JP5655579B2 - Radiation sensitive resin composition, pattern forming method, polymer and compound - Google Patents

Description

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

  With the miniaturization of structures in various electronic devices such as semiconductor devices and liquid crystal devices, it is necessary to refine the resist pattern in the lithography process. Currently, a resist pattern with a line width of about 90 nm can be formed using an ArF excimer laser, but in the future, a finer pattern formation will be required.

  Conventionally, chemically amplified resist compositions have been widely used for such pattern formation. This chemically amplified resist composition contains an acid generator component that generates an acid upon exposure, and a resin component that changes its solubility in a developer due to the action of this acid (see Patent Document 1), and an exposed portion. It is a composition that can form a pattern by utilizing a difference in dissolution rate from an unexposed portion. This chemically amplified resist composition has not only general characteristics such as resolution performance and sensitivity, but also MEEF (Mask Error Enhancement Factor) performance, which is an index representing mask reproducibility, when performing more precise line width control. It is also necessary to have such a fine shape control characteristic.

  Examples of such chemically amplified resist compositions include (1) a radiation-sensitive resin composition containing a lactone-containing (meth) acrylic polymer (see Patent Documents 2 to 4), and (2) an acrylic having a cyclic sulfonyl structure. A radiation-sensitive resin composition containing an acid ester derivative (see Patent Document 5) and the like are known. However, the radiation-sensitive resin composition (1) is excellent in resolution performance and depth of focus, but has insufficient lithography performance such as MEEF, etching resistance, etc., and can cope with recent miniaturization of devices. is not. In addition, the radiation sensitive resin composition (2) has an improved LWR (Line Width Roughness), but has insufficient lithography performance such as MEEF.

JP 59-45439 A JP-A-9-90637 JP-A-10-274852 JP 2000-26446 A JP 2009-196944 A

  The present invention has been made on the basis of the circumstances as described above, and the object thereof is a radiation-sensitive resin composition and a pattern forming method that are excellent in pattern formability and etching resistance and excellent in lithography performance such as MEEF performance. It is to provide a polymer and a compound suitably used for these.

（式（１）中、Ｘは、単結合又は２価の連結基である。Ｒ^２は、炭素数１〜２０の脂肪族鎖状炭化水素基又は炭素数４〜２０の脂環式炭化水素基である。Ｚ^１及びＺ^２は、それぞれ独立して、炭素数１〜１４の２価の脂肪族炭化水素基であり、Ｒ^２の結合している炭素原子及び−ＳＯ_２−と共に核原子数４〜３０の脂肪族複素環基を形成する。但し、Ｚ^１とＺ^２とが互いに結合していてもよい。上記Ｚ^１及びＺ^２の脂肪族炭化水素基が有する水素原子の一部又は全部は置換されていてもよい。） The invention made to solve the above problems is
[A] a polymer having a structural unit (I) containing a group R ^S represented by the following formula (1) (hereinafter also referred to as “[A] polymer”), and [B] a radiation-sensitive acid generator (Hereinafter also referred to as “[B] acid generator”)
A radiation-sensitive resin composition.

(In formula (1), X, .R ² is a single bond or a divalent linking group, having 1 to 20 carbon atoms linear aliphatic hydrocarbon group or an alicyclic hydrocarbon having 4 to 20 carbon atoms Z ¹ and Z ² are each independently a divalent aliphatic hydrocarbon group having 1 to 14 carbon atoms, and a nuclear atom together with the carbon atom to which R ² is bonded and —SO ₂ —. An aliphatic heterocyclic group of 4 to 30 is formed, provided that Z ¹ and Z ² may be bonded to each other, part of the hydrogen atoms possessed by the aliphatic hydrocarbon group of Z ¹ and Z ² Or all may be substituted.)

The [A] polymer contained in the radiation-sensitive resin composition has an appropriate polarity by having the group ^{RS of the} specific structure including the cyclic sulfonyl structure represented by the formula (1). B] Compatibility with other components such as an acid generator is improved. Therefore, the said radiation sensitive resin composition is excellent in pattern formation property, MEEF performance, etc. Moreover, the said radiation sensitive resin composition also improves etching tolerance because the [A] polymer has a sulfur atom. Furthermore, in the structural unit (I), since the carbon bonded to the ester group is a tertiary carbon, the cyclic sulfonyl structure portion is easily dissociated by an acid. Therefore, the radiation sensitive resin composition containing such a [A] polymer can change the solubility in a developer by the action of an acid generated from the [B] acid generator in the exposed portion, The contrast between the exposed area and the unexposed area is improved, and a good pattern can be formed.

（式（１−１）中、Ｒ^１は、水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。） The structural unit (I) is a structural unit (I-1) represented by the following formula (1-1), a structural unit (I-2) represented by the following formula (1-2), and the following formula ( It is preferably at least one structural unit selected from the group consisting of the structural unit (I-3) represented by 1-3).

(In Formula (1-1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.)

  Thus, the said radiation sensitive resin composition is pattern-forming property because the polymer principal chain part in a [A] polymer is a structure represented by said Formula (1-1)-(1-3). Excellent etching resistance and MEEF performance.

As said aliphatic hydrocarbon group of Z < ¹ > and Z < ² >, a C1-C8 aliphatic chain hydrocarbon group is preferable. The said radiation sensitive resin composition is excellent by pattern formation property, etching tolerance, and MEEF performance because [A] polymer has the group of the said specific structure.

  The aliphatic heterocyclic group is preferably a monocyclic group. The said radiation sensitive resin composition can further improve pattern formation property, etching tolerance, and MEEF performance because [A] polymer has group of the above-mentioned specific structure of a monocycle.

  The divalent linking group for X preferably contains an ester group. The said radiation sensitive resin composition can further improve pattern formation property, etching tolerance, and MEEF performance because the connection group of the main chain of a [A] polymer and a cyclic sulfonyl group contains an ester group.

  The radiation-sensitive resin composition preferably further contains a polymer having a higher fluorine atom content than the [C] [A] polymer (hereinafter also referred to as “[C] polymer”). When the radiation sensitive resin composition contains a [C] polymer that is a water repellent resin, the [C] polymer tends to be unevenly distributed in the vicinity of the resist film surface when a resist film is formed. Therefore, it is possible to suppress the elution of the acid generator, the acid diffusion control agent, etc. into the immersion medium during the immersion exposure, and further improve the effects of the present invention such as improvement of pattern formability, etching resistance, and MEEF performance. can do. Further, due to the water-repellent characteristics of the [C] polymer, 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.

The pattern forming method of the present invention comprises:
(1) A resist film forming step of applying a radiation sensitive resin composition of the present invention on a substrate to form a resist film;
(2) an exposure step of irradiating at least a part of the resist film with radiation; and (3) a development step of developing the exposed resist film.

  According to the pattern forming method, since the radiation-sensitive resin composition has the performance as described above, a good fine pattern can be formed.

（式（１）中、Ｘは、単結合又は２価の連結基である。Ｒ^２は、炭素数１〜２０の脂肪族鎖状炭化水素基又は炭素数４〜２０の脂環式炭化水素基である。Ｚ^１及びＺ^２は、それぞれ独立して、炭素数１〜１４の２価の脂肪族炭化水素基であり、Ｒ^２の結合している炭素原子及び−ＳＯ_２−と共に核原子数４〜３０の脂肪族複素環基を形成する。但し、Ｚ^１とＺ^２とが互いに結合していてもよい。上記Ｚ^１及びＺ^２の脂肪族炭化水素基が有する水素原子の一部又は全部は置換されていてもよい。） The polymer of the present invention has a structural unit (I) containing a group R ^S represented by the following formula (1).

(In formula (1), X, .R ² is a single bond or a divalent linking group, having 1 to 20 carbon atoms linear aliphatic hydrocarbon group or an alicyclic hydrocarbon having 4 to 20 carbon atoms Z ¹ and Z ² are each independently a divalent aliphatic hydrocarbon group having 1 to 14 carbon atoms, and a nuclear atom together with the carbon atom to which R ² is bonded and —SO ₂ —. An aliphatic heterocyclic group of 4 to 30 is formed, provided that Z ¹ and Z ² may be bonded to each other, part of the hydrogen atoms possessed by the aliphatic hydrocarbon group of Z ¹ and Z ² Or all may be substituted.)

The polymer has a group R ^S having the specific structure including a cyclic sulfonyl structure. Therefore, the radiation sensitive resin composition containing the said polymer is excellent in pattern formation property. Moreover, it is excellent also in etching resistance by containing a sulfur atom. Furthermore, since it is excellent also in MEEF performance etc., the said polymer is used suitably for the radiation sensitive resin composition etc. which are used for lithography technique.

（式（１−１）中、Ｒ^１は、水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。） The structural unit (I) is a structural unit (I-1) represented by the following formula (1-1), a structural unit (I-2) represented by the following formula (1-2), and the following formula ( It may be at least one kind of structural unit selected from the group consisting of the structural unit (I-3) represented by 1-3).

(In Formula (1-1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.)

  [A] The polymer main chain portion in the polymer has a structure represented by the above formulas (1-1) to (1-3), so that the radiation-sensitive resin composition containing the polymer has a pattern. Formability, MEEF performance and etching resistance are further improved.

（式（１）中、Ｘは、単結合又は２価の連結基である。Ｒ^２は、炭素数１〜２０の脂肪族鎖状炭化水素基又は炭素数４〜２０の脂環式炭化水素基である。Ｚ^１及びＺ^２は、それぞれ独立して、炭素数１〜１４の２価の脂肪族炭化水素基であり、Ｒ^２の結合している炭素原子及び−ＳＯ_２−と共に核原子数４〜３０の脂肪族複素環基を形成する。但し、Ｚ^１とＺ^２とが互いに結合していてもよい。上記Ｚ^１及びＺ^２の脂肪族炭化水素基が有する水素原子の一部又は全部は置換されていてもよい。） The compound of the present invention contains a group R ^S represented by the following formula (1).

(In formula (1), X, .R ² is a single bond or a divalent linking group, having 1 to 20 carbon atoms linear aliphatic hydrocarbon group or an alicyclic hydrocarbon having 4 to 20 carbon atoms Z ¹ and Z ² are each independently a divalent aliphatic hydrocarbon group having 1 to 14 carbon atoms, and a nuclear atom together with the carbon atom to which R ² is bonded and —SO ₂ —. An aliphatic heterocyclic group of 4 to 30 is formed, provided that Z ¹ and Z ² may be bonded to each other, part of the hydrogen atoms possessed by the aliphatic hydrocarbon group of Z ¹ and Z ² Or all may be substituted.)

When the compound has the group R ^S having the specific structure represented by the above formula (1), it can be suitably used as a monomer for incorporating the structural unit (I) into the polymer. The compound can be easily synthesized from a heterocyclic compound containing a sulfur atom as a ring constituent atom.

（式（ｉ）中、Ｒ^１は、水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。） The compound of the present invention is represented by the following formula (i).

(In formula (i), R ¹ represents a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.)

  By having the structure represented by the above formula (i), the compound can be more suitably used as a monomer for incorporating the structural unit (I) into the polymer.

Here, the “chain hydrocarbon group” means a hydrocarbon group composed of only a chain structure without including a cyclic structure in the main chain, and includes both a linear hydrocarbon group and a branched hydrocarbon group. Shall be included. However, a hetero atom is not included in the skeleton chain.
The “alicyclic hydrocarbon group” means a hydrocarbon group that includes only an aliphatic cyclic hydrocarbon structure as a ring structure and does not include an aromatic ring structure. However, a hetero atom is not included in the skeleton chain. Moreover, it does not need to be comprised only by the structure of an aliphatic cyclic hydrocarbon, and the chain structure may be included in the part.
The “aliphatic hydrocarbon group” is a hydrocarbon group including both the “chain hydrocarbon group” and the “alicyclic hydrocarbon group”.
The “radiation” of the “radiation sensitive resin composition” is a concept including visible light, ultraviolet light, far ultraviolet light, X-rays, charged particle beams and the like.
“Number of nuclear atoms” refers to the total number of atoms forming a carbocyclic or heterocyclic ring.

  As described above, since the radiation-sensitive resin composition of the present invention contains a polymer having a specific structural unit containing a cyclic sulfonyl structure, it is excellent in pattern formability and etching resistance, and MEEF and the like. As a result, it can contribute to fine pattern formation.

It is a figure which shows the pattern cross-sectional shape used for evaluation of pattern formation property.

<Radiation sensitive resin composition>
The radiation sensitive resin composition of the present invention contains a [A] polymer and a [B] acid generator. Furthermore, it is preferable to contain a [C] polymer. In addition, you may contain an arbitrary component, unless the effect of this invention is impaired. Hereinafter, each component will be described in detail.

<[A] polymer>
[A] The polymer has a structural unit (I) containing a group R ^S represented by the above formula (1). [A] Since the polymer has a group having the above-mentioned specific structure containing a cyclic sulfonyl structure, the polymer exhibits an appropriate polarity, and [B] compatibility with other components such as an acid generator is improved. Resin composition is excellent in pattern formability, MEEF performance, and the like. Moreover, since the [A] polymer has a sulfur atom, the radiation-sensitive resin composition is also excellent in etching resistance. Furthermore, in the structural unit (I), since the carbon bonded to the ester group is a tertiary carbon, the cyclic sulfonyl structure portion is easily dissociated by an acid. Therefore, the radiation sensitive resin composition containing such a [A] polymer can change the solubility in a developer by the action of an acid generated from the [B] acid generator in the exposed portion, A good pattern in which the contrast between the exposed part and the unexposed part is improved can be formed.
[A] The polymer has the structural unit (I) and may further have “another structural unit” other than the structural unit (I). Hereinafter, each structural unit will be described in detail.

[Structural unit (I)]
The structural unit (I) is a structural unit containing the group R ^S represented by the formula (1).
In formula (1), X is a single bond or a divalent linking group. R ² is an aliphatic chain hydrocarbon group having 1 to 20 carbon atoms or an alicyclic hydrocarbon group having 4 to 20 carbon atoms. Z ¹ and Z ² are each independently a divalent aliphatic hydrocarbon group having 1 to 14 carbon atoms, and together with the carbon atom to which R ² is bonded and —SO ₂ —, the number of nuclear atoms is 4 to 30. An aliphatic heterocyclic group of However, Z ¹ and Z ² may be bonded to each other. Some or all of the hydrogen atoms contained in the aliphatic hydrocarbon groups of Z ¹ and Z ² may be substituted.

  Examples of the divalent linking group represented by X include, for example, a divalent chain hydrocarbon group having 1 to 30 carbon atoms, a divalent aliphatic cyclic hydrocarbon group having 3 to 30 carbon atoms, and 6 carbon atoms. To 30 divalent aromatic hydrocarbon groups, or a divalent group obtained by combining these with an ether group, an ester group, a carbonyl group, an imino group, or an amide group. The divalent linking group may have a substituent.

Examples of the divalent chain hydrocarbon group having 1 to 30 carbon atoms include:
Chain saturated hydrocarbon groups such as methanediyl, ethanediyl, propanediyl, butanediyl, pentanediyl, hexanediyl, octanediyl, decandiyl, undecandiyl, hexadecandiyl, icosanediyl;
Ethenediyl group, propenediyl group, butenediyl group, pentenediyl group, hexenediyl group, octenediyl group, decenediyl group, undecenediyl group, hexadecenediyl group, icosendiyl group, ethynediyl group, propynediyl group, butynediyl group, octanediyl group, butadienediyl group, hexadiene group And chain unsaturated hydrocarbon groups such as alkynediyl groups such as octatrienediyl group.

Examples of the divalent aliphatic cyclic hydrocarbon group having 3 to 30 carbon atoms include:
Monocyclic saturated hydrocarbons such as cyclopropanediyl, cyclobutanediyl, cyclopentanediyl, cyclohexanediyl, cycloheptanediyl, cyclooctanediyl, cyclodecanediyl, methylcyclohexanediyl, ethylcyclohexanediyl Group;
Cyclobutenediyl group, cyclopentenediyl group, cyclohexenediyl group, cycloheptenediyl group, cyclooctenediyl group, cyclodecenediyl group, cyclopentadienediyl group, cyclohexadienediyl group, cyclooctadienediyl group, cyclodecadienediyl group Monocyclic unsaturated hydrocarbon groups such as
Bicyclo [2.2.1] heptanediyl group, bicyclo [2.2.2] octanediyl group, tricyclo [5.2.1.0 ^2,6 ] decanediyl group, tricyclo [3.3.1.1 ^{3, 7} ] decandiyl group, tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] a polycyclic saturated hydrocarbon group such as a dodecanediyl group or an adamantanediyl group;
Bicyclo [2.2.1] heptenediyl group, bicyclo [2.2.2] octenediyl group, tricyclo [5.2.1.0 ^2,6 ] decenediyl group, tricyclo [3.3.1.1 ^3,7 ] Decenediyl group, tetracyclo [6.2.1.1 ^3,6 . And a polycyclic unsaturated hydrocarbon group such as 0 ^2,7 ] dodecenediyl group.

  Examples of the divalent aromatic hydrocarbon group having 6 to 30 carbon atoms include a phenylene group, a biphenylene group, a terphenylene group, a benzylene group, a phenyleneethylene group, a phenylenecyclohexylene group, and a naphthylene group.

  In addition, specific examples of the divalent linking group include groups represented by the following formulas (X-1) to (X-7).

In the above formulas (X-1) to (X-7), R ^x1 and R ^x2 are each independently a divalent chain hydrocarbon group having 1 to 30 carbon atoms and a divalent group having 3 to 30 carbon atoms. An aliphatic cyclic hydrocarbon group, and a divalent aromatic hydrocarbon group having 6 to 30 carbon atoms. * Indicates a binding site to the ester group of the above formula (1).

The R ^x1 and R ^x2 are preferably a C 1-3 divalent chain hydrocarbon group having 1 to 3 carbon atoms.

  Among these, as said X, the bivalent group containing a single bond and an ester group is preferable, and the bivalent group containing the ester group represented by a single bond and said Formula (X-7) is more preferable. Of these, a single bond is more preferable.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms represented by R ² include:
Chain saturated hydrocarbon groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, hexadecyl;
Examples thereof include chain unsaturated hydrocarbon groups such as ethenyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, octenyl group, hexadecenyl group, ethynyl group, propynyl group, and butynyl group.

Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by R ² include:
Monocyclic saturated hydrocarbon groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclodecyl group, methylcyclohexyl group, and ethylcyclohexyl group;
Monocyclic unsaturated carbonization such as cyclobutenyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, cyclooctenyl, cyclodecenyl, cyclopentadienyl, cyclohexadienyl, cyclooctadienyl, cyclodecadienyl A hydrogen group;
Bicyclo [2.2.1] heptyl group, bicyclo [2.2.2] octyl group, tricyclo [5.2.1.0 ^2,6 ] decyl group, tricyclo [3.3.1.1 ^3,7 ] Decyl group, tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] a polycyclic saturated hydrocarbon group such as a dodecyl group or an adamantyl group;
Bicyclo [2.2.1] heptenyl group, bicyclo [2.2.2] octenyl group, tricyclo [5.2.1.0 ^2,6 ] decenyl group, tricyclo [3.3.1.1 ^3,7 ] Decenyl group, tetracyclo [6.2.1.1 ^3,6 . And a polycyclic unsaturated hydrocarbon group such as 0 ^2,7 ] dodecenyl group.

Examples of the divalent aliphatic hydrocarbon group having 1 to 14 carbon atoms represented by Z ¹ and Z ² include a divalent aliphatic chain hydrocarbon group having 1 to 14 carbon atoms and a divalent group having 3 to 14 carbon atoms. Of the alicyclic hydrocarbon group.

Examples of the divalent aliphatic chain hydrocarbon group having 1 to 14 carbon atoms include:
Chain saturated hydrocarbon groups such as methanediyl group, ethanediyl group, propanediyl group, butanediyl group, pentanediyl group, hexanediyl group, octanediyl group, decanediyl group;
Ethenediyl group, propenediyl group, butenediyl group, pentenediyl group, hexenediyl group, octenediyl group, decenediyl group, ethynediyl group, propynediyl group, butynediyl group, octynediyl group, butadienediyl group, hexadienediyl group, octatrienediyl group, etc. Saturated hydrocarbon group etc. are mentioned.

As said C3-C14 bivalent alicyclic hydrocarbon group, for example,
Monocyclic saturated hydrocarbons such as cyclopropanediyl, cyclobutanediyl, cyclopentanediyl, cyclohexanediyl, cycloheptanediyl, cyclooctanediyl, cyclodecanediyl, methylcyclohexanediyl, ethylcyclohexanediyl Group;
Cyclobutenediyl group, cyclopentenediyl group, cyclohexenediyl group, cycloheptenediyl group, cyclooctenediyl group, cyclodecenediyl group, cyclopentadienediyl group, cyclohexadienediyl group, cyclooctadienediyl group, cyclodecadienediyl group Monocyclic unsaturated hydrocarbon groups such as
Bicyclo [2.2.1] heptanediyl group, bicyclo [2.2.2] octanediyl group, tricyclo [5.2.1.0 ^2,6 ] decanediyl group, tricyclo [3.3.1.1 ^{3, 7} ] decandiyl group, tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] a polycyclic saturated hydrocarbon group such as a dodecanediyl group or an adamantanediyl group;
Bicyclo [2.2.1] heptenediyl group, bicyclo [2.2.2] octenediyl group, tricyclo [5.2.1.0 ^2,6 ] decenediyl group, tricyclo [3.3.1.1 ^3,7 ] Decenediyl group, tetracyclo [6.2.1.1 ^3,6 . And a polycyclic unsaturated hydrocarbon group such as 0 ^2,7 ] dodecenediyl group.

  Among these, a C1-C14 bivalent aliphatic chain hydrocarbon group is preferable, and a C1-C8 aliphatic chain hydrocarbon group is more preferable. Of these, an aliphatic chain saturated hydrocarbon group having 1 to 8 carbon atoms is preferable, and an aliphatic chain saturated hydrocarbon group having 1 or 2 carbon atoms is more preferable.

The divalent aliphatic heterocyclic group having 4 to 30 nucleus atoms may be a monocyclic aliphatic heterocyclic group or a polycyclic aliphatic heterocyclic group. The aliphatic heterocyclic group is monocyclic when Z ¹ and Z ² are chain hydrocarbon groups and Z ¹ and Z ² are not bonded to each other. In addition, when Z ¹ and / or Z ² is an alicyclic hydrocarbon group, a polycyclic aliphatic complex may be formed regardless of whether Z ¹ and Z ² are bonded to each other. Form a ring group. The aliphatic heterocyclic group is preferably a monocyclic group.
Among the divalent aliphatic heterocyclic groups having 4 to 30 nuclear atoms, divalent aliphatic heterocyclic groups having 4 to 10 nuclear atoms are preferable, and divalent aliphatic heterocyclic groups having 5 or 6 nuclear atoms are preferable. A cyclic group is more preferable.

Examples of the substituent in which part or all of the hydrogen atoms of the aliphatic hydrocarbon group represented by Z ¹ and Z ² may be substituted include a halogen atom, a hydroxyl group, a carboxyl group, a keto group, and a sulfonamide group. , Amino group, amide group, cyano group and the like.

Examples of the group R ^S represented by the above formula (1) include groups represented by the following formulas (rs-1) to (rs-28).

In said formula, R < ² > is synonymous with the said Formula (1).

  Among these, groups represented by the above formulas (rs-1) to (rs-3) are preferable from the viewpoint of pattern formation, MEEF performance, and etching resistance.

  As the structural unit (I), the structural unit (I-1) represented by the above formula (1-1), the structural unit (I-2) represented by the above formula (1-2), and the above formula ( It is preferably at least one structural unit selected from the group consisting of the structural unit (I-3) represented by 1-3).

In formula (1-1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. In formulas (1-1), (1-2), and (1-3), R ^S is each independently a group represented by the above formula (1).

  Examples of the structural unit (I-1) represented by the formula (1-1) include structural units represented by the following formulas (1-1-1) to (1-1-28). .

In said formula, R < ¹ > is synonymous with the said Formula (1-1). R ² has the same meaning as in the above formula (1).

  Examples of the structural unit (I-2) represented by the above formula (1-2) include structural units represented by the following formulas (1-2-1) to (1-2-7). .

In said formula, R < ² > is synonymous with the said Formula (1).

  Examples of the structural unit (I-3) represented by the above formula (1-3) include structural units represented by the following formulas (1-3-1) to (1-3-7). .

  Among these, the structural unit (I) is preferably a structural unit represented by the above formula (1-1) from the viewpoint of pattern formation, MEEF performance, and etching resistance improvement. The structural units represented by 1-1) to (1-1-3) are more preferable.

  Examples of the preferable structural unit include a structural unit represented by the following formula.

In said formula, R < ¹ > is synonymous with the said Formula (1-1).

Examples of the monomer that gives the structural unit (I) include compounds represented by the following formulas (i) to (iii).

In said formula (i), R < ¹ > is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. In the above formulas (i) to (iii), R ^S is a group represented by the above formula (1).

  Among these, the compound represented by the above formula (i) is preferable, and examples of the compound represented by the above formula (i) include a compound represented by the following formula.

  The synthesis of the compound represented by the above formula (i) can be performed, for example, according to the following scheme.

  As shown in the above scheme, for example, a cyclic sulfide compound is oxidized with an oxidizing agent such as hydrogen peroxide to obtain a cyclic sulfone compound. An alkylmagnesium bromide (Grignard reagent) prepared from 1-bromoalkane and magnesium is reacted with a cyclic sulfone compound in a solvent such as diethyl ether to obtain a 1-alkyl-1-hydroxy-cyclic sulfone compound. It is done. Furthermore, the compound of this invention represented by the said Formula (i) can be obtained by making methacryloyl chloride etc. react in base presence, such as organic amine.

  Examples of the oxidizing agent used in the oxidation reaction include hydrogen peroxide, metachloroperbenzoic acid, t-butyl hydroperoxide, potassium peroxysulfate, potassium permanganate, sodium perborate, sodium metaiodate, chromic acid, and dichrome. Examples thereof include sodium acid, halogen, iodobenzene dichloride, iodobenzene diacetate, osmium oxide (VIII), ruthenium oxide (VIII), sodium hypochlorite, sodium chlorite, oxygen gas, ozone gas and the like. Of these, hydrogen peroxide, metachloroperbenzoic acid, and t-butyl hydroperoxide are preferred. A transition metal catalyst can be used. Examples of the transition metal catalyst include heteropolyacids such as phosphotungstic acid, phosphomolybdic acid and silicotungstic acid, or salts thereof, disodium tungstate, iron (III) salt, copper (II) salt, ruthenium (III). Examples thereof include salts and selenium oxide (IV). Of these, disodium tungstate is preferred.

  The Grignard reagent can be prepared by a known method by reacting an alkyl halide with magnesium. The Grignard reaction is carried out in the presence of an anhydrous inert organic solvent. Examples of inert organic solvents include diethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, tetrahydrofuran (THF), dioxane, tetrahydropyran, n-hexane, heptane, nonane, decane, cyclohexane, benzene, toluene, xylene, and trimethylbenzene. Or ethylbenzene etc. are mentioned.

  The inert organic solvent after the Grignard reaction contains a magnesium salt produced by the reaction in addition to the target compound. If water or a dilute acid is added to this and washed with water, inorganic salts are removed and the produced organic compound is separated.

  [A] The content of the structural unit (I) in the polymer is preferably 5 mol% or more and 80 mol% or less, and preferably 5 mol% or more and 40 mol% or less with respect to all the structural units constituting the [A] polymer. Is more preferable. 15 mol% or more and 40 mol% or less are more preferable. [A] If the content of the structural unit (I) in the polymer is less than 5 mol%, lithography performance such as MEEF performance may be insufficient, and if it exceeds 80 mol%, pattern formability is reduced. There is a case. [A] The polymer may have one or more structural units (I).

  [A] The polymer is an (a1) structural unit containing an acid dissociable group, (a2) a structural unit containing a polar group, (a3) a structural unit having a lactone structure or a cyclic carbonate structure, and a structural unit having a fluorine atom. (A4) structural units or other structural units such as (a5) structural units can be further included. The structural unit can contain one kind or two or more kinds. Hereinafter, each structural unit will be described in detail.

[(A1) Structural unit]
(A1) As a structural unit, the structural unit shown by following formula (2) is mentioned.

In the above formula (2), R ^a1 is a hydrogen atom or a methyl group. R ^{a2 to} R ^a4 are each independently an alkyl group having 1 to 4 carbon atoms or an alicyclic hydrocarbon group having 4 to 20 carbon atoms. However, R ^a3 and R ^a4 may be bonded to each other to form a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms together with the carbon atom to which they are bonded.

  Examples of the alkyl group having 1 to 4 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, and t-butyl group. Is mentioned.

The alicyclic hydrocarbon group having 4 to 20 carbon atoms, or the alicyclic hydrocarbon group having 4 to 20 carbon atoms formed together with the carbon atom to which R ^a3 and R ^a4 are bonded to each other. Includes a polycyclic alicyclic group having a bridged skeleton such as an adamantane skeleton or a norbornane skeleton; and a monocyclic alicyclic group having a cycloalkane skeleton such as cyclopentane or cyclohexane. In addition, these groups may be substituted with one or more linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms, for example.

  (A1) As the structural unit, a structural unit represented by the following formula is preferred.

In the above formula, R ^a1 has the same ^{meaning as} the above formula (2). R ^a5 is an alkyl group having 1 to 4 carbon atoms. m is an integer of 1-6.

  Among these, structural units represented by the following formulas (2-1) to (2-20) are more preferable, and (2-3), (2-4), (2-11) and (2-12) are Particularly preferred.

In the above formula, R ^a1 has the same ^{meaning as} the above formula (2).

  In the [A] polymer, the content ratio of the (a1) structural unit is preferably 5% by mole to 80% by mole, and preferably 10% by mole to 80% by mole with respect to all the structural units constituting the [A] polymer. Is more preferable, and 20 mol% to 70 mol% is particularly preferable. When the content ratio of the structural unit (a1) exceeds 80 mol%, the adhesion of the resist film is lowered, and pattern collapse or pattern peeling may occur. In addition, the [A] polymer may have 1 type or 2 types or more of (a1) structural units.

(A1) Monomers that give structural units include, for example, (meth) acrylic acid-bicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-bicyclo [2.2.2] octa. 2-yl ester, (meth) acrylic acid-tricyclo [5.2.1.0 ^2,6 ] dec-7-yl ester, (meth) acrylic acid-tricyclo [3.3.1.1 ^3,7 Deca-1-yl ester, (meth) acrylic acid-tricyclo [3.3.1.1 ^3,7 ] dec-2-yl ester, and the like.

[(A2) Structural unit]
[A] The polymer preferably further includes (a2) a structural unit containing a polar group represented by the following formula. Examples of the “polar group” herein include a hydroxyl group, a carboxyl group, a keto group, a sulfonamide group, an amino group, an amide group, and a cyano group.

  (A2) As a structural unit, the structural unit shown, for example by a following formula is mentioned.

In the above formula, R ^a9 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

  Among these, the structural unit represented by the above formula (a2-1) and the structural unit represented by (a2-3) are preferable.

  In the [A] polymer, the content ratio of the (a2) structural unit is preferably 5 mol% to 80 mol%, and preferably 8 mol% to 40 mol%, based on all structural units constituting the [A] polymer. Is more preferable. In addition, the [A] polymer may have 1 type (s) or 2 or more types of (a2) structural units.

[(A3) Structural unit]
[A] The polymer may further include (a3) a structural unit having a lactone structure or a cyclic carbonate structure. (A3) By having the structural unit, the adhesion of the resist film to the substrate can be improved.

  (A3) As a structural unit, the structural unit shown by a following formula is mentioned, for example.

In the above formula, R ^a6 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ^a7 is a hydrogen atom or a methyl group. R ^a8 is a hydrogen atom or a methoxy group. Z ^a1 is a single bond or a methylene group. Z ^a2 is a methylene group or an oxygen atom. a and b are 0 or 1;

  (A3) As the structural unit, a structural unit represented by the following formula is preferred.

In the above formula, R ^a6 is a hydrogen atom or a methyl group.

  In the [A] polymer, the content ratio of the (a3) structural unit is preferably 5 mol% or more and 70 mol% or less, and preferably 10 mol% or more and 50 mol based on all the structural units constituting the [A] polymer. % Or less is more preferable. By setting it as such a content rate, the adhesiveness of a resist and a board | substrate can be improved. On the other hand, when it exceeds 70 mol%, a good pattern may not be obtained.

  (A3) As a preferable monomer which gives a structural unit, the monomer as described in international publication 2007/116664 pamphlet is mentioned, for example.

[(A4) Structural unit]
(A4) The structural unit is a structural unit represented by the following formula (3).

In the above formula (3), R ^a9 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ^a10 is a linear or branched alkyl group having 1 to 6 carbon atoms having a fluorine atom, or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms having a fluorine atom. However, the alkyl group and the alicyclic hydrocarbon group may be partially or entirely substituted with hydrogen atoms.

  As said C1-C6 linear or branched alkyl group, a methyl group, an ethyl group, a propyl group, a butyl group etc. are mentioned, for example.

  Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms include a cyclopentyl group, a cyclopentylpropyl group, a cyclohexyl group, a cyclohexylmethyl group, a cycloheptyl group, a cyclooctyl group, and a cyclooctylmethyl group.

  Of the structural unit (a4) represented by the above formula (3), for example, structural units represented by the following formulas (3-1) and (3-2) are preferable.

In formulas (3-1) and (3-2), R ^a9 has the same ^meaning as formula (3) above.

  (A4) Examples of monomers that give structural units include trifluoromethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, perfluoroethyl (meth) acrylate, perfluoro n-propyl ( (Meth) acrylate, perfluoro i-propyl (meth) acrylate, perfluoro n-butyl (meth) acrylate, perfluoro i-butyl (meth) acrylate, perfluoro t-butyl (meth) acrylate, perfluorocyclohexyl (meth) Acrylate, 2- (1,1,1,3,3,3-hexafluoro) propyl (meth) acrylate, 1- (2,2,3,3,4,4,5,5-octafluoro) pentyl ( (Meth) acrylate, 1- (2,2,3,3,4,4,5,5-octafluoro) hex (Meth) acrylate, perfluorocyclohexylmethyl (meth) acrylate, 1- (2,2,3,3,3-pentafluoro) propyl (meth) acrylate, 1- (2,2,3,3,4, 4,4-Heptafluoro) penta (meth) acrylate, 1- (3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10- Heptadecafluoro) decyl (meth) acrylate, 1- (5-trifluoromethyl-3,3,4,4,5,6,6,6-octafluoro) hexyl (meth) acrylate and the like.

  In the [A] polymer, the content of the (a4) structural unit is preferably 2 mol% to 70 mol%, and preferably 5 mol% to 30 mol% with respect to all the structural units constituting the [A] polymer. More preferred. The [A] polymer may have (a4) one or more structural units.

[(A5) Structural unit]
(A5) The structural unit is a structural unit represented by the following formula (4).

In formula (4), R ^a11 is a hydrogen atom, a methyl group or a trifluoromethyl group. R ^a12 is a (k + 1) ^-valent linking group. ^Xa is ^a divalent linking group having ^a fluorine atom. R ^a13 is a hydrogen atom or a monovalent organic group. k is an integer of 1 to 3. However, when k is 2 or 3, the plurality of X and R ^a13 may be the same or different.

In the above formula (4), the (k + 1) -valent linking group represented by R ^a12 is, for example, a linear or branched hydrocarbon group having 1 to 30 carbon atoms or an alicyclic hydrocarbon having 3 to 30 carbon atoms. A group, an aromatic hydrocarbon group having 6 to 30 carbon atoms, or one or more groups selected from the group consisting of these groups and an oxygen atom, a sulfur atom, an ether group, an ester group, a carbonyl group, an imino group, and an amide group And a combination of these. The (k + 1) -valent linking group may have a substituent.

  Examples of the linear or branched hydrocarbon group having 1 to 30 carbon atoms include (k + 1) hydrocarbon groups such as methane, ethane, propane, butane, pentane, hexane, heptane, decane, icosane and triacontane. And a group in which a hydrogen atom is removed.

Examples of the alicyclic hydrocarbon group having 3 to 30 carbon atoms include monocyclic saturated hydrocarbons such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclodecane, methylcyclohexane, and ethylcyclohexane;
Monocyclic unsaturated hydrocarbons such as cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclodecene, cyclopentadiene, cyclohexadiene, cyclooctadiene, cyclodecadiene;
Bicyclo [2.2.1] heptane, bicyclo [2.2.2] octane, tricyclo [5.2.1.0 ^2,6 ] decane, tricyclo [3.3.1.1 ^3,7 ] decane, Tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] polycyclic saturated hydrocarbons such as dodecane and adamantane;
Bicyclo [2.2.1] heptene, bicyclo [2.2.2] octene, tricyclo [5.2.1.0 ^2,6 ] decene, tricyclo [3.3.1.1 ^3,7 ] decene, Tetracyclo [6.2.1.1 ^3,6 . And a group obtained by removing (m + 1) hydrogen atoms from a polycyclic hydrocarbon group such as 0 ^2,7 ] dodecene.

  Examples of the aromatic hydrocarbon group having 6 to 30 carbon atoms include an aromatic hydrocarbon group such as benzene, naphthalene, phenanthrene, anthracene, tetracene, pentacene, pyrene, picene, toluene, xylene, ethylbenzene, mesitylene, cumene, and the like (m + 1 ) Groups from which a single hydrogen atom has been removed.

In the formula (4), the divalent linking group having a fluorine atom represented by X ^a, include a divalent linear hydrocarbon group having 1 to 20 carbon atoms having a fluorine atom. The X ^a, for example, structures represented by Formulas ^{(X a -1) ~ (X} a -6) and the like.

X ^a is preferably a structure represented by the above formulas (X ^a -1) and (X ^a -2).

In the above formula (4), examples of the organic group represented by R ^a13 include, for example, a linear or branched hydrocarbon group having 1 to 30 carbon atoms, an alicyclic hydrocarbon group having 3 to 30 carbon atoms, and 6 carbon atoms. To 30 aromatic hydrocarbon groups, or a combination of these groups and one or more groups selected from the group consisting of oxygen, sulfur, ether, ester, carbonyl, imino and amide groups Is mentioned.

  Examples of the structural unit (a5) include structural units represented by the following formulas (4-1) and (4-2).

In the above formula (4-1), R ^a12 is a divalent linear, branched or cyclic saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms. R ^a11 , X ^a and R ^a13 are as defined in the above formula (4).
In the formula ^{(4-2), R a11, X} a, R a13 and k are as defined in the above formula (4). However, when k is 2 or 3, the plurality of X ^a and R ^a13 may be the same or different.

  Examples of the structural unit represented by the above formula (4-1) and formula (4-2) include the following formula (4-1-1), formula (4-1-2), and formula (4-2-1). The structural unit shown by these is mentioned.

In the formulas (4-1-1), (4-1-2), and (4-2-1), R ^a11 has the same ^{meaning as} the formula (4).

  (A5) Examples of monomers that give structural units include (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-3-propyl) ester and (meth) acrylic acid. (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-butyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy -5-pentyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester, (meth) acrylic acid 2-{[5- ( 1 ′, 1 ′, 1′-trifluoro-2′-trifluoromethyl-2′-hydroxy) propyl] bicyclo [2.2.1] heptyl} ester and the like.

  In the [A] polymer, the content of the (a5) structural unit is preferably 10% by mole to 60% by mole, and preferably 20% by mole to 40% by mole with respect to all the structural units constituting the [A] polymer. More preferred. In addition, the [A] polymer may have 1 type or 2 types or more of (a5) structural units.

  In the [A] polymer, the content of the other structural units is usually 95 mol% or less, preferably 90 mol% or less, and preferably 85 mol%, based on all structural units constituting the [A] polymer. The following is more preferable.

[A] The fluorine atom content in the polymer is preferably lower than that of the polymer [C] described later. In the radiation sensitive resin composition of the present invention, the [A] polymer is preferably used as the base resin. In that case, the effects of the present invention such as improvement of lithography performance such as pattern formability and MEEF performance and etching resistance are achieved. You can get enough. [A] The content ratio of fluorine atoms in the polymer is usually 50% by mass or less, preferably 30% by mass or less, more preferably 10% by mass or less, based on the total amount of the polymer [A] 100% by mass. It is. In addition, this fluorine atom content rate can be measured by ¹³ C-NMR. Moreover, in order to fully demonstrate the said effect, it is preferable that the difference of the content rate of the fluorine atom in a [A] polymer and the content rate of the fluorine atom in a [C] polymer is 1 mass% or more. More preferably, it is 3 mass% or more.

  [A] The polymer can also be used as a water-repellent resin. In that case, the content ratio of the fluorine atom in the [A] polymer is usually 5% by mass or more, preferably 5% by mass to 50% by mass, with the total amount of the [A] polymer being 100% by mass, more preferably Preferably it is 5 mass%-45 mass%. [A] When the polymer is also used as a water-repellent resin, a polymer serving as a base resin may be added. [A] When the polymer is also used as a water repellent resin, the water repellency of the formed photoresist film surface can be increased, and it can be suitably used in a pattern forming step by an immersion exposure method.

<[A] Polymer Synthesis Method>
[A] The polymer can be synthesized according to a conventional method such as radical polymerization. For example,
A method in which a solution containing a monomer and a radical initiator is dropped into a reaction solvent or a solution containing a monomer to cause a polymerization reaction;
A method in which a solution containing a monomer and a solution containing a radical initiator are separately dropped into a reaction solvent or a solution containing a monomer to cause a polymerization reaction;
A plurality of types of solutions containing each monomer and a solution containing a radical initiator are separately added to a reaction solvent or a solution containing a monomer and synthesized by a method such as a polymerization reaction. It is preferable. In addition, when the monomer solution is dropped and reacted with respect to the monomer solution, the monomer amount in the dropped monomer solution is 30 mol with respect to the total amount of monomers used for polymerization. % Or more is preferable, 50 mol% or more is more preferable, and 70 mol% or more is particularly preferable.

  What is necessary is just to determine the reaction temperature in these methods suitably with initiator seed | species. Usually, it is 30 to 180 ° C, preferably 40 to 160 ° C, and more preferably 50 to 140 ° C. The dropping time varies depending on the reaction temperature, the type of initiator, the monomer to be reacted, etc., but is usually 30 minutes to 8 hours, preferably 45 minutes to 6 hours, and more preferably 1 hour to 5 hours. . Further, the total reaction time including the dropping time varies depending on the conditions similarly to the dropping time, but is usually 30 minutes to 8 hours, preferably 45 minutes to 7 hours, and more preferably 1 hour to 6 hours.

  Examples of the radical initiator used in the polymerization include azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2 -Cyclopropylpropionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile) and the like. These initiators can be used alone or in admixture of two or more.

Examples of the solvent used for the polymerization include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2-pentanol;
Ketones such as acetone, 2-butanone, 4-methyl-2-pentanone, 2-heptanone;
Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate and methyl propionate;
alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, 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;
Ethers such as tetrahydrofuran, dimethoxyethanes, diethoxyethanes;
Etc. These solvents may be used alone or in combination of two or more.

  The resin obtained by the polymerization reaction is preferably recovered by a reprecipitation method. That is, after completion of the polymerization reaction, the target resin is recovered as a powder by introducing the polymerization solution into a reprecipitation solvent. As the reprecipitation solvent, alcohols or alkanes can be used alone or in admixture of two or more. In addition to the reprecipitation method, the resin can be recovered by removing low-molecular components such as monomers and oligomers by a liquid separation operation, a column operation, an ultrafiltration operation, or the like.

  [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 500,000 or less, more preferably 2,000 or more and 400,000 or less. Preferably, it is 3,000 or more and 300,000 or less. In addition, when the Mw of the [A] polymer is less than 1,000, the heat resistance when used as a resist tends to decrease. On the other hand, when the Mw of the [A] polymer exceeds 500,000, the developability when used as a resist tends to be lowered.

  [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, preferably from 1 to 2. More preferred. By setting Mw / Mn in such a range, the photoresist film has excellent resolution performance.

  Mw and Mn in this specification are GPC columns (Tosoh Corporation, 2 G2000HXL, 1 G3000HXL, 1 G4000HXL), with a flow rate of 1.0 mL / min, elution solvent tetrahydrofuran, and column temperature of 40 ° C. under analysis conditions. The value measured by GPC using monodisperse polystyrene as a standard.

<[B] Acid generator>
[B] The acid generator generates an acid upon exposure, and the acid dissociable groups present in the [A] polymer are dissociated by the acid. As a result, the exposed portion becomes soluble in the developer. The content form of the [B] acid generator in the radiation sensitive resin composition is incorporated as part of the polymer even in the form of a compound as described later (hereinafter also referred to as “[B] acid generator”). Both forms may be used.

  [B] Examples of the acid generator include onium salt compounds such as sulfonium salts and iodonium salts, organic halogen compounds, and sulfone compounds such as disulfones and diazomethane sulfones. Among these, preferable specific examples of the [B] acid generator include, for example, compounds described in paragraphs [0080] to [0113] of JP-A-2009-134088.

  [B] Specific examples of the acid generator include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, and bis (4-t-butylphenyl) iodonium. Trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, bis (4-t-butylphenyl) iodonium perfluoro-n-octanesulfonate, triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium Nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, cyclohexyl 2-oxocyclohexyl Le methyl trifluoromethanesulfonate, dicyclohexyl-2-oxo-cyclohexyl trifluoromethane sulfonate, 2-oxo-cyclohexyl dimethyl sulfonium trifluoromethane sulfonate, 4-hydroxy-1-naphthyl dimethyl sulfonium trifluoromethane sulfonate,

  4-hydroxy-1-naphthyltetrahydrothiophenium trifluoromethanesulfonate, 4-hydroxy-1-naphthyltetrahydrothiophenium nonafluoro-n-butanesulfonate, 4-hydroxy-1-naphthyltetrahydrothiophenium perfluoro-n- Octanesulfonate, 1- (1-naphthylacetomethyl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (1-naphthylacetomethyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (1-naphthylacetomethyl) Tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium trifluoromethanesulfonate, 1- 3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium nonafluoro -n- butane sulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium perfluoro -n- octane sulfonate,

  Trifluoromethanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide, nonafluoro-n-butanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide , Perfluoro-n-octanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide, N-hydroxysuccinimide trifluoromethanesulfonate, N-hydroxysuccinimide nonafluoro-n- Butanesulfonate, N-hydroxysuccinimide perfluoro-n-octanesulfonate, and 1,8-naphthalenedicarboxylic acid imide trifluoromethanesulfonate are preferred.

  These [B] acid generators may be used alone or in combination of two or more. [B] The amount of the acid generator used is usually 0.1 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the polymer [A] from the viewpoint of ensuring sensitivity and developability as a resist. Preferably they are 0.5 mass part or more and 15 mass parts or less. In this case, if the amount of the [B] acid generator used is less than 0.1 parts by mass, the sensitivity and developability tend to decrease. On the other hand, if it exceeds 15 parts by mass, the transparency to radiation decreases, and the desired There is a risk that it may be difficult to obtain a resist pattern.

<[C] polymer>
The said radiation sensitive resin composition can further contain the polymer whose fluorine atom content rate is higher than a [C] [A] polymer as a suitable component. When the radiation-sensitive composition contains a [C] polymer, the hydrophobicity of the resist film is improved, and even when immersion exposure is performed, the substance elution suppression is excellent, and the resist film and the immersion liquid The receding contact angle can be sufficiently high, and when the scan exposure is performed at a high speed, water droplets do not remain, and the usefulness of the radiation-sensitive composition for immersion exposure is enhanced.

[C] As an aspect of the polymer, for example, a structure in which a fluorinated alkyl group is bonded to the main chain;
A structure in which a fluorinated alkyl group is bonded to the side chain;
Examples include a structure in which a fluorinated alkyl group is bonded to the main chain and the side chain.

  As a monomer that gives a structure in which a fluorinated alkyl group is bonded to the main chain, for example, an α-trifluoromethyl acrylate compound, a β-trifluoromethyl acrylate compound, an α, β-trifluoromethyl acrylate compound, one or more types Examples thereof include compounds in which the hydrogen at the vinyl moiety is substituted with a fluorinated alkyl group such as a trifluoromethyl group.

  Monomers that give a structure in which a fluorinated alkyl group is bonded to the side chain include, for example, those in which the side chain of an alicyclic olefin compound such as norbornene is a fluorinated alkyl group or a derivative thereof, acrylic acid or methacrylic acid side Examples thereof include ester compounds in which the chain is a fluorinated alkyl group or a derivative thereof, and one or more olefin side chains (sites not including a double bond) being a fluorinated alkyl group or a derivative thereof.

  Examples of the monomer that gives a structure in which a fluorinated alkyl group is bonded to the main chain and the side chain include α-trifluoromethylacrylic acid, β-trifluoromethylacrylic acid, α, β-trifluoromethylacrylic acid, and the like. Is a fluorinated alkyl group or its derivative ester compound. One or more vinyl moiety hydrogens are substituted with a fluorinated alkyl group such as a trifluoromethyl group. The hydrogen bonded to the double bond of one or more alicyclic olefin compounds is replaced with a fluorinated alkyl group such as a trifluoromethyl group, and the side chain is a fluorinated alkyl group or a derivative thereof. And the like. In addition, an alicyclic olefin compound shows the compound in which a part of ring is a double bond.

  [C] The polymer preferably has (c1) structural unit and / or (c2) structural unit having a fluorine atom, and has (c3) structural unit, lactone structure or cyclic carbonate structure having an acid dissociable group. (C4) You may have other structural units, such as a structural unit.

  Examples of the structural unit (c1) include the same structural units as those cited as the structural unit (a4) in the [A] polymer. Examples of the structural unit (c2) include the same structural units as those exemplified as the structural unit (a5) in the [A] polymer. Moreover, as the structural unit (c3), the same structural units as those exemplified as the structural unit (a1) in the [A] polymer can be exemplified. Examples of the structural unit (c4) include the same structural units as those exemplified as the structural unit (a3) in the [A] polymer.

  In the [C] polymer, the content ratio of the (c1) structural unit is preferably 5 mol% to 80 mol% with respect to all the structural units constituting the [C] polymer, and is 10 mol% to 80 mol%. Is more preferable, and 20 mol% to 70 mol% is particularly preferable. (C1) When the content ratio of the structural unit exceeds 80 mol%, the adhesiveness of the resist film is lowered, and pattern collapse or pattern peeling may occur. In addition, the [C] polymer may have 1 type or 2 types or more of (c1) structural units.

  In the [C] polymer, the content ratio of the (c2) structural unit is preferably 20 mol% to 90 mol%, preferably 30 mol% to 85 mol%, based on all structural units constituting the [C] polymer. Is more preferable. In addition, the [C] polymer may have 1 type (s) or 2 or more types of (c2) structural units.

  In the [C] polymer, the content ratio of the (c3) structural unit is preferably 5 mol% to 40 mol% with respect to all the structural units constituting the [C] polymer, and is 10 mol% to 30 mol%. Is more preferable.

  In the [C] polymer, the content ratio of the (c4) structural unit is preferably 0 mol% to 70 mol%, preferably 10 mol% to 40 mol%, based on all structural units constituting the [C] polymer. Is more preferable. By setting it as such a content rate, the adhesiveness of a resist and a board | substrate can be improved. On the other hand, when it exceeds 70 mol%, a good pattern may not be obtained.

<[C] Polymer Synthesis Method>
[C] The polymer can be produced, for example, by polymerizing a monomer corresponding to each predetermined structural unit in a suitable solvent using a radical polymerization initiator.

  Examples of the radical polymerization initiator and solvent used for the polymerization include the same solvents as those mentioned in the method for synthesizing [A] polymer.

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

  [C] The Mw of the polymer by the GPC method is preferably 1,000 to 100,000, more preferably 1,000 to 50,000, and particularly preferably 1,000 to 30,000. [C] By making Mw of a polymer into the said range, the said radiation sensitive resin composition containing this is excellent in lithography performance.

  [C] The ratio (Mw / Mn) between Mw and Mn of the polymer is usually 1 to 3, preferably 1 to 2.

<[D] Nitrogen-containing compound>
The radiation sensitive resin composition preferably further contains a [D] nitrogen-containing compound. [D] The nitrogen-containing compound controls the diffusion phenomenon of the acid generated from the [B] acid generator upon exposure in the resist film, and suppresses an undesirable chemical reaction in the non-exposed region, and has a resolution as a resist. While improving further, the storage stability of the obtained radiation sensitive resin composition improves. [D] The inclusion form of the nitrogen-containing compound in the radiation-sensitive resin composition may be a free compound form, a form incorporated as part of a polymer, or both forms.

  [D] The nitrogen-containing compound is represented by the following formula, for example.

In the above formula, R ^{d1 to} R ^d5 are each independently a hydrogen atom, or a linear, branched, or cyclic C 1-20 alkyl group, aryl group, or aralkyl group. However, these groups may have a substituent. In addition, R ^d1 and R ^d2 are bonded to each other with a nitrogen atom to which R ^d1 and R ^d2 are bonded and / or R ^d3 and R ^d4 are bonded to each other with a carbon atom to which R ^d3 and R ^d4 are bonded. Alternatively, an unsaturated hydrocarbon group or a derivative thereof may be formed.

  Examples of the [D] nitrogen-containing compound represented by the above formula include Nt-butoxycarbonyldi-n-octylamine, Nt-amyloxycarbonyldi-n-octylamine, and Nt-butoxycarbonyldi- -N-nonylamine, Nt-amyloxycarbonyldi-n-nonylamine, Nt-butoxycarbonyldi-n-decylamine, Nt-amyloxycarbonyldi-n-decylamine, Nt-butoxycarbonyldicyclohexyl Amine, Nt-amyloxycarbonyldicyclohexylamine, Nt-butoxycarbonyl-1-adamantylamine, Nt-amyloxycarbonyl-1-adamantylamine, Nt-butoxycarbonyl-2-adamantylamine, N -T-amyloxycarbonyl-2-adamantylamine, N- -Butoxycarbonyl-N-methyl-1-adamantylamine, Nt-amyloxycarbonyl-N-methyl-1-adamantylamine, (S)-(-)-1- (t-butoxycarbonyl) -2-pyrrolidine Methanol, (S)-(−)-1- (t-amyloxycarbonyl) -2-pyrrolidinemethanol, (R)-(+)-1- (t-butoxycarbonyl) -2-pyrrolidinemethanol, (R) -(+)-1- (t-amyloxycarbonyl) -2-pyrrolidinemethanol, Nt-butoxycarbonyl-4-hydroxypiperidine, Nt-amyloxycarbonyl-4-hydroxypiperidine, Nt-butoxy Carbonylpyrrolidine, Nt-amyloxycarbonylpyrrolidine, N, N′-di-t-butoxycarbonylpiperazine, N, '-Di-t-amyloxycarbonylpiperazine, N, N-di-t-butoxycarbonyl-1-adamantylamine, N, N-di-t-amyloxycarbonyl-1-adamantylamine, Nt-butoxycarbonyl -4,4'-diaminodiphenylmethane, Nt-amyloxycarbonyl-4,4'-diaminodiphenylmethane, N, N'-di-t-butoxycarbonylhexamethylenediamine, N, N'-di-t-ami Roxycarbonylhexamethylenediamine, N, N, N ′, N′-tetra-t-butoxycarbonylhexamethylenediamine, N, N, N ′, N′-tetra-t-amyloxycarbonylhexamethylenediamine, N, N '-Di-t-butoxycarbonyl-1,7-diaminoheptane, N, N'-di-t-amyloxycarbo Nyl-1,7-diaminoheptane, N, N′-di-t-butoxycarbonyl-1,8-diaminooctane, N, N′-di-t-amyloxycarbonyl-1,8-diaminooctane, N, N′-di-t-butoxycarbonyl-1,9-diaminononane, N, N′-di-t-amyloxycarbonyl-1,9-diaminononane, N, N′-di-t-butoxycarbonyl-1,10 -Diaminodecane, N, N'-di-t-amyloxycarbonyl-1,10-diaminodecane, N, N'-di-t-butoxycarbonyl-1,12-diaminododecane, N, N'-di- t-amyloxycarbonyl-1,12-diaminododecane, N, N′-di-t-butoxycarbonyl-4,4′-diaminodiphenylmethane, N, N′-di-t-amyloxycarbonyl- , 4′-diaminodiphenylmethane, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonylbenzimidazole, Nt-amyloxycarbonyl-2-methylbenzimidazole, Nt-butoxycarbonyl-2-phenylbenz Examples thereof include Nt-alkylalkoxycarbonyl group-containing amino compounds such as imidazole and Nt-amyloxycarbonyl-2-phenylbenzimidazole.

  In addition to the nitrogen-containing compound represented by the above formula, examples of the nitrogen-containing compound include a tertiary amine compound, a quaternary ammonium hydroxide compound, a photodegradable base compound, and other nitrogen-containing heterocyclic compounds. It is done.

Examples of tertiary amine compounds include triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine. , Tri (cyclo) alkylamines such as cyclohexyldimethylamine, dicyclohexylmethylamine, and tricyclohexylamine;
Fragrances such as aniline, N-methylaniline, N, N-dimethylaniline, 2-methylaniline, 3-methylaniline, 4-methylaniline, 4-nitroaniline, 2,6-dimethylaniline, 2,6-diisopropylaniline Group amines;
Alkanolamines such as triethanolamine and N, N-di (hydroxyethyl) aniline;
N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, 1,3-bis [1- (4-aminophenyl) -1- Methylethyl] benzenetetramethylenediamine, bis (2-dimethylaminoethyl) ether, bis (2-diethylaminoethyl) ether and the like.

  Examples of the quaternary ammonium hydroxide compound include tetra-n-propylammonium hydroxide and tetra-n-butylammonium hydroxide.

  [D] As a content rate of a nitrogen-containing compound, 10 mass parts or less are preferable with respect to 100 mass parts of [B] polymers, and 8 mass parts or less are more preferable. When the amount used exceeds 10 parts by mass, the sensitivity as a resist tends to decrease.

<[E] solvent>
The radiation-sensitive resin composition usually contains an [E] solvent. [E] Examples of the solvent include alcohol solvents, ketone solvents, amide solvents, ether solvents, ester solvents, and mixed solvents thereof.

Examples of alcohol solvents include 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 -Monoalcohol solvents such as heptadecyl alcohol, furfuryl alcohol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, 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.

  Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, methyl-n-pentyl ketone, ethyl-n-butyl ketone, methyl-n- Ketones such as hexyl ketone, di-iso-butyl ketone, trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, diacetone alcohol, acetophenone A solvent is mentioned.

  Examples of the amide solvents include N, N′-dimethylimidazolidinone, N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropionamide, N-methylpyrrolidone and the like can be mentioned.

  Examples of the ester solvents include diethyl carbonate, propylene carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, γ-valerolactone, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec sec -Butyl, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, n-nonyl acetate, acetoacetic acid Methyl, ethyl acetoacetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol acetate Cole mono-n-butyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, diacetic acid Glycol, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate , Diethyl malonate, dimethyl phthalate, diethyl phthalate and the like.

Examples of other solvents include n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, 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 halogen-containing solvents such as dichloromethane, chloroform, chlorofluorocarbon, chlorobenzene, and dichlorobenzene.

  Of these solvents, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, ethyl lactate, γ-butyrolactone, and cyclohexanone are preferable.

<Other optional components>
The said radiation sensitive resin composition can contain a [F] uneven distribution promoter, an alicyclic skeleton compound, surfactant, a sensitizer, etc. in the range which does not impair the effect of this invention. Hereinafter, these other optional components will be described in detail. These other optional components can be used alone or in admixture of two or more. Moreover, the compounding quantity of another arbitrary component can be suitably determined according to the objective.

[[F] uneven distribution promoter]
The radiation-sensitive resin composition can be blended with an [F] uneven distribution accelerator when a resist pattern is formed using an immersion exposure method. By blending [F] an uneven distribution promoter, the [C] polymer can be further unevenly distributed in the vicinity of the surface layer. [F] Examples of the uneven distribution promoter include γ-butyrolactone and propylene carbonate.

[Alicyclic skeleton compound]
An alicyclic skeleton compound is a component that exhibits an action of further improving dry etching resistance, pattern shape, adhesion to a substrate, and the like. Examples of the alicyclic skeleton compound include adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and 1-adamantanecarboxylic acid t-butyl; deoxycholic acid t-butyl, deoxycholic acid t-butoxycarbonylmethyl, Deoxycholic acid esters such as 2-ethoxyethyl deoxycholic acid; Lithocholic acid esters such as tert-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.

[Surfactant]
Surfactants are components that 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. In addition to nonionic surfactants such as stearate, the following trade names are 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, Dainippon Ink and Chemicals), Florard FC430, FC431 ( Sumitomo 3M), Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, Asahi Glass Co., Ltd.) ) And the like.

[Sensitizer]
The sensitizer absorbs the energy of radiation and transmits the energy to the compound [A], thereby increasing the amount of acid produced. The “sensitivity of the radiation-sensitive resin composition” It has the effect of improving “sensitivity”. Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines and the like.

<Preparation of radiation-sensitive composition>
The radiation-sensitive resin composition is, for example, the above-mentioned [A] polymer and [B] acid generator, [C] polymer which is a suitable component in the above-mentioned [E] solvent, and other added as necessary. It can be prepared by mixing arbitrary components at a predetermined ratio. The radiation-sensitive resin composition is usually dissolved in an [E] solvent so that the total solid content concentration is 1% by mass to 50% by mass, preferably 2% by mass to 25% by mass, in use. For example, it is prepared by filtering with a filter having a pore size of about 0.2 μm.

<Method for forming resist pattern>
The pattern forming method of the present invention comprises:
A resist film forming step (hereinafter also referred to as “(i) step”) in which the radiation-sensitive resin composition is applied onto a substrate to form a resist film;
An exposure step of irradiating at least a part of the resist film (hereinafter also referred to as “(ii) step”) and a development step of developing the exposed resist film (hereinafter referred to as “(iii) step”) Say)
including. Hereinafter, each process is explained in full detail.

[(I) Step]
In this step, the radiation-sensitive resin composition or a composition solution obtained by dissolving this in a solvent is applied to silicon wafer, silicon dioxide, lower layer antireflection by coating means such as spin coating, cast coating, roll coating, etc. A resist film is formed by applying a predetermined film thickness on a substrate such as a wafer covered with a film, and then pre-baking to volatilize the solvent in the coating film. The lower antireflection film can be formed on the substrate surface using, for example, a lower antireflection film forming agent.

[Step (ii)]
In this step, the resist film formed in the step (i) is exposed by irradiation with radiation (in some cases, through an immersion medium such as water). At this time, radiation is irradiated through a mask having a predetermined pattern. As the radiation, irradiation is performed by appropriately selecting from visible light, ultraviolet light, far ultraviolet light, X-rays, charged particle beams and the like according to the line width of the target pattern. Far ultraviolet rays represented by ArF excimer laser (wavelength 193 nm) and KrF excimer laser (wavelength 248 nm) are preferable, and ArF excimer laser is more preferable. Next, the exposed photoresist film is subjected to post-exposure baking (PEB), so that the polymer generated from the [B] acid generator in the exposed portion of the resist film is deprotected. PEB is normally selected and carried out in the range of 50 ° C to 180 ° C.

[(Iii) Step]
In this step, a predetermined photoresist pattern is formed by developing the exposed resist film with a developer. After development, it is common to wash with water and dry. As the developer, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyl Dimethylamine, triethanolamine, tetramethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo- [4.3.0] An aqueous alkaline solution in which at least one alkaline compound such as -5-nonene is dissolved is preferable.

  When performing immersion exposure, before the step (ii), in order to protect the direct contact between the immersion liquid and the resist film, an immersion liquid insoluble immersion protective film is formed on the resist film. It may be provided. Examples of the immersion protective film include a solvent peeling type protective film that is peeled off by a solvent before the step (iii) (see, for example, JP-A-2006-227632), and (ii) a developer peeling that peels off simultaneously with the development in the step. Any of the mold protective films (for example, refer to WO2005-069096 and WO2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer peeling type immersion protective film.

  Since the resist pattern obtained in this way is excellent in pattern shape, the pattern forming method of the present invention is suitable for fine processing using a lithography technique.

<Polymer>
The polymer of the present invention has the structural unit (I) represented by the above formula (1). The polymer has an appropriate polarity by having the specific structure containing a cyclic sulfonyl structure, and when used as a component of the radiation-sensitive resin composition, the compatibility with other components is improved. The pattern formability, MEEF performance, etc. of the radiation sensitive resin composition can be improved. Moreover, the etching tolerance of a radiation sensitive resin composition can also be improved because the said polymer has a sulfur atom. Furthermore, in the structural unit (I), since the carbon bonded to the ester group is a tertiary carbon, the cyclic sulfonyl structure portion is easily dissociated by an acid. Therefore, the radiation-sensitive resin composition containing the polymer can change the solubility in the developer due to the action of the acid generated from the acid generator in the exposed portion, and the contrast between the exposed portion and the unexposed portion can be changed. And a good pattern can be formed.
In addition, about the said polymer, since it has already demonstrated in detail as [A] polymer which a radiation sensitive resin composition contains, description here is abbreviate | omitted.

<Compound>
The compound of the present invention is represented by the above formula (i). By having the specific structure, the compound can be suitably used as a monomer for incorporating the structural unit (I) into the polymer. The compound can be easily synthesized from a heterocyclic compound containing a sulfur atom as a ring constituent atom.
The compound has already been described in detail as the monomer compound that gives the structural unit (I) of the [A] polymer contained in the radiation-sensitive resin composition. Is omitted.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Mw and Mn of the polymer were measured under the following conditions using GPC columns (Tosoh Corporation, 2 G2000HXL, 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 mass%
Sample injection volume: 100 μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene

¹ H-NMR analysis and ¹³ C-NMR analysis were measured using a nuclear magnetic resonance apparatus (JEOL Ltd., JNM-EX270).

<Synthesis of compounds>
[Example 1] Synthesis of (M-1) In a 1 L reactor equipped with a stirrer and a dropping funnel, 26.8 g (200 mmol) of dihydro-3 (2H) -thiophenone 1,1-dioxide and 200 mL of diethyl ether were added. First, 100 mL (200 mmol) of a 2M solution of methylmagnesium bromide in diethyl ether was added dropwise from a dropping funnel under nitrogen, and the mixture was reacted at 20 ° C. with stirring for 16 hours. After the reaction, while cooling the inside of the reactor to 0 ° C., a mixture of 24.5 g (242 mmol) of triethylamine and 25.3 g (242 mmol) of methacryloyl chloride was dropped from the dropping funnel, and then reacted at 20 ° C. with stirring for 2 hours. I let you. The obtained suspension was filtered under reduced pressure, the filtrate was concentrated under reduced pressure, and the resulting residue was purified by silica gel column chromatography (eluent: hexane / ethyl acetate = 50/1) to give the following formula (M -1) 17.9g of compound (yield 41%) was obtained.

¹ H-NMR data is shown below.
¹ H-NMR (CDCl ₃ ) δ: 1.37 (s, 3H), 1.89 (s, 3H), 2.16-2.23 (m, 2H), 2.43-2.77 (m 2H), 3.08-3.22 (m, 2H), 5.46 (s, 1H), 6.00 (s, 1H, CH)

Example 2 Synthesis of (M-2) In Example 1, instead of 26.8 g of dihydro-3 (2H) -thiophenone 1,1-dioxide as a starting material, 1,1-dioxotetrahydrothiopyran Except for using 29.6 g of -4-one, 21.4 g of a compound represented by the following formula (M-2) was obtained in the same manner as in Example 1 (total yield 46%).

¹ H-NMR data is shown below.
¹ H-NMR (CDCl ₃ ) δ: 0.91 (t, 3H), 1.50-1.71 (m, 2H), 1.90 (s, 3H), 1.96-2.01 (m 2H), 2.11-2.21 (m, 2H), 2.78-2.97 (m, 2H), 3.11-3.31 (m, 2H), 5.46 (s, 1H) ), 6.00 (s, 1H, CH)

[Example 3] Synthesis of (M-3) In Example 1, 100 mL of ethylmagnesium bromide in diethyl ether 2M was used instead of 100 mL of methylmagnesium bromide in diethyl ether 2M as a starting material. In the same manner as in Example 1, 19.5 g of a compound represented by the following formula (M-3) was obtained (total yield 42%).

¹ H-NMR data is shown below.
¹ H-NMR (CDCl ₃ ) δ: 0.89 (t, 3H), 1.49-1.68 (m, 2H), 1.91 (s, 3H), 2.14-2.28 (m) 2H), 2.45-2.72 (m, 2H), 3.01-3.20 (m, 2H), 5.43 (s, 1H), 6.01 (s, 1H, CH)

Example 4 Synthesis of (M-4) In Example 1, 1,1-dioxotetrahydrothiopyran instead of 26.8 g of dihydro-3 (2H) -thiophenone 1,1-dioxide as starting material In the same manner as in Example 1, except that 29.6 g of -4-one was used and 100 mL of a 2M solution of ethyl magnesium bromide in diethyl ether was used instead of 100 mL of a 2M solution of methyl magnesium bromide in diethyl ether, the following formula 20.2 g of a compound represented by (M-4) was obtained (total yield 41%).

¹ H-NMR data is shown below.
¹ H-NMR (CDCl ₃ ) δ: 0.88 (t, 3H), 1.48-1.68 (m, 2H), 1.49-1.70 (m, 2H), 1.88 (s) 3H), 1.92-2.00 (m, 2H), 2.12-2.38 (m, 2H), 2.76-2.92 (m, 2H), 3.12-3.34 (M, 2H), 5.48 (s, 1H), 6.03 (s, 1H, CH)

Example 5 Synthesis of (M-5) In Example 1, 100 mL of isopropylmagnesium bromide in diethyl ether 2M was used instead of 100 mL of methylmagnesium bromide in diethyl ether 2M as a starting material. In the same manner as in Example 1, 17.7 g of a compound represented by the following formula (M-5) was obtained (total yield: 36%).

¹ H-NMR data is shown below.
¹ H-NMR (CDCl ₃ ) δ: 0.88-0.94 (m, 6H), 1.50-1.67 (m, 2H), 1.90 (s, 3H), 2.12-2 .34 (m, 2H), 2.37-2.75 (m, 3H), 2.99-3.21 (m, 2H), 5.44 (s, 1H), 6.02 (s, 1H) , CH)

Example 6 Synthesis of (M-6) In Example 1, 1,1-dioxotetrahydrothiopyran instead of 26.8 g of dihydro-3 (2H) -thiophenone 1,1-dioxide as starting material In the same manner as in Example 1, except that 29.6 g of -4-one was used and 100 mL of 2M solution of isopropylmagnesium bromide in diethyl ether was used instead of 100 mL of 2M solution of methylmagnesium bromide in diethyl ether, the following formula 18.7 g of a compound represented by (M-6) was obtained (total yield 36%).

¹ H-NMR data is shown below.
¹ H-NMR (CDCl ₃ ) δ: 0.88-0.93 (m, 6H), 1.47-1.69 (m, 2H), 1.42-1.75 (m, 2H), 1 .85 (s, 3H), 1.88-2.10 (m, 2H), 2.12-2.58 (m, 3H), 2.76-2.92 (m, 2H), 3.12 -3.34 (m, 2H), 5.48 (s, 1H), 6.03 (s, 1H, CH)

[Example 7] Synthesis of (M-7) In Example 1, instead of 26.8 g of dihydro-3 (2H) -thiophenone 1,1-dioxide as a starting material, 2-methyl-3-oxotetrahydrothiophene 21.4 g of a compound represented by the following formula (M-7) was obtained in the same manner as in Example 1 except that 29.6 g of 5,5-dioxide was used (total yield 46%).

¹ H-NMR data is shown below.
¹ H-NMR (CDCl ₃ ) δ: 0.88 (t, 3H), 1.32-1.71 (m, 5H), 1.90 (s, 3H), 2.11-2.31 (m 2H), 2.41-2.70 (m, 2H), 3.25-3.42 (m, 1H), 5.44 (s, 1H), 6.03 (s, 1H, CH)

<[A] Synthesis of polymer>
Monomers used for the synthesis of the [A] polymer and the [C] polymer described below are the above formulas (M-1) to (M-7) and the following formulas (M-8) to (M-14). Indicated.
[Example 8]
Compound (M-1) 19.2 g (20 mol%), Compound (M-10) 30.9 g (30 mol%), Compound (M-11) 10.9 g (10 mol%), Compound (M-12) ) 39.0 g (40 mol%) was dissolved in 200 g of 2-butanone, and 3.61 g of AIBN was added to prepare a monomer solution. A 1,000 mL three-necked flask containing 100 g of 2-butanone was purged with nitrogen for 30 minutes, 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 cooled polymerization solution was put into 2,000 g of methanol, and the precipitated white powder was filtered off. The filtered white powder was washed twice with 400 g of methanol, filtered, and dried at 50 ° C. for 17 hours to obtain a white powdery polymer (A-1) (81.6 g, yield 82). %). Mw of the obtained polymer (A-1) was 5,000, and Mw / Mn was 1.38. As a result of ¹³ C-NMR analysis, the structural unit derived from the compound (M-1): the structural unit derived from the compound (M-1): the structural unit derived from the compound (M-1): derived from the compound (M-1) The content ratio of the structural units was 17.3: 30.8: 10.6: 41.3 (mol%).

[Examples 9-18, Comparative Examples 1-2]
The polymers (A-2) to (A-8) and (a-1) to (a-2) were operated in the same manner as in Example 8 except that a predetermined amount of the monomers listed in Table 1 were blended. Got. In addition, Table 1 shows the Mw, Mw / Mn, yield (%), and the content of the structural unit derived from each monomer in each polymer.

<Synthesis of [C] polymer>
[Synthesis Example 1]
Compound (M-9) 17.4 g (20 mol%) and compound (M-16) 83.6 g (80 mol%) were dissolved in 100 g of 2-butanone, and AIBN 3.43 g was added to the monomer solution. Was prepared. A 1000 mL three-necked flask containing 100 g of 2-butanone was purged with nitrogen for 30 minutes, 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 was concentrated under reduced pressure using an evaporator until the weight of the polymerization solution reached 150 g. Thereafter, the concentrated solution was poured into a mixed solution of 760 g of methanol and 40 g of water to precipitate a slime-like white solid. The liquid part was removed by decantation, and the recovered solid was vacuum-dried at 60 ° C. for 15 hours to obtain 61.3 g of polymer (C-1) as a white powder (yield 61%). Mw was 3,500 and Mw / Mn was 1.66. As a result of ¹³ C-NMR analysis, the content ratio of the structural unit derived from the compound (M-9): the structural unit derived from the compound (M-16) was 19.6: 80.4 (mol%).

[Synthesis Example 2]
A polymer (C-2), which is a white powder, was obtained in the same manner as in Synthesis Example 1 except that 80 mol% of the compound (M-17) was used instead of the compound (M-16). Mw was 3,500 and Mw / Mn was 1.63. As a result of ¹³ C-NMR analysis, the content ratio of the structural unit derived from the compound (M-9) to the structural unit derived from the compound (M-17) was 20.3: 79.7 (mol%).

<Preparation of radiation-sensitive resin composition>
The [B] acid generator, acid diffusion controller and solvent used in the preparation of the radiation sensitive resin composition are as follows.

<[B] Acid generator>
Compound represented by the following formula (B-1)

<Acid diffusion control agent>
A compound represented by the following formula (D-1).

<Solvent>
Hereinafter, the solvents used in Examples and Comparative Examples are shown.
(E-1) Acetic acid propylene glycol monomethyl ether (E-2) Cyclohexanone (E-3) γ-butyrolactone

[Example 19]
100 parts by mass of the polymer (A-1) obtained in Example 8, 5 parts by mass of the polymer (C-1) obtained in Synthesis Example 1, 9.9 parts by mass of the acid generator (B-1), 1.2 parts by mass of the acid diffusion controller (D-1), 2,590 parts by mass of the solvent (E-1), 1,110 parts by mass of (E-2), and 200 parts by mass of (E-3) were mixed. The obtained mixed solution was filtered through a filter having a pore size of 0.20 μm to prepare a radiation sensitive resin composition.

[Examples 20 to 31, Comparative Examples 3 to 4]
About the [A] component, the [B] acid generator, and the [C] polymer, except having set it as the mixing | blending prescription shown in Table 2, operation similar to Example 16 was performed and each radiation sensitive resin composition was prepared. .

<Evaluation>
The following evaluation results are shown in Table 2.

[Formation of resist pattern]
Each of the above-mentioned radiation-sensitive resin compositions was applied onto a 12-inch silicon wafer on which a lower antireflection film (ARC66, manufactured by Nissan Chemical Industries) was formed, and pre-baked (PB) at 100 degrees for 60 seconds, A coating film was formed. Next, this coating film was exposed through a mask pattern using an ArF excimer laser immersion exposure apparatus (NSR S610C, manufactured by NIKON) under the conditions of NA = 1.3, ratio = 0.800, and annular. After exposure, PEB was performed at 95 ° C. for 60 seconds. Thereafter, the resist film was developed with a 2.38 mass% tetramethylammonium hydroxide aqueous solution, washed with water, and dried to form a positive resist pattern.

  Various physical properties of the resist pattern formed as described above were evaluated as follows.

[Pattern formability]
Using a radiation-sensitive resin composition prepared as described above on a 12-inch silicon wafer on which a lower-layer antireflection film is formed using an antireflection coating material for semiconductor (trade name “ARC66”, manufactured by Nissan Chemical Co., Ltd.) Then, a film having a thickness of 110 nm was formed, and soft baking (SB) was performed at 120 ° C. for 60 seconds. Next, this film was coated with an ArF excimer laser immersion exposure apparatus (trade name “NSR S610C”, manufactured by NIKON) using NA = 1.3, iNA = 1.27, ratio = 0.800, DipoleX openAngle = 35 deg. Under the conditions, exposure was performed through a mask pattern of a line and space (1L1S) having a target size of 45 nm in width. After exposure, post-exposure baking (PEB) was performed at 80 ° C. for 60 seconds. Thereafter, a 2.38 mass% tetramethylammonium hydroxide aqueous solution was used as a developer, and development with a GP nozzle was performed for 10 seconds with a developing device of a clean track (trade name: “LITIUS Pro-i” manufactured by Tokyo Electron Ltd.). After the implementation, it was washed with water for 15 seconds and dried to form a positive resist pattern. At this time, the exposure amount for forming a line and space having a width of 45 nm was determined as the optimum exposure amount. The cross-sectional shape of the pattern formed with this optimum exposure dose was observed with a scanning electron microscope (trade name: “S-4800”, manufactured by Hitachi High-Technologies Corporation), and as shown in FIG. When the upper line width of the formed pattern 2 is L1 and the lower line width is L2, (L1−L2) / L1 is in the range of −0.15 to +0.15. The case where L1-L2) / L1 was smaller than −0.15 or larger than +0.15 was evaluated as “bad”.

[MEEF performance]
The exposure amount at which a line-and-space (LS) pattern having a line width of 50 nm is formed by exposing through a mask pattern having a target size of 50 nm 1 L / 1S was defined as the optimum exposure amount. Next, an LS pattern with a pitch of 100 nm is formed using a mask pattern with an optimum exposure amount and a line width target size of 43 nm, 44 nm, 45 nm, 46 nm, and 47 nm, and the line width formed on the resist film is measured. Measurement was performed with SEM (Hitachi, CG4000). At this time, the slope of the straight line when the target size (nm) was plotted on the horizontal axis and the line width (nm) formed on the resist film using each mask pattern was plotted on the vertical axis was calculated as MEEF. It is determined that the mask reproducibility is better as the value is closer to 1, and the mask creation cost can be reduced as the MEEF value is lower.

[Etching resistance]
After spin-coating the compositions of Examples and Comparative Examples on a silicon wafer having a diameter of 12 inches, it was heated in a hot plate at 100 ° C. for 60 seconds to form a resist film having a thickness of 0.3 μm. The resist film was evaluated using the etching system (Tokyo Electron, Telius) under the following etching conditions.
CF ₄ gas flow rate: 150sccm
Chamber pressure: 100 mTorr
Power: 300W (upper) / 300W (bottom)
Time: 40sec
Temperature: 60 ° C
And the film thickness before and behind an etching process was measured, the etching rate was computed, and the etching tolerance was evaluated on the following reference | standard.
“◯”: When the etching rate is less than 60 nm / min “Δ”: When the etching rate is 60 or more and less than 120 nm / min “X”: When the etching rate is 120 nm / min or more

  As shown in Table 2, it was found that the radiation sensitive resin composition of the present invention was excellent in pattern formability, etching resistance and MEEF performance. When the radiation sensitive resin composition of the present invention is used, a good fine pattern can be formed.

  The radiation sensitive resin composition of this invention is used suitably in formation of the resist pattern in the lithography process of various electronic devices, such as a semiconductor device and a liquid crystal device.

1 substrate 2 pattern

Claims (12)

[A] A polymer having a structural unit (I) containing a group R ^S represented by the following formula (1), and [B] a radiation-sensitive resin composition containing a radiation-sensitive acid generator.

(In formula (1), X, .R ² is a single bond or a divalent linking group, having 1 to 20 carbon atoms linear aliphatic hydrocarbon group or an alicyclic hydrocarbon having 4 to 20 carbon atoms Z ¹ and Z ² are each independently a divalent aliphatic hydrocarbon group having 1 to 14 carbon atoms, and a nuclear atom together with the carbon atom to which R ² is bonded and —SO ₂ —. An aliphatic heterocyclic group of 4 to 30 is formed, provided that Z ¹ and Z ² may be bonded to each other, part of the hydrogen atoms possessed by the aliphatic hydrocarbon group of Z ¹ and Z ² Or all may be substituted.) The structural unit (I) is a structural unit (I-1) represented by the following formula (1-1), a structural unit (I-2) represented by the following formula (1-2), and the following formula ( The radiation-sensitive resin composition according to claim 1, which is at least one structural unit selected from the group consisting of the structural unit (I-3) represented by 1-3).

(In Formula (1-1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.) The radiation-sensitive resin composition according to claim 1 or 2, wherein the aliphatic hydrocarbon group of Z ¹ and Z ^{2 is} an aliphatic chain hydrocarbon group having 1 to 8 carbon atoms.   The radiation-sensitive resin composition according to claim 1, wherein the aliphatic heterocyclic group is a monocyclic group.   The radiation-sensitive resin composition according to any one of claims 1 to 4, wherein the divalent linking group of X includes an ester group. [C] The radiation sensitive resin composition according to any one of claims 1 to 5, further comprising a polymer having a higher fluorine atom content than the polymer [A]. [A] The radiation sensitive resin composition according to any one of claims 1 to 6, wherein the polymer further has a structural unit represented by the following formula (2).

(In formula (2), R ^a1 Is a hydrogen atom or a methyl group. R ^a2 ~ R ^a4 Are each independently an alkyl group having 1 to 4 carbon atoms or an alicyclic hydrocarbon group having 4 to 20 carbon atoms. However, R ^a3 And R ^a4 And may be bonded to each other to form a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms together with the carbon atom to which they are bonded. ) [A] The radiation sensitive resin composition according to any one of claims 1 to 7, wherein the polymer further comprises a structural unit having a lactone structure or a cyclic carbonate structure. The content of the structural unit (I) in the [A] polymer is 5 mol% or more and 40 mol% or less with respect to all the structural units constituting the [A] polymer. The radiation sensitive resin composition of Claim 1. [D] Nitrogen-containing compound
The radiation sensitive resin composition according to any one of claims 1 to 9, further comprising: [E] Solvent
The radiation sensitive resin composition according to any one of claims 1 to 10, further comprising: (1) A resist film forming step of forming a resist film by applying the radiation-sensitive resin composition according to any one of claims 1 to 11 on a substrate,
(2) A pattern forming method including an exposure step of irradiating at least a part of the resist film, and (3) a developing step of developing the exposed resist film.

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