JP6036545B2 - Photoresist composition, resist pattern forming method, polymer and compound - Google Patents

Description

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

  With the miniaturization of various electronic device structures such as semiconductor devices and liquid crystal devices, further miniaturization of resist patterns in the lithography process is required, and various photoresist compositions are being studied. Such a photoresist composition generates an acid in an exposed part by irradiation with exposure light such as deep ultraviolet light such as ArF excimer laser, extreme ultraviolet light (EUV), electron beam, and the like. A difference is caused in the dissolution rate of the unexposed portion with respect to the developer, and a resist pattern is formed on the substrate.

  Such a photoresist is required to be able to form a resist pattern that is excellent in sensitivity and resolution and excellent in adhesion to the substrate. In order to satisfy this requirement, the introduction of various polar groups into the polymer in the photoresist composition has been studied, and by introducing a lactone ring such as a norbornane lactone ring or a γ-butyrolactone ring, sensitivity, resolution, etc. It is known that adhesion can be improved while maintaining goodness (see Japanese Patent Application Laid-Open Nos. 2000-26446, 2000-159758, 10-2007069, and 10-274852). )

  However, at present, when the miniaturization of the resist pattern has progressed to a level of 40 nm or less, the above-mentioned photoresist composition has not only excellent resolution and adhesion but also EL (Exposure). It is required to have excellent latitude (exposure margin) performance, LWR (Line Width Roughness) performance, and CDU (Critical Dimension Uniformity) performance, and a high-precision pattern can be formed with a high yield. . However, the above conventional photoresist composition cannot satisfy these performances.

JP 2000-26446 A JP 2000-159758 A JP-A-10-207069 JP-A-10-274852

  This invention is made | formed based on the above situations, The objective is to provide the photoresist composition which is excellent in EL performance, LWR performance, and CDU performance.

（式（１）中、Ｒ^１は、水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。Ｒ^２及びＲ^３は、Ｒ^２が置換又は非置換の炭素数１〜３０の１価の炭化水素基であり、かつＲ^３が水素原子若しくは炭素数１〜３０の１価の炭化水素基であるか、又はＲ^２及びＲ^３が互いに合わせられこれらが結合する炭素原子と共に構成される炭素数３〜２０の脂環構造を表す。Ｒ^４は、炭素数１〜１０の１価の鎖状炭化水素基又は炭素数３〜２０の１価の脂環式炭化水素基である。Ｒ^５は、炭素数１〜６の１価の鎖状炭化水素基又は炭素数３〜１５の１価の脂環式炭化水素基である。ｐ及びｑは、それぞれ独立して、０〜３の整数である。但し、ｐ＋ｑは、２以上６以下である。ｒは、０〜４の整数である。ｒが２以上の場合、複数のＲ^５は同一でも異なっていてもよい。） The invention made to solve the above problems is
[A] A photoresist composition containing a structural unit (I) represented by the following formula (1) (hereinafter also referred to as “[A] polymer”), and [B] a photoresist composition containing an acid generator. is there.

(In Formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² and R ³ are monovalent having 1 to 30 carbon atoms in which R ² is substituted or unsubstituted. And R ³ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 30 carbon atoms, or R ² and R ³ are combined with each other and configured together with the carbon atom to which they are bonded. R ⁴ represents a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. ⁵ is a monovalent chain hydrocarbon group having 1 to 6 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms, p and q are each independently 0 to 3 P + q is 2 or more and 6 or less, r is an integer of 0 to 4. When r is 2 or more, a plurality of R ⁵ may be the same or different.)

The resist pattern forming method of the present invention comprises:
A step of forming a resist film using the photoresist composition;
A step of exposing the resist film; and a step of developing the exposed resist film.

（式（１）中、Ｒ^１は、水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。Ｒ^２及びＲ^３は、Ｒ^２が置換又は非置換の炭素数１〜３０の１価の炭化水素基であり、かつＲ^３が水素原子若しくは炭素数１〜３０の１価の炭化水素基であるか、又はＲ^２及びＲ^３が互いに合わせられこれらが結合する炭素原子と共に構成される炭素数３〜２０の脂環構造を表す。Ｒ^４は、炭素数１〜１０の１価の鎖状炭化水素基又は炭素数３〜２０の１価の脂環式炭化水素基である。Ｒ^５は、炭素数１〜６の１価の鎖状炭化水素基又は炭素数３〜１５の１価の脂環式炭化水素基である。ｐ及びｑは、それぞれ独立して、０〜３の整数である。但し、ｐ＋ｑは、２以上６以下である。ｒは、０〜４の整数である。ｒが２以上の場合、複数のＲ^５は同一でも異なっていてもよい。） The polymer of the present invention has a structural unit (I) represented by the following formula (1).

(In Formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² and R ³ are monovalent having 1 to 30 carbon atoms in which R ² is substituted or unsubstituted. And R ³ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 30 carbon atoms, or R ² and R ³ are combined with each other and configured together with the carbon atom to which they are bonded. R ⁴ represents a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. ⁵ is a monovalent chain hydrocarbon group having 1 to 6 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms, p and q are each independently 0 to 3 P + q is 2 or more and 6 or less, r is an integer of 0 to 4. When r is 2 or more, a plurality of R ⁵ may be the same or different.)

（式（ｉ）中、Ｒ^１は、水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。Ｒ^２及びＲ^３は、Ｒ^２が置換又は非置換の炭素数１〜３０の１価の炭化水素基であり、かつＲ^３が水素原子若しくは炭素数１〜３０の１価の炭化水素基であるか、又はＲ^２及びＲ^３が互いに合わせられこれらが結合する炭素原子と共に構成される炭素数３〜２０の脂環構造を表す。Ｒ^４は、炭素数１〜１０の１価の鎖状炭化水素基又は炭素数３〜２０の１価の脂環式炭化水素基である。Ｒ^５は、炭素数１〜６の１価の鎖状炭化水素基又は炭素数３〜１５の１価の脂環式炭化水素基である。ｐ及びｑは、それぞれ独立して、０〜３の整数である。但し、ｐ＋ｑは、２以上６以下である。ｒは、０〜４の整数である。ｒが２以上の場合、複数のＲ^５は同一でも異なっていてもよい。） The compound of the present invention is represented by the following formula (i).

(In the formula (i), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² and R ³ are monovalent having 1 to 30 carbon atoms in which R ² is substituted or unsubstituted. And R ³ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 30 carbon atoms, or R ² and R ³ are combined with each other and configured together with the carbon atom to which they are bonded. R ⁴ represents a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. ⁵ is a monovalent chain hydrocarbon group having 1 to 6 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms, p and q are each independently 0 to 3 P + q is 2 or more and 6 or less, r is an integer of 0 to 4. When r is 2 or more, a plurality of R ⁵ may be the same or different.)

  Here, the “hydrocarbon group” includes a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The “hydrocarbon group” may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The “chain hydrocarbon group” refers to a hydrocarbon group that does not include a cyclic structure but includes only a chain structure, and includes both a linear hydrocarbon group and a branched hydrocarbon group. The term “alicyclic hydrocarbon group” refers to a hydrocarbon group that includes only an alicyclic structure as a ring structure and does not include an aromatic ring structure, and includes a monocyclic alicyclic hydrocarbon group and a polycyclic alicyclic group. Includes both hydrocarbon groups. However, it is not necessary to be composed only of the alicyclic structure, and a part thereof may include a chain structure. “Aromatic hydrocarbon group” refers to a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it is not necessary to be composed only of an aromatic ring structure, and a part thereof may include a chain structure or an alicyclic structure.

  According to the photoresist composition and the resist pattern forming method of the present invention, a resist pattern having a small LWR and CDU can be formed while exhibiting a wide EL. The polymer of the present invention can be suitably used as a polymer component of the photoresist composition. The compound of the present invention can be suitably used as a raw material monomer for the polymer. Accordingly, these can be suitably used for manufacturing semiconductor devices that are expected to be further miniaturized in the future.

<Photoresist composition>
The photoresist composition contains a [A] polymer and a [B] acid generator. According to the photoresist composition, a resist pattern with small LWR and CDU can be formed while exhibiting a wide EL.

The photoresist composition may contain [C] acid diffusion controller, [D] fluorine atom-containing polymer (hereinafter also referred to as “[D] polymer”), and [E] solvent as suitable components. In addition, other optional components may be contained as long as the effects of the present invention are not impaired.
Hereinafter, each component will be described.

<[A] polymer>
[A] The polymer is a polymer having the structural unit (I). The said photoresist composition is excellent in EL performance, LWR performance, and CDU performance because the [A] polymer has the structural unit (I).
The reason why the photoresist composition has the above-described configuration and exhibits the above-mentioned effects is not necessarily clear, but can be inferred as follows, for example. That is, in the structural unit (I), a 5- to 9-membered lactone ring is bonded to a polymer chain via an ester group and one carbon atom, and the carbon atom and a lactone adjacent to the carbon atom. It has a specific structure in which at least one hydrocarbon group or the like is bonded to a ring carbon atom. In this way, the lactone ring has an appropriate distance from the polymer chain, and the movement of the side chain containing the lactone ring is appropriately limited by the three-dimensional structure, thereby having the structural unit (I) [ A] The polymer is considered to have moderate polarity and rigidity, and exhibits suitable solubility in a developer. As a result, the photoresist composition has improved EL performance, LWR performance, and CDU performance.

[A] The polymer preferably has, in addition to the structural unit (I), a structural unit (II) represented by the following formula (2), which is a structural unit other than the structural unit (I) and is a lactone You may have structural unit (III) containing at least 1 sort (s) chosen from the group which consists of a structure, a cyclic carbonate structure, and a sultone structure. Moreover, you may have other structural units other than structural unit (I)-(III). [A] The polymer may have one or more of the above structural units.
Hereinafter, each structural unit will be described.

[Structural unit (I)]
The structural unit (I) is represented by the following formula (1).

In said formula (1), R < ¹ > is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ² and ^{R 3} is a monovalent hydrocarbon group ^{R 2} is a substituted or unsubstituted 1 to 30 carbon atoms, and a monovalent hydrocarbon group ^{R 3} is a hydrogen atom or a C1-30 Or represents an alicyclic structure of 3 to 20 carbon atoms constituted by R ² and R ³ being combined with each other and the carbon atom to which they are bonded. R ⁴ is a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. R ⁵ is a monovalent chain hydrocarbon group having 1 to 6 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms. p and q are each independently an integer of 0 to 3. However, p + q is 2 or more and 6 or less. r is an integer of 0-4. When r is 2 or more, the plurality of R ⁵ may be the same or different.

R ¹ is preferably a hydrogen atom or a methyl group, more preferably a methyl group, from the viewpoint of copolymerization of the monomer that gives the structural unit (I).

Examples of the monovalent hydrocarbon group having 1 to 30 carbon atoms represented by R ² and R ³ include a monovalent chain hydrocarbon group having 1 to 30 carbon atoms and a monovalent hydrocarbon group having 3 to 30 carbon atoms. Examples thereof include an alicyclic hydrocarbon group and a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms.

Examples of the monovalent chain hydrocarbon group having 1 to 30 carbon atoms include:
Alkyl groups such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group;
An alkenyl group such as an ethenyl group, a propenyl group, a butenyl group;
Examples thereof include alkynyl groups such as ethynyl group, propynyl group and butynyl group.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 30 carbon atoms include:
Monocyclic cycloalkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetracyclododecyl group;
A monocyclic cycloalkenyl group such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, a cyclooctenyl group;
And polycyclic cycloalkenyl groups such as a norbornenyl group, a tricyclodecenyl group, and a tetracyclododecenyl group.

Examples of the monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms include:
Aryl groups such as phenyl, tolyl, xylyl, mesityl, naphthyl, anthryl;
Examples thereof include aralkyl groups such as a benzyl group, a phenethyl group, a phenylpropyl group, a naphthylmethyl group, and an anthrylmethyl group.

Examples of the substituent for substituting the hydrocarbon group for R ² include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, hydroxy group, carboxy group, amino group, cyano group, nitro group and alkoxy group. , An alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, an acyloxy group, and the like.

Examples of the alicyclic structure having 3 to 20 carbon atoms configured together with the carbon atom to which R ² and R ³ are combined with each other include a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, and cycloheptane. Examples include a structure, a cyclooctane structure, a norbornane structure, an adamantane structure, and a structure having a group containing a hetero atom such as an oxygen atom, a nitrogen atom, or a sulfur atom between carbon and carbon in these structures.

R ² is preferably an unsubstituted monovalent hydrocarbon group from the viewpoint of improving the EL performance, LWR performance and CDU performance of the photoresist composition, and is preferably a monovalent chain hydrocarbon group or monovalent fat. A cyclic hydrocarbon group is more preferable, an alkyl group and a cycloalkyl group are more preferable, an alkyl group having 1 to 6 carbon atoms and a cycloalkyl group having 3 to 8 carbon atoms are particularly preferable, and an alkyl group having 1 to 6 carbon atoms is preferable. Furthermore, a methyl group and a cyclohexyl group are most preferable.

R ³ is preferably a hydrogen atom or a monovalent chain hydrocarbon group, more preferably a hydrogen atom, from the viewpoint of improving the EL performance, LWR performance, and CDU performance of the photoresist composition. Further, when R ³ is a hydrogen atom, the synthesis of the monomer giving the structural unit (I) is facilitated.

As a combination of R ² and R ³ , R ² is preferably a monovalent chain hydrocarbon group or a monovalent alicyclic hydrocarbon group, and R ³ is a hydrogen atom or a monovalent chain hydrocarbon group. ² is more preferably a C 1-6 alkyl group or a C 3-8 cycloalkyl group, and R ³ is more preferably a hydrogen atom, R ² is a C 1-6 alkyl group, and R ³ is more preferably a hydrogen atom. R ² is particularly preferably a methyl group and R ³ is preferably a hydrogen atom. By combining R ² and R ³ as described above, and making the bulkiness of these groups moderate, it is considered that the rigidity of the [A] polymer becomes more moderate, and as a result, the EL performance of the photoresist composition, LWR performance and CDU performance can be further improved.

Examples of the monovalent chain hydrocarbon group having 1 to 10 carbon atoms represented by R ⁴ include those having 1 to 10 carbon atoms among the chain hydrocarbon groups exemplified as R ² and R ³ above. Is mentioned.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ⁴ include those having 3 to 20 carbon atoms among the alicyclic hydrocarbon groups exemplified as R ² and R ³ above. Etc.

R ⁴ is preferably a monovalent chain hydrocarbon group, more preferably a chain hydrocarbon group having 1 to 5 carbon atoms, still more preferably an alkyl group having 1 to 5 carbon atoms, a methyl group, an ethyl group, n A -propyl group and an i-propyl group are particularly preferable, and a methyl group is particularly preferable.

As a combination of R ² , R ³ and R ⁴ , R ² is a monovalent chain hydrocarbon group or monovalent alicyclic hydrocarbon group, R ³ is a hydrogen atom and R ⁴ is a monovalent chain carbon group. A hydrogen group is preferable, R ² is an alkyl group having 1 to 6 carbon atoms or a cycloalkyl group having 3 to 8 carbon atoms, R ³ is a hydrogen atom and R ⁴ is an alkyl group having 1 to 5 carbon atoms, and R ² Is more preferably a methyl group or a cyclohexyl group, R ³ is a hydrogen atom and R ⁴ is a methyl group, an ethyl group or an i-propyl group, R ² is a methyl group, R ³ is a hydrogen atom and R ⁴ is a methyl group, an ethyl group Or an i-propyl group is particularly preferable. By combining R ² , R ^3, and R ⁴ with the above combination, it is considered that the rigidity of the [A] polymer becomes more moderate due to appropriate steric hindrance between these groups, and as a result, the photoresist composition The EL performance, LWR performance and CDU performance of the product can be further improved.

Examples of the monovalent chain hydrocarbon group having 1 to 6 carbon atoms represented by R ⁵ include those having 1 to 6 carbon atoms among the chain hydrocarbon groups exemplified as R ² and R ³ above. Is mentioned.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms represented by R ⁵ include those having 3 to 15 carbon atoms among the alicyclic hydrocarbon groups exemplified as R ² and R ³ above. Etc.

R ⁵ is preferably a monovalent chain hydrocarbon group, more preferably a chain hydrocarbon group having 1 to 3 carbon atoms, and still more preferably a methyl group or an ethyl group.

p is preferably an integer of 1 to 3, more preferably 1 or 2, and still more preferably 2.
q is preferably an integer of 0 to 2, more preferably 0 or 1, and still more preferably 0.
As p + q, 2 or more and 5 or less are preferable, 2 or 3 is more preferable, and 2 is more preferable.

  Examples of the structural unit (I) include structural units represented by the following formulas (1-1) to (1-12) (hereinafter also referred to as “structural units (I-1) to (I-12)”). Etc.

In the formulas (1-1) to (1-12), R ¹ has the same meaning as the formula (1).

  Among these, from the viewpoint of superior EL performance, LWR performance and CDU performance of the photoresist composition, the structural units (I-1) to (I-5) and (I-8) to (I-12) are The structural units (I-1) to (I-4) are more preferable, and the structural unit (I-1) is more preferable.

  As a minimum of the content rate of structural unit (I), 5 mol% is preferable with respect to all the structural units which comprise a [A] polymer, 10 mol% is more preferable, 20 mol% is further more preferable, 30 mol % Is particularly preferred. As an upper limit of the content rate of structural unit (I), 90 mol% is preferable, 80 mol% is more preferable, 70 mol% is further more preferable, 60 mol% is especially preferable. By making the content rate of structural unit (I) into the said range, EL performance, LWR performance, and CDU performance of the said photoresist composition can be improved.

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

In said formula (i), R < ¹ > is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ² and ^{R 3} is a monovalent hydrocarbon group ^{R 2} is a substituted or unsubstituted 1 to 30 carbon atoms, and a monovalent hydrocarbon group ^{R 3} is a hydrogen atom or a C1-30 Or represents an alicyclic structure of 3 to 20 carbon atoms constituted by R ² and R ³ being combined with each other and the carbon atom to which they are bonded. R ⁴ is a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. R ⁵ is a monovalent chain hydrocarbon group having 1 to 6 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms. p and q are each independently an integer of 0 to 3. However, p + q is 2 or more and 6 or less. r is an integer of 0-4. When r is 2 or more, the plurality of R ⁵ may be the same or different.

  Examples of the compound (i) include compounds represented by the following formulas (1m-1) to (1m-12) (hereinafter also referred to as “compounds (1m-1) to (1m-12)”). It is done.

In the above formulas (1m-1) to (1m-12), R ¹ has the same meaning as the above formula (i).

  Among these, the compounds (1m-1) to (1m-5) and (1m-8) to (1m-12) are preferable, and the structural units (1m-1) to (1m-4) are more preferable. The unit (1m-1) is more preferable.

The method for synthesizing the compound (i) is, for example, as follows when R ³ in the above formula (i) is a hydrogen atom and q is 0, and can be synthesized according to the following scheme. In other cases, it can be synthesized by the same known method.

In the above scheme, R ¹ , R ² , R ⁴ , R ⁵ , p and r are as defined in the above formula (i). Z is a halogen atom, a hydroxy group or —OCOR. R is a monovalent hydrocarbon group.

  An α-carbonyl hydrocarbon-substituted lactone compound such as α-acetyl-γ-butyrolactone is reacted with an iodinated chain hydrocarbon or iodinated alicyclic hydrocarbon such as methyl iodide in a solvent in the presence of a base. Thus, a compound in which the α-position is substituted with a chain hydrocarbon group or an alicyclic hydrocarbon group is obtained (Reaction 1). An alcohol compound is obtained by reducing this compound with sodium borohydride in a solvent (reaction 2). Compound (i) can be obtained by reacting this alcohol compound with a (meth) acryloyl compound such as (meth) acryloyl chloride in a solvent in the presence of a base (Reaction 3).

Examples of the base used in the above reaction 1 include alkali metal carbonates such as potassium carbonate and sodium carbonate; alkali metal hydrogen carbonates such as sodium hydrogen carbonate and potassium hydrogen carbonate; alkali metal hydrogen such as sodium hydride and potassium hydride. And alkali metal hydroxides such as sodium hydroxide and potassium hydroxide.
Examples of the solvent used in the above reaction 1 include alcohol solvents such as methanol and ethanol; ether solvents such as diethyl ether, tetrahydrofuran, tetrahydropyran, and dioxane; ketone solvents such as acetone, 2-butanone, and methyl isobutyl ketone; Amide solvents such as N, N-dimethylformamide and N, N-dimethylacetamide; ester solvents such as methyl acetate and ethyl acetate; hydrocarbon solvents such as hexane, cyclohexane and benzene; halogenation such as methylene chloride and chloroform Hydrocarbon solvents; water and the like. One or two or more of these solvents may be used.

  Examples of the solvent used in the reaction 2 include alcohol solvents such as methanol and ethanol; ether solvents such as diethyl ether, tetrahydrofuran, tetrahydropyran, and dioxane; N, N-dimethylformamide, N, N-dimethylacetamide, and the like. Amide solvents; hydrocarbon solvents such as hexane, cyclohexane and benzene; halogenated hydrocarbon solvents such as methylene chloride and chloroform; water and the like. One or two or more of these solvents may be used.

Examples of the base used in the above reaction 3 include chain amine compounds such as diethylamine and triethylamine; cyclic amine compounds such as pyrrolidine and piperidine; and pyridine compounds such as pyridine and dimethylaminopyridine.
Examples of the solvent used in the above reaction 3 include ether solvents such as diethyl ether, tetrahydrofuran, tetrahydropyran and dioxane; ketone solvents such as acetone, 2-butanone and methyl isobutyl ketone; N, N-dimethylformamide, N, Amide solvents such as N-dimethylacetamide; ester solvents such as methyl acetate and ethyl acetate; hydrocarbon solvents such as hexane, cyclohexane and benzene; halogenated hydrocarbon solvents such as methylene chloride and chloroform; acetonitrile and water Is mentioned. One or two or more of these solvents may be used.

[Structural unit (II)]
The structural unit (II) is a structural unit represented by the following formula (2). The group represented by —CR ⁷ R ⁸ R ⁹ in the structural unit (II) is an acid dissociable group. The “acid-dissociable group” refers to a group that substitutes a hydrogen atom of a carboxy group and is dissociated by the action of an acid. In the photoresist composition, since the [A] polymer has the structural unit (II), sensitivity and resolution are improved, and as a result, EL performance, LWR performance, and CDU performance can be improved.

In the formula (2), R ⁶ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Y is a single bond, a carbonyloxycycloalkanediyl group having 3 to 20 carbon atoms, or a carbonyloxycycloalkanediyloxy group having 3 to 20 carbon atoms. R ⁷ is a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. R ⁸ and R ⁹ are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or these groups. Represents an alicyclic structure having 3 to 20 carbon atoms that is configured together with the carbon atoms to which they are bonded to each other.

Examples of the carbonyloxycycloalkanediyl group having 3 to 20 carbon atoms represented by Y include, for example,
Monocyclic carbonyloxycycloalkanediyl groups such as carbonyloxycyclopropanediyl group, carbonyloxycyclobutanediyl group, carbonyloxycyclopentanediyl group, carbonyloxycyclohexanediyl group;
Examples thereof include a polycyclic carbonyloxycycloalkanediyl group such as a carbonyloxynorbornanediyl group, a carbonyloxyadamantanediyl group, a carbonyloxytricyclodecanediyl group, and a carbonyloxytetracyclododecanediyl group.

Examples of the carbonyloxycycloalkanediyloxy group having 3 to 20 carbon atoms represented by Y include, for example,
Monocyclic carbonyloxycycloalkanediyloxy groups such as carbonyloxycyclopropanediyloxy group, carbonyloxycyclobutanediyloxy group, carbonyloxycyclopentanediyloxy group, carbonyloxycyclohexanediyloxy group;
Examples thereof include polycyclic carbonyloxycycloalkanediyloxy groups such as carbonyloxynorbornanediyloxy group, carbonyloxyadamantanediyloxy group, carbonyloxytricyclodecanediyloxy group, and carbonyloxytetracyclododecandiyloxy group.

  Y is preferably a single bond or a carbonyloxycycloalkanediyloxy group having 3 to 20 carbon atoms, more preferably a single bond or a polycyclic carbonyloxycycloalkanediyloxy group, and even more preferably a single bond.

R ⁶ is preferably a hydrogen atom or a methyl group, and more preferably a methyl group, from the viewpoint of copolymerization of the monomer that gives the structural unit (II).

Examples of the monovalent chain hydrocarbon group having 1 to 10 carbon atoms represented by R ⁷ , R ⁸ and R ⁹ include, for example,
Alkyl groups such as methyl group, ethyl group, n-propyl group, i-propyl group;
An alkenyl group such as an ethenyl group, a propenyl group, a butenyl group;
Examples thereof include alkynyl groups such as ethynyl group, propynyl group, and butynyl group.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above R ⁷ , R ⁸ and R ⁹ include:
Monocyclic cycloalkyl groups such as a cyclopentyl group and a cyclohexyl group;
A monocyclic cycloalkenyl group such as a cyclopentenyl group and a cyclohexenyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group and a tricyclodecyl group;
And polycyclic cycloalkenyl groups such as a norbornenyl group and a tricyclodecenyl group.

Examples of the alicyclic structure having 3 to 20 carbon atoms constituted and represented together with the carbon atom to which these groups are combined with each other include, for example,
Monocyclic cycloalkane structures such as cyclopropane structure, cyclobutane structure, cyclopentane structure, cyclohexane structure, cycloheptane structure, cyclooctane structure;
Examples thereof include polycyclic cycloalkane structures such as a norbornane structure, an adamantane structure, a tricyclodecane structure, and a tetracyclododecane structure.

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

R < ⁶ > -R < ⁹ > is synonymous with the said Formula (2) in said Formula (2-1)-(2-6). h, i, and j are each independently an integer of 1 to 4.

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

In said formula, R < ⁶ > is synonymous with the said Formula (2).

  As the structural unit (II), the structural unit (II-1), the structural unit (II-2) and the structural unit (II-5) are preferable, and the structural unit derived from 1-alkyl-1-cyclopentyl (meth) acrylate Structural units derived from 2-alkyl-2-adamantyl (meth) acrylate and structural units derived from 3- (t-alkyloxycarbonyloxy) adamantyl-1-yl (meth) acrylate are preferred.

  As a content rate of structural unit (II), 10 mol%-80 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 20 mol%-75 mol% are more preferable, 30 mol% -70 mol% is further more preferable, and 40 mol%-65 mol% is especially preferable. By making the said content rate into the said range, the sensitivity and resolution of the said photoresist composition improve more, and as a result, EL performance, LWR performance, and CDU performance improve. When the said content rate is less than the said minimum, the pattern formation property of the said photoresist composition may fall. When the said content rate exceeds the said upper limit, the adhesiveness to the board | substrate of a resist pattern may fall.

[Structural unit (III)]
The structural unit (III) is a structural unit other than the structural unit (I) and includes at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. [A] The polymer further includes the structural unit (III) in addition to the structural unit (I), so that the solubility in the developer can be further adjusted. EL performance, LWR performance and CDU performance can be improved. Moreover, the adhesiveness of the resist pattern formed from the said photoresist composition and a board | substrate can be improved.

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

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

  Among these, the structural unit (III) is preferably a structural unit containing a norbornane lactone structure, a structural unit containing a γ-butyrolactone structure, a structural unit containing an ethylene carbonate structure, or a structural unit containing a norbornane sultone structure.

  As a content rate of structural unit (III), 0 mol%-70 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 0 mol%-60 mol% are more preferable, 20 mol% More preferred is ˜55 mol%. By making the said content rate into the said range, the adhesiveness to the board | substrate of the resist pattern formed from the said photoresist composition can be improved more.

[Other structural units]
[A] The polymer may have other structural units other than the structural units (I) to (III). Examples of other structural units include structural units containing a hydroxy group.

  Examples of the structural unit containing a hydroxy group include a structural unit represented by the following formula.

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

  As a content rate of the structural unit containing the said hydroxyl group, 30 mol% or less is preferable with respect to all the structural units which comprise a [A] polymer, 20 mol% or less is preferable, and 3 mol%-15 mol% are preferable. Further preferred. When the said content rate exceeds the said upper limit, the pattern formation property of the said photoresist composition may fall.

  [A] The polymer may have other structural units in addition to the above structural units. As a content rate of the said other structural unit, 20 mol% or less is preferable and 10 mol% or less is more preferable.

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

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

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

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

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

  [A] The weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is not particularly limited, but is preferably 1,000 or more and 50,000 or less, more preferably 2,000 or more and 30,000 or less. Preferably, 3,000 or more and 20,000 or less are more preferable, and 5,000 or more and 15,000 are particularly preferable. [A] By making Mw of a polymer into the said range, the applicability | paintability and development defect inhibitory property of the said photoresist composition improve. [A] If the Mw of the polymer is less than the lower limit, a resist film having sufficient heat resistance may not be obtained. [A] If the Mw of the polymer exceeds the above upper limit, the developability of the resist film may deteriorate.

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

Mw and Mn of the polymer in this specification are values measured using gel permeation chromatography (GPC) under the following conditions.
GPC column: 2 G2000HXL, 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 a substance that generates an acid upon exposure. Since the acid-dissociable group of the [A] polymer or the like is dissociated by the generated acid to generate a carboxy group or the like, and the solubility of the [A] polymer in the developer containing the organic solvent is reduced, A negative resist pattern can be formed from the photoresist composition. The content of the [B] acid generator in the photoresist composition is, for example, a low molecular compound form (hereinafter referred to as “ [B] also referred to as “acid generator”), in the form of acid generating groups incorporated as part of the polymer, or in both forms.

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

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

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

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

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

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

  [B] The acid generator is preferably a compound represented by the following formula (3). [B] When the acid generator has the following structure, the diffusion length of the acid generated by exposure in the resist film is appropriately shortened by the interaction with the structural unit (I) of the polymer [A]. As a result, the EL performance, LWR performance and CDU performance of the photoresist composition can be improved.

In the above formula (3), R ¹⁰ is a monovalent group containing an alicyclic structure having 7 or more ring members or a monovalent group containing an aliphatic heterocyclic structure having 7 or more ring members. R ¹¹ is a fluorinated alkanediyl group having 1 to 10 carbon atoms. X ⁺ is a monovalent photodegradable onium cation.

The “number of ring members” in R ¹⁰ refers to the number of atoms constituting the ring of the alicyclic structure and the aliphatic heterocyclic structure. In the case of the polycyclic alicyclic structure and the polycyclic aliphatic heterocyclic structure, The number of atoms that make up the ring.

Examples of the monovalent group containing an alicyclic structure having 7 or more ring members represented by R ¹⁰ include:
A monocyclic cycloalkyl group such as a cyclooctyl group, a cyclononyl group, a cyclodecyl group, a cyclododecyl group;
A monocyclic cycloalkenyl group such as a cyclooctenyl group and a cyclodecenyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetracyclododecyl group;
And polycyclic cycloalkenyl groups such as a norbornenyl group and a tricyclodecenyl group.

Examples of the monovalent group containing an aliphatic heterocyclic structure having 7 or more ring members represented by R ¹⁰ include:
A group containing a lactone structure such as a norbornanelactone-yl group;
A group containing a sultone structure such as a norbornane sultone-yl group;
An oxygen atom-containing heterocyclic group such as an oxacycloheptyl group and an oxanorbornyl group;
Nitrogen atom-containing heterocyclic groups such as azacycloheptyl group and diazabicyclooctane-yl group;
And sulfur atom-containing heterocyclic groups such as a thiacycloheptyl group and a thianorbornyl group.

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

R ¹⁰ is preferably a monovalent group containing an alicyclic structure having 9 or more ring members, or a monovalent group containing an aliphatic heterocyclic structure having 9 or more ring members, such as an adamantyl group or a hydroxyadamantyl group. , A norbornanelactone-yl group, and a 5-oxo-4-oxatricyclo [4.3.1.1 ^3,8 ] undecan-yl group are more preferable, and an adamantyl group is more preferable.

Examples of the fluorinated alkanediyl group having 1 to 10 carbon atoms represented by R ¹¹ include one of hydrogen atoms of an alkanediyl group having 1 to 10 carbon atoms such as a methanediyl group, an ethanediyl group, and a propanediyl group. Examples include groups in which the above is substituted with a fluorine atom.
Among these, SO ₃ ^- fluorinated alkane diyl group which has a fluorine atom to carbon atom is bonded to adjacent groups are preferred, SO ₃ ^- 2 fluorine atoms to the carbon atom adjacent to the group is attached More preferred are fluorinated alkanediyl groups, 1,1-difluoromethanediyl group, 1,1-difluoroethanediyl group, 1,1,3,3,3-pentafluoro-1,2-propanediyl group, 1,1 1,2,2-tetrafluoroethanediyl group, 1,1,2,2-tetrafluorobutanediyl group, and 1,1,2,2-tetrafluorohexanediyl group are more preferable.

The monovalent photodegradable onium cation represented by X ⁺ is a cation that decomposes upon exposure to exposure light. In the exposed portion, sulfonic acid is generated from protons generated by the decomposition of the photodegradable onium cation and a sulfonate anion. Examples of the monovalent photodegradable onium cation represented by X ⁺ include elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi. And radiation-decomposable onium cations. Examples of the cation containing S (sulfur) as an element include a sulfonium cation and a tetrahydrothiophenium cation. Examples of the cation containing I (iodine) as an element include an iodonium cation. Among these, a sulfonium cation represented by the following formula (X-1), a tetrahydrothiophenium cation represented by the following formula (X-2), and an iodonium cation represented by the following formula (X-3) preferable.

In the above formula (X-1), R ^a1 , R ^a2 and R ^a3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, substituted or unsubstituted. aromatic hydrocarbon group having 6 to 12 carbon atoms, a or a -OSO ₂ -R ^P or _-SO 2 -R ^Q, or two or more are combined with each other configured ring of these groups . R ^P and R ^Q are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms. Or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2 and k3 are each independently an integer of 0 to 5. R ^a1 to R ^a3 and when ^{R P} and ^{R Q} are a plurality each of the plurality of ^R a1 ^{to R a3} and ^{R P} and ^{R Q} may be the same as or different from each other.
In the above formula (X-2), R ^b1 represents a substituted or unsubstituted linear or branched alkyl group having 1 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon having 6 to 8 carbon atoms. It is a group. k4 is an integer of 0-7. If R ^b1 is plural, the plurality of R ^b1 may be the same or different, and plural R ^b1 may represent a constructed ring aligned with each other. R ^b2 is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. k5 is an integer of 0-6. If R ^b2 is plural, the plurality of R ^b2 may be the same or different, and plural R ^b2 may represent a keyed configured ring structure. t is an integer of 0-3.
In the above formula (X-3), R ^c1 and R ^c2 each independently represent a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number of 6 12 aromatic hydrocarbon group, or an -OSO ₂ -R ^R or _-SO 2 -R ^S, or two or more are combined with each other configured ring of these groups. R ^R and R ^S are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms. Or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k6 and k7 are each independently an integer of 0 to 5. R ^{c1, R} c2, ^R when ^R and ^{R S} is plural respective plurality of ^{R c1,} R c2, ^{R R} and ^{R S} may have respectively the same or different.

Examples of the unsubstituted linear alkyl group represented by R ^{a1 to} R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include a methyl group, an ethyl group, an n-propyl group, and n-butyl. Groups and the like.
Examples of the unsubstituted branched alkyl group represented by R ^{a1 to} R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include an i-propyl group, an i-butyl group, a sec-butyl group, Examples include t-butyl group.
Examples of the unsubstituted aromatic hydrocarbon group represented by R ^{a1 to} R ^a3 , R ^c1, and R ^c2 include aryl groups such as phenyl group, tolyl group, xylyl group, mesityl group, and naphthyl group; benzyl group And aralkyl groups such as a phenethyl group.
Examples of the unsubstituted aromatic hydrocarbon group represented by R ^b1 and R ^b2 include a phenyl group, a tolyl group, and a benzyl group.

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

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

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

  Examples of the acid generator represented by the above formula (3) include compounds represented by the following formulas (3-1) to (3-11) (hereinafter referred to as “compounds (3-1) to (3-11)”. ) ")) And the like.

  [B] Among these, as the acid generator, an onium salt compound is preferable, a sulfonium salt is more preferable, a sulfonium salt having an anion containing an adamantane structure is more preferable, and the compound (3-2) and the compound (3- 3) and the compound (3-11) are more preferable.

  [B] As the content of the acid generator, when the [B] acid generator is a [B] acid generator, the [A] polymer 100 is used from the viewpoint of ensuring the sensitivity and developability of the photoresist composition. 0.1 parts by weight or more and 30 parts by weight or less are preferable, 0.5 parts by weight or more and 20 parts by weight or less are more preferable, 1 part by weight or more and 15 parts by weight or less are more preferable, and 3 parts by weight or more and 15 parts by weight or less. Part by mass is particularly preferred. [B] By making content of an acid generator into the said range, the sensitivity and developability of the said photoresist composition improve. [B] 1 type (s) or 2 or more types can be used for an acid generator.

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

  [C] Examples of the acid diffusion controller include a compound represented by the following formula (4) (hereinafter also referred to as “nitrogen-containing compound (I)”), a compound having two nitrogen atoms in the same molecule (hereinafter referred to as “nitrogen-containing compound (I)”). , “Nitrogen-containing compound (II)”, compounds having three nitrogen atoms (hereinafter also referred to as “nitrogen-containing compound (III)”), amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, etc. Can be mentioned.

In the above formula (4), R ¹² , R ¹³ and R ¹⁴ are each independently a hydrogen atom, an optionally substituted linear, branched or cyclic alkyl group, aryl group or aralkyl group. .

  Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; aromatic amines such as aniline. Can be mentioned.

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

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

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

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

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

  Moreover, the compound which has an acid dissociable group can also be used as said nitrogen-containing organic compound. Examples of the nitrogen-containing organic compound having such an acid dissociable group include Nt-butoxycarbonylpiperidine, Nt-butoxycarbonylimidazole, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl- 2-phenylbenzimidazole, N- (t-butoxycarbonyl) di-n-octylamine, N- (t-butoxycarbonyl) diethanolamine, N- (t-butoxycarbonyl) dicyclohexylamine, N- (t-butoxycarbonyl) Examples thereof include diphenylamine, Nt-butoxycarbonyl-4-hydroxypiperidine, Nt-amyloxycarbonyl-4-hydroxypiperidine and the like.

  Further, as the [C] acid diffusion control agent, a photodegradable base that is exposed to light and generates a weak acid by exposure can also be used. Examples of the photodegradable base include an onium salt compound that decomposes upon exposure and loses acid diffusion controllability. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (5-1), an iodonium salt compound represented by the following formula (5-2), and the like.

In the above formulas (5-1) and (5-2), R ^{15 to} R ¹⁹ are each independently a hydrogen atom, an alkyl group, an alkoxy group, a hydroxy group, or a halogen atom. E ⁻ and Q ⁻ are each independently an anion represented by OH ⁻ , R ^β —COO ⁻ , R ^β —SO ₃ ^— or the following formula (5-3). However, R ( ^beta) is an alkyl group, an aryl group, or an aralkyl group.

In the above formula (5-3), R ²⁰ represents a linear or branched alkyl group having 1 to 12 carbon atoms in which part or all of the hydrogen atoms may be substituted with fluorine atoms, or 1 carbon atom. It is a -12 linear or branched alkoxyl group. u is an integer of 0-2.

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

  Of these, the photodegradable base is preferably a sulfonium salt, more preferably a triarylsulfonium salt, further preferably triphenylsulfonium salicylate, triphenylsulfonium 10-camphor sulfonate, and triphenylsulfonium 10-camphor. Sulfonate is particularly preferred.

  [C] The content of the acid diffusion controller is 0 to 20 parts by mass with respect to 100 parts by mass of the polymer [A] when the [C] acid diffusion controller is a [C] acid diffusion controller. Preferably, 0.1 mass part-15 mass parts are more preferable, 0.3 mass part-10 mass parts are more preferable, 0.5 mass part-5 mass parts are especially preferable. [C] When the content of the acid diffusion controller exceeds the above upper limit, the sensitivity of the photoresist composition may decrease.

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

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

[D] The fluorine atom content of the polymer is preferably 1% by mass or more, more preferably 2% by mass to 60% by mass, further preferably 4% by mass to 40% by mass, and 7% by mass to 30% by mass. Particularly preferred. [D] If the fluorine atom content of the polymer is less than the lower limit, the hydrophobicity of the resist film surface may be lowered. The fluorine atom content (% by mass) of the polymer can be calculated from the structure of the polymer obtained by ¹³ C-NMR spectrum measurement.

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

[Structural unit (Da)]
The structural unit (Da) is a structural unit represented by the following formula (6a). [D] A polymer can adjust a fluorine atom content rate by having a structural unit (Da).

In said formula (6a), ^RD is a hydrogen atom, a methyl group, or a trifluoromethyl group. G is a single bond, an oxygen atom, a sulfur atom, —CO—O—, —SO ₂ —O—NH—, —CO—NH— or —O—CO—NH—. R ^E is a monovalent chain hydrocarbon group having 1 to 6 carbon atoms having at least one fluorine atom or a monovalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms having at least one fluorine atom. It is.

The chain hydrocarbon group having 1 to 6 carbon atoms and having at least one fluorine atom represented by R ^E, for example, a trifluoromethyl group, a 2,2,2-trifluoroethyl group, perfluoroethyl Group, 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoropropyl group, perfluoro n-propyl group, perfluoro i-propyl group, perfluoro Examples include n-butyl group, perfluoro i-butyl group, perfluoro t-butyl group, 2,2,3,3,4,4,5,5-octafluoropentyl group, perfluorohexyl group and the like.

Examples of the aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms and having at least one fluorine atom represented by R ^E, for example, monofluoromethyl cyclopentyl group, difluorocyclopentyl groups, perfluorocyclopentyl group, monofluoromethyl cyclohexyl , Difluorocyclopentyl group, perfluorocyclohexylmethyl group, fluoronorbornyl group, fluoroadamantyl group, fluorobornyl group, fluoroisobornyl group, fluorotricyclodecyl group, fluorotetracyclodecyl group and the like.

Examples of the monomer that gives the structural unit (Da) include trifluoromethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, and 2,2,2-trifluoro. Ethyloxycarbonylmethyl (meth) acrylic acid ester, perfluoroethyl (meth) acrylic acid ester, perfluoro n-propyl (meth) acrylic acid ester, perfluoro i-propyl (meth) acrylic acid ester, perfluoro n-butyl (Meth) acrylic acid ester, perfluoro i-butyl (meth) acrylic acid ester, perfluoro t-butyl (meth) acrylic acid ester, 2- (1,1,1,3,3,3-hexafluoropropyl) (Meth) acrylic acid ester, 1- (2,2,3,3,4,4,5,5-octaful Lopentyl) (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) acrylic acid ester, 1- (2,2,3,3,3-pentafluoropropyl) (meth) acrylic acid ester, monofluorocyclopentyl (meth) Acrylic acid ester, difluorocyclopentyl (meth) acrylic acid ester, perfluorocyclopentyl (meth) acrylic acid ester, monofluorocyclohexyl (meth) acrylic acid ester, difluorocyclopentyl (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) acrylic Acid ester, fluoronorbornyl (meth) acrylic acid ester, fluoroadamantyl (meth) acrylic acid ester, fluorobornyl (meth) acrylic acid ester, fluoroisobornyl Meth) acrylic acid esters, fluoro tricyclodecyl (meth) acrylate, fluoro tetracyclododecene decyl (meth) acrylic acid ester.
Among these, 2,2,2-trifluoroethyloxycarbonylmethyl (meth) acrylic acid ester is preferable.

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

[Structural unit (Db)]
The structural unit (Db) is a structural unit represented by the following formula (6b). Since the [D] polymer has a structural unit (Db) and becomes hydrophobic, the dynamic contact angle of the resist film surface formed from the photoresist composition can be further improved.

In said formula (6b), R ^<F> is a hydrogen atom, a methyl group, or a trifluoromethyl group. R ²¹ is an (s + 1) -valent hydrocarbon group having 1 to 20 carbon atoms, and an oxygen atom, a sulfur atom, —NR′—, a carbonyl group, —CO—O—, or a terminal at the R ²² side of R ²¹ Also includes a structure in which —CO—NH— is bonded. R ′ is a hydrogen atom or a monovalent organic group. R ²² is a single bond, a divalent chain hydrocarbon group having 1 to 10 carbon atoms, or a divalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms. X ² is a divalent chain hydrocarbon group having 1 to 20 carbon atoms and having at least one fluorine atom. A ¹ is an oxygen atom, —NR ″ —, —CO—O— *, or —SO ₂ —O— *. R ″ is a hydrogen atom or a monovalent organic group. * ^Indicates a binding site that binds to ^{R 21.} R ²³ is a hydrogen atom or a monovalent organic group. s is an integer of 1 to 3. However, when s is 2 or 3, a plurality of R ²² , X ² , A ¹ and R ²³ may be the same or different.

When R ²³ is a hydrogen atom, it is preferable in that the solubility of [D] polymer in an alkaline developer can be improved.

Examples of the monovalent organic group represented by R ²³ include an acid dissociable group, an alkali dissociable group, or a hydrocarbon group having 1 to 30 carbon atoms which may have a substituent.

  Examples of the structural unit (Db) include structural units represented by the following formulas (6b-1) to (6b-3).

In the above formulas (6b-1) to (6b-3), R ^{21 ′} is a divalent linear, branched or cyclic saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms. R ^F , X ² , R ²³ and s are as defined in the above formula (6b). When s is 2 or 3, the plurality of X ² and R ²³ may be the same or different.

  As a content rate of the said structural unit (6b), 0 mol%-90 mol% are preferable with respect to all the structural units which comprise a [D] polymer, 5 mol%-85 mol% are more preferable, 10 mol % To 80 mol% is more preferable. By setting it as such a content rate, the resist film surface formed from the said photoresist composition can improve the fall degree of a dynamic contact angle in alkali image development.

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

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

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

  As a content rate of said other structural unit, it is 30 mol% or less normally with respect to all the structural units which comprise a [D] polymer, and 20 mol% or less is preferable. If the content ratio of the other structural unit exceeds the upper limit, the pattern forming property of the photoresist composition may be deteriorated.

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

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

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

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

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

Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, 2-heptanone (methyl-n-pentyl ketone), and ethyl-n-butyl ketone. Chain ketone solvents such as methyl-n-hexyl ketone, di-iso-butyl ketone and trimethylnonanone:
Cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone and methylcyclohexanone:
2,4-pentanedione, acetonylacetone, acetophenone and the like can be mentioned.

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

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

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

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

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

(Surfactant)
Surfactants have the effect of improving coatability, striation, developability, and the like. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol diacrylate. Nonionic surfactants such as stearate; commercially available products 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 the like, and has an effect of improving the “apparent sensitivity” of the photoresist composition.

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

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

  The photoresist composition can be used both for forming a positive pattern using an alkaline developer and for forming a negative pattern using a developer containing an organic solvent. Among these, when used for negative pattern formation using a developer containing an organic solvent, the photoresist composition can exhibit higher EL performance.

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

Further, in the resist film forming step, using a photoresist composition for forming a negative pattern using a developer containing an organic solvent,
It is preferable that the developer in the development step contains an organic solvent.

  According to the resist pattern forming method, since the photoresist composition described above is used, it is possible to form a resist pattern having a small LWR and CDU while exhibiting a wide EL. Hereinafter, each step will be described.

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

  In order to prevent the influence of basic impurities and the like contained in the environmental atmosphere, a protective film disclosed in, for example, JP-A-5-188598 can be provided on the resist film. Further, in order to prevent the acid generator and the like from flowing out of the resist film, a liquid immersion protective film disclosed in, for example, JP-A-2005-352384 can be provided on the resist film. These techniques can be used in combination.

[Exposure process]
In this step, exposure is performed by irradiating the resist film formed in the resist film forming step with exposure light through a photomask (in some cases, through an immersion medium such as water). The exposure light may be, for example, electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (13.5 nm, EUV), X-rays, γ-rays, electron beams, α-rays, depending on the line width of the target pattern. And charged particle beams. Among these, far ultraviolet rays, EUV, and electron beams are preferable, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV, and electron beams are more preferable, and ArF excimer laser light, EUV, and electron beams are preferable. Further preferred.

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

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

[Development process]
In this step, the resist film exposed in the exposure step is developed using a developer. Thereby, a predetermined resist pattern is formed. Examples of the developer include an alkali developer and a developer containing an organic solvent.

  Examples of the alkali 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] -5-Alkaline aqueous solution in which at least one kind of alkaline compound such as nonene is dissolved.

  Examples of the organic solvent contained in the developer containing the organic solvent include one or more of the solvents listed as the [E] solvent of the above-described photoresist composition. Among these, ether solvents, ester solvents, and ketone solvents are preferable. As the ether solvent, an aromatic-containing ether solvent is preferable, and anisole is more preferable. As the ester solvent, an acetate solvent is preferable, and n-butyl acetate is more preferable. As the ketone solvent, a chain ketone solvent is preferable, and 2-heptanone is more preferable.

  As content of the organic solvent in a developing solution, 80 mass% or more is preferable, 90 mass% or more is more preferable, 95 mass% or more is further more preferable, 99 mass% or more is especially preferable. By setting the content of the organic solvent in the developer within the above range, the contrast between the exposed area and the unexposed area can be improved. As a result, the LWR and CDU are smaller while exhibiting a wider EL. A resist pattern can be formed. Examples of components other than the organic solvent include water and silicone oil.

  An appropriate amount of a surfactant can be added to the developer as necessary. As the surfactant, for example, an ionic or nonionic fluorine-based and / or silicon-based surfactant can be used.

  By using a developer containing an organic solvent as the developer, a resist pattern with a small LWR and CDU can be formed while exhibiting a wider EL.

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

  After the development, it is preferable to rinse with a rinsing liquid such as water or alcohol and then dry. As the rinsing method, for example, a method of continuously applying a rinsing liquid onto a substrate rotating at a constant speed (rotary coating method), a method of immersing the substrate in a tank filled with the rinsing liquid for a certain period of time (dip method) ), A method (spray method) of spraying a rinse liquid on the substrate surface, and the like.

  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.

[Mw and Mn]
Mw and Mn of the polymer were measured by 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

[ ¹ H-NMR analysis and ¹³ C-NMR analysis]
Of ¹ H-NMR analysis and ¹³ C-NMR analysis of the compound, ¹³ C-NMR analysis to determine the respective structural units content and fluorine atom content of the polymer, nuclear magnetic resonance apparatus (JNM-ECX400, manufactured by JEOL ).

<Synthesis of Compound (i)>
According to the following reaction scheme, compounds (i) represented by the following formulas (M-1) to (M-4) were respectively synthesized.

  In the above reaction scheme, R is a methyl group or a cyclohexyl group. R 'is a methyl group, an ethyl group or an i-propyl group.

[Example 1]
α-Acetyl-γ-butyrolactone 94.0 g (734 mmol), potassium carbonate 112 g (807 mmol), iodomethane 125 g (881 mmol) and acetone 600 g as a solvent were placed in a 2,000 mL eggplant flask and stirred at 55 ° C. for 6 hours. The inorganic salt was then removed by filtration. After concentration, purification by column chromatography gave 100 g of methyl-substituted product (yield 96%).
90.0 g (633 mmol) of the methyl compound and 600 mL of methanol as a solvent were placed in a 2,000 mL eggplant flask and cooled to 0 ° C. in an ice bath. A solution prepared by dissolving 12.0 g (317 mmol) of sodium borohydride in 60 mL of methanol was added dropwise over 20 minutes. After stirring at 0 ° C. for 3 hours, ammonium chloride was added to stop the reaction, followed by extraction and washing. After concentration, 62.1 g (yield 68%) of the alcohol was obtained by purification by column chromatography.
16.5 g (114 mmol) of the above alcohol compound, 1.39 g (11.4 mmol) of dimethylaminopyridine, 17.4 g (172 mmol) of triethylamine and 100 g of dehydrated acetonitrile as a solvent were placed in a 500 mL eggplant flask and brought to 0 ° C. in an ice bath. Cooled down. Thereto, 12.5 g (120 mmol) of methacrylic acid chloride was added dropwise over 10 minutes. The mixture was stirred for 10 hours while gradually warming from 0 ° C. to room temperature. Water was added to stop the reaction, followed by extraction and washing. After concentration, 20.3 g (yield 84%) of 1- (α-methyl-γ-butyrolactone-yl) ethane-1-yl methacrylate represented by the following formula (M-1) was purified by column chromatography. , Purity> 99%).

[Example 2]
In Example 1, 1- (α-ethyl-γ methacrylate represented by the following formula (M-2) was used in the same manner as in Example 1 except that the same number of moles of iodoethane was used instead of iodomethane. 21.2 g (82% yield, purity> 99%) of -butyrolactone-yl) ethane-1-yl were obtained.

[Example 3]
In Example 1, 1- (α-methacrylic acid represented by the following formula (M-3) was used in the same manner as in Example 1 except that 2-iodopropane having the same mole number was used instead of iodomethane. 21.4 g (78% yield, purity> 99%) of isopropyl-γ-butyrolactone-yl) ethane-1-yl were obtained.

[Example 4]
In Example 1, in place of α-acetyl-γ-butyrolactone, the same formula (M-4) is used as in Example 1 except that α-cyclohexylcarbonyl-γ-butyrolactone having the same mole number was used. 24.0 g (yield 75%, purity> 99%) of methacrylic acid (α-methyl-γ-butyrolactone-yl) -cyclohexylmethyl was obtained.

<Synthesis of polymer>
Each monomer used for the synthesis of [A] polymer and [D] polymer is shown below.

[[A] Synthesis of polymer]
[Example 5]
9.14 g (40 mol%) of compound (M-1) and 10.86 g (60 mol%) of compound (M-13) were dissolved in 40 g of 2-butanone, and 2,2′- as a polymerization initiator was further dissolved. A monomer solution was prepared by dissolving 0.88 g of azobis (isobutyronitrile) (AIBN) (5 mol% based on the total number of moles of the compound). A 100 mL three-necked flask containing 20 g of 2-butanone was purged with nitrogen for 30 minutes, then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 4 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization reaction solution was cooled with water and cooled to 30 ° C. or lower. The cooled polymerization reaction liquid was put into 400 g of methanol, and the precipitated white powder was filtered off. The filtered white powder was washed twice with 80 g of methanol, filtered, and dried at 60 ° C. for 17 hours to obtain a white powdery polymer (A-1) (yield 11.6 g, Yield 58%). Mw of the polymer (A-1) was 8,800, and Mw / Mn was 1.45. As a result of ¹³ C-NMR analysis, the content ratios of the structural unit derived from the compound (M-1) and the structural unit derived from (M-13) were 42 mol% and 58 mol%, respectively.

[Examples 6 to 13 and Synthesis Examples 1 to 8]
Except having used each monomer of the kind and usage-amount shown in following Table 1, it is the same as that of Example 5, and polymer (A-2)-(A-9) and polymer (a-1)- (A-8) was synthesized. The total mass of the monomers used was 20.0 g. “-” In Table 1 indicates that the corresponding compound was not used. Table 1 shows the content ratio, yield (%), Mw, and Mw / Mn ratio of each structural unit of the obtained polymer.

[[D] Synthesis of polymer]
[Synthesis Example 9]
20.0 g of the above compound (M-16) was dissolved in 20.0 g of 2-butanone, and further 1.25 g of dimethyl 2,2′-azobisisobutyrate as a polymerization initiator (8 mol relative to the compound). %) Was dissolved to prepare a monomer solution. A 300 mL three-necked flask containing 20 g of 2-butanone was purged with nitrogen for 30 minutes, and then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 4 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization reaction solution was cooled with water and cooled to 30 ° C. or lower. After transferring this polymerization reaction liquid to a 500 mL separatory funnel, the polymerization reaction liquid was uniformly diluted with 60 g of n-hexane, 240 g of methanol was added and mixed, and then 12 g of distilled water was added. The mixture was further stirred and allowed to stand for 30 minutes. Thereafter, the lower layer was recovered and solvent substitution was performed to obtain a propylene glycol monomethyl ether acetate solution of the polymer (D-1) (yield 79%). Mw of the polymer (D-1) was 6,100, and Mw / Mn was 1.52.

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

[[B] acid generator]
Each structural formula is shown below.
B-1: Triphenylsulfonium 2- (adamantan-1-ylcarbonyloxy) -1,1,3,3,3-pentafluoropropane-1-sulfonate B-2: Triphenylsulfonium adamantane-1-ylcarbonyloxy Difluoromethanesulfonate B-3: Triphenylsulfonium 2- (adamantan-1-yl) -1,1-difluoroethanesulfonate

[[C] acid diffusion controller]
Each structural formula is shown below.
C-1: Triphenylsulfonium 10-camphorsulfonate C-2: N- (undecan-1-ylcarbonyloxyethyl) morpholine C-3: N- (t-amyloxycarbonyl) -4-hydroxypiperidine

[[E] solvent]
E-1: Propylene glycol monomethyl ether acetate E-2: Cyclohexanone E-3: γ-butyrolactone

[Example 14]
[A] 100 parts by mass of (A-1) as a polymer, [B] 8.5 parts by mass of (B-1) as an acid generator, [C] (C-1) 1 as an acid diffusion controller .9 parts by mass, (D-1) 3 parts by mass as a polymer, and (E-1) 2,214 parts by mass as a solvent [E], (E-2) 949 parts by mass and (E -3) 30 parts by mass was mixed to prepare a photoresist composition (J-1).

[Examples 15 to 27 and Comparative Examples 1 to 9]
Photoresist compositions (J-2) to (J-14) and (CJ-1) to (CJ-) were carried out in the same manner as in Example 1 except that the components having the types and contents shown in Table 2 were used. 9) was prepared. “-” In Table 2 indicates that the corresponding component was not used.

About the obtained photoresist composition, the resist pattern was formed in accordance with the following method and evaluated.
In the case of ArF exposure, alkali development and organic solvent development were evaluated, and in the case of EUV exposure, alkali development was evaluated.

<ArF exposure: alkali development>
<Formation of resist pattern>
[Examples 28 to 39 and Comparative Examples 10 to 17]
Using a spin coater (CLEAN TRACK ACT12, manufactured by Tokyo Electron) on the surface of a 12-inch silicon wafer, a lower antireflection film forming composition (ARC66, manufactured by Brewer Science) was applied, and then heated at 205 ° C. for 60 seconds. As a result, a lower antireflection film having a thickness of 105 nm was formed. Each photoresist composition was applied onto the lower antireflection film using the spin coater, and PB was performed at 100 ° C. for 60 seconds. Thereafter, it was cooled at 23 ° C. for 30 seconds to form a resist film having a thickness of 90 nm. Next, this resist film was subjected to an optical condition of NA = 1.3 and dipole (Sigma 0.977 / 0.782) using an ArF excimer laser immersion exposure apparatus (NSR-S610C, manufactured by NIKON SEIKI COMPANY). The film was exposed through a mask pattern for forming a resist pattern of 40 nm line and space (1L / 1S). After the exposure, PEB was performed for 60 seconds at the PEB temperature shown in Table 3 below. Then, using a 2.38 mass% TMAH aqueous solution, performing paddle development at 23 ° C. for 30 seconds, then rinsing with ultrapure water for 7 seconds, and then spin-drying by shaking off at 2,000 rpm for 15 seconds. A 40 nm line and space (1L / 1S) resist pattern was formed.

<Evaluation>
The resist pattern obtained above was evaluated according to the following method. The evaluation results are shown in Table 3. A scanning electron microscope (CG-4000, manufactured by Hitachi High-Technologies) was used for observation and length measurement of the resist pattern.

[sensitivity]
In the formation of the resist pattern, an exposure amount for forming a 40 nm line and space (1L / 1S) resist pattern was determined as an optimum exposure amount (Eop), and this was defined as sensitivity (mJ / cm ² ). The sensitivity can be evaluated as “good” when it is 40 mJ / cm ² or less, and “bad” when it exceeds 40 mJ / cm ² .

[EL performance]
The exposure amount when the line pattern after the reduced projection exposure is exposed through a mask having a 40 nm line and space (1L / 1S) and the line width of the formed line pattern is within ± 10% of 40 nm. The ratio of the range to the optimum exposure amount was defined as EL performance (exposure margin). The EL performance can be evaluated as “good” when it is 15% or more, and “bad” when it is less than 15%.

[LWR performance]
The 40 nm line and space (1L / 1S) line pattern resolved at the optimum exposure amount was observed from above the pattern using the scanning electron microscope. Then, a total of 50 line widths were measured at arbitrary points, and a value calculated by measuring the measurement variation as 3 sigma was defined as LWR performance (nm). The smaller the value of the LWR performance, the smaller the line play and the better. The LWR performance can be evaluated as “good” when it is 3.5 nm or less, and “bad” when it exceeds 3.5 nm.

[CDU performance]
The 40 nm line and space (1L / 1S) line pattern resolved at the optimum exposure amount was observed from above the pattern using the scanning electron microscope. The line width was measured at 20 points in the range of 400 nm, the average value was measured at a total of 1,000 points, and the value calculated with the measurement variation as 3 sigma was defined as CDU (nm). The smaller the value of the CDU performance, the better the line width variation over a long period. The CDU performance can be evaluated as “good” when it is 1.3 nm or less, and “bad” when it exceeds 1.3 nm.

  From the results of Table 3, it can be seen that the photoresist compositions of the examples are excellent in all of EL performance, LWR performance, and CDU performance in alkaline development of ArF exposure. On the other hand, it was also shown that the photoresist composition of the comparative example has insufficient performance or it is difficult to combine these performances.

<ArF exposure: organic solvent development>
<Formation of resist pattern>
[Examples 40 to 48 and Comparative Examples 18 to 25]
Using a spin coater (CLEAN TRACK ACT12, manufactured by Tokyo Electron) on the surface of a 12-inch silicon wafer, a lower antireflection film forming composition (ARC66, manufactured by Brewer Science) was applied, and then heated at 205 ° C. for 60 seconds. As a result, a lower antireflection film having a thickness of 105 nm was formed. Each photoresist composition was applied onto the lower antireflection film using the spin coater, and PB was performed at 100 ° C. for 60 seconds. Thereafter, it was cooled at 23 ° C. for 30 seconds to form a resist film having a thickness of 90 nm. Next, this resist film was subjected to an optical condition of NA = 1.3 and dipole (Sigma 0.977 / 0.782) using an ArF excimer laser immersion exposure apparatus (NSR-S610C, manufactured by NIKON SEIKI COMPANY). The film was exposed through a mask pattern for forming a resist pattern of 40 nm line and space (1L / 1S). After the exposure, PEB was performed for 60 seconds at the PEB temperature shown in Table 4 below. Thereafter, paddle development with butyl acetate (30 seconds) and rinsing with 4-methyl-2-pentanol (7 seconds) were performed. Thereafter, a 40 nm line and space (1 L / 1S) resist pattern was formed by spin-drying at 2,000 rpm for 15 seconds.

  The resist pattern obtained above was evaluated by the same method and evaluation criteria as in the case of the “alkali development”. The evaluation results are shown in Table 4.

  From the results of Table 4, it can be seen that in the organic solvent development of ArF exposure, the photoresist compositions of the examples are excellent in all of EL performance, LWR performance, and CDU performance. On the other hand, it was also shown that the photoresist composition of the comparative example has insufficient performance or it is difficult to combine these performances. Moreover, it can be seen from comparison with the results in Table 3 that organic solvent development can exhibit a wider EL than alkali development.

<EUV exposure>
<Formation of resist pattern>
[Example 49 and Comparative Example 26]
A lower antireflection film having a film thickness of 25 nm was formed by applying a composition for forming a lower antireflection film on the surface of a 12-inch silicon wafer, followed by heating at 205 ° C. for 60 seconds. On this lower antireflection film, each photoresist composition shown in Table 5 below was applied, and PB was performed at 100 ° C. for 60 seconds. Thereafter, it was cooled at 23 ° C. for 30 seconds to form a resist film having a thickness of 50 nm. Next, a mask pattern for forming a resist pattern of 35 nm line and space (1L / 1S) is formed on this resist film using an EUV exposure apparatus (NXE3100, manufactured by ASML) under an optical condition of NA = 0.25 and dipole. Exposed through. After the exposure, PEB was performed for 60 seconds at the PEB temperature shown in Table 5 below. Then, using a 2.38 mass% TMAH aqueous solution, performing paddle development at 23 ° C. for 30 seconds, then rinsing with ultrapure water for 7 seconds, and then spin-drying by shaking off at 2,000 rpm for 15 seconds. A 35 nm line and space (1L / 1S) resist pattern was formed.

  The resist pattern obtained above was evaluated by the following method. The evaluation results are shown in Table 5. A scanning electron microscope (CG-4000, manufactured by Hitachi High-Technologies Corporation) was used for observation and length measurement of the resist pattern.

<Evaluation>
[sensitivity]
In the formation of the resist pattern, an exposure amount for forming a 35 nm line and space (1L / 1S) resist pattern was determined as an optimum exposure amount (Eop), and this was defined as sensitivity (mJ / cm ² ). The sensitivity can be evaluated as “good” when it is 20 mJ / cm ² or less, and “bad” when it exceeds 20 mJ / cm ² .

[Resolution]
The dimension of the minimum resist pattern that can be resolved at the optimum exposure amount is defined as the resolution. The smaller the value, the better the resolution (nm). The resolution can be evaluated as “good” when it is 30 nm or less, and “bad” when it exceeds 30 nm.

[LWR performance]
A 35 nm line and space (1L / 1S) line pattern resolved at the optimum exposure dose was observed from above the pattern using the scanning electron microscope. The line width was measured at a total of 50 points at arbitrary points, and the value calculated with the measurement variation as 3 sigma was defined as LWR (nm). The smaller the value of the LWR performance, the smaller the line play and the better. The LWR performance can be evaluated as “good” when it is 5.0 nm or less, and “bad” when it exceeds 5.0 nm.

  From the results of Table 5, it can be seen that in EUV exposure, the photoresist compositions of the examples are superior in LWR performance while maintaining the resolution as compared with the photoresist compositions of the comparative examples.

According to the photoresist composition and the resist pattern forming method of the present invention, a resist pattern having a small LWR and CDU can be formed while exhibiting a wide EL. The polymer of the present invention can be suitably used as a polymer component of the photoresist composition. The compound of the present invention can be suitably used as a raw material monomer for the polymer. Accordingly, these can be suitably used for manufacturing semiconductor devices that are expected to be further miniaturized in the future.

Claims (10)

[A] A polymer having a structural unit (I) represented by the following formula (1), and [B] a photoresist composition containing an acid generator.

(In Formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² and R ³ are monovalent having 1 to 30 carbon atoms in which R ² is substituted or unsubstituted. And R ³ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 30 carbon atoms, or R ² and R ³ are combined with each other and configured together with the carbon atom to which they are bonded. R ⁴ represents a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. ⁵ is a monovalent chain hydrocarbon group having 1 to 6 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms, p and q are each independently 0 to 3 P + q is 2 or more and 6 or less, r is an integer of 0 to 4. When r is 2 or more, a plurality of R ⁵ may be the same or different.) [A] The photoresist composition according to claim 1, wherein the polymer further has a structural unit (II) represented by the following formula (2).

(In the formula (2), R ⁶ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Y is a single bond, a carbonyloxycycloalkanediyl group having 3 to 20 carbon atoms, or a 3 to 3 carbon atoms. 20 is a carbonyloxycycloalkanediyloxy group having 20. R ⁷ is a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. ⁸ and R ⁹ are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or these groups are (Represents an alicyclic structure having 3 to 20 carbon atoms that is configured together with the carbon atoms to which they are bonded.)   [A] The polymer further has a structural unit (III) which is a structural unit other than the structural unit (I) and includes at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure and a sultone structure. The photoresist composition according to claim 1 or 2. [B] The photoresist composition according to claim 1, 2, or 3, wherein the acid generator is a compound represented by the following formula (3).

(In Formula (3), R ¹⁰ is a monovalent group containing an alicyclic structure having 7 or more ring members or a monovalent group containing an aliphatic heterocyclic structure having 7 or more ring members. R ¹¹ is carbon. (It is a fluorinated alkanediyl group having a number of 1 to 10. X ⁺ is a monovalent photodegradable onium cation.) The photoresist composition according to any one of claims 1 to 4, wherein R ^{2 in the} formula (1) is an alkyl group having 1 to 6 carbon atoms, and R ³ is a hydrogen atom.   The photoresist composition according to any one of claims 1 to 5, which is for forming a negative pattern using a developer containing an organic solvent. A step of forming a resist film using the photoresist composition according to any one of claims 1 to 6,
A resist pattern forming method comprising: exposing the resist film; and developing the exposed resist film. In the resist film forming step, using the photoresist composition according to claim 6,
The resist pattern forming method according to claim 7, wherein the developer in the developing step contains an organic solvent. The polymer which has structural unit (I) represented by following formula (1).

(In Formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² and R ³ are monovalent having 1 to 30 carbon atoms in which R ² is substituted or unsubstituted. And R ³ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 30 carbon atoms, or R ² and R ³ are combined with each other and configured together with the carbon atom to which they are bonded. R ⁴ represents a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. ⁵ is a monovalent chain hydrocarbon group having 1 to 6 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms, p and q are each independently 0 to 3 P + q is 2 or more and 6 or less, r is an integer of 0 to 4. When r is 2 or more, a plurality of R ⁵ may be the same or different.) A compound represented by the following formula (i).

(In the formula (i), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² and R ³ are monovalent having 1 to 30 carbon atoms in which R ² is substituted or unsubstituted. And R ³ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 30 carbon atoms, or R ² and R ³ are combined with each other and configured together with the carbon atom to which they are bonded. R ⁴ represents a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. ⁵ is a monovalent chain hydrocarbon group having 1 to 6 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms, p and q are each independently 0 to 3 P + q is 2 or more and 6 or less, r is an integer of 0 to 4. When r is 2 or more, a plurality of R ⁵ may be the same or different.)