JP6241267B2 - Radiation-sensitive resin composition and resist pattern forming method - Google Patents

Description

  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 excellent 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, etc. 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 while improving the performance (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 11-212265 A JP 2003-5375 A JP 2008-83370 A

  The present invention has been made based on the above-described circumstances, and its purpose is to exhibit excellent MEEF performance, depth of focus and exposure margin, and LWR performance, CDU performance, resolution, and a rectangular shape in cross section. It is providing the radiation sensitive resin composition which can form the resist pattern excellent in property.

（式（１）中、Ｌは、炭素数１〜２０の２価の有機基である。Ｍは、置換若しくは非置換の２価の炭素数１〜２０の炭化水素基である。ＬとＭとは互いに合わせられこれらが結合する炭素原子と共に構成される環員数３〜２０の単環の脂環構造を形成してもよい。Ｒ^１は、炭素数１〜２０の１価の有機基である。） The invention made to solve the above problems includes an acid-dissociable group-containing polymer (hereinafter also referred to as “[A] polymer”), and a radiation-sensitive acid generator (hereinafter referred to as “[B] acid generator”. A first structural unit comprising a group represented by the following formula (1) (hereinafter also referred to as “group (1)”): (Hereinafter also referred to as “structural unit (I)”), and the radiation-sensitive acid generator contains an onium salt.

(In Formula (1), L is a C1-C20 bivalent organic group. M is a substituted or unsubstituted bivalent C1-C20 hydrocarbon group. L and M And may form a monocyclic alicyclic structure having 3 to 20 ring members composed of carbon atoms bonded to each other, and R ¹ is a monovalent organic group having 1 to 20 carbon atoms. is there.)

Another invention made to solve the above problems is as follows:
A resist pattern forming method comprising: forming a resist film; exposing the resist film; and developing the exposed resist film; and forming the resist film from the radiation-sensitive resin composition.

（式（Ｉ）中、Ｒ^５は、水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。Ｌは、炭素数１〜２０の２価の有機基である。Ｍは、置換若しくは非置換の炭素数１〜２０の２価の炭化水素基である。ＬとＭとは互いに合わせられこれらが結合する炭素原子と共に構成される環員数３〜２０の単環の脂環構造を形成してもよい。Ｒ^１は、炭素数１〜２０の１価の有機基である。） Yet another invention made to solve the above problems is as follows:
It is a polymer having a structural unit represented by the following formula (I).

(In Formula (I), R ⁵ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. L is a divalent organic group having 1 to 20 carbon atoms. M is a substituted or non-substituted group. A substituted divalent hydrocarbon group having 1 to 20 carbon atoms, L and M are combined with each other to form a monocyclic alicyclic structure having 3 to 20 ring members composed of carbon atoms to which they are bonded. R ¹ is a monovalent organic group having 1 to 20 carbon atoms.)

（式（ｉ）中、Ｒ^５は、水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。Ｌは、炭素数１〜２０の２価の有機基である。Ｍは、置換若しくは非置換の炭素数１〜２０の２価の炭化水素基である。ＬとＭとは互いに合わせられこれらが結合する炭素原子と共に構成される環員数３〜２０の単環の脂環構造を形成してもよい。Ｒ^１は、炭素数１〜２０の１価の有機基である。） Yet another invention made to solve the above problems is as follows:
It is a compound represented by the following formula (i).

(In formula (i), R ⁵ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. L is a divalent organic group having 1 to 20 carbon atoms. M is a substituted or non-substituted group. A substituted divalent hydrocarbon group having 1 to 20 carbon atoms, L and M are combined with each other to form a monocyclic alicyclic structure having 3 to 20 ring members composed of carbon atoms to which they are bonded. R ¹ is a monovalent organic group having 1 to 20 carbon atoms.)

Here, the “organic group” refers to 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.

  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 excellent. A 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 that is expected to be further miniaturized in the future.

<Radiation sensitive resin composition>
The radiation-sensitive resin composition contains a [A] polymer and a [B] acid generator, and can form a resist pattern having excellent LWR performance, CDU performance, resolution, and cross-sectional rectangularity. It can be used as a resist composition. In addition, the radiation-sensitive resin composition has, as suitable components, [C] acid diffusion controller, polymer other than [D] [A] polymer (hereinafter also referred to as “[D] polymer”) and [ E] It may contain a solvent, and may contain other optional components as long as the effects of the present invention are not impaired.

  The radiation-sensitive resin composition may contain only the base polymer as the polymer component, and may contain a water-repellent polymer additive in addition to the base polymer. “Base polymer” refers to a polymer that is a main component of a resist film formed from a radiation-sensitive resin composition, and preferably occupies 50% by mass or more based on the total polymer constituting the resist film. Refers to a polymer. Further, the “water-repellent polymer additive” is a polymer that tends to be unevenly distributed in the surface layer of the resist film to be formed by being contained in the radiation-sensitive resin composition. A polymer having higher hydrophobicity than the polymer serving as the base polymer tends to be unevenly distributed in the resist film surface layer, and can function as a water-repellent polymer additive. By containing the water-repellent polymer additive, the radiation-sensitive resin composition can suppress elution of acid generators and the like from the resist film, and the formed resist film surface exhibits a high dynamic contact angle. Therefore, the resist film surface can exhibit excellent water drainage characteristics. Accordingly, in the immersion exposure process, high-speed scan exposure can be performed without the necessity of separately forming an upper layer film for blocking the resist film surface and the immersion medium. When the said radiation sensitive resin composition contains a water-repellent additive, as content of a water-repellent polymer additive, 0.1 mass part-20 mass parts are preferable with respect to 100 mass parts of base polymers. 0.3 parts by mass to 15 parts by mass is more preferable, and 0.5 parts by mass to 10 parts by mass is more preferable. As content of the base polymer in the said radiation sensitive resin composition, 70 mass% or more is preferable with respect to the total solid in the said radiation sensitive resin composition, 80 mass% or more is more preferable, 85 mass% % Or more is more preferable.

In the radiation-sensitive resin composition, in order for the polymer to function well as the water-repellent polymer additive, the polymer constituting the water-repellent polymer additive is preferably a polymer having a fluorine atom. Moreover, it is more preferable that the fluorine atom content is larger than the fluorine atom content of the base polymer. If the fluorine atom content of the water-repellent polymer additive is larger than the fluorine atom content of the base polymer, the tendency of the water-repellent polymer additive to be unevenly distributed on the surface layer is further increased in the formed resist film. In addition, the characteristics resulting from the hydrophobicity of the water-repellent polymer additive such as high water drainage on the resist film surface are more effectively exhibited. The fluorine atom content of the polymer constituting the water-repellent polymer additive is preferably 1% by mass or more, more preferably 3% by mass or more, further preferably 5% by mass or more, and particularly preferably 7% by mass or more. In addition, this fluorine atom content rate (mass%) is computable from the structure of the polymer calculated | required by the measurement of < ¹³ > C-NMR.

As an aspect of the polymer component in the radiation sensitive resin composition, (1) [A] polymer as base polymer, (2) [A] polymer and water repellent polymer additive as base polymer [A] polymer as, (3) [A] polymer as base polymer and [D] polymer as water repellent polymer additive, (4) [D] polymer as base polymer, and The case where each contains the [A] polymer as a water-repellent polymer additive is mentioned.
Hereinafter, each structural component of the said radiation sensitive resin composition is demonstrated in order.

<[A] polymer>
[A] The polymer is a polymer containing an acid dissociable group and having the structural unit (I). The radiation-sensitive resin composition exhibits excellent MEEF performance, depth of focus, and exposure margin because the [A] polymer has the structural unit (I), and LWR performance, CDU performance, resolution, and It is possible to form a resist pattern with excellent cross-sectional rectangularity (these performances are hereinafter also referred to as “lithographic performances”). [A] The reason why the polymer has the above-described configuration and thus exhibits the above-mentioned effects is not necessarily clear, but can be inferred as follows, for example. That is, since the structural unit (I) has both an ester group and a carbonyl group, it has a high polarity. Therefore, the onium salt of the [B] acid generator can be more favorably dispersed in the resist film. Further, due to the high polarity described above, the [A] polymer can adjust the solubility in the developer to a more appropriate one. 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 is a second structural unit containing an acid dissociable group (hereinafter referred to as “structural unit (II)”). A structural unit (III) containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure and a sultone structure, a structural unit (IV) containing a polar group, and a fluorine atom-containing structural unit (V) It may have other structural units other than the structural units (I) to (V).

[A] The content of the acid dissociable group in the polymer is as follows: (1) When included as R ¹ in the structural unit (I), (2) When included in the structural unit (II), (3) The case of both is mentioned.

  [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 said formula (1), L is a C1-C20 bivalent organic group. M is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms. L and M may be combined with each other to form a monocyclic alicyclic structure having 3 to 20 ring members and a carbon atom to which they are bonded. R ¹ is a monovalent organic group having 1 to 20 carbon atoms.

  Examples of the divalent organic group having 1 to 20 carbon atoms represented by L include, for example, a divalent hydrocarbon group having 1 to 20 carbon atoms, a carbon-carbon boundary of the hydrocarbon group, or a terminal on the bond side. Examples include a group containing a divalent heteroatom-containing group, a group obtained by substituting part or all of the hydrogen atoms of the hydrocarbon group and the group containing a heteroatom-containing group.

  Examples of the divalent hydrocarbon group include a divalent chain hydrocarbon group, a divalent alicyclic hydrocarbon group, and a divalent aromatic hydrocarbon group.

Examples of the chain hydrocarbon group 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 alicyclic hydrocarbon group include a monocyclic cycloalkanediyl group such as a cyclopropanediyl group, a cyclobutanediyl group, a cyclopentanediyl group, and a 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 aromatic hydrocarbon group include arenediyl groups such as a benzenediyl group and a toluenediyl group.

  Examples of the hetero atom contained in the divalent hetero atom-containing group 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 divalent heteroatom-containing group include —O—, —CO—, —CS—, —NR′—, and combinations thereof. R ′ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

  L is preferably a divalent chain hydrocarbon group or a divalent alicyclic hydrocarbon group, more preferably an alkanediyl group or a cycloalkanediyl group, and even more preferably a methanediyl group or a cyclohexanediyl group.

  As a C1-C20 bivalent hydrocarbon group represented by said M, the group similar to the bivalent hydrocarbon group illustrated by said L, etc. are mentioned, for example. 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 a group obtained by adding one hydrogen atom to the L divalent organic group.

  As M, a substituted or unsubstituted methanediyl group is preferable. By using M as such a group, since two —CO— are close to each other, the dispersibility of the above-mentioned [B] acid generator can be further improved. As M, a substituted methanediyl group is more preferable. By making M a substituted methanediyl group, it is considered that the dispersibility of the [B] acid generator can be improved and the diffusion length of the acid generated from the [B] acid generator can be shortened more appropriately. As a substituent which substitutes a methanediyl group, the alkanediyl group couple | bonded with the same carbon atom which a methyl group, an acetyl group, and M have is preferable.

  Moreover, as M, a substituted or unsubstituted C2-C20 hydrocarbon group is also preferable. By using M as such a group, the solubility of the above-mentioned [A] polymer in the developer can be further improved, and the diffusion length of the acid generated from the above-mentioned [B] acid generator is more appropriately set. It is thought that it can be shortened. Of these, an unsubstituted ethanediyl group and an unsubstituted phenylene group are preferred.

  Examples of the monocyclic alicyclic structure having 3 to 20 ring members composed of carbon atoms to which L and M are bonded to each other include a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, and the like. It is done. Among these, a cyclohexane structure is preferable. When L and M constitute such a monocyclic alicyclic structure, the diffusion length of the acid generated from the [B] acid generator and the dispersion of the [B] acid generator are made appropriate. It is considered possible.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ¹ include, for example, a monovalent hydrocarbon group having 1 to 20 carbon atoms, a carbon-carbon boundary of the hydrocarbon group, or a terminal on the bond side. And groups containing a divalent heteroatom-containing group, a group obtained by substituting part or all of the hydrogen atoms of the hydrocarbon group and the group containing a heteroatom-containing group.

  Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include a chain hydrocarbon group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, and an aromatic group having 6 to 20 carbon atoms. A hydrocarbon group etc. are mentioned.

Examples of the chain hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a t-butyl group, and a pentyl group. An alkyl group;
Alkenyl groups such as ethenyl group, propenyl group, butenyl group, pentenyl group;
Examples include alkynyl groups such as ethynyl group, propynyl group, butynyl group, and pentynyl group.

Examples of the alicyclic hydrocarbon group include monocyclic cycloalkyl groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetracyclododecyl group;
A monocyclic cycloalkenyl group such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, a cyclohexenyl group;
And polycyclic cycloalkenyl groups such as a norbornenyl group and a tricyclodecenyl group.

Examples of the aromatic hydrocarbon group include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group;
Examples include aralkyl groups such as benzyl group, phenethyl group, naphthylmethyl group, and anthrylmethyl group.

R ¹ is preferably a group having a lactone structure, a group having a sultone structure, a group having a cyclic carbonate structure, or a group having OH.

Further, as the R ^1, preferable groups represented by the following formula (X).

In the formula (X), ^{R 2} is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ³ and R ⁴ are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or these groups are It represents an alicyclic structure having 3 to 20 carbon atoms that is configured together with the carbon atoms to which they are bonded. * Shows the site | part couple | bonded with the oxy group in the said Formula (1).

  The group represented by the above formula (X) has acid dissociability. When the group (X) has acid dissociation property, it is dissociated by the action of the acid generated from the [B] acid generator in the exposed area to generate a carboxy group from the group (1). The solubility with respect to a liquid can be improved more.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ² include the same groups as the monovalent hydrocarbon group having 1 to 20 carbon atoms exemplified as R ¹ .

R ² is preferably a methyl group, an ethyl group, or an adamantyl group.

Examples of the monovalent chain hydrocarbon having 1 to 10 carbon atoms represented by R ³ and R ⁴ include those having 1 to 10 carbon atoms among the chain hydrocarbon groups exemplified for R ^1. It is done.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ³ and R ⁴ include the same groups as the alicyclic hydrocarbon group exemplified for R ¹ .

Examples of the alicyclic structure having 3 to 20 carbon atoms configured together with the carbon atom to which R ³ and R ⁴ are combined and bonded to each other include a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, a cycloheptane structure, Monocyclic cycloalkane structures such as cyclooctane structures;
Examples thereof include polycyclic cycloalkane structures such as a norbornane structure, an adamantane structure, a tricyclodecane structure, and a tetracyclododecane structure.
Among these, a monocyclic cycloalkane structure is preferable, and a cyclopentane structure and a cyclohexane structure are more preferable.

  Examples of the structural unit (I) include structural units represented by the following formulas (2-1) to (2-3) (hereinafter also referred to as “structural units (I-1) to (I-3)”). Etc.

In the above formulas (2-1) to (2-3), Z is a group represented by the above formula (1). In the above formula (2-1) or (2-2), ^{R 5} and ^{R 6} are a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. In the above formula (2-2), A ¹ is a single bond, —O—, —COO— or —CONH—. In the above formula (2-3), ^{R 7} is a hydrogen atom or a methyl group. R ⁸ , R ⁹ and R ¹⁰ are each independently a hydrogen atom, a halogen atom, a hydroxy group or a monovalent organic group having 1 to 20 carbon atoms, or one or more R ⁸ , one or more Two or more of R ⁹ and R ¹⁰ represent a ring structure having 3 to 20 ring members that are combined with each other. a is an integer of 1 to 4. When a is 2 or more, the plurality of R ⁸ and R ⁹ may be the same or different. A ² is a single bond or a divalent organic group. R ¹⁰ and A 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.

  Z is preferably bonded to the oxy group with a carbon atom in the above formulas (2-1) and (2-2).

From the viewpoint of copolymerization of the monomer that gives the structural unit (I),
R ⁵ and R ⁶ are preferably a hydrogen atom or a methyl group, and more preferably a methyl group.
R ⁷ is preferably a hydrogen atom.

Examples of the divalent organic group represented by A ² include the same groups as those exemplified as the L divalent organic group.

Examples of the monovalent organic group R ^8, R ⁹ and carbon atoms represented by R ¹⁰ 1 to 20, for example, such as a monovalent organic group and similar groups exemplified as R ¹ above can be mentioned.
R ⁸ and R ⁹ are preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom.

R ¹⁰ is preferably a monovalent hydrocarbon group, more preferably a monovalent chain hydrocarbon group or a monovalent alicyclic hydrocarbon group, still more preferably an alkyl group or a cycloalkyl group, a methyl group, an ethyl group Group, cyclohexyl group and adamantyl group are particularly preferred.

Examples of the ring structure having 3 to 20 ring members formed by combining two or more of the one or more R ⁸ , one or more R ⁹ and R ¹⁰ with each other include, for example, a cyclopropane structure, a cyclobutane structure, a cyclo Examples thereof include an alicyclic structure such as a pentane structure, a cyclohexane structure, a norbornane structure, and an adamantane structure; an aliphatic heterocyclic structure such as an oxacyclopentane structure, a thiacyclopentane structure, and an azacyclopentane structure.

Examples of the ring structure having 3 to 20 ring members constituted by R ¹⁰ and A ² together with the carbon atom to which they are bonded include two of the above-mentioned one or plural R ⁸ , R ⁹ and R ^10. Examples thereof include ring structures similar to those exemplified as the ring structure constituted by combining the above.

  As a, 1 or 2 is preferable, and 1 is more preferable.

  As the structural unit (I-1), for example, a structural unit represented by the following formula (2-1-1) or (2-1-2) (hereinafter referred to as “structural unit (I-1-1) or ( I-1-2) ”is a structural unit represented by the following formula (2-2-1) as the structural unit (I-2) (hereinafter referred to as“ structural unit (I-2-1) ”). As the structural unit (I-3) is a structural unit represented by the following formulas (2-3-1) to (2-3-3) (hereinafter referred to as “structural unit (I-3-)”. 1) to (I-3-3) ”).

  Of these, the structural unit (I-1-1) is preferable.

  As the structural unit (I), structural units represented by the following formulas (2-1-1-1) to (2-1-1-10) (hereinafter referred to as “structural unit (I-1-1-1)”. ) To (I-1-1-10) ”).

  As a minimum of the content rate of structural unit (I), 1 mol% is preferable with respect to all the structural units which comprise a [A] polymer, 3 mol% is more preferable, 5 mol% is further more preferable, 10 mol % Is particularly preferred. As an upper limit of the content rate of structural unit (I), 90 mol% is preferable, 70 mol% is more preferable, 50 mol% is further more preferable, 30 mol% is especially preferable. By making the content rate of structural unit (I) 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 ⁵ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. L is a C1-C20 divalent organic group. M is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms. L and M may be combined with each other to form a monocyclic alicyclic structure having 3 to 20 ring members and a carbon atom to which they are bonded. R ¹ is a monovalent organic group having 1 to 20 carbon atoms.

For example, when R ⁵ is a methyl group, L is a methanediyl group, and M is a propane-2,2-diyl group, the compound (i) can be easily synthesized according to the following scheme.

In the above scheme, R ¹ has the same meaning as in the above formula (1).

The dimethyl compound represented by the above formula (i′-b) is obtained by reacting the compound represented by the above formula (i′-a) with iodomethane in a solvent such as acetone in the presence of a base such as potassium carbonate. Can be obtained. Next, the compound represented by the above formula (i′-c) can be obtained by hydrolyzing the dimethyl compound (i′-b) in the presence of a base such as lithium hydroxide.
The compound (i′-c) obtained above is reacted with a chlorinating agent such as oxalyl chloride in a solvent such as acetonitrile, and further, acetonitrile in the presence of a hydroxy compound represented by the above formula (Y) and a base such as triethylamine. The ester body represented by the above formula (i′-d) can be obtained by reacting in a solvent such as the above. Next, the bromo compound represented by the above formula (i′-e) is obtained by reacting this compound (i′-d) with a brominating agent such as pyridinium tribromide in a solvent such as tetrahydrofuran. Can do. Further, the compound (i′-e) and methacrylic acid are reacted in a solvent such as N, N-dimethylformamide (DMF) in the presence of a base such as potassium carbonate, whereby the compound (i ′) Generate. The resulting product can be isolated by purification by solvent washing, column chromatography, recrystallization, distillation and the like.

  In addition, compounds (i) other than the compound (i ′) can also be synthesized by the same method as described above.

[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” refers to a group that replaces a hydrogen atom such as a carboxy group or a phenolic hydroxyl group and 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). Unit (hereinafter also referred to as “structural unit (II-2)”) and the like.

In the above formula ^{(3-1), R 12} is 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 chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or these groups are It represents an alicyclic structure having 3 to 20 carbon atoms that is configured together with the carbon atoms to which they are bonded.
In said formula (3-2), R < ¹⁶ > is a hydrogen atom or a methyl group. L ¹ is a single bond, —CCOO— or —CONH—. R ¹⁷ , 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 or a methyl group, and 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 include the same groups as the monovalent hydrocarbon group having 1 to 20 carbon atoms exemplified in the above formula (X). It is done.

Examples of the monovalent chain hydrocarbon group having 1 to 10 carbon atoms or the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ¹⁴ and R ¹⁵ include, for example, R ³ and R ⁴ Examples thereof include the same groups as the exemplified monovalent chain hydrocarbon group having 1 to 10 carbon atoms or monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.

Examples of the alicyclic structure having 3 to 20 carbon atoms constituted by R ¹⁴ and R ¹⁵ together 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, Monocyclic cycloalkane structures such as cyclooctane structures;
Examples thereof include polycyclic cycloalkane structures such as a norbornane structure, an adamantane structure, a tricyclodecane structure, and a tetracyclododecane structure.

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

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 said formula (3-2-1), R < ¹⁶ > -R < ¹⁹ > is synonymous with said formula (3-2).

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

In said formula, R < ¹² > is synonymous with said 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 unit derived from (meth) acrylate, structural unit derived from 2-alkyl-2-tetracyclododecan-yl (meth) acrylate, structure derived from 2- (1-cyclohexyl) -2-propyl (meth) acrylate A unit, a structural unit derived from t-decane-yl (meth) acrylate, and a structural unit derived from 1-alkyl-1-cyclooctyl (meth) acrylate are preferred.

  Examples of the structural unit (II-2) include structural units represented by the following formulas.

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

  As the structural unit (II-2), a structural unit derived from p- (1-cyclohexylethoxyethoxy) styrene is preferable.

  As a content rate of structural unit (II), 10 mol%-90 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 20 mol%-80 mol% are more preferable, 30 mol% More preferred is ˜75 mol%. 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 at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure and a sultone structure (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.

  Of these, the structural unit (III) is preferably a structural unit containing a lactone structure, more preferably a structural unit containing a norbornane lactone structure, a structural unit containing an oxynorbornane lactone structure, or a structural unit containing a γ-butyrolactone structure. , Structural unit derived from norbornanelactone-yl (meth) acrylate, structural unit derived from cyano-substituted norbornanelactone-yl (meth) acrylate, structural unit derived from oxynorbornanelactone-yl (meth) acrylate, γ-butyrolactone- A structural unit derived from 3-yl (meth) acrylate is more preferable.

  The content ratio of the structural unit (III) is preferably 0 mol% to 80 mol%, more preferably 5 mol% to 70 mol%, more preferably 20 mol%, based on all structural units constituting the [A] polymer. -60 mol% is more preferable, and 25 mol%-50 mol% is especially preferable. [A] When the content of the structural unit (III) is within the above range, the polymer can adjust the solubility in the developer 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.

  As a structural unit containing the said polar group, the structural unit represented by a following formula etc. are mentioned, for example.

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

  [A] The content of the structural unit (IV) in the polymer is preferably 0 mol% to 50 mol%, and 0 mol% to 30 mol%, based on all structural units constituting the [A] polymer. More preferably, 5 mol% to 25 mol% is more preferable, and 10 mol% to 20 mol% is particularly preferable.

  [A] By setting the content of the structural unit (IV) in the above range, the polymer can adjust the solubility in the developer 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 and 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 and 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-octaful Lopentyl) (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] The content ratio of the structural unit (V-1) in the polymer is preferably 0 mol% to 80 mol%, and preferably 0 mol% to 50 mol, based on all structural units constituting the [A] polymer. % Is more preferable, 5 mol% to 30 mol% is further preferable, and 8 mol% to 20 mol% is particularly preferable.

  [A] A polymer can express the higher dynamic contact angle of the resist film surface at the time of immersion exposure by making the content rate of a structural unit (V-1) into the said range.

[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 a (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 divalent chain hydrocarbon group having 1 to 20 carbon atoms and 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 C 1-20 divalent linear, branched or cyclic saturated or unsaturated hydrocarbon group. 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] The content ratio of the structural unit (V-2) in the polymer is preferably 0% by mole to 80% by mole, and preferably 0% by mole to 60% by mole with respect to all the structural units constituting the [A] polymer. % Is more preferable, and 5 mol% to 40 mol% is more preferable.
[A] The polymer has the content ratio of the structural unit (V-2) within the above range, so that 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.

(Other structural units)
[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 said formula (z-1), ^Rf1 and ^Rf2 are respectively independently a C1-C10 alkyl group or a C1-C10 fluorinated alkyl group. 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.

  Examples of the group (z) include 1,1,1,3,3,3-hexafluoro-2-hydroxypropyl group, hydroxy-di (pentafluoroethyl) methyl group, 1,1,1, trifluoro-2. -A hydroxypropyl group is preferable and a 1,1,1,3,3,3-hexafluoro-2-hydroxypropyl group is more preferable.

  As the structural unit (VI), for example, structural units represented by the following formulas (5-1) to (5-9) (hereinafter also referred to as “structural units (VI-1) to (VI-9)”) and the like Is mentioned.

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

  [A] The content ratio of the structural unit (VI) in the polymer is preferably from 0 mol% to 80 mol%, and from 20 mol% to 70 mol%, based on all structural units constituting the [A] polymer. More preferably, it is more preferably 30 mol% to 60 mol%. [A] By setting the content ratio of the structural unit (VI) in the above range, the polymer can further adjust the solubility in the developer more appropriately. 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.

  [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. As a content rate of the said other structural unit, 20 mol% or less is preferable with respect to all the structural units which comprise a [A] polymer, and 10 mol% or less is more preferable.

  As content of the [A] polymer in the said radiation sensitive resin composition, 70 mass% or more is preferable with respect to the total solid in the said radiation sensitive resin composition, 80 mass% or more is more preferable, 85 mass% or more 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), azo radical initiators such as 2,2′-azobis (2,4-dimethylvaleronitrile), 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 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.

  As reaction temperature in the said superposition | polymerization, it is 40 to 150 degreeC normally, and 50 to 120 degreeC is preferable. The reaction time is usually 1 hour to 48 hours, preferably 1 hour to 24 hours.

  [A] 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 or more and 50,000 or less, more preferably 2,000 or more and 30,000 or less. Preferably, 3,000 or more and 20,000 or less are more preferable, and 5,000 or more and 15,000 are particularly preferable. [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 ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC of the polymer is usually from 1 to 5, preferably from 1 to 3, more preferably from 1 to 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 contains an onium salt and 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. In addition, it is considered that the [B] acid generator can improve the affinity with the [A] polymer having the highly polar structural unit (I) by containing an onium salt, and in the resist film Increased dispersibility. 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] 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 including 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;
And polycyclic cycloalkenyl groups such as a norbornenyl group and a 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;
Nitrogen atom-containing heterocyclic groups such as azacycloheptyl group and diazabicyclooctane-yl group;
And sulfur atom-containing heterocyclic groups such as a thiacycloheptyl group and a thianorbornyl group.

The number of ring members of the group represented by R ²³ is preferably 8 or more, more preferably 9 to 15 and even more preferably 10 to 13 from the viewpoint that the diffusion length of the acid described above becomes more appropriate.

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

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. And 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) preferable.

In the above formula (X-1), R ^a1 , R ^a2 and R ^a3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, substituted or unsubstituted. aromatic hydrocarbon group having 6 to 12 carbon atoms, a or 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. R ^a1 to R ^a3 and when ^{R P} and ^{R Q} are a plurality each of the plurality of ^R a1 ^{to 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 having 6 to 8 carbon atoms. It is a group. k4 is an integer of 0-7. 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 0-6. 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 0-3.
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 12 aromatic hydrocarbon group, or an -OSO ₂ -R ^R or _-SO 2 -R ^S, or two or more are combined with each other configured ring of these groups. R ^R and R ^S 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. 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, Examples include 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, 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.

As k1, k2, and k3 in the formula (X-1), integers of 0 to 2 are preferable, 0 or 1 is more preferable, and 0 is more preferable.
As k4 in the formula (X-2), an integer of 0 to 2 is preferable, 0 or 1 is more preferable, and 1 is more preferable. k5 is preferably an integer of 0 to 2, more preferably 0 or 1, and still more preferably 0.
As k6 and k7 in the formula (X-3), an integer of 0 to 2 is preferable, 0 or 1 is more preferable, and 0 is more preferable.

As said X ^<+> , the cation represented by the said Formula (X-1) is preferable, and a triphenylsulfonium cation is more preferable.

  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] Among these, the acid generator is preferably a sulfonium salt or a tetrahydrothiophenium salt. The compound (7-1), the compound (7-2), the compound (7-12), and the compound (7-13) are preferred. ) Is more preferable.

  In addition, as the [B] acid generator, a polymer in which the structure of the above formula (7), such as a polymer having a structural unit represented by the following formula (7-14), is incorporated as a part of the polymer is also available. preferable.

In said formula (7-14), R 'is a hydrogen atom or a methyl group. X ⁺ is synonymous with the above formula (7).

  [B] As 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, [A] 100 mass of the polymer. 0.1 parts by mass or more and 30 parts by mass or less are preferable, 0.5 parts by mass or more and 20 parts by mass or less are more preferable, and 1 part by mass or more and 15 parts by mass or less are 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; 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 and pyrazole.

  Moreover, the compound which has an acid dissociable group can also be used as said nitrogen-containing organic compound. 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 by 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 formula (9-1) and formula (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 an anion represented by OH ⁻ , R ^β —COO ⁻ , R ^β —SO ₃ ^— or 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 carbon atom. It is a -12 linear or branched alkoxyl group. u is an integer of 0-2.

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

  Of these, the photodegradable base is preferably a sulfonium salt, more preferably a triarylsulfonium salt, and triphenylsulfonium 2.4.6. Triisopropyl phenyl sulfonate and triphenyl sulfonium 10-camphor sulfonate are more preferable.

  [C] The content of the acid diffusion controller is 0 to 20 parts by mass with respect to 100 parts by mass of the polymer [A] when the [C] acid diffusion controller is a [C] acid diffusion controller. Preferably, 0.1 mass part-15 mass parts are more preferable, and 0.3 mass part-10 mass parts are 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 other than the [A] polymer. [D] As a polymer, (D-1) a fluorine atom-containing polymer (hereinafter also referred to as “(D-1) fluorine atom-containing polymer”) used as a water-repellent polymer additive, as a base polymer And a polymer having a structural unit containing an acid-dissociable group (hereinafter, also referred to as “(D-2) polymer”).

((D-1) Fluorine atom-containing polymer)
The radiation-sensitive composition contains (D-1) a fluorine atom-containing polymer, so that when the resist film is formed, the oil-repellent characteristics of the (D-1) fluorine atom-containing polymer in the film. Therefore, the distribution tends to be unevenly distributed in the vicinity of the resist film surface, and it is possible to suppress the acid generator, the acid diffusion controller, and the like from being eluted into the immersion medium during the immersion exposure. Further, due to the water repellency characteristics of the (D-1) fluorine atom-containing 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 (D-1) fluorine atom containing polymer, the resist film suitable for an immersion exposure method can be formed.

  (D-1) The fluorine atom-containing polymer is not particularly limited as long as it is a polymer having a fluorine atom, but the fluorine atom content rate ([A] polymer in the radiation sensitive resin composition ( (Mass%) is preferably large. [A] When the fluorine atom content is higher than that of the polymer, the degree of uneven distribution described above becomes higher, and the properties such as water repellency and elution suppression of the resulting resist film are improved.

(D-1) The fluorine atom content of the fluorine atom-containing polymer is preferably 1% by mass or more, more preferably 2% by mass to 60% by mass, further preferably 4% by mass to 40% by mass, and 7% by mass. -30 mass% is particularly preferred. (D-1) If the fluorine atom content of the fluorine atom-containing 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-1) The fluorine atom-containing polymer preferably has the fluorine atom-containing structural unit (V) in the above-described [A] polymer. (D-1) The fluorine atom-containing polymer may have one or more structural units (V).

  (D-1) As a content rate of the structural unit (V) in a fluorine atom containing polymer, (D-1) 0 mol%-90 mol% with respect to all the structural units which comprise a fluorine atom containing polymer. Preferably, 5 mol%-85 mol% are more preferable, and 10 mol%-80 mol% are 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-1) The fluorine atom-containing polymer may further have a structural unit containing an acid dissociable group. (D-1) Since the fluorine atom-containing 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.

  As a content rate of the structural unit containing the said acid dissociable group, 5 mol%-90 mol% are preferable with respect to all the structural units which comprise a (D-1) fluorine atom containing polymer, 10 mol%-70 mol. % Is more preferable, 15 mol% to 60 mol% is more preferable, and 15 mol% to 50 mol% is particularly 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]
Further, (D-1) the fluorine atom-containing polymer has at least one structure selected from the group consisting of, for example, a structural unit containing an alkali-soluble group, a lactone structure, a cyclic carbonate structure, and a sultone structure in addition to the above structural unit. And other structural units such as a structural unit containing alicyclic group. Examples of the alkali-soluble group include a carboxy group, a sulfonamido group, and a sulfo group.

  As a content rate of said other structural unit, it is 30 mol% or less normally with respect to all the structural units which comprise a (D-1) fluorine atom containing polymer, and 20 mol% or less is preferable. 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.

  As content of the (D-1) fluorine atom containing polymer in the said radiation sensitive resin composition, 0-20 mass parts is preferable with respect to 100 mass parts of [A] polymer, 0.5 mass part -15 mass parts is more preferable, and 1 mass part-10 mass parts is further more preferable. (D-1) When content of a fluorine atom containing polymer exceeds the said upper limit, the pattern formability of the said radiation sensitive resin composition may fall.

<(D-2) Polymer>
For example, when the [A] polymer is used as a water-repellent polymer additive, the radiation-sensitive resin composition preferably contains (D-2) a polymer as a base polymer.

  Examples of the (D-2) polymer include those having the structural units (II) to (V) and other structural units in the [A] polymer.

<[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 the alcohol solvent 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 C2-C18 polyhydric alcohol solvent such as 1,2-propylene glycol;
Examples include C3-C19 polyhydric alcohol partial ether solvents 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, Chain ketone solvents such as di-iso-butyl ketone and trimethylnonanone:
Cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone and methylcyclohexanone:
2,4-pentanedione, acetonylacetone, acetophenone and the like can be mentioned.

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. More preferred are monomethyl ether acetate, propylene glycol monomethyl ether, γ-butyrolactone, and cyclohexanone.

<Other optional components>
The said radiation sensitive resin composition may contain other arbitrary components other than said [A]-[E] component. 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]
When the radiation sensitive resin composition contains a water-repellent polymer additive as the (D-1) fluorine atom-containing polymer, the uneven distribution accelerator is more efficient for this water-repellent polymer additive. It has the effect of segregating on the resist film surface. 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, and norbornane lactone.
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.

  The content of the uneven distribution accelerator is preferably 10 parts by mass to 500 parts by mass, more preferably 15 parts by mass to 300 parts by mass with respect to 100 parts by mass of the total amount of the polymer in the radiation sensitive resin composition. 20 mass parts-200 mass parts are further more preferable, and 25 mass parts-100 mass parts are 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 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, manufactured by Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (above, manufactured by Tochem Products), MegaFuck F171, F173 (above, manufactured by DIC), Florard FC430, FC431 (above, Sumitomo 3M) Manufactured by Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, manufactured by Asahi Glass Industrial Co., Ltd.) Can be mentioned. As content of surfactant in the said radiation sensitive resin composition, it is 2 mass parts or less normally with respect to 100 mass parts of [A] polymers.

(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 deoxycholate, t-butoxycarbonylmethyl deoxycholic acid, 2-ethoxyethyl deoxycholic acid;
Lithocholic acid esters such as t-butyl lithocholic acid, t-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. As content of the alicyclic skeleton containing compound in the said radiation sensitive resin composition, it is 5 mass parts or less normally with respect to 100 mass parts of [A] polymers.

(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. As content of the sensitizer in the said radiation sensitive resin composition, it is 2 mass parts or less normally with respect to 100 mass parts of [A] polymers.

<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 solid content concentration of the said radiation sensitive resin composition, 0.1 mass%-50 mass% are preferable, 0.5 mass%-30 mass% are more preferable, 1 mass%-20 mass% are more preferable, 1.5 mass%-10 mass% are especially preferable.

<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, Japanese Patent Application Laid-Open No. 59-93448, or the like 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 PB temperature, it is 60 to 140 degreeC normally, and 80 to 120 degreeC is preferable. The PB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds. The thickness of the resist film to be formed is preferably 10 nm to 1,000 nm, and more preferably 10 nm to 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 preferable. Further preferred.

  When the 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 PEB temperature, it is 50 to 180 degreeC normally, and 80 to 130 degreeC is preferable. The PEB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 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 a developer used for the above development,
In the case of alkaline 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, 1,5-diazabicyclo- [4. 3.0] -5 aqueous solution in which at least one alkaline compound such as 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, etc., 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. As a ketone solvent, a chain ketone is preferable and 2-heptanone is more preferable. As content of the organic solvent in a developing solution, 80 mass% or more is preferable, 90 mass% or more is more preferable, 95 mass% or more is further more preferable, 99 mass% or more is especially preferable. 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.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, this 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), sample concentration: Measurement was performed by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard under the analysis conditions of 1.0 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 for determining the content ratio (mol%) of each structural unit in each polymer was performed.

<Synthesis of compounds>
[Example 1] (Synthesis of Compound (Z-1))
To a 1,000 mL round bottom flask were added potassium carbonate 133 g (961 mmol), ethyl acetoacetate 50.0 g (384 mmol), iodomethane 182 g (1.15 mol) and acetone 250 g, and the mixture was stirred at 60 ° C. for 15 hours. After cooling to room temperature, insolubles were removed by celite filtration. After distilling off the obtained solution, the residue was purified by column chromatography to obtain 51.4 g (yield 85%) of a dimethyl compound represented by the following formula (z-1).

  Next, 20.0 g (126 mmol) of (z-1) obtained above and 50 mL of tetrahydrofuran were added to a 300 mL round bottom flask and stirred in a water bath. There, the 5 mass% aqueous solution of 3.17 g (132 mmol) of lithium hydroxide was dripped slowly. After completion of dropping, the mixture was stirred at room temperature for 10 hours. Concentrated hydrochloric acid was added until the pH was 2 or less, and the mixture was extracted with dichloromethane. By distilling off the solvent, 15.1 g of a crude product represented by the following formula (z-2) was obtained. This product was used in the next reaction without further purification.

  To the 200 mL round bottom flask, 15.1 g (116 mmol) of (z-2) obtained above, 50 mL of acetonitrile and 0.5 g of dimethylformamide were added, and the mixture was cooled and stirred in an ice bath. To this, 19.1 g (151 mmol) of oxalyl chloride was slowly added dropwise. After completion of dropping, the mixture was stirred at 0 ° C. for 15 minutes and then stirred at room temperature for 3 hours. After distilling off the solvent and excess oxalyl chloride, 30 mL of acetonitrile was added to form a solution (hereinafter also referred to as “solution (I)”).

  In a 300 mL round bottom flask, 14.9 g (96.7 mmol) 2-hydroxy-4-oxatricyclo [4.2.1.03,7] nonan-5-one, 17.6 g (174 mmol) triethylamine and 100 g acetonitrile. And cooled and stirred in an ice bath. The solution (I) prepared above was slowly added dropwise thereto. After completion of dropping, the mixture was stirred at 0 ° C. for 1 hour, and then stirred at room temperature for 8 hours. After the solvent was distilled off, ethyl acetate was added and insoluble matters were removed by Celite filtration. The obtained solution was washed with water three times, and then the solvent was distilled off. By purification by column chromatography, 20.1 g (yield 78%) of an ester compound represented by the following formula (z-3) was obtained.

  To a 300 mL round bottom flask, 15.0 g (56.3 mmol) of (z-3) obtained above and 100 g of tetrahydrofuran were added and stirred at room temperature. Thereto, 18.9 g (59.1 mmol) of pyridinium tribromide was added little by little as a solid. After completion of the addition, the mixture was stirred at room temperature for 1 hour. After the solvent was distilled off, ethyl acetate was added and insoluble matters were removed by filtration. The obtained solution was washed with water three times, and then the solvent was distilled off. By purification by column chromatography, 15.5 g (yield 80%) of a bromo compound represented by the following formula (z-4) was obtained.

  To a 300 mL round bottom flask were added 4.49 g (52.2 mmol) of methacrylic acid, 40 mL of DMF, 9.02 g (65.2 mmol) of potassium carbonate and 2.89 g (17.4 mmol) of potassium iodide, and the mixture was stirred at room temperature for 30 minutes. . A solution prepared by dissolving (z-4) 15.0 (43.5 mmol) obtained above in 15 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, 11.4 g (yield 75%) of a compound represented by the following formula (Z-1) was obtained.

[Examples 2 to 10] (Synthesis of compounds (Z-2) to (Z-10))
By appropriately selecting a precursor and performing the same operation as in Example 1, compounds represented by the following formulas (Z-2) to (Z-10) were synthesized.

<Synthesis of polymer>
<Synthesis of [A] polymer and (D-1) fluorine atom-containing polymer>
The monomers used for the synthesis of [A] polymer and (D-1) fluorine atom-containing 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 ( As for V), the above compound (M-4) gives each other structural unit. 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 11] (Synthesis of polymer (A-1))
7.15 g (35 mol%) of compound (M-1), 5.19 g (35 mol%) of compound (M-2), 3.09 g (15 mol%) of compound (M-3) and compound (Z-1) ) 4.58 g (15 mol%) was dissolved in 40 g of 2-butanone, and 0.72 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 powder 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 12 to 24, 26 and 27, Synthesis Examples 1 to 5, and Synthesis Examples 7 and 8]
(Polymers (A-2) to (A-14), Polymers (A-16) and (A-17), Polymers (a-1) to (a-5), and Polymer (a-7) ) And (a-8))
Each polymer was synthesized in the same manner as in Example 11 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 25] (Synthesis of polymer (A-15))
Compound (M-4) 40.10 g (50 mol%), compound (M-5) 42.98 g (35 mol%), compound (Z-2) 16.93 g (15 mol%), radical polymerization initiator After 4.06 g of AIBN (5 mol% based on the total monomers) and 1 g of t-dodecyl mercaptan were dissolved in 100 g of propylene glycol monomethyl ether, the reaction temperature was maintained at 70 ° C. in a nitrogen atmosphere, Polymerized. After completion of the polymerization reaction, the polymer solution was dropped into 1,000 g of n-hexane to solidify 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-15) (65.7 g, yield 77%). Mw of the polymer (A-15) 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-2) was 50.3 mol%, 34.6 mol% and 15. It was 1 mol%.

[Synthesis Example 6] (Synthesis of polymer (a-6))
The polymer (a-6) was synthesized in the same manner as in Example 25 except that the types and amounts of monomers shown in Table 1 were used.

[Synthesis Example 9] (Synthesis of Polymer (D-1))
Compound (M-15) 82.2 g (70 mol%) and compound (M-12) 17.8 g (30 mol%) were dissolved in 200 g of 2-butanone, and AIBN 0.46 g (total single amount) 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 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. 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 ratio of each structural unit derived from (M-15) and (M-12) was 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: Norbornanesulton-2-yloxycarbonyldifluoromethane Sulfonate B-3: Triphenylsulfonium 3- (piperidin-1-ylsulfonyl) -1,1,2,2,3,3-hexafluoropropane-1-sulfonate B-4: Triphenylsulfonium adamantane-1-yl Oxycarbonyldifluoromethanesulfonate B-5: N- (trifluoromethanesulfonyloxy) -1,8-naphthalimide

[[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 28]
[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 mass, (D-1) 3 parts by mass of (D-1-1) as a fluorine atom-containing polymer, (E-1) 2,240 parts by mass as (E) solvent, and (E-2) 960 parts by mass and [F] 30 parts by mass of (F-1) as an uneven distribution accelerator were mixed, and the resulting mixture was filtered through a membrane filter having a pore size of 0.2 μm to thereby prepare a radiation-sensitive resin composition. (J-1) was prepared.

[Examples 29 to 41 and Comparative Examples 1 to 6]
Each radiation-sensitive resin composition was prepared in the same manner as in Example 28 except that the components having the types and contents shown in Table 2 were used.

[Example 42]
[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 Radiation sensitivity 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 resin composition (J-15) was prepared.

[Examples 43 to 58 and Comparative Examples 7 to 15]
Each radiation-sensitive resin composition was prepared in the same manner as in Example 42 except that the components having 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 a 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 a film 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)]
In [Formation of resist pattern (1)], except that organic solvent development was performed using n-butyl acetate instead of the TMAH aqueous solution and washing with water was not performed, [Formation of resist pattern (1)] The negative resist pattern was formed in the same manner as described above.

[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 a film 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 above resist pattern formation (3) except that n-butyl acetate was used instead of the TMAH aqueous solution and the organic solvent was developed. 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, the comparative example which is a determination criterion in the LWR performance, the MEEF performance, the CDU performance, the resolution, the depth of focus, and the exposure margin is the comparative example 1, the comparative example 2 and the comparative example 6, and the working example. Comparative Examples 1 to 29-38, Comparative Example 3 to Example 39, Comparative Example 4 to Example 40, Comparative Example 5 to Example 41, Comparative Example 7 to Example 42, Comparative Example 8, Comparative Example 8 and Comparative Example Comparative Example 7 for Example 15 and Examples 43-52, Comparative Example 9 for Example 53, Comparative Example 10 for Example 54, Comparative Example 11 for Example 55, Comparative Example 12 for Example 56, Example 57 is Comparative Example 13 and Example 58 is Comparative Example 14.

[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”.

[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 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”.

[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”.

[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 exposure margin = (E (36) The exposure margin (%) was calculated from the equation: −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”.

  From the results of Tables 4 and 5, the radiation-sensitive resin compositions of the examples show the LWR performance, CDU performance, resolution in the case of ArF exposure and electron beam exposure, in the case of alkali development and in the case of organic solvent development. It was shown that it is excellent in the property, rectangularity of the cross-sectional shape, depth of focus, exposure margin, and MEEF performance. On the other hand, it was also shown that the radiation sensitive resin compositions of the comparative examples were inferior in performance to the examples. In general, it is known that the electron beam exposure shows the same tendency as in the case of EUV exposure. Therefore, even in the case of EUV exposure, according to the radiation-sensitive resin composition of the examples. It is estimated that the LWR performance is excellent.

  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 excellent. A 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 that is expected to be further miniaturized in the future.

Claims (7)

A radiation-sensitive resin composition comprising an acid-dissociable group-containing polymer and a radiation-sensitive acid generator,
The polymer has a first structural unit containing a group represented by the following formula (1),
The radiation sensitive resin composition, wherein the radiation sensitive acid generator contains a compound represented by the following formula (7) .

(In the formula (1), L is a divalent organic group having 1 to 20 carbon atoms. M is a substituted or unsubstituted methanediyl group . L and M are combined with each other and bonded to each other. A monocyclic alicyclic structure having 3 to 20 ring members constituted with atoms may be formed, and R ¹ is a monovalent organic group having 1 to 20 carbon atoms.

(In 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 carbon. (It is a fluorinated alkanediyl group having a number of 1 to 10. X ⁺ is a monovalent radiation-sensitive onium cation.) The R ¹ in the formula (1) is at least one selected from the group consisting of a group having a lactone structure, a group having a sultone structure, a group having a cyclic carbonate structure, and a group having OH. Radiation sensitive resin composition. The radiation sensitive resin composition according to claim 1, wherein R ¹ in the formula (1) is represented by the following formula (X).

(In Formula (X), R ² is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ³ and R ⁴ are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms. Or it is a C3-C20 monovalent alicyclic hydrocarbon group, or these groups are mutually match | combined and the C3-C20 alicyclic structure comprised with the carbon atom which these couple | bond together is represented. * Indicates a site bonded to the oxy group in the above formula (1).) The radiation-sensitive resin composition according to claim 1 , wherein L in the formula (1) is a methanediyl group. The radiation sensitivity according to any one of claims 1 to 4 , wherein the first structural unit is represented by any one of the following formulas (2-1), (2-2), and (2-3). Resin composition.

(In the formulas (2-1) to (2-3), Z is a group represented by the above formula (1).
In formula (2-1) or (2-2), R ⁵ and R ⁶ are a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.
In Formula (2-2), A ¹ is a single bond, —O—, —COO—, or —CONH—.
In formula (2-3), R ⁷ represents a hydrogen atom or a methyl group. R ⁸ , R ⁹ and R ¹⁰ are each independently a hydrogen atom, a halogen atom, a hydroxy group or a monovalent organic group having 1 to 20 carbon atoms, or one or more R ⁸ , one or more Two or more of R ⁹ and R ¹⁰ represent a ring structure having 3 to 20 ring members constituted by being combined with each other. a is an integer of 1 to 4. When a is 2 or more, the plurality of R ⁸ and R ⁹ may be the same or different. A ² is a single bond or a divalent organic group. R ¹⁰ and A 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. ) The radiation sensitive resin composition according to any one of claims 1 to 5 , wherein the polymer further includes a second structural unit which is a structural unit other than the first structural unit and includes an acid dissociable group. object. Forming a resist film;
A step of exposing the resist film, and a step of developing the exposed resist film,
The resist pattern formation method which forms the said resist film with the radiation sensitive resin composition of any one of Claims 1-6 .