KR102111345B1 - Photoresist composition and process for forming negative resist pattern - Google Patents

Abstract

An object of the present invention is to provide a photoresist composition excellent in EL performance, LWR performance, and CDU performance while enabling formation of a fine pattern by development using an organic solvent.
The solution of the present invention is a photoresist composition for forming a negative pattern using a developer containing an organic solvent, characterized by containing a polymer having a first structural unit represented by the following formula (1) and an acid generator. Is done. It is preferable that the said polymer further has a 2nd structural unit containing an acid dissociable group. It is preferable that the said polymer further has a 3rd structural unit containing at least 1 sort (s) selected from the group which consists of a lactone structure, a cyclic carbonate structure, and a sultone structure as a structural unit other than a 1st structural unit. As the acid generator, a compound represented by the following formula (3) is preferable.

Description

Photoresist composition and method of forming a negative resist pattern {PHOTORESIST COMPOSITION AND PROCESS FOR FORMING NEGATIVE RESIST PATTERN}

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

With the miniaturization of various electronic device structures such as semiconductor devices and liquid crystal devices, further miniaturization of the resist pattern in the lithography process is required, and for this reason, various photoresist compositions have been studied. The photoresist composition generates an acid in the exposed portion by irradiation of exposure light such as an ultraviolet ray or an electron beam such as an ArF excimer laser, and a difference in the dissolution rate of the exposed portion and the unexposed portion in the developer by catalytic action of the acid. Generated to form a resist pattern on the substrate.

On the other hand, as a technique of using the features of such a photoresist composition and increasing the resolution without increasing the process using an existing apparatus, a technique using an organic solvent having a lower polarity than an aqueous alkali solution in a developer is known (Japanese Patent Publication No. 2000-199953). In this way, when an organic solvent is used, optical contrast can be increased, and as a result, a fine resist pattern with higher resolution can be formed.

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

Japanese Patent Publication No. 2000-199953

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

The invention made to solve the above problems,

As a photoresist composition for forming a negative pattern using a developer containing an organic solvent,

A polymer having a first structural unit represented by the following formula (1) (hereinafter also referred to as "structural unit (I)") (hereinafter also referred to as "[A] polymer"), and

Acid generator (hereinafter also referred to as "[B] acid generator")

It is a photoresist composition characterized by containing.

(In the 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 is 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 or a monovalent carbon atom having 1 to 6 carbon atoms. A linear hydrocarbon group or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms, or two or more of R ³ , R ⁴ and R ⁵ combined with each other, and representing an alicyclic structure having 3 to 20 carbon atoms, m being 0 to 3 And n is an integer from 1 to 4, and when R ³ , R ⁴ and R ⁵ are plural, plural R ³ , R ⁴ and R ⁵ may be the same or different, respectively)

Method of forming a resist pattern of the present invention,

Forming a resist film using the photoresist composition,

A process of exposing the resist film, and

Process for developing the exposed resist film using a developer containing an organic solvent

Have

Here, the "hydrocarbon group" includes a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The "hydrocarbon group" may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group. The "chain hydrocarbon group" refers to a hydrocarbon group composed of only a chain structure without including a cyclic structure, and includes both a straight chain hydrocarbon group and a branched hydrocarbon group. The "alicyclic hydrocarbon group" refers to a hydrocarbon group containing only an alicyclic structure and not an aromatic ring structure as the ring structure, and includes both a monocyclic alicyclic hydrocarbon group and a polycyclic alicyclic hydrocarbon group. However, it is not necessary to consist only of an alicyclic structure, and a chain structure may be included in a part. The "aromatic hydrocarbon group" refers to a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it is not necessary to consist only of an aromatic ring structure, and a part may include a chain structure or an alicyclic structure.

According to the photoresist composition and the resist pattern forming method of the present invention, a resist pattern having a small LWR and CDU can be formed while exhibiting wide EL in forming a negative pattern using a developer containing an organic solvent. Therefore, the photoresist composition and the method of forming a resist pattern can be preferably used for semiconductor device manufacturing, which is expected to be further refined in the future.

<Photoresist composition>

The photoresist composition is a photoresist composition for forming a negative pattern using a developer containing an organic solvent, and is characterized by containing [A] polymer and [B] acid generator.

According to the photoresist composition, by using a developer containing an organic solvent, a negative resist pattern formed by exposing the exposed portion can be formed while exhibiting excellent EL performance, and the LWR and CDU of the resist pattern can be reduced. Can be.

The photoresist composition may contain [C] acid diffusion control body, [D] fluorine atom-containing polymer (hereinafter also referred to as "[D] polymer"), and [E] solvent as suitable components, and the present invention Other optional components may be contained within a range that does not impair the effect.

Hereinafter, each component is demonstrated.

<[A] polymer>

[A] The polymer is a polymer having a structural unit (I). The photoresist composition has excellent EL performance, LWR performance, and CDU performance in a negative pattern formation method using a developer containing an organic solvent because the polymer [A] has a structural unit (I).

The reason why the photoresist composition exerts the above effects by having the above-described composition is not necessarily clear, but can be estimated as follows, for example. That is, the structural unit (I) has a specific structure in which the 5 to 8 membered lactone ring is bonded to the polymer chain through a group represented by R ² and an ester group. Since the lactone ring has an appropriate distance from the polymer chain in this way, the polymer [A] having the structural unit (I) is considered to have appropriate polarity and rigidity, and exhibits desirable solubility in a developing solution containing an organic solvent. . As a result, the photoresist composition improves 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 lactone as a structural unit other than the structural unit (I), a second structural unit containing an acid dissociable group (hereinafter, also referred to as "structural unit (II)"), and a structural unit other than the structural unit (I) It is preferable to have a third structural unit (hereinafter also referred to as "structural unit (III)") containing at least one member selected from the group consisting of a structure, a cyclic carbonate structure and a sultone structure, and structural unit (I) Other structural units may be further included in addition to (III). [A] The polymer may have one or two or more of the above structural units.

Hereinafter, each structural unit is demonstrated.

[Structural Unit (I)]

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

In the 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, It is a monovalent chain hydrocarbon group having 1 to 6 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms, or two or more of R ³ , R ⁴ and R ⁵ are combined to form an alicyclic structure having 3 to 20 carbon atoms. Shows. m is an integer from 0 to 3. n is an integer from 1 to 4. R ^3, R ⁴ and R ^5, if a plurality of individuals, respectively, the plurality of R ^3, R ⁴ and R ⁵ are the same or each may be different.

As R ¹ , from the viewpoint of copolymerization of the monomers providing the structural unit (I), a hydrogen atom or a methyl group is preferable, and a methyl group is more preferable.

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, a divalent alicyclic hydrocarbon group having 3 to 30 carbon atoms, and 6 to 30 carbon atoms. And bivalent aromatic hydrocarbon groups.

As said divalent chain hydrocarbon group, For example,

Alkanediyl groups such as methanediyl group, ethanediyl group, propanediyl group, and butanediyl group;

Alkendiyl groups such as ethendiyl group, propendiyl group, and butenediyl group;

And alkynediyl groups such as ethyndiyl group, propyndiyl group, and butyndiyl group.

As said divalent alicyclic hydrocarbon group, for example,

Monocyclic cycloalkanediyl groups such as cyclopropanediyl group, cyclobutanediyl group, cyclopentanediyl group, and cyclohexanediyl group;

Monocyclic cycloalkendiyl groups such as cyclopropendiyl group and cyclobutenediyl group;

Polycyclic cycloalkanediyl groups such as norbornanediyl group, adamantanediyl group, tricyclodecanediyl group, and tetracyclododecanediyl group;

And polycyclic cycloalkendiyl groups such as norbornene diyl group and tricyclodecenediyl group.

As said divalent aromatic hydrocarbon group, for example,

Arenediyl groups such as benzenediyl group, toluenediyl group, xylenediyl group, naphthalenediyl group, anthracenediyl group, and phenanthrendiyl group;

And arendyl (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 atom, such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, etc. are mentioned, for example.

Of these, fluorine atoms are preferred.

As the divalent hydrocarbon group represented by R ² , a group having two bonding hands on the same carbon atom is preferable. That is, examples of the R ^2, is preferably a substituted or unsubstituted alkaryl nilri dengi, a substituted or unsubstituted cycloalkyl alkaryl nilri den. When R ² is the above group, it is considered that the above-described rigidity and polarity in the polymer [A] are more appropriate, and as a result, EL performance, LWR performance and CDU performance of the photoresist composition can be further improved.

As R ² , an unsubstituted divalent hydrocarbon group and a divalent fluorinated hydrocarbon group are preferable, and an unsubstituted cycloalkanediyl group and a fluorinated alkanediyl group are more preferable, and an unsubstituted cycloalkanylidene group and a fluorinated alkanylidene group More preferably, the unsubstituted monocyclic or polycyclic cycloalkanylidene group having 3 to 20 carbon atoms, the fluorinated alkanylidene group having 1 to 20 carbon atoms is particularly preferable, and the unsubstituted monocyclic or polycyclic cycloalkanyl having 5 to 12 carbon atoms The den group, a fluorinated alkanilidene group having 3 to 10 carbon atoms is more particularly preferable, and the cyclohexanidene group, adamantanilidene group, cyclohexylmethylidene group, 1,1,1-trifluoro-2,2-propylidene group 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 group, ethyl group, propyl group and butyl group;

Alkenyl groups such as ethenyl group, propenyl group, and butenyl group;

And 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 R ³ , R ⁴ and R ⁵ include, for example,

Monocyclic cycloalkyl groups such as cyclopropyl group, cyclobutyl group, and cyclopentyl group;

Monocyclic cycloalkenyl groups such as cyclobutenyl group and cyclopentenyl group;

Polycyclic cycloalkyl groups such as norbornyl group, adamantyl group, and tricyclodecyl group;

And polycyclic cycloalkenyl groups such as norbornene and tricyclodecenyl groups.

Examples of the alicyclic structure having 3 to 20 carbon atoms formed by combining two or more of R ³ , R ⁴ and R ⁵ together are, for example, a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclopentene structure, and a cyclopentadiene. Structures, cyclohexane structures, cyclooctane structures, cyclodecane structures, and the like.

As R ³ , a chain hydrocarbon group is preferable, an alkyl group is more preferable, an alkyl group having 1 to 6 carbon atoms is more preferable, and a methyl group and an ethyl group are particularly preferable.

The R ⁴ and R ⁵ are preferably a hydrogen atom or a chain hydrocarbon group, more preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom, a methyl group or an ethyl group, and particularly preferably a hydrogen atom.

As said m, since the above-mentioned rigidity and polarity of the polymer [A] are considered to be more appropriate, an integer of 0 to 2 is preferable, 0 or 1 is more preferable, and 0 is more preferable.

As said n, 1 or 2 is preferable and 1 is more preferable at the point which it thinks that the above-mentioned rigidity and polarity of the polymer [A] become more appropriate.

As the structural unit (I), for example, 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. Can be heard.

In the formulas (1-1) to (1-13), R ¹ is as defined in the formula (1).

Of these, structural units (I-1) to (I-6) are preferable, and structural units (I-1) to (I-4) are more preferable.

As the lower limit of the content ratio of the structural unit (I), 1 mol% is preferable, 7 mol% is more preferable, 15 mol% is more preferable, and 25 mol% is preferable with respect to the whole structural unit constituting the polymer [A]. 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 more preferable, and 55 mol% is particularly preferable. By setting the content ratio in the above range, EL performance, LWR performance and CDU performance of the photoresist composition can be improved. When the said content ratio is less than the said lower limit, the said effect may not fully be exhibited. When the content ratio exceeds the upper limit, the pattern formability of the photoresist composition may be lowered.

As a compound providing the structural unit (I), for example, 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 formulas (1m-1) to (1m-13), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

Of these, compounds (1m-1) to (1m-6) are preferred, and compounds (1m-1) to (1m-4) are more preferred.

The compound providing the structural unit (I) can be synthesized, for example, by reacting an alcohol having a 5- to 8-membered ring lactone structure with (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 dissociates by the action of an acid as a group that replaces a hydrogen atom such as a hydroxy group or a carboxy group. 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)"), a structural unit represented by the following formula (2-2) (Hereinafter, also referred to as "structural unit (II-2)") and the like. The group represented by -CR ⁷ R ⁸ R ⁹ of the structural unit (II-1) and the group represented by -CR ^C R ^D OR ^E of the structural unit (II-2) are acid dissociable groups. In the photoresist composition, the polymer [A] has a structural unit (II), thereby improving sensitivity and resolution, and consequently, 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 are combined with each other to form 3 to 3 carbon atoms. The alicyclic structure of 20 is shown.

In the formula (2-2), R ^A 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 these groups combine with each other to represent an alicyclic structure having 3 to 20 of reduced water composed of carbon atoms to which they are bonded. R ^E is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^B and R ^E may be combined with each other to represent a ring structure of reduced water 5 to 20 composed of an oxygen atom to which they are bonded and a carbon atom to which R ^C and R ^D are bonded.

Examples of the R ⁶ and R ^A, in view of the copolymerizability of the monomer giving the structural unit (II) is a hydrogen atom, a methyl group is preferable, and more preferably a methyl group.

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 and i-propyl group;

Alkenyl groups such as ethenyl group, propenyl group, and butenyl group;

And alkynyl groups such as ethynyl group, propynyl group, and butynyl group.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ⁷ , R ⁸ and R ⁹ include, for example,

Monocyclic cycloalkyl groups such as cyclopentyl group and cyclohexyl group;

Monocyclic cycloalkenyl groups such as cyclopentenyl group and cyclohexenyl group;

Polycyclic cycloalkyl groups such as norbornyl group, adamantyl group, and tricyclodecyl group;

And polycyclic cycloalkenyl groups such as norbornene and tricyclodecenyl groups.

Examples of the alicyclic structure having 3 to 20 carbon atoms represented by the above-mentioned groups combined with the carbon atoms to which they are bonded are, for example,

Monocyclic cycloalkane structures such as cyclopropane structure, cyclobutane structure, cyclopentane structure, cyclohexane structure, cycloheptane structure, cyclooctane structure;

And polycyclic cycloalkane structures such as norbornane structure, adamantane structure, tricyclodecane structure, and 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 a plurality of these divalent hydrocarbon groups, -O-, -COO-, and the like. And combinations of groups. 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 of R ² in the formula (1). As R ^{B, a} divalent chain hydrocarbon group, a divalent alicyclic hydrocarbon group, and a group in which a divalent chain hydrocarbon group and -COO- are combined are preferable, and an alkanediyl group, cycloalkanediyl group, alkanediylcarbonyloxyalkanediyl group More preferably, methanediyl group, ethanediyl group, cyclohexanediyl group, norbornanediyl group, adamantanediyl group, methanediylcarbonyloxypropanediyl group is more preferable, ethanediyl group, adamantanediyl group is particularly preferable. desirable.

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.

As R ^C and R ^D , a hydrogen atom and a chain hydrocarbon group are preferable, a hydrogen atom and an alkyl group are more preferable, and a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, and an i-propyl group are more preferable, and a hydrogen atom, a methyl group, and i -Propyl group is particularly preferred.

Examples of the alicyclic structure of the reduced water 3 to 20 formed by combining the groups of R ^C and R ^D with each other include, for example, a monocyclic cycloalkane structure such as a cyclopentane structure, a cyclohexane structure, and a cyclooctane structure; And polycyclic cycloalkane structures such as norbornane structure and adamantane structure. Among these, a monocyclic cycloalkane structure is preferable, and a cyclohexane structure is more preferable.

As R ^{E, a} chain hydrocarbon group and an alicyclic hydrocarbon group are preferable, a chain hydrocarbon group is more preferable, an alkyl group is more preferable, and a methyl group and a t-butyl group are particularly preferable.

As the ring structure of the reduced water from 5 to 20 in which the R ^B and R ^E configuration combined with each other, for example, and the like dioxa cyclopentane structure, dioxa cyclohexane structure, dioxa-cycloalkyl-dioxa cycloalkane structure, such as heptane structure Can be. Among these, the dioxacyclopentane structure and the dioxacyclohexane structure are preferable, and the 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 referred to as “structural units (II-1-1) to (II-1-4)” ) ”Is also preferred.

In the formulas (2-1-1) to (2-1-4), R ⁶ to R ⁹ are as defined in the formulas (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 formula.

In the above formula, R ⁶ is as defined in the above formula (2-1).

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

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

In the formulas (2-2-1) and (2-2-2), R ^A , R ^C and R ^D are synonymous with the formula (2-2). R ^b is a divalent hydrocarbon group having 1 to 19 carbon atoms. h is an integer from 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 formula.

In the above formula, R ^A is as defined 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, derived from alkoxyalkoxycycloalkyl (meth) acrylate The structural unit is preferable, and 2,2-dimethyl-1,3-dioxycyclopentane-yl (meth) acrylate and t-butoxy-i-butoxy adamantane-yl (meth) acrylate are more preferable. .

The content ratio of the structural unit (II) is preferably 10 mol% to 80 mol%, more preferably 20 mol% to 70 mol%, and more preferably 25 mol% to 60 mol, relative to the total structural units constituting the polymer [A]. Molar% is more preferable. By setting the content ratio in the above range, the sensitivity and resolution of the photoresist composition are further improved, resulting in improved EL performance, LWR performance and CDU performance. When the content ratio is less than the lower limit, the pattern formability of the photoresist composition may be lowered. When the content ratio exceeds the upper limit, the adhesion of the resist pattern to the substrate may decrease.

[Structural Unit (III)]

The structural unit (III) is a structural unit other than the structural unit (I), and is a structural unit containing at least one member selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. [A] The polymer has a structural unit (III) in addition to the structural unit (I), so that the solubility in a developer can be further adjusted, and as a result, EL performance, LWR performance and CDU performance of the photoresist composition can be improved. have. In addition, adhesion between the resist pattern formed from the photoresist composition and the substrate can be improved.

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

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

As the structural unit (III), among them, a structural unit containing a norbornanelactone structure, a structural unit comprising a γ-butyrolactone structure, a structural unit containing an ethylene carbonate structure, and a norbornanesultone structure The structural unit to be preferred is preferably a structural unit derived from norbornanelactone-yl (meth) acrylate, a structural unit derived from cyano-substituted norbornanelactone-yl (meth) acrylate, norbornanelactone-yl Structural units derived from cycarbonylmethyl (meth) acrylate, structural units derived from γ-butyrolactone-yl (meth) acrylate, and structural units derived from ethylene carbonate-ylmethyl (meth) acrylate , Structural units derived from norbornansultone-yl (meth) acrylate, structural units derived from norbornansultone-yloxycarbonylmethyl (meth) acrylate are more bar It is recommended.

The content ratio of the structural unit (III) is preferably 0 mol% to 70 mol%, more preferably 10 mol% to 65 mol%, and 25 mol% to 55 mol. With respect to the total structural units constituting the polymer [A]. Molar% is more preferable. By setting the said content ratio in the said range, the adhesiveness of the resist pattern formed from the said photoresist composition to a board | substrate can be improved more. When the content ratio is less than the lower limit, adhesion of the resist pattern formed from the photoresist composition to the substrate may decrease. When the content ratio exceeds the upper limit, the pattern formability of the photoresist composition may be lowered.

[Other structural units]

[A] The polymer may have other structural units other than the structural units (I) to (III). As another structural unit, a structural unit containing a hydroxyl group, etc. are mentioned, for example.

As a structural unit containing the said hydroxy group, the structural unit etc. which are represented by the following formula are mentioned, for example.

In the above formula, R ^L2 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

The content ratio of the structural unit containing the hydroxy group is preferably 30 mol% or less, preferably 20 mol% or less, and more preferably 3 mol% to 15 mol% relative to the total structural units constituting the polymer [A]. Do. When the content ratio exceeds the upper limit, the pattern formability of the photoresist composition may be lowered.

[A] The polymer may have other structural units in addition to the above structural units. The content ratio of the other structural units is preferably 20 mol% or less, and more preferably 10 mol% or less.

[A] As the content of the polymer, 70% by mass or more is preferable, more preferably 80% by mass or more, and even more preferably 85% by mass or more, among the total solids of the photoresist composition.

<[A] Synthesis method of polymer>

The polymer [A] can be synthesized, for example, by polymerizing a monomer providing 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), and 2,2'-azobis (2-cyclopropyl). Azo-based radical initiators such as propionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), and dimethyl2,2'-azobisisobutylate; And peroxide-based radical initiators such as benzoyl peroxide, t-butyl hydroperoxide and cumene hydroperoxide. Of these, AIBN, dimethyl2,2'-azobisisobutylate is preferred, and AIBN is more preferred. These radical initiators may be used alone or in combination of two or more.

As a solvent used for the said polymerization, for example,

alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane;

Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin and norbornane;

Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene and cumene;

Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylenedibromide, and 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 and 2-heptanone;

Ethers such as tetrahydrofuran, dimethoxyethanes and diethoxyethanes;

And 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.

The reaction temperature in the polymerization is usually 40 ° C to 150 ° C, preferably 50 ° C to 120 ° C. The reaction time is usually 1 hour to 48 hours, and preferably 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, more preferably 3,000 or more and 20,000 or less More preferably, 5,000 or more and 15,000 or less are particularly preferable. When the Mw of the polymer [A] is within the above range, the coating property and the development defect suppression property of the photoresist composition are improved. When the Mw of the polymer [A] is less than the above lower limit, a resist film having sufficient heat resistance may not be obtained. When the Mw of the polymer [A] exceeds the above upper limit, the developability of the resist film may decrease.

[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 1 or more and 5 or less, preferably 1 or more and 3 or less, and more preferably 1 or more and 2 or less. .

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 (manufactured by Wako Junyaku High School)

Flow rate: 1.0 mL / min

Sample concentration: 1.0 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 acid by exposure. The acid-dissociable group possessed by the polymer [A] and the like is dissociated by the generated acid to generate a carboxy group, and the solubility of the polymer [A] in the developer containing the organic solvent decreases. As a form of containing the acid generator of [B] in the photoresist composition capable of forming a resist pattern of, the form of a low-molecular compound as described below (hereinafter, also appropriately referred to as "[B] acid generator") ), Or in the form of an acid generator inserted as part of the polymer, or both.

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

As an onium salt compound, sulfonium salt, tetrahydrothiophenium salt, iodonium salt, phosphonium salt, diazonium salt, pyridinium salt, etc. are mentioned, for example.

As the sulfonium salt, for example, triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1] hep-2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium2-bicyclo [2.2.1] hep-2-yl-1 , 1-difluoroethanesulfonate, triphenylsulfonium camposulfonate, 4-cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butane Sulfonate, 4-cyclohexylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hep-2-yl-1,1, 2,2-tetrafluoroethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium camposulfonate, 4-methanesulfonylphenyldiphenylsulfonium trifluoromethanesulfonate, 4 -Methanesulfonylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium2 -Bicyclo [2.2.1] hep-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium camposulfonate, triphenylsulfonium1,1 And 2,2-tetrafluoro-6- (1-adamantanecarbonyloxy) -hexane-1-sulfonate.

As the tetrahydrothiophenium salt, for example, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxynaphthalene-1- 1) Tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- ( 4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium2-bicyclo [2.2.1] hep-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- ( 4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium camposulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium perfluoro Low-n-octanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothi Phenium2-bicyclo [2.2.1] hep-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophene Niumcamposulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiopheniumtrifluoromethanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydroty Ophenium nonafluoro-n-butanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (3,5-dimethyl -4-hydroxyphenyl) tetrahydrothiophenium2-bicyclo [2.2.1] hep-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (3,5-dimethyl And -4-hydroxyphenyl) tetrahydrothiophenium camposulfonate.

As the iodonium salt, for example, diphenyl iodonium trifluoromethanesulfonate, diphenyl iodonium nonafluoro-n-butanesulfonate, diphenyl iodonium perfluoro-n-octanesulfonate, Diphenyl iodonium 2-bicyclo [2.2.1] hep-2-yl-1,1,2,2-tetrafluoroethanesulfonate, diphenyliodonium camposulfonate, 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) iodonium2-bicyclo [2.2.1] hep-2-yl-1,1,2,2-tetrafluoroethanesulfonate, bis And (4-t-butylphenyl) iodonium camphorsulfonate.

As the N-sulfonyloxyimide compound, for example, N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboxyimide, N- (nonafluoro -n-butanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboxyimide, N- (perfluoro-n-octanesulfonyloxy) bicyclo [2.2.1] Hept-5-ene-2,3-dicarboxyimide, N- (2-bicyclo [2.2.1] hep-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy) bicyclo [2.2.1] Hept-5-ene-2,3-dicarboxyimide, N- (2- (3-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10 ] dodecanyl) -1,1- Difluoroethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboxyimide, N- (camposulfonyloxy) bicyclo [2.2.1] hept-5-ene- And 2,3-dicarboxyimide.

[B] As the acid generator, a compound represented by the following formula (3) is preferable. [B] It is thought that the diffusion length of the acid generated by exposure in the resist film is shortened more appropriately due to the interaction of the polymer (A) with the structural unit (I) by the acid generator having the following structure, and as a result EL performance, LWR performance and CDU performance of the photoresist composition may be improved.

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

The "reduction number" in R ¹⁰ refers to the number of atoms constituting a ring of an alicyclic structure and an aliphatic heterocyclic structure, and in the case of a polycyclic alicyclic structure and a polycyclic aliphatic heterocyclic structure, refers to the number of atoms constituting this polycyclic ring. .

As the monovalent group containing a cycloaliphatic structure of reduced water over 7 represented by the above R ^10, e.g.

Monocyclic cycloalkyl groups such as cyclooctyl group, cyclononyl group, cyclodecyl group, and cyclododecyl group;

Monocyclic cycloalkenyl groups such as cyclooctenyl groups and cyclodecenyl groups;

Polycyclic cycloalkyl groups such as norbornyl group, adamantyl group, tricyclodecyl group, and tetracyclododecyl group;

And polycyclic cycloalkenyl groups such as norbornene and tricyclodecenyl groups.

As a monovalent group containing the aliphatic heterocyclic structure of 7 or more of the reducing water represented by R ¹⁰ , for example,

Groups including lactone structures such as norbornanelactone-yl group;

Groups including sultone structures such as norbornanesultone-diary;

An oxygen atom-containing heterocyclic group such as an oxacycloheptyl group and an oxanorbornyl group;

Nitrogen atom-containing heterocyclic groups such as an azacycloheptyl group and a diazabicyclooctane-yl group;

And sulfur atom-containing heterocyclic groups such as a thiacycloheptyl group and a thianorbornyl group.

As the reducing water of the group represented by R ¹⁰ , 8 or more are preferable, 9 to 15 are more preferable, and 10 to 13 are more preferable from the viewpoint of making the diffusion length of the above-mentioned acid more appropriate.

As R ¹⁰ , among these, a monovalent group containing an alicyclic structure of 9 or more of reduced water, a monovalent group containing an aliphatic heterocyclic structure of 9 or more of reduced water is preferable, and an adamantyl group, hydroxyadamantyl group, norbornanlactone-yl group , 5-oxo-4- ^oxatricyclo [4.3.1.1 ^3,8 ] undecane-yl group is more preferable, and adamantyl group is more preferable.

As the fluorinated alkanediyl group having 1 to 10 carbon atoms represented by R ¹¹ , for example, at least one hydrogen atom having an alkanediyl group having 1 to 10 carbon atoms such as methanediyl group, ethanediyl group, and propanediyl group may be used. And groups substituted with fluorine atoms.

Among these, a fluorinated alkanediyl group in which a fluorine atom is bonded to a carbon atom adjacent to the SO ₃ ^- group is preferable, and a fluorinated alkanediyl group in which two fluorine atoms are bonded to a carbon atom adjacent to the SO ₃ ^- group is more preferable, 1,1-difluoromethanediyl group, 1,1-difluoroethanediyl group, 1,1,3,3,3-pentafluoro-1,2-propanediyl group, 1,1,2, 2-tetrafluoroethane diyl group, 1,1,2,2-tetrafluorobutanediyl group, 1,1,2,2-tetrafluorohexanediyl group is more preferable.

The monovalent photodegradable onium cation represented by X ⁺ is a cation decomposed by irradiation with exposure light. In the exposed portion, sulfonic acid is generated from protons and sulfonate anions generated by decomposition of the photodegradable onium cation. The monovalent photodegradable onium cation represented by X ⁺ includes elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, Bi, for example. And radiation-decomposable onium cations. Examples of the cation containing S (sulfur) as an element include, for example, sulfonium cations, tetrahydrothiophenium cations, and the like, and examples of elements containing I (iodine) include iodonium cations. have. Of these, sulfonium cations represented by the following formula (X-1), tetrahydrothiophenium cations represented by the following formula (X-2), and iodonium cations represented by the following formula (X-3) are preferred. Do.

In the 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, a substituted or unsubstituted aromatic having 6 to 12 carbon atoms. A hydrocarbon group, -OSO ₂ -R ^P or -SO ₂ -R ^Q , or two or more of these groups are combined with each other to represent a ring structure. R ^P and R ^Q are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms, or a substituted or unsubstituted carbon atom having 6 to 6 carbon atoms. It is an aromatic hydrocarbon group of 12. k1, k2 and k3 are each independently an integer from 0 to 5. When R ^a1 to R ^a3, and R ^P and R ^Q are each individual plurality, the plurality of R ^a1 to R ^a3, and R ^P and R ^Q may be the same or different from each other.

In the formula (X-2), R ^b1 is a substituted or unsubstituted linear or branched alkyl group having 1 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms. k4 is an integer from 0 to 7. When there are plural R ^{b1 s} , a plurality of R ^{b1 s} may be the same or different, and a plurality of R ^{b1 s} may represent a ring structure formed by merging 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 from 0 to 6. When R ^b2 multiple individual, a plurality of R ^b2 may be the same or different, a plurality of R ^b2 may represent a ring structure consisting combined with each other. q is an integer from 0 to 3.

In the formula (X-3), R ^c1 and R ^c2 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, -OSO ₂ -R ^R or -SO ₂ -R ^S , or two or more of these groups are combined with each other to represent a ring structure. R ^R and R ^S are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms, or a substituted or unsubstituted 6 to 6 carbon atoms. It is an aromatic hydrocarbon group of 12. k6 and k7 are each independently an integer of 0-5. R ^c1, R ^c2, R ^R and R ^S are a plurality if each individual, a plurality of R ^c1, R ^c2, R ^R and R ^S are the same or each may be 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, for example, a methyl group, ethyl group, n-propyl group, n-butyl group, and the like. have.

Examples of the unsubstituted branched alkyl group represented by R ^a1 to R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include, for example, i-propyl group, i-butyl group, sec-butyl group, t- And butyl groups.

Examples of the unsubstituted aromatic hydrocarbon groups represented by R ^a1 to R ^a3 , R ^c1 and R ^c2 include, for example, aryl groups such as a phenyl group, tolyl group, xylyl group, mesityl group, and naphthyl group; Aralkyl groups, such as a benzyl group and a phenethyl group, are mentioned.

As an unsubstituted aromatic hydrocarbon group represented by said R ^b1 and R ^b2 , a phenyl group, a tolyl group, a benzyl group, etc. are mentioned, for example.

Examples of the substituent that may be substituted for the hydrogen atom of the alkyl group and the aromatic hydrocarbon group include halogen atoms such as fluorine atom, chlorine atom, bromine atom, and iodine atom, hydroxy group, carboxy group, cyano group, nitro group, alkoxy group, And an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, and an acyloxy group.

Of these, halogen atoms are preferred, and fluorine atoms are more preferred.

As R ^a1 to R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^{c2, an} unsubstituted linear or branched alkyl group, a fluorinated alkyl group, an unsubstituted monovalent aromatic hydrocarbon group, -OSO ₂ -R ",- SO ₂ -R "is preferable, a fluorinated alkyl group, an unsubstituted monovalent aromatic hydrocarbon group is more preferable, and a fluorinated alkyl group is more preferable. 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), an integer of 0 to 2 is preferable, 0 or 1 is more preferable, and 0 is more preferable.

As k4 in the said Formula (X-2), the integer of 0-2 is preferable, 0 or 1 is more preferable, and 1 is still more preferable. As k5, the integer of 0-2 is preferable, 0 or 1 is more preferable, and 0 is still more preferable.

As k6 and k7 in the said Formula (X-3), the integer of 0-2 is preferable, 0 or 1 is more preferable, and 0 is still more preferable.

As the acid generator represented by the above formula (3), for example, compounds represented by the following formulas (3-1) to (3-10) (hereinafter, "compounds (3-1) to (3-10)" Also known as).

[B] As an acid generator, an onium salt compound is preferable, a sulfonium salt and a tetrahydrothiophenium salt are more preferable, and compounds (3-1) to (3-5) are more preferable.

[B] As the content of the acid generator, [B] when the acid generator is the [B] acid generator, from the viewpoint of ensuring the sensitivity and developability of the photoresist composition, [A] 0.1 mass to 100 parts by mass of the polymer More than 30 parts by mass is preferable, more than 0.5 parts by mass and more preferably 20 parts by mass or less, and even more preferably 1 part by mass or more and 15 parts by mass or less. [B] By setting the content of the acid generator in the above range, the sensitivity and developability of the photoresist composition are improved. [B] One or two or more acid generators may be used.

<[C] acid diffusion control body>

The photoresist composition may contain [C] an acid diffusion control body as necessary.

The acid diffusion control body [C] controls the diffusion phenomenon of the acid generated from the acid generator [B] in the resist film by exposure, and exerts an effect of suppressing undesirable chemical reactions in the non-exposed region, , The storage stability of the resulting photoresist composition is further improved, and the resolution as a resist is further improved, and at the same time, a change in the line width of the resist pattern due to a variation in the delay time after exposure from exposure to development processing can be suppressed, thereby improving process stability. An excellent photoresist composition is obtained. As the content form in the photoresist composition of the [C] acid diffusion control body, it is in the form of a liberated compound (hereinafter, appropriately referred to as "[C] acid diffusion control agent"), or a form inserted as part of the polymer. Or it may be in the form of both.

[C] As the acid diffusion control agent, for example, 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, " Nitrogen-containing compound (II) ”, a compound having three nitrogen atoms (hereinafter also referred to as“ nitrogen-containing compound (III) ”), an amide group-containing compound, a urea compound, and a nitrogen-containing heterocyclic compound. have.

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

Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine; Dialkylamines such as di-n-butylamine; Trialkylamines such as triethylamine; And aromatic amines such as aniline.

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.

As the amide group-containing compound, for example, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pi And lollydon, N-methylpyrrolidone, and the like.

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

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

Further, as the nitrogen-containing organic compound, a compound having an acid-dissociable group can also be used. Examples of the nitrogen-containing organic compound having such an acid-dissociable group include Nt-butoxycarbonylpiperidine, Nt-butoxycarbonylimidazole, Nt-butoxycarbonylbenzimidazole, and Nt-butoxycar Carbonyl-2-phenylbenzimidazole, N- (t-butoxycarbonyl) di-n-octylamine, N- (t-butoxycarbonyl) diethanolamine, N- (t-butoxycarbonyl) Dicyclohexylamine, N- (t-butoxycarbonyl) diphenylamine, Nt-butoxycarbonyl-4-hydroxypiperidine, Nt-amyloxycarbonyl-4-hydroxypiperidine, etc. Can be lifted.

Further, as the acid diffusion control agent [C], a photodegradable base that is light-sensitive by exposure to generate a weak acid may be used. Examples of the photodegradable base include onium salt compounds that decompose by exposure and lose acid diffusion control. Examples of the onium salt compound include sulfonium salt compounds represented by the following formula (5-1), iodonium salt compounds represented by the following formula (5-2), and the like.

In the 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 selected from ^{OH -, R β -COO -,} R β -SO 3 - Or it is an anion represented by the following general formula (5-3). However, R ^β is an alkyl group, an aryl group, or an aralkyl group.

In the formula (5-3), R ²⁰ is a straight or branched alkyl group having 1 to 12 carbon atoms, which may be partially or entirely substituted with a fluorine atom, or a straight or branched chain having 1 to 12 carbon atoms. It is an alkoxyl group. u is an integer from 0 to 2.

As said photo-disintegrative base, the compound etc. which are represented by the following formula are mentioned, for example.

As said photo-disintegrating base, a sulfonium salt is preferable among these, a triarylsulfonium salt is more preferable, triphenylsulfonium salicylate, triphenylsulfonium 10-camposulfonate is more preferable, and triphenylsulfonium 10-Camposulfonate is particularly preferred.

[C] As the content of the acid diffusion control body, [C] when the acid diffusion control body is the [C] acid diffusion control agent, [A] 0 to 20 parts by mass is preferable with respect to 100 parts by mass of the polymer, and 0.1 to 15 parts by mass Addition is more preferable, and 0.3 to 10 parts by mass is more preferable. [C] When the content of the acid diffusion control agent 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 the [A] polymer). When the photoresist composition contains the polymer [D], when the resist film is formed, the distribution tends to be localized in the vicinity of the surface of the resist film due to the oil-repellent characteristics of the fluorine-containing polymer in the film. It is possible to suppress the elution of an acid generator or an acid diffusion control agent in the immersion medium. In addition, the water-repellent characteristics of this [D] polymer can control the forward contact angle of the resist film and the immersion medium to a desired range, so that the occurrence of bubble defects can be suppressed. In addition, the retracting contact angle between the resist film and the immersion medium becomes high, and scan exposure can be performed at high speed without leaving water droplets. Thus, when the said photoresist composition contains [D] polymer, a resist film suitable for a liquid immersion exposure method can be formed.

The polymer [D] is not particularly limited as long as it is a polymer having a fluorine atom, but it is preferable to have a higher fluorine atom content (mass%) than the polymer [A] in the photoresist composition. The higher the fluorine atom content than the [A] polymer, the higher the degree of localization described above, and the more excellent the properties of the resulting resist film, such as water repellency and elution inhibition.

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

As the [D] polymer, it is preferable to have at least one member selected from the group consisting of the following structural units (Da) and (Db). [D] The polymer may have one or two 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] The polymer has a structural unit (Da), so that the content of fluorine atoms can be adjusted.

In the formula (6a), R ^D 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.

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

Examples of the aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms having at least one fluorine atom represented by R ^E include, for example, a monofluorocyclopentyl group, difluorocyclopentyl group, perfluorocyclopentyl group, and monofluoro Locyclohexyl group, difluorocyclopentyl group, perfluorocyclohexylmethyl group, fluoronorbornyl group, fluoroadamantyl group, fluorobornyl group, fluoroisobornyl group, fluorotricyclodecyl group, fluorotetra And cyclodecyl groups.

As a monomer providing the structural unit (Da), for example, trifluoromethyl (meth) acrylic acid ester, 2,2,2-trifluoroethyl (meth) acrylic acid ester, 2,2,2-trifluoro Ethyloxycarbonyl methyl (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-octafluoropentyl) (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 Le, difluorocyclopentyl (meth) acrylic acid ester, perfluorocyclopentyl (meth) acrylic acid ester, monofluorocyclohexyl (meth) acrylic acid ester, difluorocyclopentyl (meth) acrylic acid ester, perfluorocyclo Hexyl methyl (meth) acrylic acid ester, fluoronorbornyl (meth) acrylic acid ester, fluoroadamantyl (meth) acrylic acid ester, fluorobornyl (meth) acrylic acid ester, fluoroisobornyl (meth) acrylic acid ester, And fluorotricyclodecyl (meth) acrylic acid esters, fluorotetracyclodecyl (meth) acrylic acid esters, and the like.

Among them, 2,2,2-trifluoroethyloxycarbonylmethyl (meth) acrylic acid ester is preferred.

As content ratio of structural unit (Da), 5 mol% to 95 mol% is preferable, 10 mol% to 90 mol% is more preferable, and 30 mol% to 85 mol% with respect to the whole structural unit which comprises polymer [D] Molar% is more preferable. By setting it as such a content ratio, the higher dynamic contact angle of the surface of a resist film 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), hydrophobicity is increased, and thus the dynamic contact angle of the surface of the resist film formed of the photoresist composition can be further improved.

In the formula (6b), R ^F is a hydrogen atom, a methyl group or a trifluoromethyl group. R ²¹ is a (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 -CO-NH at the terminal of the R ²² side of R ²¹ It also includes a structure in which-is combined. R 'is a hydrogen atom or a monovalent organic group. R ²² is a single bond, a C 1 to C 10 divalent chain hydrocarbon group, or a C 4 to C 20 divalent aliphatic cyclic hydrocarbon group. X ² is a divalent chain hydrocarbon group having 1 to 20 carbon atoms 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. * Represents a binding site that binds R ²¹ . R ²³ is a hydrogen atom or a monovalent organic group. s is an integer from 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, respectively.

When R ²³ is a hydrogen atom, it is preferable from the viewpoint of improving the solubility of the polymer [D] in the alkali developer.

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.

As said structural unit (Db), the structural unit etc. which are represented by following formula (6b-1)-(6b-3) are mentioned, for example.

In the 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 synonymous with the above formula (6b). When s is 2 or 3, a plurality of X ² and R ²³ may be the same or different, respectively.

The content ratio of the structural unit (6b) is preferably 0 mol% to 90 mol%, more preferably 5 mol% to 85 mol%, and more preferably 10 mol% to 10 mol% with respect to the total structural units constituting the polymer [D]. 80 mol% is more preferable. By setting it as such a content ratio, the surface of the resist film formed from the said photoresist composition can improve the fall of the dynamic contact angle in alkali development.

[Structural Unit (Dc)]

[D] In addition to the structural units (Da) and (Db), the polymer may have a structural unit (hereinafter also referred to as “structural unit (Dc)”) containing an acid dissociable group (however, the structural unit (Db)) Except for). [D] When the polymer has a structural unit (Dc), the shape of the resulting resist pattern becomes better. As a structural unit (Dc), the structural unit (II) etc. in the above-mentioned [A] polymer are mentioned.

The content ratio of the structural unit (Dc) is preferably 5 mol% to 90 mol%, more preferably 10 mol% to 70 mol%, and 15 mol% to 15 mol% with respect to the total structural units constituting the polymer [D]. 60 mol% is more preferable, and 15 mol% to 50 mol% is particularly preferable. When the content ratio of the structural unit (Dc) is less than the above lower limit, the occurrence of developing defects in the resist pattern may not be sufficiently suppressed. When the content ratio of the structural unit (Dc) exceeds the above upper limit, the hydrophobicity of the surface of the resulting resist film may decrease.

[Other structural units]

Further, the polymer [D] is a structural unit including at least one structure selected from the group consisting of, for example, a structural unit containing an alkali-soluble group, a lactone structure, a cyclic carbonate structure, and a sultone structure, in addition to the above structural units. , It 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. As a structural unit which has at least 1 type of structure chosen from the group which consists of a lactone structure, a cyclic carbonate structure, and a sultone structure, the structural unit (III) in the above-mentioned [A] polymer is mentioned.

As content ratio of the said other structural unit, it is 30 mol% or less normally with respect to the whole structural unit which comprises [D] polymer, and 20 mol% or less is preferable. When the content ratio of the other structural units exceeds the upper limit, the pattern formability of the photoresist composition may be deteriorated.

The content of the polymer [D] in the photoresist composition is preferably 0 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, and more preferably 1 to 10 parts by mass relative to 100 parts by mass of the polymer [A]. Addition is more preferred. When the content of the polymer [D] exceeds the above upper limit, the pattern formability of the photoresist composition may be deteriorated.

<[E] solvent>

The photoresist composition usually contains a [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 [C] acid diffusion control body contained as necessary.

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

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, green Monoalcohol-based solvents such as furyl alcohol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, and 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, Polyhydric alcohol solvents such as 2-ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and 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 mono Methyl 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 And polyhydric alcohol partial ether-based solvents such as glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, and dipropylene glycol monopropyl ether.

As an ether solvent, for example,

Dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether;

Cyclic ether-based solvents such as tetrahydrofuran and tetrahydropyran;

And aromatic ring-containing ether solvents such as diphenyl ether and anisole (methylphenyl ether).

Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, and 2-heptanone (methyl-n-pentyl ketone). ), Ethyl-n-butyl ketone, methyl-n-hexyl ketone, di-iso-butyl ketone, trimethyl nonanone and other chain ketone solvents:

Cyclic ketone-based solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, and methylcyclohexanone:

And 2,4-pentanedione, acetonyl acetone, and acetophenone.

Examples of the amide solvent include cyclic amide solvents such as N, N'-dimethylimidazolidinone and N-methylpyrrolidone;

Chain amides such as N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide and N-methylpropionamide And solvents.

As an ester solvent, for example,

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-me acetate Acetic acid ester solvents such as methoxybutyl, 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 Polyhydric alcohol partial ether acetate-based solvents such as monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, and dipropylene glycol monoethyl ether acetate;

lactone-based solvents such as γ-butyrolactone and valerolactone;

Carbonate-based solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate;

Diacetic acid glycol, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl acetoacetate, ethyl acetate, ethyl lactate, methyl lactate, ethyl lactate n -Butyl, n-amyl lactate, diethyl malonate, dimethyl phthalate, diethyl phthalate, and the like.

As a hydrocarbon-based solvent, for example

Aliphatic such as n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, cyclohexane, methylcyclohexane Hydrocarbon-based solvents;

Benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, iso-propylbenzene, diethylbenzene, iso-butylbenzene, triethylbenzene, di-iso-propylbenzene, n And aromatic hydrocarbon-based solvents such as amyl naphthalene.

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

<Other optional ingredients>

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. One or two or more of these other optional components may be used in combination.

(Surfactants)

The surfactant exerts an 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, and polyethylene glycol dilau. Nonionic surfactants such as rate and polyethylene glycol distearate; As commercial products, KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), polyflow No.75, copper No.95 (above, manufactured by Kyoeisha Chemical Co., Ltd.), F-top EF301, copper EF303, copper EF352 (above, manufactured by Tochem Products) , Megaface F171, Copper F173 (above, manufactured by DIC), Fluorad FC430, Copper FC431 (above, manufactured by Sumitomo 3M), Asahi Guard AG710, Sufflon S-382, Copper SC-101, Copper SC-102, Copper And SC-103, copper SC-104, copper SC-105, and copper SC-106 (above, manufactured by Asahi Glass High School). The content of the surfactant in the photoresist composition is usually 2 parts by mass or less based on 100 parts by mass of the polymer [A].

(An alicyclic skeleton-containing compound)

The alicyclic skeleton-containing compound exerts an effect of improving dry etching resistance, pattern shape, adhesion to a substrate, and the like.

Examples of the alicyclic skeleton-containing compound include

Adamantane derivatives such as 1-adamantane carboxylic acid, 2-adamantanone, and 1-adamantanecarboxylic acid t-butyl;

Deoxycholic acid esters such as t-butyl deoxycholic acid, t-butoxycarbonylmethyl deoxycholic acid and 2-ethoxyethyl deoxycholic acid;

Litocholic acid esters, such as t-butyl Litocholate, t-butoxycarbonylmethyl Litocholate, and 2-ethoxyethyl Litocholate;

3- [2-hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] dodecane, 2-hydroxy-9-methoxycarbonyl And -5-oxo-4-oxa-tricyclo [4.2.1.0 ^{3, 7} ] nonane. The content of the alicyclic skeleton-containing compound in the photoresist composition is usually 5 parts by mass or less based on 100 parts by mass of the polymer [A].

(Sensitizer)

The sensitizer exhibits an action of increasing the amount of acid generated from the acid generator (B), and exhibits an effect of improving the "apparent sensitivity" of the photoresist composition.

Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rosebengal, pyrenes, anthracene, phenothiazines, and the like. These sensitizers may be used alone or in combination of two or more. The content of the sensitizer in the photoresist composition is usually 2 parts by mass or less based on 100 parts by mass of the polymer [A].

<Production method of photoresist composition>

The photoresist composition may be prepared by, for example, mixing the [A] polymer, [B] acid generator, [C] acid diffusion control agent, optional components contained as necessary, and [F] solvent in a predetermined ratio. Can be. It is preferable to filter the photoresist composition after mixing, for example, with a filter having a pore size of about 0.2 µm. The solid content concentration of the photoresist composition is usually 0.1% by mass to 50% by mass, preferably 0.5% by mass to 30% by mass, and more preferably 1% by mass to 20% by mass.

<Negative resist pattern formation method>

The negative resist pattern forming method,

A step of forming a resist film using the photoresist composition (hereinafter also referred to as a "resist film forming process"),

A step of exposing the resist film (hereinafter also referred to as "exposure process"), and

Process of developing the exposed resist film using a developer containing an organic solvent (hereinafter also referred to as "development process")

Have

According to the negative resist pattern forming method, since the above-described photoresist composition is used, a resist pattern having a small LWR and CDU can be formed while exhibiting wide EL. Hereinafter, each process is demonstrated.

[Resist film formation process]

In this step, a resist film is formed using the photoresist composition. Examples of the substrate for forming the resist film include conventionally known ones such as silicon wafers, silicon dioxide, and wafers coated with aluminum. Further, an organic or inorganic antireflection film disclosed in, for example, Japanese Patent Publication (Patent) 6-12452 or Japanese Patent Publication (Small) 59-93448 can be formed on a substrate. As a coating method, rotation coating (spin coating), flexible coating, roll coating, etc. are mentioned, for example. After coating, if necessary, prebaking (PB) may be performed to volatilize the solvent in the coating film. The PB temperature is usually 60 ° C to 140 ° C, preferably 80 ° C to 120 ° C. The PB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds. The film thickness of the formed resist film 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 contained in the environmental atmosphere, a protective film disclosed in, for example, Japanese Patent Laid-Open No. 5-188598 can be formed on the resist film. In addition, in order to prevent leakage of acid generators and the like from the resist film, a protective film for immersion disclosed in, for example, Japanese Patent Laid-Open No. 2005-352384 can also be formed on the resist film. Moreover, these techniques can be used together.

[Exposure process]

In this step, the resist film formed in the resist film forming step is exposed by irradiating exposure light through a photomask (or 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, depending on the line width of the target pattern; And charged particle beams such as electron beams and α-rays. Among these, far ultraviolet rays and electron beams are preferred, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), and electron beam are more preferable, ArF excimer laser light and electron beam are more preferable.

The exposure method can be appropriately selected depending on the shape of the desired resist pattern or the like. For example, an isotrench pattern can be formed by exposing the desired area through an isoline pattern mask. Moreover, exposure can also be performed twice or more. When exposure is performed twice or more, it is preferable to perform exposure continuously. In the case of multiple exposures, for example, a first exposure is performed through a line-and-space pattern mask on a desired area, and then a second exposure is performed so that lines intersect with the exposure unit that has undergone the first exposure. It is preferable that the first exposure section and the second exposure section are orthogonal. By orthogonal, it is easy to form a contact hole pattern in a circular shape in an unexposed portion surrounded by an exposed portion.

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 transparent to the exposure wavelength, and a liquid having a temperature coefficient of refractive index as small as possible so that the distortion of the optical image projected on the film is minimal, but in particular, when the exposure light source is ArF excimer laser light (wavelength 193 nm) , It is preferable to use water from the viewpoint of availability and handling ease in addition to the above-mentioned viewpoints. When water is used, it is possible to reduce the surface tension of the water and at the same time, add an additive that increases the surface active force in a small proportion. It is preferable that this additive does not dissolve the resist film on the wafer, and the influence on the optical coating of the lower surface of the lens can be neglected. Distilled water is preferable as the water to be used.

After the exposure, post-exposure firing (PEB) is performed to accelerate the dissociation of the acid-dissociable group of the polymer [A] or the like by the acid generated from the acid generator [B] by exposure in the exposed portion of the resist film. desirable. The PEB causes a difference in solubility in the developer in the exposed portion and the unexposed portion. The PEB temperature is usually 50 ° C to 180 ° C, preferably 80 ° C to 130 ° C. The PEB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.

[Development process]

In this step, a 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 a rinse solution such as water or alcohol, and then dry.

Examples of the developer include organic solvents such as hydrocarbon-based solvents, ether-based solvents, ester-based solvents, ketone-based solvents, and alcohol-based solvents, or solvents containing these organic solvents. As said organic solvent, 1 type (s) or 2 or more types of the solvents listed as the [E] solvent of the above-mentioned photoresist composition are mentioned, for example. Among these, ether-based solvents, ester-based solvents, and ketone-based solvents are preferable. As the ether-based solvent, an aromatic-containing ether-based solvent is preferable, and anisole is more preferable. As the ester-based solvent, an acetic acid ester-based solvent is preferable, and n-butyl acetate is more preferable. As a ketone solvent, a chain ketone solvent is preferable, and 2-heptanone is more preferable.

The content of the organic solvent in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 99% by mass or more. By setting the content of the organic solvent in the developer to the above range, the contrast between the exposed portion and the unexposed portion can be improved, and as a result, a resist pattern with a smaller LWR and CDU can be formed while exhibiting a wider EL. Moreover, as components other than an organic solvent, water, silicone oil, etc. are mentioned, for example.

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

As the developing method, for example, a method in which a substrate is immersed in a bath filled with a developer for a certain time (dipping method), a method in which a developer is raised on a surface of a substrate by surface tension and stopped for a certain time (puddle method), substrate A method of spraying a developer onto the surface (spray method), a method of continuously drawing the developer while scanning a nozzle for drawing the developer at a constant speed on a substrate rotating at a constant speed (dynamic dispensing method), and the like. .

It is preferable to wash the resist film after the development with a rinse liquid. An organic solvent can also be used as this rinse liquid, and the generated scum can be cleaned efficiently. As the rinse liquid, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, alcohol-based solvents, and amide-based solvents are preferable. Of these, alcohol-based solvents and ester-based solvents are preferable, and a monovalent alcohol-based solvent having 6 to 8 carbon atoms is more preferable. Examples of the monovalent alcohol having 6 to 8 carbon atoms include linear, branched or cyclic monovalent alcohols, such as 1-hexanol, 1-heptanol, 1-octanol and 4-methyl-2-pentane. And all, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, and benzyl alcohol. Among 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 rinse liquid may be used alone or in combination of two or more. The water content in the rinse liquid is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less. By setting the water content to the above range, good development characteristics can be obtained. In addition, a surfactant may be added to the rinse liquid.

As a method of the cleaning treatment with a rinse liquid, for example, a method of continuously drawing the rinse liquid onto a substrate rotating at a constant speed (rotation coating method), a method of immersing the substrate in a bath filled with a rinse liquid for a certain time (D Ping method), the method of spraying a rinse liquid on the substrate surface (spray method), and the like.

[Example]

Hereinafter, the present invention will be specifically described based on Examples, but the present invention is not limited to these Examples. Methods for measuring various physical property values are shown below.

[Mw and Mn]

The 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 (manufactured by Wako Junyaku High School)

Flow rate: 1.0 mL / min

Sample concentration: 1.0 mass%

Sample injection volume: 100 μL

Detector: Differential refractometer

Standard material: monodisperse polystyrene

[ ¹ H-NMR analysis and ¹³ C-NMR analysis]

¹ H-NMR analysis and ¹³ C-NMR analysis, ¹³ C-NMR analysis for determining the constituent unit content ratio, and a fluorine atom content of the polymer of the compound, was prepared using a nuclear magnetic resonance apparatus (JNM-ECX400, Nihon Denshi Co.) Was measured.

<Synthesis of polymer>

The monomers used for the synthesis of the polymers [A] and [D] are shown below.

[[A] Synthesis of polymers]

[Synthesis Example 1]

12.00 g (50 mol%) of compound (M-1) and 8.00 g (50 mol%) of compound (M-5) were dissolved in 40 g of 2-butanone, and 0.78 g of AIBN as a polymerization initiator (relative to the total number of moles of the compound) 5 mol%) was further dissolved to prepare a monomer solution. After purging nitrogen in a 100 mL three-necked flask containing 20 g of 2-butanone for 30 minutes, heating to 80 ° C. while stirring, and dropping the prepared monomer solution over a period of 4 hours with a dropping funnel. The initiation of dropping was set as the start time of the polymerization reaction, and the polymerization reaction was performed for 6 hours. After completion of the polymerization reaction, the polymerization reaction solution was water-cooled and cooled to 30 ° C or lower. This cooled polymerization reaction solution was charged into 400 g of methanol, and the precipitated white powder was filtered off. The white powder separated by filtration was washed twice with 80 g of methanol, then filtered and dried at 60 ° C. for 17 hours to obtain a white powdery polymer (A-1) (amount 16.2 g, yield 81%). The polymer (A-1) had an Mw of 7,100 and an Mw / Mn of 1.61. ^As a result of ¹³ C-NMR analysis, the content ratio of the structural unit derived from compound (M-1) and the structural unit derived from (M-5) was 50.5 mol% and 49.5 mol%, respectively.

[Synthesis Examples 2 to 17]

Synthesis of polymers (A-2) to (A-15) and polymers (CA-1) and (CA-2) in the same manner as in Synthesis Example 1, except that each monomer of the type and amount shown in Table 1 below was used. Did. In addition, the total mass of the monomers used was 20.0 g. Table 1 shows the content ratio, yield (%), Mw and Mw / Mn ratio of each structural unit of these polymers together.

[[D] Synthesis of polymers]

[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 2,2'-azobis as a polymerization initiator. A monomer solution was prepared by further dissolving 0.74 g of isobutylate. After purging nitrogen in a 300 mL three-necked flask containing 10 g of 2-butanone for 30 minutes, the mixture was heated to 80 ° C while stirring, and the prepared monomer solution was added dropwise over 4 hours using a dropping funnel. The initiation of dropping was set as the start time of the polymerization reaction, and the polymerization reaction was performed for 6 hours. After completion of the polymerization reaction, the polymerization reaction solution was water-cooled and cooled to 30 ° C or lower. After transferring the polymerization reaction solution to a 500 ml separatory funnel, the polymerization reaction solution was uniformly diluted with 150 g of n-hexane, mixed with 600 g of methanol, and then stirred with 30 g of distilled water and stirred. Let it stand. Thereafter, the lower layer was recovered and subjected to solvent substitution to obtain a polymer (D-1) propylene glycol monomethyl ether solution (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 ratio of the structural unit derived from compound (M-18) and the structural unit derived from compound (M-10) was 80.5 mol% and 19.5 mol%, respectively.

<Production of photoresist composition>

Each component used in the production of the photoresist composition is shown below.

[[B] acid generator]

Each structural formula is shown below.

B-1: triphenylsulfonium adamantan-1-yloxycarbonyldifluoromethanesulfonate

B-2: 4-butoxynaphthalen-1-yltetrahydrothiophenium adamantan-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 control agent]

Each structural formula is shown below.

C-1: Triphenylsulfonium 10-camposulfonate

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 polymer, [B] 4.5 parts by mass of (B-1) as acid generator, [C] 8.7 parts by mass of (C-1) as acid diffusion control agent, [D] 5 parts by weight of (D-1) as a polymer and 1,981 parts by mass of (E-1) as a solvent, and (E-2) 849 parts by mass and (E-3) 100 parts by mass were mixed to form a photoresist composition (J -1) was prepared.

[Examples 2 to 19 and Comparative Examples 1 and 2]

Photoresist compositions (J-2) to (J-19) and (CJ-1) and (CJ-2) were prepared in the same manner as in Example 1, except that each component of the type and content shown in Table 2 below was used. It was prepared.

<Formation of resist pattern>

After applying a composition for forming a lower antireflection film (ARC66, manufactured by Brewer Science) using a spin coater (CLEAN TRACK ACT 12, manufactured by Tokyo Electron) on the surface of a 12-inch silicon wafer, at 205 ° C By heating for 60 seconds, a lower antireflection film having a thickness of 105 nm was formed. Each photoresist composition was applied to the lower antireflection film using the spin coater, and PB was performed at 100 ° C for 60 seconds. Thereafter, the mixture was cooled at 23 ° C for 30 seconds to form a resist film having a film thickness of 90 nm. Subsequently, using the ArF excimer laser immersion exposure apparatus (NSR-S610C, manufactured by Nikon), the resist film was subjected to an optical condition of NA = 1.3, dipole (Sigma 0.977 / 0.782), 44 nm line / 38 nm space. Was exposed through a mask pattern for forming a resist pattern. After exposure, PEB was performed for 60 seconds at the PEB temperature shown in Table 3 below. Thereafter, puddle development was performed at 23 ° C. for 30 seconds using butyl acetate, followed by rinsing for 7 seconds using 4-methyl-2-pentanol, and then spin-dried by centrifugation at 2,000 rpm for 15 seconds to 44 nm. A negative resist pattern of line / 38 nm space was formed.

<Evaluation>

Each photoresist composition was evaluated by measuring the formed resist pattern according to the following method. In addition, a scanning electron microscope (CG-4000, manufactured by Hitachi High Technology) was used to measure the length of 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 optimal exposure amount (Eop), which was taken as sensitivity (mJ / cm ² ). Sensitivity can be evaluated as "good" when 40 mJ / cm ² or less, and "bad" when it exceeds 40 mJ / cm ² .

[EL performance]

When the mask pattern for forming a resist pattern in a 44nm line / 38nm space is used, the ratio of the pattern to be resolved to the Eop in the range of the exposure amount when the mask dimension is within ± 10% of the design dimension of the mask is the EL (exposure margin) ) Performance (%). The larger the value of the EL performance, the smaller the amount of change in the patterning performance with respect to the change in exposure amount, and the better. 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 the top of the pattern using the scanning electron microscope. A total of 500 points of variation in line width was measured, and a 3 sigma value was obtained from the distribution of the measured values, and this was taken as LWR performance (nm). LWR performance is good, so that the value is small, the line fluctuation is small. LWR performance can be evaluated as "good" when it is 3.0 nm or less, and "bad" when it exceeds 3.0.

[CDU performance]

The formed resist pattern was observed from the top of the pattern using the scanning electron microscope. The line width was measured at 20 points in the range of 400 nm, and the average value was measured at a total of 500 points at arbitrary points, and 3 sigma values were obtained from the distribution of the measured values, and this was used as the CDU performance (nm). The smaller the value of the CDU performance, the better the variation in line width in the long period. CDU performance can be evaluated as "good" when 1.5 nm or less, and "bad" when it exceeds 1.5 nm.

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

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

According to the photoresist composition and the resist pattern forming method of the present invention, in forming a negative pattern using a developer containing an organic solvent, a resist pattern having a small LWR and CDU while exhibiting wide EL can be formed. Therefore, the photoresist composition and the method of forming a resist pattern can be preferably used for semiconductor device manufacturing, which is expected to be further refined in the future.

Claims (6)

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

(In the 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 is R ³ is a monovalent chain hydrocarbon group having 1 to 6 carbon atoms or monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms, and R ⁴ and R ⁵ are each independently a hydrogen atom or a monovalent carbon atom having 1 to 6 carbon atoms. A linear hydrocarbon group or a monovalent alicyclic hydrocarbon group having 3 to 15 carbon atoms, or two or more of R ³ , R ⁴ and R ⁵ being combined with each other, and representing an alicyclic structure having 3 to 20 carbon atoms, m being 0 to 3 And n is an integer from 1 to 4, and when R ³ , R ⁴ and R ⁵ are plural, plural R ³ , R ⁴ and R ⁵ may be the same or different, respectively)

(In the formula (3), R ¹⁰ is a monovalent group containing an alicyclic structure of 7 or more of reduced water or a monovalent group containing an aliphatic heterocyclic structure of 7 or more of reduced water, and R ¹¹ is 1 to 10 carbon atoms. Fluorinated alkanediyl group, X ⁺ is a monovalent photodegradable onium cation) The photoresist composition according to claim 1, wherein the polymer further has a second structural unit comprising an acid dissociable group. The polymer according to claim 1, wherein the polymer further has a third structural unit including at least one member selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure as structural units other than the first structural unit. Phosphorus photoresist composition. The photoresist composition according to claim 1, wherein the hydrocarbon group for R ² in the formula (1) is an unsubstituted monocyclic or polycyclic cycloalkanylidene group having 3 to 20 carbon atoms. A process of forming a resist film using the photoresist composition according to any one of claims 1 to 4,
A process of exposing the resist film, and
Process for developing the exposed resist film using a developer containing an organic solvent
A method of forming a negative resist pattern having a. delete