JP4319136B2 - Positive resist composition and resist pattern forming method - Google Patents

Description

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

In recent years, in the manufacture of semiconductor elements and liquid crystal display elements, miniaturization has rapidly progressed due to advances in lithography technology. As a technique for miniaturization, the wavelength of an exposure light source is generally shortened. Specifically, conventionally, ultraviolet rays typified by g-line and i-line were used, but now KrF excimer laser (248 nm) is the center of mass production, and ArF excimer laser (193 nm) is mass-produced. It has begun to be introduced.
Such a resist for a short wavelength light source is required to have high resolution capable of reproducing a pattern with a fine dimension and high sensitivity to such a short wavelength light source. As one of the resists that satisfy such conditions, a chemically amplified resist containing a base resin and an acid generator (PAG) that generates an acid upon exposure is known. There are a positive type in which the alkali solubility of the portion increases and a negative type in which the alkali solubility of the exposed portion decreases.

There is an onium salt as a PAG used in the chemically amplified positive resist composition, and various types have been proposed so far. For example, the following Patent Document 1 describes a PAG composed of a triphenylsulfonium onium salt. Among them, a fluorinated alkyl sulfonate ion such as triphenylsulfonium nonafluorobutanesulfonate (TPS-PFBS) is anion (acid). The most commonly used is an onium salt acid generator.
JP 2003-167347 A

  By the way, when realizing a resist pattern with fine dimensions, the variation in the pattern size (EL margin) when the exposure amount changes is suppressed, and the mask size is faithfully changed when the mask size is changed. Good dimensional fidelity (mask linearity) that can be reproduced in a pattern is an important characteristic, but it is difficult to achieve these simultaneously.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a positive resist composition and a method for forming a resist pattern, which can improve EL margin and dimensional fidelity.

  In order to achieve the above object, the positive resist composition of the present invention comprises a resin component (A) whose alkali solubility is increased by the action of an acid and an acid generator component (B) which generates an acid upon exposure. A positive resist composition containing the onium salt acid generator (B1) having a cation moiety represented by the following general formula (b-1), and the following general formula (b-): It contains an oxime sulfonate acid generator (B2) having a structure represented by 2).

[Wherein, R ¹ ″ represents an alkyl group, an alkoxy group, a halogen atom or a hydroxyl group, and R ² ″ and R ³ ″ each independently represents an aryl group or an alkyl group which may have a substituent. , N represents 0 or an integer of 1 to 3, except that R ² ″ and R ³ ″ are bonded to each other to form a ring.

[Wherein R ²¹ ′ represents an organic group, and R ²² ′ represents a monovalent organic group or a cyano group. ]

  The present invention also provides a resist pattern comprising a step of forming a resist film on a substrate using the positive resist composition of the present invention, a step of exposing the resist film, and a step of developing the resist film to form a resist pattern. A forming method is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the formation method of the positive resist composition and resist pattern which can improve EL margin and dimensional fidelity are provided.

<Resin component (A)>
The component (A) is an alkali-insoluble one having a so-called acid dissociable dissolution inhibiting group, and when acid is generated from the component (B) by exposure, the acid dissociates the acid dissociable dissolution inhibiting group, (A) A component becomes alkali-soluble.
Therefore, in the formation of the resist pattern, when the resist composition applied on the substrate is selectively exposed, the alkali solubility of the exposed portion increases and alkali development can be performed.
The component (A) is not particularly limited, and resins that have been proposed as base resins for chemically amplified positive resist compositions can be used.

・ Structural unit (a1)
The component (A) preferably has a structural unit (a1) derived from an acrylate ester having an acid dissociable, dissolution inhibiting group.
In the following description of examples of positive resist compositions, the meanings of terms are as follows. “Structural unit” refers to a monomer unit constituting a polymer (resin).
“Structural unit derived from acrylic acid” means a structural unit formed by cleavage of an ethylenic double bond of acrylic acid.
The “structural unit derived from an acrylate ester” means a structural unit constituted by cleavage of an ethylenic double bond of an acrylate ester.
In the “structural unit derived from acrylic acid” and “structural unit derived from acrylate ester”, the term “α-position (α-position carbon atom)” means that a carboxy group is present unless otherwise specified. It is a bonded carbon atom.
The “structural unit derived from acrylic acid” is a structural unit in which a hydrogen atom bonded to a carbon atom at the α-position is substituted with another substituent such as a halogen atom, an alkyl group, or a halogenated alkyl group, The concept includes a structural unit derived from an acrylate ester in which a hydrogen atom is bonded to a carbon atom at the position.
Further, the “alkyl group” includes a linear, cyclic or branched alkyl group unless otherwise specified.

The acid dissociable, dissolution inhibiting group in the structural unit (a1) has an alkali dissolution inhibiting property that makes the entire resin component (A) insoluble in alkali before dissociation, and the entire resin component (A) becomes alkali-soluble after dissociation. So far as it is changed, those proposed so far as the acid dissociable, dissolution inhibiting group of the base resin for chemically amplified resist can be used. Generally, a group that forms a cyclic or chain tertiary alkyl ester with a carboxy group of (meth) acrylic acid, or a group that forms a cyclic or chain alkoxyalkyl ester is widely known. . More preferably, it is a group that forms a cyclic or chain tertiary alkyl ester with a carboxy group of (meth) acrylic acid.
“(Meth) acrylic acid ester” means one or both of acrylic acid ester and methacrylic acid ester.

Here, the tertiary alkyl ester is an ester formed by substituting a hydrogen atom of a carboxy group with an alkyl group or a cycloalkyl group, and a carbonyloxy group (—C (O) —O—). ), The tertiary carbon atom of the alkyl group or cycloalkyl group is bonded to the terminal oxygen atom. In this tertiary alkyl ester, when an acid acts, a bond is cut between an oxygen atom and a tertiary carbon atom.
The alkyl group or cycloalkyl group may have a substituent.
Hereinafter, a group that is acid dissociable by constituting a carboxy group and a tertiary alkyl ester is referred to as a “tertiary alkyl ester type acid dissociable, dissolution inhibiting group” for convenience.
The cyclic or chain alkoxyalkyl ester forms an ester by replacing the hydrogen atom of the carboxy group with an alkoxyalkyl group, and the carbonyloxy group (—C (O) —O—) A structure in which the alkoxyalkyl group is bonded to a terminal oxygen atom is shown. In this alkoxyalkyl ester, when an acid acts, a bond is cut between an oxygen atom and an alkoxyalkyl group.

  As the structural unit (a1), one type selected from the group consisting of structural units represented by general formula (a1-0-1) shown below and structural units represented by general formula (a1-0-2) shown below. It is preferable to use the above.

(In the formula, R represents a hydrogen atom, a fluorine atom, a lower alkyl group, or a fluorinated lower alkyl group; X ¹ represents an acid dissociable, dissolution inhibiting group.)

(Wherein R is the same as above; X ² represents an acid dissociable, dissolution inhibiting group; Y ² represents an aliphatic cyclic group.)

In the general formula (a1-0-1), the lower alkyl group as R is an alkyl group having 1 to 5 carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, n- Examples include a lower linear or branched alkyl group such as a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group.
The fluorinated lower alkyl group as R is an alkyl group having 1 to 5 carbon atoms in which some or all of the hydrogen atoms of the alkyl group are substituted with fluorine atoms, It is preferable that all are fluorinated.
The fluorinated lower alkyl group having 1 to 5 carbon atoms is preferably a trifluoromethyl group, a hexafluoroethyl group, a heptafluoropropyl group, a nonafluorobutyl group, or the like, and more preferably a trifluoromethyl group.
X ¹ is not particularly limited as long as it is an acid dissociable, dissolution inhibiting group, and examples thereof include an alkoxyalkyl group, a tertiary alkyl ester type acid dissociable, dissolution inhibiting group, and the like. Acid dissociable, dissolution inhibiting groups are preferred. Examples of the tertiary alkyl ester type acid dissociable, dissolution inhibiting group include an aliphatic branched acid dissociable, dissolution inhibiting group and an acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group.

Here, “aliphatic” in the claims and the specification is a relative concept with respect to aromatics, and is defined to mean a group, a compound, or the like that does not have aromaticity. The “aliphatic cyclic group” means a monocyclic group or polycyclic group having no aromaticity.
The “aliphatic cyclic group” in the structural unit (a1) may or may not have a substituent. Examples of the substituent include a lower alkyl group having 1 to 5 carbon atoms, a fluorine atom, a fluorinated lower alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, an oxygen atom (= O), and the like.
The basic ring structure excluding the substituent of the “aliphatic cyclic group” is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated. A polycyclic group is preferred.
Specific examples of such aliphatic cyclic groups include, for example, monocycloalkanes, bicycloalkanes, trialkyls which may or may not be substituted with a lower alkyl group, a fluorine atom or a fluorinated alkyl group. Examples include groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as cycloalkane or tetracycloalkane. Specific examples include monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.
Specific examples of the aliphatic branched acid dissociable, dissolution inhibiting group include a tert-butyl group and a tert-amyl group.
Examples of the acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group include a group having a tertiary carbon atom on the ring skeleton of a cycloalkyl group. Specifically, 2-methyl- Examples thereof include an adamantyl group and a 2-ethyladamantyl group. Alternatively, as a structural unit represented by the following general formula, a group having an aliphatic cyclic group such as an adamantyl group and a branched alkylene group having a tertiary carbon atom bonded thereto can be given.

[Wherein, R is the same as described above, and R ¹⁵ and R ¹⁶ represent an alkyl group (which may be linear or branched, and preferably has 1 to 5 carbon atoms). ]

  Further, the alkoxyalkyl group is preferably a group represented by the following general formula.

(In the formula, R ²¹ and R ²² are each independently an alkyl group or a hydrogen atom, and R ²³ is an alkyl group or a cycloalkyl group. Alternatively, the ends of R ²¹ and R ²³ are combined to form a ring. You may do it.)

In R ²¹ and R ²² , the alkyl group preferably has 1 to 15 carbon atoms, may be linear or branched, and is preferably an ethyl group or a methyl group, and most preferably a methyl group. In particular, it is preferable that one of R ²¹ and R ²² is a hydrogen atom and the other is a methyl group.
R ²³ is an alkyl group or a cycloalkyl group, preferably having 1 to 15 carbon atoms, and may be linear, branched or cyclic. When R ²³ is linear or branched, it preferably has 1 to 5 carbon atoms, more preferably an ethyl group or a methyl group, and most preferably an ethyl group.
When R ²³ is cyclic, it preferably has 4 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and most preferably 5 to 10 carbon atoms. Specifically, one or more polycycloalkanes such as monocycloalkane, bicycloalkane, tricycloalkane, and tetracycloalkane, which may or may not be substituted with a fluorine atom or a fluorinated alkyl group, are included. Examples include groups excluding hydrogen atoms. Specific examples include monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Among them, a group obtained by removing one or more hydrogen atoms from adamantane is preferable.
In the above formula, R ²¹ and R ²³ are each independently an alkylene group having 1 to 5 carbon atoms, and the end of R ^{23 and} the end of R ²¹ may be bonded.
In this case, a cyclic group is formed by R ²¹ , R ²³ , the oxygen atom to which R ²³ is bonded, and the carbon atom to which the oxygen atom and R ²¹ are bonded. The cyclic group is preferably a 4- to 7-membered ring, and more preferably a 4- to 6-membered ring. Specific examples of the cyclic group include a tetrahydropyranyl group and a tetrahydrofuranyl group.

In general formula (a1-0-2), R is the same as described above. X ² is the same as X ¹ in formula (a1-0-1).
Y ² is a divalent aliphatic cyclic group.
Since Y ² is a divalent aliphatic cyclic group, it is the same as the description of the “aliphatic cyclic group” in the structural unit (a1) except that a group in which two or more hydrogen atoms are removed is used. Can be used.

  More specifically, examples of the structural unit (a1) include structural units represented by the following general formulas (a1-1) to (a1-4).

[In the above formula, X ′ represents a tertiary alkyl ester type acid dissociable, dissolution inhibiting group, Y represents a lower alkyl group having 1 to 5 carbon atoms, or an aliphatic cyclic group; M represents 0 or 1; R is the same as defined above; R ¹ ′ and R ² ′ each independently represent a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms. ]

In the R ¹ ′ and R ² ′, at least one is preferably a hydrogen atom, and more preferably both are hydrogen atoms. n is preferably 0 or 1.

X ′ is the same as the tertiary alkyl ester type acid dissociable, dissolution inhibiting group exemplified in X ¹ above.
Examples of the aliphatic cyclic group for Y include the same as those exemplified in the description of the “aliphatic cyclic group” in the structural unit (a1).

  Specific examples of the structural units represented by the general formulas (a1-1) to (a1-4) are shown below.

As the structural unit (a1), one type may be used alone, or two or more types may be used in combination. Among these, the structural unit represented by general formula (a1-1) and (a1-3) is preferable, and the structural unit represented by general formula (a1-1) is more preferable. Specifically, at least one selected from structural units represented by (a1-1-1) to (a1-1-6) or (a1-1-35) to (a1-1-41) is used. Is more preferable.
Furthermore, as the structural unit (a1), in particular, those represented by the following general formula (a1-1-01) including the structural units of the formulas (a1-1-1) to (a1-1-4) And the following general formula (a1-1-02) including the structural units of the formulas (a1-1-36), (a1-1-38), (a1-1-39) and (a1-1-41) preferable.

(In the formula, R represents a hydrogen atom or a lower alkyl group, and R ¹¹ represents a lower alkyl group.)

(Wherein R represents a hydrogen atom or a lower alkyl group, R ¹² represents a lower alkyl group, h represents an integer of 1 to 3)

In general formula (a1-1-01), R is the same as defined above. The lower alkyl group for R ^{11 is the same as} the lower alkyl group for R, and is preferably a methyl group or an ethyl group.

In general formula (a1-1-02), R is the same as defined above. The lower alkyl group for R ^{12 is the same as} the lower alkyl group for R, preferably a methyl group or an ethyl group, and most preferably an ethyl group. h is preferably 1 or 2, and most preferably 2.

  In the resin component (A), the proportion of the structural unit (a1) is preferably from 10 to 80 mol%, more preferably from 20 to 70 mol%, more preferably from 30 to 50, based on all the structural units constituting the resin component (A). More preferred is mol%. By setting it to the lower limit value or more, a pattern can be obtained when the resist composition is used, and by setting it to the upper limit value or less, it is possible to balance with other structural units.

・ Structural unit (a2)
The resin component (A) preferably has a structural unit (a2) derived from an acrylate ester having a lactone-containing monocyclic or polycyclic group, in addition to the structural unit (a1).
The lactone-containing monocyclic or polycyclic group of the structural unit (a2) increases the adhesion of the resist film to the substrate or the hydrophilicity with the developer when the resin component (A) is used for forming the resist film. It is effective in improving the sex.
Here, the lactone-containing monocyclic or polycyclic group refers to a cyclic group containing one ring (lactone ring) containing an —O—C (O) — structure. The lactone ring is counted as the first ring, and when it is only the lactone ring, it is called a monocyclic group, and when it has another ring structure, it is called a polycyclic group regardless of the structure.

As the structural unit (a2), any structural unit can be used without particular limitation as long as it has both such a lactone structure (—O—C (O) —) and a cyclic group.
Specifically, examples of the lactone-containing monocyclic group include groups in which one hydrogen atom has been removed from γ-butyrolactone. Examples of the lactone-containing polycyclic group include groups in which one hydrogen atom has been removed from a bicycloalkane, tricycloalkane, or tetracycloalkane having a lactone ring. In particular, a group obtained by removing one hydrogen atom from a lactone-containing tricycloalkane having the following structural formula is advantageous in that it is easily available industrially.

  More specifically, examples of the structural unit (a2) include structural units represented by general formulas (a2-1) to (a2-5) shown below.

[Wherein, R is the same as defined above, R ′ is a hydrogen atom, a lower alkyl group, or an alkoxy group having 1 to 5 carbon atoms, and m is an integer of 0 or 1.] ]

In general formulas (a2-1) to (a2-5), the lower alkyl group for R ′ is the same as the lower alkyl group for R in the structural unit (a1).
In general formulas (a2-1) to (a2-5), R ′ is preferably a hydrogen atom in view of industrial availability.

  Specific structural units of the general formulas (a2-1) to (a2-5) are exemplified.

In general formulas (a2-1) to (a2-5), R ′ is preferably a hydrogen atom in view of industrial availability.
Among these, it is preferable to use at least one selected from general formulas (a2-1) to (a2-5), and at least one selected from general formulas (a2-1) to (a2-3). It is preferable to use more than one species. Specifically, chemical formulas (a2-1-1), (a2-1-2), (a2-2-1), (a2-2-2), (a2-3-1), (a2-3) -2), at least one selected from (a2-3-9) and (a2-3-10) is preferably used.

In the resin component (A), as the structural unit (a2), one type may be used alone, or two or more types may be used in combination.
The proportion of the structural unit (a2) in the resin component (A) is preferably 5 to 60 mol%, more preferably 15 to 50 mol%, based on the total of all structural units constituting the resin component (A). 25-50 mol% is more preferable. By setting it to the lower limit value or more, the effect of containing the structural unit (a2) can be sufficiently obtained, and by setting the upper limit value or less, it is possible to balance with other structural units.

  In the present invention, the resin component (A) is preferably a copolymer having both of these structural units (a1) and (a2) because the effects of the present invention are excellent.

・ Structural unit (a3)
The resin component (A) is derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group in addition to the structural unit (a1) or in addition to the structural units (a1) and (a2). The structural unit (a3) may be included. By having the structural unit (a3), the hydrophilicity of the component (A) is increased, the affinity with the developer is increased, the alkali solubility in the exposed area is improved, and the resolution is improved.
Examples of the polar group include a hydroxyl group, a cyano group, a carboxy group, and a hydroxyalkyl group in which a part of hydrogen atoms of an alkyl group is substituted with a fluorine atom. A hydroxyl group is particularly preferable.
Examples of the aliphatic hydrocarbon group include a linear or branched hydrocarbon group having 1 to 10 carbon atoms (preferably an alkylene group) and a polycyclic aliphatic hydrocarbon group (polycyclic group). . As the polycyclic group, for example, a resin for a resist composition for ArF excimer laser can be appropriately selected from among many proposed ones.
Among them, it contains an aliphatic polycyclic group containing a hydroxyalkyl group in which a part of hydrogen atoms of a hydroxyl group, a cyano group, a carboxy group, or an alkyl group is substituted with a fluorine atom, and is derived from an acrylate ester. A structural unit is more preferable. Examples of the polycyclic group include groups in which one or more hydrogen atoms have been removed from bicycloalkane, tricycloalkane, tetracycloalkane, or the like. Specific examples include groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane. Such a polycyclic group can be appropriately selected and used from among many proposed polymers (resin components) for resist compositions for ArF excimer lasers. Among these polycyclic groups, there are groups in which two or more hydrogen atoms have been removed from adamantane, groups in which two or more hydrogen atoms have been removed from norbornane, and groups in which two or more hydrogen atoms have been removed from tetracyclododecane. Industrially preferable.

  The structural unit (a3) is derived from a hydroxyethyl ester of acrylic acid when the hydrocarbon group in the polar group-containing aliphatic hydrocarbon group is a linear or branched hydrocarbon group having 1 to 10 carbon atoms. When the hydrocarbon group is a polycyclic group, a structural unit represented by the following formula (a3-1), a structural unit represented by (a3-2), (a3-3) The structural unit represented by is mentioned as a preferable thing.

(Wherein R is the same as above, j is an integer of 1 to 3, k is an integer of 1 to 3, t 'is an integer of 1 to 3, and l is an integer of 1 to 5) And s is an integer of 1 to 3.)

  In formula (a3-1), j is preferably 1 or 2, and more preferably 1. When j is 2, it is preferable that the hydroxyl group is bonded to the 3rd and 5th positions of the adamantyl group. When j is 1, it is preferable that the hydroxyl group is bonded to the 3-position of the adamantyl group.

  In formula (a3-2), k is preferably 1. The cyano group is preferably bonded to the 5th or 6th position of the norbornyl group.

  In formula (a3-3), t ′ is preferably 1. l is preferably 1. s is preferably 1. These preferably have a 2-norbornyl group or a 3-norbornyl group bonded to the terminal of the carboxy group of acrylic acid. The fluorinated alkyl alcohol is preferably bonded to the 5th or 6th position of the norbornyl group.

As the structural unit (a3), one type may be used alone, or two or more types may be used in combination.
When the resin component (A) has the structural unit (a3), the proportion of the structural unit (a3) in the resin component (A) is 5 to 50 mol with respect to all the structural units constituting the resin component (A). %, More preferably 15 to 45 mol%, and most preferably 15 to 35 mol%.

・ Structural unit (a4)
The resin component (A) may contain other structural units (a4) other than the structural units (a1) to (a3) as long as the effects of the present invention are not impaired.
The structural unit (a4) is not particularly limited as long as it is another structural unit not classified into the structural units (a1) to (a3) described above, and is for ArF excimer laser, for KrF excimer laser (preferably ArF excimer laser). A number of conventionally known resins can be used for resist resins such as
As the structural unit (a4), for example, a structural unit containing an acid non-dissociable aliphatic polycyclic group and derived from an acrylate ester is preferable. Examples of the polycyclic group include those exemplified in the case of the structural unit (a1), and for ArF excimer laser and KrF excimer laser (preferably for ArF excimer laser). A number of hitherto known materials can be used as the resin component of the resist composition.
In particular, at least one selected from a tricyclodecanyl group, an adamantyl group, a tetracyclododecanyl group, an isobornyl group, and a norbornyl group is preferable in terms of industrial availability. These polycyclic groups may be substituted with a linear or branched alkyl group having 1 to 5 carbon atoms.
Specific examples of the structural unit (a4) include those represented by the following general formulas (a4-1) to (a4-5).

(In the formula, R is as defined above.)

  Such structural unit (a4) is not an essential component of the resin component (A), but when it is contained in the resin component (A), it is based on the total of all structural units constituting the resin component (A). The structural unit (a4) is contained in an amount of 1 to 30 mol%, preferably 10 to 20 mol%.

  The resin component (A) can be obtained by polymerizing a monomer for deriving each structural unit by a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN). .

-A structural unit (M1) having a specific terminal structure
The resin component (A) preferably has a hydroxyl group bonded to a carbon atom at the polymer terminal, and the α-position carbon atom of the hydroxyl group has a terminal structure having at least one electron-withdrawing group.
Examples of the electron withdrawing group include a halogen atom and a halogenated alkyl group.
Examples of the halogen atom include a fluorine atom and a chlorine atom, and a fluorine atom is preferable.
In the halogenated alkyl group, the halogen is the same as the halogen atom. The alkyl group is desirably a lower alkyl group having, for example, about 1 to 3 carbon atoms, preferably a methyl group or an ethyl group, and most preferably a methyl group. Specific examples include a trifluoromethyl group, a difluoromethyl group, a monofluoromethyl group, a perfluoroethyl group, and the like, and a trifluoromethyl group is particularly preferable.
The number of electron-withdrawing groups is 1 or 2, preferably 2.

Has a hydroxyl group bonded to the carbon atom, the carbon atom of the α-position of the hydroxyl group, and has at least one electron-withdrawing group, more specifically and preferably, have a -CR 1 ^R 2 ^OH groups R ¹ and R ² are each independently an alkyl group, a halogen atom, or a halogenated alkyl group, and at least one of them is represented as an electron-withdrawing group selected from a halogen atom or a halogenated alkyl group. be able to.
The halogen atom or halogenated alkyl group here is the same as described above, and examples of the alkyl group include lower alkyl groups such as a methyl group, an ethyl group, and a propyl group. And as described above, the electron-withdrawing group is preferably a fluorine atom or a fluorinated alkyl group, and particularly when R ¹ and R ² are both fluorinated alkyl groups, particularly a trifluoromethyl group, Moreover, it is excellent in the effect which makes LER (line edge roughness: the uneven unevenness | corrugation of a line side wall) small, and preferable.

In the resin component (A), the proportion of the structural unit (M1) having a —CR ¹ R ² OH group bonded to the polymer terminal (hereinafter, the group may be referred to as “terminal structure”) is the resin component ( It is preferable that it is 1 mol% or more (preferably 2 mol% or more) with respect to a total of 100 mol% of structural units other than the said structural unit (M1) among all the structural units which comprise A). The total of structural units other than the structural unit (M1) is the main component of a structural unit or resin derived from a known polymerization initiator such as azobisisobutyronitrile (AIBN) used in radical polymerization. Contains units derived from monomers.
The upper limit value is not particularly limited, but is practically set to, for example, 5 mol% or less due to the production method and the like. Moreover, by setting it as 1 mol% or more, it is excellent in the reduction effect of the image development defect by having introduce | transduced the terminal structure, and the improvement effect of LER. Below this, these effects tend to be inferior. Needless to say, the number of moles of the structural unit (M1) is equal to the number of moles of the terminal structure and the number of moles of the hydroxyl group.

The terminal structure can be introduced into the polymer terminal by adding a chain transfer agent having a —CR ¹ R ² OH group, for example, when a polymer is produced by radical polymerization using a monomer and a polymerization initiator. In this case, the structural unit (M1) having the terminal structure is a structural unit (M1) derived from this chain transfer agent.
The chain transfer agent is represented by, for example, the general formula “X—R′—CR ¹ R ² OH”.
In the formula, X is a hydroxyl group or a thiol group, and in the chain transfer agent, a hydrogen atom of the hydroxyl group or the thiol group is eliminated and bonded to the polymer terminal. Therefore, in this case, the structural unit (M1) is a unit obtained by removing a hydrogen atom from the hydroxyl group or thiol group of X in “X—R′—CR ¹ R ² OH”. From the viewpoint of reactivity, X is preferably a thiol group.
R ′ in “X—R′—CR ¹ R ² OH” is a divalent aliphatic hydrocarbon group (which may be linear, branched or cyclic) or a divalent aromatic hydrocarbon group. Of these, linear or branched aliphatic hydrocarbon groups are preferred.
Examples of the alicyclic group include a cyclohexylene group. Examples of the aromatic hydrocarbon group include a p-phenylene group.
Examples of the linear or branched aliphatic hydrocarbon group include a methylene group, an ethylene group, an n-propylene group, and an isopropylene group, and an ethylene group and an n-propylene group are preferable.
A general formula of a preferred chain transfer agent is represented by SH— (CH ₂ ) _m —C (CF ₃ ) ₂ —OH (m is an integer of 2 to 4). Thus, the preferred structural units (M1) is represented by _{-S- (CH 2) m -C (} CF 3) 2 -OH.

The ratio of the terminal structure (the ratio of the structural unit (M1)) is, for example, adjusting the amount of charged monomers and the amount of the chain transfer agent, or adjusting the timing at which the chain transfer agent is added. It can be changed by adjusting the mass average molecular weight.
In the resin for resist composition after synthesis, the number of moles of the terminal structure (number of moles of the structural unit (M1)) can be measured by NMR (nuclear magnetic resonance spectrum) such as proton-NMR and carbon NMR. it can.

The mass average molecular weight (Mw) of the resin component (A) (polystyrene conversion standard by gel permeation chromatography) is not particularly limited, but is preferably 2000 to 50000, more preferably 3000 to 30000, and more preferably 5000 to 20000. Most preferred. When it is smaller than the upper limit of this range, it has sufficient solubility in a resist solvent to be used as a resist, and the dry etching resistance and resist pattern cross-sectional shape are larger than the lower limit of this range.
Further, the dispersity (Mw / Mn) is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and most preferably 1.2 to 2.5.

<Acid generator component (B)>
In the present invention, an onium salt acid generator (B1) having a cation moiety represented by the general formula (b-1) and an oxime sulfonate system having a structure represented by the following general formula (b-2) The acid generator (B2) is used as an essential component.
In · (B1) component above general formula ^{(b-1), R 1} " is an alkyl group, an alkoxy group, a halogen atom or a hydroxyl group, n represents the .n represents an integer of 0 or 1 to 3 2, or 3, And the plurality of R ¹ ″ may be the same as or different from each other.
The alkyl group as R ¹ ″ is preferably an alkyl group having 1 to 5 carbon atoms, and most preferably a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group.
The alkoxy group as R ¹ ″ is preferably an alkoxy group having 1 to 5 carbon atoms, and most preferably a methoxy group or an ethoxy group.
The halogen atom as R ¹ ″ is preferably a fluorine atom.
The n is preferably 0 or 1, more preferably 0.

In the general formula (b-1), R ² ″ and R ³ ″ each independently represents an aryl group or an alkyl group which may have a substituent.
The aryl group as R ² ″ and R ³ ″ is not particularly limited, and is, for example, an aryl group having 6 to 20 carbon atoms. It may or may not be substituted with a group, a halogen atom, a hydroxyl group or the like. The aryl group is preferably an aryl group having 6 to 10 carbon atoms because it can be synthesized at a low cost. Specific examples include a phenyl group and a naphthyl group.
When the hydrogen atom of the aryl group is substituted, the alkyl group as the substituent is the same as the alkyl group as R ¹ ″.
The alkoxy group as the substituent when the hydrogen atom of the aryl group is substituted is the same as the alkoxy group as the R ¹ ″.
When the hydrogen atom of the aryl group is substituted, the halogen atom as the substituent is the same as the halogen atom as R ¹ ″.
The alkyl group as R ² ″ and R ³ ″ is not particularly limited, and examples thereof include linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms. It is preferable that it is C1-C5 from the point which is excellent in resolution. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a nonyl group, and a decanyl group. A methyl group is preferable because it is excellent in resolution and can be synthesized at low cost.
Most preferably, R ² ″ and R ³ ″ are both phenyl groups.

The anion moiety in the component (B1) is not particularly limited, and those known as the anion moiety of the onium salt acid generator can be appropriately used.
For example, an anion moiety represented by the general formula “R ⁴ ” SO ₃ ^— (R ⁴ ”represents a linear, branched or cyclic alkyl group or fluorinated alkyl group)”, the following general formula (b-3 ), An anion moiety represented by the following general formula (b-4), and the like can be used.

[Wherein X ″ represents an alkylene group having 2 to 6 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom; Y ″ and Z ″ each independently represent at least one hydrogen atom as a fluorine atom; Represents an alkyl group having 1 to 10 carbon atoms and substituted with

In the general formula “R ⁴ ″ SO ₃ ⁻ ”, R ⁴ ″ represents a linear, branched or cyclic alkyl group or a fluorinated alkyl group.
The alkyl group as R ⁴ ″ preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms.
The cyclic alkyl group as R ⁴ ″ is the cyclic group shown as R ² ″ or R ³ ″ and preferably has 4 to 15 carbon atoms and preferably 4 to 10 carbon atoms. More preferably, it is most preferable that it is C6-C10.
The fluorinated alkyl group as R ⁴ ″ preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms. The fluorination rate of the fluorinated alkyl group (ratio of fluorine atoms in the alkyl group) is preferably 10 to 100%, more preferably 50 to 100%, and in particular, all hydrogen atoms are substituted with fluorine atoms. It is preferable because the strength of the acid is increased.
R ⁴ ″ is most preferably a linear or cyclic alkyl group or a fluorinated alkyl group.

In the general formula (b-3), X ″ is a linear or branched alkylene group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkylene group has 2 to 6 carbon atoms. , Preferably 3 to 5 carbon atoms, most preferably 3 carbon atoms.
In the general formula (b-4), Y ″ and Z ″ are each independently a linear or branched alkyl group in which at least one hydrogen atom is substituted with a fluorine atom, and the carbon of the alkyl group The number is 1 to 10, preferably 1 to 7 carbon atoms, more preferably 1 to 3 carbon atoms.
The carbon number of the alkylene group of X ″ or the carbon number of the alkyl group of Y ″ and Z ″ is preferably as small as possible because the solubility in the resist solvent is good within the above carbon number range.
In addition, in the alkylene group of X ″ or the alkyl group of Y ″ and Z ″, the greater the number of hydrogen atoms substituted with fluorine atoms, the stronger the acid strength, which is preferable. The proportion of fluorine atoms, that is, the fluorination rate is preferably 70 to 100%, more preferably 90 to 100%, and most preferably a perfluoroalkylene group or perfluoro group in which all hydrogen atoms are substituted with fluorine atoms. It is an alkyl group.

As the anion moiety of the component (B1), an anion moiety represented by the general formula “R ⁴ ″ SO ₃ ⁻ ” is preferable, and R ⁴ ″ is more preferably a fluorinated alkyl group.

Preferred specific examples of the component (B1) are listed below.

  Among these, it is preferable to use at least one selected from the chemical formulas (b1-01) to (b1-06).

-Component (B2) In the general formula (b-2), R ²¹ 'represents an organic group, and R ²² ' represents a monovalent organic group or a cyano group.
In the present invention, the organic group is a group containing a carbon atom, and has an atom other than a carbon atom (for example, a hydrogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom (fluorine atom, chlorine atom, etc.)). It may be.
The organic group as R ²¹ ′ is preferably a linear, branched or cyclic alkyl group or aryl group. These alkyl groups and aryl groups may have a substituent. There is no restriction | limiting in particular as this substituent, For example, a fluorine atom, a C1-C6 linear, branched or cyclic alkyl group etc. are mentioned. Here, “having a substituent” means that part or all of the hydrogen atoms of the alkyl group or aryl group are substituted with a substituent.
As an alkyl group, C1-C20 is preferable, C1-C10 is more preferable, C1-C8 is more preferable, C1-C6 is especially preferable, and C1-C4 is the most preferable. As the alkyl group, a partially or completely halogenated alkyl group (hereinafter sometimes referred to as a halogenated alkyl group) is particularly preferable. The partially halogenated alkyl group means an alkyl group in which a part of hydrogen atoms is substituted with a halogen atom, and the fully halogenated alkyl group means that all of the hydrogen atoms are halogen atoms. Means an alkyl group substituted with Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is particularly preferable. That is, the halogenated alkyl group is preferably a fluorinated alkyl group.
The aryl group preferably has 4 to 20 carbon atoms, more preferably 4 to 10 carbon atoms, and most preferably 6 to 10 carbon atoms. As the aryl group, a partially or completely halogenated aryl group is particularly preferable. The partially halogenated aryl group means an aryl group in which a part of hydrogen atoms is substituted with a halogen atom, and the fully halogenated aryl group means that all of the hydrogen atoms are halogen atoms. Means an aryl group substituted with.
R ²¹ ′ is particularly preferably a C 1-4 alkyl group having no substituent or a C 1-4 fluorinated alkyl group.

The organic group as R ²² ′ is preferably a linear, branched or cyclic alkyl group, aryl group or cyano group. As the alkyl group and aryl group for R ²² ′, the same alkyl groups and aryl groups as those described above for R ²¹ ′ can be used.
R ²² ′ is particularly preferably a cyano group, an alkyl group having 1 to 8 carbon atoms having no substituent, or a fluorinated alkyl group having 1 to 8 carbon atoms.

  More preferable examples of the component (B2) include compounds represented by the following general formula (B-2) or (B-3).

[In Formula (B-2), R ³¹ represents a cyano group, an alkyl group having no substituent, or a halogenated alkyl group. R ³² is an aryl group. R ³³ is an alkyl group having no substituent or a halogenated alkyl group. ]

[In the formula (B-3), R ³⁴ represents a cyano group, an alkyl group having no substituent, or a halogenated alkyl group. R ³⁵ is a divalent or trivalent aromatic hydrocarbon group. R ³⁶ is an alkyl group having no substituent or a halogenated alkyl group. p is 2 or 3. ]

In the general formula (B-2), the alkyl group or halogenated alkyl group having no substituent for R ³¹ preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and more preferably carbon atoms. Numbers 1 to 6 are most preferable.
R ³¹ is preferably a halogenated alkyl group, more preferably a fluorinated alkyl group.
The fluorinated alkyl group for R ³¹ is preferably fluorinated by 50% or more of the hydrogen atom of the alkyl group, more preferably 70% or more, and even more preferably 90% or more.

As the aryl group of R ³² , one hydrogen atom is removed from an aromatic hydrocarbon ring such as a phenyl group, a biphenyl group, a fluorenyl group, a naphthyl group, an anthracyl group, a phenanthryl group, or the like. And a heteroaryl group in which a part of carbon atoms constituting the ring of these groups is substituted with a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. Among these, a fluorenyl group is preferable.
The aryl group represented by R ³² may have a substituent such as an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group, or an alkoxy group. The alkyl group or halogenated alkyl group in the substituent preferably has 1 to 8 carbon atoms, and more preferably 1 to 4 carbon atoms. The halogenated alkyl group is preferably a fluorinated alkyl group.

The alkyl group or halogenated alkyl group having no substituent for R ³³ preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 6 carbon atoms.
R ³³ is preferably a halogenated alkyl group, more preferably a fluorinated alkyl group, and most preferably a partially fluorinated alkyl group.
The fluorinated alkyl group for R ³³ preferably has 50% or more of the hydrogen atom of the alkyl group, more preferably 70% or more, and even more preferably 90% or more. This is preferable because the strength of the acid is increased. Most preferably, it is a fully fluorinated alkyl group in which a hydrogen atom is 100% fluorine-substituted.

In the general formula (B-3), the alkyl group or halogenated alkyl group having no substituent for R ³⁴ is the same as the alkyl group or halogenated alkyl group having no substituent for R ^31. Is mentioned.
Examples of the divalent or trivalent aromatic hydrocarbon group for R ³⁵ include groups obtained by further removing one or two hydrogen atoms from the aryl group for R ³² .
Examples of the alkyl group or halogenated alkyl group having no substituent for R ³⁶ include the same alkyl groups or halogenated alkyl groups as those having no substituent for R ³³ .
p is preferably 2.

Specific examples of the component (B2) include α- (p-toluenesulfonyloxyimino) -benzyl cyanide, α- (p-chlorobenzenesulfonyloxyimino) -benzyl cyanide, α- (4-nitrobenzenesulfonyloxyimino) -Benzyl cyanide, α- (4-nitro-2-trifluoromethylbenzenesulfonyloxyimino) -benzyl cyanide, α- (benzenesulfonyloxyimino) -4-chlorobenzyl cyanide, α- (benzenesulfonyloxyimino ) -2,4-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -2,6-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -4-methoxybenzyl cyanide, α- (2- Chlorobenzenesulfonyloxyimino) -4-methoxyben Rucyanide, α- (benzenesulfonyloxyimino) -thien-2-ylacetonitrile, α- (4-dodecylbenzenesulfonyloxyimino) -benzylcyanide, α-[(p-toluenesulfonyloxyimino) -4-methoxyphenyl ] Acetonitrile, α-[(dodecylbenzenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α- (tosyloxyimino) -4-thienyl cyanide, α- (methylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (Methylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -1-cycloheptenylacetonitrile, α- (methylsulfonyloxyimino) -1-cyclooctenylacetonitrile α- (trifluoromethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -cyclohexylacetonitrile, α- (ethylsulfonyloxyimino) -ethylacetonitrile, α- (propylsulfonyloxyimino ) -Propylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclopentylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclohexylacetonitrile, α- (cyclohexylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (ethylsulfonyloxy) Imino) -1-cyclopentenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclopentenylacetonite Ril, α- (n-butylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (ethylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α -(N-butylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoromethylsulfonyl) Oxyimino) -phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p-methoxyphenyla Tonitoriru, alpha-(propylsulfonyl oxyimino)-p-methylphenyl acetonitrile, alpha-like (methylsulfonyloxyimino)-p-bromophenyl acetonitrile.
Moreover, the compound represented by the following chemical formula is mentioned.

  Moreover, the example of a preferable compound is shown below among the compounds represented by the said general formula (B-2) or (B-3).

  Among the above exemplified compounds, the following three compounds are preferable.

The mass ratio (B1) :( B2) of the content of the component (B1) and the component (B2) in the positive resist composition of the present invention is preferably 10:90 to 90:10, and 25:75 to 75: 25 is more preferable, and 40:60 to 60:40 is more preferable. When the mass ratio of the component (B1) and the component (B2) is within the above range, the characteristics of the pattern shape, EL margin, and dimensional fidelity can be improved.
The content of the component (B1) in the positive resist composition of the present invention is preferably 1 to 10 parts by mass, more preferably 3 to 7 parts by mass with respect to 100 parts by mass of the component (A), and 5 to 7 Part by mass is more preferable. A sufficient effect can be obtained by setting the content of the component (B1) to be equal to or higher than the lower limit of the above range. On the other hand, in order to suppress the generation of scum and obtain a good shape, it is preferable to set the upper limit of the above range.
The content of the component (B2) in the positive resist composition of the present invention is preferably 1 to 10 parts by weight, more preferably 2 to 8 parts by weight, and 3 to 7 parts per 100 parts by weight of the component (A). Part by mass is more preferable. A sufficient effect can be obtained by setting the content of the component (B2) to be equal to or higher than the lower limit of the above range. In order to obtain good coating properties, it is preferable to set the upper limit value within the above range.

In the present invention, as the component (B), one or more acid generator components other than the component (B1) and the component (B2) may be contained. The other acid generator component is not particularly limited, and those that have been proposed as acid generators for chemically amplified resists can be used. For example, onium salt acid generators such as sulfonium salts and iodonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, poly (bis), which are not included in the components (B1) and (B2). There are various known diazomethane acid generators such as sulfonyl) diazomethanes, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators and the like.
2-20 mass parts is preferable with respect to 100 mass parts of (A) component, as for the total content of (B) component in the positive resist composition of this invention, 5-15 mass parts is more preferable, and 8-14 Most preferably, it is part by mass. By setting it within the above range, pattern formation is sufficiently performed and good characteristics are obtained. Moreover, since a uniform solution is obtained and storage stability becomes favorable, it is preferable.
The proportion of the total of the component (B) and the component (B1) and the component (B2) is preferably 50% by mass or more, more preferably 75% by mass or more, and most preferably 100% by mass.

<Nitrogen-containing organic compound (D)>
The positive resist composition of the present invention can further contain a nitrogen-containing organic compound (D) as an optional component in order to improve the resist pattern shape, the stability over time, and the like.
Since a wide variety of components (D) have been proposed, any known one may be used, but aliphatic amines, particularly secondary aliphatic amines and tertiary aliphatic amines are preferred. .
Examples of the aliphatic amine include amines (alkyl amines or alkyl alcohol amines) in which at least one hydrogen atom of ammonia NH ₃ is substituted with an alkyl group or hydroxyalkyl group having 12 or less carbon atoms. Specific examples thereof include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine; diethylamine, di-n-propylamine, di-n-heptylamine, Dialkylamines such as di-n-octylamine and dicyclohexylamine; trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine, tri-n-heptyl Trialkylamines such as amine, tri-n-octylamine, tri-n-nonylamine, tri-n-decanylamine, tri-n-dodecylamine; diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, di-n -Ok Noruamin, alkyl alcohol amines such as tri -n- octanol amine. Among these, alkyl alcohol amines and trialkyl amines are preferable, and alkyl alcohol amines are most preferable. Of the alkyl alcohol amines, triethanolamine and triisopropanolamine are most preferred.
These may be used alone or in combination of two or more.
(D) component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

<(E) component>
In addition, the positive resist composition of the present invention includes an organic carboxylic acid as an optional component for the purpose of preventing sensitivity deterioration due to the blending of the component (D), and improving the resist pattern shape, retention stability, and the like. An acid or phosphorus oxo acid or a derivative thereof (E) (referred to herein as component (E)) can be contained. In addition, (D) component and (E) component can also be used together, and any 1 type can also be used.
As the organic carboxylic acid, for example, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.
Phosphorus oxoacids or derivatives thereof include phosphoric acid, phosphoric acid di-n-butyl ester, phosphoric acid diphenyl ester and other phosphoric acid or derivatives thereof such as phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid- Like phosphonic acids such as di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester and derivatives thereof, phosphinic acids such as phosphinic acid, phenylphosphinic acid and their esters Among these, phosphonic acid is particularly preferable.
(E) A component is used in the ratio of 0.01-5.0 mass parts per 100 mass parts of (A) component.

<Organic solvent>
The positive resist composition of the present invention can be produced by dissolving the material in an organic solvent.
Any organic solvent may be used as long as it can dissolve each component to be used to form a uniform solution, and one or two kinds of conventionally known solvents for chemically amplified resists can be used. These can be appropriately selected and used.
For example, lactones such as γ-butyrolactone, ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone, ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate Polyhydric alcohols such as dipropylene glycol or dipropylene glycol monoacetate monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether and derivatives thereof, cyclic ethers such as dioxane, Methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, pyruvate Le, methyl methoxypropionate, esters such as ethyl ethoxypropionate can be exemplified.

These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
A mixed solvent obtained by mixing propylene glycol monomethyl ether acetate (PGMEA) and a polar solvent is preferable. The blending ratio (mass ratio) may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. It is preferable to be within the range.
More specifically, when EL is blended as a polar solvent, the mass ratio of PGMEA: EL is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2.
In addition, as the organic solvent, a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone is also preferable. In this case, the mixing ratio of the former and the latter is preferably 70:30 to 95: 5.
Although the amount of the organic solvent used is not particularly limited, it is a concentration that can be applied to a substrate and the like, and is appropriately set according to the coating film thickness. In general, the solid content concentration of the resist composition is 2 to 20 mass. %, Preferably 5-15% by mass.

Other optional components In the positive resist composition of the present invention, there are further miscible additives as desired, for example, additional resins for improving the performance of the resist film, and surfactants for improving the coating properties. Further, a dissolution inhibitor, a plasticizer, a stabilizer, a colorant, an antihalation agent, a dye, and the like can be appropriately added and contained.

<Resist pattern formation method>
The resist pattern forming method of the present invention can be performed, for example, as follows.
That is, first, the positive resist composition is coated on a substrate such as a silicon wafer with a spinner and prebaked for 40 to 120 seconds, preferably 60 to 90 seconds under a temperature condition of 80 to 150 ° C. A film is formed.
Next, the resist film is selectively exposed with ArF excimer laser light through a desired mask pattern by, for example, an ArF exposure apparatus, and then subjected to PEB (post-exposure heating) at a temperature of 80 to 150 ° C. It is applied for 40 to 120 seconds, preferably 60 to 90 seconds.
Next, this is developed using an alkali developer, for example, an aqueous solution of 0.1 to 10% by mass of tetramethylammonium hydroxide. You may post-bake after image development processing as needed.
In this way, a resist pattern faithful to the mask pattern can be obtained.
An organic or inorganic antireflection film can be provided between the substrate and the coating layer of the resist composition.

The wavelength used for the exposure is not particularly limited, and ArF excimer laser, KrF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), EB (electron beam), X-ray, soft X-ray, etc. Can be done using radiation. In particular, the positive resist composition according to the present invention is particularly effective for an ArF excimer laser.

According to the positive resist composition of the present invention, EL margin and dimensional fidelity can be improved. Further, the resist pattern is less likely to fall down, and the line edge roughness (LER) at which the surface of the side wall of the line pattern becomes non-uniform is also improved.
The reason for this is not clear, but the component (B1) has a substituent derived from naphthalene in the cation portion, and therefore has a light absorption in the exposure wavelength band as compared with an acid generator component composed of a triphenylsulfonium-based onium salt. If the exposure amount is the same, the acid generation amount per mole of the acid generator component is considered to be suppressed. In particular, it is presumed that absorption of light is effectively suppressed in the wavelength band of ArF excimer laser (in particular, transparency is improved with respect to ArF excimer laser light). In the present invention, when the component (B1) and the component (B2) that is an oxime sulfonate acid generator are used in combination, the above-described plurality of good characteristics can be achieved at the same time due to the synergistic effect of the two. Conceivable.

(Synthesis Example 1)
0.1 mol of a mixture of 2-ethyl-2-adamantyl methacrylate, norbornane lactone methacrylate, and 3-hydroxy-1-adamantyl methacrylate was dissolved in 150 ml of THF (tetrahydrofuran), and AIBN (4 mol% based on 100 mol% of the monomer) was dissolved. ) To initiate radical polymerization at 70 ° C., and as a chain transfer agent for polymerization, the following chemical formula

The polymerization reaction was carried out by adding 3 mol% of the compound represented by the formula (1) to the total of 100 mol% of the charged monomer and AIBN. After completion of the polymerization reaction, the reaction solution was poured into 2000 ml of n-heptane, stirred at 25 ° C. for 30 minutes, and the precipitated solid was collected by filtration. This solid was dissolved again in 200 ml of THF and then poured into 2000 ml of n-heptane, stirred at 25 ° C. for 30 minutes, and the precipitated solid was collected by filtration and dried to obtain a resin A represented by the following chemical formula. In the following chemical formula, n / m / l = 40/40/20 (molar ratio). Resin A had a weight average molecular weight of 6000 and a dispersity (mass average molecular weight / number average molecular weight) of 1.5.

Example 1
To 100 parts by mass of the resin A obtained in Synthesis Example 1, the component (B) is represented by 6.0 parts by mass of the compound represented by the chemical formula (b1-01) and the chemical formula (b2-01). Compound 6.0 parts by weight, 0.45 parts by weight of triethanolamine as component (D), 25 parts by weight of γ-butyrolactone (GBL), and propylene glycol monomethyl ether acetate (PM) and methyl amyl ketone (MAK) A positive resist composition having a solid content concentration of about 9% by mass was prepared by dissolving in a mixture (mass ratio 8: 2).

Next, an organic antireflection film composition “AR-46” (trade name, manufactured by Shipley Co., Ltd.) was applied onto an 8-inch silicon wafer using a spinner, and baked on a hot plate at 225 ° C. for 60 seconds to dry. As a result, an organic antireflection film having a film thickness of 29 nm was formed. Then, the positive resist composition is applied onto the antireflection film using a spinner, prebaked (PAB) at 105 ° C. for 60 seconds on a hot plate, and dried to form a resist layer having a thickness of 200 nm. did.
Next, an ArF excimer laser (193 nm) is selectively passed through a 6% halftone reticle with an ArF exposure apparatus NSR-S306 (manufactured by Nikon; NA (numerical aperture) = 0.78, 2/3 ring zone). Irradiated.
Then, PEB treatment was performed at 110 ° C. for 60 seconds, and further developed at 23 ° C. with a 2.38 mass% tetramethylammonium hydroxide aqueous solution for 60 seconds. Thereafter, it was washed with water for 20 seconds and then shaken and dried. Furthermore, it was heated and dried at 100 ° C. for 60 seconds to form a line and space pattern (hereinafter referred to as L / S pattern).

The following characteristics were evaluated.
<Sensitivity>
The optimum exposure amount at which a 85 nm line and space (pitch is 180 nm) was formed was measured in units of mJ / cm ² (energy amount) as sensitivity (EOP). The results are shown in Table 1 below.
<EL margin>
The EL margin (unit: nm / mJ) represented by the change amount of the pattern size per 1 mJ of exposure dose was measured in the range of the exposure dose where the L / S pattern was obtained in the pattern size range of 85 nm ± 10%. The results are shown in Table 1 below.
<Mask linearity>
L / S patterns were formed using 110 nm and 130 nm line and space mask patterns, and the MEF (mask error factor) value was determined from the following equation.
MEF = | CD ₁₃₀ −CD ₁₁₀ | / | MD ₁₃₀ −MD ₁₁₀ |
In the above formula, CD ₁₃₀ and CD ₁₁₀ are resist pattern widths (nm) of L & S patterns formed using mask patterns of 130 nm and 110 nm, respectively, and MD ₁₃₀ and MD ₁₁₀ are mask pattern widths (nm), respectively. Yes, MD ₁₃₀ = 130 and MD ₁₁₀ = 110. This is a parameter indicating how faithfully a mask pattern having a different line width can be reproduced with the same exposure amount. The closer this MEF value is to 1, the better the mask linearity is. The results are shown in Table 1 below.
<Pattern collapse>
The exposure time in selective exposure was increased, and when the pattern width gradually narrowed along with that, the location where the pattern collapsed was observed by SEM. The results are shown in Table 1 below.
<LER>
For the 85 nm L / S pattern (pitch is 180 nm) obtained in the EOP, 3σ, which is a measure indicating LER, was obtained as an evaluation of line edge roughness (LER) at which the surface of the side wall of the line pattern becomes non-uniform. 3σ is a side length SEM (manufactured by Hitachi, Ltd., trade name “S-9220”). The width of the resist pattern of the sample is measured at 32 locations, and the standard deviation (σ) calculated from the result is 3 times the value (3σ ). This 3σ means that the smaller the value, the smaller the roughness and the uniform width resist pattern was obtained. The results are shown in Table 1 below.

(Comparative Example 1)
The same procedure as in Example 1 was conducted except that the component (B) was changed to 6.0 parts by mass of the compound represented by the chemical formula (b2-01) and 2.0 parts by mass of triphenylsulfonium nonafluorobutanesulfonate. After preparing a positive resist composition, an L / S pattern was formed in the same manner as in Example 1 and the same evaluation was performed. The results are shown in Table 1 below.

Claims (5)

A positive resist composition comprising a resin component (A) whose alkali solubility is increased by the action of an acid, and an acid generator component (B) that generates an acid upon exposure,
The component (B) is represented by the following general formula (b-1)

[Wherein, R ¹ ″ represents an alkyl group, an alkoxy group, a halogen atom or a hydroxyl group, and R ² ″ and R ³ ″ each independently represents an aryl group or an alkyl group which may have a substituent. , N represents 0 or an integer of 1 to 3, except that R ² ″ and R ³ ″ are bonded to each other to form a ring.
An onium salt-based acid generator (B1) having a cation moiety represented by formula (b-2):

[Wherein R ²¹ ′ represents an organic group, and R ²² ′ represents a monovalent organic group or a cyano group. ]
A positive resist composition comprising an oxime sulfonate acid generator (B2) having a structure represented by:   2. The positive resist composition according to claim 1, wherein a mass ratio (B1) :( B2) between the content of the component (B1) and the content of the component (B2) is 10:90 to 90:10.   3. The positive electrode according to claim 1, wherein the component (A) contains a resin having a hydroxyl group bonded to a carbon atom at a polymer terminal, and the α-position carbon atom of the hydroxyl group has at least one electron withdrawing group. Type resist composition.   The positive resist composition as described in any one of Claims 1-3 containing a nitrogen-containing organic compound (D). A step of forming a resist film on a substrate using the positive resist composition according to any one of claims 1 to 4, a step of exposing the resist film, and developing the resist film to form a resist pattern A resist pattern forming method including a process.