable group of the [A] polymer or the like is dissociated by the generated acid to generate a carboxy group or the like, and the solubility of the [A] polymer in the developer changes. A resist pattern can be formed from the object. The contained form of the [B] acid generator in the radiation-sensitive resin composition may be a low molecular compound form (hereinafter also referred to as “[B] acid generator” as appropriate), as described later. It may be a form incorporated as a part or both of these forms.

[B] Examples of the acid generator include onium salt compounds, N-sulfonyloxyimide compounds, halogen-containing compounds, diazoketone compounds, and the like.

Examples of the onium salt compounds include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, and the like.

Specific examples of the [B] acid generator include compounds described in paragraphs [0080] to [0113] of JP2009-134088A.

[B] The acid generator is preferably a compound represented by the following formula (7). [B] When the acid generator has the following structure, the diffusion length of the acid generated by exposure in the resist film is appropriately shortened by the interaction with the structural unit (I) of the polymer [A]. As a result, the lithography performance of the radiation sensitive resin composition can be improved.

In the above formula (7), R ²³ is a monovalent group containing an alicyclic structure having 6 or more ring members or a monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members. R ²⁴ is a fluorinated alkanediyl group having 1 to 10 carbon atoms. X ⁺ is a monovalent radiation-sensitive onium cation.

The “number of ring members” in R ²³ refers to the number of atoms constituting the ring of an alicyclic structure and an aliphatic heterocyclic structure, and in the case of a polycyclic alicyclic structure and a polycyclic aliphatic heterocyclic structure, The number of atoms that make up the ring.

Examples of the monovalent group having an alicyclic structure having 6 or more ring members represented by R ²³ include monocyclic groups such as a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, and a cyclododecyl group. A cycloalkyl group;
A monocyclic cycloalkenyl group such as a cyclohexenyl group, a cycloheptenyl group, a cyclooctenyl group, a cyclodecenyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetracyclododecyl group;
Examples thereof include polycyclic cycloalkenyl groups such as norbornenyl group and tricyclodecenyl group.

Examples of the monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members represented by R ²³ include a group containing a lactone structure such as a norbornanelactone-yl group;
A group containing a sultone structure such as a norbornane sultone-yl group;
An oxygen atom-containing heterocyclic group such as an oxacycloheptyl group and an oxanorbornyl group;
A nitrogen atom-containing heterocyclic group such as an azacycloheptyl group or a diazabicyclooctane-yl group;
And sulfur atom-containing heterocyclic groups such as a thiacycloheptyl group and a thianorbornyl group.

The lower limit of the ring members of groups denoted by R ^23, in view to be appropriate diffusion length of the above-mentioned acid is further preferred 8, 9, and still more preferably 10. The upper limit of the number of ring members is preferably 15 and more preferably 13 from the viewpoint that the acid diffusion length becomes more appropriate.

Among them, R ²³ is preferably a monovalent group containing an alicyclic structure having 9 or more ring members and a monovalent group containing an aliphatic heterocyclic structure having 9 or more ring members, an adamantyl group, a hydroxyadamantyl group A norbornanelactone-yl group and a 5-oxo-4-oxatricyclo [4.3.1.1 ^3,8 ] undecan-yl group are more preferred, and an adamantyl group is more preferred.

Examples of the fluorinated alkanediyl group having 1 to 10 carbon atoms represented by R ²⁴ include one or more hydrogen atoms of an alkanediyl group having 1 to 10 carbon atoms such as a methanediyl group, an ethanediyl group, and a propanediyl group. And a group in which is substituted with a fluorine atom. Among these, SO ₃ ^- fluorinated alkane diyl group which has a fluorine atom to carbon atom is bonded to adjacent groups are preferred, SO ₃ ^- 2 fluorine atoms to the carbon atom adjacent to the group is attached More preferred are fluorinated alkanediyl groups, 1,1-difluoromethanediyl group, 1,1-difluoroethanediyl group, 1,1,3,3,3-pentafluoro-1,2-propanediyl group, 1,1 1,2,2-tetrafluoroethanediyl group, 1,1,2,2-tetrafluorobutanediyl group and 1,1,2,2-tetrafluorohexanediyl group are more preferable.

The monovalent radiation-sensitive onium cation represented by X ⁺ is a cation that decomposes upon irradiation with radiation. In the exposed portion, sulfonic acid is generated from protons generated by the decomposition of the radiation-sensitive onium cation and sulfonate anions. Examples of the monovalent radiation-sensitive onium cation represented by X ⁺ include elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi. Examples include radiation-sensitive onium cations. Examples of the cation containing S (sulfur) as an element include a sulfonium cation and a tetrahydrothiophenium cation. Examples of the cation containing I (iodine) as an element include an iodonium cation. Among these, a sulfonium cation represented by the following formula (X-1), a tetrahydrothiophenium cation represented by the following formula (X-2), and an iodonium cation represented by the following formula (X-3) are: preferable.

In the above formula (X-1), R ^a1 , R ^a2 and R ^a3 each independently represent a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted group. aromatic hydrocarbon group having 6 to 12 carbon atoms, represents or is a -OSO ₂ -R ^P or _-SO 2 -R ^Q, or two or more are combined with each other configured ring of these groups . R ^P and R ^Q are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms. Or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2 and k3 are each independently an integer of 0 to 5. When R ^a1 ~ ^{R a3} and ^{R P} and ^{R Q} are a plurality each of the plurality of ^R a1 ^{~ R a3} and ^{R P} and ^{R Q} may be the same as or different from each other.

In the above formula (X-2), R ^b1 represents a substituted or unsubstituted linear or branched alkyl group having 1 to 8 carbon atoms or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms. It is. k4 is an integer of 0 to 7. If R ^b1 is plural, the plurality of R ^b1 may be the same or different, and plural R ^b1 may represent a constructed ring aligned with each other. R ^b2 is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. k5 is an integer of 0 to 6. If R ^b2 is plural, the plurality of R ^b2 may be the same or different, and plural R ^b2 may represent a keyed configured ring structure. q is an integer of 0 to 3.

In the above formula (X-3), R ^c1 and R ^c2 each independently represent a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number of 6 aromatic hydrocarbon group having to 12 represent two or more are combined with each other configured ring of -OSO ₂ -R ^R or _-SO 2 -R or ^S or those groups. R ^R and R ^S each independently represent a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms. Or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k6 and k7 are each independently an integer of 0 to 5. R ^c1, ^R c2, ^R when ^R and ^{R S} is plural respective plurality of ^R ^c1, R c2, ^{R R} and ^{R S} may have respectively the same or different.

Examples of the unsubstituted linear alkyl group represented by R ^a1 to R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Etc.

Examples of the unsubstituted branched alkyl group represented by R ^a1 to R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include i-propyl group, i-butyl group, sec-butyl group, t -A butyl group etc. are mentioned.

Examples of the unsubstituted aromatic hydrocarbon group represented by R ^a1 to R ^a3 , R ^c1 and R ^c2 include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a mesityl group, and a naphthyl group; a benzyl group, And aralkyl groups such as phenethyl group.

Examples of the unsubstituted aromatic hydrocarbon group represented by R ^b1 and R ^b2 include a phenyl group, a tolyl group, and a benzyl group.

Examples of the substituent that may be substituted for the hydrogen atom of the alkyl group and aromatic hydrocarbon group include a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, a hydroxy group, a carboxy group, and a cyano group. Nitro group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, acyloxy group and the like. Among these, a halogen atom is preferable and a fluorine atom is more preferable.

R ^a1 to R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include an unsubstituted linear or branched alkyl group, a fluorinated alkyl group, and an unsubstituted monovalent aromatic hydrocarbon group. , —OSO ₂ —R ″ and —SO ₂ —R ″ are preferred, fluorinated alkyl groups and unsubstituted monovalent aromatic hydrocarbon groups are more preferred, and fluorinated alkyl groups are more preferred. R ″ is an unsubstituted monovalent alicyclic hydrocarbon group or an unsubstituted monovalent aromatic hydrocarbon group.

In the above formula (X-1), k1, k2 and k3 are preferably integers of 0 to 2, more preferably 0 and 1, and even more preferably 0.

In the above formula (X-2), k4 is preferably an integer of 0 to 2, more preferably 0 and 1, and even more preferably 1. k5 is preferably an integer of 0 to 2, more preferably 0 and 1, and still more preferably 0.

In the above formula (X-3), k6 and k7 are preferably integers of 0 to 2, more preferably 0 and 1, and even more preferably 0.

X ⁺ is preferably a cation represented by the above formula (X-1), more preferably a triphenylsulfonium cation.

Examples of the acid generator represented by the above formula (7) include compounds represented by the following formulas (7-1) to (7-13) (hereinafter referred to as “compounds (7-1) to (7-13)”. ) ")) And the like.

In the above formulas (7-1) to (7-13), X ⁺ has the same meaning as in the above formula (7).

[B] Of these, the acid generator is preferably an onium salt compound, more preferably a sulfonium salt or a tetrahydrothiophenium salt, and the compound (7-1), compound (7-2), compound (7-12). And compound (7-13) are more preferable.

[B] As the lower limit of the content of the acid generator, when the [B] acid generator is a [B] acid generator, from the viewpoint of securing the sensitivity of the radiation-sensitive resin composition, the [A] polymer 0.1 mass part is preferable with respect to 100 mass parts, 0.5 mass part is more preferable, and 1 mass part is further more preferable. As an upper limit of the said content, 30 mass parts is preferable, 20 mass parts is more preferable, and 15 mass parts is further more preferable. [B] By making content of an acid generator into the said range, the sensitivity of the said radiation sensitive resin composition improves. The radiation-sensitive resin composition may contain one or more [B] acid generators.

<[C] Acid diffusion controller>
The said radiation sensitive resin composition may contain a [C] acid diffusion control body as needed. [C] The acid diffusion control body controls the diffusion phenomenon in the resist film of the acid generated from the [B] acid generator by exposure, has the effect of suppressing undesirable chemical reactions in the non-exposed areas, and the radiation sensitivity obtained The storage stability of the photosensitive resin composition is further improved, the resolution of the resist is further improved, and the change in the line width of the resist pattern due to fluctuations in the holding time from exposure to development processing can be suppressed, thereby stabilizing the process. A radiation-sensitive resin composition having excellent properties can be obtained. [C] The content of the acid diffusion controller in the radiation-sensitive resin composition is incorporated as a part of the polymer even in the form of a free compound (hereinafter referred to as “[C] acid diffusion controller” as appropriate). Or both of these forms.

[C] As the acid diffusion controller, for example, a compound represented by the following formula (8) (hereinafter also referred to as “nitrogen-containing compound (I)”), a compound having two nitrogen atoms in the same molecule (hereinafter referred to as “nitrogen-containing compound (I)”) "Nitrogen-containing compound (II)"), compounds having three nitrogen atoms (hereinafter also referred to as "nitrogen-containing compound (III)"), amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, etc. It is done.

In the above formula (8), R ²⁵ , R ²⁶ and R ²⁷ are each independently a hydrogen atom, an optionally substituted linear, branched or cyclic alkyl group, aryl group or aralkyl group. .

Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; aromatic amines such as aniline. It is done.

Examples of the nitrogen-containing compound (II) include ethylenediamine, N, N, N ′, N′-tetramethylethylenediamine, and the like.

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

Examples of the amide group-containing compound include formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone and the like. It is done.

Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tributylthiourea and the like.

Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N- (undecylcarbonyloxyethyl) morpholine; pyrazine, pyrazole and the like.

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

Further, as the [C] acid diffusion control agent, a photodegradable base that is exposed to light and generates a weak acid upon exposure can also be used. Examples of the photodegradable base include an onium salt compound that loses acid diffusion controllability by being decomposed by exposure. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (9-1), an iodonium salt compound represented by the following formula (9-2), and the like.

In the above formulas (9-1) and (9-2), R ²⁸ to R ³² are each independently a hydrogen atom, an alkyl group, an alkoxy group, a hydroxy group, or a halogen atom. E ⁻ and Q ⁻ are each independently OH ⁻ , R ^β —COO ⁻ , R ^β —SO ₃ ^— or an anion represented by the following formula (9-3). However, R ( ^beta) is an alkyl group, an aryl group, or an aralkyl group.

In the above formula (9-3), R ³³ represents a linear or branched alkyl group having 1 to 12 carbon atoms, in which part or all of the hydrogen atoms may be substituted with fluorine atoms, or 1 to 12 linear or branched alkoxyl groups. u is an integer of 0-2.

Examples of the photodegradable base include compounds represented by the following formulas.

Among these, the photodegradable base is preferably a sulfonium salt, more preferably a triarylsulfonium salt, and triphenylsulfonium 2.4.6. More preferred are triisopropyl phenyl sulfonate and triphenyl sulfonium 10-camphor sulfonate.

When the radiation sensitive resin composition contains a [C] acid diffusion controller as the [C] acid diffusion controller, the lower limit of the content of the [C] acid diffusion controller is 100 masses of the [A] polymer. 0.1 parts by mass is preferable with respect to parts, and 0.3 parts by mass is more preferable. As an upper limit of the said content, 20 mass parts is preferable, 15 mass parts is more preferable, and 10 mass parts is further more preferable. [C] By making content of an acid diffusion control agent into the said range, the lithography performance of the said radiation sensitive resin composition can be improved. [C] When the content of the acid diffusion controller exceeds the upper limit, the sensitivity of the radiation-sensitive resin composition may be lowered. The radiation-sensitive resin composition may contain one or more [C] acid diffusion controllers.

<[D] Polymer>
[D] The polymer is a polymer containing a fluorine atom (except for those corresponding to the [A] polymer). When the radiation-sensitive composition contains the [D] polymer, when the resist film is formed, the distribution is near the resist film surface due to the oil-repellent characteristics of the [D] polymer in the film. There is a tendency to be unevenly distributed, and it is possible to prevent the acid generator, the acid diffusion controller, and the like from being eluted into the immersion medium during immersion exposure. Further, due to the water repellency characteristics of the [D] polymer, the advancing contact angle between the resist film and the immersion medium can be controlled within a desired range, and the occurrence of bubble defects can be suppressed. Furthermore, the receding contact angle between the resist film and the immersion medium is increased, and high-speed scanning exposure is possible without leaving water droplets. Thus, when the said radiation sensitive resin composition contains a [D] polymer, the resist film suitable for an immersion exposure method can be formed.

[D] The polymer is not particularly limited as long as it is a polymer having a fluorine atom, but the fluorine atom content (% by mass) is higher than that of the [A] polymer in the radiation-sensitive resin composition. It is preferable. [A] When the fluorine atom content is higher than that of the polymer, the degree of uneven distribution described above becomes higher, and characteristics such as water repellency and elution suppression of the resulting resist film are improved.

[D] The lower limit of the fluorine atom content of the polymer is preferably 1% by mass, more preferably 2% by mass, further preferably 4% by mass, and particularly preferably 7% by mass. As an upper limit of the said content rate, 60 mass% is preferable, 40 mass% is more preferable, and 30 mass% is further more preferable. [D] If the fluorine atom content of the polymer is less than the lower limit, the hydrophobicity of the resist film surface may be lowered. The fluorine atom content (% by mass) of the polymer can be calculated from the structure of the polymer obtained by ¹³ C-NMR spectrum measurement.

[D] The polymer preferably has the fluorine atom-containing structural unit (V) in the above-mentioned [A] polymer. [D] The polymer may have one or more structural units (V).

[D] When the polymer has a structural unit (V), the lower limit of the content ratio of the structural unit (V) in the [D] polymer is 5 for all structural units constituting the [D] polymer. Mol% is preferable and 10 mol% is more preferable. As an upper limit of the said content rate, 90 mol% is preferable, 85 mol% is more preferable, and 80 mol% is further more preferable. By setting it as such a content rate, the resist film surface formed from the said radiation sensitive resin composition can improve the fall degree of a dynamic contact angle in alkali image development.

[D] The polymer may further have a structural unit containing an acid dissociable group. [D] When the polymer has a structural unit containing an acid dissociable group, the shape of the resulting resist pattern becomes better. Examples of the structural unit containing an acid dissociable group include the structural unit (II) in the above-described [A] polymer.

[D] When the polymer has a structural unit containing the acid dissociable group, the lower limit of the content ratio of the structural unit containing the acid dissociable group is [D] with respect to all structural units constituting the polymer. 5 mol% is preferable, 10 mol% is more preferable, and 15 mol% is further more preferable. As an upper limit of the said content rate, 90 mol% is preferable, 70 mol% is more preferable, 60 mol% is further more preferable, 50 mol% is especially preferable. When the content ratio of the structural unit containing an acid dissociable group is less than the above lower limit, development defects in the resist pattern may not be sufficiently suppressed. When the content ratio of the structural unit containing an acid dissociable group exceeds the above upper limit, the hydrophobicity of the resulting resist film surface may be lowered.

[Other structural units]
In addition to the above structural unit, the [D] polymer is, for example, a structural unit containing an alkali-soluble group; a structural unit containing a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof; a structure containing an alicyclic group You may have other structural units, such as a unit. Examples of the alkali-soluble group include a carboxy group, a sulfonamido group, and a sulfo group.

The upper limit of the content ratio of the above other structural units is usually 30 mol%, preferably 20 mol%, based on all structural units constituting the [D] polymer. When the content rate of said other structural unit exceeds the said upper limit, the pattern formation property of the said radiation sensitive resin composition may fall.

When the said radiation sensitive resin composition contains a [D] polymer, as a minimum of content of the [D] polymer in the said radiation sensitive resin composition, with respect to 100 mass parts of a [A] polymer. 0.5 parts by mass is preferable, and 1 part by mass is more preferable. As an upper limit of the said content, 20 mass parts is preferable, 15 mass parts is more preferable, and 10 mass parts is further more preferable. [D] If the content of the polymer exceeds the above upper limit, the pattern-forming property of the radiation-sensitive resin composition may be lowered.

<[E] solvent>
The radiation-sensitive resin composition usually contains an [E] solvent. [E] The solvent is particularly a solvent that can dissolve or disperse at least the [A] polymer, the [B] acid generator and the optionally contained [C] acid diffusion controller, [D] polymer, and the like. It is not limited. The radiation-sensitive resin composition may contain one or more [E] solvents.

[E] Examples of the solvent include alcohol solvents, ether solvents, ketone organic solvents, amide solvents, ester organic solvents, hydrocarbon solvents, and the like.

Examples of alcohol solvents include aliphatic monoalcohol solvents having 1 to 18 carbon atoms such as 4-methyl-2-pentanol and n-hexanol;
An alicyclic monoalcohol solvent having 3 to 18 carbon atoms such as cyclohexanol;
A polyhydric alcohol solvent having 2 to 18 carbon atoms such as 1,2-propylene glycol;
Examples thereof include polyhydric alcohol partial ether solvents having 3 to 19 carbon atoms such as propylene glycol monomethyl ether.

Examples of ether solvents include dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, diisoamyl ether, dihexyl ether, and diheptyl ether;
Cyclic ether solvents such as tetrahydrofuran and tetrahydropyran;
And aromatic ring-containing ether solvents such as diphenyl ether and anisole.

Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, 2-heptanone, ethyl-n-butyl ketone, methyl-n-hexyl ketone, Linear ketone solvents such as di-iso-butyl ketone and trimethylnonanone;
Cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone;
Examples include 2,4-pentanedione, acetonylacetone, acetophenone, and the like.

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

Examples of ester solvents include monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate;
Polyhydric alcohol carboxylate solvents such as propylene glycol acetate;
Polyhydric alcohol partial ether carboxylate solvents such as propylene glycol monomethyl ether acetate;
Polycarboxylic acid diester solvents such as diethyl oxalate;
Examples thereof include carbonate solvents such as dimethyl carbonate and diethyl carbonate.

Examples of the hydrocarbon solvent include aliphatic hydrocarbon solvents having 5 to 12 carbon atoms such as n-pentane and n-hexane;
Examples thereof include aromatic hydrocarbon solvents having 6 to 16 carbon atoms such as toluene and xylene.

Among these, ester solvents, ketone solvents and alcohol solvents are preferable, polyhydric alcohol partial ether acetate solvents, lactone solvents, cyclic ketone solvents and polyhydric alcohol partial ether solvents are more preferable, and propylene glycol. More preferred are monomethyl ether acetate, propylene glycol monomethyl ether, γ-butyrolactone and cyclohexanone.

<Other optional components>
The radiation-sensitive resin composition may contain other optional components in addition to the components [A] to [E]. Examples of the other optional components include uneven distribution accelerators, surfactants, alicyclic skeleton-containing compounds, and sensitizers. Each of these other optional components may be used alone or in combination of two or more.

[Uneven distribution promoter]
The uneven distribution accelerator is used to more efficiently apply the water-repellent polymer additive to the resist film surface when the radiation-sensitive resin composition contains the water-repellent polymer additive as the [D] polymer. It has an effect of segregation. By adding this uneven distribution accelerator to the radiation sensitive resin composition, the amount of the water-repellent polymer additive added can be reduced as compared with the conventional case. Therefore, it is possible to further suppress the elution of components from the resist film to the immersion liquid without impairing the resolution, LWR performance, and defect suppression, or to perform immersion exposure at a higher speed by high-speed scanning. As a result, it is possible to improve the hydrophobicity of the resist film surface that suppresses immersion-derived defects such as watermark defects. Examples of such an uneven distribution promoter include low molecular compounds having a relative dielectric constant of 30 or more and 200 or less and a boiling point at 1 atm of 100 ° C. or more. Specific examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, and polyhydric alcohols.

Examples of the lactone compound include γ-butyrolactone, valerolactone, mevalonic lactone, norbornane lactone, and the like.

Examples of the carbonate compound include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate and the like.

Examples of the nitrile compound include succinonitrile.

Examples of the polyhydric alcohol include glycerin.

When the radiation-sensitive resin composition contains an uneven distribution accelerator, the lower limit of the content of the uneven distribution accelerator is 10 mass with respect to 100 parts by mass of the total amount of the polymer in the radiation-sensitive resin composition. Part is preferable, 15 parts by mass is more preferable, 20 parts by mass is further preferable, and 25 parts by mass is particularly preferable. As an upper limit of the said content, 500 mass parts is preferable, 300 mass parts is more preferable, 200 mass parts is further more preferable, 100 mass parts is especially preferable.

(Surfactant)
Surfactants have the effect of improving coatability, striation, developability, and the like. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol diacrylate. Nonionic surfactants such as stearate; commercially available products include “KP341” from Shin-Etsu Chemical Co., Ltd., “Polyflow No. 75, No. 95” from Kyoeisha Chemical Co., Ltd., “F-Top EF301, EF303, EF352 ", DIC's" MegaFuck F171, F173 ", Sumitomo 3M's" Florard FC430, FC431 ", Asahi Glass Industry's" Asahi Guard AG710, Surflon S- " 82, SC-101, SC-102, the SC-103, the SC-104, the SC-105, the SC-106 ", and the like. When the radiation sensitive resin composition contains a surfactant, the upper limit of the content of the surfactant in the radiation sensitive resin composition is usually 2 parts by mass with respect to 100 parts by mass of the polymer [A]. It is.

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

Examples of the alicyclic skeleton-containing compound include adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and 1-adamantanecarboxylic acid t-butyl;
Deoxycholic acid esters such as t-butyl deoxycholic acid, t-butoxycarbonylmethyl deoxycholic acid, 2-ethoxyethyl deoxycholic acid;
Lithocholic acid esters such as tert-butyl lithocholic acid, tert-butoxycarbonylmethyl lithocholic acid, 2-ethoxyethyl lithocholic acid;
3- [2-hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] nonane, and the like. When the said radiation sensitive resin composition contains an alicyclic skeleton containing compound, as an upper limit of content of the alicyclic skeleton containing compound in the said radiation sensitive resin composition, it is [A] 100 mass parts of polymers. On the other hand, it is usually 5 parts by mass.

(Sensitizer)
A sensitizer exhibits the effect | action which increases the production amount of the acid from [B] acid generator etc., and there exists an effect which improves the "apparent sensitivity" of the said radiation sensitive resin composition.

Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines, and the like. These sensitizers may be used alone or in combination of two or more. When the said radiation sensitive resin composition contains a sensitizer, as an upper limit of content of the sensitizer in the said radiation sensitive resin composition, it is 2 mass parts normally with respect to 100 mass parts of [A] polymers. It is.

<Method for preparing radiation-sensitive resin composition>
The said radiation sensitive resin composition can be prepared by mixing a [A] polymer, a [B] acid generator, the arbitrary component contained as needed, and a [E] solvent in a predetermined ratio, for example. The radiation-sensitive resin composition is preferably filtered after mixing with, for example, a filter having a pore size of about 0.2 μm. As a minimum of solid content concentration of the radiation sensitive resin composition, 0.1 mass% is preferred, 0.5 mass% is more preferred, 1 mass% is still more preferred, and 1.5 mass% is especially preferred. The upper limit of the solid content concentration of the radiation-sensitive resin composition is preferably 50% by mass, more preferably 30% by mass, still more preferably 20% by mass, and particularly preferably 10% by mass.

<Resist pattern formation method>
The resist pattern forming method includes a step of forming a resist film (hereinafter also referred to as “resist film forming step”), a step of exposing the resist film (hereinafter also referred to as “exposure step”), and the exposed resist. Process of developing the film (hereinafter also referred to as “development process”)
The resist film is formed from the radiation-sensitive resin composition.

According to the resist pattern forming method, since the radiation sensitive resin composition described above is used, while exhibiting excellent MEEF performance, depth of focus, and exposure margin, LWR and CDU are small, resolution is high, It is possible to form a resist pattern that is excellent in rectangular shape in cross section. Hereinafter, each step of the resist pattern forming method will be described.

[Resist film forming step]
In this step, a resist film is formed from the radiation sensitive resin composition. Examples of the substrate on which the resist film is formed include conventionally known ones such as a silicon wafer, silicon dioxide, and a wafer coated with aluminum. Further, for example, an organic or inorganic antireflection film disclosed in Japanese Patent Publication No. 6-12452 and Japanese Patent Application Laid-Open No. 59-93448 may be formed on the substrate. Examples of the coating method include spin coating (spin coating), cast coating, and roll coating. After application, pre-baking (PB) may be performed as needed to volatilize the solvent in the coating film. As a minimum of PB temperature, it is usually 60 ° C and 80 ° C is preferred. As an upper limit of PB temperature, it is 140 degreeC normally and 120 degreeC is preferable. The lower limit of the PB time is usually 5 seconds, and preferably 10 seconds. The upper limit of the PB time is usually 600 seconds, and preferably 300 seconds. The lower limit of the average thickness of the resist film to be formed is preferably 10 nm. The upper limit of the average thickness is preferably 1,000 nm, and more preferably 500 nm.

[Exposure process]
In this step, the resist film formed in the resist film forming step is exposed by irradiation with radiation through a photomask or the like (in some cases through an immersion medium such as water). Examples of radiation include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), X-rays, and γ rays, and charged particle beams such as electron beams and α rays, depending on the line width of the target pattern. Is mentioned. Among these, far ultraviolet rays, EUV and electron beams are preferable, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV and electron beams are more preferable, and ArF excimer laser light, EUV and electron beams are more preferable. Further preferred.

When exposure is performed by immersion exposure, examples of the immersion liquid to be used include water and a fluorine-based inert liquid. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has a refractive index temperature coefficient that is as small as possible so as to minimize distortion of the optical image projected onto the film. In the case of excimer laser light (wavelength 193 nm), it is preferable to use water from the viewpoints of availability and easy handling in addition to the above-described viewpoints. When water is used, an additive that reduces the surface tension of water and increases the surface activity may be added in a small proportion. This additive is preferably one that does not dissolve the resist film on the wafer and can ignore the influence on the optical coating on the lower surface of the lens. The water used is preferably distilled water.

After the exposure, post-exposure baking (PEB) is performed, and in the exposed part of the resist film, the acid-dissociable group of the [A] polymer and the like by the acid generated from the [B] acid generator by exposure is dissociated. Is preferably promoted. This PEB causes a difference in solubility in the developer between the exposed area and the unexposed area. As a minimum of PEB temperature, it is 50 ° C usually and 80 ° C is preferred. The upper limit of the PEB temperature is usually 180 ° C, preferably 130 ° C. The lower limit of the PEB time is usually 5 seconds, and preferably 10 seconds. The upper limit of the PEB time is usually 600 seconds, and preferably 300 seconds.

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

As the developer used for the above development, in the case of alkali development, for example, 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, Examples thereof include an alkaline aqueous solution in which at least one alkaline compound such as 1,5-diazabicyclo- [4.3.0] -5-nonene is dissolved. Among these, a TMAH aqueous solution is preferable, and a 2.38 mass% TMAH aqueous solution is more preferable.

In the case of organic solvent development, organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents and the like or solvents containing organic solvents can be mentioned. As said organic solvent, the 1 type (s) or 2 or more types of the solvent enumerated as the [B] solvent of the above-mentioned resin composition are mentioned, for example. Among these, ester solvents and ketone solvents are preferable. As the ester solvent, an acetate solvent is preferable, and n-butyl acetate is more preferable. The ketone solvent is preferably a chain ketone, more preferably 2-heptanone. As a minimum of content of the organic solvent in a developing solution, 80 mass% is preferred, 90 mass% is more preferred, 95 mass% is still more preferred, and 99 mass% is especially preferred. Examples of components other than the organic solvent in the developer include water and silicone oil.

As a developing method, for example, a method in which a substrate is immersed in a tank filled with a developer for a certain period of time (dip method), a method in which the developer is raised on the surface of the substrate by surface tension and is left stationary for a certain time (paddle method) ), A method of spraying the developer on the substrate surface (spray method), a method of continuously applying the developer while scanning the developer coating nozzle on the substrate rotating at a constant speed (dynamic dispensing method) Etc.

<Polymer>
The polymer of the present invention has a structural unit represented by the above formula (I). The said polymer can be used suitably as a polymer component of the said radiation sensitive resin composition mentioned above. The polymer is described above as the [A] polymer in the radiation-sensitive resin composition.

<Compound>
The compound of the present invention is represented by the above formula (i). Since the compound has a structure represented by the above formula (i), it is suitably used as a monomer compound in which the structural unit (I) is incorporated into the polymer. The compound is described above as a monomer that gives the structural unit (I) in the [A] polymer of the radiation-sensitive resin composition.

Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples. Each physical property measurement in the examples was performed by the following methods.

[Weight average molecular weight (Mw) and number average molecular weight (Mn)]
Using GPC columns (two "G2000HXL", one "G3000HXL", one "G4000HXL" from Tosoh Corporation), flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran (Wako Pure Chemical Industries, Ltd.), sample concentration: Measurement was performed by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard under the analysis conditions of 1.0% by mass, sample injection amount: 100 μL, column temperature: 40 ° C., detector: differential refractometer. The degree of dispersion (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[ ¹³ C-NMR analysis]
Using a nuclear magnetic resonance apparatus (“JNM-ECX400” manufactured by JEOL Ltd.), deuterated chloroform was used as a measurement solvent, and analysis was performed to determine the content ratio (mol%) of each structural unit in each polymer.

[Example 1] (Synthesis of Compound (Z-1))
To a 2,000 mL eggplant flask, 94.0 g (734 mmol) of α-acetyl-γ-butyrolactone, 112 g (807 mmol) of potassium carbonate, 125 g (881 mmol) of iodomethane and 600 g of acetone as a solvent were added and stirred at 55 ° C. for 6 hours. Next, the inorganic salt was removed by filtration, followed by concentration and purification by column chromatography to obtain 100 g (yield 96%) of a methyl-substituted product represented by the following formula (z-1).

Next, 50 g (352 mmol) of (z-1) obtained above and 100 mL of hexane were added to a 300 mL round bottom flask, and the mixture was stirred in a water bath under a nitrogen atmosphere. Thereto, 49.9 g (370 mmol) of sulfuryl chloride was slowly added dropwise. After completion of dropping, the mixture was stirred at room temperature for 3 hours. The solvent was distilled off to obtain 62.0 g (yield 100%) of a crude product represented by the following formula (z-2). This product was used in the next reaction without further purification. *

Into a 1,000 mL round bottom flask, 36.4 g (422 mmol) of methacrylic acid, 300 mL of DMF, 72.9 g (528 mmol) of potassium carbonate and 23.4 g (141 mmol) of potassium iodide were added and stirred at room temperature for 30 minutes. A solution obtained by dissolving (z-2) 62.0 (351 mmol) obtained above in 100 mL of DMF was slowly added dropwise thereto. After completion of dropping, the mixture was stirred at 45 ° C. for 4 hours. After completion of the reaction, ethyl acetate was added and the salt was removed by filtration. The obtained solution was washed with water, and then the solvent was distilled off. By purification by column chromatography, 59.6 g (yield 75%) of a compound represented by the following formula (Z-1) was obtained.

[Examples 2 to 21] (Synthesis of compounds (Z-2) to (Z-21))
A precursor represented by the following formulas (Z-2) to (Z-21) was synthesized by appropriately selecting a precursor and performing the same operation as in Example 1.

<Synthesis of Polymer> [Synthesis of [A] Polymer and [D] Polymer]
The monomers used for the synthesis of [A] polymer and [D] polymer are shown below.

The compounds (M-1), (M-5) to (M-7), (M-9), (M-12), and (M-13) represent the structural unit (II) and the compound ( M-2), (M-8), and (M-10) represent the structural unit (III), the compound (M-3) represents the structural unit (IV), and the compound (M-15) represents the structural unit (III). V), and the compound (M-4) gives other structural units. Compound (M-14) incorporates a structural unit having the structure of [B] acid generator in [A] polymer. The compound (M-16) is a monomer used in place of the structural unit (I) in the following synthesis examples.

[Example 22] (Synthesis of polymer (A-1))
Compound (M-1) 7.78 g (35 mol%), Compound (M-2) 5.65 g (35 mol%), Compound (M-3) 3.36 g (15 mol%) and Compound (Z-1 ) 3.22 g (15 mol%) was dissolved in 40 g of 2-butanone, and 0.78 g of AIBN (5 mol% based on the total monomers) was added as a radical polymerization initiator to prepare a monomer solution. Next, a 100 mL three-necked flask containing 20 g of 2-butanone was purged with nitrogen for 30 minutes and then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled with water and cooled to 30 ° C. or lower. The polymerization solution cooled in 400 g of methanol was added, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 80 g of methanol, filtered, and dried at 50 ° C. for 17 hours to synthesize a white powdery polymer (A-1) (15.2 g, yield 76). %). Mw of the polymer (A-1) was 7,300, and Mw / Mn was 1.53. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from (M-1), (M-2), (M-3) and (Z-1) was 34.3 mol%, respectively. 35.1 mol%, 14.6 mol% and 16.0 mol%.

[Examples 23 to 46, 48 and 49 and Synthesis Examples 1 to 5, 7 and 8] (Polymers (A-2) to (A-25), (A-27) and (A-28) and polymers) (Synthesis of (a-1) to (a-5), (a-7) and (a-8))
Each polymer was synthesized in the same manner as in Example 22 except that the types and amounts of monomers shown in Table 1 were used. “-” In Table 1 indicates that the corresponding monomer was not used.

[Example 47] (Synthesis of polymer (A-26))
Compound (M-4) 40.15 g (50 mol%), compound (M-5) 43.04 g (35 mol%), compound (Z-1) 16.8 g (15 mol%), radical polymerization initiator AIBN 3.82 g (5 mol% based on the total monomers) and t-dodecyl mercaptan 1 g were dissolved in 100 g of propylene glycol monomethyl ether, and the reaction temperature was maintained at 70 ° C. in a nitrogen atmosphere for 16 hours. I let you. After the completion of the polymerization reaction, the polymerization solution was dropped into 1,000 g of n-hexane to coagulate and purify the polymer. Next, 150 g of propylene glycol monomethyl ether was added to the polymer again, and then 150 g of methanol, 34 g of triethylamine and 6 g of water were further added, and a hydrolysis reaction was performed for 8 hours while refluxing at the boiling point. After completion of the hydrolysis reaction, the solvent and triethylamine were distilled off under reduced pressure, and the resulting polymer was dissolved in 150 g of acetone, then dropped into 2,000 g of water to solidify, and the resulting white powder was filtered, And dried for 17 hours to obtain a white powdery polymer (A-26) (65.7 g, yield 77%). Mw of the polymer (A-26) was 7,500, and Mw / Mn was 1.90. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from p-hydroxystyrene, (M-5) and (Z-1) was 50.3 mol%, 34.6 mol% and 15. It was 1 mol%.

[Synthesis Example 6] (Synthesis of Polymer (a-6)) A polymer (a-) was prepared in the same manner as in Example 47 except that the types and amounts of monomers shown in Table 1 were used. 6) was synthesized.

[Synthesis Example 9] (Synthesis of polymer (D-1))
82.2 g (70 mol%) of the compound (M-15) and 17.8 g (30 mol%) of the compound (M-12) were dissolved in 200 g of 2-butanone, and 0.46 g (total single amount) of AIBN was used as a radical polymerization initiator. The monomer solution was prepared by adding 1 mol% to the body. Next, a 500 mL three-necked flask containing 100 g of 2-butanone was purged with nitrogen for 30 minutes, and then heated to 80 ° C. with stirring, and the monomer solution prepared above was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled with water and cooled to 30 ° C. or lower. After replacing the solvent with 400 g of acetonitrile, the operation of adding 100 g of hexane and stirring to recover the acetonitrile layer was repeated three times. By replacing the solvent with propylene glycol monomethyl ether acetate, a solution containing 60.1 g of the polymer (D-1) was obtained (yield 60%). Mw of the polymer (D-1) was 15,000, and Mw / Mn was 1.90. As a result of ¹³ C-NMR analysis, the content ratios of structural units derived from (M-15) and (M-12) were 70.3 mol% and 29.7 mol%, respectively.

<Preparation of radiation-sensitive resin composition>
Each component used for preparation of each radiation sensitive resin composition is shown below.

[[B] acid generator]
Each structural formula is shown below.
B-1: Triphenylsulfonium 2- (adamantan-1-ylcarbonyloxy) -1,1,3,3,3-pentafluoropropane-1-sulfonate B-2: Triphenylsulfonium norbornane sultone-2-yloxy Carbonyl difluoromethanesulfonate B-3: Triphenylsulfonium 3- (piperidin-1-ylsulfonyl) -1,1,2,2,3,3-hexafluoropropane-1-sulfonate B-4: Triphenylsulfonium adamantane 1-yloxycarbonyldifluoromethanesulfonate

[[C] acid diffusion controller]
Each structural formula is shown below.
C-1: Triphenylsulfonium 2.4.6. Triisopropylphenylsulfonate C-2: Triphenylsulfonium 10-camphorsulfonate C-3: N- (n-undecan-1-ylcarbonyloxyethyl) morpholine C-4: Tri-n-pentylamine

[[E] solvent] E-1: Propylene glycol monomethyl ether acetate E-2: Cyclohexanone

[[F] uneven distribution promoter]
F-1: γ-butyrolactone

[Example 50]
[A] 100 parts by mass of (A-1) as a polymer, [B] 8.5 parts by mass of (B-1) as an acid generator, [C] (C-1) 2 as an acid diffusion controller 3 parts by weight, (D-1) 3 parts by weight as a [D] polymer, (E-1) 2,240 parts by weight and (E-2) 960 parts by weight as a solvent and [F] A radiation-sensitive resin composition (J-1) was prepared by mixing 30 parts by mass of (F-1) as an uneven distribution accelerator and filtering the obtained mixed solution through a membrane filter having a pore size of 0.2 μm. .

[Examples 51 to 74 and Comparative Examples 1 to 5]
Each radiation-sensitive resin composition was prepared in the same manner as in Example 50 except that the components having the types and contents shown in Table 2 were used.

[Example 75]
[A] 100 parts by mass of (A-1) as a polymer, [B] 20 parts by mass of (B-1) as an acid generator, [C] (C-1) 3.6 as an acid diffusion controller The radiation sensitive resin is obtained by mixing 4 parts by mass and (E-1) 4,280 parts by mass and (E-2) 1,830 parts by mass as [E] solvent and filtering through a membrane filter having a pore size of 0.2 μm. A composition (J-26) was prepared.

[Examples 76 to 102 and Comparative Examples 6 to 13]
Each radiation-sensitive resin composition was prepared in the same manner as in Example 75 except that the components of the types and contents shown in Table 3 were used.

<Formation of resist pattern>
[Formation of resist pattern (1)]
A 12-inch silicon wafer surface was coated with a composition for forming a lower antireflection film (“ARC66” from Brewer Science Co., Ltd.) using a spin coater (“CLEAN TRACK ACT12” from Tokyo Electron), and then 205 ° C. Was heated for 60 seconds to form a lower antireflection film having an average thickness of 105 nm. On this lower antireflection film, each of the radiation sensitive resin compositions described in Table 2 was applied using the above spin coater, and PB was performed at 90 ° C. for 60 seconds. Then, it cooled at 23 degreeC for 30 second, and formed the resist film with an average thickness of 90 nm. Next, this resist film was subjected to an optical condition of NA = 1.3 and dipole (Sigma 0.977 / 0.782) using an ArF excimer laser immersion exposure apparatus (“NSR-S610C” manufactured by NIKON). , Exposed through a 40 nm line and space (1L1S) mask pattern. After the exposure, PEB was performed at 90 ° C. for 60 seconds. Thereafter, the resist was alkali-developed using a 2.38 mass% TMAH aqueous solution as an alkali developer, washed with water, and dried to form a positive resist pattern. When forming the resist pattern, the exposure amount formed in a one-to-one line and space with a line width of 40 nm and a line width formed through a one-to-one line and space mask with a target dimension of 40 nm is an optimum exposure amount ( Eop).

[Formation of resist pattern (2)]
The above [Resist pattern formation (1)] except that in [Resist pattern formation (1)], the organic solvent was developed using n-butyl acetate instead of the TMAH aqueous solution, and washing with water was not performed. In the same manner as described above, a negative resist pattern was formed.

[Formation of resist pattern (3)]
Using a spin coater (“CLEAN TRACK ACT8” manufactured by Tokyo Electron Ltd.) on the surface of an 8-inch silicon wafer, each radiation sensitive resin composition described in Table 3 was applied, and PB was performed at 90 ° C. for 60 seconds. . Then, it cooled at 23 degreeC for 30 second, and formed the resist film with an average thickness of 50 nm. Next, the resist film was irradiated with an electron beam by using a simple electron beam drawing apparatus (“HL800D” manufactured by Hitachi, Ltd., output: 50 KeV, current density: 5.0 A / cm ² ). After irradiation, PEB was performed at 120 ° C. for 60 seconds. Thereafter, development was performed at 23 ° C. for 30 seconds using a 2.38 mass% TMAH aqueous solution as an alkali developer, washed with water, and dried to form a positive resist pattern.

[Formation of resist pattern (4)]
A negative resist pattern was prepared in the same manner as in the resist pattern formation (3) except that n-butyl acetate was used instead of the TMAH aqueous solution and the organic solvent was developed and no washing with water was performed. Formed.

<Evaluation>
About the resist pattern formed using the said radiation sensitive resin composition, it measures by the following method, LWR performance about a radiation sensitive resin composition, MEEF performance, CDU performance, resolution, rectangle of a cross-sectional shape , Depth of focus and exposure margin were evaluated. The evaluation results are shown in Tables 4 and 5. A scanning electron microscope (Hitachi High-Technologies “CG-4100”) was used for measuring the resist pattern. In addition, comparative examples serving as determination criteria in LWR performance, MEEF performance, CDU performance, resolution, depth of focus, and exposure margin are as follows. For Example 50, Comparative Example 1 and Comparative Example 2, and Examples 51 to 71 are used. Is Comparative Example 1 for Example 72, Comparative Example 3 for Example 72, Comparative Example 4 for Example 73, Comparative Example 5 for Example 74, Comparative Example 6 and Comparative Example 7 for Example 75, and Examples 76-96. Comparative Example 6 for Example 97, Comparative Example 8 for Example 97, Comparative Example 9 for Example 98, Comparative Example 10 for Example 99, Comparative Example 11 for Example 100, Comparative Example 12 for Example 101 Example 102 is Comparative Example 13.

[LWR performance]
The resist pattern formed by irradiating the exposure amount of Eop was observed from above the pattern using the scanning electron microscope. A total of 50 line widths were measured at arbitrary points, and a 3-sigma value was obtained from the distribution of the measured values, and this was defined as LWR performance. The LWR performance indicates that the smaller the value, the smaller the backlash of the line. When the LWR performance is 10% or more (LWR performance is 90% or less) when compared with the comparative example, the LWR performance is “good” and less than 10% (LWR performance is improved). When the value was over 90%), it was evaluated as “bad”.

[MEEF performance]
In the resist pattern that is resolved by irradiating with the exposure amount of Eop, the line width of the resist pattern formed by using the mask pattern having the line widths of 51 nm, 53 nm, 55 nm, 57 nm, and 59 nm is plotted on the vertical axis. The slope of the straight line when the pattern size was plotted on the horizontal axis was calculated, and this was taken as the MEEF performance. The MEEF performance indicates that the closer the value is to 1, the better the mask reproducibility. When the MEEF performance is 10% or more when the value is compared with that of the comparative example (MEEF performance value is 90% or less), the MEEF performance is less than 10% (MEEF performance is improved). When the value was over 90%), it was evaluated as “bad”.

[CDU performance]
The resist pattern formed by irradiating the exposure amount of Eop was observed from above the pattern using the scanning electron microscope. The line width is measured at 20 points in the range of 400 nm, the average value is obtained, the average value is measured at a total of 500 points, and the 3 sigma value is obtained from the distribution of the measured values, which is taken as the CDU performance. . The CDU performance indicates that the smaller the value, the smaller the line width variation in a long cycle. When the CDU performance is improved by 10% or more (the CDU performance value is 90% or less) when the value is compared with that of the comparative example, the improvement is less than 10% (the CDU performance is improved). When the value was over 90%), it was evaluated as “bad”.

[Resolution]
The dimension of the minimum resist pattern resolved by irradiating the exposure amount of Eop was measured, and this measured value was defined as the resolution. The resolution indicates that the smaller the value, the better the pattern can be formed. When the resolution is 10% or more when the value is compared with that of the comparative example (resolution value is 90% or less), “good” and less than 10% (solution) In the case of an image quality value of more than 90%, it was evaluated as “bad”.

[Rectangularity of the cross-sectional shape]
The cross-sectional shape of the resist pattern resolved by irradiating the exposure amount of Eop was observed, and the line width Lb in the middle in the height direction of the resist pattern and the line width La in the upper part of the resist pattern were measured. The rectangularity of the cross-sectional shape indicates that the closer the value is to 1, the more the resist pattern may be rectangular. The rectangularity of the cross-sectional shape is “good” when 0.9 ≦ (La / Lb) ≦ 1.1, and (La / Lb) <0.9 or 1.1 <(La / Lb). The case was evaluated as “bad”.

[Depth of focus]
In the resist pattern resolved by irradiating the exposure amount of Eop, the dimension when the focus is changed in the depth direction is observed, and the pattern dimension is 90% to 110% of the reference without any bridge or residue. The depth of entry in the depth direction was measured, and this measured value was defined as the depth of focus. The larger the value of the focal depth, the smaller the variation in the dimension of the pattern obtained when the focal position varies, and the higher the yield during device fabrication. Depth of focus is 10% or better when the value is compared with that of the comparative example (depth of focus is 110% or more), and better than 10% (depth of focus is less than 110%). ) Was evaluated as “bad”.

[Exposure margin]
In the range of the exposure amount including the Eop, the exposure amount was changed every 1 mJ / cm ² to form resist patterns, respectively, and the respective line widths were measured using the scanning electron microscope. From the relationship between the obtained line width and exposure amount, an exposure amount E (44) at which the line width becomes 44 nm and an exposure amount E (36) at which the line width becomes 36 nm are obtained, and the exposure margin = (E (36) − The exposure margin (%) was calculated from the equation of E (44)) × 100 / (optimum exposure amount). The larger the value of the exposure margin, the smaller the variation in the dimension of the pattern obtained when the exposure amount fluctuates, and the higher the yield during device fabrication. When the exposure margin is 10% or more when the value is compared with that of the comparative example (exposure margin is 110% or more), it is “good” and less than 10% (exposure). When the margin value was less than 110%, it was evaluated as “bad”.

Claims

The radiation sensitive resin composition containing the polymer which has a structural unit containing group represented by following formula (1), and a radiation sensitive acid generator.

(In formula (1), R 1 is a substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms. R 2 is a single bond or a substituted or unsubstituted 2 having 1 to 5 carbon atoms. R 1 and at least one of one or more R 2 form a ring structure having 3 to 20 ring members composed of carbon atoms to which they are bonded together and to which they are bonded. A is an integer of 1 to 3. When a is 2 or more, a plurality of R 2 may be the same or different, and A has two or more heteroatoms, (This is a monovalent group bonded to R 2 by a carbon atom. * Indicates a bonding site.)
The radiation-sensitive resin composition according to claim 1, wherein A in the formula (1) is a monovalent cyclic group having a heterocyclic structure.
The radiation sensitivity according to claim 2, wherein the heterocyclic structure is a lactone structure, a lactam structure, a sultone structure, a cyclic sulfone structure, a cyclic sulfoxide structure, a cyclic amine structure, a cyclic imide structure, a cyclic sulfonamide structure, or a combination thereof. Resin composition.
The sensitivity according to claim 1, wherein the polymer has a structural unit represented by the following formula (2-1), a structural unit represented by the following formula (2-2), or a combination thereof as the structural unit. Radiation resin composition.

(In the formulas (2-1) and (2-2), Z is a group represented by the above formula (1), and R 10 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. .
In the formula (2-2), L is a single bond, —O—, —COO— or —CONH—. )
The radiation sensitive resin composition according to claim 1, wherein a in the above formula (1) is 1.
The radiation sensitive resin composition according to claim 1, wherein R 2 in the formula (1) is a single bond.
The radiation sensitive resin composition according to claim 1, wherein R 1 in the formula (1) is a substituted or unsubstituted methanediyl group.
Forming a resist film;
A step of exposing the resist film, and a step of developing the exposed resist film,
A method for forming a resist pattern, wherein the resist film is formed from the radiation-sensitive resin composition according to claim 1.
A polymer having a structural unit represented by the following formula (I).

(In the formula (I), R 1 is a substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms. R 2 is a single bond or a substituted or unsubstituted 2 having 1 to 5 carbon atoms. R 1 and at least one of one or more R 2 form a ring structure having 3 to 20 ring members composed of carbon atoms to which they are bonded together and to which they are bonded. A is an integer of 1 to 3. When a is 2 or more, a plurality of R 2 may be the same or different, and R 10 is a hydrogen atom, a fluorine atom, a methyl group or A is a trifluoromethyl group, and A is a monovalent group having two or more heteroatoms and bonded to R 2 with a carbon atom.
A compound represented by the following formula (i).

(In the formula (i), R 1 is a substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms. R 2 is a single bond or a substituted or unsubstituted 2 having 1 to 5 carbon atoms. R 1 and at least one of one or more R 2 form a ring structure having 3 to 20 ring members composed of carbon atoms to which they are bonded together and to which they are bonded. A is an integer of 1 to 3. When a is 2 or more, a plurality of R 2 may be the same or different, and R 10 is a hydrogen atom, a fluorine atom, a methyl group or A is a trifluoromethyl group, and A is a monovalent group having two or more heteroatoms and bonded to R 2 with a carbon atom.