JP4558475B2 - Positive resist composition and resist pattern forming method - Google Patents

Description

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

In the photolithography technique, for example, a resist film made of a resist composition is formed on a substrate, and the resist film is irradiated with radiation such as light or an electron beam through a photomask in which a predetermined pattern is formed. A step of forming a resist pattern having a predetermined shape on the resist film is performed by performing selective exposure and developing. A resist composition in which the exposed portion changes to a property that dissolves in the developer is referred to as a positive type, and a resist composition that changes to a property in which the exposed portion does not dissolve in the developer is referred to as a negative type.
In recent years, in the manufacture of semiconductor elements and liquid crystal display elements, miniaturization has rapidly progressed due to advances in lithography technology. As a means for miniaturization, the wavelength of exposure light is generally shortened. Specifically, conventionally, ultraviolet rays typified by g-line and i-line have been used, but now KrF is used. Excimer laser (248 nm) has been introduced, and ArF excimer laser (193 nm) has begun to be introduced. In addition, studies have been conducted on shorter wavelength F ₂ excimer lasers (157 nm), EUV (extreme ultraviolet rays), electron beams, X-rays, and the like. The exposure with an electron beam or EUV is usually performed by exposure through a desired mask pattern or direct drawing in a vacuum.

Further, in order to reproduce a pattern with a fine dimension, a resist material having high resolution is required. As such a resist material, a chemically amplified resist composition containing a base resin and an acid generator that generates an acid upon exposure is used. For example, a positive chemically amplified resist contains a resin component whose alkali solubility is increased by the action of an acid and an acid generator component that generates an acid upon exposure. When acid is generated from the above, the exposed part becomes alkali-soluble.
As a resin component of a positive resist composition, a resin in which a part of hydroxyl groups of a polyhydroxystyrene resin is generally protected with an acid dissociable, dissolution inhibiting group, or a part of carboxy groups in an acrylic resin is acid dissociated. Resins protected with a soluble dissolution inhibiting group are used. Examples of the acid dissociable, dissolution inhibiting group include so-called acetal groups such as chain ether groups typified by 1-ethoxyethyl groups or cyclic ether groups typified by tetrahydropyranyl groups, and tert-butyl groups. Tertiary alkyl groups, tertiary alkoxycarbonyl groups represented by tert-butoxycarbonyl groups, and the like are mainly used (see, for example, Patent Document 1).

On the other hand, as a photomask used for pattern formation, a mask provided with a transparent substrate and a shielding layer formed in a predetermined pattern thereon is used.
In the production of such a photomask, a resist composition is used in the same manner as described above, and is usually produced as follows. That is, a shielding substrate material provided with a shielding layer (chromium oxide layer) containing chromium oxide as a main component on a transparent substrate (glass substrate) is prepared, and a resist film is formed on the chromium oxide layer. Then, the resist film is selectively exposed through a photomask-forming resist and developed to form a resist pattern on the chromium oxide layer. Next, using the resist pattern as a mask, a portion of the chromium oxide layer where the pattern is not formed is etched to transfer the pattern to the chromium oxide layer, whereby the chromium oxide having a predetermined pattern on the glass substrate. A photomask provided with a layer is obtained (see, for example, Non-Patent Document 1).
In the production of a photomask, exposure is mainly performed by direct drawing of an electron beam because a fine pattern can be formed.
JP 2002-341538 A Isao Tanabe et al., “The story of photomask technology”, Industrial Research Co., Ltd., first edition, August 20, 1996, p. 10-19

  However, when the resist material as described above is used, the target pattern can be obtained on the same substrate surface even under the same drawing conditions, particularly when drawing in a vacuum, for example, direct drawing of an electron beam. There is a problem that the difference between the dimension and the pattern dimension to be formed is large and the dimensional controllability is poor. Dimension controllability is an important characteristic in the manufacture of photomasks, and the influence on the performance of the photomask increases as the pattern size becomes finer. Particularly, it is very important in the manufacture of photomasks after the 65 nm node. .

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a positive resist composition and a resist pattern forming method excellent in dimensional controllability.

The first aspect of the present invention that solves the above-mentioned problems includes an alkali-soluble structural unit (a1) and a structural unit (a2) having an acid dissociable, dissolution inhibiting group, and increases alkali solubility by the action of an acid. A positive resist composition containing a resin component (A) to be generated and an acid generator component (B) that generates an acid upon exposure,
In the resin component (A), the structural unit (a1) has a structural unit (a11) derived from (α-methyl) hydroxystyrene, and the structural unit (a2) has the following general formula (II):

［式中、Ｘは脂肪族環式基、芳香族環式炭化水素基または炭素数１〜５のアルキル基を表し、Ｒ^１は炭素数１〜５のアルキル基を表し、もしくはＸおよびＲ^１がそれぞれ独立に炭素数１〜５のアルキレン基であってＸの末端とＲ^１の末端とが結合していてもよく、Ｒ^２は炭素数１〜５のアルキル基または水素原子を表す。］
で表される酸解離性溶解抑制基（ＩＩ）および／または鎖状第３級アルコキシカルボニル基、鎖状第３級アルキル基、および鎖状第３級アルコキシカルボニルアルキル基からなる群から選択される少なくとも１種の酸解離性溶解抑制基（ＩＩＩ）を有し、かつ
下記一般式（ｃ−１）で表される芳香族アミン（Ｃ）を含有することを特徴とするポジ型レジスト組成物である。

［式中、Ｒ ^１１ 〜Ｒ ^１３ はそれぞれ独立に芳香族炭化水素基を表す。］

[Wherein, X represents an aliphatic cyclic group, an aromatic cyclic hydrocarbon group, or an alkyl group having 1 to 5 carbon atoms, R ¹ represents an alkyl group having 1 to 5 carbon atoms, or X and R ¹ Each independently represents an alkylene group having 1 to 5 carbon atoms, and the end of X and the end of R ¹ may be bonded to each other, and R ² represents an alkyl group having 1 to 5 carbon atoms or a hydrogen atom. ]
Selected from the group consisting of an acid dissociable, dissolution inhibiting group (II) and / or a chain tertiary alkoxycarbonyl group, a chain tertiary alkyl group, and a chain tertiary alkoxycarbonylalkyl group Having at least one acid dissociable, dissolution inhibiting group (III), and
A positive resist composition comprising an aromatic amine (C) represented by the following general formula (c-1) .

[Wherein, R ^{11 to} R ¹³ each independently represents an aromatic hydrocarbon group. ]

  Further, the second aspect of the present invention includes a step of forming a resist film on a substrate using the positive resist composition of the first aspect, a step of selectively exposing the resist film, and an alkali treatment of the resist film. A resist pattern forming method including a step of forming a resist pattern by development.

In the present specification and claims, the “constituent unit” means a monomer unit constituting the polymer.
“Exposure” is a concept that includes general irradiation of radiation, and includes irradiation of an electron beam.

  According to the present invention, a positive resist composition and a resist pattern forming method excellent in dimensional controllability can be provided.

<Positive resist composition>
The positive resist composition of the present invention comprises an alkali-soluble constituent unit (a1) and a constituent unit (a2) having an acid dissociable, dissolution inhibiting group, and a resin component (in which alkali solubility is increased by the action of an acid ( A) (hereinafter also referred to as component (A)) and an acid generator component (B) that generates acid upon exposure (hereinafter also referred to as component (B)).
In the component (A), when an acid generated from the component (B) acts upon exposure, the acid dissociable, dissolution inhibiting group is dissociated, thereby changing the entire component (A) from alkali-insoluble to alkali-soluble.
Therefore, when the resist pattern is selectively exposed or drawn with or without a mask pattern, or when post-exposure heating (PEB) is performed in addition to exposure or drawing, the exposed portion turns into alkali-soluble. Since the unexposed portion remains insoluble in alkali and does not change, a positive resist pattern can be formed by alkali development.

[(A) component]
・ Structural unit (a1)
In the component (A), the alkali-soluble structural unit (a1) is a polar group such as a hydroxyl group or a carboxy group in the structural unit, and the monomer for deriving the structural unit becomes an alkali such as an alkali developer. A structural unit that is soluble.
In the present invention, the structural unit (a1) needs to have the following structural unit (a11). The combination of the structural unit (a11) and the structural unit (a2) having the acid dissociable, dissolution inhibiting groups (II) and (III) described later improves dimensional controllability. Moreover, dry etching tolerance improves by having a structural unit (a11). Further, (α-methyl) hydroxystyrene as a raw material has advantages such as being readily available and being inexpensive.

The structural unit (a11) is a structural unit derived from (α-methyl) hydroxystyrene.
Here, (α-methyl) hydroxystyrene means one or both of hydroxystyrene and α-methylhydroxystyrene. “Α-methylhydroxystyrene” means a hydrogen atom bonded to an α carbon atom of hydroxystyrene substituted with a methyl group. The “structural unit derived from (α-methyl) styrene” means a structural unit formed by cleavage of an ethylenic double bond of (α-methyl) styrene.
Examples of the structural unit (a11) include structural units represented by the following general formula (I).

［式中、Ｒは水素原子又はメチル基であり、ｍは１〜３の整数である。］

[In formula, R is a hydrogen atom or a methyl group, and m is an integer of 1-3. ]

In general formula (I), R is a hydrogen atom or a methyl group, and is preferably a hydrogen atom.
m is an integer of 1 to 3, and preferably 1.
When m is 1, the position of the hydroxyl group may be any of the o-position, m-position, and p-position, but the p-position is preferred because it is readily available and inexpensive. Furthermore, when m is 2 or 3, arbitrary substitution positions can be combined.

In the present invention, the structural unit (a1) preferably further has a structural unit (a12) derived from an (α-lower alkyl) acrylate ester having an alcoholic hydroxyl group.
Such a structural unit (a12) has lower solubility in an alkaline developer than the structural unit (a11). Therefore, when the component (A) has the structural unit (a12), the component (A) in a state where the acid dissociable, dissolution inhibiting group is dissociated is more than when the structural unit (a1) has only the structural unit (a11). Has low solubility in an alkaline developer. For this reason, sufficient insolubility with respect to an alkaline developer is obtained even if the proportion of the structural unit (a2) having an acid dissociable, dissolution inhibiting group is smaller than when the structural unit (a1) has only the structural unit (a11). And film loss after development can be reduced.
Therefore, the structural unit (a12) is not limited as long as it has such an action, as long as it is a structural unit derived from an (α-lower alkyl) acrylate ester having an alcoholic hydroxyl group.

  Here, “(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. 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.

  The lower alkyl group bonded to the α carbon atom of the α-lower alkyl acrylate ester is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group, or an isopropyl group. , N-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group and the like. Industrially, a methyl group is preferable.

The structural unit (a12) is preferably a structural unit derived from an aliphatic polycyclic group-containing (α-lower alkyl) acrylate ester having an alcoholic hydroxyl group. Since such a structural unit contains an aliphatic polycyclic group, improvement in etching resistance and reduction in film loss after etching are expected. Also, the resolution is excellent. “Aliphatic” means a group, compound, or the like that does not have aromaticity, as will be described later.
Examples of the polycyclic group constituting the aliphatic polycyclic group having an alcoholic hydroxyl group include groups in which one hydrogen atom has been removed from bicycloalkane, tricycloalkane, tetracycloalkane, and the like. Specific examples include groups in which one hydrogen atom has 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 ArF resists and the like. Of these, an adamantyl group, a norbornyl group, and a tetracyclododecanyl group are industrially preferable.

The structural unit (a12) is particularly preferably a structural unit derived from an adamantyl group-containing (α-lower alkyl) acrylate ester having an alcoholic hydroxyl group, as represented by the following general formula (IV).
As the structural unit represented by the general formula (IV), the structural unit represented by the following general formula (IVa) is most preferable.

［式中、Ｒは水素原子又は低級アルキル基であり、ｘは１〜３の整数である。］

[Wherein, R is a hydrogen atom or a lower alkyl group, and x is an integer of 1 to 3. ]

  In the present invention, the structural unit (a1) may have a structural unit other than the structural unit (a11) and the structural unit (a12). Examples of the structural unit include a structural unit derived from (meth) acrylic acid. “(Meth) acrylic acid” means one or both of methacrylic acid and acrylic acid. Further, the “structural unit derived from (meth) acrylic acid” means a structural unit constituted by cleavage of an ethylenic double bond of (meth) acrylic acid.

  In the component (A), the proportion of the structural unit (a1) is preferably 50 to 95 mol%, more preferably 60 to 85 mol% with respect to all the structural units constituting the component (A). 65 to 80 mol% is most preferable. Thereby, moderate alkali solubility is obtained.

・ Structural unit (a2)
The structural unit (a2) is a structural unit having an acid dissociable, dissolution inhibiting group.
In the present invention, it is necessary to have an acid dissociable, dissolution inhibiting group (II) and / or an acid dissociable, dissolution inhibiting group (III) as the acid dissociable, dissolution inhibiting group. The structural unit (a2) only needs to have at least one of an acid dissociable, dissolution inhibiting group (II) and an acid dissociable, dissolution inhibiting group (III). Preferably has a dissociable dissolution inhibiting group (II), and having both a dissociable dissolution inhibiting group (II) and an acid dissociable dissolution inhibiting group (III) is stable in PED (Post Exposure Delay) in a vacuum. It is more preferable because of its superiority.

The acid dissociable, dissolution inhibiting group (II) is a group represented by the above general formula (II).
In formula (II), X represents an aliphatic cyclic group, an aromatic cyclic hydrocarbon group, or an alkyl group having 1 to 5 carbon atoms.
Here, “aliphatic” is a relative concept with respect to aromatics, and is defined to mean groups, compounds, and the like that do not have aromaticity. “Aliphatic cyclic group” means a monocyclic group or a polycyclic group having no aromaticity. In this case, “aliphatic cyclic group” means a group consisting of carbon and hydrogen (carbonized). Although it is not limited to being a hydrogen group, it is preferably a hydrocarbon group. The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated. A polycyclic group is preferred.
Such an aliphatic cyclic group can be used, for example, by appropriately selecting from a large number of proposals in conventional ArF resists. Specific examples of the aliphatic cyclic group include an aliphatic monocyclic group having 5 to 7 carbon atoms and an aliphatic polycyclic group having 10 to 16 carbon atoms. Examples of the aliphatic monocyclic group having 5 to 7 carbon atoms include groups in which one hydrogen atom has been removed from a monocycloalkane. Specifically, one hydrogen atom has been removed from cyclopentane, cyclohexane and the like. Group. Examples of the aliphatic polycyclic group having 10 to 16 carbon atoms include groups in which one hydrogen atom has been removed from bicycloalkane, tricycloalkane, tetracycloalkane and the like. Specifically, adamantane, norbornane, Examples include groups in which one hydrogen atom has been removed from a polycycloalkane such as isobornane, tricyclodecane, and tetracyclododecane. Among these, an adamantyl group, a norbornyl group, and a tetracyclododecanyl group are industrially preferable, and an adamantyl group is particularly preferable.
Examples of the aromatic cyclic hydrocarbon group for X include aromatic polycyclic groups having 10 to 16 carbon atoms. Specific examples include groups in which one hydrogen atom has been removed from naphthalene, anthracene, phenanthrene, pyrene, and the like. Specific examples include 1-naphthyl group, 2-naphthyl group, 1-anthracenyl group, 2-anthracenyl group, 1-phenanthryl group, 2-phenanthryl group, 3-phenanthryl group, 1-pyrenyl group, and the like. A naphthyl group is particularly preferred industrially.
The alkyl group of X may be linear or branched. Specific examples include 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. Industrially, a methyl group or an ethyl group is preferable, and a methyl group is particularly preferable.
X is preferably an aliphatic polycyclic group. When X is an aliphatic polycyclic group, the line edge roughness of the resist pattern and the rectangular shape of the cross-sectional shape are improved. Moreover, etching resistance is also improved.
Moreover, when a structural unit (a2) contains the structural unit (a22) mentioned later, it is preferable that X is a C1-C5 alkyl group at the point of the ease of a synthesis | combination.

In the formula (II), R ¹ represents an alkyl group having 1 to 5 carbon atoms, and may be linear or branched. Specific examples include 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. Industrially, a methyl group or an ethyl group is preferable, and a methyl group is particularly preferable.
R ² represents an alkyl group having 1 to 5 carbon atoms or a hydrogen atom. Examples of the alkyl group include those similar to the alkyl group for R ¹ . R ² is preferably a hydrogen atom industrially.

In Formula (II), X and R ¹ may each independently be an alkylene group having 1 to 5 carbon atoms, and the end of X and the end of R ¹ may be bonded.
In this case, in the formula (II), a cyclic group is formed by R ¹ , X, the oxygen atom to which X is bonded, and the carbon atom to which the oxygen atom and R ¹ are bonded. The cyclic group is preferably a 4-7 membered ring, and more preferably a 4-6 membered ring. Specific examples of the cyclic group include a tetrahydropyranyl group and a tetrahydrofuranyl group.

  As the acid dissociable, dissolution inhibiting group (II), in particular, the acid dissociable, dissolution inhibiting group represented by the following general formula (II-1) is excellent in the effect of the present invention and is preferable.

［式中、Ｙは脂肪族環式基、芳香族環式炭化水素基、または炭素数１〜５のアルキル基を表し、Ｒ^１は炭素数１〜５のアルキル基を表す。］

[Wherein, Y represents an aliphatic cyclic group, an aromatic cyclic hydrocarbon group, or an alkyl group having 1 to 5 carbon atoms, and R ¹ represents an alkyl group having 1 to 5 carbon atoms. ]

Alkyl group of 1 to 5 carbon atoms for R ¹ is the same as ^{R 1} in the general formula (II).
In addition, as the aliphatic cyclic group, aromatic cyclic hydrocarbon group or alkyl group having 1 to 5 carbon atoms of Y, the aliphatic cyclic group or aromatic cyclic hydrocarbon of X in the above general formula (II) The same as the group or the alkyl group having 1 to 5 carbon atoms.

Specific examples of the acid dissociable, dissolution inhibiting group represented by formula (II-1) include, for example, when Y is a group that is an alkyl group, that is, a 1-alkoxyalkyl group, a 1-methoxyethyl group, 1- Ethoxyethyl group, 1-iso-propoxyethyl group, 1-n-butoxyethyl group, 1-tert-butoxyethyl group, methoxymethyl group, ethoxymethyl group, iso-propoxymethyl group, n-butoxymethyl group, tert- Examples include butoxymethyl group. Examples of the group in which Y is an aliphatic cyclic group include 1-cyclohexyloxyethyl group, 1- (2-adamantyl) oxymethyl group, and 1- (1-adamantyl) represented by the following formula (II-a). ) An oxyethyl group. Examples of the group in which Y is an aromatic cyclic hydrocarbon group include a 1- (2-naphthyl) oxyethyl group represented by the following formula (II-b).
Among these, a 1-ethoxyethyl group or a 1- (1-adamantyl) oxyethyl group is particularly preferable.

The acid dissociable, dissolution inhibiting group (III) is at least one selected from the group consisting of a chain tertiary alkoxycarbonyl group, a chain tertiary alkyl group, and a chain tertiary alkoxycarbonylalkyl group. .
The chain tertiary alkoxy group and / or chain tertiary alkyl group contained in the acid dissociable, dissolution inhibiting group (III) preferably has 4 to 10 carbon atoms, and more preferably 4 to 8 carbon atoms. Moreover, as the total carbon number of acid dissociable, dissolution inhibiting group (III), 4-10 are preferable and 4-8 are more preferable.
Examples of the chain tertiary alkoxycarbonyl group include a tert-butoxycarbonyl group and a tert-amyloxycarbonyl group.
Examples of the chain tertiary alkyl group include a tert-butyl group and a tert-amyl group.
Examples of the chain-like tertiary alkoxycarbonylalkyl group include a tert-butoxycarbonylmethyl group and a tert-amyloxycarbonylmethyl group.
Among these, a chain-like tertiary alkoxycarbonyl group is preferable, and among them, a tert-butoxycarbonyl group is most preferable because the resist pattern shape is good.

Moreover, the structural unit (a2) may have a structural unit having an acid dissociable, dissolution inhibiting group other than the acid dissociable, dissolution inhibiting groups (II) and (III) as necessary.
As acid dissociable, dissolution inhibiting groups other than acid dissociable, dissolution inhibiting groups (II) and (III), conventionally known acid dissociable, dissolution inhibiting groups can be used. As the conventionally known acid dissociable dissolution inhibiting groups, those proposed as acid dissociable dissolution inhibiting groups in chemically amplified KrF positive resist compositions and ArF positive resist compositions may be appropriately used. On the ring, such as 1-methylcyclopentyl group, 1-ethylcyclopentyl group, 1-methylcyclohexyl group, 1-ethylcyclohexyl group, 2-methyl-2-adamantyl group, 2-ethyl-2-adamantyl group, etc. And monocyclic or polycyclic aliphatic hydrocarbon groups containing a tertiary carbon atom.

  Examples of the structural unit (a2) include the structural unit (a21) in which the hydrogen atom of the hydroxyl group of the structural unit (a11) is substituted with an acid dissociable, dissolution inhibiting group, and the alcoholic hydroxyl group of the structural unit (a12). Structural unit (a22) in which a hydrogen atom is substituted with an acid dissociable, dissolution inhibiting group, and a structural unit in which a hydrogen atom of a carboxy group in a structural unit derived from (meth) acrylic acid is substituted with an acid dissociable, dissolution inhibiting group Examples include units. Among these, it is preferable to have the structural unit (a21) and / or the structural unit (a22).

  In the component (A), the proportion of the structural unit (a2) is preferably from 5 to 45 mol%, more preferably from 10 to 45 mol%, based on all the structural units constituting the component (A). 40 mol% is more preferable, and it is most preferable that it is 20-35 mol%. Thereby, it is possible to sufficiently ensure alkali insolubility in the unexposed portion of the resist film when forming the resist pattern.

  In addition, in the component (A), the total of the structural unit (a11) and the structural unit (a21) (hydroxystyrene-based structural unit) and the total of the structural unit (a12) and the structural unit (a22) ((α-lower alkyl) The ratio (molar ratio) to (acrylic ester-based structural unit) is preferably in the range of 9: 1 to 1: 9, more preferably 8: 2 to 2: 8, and 8: 2 to 5 : 5 is most preferable. By being within the above range, sufficient solubility in a developer can be secured.

In addition to the structural units (a1) and (a2), the component (A) may further have a structural unit (a3) derived from (α-methyl) styrene.
In the present invention, the structural unit (a3) is not essential, but if it is contained, advantages such as an improved depth of focus and improved dry etching resistance can be obtained.

  Here, “(α-methyl) styrene” means one or both of styrene and α-methylstyrene. “Α-methylstyrene” means that a hydrogen atom bonded to the α carbon atom of styrene is substituted with a methyl group. The “structural unit derived from (α-methyl) styrene” means a structural unit formed by cleavage of an ethylenic double bond of (α-methyl) styrene. In (α-methyl) styrene, the hydrogen atom of the phenyl group may be substituted with a substituent such as an alkyl group having 1 to 5 carbon atoms.

  Examples of the structural unit (a3) include structural units represented by the following general formula (III).

［式中、Ｒは水素原子またはメチル基を表し、Ｒ^３は炭素数１〜５のアルキル基を表し、ｎは０または１〜３の整数を表す。］

[Wherein, R represents a hydrogen atom or a methyl group, R ³ represents an alkyl group having 1 to 5 carbon atoms, and n represents an integer of 0 or 1 to 3. ]

In Formula (III), R ³ is a linear or branched alkyl group having 1 to 5 carbon atoms, and is a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, or a tert-butyl group. , A pentyl group, an isopentyl group, a neopentyl group, and the like. Industrially, a methyl group or an ethyl group is preferable.
n is 0 or an integer of 1 to 3. Of these, n is preferably 0 or 1, and is particularly preferably 0 industrially.
In addition, when n is 1 to ³ , the substitution position of R ³ may be any of the o-position, m-position and p-position, and when n is 2 or 3, any substitution The positions can be combined.

  When the component (A) has the structural unit (a3), the proportion of the structural unit (a3) is preferably 0.5 to 25 mol%, preferably 3 to 20 mol, based on all the structural units constituting the component (A). If the structural unit (a3) in which% is more preferable is more than the above range, the solubility in the developer tends to deteriorate.

The weight average molecular weight of component (A) (polystyrene conversion by gel permeation chromatography (GPC), the same shall apply hereinafter) is preferably from 3500 to 33000, more preferably from 5500 to 23000.
In particular, the mass average molecular weight in a state where all the acid dissociable, dissolution inhibiting groups are dissociated is preferably 2000 to 30000, and more preferably 4000 to 20000. By making the mass average molecular weight in the state where all of the acid dissociable, dissolution inhibiting groups are dissociated to 30000 or less, sufficient solubility in a resist solvent can be secured, and by making it 2000 or more, the dry etching resistance of the resulting resist pattern can be ensured. Improves film loss. Further, within the above range, the film loss after etching is reduced as the mass average molecular weight is larger.
Further, the smaller the degree of dispersion (Mw / Mn (number average molecular weight)) of the component (A), the better the resolution, and the better. The dispersity is preferably 2.0 or less, and more preferably 1.7 or less.

In the present invention, the component (A) is a copolymer (hereinafter referred to as the structural unit (a11), the structural unit (a12), the structural unit (a21) and / or the structural unit (a22). And a copolymer (A-1)). Thereby, good resolution is obtained and development defects are reduced. Also, a good depth of focus can be obtained.
The copolymer (A-1) may further have the structural unit (a3).

For example, the copolymer (A-1) is obtained by polymerizing a monomer corresponding to the structural unit (a11) and a monomer corresponding to the structural unit (a12), and then hydroxyl groups of the structural unit (a11) and the structural unit (a12). Can be produced by a method of substituting a part of the hydrogen atoms with an acid dissociable, dissolution inhibiting group into a structural unit (a21) and / or a structural unit (a22) by a known method.
Alternatively, a monomer corresponding to the structural unit (a21) and a monomer corresponding to the structural unit (a22) are prepared, and after these monomers are polymerized by a conventional method, the acid dissociable, dissolution inhibiting group is dissociated by hydrolysis. To the structural unit (a11) and the structural unit (a12), and if necessary, the hydrogen atom of the hydroxyl group of the structural unit (a11) and / or the structural unit (a12) may be replaced with an acid dissociable, dissolution inhibiting group by a known method. It can also be produced by a method of substituting the structural unit (a21) and / or the structural unit (a22).

  In the present invention, in particular, the component (A) has the structural unit (a1) and the structural unit (a2), and the acid dissociable dissolution inhibiting group (II) is used as the acid dissociable dissolution inhibiting group. A polymer (A1) having the acid dissociable, dissolution inhibiting group (III), the structural unit (a1) and the structural unit (a2), and having an acid dissociable, dissolution inhibiting group It is preferable to contain the polymer (A2) having the acid dissociable, dissolution inhibiting group (III) and not having the acid dissociable, dissolution inhibiting group (II). By using such a mixture as the component (A), it is possible to obtain an excellent pattern having a rectangular shape with a good resist pattern shape. In addition, it is easier to contain the acid dissociable, dissolution inhibiting group (II) and the acid dissociable, dissolution inhibiting group (III) in different polymers and use them as a mixed resin, than in the same polymer. Can be prepared.

In the present invention, it is particularly preferable that the polymer (A1) is the following polymer (A11) and the polymer (A2) is the following polymer (A21). Moreover, it is preferable that a polymer (A1) is the following polymer (A12), and a polymer (A2) is the following polymer (A21).
Polymer (A11): Polymer having the structural unit (a11) and the structural unit (a21) and not having the structural unit (a12) and the structural unit (a22) (however, acid dissociable dissolution) Having inhibitory group (II) and no acid dissociable, dissolution inhibiting group (III))
Polymer (A12): Polymer having structural unit (a11), structural unit (a12), structural unit (a21) and / or structural unit (a22) (however, acid dissociable dissolution inhibition) Having the group (II) and not having the acid dissociable, dissolution inhibiting group (III))
Polymer (A21): Polymer having the structural unit (a11) and the structural unit (a21) and not having the structural unit (a12) and the structural unit (a22) (however, acid dissociable dissolution) Having inhibitory group (III) and not having acid dissociable, dissolution inhibiting group (II))

  In the polymer (A11), the structural unit (a11) may be the same as the structural unit (a21) in a state where the acid dissociable, dissolution inhibiting group is dissociated, that is, in a state where the acid dissociable, dissolution inhibiting group is substituted with a hydrogen atom. May be different. For example, the groups bonded to the α-position carbon atom of hydroxystyrene may be the same (both are hydrogen atoms or methyl groups) or may be different (one is a hydrogen atom and the other is a methyl group). In terms of alkali solubility control, both are preferably hydrogen atoms.

In the polymer (A11), the content ratio of the structural unit (a11) is based on the total of all the structural units constituting the polymer (A11) in terms of resolution, balance with the structural unit (a21), and the like. 50 to 95 mol% is preferable, 55 to 85 mol% is more preferable, and 55 to 75 mol% is more preferable.
The content of the structural unit (a21) is preferably 5 to 50 mol%, more preferably 10 to 45 mol%, based on the total of all the structural units constituting the polymer (A11). 15 to 45 mol% is more preferable. In particular, when the polymer (A11) does not have the structural unit (a3), 20 to 45 mol% is more preferable. Moreover, when it has a structural unit (a3), 10-20 mol% is more preferable. By setting the content ratio of the structural unit (a21) to be equal to or higher than the lower limit value of the above range, good contrast can be obtained, and by setting the content ratio of the structural unit (a21) to be equal to or lower than the upper limit value of the above range, an effect of preventing development defects can be obtained. It is done.

The polymer (A11) preferably further has a structural unit (a3) in addition to the structural units (a11) and (a21). The structural unit (a3) is not essential, but if it is contained, advantages such as an improved depth of focus and further improved dry etching resistance can be obtained.
When the structural unit (a3) is included, the proportion of the structural unit (a3) in the polymer (A2) is 0.5 to 10 mol% of the total of all the structural units constituting the polymer (A2). Preferably, 2 to 5 mol% is more preferable. When the structural unit (a3) is more than the above range, the solubility in the developer tends to deteriorate.

  In the polymer (A11), the acid dissociable, dissolution inhibiting group (II) is preferably a group in which X in the formula (II) is an adamantyl group or a naphthyl group. Specific examples include a 1- (1-adamantyl) oxyethyl group represented by the above formula (II-a), a 1- (2-naphthyl) oxyethyl group represented by the above formula (II-b), and the like. .

As a polymer (A11), 1 type may be used independently and 2 or more types may be mixed and used.
In the case of using a mixture of two or more kinds as the polymer (A1), a polymer having the structural unit (a11) and the structural unit (a21) and not having the structural unit (a3), and a structural Any two or more selected from the group consisting of a polymer having the unit (a11), the structural unit (a21) and the structural unit (a3) can be combined. That is, those having different mass average molecular weights of those polymers and those having different proportions of the respective structural units can be arbitrarily mixed and used. Such a mixture includes a polymer having the structural unit (a11) and the structural unit (a21) and not having the structural unit (a3), the structural unit (a11), the structural unit (a21), and the structural unit ( and a mixture with a polymer having a3). By using such a mixture as the polymer (A1), the formed resist pattern has a good rectangular shape and an excellent isolated line can be obtained.

The mass average molecular weight of the polymer (A11) is preferably 2000 to 30000, more preferably 5000 to 20000. By setting the mass average molecular weight to 30000 or less, the solubility in a resist solvent can be improved, and by setting the mass average molecular weight to 2000 or more, the dry etching resistance of the resulting resist pattern is improved and film loss is improved. Also, a good resist pattern shape can be obtained.
Moreover, it is excellent in the resolution property that it is a monodispersion thing with a small dispersion degree (Mw / Mn ratio) of a polymer (A11), and preferable. Specifically, the dispersity is preferably 2.0 or less, and more preferably 1.7 or less.

For example, the polymer (A11) is obtained by polymerizing a monomer corresponding to the structural unit (a11), and then converting a part of the hydrogen atoms of the hydroxyl group of the structural unit (a11) to an acid dissociable, dissolution inhibiting group ( It can be produced by a method in which the structural unit (a21) is protected with an acid dissociable, dissolution inhibiting group (II).
Alternatively, a monomer corresponding to the structural unit (a21) is prepared in advance, polymerized by a conventional method, and then a part of the hydrogen atom of the hydroxyl group protected with an acid dissociable, dissolution inhibiting group is converted into a hydrogen atom by hydrolysis. It can manufacture also by the method of changing to and using as a structural unit (a11).

The polymer (A12) is a polymer having the structural unit (a11), the structural unit (a12), and at least one of the structural unit (a21) and the structural unit (a22).
The structural unit (a21) and the structural unit (a22) are not particularly limited as long as one of them is included. In particular, it is preferable to contain only the structural unit (a21) or to contain both the structural units (a21) and (a22).

When the polymer (A12) has the structural unit (a21), the structural unit (a11) and the acid dissociable, dissolution inhibiting group are dissociated in the polymer (A12), that is, the acid dissociable, dissolution inhibiting group is a hydrogen atom. The structural unit (a21) in a state substituted with may be the same as or different from the polymer (A11).
When the polymer (A12) has the structural unit (a22), the structural unit (a12) and the acid dissociable, dissolution inhibiting group are dissociated, that is, the acid dissociable, dissolution inhibiting group is replaced with a hydrogen atom. The structural unit (a22) may be the same or different. For example, the structural unit (a21) and the structural unit (a22) may be a structural unit derived from an acrylate ester or a structural unit derived from a methacrylic acid ester, and contain an alcoholic hydroxyl group. The structure of the aliphatic polycyclic group may be the same or different. In terms of alkali solubility control, both the structural unit (a12) and the structural unit (a22) are preferably structural units derived from an acrylate ester.

  In the polymer (A12), the acid dissociable, dissolution inhibiting group (II) is preferably a group in which Y in the formula (II-1) is an alkyl group, that is, a 1-alkoxyalkyl group.

  In the polymer (A12), the ratio of the total of the structural unit (a21) and the structural unit (a22) to the total of the structural unit (a11), the structural unit (a12), the structural unit (a21), and the structural unit (a22), That is, the protection ratio of the hydroxyl group in the copolymer (A-1) (ratio in which the hydrogen atom of the hydroxyl group is substituted with an acid dissociable, dissolution inhibiting group) is preferably 10 to 35 mol%, and preferably 15 to 30 More preferably, mol% is more preferable, and 20-30 mol% is further more preferable. By setting it to the upper limit of the above range or less, pattern defects (development defects) of the resist pattern after development can be effectively prevented. On the other hand, when the protection ratio of the hydroxyl group is not less than the lower limit of the above range, the etching resistance is improved and the film loss is reduced. In addition, degradation of resolution performance can be suppressed. Further, the higher the hydroxyl group protection ratio, the more the film loss after development can be reduced.

  In the polymer (A12), the total of the structural unit (a11) and the structural unit (a21) (hydroxystyrene-based structural unit) and the total of the structural unit (a12) and the structural unit (a22) ((α-lower alkyl). ) Acrylic ester-based structural unit) (molar ratio) is preferably in the range of 95: 5 to 50:50, more preferably in the range of 95: 5 to 60:40. 85:15 to 70:30. By being within the above range, sufficient solubility in a developer can be secured.

  In the polymer (A12), the total of the structural unit (a11), the structural unit (a12), the structural unit (a21) and / or the structural unit (a22) is the polymer (A12). It is preferably 90 mol% or more, more preferably 95 mol% or more, and may be 100 mol% with respect to the total of all the constituent units to be constituted. When it is 90 mol% or more, the resolution is good.

In addition to the structural unit (a11), the structural unit (a12), the structural unit (a21), and the structural unit (a22), the polymer (A12) is further composed of the structural unit (a3) in the same manner as the polymer (A1). You may have.
When the structural unit (a3) is included, the proportion of the structural unit (a3) in the polymer (A12) is 0.5 to 10 mol% of the total of all the structural units constituting the polymer (A12). Preferably, 2 to 5 mol% is more preferable. When the structural unit (a3) is more than the above range, the solubility in the developer tends to deteriorate.

The mass average molecular weight (Mw) of the polymer (A12) is preferably 5000 or more and 20000 or less, and more preferably 4500 or more and 15000 or less. The resistance to dry etching of the resist pattern from which the mass average molecular weight is obtained is improved, and the film loss is improved. Moreover, generation | occurrence | production of a microbridge can be prevented. The microbridge here is a kind of development defect, for example, a defect in a line-and-space pattern in which a portion close to the surface of an adjacent resist pattern is connected by a resist and is in a bridged state. Microbridges are more likely to occur as the mass average molecular weight is higher and the post-exposure heating (PEB) temperature is higher.
Moreover, it is excellent in the resolution property that it is a monodispersed thing with a small dispersion degree (Mw / Mn ratio) of a polymer (A12). Specifically, the dispersity is preferably 2.0 or less, and more preferably 1.7 or less.

  As a polymer (A12), 1 type may be used independently and 2 or more types may be mixed and used.

The polymer (A12) is obtained, for example, by copolymerizing a monomer corresponding to the structural unit (a11) and a monomer corresponding to the structural unit (a12), and then the structural unit (a11) and / or the structural unit (a12). It can be produced by a method in which a part of the hydrogen atom of the hydroxyl group is protected with an acid dissociable, dissolution inhibiting group by a known method to form the structural unit (a21) and / or the structural unit (a22).
Alternatively, it can be produced by preparing monomers corresponding to the structural units (a11), (a12), (a21) and (a22) and copolymerizing them by a conventional method.

  In the polymer (A21), the proportion of the structural unit (a11) is based on the total of all the structural units constituting the polymer (A21) in terms of resolution, balance with the structural unit (a21), and the like. 30 to 70 mol% is preferable, 35 to 60 mol% is more preferable, and 40 to 55 mol% is most preferable.

  Moreover, it is preferable that the ratio of a structural unit (a21) in a polymer (A21) is 30-50 mol% with respect to the sum total of all the structural units which comprise a polymer (A21), and 35-45 mol. % Is more preferable. By setting the content ratio to be equal to or higher than the lower limit of the above range, an excellent exposure amount margin can be obtained, and the resolution, in particular, the resolution of an isolated line pattern is improved. Moreover, by making it below the upper limit of said range, a balance with a structural unit (a11) becomes favorable.

The mass average molecular weight of the polymer (A21) is preferably 2000 to 30000, and more preferably 5000 to 20000.
By making the mass average molecular weight 30000 or less, solubility in a resist solvent can be improved, and by making it 2000 or more, a good resist pattern shape can be obtained.
Moreover, as a dispersion degree of a polymer (A21), it is excellent in the resolution property that it is monodispersion with a small dispersion degree, and preferable. Specifically, 2.0 or less is preferable, and 1.5 or less is more preferable.

  As the polymer (A21), one type may be used alone, or two or more types may be mixed and used.

For example, the polymer (A21) is obtained by polymerizing a monomer corresponding to the structural unit (a11), and then converting some of the hydrogen atoms of the hydroxyl group of the structural unit (a11) to an acid dissociable, dissolution inhibiting group ( It can be produced by a method in which the structural unit (a21) is protected with an acid dissociable, dissolution inhibiting group (including III).
Alternatively, a monomer corresponding to the structural unit (a21) is prepared in advance, polymerized by a conventional method, and then a part of the hydrogen atom of the hydroxyl group protected with an acid dissociable, dissolution inhibiting group is converted into a hydrogen atom by hydrolysis. It can manufacture also by the method of changing to and using as a structural unit (a11).

In the component (A), the content ratio (mass ratio) of the polymer (A1) and the polymer (A2) is preferably in the range of 10/90 to 90/10, and 20/80 to 80 / 20 is more preferable, and 20/80 to 70/30 is more preferable. By making the ratio within this range, the effect of the present invention becomes particularly excellent.
Further, the total amount of the polymer (A1) and the polymer (A2) in the component (A) is preferably 50 to 100% by mass and more preferably 70 to 100% by mass for the effect of the present invention. . Most preferably, it is 100% by mass, that is, the component (A) is preferably a mixed resin of the polymer (A1) and the polymer (A2).

  In the positive resist composition of the present invention, the content of the component (A) may be adjusted according to the resist film thickness to be formed.

  The component (B) is not particularly limited, and those that have been proposed as acid generators for chemically amplified resists 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, and poly (bissulfonyl) diazomethanes. There are various known diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators, and the like.

  Examples of the onium salt acid generator include compounds represented by the following general formula (b-1) or (b-2).

［式中、Ｒ^１”〜Ｒ^３”，Ｒ^５”〜Ｒ^６”は、それぞれ独立に、アリール基またはアルキル基を表し；Ｒ^４”は、直鎖、分岐または環状のアルキル基またはフッ素化アルキル基を表し；Ｒ^１”〜Ｒ^３”のうち少なくとも１つはアリール基を表し、Ｒ^５”〜Ｒ^６”のうち少なくとも１つはアリール基を表す。］

[Wherein R ¹ ″ to R ³ ″ and R ⁵ ″ to R ⁶ ″ each independently represents an aryl group or an alkyl group; R ⁴ ″ represents a linear, branched or cyclic alkyl group or fluorinated group. Represents an alkyl group; at least one of R ¹ ″ to R ³ ″ represents an aryl group, and at least one of R ⁵ ″ to R ⁶ ″ represents an aryl group.]

In formula (b-1), R ¹ ″ to R ³ ″ each independently represents an aryl group or an alkyl group. At least one of R ¹ ″ to R ³ ″ represents an aryl group. Of R ¹ ″ to R ³ ″, two or more are preferably aryl groups, and most preferably all R ¹ ″ to R ³ ″ are aryl groups.
The aryl group for R ¹ ″ to R ³ ″ is not particularly limited, and is, for example, an aryl group having 6 to 20 carbon atoms, in which part or all of the hydrogen atoms are alkyl groups, alkoxy groups It may or may not be substituted with a group, a halogen atom or the like. The aryl group is preferably an aryl group having 6 to 10 carbon atoms because it can be synthesized at a low cost. Specific examples include a phenyl group and a naphthyl group.
The alkyl group that may be substituted for the hydrogen atom of the aryl group is preferably an alkyl group having 1 to 5 carbon atoms, and is a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group. Is most preferred.
The alkoxy group that may be substituted for the hydrogen atom of the aryl group is preferably an alkoxy group having 1 to 5 carbon atoms, and most preferably a methoxy group or an ethoxy group.
The halogen atom that may be substituted for the hydrogen atom of the aryl group is preferably a fluorine atom.
The alkyl group for R 1 ^{"~R 3",} is not particularly limited, for example, a straight, include alkyl groups such as branched or cyclic. It is preferable that it is C1-C5 from the point which is excellent in resolution. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a nonyl group, and a decanyl group. A methyl group is preferable because it is excellent in resolution and can be synthesized at low cost.
Among these, it is most preferable that all of R ^{1 to} R ³ are phenyl groups.

R ⁴ ″ represents a linear, branched or cyclic alkyl group or a fluorinated alkyl group.
The linear alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms.
The cyclic alkyl group is a cyclic group as indicated by R ¹ ″ and preferably has 4 to 15 carbon atoms, more preferably 4 to 10 carbon atoms, and more preferably 6 carbon atoms. Most preferably, it is -10.
The fluorinated alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms. Also. The fluorination rate of the fluorinated alkyl group (ratio of fluorine atoms in the alkyl group) is preferably 10 to 100%, more preferably 50 to 100%, and particularly those in which all hydrogen atoms are substituted with fluorine atoms. Since the strength of the acid is increased, it is preferable.
R ⁴ ″ is most preferably a linear or cyclic alkyl group or a fluorinated alkyl group.

In formula (b-2), R ⁵ ″ to R ⁶ ″ each independently represents an aryl group or an alkyl group. At least one of R ⁵ ″ to R ⁶ ″ represents an aryl group. Of R ⁵ ″ to R ⁶ ″, two or more are preferably aryl groups, and all of R ⁵ ″ to R ⁶ ″ are most preferably aryl groups.
As the aryl group for R ⁵ ″ to R ⁶ ″, the same as the aryl groups for R ¹ ″ to R ³ ″ can be used.
Examples of the alkyl group for R ⁵ ″ to R ⁶ ″ include the same as the alkyl group for R ¹ ″ to R ³ ″.
Among these, it is most preferable that all of R ⁵ ″ to R ⁶ ″ are phenyl groups.
"As ^{R 4} in the formula (b-1)" ^{R 4} in the In the formula (b-2) include the same as.

  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 E) phenylsulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or nonafluorobutanesulfonate, diphenyl (1- (6-methoxy) naphthyl) sulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or nonafluorobutanesulfonate Is mentioned. In addition, onium salts in which the anion portion of these onium salts is replaced with methanesulfonate, n-propanesulfonate, n-butanesulfonate, or n-octanesulfonate can also be used.

  Moreover, what replaced the anion part by the anion part represented by the following general formula (b-3) or (b-4) in the said general formula (b-1) or (b-2) can also be used. (The cation moiety is the same as (b-1) or (b-2)).

［式中、Ｘ”は、少なくとも１つの水素原子がフッ素原子で置換された炭素数２〜６のアルキレン基を表し；Ｙ”、Ｚ”は、それぞれ独立に、少なくとも１つの水素原子がフッ素原子で置換された炭素数１〜１０のアルキル基を表す。］

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

X ″ is a linear or branched alkylene group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkylene group has 2 to 6 carbon atoms, preferably 3 to 5 carbon atoms, Preferably it is C3.
Y ″ and Z ″ are each independently a linear or branched alkyl group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkyl group has 1 to 10 carbon atoms, preferably It is C1-C7, More preferably, it is C1-C3.
The carbon number of the alkylene group of X ″ or the carbon number of the alkyl group of Y ″ and Z ″ is preferably as small as possible because the solubility in the resist solvent is good within the above carbon number range.
In addition, in the alkylene group of X ″ or the alkyl group of Y ″ and Z ″, as the number of hydrogen atoms substituted with fluorine atoms increases, the strength of the acid increases, and high-energy light or electron beam of 200 nm or less The ratio of fluorine atoms in the alkylene group or alkyl group, that is, the fluorination rate is preferably 70 to 100%, more preferably 90 to 100%, and most preferably all. Are a perfluoroalkylene group or a perfluoroalkyl group in which a hydrogen atom is substituted with a fluorine atom.

  In the present invention, the oxime sulfonate-based acid generator is a compound having at least one group represented by the following general formula (B-1), and has a property of generating an acid upon irradiation with radiation. . Such oxime sulfonate-based acid generators are frequently used for chemically amplified resist compositions, and can be arbitrarily selected and used.

（式（Ｂ−１）中、Ｒ^２１、Ｒ^２２はそれぞれ独立に有機基を表す。）

(In formula (B-1), R ²¹ and R ²² each independently represents an organic group.)

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

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

  More preferable examples of the oxime sulfonate-based acid generator include compounds represented by the following general formula (B-2) or (B-3).

［式（Ｂ−２）中、Ｒ^３１は、シアノ基、置換基を有さないアルキル基またはハロゲン化アルキル基である。Ｒ^３２はアリール基である。Ｒ^３３は置換基を有さないアルキル基またはハロゲン化アルキル基である。］

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

［式（Ｂ−３）中、Ｒ^３４はシアノ基、置換基を有さないアルキル基またはハロゲン化アルキル基である。Ｒ^３５は２または３価の芳香族炭化水素基である。Ｒ^３６は置換基を有さないアルキル基またはハロゲン化アルキル基である。ｐは２または３である。］

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

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

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

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

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

Specific examples of 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.
Moreover, the compound represented by the following chemical formula is mentioned.

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

  Of the above exemplified compounds, the following three compounds are preferred.

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) and 1,4-bis (phenylsulfonyldiazomethylsulfonyl) having the following structure. Butane (compound B), 1,6-bis (phenylsulfonyldiazomethylsulfonyl) hexane (compound C), 1,10-bis (phenylsulfonyldiazomethylsulfonyl) decane (compound D), 1,2-bis (cyclohexylsulfonyl) Diazomethylsulfonyl) ethane (compound E), 1,3-bis (cyclohexylsulfonyldiazomethylsulfonyl) propane (compound F), 1,6-bis (cyclohexylsulfonyldiazomethylsulfonyl) hexane (compound G), 1,10- Bis (cyclohex Le diazomethylsulfonyl) decane (compound H) and the like.

  Among them, the component (B) preferably contains at least one selected from the group consisting of an onium salt acid generator having a fluorinated alkyl sulfonate ion as an anion and an oxime sulfonate acid generator. It is more preferable to contain both an onium salt-based acid generator and an oxime sulfonate-based acid generator having an alkylsulfonate ion as an anion. Thereby, high resolution can be achieved.

(B) As a component, these acid generators may be used individually by 1 type, and may be used in combination of 2 or more type.
Content of (B) component in the positive resist composition of this invention 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.

[Aromatic amine (C)]
In the present invention, it is necessary to contain the aromatic amine (C) (hereinafter sometimes referred to as the component (C)) together with the components (A) and (B) described above. By using these components in combination, dimensional controllability is improved.

In the present invention, the “aromatic amine” means that at least one of the hydrogen atoms of ammonia NH ₃ is an aromatic hydrocarbon group, and a hetero atom such as a nitrogen atom where a part of carbon atoms constituting the aromatic hydrocarbon group is a nitrogen atom. Means a compound substituted with an organic group having aromaticity (hereinafter sometimes referred to as an aromatic group), such as a group substituted with.
The aromatic hydrocarbon group preferably has 4 to 20 carbon atoms, more preferably 5 to 15 carbon atoms, and most preferably 6 to 10 carbon atoms.
Specific examples of the aromatic hydrocarbon group include groups obtained by removing one hydrogen atom from an aromatic ring such as benzene, naphthalene, and anthracene (for example, phenyl group, naphthyl, anthracenyl group, etc.); straight chain having 1 to 5 carbon atoms Alternatively, a group in which a part of hydrogen atoms of a branched alkyl group is substituted with an aromatic ring (for example, a benzyl group, a phenylethyl group (C ₆ H ₅ —CH ₂ —CH ₂ —), a naphthylmethyl group (C ₁₀ H ₇ — CH ₂ —), naphthylethyl group (C ₁₀ H ₇ —CH ₂ —CH ₂ —) and the like. In these groups, the aromatic ring may have a substituent, and examples of the substituent include an alkyl group having 1 to 5 carbon atoms.
As the aromatic group, an aromatic hydrocarbon group is preferable, a phenyl group or a benzyl group is more preferable, and a benzyl group is particularly preferable because of excellent effects of the present invention.

The component (C) includes, according to the number of hydrogen atoms substituted with an atom other than a hydrogen atom or a substituent X ′ (including at least one aromatic group) among the three hydrogen atoms of ammonia NH ₃ . It is divided into a primary amine (X′NH ₂ ), a secondary amine (X ′ ₂ NH), and a tertiary amine (X ′ ₃ N). In the present invention, the aromatic amine is preferably a secondary amine and / or a tertiary amine, and more preferably a tertiary amine because of its excellent stability in vacuum and the like.
In the primary amine, X ′ (atom or substituent other than a hydrogen atom) is an aromatic group. Further, in the secondary amine and / or the tertiary amine, it is sufficient that X ′ contains at least one aromatic group, and in addition, a linear, branched or cyclic group having 1 to 5 carbon atoms. An aliphatic hydrocarbon group, a group in which a part of carbon atoms of the aliphatic hydrocarbon group is substituted with a hetero atom such as a nitrogen atom, and the like may be included.
In addition, the component (C) may be a monoamine having one nitrogen atom in the molecule, and a diamine having two nitrogen atoms (phenylenediamine, benzidine, diaminonaphthalene, tolidine, etc.), Polyamines such as three triamines and four tetraamines may be used. Of these, monoamine is preferred.

  More specifically, examples of the component (C) include compounds represented by the following general formula (c-1).

［式中、Ｒ^１１〜Ｒ^１３はそれぞれ独立に水素原子、炭素数１〜１０のアルキル基または芳香族炭化水素基を表し、Ｒ^１１〜Ｒ^１３のうち少なくとも１つは芳香族炭化水素基を表す。］

[Wherein, R ^{11 to} R ¹³ each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or an aromatic hydrocarbon group, and at least one of R ^{11 to} R ¹³ represents an aromatic hydrocarbon group. To express. ]

Those in which two of R ^{11 to} R ¹³ are hydrogen atoms are primary amines, those in which one of R ^{11 to} R ¹³ is a hydrogen atom are secondary amines, and R ^{11 to} R ¹³ are Those that are all groups other than hydrogen atoms are tertiary amines.
In R ^{11 to} R ¹³ , the alkyl group having 1 to 10 carbon atoms may be linear, branched or aliphatic, and when linear or branched, it has 1 to 6 carbon atoms. Is preferable and 1-4 is more preferable. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group.
In R < ¹¹ > -R < ¹³ >, when a C1-C10 alkyl group is aliphatic cyclic, it is preferable that it is C3-C10, and it is more preferable that it is 4-6. Specific examples include a cyclopentyl group and a cyclohexyl group.
In R ^{11 to} R ¹³ , examples of the aromatic hydrocarbon group include the same groups as described above.
At least one of R ^{11 to} R ¹³ needs to be an aromatic hydrocarbon group, and from the viewpoint of excellent stability in vacuum, it is preferable that two or more are aromatic hydrocarbon groups. Most preferably, it is a group hydrocarbon group.

  Specific examples of the compound represented by the formula (c-1) include primary amines such as benzylamine, phenylamine, and phenethylamine; secondary amines such as dibenzylamine, diphenylamine, and diphenethylamine; triphenylamine And tertiary amines such as tribenzylamine and triphenethylamine. Among these, triphenylamine and tribenzylamine are preferable because of excellent effects of the present invention. Tribenzylamine is particularly preferable because the sensitivity can be adjusted to a sensitivity suitable as a resist composition and the resolution is excellent.

These may be used alone or in combination of two or more.
The content of the component (C) in the positive resist composition of the present invention is preferably 0.1 to 10 parts by mass, more preferably 0.3 to 5 parts by mass with respect to 100 parts by mass of the component (A). 0.5-3 mass parts is more preferable. Since it is excellent in the effect of this invention as it is more than a lower limit and below an upper limit, it is preferable.

[Organic solvent]
The positive resist composition of the present invention can be produced by dissolving the component (A), the component (B), the component (C) and any components described later in an organic solvent.
Any organic solvent may be used as long as it can dissolve each component to be used to form a uniform solution, and one or two kinds of conventionally known solvents for chemically amplified resists can be used. These can be appropriately selected and used.
For example, lactones such as γ-butyrolactone, ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone, ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate Polyhydric alcohols such as dipropylene glycol or dipropylene glycol monoacetate monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether and derivatives thereof, cyclic ethers such as dioxane, Methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, pyruvate Le, methyl methoxypropionate, esters such as ethyl ethoxypropionate can be exemplified.
These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
A mixed solvent obtained by mixing propylene glycol monomethyl ether acetate (PGMEA) and a polar solvent is preferable. The blending ratio (mass ratio) may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. It is preferable to be within the range.
More specifically, when EL is blended as a polar solvent, the mass ratio of PGMEA: EL is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2.
In addition, as the organic solvent, a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone is also preferable. In this case, the mixing ratio of the former and the latter is preferably 70:30 to 95: 5.
The amount of the organic solvent used is not particularly limited, but is a concentration that can be applied to a substrate and the like, and is appropriately set according to the coating film thickness. Generally, the solid concentration of the resist composition is 2 to 20 mass. %, Preferably 5-15% by mass.

[Other ingredients]
In the positive resist composition of the present invention, a nitrogen-containing organic compound (however, the (B) component and the (C) component are excluded) is further added as an optional component in order to improve the resist pattern shape, the stability over time. ) (D) (hereinafter referred to as component (D)).
Since a wide variety of components (D) have already been proposed, 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-n-propylamine, Tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decanylamine, tri-n- Trialkylamines such as dodecylamine; diethanolamine, trieta Ruamin, diisopropanolamine, triisopropanolamine, di -n- octanol amine, alkyl alcohol amines tri -n- octanol amine is Ageraru. Among these, a secondary aliphatic amine and a tertiary aliphatic amine are particularly preferable, a trialkylamine having 5 to 10 carbon atoms is more preferable, and tri-n-octylamine is most preferable.
These may be used alone or in combination of two or more.
(D) component is 0.01-3.0 mass parts normally with respect to 100 mass parts of (A) component, Preferably it is used in 0.05-2 mass parts.

In addition, the positive resist composition of the present invention is further improved for the purpose of preventing sensitivity deterioration due to the blending of the component (C) and / or the component (D), and improving the resist pattern shape, the holding stability, etc. As an optional component, an organic carboxylic acid or an oxo acid of phosphorus or a derivative thereof (E) (hereinafter referred to as (E) component) 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 further contains miscible additives as desired, for example, additional resins for improving the performance of the resist film, surfactants for improving coating properties, dissolution inhibitors, Plasticizers, stabilizers, colorants, antihalation agents, dyes, and the like can be added and contained as appropriate.

As described above, the positive resist composition of the present invention is excellent in dimensional controllability. This is because the positive resist composition of the present invention can form a resist film whose performance is not easily changed in vacuum, that is, a resist film having high stability in vacuum. That is, conventionally, in the production of a photomask, exposure of a resist film is usually performed by direct writing with an electron beam in a vacuum (for example, 1 × 10 ⁻⁷ to 1 × 10 ⁻⁵ Pa). However, in exposure by direct drawing of an electron beam, it takes a long time (for example, about 12 to 24 hours) from the start to the end of drawing as the pattern becomes finer. Therefore, even within the same substrate surface, the time from exposure to post-exposure heating (PEB) and development differs between the first exposed portion and the last exposed portion. Conventionally, since the resist film has low stability in vacuum and the performance change over time is large, there is a difference in resist performance, and the pattern size of the first exposed part and the last exposed part of the pattern are different. It is presumed that the dimensional controllability was lowered as a result of the difference in pattern dimensions. On the other hand, the positive resist composition of the present invention is considered to have good dimensional controllability because of high stability in vacuum and small change in performance over time. The reason why the stability in vacuum is high is not clear, but aromatic amines volatilize out of the membrane during vacuum compared to aliphatic amines such as trioctylamine, which are conventionally blended as nitrogen-containing compounds. Therefore, it is assumed that the performance is not easily changed and is stable.

  Further, the positive resist composition of the present invention is not easily affected by the substrate, and no matter what substrate is used, for example, a rectangular pattern on a silicon substrate, an antireflection film, a chromium oxide layer, or the like. Can be formed. For example, a substrate in which a chromium oxide layer is laminated as a substrate is usually used for manufacturing a photomask. In order to manufacture a photomask with a fine pattern, a resist using a chemically amplified resist on the chromium oxide layer is used. When the pattern is formed, the acid generated from the acid generator is deactivated at the interface with the chromium oxide layer due to the influence of the chromium oxide layer. For example, in the case of a positive type, the portion is alkali-insoluble. There is a problem that the rectangular pattern cannot be formed because the resist at the interface with the substrate remains without being removed after development, without changing. Etching the shielding layer using such a poorly shaped resist pattern as a photomask is disadvantageous because the pattern cannot be transferred faithfully and a precise photomask cannot be obtained. In contrast, the positive resist composition of the present invention is less susceptible to the chromium oxide layer and can form a rectangular pattern on the chromium oxide layer.

  Therefore, the positive resist composition of the present invention is suitable for manufacturing a photomask. That is, as described above, the positive resist composition of the present invention has high stability in vacuum and small change in performance over time, and therefore has good dimensional controllability, and has a rectangular shape on the chromium oxide layer. Since the pattern can be formed, by using the positive resist composition of the present invention, the pattern can be faithfully transferred to the chromium oxide layer, and a precise photomask can be obtained.

<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. Further, for example, an electron beam or other far ultraviolet rays are selectively exposed with or without a desired mask pattern by an electron beam drawing apparatus or the like. That is, after exposing through a mask pattern or drawing by direct irradiation with an electron beam without passing through a mask pattern, heat treatment (post-exposure baking (PEB)) is performed at a temperature of 80 to 150 ° C. for 40 to 120. Second, preferably 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 of the electron beam or other far ultraviolet rays used for exposure is not particularly limited, and ArF excimer laser, KrF excimer laser, F ₂ laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), electron beam, X-ray, It can be performed using radiation such as soft X-rays.
Since the positive resist composition of the present invention has high stability under vacuum, it can be suitably used for resist pattern formation including an exposure step under vacuum, and for electron beams or EUV (extreme ultraviolet). Particularly preferred for an electron beam.

  Furthermore, when manufacturing a photomask using the positive resist composition of the present invention, the resist pattern is formed on a glass substrate on which a chromium oxide layer is laminated, and the positive resist composition for manufacturing a photomask of the present invention is used. This is formed by forming a positive resist film using, and subjecting the positive resist film to exposure treatment, followed by heat treatment (PEB) and development treatment to form a resist pattern. it can.

Specifically, first, a glass substrate having a chromium oxide layer laminated on one side is prepared. The chromium oxide layer is a layer mainly composed of chromium oxide. As the chromium oxide, Cr _a O _b (in the chemical formula, a is an integer of 1 to 2, and preferably 1, b is 3 to 3). 1 or a mixture of two or more selected from the group consisting of compounds represented by the following formula:
On the glass substrate with the chromium oxide layer, the positive resist composition for manufacturing a photomask of the present invention prepared in a solution is applied with a spinner or the like and dried to form a positive resist film.
Next, an exposure process is selectively performed on the positive resist film. The exposure process can use KrF excimer laser light, ArF excimer laser light, F ₂ excimer laser light, EUV (Extreme Ultraviolet), electron beam, soft X-ray, X-ray, etc., and a desired mask pattern. It can be performed by irradiation through direct drawing or direct drawing. In the present invention, it is preferable to use an electron beam for the exposure processing, and direct drawing using an electron beam is particularly preferably used.
Subsequently, a post-exposure heating (PEB) process is performed. The heating conditions in the PEB treatment vary depending on the type of each component in the resist composition, the blending ratio, the coating film thickness, and the like, but are, for example, about 80 to 150 ° C. and 40 to 120 seconds, more preferably about 60 to 90 seconds.
After the PEB process, a positive resist pattern can be obtained by developing using a developer such as an alkaline aqueous solution and performing a process such as washing with water and drying as necessary. The developer is not particularly limited, and a commonly used alkaline aqueous solution or the like can be used. For example, an aqueous solution of TMAH (tetramethylammonium hydroxide) having a concentration of 2.38% by mass is preferably used.

  Furthermore, by using the resist pattern as a mask, a portion of the chromium oxide layer where the pattern is not formed is etched to transfer the pattern to the chromium oxide layer, thereby oxidizing the glass substrate and a predetermined pattern thereon. A photomask with a chromium layer can be manufactured.

Examples of the present invention will be described below, but the scope of the present invention is not limited to these examples.
Examples 1-4, Comparative Example 1, Examples 5-8, Comparative Example 2, Examples 9-12, Comparative Example 3, Examples 13-16, Comparative Example 4
100 parts by mass of component (A) shown in Table 1 below, 8 parts by mass of α- (methyloxyimino) -p-methoxyphenylacetonitrile as component (B), amines shown in Table 1, and as component (E) 0.364 parts by mass of salicylic acid and 0.05 parts by mass of a surfactant “XR-104” (trade name, manufactured by Dainippon Ink & Chemicals, Inc.) were dissolved in 1150 parts by mass of propylene glycol monomethyl ether acetate. Thus, a positive resist composition solution was prepared.

The obtained positive resist composition solution was uniformly applied on an 8-inch silicon substrate subjected to hexamethyldisilazane treatment so as to have the resist film thickness shown in Table 1 below, and baked at 110 ° C. for 90 seconds. The film was formed by performing the treatment (PAB).
The substrate was drawn with an electron beam drawing machine (Hitachi HL-800D, 70 kV acceleration voltage) and then baked (PEB) at 110 ° C. for 90 seconds, with a 2.38 mass% TMAH aqueous solution. After developing at 23 ° C. for 60 seconds, rinsing with pure water for 30 seconds, performing shake-off drying, post-baking treatment is performed at 100 ° C. for 60 seconds, and a line and space with a line width of 200 nm (line width / space width = A resist pattern (hereinafter, referred to as a 200 nm resist pattern) targeting 1/1) was formed.
The obtained resist pattern was observed with a scanning electron microscope (SEM), and the optimum exposure amount (μC / cm ² ) at which a 200 nm resist pattern was formed was determined. The results are shown in Table 2 as “sensitivity”.
Moreover, the resist pattern was observed by SEM, and the limit resolution (nm) at the optimum exposure amount at which a 200 nm resist pattern was formed was determined. The results are shown in Table 2 as “resolution”.

Further, the positive resist composition solution obtained above was applied on an 8-inch silicon substrate so as to have a resist film thickness of 300 nm, and was subjected to PAB at 110 ° C. for 90 seconds to form a film. In the electron beam drawing apparatus (Hitachi HL-800D, 70 kV acceleration voltage), the drawing is performed at the same exposure amount every 2 hours after being drawn for 24 hours at maximum, and then 23 ° C. with 2.38 mass% TMAH aqueous solution. The film was developed for 60 seconds, rinsed with pure water for 30 seconds, shaken and dried, and then post-baked at 100 ° C. for 60 seconds. As a result, a plurality of 200 nm resist patterns having different times of leaving in the drawing apparatus were formed on the same substrate. The pressure in the drawing apparatus was 1.8 × 10 ⁻⁵ Pa.
With respect to the obtained resist pattern of 200 nm, the dimensional change was calculated as follows. The results are shown in Table 2.
Dimensional change amount (nm) = line width having the largest change amount−200 nm (of the formed resist pattern, the value obtained by subtracting 200 nm from the line width of the thickest part of the line pattern and 200 nm from the line width of the thinnest part) The value with the larger absolute value)
In Table 2, a value of + indicates that the pattern is thick, and a value of-indicates that the pattern is thin.

The structures of resins 1 to 5 in Table 1 are as shown below.
In Table 1, amine 1 is tri-n-octylamine, amine 2 is triphenylamine, and amine 3 is tribenzylamine. In addition, 0.96 mass parts of amine 1, 0.666 mass parts of amine 2, and 0.78 mass parts of amine 3 are equimolar amounts.

［式中、ａ^１：ｂ^１：ｃ^１：ｄ^１（モル比）＝５８：１７：２２：３（モル比）であり、Ｅｖは１−エトキシエチル基を表す。Ｍｗ＝１２０００、Ｍｗ／Ｍｎ＝１．７］

[Wherein, a ¹ : b ¹ : c ¹ : d ¹ (molar ratio) = 58: 17: 22: 3 (molar ratio), and Ev represents a 1-ethoxyethyl group. Mw = 12000, Mw / Mn = 1.7]

［式中、ａ^２：ｂ^２：ｃ^２：ｄ^２（モル比）＝５８：１７：２２：３であり、Ｅｖは１−エトキシエチル基を表す。Ｍｗ＝１００００、Ｍｗ／Ｍｎ＝１．５］

[Wherein, a ² : b ² : c ² : d ² (molar ratio) = 58: 17: 22: 3, and Ev represents a 1-ethoxyethyl group. Mw = 10000, Mw / Mn = 1.5]

［式中、樹脂３はａ^３：ｂ^３（モル比）＝７２：２８であり、Ｍｗ＝１２０００、Ｍｗ／Ｍｎ＝１．２。樹脂４はａ^４：ｂ^４：ｃ^４（モル比）＝６２：２８：１０であり、Ｍｗ＝１００００、Ｍｗ／Ｍｎ＝１．２。］

Wherein the resin 3 ^a 3: ^{b 3} (molar ratio) = 72: A 28, Mw = 12000, Mw / Mn = 1.2. Resin 4 is ^{a 4:} b 4 - ^{c 4} (molar ratio) = 62: 28: A 10, Mw = 10000, Mw / Mn = 1.2. ]

［式中、ｍ：ｎ（モル比）＝５６：４４である。Ｍｗ＝１２４００、Ｍｗ／Ｍｎ＝１．２］

[Wherein, m: n (molar ratio) = 56: 44. Mw = 12400, Mw / Mn = 1.2]

As shown in the above results, in Examples 1 to 16, since the amount of dimensional change was small, it was confirmed that the dimensional controllability was excellent in stability in vacuum. Among them, Examples 3 to 4, Examples 7 to 8, Examples 11 to 12, and Examples 15 to 16 using both the resin 1, 2, 3 or 4 and the resin 5 are the results of dimensional change. Was particularly good.
In addition, the positive resist compositions of Examples 1 to 16 had sufficiently high resolution, and in particular, the resolution was particularly excellent when tribenzylamine was used.
On the other hand, although the positive resist compositions of Comparative Examples 1 to 4 had high resolution, the dimensional change was large and the dimensional controllability was poor.

Claims (17)

A resin component (A) having an alkali-soluble structural unit (a1) and a structural unit (a2) having an acid dissociable, dissolution inhibiting group, and increased in alkali solubility by the action of an acid, and generates an acid upon exposure. A positive resist composition containing an acid generator component (B),
In the resin component (A), the structural unit (a1) has a structural unit (a11) derived from (α-methyl) hydroxystyrene, and the structural unit (a2) has the following general formula (II):

[Wherein, X represents an aliphatic cyclic group, an aromatic cyclic hydrocarbon group, or an alkyl group having 1 to 5 carbon atoms, R ¹ represents an alkyl group having 1 to 5 carbon atoms, or X and R ¹ Each independently represents an alkylene group having 1 to 5 carbon atoms, and the end of X and the end of R ¹ may be bonded to each other, and R ² represents an alkyl group having 1 to 5 carbon atoms or a hydrogen atom. ]
Selected from the group consisting of an acid dissociable, dissolution inhibiting group (II) and / or a chain tertiary alkoxycarbonyl group, a chain tertiary alkyl group, and a chain tertiary alkoxycarbonylalkyl group Having at least one acid dissociable, dissolution inhibiting group (III), and
A positive resist composition comprising an aromatic amine (C) represented by the following general formula (c-1) .

[Wherein, R ^{11 to} R ¹³ each independently represents an aromatic hydrocarbon group. ] The acid dissociable, dissolution inhibiting group (II) is represented by the following general formula (II-1)

[Wherein, Y represents an aliphatic cyclic group , an aromatic cyclic hydrocarbon group or an alkyl group having 1 to 5 carbon atoms, and R ¹ represents an alkyl group having 1 to 5 carbon atoms. ]
The positive resist composition according to claim 1 Symbol placement in an acid dissociable dissolution inhibiting group represented. The acid dissociable, dissolution inhibiting group (III) is a chain tertiary alkoxycarbonyl group claim 1 or 2 positive resist composition. The structural unit (a1) further has an (α-lower alkyl) acrylate ester having an alcoholic hydroxyl group [the lower alkyl has 1 to 5 carbon atoms. The positive resist composition according to any one of claim 1 to 3 having the induced structural unit (a12) from. The structural unit (a12) is an aliphatic polycyclic group-containing (α-lower alkyl) acrylate ester having an alcoholic hydroxyl group [the carbon number of the lower alkyl is 1 to 5. The positive resist composition according to claim 4, wherein a structural unit derived from. The structural unit (a2) is, according to any one of claims 1 to 5 hydrogen atoms of the hydroxyl groups including a structural unit formed by substituted with an acid dissociable dissolution inhibiting group (a21) of the structural unit (a11) A positive resist composition. The structural unit (a2) is, any one of claims 4-6 hydrogen atoms alcoholic hydroxyl group containing a structural unit formed by substituted with an acid dissociable dissolution inhibiting group (a22) of the structural unit (a12) The positive resist composition as described in 1. above. The said resin component (A) contains the copolymer which has the said structural unit (a11), the said structural unit (a12), the said structural unit (a21), and / or the said structural unit (a22). 7. The positive resist composition according to 7 . The resin component (A) has the structural unit (a1) and the structural unit (a2), has the acid dissociable dissolution inhibiting group (II) as an acid dissociable dissolution inhibiting group, and the acid. The polymer (A1) having no dissociable dissolution inhibiting group (III), the structural unit (a1) and the structural unit (a2), and the acid dissociable dissolution as an acid dissociable dissolution inhibiting group The positive resist composition according to claim 7 or 8, comprising a polymer (A2) having an inhibitory group (III) and not having the acid dissociable, dissolution inhibiting group (II). 10. The positive resist composition according to claim 9 , wherein a content ratio (mass ratio) between the polymer (A1) and the polymer (A2) is within a range of 10/90 to 90/10. The polymer (A1) is a polymer (A11) having the structural unit (a11) and the structural unit (a21) and not having the structural unit (a12) and the structural unit (a22). The polymer (A2) has the structural unit (a11) and the structural unit (a21), and does not have the structural unit (a12) and the structural unit (a22) (A21). The positive resist composition according to claim 9 or 10 . The positive resist composition according to claim 11, wherein in the polymer (A11), the X of the acid dissociable, dissolution inhibiting group (II) is an adamantyl group or a naphthyl group. The positive resist composition according to claim 11 or 12, wherein the polymer (A11) further has a structural unit (a3) derived from (α-methyl) styrene. The polymer (A1) is a polymer (A12) having the structural unit (a11), the structural unit (a12), the structural unit (a21) and / or the structural unit (a22). The polymer (A2) has the structural unit (a11) and the structural unit (a21), and does not have the structural unit (a12) and the structural unit (a22) (A21). The positive resist composition according to claim 9 or 10 . The positive resist composition according to claim 14, wherein in the polymer (A12), the acid dissociable, dissolution inhibiting group (II) is a 1-alkoxyalkyl group. The positive resist composition according to any one of claims 1 to 15 , which is used for producing a photomask. A step of forming a resist film on a substrate using the positive resist composition according to any one of claims 1 to 16 , a step of selectively exposing the resist film, and alkali developing the resist film A resist pattern forming method including a step of forming a resist pattern.