WO2005057287A1

WO2005057287A1 - Positive resist composition and method for forming resist pattern

Info

Publication number: WO2005057287A1
Application number: PCT/JP2004/018189
Authority: WO
Inventors: Hideo Hada; Masaru Takeshita; Ryotaro Hayashi; Syogo Matsumaru
Original assignee: Tokyo Ohka Kogyo Co., Ltd.
Priority date: 2003-12-15
Filing date: 2004-12-07
Publication date: 2005-06-23
Also published as: JP2005173468A; TW200528923A; TWI286670B

Abstract

Disclosed is a positive resist composition with excellent resolution which enables to reduce line-edge roughness. This composition contains, as a resin component (A) whose alkali solubility is increased by action of an acid, a copolymer having a constitutional unit (a1) derived from a (meth)acrylate containing a polycyclic group-containing acid-cleavable dissolution inhibiting group, a constitutional unit (a2) derived from a (meth)acrylate containing a lactone-containing monocyclic or polycyclic group, a constitutional unit (a3) derived from a (meth)acrylate containing a hydroxyl group-containing polycyclic group, and a constitutional unit (a4) derived from a (meth)acrylate containing a polycyclic group-containing acid-uncleavable dissolution inhibiting group other than the constitutional units (a2) and (a3); and as an acid generator component (B) which generates an acid when exposed to light, at least one sulfonium compound represented by the following general formula (b-1) or (b-2).

Description

Specification

Positive resist composition and method for forming resist pattern

Technical field

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

This application claims the priority of Japanese Patent Application No. 2003-416,584 filed on Dec. 15, 2003, the content of which is incorporated herein by reference.

Background art

In recent years, in the production of semiconductor devices and liquid crystal display devices, miniaturization has rapidly progressed due to advances in lithography technology. As a method of miniaturization, the wavelength of an exposure light source is generally shortened. Specifically, ultraviolet rays typified by g-line and i-line have been used in the past, but now a KrF excimer laser (248 nm) has been introduced.

In addition, one of the resist materials that satisfies the conditions of high resolution that can reproduce fine dimensional patterns contains a base resin that increases alkali solubility by the action of acid and an acid generator that generates acid by exposure. A chemically amplified positive resist composition is known. As the acid generator, at present, oxam salt is most commonly used. Most of the aeon part (acid) of the oxam salt is a chain-like fluorinated alkylsulfonate ion, and other acids are rarely used because of the problem of acidity. In order to control the diffusion length of the acid in the resist film, the alkyl chain of the fluorinated alkyl is preferably a carbon atom having a long carbon number, and the alkyl chain has a carbon number of 4 or more. With regard to fluorinated alkyl sulfonic acids, safety concerns have begun to be raised, and their use is now being restricted worldwide. Therefore, there is a need for an acid generator having a short diffusion length in a resist film without using such a long-chain fluorinated alkylsulfonic acid.

[0003] On the other hand, with the rapid miniaturization of semiconductor elements in recent years, further improvement in resolution is required. In particular, when forming a so-called isolated line pattern in which the ratio of the resist line portion size to the space portion size is less than 1, for example, the ratio of the resist line portion size to the space portion size is 1Z9, it is necessary to improve the resolution. It is becoming. Furthermore, the size of such an isolated line pattern portion (sparse pattern portion) and the space portion is not required. And so-called line-and-space (L & S) pattern parts (dense pattern parts) where the ratio of the resist line part size to be used is 1 or more, for example, the ratio of the resist line part size to the space part size is 1Z1 In the pattern forming process, there is a problem of a so-called proximity effect in which a difference occurs in the resist pattern size between the sparse pattern portion and the dense pattern portion, but it is difficult to suppress such a proximity effect with a conventional resist. Yes, improvements are desired.

Also, with the rapid miniaturization of semiconductor devices, line edge roughness (LER) has become a serious problem, and improvement thereof is also desired.

[0004] The present inventors have already included a specific quaternary copolymer as a chemically amplified positive resist composition which is excellent in the resolution of an isolated line pattern and can suppress the proximity effect in a dense / dense mixed pattern. Proposal of a posi-type resist composition using, as a base resin, a resin component having a unit derived from a (meth) acrylic ester in the main chain and having an increased solubility in alkali due to the action of an acid, (See Patent Document 1).

However, although the positive resist composition containing the quaternary copolymer described in Patent Document 1 is excellent in the resolution of the isolated line pattern, the resolution of the L & S pattern and the trench pattern, that is, the resist The resolution of an isolated space pattern in which the ratio of the space portion size to the line portion size is less than 1, for example, the ratio of the space portion size to the resist line portion size is 1Z9 is not sufficient. Therefore, further improvement is required for the resolution of these patterns. Further, a positive resist composition containing the quaternary copolymer is required to further improve line edge roughness.

(Patent Document 1) Japanese Patent Application Laid-Open No. 2003-167347

Disclosure of the invention

Problems to be solved by the invention

The present invention has been made in view of the above circumstances, and is directed to a positive resist composition having excellent LER reduction and resolution, particularly excellent resolution of L & S patterns and isolated space patterns. An object of the present invention is to provide a method for forming a resist pattern using a distaste composition.

Means for solving the problem [0006] The present inventors have conducted intensive studies and found that the above problem can be solved by using the quaternary copolymer in combination with a specific acid generator.

The present invention has been made based on the above findings. The first aspect (aspect) of the present invention comprises (A) a resin component whose alkali solubility is increased by the action of an acid, and (B) an acid component by exposure to light. A positive resist composition containing an acid generator component that generates

The resin component (A) includes a monocyclic or polycyclic group-containing acid dissociable, dissolution inhibiting group, a (meth) acrylate structural unit derived from acrylate ester (al), and a rataton-containing monocyclic or polycyclic ring. A structural unit (a2) derived from a (meth) acrylate ester containing a formula group, a structural unit (a3) derived from a (meth) acrylate ester containing a hydroxyl group-containing polycyclic group, and the structural unit ( a2), _a copolymer containing _a structural unit ( _a4 ) derived from a (meth) acrylate ester containing a polycyclic group-containing non-acid dissociable, dissolution inhibiting group other than (a3),

The positive resist composition, wherein the acid generator component (B) contains at least one sulfo-dimethyl compound represented by the following general formula (b-1) or (b-2) It is.

[0007] [Formula 1]

[0008] In the formula, X represents an alkylene group having 2 to 6 carbon atoms in which at least one hydrogen atom has been replaced by a fluorine atom; Υ and 、 each independently represent at least one hydrogen atom having a fluorine atom Represents an alkyl group having 1 to 10 carbon atoms substituted with; R ¹ — R ³ each independently represents an aryl group or an alkyl group, and at least one of R ¹ — R ³ represents an aryl group . Further, the second aspect of the present invention (aspect) is that the positive resist composition is used on a substrate. A resist pattern forming method comprising: forming a resist film on a resist film; selectively performing exposure processing on the resist film; and developing the resist film with an alkali to form a resist pattern.

In the present invention, the “rataton-containing monocyclic group or polycyclic group” is a monocyclic group composed of a rataton ring or a polycyclic group having a rataton ring. In this case, the rataton ring refers to one ring containing a CO—O structure, which is counted as the first ring. Therefore, here, a rataton-containing monocyclic group is used in the case of only a rataton ring, and a rataton-containing polycyclic group is used in the case of having another ring structure regardless of the structure. In the present invention, the “structural unit” means a monomer unit constituting the polymer. In addition, in the present specification, the “structural unit from which the (meth) acrylic acid ester power is also derived” refers to a unit represented by the following general formula (5), where R is a hydrogen atom. A constitutional unit derived from an ester, a constitutional unit derived from a methacrylic acid ester which is an R-methyl group, and a lower alkyl group having about 2 to 5 carbon atoms in which R is a specific example, specifically, an ethyl group, It is a general term for structural units that are linear or branched alkyl groups such as propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, and neopentyl group.

[0010] [Formula 2]

The invention's effect

[0011] According to the positive resist composition and the method of forming a resist pattern of the present invention, a resist pattern excellent in LER reduction and resolution, particularly in resolution of an L & S pattern and an isolated space pattern, can be formed.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The positive resist composition of the present invention comprises a resin component (A) whose alkali solubility is increased by the action of an acid (hereinafter sometimes referred to as a component (A)), and an acid generator component which generates an acid upon exposure. (B) (hereinafter sometimes referred to as component (B)).

According to the present invention, the component (A) is a copolymer containing the structural unit (al)-(a4), and the component (B) is a copolymer represented by the general formula (b-1) or (b-2). ), Characterized in that it contains at least one sulfonium compound.

By the combination of the component (A) and the component (B), it is possible to form a resist pattern excellent in resolution, particularly in resolution of an L & S pattern or an isolated space pattern. Also, the shape of the obtained resist pattern is excellent in rectangularity with high perpendicularity of the pattern side wall. Further, a resist pattern with reduced line edge roughness (LER) can be formed. Also, the depth of focus (DOF) when forming a resist pattern is large. Here, LER means uneven unevenness formed on a sidewall of a line and space pattern in a developed resist pattern, for example.

[0013] <Component (A)>

The component (A) is an alkali-insoluble component having a so-called acid dissociable, dissolution inhibiting group. When an acid generated from the component (B) acts upon exposure to light, the acid dissociable, dissolution inhibiting group dissociates. As a result, the entire component (A) changes to alkali-insoluble caparum and alkali-soluble. Therefore, when exposure is performed through a mask pattern in the formation of a resist pattern, or when post-exposure bake (PEB) is performed in addition to exposure, the exposed part turns alkali-soluble, while the unexposed part remains alkali-insoluble. Since it does not change, a positive resist pattern can be formed by alkali development.

The structural unit (al) is a unit derived from a (meth) acrylate ester containing a monocyclic or polycyclic group-containing acid dissociable, dissolution inhibiting group.

Examples of the monocyclic group include groups obtained by removing one hydrogen atom from a cycloalkane, for example, an aliphatic monocyclic group such as a cyclopentyl group and a cyclohexyl group. Polycyclic groups include bicycloalkane, tricycloalkane, tetracycloalkane, etc., adamantane, Examples include groups in which one hydrogen atom has been removed from polycycloalkanes such as norbornane, isobornane, tricyclodecane, and tetracyclododecane, that is, aliphatic polycyclic groups. Here, many of these monocyclic or polycyclic groups have been proposed for ArF resists.In the present invention, these monocyclic or polycyclic groups can be arbitrarily selected and used. Of these, use of an aliphatic polycyclic group such as an adamantyl group, a norbornyl group, or a tetracyclododele group is preferred in terms of industrial availability and the like.

[0015] As described above, the acid dissociable, dissolution inhibiting group has an alkali dissolution inhibiting property that renders the entire component (A) alkali-insoluble before exposure, and is generated from the component (B) described below after exposure. It is dissociated by the action of an acid, and changes the entire component (A) to alkali-soluble.

As such an acid dissociable, dissolution inhibiting group, for example, those which form a cyclic or chain tertiary alkyl ester with a carboxyl group of (meth) acrylic acid are widely known. Any structural unit (al) may be used without particular limitation as long as it has the above-mentioned functions. Specifically, at least one structural unit selected from the following general formulas (1), (2) and (3) is preferred in terms of excellent resolution and dry etching resistance.

[0016] [Formula 3]

(Where R is a hydrogen atom or a lower alkyl group, and R ¹ is a lower alkyl group)

[0017] [Formula 4]

(Where R is a hydrogen atom or a lower alkyl group, and R ² and R ³ are each independently a lower alkyl group)

[0018] [Formula 5]

(3)

(Where R is a hydrogen atom or a lower alkyl group, and R ⁴ is a tertiary alkyl group)

[0019] In the structural unit represented by the general formula (1), the carbon atom adjacent to the oxygen atom (1-O-1) in the ester portion of (meth) acrylic acid is the third unit on the ring skeleton such as an adamantyl group. This is the case when it becomes a lower alkyl group.

R represents a hydrogen atom or a methyl group, and further a lower alkyl group having 2 to 5 carbon atoms, specifically, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, Lower linear or branched alkyl groups such as pentyl group, isopentyl group and neopentyl group are exemplified. R ¹ is a lower linear or branched group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group. Alkyl group. Here, if R ¹ is an alkyl group having 2 or more carbon atoms, acid dissociation tends to be higher than that of a methyl group, which is preferable. However, industrially, a methyl group or an ethyl group is most preferable.

[0020] In the structural unit represented by the general formula (2), the carbon atom adjacent to the oxygen atom (1-O-1) in the ester portion of (meth) acrylic acid is a tertiary alkyl group. And a ring skeleton such as an adamantyl group. In the structural unit represented by the general formula (2), R has the same definition as in the general formula (1), and R ² and R ³ are each independently a lower alkyl group, that is, It is a C5 linear or branched alkyl group. Such groups tend to be more acid dissociable than the 2-methyl-2-adamantyl group. It is industrially preferable that both R ² and R ^{3 be} methyl groups.

[0021] In the structural unit represented by the general formula (3), the carbon atom adjacent to the oxygen atom (-O-) in another ester part, which is different from the (meth) acrylate part, is a tertiary alkyl group. There is a case where the ester portion and the (meth) acrylate portion are connected by a ring skeleton such as a tetracyclododele group. In the unit represented by the general formula (3), R has the same definition as in the case of the general formula (1), and R ⁴ is a tertiary alkyl group such as a tert-butyl group or a tert-amyl group. And preferably a tertiary alkyl group having 4 or 5 carbon atoms. It is industrially preferable that R ^{4 be} a t tert-butyl group.

Among the structural units represented by the general formulas (1) and (3), those which are particularly the structural units represented by the general formula (1) and in which R ¹ is a methyl group or an ethyl group It is preferable in that it has excellent power resolution.

The structural unit (a2) is a structural unit derived from ester (meth) acrylate containing a rataton-containing monocyclic or polycyclic group. The rataton functional group is effective for increasing the adhesion of the resist film formed from the composition of the present invention to the substrate and increasing the hydrophilicity with the developer.

The structural unit (a2) is not particularly limited as long as it has such a radian functional group and a cyclic group. Anything can be used without being done. Specifically, examples of the rataton-containing monocyclic group include groups in which the γ-petit mouth rataton force also excludes one hydrogen atom, and examples of the rataton-containing polycyclic group include a bicycloalkane having a rataton group. , Tricycloalkane, and tetracycloalkane groups which exclude one hydrogen atom. In particular, the structural formula

A rataton-containing bicycloalkane having the formula (6) or a rataton-containing tricycloalkane having the structural formula (7) is advantageous in terms of industrial availability and the like, excluding one hydrogen atom.

[0023] [Formula 6]

[0024] [Formula 7]

(7)

Further, specific examples of the structural unit (a2) include structural units derived from a (meth) acrylate ester cap having a rataton-containing monocycloalkyl group or a tricycloalkyl group. Include structural units represented by the following general formulas (8) to (10).

[0026]

(Wherein, R is a hydrogen atom or a lower alkyl group)

[0027] [Formula 9]

It exists as a mixture of isomers at the 5- or 6-position. (Wherein, R is a hydrogen atom or a lower alkyl group)

[0028] [Formula 10]

(Wherein, R is a hydrogen atom or a lower alkyl group)

[0029] In addition, among the structural units represented by the general formulas (8) to (10), the α-carbon has an ester bond in terms of excellent suppression and reduction of the proximity effect. Preference is given to a γ-petit ratatone ester of (meth) acrylic acid represented by the general formula (10), that is, a structural unit derived from a (meth) acrylate ester of γ-butyrolataton.

Further, the structural unit derived from norbornane ratatotone ester of (meth) acrylic acid represented by the general formulas (8) and (9), that is, the structural unit derived from the (meth) acrylic acid ester of norbornane ratatone is a resist pattern obtained. The shape, for example, the rectangularity is more favorable, so that it is preferable. In particular, the structural unit represented by the general formula (9) is preferable because its effect is extremely high.

[0030] Structural unit (a3) is a structural unit derived from a (meth) acrylate ester containing a hydroxyl group-containing polycyclic group, and has a hydroxyl group which is a polar group, so that the resin component (A) It enhances the hydrophilicity of the whole developer and improves the alkali solubility of the exposed part, thereby contributing to the improvement of the resolution. Here, as the polycyclic group, the same polycyclic group as in the case of the structural unit (al) can be used.

The structural unit (a3) is not particularly limited as long as it is a hydroxyl group-containing polycyclic group, and any unit can be used. Specifically, a hydroxyl-containing adamantyl group, particularly a structural unit represented by the following general formula (4), is preferred in that it has an effect of increasing dry etching resistance and an effect of making a pattern cross section rectangular.

[0031] [Formula 11]

( Four)

(Wherein, R is a hydrogen atom or a lower alkyl group)

The structural unit (a4) is a structural unit derived from a (meth) acrylate ester cap having a polycyclic group-containing non-acid dissociable, dissolution inhibiting group other than the structural units (a2) and (a3).

A structural unit derived from a (meth) acrylate ester containing a polycyclic group-containing non-acid dissociable, dissolution inhibiting group suppresses alkali solubility by increasing the hydrophobicity of the entire component (A) before and after exposure. A structural unit having a function. That is, while reducing the alkali solubility of the entire component (A) before exposure, the acid dissociable, dissolution inhibiting group of the structural unit (al) is not dissociated by the action of an acid generated from the component (B) after exposure. Is a structural unit containing a group having a dissolution inhibiting property that reduces the alkali solubility of the entire component (A) when the entire component (A) changes to alkali-soluble due to dissociation of the components.

The structural unit (a4) does not overlap with the structural unit (al), the structural unit (a2), and the structural unit (a3). That is, it does not hold any groups such as an acid dissociable, dissolution inhibiting group in the structural unit (al), a rataton group in the structural unit (a2), and a hydroxyl group in the structural unit (a3). As the polycyclic group of the structural unit (a4), the same polycyclic group as in the case of the structural unit (al) can be used.

As such a structural unit (a4), a number of conventionally known ArF positive resist materials can be used. Particularly, tricyclodecanyl (meth) acrylate, adamantyl (meth) acrylate Structural units derived from at least one member selected from the group consisting of methacrylate, tetracyclododetyl (meth) acrylate, and isovol (meth) acrylate It is preferable in that it is easy to perform. These exemplified constituent units are shown below as general formulas (11) and (14). Among these, the structural unit represented by the general formula (11) is preferable because the shape of the obtained resist pattern, for example, rectangularity is particularly good.

[0033] [Formula 12]

It exists as a mixture of isomers at the 5- or 6-position.

(Wherein, R is a hydrogen atom or a lower alkyl group)

[0034] [Formula 13]

(Wherein, R is a hydrogen atom or a lower alkyl group) [0035]

(Wherein, R is a hydrogen atom or a lower alkyl group)

[0036] The component (A) particularly includes a structural unit represented by the general formula (1) as the structural unit (al) and a structural unit represented by the general formula (9) as the structural unit (a2). A copolymer comprising a structural unit represented by the general formula (11) as a structural unit (a4) and a structural unit represented by the general formula (4) as a structural unit (a3); That is, a copolymer containing the four types of structural units described in the following [Chemical formula 15] is preferable. This is because the rectangularity of the LER and the resist pattern is particularly excellent. Further, the dry etching resistance is preferably higher than that of a resin described later.

Among them, a copolymer composed of the structural units (al)-(a4) is preferable because of its excellent effect.

[0037] [Formula 15]

(In the formula, R is a hydrogen atom or a lower alkyl group, and R ⁵ is a methyl group or an ethyl group.)

[0038] (A) constituent in the component unit (al) - the proportion of (a4), the structural unit (al) is 25 50 mole ^_0/0, the range of preferably 30 to 40 mole ^_0/0 There, the structural unit (a2) force 5- 50 mole ^_0/0, preferably in the range of 30- 40 mol%, the structural unit (a3) is 10 30 mole ^_0/0, preferably 10-20 mole ⁰ / ₀ in the range of the structural unit (a4) is 3-25 mole ^_0/0, and preferably from suitably in the range of 5-20 mol%. Within such a range, the obtained positive resist composition can greatly improve the depth of focus of the isolated pattern formed, and can sufficiently reduce the proximity effect by sufficiently suppressing the proximity effect. If the above range is largely deviated, a problem may occur when the resolution is reduced.

In addition, in the positive resist composition of the present invention, as the component (A), a monomer that forms each of the structural units (al)-(a4) is added to a conventional chemically amplified positive resist. To make the resist soluble in alkali such as acrylic acid derivatives, methacrylic acid derivatives, acrylic acid, methacrylic acid, maleic acid, fumaric acid, etc., which have a well-known dry etching resistance improving group or acid non-dissociable, dissolution inhibiting group. A known carboxylic acid having an ethylenic double bond, a known monomer used in the production of an acrylic resin, or the like is appropriately combined as needed and copolymerized.

As the acrylic acid derivative, for example, naphthyl acrylate, benzyl acrylate, atari Hydroxy group of carboxyl group, such as 3-lactic acid, oxocyclohexyl, ester of acrylic acid and terbineol, and ester of acrylic acid and 3-bromoacetone were protected by dry etching resistance improving group and acid non-dissociable substituent. Acrylic esters and the like can be mentioned. Examples of the methacrylic acid derivative include methacrylic acid derivatives corresponding to these acrylic acid derivatives.

[0041] Examples of the carboxylic acid having an ethylenic double bond include acrylic acid, methacrylic acid, maleic acid, and fumaric acid.

Examples of known monomers used in the production of acrylic resin include, for example, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate Alkyl acrylates such as octyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate, and the corresponding alkyl methacrylates. .

[0042] The component (A) is a monomer for deriving each structural unit, for example, azobisisobuty-tolyl

Polymerization can be obtained by known radical polymerization using a radical polymerization initiator such as (AIBN).

The mass average molecular weight of component (A) (polystyrene conversion standard by gel permeation chromatography) is preferably 30,000 or less, more preferably 7,500 or less. It is more preferably 4000-7200, most preferably 5000-6500. When the weight average molecular weight is S7500 or less, LER is further improved. Also, development defects during alkali development are reduced.

When the mass average molecular weight is 4000 or more, the synthesis of the component (A) is easy. The degree of dispersion is preferably 1.0-5.0 force S, more preferably 1.0-3.0.

[0044] The component (ii) can be composed of one or more resins. For example, the copolymer having the structural unit (al)-(a4) as described above can be used alone. Two or more types may be mixed and used.

In the present invention, since the component (A) is a copolymer containing the structural unit (al)-(a4), the depth of focus of an isolated line pattern is improved, and the proximity effect is reduced. Also reduce As a result, a resist pattern faithful to the mask pattern is formed in both the coarse and dense patterns.

In addition, the combination with the component (B) described later enhances the resolution of the L & S pattern and the isolated space pattern. Furthermore, the LER, shape and depth of focus of these patterns are improved.

[0046] <Component (B)>

In the present invention, the component (B) is a sulfo-dum compound represented by the general formula (b-1) or (b-2) (hereinafter referred to as a sulfo-dum compound 1 or a sulfo-dum compound, respectively). Compound 2).

In the formulas (b-1) and (b-2), X is a linear or branched alkylene group in which at least one hydrogen atom has been replaced by a fluorine atom, and the number of carbon atoms of the alkylene group is Is 2-6, preferably 3-5, and most preferably 3 carbon atoms.

Υ and Ζ are each independently a linear or branched alkyl group in which at least one hydrogen atom is substituted by a fluorine atom, and the alkyl group has 1 to 10 carbon atoms, and is preferably It is 117, more preferably 113. It is preferable that the number of carbon atoms of the alkylene group of X or the number of carbon atoms of the alkyl group of 小さい or 小さい be smaller, since the solubility in the resist solvent is better.

In the alkylene group of X or the alkyl groups of Υ and Ζ, as the number of hydrogen atoms substituted with fluorine atoms increases, the strength of the acid increases, and high energy of 200 nm or less or electron beam Preferred because it increases the transparency to. The proportion of fluorine atoms in the alkylene group or alkyl group, that is, the fluorination rate, is preferably 70-100%, more preferably 90-100%, and most preferably all hydrogen atoms are fluorine atoms. Or a perfluoroalkylene group or a perfluoroalkyl group.

[0048] R ¹ - R ³ each independently represent a Ariru group or an alkyl group.

At least one of R ^{1 to} R ³ represents an aryl group. R ¹ - of R ^3, preferably be 2 or more is a Ariru group instrument R ¹ - all R ³ is most preferably a Ariru group.

The aryl group represented by R ^{1 to} R ³ is not particularly limited. For example, it is an aryl group having 6 to 20 carbon atoms, which may or may not be substituted with an alkyl group, a halogen atom or the like. And a benzyl group and a naphthyl group. An aryl group having 6 to 10 carbon atoms is preferable because it can be synthesized at low cost.

The alkyl group of R ^{1 to} R ³ is not particularly limited, and examples thereof include a linear, branched or cyclic alkyl group having 11 to 10 carbon atoms. From the viewpoint of excellent resolution, it is preferable that the carbon number is 115. Specifically, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, cyclopentyl, hexyl, cyclohexyl, nonyl, decanyl A methyl group is preferred because it has excellent resolution and can be synthesized at a low cost.

Of these, it is most preferred that R ¹ — R ³ are all phenolic groups! / ,.

[0049] These sulfo-dimethyl compounds 1 and 2 may be used alone or in combination of two or more.

[0050] In the present invention, the component (B) provides a positive resist composition having excellent LER, resolution, resist pattern shape, depth of focus, and the like. It is necessary to include it.

[0051] In the component (B), the proportion of at least one selected from the sulfo-pum compounds 1 and 2 is preferably 25 to 100% by mass of the entire component (B) as a total amount. 100% by mass is more preferred. When the content is 25% by mass or more, the effect of the present invention is sufficient.

[0052] In the present invention, the component (B) may further contain a known acid generator conventionally used in a chemically amplified photoresist composition. Acid generators have been used in the past, such as rhododium salts and sulfonium salts, etc., oxime sulfonates, bisalkyl or bisarylsulfonyldiazomethanes, nitrobenzylsulfonates, Since various types such as iminosulfonates and disulfones are known, such known acid generators can be used without any particular limitation.

Among them, particularly, a dimethyl salt containing a fluorinated alkylsulfonic acid ion as an ion (hereinafter referred to as an ionic salt-based acid generator) is preferable because the generated acid is strong.

Examples of the cation of the strong acid salt-based acid generator include lower alkyl groups such as methyl group, ethyl group, propyl group, n-butyl group and tert-butyl group; methoxy group and ethoxy group. And substituted with a lower alkoxy group such as, for example, mono- or di-fluoronium, sodium di- or triphenylsulfonium; and dimethyl (4-hydroxynaphthyl) sulfonium.

In addition, the strong acid salt-based acid generator has one or more hydrogen atoms in a linear alkyl group having 117, more preferably 113 carbon atoms. Fluoroalkylsulfonic acid ionic force substituted with an atom Power with high safety Preferred. When the carbon number is 7 or less, the strength as a sulfonic acid also increases. Further, the fluorination rate (the ratio of fluorine atoms in the alkyl group) of the fluorinated alkyl sulfonate ion is preferably 10 to 100%, more preferably 50 to 100%, and in particular, all hydrogen atoms are fluorinated. It is preferable because the strength of the acid is increased. Specific examples of such a substance include trifluoromethanesulfonate and heptafluoropropanesulfonate.

[0053] Specific examples of such a foam salt-based acid generator include trifluoromethanesulfonate, nonafluorobutanesulfonate, and bis (4-tert-butylphenyl) odonium of diphenyl odonium. Trifluoromethanesulfonate or nonafluorobutanesulfonate, trifluoromethanesulfonate of triphenylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, tri (4-methylphenyl) sulfonate- ゥTrifluoromethanesulfonate, heptafluoropropanesulfonate or nonafluorobutanesulfonate, dimethyl (4-hydroxynaphthyl) sulfo-dimethyl trifluoromethanesulfonate, heptafluoropropanesulfonate or No Nafluorobutanesulfonate, trifluorone methanesulfonate of monophenyldimethylsulfonate, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, trifluorone of diphenylmonomethylsulfonate Romethanesulfonate, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate.

These acid salt-based acid generators can be used alone or in combination of two or more.

[0054] As the component (B), an acid salt-based acid generator is selected from sulfoxide compounds 1 and 2. When used as a mixture with at least one kind, the proportion of the acid salt-based acid generator is preferably from 10 to 75% by mass, more preferably from 30 to 70% by mass. By blending the acid generator within the above range, the LER and the development defect can be improved. Also, the mixing ratio (mass ratio) of the oxamium salt-based acid generator and at least one selected from the sulfo-ammonium compounds 1 and 2 is 1: 9 to 9: 1, preferably 1: 5 to 5-5. : 1, most preferably 1: 2—2: 1. By mixing and using an acid generator in the above ratio, LER and development defects are excellent.

[0055] The component (B) is used in a proportion of 0.1 to 30 parts by mass, preferably 0.5 to 20 parts by mass, more preferably 1 to 10 parts by mass, per 100 parts by mass of the component (A). . If the amount is less than the lower limit, image formation is not performed. If the amount is more than 30 parts by mass, a uniform solution is obtained, and storage stability may be deteriorated.

[0056] <Component (C)>

The positive resist composition of the present invention can be produced by dissolving the materials in an organic solvent (C) (hereinafter, referred to as component (C)).

As the component (C), any one can be used as long as it can dissolve each component to be used to form a uniform solution. Two or more types can be appropriately selected and used.

For example, ketones such as γ-butyrolatatone, acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, and 2-heptanone; ethylene glycol, ethylene glycol monomonoacetate, diethylene glycol, diethylene glycol monomonoacetate, Polyhydric alcohols such as propylene glycol, propylene glycol monoacetate, dipropylene glycol, dimethyl glycol monoacetate monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether, and derivatives thereof, and dioxane Cyclic ethers such as, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methoxide Methyl propionate, and E ester such as ethoxyethyl propionate Echiru can be exemplified. These organic solvents may be used alone or as a mixed solvent of two or more. Propylene glycol monomethyl ether acetate The mixing ratio of PGMEA and the polar solvent may be appropriately determined in consideration of the compatibility of PGMEA with the polar solvent, but is preferably 1: 9 to 9: 1, more preferably 2: 8. — It is preferable to be within the range of 8: 2.

More specifically, when mixing ethyl lactate (EL) as a polar solvent, the mass ratio of PGMEA: EL is preferably 2: 8-8: 2, and more preferably 3: 7-7: 3. preferable. In addition, as the organic solvent, a mixed solvent of at least one selected from the group consisting of PGMEA and EL and an organic solvent is also preferable. In this case, the mixing ratio of the former and the latter is preferably 70: 30-95: 5.

The amount of the component (C) is not particularly limited, but is a concentration that can be applied to a substrate or the like and is appropriately set according to the coating film pressure. Generally, the solid content concentration of the resist composition is 2 to 2 0 mass%, preferably in the range of 5-15 mass%.

[0057] <(D) component>

The positive resist composition of the present invention further comprises an optional component in order to improve the resist pattern shape, post exposure stability of the latent image rormed by the pattern wise exposure of the resist layer, and the like. For example, a nitrogen-containing organic compound (D) (hereinafter, referred to as a component (D)) can be blended.

Since a wide variety of components (D) have already been proposed, known components may be used arbitrarily, but amines, particularly secondary lower aliphatic amines ゃ tertiary lower aliphatic amines, are preferred. .

The term "lower aliphatic amine" refers to an alkyl or alkyl alcohol amine having 5 or less carbon atoms.Examples of the secondary and tertiary amines include trimethylamine, getylamine, triethynoleamine, and diamine. _n -Propylamine, tree n-Propylamine, tripentinoleamine, diethanolamine, triethanolamine, triisopropanolamine, etc. Power especially tertiary alkanolamine such as triethanolamine is preferable .

These may be used alone or in combination of two or more.

The component (D) is generally used in the range of 0.01 to 5.0 parts by mass based on 100 parts by mass of the component (A).

[0058] <Component (E)> Further, for the purpose of preventing the sensitivity deterioration due to the blending with the component (D) and improving the resist pattern shape, the stability over time, and the like, further, as an optional component, an organic carboxylic acid or oxo acid of phosphorus or phosphorus. The derivative (E) (hereinafter referred to as the component (E)) can be contained. In addition, the component (D) and the component (E) can be used in combination, or one of them is 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 oxo acids or derivatives thereof include phosphoric acid, derivatives such as phosphoric acid or di-n-butyl phosphate, diphenyl phosphate or the like, phosphonic acid, dimethyl phosphonate, and the like. Phosphonic acids such as di-n-butyl phosphonate, phenylphosphonic acid, diphenyl phosphonate, dibenzyl phosphonate and derivatives thereof such as esters, phosphines such as phosphinic acid and phenylphosphinic acid Derivatives such as acids and their esters are preferred, of which phosphonic acids are particularly preferred.

The component (E) is used in an amount of 0.01 to 5.0 parts by mass per 100 parts by mass of the component (A).

[0059] <Other optional components>

The positive resist composition of the present invention may further contain, if desired, additives that are miscible, for example, an additional resin for improving the performance of the resist film, a surfactant for improving coating properties, and dissolution inhibition. Agents, plasticizers, stabilizers, coloring agents, antihalation agents and the like can be added as needed.

<< Method of Forming Resist Pattern >>

The method of forming a resist pattern according to the present invention can be performed, for example, as follows. That is, first, the positive resist composition is applied on a substrate such as silicon wafer with a spinner or the like, and PAB (pre-beta) is applied at a temperature of 80 to 150 ° C. for 40 to 120 seconds, preferably 60 to 150 seconds. — Apply for 90 seconds to form resist film. After selectively exposing ArF excimer laser light through a desired mask pattern using, for example, an ArF exposure apparatus, PEB (post-exposure baking) is applied for 40-120 seconds at a temperature of 80-150 ° C. Apply for 60-90 seconds, preferably. This is then added to an alkaline developer such as 0.1-10% by weight tetra Develop using an aqueous solution of methyl ammonium hydroxide. Thus, a resist pattern faithful to the mask pattern can be obtained.

Note that an organic or inorganic antireflection film can be provided between the substrate and the coating layer of the resist composition.

The wavelength used for exposure is not particularly limited, and may be ArF excimer laser, KrF excimer laser, F excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), EB (electron

2

(Radiation), X-rays, soft X-rays and the like. The resist composition according to the present invention is particularly effective for an ArF excimer laser.

Example

[0061] Hereinafter, the present invention will be described in detail with reference to examples.

Synthesis example 1-1

0.25 mol of a mixture of the following monomers (all), (a21), (a31) and (a41) was dissolved in 500 ml of methyl ethyl ketone (MEK), and AIBNO. Olmol was dissolved in the solution. . The resulting solution was heated to 65-70 ° C and maintained at this temperature for 3 hours. Thereafter, the obtained reaction solution was poured into 3 L of well-stirred isopropanol, and the precipitated solid was separated by filtration. The obtained solid was dissolved in 300 ml of MEK, poured into 3 L of well-stirred methanol, and the precipitated solid was separated by filtration, dried, and expressed by the following [Chemical Formula 16]. Resin 1-1 was obtained.

(al l): 2- (In the general formula (1), in R mosquito butyl group, a monomer corresponding with the structural unit R ¹ is a methyl group) methyl-2 § Dammann chill meth Tari rate 40 mole ^_0/0

(a21): .gamma. butyrate Lola (in the general formula (10), a monomer corresponding with the structural unit in which R power methyl group) Taton meth Tari rate 40 mole ^_0/0

(a31): 3- (In the general formula (4), a monomer corresponding with the structural unit R is a methylation group) hydroxy -1-§ Dammann chill meth Tari rate 15 mole ^_0/0

(a41): Torishikurodeka - Rume Tatari rate (in the general formula (11), a monomer corresponding with the structural unit in which R mosquito methyl group) 5 mole ^_0/0

[0062] [Formula 16]

(Where pZqZrZs = 40Z40Zl5Z5 (molar ratio))

[0063] Synthesis Example 1 2

Resin 1-2 having a weight average molecular weight of 6900 was obtained by the same composition and method as in Synthesis Example 1-1.

[0064] Synthesis Example 2-1

In Synthesis Example 1-1, the following monomers (al2) and (a22) were used in place of (all) and (a21), and the composition of each monomer was changed to (& 12) 7 (& 22) 7 (& 31) 7 (& 41) = 40 monoles ⁰ / oZ 35 monoles ⁰ / oZ 15 mol% Z10 mol% In the same manner as in Synthesis Example 1-1, a resin having a mass average molecular weight of 10500 represented by the following [Chemical Formula 17] 2-1 Got.

(al2): 2-Ethyl-2-adamantyl methacrylate (a monomer corresponding to a structural unit in which R is a methyl group and R ¹ is an ethyl group in the general formula (1))

(a22): Norbornane ratatone methacrylate (a monomer corresponding to a structural unit that is an R-methyl group in general formula (8))

[0065]

(Where pZqZrZs = 40Z35Zl5Zl〇 (molar ratio))

Synthesis Example 2—2

Resin 2-2 having a weight average molecular weight of 6,400 was obtained by the same composition and method as in Synthesis Example 2-1.

Synthesis Example 3-1

In Synthesis Example 2, except that the following monomer (a23) was used in place of (a22), a resin 3-1 having a mass average molecular weight of 7200 represented by the following [Chemical Formula 18] was prepared in the same manner as in Synthesis Example 2. Obtained.

(a23): Norbornane ratatone methacrylate (a monomer corresponding to a structural unit that is an R-methyl group in the general formula (9))

[0068] [Formula 18]

(Where pZqZrZs = 40Z35Zl5Zl〇 (molar ratio))

[0069] Synthesis Example 3-2

Resin 2-2 having a mass average molecular weight of 10,000 was obtained by the same composition and method as in Synthesis Example 3-1. [0070] Example 1

In 100 parts by mass of the resin 1-1 having a mass average molecular weight of 10,000 obtained in Synthesis Example 1-1, as a component (B), X in the above general formula (b-1) has 3 carbon atoms and all hydrogen atoms are A sulfonium compound in which an alkylene group substituted with a fluorine atom and R ^{1 to} R ³ are a phenyl group ([Chemical Formula 19]; hereinafter, PAG1 and! /); 3.0 mass% ^ As a component (D), 0.35 parts by weight of triethanolanolamine is dissolved in a mixture (weight ratio of 8: 2) of propylene glycol monomethyl ether acetate (PGMEA) and ethyl lactate (EL), and the solid content is adjusted. A positive resist composition having a concentration of 8% by mass was prepared.

[0071]

In the next step, an organic anti-reflective coating composition “ARC-29A” (trade name, manufactured by Pruy Science Co., Ltd.) was applied on a silicon wafer using a spinner and then heated to 215 ° C. on a hot plate. By baking for 60 seconds and drying, an organic antireflection film having a thickness of 77 nm was formed. Then, the above-mentioned positive resist composition is applied on an antireflection film using a spinner, pre-beta (PAB) at 120 ° C for 90 seconds on a hot plate, and dried to form a resist layer having a thickness of 250 nm. Was formed.

Next, an ArF exposure apparatus NSR-S302 (manufactured by -Con; NA (numerical aperture) = 0.60, σ = 0.55 According to 5), an ArF excimer laser (193 nm) was selectively irradiated through a mask pattern (binary).

Then, PEB treatment was performed at 130 ° C for 90 seconds, followed by paddle development at 23 ° C with a 2.38% by weight aqueous solution of tetramethylammonium hydroxide for 60 seconds, followed by washing with water for 20 seconds and drying. Was formed.

[0073] As a result, using the positive resist composition of Example 1, an exposure in which a 120 nm line and space mask having a 1:10 (1320 nm pitch (P)) mask was transferred to a space width of 80 nm. The quantity Eop (sensitivity) was 25 mjZcm ² .

The isolated resist pattern having a width of 80 nm formed had a round top shape, vertical resist line side walls, and a rectangular shape.

In addition, 3σ, which is a scale indicating the LER of the pattern formed above, was obtained. As a result, 3 σ of the obtained pattern was 5. Onm. The value of 3σ is the standard deviation (σ) of the standard deviation (σ) calculated by measuring the resist pattern width of the sample at 32 locations using a side length SEM (trade name “S-9220” manufactured by Hitachi, Ltd.). Double value (3σ). This 3σ means that the smaller the value, the smaller the roughness and the more uniform the width of the resist pattern.

The depth of focus (DOF) was 450 nm.

Further, at the above-mentioned exposure dose Eop, the line and space separation resolution was 240 nm pitch when the exposure was performed while gradually decreasing the pitch of the mask. The smaller the value S of the separation resolution, the better the performance as a resist composition. This evaluation method is frequently and frequently used by those skilled in the art.

Examples 2 to 18 and Comparative Examples 1 to 5

A positive resist composition was prepared in the same manner as in Example 1 except that the type of the component (A) and the type and the amount (parts by mass) of the component (B) were changed as shown in Table 1.

In Examples 9-112 and Comparative Example 3, the temperature of PAB in Example 1 was changed to 105 ° C, and the temperature of PEB was changed to 95 ° C. In Examples 13-18 and Comparative Examples 415, the temperature of PAB in Example 1 was changed to 125 ° C, and the temperature of PEB was changed to 115 ° C.

[Table 1]

[0077] In Table 1, PAG2 is a compound represented by the following [Chemical Formula 20], PAG3 is a compound represented by the following [Chemical Formula 21], and PAG4 is a compound represented by the following [Chemical Formula 22]. is there.

[0078] [Formula 20]

[0079] [Formula 21]

[0080]

The positive resist compositions prepared in Examples 2-18 and Comparative Examples 15 were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

In Table 1, “Round” refers to the area near the resist film surface on the side wall of the resist. This indicates that the top shape is rounded and the shape of the space portion is tapered. As is clear from the above results, the positive resist composition of Example 118 had a high resolution of the isolated space pattern and the L & S pattern. Furthermore, it was found that the shape of the formed pattern was good, the LER was small, and the DOF was large. Among them, the positive resist compositions of Examples 13-18 using Resin 3 were particularly excellent in LER.

The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments. Additions, omissions, substitutions, and other modifications of the configuration can be made without departing from the spirit of the present invention. The present invention is not limited by the above description, but is limited only by the scope of the appended claims.

Claims

Claims [1] A positive resist composition comprising (A) a resin component whose alkali solubility is increased by the action of an acid, and (B) an acid generator component which generates an acid upon exposure. The fat component (A) contains a monocyclic or polycyclic group-containing acid dissociable, dissolution inhibiting group and contains a (meth) acrylate derived structural unit (al) and a rataton-containing monocyclic or polycyclic group. (A) a structural unit derived from a (meth) acrylic acid ester, (a3) a structural unit derived from a (meth) acrylic acid ester containing a hydroxyl group-containing polycyclic group, and (a2), (a3) ) Other than a polycyclic group-containing non-acid dissociable, dissolution inhibiting group, a (meth) acrylic acid ester is a copolymer containing a structural unit (a4) which is also derived, wherein the acid generator component (B) is At least one sulfo-dum compound represented by the following general formula (b-1) or (b-2) The positive resist composition characterized in that it contains.

[Chemical 1]

In the formula, X represents an alkylene group having 2 to 6 carbon atoms in which at least one hydrogen atom has been replaced by a fluorine atom; Υ and Ζ each independently represent at least one hydrogen atom having been replaced by a fluorine atom. R ^{1 to} R ³ each independently represent an aryl group or an alkyl group; and at least one of R ^{1 to} R ³ represents an aryl group.

[2] The structural unit (al) has the following general formula (1), (2) or (3)

[Chemical 2]

[Formula 3]

(In the formula, R is a hydrogen atom or a lower alkyl group, and R ² and IT are each independently a lower alkyl group.)

[Formula 4]

(Wherein, R represents a hydrogen atom or a lower alkyl group, R ⁴ is a is a tertiary alkyl group) The positive resist composition according to claim 1, wherein at least one of structural units represented by.

[3] The positive electrode according to claim 2, wherein the structural unit (al) is a structural unit represented by the general formula (1), and R ¹ in the general formula (1) is a methyl group or an ethyl group. -Type resist composition.

[4] The poly-type resist composition according to claim 1, wherein the structural unit (a2) is a structural unit derived from a (meth) acrylate ester containing a rataton-containing monocycloalkyl group or a bicycloalkyl group.

5. The positive resist composition according to claim 4, wherein the structural unit (a2) is a structural unit derived from the (meth) acrylate ester force of γ-petit mouth ratataton.

6. The positive resist composition according to claim 4, wherein the structural unit (a2) is a structural unit that also induces the (meth) acrylate ester power of norbornane ratatone.

[7] The structural unit (a2) is represented by the following general formula (9)

[Formula 5]

7. The positive resist composition according to claim 6, which is a structural unit represented by the formula: wherein R is a hydrogen atom or a lower alkyl group.

8. The positive resist composition according to claim 1, wherein the structural unit (a3) is a structural unit derived from ester (meth) acrylate containing a hydroxyl group-containing adamantyl group.

[9] The structural unit (a3) is represented by the following general formula (4)

[Formula 6]

Wherein R is a hydrogen atom or a lower alkyl group. Item 10. The positive resist composition according to Item 8,

[10] The structural unit (a4) is a structural unit derived from at least one force selected from the group consisting of tricyclodecal (meth) atalylate, adamantyl (meth) atalylate, and tetracyclodode phenol (meth) acrylate. The positive resist composition according to claim 1.

[11] The positive resist yarn composition according to claim 10, wherein the structural unit (a4) is a structural unit represented by the following general formula (11).

[Formula 7]

In the formula, R is a hydrogen atom or a lower alkyl group.

12. The positive resist composition according to claim 1, wherein the resin component (A) has a mass average molecular weight of 7,500 or less.

[13] The ratio of each structural unit (al) — (a4) in the resin component (A) is in the range of the structural unit (al) power S25—50 mol%, and the structural unit (a2) is 25— 2. The positive resist composition according to claim 1, wherein the content is in the range of 50 mol%, the constitutional unit (a3) is in the range of 10 to 30 mol%, and the constitutional unit (a4) is in the range of 3 to 25 mol%. object.

[14] The above-mentioned acid generator component (B) further comprises a oxalate-based acid generator having a linear fluoroalkylsulfonate ion having 117 carbon atoms as an ion. 2. The positive resist composition according to 1.

[15] The positive resist composition according to claim 1, further comprising a nitrogen-containing organic compound.

[16] A resist film is formed on a substrate using the positive resist composition according to claim 1, and the resist film is selectively exposed to light, and then subjected to alkali development. A method for forming a resist pattern, comprising: forming a first pattern.

[17] A resist pattern formed by the method according to claim 16.