JP2006106496A - Resist composition and method for forming resist pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resist composition and a method for forming a resist pattern to improve the cross-sectional squareness property of a resist pattern. <P>SOLUTION: The resist composition contains a resin component (A) whose alkali solubility is changed by the effect of an acid, and an acid generator component (B), and further contains a surfactant (D1) having an amide bond. The method for forming a resist pattern is carried out by using the composition. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

In recent years, in the manufacture of semiconductor elements and liquid crystal display elements, pattern miniaturization has been rapidly progressing 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 have been used, but at present, mass production of semiconductor elements using a KrF excimer laser or an ArF excimer laser has started. Further, F ₂ excimer laser having a shorter wavelength than these excimer lasers, electron beams, also consider such extreme ultraviolet radiation and X-rays have been made.
In addition, as one of the resist materials that satisfy the high resolution conditions that can reproduce patterns with fine dimensions, it contains a base resin whose alkali solubility changes due to the action of acid and an acid generator that generates acid upon exposure. A chemically amplified resist composition is known. The chemically amplified resist composition includes a negative type containing an alkali-soluble resin, an acid generator and a crosslinking agent, and a positive type containing a resin whose acid solubility is increased by the action of an acid and an acid generator.

For example, as a resist base resin used in ArF excimer laser lithography or the like, a resin (acrylic resin) having a structural unit derived from (meth) acrylic acid is mainly used because of excellent transparency near 193 nm. (Patent Document 1 etc.).
JP 2003-167347 A

However, in the conventional resist composition, a phenomenon that the tip portion of the resist pattern becomes round may occur in the cross section of the resist pattern.
If the rectangular shape of the cross-sectional shape is not sufficient in this way, it becomes a serious problem particularly when fine processing is required.

  This invention is made | formed in view of the said situation, and it aims at providing the formation method of the resist composition and resist pattern which can improve the rectangularity of the cross-sectional shape of a resist pattern.

In order to solve the above problems, the present invention provides the following means.
1st aspect contains surfactant (D1) which has an amide bond in the resist composition containing the resin component (A) from which alkali solubility changes with the effect | action of an acid, and an acid generator component (B). The resist composition characterized by the above.
In the second aspect, the resist composition of the present invention is applied on a substrate, pre-baked, selectively exposed, then subjected to PEB (post-exposure heating), and alkali-developed to form a resist pattern. This is a resist pattern forming method.

In the present invention, “structural unit” means a monomer unit constituting a polymer.
Further, “(α-lower alkyl) acrylic acid ester” means one or both of α-lower alkyl acrylic acid ester such as methacrylic acid ester and acrylic acid ester. Here, the “α-lower alkyl acrylate ester” means that a hydrogen atom bonded to the α carbon atom of the acrylate ester is substituted with a lower alkyl group. The “structural unit derived from (α-lower alkyl) acrylate ester” means a structural unit formed by cleavage of an ethylenic double bond of (α-lower alkyl) acrylate ester.
In addition, “exposure” is a concept including general radiation irradiation.

  In the present invention, it is possible to provide a resist composition and a method for forming a resist pattern that can improve the rectangularity of the cross-sectional shape of the resist pattern.

[Resist composition]
The resist composition of the present invention contains a surfactant (D1) having an amide bond in a resist composition containing a resin component (A) whose alkali solubility is changed by the action of an acid and an acid generator component (B). It is characterized by doing.

<(A) component>
The component (A) is not particularly limited, and one or two or more types of alkali-soluble resins or resins that can be alkali-soluble that have been proposed as base resins for chemically amplified resists can be used. . In the former case, a so-called negative type resist composition is used, and in the latter case, a so-called positive type resist composition.

  In the case of the negative type, a crosslinking agent is blended in the resist composition together with the alkali-soluble resin and the component (B). When an acid is generated from the component (B) by exposure at the time of resist pattern formation, the acid acts to cause cross-linking between the alkali-soluble resin and the cross-linking agent, thereby changing to alkali-insoluble.

As the alkali-soluble resin, a resin having a unit derived from at least one selected from α- (hydroxyalkyl) acrylic acid or a lower alkyl ester of α- (hydroxyalkyl) acrylic acid is a good resist with little swelling. A pattern can be formed, which is preferable.
In addition, as the crosslinking agent, for example, when an amino crosslinking agent such as glycoluril having a methylol group or an alkoxymethyl group, particularly a butoxymethyl group is used, a good resist pattern with less swelling can be formed. preferable. The blending amount of the crosslinking agent is preferably in the range of 1 to 50 parts by mass with respect to 100 parts by mass of the alkali-soluble resin.

In the case of the positive type, 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 is converted into the acid dissociable dissolution inhibiting group. (A) component becomes alkali-soluble by dissociating.
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.
In the present invention, a positive type is preferred.

The component (A) preferably contains a structural unit derived from an (α-lower alkyl) acrylic acid ester in both positive and negative types.
(Α-Lower alkyl) A hydrogen atom or a lower alkyl group is bonded to the α-position of the acrylate ester. The lower alkyl group is an alkyl group having 1 to 5 carbon atoms, specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, Examples include lower linear or branched alkyl groups such as isopentyl group and neopentyl group. A hydrogen atom or a methyl group is preferably bonded to the α-position in terms of industrial availability.
In the present invention, in the component (A), the structural unit derived from the (α-lower alkyl) acrylic acid ester is preferably 20 mol% or more, more preferably 50 mol% or more, still more preferably 70 mol% or more. The most preferable content is 100 mol% because a suitable resist composition can be obtained.
In general, in the component (A), as the proportion of the structural unit derived from an α-lower alkyl-acrylate ester having a lower alkyl group bonded to the α-position increases, the tip of the resist pattern becomes rounder and rectangular. However, in the present invention, the component (A) containing a structural unit derived from an α-lower alkyl-acrylate ester having a lower alkyl group bonded to the α-position may be used. A rectangular resist pattern is obtained.

Further, in the case of a positive resist composition, the component (A) is a structural unit (a1) derived from an (α-lower alkyl) acrylate ester having an acid dissociable, dissolution inhibiting group, a lactone-containing monocycle or It is preferable to include a polymer compound (A1) having a structural unit (a2) derived from an (α-lower alkyl) acrylate ester having a polycyclic group.
Further, the polymer compound (A1) preferably has a structural unit (a3) derived from an (α-lower alkyl) acrylate ester containing a polar group-containing aliphatic hydrocarbon group.
Moreover, (A) component can also contain resin other than a high molecular compound (A1), and may consist of a high molecular compound (A1), and the ratio of a high molecular compound (A1) in (A) component. Is preferably 50% by mass or more, more preferably 80 to 100% by mass, and most preferably 100% by mass. A high molecular compound (A1) can also be used 1 type or in mixture of 2 or more types.

・ Structural unit (a1)
The structural unit (a1) is a structural unit derived from an (α-lower alkyl) acrylate ester having an acid dissociable, dissolution inhibiting group.

  The acid dissociable, dissolution inhibiting group in the structural unit (a1) has an alkali dissolution inhibiting property that makes the entire polymer compound (A1) insoluble in alkali before dissociation, and the entire polymer compound (A1) is alkalinized after dissociation. As long as it is changed to be soluble, those that have been proposed as acid dissociable, dissolution inhibiting groups for base resins for chemically amplified resists can be used. Generally, it forms a cyclic or chain tertiary alkyl ester with a carboxy group of (meth) acrylic acid, or a cyclic or chain alkoxyalkyl ester with a carboxy group of (meth) acrylic acid Such groups are widely known. “(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 replacing the hydrogen atom of a carboxy group with an alkyl group or a cycloalkyl group, and the carbonyloxy group (—C (O) —O). A structure in which the tertiary carbon atom of the alkyl group or cycloalkyl group is bonded to the terminal oxygen atom of-).
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.
In addition, the cyclic or chain alkoxyalkyl ester forms an ester by replacing the hydrogen atom of the carboxyl 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, the bond is broken between the oxygen atom and the 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.

（式中、Ｒは水素原子または低級アルキル基を示し；Ｘ^１は酸解離性溶解抑制基を示す。）

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

（式中、Ｒは水素原子または低級アルキル基を示し；Ｘ^２は酸解離性溶解抑制基を示し；Ｙ^２は脂肪族環式基を示す。）

(Wherein, R represents a hydrogen atom or a lower alkyl group; X ² represents an acid dissociable, dissolution inhibiting group; Y ² represents an aliphatic cyclic group.)

In the general formula (a1-0-1), R represents a hydrogen atom or a lower alkyl group, and a description of the hydrogen atom or the lower alkyl group bonded to the α-position of the above-mentioned (α-lower alkyl) acrylate ester; It is the same thing. .
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.
In the present specification and claims, “aliphatic” is a relative concept with respect to aromatics, and is defined to mean groups, compounds, and the like that do not have aromaticity.
The “aliphatic cyclic group” means a monocyclic group or a polycyclic group having no aromaticity.
At this time, the “aliphatic cyclic group” 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, tricycloalkanes, tetraalkyls which may or may not be substituted with a fluorine atom or a fluorinated alkyl group. Examples thereof include groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as cycloalkane. 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.

［式中、Ｒは上記と同じであり、Ｒ^１５、Ｒ^１６はアルキル基（直鎖、分岐鎖状のいずれでもよく、好ましくは炭素数１〜５である）を示す。］

[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). ]

  Moreover, in the said alkoxyalkyl group, group shown with the following general formula is preferable.

（式中、Ｒ^２１、Ｒ^２２はそれぞれ独立して低級アルキル基または水素原子であり、Ｒ^２３はシクロアルキル基またはアルキル基である。または、Ｒ^２１とＲ^２３の末端が結合して環を形成していてもよい。）

(Wherein R ²¹ and R ²² are each independently a lower alkyl group or a hydrogen atom, and R ²³ is a cycloalkyl group or an alkyl group. Alternatively, the ends of R ²¹ and R ²³ are bonded to form a ring. (It may be formed.)

In R ²¹ and R ²² , the lower 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 a cycloalkyl group or an alkyl 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.
Preferably when R ²³ is a cyclic 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 a group excluding a hydrogen atom. 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 may be bonded to the end of R ²¹ .
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 defined 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, the same as described above for the “aliphatic cyclic group” can be used except that a group in which two or more hydrogen atoms are removed is used. .

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

［上記式中、Ｘは、第３級アルキルエステル型酸解離性溶解抑制基を表し、Ｙは炭素数１〜５の低級アルキル基、または脂肪族環式基を表し；ｎは０又は１〜３の整数を表し；ｍは０または１を表し；Ｒ、Ｒ^１、Ｒ^２はそれぞれ独立して水素原子または炭素数１〜５の低級アルキル基を表す。］

[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; It represents the integer 3; m is 0 or ^{1; R, R 1, R} 2 each independently represents a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms. ]

Preferably, at least one of R ¹ and R ² is a hydrogen atom, more preferably a hydrogen atom. n is preferably 0 or 1.

X are the same tertiary alkyl ester-type acid dissociable, dissolution inhibiting groups as those described above for X ^1. Examples of the aliphatic cyclic group for Y include the same groups as those exemplified above in the description of “aliphatic cyclic group”.

  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) is preferable, and specifically, the structural units represented by (a1-1-1) to (a1-1-6) are most preferable.
In addition, as the structural unit (a1), those represented by general formula (a1-1-0) shown below that include the structural units of formula (a1-1-1) to formula (a1-1-4) are also included. preferable.

（式中、Ｒは水素原子または低級アルキル基を示し、Ｒ^１１は低級アルキル基を示す。）

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

R is the same as described 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 the polymer compound (A1), the proportion of the structural unit (a1) is preferably 10 to 80 mol%, more preferably 20 to 60 mol%, based on all structural units constituting the polymer compound (A1). More preferred is ˜50 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 polymer compound (A1) may have a structural unit (a2) derived from an (α-lower alkyl) acrylate ester having a lactone-containing monocyclic or polycyclic group in addition to the structural unit (a1). preferable.
The lactone-containing monocyclic or polycyclic group of the structural unit (a2) can be used to increase the adhesion of the resist film to the substrate when the polymer compound (A1) is used for forming a resist film, It is effective in increasing hydrophilicity.
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.

Any lactone-containing monocyclic or polycyclic group can be used without particular limitation as long as it has such a lactone ring.
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.

［式中、Ｒは水素原子または低級アルキル基であり、Ｒ’は水素原子、低級アルキル基、または炭素数１〜５のアルコキシ基であり、ｍは０または１の整数である。］

[Wherein, R is a hydrogen atom or a lower alkyl group, 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 and 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.

  In general, in the component (A), when the structural unit (a2-1) represented by the general formula (a2-1) is included, the tip of the resist pattern becomes round and the rectangularity tends to deteriorate. In the present invention, a rectangular resist pattern can be obtained even when the component (A) containing the structural unit (a2-1) is used.

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

  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 polymer compound (A1), as the structural unit (a2), one type of structural unit may be used alone, or two or more types may be used in combination.
10-80 mol% is preferable with respect to the sum total of all the structural units which comprise a high molecular compound (A1), and, as for the ratio of the structural unit (a2) in a high molecular compound (A1), 20-60 mol% is more. Preferably, 30-50 mol% is more preferable. By making it the lower limit value or more, the effect of containing the structural unit (a2) can be sufficiently obtained, and by making it the upper limit value or less, it is possible to balance with other structural units.

・ Structural unit (a3)
The polymer compound (A1) may further have a structural unit (a3) derived from an (α-lower alkyl) acrylate ester containing a polar group-containing aliphatic hydrocarbon group. 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, 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 (α-lower alkyl) acrylic A structural unit derived from an acid ester is more preferred. Examples of the polycyclic group include groups in which two or more hydrogen atoms have been removed from bicycloalkane, tricycloalkane, tetracycloalkane and the like. Specific examples include groups in which two or more hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, and 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.

  As the structural unit (a3), 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, (α-lower alkyl) acrylic acid A structural unit derived from hydroxyethyl ester is preferred, and 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) The structural unit represented by (a3-3) is preferable.

（式中、Ｒは前記に同じであり、ｊは１〜３の整数であり、ｋは１〜３の整数であり、ｔは１〜３の整数であり、ｌは１〜５の整数であり、ｓは１〜３の整数である。）

(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 from 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. In these, a 2-norbornyl group or a 3-norbornyl group is preferably bonded to the terminal of the carboxy group of (α-lower alkyl) 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 polymer compound (A1) has the structural unit (a3), the proportion of the structural unit (a3) in the polymer compound (A1) is 5 with respect to all the structural units constituting the polymer compound (A1). It is preferably ˜50 mol%, more preferably 10 to 35 mol%.

・ Structural unit (a4)
The polymer compound (A1) 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 that is not classified into the structural units (a1) to (a3) described above. For ArF excimer laser, for KrF positive excimer laser (preferably ArF excimer) A number of hitherto known materials can be used for resist resins such as lasers.
As the structural unit (a4), for example, a structural unit containing an acid non-dissociable aliphatic polycyclic group and derived from an (α-lower alkyl) acrylate ester is preferable. Examples of the polycyclic group include those similar to those exemplified in the case of the structural unit (a1), and for ArF excimer laser and KrF positive excimer laser (preferably for ArF excimer laser). A number of hitherto known materials can be used for 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.
Specific examples of the structural unit (a4) include those represented by the following general formulas (a4-1) to (a4-5).

（式中、Ｒは前記と同じである。）

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

  The structural unit (a4) is not an essential component of the polymer compound (A1), but when it is contained in the polymer compound (A1), the total of all the structural units constituting the polymer compound (A1). The structural unit (a4) is preferably contained in an amount of 1 to 30 mol%, preferably 10 to 20 mol%.

The polymer compound (A1) 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). it can.
Further, in the polymer compound (A1), a chain transfer agent such as HS—CH ₂ —CH ₂ —CH ₂ —C (CF ₃ ) ₂ —OH is used in combination in the above polymerization. it may be introduced -C _{(CF 3)} 2 -OH group at the terminal. As described above, a copolymer introduced with a hydroxyalkyl group in which a part of hydrogen atoms in the alkyl group is substituted with a fluorine atom reduces development defects and LER (line edge roughness: uneven unevenness of line side walls). Is effective.

Although the mass mean molecular weight (Mw) (polystyrene conversion standard by gel permeation chromatography) of a high molecular compound (A1) is not specifically limited, 3000-50000 are preferable, 5000-30000 are more preferable, 7000-15000. Is most preferred. By making it below the upper limit of this range, solubility in a resist solvent sufficient for use as a resist is improved, and by making it above the lower limit of this range, dry etching resistance and resist pattern cross-sectional shape are improved. .
The dispersity (Mw / Mn) is preferably 1.0 to 5.0, and more preferably 1.0 to 3.0.
The same applies to the Mw and dispersity of the component (A).

  The proportion of the component (A) in the positive resist composition can be appropriately adjusted depending on the intended resist film thickness.

<(B) component>
The component (B) is not particularly limited, and any component that has been proposed as an acid generator for a chemically amplified positive resist can be used. Examples of such acid generators include onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, poly (bissulfonyl) diazomethanes, and the like. There are various known diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators, and the like.

  Specific examples of the onium salt-based acid generator include diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, bis (4-tert-butylphenyl) iodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, and triphenylsulfonium trifluoromethane. Sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, tri (4-methylphenyl) sulfonium trifluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, dimethyl (4-hydroxynaphthyl) sulfonium trifluoromethane Sulfonate, its heptafluoropropane sulphonate or its Nafluorobutane sulfonate, trifluoromethane sulfonate of monophenyldimethylsulfonium, heptafluoropropane sulfonate or nonafluorobutane sulfonate thereof, trifluoromethane sulfonate of diphenyl monomethylsulfonium, heptafluoropropane sulfonate or nonafluorobutane sulfonate thereof, (4- Trifluoromethanesulfonate of methylphenyl) diphenylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of (4-methoxyphenyl) diphenylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, tri (4 -Tert-bu Le) trifluoromethanesulfonate triphenylsulfonium, its like heptafluoropropane sulfonate or nonafluorobutane sulfonates.

  Specific examples of oxime sulfonate acid generators include α- (p-toluenesulfonyloxyimino) -benzyl cyanide, α- (p-chlorobenzenesulfonyloxyimino) -benzyl cyanide, α- (4-nitrobenzenesulfonyloxy). Imino) -benzylcyanide, α- (4-nitro-2-trifluoromethylbenzenesulfonyloxyimino) -benzylcyanide, α- (benzenesulfonyloxyimino) -4-chlorobenzylcyanide, α- (benzenesulfonyl) Oxyimino) -2,4-dichlorobenzylcyanide, α- (benzenesulfonyloxyimino) -2,6-dichlorobenzylcyanide, α- (benzenesulfonyloxyimino) -4-methoxybenzylcyanide, α- ( 2-Chlorobenzenesulfonyloxyimino) 4-methoxybenzylcyanide, 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-cyclo Pentenyl acetonitrile, α- (methylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -1-cycloheptenylacetonitrile, α- (methylsulfonyloxyimino) -1-cyclooctene Acetonitrile, α- (trifluoromethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -cyclohexylacetonitrile, α- (ethylsulfonyloxyimino) -ethylacetonitrile, α- (propyl Sulfonyloxyimino) -propylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclopentylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclohexylacetonitrile, α- (cyclohexylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- ( Ethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclope Nthenyl acetonitrile, 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- (trifluoro Methylsulfonyloxyimino) -phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p- Butoxy phenylacetonitrile, alpha-(propylsulfonyl oxyimino)-p-methylphenyl acetonitrile, alpha-like (methylsulfonyloxyimino)-p-bromophenyl acetonitrile. Of these, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile is preferred.

An oxime sulfonate acid generator represented by the following chemical formula can also be used.

Among diazomethane acid generators, specific examples of bisalkyl or bisarylsulfonyldiazomethanes include bis (isopropylsulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (1,1-dimethylethylsulfonyl) diazomethane, Examples include bis (cyclohexylsulfonyl) diazomethane, bis (2,4-dimethylphenylsulfonyl) diazomethane, and the like.
Examples of poly (bissulfonyl) diazomethanes include 1,3-bis (phenylsulfonyldiazomethylsulfonyl) propane (Compound A, decomposition point 135 ° C.), 1,4-bis (phenyl) having the following structure. Sulfonyldiazomethylsulfonyl) butane (compound B, decomposition point 147 ° C.), 1,6-bis (phenylsulfonyldiazomethylsulfonyl) hexane (compound C, melting point 132 ° C., decomposition point 145 ° C.), 1,10-bis (phenyl) Sulfonyldiazomethylsulfonyl) decane (compound D, decomposition point 147 ° C.), 1,2-bis (cyclohexylsulfonyldiazomethylsulfonyl) ethane (compound E, decomposition point 149 ° C.), 1,3-bis (cyclohexylsulfonyldiazomethylsulfonyl) ) Propane (Compound F, decomposition point 153 ° C.), , 6-bis (cyclohexylsulfonyldiazomethylsulfonyl) hexane (Compound G, melting point 109 ° C., decomposition point 122 ° C.), 1,10-bis (cyclohexylsulfonyldiazomethylsulfonyl) decane (Compound H, decomposition point 116 ° C.), etc. Can be mentioned.

In the present invention, it is particularly preferable to use an onium salt having a fluorinated alkyl sulfonate ion as an anion as the component (B).
As the component (B), one type of acid generator may be used alone, or two or more types may be used in combination.
(B) Content of a component is 0.5-30 mass parts with respect to 100 mass parts of (A) component, Preferably it is 1-10 mass parts. By setting it within the above range, pattern formation is sufficiently performed. Moreover, since a uniform solution is obtained and storage stability becomes favorable, it is preferable.

<(D1) component>
The component (D1) is a surfactant having an amide bond.
The component (D1) is not particularly limited as long as it has an amide bond, and may be a primary amide, a secondary amide, or a tertiary amide, but a primary amide is preferred.
And it preferably has “—NR ₄₁ —C (O) — bond”. In the formula, R ₄₁ is a hydrogen atom or an alkyl group. In R _41, the alkyl group may be either linear or branched, and the number of carbon atoms is preferably 5 to 20, preferably 5 to 15, further from 6 to 10. As the component (D1), an N-substituted amide in which R ₄₁ is an alkyl group is more preferable.

  More specifically, the component (D1) preferably includes the compound (d1) represented by the following general formula (d1), and the component (D1) is more preferably composed of the compound (d1).

(In the formula, R ₄₀ represents an alkyl group having 5 to 20 carbon atoms, and R ₄₂ represents an alkylene group having 2 to 5 carbon atoms which may have a substituent.)

R ₄₀ is preferably the same as R ₄₁ .
_R42 is an optionally substituted alkylene group having 2 to 5 carbon atoms, and the alkylene group may be linear or branched, but may be linear. preferable. Examples of the substituent include a lower alkoxy group having 1 to 5 carbon atoms. Among these, it is preferable not to have a substituent.
Of those contained in the compound (d1), the compound (d1-1) represented by the following chemical formula (d1-1) is particularly preferable.

(D1) A component can be used 1 type or in mixture of 2 or more types.
And the compounding quantity of (D1) component is 0.01-1 mass part with respect to 100 mass parts of (A) component, Preferably it is 0.05-0.5 mass part, Furthermore, 0.08-0.2. Part by mass. By setting it to the lower limit value or more, the effect of the present invention can be improved. By setting the upper limit value or less, saturation of the effect can be prevented, which is economically advantageous.

In the positive resist composition of the present invention, the above component (A), component (B), component (D1), and various optional components described later are dissolved in an organic solvent (hereinafter also referred to as component (C)). Can be manufactured.
As the component (C), any organic solvent may be used as long as it can dissolve each component to be used to form a uniform solution, and any conventionally known solvent for chemical amplification resists can be used. One or two or more 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 mixing ratio (mass ratio) may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, but is preferably 1: 9 to 9: 9: 1, more preferably 2: 8 to 8: A range of 2 is preferable.
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.
(C) Although the usage-amount of a component is not specifically limited, Although it is a density | concentration which can be apply | coated to a board | substrate etc. and is suitably set according to a coating film thickness, generally the solid content concentration 2-2 of a resist composition. It is used so that it may become in the range of 20 mass%, Preferably 5-15 mass%.

In the positive resist composition, a nitrogen-containing organic compound (D) (hereinafter referred to as (D)), which is not the component (D1), is further added as an optional component in order to improve the resist pattern shape and stability with time. Component)).
As the component (D), a wide variety of so-called quenchers have already been proposed, and any known one may be used. For example, n-hexylamine, n-heptylamine, n-octylamine , N-nonylamine, monoalkylamines such as n-decylamine; dialkylamines such as diethylamine, di-n-propylamine, di-n-heptylamine, di-n-octylamine, dicyclohexylamine; trimethylamine, triethylamine, tri-amine n-propylamine, tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decanylamine , Trialkylamines such as tri-n-dodecylamine; Ethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, di -n- octanol amine, alkyl alcohol amines tri -n- octanol amine is Ageraru. Among these, secondary aliphatic amines and tertiary aliphatic amines are preferable, and tertiary alkanolamines such as triethanolamine and triisopropanolamine are particularly preferable.
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.
In addition, since the component (D1) can also serve as the component (D), in the resist composition essential for the component (D1) of the present invention, the amount of the component (D) can be reduced, The component (D) can be omitted.

In addition, the positive resist composition of the present invention further 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. Alternatively, phosphorus oxo acid or its derivative (E) (hereinafter referred to 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.

  The positive resist composition of the present invention may further contain miscible additives as desired, for example, an additional resin for improving the performance of the resist film, a surfactant for improving coating properties, a dissolution inhibitor, Plasticizers, stabilizers, colorants, antihalation agents, dyes, and the like can be added and contained as appropriate.

≪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 applied onto 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. After selectively exposing ArF excimer laser light through a desired mask pattern using, for example, an ArF exposure apparatus or the like, PEB (post-exposure heating) is performed for 40 to 120 seconds at a temperature of 80 to 150 ° C., preferably Apply for 60-90 seconds. Subsequently, this is developed using an alkaline developer, for example, an aqueous 0.1 to 10% by mass tetramethylammonium hydroxide solution. 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. The photoresist composition according to the present invention is particularly effective for an ArF excimer laser.

  In the present invention, it is possible to provide a resist composition and a method for forming a resist pattern that can improve the rectangularity of the cross-sectional shape of the resist pattern. Also, the resolution is good.

Examples of the present invention will be described below, but the scope of the present invention is not limited to these examples.
[Example 1]
The following assembly materials were mixed to obtain a positive resist composition.
Component (A): resin composed of structural units represented by the following chemical formula [n: m: l = 30: 50: 20 (mol%)] (mass average molecular weight 10,000, dispersity 2.0) 100 parts by mass

Component (B): a mixture of 2.0 parts by mass of the compound represented by the following chemical formula (b1) and 0.8 part by mass of the compound represented by the following chemical formula (b2)

Component (C): PGMEA / EL (mass ratio) = 8/2 mixture 900 parts by mass γ-butyrolactone 25 parts by mass

(D1) Component: Compound (d1-1) 0.1 part by mass (D) Component: Triethanolamine 0.25 part by mass

Subsequently, the following evaluation was performed.
An organic antireflection film material (trade name ARC-29A, manufactured by Brewer Science Co., Ltd.) is applied onto an 8-inch silicon wafer and baked at 225 ° C. for 60 seconds to form an antireflection film having a thickness of 77 nm. did.
On the substrate, the positive resist composition obtained above is uniformly applied using a spinner, pre-baked on a hot plate at 120 ° C. for 60 seconds, and dried to form a resist layer having a thickness of 270 nm. Formed. Subsequently, it selectively exposed through the binary mask using ArF exposure apparatus (wavelength 193nm) NSR-S302 (made by Nikon, NA (numerical aperture) = 0.60, 2/3 annular illumination).
Then, PEB treatment is performed at 120 ° C. for 60 seconds, and further paddle development is performed with a developer (2.38 mass% tetramethylammonium hydroxide aqueous solution) at 23 ° C. for 60 seconds, and then pure water is used for 30 seconds. The film was rinsed with water and dried by shaking to form a 120 nm line and space (1: 1) resist pattern (hereinafter referred to as L / S pattern).

<Sensitivity>
The exposure amount at which a 120 nm line and space (L / S) pattern was formed at 1: 1 was measured in units of mJ / cm ² (energy amount) as sensitivity (EOP). As a result, the sensitivity was 31 mJ / cm ^2.

<Resist pattern shape>
At the sensitivity (EOP), an L / S pattern of 110 nm and an L / S pattern of 120 nm were obtained.
When these patterns were observed from above with a scanning electron microscope (SEM), the width of the white band generated at the edge portion parallel to the longitudinal direction of the pattern was very small. In addition, the width of the white band tends to increase as the tip of the cross-sectional shape becomes rounded.
And when cross-sectional shape was observed with the scanning electron microscope (SEM), it was cross-sectional rectangle.

[Comparative Example 1]
In Example 1, a positive resist composition was produced in the same manner except that the component (D1) was not blended, and evaluated in the same manner.
As a result, the sensitivity was 25 mJ / cm ² .
Regarding the pattern shape, the width of the white band was larger than that of Example 1 when observed from above the pattern. Furthermore, the cross-sectional shape had a rounded tip.

  The positive resist compositions of Example 1 and Comparative Example 1 were exposed under the same depth of focus characteristics (DOF) and mask linearity characteristics [same exposure conditions (the same mask size on the reticle, but the same exposure amount)]. In this case, the characteristics of accurately reproducing resist patterns corresponding to different mask dimensions on the reticle] were evaluated.

From these results, it was confirmed that a pattern shape with good rectangularity was obtained in the examples according to the present invention. It was also confirmed that the L / S pattern of 110 nm could be resolved and the resolution was good.

Claims (10)

In a resist composition containing a resin component (A) whose acid solubility is changed by the action of an acid and an acid generator component (B),
A resist composition comprising a surfactant (D1) having an amide bond. The resist composition according to claim 1, wherein the component (D1) contains a compound (d1) represented by the following general formula (d1).

(In the formula, R ₄₀ represents an alkyl group having 5 to 20 carbon atoms, and R ₄₂ represents an alkylene group having 2 to 5 carbon atoms which may have a substituent.) The resist composition according to claim 2, wherein the compound (d1) includes a compound (d1-1) represented by the following chemical formula (d1-1).

  The resist composition as described in any one of Claims 1-3 WHEREIN: The resist composition whose compounding quantity of (D1) component is 0.01-1 mass part with respect to 100 mass parts of (A) component.   The resist composition according to any one of claims 1 to 4, wherein the component (A) is derived from an (α-lower alkyl) acrylate ester having an acid dissociable, dissolution inhibiting group (a1). A resist composition comprising a polymer compound (A1) having a structural unit (a2) derived from an (α-lower alkyl) acrylate ester having a lactone-containing monocyclic or polycyclic group.   The resist composition according to claim 5, wherein the polymer compound (A1) further comprises a structural unit (a3) derived from an (α-lower alkyl) acrylate ester containing a polar group-containing aliphatic hydrocarbon group. A resist composition. The resist composition according to claim 5 or 6, wherein the structural unit (a2) includes a structural unit (a2-1) represented by the following general formula (a2-1).

(In the formula, R and R ′ each independently represent a hydrogen atom or a lower alkyl group, and two R ′ may be different or the same.)   The resist composition according to claim 1, wherein the component (A) includes a structural unit derived from an α-lower alkyl-acrylic ester.   The resist composition according to claim 1, further comprising a nitrogen-containing organic compound (D) different from the component (D1). The resist composition according to any one of claims 1 to 9 is applied on a substrate, pre-baked, selectively exposed, then subjected to PEB (post-exposure heating), alkali development, and resist. A resist pattern forming method comprising forming a pattern.