JP6136811B2 - Photoresist composition and negative resist pattern forming method - Google Patents

Description

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

  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 portion by irradiation with exposure light such as deep ultraviolet rays such as an ArF excimer laser or an electron beam, and a developer solution for exposed and unexposed portions by the catalytic action of this acid. A difference in the dissolution rate with respect to is formed, and a resist pattern is formed on the substrate.

  On the other hand, a technique using an organic solvent having a polarity lower than that of an alkaline aqueous solution as a developing solution is known as a technique for enhancing the resolving power without increasing the number of steps by using the characteristics of such a photoresist composition. (See JP 2000-199953 A). Thus, when an organic solvent is used, the optical contrast can be increased, and as a result, a fine resist pattern with higher resolution can be formed.

  However, at present, when the miniaturization of the resist pattern has progressed to a level of 45 nm or less, the above-mentioned photoresist composition has not only excellent resolution but also EL (Exposure Latitude). It is required to have excellent (margin) performance, and to be excellent in LWR (Line Width Roughness) performance and CDU (Critical Dimension Uniformity) performance, and it is required to form a high-precision pattern with high yield. However, the above conventional photoresist composition cannot satisfy these performances.

JP 2000-199953 A

  The present invention has been made based on the circumstances as described above, and its purpose is to provide a photoresist composition that is excellent in EL performance, LWR performance, and CDU performance while enabling formation of a fine pattern by development using an organic solvent. Is to provide.

（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は、置換又は非置換の炭素数１〜３０の２価の炭化水素基である。Ｒ^３、Ｒ^４及びＲ^５は、Ｒ^３が炭素数１〜６の１価の鎖状炭化水素基若しくは炭素数３〜１５の１価の脂環式炭化水素基であり、かつＲ^４及びＲ^５がそれぞれ独立して水素原子、炭素数１〜６の１価の鎖状炭化水素基若しくは炭素数３〜１５の１価の脂環式炭化水素基であるか、又はＲ^３、Ｒ^４及びＲ^５のうちの２つ以上が互いに合わせられ構成される炭素数３〜２０の脂環構造を表す。ｍは、０〜３の整数である。ｎは、１〜４の整数である。Ｒ^３、Ｒ^４及びＲ^５がそれぞれ複数の場合、複数のＲ^３、Ｒ^４及びＲ^５はそれぞれ同一でも異なっていてもよい。） The invention made to solve the above problems is
A negative pattern forming photoresist composition using a developer containing an organic solvent,
A polymer (hereinafter also referred to as “[A] polymer”) having a first structural unit represented by the following formula (1) (hereinafter also referred to as “structural unit (I)”), and an acid generator (hereinafter referred to as “structural unit (I)”). , Also referred to as “[B] acid generator”)
It is a photoresist composition characterized by containing.

(In Formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² is a substituted or unsubstituted divalent hydrocarbon group having 1 to 30 carbon atoms. R ³ , R ^4, and R ⁵ are R ³ is a monovalent chain hydrocarbon group having 1 to 6 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms, and R ⁴ And R ⁵ are each independently a hydrogen atom, a monovalent chain hydrocarbon group having 1 to 6 carbon atoms, or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms, or R ³ , R ⁴ and R ⁵ represents an alicyclic structure having 3 to 20 carbon atoms constituted by being combined with each other, m is an integer of 0 to 3, and n is an integer of 1 to 4. .R ^{3, R 4} and when ^{R 5} is plural, respectively, a plurality of ^R 3, ^{R 4} and ^{R 5} may be respectively 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 using a developer containing an organic solvent.

  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, in a negative pattern formation using a developer containing an organic solvent, a resist pattern having a small LWR and CDU can be formed while exhibiting a wide EL. it can. Therefore, the photoresist composition and the resist pattern forming method can be suitably used for manufacturing semiconductor devices that are expected to be further miniaturized in the future.

<Photoresist composition>
The photoresist composition is a negative pattern forming photoresist composition using a developer containing an organic solvent, and is characterized by containing a [A] polymer and a [B] acid generator.
According to the photoresist composition, by using a developer containing an organic solvent, a negative resist pattern formed by leaving an exposed portion can be formed while exhibiting excellent EL performance. In addition, the LWR and CDU of this resist pattern can be reduced.
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). Since the [A] polymer has the structural unit (I), the photoresist composition is excellent in EL performance, LWR performance and CDU performance in a negative pattern forming method using a developer containing an organic solvent.
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, the structural unit (I) has a specific structure in which a 5- to 8-membered lactone ring is bonded to a polymer chain via a group represented by R ² and an ester group. Thus, since the lactone ring has an appropriate distance from the polymer chain, the [A] polymer having this structural unit (I) is considered to have an appropriate polarity and rigidity, It exhibits suitable solubility in a developer containing a solvent. As a result, the photoresist composition has improved EL performance, LWR performance, and CDU performance in a negative pattern forming method using a developer containing an organic solvent.

[A] The polymer is a structural unit other than the structural unit (I), a second structural unit containing an acid-dissociable group described later (hereinafter also referred to as “structural unit (II)”), and a structural unit other than the structural unit (I). And preferably having a third structural unit (hereinafter also referred to as “structural unit (III)”) containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure and a sultone structure. You may have other structural units other than (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 is a substituted or unsubstituted divalent hydrocarbon group having 1 to 30 carbon atoms. R ³ , R ^4, and R ⁵ are R ³ is a monovalent chain hydrocarbon group having 1 to 6 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms, and R ⁴ and R ⁵ is each independently a hydrogen atom, a monovalent chain hydrocarbon group having 1 to 6 carbon atoms, or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms, or R ³ and R ^4. And R ⁵ represents an alicyclic structure having 3 to 20 carbon atoms formed by combining two or more of R ⁵ . m is an integer of 0-3. n is an integer of 1 to 4. R ^3, if ^{R 4} and ^{R 5} are a plurality of each of the plurality of ^R 3, ^{R 4} and ^{R 5} may be respectively 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 unsubstituted divalent hydrocarbon group having 1 to 30 carbon atoms represented by R ² include, for example, a divalent chain hydrocarbon group having 1 to 30 carbon atoms and a divalent hydrocarbon group having 3 to 30 carbon atoms. Alicyclic hydrocarbon groups, divalent aromatic hydrocarbon groups having 6 to 30 carbon atoms, and the like.

Examples of the divalent chain hydrocarbon group include:
Alkanediyl groups such as methanediyl, ethanediyl, propanediyl, butanediyl;
Alkenediyl groups such as ethenediyl group, propenediyl group, butenediyl group;
Examples include alkynediyl groups such as ethynediyl group, propynediyl group, and butynediyl group.

Examples of the divalent alicyclic hydrocarbon group include:
Monocyclic cycloalkanediyl groups such as cyclopropanediyl group, cyclobutanediyl group, cyclopentanediyl group, cyclohexanediyl group;
Monocyclic cycloalkenediyl groups such as cyclopropenediyl group and cyclobutenediyl group;
A polycyclic cycloalkanediyl group such as a norbornanediyl group, an adamantanediyl group, a tricyclodecanediyl group, a tetracyclododecanediyl group;
And polycyclic cycloalkenediyl groups such as norbornenediyl group and tricyclodecenediyl group.

Examples of the divalent aromatic hydrocarbon group include:
Arenediyl groups such as benzenediyl group, toluenediyl group, xylenediyl group, naphthalenediyl group, anthracenediyl group, phenanthrenediyl group;
Examples thereof include arenediyl (cyclo) alkanediyl groups such as benzenediylmethanediyl group and naphthalenediylcyclohexanediyl group.

As a substituent which substitutes the hydrogen atom of the said bivalent hydrocarbon group, halogen atoms, such as a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. are mentioned, for example.
Among these, a fluorine atom is preferable.

The divalent hydrocarbon group represented by R ² is preferably a group having two bonds on the same carbon atom. That is, R ² is preferably a substituted or unsubstituted alkanylidene group or a substituted or unsubstituted cycloalkenylidene group. When R ² is the above group, the above-mentioned rigidity and polarity in the [A] polymer are considered to be more appropriate, and as a result, the EL performance, LWR performance, and CDU performance of the photoresist composition are further improved. Can be made.

R ² is preferably an unsubstituted divalent hydrocarbon group or a divalent fluorinated hydrocarbon group, more preferably an unsubstituted cycloalkanediyl group or a fluorinated alkanediyl group, and an unsubstituted cycloalkanylidene. Group, a fluorinated alkanylidene group is more preferable, an unsubstituted monocyclic or polycyclic cycloalkanylidene group having 3 to 20 carbon atoms, and a fluorinated alkanylidene group having 1 to 20 carbon atoms are particularly preferable, and the number of carbon atoms is 5 to 12 And more preferably an unsubstituted monocyclic or polycyclic cycloalkanylidene group, a fluorinated alkanylidene group having 3 to 10 carbon atoms, a cyclohexanilidene group, an adamantanilidene group, a cyclohexylmethylidene group, 1,1, A 1-trifluoro-2,2-propylidene group is most preferred.

Examples of the monovalent chain hydrocarbon group having 1 to 6 carbon atoms represented by R ³ , R ⁴ and R ⁵ include, for example,
Alkyl groups such as methyl, ethyl, propyl and butyl groups;
An alkenyl group such as an ethenyl group, a propenyl group, a butenyl group;
Examples thereof include alkynyl groups such as ethynyl group, propynyl group, and butynyl group.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms represented by the R ³ , R ⁴ and R ⁵ include, for example,
Monocyclic cycloalkyl groups such as cyclopropyl, cyclobutyl, and cyclopentyl;
A monocyclic cycloalkenyl group such as a cyclobutenyl group and a cyclopentenyl 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 in which two or more of R ³ , R ⁴ and R ⁵ are configured to be combined with each other include, for example, a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclopentene structure, Examples thereof include a cyclopentadiene structure, a cyclohexane structure, a cyclooctane structure, and a cyclodecane structure.

Among these, R ³ is preferably a chain hydrocarbon group, more preferably an alkyl group, still more preferably an alkyl group having 1 to 6 carbon atoms, and particularly preferably a methyl group or an ethyl group.
R ⁴ and R ⁵ are preferably a hydrogen atom or a chain hydrocarbon group, more preferably a hydrogen atom or an alkyl group, still more preferably a hydrogen atom, a methyl group or an ethyl group, and particularly preferably a hydrogen atom.

As said m, the integer of 0-2 is preferable at the point considered that the above-mentioned rigidity and polarity of a [A] polymer become more moderate, 0 or 1 is more preferable, and 0 is still more preferable.
As said n, 1 or 2 is preferable and 1 is more preferable at the point considered that the above-mentioned rigidity and polarity of [A] polymer become more moderate.

  Examples of the structural unit (I) include structural units represented by the following formulas (1-1) to (1-13) (hereinafter also referred to as “structural units (I-1) to (I-13)”). Etc.

In the above formulas (1-1) to (1-13), R ¹ has the same meaning as the above formula (1).

  Among these, the structural unit (I-1) to the structural unit (I-6) are preferable, and the structural unit (I-1) to the structural unit (I-4) are more preferable.

  As a minimum of the content rate of structural unit (I), 1 mol% is preferable with respect to all the structural units which comprise a [A] polymer, 7 mol% is more preferable, 15 mol% is further more preferable, 25 mol % Is particularly preferred. As an upper limit of the content rate of structural unit (I), 80 mol% is preferable, 75 mol% is more preferable, 65 mol% is further more preferable, 55 mol% is especially preferable. By making the said content rate into the said range, EL performance, LWR performance, and CDU performance of the said photoresist composition can be improved. When the content ratio is less than the lower limit, the above effect may not be sufficiently exhibited. When the said content rate exceeds the said upper limit, the pattern formation property of the said photoresist composition may fall.

  Examples of the compound that gives the structural unit (I) include compounds represented by the following formulas (1m-1) to (1m-13) (hereinafter also referred to as “compounds (1m-1) to (1m-13)”). ) And the like.

In the above formulas (1m-1) to (1m-13), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

  Among these, compounds (1m-1) to (1m-6) are preferable, and compounds (1m-1) to (1m-4) are more preferable.

  The compound giving the structural unit (I) can be synthesized, for example, by reacting an alcohol having a 5- to 8-membered lactone structure with a (meth) acrylic acid halide by a known method.

[Structural unit (II)]
The structural unit (II) is a structural unit containing an acid dissociable group. The “acid-dissociable group” refers to a group that replaces a hydrogen atom such as a hydroxy group or a carboxy group and that dissociates by the action of an acid. As the structural unit (II), for example, a structural unit represented by the following formula (2-1) (hereinafter, also referred to as “structural unit (II-1)”), and represented by the following formula (2-2) A structural unit (hereinafter also referred to as “structural unit (II-2)”). The group represented by —CR ⁷ R ⁸ R ⁹ in the structural unit (II-1) and the group represented by —CR ^C R ^D OR ^E in the structural unit (II-2) are acid dissociable groups. Since the [A] polymer has the structural unit (II), the photoresist composition can improve sensitivity and resolution, and as a result, can improve EL performance, LWR performance, and CDU performance.

In the formula (2-1), ^{R 6} is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 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.
In said formula (2-2), ^RA is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ^B is a divalent organic group having 2 to 20 carbon atoms. R ^C and R ^D are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, or the number of ring members composed of these groups together with the carbon atom to which they are bonded. 3-20 alicyclic structures are represented. R ^E is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^B and R ^E may represent a ring structure having 5 to 20 ring members that is configured together with the oxygen atom to which they are bonded and the carbon atom to which R ^C and R ^D are bonded.

R ⁶ and R ^A are preferably a hydrogen atom or a methyl group, and more preferably a methyl group, from the viewpoint of the copolymerizability 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.

Examples of the divalent organic group having 2 to 20 carbon atoms represented by R ^B include, for example, a divalent hydrocarbon group having 2 to 20 carbon atoms, one or more of these divalent hydrocarbon groups, and —O. And a group in combination with —, —COO— and the like. Examples of the divalent hydrocarbon group having 2 to 20 carbon atoms include those having 2 to 20 carbon atoms among the groups exemplified as the divalent hydrocarbon group for R ² in the above formula (1). R ^B is preferably a divalent chain hydrocarbon group, a divalent alicyclic hydrocarbon group, a group in which a divalent chain hydrocarbon group and —COO— are combined, an alkanediyl group, a cycloalkane. Diyl group and alkanediylcarbonyloxyalkanediyl group are more preferable, methanediyl group, ethanediyl group, cyclohexanediyl group, norbornanediyl group, adamantanediyl group and methanediylcarbonyloxypropanediyl group are more preferable, ethanediyl group and adamantanediyl group are more preferable. Particularly preferred.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^C , R ^D and R ^E include a group in which one hydrogen atom is added to the divalent hydrocarbon group exemplified as R ^B above. Is mentioned.
R ^C and R ^D are preferably a hydrogen atom or a chain hydrocarbon group, more preferably a hydrogen atom or an alkyl group, and even more preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group or an i-propyl group, Particularly preferred are a hydrogen atom, a methyl group, and an i-propyl group.
Examples of the alicyclic structure having 3 to 20 ring members constituted by combining R ^C and R ^D groups with each other include, for example, a monocyclic cycloalkane structure such as a cyclopentane structure, a cyclohexane structure, and a cyclooctane structure; a norbornane structure And a polycyclic cycloalkane structure such as an adamantane structure. Among these, a monocyclic cycloalkane structure is preferable, and a cyclohexane structure is more preferable.

R ^E is preferably a chain hydrocarbon group or an alicyclic hydrocarbon group, more preferably a chain hydrocarbon group, still more preferably an alkyl group, and particularly preferably a methyl group or a t-butyl group.
Examples of the ring structure having 5 to 20 ring members constituted by combining R ^B and R ^E with each other include dioxacycloalkane structures such as a dioxacyclopentane structure, a dioxacyclohexane structure, and a dioxacycloheptane structure. Etc. Among these, a dioxacyclopentane structure and a dioxacyclohexane structure are preferable, and a dioxacyclopentane structure is more preferable.

  As the structural unit (II-1), structural units represented by the following formulas (2-1-1) to (2-1-4) (hereinafter “structural units (II-1-1) to (II-1)” -4) ") is preferred.

In the above formulas (2-1-1) to (2-1-4), R ^{6 to} R ⁹ have the same meaning as the above formula (2-1). i and j are each independently an integer of 1 to 4.

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

In said formula, R < ⁶ > is synonymous with the said Formula (2-1).

  The structural unit (II-1) includes a structural unit derived from 1-alkyl-1-cyclopentyl (meth) acrylate, a structural unit derived from 2-alkyl-2-adamantyl (meth) acrylate, and 2- (adamantane-1 A structural unit derived from -yl) propan-2-yl (meth) acrylate and a structural unit derived from 2-cyclohexylpropan-2-yl (meth) acrylate are preferred.

  As the structural unit (II-2), a structural unit represented by the following formula (2-2-1) (hereinafter, also referred to as “structural unit (II-2-1)”), The structural unit represented by 2) (hereinafter also referred to as “structural unit (II-2-2)”) is preferable.

In the above formulas (2-2-1) and (2-2-2), R ^A , R ^C and R ^D are as defined in the above formula (2-2). ^Rb is a C1-C19 divalent hydrocarbon group. h is an integer of 1 to 4. R ^{B ′} is a divalent hydrocarbon group having 2 to 20 carbon atoms. R ^{E ′} is a monovalent hydrocarbon group having 1 to 20 carbon atoms.

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

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

In the above formula, R ^A has the same meaning as in the above formula (2-2).

  As the structural unit (II-2), a structural unit derived from 2,2-dialkyl-1,3-dioxycycloalkane-ylalkyl (meth) acrylate and a structural unit derived from alkoxyalkoxycycloalkyl (meth) acrylate 2,2-dimethyl-1,3-dioxycyclopentanyl (meth) acrylate and t-butoxy-i-butoxyadamantanyl (meth) acrylate are more preferable.

  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%-70 mol% are more preferable, 25 mol% -60 mol% is more 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. -Structural unit derived from yl (meth) acrylate, structural unit derived from cyano-substituted norbornanelactone-yl (meth) acrylate, structural unit derived from norbornanelactone-yloxycarbonylmethyl (meth) acrylate, γ-butyrolactone-yl Structural unit derived from (meth) acrylate, structural unit derived from ethylene carbonate-ylmethyl (meth) acrylate, structural unit derived from norbornane sultone-yl (meth) acrylate, norbornane sultone-yl A structural unit derived from oxycarbonylmethyl (meth) acrylate is more preferred.

  As a content rate of structural unit (III), 0 mol%-70 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 10 mol%-65 mol% are more preferable, 25 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. When the said content rate is less than the said minimum, the adhesiveness to the board | substrate of the resist pattern formed from the said photoresist composition may fall. When the said content rate exceeds the said upper limit, the pattern formation property of the said photoresist composition may fall.

[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 ^L2 represents 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. q is an integer of 0-3.
In the above formula (X-3), R ^c1 and R ^c2 each independently represent a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number of 6 12 aromatic hydrocarbon group, or an -OSO ₂ -R ^R or _-SO 2 -R ^S, or two or more are combined with each other configured ring of these groups. R ^R and R ^S are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms. Or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k6 and k7 are each independently an integer of 0 to 5. R ^{c1, R} c2, ^R when ^R and ^{R S} is plural respective plurality of ^{R c1,} R c2, ^{R R} and ^{R S} may have respectively the same or different.

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

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

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

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

  Examples of the acid generator represented by the above formula (3) include compounds represented by the following formulas (3-1) to (3-10) (hereinafter referred to as “compounds (3-1) to (3-10)”. ) ")) And the like.

  [B] Among these, as the acid generator, onium salt compounds are preferable, sulfonium salts and tetrahydrothiophenium salts are more preferable, and compounds (3-1) to (3-5) 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 mass or more and 30 parts by mass or less are preferable, 0.5 parts by mass or more and 20 parts by mass or less are more preferable, and 1 part by mass or more and 15 parts by mass or less are more preferable. [B] By making content of an acid generator into the said range, the sensitivity and developability of the said photoresist composition improve. [B] 1 type (s) or 2 or more types can be used for an acid generator.

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

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

In the above formula (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, and 0.3 mass part-10 mass parts are further more preferable. [C] When the content of the acid diffusion controller exceeds the above upper limit, the sensitivity of the photoresist composition may decrease.

<[D] Polymer>
[D] The polymer is a fluorine atom-containing polymer (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. In addition, the fluorine atom content rate (mass%) of a polymer can obtain | require the structure of a polymer by < ¹³ > C-NMR spectrum measurement, and can calculate it from the structure.

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

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

Examples of ester solvents include:
Methyl acetate, ethyl acetate, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec-butyl acetate, n-pentyl acetate, i-pentyl acetate, sec-pentyl acetate, 3-methoxy acetate Acetate solvents such as butyl, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, and n-nonyl acetate;
Ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether Polyhydric alcohol partial ether acetate solvents such as acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate;
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>
The photoresist composition includes, for example, a [A] polymer, a [B] acid generator, a [C] acid diffusion controller, an optional component contained as necessary, and a [F] solvent in 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.

<Negative resist pattern forming method>
The negative 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 using a developer containing an organic solvent (hereinafter also referred to as “development step”).
Have

  According to the negative resist pattern forming method, since the photoresist composition described above is used, a resist pattern having a small LWR and CDU can be formed 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). Examples of the exposure light include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, X-rays, and γ rays; charged particle beams such as electron beams and α-rays, depending on the line width of the target pattern. Among these, far ultraviolet rays and electron beams are preferable, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), and electron beams are more preferable, and ArF excimer laser light and electron beams are more preferable.

  The exposure method can be appropriately selected depending on the desired resist pattern shape and the like. For example, an isotrench pattern can be formed by exposing a desired region through an isoline pattern mask. Moreover, you may perform exposure twice or more. When performing exposure twice or more, it is preferable to perform exposure continuously. In the case of performing multiple exposures, for example, the first exposure is performed on a desired region through a line and space pattern mask, and then the second exposure is performed so that the line intersects the exposure unit that has performed the first exposure. I do. The first exposure part and the second exposure part are preferably orthogonal. By being orthogonal, it becomes easy to form a perfect circular contact hole pattern in the unexposed area surrounded by the exposed area.

  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 containing an organic solvent. Thereby, a predetermined resist pattern is formed. After development, it is common to wash with water or a rinse solution such as alcohol and then dry.

  Examples of the developer include organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, and solvents containing these organic solvents. Examples of 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.

  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.

  The resist film after the development is preferably washed with a rinse solution. An organic solvent can also be used as the rinsing liquid, and the generated scum can be washed efficiently. As the rinsing liquid, hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents, amide solvents and the like are preferable. Among these, alcohol solvents and ester solvents are preferable, and monovalent alcohol solvents having 6 to 8 carbon atoms are more preferable. Examples of monohydric alcohols having 6 to 8 carbon atoms include linear, branched or cyclic monohydric alcohols, such as 1-hexanol, 1-heptanol, 1-octanol, and 4-methyl-2-pentanol. 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, benzyl alcohol and the like. Of these, 1-hexanol, 2-hexanol, 2-heptanol, and 4-methyl-2-pentanol are preferable, and 4-methyl-2-pentanol is more preferable.

  Each component of the said rinse liquid may be used independently and may use 2 or more types together. The water content in the rinse liquid is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 3% by mass or less. By setting the water content within the above range, good development characteristics can be obtained. A surfactant can also be added to the rinse solution.

  As a cleaning treatment method using a rinsing liquid, for example, a method of continuously applying the rinsing liquid onto a substrate rotating at a constant speed (rotary coating method), or 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 rinsing 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 polymer>
Each monomer used for the synthesis of [A] polymer and [D] polymer is shown below.

[[A] Synthesis of polymer]
[Synthesis Example 1]
12.00 g (50 mol%) of the compound (M-1) and 8.00 g (50 mol%) of the compound (M-5) are dissolved in 40 g of 2-butanone, and 0.78 g of AIBN as a polymerization initiator (compound) The monomer solution was prepared by dissolving 5 mol%) of the total number of moles. 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 16.2 g, Yield 81%). Mw of the polymer (A-1) was 7,100, and Mw / Mn was 1.61. 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-5) were 50.5 mol% and 49.5 mol%, respectively. .

[Synthesis Examples 2 to 17]
Except having used each monomer of the kind and usage-amount shown in following Table 1, it carried out similarly to the synthesis example 1, and polymer (A-2)-(A-15) and polymer (CA-1) and (CA-2) was synthesized. The total mass of the monomers used was 20.0 g. Table 1 shows the content, yield (%), Mw, and Mw / Mn ratio of each structural unit of these polymers.

[[D] Synthesis of polymer]
[Synthesis Example 18]
16.23 g (80 mol%) of the compound (M-21) and 3.77 g (20 mol%) of the compound (M-10) were dissolved in 30 g of 2-butanone, and dimethyl 2, as a polymerization initiator was further dissolved. A monomer solution was prepared by dissolving 0.74 g of 2′-azobisisobutyrate. A 300 mL three-necked flask containing 10 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. After transferring this polymerization reaction liquid to a 500 ml separatory funnel, the polymerization reaction liquid was uniformly diluted with 150 g of n-hexane, 600 g of methanol was added and mixed, and then 30 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 60%). Mw of the polymer (D-1) was 6,600, and Mw / Mn was 1.50. As a result of ¹³ C-NMR analysis, the content ratios of the structural unit derived from the compound (M-18) and the structural unit derived from the compound (M-10) were 80.5 mol% and 19.5 mol%, respectively. It was.

<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 adamantane-1-yloxycarbonyldifluoromethanesulfonate B-2: 4-Butoxynaphthalen-1-yltetrahydrothiophenium adamantane-1-yloxycarbonyldifluoromethanesulfonate B-3: Triphenylsulfonium 2- (adamantan-1-yl) -1,1-difluoroethanesulfonate B-4: Triphenylsulfonium 6- (adamantan-1-ylcarbonyloxy) -1,1,2,2-tetrafluorohexane-1-sulfonate

[[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 1]
[A] 100 parts by mass of (A-1) as a polymer, [B] 4.5 parts by mass of (B-1) as an acid generator, [C] (C-1) 8 as an acid diffusion controller 0.7 parts by weight, (D-1) 5 parts by weight as a polymer, and (E-1) 1,981 parts by weight, (E-2) 849 parts by weight and (E) as a solvent. -3) 100 parts by mass was mixed to prepare a photoresist composition (J-1).

[Examples 2 to 19 and Comparative Examples 1 and 2]
Photoresist compositions (J-2) to (J-19), (CJ-1) and (CJ-) were the same as in Example 1 except that the components of the types and contents shown in Table 2 below were used. 2) was prepared.

<Formation of resist pattern>
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 is 44 nm in 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). It exposed through the mask pattern for resist pattern formation of a line / 38 nm space. After the exposure, PEB was performed for 60 seconds at the PEB temperature shown in Table 3 below. Thereafter, paddle development is performed with butyl acetate at 23 ° C. for 30 seconds, then rinsed with 4-methyl-2-pentanol for 7 seconds, and then spin-dried by shaking off at 2,000 rpm for 15 seconds. , 44 nm line / 38 nm space negative resist pattern was formed.

<Evaluation>
About the formed resist pattern, each photoresist composition was evaluated by measuring according to the following method. A scanning electron microscope (CG-4000, manufactured by Hitachi High-Technologies) was used for measuring the resist pattern.

[sensitivity]
In the formation of the resist pattern, an exposure amount for forming a resist pattern of 44 nm line / 38 nm space 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 ratio of the exposure amount range to the above Eop when the pattern dimension resolved when using the mask pattern for resist pattern formation of 44 nm line / 38 nm space is within ± 10% of the mask design dimension is EL (Exposure margin) Performance (%). As the EL performance value is larger, the change amount of the patterning performance with respect to the exposure amount change is smaller and better. The EL performance can be evaluated as “good” when it is 16% or more, and “bad” when it is less than 16%.

[LWR performance]
The formed resist pattern was observed from above the pattern using the scanning electron microscope. A total of 500 line width variations were measured, and a 3-sigma value was determined from the distribution of the measured values, and this 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 3.0 nm or less, and “bad” when it exceeds 3.0 nm.

[CDU performance]
The formed resist pattern 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 500 points, and a 3-sigma value was obtained from the distribution of the measured values, which was taken as CDU performance (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 1.5 nm or less, and “bad” when it exceeds 1.5 nm.

  Table 3 shows the measured values as the evaluation results. In addition, since it was not resolved in the photoresist composition (CJ-2) of Comparative Example 2, each evaluation was not performed.

  As is apparent from the results in Table 3, according to the photoresist composition of the example, a fine resist pattern with small LWR and CDU can be formed while exhibiting a wide EL. On the other hand, in the photoresist composition of the comparative example, each performance of EL, LWR, and CDU was insufficient, or some of them did not resolve.

According to the photoresist composition and the resist pattern forming method of the present invention, in a negative pattern formation using a developer containing an organic solvent, a resist pattern having a small LWR and CDU can be formed while exhibiting a wide EL. it can. Therefore, the photoresist composition and the resist pattern forming method can be suitably used for manufacturing semiconductor devices that are expected to be further miniaturized in the future.

Claims (5)

A negative pattern forming photoresist composition using a developer containing an organic solvent,
A polymer having a first structural unit represented by the following formula (1), and
A photoresist composition comprising an acid generator represented by the following formula (3) .

(In Formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² is a substituted or unsubstituted divalent hydrocarbon group having 1 to 30 carbon atoms. R ³ , R ^4, and R ⁵ are R ³ is a monovalent chain hydrocarbon group having 1 to 6 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms, and R ⁴ And R ⁵ are each independently a hydrogen atom, a monovalent chain hydrocarbon group having 1 to 6 carbon atoms, or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms, or R ³ , R ⁴ and R ⁵ represents an alicyclic structure having 3 to 20 carbon atoms constituted by being combined with each other, m is an integer of 0 to 3, and n is an integer of 1 to 4. .R ^{3, R 4} and when ^{R 5} is plural, respectively, a plurality of ^R 3, ^{R 4} and ^{R 5} may be respectively the same or different.)

(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 claim 1, wherein the polymer further has a second structural unit containing an acid dissociable group.   The said polymer is structural units other than a 1st structural unit, Comprising: The 1st claim | claim or Claim 3 which further has the 3rd structural unit containing at least 1 sort (s) chosen from the group which consists of a lactone structure, a cyclic carbonate structure, and a sultone structure. 2. The photoresist composition according to 2. Hydrocarbon group in R ² in the formula (1) is, according to claim 1 is an unsubstituted monocyclic or polycyclic cycloalkane crab isopropylidene group having 3 to 20 carbon atoms, according to claim 2 or claim 3 Photoresist composition. A photoresist composition for forming a negative pattern using a developer containing an organic solvent, comprising a polymer having a first structural unit represented by the following formula (1) and an acid generator: A resist film is formed using a product (excluding a resist composition containing a structural unit represented by the following formula (I) and a resin containing a structural unit having an acid labile group and an acid generator). The process of
A negative resist pattern forming method comprising: a step of exposing the resist film; and a step of developing the exposed resist film using a developer containing an organic solvent.

(In Formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² is a substituted or unsubstituted divalent hydrocarbon group having 1 to 30 carbon atoms. R ³ , R ^4, and R ⁵ are R ³ is a monovalent chain hydrocarbon group having 1 to 6 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms, and R ⁴ And R ⁵ are each independently a hydrogen atom, a monovalent chain hydrocarbon group having 1 to 6 carbon atoms, or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms, or R ³ , R ⁴ and R ⁵ represents an alicyclic structure having 3 to 20 carbon atoms constituted by being combined with each other, m is an integer of 0 to 3, and n is an integer of 1 to 4. .R ^{3, R 4} and when ^{R 5} is plural, respectively, a plurality of ^R 3, ^{R 4} and ^{R 5} may be respectively the same or different.)

[In the formula (I),
R ¹ is an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, a hydrogen atom or a halogen atom.
Represents an atom.
L ¹ represents a divalent saturated hydrocarbon group having 1 to 18 carbon atoms, and is contained in the saturated hydrocarbon group.
At least one methylene group is replaced by an oxygen atom or a carbonyl group;
The hydrogen atom contained in the hydrocarbon group may be substituted with a hydroxy group.
R ² represents an alkyl group having 1 to 6 carbon atoms.
m represents an integer of 0 to 5, and when m is 2 or more, the plurality of R ² are the same or different. ]