JP5742563B2 - Photoresist composition and resist pattern forming method - Google Patents

Description

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

  The photoresist composition generates acid in the exposed area by exposure to deep ultraviolet rays such as ArF excimer laser, electron beam, etc., and the dissolution rate of the exposed area and unexposed area in the developer by the reaction using this acid as a catalyst. And a resist pattern is formed on the substrate (see Japanese Patent Application Laid-Open No. 59-45439).

  Such a photoresist composition is required to have a large process margin such as depth of focus and exposure margin in order to ensure the stability of the resist pattern formation process. At the same time, with a single photoresist composition, for example, various patterns with different shapes such as pitches such as dense patterns and isolated patterns, line patterns, hole patterns, trench patterns, etc., and mixed patterns can be accurately A wide range of applications, such as being able to be formed, is also required.

  However, the depth of focus varies depending on the pitch, size, shape, and the like of the resist pattern to be formed due to optical factors and the like. Therefore, in the case of forming a dense pattern and an isolated pattern at the same time in the conventional photoresist composition, it is difficult to set both the depth of focus to a high level. As a result, various patterns can be formed while ensuring process stability. There is an inconvenience that it is difficult to apply to the above. In particular, when an isolated trench pattern is formed, the resist pattern to be formed has a trailing shape mainly due to a decrease in depth of focus and exposure margin due to optical factors, and the bottom of the pattern. In addition, there is a disadvantage that a good cross-sectional shape cannot be obtained due to the generation of residues.

See JP-A-59-45439

  The present invention has been made based on such a situation, and an object of the present invention is to provide a resist pattern that can achieve a high depth of focus in both dense and isolated trench pattern formation and that has a good cross-sectional shape. It is to provide a photoresist composition that can be formed.

（式（１）中、Ｒ^１、Ｒ^２及びＲ^３は、それぞれ独立して、炭素数１〜２０のアルキル基又は炭素数３〜２０の１価の脂環式炭化水素基である。但し、Ｒ^１とＲ^２とが互いに結合して、これらが結合している硫黄原子と共に環構造を形成していてもよい。Ｘは、単結合又は酸素原子である。ａは、０〜７の整数である。但し、Ｒ^３及びＸがそれぞれ複数の場合、複数のＲ^３及びＸはそれぞれ同一でも異なっていてもよい。ｂは、０又は１である。） The invention made to solve the above problems is
[A] a polymer having a structural unit (I) containing an acid dissociable group (hereinafter, also referred to as “[A] polymer”), and [B] a cation represented by the following formula (1) (hereinafter, “ Acid generator (hereinafter referred to as “[B] acid generator”) and an anion having an alicyclic structure having 6 to 15 carbon atoms (hereinafter also referred to as “anion (B)”). Is also called)
Is a photoresist composition containing

(In formula (1), R ¹ , R ² and R ³ are each independently an alkyl group having 1 to 20 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. , R ¹ and R ² may be bonded to each other to form a ring structure together with the sulfur atom to which they are bonded, X is a single bond or an oxygen atom, and a is 0-7. (However, when there are a plurality of R ³ and X, respectively, the plurality of R ³ and X may be the same or different. B is 0 or 1.)

  Since the photoresist composition contains the [A] polymer and the [B] acid generator, the depth of focus in forming both dense and isolated trench patterns can be increased to a high level, and the cross-sectional shape can be increased. A good resist pattern can be formed. Although it is not necessarily clear why the photoresist composition has the above-described configuration, the above-described effect can be exhibited. For example, the anion of [B] an acid generator is an anion (B) having a bulky alicyclic structure. In addition to the appropriate diffusion length of the acid generated by this, it is considered that the cation (B) is used as the cation to increase the permeability of the [B] acid generator to exposure light. In addition, [B] the generation of residues in the step of the trench pattern and the like is suppressed due to the appropriate diffusion length of the acid generated from the acid generator and the increased permeability to exposure light, and as a result. As a result, it is considered that the cross-sectional shape of the formed resist pattern is improved.

（式（１−１）中、Ｒ^３、Ｘ、ａ及びｂは、上記式（１）と同義である。） The cation represented by the above formula (1) is preferably represented by the following formula (1-1).

(In formula (1-1), R ³ , X, a and b have the same meanings as in formula (1) above).

  [B] Since the acid generator cation has the above specific structure, the exposure light transmittance of the [B] acid generator can be appropriately increased. As a result, in both dense and isolated trench pattern formation, The depth of focus can be increased to a higher level, and a resist pattern with a better cross-sectional shape can be formed.

（式（２）中、Ｒ^４は、炭素数６〜１５の脂環構造を有する１価の基である。Ｙは、ヘテロ原子を含む２価の連結基である。Ｒ^５は、炭素数１〜２０の２価の炭化水素基である。Ｒ^ｆ１及びＲ^ｆ２は、それぞれ独立して、水素原子、フッ素原子、炭素数１〜３０のアルキル基又は炭素数１〜３０のフッ素化アルキル基である。ｍは、１〜３の整数である。ｎは、０〜５の整数である。但し、Ｒ^４、Ｙ、Ｒ^５、Ｒ^ｆ１及びＲ^ｆ２がそれぞれ複数の場合、複数のＲ^４、Ｙ、Ｒ^５、Ｒ^ｆ１及びＲ^ｆ２はそれぞれ同一でも異なっていてもよい。） The anion is preferably represented by the following formula (2).

(In Formula (2), R ⁴ is a monovalent group having an alicyclic structure having 6 to 15 carbon atoms. Y is a divalent linking group containing a hetero atom. R ⁵ is a carbon number. R 2 is a divalent hydrocarbon group having 1 to ^20. R ^f1 and R ^f2 each independently represent a hydrogen atom, a fluorine atom, an alkyl group having 1 to 30 carbon atoms, or a fluorinated alkyl group having 1 to 30 carbon atoms. M is an integer of 1 to 3. n is an integer of 0 to ^5. However, when R ⁴ , Y, R ⁵ , R ^f1, and R ^f2 are plural, plural R ⁴ , Y, R ⁵ , R ^f1 and R ^f2 may be the same or different.

  [B] It is thought that the acid generated by exposure becomes more bulky and the acid diffusion length becomes more appropriate because the anion of the acid generator has the above specific structure, and as a result, both dense and isolated trench patterns Both the depth of focus in formation can be made higher and a resist pattern with a better cross-sectional shape can be formed.

  The anion preferably has at least one structure selected from the group consisting of an adamantane structure and a norbornane structure. [B] It is considered that the acid generated by the anion of the acid generator has the above-mentioned specific structure, so that the generated acid is further bulked. As a result, the depth of focus in both dense and isolated trench pattern formation is further increased. And a resist pattern having a better cross-sectional shape can be formed.

  [A] The polymer preferably further has a structural unit (II) containing a polar group. [A] It is considered that the polymer further has the structural unit (II), thereby improving the adhesion to the base. [B] Combined with the effects of the above-mentioned properties of the acid generator, as a result, the dense and isolated Both depths of focus in forming both trench patterns can be set to a higher level, and a resist pattern having a better cross-sectional shape can be formed.

（式（３）中、Ｒ^６、Ｒ^７及びＲ^８は、それぞれ独立して、ヒドロキシル基、ハロゲン原子、アルキル基、１価の脂環式炭化水素基、アルコキシ基、−Ｓ−Ｒ^Ａ、−ＯＳＯ_２−Ｒ^Ｂ又は−ＳＯ_２−Ｒ^Ｃである。Ｒ^Ａ、Ｒ^Ｂ及びＲ^Ｃは、それぞれ独立して、アルキル基、１価の脂環式炭化水素基、アルコキシ基、アリール基又はアラルキル基である。但し、Ｒ^６、Ｒ^７、Ｒ^８、Ｒ^Ａ、Ｒ^Ｂ及びＲ^Ｃにおけるアルキル基、１価の脂環式炭化水素基、アルコキシ基、アリール基及びアラルキル基の水素原子の一部又は全部は置換されていてもよい。ｐ、ｑ及びｒは、それぞれ独立して、０〜５の整数である。Ｒ^６、Ｒ^７及びＲ^８がそれぞれ複数の場合、複数のＲ^６、Ｒ^７及びＲ^８はそれぞれ同一でも異なっていてもよい。） [C] A cation represented by the following formula (3) (hereinafter also referred to as “cation (C)”) and an anion having an alicyclic structure having 6 to 15 carbon atoms (hereinafter also referred to as “anion (C)”). ) And an acid generator (hereinafter also referred to as “[C] acid generator”)
It is preferable to further contain.

(In Formula (3), R < ⁶ >, R < ⁷ > and R < ⁸ > are respectively independently a hydroxyl group, a halogen atom, an alkyl group, a monovalent alicyclic hydrocarbon group, an alkoxy group, -S-R ^<A> , -OSO ₂ -R ^B or _-SO 2 -R ^C a is ^.R a, ^{R B} and ^{R C} are each independently an alkyl group, a monovalent alicyclic hydrocarbon group, an alkoxy group, an aryl group, or An aralkyl group, provided that an alkyl group, a monovalent alicyclic hydrocarbon group, an alkoxy group, an aryl group and an aralkyl group in R ⁶ , R ⁷ , R ⁸ , R ^A , R ^B and R ^C A part or all of them may be substituted, and p, q and r are each independently an integer of 0 to 5. When R ⁶ , R ⁷ and R ⁸ are plural, plural R ⁶ , R ⁷ and R ⁸ may be the same or different.

  In addition to the [B] acid generator, the photoresist composition can further improve the focal depth in both dense and isolated trench patterns in a more balanced manner by further including a [C] acid generator.

The resist pattern forming method of the present invention comprises:
(1) A step of applying the photoresist composition on a substrate to form a resist film;
(2) a step of exposing the resist film through a photomask; and (3) a step of developing the exposed resist film.

  According to the resist pattern forming method, since the photoresist composition having the above performance is used, a pattern can be formed with a wide depth of focus in both dense and isolated trench pattern formation, and a cross-sectional shape. Can form a good resist pattern.

  Therefore, the resist pattern forming method is suitable for forming a trench pattern, and can form a resist pattern with a wide focal depth in both dense and isolated trench pattern formation.

  As described above, according to the photoresist composition and the resist pattern forming method of the present invention, the depth of focus in forming both dense and isolated trench patterns can be set to a high level, and the resist having a good cross-sectional shape. A pattern can be formed.

<Photoresist composition>
The photoresist composition of the present invention contains a [A] polymer and a [B] acid generator. Moreover, the said photoresist composition may contain a [C] acid generator and a [D] acid diffusion control agent as a suitable component. Furthermore, the said photoresist composition may contain other arbitrary components, such as a [E] fluorine-containing atom containing polymer, in the range which does not impair the effect of this invention. Hereinafter, each component will be described.

<[A] polymer>
[A] A polymer is a polymer which has structural unit (I) containing an acid dissociable group. In the photoresist composition, the acid dissociable group in the structural unit (I) is dissociated by the action of an acid generated from the acid generator [B] described later, whereby the polymer [A] is converted into an alkaline developer. A resist pattern can be formed by becoming soluble. The “acid-dissociable group” refers to a group that replaces a hydrogen atom of a polar group such as a carboxyl group or a hydroxyl group, and dissociates in the presence of an acid.

  [A] The polymer has, in addition to the structural unit (I), a structural unit (III) having at least one group selected from the group consisting of a structural unit (II) containing a polar group, a lactone group and a cyclic carbonate group. Etc. are preferable. [A] The polymer may have one or two or more of these structural units.

[Structural unit (I)]
The structural unit (I) is a structural unit containing an acid dissociable group. The structural unit (I) is not particularly limited as long as it contains an acid dissociable group, and examples thereof include a structural unit (I-1) represented by the following formula (4).

In said formula (4), ^Ra is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ^p is an acid dissociable group represented by the following formula (i).

In said formula (i), R ^<p1> , R ^<p2> and R ^<p3> are respectively independently a C1-C4 alkyl group or a C4-C20 monovalent alicyclic hydrocarbon group. However, R ^p2 and R ^p3 may be bonded to each other to form a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms together with the carbon atom to which they are bonded.

The R ^a, from the viewpoint of copolymerizability of the monomer giving the structural units (I), a methyl group is preferred.

Examples of the alkyl group having 1 to 4 carbon atoms represented by R ^p1 , R ^p2 and R ^p3 include, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl. Group, sec-butyl group, t-butyl group and the like. Among these, a methyl group, an ethyl group, and an i-propyl group are preferable, and a methyl group is more preferable.

Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by R ^p1 , R ^p2 and R ^p3 include a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and the like. A monocyclic alicyclic hydrocarbon group; a polycyclic alicyclic hydrocarbon group such as a norbornyl group, an adamantyl group, a tricyclodecanyl group, and a tetracyclododecanyl group. Among these, a cyclopentyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group are preferable, and a cyclohexyl group and an adamantyl group are more preferable.

Examples of the divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms that are formed together with the carbon atom to which R ^p2 and R ^p3 are bonded to each other include, for example, a cyclobutanediyl group and a cyclopentanediyl group And monocyclic alicyclic hydrocarbon groups such as cyclohexanediyl group and cyclooctanediyl group; and polycyclic alicyclic hydrocarbon groups such as norbornanediyl group and adamantanediyl group. Among these, a cyclopentanediyl group, a cyclohexanediyl group, a norbornanediyl group, and an adamantanediyl group are preferable, and a cyclopentanediyl group is more preferable.

  Examples of the structural unit (I-1) include structural units represented by the following formulas (4-1) to (4-4).

In the above formulas (4-1) to (4-4), R ^a has the same meaning as the above formula (4). R ^p1 , R ^p2 and R ^p3 are as defined in the above formula (i).

  Examples of the structural unit represented by the above formula (4) or (4-1) to (4-4) include a structural unit represented by the following formula.

In the above formula, R ^a has the same ^{meaning as} in the above formula (4).

  Among these, the structural unit represented by the above formula (4-1) and the structural unit represented by the above formula (4-2) are preferable, and the structural unit represented by the above formula (4-2) is more preferable. A structural unit derived from 1-methyl-cyclopentyl (meth) acrylate is more preferable.

  As a content rate of structural unit (I), 20-80 mol% is preferable with respect to all the structural units which comprise a [A] polymer, 40-70 mol% is more preferable, and 40-60 mol% is further. preferable. When the content ratio of the structural unit (I) is less than the lower limit, the pattern forming property of the photoresist composition may be deteriorated. On the contrary, when the content ratio of the structural unit (I) exceeds the above upper limit, the adhesion of the formed resist pattern may be lowered.

[Structural unit (II)]
The structural unit (II) is a structural unit containing a polar group. Examples of the polar group include a hydroxyl group, a cyano group, and a carboxyl group, and among these, a hydroxyl group is preferable. [A] Since the polymer further includes the structural unit (II) in addition to the structural unit (I), the adhesion with the base is considered to be improved, and as a result, the photoresist composition is dense and isolated. Both the depth of focus in forming the trench pattern can be set to a higher level.

  The structural unit (II) is not particularly limited as long as it contains a polar group. For example, the structural unit represented by the following formulas (2-1) to (2-3) (hereinafter referred to as “structural unit (II-1)”) ~ (II-3) ").

In the above formulas (2-1) to (2-3), R ^G is each independently a hydroxyl group, a cyano group, or a carboxyl group. If R ^G is plural, the plurality of R ^G may be the same or different.
In the above formulas (2-1) and (2-2), R ^b is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.
In the above formula (2-1), E is a divalent acid dissociable group. ^RD is an (i + 1) -valent alicyclic hydrocarbon group. L is a divalent hydrocarbon group. i is an integer of 1 to 3. When there are a plurality of L, the plurality of L may be the same or different.
In the above formula (2-2), R ^E is a (j + 1) -valent alicyclic hydrocarbon group. j is an integer of 1 to 3.
In the above formula (2-3), R ^c is a hydrogen atom or a methyl group. R ^F is a (k + 2) -valent group that forms a cyclic structure with the carbon atoms that make up the lactone ring. k is an integer of 1 to 3.

As ^RG , a hydroxyl group is particularly preferable.

As said ^Rb , a methyl group is preferable from the viewpoint of copolymerization of the monomer which gives the structural unit (II-1) or (II-2).

  The divalent acid dissociable group represented by E is a group in which the oxygen-carbon bond between the ester group to be bonded is cleaved by an acid. Examples of such a group include 2,2-propanediyl group, 2,2-butanediyl group, 2,3-butanediyl group and the like. Among these, 2,2-propanediyl group is preferable.

Examples of the (i + 1) -valent alicyclic hydrocarbon group represented by ^RD include, for example,
Examples of the divalent (i = 1) alicyclic hydrocarbon group include a 1,3-adamantanediyl group, a 1,2-adamantanediyl group, a 2,5-norbornanediyl group, and a 1,4-cyclohexanediyl group. And
Examples of the trivalent (i = 2) alicyclic hydrocarbon group include 1,3,5-adamantanetriyl group, 1,2,3-adamantanetriyl group, 2,3,5-norbornanetriyl group, 1 3,4-cyclohexanetriyl group and the like.
Among these, 1,3-adamantanediyl group and 1,3,5-adamantanetriyl group are preferable, and 1,3-adamantanediyl group is more preferable.

As the divalent hydrocarbon group represented by L, for example,
Alkanediyl groups such as 2,2-propanediyl group, 2,2-butanediyl group, 2,3-butanediyl group;
Examples include cycloalkanediyl groups such as 1,2-cyclopentanediyl group and 1,2-cyclohexanediyl group.
Among these, an alkanediyl group is preferable, and a 2,2-propanediyl group is more preferable.

  i is preferably 1 or 2, and more preferably 1.

Examples of the (j + 1) -valent alicyclic hydrocarbon group represented by R ^E include groups similar to those exemplified as the (i + 1) -valent alicyclic hydrocarbon group represented by R ^D above. Is mentioned.

  j is preferably 1 or 2, and more preferably 1.

R ^c is preferably a hydrogen atom from the viewpoint of the copolymerizability of the monomer giving the structural unit (II).

Examples of the cyclic structure formed by the (k + 2) -valent group represented by R ^F together with the carbon atom constituting the lactone ring include a monocyclic structure such as a cyclopentane structure and a cyclohexane structure; a norbornane structure and an adamantane structure, and the like. Examples include polycyclic structures. Among these, a cyclohexane structure and an adamantane structure are preferable, and a cyclohexane structure is more preferable.

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

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

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

  Among these, as the structural unit (II), the structural unit (II-1) and the structural unit (II-3) are preferable, and 2- (3- (2-hydroxy-2-propyl) adamantyl) -2-propyl is preferable. A structural unit derived from (meth) acrylate and a structural unit derived from 8-hydroxy-3-methylene-1-oxaspiro [4.5] decan-2-one are more preferred.

  As a content rate of structural unit (II), 30 mol% or less is preferable with respect to all the structural units which comprise a [A] polymer, 1-20 mol% is more preferable, and 2-15 mol% is further more preferable. . When the content ratio of the structural unit (II) exceeds the above upper limit, the contrast before and after the development is decreased, so that the pattern forming property of the photoresist composition may be deteriorated.

[Structural unit (III)]
The structural unit (III) is a structural unit containing at least one group selected from the group consisting of a lactone group and a cyclic carbonate group. [A] When the polymer has the structural unit (III), basic resist characteristics such as adhesion to a resist film formed from the photoresist composition can be further improved. Further, the solubility of the resist film in the developer can be increased. Here, the lactone group refers to a cyclic group containing one ring (lactone ring) including a bond represented by —O—C (O) —. Moreover, a cyclic carbonate group shows the cyclic group containing one ring (cyclic carbonate ring) containing the coupling | bonding represented by -OC (O) -O-. The lactone ring or cyclic carbonate ring is counted as the first ring, and if it has only a lactone ring or cyclic carbonate ring, it is called a monocyclic group, and if it has another ring structure, it is called a polycyclic group regardless of the structure. .

  Examples of the structural unit having a lactone group include a structural unit represented by the following formula.

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

As said R ^<L1> , a methyl group is preferable from a copolymerizable viewpoint of the monomer which gives structural unit (III).

  Among these, the structural unit (III) containing a lactone group is preferably a structural unit containing a norbornane lactone group or a structural unit containing a butyrolactone group, and a structure derived from norbornane lactonyl (meth) acrylate or butyrolactonyl (meth) acrylate. A unit is more preferable, and a structural unit derived from norbornane lactonyl (meth) acrylate is more preferable.

  Examples of the structural unit having a cyclic carbonate group include a structural unit represented by the following formula.

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

As said R ^<L1> , a methyl group is preferable from a copolymerizable viewpoint of the monomer which gives structural unit (III).

  Among these, the structural unit (III) containing a cyclic carbonate group is preferably a structural unit having an ethylene carbonate ring, and more preferably a structural unit derived from 1,2-propylene carbonate (meth) acrylate.

  As a content rate of structural unit (III), 70 mol% or less is preferable with respect to all the structural units which comprise a [A] polymer, 10-65 mol% is more preferable, and 20-60 mol% is further more preferable. . If the content ratio of the structural unit (III) exceeds the above upper limit, the pattern forming property of the photoresist composition may be deteriorated.

[Other structural units]
[A] The polymer may contain other structural units in addition to the structural units (I) to (III). Examples of the other structural unit include a structural unit containing a non-acid-dissociable alicyclic hydrocarbon group and a structural unit having a polar group other than a hydroxyl group. The content ratio of other structural units is usually 30 mol% or less, preferably 20 mol% or less, based on all the structural units constituting the [A] polymer.

  The content of the [A] polymer in the photoresist composition is usually 70% by mass or more and more preferably 75% by mass or more with respect to the total solid content. [A] If the content of the polymer is smaller than the lower limit, the pattern forming property of the photoresist composition may be lowered. In addition, the said photoresist composition may contain 1 type (s) or 2 or more types of [A] polymers.

<[A] Polymer Synthesis Method>
[A] The polymer can be synthesized, for example, by polymerizing a monomer giving each structural unit in a suitable solvent using a radical polymerization initiator.

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

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

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

  [A] The weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is not particularly limited, but is preferably 1,000 or more and 500,000 or less, more preferably 2,000 or more and 400,000 or less. Preferably, 3,000 or more and 300,000 or less are more preferable. [A] If the Mw of the polymer is less than the lower limit, the heat resistance of the resulting resist film may be reduced. Conversely, if the Mw of the [A] polymer exceeds 500,000, the developability of the resist film may be reduced.

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

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

<[B] Acid generator>
[B] The acid generator is an acid generator containing a cation (B) and an anion (B). The photoresist composition contains a [B] acid generator in addition to the [A] polymer, so that the depth of focus in both dense and isolated trench pattern formation can be increased to a high level and A resist pattern having a good shape can be formed. The reason why the photoresist composition contains the [B] acid generator is not necessarily clear, but for example, the anion of the [B] acid generator is an anion having a bulky alicyclic structure ( In addition to the appropriate diffusion length of the acid generated by B), the cation (B) is used as a cation, so that the [B] acid generator can be improved in permeability to exposure light. It is done. Further, due to the improvement of the depth of focus, it is considered that the generation of residues at the step of the trench pattern is suppressed, and as a result, the cross-sectional shape of the formed resist pattern is improved.

[Cation (B)]
The cation (B) is a cation represented by the above formula (1).

The formula ^(1), R 1, ^{R 2} and ^{R 3} are each independently a monovalent alicyclic hydrocarbon group having an alkyl group or a 3 to 20 carbon atoms having 1 to 20 carbon atoms. However, R ¹ and R ² may be bonded to each other to form a ring structure together with the sulfur atom to which they are bonded. X is a single bond or an oxygen atom. a is an integer of 0-7. However, in the case of multiple R ³ and X are each the plurality of R ³ and X may be the same as or different from each other. b is 0 or 1.

Examples of the alkyl group having 1 to 20 carbon atoms represented by R ¹ , R ² and R ³ include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group and an i-butyl group. , Sec-butyl group, t-butyl group and the like.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ¹ , R ² and R ³ include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group and the like. A monocyclic alicyclic hydrocarbon group; a polycyclic alicyclic hydrocarbon group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, and a tetracyclododecyl group;

Examples of the ring structure formed by combining R ¹ and R ² together with the sulfur atom to which they are bonded include, for example, a thiacyclopropane structure, a thiacyclobutane structure, a thiacyclopentane structure, a thiacyclohexane structure, Examples thereof include a cyclodecane structure. Among these, a thiacyclopentane structure and a thiacyclohexane structure are preferable, and a thiacyclopentane structure is more preferable.

  X is preferably a single bond when b is 0 and an oxygen atom when b is 1 from the viewpoint of increasing the depth of focus.

  a is preferably an integer of 0 to 3, more preferably 0 or 1, and still more preferably 1.

  As b, 0 is preferable from the viewpoint of achieving a higher depth of focus in both dense and isolated trench patterns. When b is 1, it is preferable that a sulfur atom is bonded to the 1-position of the naphthalene ring of the cation (B).

  Examples of the cation (B) include cations represented by the following formulas (b-1) to (b-22).

  As the cation (B), a cation represented by the above formula (1-1) is preferable. By making the cation (B) a cation represented by the above formula (1-1), it is considered that the exposure light transmittance of the [B] acid generator is improved, and as a result, formation of dense and isolated trench patterns is achieved. The depth of focus can be increased to a high level, and a resist pattern with a better cross-sectional shape can be formed.

In said formula (1-1), R < ³ >, X, a, and b are synonymous with the said formula (1).

  As the cation (B), among the above formulas (b-1) to (b-22), (b-5) to (b-8), (b-16), (b-18), (b- 19) and cations represented by (b-21) are preferred, cations represented by (b-6) and cations represented by (b-16) are more preferred, represented by (b-8). More preferred are cations.

[Anion (B)]
The anion (B) is an anion having an alicyclic structure having 6 to 15 carbon atoms. A C6-C15 alicyclic structure means the structure containing the carbon skeleton which a C6-C15 alicyclic hydrocarbon has.

  Examples of the alicyclic structure having 6 to 15 carbon atoms of the anion include a cyclohexane structure, a cycloheptane structure, a cyclooctane structure, a cyclononane structure, a cyclodecane structure, a cyclododecane structure and the like; a norbornane structure and an adamantane structure And polycyclic alicyclic structures such as a tricyclodecane structure and a tetracyclododecane structure. Among these, a cyclohexane structure, a norbornane structure, and an adamantane structure are preferable, and a norbornane structure and an adamantane structure are more preferable. The anion (B) having a norbornane structure and / or an adamantane structure is considered to further increase the acid generated, and as a result, both the depth of focus in forming dense and isolated trench patterns can be further increased. And a resist pattern having a better cross-sectional shape can be formed.

  As the anion (B), an anion represented by the above formula (2) is preferable. By making the anion (B) an anion represented by the above formula (2), it is considered that the acid generated by exposure becomes more bulky and the acid diffusion length becomes more appropriate. Both the depth of focus in forming the trench pattern can be set to a higher level, and a resist pattern having a better cross-sectional shape can be formed.

In the above formula (2), ^{R 4} is a monovalent group having an alicyclic structure having 6 to 15 carbon atoms. Y is a divalent linking group containing a hetero atom. R ⁵ is a divalent hydrocarbon group having 1 to 20 carbon atoms. R ^f1 and R ^f2 are each independently a hydrogen atom, a fluorine atom, an alkyl group having 1 to 30 carbon atoms, or a fluorinated alkyl group having 1 to 30 carbon atoms. m is an integer of 1-3. n is an integer of 0-5. ^However, R ^{4, Y,} R ^5, when ^{R f1} and ^{R f2} is plural respective plurality of ^{R 4, Y,} R ^{5, R f1} and ^{R f2} may each be the same or different.

Examples of the monovalent group having an alicyclic structure having 6 to 15 carbon atoms represented by R ^4, for example,
As a group having a monocyclic alicyclic structure,
Monocyclic alicyclic hydrocarbons such as cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, cyclododecyl, cyclotridecyl, cyclotetradecyl, cyclopentadecyl Groups; groups having a heteroatom such as a 7-oxanorbornyl group, a 7-azanorbornyl group, and a cyclohexane lactonyl group, and a monocyclic alicyclic structure.
In addition, as a group having a polycyclic alicyclic structure,
A polycyclic alicyclic hydrocarbon group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetracyclododecyl group; a polycyclic alicyclic structure having a heteroatom such as a norbornane lactonyl group or an adamantane lactonyl group; And the like.
Among these, a group having a polycyclic alicyclic structure is preferable, a norbornyl group, an adamantyl group, and a norbornane lactonyl group are more preferable, and an adamantyl group and a norbornane lactonyl group are more preferable.

  Examples of the divalent linking group containing a hetero atom represented by Y include, for example, a carbonyl group, an ester group, an ether group, a carbonate group, an imino group, an amide group, a carbamate group, a sulfide group, a thiocarbonyl group, and a thioester group. Thiocarbonate group, thioamide group, thiocarbamate group and the like. Among these, a carbonyl group, an ester group, an ether group, and a carbonate group are preferable, a carbonyl group and an ester group are more preferable, and an ester group is more preferable.

Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms represented by R ⁵ include a divalent chain hydrocarbon group having 1 to 20 carbon atoms and a divalent alicyclic ring having 3 to 20 carbon atoms. Examples thereof include a formula hydrocarbon group and a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

  Examples of the divalent chain hydrocarbon group having 1 to 20 carbon atoms include a methanediyl group, an ethanediyl group, a propanediyl group, and a butanediyl group.

  Examples of the divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include a cyclopropanediyl group, a cyclobutanediyl group, a cyclopentanediyl group, a cyclohexanediyl group, a norbornanediyl group, and an adamantanediyl group.

  Examples of the divalent aromatic hydrocarbon group having 6 to 20 carbon atoms include a phenylene group, a benzylene group, a phenethylene group, a phenylenepropylene group, a naphthylene group, and a naphthylenemethylene group.

Among these, R ⁵ is preferably a divalent chain hydrocarbon group or a divalent alicyclic hydrocarbon group. A methanediyl group, an ethanediyl group, a propanediyl group, a butanediyl group, a cyclopentanediyl group, cyclohexane. A diyl group, a norbornanediyl group, and an adamantanediyl group are more preferable, and an ethanediyl group, a propanediyl group, and a cyclohexanediyl group are more preferable.

Examples of the alkyl group having 1 to 30 carbon atoms represented by R ^f1 and R ^f2 include, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec -Propyl group, t-propyl group, n-hexyl group, n-decyl group and the like.

Examples of the fluorinated alkyl group having 1 to 30 carbon atoms represented by R ^f1 and R ^f2 include a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a fluoroethyl group, a difluoroethyl group, and a trifluoroethyl group. Perfluoroethyl group, perfluoro-n-propyl group, hexafluoro-i-propyl group, perfluorobutyl group, perfluoropentyl group, perfluorohexyl group, perfluorooctyl group, perfluorodecyl group and the like. .

Among these, R ^f1 and R ^f2 are preferably a fluorine atom and a fluorinated alkyl group having 1 to 30 carbon atoms, more preferably a fluorine atom and a perfluoroalkyl group having 1 to 6 carbon atoms, A fluoromethyl group is more preferred, and a fluorine atom is particularly preferred.

  n is preferably an integer of 0 to 3, more preferably an integer of 0 to 2, further preferably 0 or 1, and particularly preferably 1 from the viewpoint of improving the depth of focus of the photoresist composition.

Examples of the group represented by (—C (R ^f1 ) (R ^f2 ) —) n in the above formula (1) include groups represented by the following formulas.

  Among these, from the viewpoint that the strength of the acid generated from the [B] generator is increased, the diffusion length of the acid becomes more appropriate, and the depth of focus of the photoresist composition becomes wider, a fluoromethylene group, A difluoromethylene group, a tetrafluoroethylene group, a trifluoromethylmethylene group, and a hexafluoropropylene group are preferable, and a fluoromethylene group and a difluoromethylene group are more preferable.

  As m, 1 or 2 is preferable.

  Examples of the anion (B) include anions represented by the following formulas (a-1) to (a-10).

  Among these, the anions represented by (a-1) to (a-7) are preferable from the viewpoint of increasing the depth of focus of the photoresist composition, and (a-1), (a-2), The anions represented by (a-5) and (a-6) are more preferred, and the anions represented by (a-1), (a-5) and (a-6) are more preferred.

  [B] The lower limit of the content of the acid generator is preferably 0.1 parts by weight, more preferably 1 part by weight, further preferably 10 parts by weight, and 13 parts by weight with respect to 100 parts by weight of the [A] polymer. Part is particularly preferred, and 15 parts by weight is even more preferred. [B] If the content of the acid generator is less than the lower limit, the sensitivity of the photoresist composition may be lowered. On the other hand, the upper limit of the content of the [B] acid generator is preferably 30 parts by mass, more preferably 25 parts by mass, and still more preferably 22 parts by mass with respect to 100 parts by mass of the [A] polymer. [B] If the content of the acid generator exceeds the above upper limit, the pattern forming property of the photoresist composition may deteriorate. In addition, the said photoresist composition may contain 1 type, or 2 or more types of [B] acid generators.

<[C] acid generator>
[C] The acid generator is an acid generator containing a cation (C) and an anion (C). The photoresist composition further contains a [C] acid generator in addition to the [B] acid generator, whereby the depth of focus in forming both dense and isolated trench patterns can be improved in a balanced manner.

[Cation (C)]
The cation (C) is a cation represented by the above formula (3).

In the above formula (3), R ⁶ , R ⁷ and R ⁸ are each independently a hydroxyl group, a halogen atom, an alkyl group, a monovalent alicyclic hydrocarbon group, an alkoxy group, —S—R ^A , a -OSO ₂ -R ^B or _-SO 2 -R ^C. R ^A , R ^B and R ^C each independently represents an alkyl group, a monovalent alicyclic hydrocarbon group, an alkoxy group, an aryl group or an aralkyl group. However, part or all of the hydrogen atoms of the alkyl group, monovalent alicyclic hydrocarbon group, alkoxy group, aryl group and aralkyl group in R ⁶ , R ⁷ , R ⁸ , R ^A , R ^B and R ^C are May be substituted. p, q, and r are each independently an integer of 0-5. R ^6, when ^{R 7} and ^{R 8} is plural, respectively, a plurality of ^R 6, ^{R 7} and ^{R 8} may be the same as or different from each other.

Examples of the halogen atom represented by R ⁶ , R ⁷ and R ⁸ include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

Examples of the alkyl group represented by R ⁶ , R ⁷ and R ⁸ include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, Examples include t-butyl group.

Examples of the monovalent alicyclic hydrocarbon group represented by R ⁶ , R ⁷ and R ⁸ include monocyclic alicyclic carbonization such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, and cyclodecyl group. A hydrogen group; a polycyclic alicyclic hydrocarbon group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetradecyldodecyl group, and the like.

As an alkoxy group represented by said R < ⁶ >, R < ⁷ > and R < ⁸ >, a methoxy group, an ethoxy group, n-propoxy, i-propoxy group etc. are mentioned, for example.

Examples of the alkyl group represented by R ^A , R ^B and R ^C include the same groups as those exemplified as the alkyl group represented by R ⁶ , R ⁷ and R ⁸ .

Examples of the monovalent alicyclic hydrocarbon group represented by the above R ^A , R ^B and ^RC include, for example, the monovalent alicyclic hydrocarbon group represented by the above R ⁶ , R ⁷ and R ^8. Examples include the same groups as the exemplified groups.

Examples of the alkoxy group represented by R ^A , R ^B and R ^C include the same groups as those exemplified as the alkoxy group represented by R ⁶ , R ⁷ and R ⁸ .

Examples of the aryl group represented by R ^A , R ^B, and R ^C include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and a methylnaphthyl group.

Examples of the aralkyl group represented by R ^A , R ^B and R ^C include a benzyl group, a phenethyl group, a phenylpropyl group and a naphthylmethyl group.

Examples of the substituent of the alkyl group, monovalent alicyclic hydrocarbon group, alkoxy group, aryl group and aralkyl group in the above R ⁶ , R ⁷ , R ⁸ , R ^A , R ^B and R ^C include, for example, a halogen atom , Hydroxyl group, alkoxy group, acyl group, acyloxy group and the like.

  As p, q, and r, an integer of 0 to 3 is preferable, 0 or 1 is more preferable, and 0 is more preferable.

  Examples of the cation (C) include cations represented by the following formulas (c-1) to (c-36).

  Among these, the anion represented by (c-1) is preferable.

[Anion (C)]
The anion (C) is an anion having an alicyclic structure having 6 to 15 carbon atoms. The description about the anion (C) is the same as the anion (B) in the above-mentioned [B] acid generator.

  As content of the [C] acid generator in the said photoresist composition, 20 mass parts or less are preferable with respect to 100 mass parts of [A] polymers, 0.1-18 mass parts is more preferable, 16 parts by mass is more preferable, and 10 to 14 parts by mass is particularly preferable. [C] When the content of the acid generator exceeds the above upper limit, the depth of focus of the photoresist composition tends to decrease. The photoresist composition may contain one or more [C] acid generators.

<[D] Acid diffusion controller>
[D] The acid diffusion controlling agent controls the diffusion phenomenon in the resist film of the acid generated from [B] acid generator and the like by exposure, and has the effect of suppressing undesirable chemical reaction in the non-exposed region. The storage stability of the resist composition is further improved, the resolution of the resist is further improved, and changes in the line width of the resist pattern due to fluctuations in the holding time from exposure to development processing can be suppressed. A very excellent composition.

  [D] Examples of the acid diffusion controller include amine compounds, amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, and the like.

  Examples of the amine compound include mono (cyclo) alkylamines; di (cyclo) alkylamines; tri (cyclo) alkylamines; substituted alkylanilines or derivatives thereof; ethylenediamine, N, N, N ′, N′-tetra Methylethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminobenzophenone, 4,4′-diaminodiphenylamine, 2,2-bis (4 -Aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2- (4-aminophenyl) -2- (3-hydroxyphenyl) propane, 2- (4-amino) Phenyl) -2- (4-hydroxyphenyl) propane, 1, -Bis (1- (4-aminophenyl) -1-methylethyl) benzene, 1,3-bis (1- (4-aminophenyl) -1-methylethyl) benzene, bis (2-dimethylaminoethyl) ether Bis (2-diethylaminoethyl) ether, 1- (2-hydroxyethyl) -2-imidazolidinone, 2-quinoxalinol, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, N, N, N ′, N ″ N ″ -pentamethyldiethylenetriamine and the like.

  Examples of the amide group-containing compound include Nt-butoxycarbonyl group-containing amino compounds such as Nt-butoxycarbonyl-4-hydroxypiperidine, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N- Examples include methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone, N-acetyl-1-adamantylamine, and isocyanuric acid tris (2-hydroxyethyl). Among these, Nt-butoxycarbonyl group-containing amino compounds are preferable, and Nt-butoxycarbonyl-4-hydroxypiperidine is more preferable.

  Examples of urea compounds include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tri-n-butylthiourea and the like. Is mentioned.

  Examples of the nitrogen-containing heterocyclic compound include imidazoles; pyridines; piperazines; pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, piperidine, piperidine ethanol, 3-piperidino-1,2-propanediol, morpholine, 4- Methylmorpholine, 1- (4-morpholinyl) ethanol, 4-acetylmorpholine, 3- (N-morpholino) -1,2-propanediol, 1,4-dimethylpiperazine, 1,4-diazabicyclo [2.2.2 ] Octane etc. are mentioned.

  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 decomposes upon exposure and loses acid diffusion controllability. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (D1), an iodonium salt compound represented by the following formula (D2), and the like.

In the above formula (D1) and formula (D2), R ^{9 to} R ¹³ are each independently a hydrogen atom, an alkyl group, an alkoxyl group, a hydroxyl group, or a halogen atom. Z ⁻ is OH ⁻ , R ^H —COO ⁻ , R ^H —SO ₃ ^— or an anion represented by the following formula (D3). However, ^RH is an alkyl group, an aryl group, or an aralkyl group.

In the above formula (D3), R ¹⁴ is a linear or branched alkyl group having 1 to 12 carbon atoms or a carbon atom having 1 to 12 carbon atoms, in which part or all of the hydrogen atoms may be substituted with fluorine atoms. It is a linear or branched alkoxyl group. u is an integer of 0-2.

  The content of the [D] acid diffusion controller in the photoresist composition is preferably less than 10 parts by mass and more preferably less than 5 parts by mass with respect to 100 parts by mass of the [A] polymer. [D] When the content of the acid diffusion controller exceeds 10 parts by mass, the sensitivity of the photoresist composition tends to decrease. The photoresist composition may contain one or more [D] acid diffusion control agents.

<[E] Fluorine atom-containing polymer>
[E] The fluorine atom-containing polymer is a polymer having a higher fluorine atom content ratio than the [A] polymer. The photoresist composition contains the [E] fluorine atom-containing polymer, and when the resist film is formed, the distribution of the resist film surface layer depends on the oil-repellent characteristics of the [E] fluorine atom-containing polymer. Therefore, at the time of immersion exposure, elution of the acid generator and acid diffusion control agent in the film into the immersion medium can be suppressed. Further, due to the water-repellent characteristics of the [E] fluorine atom-containing polymer, the advancing contact angle between the resist film and the immersion medium can be controlled within a desired range, and the occurrence of bubble defects can be suppressed. In addition, the receding contact angle between the resist film and the immersion medium can be increased, and as a result, high-speed scanning exposure is possible without leaving water droplets. Thus, when the said photoresist composition contains a [E] fluorine atom containing polymer, the resist film suitable for an immersion exposure method can be formed. In addition, the fluorine atom content rate (mass%) of a polymer can be calculated | required by identifying the structure of a polymer by < ¹³ > C-NMR measurement.

  [E] The fluorine atom-containing polymer is not particularly limited as long as it is a polymer containing a fluorine atom, but is usually formed by polymerizing one or more monomers containing fluorine atoms in the structure. be able to. Examples of the monomer containing a fluorine atom in the structure include those containing a fluorine atom in the main chain, those containing a fluorine atom in the side chain, and those containing a fluorine atom in the main chain and the side chain.

  Examples of the monomer containing a fluorine atom in the main chain include an α-fluoroacrylate compound, an α-trifluoromethyl acrylate compound, a β-fluoroacrylate compound, a β-trifluoromethyl acrylate compound, and an α, β-fluoroacrylate compound. , Α, β-trifluoromethyl acrylate compounds, compounds in which one or more types of vinyl moiety hydrogen are substituted with fluorine atoms or trifluoromethyl groups, and the like.

  Examples of the monomer containing a fluorine atom in the side chain include those in which the side chain of an alicyclic olefin compound such as norbornene is a fluorine atom, a fluoroalkyl group or a derivative thereof, acrylic acid or methacrylic acid, and a fluoroalkyl alcohol. And an ester compound formed from a derivative thereof and one or more olefin side chains (parts not including a double bond) are fluorine atoms, fluoroalkyl groups or derivatives thereof.

  Examples of monomers containing fluorine atoms in the main chain and side chain include α-fluoroacrylic acid, β-fluoroacrylic acid, α, β-fluoroacrylic acid, α-trifluoromethylacrylic acid, β-trifluoro An ester compound formed from methylacrylic acid, α, β-ditrifluoromethylacrylic acid, etc., and a fluoroalkyl alcohol or a derivative thereof, and hydrogen in one or more kinds of vinyl sites is substituted with a fluorine atom or a trifluoromethyl group A compound in which the side chain of the compound is substituted with a fluorine atom or a fluoroalkyl group or a derivative thereof, and hydrogen bonded to a double bond of one or more alicyclic olefin compounds is substituted with a fluorine atom or a trifluoromethyl group And those whose side chain is a fluoroalkyl group or a derivative thereof. In addition, this alicyclic olefin compound shows the compound in which a part of ring is a double bond.

  In the fluorine atom-containing polymer, the structural unit imparting a fluorine atom is not particularly limited. However, the structural unit represented by the following formula (E1) (hereinafter referred to as “structural unit (EI)”) Is preferably used as the fluorine atom-providing structural unit.

In said formula (E1), ^Rd is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. A is a single bond or a divalent linking group. R ¹⁵ is a linear or branched alkyl group having 1 to 6 carbon atoms having at least one fluorine atom, a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms, or a derivative thereof. .

  Examples of the divalent linking group represented by A include an oxygen atom, a sulfur atom, a carbonyloxy group, an oxycarbonyl group, an amide group, a sulfonylamide group, and a urethane group.

  Preferred monomers that give the structural unit (EI) include trifluoromethyl (meth) acrylic acid ester, 2,2,2-trifluoroethyl (meth) acrylic acid ester, and perfluoroethyl (meth) acrylic. Acid ester, perfluoro n-propyl (meth) acrylic acid ester, perfluoro i-propyl (meth) acrylic acid ester, perfluoro n-butyl (meth) acrylic acid ester, perfluoro i-butyl (meth) acrylic acid ester , Perfluoro t-butyl (meth) acrylate, 2- (1,1,1,3,3,3-hexafluoropropyl) (meth) acrylate, 1- (2,2,3,3, 4,4,5,5-octafluoropentyl) (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) ) Acrylic acid ester, 1- (2,2,3,3,3-pentafluoropropyl) (meth) acrylic acid ester, 1- (3,3,4,4,5,5,6,6,7, 7,8,8,9,9,10,10,10-heptadecafluorodecyl) (meth) acrylic acid ester, 1- (5-trifluoromethyl-3,3,4,4,5,6,6 , 6-octafluorohexyl) (meth) acrylic acid ester and the like.

  In the fluorine atom-containing polymer, the content ratio of the structural unit (EI) is usually 5 mol% or more, preferably 10 mol% or more, more preferably, with respect to all the structural units in the fluorine atom-containing polymer. It is 15 mol% or more. If the content ratio of the structural unit (EI) is less than 5 mol%, a receding contact angle of 70 ° or more may not be achieved, and elution of the acid generator and the like from the resist film may not be suppressed. The said fluorine atom containing polymer may contain 1 type of structural units (EI), and may contain 2 or more types.

  In addition to the structural unit having a fluorine atom in the structure, the fluorine atom-containing polymer includes, for example, a structural unit having an acid dissociable group for controlling the dissolution rate in a developer, a lactone skeleton, a hydroxyl group, In order to suppress scattering of light due to structural units having a carboxyl group or the like, or structural units having an alicyclic compound, or reflection from the substrate, “other structural units” such as structural units derived from aromatic compounds are 1 More than one kind can be contained.

  Examples of the structural unit having a dissociable group include a structural unit represented by the following formula (E2) (hereinafter also referred to as “structural unit (E-II)”).

In the above formula (E2), R ^e is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ^q1 , R ^q2 and R ^q3 are each independently a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof, or a linear or branched alkyl having 1 to 4 carbon atoms. It is a group.

Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by R ^q1 , R ^q2 and R ^q3 include norbornane, tricyclodecane, tetracyclododecane, adamantane, cyclobutane and cyclopentane. , A group derived from an alicyclic ring such as cycloalkane such as cyclohexane, cycloheptane, cyclooctane, etc .; a part or all of the hydrogen atoms of the group derived from these alicyclic rings may be, for example, a methyl group, ethyl A linear or branched alkyl group having 1 to 4 carbon atoms such as a group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group, etc. Or a group substituted with one or more cycloalkyl groups having 3 to 10 carbon atoms such as a cyclobutyl group and a cyclohexyl group. Moreover, any two of R ^{12 to} R ¹⁴ may be bonded to each other to form a divalent alicyclic hydrocarbon group or a derivative group thereof together with the carbon atom to which each is bonded. Of these alicyclic hydrocarbon groups, norbornane, tricyclodecane, tetracyclododecane, adamantane, cyclopentane, or a group derived from an alicyclic ring of cyclohexane, or a hydrogen derived from these alicyclic rings A group in which an atom is substituted with the above alkyl group is preferable.

Examples of the linear or branched alkyl group having 1 to 4 carbon atoms represented by R ^q1 , R ^q2 and R ^q3 include, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n -Butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group and the like can be mentioned.

  In the above formula (E2), preferred acid dissociable groups, that is, examples of the group bonded to the oxygen atom of the ester group include a t-butyl group, a 1-n- (1-ethyl-1-methyl) propyl group, 1-n- (1,1-dimethyl) propyl group, 1-n- (1,1-dimethyl) butyl group, 1-n- (1,1-dimethyl) pentyl group, 1- (1,1-diethyl) ) Propyl group, 1-n- (1,1-diethyl) butyl group, 1-n- (1,1-diethyl) pentyl group, 1- (1-methyl) cyclopentyl group, 1- (1-ethyl) cyclopentyl Group, 1- (1-n-propyl) cyclopentyl group, 1- (1-i-propyl) cyclopentyl group, 1- (1-methyl) cyclohexyl group, 1- (1-ethyl) cyclohexyl group, 1- (1 -N-propyl) cyclohexyl group, 1- 1-i-propyl) cyclohexyl group, 1- {1-methyl-1- (2-norbornyl)} ethyl group, 1- {1-methyl-1- (2-tetracyclodecanyl)} ethyl group, 1- {1-methyl-1- (1-adamantyl)} ethyl group, 2- (2-methyl) norbornyl group, 2- (2-ethyl) norbornyl group, 2- (2-n-propyl) norbornyl group, 2- (2-i-propyl) norbornyl group, 2- (2-methyl) tetracyclodecanyl group, 2- (2-ethyl) tetracyclodecanyl group, 2- (2-n-propyl) tetracyclodecanyl group 2- (2-i-propyl) tetracyclodecanyl group, 1- (1-methyl) adamantyl group, 1- (1-ethyl) adamantyl group, 1- (1-n-propyl) adamantyl group, 1- (1-i-propyl) adaman Group consisting of these alicyclic rings, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, Examples include a group substituted with one or more of a linear or branched alkyl group having 1 to 4 carbon atoms, such as a t-butyl group, or a cyclic alkyl group having 3 to 10 carbon atoms. .

Preferred monomers that give the structural unit (E-II) include (meth) acrylic acid 2-methyladamantyl-2-yl ester and (meth) acrylic acid 2-methyl-3-hydroxyadamantyl-2-yl ester. (Meth) acrylic acid 2-ethyladamantyl-2-yl ester, (meth) acrylic acid 2-ethyl-3-hydroxyadamantyl-2-yl ester, (meth) acrylic acid 2-n-propyladamantyl-2-yl ester Ester, (meth) acrylic acid 2-isopropyladamantyl-2-yl ester, (meth) acrylic acid-2-methylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-2-ethyl ester Bicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-8-methyltricyclo [5.2. .0 ^2,6] decan-8-yl ester, (meth) ethyl-8-acrylic acid tricyclo [5.2.1.0 ^2,6] decan-8-yl ester, (meth) acrylic acid -4 -Methyltetracyclo [6.2.1 ^3,6 . 0 ^2,7 ] dodecan-4-yl ester, (meth) acrylic acid-4-ethyltetracyclo [6.2.1 ^3,6 . 02,7] dodecan-4-yl ester, (meth) acrylic acid 1- (bicyclo [2.2.1] hept-2-yl) -1-methylethyl ester, (meth) acrylic acid 1- (tricyclo [ 5.2.1.0 ^2,6 ] decan-8-yl) -1-methylethyl ester, (meth) acrylic acid 1- (tetracyclo [6.2.1 ^3,6.0 0.0 ^2,7 ] dodecane- 4-yl) -1-methylethyl ester, (meth) acrylic acid 1- (adamantan-1-yl) -1-methylethyl ester, (meth) acrylic acid 1- (3-hydroxyadamantan-1-yl)- 1-methylethyl ester, (meth) acrylic acid 1,1-dicyclohexylethyl ester, (meth) acrylic acid 1,1-di (bicyclo [2.2.1] hept-2-yl) ethyl ester, ( Data) acrylic acid 1,1-di (tricyclo [5.2.1.0 ^2,6] decan-8-yl) ethyl ester, (meth) acrylic acid 1,1-di (tetracyclo [6.2.1 ^3,6 .0 ^2,7] dodecane-4-yl) ethyl ester, (meth) acrylic acid 1,1-di (adamantan-1-yl) ethyl ester, (meth) acrylic acid 1-methyl-1-cyclopentyl Examples include esters, (meth) acrylic acid 1-ethyl-1-cyclopentyl ester, (meth) acrylic acid 1-methyl-1-cyclohexyl ester, (meth) acrylic acid 1-ethyl-1-cyclohexyl ester, and the like.

  Among these monomers, (meth) acrylic acid 2-methyladamantyl-2-yl ester, (meth) acrylic acid 2-ethyladamantyl-2-yl ester, (meth) acrylic acid-2-methylbicyclo [2 2.1] hept-2-yl ester, (meth) acrylic acid-2-ethylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid 1- (bicyclo [2.2. 1] hept-2-yl) -1-methylethyl ester, (meth) acrylic acid 1- (adamantan-1-yl) -1-methylethyl ester, (meth) acrylic acid 1-methyl-1-cyclopentyl ester, (Meth) acrylic acid 1-ethyl-1-cyclopentyl ester, (meth) acrylic acid 1-methyl-1-cyclohexyl ester, (meth) acrylic acid 1-e -1-cyclohexyl ester.

  As the structural unit having the lactone skeleton, those similar to the structural unit (III) of the [A] polymer can be used. (Hereinafter also referred to as “structural unit (E-III)”)

  Examples of the structural unit having the alicyclic group (hereinafter also referred to as “structural unit (E-IV)”) include a structural unit represented by the following formula (E4).

In the above formula (E4), R ^f is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ¹⁶ is a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms.

Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by R ¹⁶ include cyclobutane, cyclopentane, cyclohexane, bicyclo [2.2.1] heptane, and bicyclo [2.2. 2] Octane, tricyclo [5.2.1.0 ^2,6 ] decane, tetracyclo [6.2.1.1 ^3,6 . Hydrocarbon groups derived from alicyclic rings of cycloalkanes such as 0 ^2,7 ] dodecane and tricyclo [3.3.1.1 ^3,7 ] decane. The carbon hydrogen group derived from these cycloalkane-derived alicyclic rings may have a substituent, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group. 1 type or more of C1-C4 linear or branched alkyl groups, such as 2-methylpropyl group, 1-methylpropyl group, t-butyl group, or C3-C10 cycloalkyl group, or 1 It may be substituted with more than one. The substituents are not limited to these alkyl groups and cycloalkyl groups, and may be those substituted with a hydroxyl group, a cyano group, a hydroxyalkyl group having 1 to 10 carbon atoms, a carboxyl group, or an oxygen atom. .

Preferred monomers that give the structural unit (E-IV) include (meth) acrylic acid-bicyclo [2.2.1] hept-2-yl ester and (meth) acrylic acid-bicyclo [2.2. 2] Oct-2-yl ester, (meth) acrylic acid-tricyclo [5.2.1.02,6] dec-7-yl ester, (meth) acrylic acid-tetracyclo [6.2.1.13, 6.0 ^2,7 ] dodec-9-yl ester, (meth) acrylic acid-tricyclo [3.3.1.1 ^3,7 ] dec-1-yl ester, (meth) acrylic acid-tricyclo [3. 3.1.1 ^3,7 ] dec-2-yl ester and the like.

  Moreover, as a preferable monomer which gives the structural unit derived from the said aromatic compound (henceforth "structural unit (EV)"), for example, styrene, α-methylstyrene, 2-methylstyrene, 3 -Methylstyrene, 4-methylstyrene, 2-methoxystyrene, 3-methoxystyrene, 4-methoxystyrene, 4- (2-t-butoxycarbonylethyloxy) styrene 2-hydroxystyrene, 3-hydroxystyrene, 4-hydroxy Styrene, 2-hydroxy-α-methylstyrene, 3-hydroxy-α-methylstyrene, 4-hydroxy-α-methylstyrene, 2-methyl-3-hydroxystyrene, 4-methyl-3-hydroxystyrene, 5-methyl -3-hydroxystyrene, 2-methyl-4-hydroxystyrene, 3-methyl-4 Hydroxystyrene, 3,4-dihydroxystyrene, 2,4,6-trihydroxystyrene, 4-t-butoxystyrene, 4-t-butoxy-α-methylstyrene, 4- (2-ethyl-2-propoxy) styrene 4- (2-ethyl-2-propoxy) -α-methylstyrene, 4- (1-ethoxyethoxy) styrene, 4- (1-ethoxyethoxy) -α-methylstyrene, phenyl (meth) acrylate, ( Meth) acrylic acid benzyl, acenaphthylene, 5-hydroxyacenaphthylene, 1-vinylnaphthalene, 2-vinylnaphthalene, 2-hydroxy-6-vinylnaphthalene, 1-naphthyl (meth) acrylate, 2-naphthyl (meth) acrylate, 1-naphthylmethyl (meth) acrylate, 1-anthryl (meth) acrylate, 2 -Anthryl (meth) acrylate, 9-anthryl (meth) acrylate, 9-anthrylmethyl (meth) acrylate, 1-vinylpyrene, etc. are mentioned.

  As the “other structural unit” of the above-mentioned [E] fluorine atom-containing polymer, the structural unit (E-II), the structural unit (E-III), the structural unit (E-IV), and the structural unit (EV) May have only 1 type, and may have 2 or more types. In the [E] fluorine atom-containing polymer, the content ratio of these other structural units is usually 80 mol% or less, preferably 75 mol%, based on all the structural units constituting the [E] fluorine atom-containing polymer. Hereinafter, it is 70 mol% or less more preferably.

<[E] Method for Synthesizing Fluorine Atom-Containing Polymer>
The fluorine atom-containing polymer can be synthesized, for example, by polymerizing monomers corresponding to predetermined respective structural units in a suitable solvent using a radical polymerization initiator.

<[F] solvent>
The photoresist composition usually contains a [F] solvent. [F] The solvent is not particularly limited as long as it can dissolve or disperse the [A] polymer, the [B] acid generator, and optional components contained as necessary.

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

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

  Examples of the ether solvent include diethyl ether, dipropyl ether, dibutyl ether, diphenyl ether, methoxybenzene, anisole (methylphenyl ether) and the like.

  Examples of ketone solvents include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, methyl-n-pentyl ketone (2-heptanone), ethyl-n-butyl ketone. , Ketones such as methyl-n-hexyl ketone, di-iso-butyl ketone, trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, acetophenone And system solvents.

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

  Examples of the ester solvents include diethyl carbonate, propylene carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, γ-valerolactone, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec sec -Butyl, n-pentyl acetate, i-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, n-acetate -Nonyl, methyl acetoacetate, ethyl acetoacetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoe Til ether acetate, diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl Ether acetate, glycol diacetate, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate , N-amyl lactate, diethyl malonate, dimethyl phthalate, diethyl phthalate, etc. .

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

  Among these, ester solvents and ketone solvents are preferable, and propylene glycol monomethyl ether acetate, cyclohexanone, and γ-butyrolactone are more preferable. The photoresist composition may contain one or more [F] organic solvents.

<Other optional components>
The photoresist composition may contain other optional components in addition to the components [A] to [E]. Examples of the other optional components include [B] acid generators and other acid generators other than [C] acid generators, surfactants, and alicyclic skeleton-containing compounds. Each of these other optional components may be used alone or in combination of two or more.

[Other acid generators]
Although the said photoresist composition contains a [B] acid generator and the [C] acid generator as needed, it is not necessary especially, Other than a [B] acid generator and a [C] acid generator Other acid generators may be included in a small amount. Examples of other acid generators include sulfonium salt compounds or tetrahydrothiophenium salt compounds, iodonium salt compounds, phosphonium salt compounds, diazonium salt compounds, and pyridinium salts other than [B] acid generators and [C] acid generators. Examples include compounds, sulfonimide compounds, halogen-containing compounds, diazoketone compounds, and the like.

[B] As the sulfonium salt compound other than the acid generator and the [C] acid generator, for example,
Triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n- Butanesulfonate, 4-cyclohexylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium Perfluo -n- octane sulfonate, and the like.

  Examples of tetrahydrothiophenium salt compounds other than [B] acid generator and [C] acid generator include 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, (6-n-butoxynaphthalen-2-yl) te Lahydrothiophenium perfluoro-n-octanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydro Examples thereof include thiophenium nonafluoro-n-butanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium perfluoro-n-octanesulfonate.

As an iodonium salt, for example,
Diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2, 2-tetrafluoroethanesulfonate, diphenyliodonium camphorsulfonate, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, bis (4-t- Butylphenyl) iodonium perfluoro-n-octanesulfonate, bis (4-t-butylphenyl) iodonium 2-bicyclo [2.2.1] hept-2-yl-1,1 2,2-tetrafluoroethane sulfonate, bis (4-t- butylphenyl) iodonium camphorsulfonate, and the like. Of these iodonium salts, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate is preferred.

As a sulfonimide compound, for example,
N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (nonafluoro-n-butanesulfonyloxy) bicyclo [2.2.1] hept -5-ene-2,3-dicarboximide, N- (perfluoro-n-octanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- ( 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboxy imide, N- (2- (3- tetracyclo ^[4.4.0.1 2,5 ^{.1 7,10]} dodecanyl) -1,1-difluoroethane-sulfonyloxy) bicyclo [2.2.1] hept Examples include -5-ene-2,3-dicarboximide, N- (camphorsulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide. Of these sulfonimide compounds, N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide is preferred.

  As content of the other acid generator in the said photoresist composition, it is 10 mass parts or less normally with respect to 100 mass parts of [A] polymers, 5 mass parts or less are preferable, and 1 mass part or less is preferable. More preferred. When the content of the other acid generator exceeds the upper limit, the depth of focus of the photoresist composition tends to decrease.

[Surfactant]
Surfactants have the effect of improving coatability, striation, developability, and the like. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol diacrylate. Nonionic surfactants such as stearate; commercially available products include KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, manufactured by Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (above, manufactured by Tochem Products), MegaFuck F171, F173 (above, manufactured by DIC), Florard FC430, FC431 (above, Sumitomo 3M) Manufactured by Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, manufactured by Asahi Glass Industrial Co., Ltd.) Can be mentioned. As content of surfactant in the said photoresist composition, it is 2 mass parts or less normally with respect to 100 mass parts of [A] polymers.

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

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

[Sensitizer]
The sensitizer exhibits an effect of increasing the amount of acid generated from the [B] acid generator and [C] acid generator, and has the effect of improving the “apparent sensitivity” of the photoresist composition. Play.

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

<Method for preparing photoresist composition>
The photoresist composition can be prepared, for example, by mixing [A] polymer, [B] acid generator, optional component contained as necessary, and [F] solvent at a predetermined ratio. The photoresist composition is usually mixed with each component so that the total solid content concentration is 1 to 50% by mass, preferably 3 to 25% by mass, and then filtered through, for example, a filter having a pore size of about 0.2 μm. It is prepared by.

<Method for forming resist pattern>
The method for forming a resist pattern according to the present invention includes:
(1) A step of applying the photoresist composition on a substrate to form a resist film (hereinafter also referred to as “(1) step”),
(2) a step of exposing the resist film through a photomask (hereinafter also referred to as “(2) step”); and (3) a step of developing the exposed resist film (hereinafter referred to as “(3)”. Also called "process")
Have Hereinafter, each step will be described.

[(1) Process]
In the step (1), the photoresist composition is applied onto the substrate by an appropriate application means such as spin coating, cast coating, roll coating or the like, thereby forming a resist film. Examples of the substrate include a silicon wafer, silicon dioxide, a wafer coated with an antireflection film, and the like. Specifically, after applying the photoresist so that the resulting resist film has a predetermined thickness, the solvent in the coating film is vaporized by pre-baking (PB) to form a resist film. As temperature of PB, it is 60 to 140 degreeC normally, and 80 to 120 degreeC is preferable. The PB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.

[(2) Process]
In the step (2), the photoresist film formed in the step (1) is irradiated with exposure light (possibly through an immersion medium such as water) to be exposed. In this case, exposure light is irradiated through a mask having a predetermined pattern. The exposure light is appropriately selected and irradiated from, for example, visible light, ultraviolet light, far ultraviolet light, X-rays, charged particle beams, etc. according to the line width of the target pattern. Among these, far ultraviolet rays such as ArF excimer laser light (wavelength 193 nm) and KrF excimer laser light (wavelength 248 nm) are preferable, and ArF excimer laser light is particularly preferable.

  After the exposure, post-exposure baking (PEB) is preferably performed to promote dissociation of the acid-dissociable group of the [A] polymer by the acid generated by the exposure in the exposed portion of the resist film. This PEB causes a difference in solubility in an alkaline developer between an exposed portion (exposed portion) and an unexposed portion (unexposed portion). As temperature of PEB, it is 50 to 180 degreeC normally, and 80 to 130 degreeC is preferable. The PEB time is usually 5 to 600 seconds, preferably 10 to 300 seconds.

[(3) Process]
In step (3), the exposed photoresist film is developed with a developer to form a predetermined resist pattern. After development, it is common to wash with water and dry. Examples of the developer include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, Ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo- [4. 3.0] An aqueous alkali solution in which at least one of alkaline compounds such as 5-nonene is dissolved is preferable. In addition, as a developer, an organic solvent such as a hydrocarbon solvent, an ether solvent, an ester solvent, a ketone solvent, an alcohol solvent, or a solvent containing an organic solvent can be used.

  In addition, when performing immersion exposure, before the step (2), in order to protect the direct contact between the immersion liquid and the resist film, an immersion protective film insoluble in the immersion liquid is formed on the resist film. May be provided. Examples of the immersion protective film include a solvent peeling type protective film that peels off with a solvent before the step (3) (see, for example, JP-A-2006-227632), and a developer peeling type that peels off simultaneously with the development in the step (3). Any of the protective films (see, for example, WO2005-069076 and WO2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer peeling type immersion protective film.

  Since the resist pattern forming method uses the photoresist composition described above, it is particularly suitable for forming a trench pattern, and has an excellent balance of focus depth in both dense trench pattern and isolated trench pattern formation. In addition, a pattern having a good cross-sectional shape can be formed.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. The measuring method of various physical property values is shown below.

[ ¹³ C-NMR analysis]
The ¹³ C-NMR analysis of the polymer was measured using a nuclear magnetic resonance apparatus (JNM-EX270, manufactured by JEOL Ltd.).

<[A] Synthesis of polymer>
[A] Monomers used for polymer synthesis are shown below.

[Synthesis Example 1] (Synthesis of polymer (A-1))
60 mol% of the compound (M-1) and 40 mol% of the compound (M-2) as monomers, and 5 mol% of AIBN as a polymerization initiator (ratio to the total number of moles of monomer and polymerization initiator) Was dissolved in 60 g of methyl ethyl ketone to prepare a monomer solution. The total mass of the monomers was 30 g.
Meanwhile, 30 g of ethyl methyl ketone was charged into a 500 mL three-necked flask equipped with a thermometer and a dropping funnel, and purged with nitrogen for 30 minutes. Then, it heated so that it might become 80 degreeC, stirring the inside of a flask with a magnetic stirrer.
Subsequently, the monomer solution prepared above was dropped into the flask using a dropping funnel over 3 hours to perform a polymerization reaction. After dropping, the mixture was aged for 3 hours, and then cooled to 30 ° C. or lower to obtain a polymerization reaction solution.
This polymerization reaction solution was put into 600 g of methanol, and the precipitated white powder was filtered off. The filtered white powder was washed twice with 120 g of methanol as a slurry, washed, filtered and dried at 50 ° C. for 17 hours to obtain a white powder polymer (A-1) ( Yield: 24.4 g, Yield: 81.3%). Mw of the polymer (A-1) was 7,500, and Mw / Mn was 1.4. As a result of ¹³ C-NMR analysis, the content ratio (mol%) of the structural unit derived from the compound (M-1) to the structural unit derived from the compound (M-2) was 57.6: 42.4. .

[Synthesis Examples 2 and 3] (Synthesis of Polymers (A-2) and (A-3))
Polymers (A-2) and (A-3) were respectively synthesized in the same manner as in Synthesis Example 1 except that the types and amounts of compounds shown in Table 1 below were used. Table 1 shows the measured values of Mw, Mw / Mn, the content ratio of each structural unit, and the yield (%) of the polymers (A-2) and (A-3).

<Preparation of photoresist composition>
[A] The components constituting the photoresist composition other than the polymer are shown below.

[[B] acid generator]
B-1 to B-6: Compounds represented by the following formulas (B-1) to (B-6), respectively.

[[C] acid generator]
C-1: Compound represented by the following formula (C-1)

[[D] acid diffusion controller]
D-1: Nt-butoxycarbonyl-4-hydroxypiperidine

[[F] solvent]
F-1: Propylene glycol monomethyl ether acetate F-2: Cyclohexanone F-3: γ-Butyrolactone

[Example 1]
[A] 100 parts by mass of (A-1) as a polymer, [B] 17.5 parts by mass of (B-1) as an acid generator, [D] (D-1) 1 as an acid diffusion controller .7 parts by mass, and (F-1) 1,985 parts by mass, (F-2) 850 parts by mass and (F-3) 30 parts by mass as a solvent were mixed, and the photoresist of Example 1 was mixed. A composition was prepared.

[Examples 2 to 10 and Comparative Example 1]
Photoresist compositions of Examples 2 to 10 and Comparative Example 1 were prepared in the same manner as in Example 1 except that the components of the types and blending amounts shown in Table 2 below were used. “-” In Table 2 indicates that the corresponding component was not used.

<Evaluation>
About each prepared said photoresist composition, according to the following method, the depth of focus (Dense DOF) in dense trench pattern formation, the depth of focus (Iso DOF) in isolated trench pattern formation, and the cross-sectional shape of the resist pattern formed were evaluated. The obtained evaluation results are shown in Table 2 below.

[Depth of focus in dense trench pattern formation (Dense DOF)]
A 12-inch silicon wafer was spin-coated with a composition for forming an antireflection film (ARC66, manufactured by Nissan Chemical Co., Ltd.) using a coating / developing apparatus (CLEAN TRACK Lithius Pro i, manufactured by Tokyo Electron), and then at 205 ° C. By baking for 60 seconds, a lower antireflection film having a film thickness of 105 nm was formed. On the lower antireflection film, the photoresist composition is spin-coated using a coating / developing apparatus (CLEAN TRACK ACT12, manufactured by Tokyo Electron), SB is performed at 100 ° C. for 60 seconds, and a resist film having a thickness of 100 nm is formed. Formed. Next, the upper layer film forming composition described in Example 1 of WO2008 / 47678 is spin-coated on the resist film using the above coating / developing apparatus (CLEAN TRACK Lithius Pro i), and at 90 ° C. for 60 seconds. An upper layer film having a thickness of 30 nm was formed by PB. Subsequently, the formed resist film was passed through a mask pattern of 70 nm Line 140 nm Pitch using an ArF excimer laser immersion exposure apparatus (NSR S610C, manufactured by NIKON) under the conditions of NA = 1.3, ratio = 0.675, and Annular. And exposed. After the exposure, PEB was performed for 60 seconds at the PEB temperature (° C.) shown in Table 2 below. Then, it developed with 2.38 mass% TMAH aqueous solution, washed with water, and dried, and the positive resist pattern was formed. At this time, an exposure amount at which a portion exposed through a mask pattern of 70 nm Line 140 nm Pitch forms a Line having a line width of 70 nm was defined as an optimum exposure amount (Eop). Note that a scanning electron microscope (CG-4100, manufactured by Hitachi High-Technologies) was used for length measurement.

  In the above Eop, the range in which the focal point where the width of the trench (space portion) formed falls within the range of 63 nm to 77 nm is deviated is defined as Dense DOF. It can be said that if Dense DOF is 0.04 μm or more, it is “good”, and if it is 0.02 μm or more and less than 0.04 μm, it is “somewhat good”.

[Depth of focus in isolated pattern (Iso DOF)]
A positive resist pattern was formed in the same manner as in the formation of the 70 nm Line 140 nm Pitch pattern except that the exposure was performed at the Eop through a 50 nm Trench 1000 nm Pitch mask pattern. At this time, when the focus of the pattern to be formed is 50 nm Trench 1000 nm Pitch, the range in which the width of the formed trench is deviated to fall within 45 nm to 55 nm is defined as Iso DOF. It can be said that the Iso DOF is good if it is 0.06 μm or more.

[Pattern cross-sectional shape]
At the above Eop, the cross-sectional shape of the trench pattern of 50 nm Trench 1000 nm Pitch formed above was observed using a scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies). The case where the pattern cross-sectional shape was a rectangle was evaluated as “good”, the case where a slight skirt was observed, “slightly good”, and the case where the skirt was a shape “bad”.

  As is clear from the results in Table 2, when the photoresist compositions of Examples 1 to 10 were used, compared to the photoresist composition of Comparative Example 1, both the dense and isolated trench patterns were focused. It is possible to form a resist pattern in which both the depth can be set to a high level and the cross-sectional shape is excellent. In addition, it can be seen from the results in Table 2 that as the content of the [B] acid generator is increased, the depth of focus particularly in forming an isolated trench pattern tends to be further improved. This is presumably because, for example, the [B] acid generator used in the present invention has high permeability to exposure light, so that it can function effectively even if the concentration in the resist film is increased.

  According to the photoresist composition and the pattern forming method of the present invention, both the dense and isolated trench patterns can be formed at a high depth of focus, and a resist pattern having an excellent cross-sectional shape can be formed. Therefore, it can be suitably used for lithography techniques that require further formation of patterns of various shapes and sizes and further miniaturization in the future.

Claims (9)

[A] a polymer having a structural unit (I) containing an acid-dissociable group, and [B] an acid generator comprising a cation represented by the following formula (1) and an anion represented by the following formula (2) Containing agents,
[A] A photoresist composition in which the content of the [B] acid generator is 10 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the polymer .

(In formula (1), R ¹ , R ² and R ³ are each independently an alkyl group having 1 to 20 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. , R ¹ and R ² may be bonded to each other to form a ring structure together with the sulfur atom to which they are bonded, X is a single bond or an oxygen atom, and a is 0-7. (However, when there are a plurality of R ³ and X, respectively, the plurality of R ³ and X may be the same or different. B is 0 or 1.)

(In Formula (2), R ⁴ is a monovalent group having an alicyclic structure having 6 to 15 carbon atoms. Y is a divalent linking group containing a hetero atom. R ⁵ is a carbon number. R 2 is a divalent hydrocarbon group having 1 to ^20. R ^f1 and R ^f2 each independently represent a hydrogen atom, a fluorine atom, an alkyl group having 1 to 30 carbon atoms, or a fluorinated alkyl group having 1 to 30 carbon atoms. M is an integer of 1 to 3. n is an integer of 0 to ^5. However, when R ⁴ , Y, R ⁵ , R ^f1, and R ^f2 are plural, plural R ⁴ , Y, R ⁵ , R ^f1 and R ^f2 may be the same or different. The photoresist composition according to claim 1, wherein the cation represented by the formula (1) is represented by the following formula (1-1).

(In formula (1-1), R ³ , X, a and b have the same meanings as in formula (1) above). The photoresist composition according to claim 1 or 2 , wherein the anion has at least one structure selected from the group consisting of an adamantane structure and a norbornane structure. [A] The photoresist composition according to claim 1 , wherein the polymer further comprises a structural unit (II) containing a polar group. [C] In any one of Claims 1-4 which further contains the acid generator containing the cation represented by following formula (3), and the anion which has a C6-C15 alicyclic structure. The photoresist composition as described.

(In Formula (3), R < ⁶ >, R < ⁷ > and R < ⁸ > are respectively independently a hydroxyl group, a halogen atom, an alkyl group, a monovalent alicyclic hydrocarbon group, an alkoxy group, -S-R ^<A> , -OSO ₂ -R ^B or _-SO 2 -R ^C a is ^.R a, ^{R B} and ^{R C} are each independently an alkyl group, a monovalent alicyclic hydrocarbon group, an alkoxy group, an aryl group, or An aralkyl group, provided that an alkyl group, a monovalent alicyclic hydrocarbon group, an alkoxy group, an aryl group and an aralkyl group in R ⁶ , R ⁷ , R ⁸ , R ^A , R ^B and R ^C A part or all of them may be substituted, and p, q and r are each independently an integer of 0 to 5. When R ⁶ , R ⁷ and R ⁸ are plural, plural R ⁶ , R ⁷ and R ⁸ may be the same or different. [A] The polymer has a structural unit (I-1) represented by the following formula (4), and the content ratio of the structural unit (I-1) to all structural units constituting the [A] polymer is 40. The photoresist composition according to any one of claims 1 to 5, which has a mol% or more and 70 mol% or less.

(In formula (4), R ^a Is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ^p Is an acid dissociable group represented by the following formula (i). )

(In formula (i), R ^p1 , R ^p2 And R ^p3 Are each independently an alkyl group having 1 to 4 carbon atoms or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms. However, R ^p2 And R ^p3 May combine with each other to form a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms together with the carbon atom to which they are bonded. ) The photoresist composition according to any one of claims 1 to 6, which is used for forming a trench pattern. (1) A step of applying the photoresist composition according to any one of claims 1 to 7 on a substrate to form a resist film;
(2) A resist pattern forming method including a step of exposing the resist film through a photomask, and (3) a step of developing the exposed resist film. The method for forming a resist pattern according to claim 8 , wherein a trench pattern is formed.