JP2017044874A - Radiation-sensitive resin composition and method for forming resist pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation-sensitive resin composition excellent in depth of focus, MEEF performance, LWR performance, resolution, rectangularity of a cross-sectional shape and film shrinkage suppressing property.SOLUTION: The radiation-sensitive resin composition comprises a polymer described below, a radiation-sensitive acid generator, and a solvent. The polymer has a first structural unit represented by formula (1) and a second structural unit represented by formula (2) and has a maleimide structural unit represented by formula (1-1) as the first structural unit, in which the content percentage of the first structural unit is 50 mol% or less and the content percentage of the maleimide structural unit is 4 mol% or more.SELECTED DRAWING: None

Description

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

  For forming various electronic devices such as semiconductor devices and liquid crystal devices, a resist pattern forming method by photolithography is used. In this resist pattern forming method, for example, a radiation sensitive resin composition for forming a resist pattern on a substrate is used. The radiation-sensitive resin composition generates an acid in an exposed portion by irradiation with radiation such as far ultraviolet rays such as ArF excimer laser light, electromagnetic waves such as extreme ultraviolet (EUV), and charged particle beams such as electron beams. The acid catalysis causes a difference in the dissolution rate of the exposed portion and the unexposed portion with respect to the developer, thereby forming a resist pattern on the substrate.

  Such a radiation sensitive resin composition can not only form a resist pattern with high resolution and excellent rectangularity in cross-sectional shape, but also has MEEF (Mask Error Enhancement Factor) performance indicating mask fidelity, and LWR (line width variation). In order to improve Line Width Roughness performance and process stability, it is required to be excellent in lithography performance and to obtain a highly accurate pattern with high yield. In response to this requirement, various structures of the polymer contained in the radiation-sensitive resin composition have been studied. By having a lactone structure such as a butyrolactone structure or a norbornane lactone structure, the resist pattern can be adhered to the substrate. It is known that these properties can be improved while improving the performance (see JP-A-11-212265, JP-A-2003-5375 and JP-A-2008-83370).

  However, at the present time when the resist pattern is miniaturized to a level of 50 nm or less, the required level of the performance is further increased, and the conventional radiation-sensitive resin composition can satisfy these requirements. Not done. Recently, in order to further improve the above-described resolution and the like, it is also required to have excellent film shrinkage suppression during post-exposure heating (PEB).

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

  The present invention has been made based on the above circumstances, and is a radiation-sensitive resin composition that is excellent in depth of focus, MEEF performance, LWR performance, resolution, rectangular cross-sectional shape, and film shrinkage suppression. For the purpose of provision.

（式（１）中、Ｒ^１１及びＲ^１２は、それぞれ独立して、水素原子又は炭素数１〜２０の１価の有機基である。Ｒ^１３は、炭素数１〜４０の２価の有機基であり、Ｒ^１３と結合している２つの炭素原子と共に環員数３〜４０の環構造を形成している。
式（２）中、Ｒ^２１、Ｒ^２２、Ｒ^２３及びＲ^２４は、それぞれ独立して、水素原子、フッ素原子又は炭素数１〜４０の１価の有機基である。
式（１−１）中、Ａは、単結合又は炭素数１〜２０の２価の有機基である。Ｌは、環内に−ＣＯ−、−Ｏ−及び−ＳＯ_２−から選ばれる基をひとつ以上有していてもよい、環員数４以上の１価の環状有機基である。） The invention made in order to solve the above problems includes a first structural unit represented by the following formula (1) (hereinafter also referred to as structural unit (I)) and a second structural unit represented by the following formula (2). (Hereinafter also referred to as “structural unit (II)”) (hereinafter also referred to as “[A] polymer”), radiation-sensitive acid generator (hereinafter also referred to as “[B] acid generator”). ), And a solvent (hereinafter also referred to as “[C] solvent”), and the [A] polymer is a maleimide structural unit represented by the following formula (1-1) as the structural unit (I) ( Hereinafter, it is also referred to as “structural unit (I-1)”, the content of the structural unit (I) in the [A] polymer is 50 mol% or less, and the structural unit in the [A] polymer. It is a radiation sensitive resin composition whose content rate of (I-1) is 4 mol% or more.

(In formula (1), R ¹¹ and R ¹² are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ¹³ is a divalent organic group having 1 to 40 carbon atoms. A ring structure having 3 to 40 ring members together with two carbon atoms bonded to R ¹³ .
In Formula (2), R ²¹ , R ²² , R ²³ and R ²⁴ are each independently a hydrogen atom, a fluorine atom or a monovalent organic group having 1 to 40 carbon atoms.
In formula (1-1), A represents a single bond or a divalent organic group having 1 to 20 carbon atoms. L is a monovalent cyclic organic group having 4 or more ring members, which may have one or more groups selected from —CO—, —O—, and —SO ₂ — in the ring. )

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

  Here, the “organic group” refers to a group containing at least one carbon atom. The “hydrocarbon group” includes a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The “hydrocarbon group” may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The “chain hydrocarbon group” refers to a hydrocarbon group that does not include a cyclic structure but includes only a chain structure, and includes both a linear hydrocarbon group and a branched hydrocarbon group. The term “alicyclic hydrocarbon group” refers to a hydrocarbon group that includes only an alicyclic structure as a ring structure and does not include an aromatic ring structure, and includes a monocyclic alicyclic hydrocarbon group and a polycyclic alicyclic group. Includes both hydrocarbon groups. However, it is not necessary to be composed only of the alicyclic structure, and a part thereof may include a chain structure. “Aromatic hydrocarbon group” refers to a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it is not necessary to be composed only of an aromatic ring structure, and a part thereof may include a chain structure or an alicyclic structure. “Number of ring members” means the number of atoms constituting the ring of an aromatic ring structure, aromatic heterocyclic structure, alicyclic structure and aliphatic heterocyclic structure. In the case of a polycyclic ring structure, this polycyclic ring The number of atoms to be played.

  According to the radiation-sensitive resin composition of the present invention, the [A] polymer has appropriate rigidity due to a specific structure, so that the depth of focus, MEEF performance, LWR performance, resolution, cross-sectional shape A resist pattern having excellent rectangularity and film shrinkage suppression (hereinafter also referred to as “lithographic performance”) can be formed. Therefore, the said radiation sensitive resin composition can be used suitably for semiconductor device manufacture for which further refinement | miniaturization is anticipated from now on.

<Radiation sensitive resin composition>
The radiation sensitive resin composition contains a [A] polymer, a [B] acid generator, and a [C] solvent. The radiation-sensitive resin composition contains [D] acid diffusion controller, [E] polymer having a higher fluorine atom content than [A] polymer, and [F] uneven distribution accelerator as suitable components. In the range which does not impair the effect of this invention, you may contain another arbitrary component. Hereinafter, each component will be described.

<[A] Polymer>
The [A] polymer has the structural unit (I) and the structural unit (II), the structural unit (I) has the structural unit (I-1), and the [A] structural unit (I ) Is a polymer having a content ratio of 50 mol% or less and a content ratio of the structural unit (I-1) in the [A] polymer of 4 mol% or more.

  The reason why the radiation-sensitive resin composition has the above-described configuration and exhibits the above-mentioned effects is not necessarily clear, but can be inferred as follows, for example. That is, since the [A] polymer has the structural unit (I-1) as the structural unit (I), its main chain has high rigidity. Moreover, in this structural unit (I-1), the lactone ring group, sultone ring group, or carbonate ring group which has polarity and bulkiness is moderately separated from the main chain of the [A] polymer. Therefore, the [A] polymer has moderate flexibility in combination with the rigidity of the main chain, and as a result, the rigidity as the polymer is appropriate. [A] Since the polymer has such a structural unit (I) and structural unit (I-1) in a specific content ratio, [B] the acid diffusion length generated from the acid generator is appropriately shortened. It is thought that you can. As a result, the lithography performance of the radiation sensitive resin composition can be improved.

  [A] The polymer may have other structural units in addition to the structural unit (I) and the structural unit (II). [A] The polymer is usually a base polymer in the radiation-sensitive resin composition. The “base polymer” refers to a polymer that is a main component of the polymers constituting the resist pattern, and preferably occupies 50% by mass or more, more preferably 60% by mass or more. Hereinafter, each structural unit will be described.

[Structural unit (I)]
The structural unit (I) is a structural unit represented by the following formula (1). In the structural unit (I), two mutually adjacent carbon atoms constituting the main chain of the [A] polymer form a ring structure.

The formula ^{(1), R 11} and ^{R 12} are each independently a monovalent organic group hydrogen atom or a C 1-20. R ¹³ is a divalent organic group having 1 to 40 carbon atoms, and forms a ring structure having 3 to 40 ring members together with two carbon atoms bonded to R ¹³ .

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ¹ and R ² include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a carbon-carbon bond or a bond of the hydrocarbon group. A group (a) containing a divalent heteroatom-containing group at the terminal on the side, a group obtained by substituting a part or all of the hydrogen atoms of the hydrocarbon group and group (a) with a monovalent heteroatom-containing group, etc. Can be mentioned.

  Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and the number of carbon atoms. Examples thereof include 6-20 monovalent aromatic hydrocarbon groups.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, alkyl groups such as t-butyl groups;
An alkenyl group such as an ethenyl group, a propenyl group, a butenyl group;
Examples thereof include alkynyl groups such as ethynyl group, propynyl group and butynyl group.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monocyclic cycloalkyl groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group;
A monocyclic cycloalkenyl group such as a cyclobutenyl group, a cyclopentenyl group, or a cyclohexenyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetracyclododecyl group;
And polycyclic cycloalkenyl groups such as a norbornenyl group, a tricyclodecenyl group, and a tetracyclododecenyl group.

Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group;
Examples include aralkyl groups such as benzyl group, phenethyl group, phenylpropyl group, naphthylmethyl group, and the like.

Examples of the divalent heteroatom-containing group include —O—, —CO—, —S—, —CS—, —SO ₂ —, —NR′—, a combination of two or more thereof, and the like. Is mentioned. R ′ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms.

  Examples of the monovalent heteroatom-containing group include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, hydroxy group, carboxy group, cyano group, amino group, sulfanyl group (-SH) and the like. .

Examples of the divalent organic group having 1 to 40 carbon atoms represented by R ^13, for example, a monovalent group derived by removing one hydrogen atom from an organic group exemplified as the R ¹¹ and R ¹² can be mentioned.

Examples of the ring structure having 3 to 40 ring members formed together with the two carbon atoms to which R ¹³ and R ¹³ are bonded include a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, a norbornane structure, and an adamantane structure. Alicyclic structures such as
Examples thereof include aliphatic heterocyclic structures such as an oxacyclopentane structure and an azacyclopentane structure.

  [A] The polymer has the structural unit (I-1) as the structural unit (I). The structural unit (I-1) is represented by the following formula (1-1).

In said formula (1-1), A is a single bond or a C1-C20 bivalent organic group. L is a monovalent cyclic organic group having 4 or more ring members, which may have one or more groups selected from —CO—, —O—, and —SO ₂ — in the ring.

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

  Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include a divalent chain hydrocarbon group having 1 to 20 carbon atoms, a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and the number of carbon atoms. A divalent aromatic hydrocarbon group of 6 to 20, a group (h) containing a divalent heteroatom-containing group at a carbon-carbon end or a bond-side end of the hydrocarbon group, the hydrocarbon group and the group ( and a group in which part or all of the hydrogen atoms in h) are substituted with a monovalent heteroatom-containing group.

Examples of the divalent chain hydrocarbon group having 1 to 20 carbon atoms include methanediyl group, ethanediyl group, n-propanediyl group, i-propanediyl group, n-butanediyl group, i-butanediyl group, and sec-butanediyl. Group, alkanediyl group such as t-butanediyl group;
Alkenediyl groups such as ethenediyl group, propenediyl group, butenediyl group;
Examples include alkynediyl groups such as ethynediyl group, propynediyl group, and butynediyl group.

Examples of the divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monocyclic cycloalkanediyl groups such as cyclopropanediyl group, cyclobutanediyl group, cyclopentanediyl group, and cyclohexanediyl group;
Monocyclic cycloalkenediyl groups such as cyclopropenediyl group, cyclobutenediyl group, cyclopentenediyl group, cyclohexenediyl group;
A polycyclic cycloalkanediyl group such as a norbornanediyl group, an adamantanediyl group, a tricyclodecanediyl group, a tetracyclododecanediyl group;
Examples thereof include polycyclic cycloalkenediyl groups such as norbornenediyl group, tricyclodecenediyl group, and tetracyclododecenediyl group.

Examples of the divalent aromatic hydrocarbon group having 6 to 20 carbon atoms include arenediyl groups such as benzenediyl group, toluenediyl group, naphthalenediyl group;
Examples thereof include arenediylalkanediyl groups such as benzenediylmethanediyl group and naphthalenediylmethanediyl group.

Examples of the divalent hetero atom-containing group include the same groups as those exemplified as the divalent hetero atom-containing group contained in the monovalent organic group of R ¹ and R ² .

The monovalent hetero atom-containing group described above, for example, monovalent same groups as the groups exemplified as the hetero atom-containing group contained in the monovalent organic group of said R ¹ and R ² can be mentioned.

  As A, from the viewpoint of adjusting the rigidity of the polymer [A] more appropriately and further improving the lithography performance, a single bond or a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms is Preferably, a single bond or a substituted or unsubstituted divalent chain hydrocarbon group having 1 to 20 carbon atoms is more preferable, and a single bond or a substituted or unsubstituted divalent alkyl group having 1 to 20 carbon atoms is more preferable. A single bond or a substituted or unsubstituted divalent alkyl group having 1 to 10 carbon atoms is particularly preferable, and a single bond or a substituted or unsubstituted divalent alkyl group having 1 to 5 carbon atoms is more particularly preferable.

As the A, [A] by more appropriately adjust the rigidity of the polymer, from the viewpoint of further improving the LWR performance and MEEF performance, a single bond and ^{-CR 14 R} 15 - ^(R 14 and ^{R 15} Are each independently a hydrogen atom or a monovalent organic group having 1 to 19 carbon atoms).

  Moreover, as said A, it is an organic group and a carbonyl group is included from a viewpoint which balances both a depth of focus and MEEF performance at a high level by adjusting the rigidity of [A] polymer more appropriately. It is preferable.

As said L, the cyclic organic group which does not have an aromatic ring structure is preferable. As the above-mentioned L, -CO in the ring -, - O-and -SO ₂ - cyclic organic group having more than one group selected from the preferred. Moreover, as said L, a lactone ring group, a sultone ring group, and a carbonate ring group are preferable.

  The “lactone ring group” is a group formed by removing one hydrogen atom bonded to a carbon atom constituting one ring (lactone ring) including a group represented by —O—C (O) —. Say. The ring structure may have other rings in addition to the lactone ring. The lactone ring group may have a substituent that substitutes part or all of the hydrogen atoms bonded to the carbon atoms constituting the lactone ring. In addition, this lactone ring is counted as the first ring, and when it is only a lactone ring, it is referred to as a monocyclic lactone ring group, and when it has another ring, it is referred to as a polycyclic lactone ring group regardless of its structure.

Examples of the lactone ring group include monocyclic lactone ring groups such as a butyrolactone ring group and a valerolactone ring group;
And polycyclic lactone ring groups such as norbornane lactone ring group and 5-oxo-4-oxatricyclo [4.3.1.1 ^3,8 ] undecane ring group.

  Examples of the substituent include a hydrocarbon group, a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, a hydroxy group, a carboxy group, a cyano group, an amino group, and a sulfanyl group (—SH).

The “sultone ring group” refers to a group formed by removing one hydrogen atom bonded to a carbon atom constituting one ring (sultone ring) represented by —O—S (O ₂ ) —. The ring structure may have other rings in addition to the sultone ring. The sultone ring group may have a substituent that substitutes part or all of the hydrogen atoms to which the carbon atoms constituting the sultone ring are bonded. In addition, this lactone is counted as the first ring, and when it is only a lactone ring, it is called a monocyclic sultone ring group, and when it has another ring, it is called a polycyclic sultone ring group regardless of its structure.

Examples of the sultone ring group include monocyclic sultone ring groups such as butyrosultone ring group and valerosultone ring group;
And polycyclic sultone ring groups such as norbornane sultone ring group.

  Here, the “carbonate ring” means a group formed by removing one hydrogen atom bonded to a carbon atom constituting one ring (carbonate ring) represented by —O—C (O) —. . The ring structure may have other rings in addition to the carbonate ring. You may have a substituent which substitutes a part or all of the hydrogen atom which the carbon atom which comprises a carbonate ring has couple | bonded. Further, this carbonate ring is counted as the first ring, and in the case of only the carbonate ring, it is called a monocyclic carbonate ring group, and in the case of having another ring, it is called a polycyclic carbonate ring group regardless of its structure.

Examples of the carbonate ring group include monocyclic carbonate ring groups such as a butyrocarbonate ring group and a valerocarbonate ring group;
And polycyclic carbonate ring groups such as norbornane carbonate ring group.

  Examples of the structural unit (I-1) include structural units represented by the following formulas (1-1-1) to (1-1-36) (hereinafter referred to as “structural units (I-1-1) to (I -1-36) ")).

  As the structural unit (I-1), structural units (I-1-1) to (I-1-17), (I-1-25) and (I-1-33) are preferable. -1-5), (I-1-7), (I-1-14) and (I-1-15) are more preferable.

  The compound that gives the structural unit (I-1) (hereinafter also referred to as “compound (I-1)”) is, for example, a compound (hereinafter referred to as “compound (I-1)”) represented by the following formula (1-1 ′): In the case of “compound (I-1 ′)”, as shown in the following scheme, a compound represented by the following formula (a) and a compound represented by the following formula (b1) are combined with potassium carbonate or the like. In the presence of a base in a solvent such as dimethylformamide.

  In the above scheme, A is a single bond or a divalent organic group having 1 to 20 carbon atoms. L is a lactone ring group, a sultone ring group, or a carbonate ring group. X 'is a halogen atom.

  Examples of the halogen atom represented by X ′ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, a chlorine atom and a bromine atom are preferable, and a chlorine atom is more preferable.

  Compound (I-1) is, for example, a compound (I-1) represented by the following formula (1-1 ″) (hereinafter also referred to as “compound (I-1 ″)”) or the following formula ( In the case of a compound represented by 1-1 ″ ′) (hereinafter also referred to as “compound (I-1 ′ ″)”), as represented by the following scheme, a compound represented by the following formula (a): And a compound represented by the following formula (b2) or (b3) can be produced by addition reaction in a solvent such as dichloromethane in the presence of a base such as potassium carbonate. In the above reaction, it is preferable that the carbon-carbon double bond of the maleimide structure is protected with, for example, cyclopentadiene. Thereafter, the maleimide structure is regenerated by deprotection.

  In the above scheme, A ′ is a single bond or a divalent organic group having 1 to 18 carbon atoms. L is a lactone ring group, a sultone ring group, or a carbonate ring group.

  [A] The lower limit of the content of the structural unit (I-1) in the polymer is 4 mol%, more preferably 7 mol%, based on all structural units constituting the [A] polymer. Mole% is particularly preferred. As an upper limit of the said content rate, 49 mol% is preferable with respect to all the structural units which comprise a [A] polymer, 35 mol% is more preferable, and 25 mol% is especially preferable.

  The lower limit of the content ratio of the structural unit (I-1) in the structural unit (I) is preferably 20 mol%, more preferably 40 mol%, based on all structural units constituting the structural unit (I). More preferred is mol%, and particularly preferred is 90 mol%.

  As the structural unit (I), in addition to the structural unit (I-1), other structural units derived from substituted or unsubstituted cycloalkenes (for example, structural units derived from substituted or unsubstituted norbornene, etc.) You may have a structural unit. The structural unit (I) preferably has substantially no other structural unit. Here, “substantially free” of the other structural unit means that the upper limit of the content ratio of the structural unit derived from the unsubstituted cycloalkene is the total structural unit constituting the polymer [A]. On the other hand, it is preferably 2 mol%, more preferably 1 mol%, still more preferably 0.1 mol%, and particularly preferably 0 mol%.

  [A] The upper limit of the content ratio of the structural unit (I) in the polymer is 50 mol%, more preferably 40 mol%, more preferably 30 mol%, based on all structural units constituting the [A] polymer. Is more preferable. [A] The lower limit of the content ratio of the structural unit (I) in the polymer is preferably 4 mol%, more preferably 9 mol%, and 19 mol% with respect to all the structural units constituting the [A] polymer. Is more preferable. By making the content rate of structural unit (I) into the said range, the sensitivity of the said radiation sensitive resin composition can be improved more, and, as a result, both the depth of focus and MEEF performance can be made compatible at a high level. it can.

[Structural unit (II)]
The structural unit (II) is represented by the following formula (2). In the structural unit (II), two adjacent carbon atoms constituting the main chain of the [A] polymer do not form a ring structure.

In said formula (2), R <^21> , R <^22> , R <^23> and R <^24> are respectively independently a hydrogen atom, a fluorine atom, or a C1-C40 monovalent organic group.

Examples of the monovalent organic group having 1 to 40 carbon atoms represented by R ²¹ , R ²² , R ²³ and R ²⁴ include monovalent organic groups exemplified as R ¹ and R ^{2 in} the above formula (1). And the like groups.

The structural unit (II) may have an acid dissociable group. That is, at least one of R ²¹ , R ²² , R ²³ and R ^{24 in} the above formula (2) may be a group containing an acid dissociable group. The “acid-dissociable group” refers to a group that substitutes a hydrogen atom of a carboxy group or a phenolic hydroxyl group and dissociates by the action of an acid. [A] When the polymer has an acid-dissociable group, the sensitivity of the radiation-sensitive resin composition can be further increased, and as a result, the lithography performance can be further improved.

The structural unit (II) may have a lactone ring group, a cyclic carbonate ring group, a sultone ring group, a polar group, or a combination thereof (hereinafter also referred to as “polar group or the like”). At least one of R ²¹ , R ²² , R ²³ and R ²⁴ in 2) may be a group having the above polar group, etc. Examples of the polar group include a hydroxy group, a carboxy group, an amino group, and a sulfonamide group. , A cyano group, a nitro group, etc. [A] Since the polymer has a polar group or the like, the solubility in a developer can be appropriately adjusted, and as a result, the radiation-sensitive resin composition. The lithography performance of the product can be further improved, and the adhesion between the resist pattern formed from the radiation-sensitive resin composition and the substrate can be improved.

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

In the above formula ^{(2-1), R 31} is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ³² is a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms.

In said formula (2-2), ^R41 is a hydrogen atom or a methyl group. X is a hydroxy group, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms. n is an integer of 0-5. When n is 2 or more, the plurality of Xs may be the same or different.

R ³¹ is preferably a hydrogen atom or a methyl group, and more preferably a methyl group, from the viewpoint of the copolymerizability of the homopolymer that gives the structural unit (II-1).

Examples of the monovalent organic group having 1 to 40 carbon atoms represented by R ³² include groups similar to the monovalent organic groups exemplified as R ¹ and R ^{2 in} the above formula (1).

R ⁴¹ is preferably a hydrogen atom from the viewpoint of copolymerizability of the monomer that gives the structural unit (II-2).

  Examples of the halogen atom represented by X include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by X include groups similar to the monovalent organic groups exemplified as R ¹ and R ^{2 in} the above formula (1).

Examples of the structural unit (II-1) include a structural unit containing an acid dissociable group (hereinafter, also referred to as “structural unit (II-1-1)”). Examples of the structural unit (II-1) include structural units in which R ³² in the above formula (2-1) is a group containing an acid dissociable group. Further, as the structural unit (II-1), for example, a structural unit containing a lactone ring group, a cyclic carbonate ring group, a sultone ring group and a polar group or a combination thereof (hereinafter referred to as “structural unit (II-1-2)”). Also called). Examples of the structural unit (II-1) include structural units in which R ³² in the above formula (2-1) is a group containing a polar group or the like.

  Examples of the structural unit (II-1-1) include a structural unit represented by the following formula (2-1-1).

In the above formula ^{(2-1-1), R 31} is as defined in the above formula (2-1). R ^32a is a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. R ^32b and R ^32c are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or these groups are It represents an alicyclic structure having 3 to 20 carbon atoms, which is formed together with the carbon atoms to which they are bonded.

Examples of the monovalent chain hydrocarbon group having 1 to 10 carbon atoms represented by R ^32a , R ^32b, and R ^32c include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, and an i-propyl group. ;
An alkenyl group such as an ethenyl group, a propenyl group, a butenyl group;
Examples thereof include alkynyl groups such as ethynyl group, propynyl group and butynyl group.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ^32a , R ^32b and R ^32c include monocyclic cycloalkyl groups such as a cyclopentyl group and a cyclohexyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group and a tricyclodecyl group;
A monocyclic cycloalkenyl group such as a cyclopentenyl group and a cyclohexenyl group;
Examples thereof include polycyclic cycloalkenyl groups such as norbornenyl group and tricyclodecenyl group.

Examples of the alicyclic structure having 3 to 20 carbon atoms constituted by the carbon atoms to which the groups of R ^32b and R ^32c are combined and bonded to each other include, for example, a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, a cyclo Monocyclic cycloalkane structures such as heptane structure and cyclooctane structure;
Examples thereof include polycyclic cycloalkane structures such as a norbornane structure, an adamantane structure, a tricyclodecane structure, and a tetracyclododecane structure.

  As the structural unit (II-1-1), structural units represented by the following formulas (2-1-1-1) to (2-1-1-6) (hereinafter referred to as “structural unit (II-1-1)”). 1-1) to (II-1-1-6) ”).

In the above formulas (2-1-1-1) to (2-1-1-3), R ³¹ , R ^32a , R ^32b and R ^32c have the same meaning as the above formula (2-1-1). R ^{32a ′} , R ^{32b ′} and R ^{32c ′} are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms. n _p is each independently an integer of 1 to 4.

  Examples of the structural units (II-1-1-1) to (II-1-1-6) include structural units represented by the following formulas.

In the above formula, R ³¹ has the same meaning as the above formula (2-1).

R ³¹ is preferably a hydrogen atom and a methyl group, more preferably a methyl group, from the viewpoint of copolymerization of the monomer that gives the structural unit (II-1-2).

  Among these, a structural unit derived from 1-alkylcycloalkyl (meth) acrylate and a structural unit derived from cycloalkyldialkyl (meth) acrylate are preferable.

  [A] When the polymer has the structural unit (II-1-1), the lower limit of the content ratio of the structural unit (II-1-1) is [A] all structural units constituting the polymer. On the other hand, 10 mol% is preferable, 20 mol% is more preferable, and 30 mol% is further more preferable. As an upper limit of the said content rate, 90 mol% is preferable, 80 mol% is more preferable, and 75 mol% is further more preferable. By making the content rate of structural unit (II-1-1) into the said range, the sensitivity of the said radiation sensitive resin composition can be raised more, and, as a result, lithography performance can be improved more.

  Examples of the structural unit (II-1-2) include a structural unit represented by the following formula.

In the above formula, R ³¹ has the same meaning as the above formula (2-1).

R ³¹ is preferably a hydrogen atom and a methyl group, more preferably a methyl group, from the viewpoint of copolymerization of the monomer that gives the structural unit (II-1-2).

  Among these, as the structural unit (II-1-2), a structural unit containing a norbornane lactone ring group, a structural unit containing an oxanorbornane lactone ring group, a structural unit containing a γ-butyrolactone ring group, and a norbornane sultone ring group , A structural unit containing an ethylene carbonate cyclic group, and a structural unit containing a 3-hydroxyadamantyl group are preferred.

  [A] When a polymer has a structural unit (II-1-2), as a minimum of the content rate of a structural unit (II-1-2), with respect to all the structural units which comprise a [A] polymer. 1 mol% is preferable and 5 mol% is more preferable. As an upper limit of the said content rate, 80 mol% is preferable, 70 mol% is more preferable, and 60 mol% is further more preferable. By making the content rate of structural unit (II-1-2) into the said range, the adhesiveness to the board | substrate of the resist pattern formed from the said radiation sensitive resin composition can be improved more.

  As the structural unit (II-2), a structural unit containing an acid-dissociable group (hereinafter, also referred to as “structural unit (II-2-1)”), that is, X in the above formula (2-2) is acid-dissociated. A structural unit which is a group containing a functional group, a structural unit containing a phenolic hydroxyl group (hereinafter also referred to as “structural unit (II-2-2)”), that is, X in the above formula (2-2) is a phenolic hydroxyl group The structural unit etc. which are are mentioned.

  Examples of the structural unit (II-2-1) include a structural unit represented by the following formula (2-2-1).

In the above formula ^{(2-2-1), R 41} is as defined in the above formula (2-2). R ^Xa is a hydrogen atom or a C 1-20 valent hydrocarbon group. R ^Xb and R ^Xc are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent oxyhydrocarbon group having 1 to 20 carbon atoms.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the above R ^Xa , R ^Xb and R ^Xc include, for example, a monovalent chain hydrocarbon group having 1 to 20 carbon atoms and 3 to 20 carbon atoms. Examples thereof include a monovalent alicyclic hydrocarbon group and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, alkyl groups such as t-butyl groups;
An alkenyl group such as an ethenyl group, a propenyl group, a butenyl group;
Examples thereof include alkynyl groups such as ethynyl group, propynyl group, and butynyl group.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monocyclic cycloalkyl groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group;
A monocyclic cycloalkenyl group such as a cyclobutenyl group, a cyclopentenyl group, or a cyclohexenyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetracyclododecyl group;
And polycyclic cycloalkenyl groups such as a norbornenyl group, a tricyclodecenyl group, and a tetracyclododecenyl group.

Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group;
Examples thereof include aralkyl groups such as benzyl group, phenethyl group, phenylpropyl group and naphthylmethyl group.

Examples of the divalent hetero atom-containing group include the same groups as those exemplified as the divalent hetero atom-containing group contained in the monovalent organic group of R ¹ and R ² .

The monovalent hetero atom-containing group described above, for example, monovalent same groups as the groups exemplified as the hetero atom-containing group contained in the monovalent organic group of said R ¹ and R ² can be mentioned.

R ^Xa , R ^Xb and R ^Xc are preferably monovalent chain hydrocarbon groups, more preferably alkyl groups, and even more preferably methyl groups.

Examples of the monovalent oxyhydrocarbon group having 1 to 20 carbon atoms represented by the above R ^Xa , R ^Xb and R ^Xc include 1 to 1 carbon atoms represented by the above R ^Xa , R ^Xb and R ^Xc. Examples of the valent hydrocarbon group include those containing an oxygen atom at the terminal on the bond side.

  Specific examples of the structural unit (II-2-1) include a structural unit represented by the following formula.

In the above ^{formula, R 41} is as defined in the above formula (2-2).

  [A] When the polymer has the structural unit (II-2-1), the lower limit of the content ratio of the structural unit (II-2-1) in the [A] polymer constitutes the [A] polymer. 10 mol% is preferable with respect to all the structural units, 20 mol% is more preferable, and 30 mol% is further more preferable. As an upper limit of the said content rate, 90 mol% is preferable, 80 mol% is more preferable, and 75 mol% is further more preferable. By making the content rate of structural unit (II-2-1) into the said range, the sensitivity of the said radiation sensitive resin composition can be raised more, and, as a result, lithography performance can be improved more as a result. it can.

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

In the above formula ^{(2-2-2), R 41} is as defined in the above formula (2-2). R ^Xd is a monovalent organic group having 1 to 20 carbon atoms. r is an integer of 0-3. When r is 2 or 3, the plurality of R ^Xd may be the same or different. s is an integer of 1 to 3. However, r + s is 5 or less.

R ⁴¹ is preferably a methyl group from the viewpoint of the copolymerizability of the monomer giving the structural unit (II-2-2).

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ^Xd include the same groups as the monovalent organic groups exemplified as R ¹ and R ^{2 in} the above formula (1).

  Among these, a monovalent chain hydrocarbon group is preferable, an alkyl group is more preferable, and a methyl group is more preferable.

  As said r, the integer of 0-2 is preferable, 0 and 1 are more preferable, and 0 is further more preferable.

  As said s, 1 and 2 are preferable and 1 is more preferable.

  Specific examples of the structural unit (II-2-2) include structural units represented by the following formulas (2-2-2-1) to (2-2-2-5) (hereinafter referred to as “structure”). Units (II-2-2-1) to (II-2-2-5) ”) and the like.

  [A] When the structural unit has the structural unit (II-2-2), the structural unit (II-2-2) is preferably a structural unit containing a phenol structure.

  [A] When the polymer has a structural unit (II-2-2), the lower limit of the content ratio of the structural unit (II-2-2) is based on the total structural units constituting the [A] polymer. 1 mol% is preferable and 5 mol% is more preferable. As an upper limit of the content rate of the said structural unit (II-2-2), 80 mol% is preferable, 70 mol% is more preferable, and 60 mol% is further more preferable. By making the content rate of structural unit (II-2-2) into the said range, the adhesiveness to the board | substrate of the resist pattern formed from the said radiation sensitive resin composition can be improved more.

[Other structural units]
[A] The polymer may have other structural units in addition to the structural units (I) and (II). Examples of the other structural unit include a structural unit derived from a cyclic compound having a methylene group. [A] When the polymer has other structural units, the upper limit of the content ratio of the other structural units is preferably 20 mol% with respect to all the structural units constituting the [A] polymer, and is preferably 10 mol%. Is more preferable.

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

Examples of the radical polymerization initiator include azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2-cyclopropyl). Azo radical initiators such as propionitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2′-azobisisobutyrate;
And peroxide radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, and the like.

  Of these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred, and AIBN is more preferred. These radical initiators can be used alone or in combination of two or more.

Examples of the solvent used for the polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane;
Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane;
Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene;
Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, chlorobenzene;
Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate and methyl propionate;
Ketones such as acetone, methyl ethyl ketone, 4-methyl-2-pentanone, 2-heptanone;
Ethers such as tetrahydrofuran, dimethoxyethanes, diethoxyethanes;
Alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2-pentanol, propylene glycol monomethyl ether;
Examples of amide solvents include chain amides such as N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, and N-methylpropionamide. And amides such as cyclic amides such as N-methylpyrrolidone and N, N′-dimethylimidazolidinone.

  Of these, ketones, ethers and amides are preferred. The solvent used for these polymerizations may be used alone or in combination of two or more.

  As a minimum of reaction temperature in the above-mentioned polymerization, it is usually 40 ° C and 50 ° C is preferred. The upper limit of the reaction temperature is usually 150 ° C, preferably 120 ° C. The lower limit of the reaction time is usually 1 hour. The upper limit of the reaction time is usually 48 hours, preferably 24 hours.

  [A] The lower limit of the weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is preferably 1,000, more preferably 2,000, still more preferably 2,500, and 3,000. Is particularly preferred. The upper limit of Mw is preferably 50,000, more preferably 30,000, still more preferably 20,000, and particularly preferably 15,000. [A] By making Mw of a polymer into the said range, the applicability | paintability and development defect inhibitory property of the said radiation sensitive resin composition improve. [A] If the Mw of the polymer is less than the lower limit, a resist film having sufficient heat resistance may not be obtained.

  [A] The lower limit of the ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC of the polymer is usually 1, and 1.1 is preferable. The upper limit of the Mw / Mn is usually 5, preferably 3 and more preferably 2.

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

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

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

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

  [B] Specific examples of the acid generator include compounds described in paragraphs [0080] to [0113] of JP-A-2009-134088.

  [B] The acid generator is preferably a compound represented by the following formula (4). [B] By making the acid generator a compound represented by the following formula (4), the diffusion length of acid generated by exposure in the resist film due to the interaction with the polar structure of the [A] polymer, etc. As a result, the lithography performance and the like of the radiation sensitive resin composition can be further improved.

In the above formula (4), R ^a1 is a monovalent group containing an alicyclic structure having 6 or more ring members or a monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members. R ^a2 is a fluorinated alkanediyl group having 1 to 10 carbon atoms. M ⁺ is a monovalent radiation-sensitive onium cation.

Examples of the monovalent group including an alicyclic structure having 6 or more ring members represented by R ^a1 include monocyclic cycloalkyl groups such as a cyclooctyl group, a cyclononyl group, a cyclodecyl group, and a cyclododecyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group, a hydroxyadamantyl group, an adamantylmethyl group, an adamantyloxycarbonyl group, an adamantylcarbonyloxy group, a tricyclodecyl group, a tetracyclododecyl group;
A monocyclic cycloalkenyl group such as a cyclooctenyl group and a cyclodecenyl group;
And polycyclic cycloalkenyl groups such as a norbornenyl group and a tricyclodecenyl group.

Examples of the monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members represented by R ^a1 include a norbornanelactone-yl group, 5-oxo-4-oxatricyclo [4.3.1.1, and the like. ^3,8 ] groups containing a lactone structure such as an undecan-yl group;
A group containing a sultone structure such as a norbornane sultone-yl group and a norbornane sultone oxycarbonyl-yl group;
An oxygen atom-containing heterocyclic group such as an oxacycloheptyl group and an oxanorbornyl group;
A nitrogen atom-containing heterocyclic group such as an azacyclohexyl group, an azacyclohexylsulfonyl group, an azacycloheptyl group, a diazabicyclooctane-yl group;
And sulfur atom-containing heterocyclic groups such as a thiacycloheptyl group and a thianorbornyl group.

The lower limit of the number of ring members of the group represented by R ^a1 is preferably 8, more preferably 9, and even more preferably 10. As an upper limit of the number of ring members, 15 is preferable, and 13 is more preferable. By setting it as the said range, the diffusion length of the above-mentioned acid becomes more moderate, and as a result, the lithography performance of the said radiation sensitive resin composition can further be improved.

Of these, R ^a1 is preferably a polycyclic cycloalkyl group, a group containing a sultone structure, or a nitrogen atom-containing heterocyclic group, more preferably an adamantyl group, a norbornane sultone-yl group, or an azacyclohexyl group.

Examples of the fluorinated alkanediyl group having 1 to 10 carbon atoms represented by R ^a2 include one or more hydrogen atoms of an alkanediyl group having 1 to 10 carbon atoms such as a methanediyl group, an ethanediyl group, and a propanediyl group. And a group in which is substituted with a fluorine atom. Among these, SO ₃ ^- fluorinated alkane diyl group which has a fluorine atom to carbon atom is bonded to adjacent groups are preferred, SO ₃ ^- 2 fluorine atoms to the carbon atom adjacent to the group is attached More preferred are fluorinated alkanediyl groups, 1,1-difluoromethanediyl group, 1,1-difluoroethanediyl group, 1,1,3,3,3-pentafluoro-1,2-propanediyl group, 1,1 1,2,2-tetrafluoroethanediyl group, 1,1,2,2-tetrafluorobutanediyl group and 1,1,2,2-tetrafluorohexanediyl group are more preferable.

The monovalent radiation-sensitive onium cation represented by M ⁺ is a cation that decomposes upon irradiation with radiation. In the exposed portion, sulfonic acid is generated from protons generated by the decomposition of the radiation-sensitive onium cation and sulfonate anions. Examples of the monovalent radiation-sensitive onium cation represented by M ⁺ include a sulfonium cation, a tetrahydrothiophenium cation, and an iodonium cation. Among these, a cation represented by the following formula (X-1), a cation represented by the following formula (X-2), and a cation represented by the following formula (X-3) are preferable.

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

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

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

Examples of the linear alkyl group represented by R ^a1 , R ^a2 , R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Etc.

Examples of the branched alkyl group represented by R ^a1 , R ^a2 , R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include i-propyl group, i-butyl group, sec-butyl group, t -A butyl group etc. are mentioned.

Examples of the aromatic hydrocarbon group represented by the above R ^a1 , R ^a2 , R ^a3 , R ^c1 and R ^c2 include aryl groups such as phenyl group, tolyl group, xylyl group, xylyl group, mesityl group and naphthyl group; benzyl group, And aralkyl groups such as phenethyl group.

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

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

As R ^a1 , R ^a2 , R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 , a linear or branched alkyl group, a fluorinated alkyl group, a valent aromatic hydrocarbon group, —OSO ₂ —R ″ and —SO ₂ —R ″ are preferred, fluorinated alkyl groups and monovalent aromatic hydrocarbon groups are more preferred, and fluorinated alkyl groups are more preferred. R ″ is an unsubstituted monovalent alicyclic hydrocarbon group or an unsubstituted monovalent aromatic hydrocarbon group.

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

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

  Examples of the acid generator represented by the above formula (4) include compounds represented by the following formulas (4-1) to (4-15) (hereinafter referred to as “compounds (4-1) to (4-15). ) ")) And the like.

In the formulas (4-1) to (4-15), M ⁺ has the same meaning as the formula (4).

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

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

<[C] solvent>
The said radiation sensitive resin composition contains a [C] solvent. [C] The solvent dissolves or disperses the [A] polymer and the [B] acid generator, and the [D] acid diffusion controller, the [E] polymer and other optional components contained as necessary. If it can do, it will not specifically limit. [C] Examples of the solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrogenated solvents, and the like.

Examples of the alcohol solvent include aliphatic monoalcohol solvents having 1 to 18 carbon atoms such as 4-methyl-2-pentanol and n-hexanol;
An alicyclic monoalcohol solvent having 3 to 18 carbon atoms such as cyclohexanol;
A polyhydric alcohol solvent having 3 to 18 carbon atoms such as 1,2-propylene glycol;
Examples thereof include C3-C19 polyhydric alcohol partial ether solvents such as propylene glycol monoethyl ether.

Examples of ether solvents include dialiphatic ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether;
Aromatic ring ether solvents such as anisole and diphenyl ether;
Examples thereof include cyclic ether solvents such as tetrahydrofuran and dioxane.

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-amyl ketone, ethyl-n-butyl ketone, methyl-n-hexyl. Chain ketone solvents such as ketone, di-iso-butyl ketone, trimethylnonanone, acetophenone;
Cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone;
And diketone solvents such as 2,4-pentanedione and acetonylacetone.

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

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

  Among these, ester solvents and ketone solvents are preferable, and polyhydric alcohol partial ether carboxylate solvents and cyclic ketone solvents are more preferable. [C] A solvent can be used individually by 1 type or in mixture of 2 or more types.

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

  [D] As the acid diffusion controller, for example, a compound represented by the following formula (5) (hereinafter also referred to as “nitrogen-containing compound (I)”), a compound having two nitrogen atoms in the same molecule (hereinafter referred to as “nitrogen-containing compound (I)”) "Nitrogen-containing compound (II)"), compounds having three nitrogen atoms (hereinafter also referred to as "nitrogen-containing compound (III)"), amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, etc. It is done.

In the above formula (5), R ⁵¹ , R ⁵² and R ⁵³ are each independently a hydrogen atom, an optionally substituted linear, branched or cyclic alkyl group, an aryl group or an aralkyl group. .

  Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine and tri-n-pentylamine; aniline, 2, And aromatic amines such as 6-di-propylaniline.

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

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

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

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

  Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N- (undecan-1-ylcarbonyloxyethyl) morpholine; pyrazine, pyrazole and the like. .

  Among these, nitrogen-containing compounds (I) and nitrogen-containing heterocyclic compounds are preferable, trialkylamines, aromatic amines and morpholines are more preferable, tri-n-pentylamine, 2,6-dii-propylaniline. And N- (n-undecan-1-ylcarbonyloxyethyl) morpholine is more preferred.

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

  Further, as the [D] acid diffusion control agent, a photodisintegratable base that is exposed to light and generates a weak acid by exposure can also be used. Examples of the photodegradable base include an onium salt compound that loses acid diffusion controllability by being decomposed by exposure. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (6-1), an iodonium salt compound represented by the following formula (6-2), and the like.

In the above formulas (6-1) and (6-2), R ⁶¹ , R ⁶² , R ⁶³ , R ⁶⁴ and R ⁶⁵ are each independently a hydrogen atom, alkyl group, alkoxy group, hydroxy group or halogen. Is an atom. E ⁻ and Q ⁻ are each independently an anion represented by OH ⁻ , R ^β —COO ⁻ , R ^β —SO ₃ ^— or the following formula (6-3). However, R ( ^beta) is an alkyl group, an aryl group, or an aralkyl group.

In the above formula (6-3), R ⁶⁶ represents a linear or branched alkyl group having 1 to 12 carbon atoms in which part or all of the hydrogen atoms may be substituted with fluorine atoms, or 1 carbon atom. It is a -12 linear or branched alkoxyl group. u is an integer of 0-2.

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

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

  When the radiation sensitive resin composition contains a [D] acid diffusion controller, the lower limit of the content of the [D] acid diffusion controller is that the [D] acid diffusion controller is a [D] acid diffusion controller. In this case, 0.1 part by mass is preferable and 0.3 part by mass is more preferable with respect to 100 parts by mass of the [E] polymer described later. As an upper limit of the said content, 90 mass parts is preferable, 85 mass parts is more preferable, and 80 mass parts is further more preferable. [D] By making content of an acid diffusion control body into the said range, the lithography performance of the said radiation sensitive resin composition can be improved. [D] When the content of the acid diffusion controller exceeds the above upper limit, the sensitivity of the radiation-sensitive resin composition may decrease. The radiation-sensitive resin composition may contain one or more [D] acid diffusion controllers.

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

[E] The lower limit of the fluorine atom content of the polymer is preferably 1% by mass, more preferably 2% by mass, further preferably 4% by mass, and particularly preferably 7% by mass. The upper limit of the fluorine atom content is preferably 60% by mass, more preferably 40% by mass, and even more preferably 30% by mass. [E] When the fluorine atom content of the polymer is less than the lower limit, the hydrophobicity of the resist film surface may be lowered. In addition, the fluorine atom content rate (mass%) of a polymer can obtain | require the structure of a polymer by < ¹³ > C-NMR spectrum measurement, and can calculate it from the structure.

  [E] The fluorine atom content in the polymer is not particularly limited and may be bonded to any of the main chain, the side chain, and the terminal, but is a structural unit containing a fluorine atom (hereinafter referred to as “structural unit (VII)”). It is preferable to have (also called).

  [E] The polymer preferably has an alkali dissociable group. [E] When the polymer has an alkali-dissociable group, the resist film surface can be effectively changed from hydrophobic to hydrophilic during alkali development, and the development defect suppression of the radiation-sensitive resin composition is improved. . The “alkali dissociable group” is a group that replaces a hydrogen atom of a carboxy group, a hydroxy group, etc., and dissociates in an alkaline aqueous solution (for example, a 2.38 mass% tetramethylammonium hydroxide aqueous solution at 23 ° C.). Refers to the group.

  As the structural unit (VII), a structural unit represented by the following formula (7a) (hereinafter also referred to as “structural unit (VIIa)”), a structural unit represented by the following formula (7b) (hereinafter referred to as “structure”). Unit (VIIb) ”) or combinations thereof are preferred. The structural unit (VII) may have one or more structural units (VIIa) and structural units (VIIb).

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

In said formula (7a), ^Rd is a hydrogen atom, a methyl group, or a trifluoromethyl group. G is a single bond, an oxygen atom, a sulfur atom, —CO—O—, —SO ₂ —O—NH—, —CO—NH— or —O—CO—NH—. R ^e is a monovalent fluorinated chain hydrocarbon group having 1 to 6 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 4 to 20 carbon atoms.

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

As the _{G, -CO-O -, -} SO 2 -O-NH -, - CO-NH- and -O-CO-NH- are preferred, -CO-O-are more preferred.

Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 6 carbon atoms represented by R ^e, for example, a trifluoromethyl group, a 2,2,2-trifluoroethyl group, perfluoroethyl group, 2 , 2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoropropyl group, perfluoro n-propyl group, perfluoro i-propyl group, perfluoro n-butyl Group, perfluoro i-butyl group, perfluoro t-butyl group, 2,2,3,3,4,4,5,5-octafluoropentyl group, perfluorohexyl group and the like.

The monovalent fluorine-cycloaliphatic hydrocarbon group having 4 to 20 carbon atoms represented by R ^e, for example monofluoromethyl cyclopentyl group, difluorocyclopentyl groups, perfluorocyclopentyl group, monofluoromethyl cyclohexyl group, difluorocyclopentyl groups Perfluorocyclohexylmethyl group, fluoronorbornyl group, fluoroadamantyl group, fluorobornyl group, fluoroisobornyl group, fluorotricyclodecyl group, fluorotetracyclodecyl group and the like.

Among these, as R ^e , a fluorinated chain hydrocarbon group is preferable, and a 2,2,2-trifluoroethyl group is more preferable.

  [E] When the polymer has a structural unit (VIIa), the lower limit of the content ratio of the structural unit (VIIa) is preferably 3 mol% with respect to all the structural units constituting the polymer. 5 mol% is more preferable. As an upper limit of the said content rate, 90 mol% is preferable with respect to all the structural units which comprise a [E] polymer, 70 mol% is more preferable, and 50 mol% is further more preferable. By making the content rate of a structural unit (VIIa) into the said range, the fluorine atom content rate of a [E] polymer can be adjusted more appropriately.

[Structural unit (VIIb)]
The structural unit (VIIb) is a structural unit represented by the following formula (7b). [E] By having the structural unit (VIIb), the polymer can adjust the fluorine atom content and change water repellency and hydrophilicity before and after alkali development.

In said formula (7b), ^Rf is a hydrogen atom, a methyl group, or a trifluoromethyl group. R ⁷¹ is a (v + 1) valent hydrocarbon group having 1 to 20 carbon atoms, or an oxygen atom, a sulfur atom, —NR′—, a carbonyl group, —CO—O— at the R ⁷² side end of this hydrocarbon group. Alternatively, it has a structure in which —CO—NH— is bonded. R ′ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ⁷² is a single bond or a divalent organic group having 1 to 20 carbon atoms. W ¹ is a single bond or a divalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms. A ¹ is an oxygen atom, —NR ″ —, —CO—O— *, or —SO ₂ —O— *. R ″ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. . * Shows the site | part couple ^| bonded with R73. R ⁷³ is a hydrogen atom or a monovalent organic group having 1 to 30 carbon atoms. v is an integer of 1 to 3. However, when v is 1, R ⁷¹ may be a single bond. When v is 2 or 3, the plurality of R ⁷² , W ¹ , A ¹ and R ⁷³ may be the same or different. When W ¹ is a single bond, R ⁷³ is a group containing a fluorine atom.

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

Examples of the (v + 1) -valent hydrocarbon group having 1 to 20 carbon atoms represented by R ⁷¹ include, for example, removing v hydrogen atoms from the monovalent hydrocarbon group exemplified as R ² in the above formula (1). And the like. The v is preferably 1 or 2, and more preferably 1.

As R ⁷¹ , when v is 1, a single bond and a divalent hydrocarbon group are preferable, a single bond and an alkanediyl group are more preferable, a single bond and an alkanediyl group having 1 to 4 carbon atoms are more preferable, Single bonds, methanediyl groups and propanediyl groups are particularly preferred.

Monovalent organic Examples of the divalent organic group having 1 to 20 carbon atoms represented by ^{R 72,} for example, the formula (1-1) to (2-4) carbon atoms exemplified as L in 20 Examples include a group obtained by removing one hydrogen atom from a group.

R ⁷² is preferably a group having a single bond and a lactone structure, more preferably a group having a single bond and a polycyclic lactone structure, and more preferably a group having a single bond and a norbornane lactone structure.

Examples of the divalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms represented by W ¹ include a fluoromethanediyl group, a difluoromethanediyl group, a fluoroethanediyl group, a difluoroethanediyl group, and a tetrafluoroethanediyl group. Fluorinated alkanediyl groups such as a group, hexafluoropropanediyl group, octafluorobutanediyl group;
Examples thereof include fluorinated alkenediyl groups such as a fluoroethenediyl group and a difluoroethenediyl group.
Among these, a fluorinated alkanediyl group is preferable, and a difluoromethanediyl group is more preferable.

As the ^{A 1,} an oxygen atom, -CO-O- * and _-SO 2 -O- * are preferred, -CO-O- * is more preferable.

Examples of the monovalent organic group having 1 to 30 carbon atoms represented by R ⁷³ include an alkali dissociable group, an acid dissociable group, and a hydrocarbon group having 1 to 30 carbon atoms. Of these, R ⁷³ is preferably an alkali dissociable group. By using R ⁷³ as an alkali dissociable group, the resist film surface can be effectively changed from hydrophobic to hydrophilic during alkali development, and the development defect suppression of the radiation-sensitive resin composition is further improved. improves.

When R ⁷³ is an alkali-dissociable group, R ⁷³ is preferably a group represented by the following formulas (iii) to (v) (hereinafter also referred to as “groups (iii) to (v)”). .

In the above formula (iii), R ^3a and R ^3b are each independently a monovalent organic group having 1 to 20 carbon atoms, or these groups are combined with each other and formed together with the carbon atom to which they are bonded. Represents an alicyclic structure having 3 to 20 ring members.

In the above formula (iv), R ^3c and R ^3d are each independently a monovalent organic group having 1 to 20 carbon atoms, or these groups are combined with each other to form a nitrogen atom to which they are bonded. Represents a heterocyclic structure having 3 to 20 ring members.

In said formula (v), R ^<3e> is a C1-C20 monovalent hydrocarbon group or a C1-C20 monovalent fluorinated hydrocarbon group.

As the monovalent organic group having 1 to 20 carbon atoms represented by R ^3a , R ^3b , R ^3c and R ^3d and the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^3e , Examples thereof include the same groups as the monovalent hydrocarbon group exemplified as R ^{2 in the} above formula (1).

Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by R ^3e include a part of hydrogen atoms included in the group exemplified as the monovalent hydrocarbon group having 1 to 20 carbon atoms, or Examples include groups that are all substituted with fluorine atoms.

  Specifically, examples of the group (iii) include groups represented by the following formulas (iii-1) to (iii-4), and examples of the group (iv) include the following formula (iv-1). Examples of the group (v) represented by formula (v) include groups represented by the following formulas (v-1) to (v-5).

R ⁷³ is preferably a hydrogen atom, because the solubility of the [E] polymer in an alkaline developer is improved. In this case, if A ¹ is an oxygen atom and W ¹ is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group, the solubility is further improved.

  [E] When the polymer has a structural unit (VIIb), the lower limit of the content ratio of the structural unit (VIIb) is preferably 10 mol% with respect to all the structural units constituting the polymer. 20 mol% is more preferable. As an upper limit of the said content rate, 90 mol% is preferable with respect to all the structural units which comprise a [E] polymer, 85 mol% is more preferable, and 80 mol% is further more preferable. By setting it as such a content rate, the water repellency before and behind alkali development of the resist film surface formed from the said radiation sensitive resin composition, hydrophilicity, etc. can be adjusted more appropriately.

  As a minimum of the content rate of the said structural unit (VII), 10 mol% is preferable with respect to all the structural units which comprise a [E] polymer, 20 mol% is more preferable, and 25 mol% is further more preferable. As an upper limit of the said content rate, 90 mol% is preferable with respect to all the structural units which comprise a [E] polymer, 85 mol% is more preferable, and 80 mol% is further more preferable.

  [E] In addition to the structural unit (VII), the polymer preferably has a structural unit containing an acid-dissociable group from the viewpoint of improving the development defect suppression of the radiation-sensitive resin composition. Examples of the structural unit containing an acid dissociable group include the structural unit (II-1-1) in the [A] polymer.

  [E] The lower limit of the content ratio of the structural unit containing an acid dissociable group in the polymer is preferably 10 mol%, more preferably 15 mol%, based on all structural units constituting the polymer [E]. 20 mol% is more preferable. As an upper limit of the content rate of the said structural unit, 85 mol% is preferable with respect to all the structural units which comprise a [E] polymer, 80 mol% is more preferable, and 75 mol% is further more preferable. [E] By making the content rate of the structural unit containing an acid dissociable group in a polymer into the said range, the development defect inhibitory property of the said radiation sensitive resin composition can further be improved.

  When the said radiation sensitive resin composition contains a [E] polymer, as a minimum of content of a [E] polymer, 0.1 mass part is preferable with respect to 100 mass parts of [A] polymers. 0.2 parts by mass is more preferable, 0.5 parts by mass is further preferable, and 1 part by mass is particularly preferable. [E] The upper limit of the content of the polymer is preferably 30 parts by mass, more preferably 20 parts by mass, further preferably 15 parts by mass, and particularly preferably 10 parts by mass with respect to 100 parts by mass of the polymer [A]. preferable.

  The [E] polymer can be synthesized by the same method as the above-described [A] polymer.

  [E] As a minimum of Mw of a polymer, 1,000 is preferred, 2,000 is more preferred, 2,500 is still more preferred, and 3,000 is especially preferred. The upper limit of Mw is preferably 50,000, more preferably 30,000, still more preferably 20,000, and particularly preferably 15,000. [E] By making Mw of a polymer into the said range, the applicability | paintability and development defect inhibitory property of the said radiation sensitive resin composition improve.

  [E] The lower limit of the ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC of the polymer is usually 1, and 1.1 is preferable. The upper limit of Mw / Mn is usually 5, preferably 3 and more preferably 2.

<[F] Localization promoter>
The [F] uneven distribution accelerator is more effective when the radiation sensitive resin composition contains a water repellent polymer additive such as a [F] polymer. It has the effect of segregating on the resist film surface. By adding the [F] uneven distribution accelerator to the radiation-sensitive resin composition, the amount of the water-repellent polymer additive added can be made smaller than before. Therefore, it is possible to further suppress the elution of components from the resist film to the immersion liquid without impairing the LWR performance, etc., and to perform immersion exposure at a higher speed by high-speed scanning, resulting in a watermark defect or the like. It is possible to improve the hydrophobicity of the resist film surface that suppresses immersion-derived defects. Examples of such [F] uneven distribution promoters include low molecular compounds having a relative dielectric constant of 30 to 200 and a boiling point of 100 ° C. at 1 atm. Specific examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, and polyhydric alcohols.

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

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

  Examples of the nitrile compound include succinonitrile.

  Examples of the polyhydric alcohol include glycerin.

  When the said radiation sensitive resin composition contains [F] uneven distribution accelerator, as a minimum of content of [F] uneven distribution accelerator, it is 10 mass parts with respect to 100 mass parts of [A] polymers. Is more preferable, 15 parts by mass is more preferable, 20 parts by mass is further preferable, and 25 parts by mass is particularly preferable. As an upper limit of content of the said [F] uneven distribution promoter, 500 mass parts is preferable with respect to 100 mass parts of [A] polymers, 300 mass parts is more preferable, 200 mass parts is further more preferable, 100 mass Part is particularly preferred.

<Other optional components>
The said radiation sensitive resin composition may contain other arbitrary components other than the said [A]-[F] component. Examples of the other optional components include surfactants, alicyclic skeleton-containing compounds, and sensitizers. Each of these other optional components may be used alone or in combination of two or more.

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

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

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

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

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

<Method for preparing radiation-sensitive resin composition>
The radiation sensitive resin composition includes, for example, [A] polymer, [B] acid generator, [C] solvent, [D] acid diffusion controller, [E] polymer, and [F] uneven distribution as necessary. It can be prepared by mixing the crystallization accelerator and other intentional components in a predetermined ratio, and preferably filtering through a membrane filter having a pore diameter of about 0.2 μm. As a minimum of solid content concentration of the radiation sensitive resin composition, 0.1 mass% is preferred, 0.5 mass% is more preferred, 1 mass% is still more preferred, and 1.5 mass% is especially preferred. The upper limit of the solid content concentration of the radiation-sensitive resin composition is preferably 50% by mass, more preferably 30% by mass, still more preferably 20% by mass, and particularly preferably 10% by mass. The “solid content concentration of the radiation-sensitive resin composition” refers to the mass% of the sum of components other than the solvent with respect to the sum of all components.

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

  According to the resist pattern forming method, since the radiation sensitive resin composition described above is used, the resist having excellent depth of focus, MEEF performance, LWR performance, resolution, rectangular cross-sectional shape, and film shrinkage suppression A pattern can be formed. Hereinafter, each step of the resist pattern forming method will be described.

[Resist film forming step]
In this step, a resist film is formed from the radiation sensitive resin composition. Examples of the substrate on which the resist film is formed include conventionally known ones such as a silicon wafer, silicon dioxide, and a wafer coated with aluminum. Further, for example, an organic or inorganic antireflection film disclosed in Japanese Patent Publication No. 6-12452, Japanese Patent Application Laid-Open No. 59-93448, or the like may be formed on the substrate. Examples of the coating method include spin coating (spin coating), cast coating, and roll coating. After application, pre-baking (PB) may be performed as needed to volatilize the solvent in the coating film. As a minimum of PB temperature, it is usually 60 ° C and 80 ° C is preferred. As an upper limit of PB temperature, it is 140 degreeC normally and 120 degreeC is preferable. The lower limit of the PB time is usually 5 seconds, and preferably 10 seconds. The upper limit of the PB time is usually 600 seconds, and preferably 300 seconds. As a minimum of the film thickness of the resist film formed, 10 nm is preferable and 20 nm is more preferable. The upper limit of the thickness of the resist film is preferably 1,000 nm and more preferably 500 nm.

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

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

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

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

  As the developer used for the development, in the case of alkali development, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n -Propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, Examples include alkaline aqueous solutions in which at least one alkaline compound such as 1,5-diazabicyclo- [4.3.0] -5-nonene is dissolved. Among these, a TMAH aqueous solution is preferable.

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

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

  Examples Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, each measurement in an Example and a comparative example was performed with the following method.

[Weight average molecular weight (Mw) and number average molecular weight (Mn)]
Using GPC columns (Toso's “G2000HXL”, “G3000HXL”, “G4000HXL”), flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, sample concentration: 1.0% by mass, Sample injection amount: 100 μL, column temperature: 40 ° C., detector: measured by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard under the analysis conditions of a differential refractometer. The degree of dispersion (Mw / Mn) was calculated from the measurement results of Mw and Mn.

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

<Synthesis of compounds>
[Synthesis Example 1] (Synthesis of Compound (M-1))
In a 500 mL round bottom flask, 10.8 g (110 mmol) of α-methylene-γ-butyrolactone, 20.0 g (121 mmol) of a compound represented by the following formula (m-1), 20.0 g (145 mmol) of potassium carbonate and dimethylformamide 200 g was added and stirred with heating at 60 ° C. for 10 hours. After cooling to room temperature, insolubles were removed by Celite filtration, and the solvent was distilled off. After dissolving in dichloromethane, washing with water was performed twice. By drying over anhydrous sodium sulfate and distilling off the solvent, 23.3 g (crude yield 81%) of a crude product represented by the following formula (m-2) was obtained. Note that this was used in the next reaction without further purification.

  To a 500 mL round bottom flask, 23.3 g of a crude product represented by the following formula (m-2) and 200 g of dimethylformamide were added, and the mixture was heated and stirred at 120 ° C. for 8 hours. After distilling off the solvent, the residue was purified by column chromatography to obtain 14.8 g of a compound represented by the following formula (M-1) (two-stage total yield 69%).

[Synthesis Examples 2 to 19] (Synthesis of Compounds (M-2) to (M-19))
By appropriately selecting a precursor and performing the same operation as in Synthesis Example 1, compounds represented by the following formulas (M-2) to (M-19) were synthesized.

<Synthesis of polymer>
The monomers used in the synthesis of the [A] polymer and [E] polymer other than the synthesized compounds (m-1) to (m-19) are shown below.

[[A] Synthesis of polymer]
[Synthesis Example 20] (Synthesis of [A] polymer (A-1))
9.50 g (50 mmol) of the above compound (M′-2), 8.61 g (40 mmol) of the above compound (M′-1), and 1.89 g (10 mmol) of the above compound (M-1) are dissolved in 40 g of 2-butanone. Then, 0.79 g of AIBN (5 mmol with respect to the total amount of monomers) as a radical polymerization initiator was added to prepare a monomer solution. Next, a 100 mL three-necked flask containing 20 g of 2-butanone was purged with nitrogen for 30 minutes, and then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled with water and cooled to 30 ° C. or lower. The polymerization solution cooled in 400 g of methanol was added, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 80 g of methanol, filtered, and dried at 50 ° C. for 17 hours to synthesize a white powdery polymer (A-1) (15.7 g, yield 79). %). Mw of the polymer (A-1) was 7,300, and Mw / Mn was 1.54. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from (M′-2), (M′-1), and (M-1) was 50.1 mol% and 40.2 mol%, respectively. 9.7 mol%.

[Synthesis Example 58] (Synthesis of Polymer (A-39))
45.27 g (50 mmol) of the compound (M′-3), 43.83 g (40 mmol) of the compound (M′-2), 10.90 g (10 mmol) of the compound (M-1), and a radical polymerization initiator. After 4.58 g of AIBN (5 mmol with respect to the total amount of monomers) and 1.14 g of t-dodecyl mercaptan were dissolved in 100 g of propylene glycol monomethyl ether, the reaction temperature was maintained at 70 ° C. under a nitrogen atmosphere, Polymerized. After completion of the polymerization reaction, the polymer solution was dropped into 1,000 g of n-hexane to solidify and purify the polymer. Next, 150 g of propylene glycol monomethyl ether was added to the polymer again, and then 150 g of methanol, 34 g of triethylamine and 6 g of water were further added, and a hydrolysis reaction was performed for 8 hours while refluxing at the boiling point. After completion of the reaction, the solvent and triethylamine were distilled off under reduced pressure, and the resulting polymer was dissolved in 150 g of acetone, then dropped into 2,000 g of water to solidify, and the resulting white powder was filtered and filtered at 50 ° C. It was made to dry for a time and the white powdery polymer (A-39) was obtained (62.1g, 70% of yield). Mw of the polymer (A-39) was 7,200, and Mw / Mn was 1.88. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from p-hydroxystyrene, (M′-2) and (M-1) was 50.2 mol%, 40.1 mol% and 9 respectively. 0.7 mol%.

[Synthesis Examples 21 to 57, 59 and 60] (Synthesis of Polymers (A-2) to (A-38) and Polymers (CA-1) and (CA-2))
Polymers (A-2) to (A-38), (CA-1) in the same manner as in Synthesis Example 20 except that the components of the types and contents shown in Table 1, Table 2 or Table 3 below were used. And (CA-2) were synthesized. In Tables 2 and 3, “-” indicates that the corresponding component was not used.

[[E] Synthesis of polymer]
[Synthesis Example 61] (Synthesis of Polymer (E-1))
71.67 g (70 mmol) of the above compound (M′-12) and 28.33 g (30 mmol) of the above compound (M′-13) were dissolved in 100 g of 2-butanone, and dimethyl 2,2 as a radical polymerization initiator was dissolved. A monomer solution was prepared by dissolving 6.47 g of '-azobisisobutyrate (5 mmol with respect to the total amount of monomers). Next, a 1,000 mL three-necked flask containing 100 g of 2-butanone was purged with nitrogen for 30 minutes, and then heated to 80 ° C. with stirring, and the monomer solution prepared above was added dropwise over 3 hours using a dropping funnel. . The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled with water and cooled to 30 ° C. or lower. The reaction solution was transferred to a 2 L separatory funnel, and then the polymerization solution was uniformly diluted with 150 g of n-hexane, and 600 g of methanol was added and mixed. Next, 30 g of distilled water was added, and the mixture was further stirred and allowed to stand for 30 minutes. Thereafter, the lower layer was recovered to obtain a propylene glycol monomethyl ether acetate solution containing the polymer (E-1) as a solid content (yield 60%). Mw of the polymer (E-1) was 7,200, and Mw / Mn was 2.00. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from (M′-12) was 71.1 mol% and 28.9 mol%, respectively.

<Preparation of radiation-sensitive resin composition>
The [B] acid generator, [D] acid diffusion controller, [C] solvent and [F] uneven distribution accelerator used for the preparation of the radiation sensitive resin composition are shown below.

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

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

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

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

[Preparation of radiation-sensitive resin composition for ArF exposure]
[Example 1]
[A] 100 parts by mass of (A-1) as a polymer, [B] 8.5 parts by mass of (B-1) as an acid generator, [D] (D-1) 2 as an acid diffusion controller 3 parts by weight, (E-1) 3 parts by weight as a polymer, (C-1) 2,240 parts by weight and (E-2) 960 parts by weight as a solvent, and [F] The radiation sensitive resin composition (J-1) was prepared by blending 30 parts by mass of (F-1) as an uneven distribution promoter and filtering the resulting blend through a membrane filter having a pore size of 0.2 μm. did.

[Examples 2 to 42 and Comparative Examples 1 and 2]
Each radiation-sensitive resin composition was prepared in the same manner as in Example 1 except that the components of the types and blending amounts shown in Table 4, Table 5 or Table 6 were used.

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

<Formation of resist pattern (2)>
A negative resist pattern was prepared in the same manner as in the above resist pattern formation (1) except that n-butyl acetate was used instead of the TMAH aqueous solution and the organic solvent was developed, and washing with water was not performed. Formed.

<Evaluation>
Each radiation-sensitive resin composition was evaluated by measuring the formed resist pattern according to the following method. The evaluation results are shown in Table 7 below. A scanning electron microscope (Hitachi High-Technologies “CG-4100”) was used for measuring the resist pattern.

[LWR performance]
The resist pattern was observed from above the pattern using the scanning electron microscope. A total of 50 line widths were measured at arbitrary points, and a 3-sigma value was obtained from the distribution of the measured values, and this was defined as LWR performance (nm). The LWR performance can be evaluated as “good” when the thickness is 4.2 nm or less and “bad” when the thickness exceeds 4.2 nm.

[Resolution]
The dimension of the minimum resist pattern that can be resolved at the optimum exposure dose is measured, and the measurement result is defined as resolution (nm). The measured value can be evaluated as “good” when it is 33 nm or less, and “bad” when it exceeds 33 nm.

[Rectangularity of the cross-sectional shape]
Observe the cross-sectional shape of the resist pattern resolved at the optimum exposure amount, measure the line width Lb in the middle of the resist pattern and the line width La at the top of the film, calculate La / Lb, and calculate the cross-sectional rectangle It was used as an index of sex. The rectangularity of the cross-sectional shape can be evaluated as “good” when 0.9 ≦ La / Lb ≦ 1.1, and “bad” when outside the above range.

[Depth of focus]
In the resist pattern resolved at the above optimum exposure amount, the dimension when the focus is changed in the depth direction is observed, and the depth direction in which the pattern dimension falls within 90% to 110% of the standard without any bridge or residue. Was measured, and the measurement result was defined as the depth of focus (nm). When the depth of focus is 25 nm or less, it can be evaluated as “good”, and when it exceeds 25 nm, it can be evaluated as “bad”.

[MEEF performance]
Above, the resist pattern resolved with five types of mask sizes (38.0 nmLine / 80 nmPitch, 39.0 nmLine / 80 nmPitch, 40.0 nmLine / 80 nmPitch, 41.0 nmLine / 80 nmPitch, 42.0 nmLine / 80 nmPitch) at the above optimum exposure dose. The line width of was measured. The obtained measurement values were plotted with the horizontal axis as the mask size and the vertical axis as the line width formed with each mask size, and the slope of the approximate straight line calculated by the least square method was obtained, and this slope was defined as MEEF performance. The MEEF performance can be evaluated as “good” when it is 5.5 nm or less, and “bad” when it exceeds 5.5 nm.

[Membrane shrinkage suppression]
A 12-inch silicon wafer surface was coated with a composition for forming a lower antireflection film (“ARC66” from Brewer Science Co., Ltd.) using a spin coater (“CLEAN TRACK ACT12” from Tokyo Electron), and then 205 ° C. Was heated for 60 seconds to form a lower antireflection film having a thickness of 105 nm. On the lower antireflection film, each of the prepared radiation sensitive resin compositions was applied using the spin coater, and PB was performed at 90 ° C. for 60 seconds. Then, it cooled at 23 degreeC for 30 second, and formed the resist film with an average film thickness of 90 nm. Next, this resist film was exposed at 70 mJ on the entire surface using an ArF excimer laser immersion exposure apparatus (“NSR-S610C” manufactured by NIKON), and then the film thickness was measured to obtain the average film thickness A. Subsequently, after carrying out PEB at 90 ° C. for 60 seconds, the film thickness was measured again to obtain the average film thickness B. At this time, 100 * (AB) / A (%) was calculated | required and this was made into the film contraction rate by PEB. The results are shown in Table 8 below. The film shrinkage inhibiting property can be evaluated as “good” when it is 20% or less, and “bad” when it exceeds 20%.

[Preparation of radiation-sensitive resin composition for electron beam exposure]
[Example 43]
[A] 100 parts by mass of (A-1) as a polymer, [B] 20 parts by mass of (B-1) as an acid generator, [D] (D-1) 3.6 as an acid diffusion controller (E-1) 4280 parts by mass and (E-2) 1830 parts by mass as a [C] solvent are blended, and the mixture is filtered through a membrane filter having a pore size of 0.2 μm to give a radiation-sensitive resin composition (J -43) was prepared.

[Examples 44 to 46 and Comparative Examples 3 and 4]
Each radiation-sensitive resin composition was prepared in the same manner as in Example 43 except that the components of the types and blending amounts shown in Table 9 below were used.

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

<Formation of resist pattern (4)>
A negative resist pattern was prepared in the same manner as in the above resist pattern formation (3) except that n-butyl acetate was used instead of the TMAH aqueous solution and the organic solvent was developed. Formed.

<Evaluation>
About the resist pattern formed using each said radiation sensitive resin composition, evaluation similar to the said Examples 1-42 was implemented. The results are shown in Table 10 below. In this case, the LWR performance can be evaluated as “good” when it is 5 nm or less and “bad” when it exceeds 5 nm.

  As can be seen from the results of Table 8, Table 9, and Table 10, according to the radiation-sensitive resin compositions of the examples, both in ArF exposure and electron beam exposure, and in any of alkaline solvents and organic solvents. It is excellent in depth of focus, MEEF performance, LWR performance, resolution, rectangular shape of a cross-sectional shape, and film shrinkage suppression (hereinafter also referred to as “lithography performance”). It is known that there is a correlation between the performance of the resist pattern obtained between electron beam exposure and EUV exposure. Therefore, it is presumed that the radiation-sensitive resin compositions of the examples exhibit excellent lithography performance even in EUV exposure.

  According to the radiation sensitive resin composition of the present invention, the [A] polymer has an appropriate rigidity due to the specific structure, so that the focal depth, the MEEF performance, the LWR performance, the resolution, and the cross-sectional rectangle are rectangular. It is possible to form a resist pattern having excellent properties and film shrinkage suppression properties. Accordingly, these can be suitably used for manufacturing semiconductor devices that are expected to be further miniaturized in the future.

Claims (8)

A polymer having a first structural unit represented by the following formula (1) and a second structural unit represented by the following formula (2);
Containing a radiation sensitive acid generator, and a solvent,
The polymer has a maleimide structural unit represented by the following formula (1-1) as the first structural unit,
The radiation sensitive resin composition whose content rate of the said 1st structural unit in the said polymer is 50 mol% or less, and whose content rate of the said maleimide structural unit in the said polymer is 4 mol% or more.

(In formula (1), R ¹¹ and R ¹² are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ¹³ is a divalent organic group having 1 to 40 carbon atoms. A ring structure having 3 to 40 ring members together with two carbon atoms bonded to R ¹³ .
In Formula (2), R ²¹ , R ²² , R ²³ and R ²⁴ are each independently a hydrogen atom, a fluorine atom or a monovalent organic group having 1 to 40 carbon atoms.
In formula (1-1), A represents a single bond or a divalent organic group having 1 to 20 carbon atoms. L is a monovalent cyclic organic group having 4 or more ring members, which may have one or more groups selected from —CO—, —O—, and —SO ₂ — in the ring. )   The radiation sensitive resin composition according to claim 1, wherein A in the formula (1-1) is a single bond or a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms. A in the above formula (1-1) is a single bond or —CR ¹⁴ R ¹⁵ —, and R ¹⁴ and R ¹⁵ are each independently a hydrogen atom or a monovalent organic group having 1 to 19 carbon atoms. The radiation sensitive resin composition of Claim 1 or Claim 2.   The radiation sensitive resin composition according to claim 1, wherein A in the formula (1-1) is an organic group, and the organic group contains a carbonyl group.   The radiation sensitive resin composition according to any one of claims 1 to 4, wherein a content ratio of the maleimide structural unit in the first structural unit is 20 mol% or more.   The radiation sensitive resin composition according to any one of claims 1 to 5, wherein the second structural unit includes an acid dissociable group. The radiation sensitive resin composition according to any one of claims 1 to 6, wherein the second structural unit is represented by the following formula (2-1) or (2-2).

(In formula (2-1), R ³¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ³² is a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms.
In formula (2-2), R ⁴¹ represents a hydrogen atom or a methyl group. X is a hydroxy group, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms. n is an integer of 0-5. When n is 2 or more, the plurality of Xs may be the same or different. ) Forming a resist film;
A step of exposing the resist film, and a step of developing the exposed resist film,
The resist pattern formation method which forms the said resist film with the radiation sensitive resin composition of any one of Claims 1-7.