JP6241226B2 - Photoresist composition, resist pattern forming method, polymer and compound - Google Patents

Description

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

  For the formation of various electronic device structures such as semiconductor devices and liquid crystal devices, a resist pattern by lithography of a photoresist composition is used. Such a photoresist composition generates an acid in an exposed portion by irradiation with exposure light such as deep ultraviolet rays such as an ArF excimer laser or an electron beam, and a developer solution for exposed and unexposed portions by the catalytic action of this acid. A difference in dissolution rate with respect to is formed, and a resist pattern is formed on the substrate.

  Such a photoresist 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 photoresist composition have been studied. By having a lactone structure such as a butyrolactone structure or a norbornane lactone structure, the adhesion of the resist pattern to the substrate can be improved. It is known that these performances 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 is progressing to a level of 45 nm or less, the required level of the performance is further increased, and the conventional photoresist composition satisfies the above requirements. Is not done.

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

  The present invention has been made based on the circumstances as described above, and its purpose is a photoresist excellent in LWR performance, CDU performance, resolution, rectangularity of a cross-sectional shape, depth of focus, exposure margin and MEEF performance. It is to provide a composition.

（式（１）中、Ｒ^１及びＲ^２は、それぞれ独立して、水素原子又は炭素数１〜２０の１価の有機基である。但し、Ｒ^１及びＲ^２のうちの少なくともいずれかは炭素数１〜２０の１価の有機基である。＊は、上記構造単位の他の部分における炭素原子に結合する部位を示す。） The invention made to solve the above problems is
A polymer (hereinafter also referred to as “[A] polymer”) having a structural unit (hereinafter also referred to as “structural unit (I)”) containing a group represented by the following formula (1), and a radiation-sensitive acid A photoresist composition containing a generator (hereinafter also referred to as “[B] acid generator”).

(In the formula (1), R ¹ and R ² are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, provided that at least one of R ¹ and R ² is (It is a monovalent organic group having 1 to 20 carbon atoms. * Indicates a site bonded to a carbon atom in another part of the structural unit.)

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 photoresist composition.

Yet another invention made to solve the above problems is as follows:
It is a polymer having a structural unit containing a group represented by the following formula (1 ′).

（式（１’）中、Ｒ^１Ａ及びＲ^２Ａは、それぞれ独立して、水素原子又は炭素数１〜２０の１価の有機基である。但し、Ｒ^１Ａ及びＲ^２Ａのうちの少なくともいずれかは置換又は非置換の炭素数３〜２０の１価の脂環式炭化水素基である。＊は、上記構造単位の他の部分における炭素原子に結合する部位を示す。）

(In Formula (1 ′), R ^1A and R ^2A are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, provided that at least one of R ^1A and R ^2A Is a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, * indicates a site bonded to a carbon atom in the other part of the structural unit.

（式（ｉＡ）中、Ｒ^１Ａ及びＲ^２Ａは、それぞれ独立して、水素原子又は炭素数１〜２０の１価の有機基である。但し、Ｒ^１Ａ及びＲ^２Ａのうちの少なくともいずれかは置換又は非置換の炭素数３〜２０の１価の脂環式炭化水素基である。Ｙは、重合性炭素−炭素二重結合を含む１価の基である。） Yet another invention made to solve the above problems is as follows:
It is a compound represented by the following formula (iA).

(In Formula (iA), R ^1A and R ^2A are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, provided that at least one of R ^1A and R ^2A is (It is a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. Y is a monovalent group containing a polymerizable carbon-carbon double bond.)

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 photoresist composition and the resist pattern forming method of the present invention, a resist that exhibits excellent depth of focus, exposure margin, and MEEF performance, has low LWR and CDU, high resolution, and excellent cross-sectional rectangularity. A pattern can be formed. The polymer of the present invention can be suitably used as a polymer component of the photoresist composition. The compound of the present invention can be suitably used as a raw material monomer for the polymer. Accordingly, these can be suitably used for manufacturing semiconductor devices that are expected to be further miniaturized in the future.

<Photoresist composition>
The photoresist composition contains a [A] polymer and a [B] acid generator. The photoresist composition includes, as suitable components, [C] acid diffusion controller, fluorine atom-containing polymer other than [A] polymer (hereinafter also referred to as “[D] polymer”), [E] [A ] And polymers other than [D] polymer (hereinafter also referred to as “[E] polymer”), [F] solvent may be contained, and within the range not impairing the effects of the present invention, An optional component may be contained.

  The photoresist composition may contain only the base polymer as a polymer component, and may contain a water-repellent polymer additive in addition to the base polymer. The “base polymer” refers to a polymer that is a main component of a resist film formed from a photoresist composition, and preferably a polymer that occupies 50% by mass or more of the total polymer constituting the resist film. Say. 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 photoresist 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. The photoresist composition contains a water-repellent polymer additive, so that elution of an acid generator and the like from the resist film can be suppressed, and the formed resist film surface exhibits a high dynamic contact angle. 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 photoresist composition contains a water repellent additive, the content of the water repellent polymer additive is preferably 0.1 part by mass to 20 parts by mass with respect to 100 parts by mass of the base polymer. More preferably, 3 parts by mass to 15 parts by mass, and even more preferably 0.5 parts by mass to 10 parts by mass. As content of the base polymer in the said photoresist composition, 70 mass% or more is preferable with respect to the total solid in the said photoresist composition, 80 mass% or more is more preferable, 85 mass% or more is further more. preferable.

In the photoresist composition, in order for the polymer to function well as a water-repellent polymer additive, the polymer constituting the water-repellent polymer additive is preferably a polymer having a fluorine atom, More preferably, the fluorine atom content is higher 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 photoresist composition, (1) [A] polymer as a base polymer, (2) [A] polymer as a base polymer and water-repellent polymer additive [A] polymer, (3) [A] polymer as base polymer and [D] polymer as water-repellent polymer additive, (4) [E] polymer and water-repellent as base polymer The case where [A] polymer as a polymer additive is each contained is mentioned.
Hereinafter, each component of the photoresist composition will be described in order.

<[A] polymer>
[A] The polymer is a polymer having the structural unit (I). In the photoresist composition, the [A] polymer has the structural unit (I), so that the LWR performance, the CDU performance, the resolution, the rectangular shape of the cross-sectional shape, the depth of focus, the exposure margin, and the MEEF performance (hereinafter, referred to as “a”). , Also referred to as “LWR performance”. Although it is not necessarily clear why the photoresist composition has the above-described configuration, the following effects can be inferred, for example. That is, the structural unit (I) includes a group having a phosphate structure. The phosphate ester structure has a larger number of oxygen atoms and higher polarity than a carboxylic ester structure. As a result, the diffusion length in the resist film containing the [A] polymer of the acid generated from the [B] acid generator can be shortened more appropriately. Moreover, the solubility of the [A] polymer in the developer can be controlled more appropriately. When R ¹ and R ² are acid-dissociable groups, the structural unit (I) has two acid-dissociable groups, so that the polarity change before and after dissociation of the acid-dissociable group becomes larger. As a result, the dissolution contrast between the exposed portion and the unexposed portion can be further increased. As a result, the LWR performance and the like are improved.

[A] When used as a base polymer, the polymer [A] includes a structural unit (II) represented by the following formula (3), a lactone structure, a cyclic carbonate structure, and a sultone structure in addition to the structural unit (I). It may have a structural unit (III) containing at least one selected from the group consisting of, a structural unit (IV) containing a hydroxy group, and other structural units other than the above (I) to (IV) It may be. When the polymer [A] is used as a water repellent additive, it preferably has a structural unit (V) containing a fluorine atom in addition to the structural unit (I), and the structural units (II) to (V). Or other structural units other than the above (I) to (V). [A] The polymer may have one or more of these structural units.
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) (hereinafter also referred to as “group (I)”).

In the above formula (1), ^{R 1} and ^{R 2} are each independently a monovalent organic group hydrogen atom or a C 1-20. However, at least one of R ¹ and R ² is a monovalent organic group having 1 to 20 carbon atoms. * Indicates a site bonded to a carbon atom in another part of the structural unit.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ¹ and R ² include, for example,
A hydrocarbon group having 1 to 20 carbon atoms, a group (α) containing a divalent heteroatom-containing group at the terminal between carbon-carbon or the bond side of the hydrocarbon group, the hydrocarbon group and the group (α) And a group in which a part or all of the hydrogen atoms are substituted with a monovalent 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 having 6 to 20 carbon atoms. Group hydrocarbon group and the like.

Examples of the chain hydrocarbon group include:
Alkyl groups such as methyl, ethyl, propyl, butyl, and pentyl groups;
Alkenyl groups such as ethenyl group, propenyl group, butenyl group, pentenyl group;
Examples thereof 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 cyclopropyl group, cyclobutyl group, cyclopentyl group, 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;
Examples thereof include polycyclic cycloalkenyl groups such as norbornenyl group and tricyclodecenyl group.

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

  Examples of the hetero atom contained in the monovalent and divalent heteroatom-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 a combination thereof. R ′ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

  Examples of the monovalent heteroatom-containing group include a hydroxy group, a carboxy group, a sulfanyl group (—SH), an amino group, and a cyano group.

The monovalent organic group for R ¹ and R ² is preferably an acid dissociable group. By using R ¹ and R ² as acid dissociable groups, the structural unit (I) becomes a structural unit containing an acid dissociable group, and as a result, the LWR performance of the photoresist composition can be improved.

  Examples of the acid dissociable group include a group represented by the following formula (a) (hereinafter also referred to as “group (a)”).

In the above formula (a), R ^p1 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^p2 and R ^p3 each independently represent a monovalent hydrocarbon group having 1 to 20 carbon atoms, or have 3 to 20 ring members formed together with the carbon atoms to which these groups are combined and bonded to each other. Represents a ring structure. However, the alicyclic structure composed of R ^p2 and R ^p3 combined with each other and the carbon atom to which they are bonded has a gap between the carbon atom adjacent to the carbon atom to which they are bonded and the carbon atom adjacent to this carbon atom. In the case of including a heavy bond, R ^p1 may be a hydrogen atom. ** indicates a site bonded to an oxygen atom.

  Examples of the acid dissociable group include groups represented by the following formulas (a-1) to (a-10) (hereinafter also referred to as “groups (a-1) to (a-10)”). Can be mentioned.

In the above formulas (a-1) to (a-10), R ^{a to} R ^j are each independently a monovalent organic group having 1 to 20 carbon atoms. a is an integer of 0-9. b is an integer of 0-7. ** is synonymous with the above formula (a).

In addition, the monovalent organic group for R ¹ and R ² is also preferably a polar group. By making R ¹ and R ² a polar group, the solubility of the [A] polymer in the developer can be adjusted more appropriately, and [B] the acid generated from the acid generator The diffusion length in the resist film can be shortened more appropriately, and as a result, the LWR performance of the photoresist composition can be further improved.
Examples of the group having polarity include a group (b-1) containing -C (R ^j ) (R ^k ) OH, an alkali dissociable group (b-2), and a group containing an alkali dissociable group (b- 3), a lactone group —COO—, a group (b-4) containing a polar group such as a (substituted) amino group, and the like. The “alkali dissociable group” refers to a group that replaces a hydrogen atom such as a carboxy group and dissociates by the action of an alkali. By using the group (b-2) or (b-3) containing an alkali-dissociable group as the polar group, the [A] polymer can further increase the affinity for an alkali developer.

  Examples of the group having polarity include groups represented by the following formulas (b-1-1) to (b-4-3) (hereinafter referred to as “groups (b-1-1) to (b-4-)”. 3) ")) and the like.

In the above formulas (b-1-1) to (b-4-3), ** represents a site bonded to an oxygen atom.
In the above formula (b-3-1), R ^k is a monovalent alkali-dissociable group.

  Among these, the group (b-1), the group (b-2), and the group (b-3) are preferable, and the group (b-1-1), the group (b-1-2), and the group (b- 2-1), group (b-2-2), and group (b-3-1) are more preferable.

  Examples of the group (I) include groups represented by the following formulas (1-1) to (1-16) (hereinafter also referred to as “groups (I-1) to (I-16)”). Can be mentioned.

  In the above formulas (1-1) to (1-16), * has the same meaning as the above formula (1).

  Of these, the group (I-1) is preferred.

  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 formula (2-1), ^{R 3} is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ⁴ is a divalent organic group having 1 to 20 carbon atoms.
In the formula (2-2), ^{R 5} is a hydrogen atom or a methyl group. R ⁶ , R ⁷ and R ⁸ are each independently a hydrogen atom, a halogen atom, a hydroxy group or a monovalent organic group having 1 to 20 carbon atoms. Two or more of one or more of R ⁶ and R ⁷ may be combined with each other to form a ring structure having 3 to 20 ring members that is configured together with the carbon atom to which they are bonded. a is an integer of 1 to 4. When a is 2 or more, the plurality of R ⁶ may be the same or different, and the plurality of R ⁷ may be the same or different. R ⁹ is a single bond or a divalent organic group having 1 to 20 carbon atoms. R ⁸ and R ⁹ may be combined with each other to form a ring structure with 3 to 20 ring members constituted together with the carbon atom to which they are bonded.
In the formula ^{(2-3), R 10} is a monovalent organic group hydrogen atom or a C 1-20. R ¹¹ is a single bond or a divalent organic group having 1 to 20 carbon atoms.

From the viewpoint of copolymerization of the monomer that gives the structural unit (I),
R ³ in the above formula (2-1) is preferably a hydrogen atom or a methyl group, and more preferably a methyl group.
R ⁵ in the above formula (2-2) is preferably a hydrogen atom.

Examples of the divalent organic group having 1 to 20 carbon atoms represented by R ⁴ , R ⁹ and R ¹¹ include, for example, a divalent hydrocarbon group having 1 to 20 carbon atoms and carbon-carbon of this hydrocarbon group. Examples thereof include a group containing the above-mentioned divalent heteroatom-containing group in between, a group obtained by substituting part or all of the hydrogen atoms of these groups with the above-mentioned monovalent heteroatom-containing group, and the like.

The divalent organic group for R ⁴ , R ⁹ and R ¹¹ is preferably a group represented by the following formula (X).

In said formula (X), R < ¹² > -R < ¹⁵ > is respectively independently a hydrogen atom or a C1-C20 monovalent organic group. ** represents a site that binds to Z in the above formulas (2-1) to (2-3).

The monovalent organic group having 1 to 20 carbon atoms represented by ^R 12 ^{to R 15,} for example, for example, such as a monovalent organic group and similar groups exemplified as ^{R 1} above and ^{R 2} can be mentioned .
R ^{12 to} R ¹⁵ are preferably a hydrogen atom or a monovalent chain hydrocarbon group, more preferably a hydrogen atom or an alkyl group, still more preferably a hydrogen atom, a methyl group or an ethyl group, and particularly preferably a hydrogen atom.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ⁶ , R ⁷ and R ⁸ include the same groups as the monovalent organic groups exemplified as R ¹ and R ^2. It is done.

R ⁶ and R ⁷ are preferably a hydrogen atom.
R ⁸ is preferably an alkyl group, more preferably a methyl group or an ethyl group.

Examples of the ring structure having 3 to 20 ring members constituted by combining two or more of the one or more of R ⁶ , R ⁷ and R ⁸ with each other include, for example, a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, Examples thereof include alicyclic structures such as cyclohexane structure, norbornane structure and adamantane structure; aliphatic heterocyclic structures such as oxacyclopentane structure, thiacyclopentane structure and azacyclopentane structure.

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

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ¹⁰ include the same groups as the monovalent organic groups exemplified as R ¹ and R ² .
R ¹⁰ is preferably a monovalent hydrocarbon group, more preferably a monovalent chain hydrocarbon group, more preferably a monovalent alicyclic hydrocarbon group, still more preferably an alkyl group or a cycloalkyl group, a methyl group, An ethyl group, a cyclohexyl group, and an adamantyl group are particularly preferable.

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

  In the above formulas (2-1-1) to (2-3-2), Z is a group represented by the above formula (1).

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

  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, 5 mol% is more preferable, 7 mol% is further more preferable, 15 mol % Is particularly preferred. As an upper limit of the content rate of structural unit (I), 100 mol% is preferable, 80 mol% is more preferable, 60 mol% is further more preferable, 50 mol% is especially preferable. By making the content rate of structural unit (I) into the said range, the LWR performance of the said photoresist composition etc. can be improved.

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

In the above formula (i), ^{R 1} and ^{R 2} are each independently a monovalent organic group hydrogen atom or a C 1-20. However, at least one of R ¹ and R ² is a monovalent organic group having 1 to 20 carbon atoms. Y is a monovalent group containing a polymerizable carbon-carbon double bond.

  Examples of the compound (i) include compounds represented by the following formulas (i-1) to (i-28).

  In the above formulas (i-1) to (i-28), Y has the same meaning as the above formula (i).

  When the compound (i) is a compound represented by the following formula (i ′), for example, it can be easily synthesized in a high yield according to the following scheme.

In the above scheme, R ′ is a monovalent organic group having 1 to 20 carbon atoms. Y ″ is a halogen atom. R ³ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Y ′ is a halogen atom, a hydroxy group or OCOR. 20 monovalent hydrocarbon groups.

By reacting the compound represented by the above formula (i′-a) with formaldehyde in a solvent such as dehydrated tetrahydrofuran in the presence of an activator such as zinc and chlorotrimethylsilane, the above formula (i ′ A hydroxy compound represented by -b) is obtained. By reacting this hydroxy compound with a (meth) acrylic compound such as (meth) acryloyl chloride in a solvent such as dehydrated tetrahydrofuran in the presence of a base such as N, N-dimethylaminopyridine or triethylamine, the above formula ( A compound represented by i′-c) is obtained. By reacting this compound with alcohols such as R ¹ —OH and R ² —OH to exchange phosphoric acid ester, or in the presence of a base such as lithium hydroxide, this compound (i′-c) is dissolved in methanol / water. By reacting a phosphonic acid compound obtained by hydrolysis in a solvent such as R ¹ —OH and R ² —OH alcohol in the presence of a dehydration condensing agent such as a carbodiimide compound, the above formula ( A compound represented by i ′) is obtained. The product can be isolated by purification by solvent washing, column chromatography, recrystallization, distillation and the like.

[Structural unit (II)]
The structural unit (II) is a structural unit represented by the following formula (3) having an acid dissociable group represented by the above formula (a). The “acid-dissociable group” refers to a group that substitutes a hydrogen atom of a carboxy group and is dissociated by the action of an acid. In the photoresist composition, since the [A] polymer has the structural unit (II), sensitivity and resolution are improved, and as a result, LWR performance and the like can be improved.

In the above formula (3), R ¹⁶ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Z ′ is a group represented by the above formula (a).

R ¹⁶ 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).

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

In the above formulas (3-1) to (3-5), R ¹⁶ has the same meaning as the above formula (3). R ^{17 to} R ¹⁹ 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. R ^{17 ′} is a hydrogen atom, a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. i and j are each independently an integer of 1 to 4. R ^X and R ^Y are each independently a hydrogen atom or a monovalent chain hydrocarbon group having 1 to 10 carbon atoms. R ^Z is a tetravalent alicyclic group having 1 to 20 carbon atoms including a carbon atom to which R ^{17 ′} is bonded and a double bond between the carbon atom to which R ^X is bonded and the carbon atom to which R ^Y is bonded. It is a hydrocarbon group.

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

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

  As the structural unit (II), a structural unit derived from 1-alkyl-1-cycloalkyl (meth) acrylate, a structural unit derived from 2-alkyl-2-adamantyl (meth) acrylate, 2- (adamantane-1- Yl) structural units derived from propan-2-yl (meth) acrylate, preferably structural units derived from 2-cyclohexylpropan-2-yl (meth) acrylate, derived from 1-methyl-1-cyclopentyl (meth) acrylate Structural unit derived from 1-ethyl-1-cyclopentyl (meth) acrylate, structural unit derived from 1-i-propyl-1-cyclopentyl (meth) acrylate, 1-methyl-1-cyclohexyl (meth) Structural unit derived from acrylate, 1-ethyl-1-cyclooctyl (meth) Structural unit derived from acrylate, structural unit derived from 2-methyl-2-adamantyl (meth) acrylate, structural unit derived from 2-i-propyl-2-adamantyl (meth) acrylate, 2-cyclohexylpropane-2- Structural unit derived from yl (meth) acrylate, structural unit derived from 2- (adamantan-1-yl) propan-2-yl (meth) acrylate, 4,6,6-trimethylbicyclo [3.1.1] A structural unit derived from hept-3-en-2-yl (meth) acrylate and a structural unit derived from 2-ethyl-2-tetracyclododecyl (meth) acrylate are more preferred.

  As a content rate of structural unit (II), 10 mol%-80 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 20 mol%-75 mol% are more preferable, 30 mol% More preferred is ~ 65 mol%. By making the said content rate into the said range, the sensitivity and resolution of the said photoresist composition improve more, and, as a result, LWR performance etc. can be improved more. When the said content rate is less than the said minimum, the pattern formation property of the said photoresist composition may fall. When the said content rate exceeds the said upper limit, the adhesiveness to the board | substrate of a resist pattern may fall.

[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. [A] Since the polymer further has the structural unit (III), the solubility in the developer can be further adjusted, and as a result, the LWR performance and the like of the photoresist composition can be improved. . Moreover, the adhesiveness of the resist pattern formed from the said photoresist composition and a board | substrate can be improved.

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

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

  Among these, the structural unit (III) is preferably a structural unit containing a norbornane lactone structure, a structural unit containing a γ-butyrolactone structure, or a structural unit containing a norbornane sultone structure, and derived from norbornane lactone-yl (meth) acrylate. A structural unit derived from cyano-substituted norbornanelactone-yl (meth) acrylate, a structural unit derived from oxynorbornanelactone-yl (meth) acrylate, a structure derived from γ-butyrolactone-3-yl (meth) acrylate A structural unit derived from a unit, γ-butyrolactone-4-yl (meth) acrylate, is more preferred.

  As a content rate of structural unit (III), 0 mol%-70 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 10 mol%-60 mol% are more preferable, 30 mol% More preferred is ˜50 mol%. By making the said content rate into the said range, the adhesiveness to the board | substrate of the resist pattern formed from the said photoresist composition can be improved more. When the said content rate is less than the said minimum, the adhesiveness to the board | substrate of the resist pattern formed from the said photoresist composition may fall. When the said content rate exceeds the said upper limit, the pattern formation property of the said photoresist composition may fall.

[Structural unit (IV)]
The structural unit (IV) is a structural unit containing a polar group. [A] Since the polymer further has the structural unit (IV), the solubility in the developer can be further adjusted, and as a result, the LWR performance and the like of the photoresist composition can be improved. . Moreover, the adhesiveness of the resist pattern formed from the said photoresist composition and a board | substrate can be improved.

  Examples of the polar group include a hydroxy group, a keto 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 ^B is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

  As a content rate of the structural unit containing the said polar group, 0 mol%-60 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 10 mol%-55 mol% are preferable, and 20 mol % To 50 mol% is more preferable. By making the said content rate into the said range, the LWR performance of the said photoresist composition etc. can be improved more.

[Structural unit (V)]
The structural unit (V) is a structural unit containing a fluorine atom. The polymer [A] can further be used as a water-repellent polymer additive by further having the structural unit (V).

  Examples of the structural unit (V) include a structural unit (Da) and a structural unit (Db) possessed by the [D] fluorine atom-containing polymer described later.

[Other structural units]
[A] The polymer may have other structural units other than the structural units (I) to (V). 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 and 10 mol% or less is more preferable.

  [A] The content of the polymer is preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 85% by mass or more in the total solid content of the photoresist composition.

<[A] Polymer Synthesis Method>
[A] The polymer can be synthesized, for example, by polymerizing a monomer giving 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. The solvent used for these polymerizations may be used alone or in combination of two or more.

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

  [A] The content of the low molecular weight component of the polymer is preferably 0.5% by mass or less, more preferably 0.2% by mass or less, and further preferably 0.1% by mass or less. [A] By setting the content of the low molecular weight component of the polymer in the above range, the LWR performance and the like of the photoresist composition can be further improved. The low molecular weight component of the polymer is a molecular weight of 1 The part below 1,000.

  In addition, content (mass%) of the low molecular weight component (part with a molecular weight less than 1,000) of the polymer in this specification is an HPLC column (“Intersil” ODS-25 μm, 4.6 mmφ × 250 mm of GL Sciences) , Flow rate of 1.0 mL / min, elution solvent acrylonitrile / 0.1% by mass phosphoric acid aqueous solution, sample concentration of 1.0% by mass, sample injection amount of 100 μL, high-performance liquid chromatography using a differential refractometer as a detector ( The value measured by HPLC).

<[B] Acid generator>
[B] The acid generator is a substance that generates an acid upon exposure. Since 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 is changed. The form of inclusion of the [B] acid generator in the photoresist composition capable of forming a resist pattern is a form of a low molecular compound as described later (hereinafter also referred to as “[B] acid generator” as appropriate). ), In the form of acid generating groups incorporated as part of the polymer, or in both forms.

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

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

  Examples of the sulfonium salt include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1] hept- 2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1-difluoroethanesulfonate, triphenylsulfonium camphorsulfonate, 4 -Cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-cyclohexyl Phenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-cyclohexylphenyl Diphenylsulfonium camphorsulfonate, 4-methanesulfonylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-methanesulfonyl Phenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafur B ethanesulfonate, 4-methanesulfonyl-phenyl camphorsulfonate, triphenylsulfonium 1,1,2,2-tetrafluoro-6- (1-adamantanecarbonyloxy) - hexane-1-sulfonate, and the like.

  Examples of the tetrahydrothiophenium salt include 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium nona. Fluoro-n-butanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophene Ni-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium camphorsulfonate , 1- (6-n-butoxynaphthalen-2-yl) Torahydrothiophenium trifluoromethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydro Thiophenium perfluoro-n-octanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2 , 2-tetrafluoroethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium camphorsulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium trifluoromethanesulfonate , 1- (3,5-dimethyl-4 Hydroxyphenyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (3,5-dimethyl- 4-hydroxyphenyl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (3,5-dimethyl-4-hydroxy Phenyl) tetrahydrothiophenium camphorsulfonate and the like.

  Examples of the iodonium salt include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hept-2-yl- 1,1,2,2-tetrafluoroethanesulfonate, diphenyliodonium camphorsulfonate, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, Bis (4-t-butylphenyl) iodonium perfluoro-n-octanesulfonate, bis (4-t-butylphenyl) iodonium 2-bicyclo [2.2 1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, bis (4-t- butylphenyl) iodonium camphorsulfonate, and the like.

Examples of the N-sulfonyloxyimide compound include N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (nonafluoro-n-butanesulfonyloxy). ) Bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (perfluoro-n-octanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2 , 3-dicarboximide, N- (2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy) bicyclo [2.2.1] hept- 5-ene-2,3-dicarboximide, N- (2- (3- tetracyclo ^[4.4.0.1 2,5 ^{.1 7,10]} dodecanyl) -1,1-difluoro-ethanone Sulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (camphorsulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3 -Dicarboximide etc. can be mentioned.

  [B] The acid generator is preferably a compound represented by the following formula (4). [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 LWR performance and the like of the photoresist composition can be improved.

In the above formula (4), R ²⁰ 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 ²¹ is a fluorinated alkanediyl group having 1 to 10 carbon atoms. X ⁺ is a monovalent radiolytic onium cation.

The “number of ring members” in R ²⁰ means the number of atoms constituting the ring of the alicyclic structure and the aliphatic heterocyclic structure, and in the case of the polycyclic alicyclic structure and the polycyclic aliphatic heterocyclic structure, The number of atoms that make up the ring.

Examples of the monovalent group containing an alicyclic structure having 6 or more ring members represented by R ²⁰ include, for example,
A monocyclic cycloalkyl group such as a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, a cyclododecyl 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 7 or more ring members represented by R ²⁰ 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 ²⁰ is preferably 8 or more, more preferably 9 to 15 and even more preferably 10 to 13 from the viewpoint that the acid diffusion length described above becomes more appropriate.

R ²⁰ 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 ²¹ include one hydrogen atom of an alkanediyl group having 1 to 10 carbon atoms such as a methanediyl group, an ethanediyl group, and a propanediyl group. Examples include groups in which the above 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-decomposable onium cation represented by X ⁺ is a cation that decomposes upon exposure to exposure light. In the exposed portion, sulfonic acid is generated from protons generated by the decomposition of the radiolytic onium cation and the sulfonate anion. Examples of the monovalent radiolytic 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-decomposable 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 n-butyl. Groups and the like.
Examples of the unsubstituted branched alkyl group represented by R ^{a1 to} R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include an i-propyl group, an i-butyl group, a sec-butyl group, Examples include t-butyl group.
Examples of the unsubstituted aromatic hydrocarbon group represented by R ^{a1 to} R ^a3 , R ^c1, and R ^c2 include aryl groups such as phenyl group, tolyl group, xylyl group, mesityl group, and naphthyl group; benzyl group And aralkyl groups such as a 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 substitute 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. 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.

  Examples of the acid generator represented by the above formula (4) include compounds represented by the following formulas (4-1) to (4-13) (hereinafter referred to as “compounds (4-1) to (4-13)”. ) ")) And the like.

In the above formulas (4-1) to (4-13), X ⁺ has the same meaning as in the above formula (4).

  [B] Among these, the acid generator is preferably an onium salt compound, more preferably a sulfonium salt or a tetrahydrothiophenium salt, and a compound (4-1), a compound (4-2), or a compound (4-12). ) And compound (4-13) are more preferred.

  [B] As the content of the acid generator, when the [B] acid generator is a [B] acid generator, the [A] polymer 100 is used from the viewpoint of ensuring the sensitivity and developability of the photoresist composition. 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 and developability of the said photoresist composition improve. [B] 1 type (s) or 2 or more types can be used for an acid generator.

<[C] Acid diffusion controller>
The said photoresist composition may contain a [C] acid diffusion control body as needed.
[C] The acid diffusion control body controls the diffusion phenomenon of the acid generated from the [B] acid generator upon exposure in the resist film and suppresses undesirable chemical reaction in the non-exposed region, and the resulting photoresist. The storage stability of the composition is further improved, the resolution as a resist is further improved, and changes in the line width of the resist pattern due to fluctuations in the holding time from exposure to development processing can be suppressed, thereby improving process stability. An excellent photoresist composition is obtained. [C] As a form of inclusion in the photoresist composition of the acid diffusion controller, a form of a free compound (hereinafter referred to as “[C] acid diffusion controller” as appropriate) was incorporated as part of the polymer. It may be in the form or both forms.

  [C] Examples of the acid diffusion controller include a compound represented by the following formula (4) (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. Can be mentioned.

In the above formula (5), R ²² , R ²³ and R ²⁴ are each independently a hydrogen atom, an optionally substituted linear, branched or cyclic alkyl group, an aryl group or an 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. Can be mentioned.

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

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

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

  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) Examples thereof include 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 decomposes upon exposure and loses acid diffusion controllability. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (6-1), an iodonium salt compound represented by the following formula (6-2), and the like.

In the above formula (6-1) and formula (6-2), R ^{25 to} R ²⁹ 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 (5-3). However, R ( ^beta) is an alkyl group, an aryl group, or an aralkyl group.

In the above formula (6-3), R ³⁰ is 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.

  As said photodegradable base, the compound etc. which are represented by a following formula are mentioned, for example.

  Of these, the photodegradable base is preferably a sulfonium salt, more preferably a triarylsulfonium salt, and even more preferably triphenylsulfonium salicylate or triphenylsulfonium 10-camphorsulfonate.

  [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] When the content of the acid diffusion controller exceeds the above upper limit, the sensitivity of the photoresist composition may decrease.

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

  [D] The polymer is not particularly limited as long as it is a polymer having a fluorine atom, but the fluorine atom content (mass%) than the [A] polymer as the base polymer in the photoresist composition. ) Is preferably high. Since the fluorine atom content is higher than that of the [A] polymer as the base polymer, the degree of uneven distribution described above becomes higher, and characteristics such as water repellency and elution suppression of the resulting resist film are improved.

[D] The fluorine atom content of the 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 to 30% by mass. Particularly preferred. [D] If the fluorine atom content of the polymer is less than the lower limit, the hydrophobicity of the resist film surface may be lowered. The fluorine atom content (% by mass) of the polymer can be calculated from the structure of the polymer obtained by ¹³ C-NMR spectrum measurement.

  [D] The polymer preferably has at least one selected from the group consisting of the following structural unit (Da) and structural unit (Db). [D] The polymer may have one or more structural units (Da) and structural units (Db).

[Structural unit (Da)]
The structural unit (Da) is a structural unit represented by the following formula (7a). [D] A polymer can adjust a fluorine atom content rate by having a structural unit (Da).

In said formula (7a), ^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, for example, a trifluoromethyl group, a 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 Examples include 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, monofluoromethyl cyclopentyl group, difluorocyclopentyl groups, perfluorocyclopentyl group, monofluoromethyl cyclohexyl , Difluorocyclopentyl group, perfluorocyclohexylmethyl group, fluoronorbornyl group, fluoroadamantyl group, fluorobornyl group, fluoroisobornyl group, fluorotricyclodecyl group, fluorotetracyclodecyl group and the like.

Examples of the monomer that gives the structural unit (Da) include trifluoromethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, and 2,2,2-trifluoro. Ethyloxycarbonylmethyl (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.
Among these, 2,2,2-trifluoroethyloxycarbonylmethyl (meth) acrylic acid ester is preferable.

  As a content rate of a structural unit (Da), 5 mol%-95 mol% are preferable with respect to all the structural units which comprise a [D] polymer, 10 mol%-90 mol% are more preferable, 30 mol% More preferred is ~ 85 mol%. By setting such a content ratio, a higher dynamic contact angle on the resist film surface can be expressed at the time of immersion exposure.

[Structural unit (Db)]
The structural unit (Db) is a structural unit represented by the following formula (7b). Since the [D] polymer has a structural unit (Db) and becomes hydrophobic, the dynamic contact angle of the resist film surface formed from the photoresist composition can be further improved.

In said formula (7b), R <^F> is a hydrogen atom, a methyl group, or a trifluoromethyl group. R ³¹ is an (s + 1) -valent hydrocarbon group having 1 to 20 carbon atoms, and an oxygen atom, a sulfur atom, —NR′—, a carbonyl group, —CO—O—, or a terminal at the R ³² side of R ³¹ Also includes a structure in which —CO—NH— is bonded. R ′ is a hydrogen atom or a monovalent organic group. R ³² 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 33.} R ³³ is a hydrogen atom or a monovalent organic group. s is an integer of 1 to 3. However, when s is 2 or 3, the plurality of R ³² , X ² , A ¹ and R ³³ may be the same or different.

When R ²⁹ is a hydrogen atom, it is preferable in that the solubility of [D] polymer in an alkaline developer can be improved.

Examples of the monovalent organic group represented by R ³³ 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 (Db) include structural units represented by the following formulas (7b-1) to (7b-3).

In the above formulas (7b-1) to (7b-3), R ^{31 ′} is a divalent linear, branched or cyclic saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms. R ^F , X ² , R ³³ and s are as defined in the above formula (7b). When s is 2 or 3, the plurality of X ² and R ³³ may be the same or different.

  As a content rate of the said structural unit (7b), 0 mol%-90 mol% are preferable with respect to all the structural units which comprise a [D] polymer, 5 mol%-85 mol% are more preferable, 10 mol % To 80 mol% is more preferable. By setting it as such a content rate, the resist film surface formed from the said photoresist composition can improve the fall degree of a dynamic contact angle in alkali image development.

[Structural unit (Dc)]
[D] The polymer may have a structural unit containing an acid dissociable group (hereinafter also referred to as “structural unit (Dc)”) in addition to the structural units (Da) and (Db) ( However, those corresponding to the structural unit (Db) are excluded). [D] When the polymer has the structural unit (Dc), the shape of the resulting resist pattern becomes better. Examples of the structural unit (Dc) include the structural unit (II) in the above-described [A] polymer.

  As a content rate of the said structural unit (Dc), 5 mol%-90 mol% are preferable with respect to all the structural units which comprise a [D] polymer, 10 mol%-70 mol% are more preferable, 15 mol% -60 mol% is more preferable, and 15 mol%-50 mol% is especially preferable. If the content ratio of the structural unit (Dc) is less than the lower limit, development defects in the resist pattern may not be sufficiently suppressed. When the content ratio of the structural unit (Dc) exceeds the upper limit, the hydrophobicity of the resulting resist film surface may be lowered.

[Other structural units]
In addition to the above structural unit, the [D] polymer includes, for example, a structural unit containing at least one structure selected from the group consisting of a structural unit containing an alkali-soluble group, a lactone structure, a cyclic carbonate structure, and a sultone structure. And may have other structural units such as a structural unit containing an alicyclic group. As said alkali-soluble group, a carboxy group, a sulfonamide group, a sulfo group etc. are mentioned, for example. Examples of the structural unit having at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure include the structural unit (III) in the above-described [A] polymer.

  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] polymer, and 20 mol% or less is preferable. If the content ratio of the other structural unit exceeds the upper limit, the pattern forming property of the photoresist composition may be deteriorated.

  As content of [D] polymer in the said photoresist composition, 0-20 mass parts is preferable with respect to 100 mass parts of [A] polymer, and 0.5 mass part-15 mass parts are more preferable. 1 mass part-10 mass parts are further more preferable. [D] When the content of the polymer exceeds the above upper limit, the pattern forming property of the photoresist composition may be lowered.

<[E] polymer>
[E] The polymer is a polymer other than the [A] polymer and the [D] polymer. For example, when the [A] polymer is used as the water-repellent polymer additive, the photoresist composition preferably contains the [E] polymer as the base polymer.

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

<[F] solvent>
The photoresist composition usually contains a [F] solvent. [F] The solvent is not particularly limited as long as it is a solvent capable of dissolving or dispersing at least the [A] polymer, the [B] acid generator, and the optionally contained [C] acid diffusion controller.

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

As an alcohol solvent, for example,
Methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, 2-methylbutanol, sec-pentanol, tert- Pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n- Nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, furf Alcohol, phenol, cyclohexanol, methyl cyclohexanol, 3,3,5-trimethyl cyclohexanol, benzyl alcohol, mono-alcohol solvents such as diacetone alcohol;
Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2 -Polyhydric alcohol solvents such as ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol;
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, polyhydric alcohol partial ether solvents such as dipropylene glycol monopropyl ether.

As an ether solvent, for example,
Dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether;
Cyclic ether solvents such as tetrahydrofuran and tetrahydropyran;
Aromatic ring-containing ether solvents such as diphenyl ether and anisole (methylphenyl ether) are exemplified.

Examples of ketone solvents include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, 2-heptanone (methyl-n-pentyl ketone), and ethyl-n-butyl ketone. Chain ketone solvents such as methyl-n-hexyl ketone, 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:
Methyl acetate, ethyl acetate, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec-butyl acetate, n-pentyl acetate, i-pentyl acetate, sec-pentyl acetate, 3-methoxy acetate Acetate solvents such as butyl, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, and n-nonyl acetate;
Ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether Polyhydric alcohol partial ether acetate solvents such as acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate;
Carbonate solvents such as diethyl carbonate;
Glycol acetate, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl acetoacetate, ethyl acetoacetate, methyl lactate, ethyl lactate N-butyl lactate, n-amyl lactate, diethyl malonate, dimethyl phthalate, diethyl phthalate and the like.

Examples of the hydrocarbon solvent include n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, and cyclohexane. , Aliphatic hydrocarbon solvents such as methylcyclohexane;
Fragrances such as benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, iso-propylbenzene, diethylbenzene, iso-butylbenzene, triethylbenzene, di-iso-propylbenzene and n-amylnaphthalene Group hydrocarbon solvents and the like.

  Among these, ester solvents and ketone solvents are preferable, polyhydric alcohol partial ether acetate solvents and cyclic ketone solvents are more preferable, and propylene glycol monomethyl ether acetate and cyclohexanone are further preferable. The photoresist composition may contain one or more [F] solvents.

<Other optional components>
The photoresist composition may contain other optional components in addition to the above [A] to [F]. 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 photoresist composition contains a water-repellent polymer additive as the [A] polymer and / or [D] polymer, the uneven distribution accelerator makes the water-repellent polymer additive more efficient. In particular, it has the effect of segregating on the resist film surface. By adding this uneven distribution promoter to the photoresist 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 weight to 500 parts by weight, more preferably 15 parts by weight to 300 parts by weight, and more preferably 20 parts by weight with respect to 100 parts by weight of the total amount of the polymer in the photoresist composition. Part to 200 parts by weight is more preferable, and 25 parts to 100 parts by weight is particularly 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 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (above, Tochem Products), MegaFuck F171, F173 (above, DIC), Florard FC430, FC431 (above, Sumitomo 3M) Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, Asahi Glass Industrial Co., Ltd.) Can be mentioned. As content of surfactant in the said photoresist 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. The content of the alicyclic skeleton-containing compound in the photoresist composition is usually 5 parts by mass or less with respect to 100 parts by mass of the [A] polymer.

(Sensitizer)
The sensitizer exhibits an effect of increasing the amount of acid generated from the [B] acid generator and the like, and has an effect of improving the “apparent sensitivity” of the photoresist 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 photoresist composition, it is 2 mass parts or less normally with respect to 100 mass parts of [A] polymers.

<Method for preparing photoresist composition>
The photoresist composition includes, for example, [A] polymer, [B] acid generator, [C] acid diffusion controller, [D] polymer, [E] polymer, and other contained as necessary. And an arbitrary component of [F] solvent may be mixed at a predetermined ratio. The photoresist composition is preferably filtered, for example, with a filter having a pore size of about 0.2 μm after mixing. As solid content concentration of the said photoresist composition, it is 0.1 mass%-50 mass% normally, 0.5 mass%-30 mass% are preferable, and 1 mass%-20 mass% are more preferable.

<Resist pattern formation method>
The resist pattern forming method is:
A step of forming a resist film (hereinafter also referred to as a “resist film forming step”),
A step of exposing the resist film (hereinafter also referred to as “exposure step”), and a step of developing the exposed resist film (hereinafter also referred to as “development step”).
With
The resist film is formed from the photoresist composition.

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

[Resist film forming step]
In this step, a resist film is formed with the photoresist 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 application method include spin coating (spin coating), cast coating, roll coating, and the like. 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.

  When immersion exposure is performed and the photoresist composition does not contain a water-repellent polymer additive, direct contact between the immersion liquid and the resist film is performed on the formed resist film. For the purpose of avoiding this, an immersion protective film that is insoluble in the immersion liquid may be provided. Examples of the immersion protective film include a solvent peeling type protective film that peels off with a solvent before the developing step (see, for example, JP-A-2006-227632), and a developer peeling type protective film that peels off simultaneously with development in the developing step (for example, Any of WO 2005-069076 and WO 2006-035790 may be used. However, from the viewpoint of throughput, it is preferable to use a developer peeling type immersion protective film.

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

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

  After the exposure, post-exposure baking (PEB) is performed, and in the exposed part of the resist film, the acid-dissociable group of the [A] polymer and the like by the acid generated from the [B] acid generator by exposure is dissociated. Is preferably promoted. This PEB causes a difference in solubility in the developer between the exposed area and the unexposed area. As 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 alkali development, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine , Ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 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. Examples of the organic solvent include one or more of the solvents listed as the [F] solvent of the above-described photoresist composition. 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 this invention has a structural unit containing group represented by the said Formula (1 ').
The polymer can be suitably used as a polymer component of the above-described photoresist composition.

<Compound>
The compound of the present invention is represented by the above formula (iA).
The said compound can be used suitably as a raw material monomer of the said polymer mentioned above.

  The said polymer and the said compound are demonstrated in the term of the [A] polymer in the said photoresist composition mentioned above.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to an Example. 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.

[Content of low molecular weight components]
The content (mass%) of the low molecular weight component (part with a molecular weight of 1,000 or less) of the polymer is determined using an HPLC column ("Intersil", OD-25 μm, 4.6 mmφ × 250 mm). 1.0 mL / min, elution solvent: acrylonitrile / 0.1% by mass phosphoric acid aqueous solution, sample concentration: 1.0% by mass, sample injection amount: 100 μL, detector: high performance liquid chromatography according to analytical conditions of differential refractometer ( HPLC).

[ 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>
According to the following method, the compounds represented by the following formulas (M-1) to (M-25) were synthesized.
[Example 1] (Synthesis of Compound (M-1))
After adding 4.25 g (65.0 mmol) of zinc powder, 50 mL of dehydrated tetrahydrofuran and 0.272 g (2.5 mmol) of chlorotrimethylsilane to a 300 mL eggplant-shaped flask, the mixture was stirred at 35 ° C. for 15 minutes. A solution prepared by dissolving 1.50 g (50.0 mmol) of formaldehyde and 11.2 g (55.0 mmol) of dimethyl bromomethylphosphonate in 40 mL of dehydrated tetrahydrofuran was slowly added dropwise thereto. At this time, the solution temperature was raised by the reaction heat, but this was carried out while adjusting the dropping speed so that the internal temperature was 45 ° C. or lower. After completion of dropping, the mixture was stirred at 35 ° C. for 5 hours, and disappearance of the raw material was confirmed by TLC. The reaction was stopped by adding an aqueous ammonium chloride solution, and then the precipitate was removed by Celite filtration. The solvent was replaced with ethyl acetate, followed by washing with water. After the solvent was distilled off, purification by column chromatography gave 6.86 g of dimethyl 2-hydroxyethylphosphonate (yield 89%).
In a 200 mL eggplant-shaped flask, 6.16 g (40.0 mmol) of dimethyl 2-hydroxyethylphosphonate, 0.244 g (2.00 mmol) of N, N-dimethylaminopyridine, 6.07 g (60.0 mmol) of triethylamine and dehydrated acetonitrile After adding 50 mL, it was cooled to 0 ° C. in an ice water bath. Thereto was added dropwise 4.60 g (44.0 mmol) of methacryloyl chloride. After stirring at 0 ° C. for 1 hour, the mixture was stirred at room temperature for 6 hours. After confirming disappearance of the raw material by TLC, water was added to stop the reaction. After extraction with ethyl acetate, washing with water was performed, and purification was performed by column chromatography to obtain 7.38 g of 2- (dimethoxyphosphoryl) ethyl methacrylate (yield 83%).
After adding 1.48 g (62.0 mmol) of lithium hydroxide, 40.5 mL of methanol and 22.5 mL of water to a 200 mL eggplant-shaped flask, it was cooled to 0 ° C. in an ice-water bath. Thereto was slowly added dropwise a solution prepared by dissolving 6.67 g of 2- (dimethoxyphosphoryl) ethyl methacrylate in 27 mL of methanol. After stirring at 0 ° C. for 3 hours and confirming disappearance of the raw material by TLC, 1M hydrochloric acid was added to stop the reaction. After adding ethyl acetate and concentrating, the solvent was replaced with ethyl acetate, and then the ethyl acetate layer was recovered. Subsequently, it was washed with water and purified by column chromatography to obtain 4.66 g of (2-methacryloyloxyethyl) phosphonic acid (yield 80%).
To a 200 mL eggplant-shaped flask was added 3.88 g (20.0 mmol) of (2-methacryloyloxyethyl) phosphonic acid, 2.56 g (20.0 mmol) of 1-ethylcyclohexanol and 80 mL of dehydrated methylene chloride, and then an ice-water bath. At 0 ° C. Thereto was added 3.83 g (20.0 mmol) of 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride as a dehydrating condensing agent. After stirring at 0 ° C. for 3 hours and confirming disappearance of the raw material by TLC, water was added to stop the reaction. After adding ethyl acetate and concentrating, the solvent was replaced with ethyl acetate, and then the ethyl acetate layer was recovered. Subsequently, it was washed with water and purified by column chromatography to obtain 6.88 g of a compound represented by the following formula (M-1) (yield 83%).

[Examples 2 to 18 and Synthesis Examples 1 to 7] (Synthesis of Compounds (M-2) to (M-25))
Compounds (M-2) to (M-25) were synthesized by changing the synthesis raw materials as appropriate and performing the same operations as in Example 1.

<[A] Synthesis of polymer>
According to the following method, the polymers (A1-1) to (A1-45) and (E-1) as polymers [A1] used as a base polymer, and [A2] used as a water-repellent polymer additive Polymers (A2-1) to (A2-15) and (D-1) as polymers were synthesized.
The monomers used for the synthesis of the [A] polymer other than the synthesized compounds (M-1) to (M-25) are shown below.

[[A1] Synthesis of polymer]
[Example 19]
(Synthesis of polymer (A1-1))
Compound (M-1) 3.86 g (10 mol%), compound (M′-1) 7.85 g (50 mol%) and compound (M′-14) 8.29 g (40 mol%) were converted into 2-butanone. It melt | dissolved in 40g and added AIBN 0.77g (5 mol% with respect to all the monomers) as a radical polymerization initiator, and prepared the monomer solution. Next, a 100 mL three-necked flask containing 20 g of 2-butanone was purged with nitrogen for 30 minutes, and then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled with water and cooled to 30 ° C. or lower. The polymerization solution cooled in 400 g of methanol was added, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 80 g of methanol, filtered, and dried at 50 ° C. for 17 hours to synthesize a white powdery polymer (A1-1) (14.8 g, yield 74). %). Mw of the polymer (A1-1) was 7,300, and Mw / Mn was 1.53. Content of the low molecular weight component of a polymer (A1-1) was 0.04 mass%. Moreover, as a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from (M-1), (M′-1) and (M′-14) was 10.1 mol% and 49.8, respectively. Mol% and 40.1 mol%.

[Examples 20 to 62 and Synthesis Examples 8 and 9]
(Synthesis of polymers (A1-2) to (A1-45) and (E-1))
Polymers (A1-2) to (A1-45) and (E) were prepared by carrying out the same operations as in Example 19 except that the types and amounts of monomers shown in Table 1 and Table 2 were used. -1) was synthesized. The total mass of the monomers used was 20 g. "-" In Table 1 and Table 2 indicates that the corresponding monomer was not used. The yield of each polymer, the content of low molecular weight components, Mw, Mw / Mn, and the content ratio of each structural unit are shown in Tables 1 and 2.

[[A2] Synthesis of polymer]
[Synthesis Example 10]
(Synthesis of polymer (A2-1))
Compound (M-20) 53.8 g (30 mol%) and compound (M′-2) 46.2 g (70 mol%) were dissolved in 100 g of 2-butanone, and dimethyl 2, as a radical polymerization initiator was dissolved. A monomer solution was prepared by dissolving 4.77 g of 2′-azobisisobutyrate. Next, a 1,000 mL three-necked flask containing 100 g of 2-butanone was purged with nitrogen for 30 minutes, and then heated to 80 ° C. with stirring, and the monomer solution prepared above was added dropwise over 3 hours using a dropping funnel. . The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization reaction solution was cooled with water and cooled to 30 ° C. or lower. After transferring the polymerization reaction liquid to a 2 L separatory funnel, the polymerization reaction liquid was uniformly diluted with 150 g of n-hexane, and 600 g of methanol was added and mixed. Next, 30 g of distilled water was added, and the mixture was further stirred and allowed to stand for 30 minutes. Thereafter, the lower layer was recovered to obtain a propylene glycol monomethyl ether acetate solution containing the polymer (A2-1) as a solid content (yield 60%). Mw of the polymer (A2-1) was 7,000, and Mw / Mn was 1.99. Content of the low molecular-weight component of a polymer (A2-1) was 0.05 mass%. As a result of ¹³ C-NMR analysis, the content ratios of the structural units derived from (M-20) and (M′-2) were 29.9 mol% and 70.1 mol%, respectively.

[Synthesis Examples 11 to 24 and Example 63]
(Synthesis of polymers (A2-2) to (A2-15) and (D-1))
Polymers (A2-2) to (A2-15) and (D-1) are obtained by performing the same operations as in Synthesis Example 11 except that the types and amounts of monomers shown in Table 3 below are used. Was synthesized. The total mass of the monomers used was 100 g. “-” In Table 3 indicates that the corresponding monomer was not used. The yield of each polymer, the content of low molecular weight components, Mw, Mw / Mn, and the content ratio of each structural unit are shown in Table 3.

<Preparation of photoresist composition>
Each component used for the preparation of the photoresist composition is shown below.

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

[[C] acid diffusion controller]
Each structural formula is shown below.
C-1: Triphenylsulfonium salicylate C-2: Triphenylsulfonium 10-camphorsulfonate C-3: N- (n-undecan-1-ylcarbonyloxyethyl) morpholine C-4: 2,6-dii -Propylaniline C-5: Tri-n-pentylamine

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

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

[Example 64]
[A] 100 parts by mass of (A1-1) as a polymer, [B] 8.5 parts by mass of (B-1) as an acid generator, [C] (C-1) 2 as an acid diffusion controller 3 parts by weight, (D-1) 3 parts by weight as a polymer, (F-1) 2,240 parts by weight and (F-2) 960 parts by weight as a solvent, and [G] A photoresist composition (J-1) was prepared by mixing 30 parts by mass of (G-1) as an uneven distribution accelerator and filtering through a membrane filter having a pore size of 0.2 μm.

[Examples 65 to 187 and Comparative Examples 1 and 2]
Except having used each component of the kind and content shown in the following Table 4, Table 5, and Table 6, it operated similarly to Example 64, photoresist composition (J-2)-(J-124), and (CJ-1) and (CJ-2) were prepared. “-” In Table 5 indicates that the corresponding component was not used.

<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 the lower antireflection film, each of the prepared photoresist compositions was applied using the 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, alkali development was performed using a 2.38% by 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)>
A negative resist pattern was prepared in the same manner as in the above resist pattern formation (1) except that n-butyl acetate was used instead of the TMAH aqueous solution and the organic solvent was developed, and washing with water was not performed. Formed.

<Formation of resist pattern (3)>
Using a spin coater (“CLEAN TRACK ACT8” manufactured by Tokyo Electron Ltd.) on the surface of an 8-inch silicon wafer, each photoresist composition shown in Table 9 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.

<Evaluation>
The above-described resist pattern was measured by the following method to evaluate the LWR performance, CDU performance, resolution, rectangularity of the cross-sectional shape, depth of focus, exposure margin, and MEEF performance of the photoresist composition. The evaluation results are shown in Tables 7-9. A scanning electron microscope (Hitachi High-Technologies “S-9380”) was used for measuring the resist pattern. In addition, the comparative example used as the determination criteria in LWR performance, CDU performance, resolution, depth of focus, exposure margin, and MEEF performance is compared to Comparative Examples 1 and 133 to 187 for Examples 64-132. This is Comparative Example 2. "-" In Table 8 and Table 9 indicates that it is a criterion for evaluation.

[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”.

[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”.

[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”.

  As is clear from the results in Tables 7 to 9, according to the photoresist composition, in the case of ArF exposure, in both alkali development and organic solvent development, LWR performance, CDU performance, resolution, cross-sectional shape Excellent rectangularity, depth of focus, exposure margin and MEEF performance. In the case of electron beam exposure, it can be seen that the LWR performance, CDU performance, resolution, rectangularity of the cross-sectional shape, depth of focus, and exposure margin are excellent. In general, it is known that the same tendency as in the case of EUV exposure can be obtained by electron beam exposure. Therefore, according to the photoresist composition of the example, even in the case of EUV exposure, It is estimated that the LWR performance is excellent.

According to the photoresist composition and the resist pattern forming method of the present invention, a resist pattern that exhibits excellent depth of focus and exposure margin, has low LWR and CDU, high resolution, and excellent cross-sectional rectangularity. can do. The polymer of the present invention can be suitably used as a polymer component of the photoresist composition. The compound of the present invention can be suitably used as a raw material monomer for the polymer. Accordingly, these can be suitably used for manufacturing semiconductor devices that are expected to be further miniaturized in the future.

Claims (5)

A polymer having a structural unit containing a group represented by the following formula (1), and a radiation-sensitive acid generator ,
A photoresist composition in which the structural unit is represented by any of the following formulas (2-1) to (2-3) .

(In the formula (1), R ¹ and R ² are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, provided that at least one of R ¹ and R ² is (It is a monovalent organic group having 1 to 20 carbon atoms. * Indicates a site bonded to a carbon atom in another part of the structural unit.)

(In the formulas (2-1) to (2-3), Z is a group represented by the above formula (1).
In formula (2-1), R ³ represents a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ⁴ is a group represented by the following formula (X) having 1 to 20 carbon atoms.
In formula (2-2), R ⁵ is a hydrogen atom or a methyl group. R ⁶ , R ⁷ and R ⁸ are each independently a hydrogen atom, a halogen atom, a hydroxy group or a monovalent organic group having 1 to 20 carbon atoms. Two or more of one or more of R ⁶ and R ⁷ may be combined with each other to form a ring structure having 3 to 20 ring members that is configured together with the carbon atom to which they are bonded. a is an integer of 1 to 4. When a is 2 or more, the plurality of R ⁶ may be the same or different, and the plurality of R ⁷ may be the same or different. R ⁹ is a single bond or a group represented by the following formula (X) having 1 to 20 carbon atoms. R ⁸ and R ⁹ may be combined with each other to form a ring structure with 3 to 20 ring members constituted together with the carbon atom to which they are bonded.
In formula (2-3), R ¹⁰ represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ¹¹ is a single bond or a group represented by the following formula (X) having 1 to 20 carbon atoms. )

(In formula (X), R ^{12 to} R ¹⁵ are each independently a hydrogen atom or a monovalent organic group having 1 to 18 carbon atoms. ** represents the above formulas (2-1) to (2 The site | part couple | bonded with Z in -3) is shown.) The photoresist composition according to claim 1, wherein the monovalent organic groups of R ¹ and R ² are acid dissociable groups. Forming a resist film;
A step of exposing the resist film, and a step of developing the exposed resist film,
A method for forming a resist pattern, wherein the resist film is formed from the photoresist composition according to claim 1 . Have a structural unit containing a group represented by the following formula (1 '),
The polymer in which the structural unit is represented by any of the following formulas (2-1) to (2-3) .

(In Formula (1 ′), R ^1A and R ^2A are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, provided that at least one of R ^1A and R ^2A Is a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, * indicates a site bonded to a carbon atom in the other part of the structural unit.

(In the formulas (2-1) to (2-3), Z is a group represented by the above formula (1 ′).
In formula (2-1), R ³ represents a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ⁴ is a group represented by the following formula (X) having 1 to 20 carbon atoms.
In formula (2-2), R ⁵ is a hydrogen atom or a methyl group. R ⁶ , R ⁷ and R ⁸ are each independently a hydrogen atom, a halogen atom, a hydroxy group or a monovalent organic group having 1 to 20 carbon atoms. Two or more of one or more of R ⁶ and R ⁷ may be combined with each other to form a ring structure having 3 to 20 ring members that is configured together with the carbon atom to which they are bonded. a is an integer of 1 to 4. When a is 2 or more, the plurality of R ⁶ may be the same or different, and the plurality of R ⁷ may be the same or different. R ⁹ is a single bond or a group represented by the following formula (X) having 1 to 20 carbon atoms. R ⁸ and R ⁹ may be combined with each other to form a ring structure with 3 to 20 ring members constituted together with the carbon atom to which they are bonded.
In formula (2-3), R ¹⁰ represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ¹¹ is a single bond or a group represented by the following formula (X) having 1 to 20 carbon atoms. )

(In formula (X), R ^{12 to} R ¹⁵ are each independently a hydrogen atom or a monovalent organic group having 1 to 18 carbon atoms. ** represents the above formulas (2-1) to (2 The site | part couple | bonded with Z in -3) is shown.) Represented by the following formula (iA) ,
Following formulas (2-1) to the compound Ru gives a structural unit represented by any one of (2-3).

(In Formula (iA), R ^1A and R ^2A are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, provided that at least one of R ^1A and R ^2A is (It is a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. Y is a monovalent group containing a polymerizable carbon-carbon double bond.)

(In formulas (2-1) to (2-3), Z is a group obtained by removing Y from the compound represented by formula (iA).
In formula (2-1), R ³ represents a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ⁴ is a group represented by the following formula (X) having 1 to 20 carbon atoms.
In formula (2-2), R ⁵ is a hydrogen atom or a methyl group. R ⁶ , R ⁷ and R ⁸ are each independently a hydrogen atom, a halogen atom, a hydroxy group or a monovalent organic group having 1 to 20 carbon atoms. Two or more of one or more of R ⁶ and R ⁷ may be combined with each other to form a ring structure having 3 to 20 ring members that is configured together with the carbon atom to which they are bonded. a is an integer of 1 to 4. When a is 2 or more, the plurality of R ⁶ may be the same or different, and the plurality of R ⁷ may be the same or different. R ⁹ is a single bond or a group represented by the following formula (X) having 1 to 20 carbon atoms. R ⁸ and R ⁹ may be combined with each other to form a ring structure with 3 to 20 ring members constituted together with the carbon atom to which they are bonded.
In formula (2-3), R ¹⁰ represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ¹¹ is a single bond or a group represented by the following formula (X) having 1 to 20 carbon atoms. )

(In formula (X), R ^{12 to} R ¹⁵ are each independently a hydrogen atom or a monovalent organic group having 1 to 18 carbon atoms. ** represents the above formulas (2-1) to (2 The site | part couple | bonded with Z in -3) is shown.)