JP4663459B2 - 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 using the same.

  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 made on shorter wavelength F2 excimer lasers (157 nm), EUV (extreme ultraviolet rays), electron beams, X-rays, and the like.

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 the chemically amplified positive resist composition, a resin in which a hydroxyl group of a polyhydroxystyrene (PHS) resin is protected with an acid dissociable, dissolution inhibiting group is generally used. Examples of the acid dissociable, dissolution inhibiting group include so-called acetal acid dissociable, dissolution inhibiting groups such as a chain ether group represented by 1-ethoxyethyl group and a cyclic ether group represented by tetrahydropyranyl group; So-called annealing-based acid dissociable, dissolution inhibiting groups such as tertiary alkyl groups typified by butyl groups and tertiary alkoxycarbonyl groups typified by tert-butoxycarbonyl groups are used (for example, patents). Reference 1).

On the other hand, in the manufacture of semiconductor elements and liquid crystal display elements, an impurity diffusion layer is formed on the substrate surface. The formation of the impurity diffusion layer is usually performed in two steps, impurity introduction and diffusion. As one of the introduction methods, impurities such as phosphorus and boron are ionized in vacuum and accelerated by a high electric field. There is ion implantation (hereinafter referred to as “implantation”) that is implanted into the substrate surface.
As a technique for selectively implanting impurity ions on the substrate surface by implantation, for example, Patent Document 2 discloses a “gradient implantation” process in which implantation is performed in a state where the substrate on which a resist pattern (mask) is formed is inclined. It has been reported. This process is considered to be an effective means when ion implantation is desired only for a small part of the substrate that is directly under the resist pattern or a side wall part of a hole formed in the substrate.
In the inclined implantation process, when a fine resist pattern of about 0.35 μm is formed, the resist pattern serving as a mask has a thickness of about 0.1 to 0.5 μm so that ion implantation is not hindered. A thin film is used.
Furthermore, the resist pattern in the inclined implantation process is required to have a shape characteristic for implanting ions into a desired portion of the substrate.

However, in the inclined implantation process using such a thin film resist pattern (hereinafter referred to as a thin film implantation process), particularly when a resin having high transparency with respect to exposure light is used, The resist pattern is likely to be defective due to the influence of the reflected light from the substrate. In particular, when a semiconductor element or a liquid crystal display element is manufactured, a thin film implantation process is performed on a substrate on which electrodes and the like are formed. Therefore, it is difficult to form a resist film with a uniform film thickness on the substrate. is there. Therefore, for example, there is a problem of a so-called standing wave (hereinafter abbreviated as SW) phenomenon in which the resist pattern dimension increases or decreases due to a change in resist film thickness. The change in pattern dimension due to SW tends to increase as the resist film becomes thinner and the transparency of the resist film increases, and is particularly noticeable in the case of a thin film having a thickness of 500 nm or less. Further, the problem of dimensional change becomes more serious as the resist pattern becomes finer.
In the resist pattern used in the implantation process, an antireflection film cannot be provided as a lower layer film.

With respect to such a problem, in Patent Document 3 below, a resist composition containing a novolak resin, a quinonediazide esterified product, and a phenol compound is added to a resist composition containing 2,2 ′, 4,4′-tetrahydroxybenzophenone and the like at around 365 nm. There has been proposed a method of suppressing a dimensional change of a resist pattern in a thin film by blending a compound (dye) having absorption with respect to light having a wavelength.
JP 2002-341538 A JP-A-8-22965 JP 2003-149816 A

However, in the method described in Patent Document 3, sufficient effects may not be obtained depending on the composition of the resist film and the conditions at the time of forming the resist pattern, and other methods are required.
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 capable of forming a resist pattern with small dimensional variation with respect to the resist film thickness.

In order to achieve the above object, the present invention employs the following configuration.
The first aspect of the present invention comprises a resin component (A) whose alkali solubility is increased by the action of an acid, an acid generator component (B) that generates an acid upon irradiation with radiation, and a compound (O ), Wherein the component (A) is a structural unit (a1) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group, and an acryl containing a lactone-containing cyclic group. A structural unit derived from an acid ester (a2), a structural unit derived from an acrylic ester containing a polar group-containing aliphatic hydrocarbon group (a3), and a non-acid-dissociable aliphatic polycyclic group A copolymer (A1) comprising a structural unit (a4) derived from an acrylate ester, wherein the component (O) comprises a structural unit (O1-1) derived from hydroxystyrene, and has acid dissociation properties Dissolution inhibiting group Ri resin (O1) der not, the (O1) content of the component, relative to the component (A) 100 parts by weight, a positive resist composition according to claim 0.1 to 10 parts by der Rukoto It is a thing.
A second aspect of the present invention includes a step of forming a resist film having a thickness of 500 nm or less on a substrate using the positive resist composition of the present invention, a step of exposing the resist film, and developing the resist film. A resist pattern forming method including a step of forming a resist pattern.

In the present specification and claims, “structural unit” means a monomer unit (monomer unit) constituting a resin component (polymer).
“Exposure” is a concept including general irradiation of radiation.

  ADVANTAGE OF THE INVENTION According to this invention, the positive resist composition and resist pattern formation method which can form a resist pattern with a small dimensional variation with respect to a resist film thickness can be provided.

≪Positive resist composition≫
The positive resist composition of the present invention comprises a resin component (A) whose alkali solubility is increased by the action of an acid (hereinafter referred to as “component (A)”) and an acid generator component (which generates an acid upon irradiation with radiation) ( B) (hereinafter referred to as the component (B)) and a compound (O) having a radiation absorbing ability.
In the positive resist composition of the present invention, the component (A) is alkali-insoluble before exposure, and when an acid generated from the component (B) acts upon exposure, the acid dissociable, dissolution inhibiting group dissociates. As a result, the alkali solubility of the entire component (A) is increased and the alkali-insoluble is changed to alkali-soluble. Therefore, when a resist film obtained by using a positive resist composition is selectively exposed in the formation of a resist pattern, the exposed portion turns alkali-soluble, while the unexposed portion remains alkali-insoluble. Therefore, alkali development can be performed.

<(A) component>
In the present invention, the component (A) preferably contains a copolymer (A1) having a structural unit derived from an acrylate ester.
When the (A1) component is used in the positive resist composition and the (O) component in the present invention, that is, the (O1) component described later is contained, a standing wave or substrate generated by reflection from the substrate at the time of exposure. It is possible to effectively reduce the adverse effect on the resist pattern shape due to irregular reflection due to a step on the surface.

Here, in the present specification and claims, the “structural unit derived from an acrylate ester” means a structural unit formed by cleavage of an ethylenic double bond of an acrylate ester.
“Acrylic acid esters” include those in which a hydrogen atom is bonded to the carbon atom at the α-position, and those in which a substituent (atom or group other than a hydrogen atom) is bonded to the carbon atom in the α-position. Include concepts. Examples of the substituent include a halogen atom, a lower alkyl group, and a halogenated lower alkyl group. 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.
The α-position (α-position carbon atom) of a structural unit derived from an acrylate ester is a carbon atom to which a carbonyl group is bonded unless otherwise specified.
The “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups unless otherwise specified.
The “lower alkyl group” is an alkyl group having 1 to 5 carbon atoms.
In the acrylate ester, as the lower alkyl group as a substituent at the α-position, specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, Examples include lower linear or branched alkyl groups such as isopentyl group and neopentyl group.
In the present invention, the α-position of the acrylate ester is preferably a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, and a hydrogen atom, a fluorine atom, a lower alkyl group or a fluorine atom. A lower alkyl group is more preferable, and a hydrogen atom or a methyl group is most preferable in terms of industrial availability.

・ Structural unit (a1)
The component (A1) preferably has a structural unit (a1) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group.
The acid dissociable, dissolution inhibiting group in the structural unit (a1) has an alkali dissolution inhibiting property that makes the entire copolymer (A1) insoluble in alkali before dissociation, and the entire copolymer (A1) is alkalinized after dissociation. As long as it is changed to be soluble, those that have been proposed as acid dissociable, dissolution inhibiting groups for base resins for chemically amplified resists can be used. Generally, a group that forms a cyclic or chain tertiary alkyl ester with a carboxy group of (meth) acrylic acid, or a group that forms a cyclic or chain alkoxyalkyl ester is widely known. . The “(meth) acrylic acid ester” means one or both of an acrylic acid ester having a hydrogen atom bonded to the α-position and a methacrylic acid ester having a methyl group bonded to the α-position.

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

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

（式中、Ｒは水素原子、ハロゲン原子、低級アルキル基またはハロゲン化低級アルキル基を示し；Ｘ^１は酸解離性溶解抑制基を示す。）

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

（式中、Ｒは水素原子、ハロゲン原子、低級アルキル基またはハロゲン化低級アルキル基を示し；Ｘ^２は酸解離性溶解抑制基を示し；Ｙ^２はアルキレン基または脂肪族環式基を示す。）

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

In the general formula (a1-0-1), the halogen atom, lower alkyl group or halogenated lower alkyl group of R is a halogen atom, lower alkyl group or halogenated lower group which may be bonded to the α-position of the acrylate ester. It is the same as the alkyl group.
X ¹ is not particularly limited as long as it is an acid dissociable, dissolution inhibiting group, and examples thereof include an alkoxyalkyl group, a tertiary alkyl ester type acid dissociable, dissolution inhibiting group, and the like. Acid dissociable, dissolution inhibiting groups are preferred. Examples of the tertiary alkyl ester type acid dissociable, dissolution inhibiting group include an aliphatic branched acid dissociable, dissolution inhibiting group and an acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group.
Here, “aliphatic” in the claims and the specification is a relative concept with respect to aromatics, and is defined to mean a group, a compound, or the like that does not have aromaticity. The “aliphatic cyclic group” means a monocyclic group or a polycyclic group having no aromaticity.
The “aliphatic cyclic group” in the structural unit (a1) may or may not have a substituent. Examples of the substituent include a lower alkyl group having 1 to 5 carbon atoms, a fluorine atom, a fluorinated lower alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, an oxygen atom (= O), and the like.
The basic ring structure excluding the substituent of the “aliphatic cyclic group” is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated. A polycyclic group is preferred.
Specific examples of such aliphatic cyclic groups include, for example, monocycloalkanes, bicycloalkanes, trialkyls which may or may not be substituted with a lower alkyl group, a fluorine atom or a fluorinated alkyl group. Examples include groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as cycloalkane or tetracycloalkane. Specific examples include monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.
Specific examples of the aliphatic branched acid dissociable, dissolution inhibiting group include a tert-butyl group and a tert-amyl group.
Examples of the acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group include a group having a tertiary carbon atom on the ring skeleton of a cyclic alkyl group, specifically 2-methyl Examples include a 2-adamantyl group and a 2-ethyl-2-adamantyl group. Alternatively, as a structural unit represented by the following general formula, a group having an aliphatic cyclic group such as an adamantyl group and a branched alkylene group having a tertiary carbon atom bonded thereto can be used.

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

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

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

（式中、Ｒ^１７、Ｒ^１８はそれぞれ独立して直鎖状または分岐状のアルキル基または水素原子であり、Ｒ^１９は直鎖状、分岐状または環状のアルキル基である。または、Ｒ^１７とＲ^１９の末端が結合して環を形成していてもよい。）

(Wherein R ¹⁷ and R ¹⁸ are each independently a linear or branched alkyl group or a hydrogen atom, and R ¹⁹ is a linear, branched or cyclic alkyl group, or R ^17. And the end of R ¹⁹ may be bonded to form a ring.)

In R ¹⁷ and R ¹⁸ , the alkyl group preferably has 1 to 15 carbon atoms, may be linear or branched, and is preferably an ethyl group or a methyl group, and most preferably a methyl group. In particular, one of R ¹⁷ and R ¹⁸ is preferably a hydrogen atom and the other is a methyl group.
R ¹⁹ is a linear, branched or cyclic alkyl group, preferably having 1 to 15 carbon atoms, and may be linear, branched or cyclic.
When R ¹⁹ is linear or branched, it preferably has 1 to 5 carbon atoms, more preferably an ethyl group or a methyl group, and most preferably an ethyl group.
When R ¹⁹ is cyclic, it preferably has 4 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and most preferably 5 to 10 carbon atoms. Specifically, one or more polycycloalkanes such as monocycloalkane, bicycloalkane, tricycloalkane, and tetracycloalkane, which may or may not be substituted with a fluorine atom or a fluorinated alkyl group, are included. Examples include a group excluding a hydrogen atom. Specific examples include monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Among them, a group obtained by removing one or more hydrogen atoms from adamantane is preferable.
In the above formula, R ¹⁷ and R ¹⁹ are each independently an alkylene group having 1 to 5 carbon atoms, and the end of R ^{19 and} the end of R ¹⁷ may be bonded.
In this case, a cyclic group is formed by R ¹⁷ , R ¹⁹ , the oxygen atom to which R ¹⁹ is bonded, and the carbon atom to which the oxygen atom and R ¹⁷ are bonded. The cyclic group is preferably a 4- to 7-membered ring, and more preferably a 4- to 6-membered ring. Specific examples of the cyclic group include a tetrahydropyranyl group and a tetrahydrofuranyl group.

In general formula (a1-0-2), R is the same as described above. X ² is the same as X ¹ in formula (a1-0-1).
Y ² is preferably an alkylene group having 1 to 4 carbon atoms or a divalent aliphatic cyclic group.
When Y ² is a divalent aliphatic cyclic group, it is the same as the description of the “aliphatic cyclic group” in the structural unit (a1) except that a group in which two or more hydrogen atoms are removed is used. Can be used.

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

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

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

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

X ′ is the same as the tertiary alkyl ester type acid dissociable, dissolution inhibiting group exemplified in X ¹ above.
Examples of the aliphatic cyclic group for Y include the same groups as those exemplified above in the explanation of “aliphatic cyclic group”.

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

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

（式中、Ｒは水素原子、ハロゲン原子、低級アルキル基またはハロゲン化低級アルキル基を示し、Ｒ^１１は低級アルキル基を示す。）

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

（式中、Ｒは水素原子、ハロゲン原子、低級アルキル基またはハロゲン化低級アルキル基を示し、Ｒ^１２は低級アルキル基を示す。ｈは１〜３の整数を表す）

(In the formula, R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, R ¹² represents a lower alkyl group, and h represents an integer of 1 to 3).

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

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

  In the copolymer (A1), the proportion of the structural unit (a1) is preferably 10 to 80 mol%, more preferably 20 to 70 mol%, based on all structural units constituting the copolymer (A1). More preferred is ˜50 mol%. By setting it to the lower limit value or more, a pattern can be obtained when the resist composition is used, and by setting it to the upper limit value or less, it is possible to balance with other structural units.

・ Structural unit (a2)
The copolymer (A1) preferably has a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group.
Here, the lactone-containing cyclic group refers to a cyclic group containing one ring (lactone ring) containing an —O—C (O) — structure. The lactone ring is counted as the first ring. When only the lactone ring is present, it is called a monocyclic group, and when it has another ring structure, it is called a polycyclic group regardless of the structure.
When the copolymer (A1) is used for forming a resist film, the lactone cyclic group of the structural unit (a2) increases the adhesion of the resist film to the substrate or increases the hydrophilicity with the developer. It is effective in doing.

As the structural unit (a2), any unit can be used without any particular limitation.
Specifically, examples of the lactone-containing monocyclic group include groups in which one hydrogen atom has been removed from γ-butyrolactone. Examples of the lactone-containing polycyclic group include groups in which one hydrogen atom has been removed from a bicycloalkane, tricycloalkane, or tetracycloalkane having a lactone ring.

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

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

[Wherein, R is a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, R ′ is a hydrogen atom, a lower alkyl group, or an alkoxy group having 1 to 5 carbon atoms, and m is 0 or It is an integer of 1. ]

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

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

In the copolymer (A1), as the structural unit (a2), one type may be used alone, or two or more types may be used in combination.
5-60 mol% is preferable with respect to the sum total of all the structural units which comprise a copolymer (A1), and the ratio of the structural unit (a2) in a copolymer (A1) is 10-50 mol% more. Preferably, 20-50 mol% is more preferable. By setting it to the lower limit value or more, the effect of containing the structural unit (a2) is sufficiently obtained, and by setting the upper limit value or less, it is possible to balance with other structural units.

・ Structural unit (a3)
The copolymer (A1) preferably contains a structural unit (a3) derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group. By having the structural unit (a3), the hydrophilicity of the component (A) is increased, the affinity with the developer is increased, the alkali solubility in the exposed area is improved, and the resolution is improved.
Examples of the polar group include a hydroxyl group, a cyano group, a carboxy group, and a hydroxyalkyl group in which a part of hydrogen atoms of an alkyl group is substituted with a fluorine atom. A hydroxyl group is particularly preferable.
Examples of the aliphatic hydrocarbon group include a linear or branched hydrocarbon group having 1 to 10 carbon atoms (preferably an alkylene group) and a polycyclic aliphatic hydrocarbon group (polycyclic group). . As the polycyclic group, for example, a resin for a resist composition for ArF excimer laser can be appropriately selected from among many proposed ones.
Among them, a structural unit derived from an acrylate ester containing an aliphatic polycyclic group containing a hydroxyalkyl group in which a part of hydrogen atoms of a hydroxyl group, a cyano group, a carboxy group, or an alkyl group is substituted with a fluorine atom Is more preferable. Examples of the polycyclic group include groups in which one or more hydrogen atoms have been removed from bicycloalkane, tricycloalkane, tetracycloalkane or the like. Specific examples include groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane. Among these polycyclic groups, there are groups in which two or more hydrogen atoms have been removed from adamantane, groups in which two or more hydrogen atoms have been removed from norbornane, and groups in which two or more hydrogen atoms have been removed from tetracyclododecane. Industrially preferable.

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

（式中、Ｒは前記に同じであり、ｊは１〜３の整数であり、ｋは１〜３の整数であり、ｔ’は１〜３の整数であり、ｌは１〜５の整数であり、ｓは１〜３の整数である。）

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

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

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

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

As the structural unit (a3), one type may be used alone, or two or more types may be used in combination.
In the copolymer (A1), the proportion of the structural unit (a3) is preferably 5 to 50% by mole, and 5 to 40% by mole with respect to all the structural units constituting the copolymer (A1). More preferably, 5-25 mol% is further more preferable.

・ Structural unit (a4)
The copolymer (A1) may contain other structural units (a4) other than the structural units (a1) to (a3) as long as the effects of the present invention are not impaired.
The structural unit (a4) is not particularly limited as long as it is another structural unit not classified into the structural units (a1) to (a3) described above, and is for ArF excimer laser, for KrF excimer laser (preferably ArF excimer laser) A number of conventionally known resins can be used for resist resins such as
As the structural unit (a4), for example, a structural unit derived from an acrylate ester containing a non-acid-dissociable aliphatic polycyclic group is preferable. Examples of the polycyclic group include those exemplified in the case of the structural unit (a1), and for ArF excimer laser and KrF excimer laser (preferably for ArF excimer laser). A number of hitherto known materials can be used as the resin component of the resist composition.
In particular, at least one selected from a tricyclodecanyl group, an adamantyl group, a tetracyclododecanyl group, an isobornyl group, and a norbornyl group is preferable in terms of industrial availability. These polycyclic groups may be substituted with a linear or branched alkyl group having 1 to 5 carbon atoms.
Specific examples of the structural unit (a4) include those represented by the following general formulas (a4-1) to (a4-5).

（式中、Ｒは前記と同じである。）

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

As the structural unit (a4), those having a structure of the following general formula (a4-1) are particularly preferred, and among them, those wherein R is a methyl group are more preferred.
When such a structural unit (a4) is contained in the copolymer (A1), the structural unit (a4) is contained in an amount of 1 to 30 mol% with respect to the total of all the structural units constituting the copolymer (A1). Preferably 10 to 20 mol% is contained.

  In the present invention, the copolymer (A1) is a copolymer having the structural unit (a1). Examples of the copolymer include the structural units (a1), (a2), and (a3). Examples thereof include copolymers and copolymers composed of the structural units (a1), (a2), (a3) and (a4).

In the component (A), as the copolymer (A1), one type may be used alone, or two or more types may be used in combination.
In the present invention, as the copolymer (A1), those containing the following combinations of structural units are particularly preferable.

［式中、Ｒは前記と同じであり、Ｒ^１０は低級アルキル基である。］

[Wherein, R is the same as defined above, and R ¹⁰ represents a lower alkyl group. ]

In formula (A1-11), the lower alkyl group for R ^{10 is the same as} the lower alkyl group for R, preferably a methyl group or an ethyl group, and most preferably a methyl group.

The copolymer (A1) can be obtained by polymerizing a monomer for deriving each structural unit by a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN). it can.
In the copolymerization (A1), a chain transfer agent such as HS—CH ₂ —CH ₂ —CH ₂ —C (CF ₃ ) ₂ —OH is used in combination in the above polymerization. it may be introduced -C _{(CF 3)} 2 -OH group at the terminal. As described above, a copolymer into which a hydroxyalkyl group in which a part of hydrogen atoms of an alkyl group is substituted with a fluorine atom is introduced has reduced development defects and LER (line edge roughness: uneven unevenness of line side walls). It is effective in reducing

The mass average molecular weight (Mw) (polystyrene conversion standard by gel permeation chromatography) of the copolymer (A1) is not particularly limited, but is preferably 2000 to 50000, more preferably 3000 to 30000, and more preferably 5000 to 20000. Is most preferred. When it is smaller than the upper limit of this range, it has sufficient solubility in a resist solvent to be used as a resist, and the dry etching resistance and resist pattern cross-sectional shape that are larger than the lower limit of this range are good.
Further, the dispersity (Mw / Mn) is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and most preferably 1.2 to 2.5. In addition, Mn shows a number average molecular weight.

<(B) component>
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, poly (bissulfonyl) diazomethanes, and the like. There are various known diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators, and the like.

  As the onium salt acid generator, for example, an acid generator represented by the following general formula (b-0) can be preferably used.

[Wherein, R ⁵¹ represents a linear, branched or cyclic alkyl group, or a linear, branched or cyclic fluorinated alkyl group; R ⁵² represents a hydrogen atom, a hydroxyl group, a halogen atom, linear or A branched alkyl group, a linear or branched halogenated alkyl group, or a linear or branched alkoxy group; R ⁵³ is an aryl group which may have a substituent; u '' Is an integer of 1 to 3. ]

In General Formula (b-0), R ⁵¹ represents a linear, branched, or cyclic alkyl group, or a linear, branched, or cyclic fluorinated alkyl group.
The linear or branched 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 preferably has 4 to 12 carbon atoms, more preferably 5 to 10 carbon atoms, and most preferably 6 to 10 carbon atoms.
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 the number of substituted fluorine atoms to the total number of hydrogen atoms in the alkyl group) is preferably 10 to 100%, more preferably 50 to 100%, particularly hydrogen atoms. Are preferably substituted with a fluorine atom because the strength of the acid is increased.
R ⁵¹ is most preferably a linear alkyl group or a fluorinated alkyl group.

R ⁵² is a hydrogen atom, a hydroxyl group, a halogen atom, a linear or branched alkyl group, a linear or branched alkyl halide group, or a linear or branched alkoxy group.
In R ⁵² , examples of the halogen atom include a fluorine atom, a bromine atom, a chlorine atom, and an iodine atom, and a fluorine atom is preferable.
In R ⁵² , the alkyl group is linear or branched, and the carbon number thereof is preferably 1 to 5, particularly 1 to 4, and more preferably 1 to 3.
In R ⁵² , the halogenated alkyl group is a group in which part or all of the hydrogen atoms in the alkyl group are substituted with halogen atoms. Examples of the alkyl group herein are the same as the “alkyl group” in R ⁵² . Examples of the halogen atom to be substituted include the same as those described above for the “halogen atom”. In the halogenated alkyl group, it is desirable that 50 to 100% of the total number of hydrogen atoms are substituted with halogen atoms, and it is more preferable that all are substituted.
In R ⁵² , the alkoxy group is linear or branched, and the carbon number thereof is preferably 1 to 5, particularly 1 to 4, and more preferably 1 to 3.
Among these, R ⁵² is preferably a hydrogen atom.

R ⁵³ is an aryl group which may have a substituent, and examples of the structure of the basic ring (matrix ring) excluding the substituent include a naphthyl group, a phenyl group, an anthracenyl group, and the like. From the viewpoint of absorption of exposure light such as ArF excimer laser, a phenyl group is desirable.
Examples of the substituent include a hydroxyl group and a lower alkyl group (straight or branched chain, preferably having 5 or less carbon atoms, particularly preferably a methyl group).
As the aryl group for R ^53, an aryl group having no substituent is more preferable.
u ″ is an integer of 1 to 3, preferably 2 or 3, and particularly preferably 3.

  Preferable examples of the acid generator represented by the general formula (b-0) include the following.

  The acid generator represented by general formula (b-0) can be used alone or in combination of two or more.

  As other onium salt-based acid generators represented by the general formula (b-0), for example, compounds represented by the following general formula (b-1) or (b-2) are also preferably used. It is done.

［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 of 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 with a 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 acid generators represented by formulas (b-1) and (b-2) include diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, bis (4-tert-butylphenyl) iodonium. Trifluoromethanesulfonate or nonafluorobutanesulfonate, triphenylsulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or nonafluorobutanesulfonate, tri (4-methylphenyl) sulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or the same Nonafluorobutanesulfonate, dimethyl (4-hydroxynaphthyl) sulfonium trifluoromethanesulfonate, its heptaful Lopropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of monophenyldimethylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of diphenylmonomethylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate (4-methylphenyl) diphenylsulfonium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, (4-methoxyphenyl) diphenylsulfonium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate , Trifluoromethanesulfonate of tri (4-tert-butyl) phenylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of diphenyl (1- (4-methoxy) naphthyl) sulfonium, its heptafluoropropane Examples thereof include sulfonates and nonafluorobutane sulfonates thereof. 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.

  In addition, in the general formula (b-1) or (b-2), an onium salt-based acid generator in which the anion moiety is replaced with an anion moiety represented by the following general formula (b-3) or (b-4). 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 this specification, the oxime sulfonate 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. is there. 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^３１、Ｒ^３２はそれぞれ独立に有機基を表す。）

(In formula (B-1), R ³¹ and R ³² each independently represents an organic group.)

The organic groups of R ³¹ and R ³² are groups containing carbon atoms, and atoms other than carbon atoms (for example, hydrogen atoms, oxygen atoms, nitrogen atoms, sulfur atoms, halogen atoms (fluorine atoms, chlorine atoms, etc.), etc.) You may have.
As the organic group for R ³¹ , a linear, branched, or cyclic alkyl group or aryl group is preferable. 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 ³¹ is particularly preferably an alkyl group having 1 to 4 carbon atoms having no substituent or a fluorinated alkyl group having 1 to 4 carbon atoms.

As the organic group for R ³² , a linear, branched, or cyclic alkyl group, aryl group, or cyano group is preferable. As the alkyl group and aryl group for R ^32, the same alkyl groups and aryl groups as those described above for R ³¹ can be used.
R ³² 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^３３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^３４はアリール基である。Ｒ^３５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 ³³ represents a cyano group, an alkyl group having no substituent, or a halogenated alkyl group. R ³⁴ is an aryl group. R ³⁵ represents an alkyl group having no substituent or a halogenated alkyl group. ]

［式（Ｂ−３）中、Ｒ^３６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^３７は２または３価の芳香族炭化水素基である。Ｒ^３８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 Formula (B-3), R ³⁶ represents a cyano group, an alkyl group having no substituent, or a halogenated alkyl group. R ³⁷ is a divalent or trivalent aromatic hydrocarbon group. ^R38 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 of R ³³ preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and carbon atoms. Numbers 1 to 6 are most preferable.
R ³³ is preferably a halogenated alkyl group, more preferably a fluorinated alkyl group.
The fluorinated alkyl group for R ³³ is preferably such that the hydrogen atom of the alkyl group is 50% or more fluorinated, more preferably 70% or more, and still more preferably 90% or more.

As the aryl group of R ³⁴ , 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, or a phenanthryl group. 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 of R ³⁴ 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 ³⁵ preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 6 carbon atoms.
R ³⁵ 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 ³⁵ preferably has 50% or more of the hydrogen atom of the alkyl group fluorinated, 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 ³⁶ is the same as the alkyl group or halogenated alkyl group having no substituent for R ^33. Is mentioned.
Examples of the divalent or trivalent aromatic hydrocarbon group for R ³⁷ include groups obtained by further removing one or two hydrogen atoms from the aryl group for R ³⁴ .
Examples of the alkyl group or halogenated alkyl group having no substituent of R ³⁸ include the same alkyl groups or halogenated alkyl groups as those having no substituent of R ³⁵ .
p ″ is preferably 2.

Specific examples of the oxime sulfonate acid generator 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-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -2,6-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -4-methoxybenzyl cyanide, 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 N-tenyl 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.
Further, an oxime sulfonate-based acid generator disclosed in JP-A-9-208554 (paragraphs [0012] to [0014] [chemical formula 18] to [chemical formula 19]), WO2004 / 074242A2 (pages 65 to 85). The oxime sulfonate acid generators disclosed in Examples 1 to 40) of No. 1 can also be suitably used.
Moreover, the following can be illustrated as a suitable thing.

  Of the above exemplified compounds, the following four 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.
Further, diazomethane acid generators disclosed in JP-A-11-035551, JP-A-11-035552, and JP-A-11-035573 can also be suitably used.
Examples of poly (bissulfonyl) diazomethanes include 1,3-bis (phenylsulfonyldiazomethylsulfonyl) propane and 1,4-bis (phenylsulfonyldiazo) disclosed in JP-A-11-322707. Methylsulfonyl) butane, 1,6-bis (phenylsulfonyldiazomethylsulfonyl) hexane, 1,10-bis (phenylsulfonyldiazomethylsulfonyl) decane, 1,2-bis (cyclohexylsulfonyldiazomethylsulfonyl) ethane, 1,3 -Bis (cyclohexylsulfonyldiazomethylsulfonyl) propane, 1,6-bis (cyclohexylsulfonyldiazomethylsulfonyl) hexane, 1,10-bis (cyclohexylsulfonyldiazomethylsulfonyl) decane, etc. Door can be.

(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.
In the present invention, it is particularly preferable to use an onium salt having a fluorinated alkyl sulfonate ion as an anion as the component (B). In particular, an onium salt-based acid generator represented by the above formula (b-1) is preferred, and triphenylsulfonium nonafluorobutanesulfonate (TPS-PFBS) is most preferred.
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.

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

<(O) component>
・ Unit (O1-1)
In the present invention, the component (O) is a resin (O1) containing a structural unit (O1-1) derived from hydroxystyrene and having no acid dissociable, dissolution inhibiting group.
Since the (O1) component has a structural unit (O1-1) derived from hydroxystyrene, it has an absorptivity for light near 193 nm. Therefore, it is preferably used in a resist pattern forming method in which exposure is performed using an ArF excimer laser. By including the (O1) component in the resist film, it is possible to reduce adverse effects on the resist pattern shape due to standing waves generated by reflection from the substrate during exposure and irregular reflection due to steps on the substrate surface.

“Hydroxystyrene” in the structural unit (O1-1) is hydroxystyrene, and those obtained by replacing the hydrogen atom at the α-position of hydroxystyrene with another substituent such as a halogen atom, an alkyl group, or a halogenated alkyl group, And further including a derivative in which one or two of the hydrogen atoms in the benzene ring are substituted with a hydroxyl group, and a derivative in which one or two of the hydrogen atoms in the benzene ring are substituted with an alkyl group; To do. The “structural unit derived from hydroxystyrene” means a structural unit formed by cleavage of an ethylenic double bond of hydroxystyrene. Note that the “α-position (α-position carbon atom) of a structural unit derived from hydroxystyrene” is a carbon atom to which a benzene ring is bonded, unless otherwise specified.
As the structural unit (O1-1), structural units represented by general formula (o1-1) shown below can be exemplified.

［上記式中、Ｒ^１は水素原子、炭素数１〜５の低級アルキル基、フッ素原子またはフッ素化低級アルキル基を表し；Ｒ^２は炭素数１〜５の低級アルキル基を表し；ｐは１〜３の整数を表し；ｑは０または１〜２の整数を表す。］

[Wherein R ¹ represents a hydrogen atom, a lower alkyl group having 1 to 5 carbon atoms, a fluorine atom or a fluorinated lower alkyl group; R ² represents a lower alkyl group having 1 to 5 carbon atoms; Represents an integer of -3; q represents 0 or an integer of 1-2. ]

In general formula (o1-1), R ¹ represents a hydrogen atom, a lower alkyl group, a fluorine atom or a fluorinated lower alkyl group.
The lower alkyl group for R ^{1 is} an alkyl group having 1 to 5 carbon atoms, and is preferably a linear or branched alkyl group, and includes a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, and an isobutyl group. Tert-butyl group, pentyl group, isopentyl group, neopentyl group and the like. Industrially, a methyl group is preferable.
The fluorinated lower alkyl group is one in which part or all of the hydrogen atoms of the above-mentioned lower alkyl group having 1 to 5 carbon atoms are substituted with fluorine atoms. In the present invention, it is preferable that all hydrogen atoms are fluorinated. The fluorinated lower alkyl group is preferably a linear or branched fluorinated lower alkyl group, more preferably a trifluoromethyl group, a hexafluoroethyl group, a heptafluoropropyl group, a nonafluorobutyl group, or the like. The group (—CF ₃ ) is most preferred.
R ¹ is preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom.

Examples of the lower alkyl group having 1 to 5 carbon atoms of R ² include the same as the lower alkyl group of R ¹ .
q is 0 or an integer of 1-2. Of these, q is preferably 0 or 1, and particularly preferably 0 industrially.
The substitution position of R ² may be any of the o-position, m-position and p-position when q is 1, and when q is 2, any substitution position may be combined. it can.
p is an integer of 1 to 3, preferably 1.
The substitution position of the hydroxyl group may be any of the o-position, m-position and p-position when p is 1, but the p-position is preferred because it is readily available and inexpensive. Furthermore, when p is 2 or 3, arbitrary substitution positions can be combined.

The structural unit (O1-1) can be used alone or in combination of two or more.
In the component (O1), the proportion of the structural unit (O1-1) is preferably 50 mol% or more, more preferably 60 mol% or more, and more preferably 70 mol% or more with respect to all the structural units constituting the (O1) component. Most preferred. Within this range, the effect of reducing the dimensional variation of the resist pattern with respect to the resist film thickness is good, and good alkali solubility is obtained. The upper limit of the proportion of the structural unit (O1-1) in the component (O1) may be 100 mol%. 90 mol% or less is preferable from the point of the effect of this invention, and 85 mol% or less is more preferable.

・ Structural unit (O1-2)
The component (O1) preferably further contains a structural unit (O1-2) derived from a styrene unit. The structural unit (O1-2) is not essential, but has an absorptivity with respect to light near 193 nm, and by containing this, the heat resistance of the resist pattern can be improved. In particular, in the implantation process, the resist pattern on the substrate is heated by the exothermic action caused by the implantation of impurities, so that the resist pattern undergoes a shape change, or a certain component in the resist pattern is gasified and vacuumed in the processing chamber. In order to prevent these problems, it is preferable that the resist pattern has high heat resistance.
Here, the term “styrene” refers to styrene and those in which the α-position hydrogen atom of styrene is substituted with another substituent such as a halogen atom, an alkyl group, an alkyl halide group, and further a hydrogen atom of a benzene ring. The concept includes a derivative in which 1 to 3 of them are substituted with an alkyl group. “Structural unit derived from styrene” means a structural unit formed by cleavage of an ethylenic double bond of styrene. In styrene, the hydrogen atom of the phenyl group may be substituted with a substituent such as a lower alkyl group.
As the structural unit (O1-2), structural units represented by general formula (o1-2) shown below can be exemplified.

［式中、Ｒ^１は水素原子、炭素数１〜５の低級アルキル基、フッ素原子またはフッ素化低級アルキル基を表し；Ｒ^３は炭素数１〜５の低級アルキル基を表し；ｒは０または１〜３の整数を表す。］

[Wherein R ¹ represents a hydrogen atom, a lower alkyl group having 1 to 5 carbon atoms, a fluorine atom or a fluorinated lower alkyl group; R ³ represents a lower alkyl group having 1 to 5 carbon atoms; Represents an integer of 1 to 3; ]

In formula (o1-2), examples of R ¹ and R ³ include the same as R ¹ and R ^{2 in} formula (o1-1).
r is 0 or an integer of 1 to 3. Of these, r is preferably 0 or 1, and particularly preferably 0 industrially.
The substitution position of R ³ may be any of the o-position, m-position and p-position when r is 1 to 3, and any substitution position may be combined when r is 2 or 3. it can.

As the structural unit (O1-2), one type may be used alone, or two or more types may be used in combination.
When the component (O1) has the structural unit (O1-2), the proportion of the structural unit (O1-2) is preferably 5 to 50 mol% with respect to all the structural units constituting the component (O1). 40 mol% is more preferable, and 10 to 30 mol% is most preferable. Within this range, the effect of having the structural unit (O1-2) is high, and the balance with other structural units is also good.

The component (O1) may be a copolymer having the structural units (O1-1) and (O1-2), or may be a mixture of polymers having one or more of these structural units. In particular, a copolymer having both of the structural units (O1-1) and (O1-2) is preferable because of excellent effects of the present invention.
The component (O1) can be obtained by polymerizing a monomer for deriving each structural unit by a conventional method, for example, a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN). it can.

  1000-5000 are preferable, as for the mass average molecular weight of (O1) component, 1500-4500 are more preferable, and 2000-4000 are the most preferable. When the mass average molecular weight is at least the lower limit of the above range, a good degree of dispersion in the entire resin component contained in the resist composition can be obtained, and a good shape of the resist pattern can be obtained. If the amount is not more than the upper limit of the above range, the radiation absorption capacity per molecule of the (O1) component is appropriately reduced, so that it is easy to control the radiation absorption amount by adjusting the addition amount of the (O1) component.

The content of the (O1) component in the positive resist composition of the present invention is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5.0 parts by mass with respect to 100 parts by mass of the (A) component. Preferably, 0.5-3 mass parts is more preferable, and 0.5-1 mass part is the most preferable.
In particular, at the time of exposure, when an antireflection film is provided on the upper layer of the resist film, the content of the (O1) component is preferably 0.1 to 5.0 parts by mass, Part by mass is more preferable. When the antireflection film is not provided, the content of the component (O1) is preferably 5.0 to 10 parts by mass, and more preferably 7.0 to 10 parts by mass.
By making the content of the (O1) component not less than the lower limit of the above range, the effect of adding the (O1) component is improved, and by making the content not more than the upper limit of the above range, excessive radiation due to the (O1) component Absorption is prevented, and dimensional fluctuations of the resist pattern due to changes in the resist film thickness can be suppressed appropriately.

<Optional component>
In the positive resist composition of the present invention, an organic carboxylic acid or an oxo acid of phosphorus or a derivative thereof (E) is used as an optional component for the purpose of preventing sensitivity deterioration and improving the resist pattern shape, retention stability, and the like. ) (Hereinafter referred to as component (E)).
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) When it contains a component, it is preferable to mix | blend in the ratio of 0.01-5.0 mass parts per 100 mass parts of (A) component.

  The positive resist composition of the present invention may further contain miscible additives as desired, for example, an additional resin for improving the performance of the resist film, a surfactant for improving coating properties, a dissolution inhibitor, A plasticizer, a stabilizer, a colorant, an antihalation agent, a dye not included in the component (O1) in the present invention, and the like can be appropriately added and contained.

The positive resist composition of the present invention can be produced by dissolving the material in an organic solvent (hereinafter sometimes referred to as (S) component).
As the component (S), any component can be used as long as it can dissolve each component to be used to form a uniform solution. Conventionally, any one of known solvents for chemically amplified resists can be used. Two or more types can be appropriately selected and used.
For example, lactones such as γ-butyrolactone;
Ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl-n-amyl ketone, methyl isoamyl ketone, 2-heptanone;
Polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol and dipropylene glycol and derivatives thereof;
Compounds having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate or dipropylene glycol monoacetate, monomethyl ether, monoethyl ether, monopropyl of the polyhydric alcohols or the compound having an ester bond Derivatives of polyhydric alcohols such as ethers, monoalkyl ethers such as monobutyl ether or compounds having an ether bond such as monophenyl ether;
Cyclic ethers such as dioxane and esters such as methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, etc. Can be mentioned.
These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
Among these, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), and EL are preferable.

Moreover, the mixed solvent which mixed PGMEA and the 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 1: 9 to 5: 5, and 1: 9. ~ 4: 6 is most preferred.
In particular, it is most preferable to use a mixed solvent of PGMEA and EL as the component (S).
The amount of the component (S) used is not particularly limited, but is a concentration that can be applied to a substrate or the like, and is appropriately set according to the coating film thickness. In general, the solid content concentration of the resist composition is 2 -20% by mass, preferably 5-15% by mass.

The positive resist composition of the present invention can form a resist pattern having a small dimensional variation with respect to the resist film thickness.
In addition, since the component (O1) used as the compound (O) having radiation absorbing ability in the present invention is a resin, it is less likely to sublimate when heated compared to a low molecular weight dye. For this reason, environmental pollution during heating and adhesion of dust on the substrate are prevented.
Further, as shown in the examples described later, according to the positive resist composition of the present invention, the roughness on the side wall of the resist pattern is improved, a resist pattern having a good shape is obtained, and an EL margin (exposure amount) is obtained. Margin) is also improved.

The positive resist composition of the present invention is capable of forming a fine resist pattern having a small dimensional variation with respect to the resist film thickness even when the film thickness of the resist film is as thin as 500 nm or less, or when there is no antireflection film in the lower layer of the resist film. Can be formed. Therefore, the positive resist composition of the present invention can be used for a thin film implantation process.
That is, since the resist pattern used in the thin film implantation process is used as a mask for implanting impurity ions, as described above, the present invention can form a fine pattern with a small dimensional change and a good shape with good reproducibility. The positive resist composition is suitable for a thin film implantation process.

  The reason why these effects can be obtained is not clear, but the compound (O) having a radiation absorbing ability in the positive resist composition contains a structural unit (O1-1) derived from hydroxystyrene, and therefore has a wavelength particularly. It is considered that the absorption of light near 193 nm and the good solubility of the resist composition in the solvent have a great influence.

≪Resist pattern formation method≫
A method of forming a resist pattern using the positive resist composition 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 prebaking (PAB) is performed at a temperature of 80 to 150 ° C. for 40 to 120 seconds, preferably 60 to 90 seconds. To form a resist film. Next, the resist film is selectively exposed to ArF excimer laser light through a desired mask pattern by, for example, an ArF exposure apparatus, and then subjected to PEB (post-exposure heating) at a temperature of 80 to 150 ° C. Is applied for 40 to 120 seconds, preferably 60 to 90 seconds. Subsequently, this is developed using an alkali developer, for example, an aqueous solution of 0.1 to 10% by mass of tetramethylammonium hydroxide. In this way, a resist pattern faithful to the mask pattern can be obtained.
An organic or inorganic antireflection film may be provided between the substrate and the coating layer of the resist composition or on the resist film.
The wavelength used for exposure is not particularly limited, and ArF excimer laser, KrF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), EB (electron beam), X-ray, soft X-ray Or the like. The positive resist composition according to the present invention is particularly effective for an ArF excimer laser.

The positive resist composition of the present invention can be applied to a method for forming a resist pattern having a normal film thickness. In particular, even when the resist film thickness is as thin as 500 nm or less, the anti-reflection is applied to the lower layer of the resist film. Even when a film is not provided, a fine resist pattern having a small dimensional variation with respect to the resist film thickness can be satisfactorily formed, and therefore can be suitably used for a method of forming a resist pattern for a thin film implantation process.
In the resist pattern forming method, a resist pattern suitable for a thin film implantation process can be obtained by setting the thickness of the resist film to 500 nm or less and exposing and developing the resist film by the above method. For the thin film implantation process, a more preferable film thickness of the resist film is 100 to 500 nm, and more preferably 200 to 500 nm.
In the implantation process, an antireflection film cannot be provided below the resist film, but an antireflection film can be provided above the resist film.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited by these examples.

[Examples 1 and 2, Comparative Example 1]
Each component shown in Table 1 was mixed and dissolved to prepare a positive resist composition solution.

Each abbreviation in Table 1 has the following meaning. Moreover, the numerical value in [] is a compounding quantity (mass part).
(A) -1: a copolymer represented by the following formula (A) -1, wherein p: q: r: s = 40: 40: 15: 5 (molar ratio), Mw = 10000, Mw / Mn = 2.0.
(B) -1: triphenylsulfonium nonafluorobutanesulfonate (D) -1: triethanolamine (O) -1: a copolymer represented by the following formula (O) -1, m: n = 75:25 (molar ratio), Mw = 3000.
(S) -1: Mixed solvent of PGMEA / EL = 1/9 (mass ratio)

(Evaluation)
The following evaluation was performed using the positive resist composition solution obtained above.
[SW evaluation]
Using a spinner, uniformly apply the positive resist composition solution obtained in Examples 1 and 2 or Comparative Example 1 onto an 8-inch silicon wafer that has been surface-treated with hexamethyldisilazane (HMDS). The resist film having a predetermined film thickness was formed by applying, pre-baking on a hot plate at 120 ° C. for 60 seconds, and drying. On the resist film, “TILC-006” (trade name; manufactured by Tokyo Ohka Kogyo Co., Ltd.) is uniformly applied using a spinner and heated at 90 ° C. for 60 seconds to form an antireflection film having a thickness of 30 nm. Formed.
Subsequently, selective exposure was performed through a 6% halftone mask using an ArF exposure apparatus (wavelength: 193 nm) S-302A (manufactured by Nikon, NA (numerical aperture) = 0.60, 2/3 ring zone).
Then, PEB treatment was performed at 130 ° C. for 60 seconds, and further developed at 23 ° C. with a 2.38 mass% tetramethylammonium hydroxide aqueous solution for 30 seconds. At this time, a scan type LD nozzle was used. Thereafter, water rinsing was performed using pure water, followed by shake-off drying. In this way, a 135 nm line and space (1: 1) resist pattern (hereinafter referred to as an L / S pattern), an isolated line pattern with a line width of 135 nm, and a trench pattern (isolated space pattern) with a space width of 135 nm are formed. did.

The film thickness of the resist film is set to 350 to 470 nm, and each of the three types of resist patterns, that is, the L / S pattern, the isolated line pattern, and the trench pattern, is formed at each film thickness, and the pattern dimensions ( Hereinafter, it was referred to as CD). In the L / S pattern and the isolated line pattern, the line width is CD, and in the trench pattern, the space width is CD. The measurement results of CD are shown in FIGS. 1 is a graph showing the measurement results for the L / S pattern, FIG. 2 is a graph showing the measurement results for the isolated line pattern, and FIG. 3 is a graph showing the measurement results for the trench pattern. In each figure, (A) shows the results of Comparative Example 1, (B) shows the results of Example 1, and (C) shows the results of Example 2.
Furthermore, the value of the amplitude of the waveform shown in the graphs of FIGS. 1 to 3 was obtained as SWE (Standing Wave Effect). The smaller the SWE, the smaller the dimensional variation of the resist pattern with respect to the resist film thickness. The results are shown in Table 2 below.

[Shape evaluation]
The cross-sectional shape of each L / S pattern obtained above was observed with a scanning electron microscope (length measurement SEM, S-9200) manufactured by Hitachi. In any film thickness, compared with Comparative Example 1, Examples 1 and 2 had less unevenness on the surface of the side wall and were smoother. That is, in the example according to the present invention, the roughness of the resist pattern was improved.

[EL margin evaluation]
Using a spinner, uniformly apply the positive resist composition solution obtained in Examples 1 and 2 or Comparative Example 1 onto an 8-inch silicon wafer that has been surface-treated with hexamethyldisilazane (HMDS). The resist film having a thickness of 390 nm was formed by coating, pre-baking on a hot plate at 120 ° C. for 60 seconds, and drying. On the resist film, a water-soluble antireflection film material was uniformly applied using a spinner to form an antireflection film having a thickness of 35 nm.
Subsequently, selective exposure was performed through a binary mask using an ArF exposure apparatus (wavelength: 193 nm) S-302A (manufactured by Nikon, NA (numerical aperture) = 0.60, σ = 0.75).
Then, PEB treatment was performed under conditions of 130 ° C. for 60 seconds, and further developed with a 2.38 mass% tetramethylammonium hydroxide aqueous solution at 23 ° C. for 30 seconds. Thereafter, water rinsing was performed using pure water, followed by shake-off drying. In this way, a 150 nm line and space (1: 1) resist pattern (hereinafter referred to as L / S pattern) was formed.

With respect to the obtained 150 nm L / S pattern, the change amount (unit: nm / mJ) of the pattern size per 1 mJ of exposure amount was measured in the range of the exposure amount obtained within the pattern size range of 150 nm ± 15%. Then, the ratio of the exposure amount width obtained in the pattern size range of 150 nm ± 15% to the optimum exposure amount (Eop) was calculated as the EL margin (exposure amount margin) (unit:%) by the following formula.
EL margin (%) = (| E ₁ −E ₂ | / Eop) × 100
Exposure amount when forming a pattern of E ₁ = 172.5 nm (mJ / cm ² )
Exposure amount when forming a pattern of E ₂ = 127.5 nm (mJ / cm ² )
The results are shown in Table 2 below.
Note that the larger the EL margin, the smaller the change amount of the pattern size accompanying the variation in the exposure amount.

From the results in Table 2, compared to Comparative Example 1, in Examples 1 and 2, the resist pattern dimensional variation (SW) with respect to the resist film thickness was reduced. Further, the effect of reducing the SW is higher in the second embodiment than in the first embodiment.
In addition, compared with Comparative Example 1, in Examples 1 and 2, the EL margin was improved, and the change amount of the pattern size accompanying the change in the exposure amount was reduced.

It is a graph which shows the result of SW evaluation concerning an Example and a comparative example. It is a graph which shows the result of SW evaluation concerning an Example and a comparative example. It is a graph which shows the result of SW evaluation concerning an Example and a comparative example.

Claims (4)

A positive resist composition comprising a resin component (A) whose alkali solubility is increased by the action of an acid, an acid generator component (B) which generates an acid upon irradiation with radiation, and a compound (O) having a radiation absorbing ability Because
The component (A) is a structural unit (a1) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group, a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group, A structural unit (a3) derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group, and a structural unit (a4) derived from an acrylate ester containing a non-acid-dissociable aliphatic polycyclic group; A copolymer (A1) comprising:
Wherein (O) component containing a structural unit (O1-1) derived from hydroxystyrene, no acid dissociable, dissolution inhibiting group resin (O1) der is,
The (O1) content of the component, wherein the component (A) 100 parts by weight, a positive resist composition comprising 0.1 to 10 parts by der Rukoto. The (O1) component, the positive resist composition according to claim 1 Symbol mounting further comprising a structural unit derived from styrene units (O1-2). The positive resist composition according to claim 1 or 2 which is for a thin-film implantation process. A step of forming a resist film having a film thickness of 500 nm or less on a substrate using the positive resist composition according to any one of claims 1 to 3 , a step of exposing the resist film, and developing the resist film A resist pattern forming method including a step of forming a resist pattern.

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