JP2006219555A - Polymer compound, positive type resist composition and method for forming resist pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a positive type resist composition that forms a pattern having excellent resolving power and a polymer compound suitable for the positive type resist composition and to provide a method for forming a resist pattern useful in the positive type resist composition. <P>SOLUTION: The polymer compound comprises a constituent unit (a1) derived from a hydroxystyrene and a constituent unit (a2) represented by general formula (a2-1) or (a2-2) (Z is an aliphatic cyclic group; n is an integer of 0 or 1-3; m is 0 or 1; Rs are each independently a hydrogen atom, a 1-5C lower alkyl group, a fluorine atom or a fluorinated lower alkyl group; R<SP>1</SP>and R<SP>2</SP>are each independently a hydrogen atom or a 1-5C lower alkyl group). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polymer compound, 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.

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.
The resin component of the chemically amplified positive resist composition is mainly composed of a resin in which the hydroxyl group of a polyhydroxystyrene (PHS) resin is protected with an acid dissociable, dissolution inhibiting group, or a structural unit derived from (meth) acrylic acid. A resin in which a carboxy group of a resin (acrylic resin) in a chain is protected with an acid dissociable, dissolution inhibiting group is generally used.
Examples of acid dissociable, dissolution inhibiting groups include so-called acetal groups such as chain ether groups typified by 1-ethoxyethyl groups and cyclic ether groups typified by tetrahydropyranyl groups; third groups typified by tert-butyl groups. A tertiary alkyl group; a tertiary alkoxycarbonyl group typified by a tert-butoxycarbonyl group is used (for example, see Patent Document 1).
JP 2002-341538 A

However, a conventional resist using a PHS-based resin having a tertiary alkyl group or a tertiary alkoxycarbonyl group as an acid dissociable dissolution inhibiting group has a difference in alkali solubility (dissolution contrast between an exposed area and an unexposed area). ) Is small and the resolution is not sufficient.
The present invention has been made in view of the above circumstances, and is a positive resist composition capable of forming a pattern with excellent resolution, a polymer compound suitable for the positive resist composition, and the positive type It is an object of the present invention to provide a resist pattern forming method using a resist composition.

  A first aspect of the present invention that solves the above problems is the structural unit (a1) derived from hydroxystyrene and the following general formula (a2-1) or (a2-2):

［上記式中、Ｚは脂肪族環式基を表し；ｎは０または１〜３の整数を表し；ｍは０または１を表し；Ｒはそれぞれ独立して水素原子、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^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。］
で表される構成単位（ａ２）とを含むこと特徴とする高分子化合物である。

[In the above formula, Z represents an aliphatic cyclic group; n represents an integer of 0 or 1 to 3; m represents 0 or 1; and R independently represents a hydrogen atom or a carbon number of 1 to 5] A lower alkyl group, a fluorine atom or a fluorinated lower alkyl group; R ¹ and R ² each independently represent a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms; ]
It is a high molecular compound characterized by including the structural unit (a2) represented by these.

The second aspect of the present invention is a positive resist composition comprising a resin component (A) whose alkali solubility is increased by the action of an acid, and an acid generator component (B) that generates an acid upon exposure,
The resin component (A) is a structural unit (a1) derived from hydroxystyrene and the following general formula (a2-1) or (a2-2)

［上記式中、Ｚは脂肪族環式基を表し；ｎは０または１〜３の整数を表し；ｍは０または１を表し；Ｒはそれぞれ独立して水素原子、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^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。］
で表される構成単位（ａ２）とを含む高分子化合物を含有すること特徴とするポジ型レジスト組成物である。

[In the above formula, Z represents an aliphatic cyclic group; n represents an integer of 0 or 1 to 3; m represents 0 or 1; and R independently represents a hydrogen atom or a carbon number of 1 to 5] A lower alkyl group, a fluorine atom or a fluorinated lower alkyl group; R ¹ and R ² each independently represent a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms; ]
A positive resist composition comprising a polymer compound containing the structural unit (a2) represented by formula (1).

  According to a third aspect of the present invention, there is provided a step of forming a resist film on a substrate using the positive resist composition of the second aspect, a step of exposing the resist film, and developing the resist film to form a resist pattern It is a resist pattern formation method including the process of forming.

In the present specification and claims, the “structural unit” means a monomer unit (monomer unit) constituting the polymer compound.
The “alkyl group” includes a linear, branched or cyclic monovalent saturated hydrocarbon group unless otherwise specified.
“Exposure” is a concept that includes general irradiation of radiation, and includes irradiation of an electron beam.

  The present invention can provide a positive resist composition capable of forming a pattern with excellent resolution, a polymer compound suitable for the positive resist composition, and a resist pattern forming method using the positive resist composition. .

<Polymer compound>
The polymer compound of the present invention (hereinafter referred to as polymer compound (A1)) is represented by the structural unit (a1) derived from hydroxystyrene and the general formula (a2-1) or (a2-2). And a structural unit (a2).

Structural unit (a1)
The structural unit (a1) is a structural unit derived from hydroxystyrene.
In the present invention, it is necessary to have the structural unit (a1). A combination of the structural unit (a1) and the structural unit (a2) described later can form a pattern having a large exposure margin and excellent resolution when forming a resist pattern. Moreover, dry etching tolerance improves by having a structural unit (a1). Furthermore, there is an advantage that hydroxystyrene as a raw material is easily available and is inexpensive.
As used herein, “hydroxystyrene” refers to 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 derivatives thereof. Include concepts. The “structural unit derived from hydroxystyrene” means a structural unit formed by cleavage of the ethylenic double bond of hydroxystyrene.
Examples of the structural unit (a1) include structural units represented by the following general formula (a-1).

［上記式中、Ｒ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；ｏは１〜３の整数を表し；ｐは０または１〜２の整数を表す。］

[In the above formula, R 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 3; p represents 0 or an integer of 1 to 2; ]

In general formula (a-1), R represents a hydrogen atom, a lower alkyl group having 1 to 5 carbon atoms, a fluorine atom, or a fluorinated lower alkyl group.
The fluorinated lower alkyl group is a group in which part or all of the hydrogen atoms in the alkyl group are substituted with fluorine atoms, and any of them may be used, but it is preferable that all are fluorinated.
Preferable examples of the lower alkyl group as R include methyl group, ethyl group, propyl group, 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 fluorinated lower alkyl group having 1 to 5 carbon atoms is preferably a trifluoromethyl group, a hexafluoroethyl group, a heptafluoropropyl group, a nonafluorobutyl group, or the like, and more preferably a trifluoromethyl group.
Examples of the lower alkyl group having 1 to 5 carbon atoms of R ³ include those similar to the lower alkyl group having 1 to 5 carbon atoms of R.
o is an integer of 1 to 3, preferably 1. When o 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 o is 2 or 3, arbitrary substitution positions can be combined.
p is 0 or an integer of 1-2. Of these, p is preferably 0 or 1, and particularly preferably 0 industrially. When p is 1, the substitution position of R ³ may be any of the o-position, m-position, and p-position, and when p is 2, any substitution position is combined. Can do.

  In the polymer compound (A1), the proportion of the structural unit (a1) is preferably 10 to 80 mol%, more preferably 20 to 75, with respect to all the structural units constituting the polymer compound (A1). 40-70 mol% is still more preferable, and 50-65 mol% is the most preferable. Within this range, moderate alkali solubility is obtained, and the balance with other structural units is good.

Structural unit (a2)
The polymer compound (A1) of the present invention has the structural unit (a2) represented by the general formula (a2-1) or (a2-2).
The structural unit (a2) is a structural unit derived from acrylic acid, and an acetal group (alkoxyalkyl group) is bonded to an oxygen atom at the terminal of a carbonyloxy group (—C (O) —O—) derived from a carboxy group. ) Type acid dissociable, dissolution inhibiting group [—C (R ¹ R ² ) —O— (CH ₂ ) _n —Z]. Therefore, when an acid acts, a bond is cut between the acid dissociable, dissolution inhibiting group and the terminal oxygen atom.
Therefore, the polymer compound (A1) of the present invention is insoluble in alkali before the acid is allowed to act, and when the acid is allowed to act, the above acid dissociable, dissolution inhibiting group is dissociated, whereby the polymer compound (A1) as a whole Can change to alkali-soluble.
In addition, the deprotection energy of such an acetal group (alkoxyalkyl group) type acid dissociable, dissolution inhibiting group is lower than that of a tertiary ester type acid dissociable, dissolution inhibiting group, and therefore has a structural unit (a2). Thus, even if the acid strength is weak, there is an advantage that the acid dissociable, dissolution inhibiting group can be eliminated to increase the alkali solubility and to resolve a fine pattern. Further, since the deprotection energy is low, the acid strength as a catalyst can be weakened, so that there is an advantage that the selection range of the acid generator can be expanded. Specifically, for example, a diazomethane acid generator, an acid generator having a camphorsulfonic acid ion in the anion portion, an oxime sulfonate acid generator, or the like can also be dissociated.

Here, “structural unit derived from acrylic acid” means a structural unit formed by cleavage of an ethylenic double bond of acrylic acid, and “structural unit derived from acrylic acid” A structural unit in which the hydrogen atom bonded to the carbon atom at the α-position is substituted with another substituent such as a halogen atom, an alkyl group, or a halogenated alkyl group, or acrylic acid in which the hydrogen atom is bonded to the carbon atom at the α-position Also included are structural units derived from esters.
“A structural unit derived from an acrylate ester” means a structural unit formed by cleavage of an ethylenic double bond of an acrylate ester, and “a structural unit derived from an acrylate ester” Also included are those in which the hydrogen atom at the α-position is substituted with another substituent such as a halogen atom, an alkyl group or a halogenated alkyl group.
In the “structural unit derived from acrylic acid” and “structural unit derived from acrylate ester”, the term “α-position (α-position carbon atom)” means that a carboxy group is present unless otherwise specified. It is a bonded carbon atom.

In general formulas (a2-1) and (a2-2), each R is independently a hydrogen atom, a lower alkyl group having 1 to 5 carbon atoms, a fluorine atom or a fluorinated lower alkyl group having 1 to 5 carbon atoms. , R includes the same as R in the general formula (a-1).
R ¹ and R ² are each independently a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms. Specific examples of the lower alkyl group for R ¹ and R ² 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. And a lower linear or branched alkyl group. The lower alkyl group is preferably a methyl group or an ethyl group in terms of industrial availability. Since R ¹ and R ² are excellent in the effects of the present invention, at least one of them is preferably a hydrogen atom, and more preferably both are hydrogen atoms.
n is preferably 0 or an integer of 1 to 3, preferably 0 or 1, and most preferably 1.
m is 0 or 1, preferably 1.

Z represents an aliphatic cyclic group, an aliphatic cyclic group having 20 or less carbon atoms is preferable, and an aliphatic cyclic group having 5 to 12 carbon atoms is more preferable. Here, “aliphatic” in the present specification and claims is a relative concept with respect to aromatics, and is defined to mean groups, compounds, and the like that do not have aromaticity. The “aliphatic cyclic group” means a monocyclic group or a polycyclic group having no aromaticity. The aliphatic cyclic group may be saturated or unsaturated, but is usually preferably saturated.
Z 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, a hydrophilic group, and the like. Examples of the hydrophilic group include ═O, —COOR (R is an alkyl group), alcoholic hydroxyl group, —OR (R is an alkyl group), imino group, amino group, and the like. O or an alcoholic hydroxyl group is preferred.
The structure of the basic ring (basic ring) excluding the substituent in the aliphatic cyclic group may be a ring consisting of carbon and hydrogen (hydrocarbon ring), and the carbon atoms constituting the hydrocarbon ring A heterocyclic ring partially substituted with a hetero atom such as a sulfur atom, an oxygen atom, or a nitrogen atom may be used. For the effect of the present invention, the basic ring in Z is preferably a hydrocarbon ring.
The hydrocarbon ring can be appropriately selected from among many proposed KrF resists, ArF resists, and the like. Specifically, monocycloalkane, bicycloalkane, tricycloalkane, tetracyclo Examples include polycycloalkanes such as alkanes. Examples of the monocycloalkane include cyclopentane and cyclohexane. Examples of the polycycloalkane include adamantane, norbornane, norbornene, methylnorbornane, ethylnorbornane, methylnorbornene, ethylnorbornene, isobornane, tricyclodecane, and tetracyclododecane. Among these, cyclohexane, cyclopentane, adamantane, norbornane, norbornene, methylnorbornane, ethylnorbornane, methylnorbornene, ethylnorbornene, and tetracyclododecane are industrially preferable, and adamantane is more preferable.

Examples of the acid dissociable, dissolution inhibiting group represented by the formula —C (R ¹ R ² ) —O— (CH ₂ ) _n —Z include groups represented by the following formulas (4) to (15). It is done.

  More specifically, the structural unit (a2) is represented by, for example, the following general formulas (a2-1-1) to (a2-1-16), (a2-2-1) to (a2-1-22). The structural unit is given.

  In the present invention, it is particularly preferable to have the structural unit (a2-1) as the structural unit (a2) because the effects of the present invention are excellent. Among them, formula (a2-1-9), formula (a2-1-10), formula (a2-1-13), formula (a2-1-14), formula (a2-1-15), formula (a2) The structural unit represented by -1-16) is preferable because the effect of the present invention is excellent.

  In the polymer compound (A1), the proportion of the structural unit (a2) is preferably 5 to 50 mol%, more preferably 10 to 40 mol%, based on all structural units constituting the polymer compound (A1). More preferred is ~ 35 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, the balance with other structural units is good. Moreover, it is excellent in an exposure margin by setting it as the said range.

The polymer compound (A1) may further have a structural unit (a3) derived from styrene in addition to the structural units (a1) and (a2).
In the present invention, the structural unit (a3) is not essential, but if it is contained, the solubility in the developer can be adjusted, and the exposure margin is further improved. In addition, advantages such as an improved depth of focus and improved dry etching resistance can be obtained.
Here, the term “styrene” includes 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, or a halogenated 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 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、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；ｎは０または１〜３の整数を表す。］

Wherein R 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; n is 0 or 1 Represents an integer of ~ 3. ]

In the formula (III), the the same as R and ^{R 3} in the formula (a-1) can be mentioned as R and ^{R 3.}
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.

As the structural unit (a3), one type may be used alone, or two or more types may be used in combination.
When the polymer compound (A1) has the structural unit (a3), the proportion of the structural unit (a3) is preferably 1 to 20 mol% with respect to all the structural units constituting the polymer compound (A1). 15 mol% is more preferable and 5-15 mol% is further more preferable. Within this range, the effect of having the structural unit (a3) is high, and the balance with other structural units is also good.

  In the present invention, the polymer compound (A1) is preferably a copolymer having all of these structural units (a1) to (a3) because of excellent effects of the present invention, and particularly the structural unit (a1). It is preferable that it is a copolymer consisting of (a3).

The polymer compound (A1) may contain other structural units (a4) other than the structural units (a1) to (a3) as long as the effects of the present invention are not impaired.
The structural unit (a4) is not particularly limited as long as it is another structural unit that is not classified into the structural units (a1) to (a3) described above. For ArF excimer laser, for KrF positive excimer laser (preferably ArF excimer) A number of hitherto known materials can be used for resist resins such as lasers.

  The polymer compound (A1) can be obtained by polymerizing a monomer for deriving each structural unit by a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN). it can.

The mass average molecular weight of the polymer compound (A1) (polystyrene conversion by gel permeation chromatography (GPC), the same shall apply hereinafter) is preferably 3000 to 50000, more preferably 5000 to 30000, and even more preferably 5000 to 20000. When the mass average molecular weight is 50000 or less, sufficient solubility in a resist solvent can be secured, and roughness can be reduced. Moreover, it is easy to adjust the solubility with respect to a developing solution as it is 3000 or more. In addition, dry etching resistance is improved and film loss is improved.
Further, the smaller the degree of dispersion (Mw / Mn (number average molecular weight)) of the polymer compound (A1) (the closer to monodispersion), the better the resolution and the better. The dispersity is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and most preferably 1.0 to 2.5.

<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 (B) which generates an acid upon exposure (hereinafter referred to as “acid generator component”). , (B) component) and a positive resist composition.
In such a positive resist composition, when an acid is generated from the component (B) by exposure, the acid dissociates the acid dissociable, dissolution inhibiting group of the component (A) and increases alkali solubility. Therefore, in the formation of the resist pattern, when the resist composition applied on the substrate is selectively exposed, the alkali solubility of the exposed portion increases and alkali development can be performed.

<(A) component>
The component (A) needs to contain the polymer compound (A1) of the present invention.
The polymer compound (A1) may be used alone or in combination of two or more.
In the component (A), the ratio of the polymer compound (A1) is preferably 50% by mass or more, more preferably 80 to 100% by mass, and most preferably 100% by mass for the effect of the present invention. is there.

  In the present invention, as the component (A), in addition to the polymer compound (A1), generally a chemically amplified positive resist resin such as a PHS resin and an acrylic resin, as long as the effects of the present invention are not impaired. You may contain resin used as.

  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.

<(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.

  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 most preferably R ⁵ ″ to R ⁶ ″ are all 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- (4-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, among onium salt acid generators, an onium salt having a relatively weak acid strength and having a camphorsulfonic acid ion in the anion portion can be used. The cation moiety is the same as that represented by the general formula (b-1) or (b-2). Specific examples include compounds represented by the following chemical formula.

  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 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 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 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).

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

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 (when A = 3) and 1,4-bis (phenylsulfonyldiazo) having the following structure. Methylsulfonyl) butane (when A = 4), 1,6-bis (phenylsulfonyldiazomethylsulfonyl) hexane (when A = 6), 1,10-bis (phenylsulfonyldiazomethylsulfonyl) decane (A = 10) 1), 1,2-bis (cyclohexylsulfonyldiazomethylsulfonyl) ethane (when B = 2), 1,3-bis (cyclohexylsulfonyldiazomethylsulfonyl) propane (when B = 3), 1,6- Bis (cyclohexylsulfonyldiazomethylsulfonyl) hexane (when B = 6) (For B = 10) 1,10-bis (cyclohexyl diazomethylsulfonyl) decane and the like.

  In the present invention, an oxime sulfonate acid generator and / or an onium salt acid generator having a fluorinated alkyl sulfonate ion as an anion is preferably used as the component (B).

(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 negative 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.

[Arbitrary ingredients]
In the positive resist composition of the present invention, a nitrogen-containing organic compound (except for the component (B)) (D) (D) (D) Hereinafter, (D) component) can be blended.
Since a wide variety of components (D) have already been proposed, any known component may be used. Examples of the component (D) include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine; diethylamine, di-n-propylamine, di-n- Dialkylamines such as heptylamine, di-n-octylamine, dicyclohexylamine; trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine, tri- Trialkylamines such as n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decanylamine, tri-n-dodecylamine; diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine Di -n- octanol amines include aliphatic amines, such as alkyl alcohol amines tri -n- octanol amine. 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.
Moreover, an aromatic amine can also be preferably used as the component (D). Aromatic amines include primary amines such as benzylamine, phenylamine and phenethylamine; secondary amines such as dibenzylamine, diphenylamine and diphenethylamine; tertiary amines such as triphenylamine, tribenzylamine and triphenethylamine. Examples include amines. Among these, tribenzylamine is preferable because of its excellent effect.
These may be used alone or in combination of two or more.
(D) component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

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

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

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

As described above, according to the positive resist composition containing the polymer compound (A1) of the present invention, a pattern having excellent resolution can be formed.
In the polymer compound (A1), the resolution is improved by the structural unit (a1), which is an alkali-soluble structural unit, and the formula —C (R ¹ R ² ) —O— (CH ₂ ) By having the structural unit (a2) having an acid dissociable, dissolution inhibiting group represented by _n- Z, the alkali solubility of the resist after dissociation of the acid dissociable, dissolution inhibiting group is improved, and the dissolution contrast is increased. This is thought to be due to the increase. That is, the acid dissociable, dissolution inhibiting group represented by the formula —C (R ¹ R ² ) —O— (CH ₂ ) _n —Z has a low activation energy in the deprotection reaction and is easily dissociated. Therefore, at the time of exposure, the rate of dissociation of the acid dissociable, dissolution inhibiting group present in the exposed area (deprotection rate) is high, and the alkali solubility in the exposed area is greatly increased. Moreover, since this acid dissociable, dissolution inhibiting group has Z (aliphatic cyclic group), the dissolution inhibiting effect is high. Therefore, the difference in alkali solubility (dissolution contrast) between the unexposed area and the exposed area is increased, and as a result, the resolution is improved.

  The positive resist composition of the present invention has a large exposure dose margin. If the exposure amount margin is small, the dimension of the resist pattern to be formed varies greatly due to a slight deviation in the exposure amount. However, in the present invention, since the exposure amount margin is large, the dimension variation of the formed resist pattern varies. Is also small.

  In the present invention, line edge roughness (LER) is reduced by improving alkali solubility in the exposed area. LER is the roughness of the resist pattern side wall surface, which may cause distortion around the hole in the hole pattern, variation in line width in the line and space pattern, etc., and may adversely affect the formation of fine semiconductor elements. In recent years, the improvement has become an important issue.

Furthermore, in the present invention, since the acid dissociable, dissolution inhibiting group is easily dissociated, an acid generation with a weak acid strength such as an oxime sulfonate acid generator or an onium salt having a camphorsulfonate ion in the anion part is generated. Even if an agent is used, it is easily dissociated, so that the resist pattern can be satisfactorily resolved, and the choice of the acid generator is wide.
From this fact, it is expected that the present invention has high environmental stability. That is, when a chemically amplified resist is used, there is a problem that problems such as a decrease in sensitivity, a deterioration in the shape of the resist pattern, and a decrease in resolution occur particularly in lithography using an electron beam or EUV. One of the causes of such problems is contamination (environmental influence) on the resist layer of a basic substance such as amine existing in the environment. That is, in the chemically amplified resist, due to the reaction mechanism of utilizing the action of acid, the acid is deactivated by the contamination of the basic substance, and its performance (sensitivity, shape, resolution, etc.) is affected. In addition, such environmental influence is also caused by the length of the process delay, for example, the time from the application of the resist to the exposure and the time from the exposure to the post-exposure heating (PEB). The degree differs, and this causes a difference in performance between lots, and changes in sensitivity, shape, resolution, and the like. In particular, in lithography using an electron beam or EUV, since exposure is usually performed in a reduced pressure environment, it is necessary to perform a reduced pressure operation, a purge operation, or the like, so that the process delay is long and the environmental influence becomes a serious problem. With respect to such problems, in the present invention, since the range of selection of the acid generator is wide, environmental stability can be improved by arbitrarily selecting and using an acid generator that is not easily affected by the environment. It is guessed.
Furthermore, for the same reason, it is expected that the substrate dependency is low. In other words, no matter what substrate is used, a good resist can be obtained on a silicon substrate, an antireflection film, a special substrate (SOG (spin-on-glass), Si-containing hard mask, chromium substrate), or the like. A pattern can be formed. That is, when a resist pattern is formed using a chemically amplified resist, the acid generated from the acid generator is deactivated at the interface with the substrate due to the influence of the substrate. There is a problem that a rectangular pattern cannot be formed because the portion remains insoluble in alkali and does not change, and after development, the resist at the interface with the substrate remains without being removed. On the other hand, the positive resist composition of the present invention can improve environmental stability by arbitrarily selecting and using an acid generator that is not easily affected by the substrate.

<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. Next, this is developed using an alkali developer, for example, an aqueous solution of 0.1 to 10% by mass of tetramethylammonium hydroxide (TMAH). 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 can be used as a KrF excimer laser, electron beam or EUV (extra electrode). For ultraviolet rays, and particularly suitable for electron beams.

Examples of the present invention will be described below, but the scope of the present invention is not limited to these examples.
Synthesis Example 1 Synthesis of 2-adamantyl chloromethyl ether Paraformaldehyde was added to 2-hydroxyadamantane, and 2.5 equivalents of hydrogen chloride gas was blown into 2-hydroxyadamantane, followed by reaction at 50 ° C. for 12 hours. After completion of the reaction, the product was distilled under reduced pressure to obtain 2-adamantyl chloromethyl ether).

Synthesis Example 2 Synthesis of 2-adamantyloxymethyl methacrylate 6.9 g of methacrylic acid was dissolved in 200 mL of tetrahydrofuran, and 8.0 g of triethylamine was added. After stirring at room temperature, 100 mL of tetrahydrofuran in which 15 g of 2-adamantyl chloromethyl ether was dissolved was added dropwise. After stirring for 12 hours at room temperature, the precipitated salt was filtered off. The obtained filtrate was evaporated, dissolved in 200 mL of ethyl acetate, washed with pure (100 mL × 3), and evaporated. After standing under ice cooling, a white solid was obtained.
Infrared absorption spectrum (IR), showing the results of measurement of the proton nuclear magnetic resonance spectra ⁽¹ H-NMR). IR (cm ⁻¹ ): 2907, 2854 (C—H stretch), 1725 (C═O stretch), 1638 (C═C stretch) ¹ H-NMR (CDCl ₃ , internal standard: tetramethylsilane) ppm: 1 .45-2.1 (m, 17H), 3.75 (s, 1H), 5.45 (s, 2H), 5.6 (s, 1H), 6.12 (s, 1H)
As a result of the above measurement, it was confirmed to be 2-adamantyloxymethyl methacrylate.

Synthesis example 3
(1) Synthesis of resin 48 g of isopropyl alcohol, 0.4 g of 4-acetoxystyrene, 0.04 g of styrene and 2-adamantyloxymethyl methacrylate 0 were added to a 4-neck flask equipped with a nitrogen blowing tube, a reflux condenser, a dropping funnel and a thermometer. .3 g was added and the atmosphere was replaced with nitrogen, and then the temperature was raised to 83 ° C. with stirring. While maintaining the temperature, 39 g of 4-acetoxystyrene, 4 g of styrene, 30 g of 2-adamantyloxymethyl methacrylate and 5 g of 2,2′-azobis- (2-methylbutyronitrile) were dissolved in 24 g of isopropyl alcohol. Was added dropwise over 3 hours. After completion of the dropping, stirring was continued for 3 hours while maintaining the temperature. Then, it cooled to 25 degreeC, the deposit was settled, the supernatant liquid was removed, and the sedimented deposit was melt | dissolved in 74 g of tetrahydrofuran. The 80% hydrazine aqueous solution 15g was dripped at the solution, and after stirring at 25 degreeC for 1 hour, reaction was complete | finished.
The obtained reaction solution was dropped into a large amount of water to obtain a precipitate. The precipitate was filtered, washed and dried to obtain a white solid random copolymer (hereinafter referred to as “resin 1”).
(2) Identification of Resin 1 The weight average molecular weight determined by gel permeation chromatography (GPC) in terms of polystyrene was 8,800, and the degree of dispersion was 1.80.
The composition ratio (molar ratio) of the structural units derived from each monomer by isotope carbon nuclear magnetic resonance ( ¹³ C-NMR) analysis was p-hydroxystyrene / styrene / 2-adamantyloxymethyl methacrylate = 60/10/30. It was.
The structure of Resin 1 is shown below.

［ａ／ｂ／ｃ＝６０／１０／３０（モル比）］

[A / b / c = 60/10/30 (molar ratio)]

Example 1
A positive resist composition solution was prepared with the composition shown in Table 1. The positive resist composition solution is uniformly applied onto an 8-inch silicon substrate that has been subjected to hexamethyldisilazane treatment, and is subjected to a 90-second baking process (PAB) under the conditions shown in Table 2 to provide a resist having a thickness of 300 nm. A film was formed. The resulting resist film was drawn with an electron beam drawing machine (Hitachi HL-800D, 70 kV acceleration voltage), and baked for 90 seconds (PEB) under the conditions shown in Table 2, 2.38 mass at 23 ° C. After developing for 60 seconds with a% TMAH aqueous solution, rinsing with pure water for 30 seconds, and shaking and drying, a baking process was performed at 100 ° C. for 60 seconds to form a resist pattern, and the following evaluation was performed. The results are summarized in Table 2.

Evaluation item <Sensitivity>
Sensitivity (μC / cm ² ) when a 1: 1 200 nm line and space pattern was formed was measured.
<Resolution>
The limiting resolution in the sensitivity is shown.
<Exposure margin>
An exposure margin was calculated by measuring a dimensional change amount with respect to 1 μC / cm ² at ± 5% from an optimum exposure amount in a 1: 1 200 nm line and space pattern.

Abbreviations in Table 1 are as follows: PAG1: α- (methyloxyimino) -p-methoxyphenylacetonitrile PAG2: triphenylsulfonium nonafluorobutanesulfonate AMINE1: tri-n-octylamine AMINE2: tribenzylamine ADD1: salicylic acid ADD2: Surfactant XR-104 (Dainippon Ink Chemical Co., Ltd.)
PGMEA: Propylene glycol monomethyl ether acetate

Resin 2: Polymer represented by the following formula (mass average molecular weight 10,000, dispersity 2.0, p: q: r = 60: 10: 30 [molar ratio])

Resin 3: Polymer represented by the following formula (mass average molecular weight 10,000, dispersity 2.0, p: q: r = 50: 20: 30 [molar ratio])

From the above results, it was found that Examples 1 to 4 were excellent in resolution as compared with Comparative Examples 1 to 3. In addition, Example 4 was superior in both exposure margin and sensitivity as compared with Comparative Examples 1 to 4. Further, when the pattern was observed from above the resist pattern with a scanning electron microscope (SEM), the resist patterns of Examples 1 to 4 had less side wall irregularities and good LER compared to Comparative Examples 1 to 3. I understood.

Claims (10)

The structural unit (a1) derived from hydroxystyrene and the following general formula (a2-1) or (a2-2)

[Wherein, Z represents an aliphatic cyclic group; n represents an integer of 0 or 1 to 3; m represents 0 or 1; and R independently represents a hydrogen atom or a lower group having 1 to 5 carbon atoms. Represents an alkyl group, a fluorine atom or a fluorinated lower alkyl group; R ¹ and R ² each independently represents a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms; ]
And a structural unit (a2) represented by the formula: The structural unit (a1) is represented by the following general formula (a-1)

[Wherein, R 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; P represents an integer of 0 or 1-2. ]
The polymer compound according to claim 1, wherein   Furthermore, the high molecular compound of Claim 1 or 2 containing the structural unit (a3) induced | guided | derived from styrene.   The polymer compound according to any one of claims 1 to 3, which has a mass average molecular weight of 3000 to 50000.   The polymer compound according to any one of claims 1 to 4, wherein a proportion of the structural unit (a1) is 10 to 80 mol% with respect to all structural units constituting the polymer compound.   The polymer compound according to claim 1, wherein the proportion of the structural unit (a2) is 5 to 50 mol% with respect to all the structural units constituting the polymer compound.   The polymer compound according to any one of claims 3 to 6, wherein the proportion of the structural unit (a3) is 1 to 20 mol% with respect to all structural units constituting the polymer compound. A positive resist composition comprising a resin component (A) whose alkali solubility is increased by the action of an acid, and an acid generator component (B) that generates an acid upon exposure,
The resin component (A) is a structural unit (a1) derived from hydroxystyrene and the following general formula (a2-1) or (a2-2)

[Wherein, Z represents an aliphatic cyclic group; n represents an integer of 0 or 1 to 3; m represents 0 or 1; and R independently represents a hydrogen atom or a lower group having 1 to 5 carbon atoms. Represents an alkyl group, a fluorine atom or a fluorinated lower alkyl group; R ¹ and R ² each independently represents a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms; ]
A positive resist composition comprising a polymer compound comprising the structural unit (a2) represented by formula (1):   The positive resist composition according to claim 8, which contains a nitrogen-containing organic compound (D). A resist comprising a step of forming a resist film on a substrate using the positive resist composition according to claim 8, a step of exposing the resist film, and a step of developing the resist film to form a resist pattern. Pattern forming method.