KR20080088533A - Positive resist composition and pattern forming method - Google Patents

Abstract

A positive resist composition is provided to reduce line edge roughness and improve exposure compliance during immersion exposure, thereby forming a high-quality resist pattern. A positive resist composition comprises: (A) a resin having acid-labile repeating units represented by the following formula (I) and undergoing an increase in solubility to an alkaline developing agent under the action of an acid; (B) a compound generating an acid upon irradiation of active rays or radiation; (C) a resin free from F and Si and having at least one repeating unit selected from the repeating units represented by the following formulae (C-I) to (C-III); and (D) a solvent. In formula (I), Xa1 is H, alkyl, cyano or halogen atom; each of Ry1-Ry3 is alkyl or cycloalkyl, or at least two of Ry1-Ry3 are bonded to each other to form a ring; and Z is a divalent linking group. In formulae (C-I)-(C-III), each R1 is H or CH3; each R2 is a hydrocarbyl having at least one -CH3 moiety; P1 is a linking group having a single bond or alkylene, ether or a combination thereof; P2 is a linking group selected from -O-, -NR-(wherein R is H or alkyl) and -NHSO2-; and n is an integer of 1-4.

Description

Positive resist composition and pattern formation method {POSITIVE RESIST COMPOSITION AND PATTERN FORMING METHOD}

The present invention relates to a positive resist composition used in the manufacturing steps of semiconductors such as ICs, the production of circuit boards such as liquid crystals, thermal heads, and other lithography steps of photoapplications, and a pattern forming method using the composition. In particular, the present invention relates to a positive resist composition suitable for exposure to an immersion type projection exposure apparatus using far ultraviolet light having a wavelength of 300 nm or less as an exposure, and a pattern forming method using the composition.

The trend toward miniaturization of semiconductor devices has led to a decrease in the wavelength of exposure and an increase in the numerical aperture NA of the projection lens. As a result, an exposure apparatus using an ArF excimer laser having a NA of 0.84 and a wavelength of 193 nm as a light source has been developed. As is generally known, the resolution and depth of focus can be represented by the following equation:

(Resolution) = k ₁ (λ / NA)

(Depth of focus) = ± k ₂ λ / NA ²

Is the wavelength of the exposure, NA is the numerical aperture of the projection lens, and k ₁ and k ₂ are coefficients related to the process.

In order to achieve improved resolution by further reducing the wavelength, an exposure apparatus using an F ₂ excimer laser having a wavelength of 157 nm as a light source is under study. However, since the lens material and the resist material used in the exposure apparatus are strictly limited, it is very difficult to stabilize the manufacturing cost of the apparatus or material or stabilize their quality. Therefore, there is a possibility that the exposure apparatus and the resist having sufficient performance and stability cannot be provided within the required period.

As a technique for improving the resolution of an optical microscope, a so-called immersion method, that is, a method of filling a liquid having a high refractive index (hereinafter may be referred to as an "immersion liquid") between the projection lens and the sample is known.

This "immersion" has the following effects. Assuming that the wavelength of the exposure in air is λ ₀ , the refractive index of the immersion liquid to air is n, the convergence half angle of light is θ, NA ₀ = sinθ, and the resolution and depth of focus when immersion is performed are It can be represented by the following formula:

(Resolution) = k ₁ (λ ₀ / n) / NA ₀

(Depth of focus) = ± k ₂ · (λ ₀ / n) NA ₀ ²

This indicates that the immersion produces the same effect as the use of exposure having a wavelength of 1 / n. That is, assuming that a light projection system with the same NA is used, the depth of focus can be increased n times by the immersion.

This is valid for any pattern profile. Thus, the immersion can be used in combination with super resolution techniques such as the phase shift method or the oblique incident illumination method currently being studied.

An example of an apparatus using the above effect for the transmission of a fine image pattern of a semiconductor element is described in JP-A-57-153433 or the like.

Recent advances in immersion exposure techniques have been described in The Proceedings of The International Society for Optical Engineering (SPIE Proc.), 4688, 11 (2002), J. Vac. Sci. Technol., B17 (1999), The Proceedings of The International Society for Optical Engineering (SPIE Proc.), 3999, 2 (2000) and the like. When an ArF excimer laser is used as the light source, pure water (refractive index at 1.93 nm: 1.44) is estimated to be the most promising as an immersion liquid from the viewpoint of transmittance and refractive index at 193 nm as well as safe handling. Fluorine-containing solutions have been studied as immersion liquids for use in exposure using an F ₂ excimer laser as a light source in view of the equilibrium between the transmittance and the refractive index at 157 nm. However, satisfactory immersion liquids have not yet been found in view of environmental safety and refractive index. Judging from the degree of effect of the immersion and maturation of the resist, the immersion exposure technique will first be used in an ArF exposure apparatus.

Since the advent of resists for KrF excimer laser (248 nm), chemical amplification has been used as an image forming method of resists to compensate for the decrease in sensitivity caused by light absorption. For example, the image forming method using positive chemical amplification exposes the resist to light, causing decomposition of the acid generator in the exposed portion and generating acid, which is then generated by subjecting the resist to post-exposure baking (PEB). The above acid is used as a reaction catalyst to convert an alkali insoluble group into an alkali soluble group and to remove the exposed portion by alkali development. As the chemically amplified resist composition, a resist composition obtained by mixing two or more resins having a specific structure is proposed, for example, in WO2005 / 003198 and JP-A-2002-303978. Although resists for ArF excimer lasers using the chemical amplification mechanism have become important resists in recent years, improvements are needed because pattern collapse occurs when they are exposed through a mask having a very fine mask size.

It is pointed out that when a chemically amplified resist is exposed to immersion exposure, the resist layer is brought into contact with the immersion liquid during exposure, resulting in degradation of the resist layer or radiation of components adversely affecting the immersion liquid from the resist layer. It is becoming. International application WO2004 / 068242 describes examples of changes in resist performance caused by immersing the ArF exposure resist in water before and after exposure, while it is pointed out that such changes are problematic in immersion exposure.

In the immersion exposure process, exposure using the scanning immersion exposure apparatus requires the movement of the immersion liquid according to the movement of the lens. Otherwise, the exposure speed decreases, which may adversely affect productivity. When the immersion liquid is water, the resist film is preferably hydrophobic and has excellent harvestability.

In addition, it is difficult to find suitable combinations of resins, photoacid generators, additives and solvents that can actually meet the integration performance of resists. In forming a fine pattern having a line width of 100 nm or less, even when the resolution performance is excellent, collapse of the line pattern occurs, which may cause defects during device fabrication. Therefore, it is required to overcome this pattern collapse and to reduce line edge roughness, otherwise this will prevent the formation of a uniform line pattern.

The term "line edge roughness" indicates that the line pattern of the resist and the edge of the substrate interface are irregularly formed in the direction perpendicular to the line direction due to the characteristics of the resist. This pattern seen in the upper right appears to have edges with irregularities (approximately ± several nm to ± several tens of nm). Since these unevenness is transferred to the substrate in the etching step, large unevenness may deteriorate the electrical properties, resulting in a decrease in yield.

It is an object of the present invention to provide a positive resist composition which causes less line edge roughness due to general exposure or immersion exposure and is excellent in harvesting during immersion exposure; And to provide a pattern forming method using the composition.

<1> (A) Resin which has an acid-decomposable repeating unit represented by general formula (I), and whose solubility to alkaline developing solution increases by the action of an acid;

(B) a compound that generates an acid upon irradiation with actinic light or radiation;

(C) Resin which does not contain fluorine and silicone and has at least 1 repeating unit chosen from repeating units represented by general formula (C-I)-(C-III); And

(D) Positive photosensitive composition containing a solvent.

(In the general formula (I),

Xa ₁ represents a hydrogen atom, an alkyl group, a cyano group or a halogen atom,

Ry ₁ to Ry ₃ each independently represent an alkyl group or a cycloalkyl group, and two or more of Ry ₁ to Ry ₃ may be bonded to each other to form a ring structure,

Z represents a divalent linking group.)

(In the above general formula (C-I) to (C-III),

R ₁ each independently represent a hydrogen atom or a methyl group,

Each R ₂ independently represents a hydrocarbon group having at least one —CH ₃ partial structure,

P ₁ represents a single bond or an alkylene group, an ether group or a linking group having two or more thereof,

P ₂ represents a linking group selected from —O—, —NR— (R represents a hydrogen atom or an alkyl group) and —NHSO ₂ —,

n represents the integer of 1-4.)

<2> The positive resist composition according to the above <1>, wherein Z in General Formula (I) is a divalent linear hydrocarbon group or a divalent cyclic hydrocarbon group.

<3> The positive resist composition according to <1> or <2>, wherein the resin (A) further has a repeating unit having one or more groups selected from lactone groups, hydroxyl groups, cyano groups, and acid groups.

<4> In any one of <1>-<3>,

The compound (B) is a positive resist composition comprising a compound that generates an acid represented by the general formula (BII):

(In the above general formula (BII),

Rb ₁ represents a group having an electron withdrawing group,

Rb ₂ represents an organic group having no electron withdrawing group,

m and n respectively represent the integer of 0-5, provided that m + n <= 5,

When m represents 2 or more, some Rb < ₁ > may be the same or different,

when n represents 2 or more, a plurality of Rb ₂ may be the same or different.)

<5> In the above <4>, in the general formula (BII), m represents 1 to 5, and the electron withdrawing group of Rb ₁ is selected from a fluorine atom, a fluoroalkyl group, a nitro group, an ester group, and a cyano group Positive resist composition of at least one atom or group selected.

<6> In any one of <1>-<5>,

Resin (C) has a positive resist composition which further has a repeating unit represented by General formula (C):

(In the general formula (C),

X ₁ , X ₂ and X ₃ each independently represent a hydrogen atom, an alkyl group, or a halogen atom,

L represents a single bond or a divalent linking group,

Rp ₁ represents an acid-decomposable group.)

<7> The above-mentioned <6>,

The said resistive unit represented by the said General formula (C) is a positive resist composition which is a repeating unit represented by General formula (C1).

(In the general formula (C1),

X ₁ , X ₂ and X ₃ each independently represent a hydrogen atom, an alkyl group, or a halogen atom,

R₁₂, R₁₃ And R₁₄Each independently represents an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, provided that R is₁₂, R₁₃ And R₁₄ One or more of represents an alkyl group, and R₁₂, R₁₃ And R₁₄ Two of them may combine to form a ring.)

<8> Positive resist composition in any one of said <1>-<7> used for exposure to the light which has a wavelength of 200 nm or less.

<9> The positive resist composition as described in <4> or <5>, in which the organic group of Rb ₂ having no electron withdrawing group in general formula (BII) has a cycloaliphatic group.

<10> The positive resist composition according to any one of <1> to <9>, further comprising (E) a basic compound.

<11> The positive resist composition as described in <10>, which contains at least 2,6-diisopropylaniline and tetrabutylammonium hydroxide as the basic compound (E).

<12> Positive resist composition in any one of said <1>-<11> which contains at least propylene glycol monomethyl ether acetate, 2-heptanone, and (gamma) -butyrolactone as a solvent (D).

<13> The positive resist composition according to any one of <1> to <12>, further comprising (F) a surfactant.

<14> A resist film is formed from the positive resist composition in any one of said <1>-<13>; Exposing and developing the resist film.

<15> The pattern formation method according to <14>, wherein the resist film is exposed through an immersion liquid.

In the following, the present invention will be described in detail.

In the present specification, when a group (atom group) is represented without specifying whether substituted or unsubstituted, the group includes both a group having no substituent and a group having a substituent. For example, the term "alkyl group" includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).

(A) Resin whose solubility in alkaline developer increases due to the action of acid

The resin used in the positive photosensitive composition of the present invention, in which solubility in an alkaline developer is increased by the action of an acid, is a resin having an acid-decomposable repeating unit represented by the following general formula (I) ("component (A) May be referred to as "resin":

In the general formula (I),

Xa ₁ represents a hydrogen atom, an alkyl group, a cyano group or a halogen atom,

Ry ₁ to Ry ₃ each independently represent an alkyl group or a cycloalkyl group, or two or more of Ry ₁ to Ry ₃ may combine to form a monocyclic or polycyclic hydrocarbon structure,

Z represents a divalent linking group.

In the general formula (I), the alkyl group of Xa ₁ may be substituted with a hydroxyl group, a halogen atom, or the like. Xa ₁ is preferably a hydrogen atom or a methyl group.

The alkyl group of Ry ₁ to Ry ₃ may be a linear alkyl group or a branched alkyl group. It may have a substituent. Examples of the substituent which it may have include a fluorine atom, a chlorine atom, a bromine atom, a hydroxyl group, and a cyano group. The straight chain or branched alkyl groups are the C _{1 -8} alkyl group, more preferably a C _{1 -4} alkyl group; Examples include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group and t-butyl group, preferably methyl and ethyl group.

Examples of the cycloalkyl group of ₁ ~ Ry Ry ₃ include a monocyclic C _{3 -8} cycloalkyl group and a polycyclic C _{7 -14} cycloalkyl group. They may have a substituent. Preferred examples of the monocyclic cycloalkyl group include a cyclopentyl group, a cyclohexyl group, and a cyclopropyl group. Preferred examples of the polycyclic cycloalkyl group include adamantyl group, norbornane group, tetracyclododecanyl group, tricyclodecanyl group and diamantyl group.

Ry ₁ to Ry ₃ It is preferable that the said monocyclic hydrocarbon structure formed by two or more of these bonds is a cyclopentyl group or a cyclohexyl group. Ry ₁ to Ry ₃ It is preferable that the said polycyclic hydrocarbon structure formed by two or more of these bonds is an adamantyl group, norbornyl group, or a tetracyclo dodecanyl group.

Z is preferably a divalent straight chain hydrocarbon group or a divalent cyclic hydrocarbon group. It may have a substituent. Examples of the substituent which it may have include a fluorine atom, a chlorine atom, a bromine atom, a hydroxyl group, and a cyano group. Z is a divalent C _{1 -20} connecting group is preferred, more preferably straight-chain C _{1 -4} alkyl group, or a cyclic C _{5 -20} alkylene group, or a combination thereof. Examples of the straight-chain C _{1 -4} alkyl group may include a group of methylene, ethylene, propylene, and butylene. It may be linear or branched. It is preferable that it is a methylene group. Examples of the cyclic C _{5 -20} alkylene group are cyclopentyl group and a cyclohexylene group ah monocyclic alkyl group, and a norbornyl group and the like but containing polycyclic alkylene group such as a naphthyl group, preferably adamantyl It's Rengi.

The polymeric compound for forming the said repeating unit represented with the said general formula (I) can be synthesize | combined easily by a well-known method. For example, according to the same method as described in JP-A-2005-331918, the alcohol is reacted with a carboxylic acid halide compound under basic conditions, and then the reaction product is subjected to basic reaction as shown in the following scheme. It can be synthesized by reacting with a carboxylic acid compound:

Although the preferable specific example of the said repeating unit represented by the said general formula (I) is shown below, this invention is not limited to them. In the above general formula, Xa ₁ represents a hydrogen atom, an alkyl group, a cyano group or a halogen atom.

The repeating unit represented by the general formula (I) is decomposed by the action of an acid to produce a carboxyl group. As a result, it increases the solubility of the resin in the alkaline developer.

Resin of component (A) may have other acid-decomposable repeating units other than the said acid-decomposable repeating unit represented by the said general formula (I).

It is preferable that acid-decomposable repeating units other than the said acid-decomposable repeating unit represented by said general formula (I) are repeating units represented with the following general formula (II):

In the general formula (II),

Xa ₁ represents a hydrogen atom, an alkyl group, a cyano group, or a halogen atom and is the same as Xa _{1 in} General Formula (I).

Rx ₁ to Rx ₃ each independently represent an alkyl group or a cycloalkyl group. Rx ₁ to Rx ₃ Two or more of them may combine to form a cycloalkyl group.

As the alkyl group of Rx ₁ Rx ~ _3, methyl group, ethyl group, n- propyl group, isopropyl group, n- butyl group, an isobutyl group, and straight chain or branched, such as t- butyl group is preferably C _{1 -4} Do.

Rx as the cycloalkyl group of ₁ ~ Rx _3, a cyclopentyl group and a cyclohexyl monocyclic cycloalkyl group, and a norbornyl group, tetracyclo decamethylene group, a tetracyclododecanyl group, and adamantyl polycyclic cycloalkyl group such as a group such as a group desirable.

Rx ₁ to Rx ₃ As said cycloalkyl group formed by combining two or more of these, monocyclic cycloalkyl groups, such as a cyclopentyl group and a cyclohexyl group, and polycyclic cyclos, such as a norbornyl group, a tetracyclo decanyl group, a tetracyclo dodecanyl group, and an adamantyl group Alkyl groups are preferred.

These groups given as Rx ₁ to Rx ₃ may further have a substituent. Examples of the substituents which they may have include a fluorine atom, a chlorine atom, a bromine atom, a hydroxyl group, and a cyano group.

As a preferred manner of Rx ₁ to Rx ₃ , Rx ₁ represents a methyl group or an ethyl group, and Rx ₂ and Rx ₃ combine to form the monocyclic or polycyclic cycloalkyl group.

Although the following is the specific example of the preferable repeating unit which has an acid-decomposable group, this invention is not limited to them.

(Rx represents H, CH ₃ or CH ₂ OH, Rxa and Rxb represents a C _{1 -4} alkyl group.)

It is preferable that the said repeating unit represented by the said general formula (II) is the repeating unit 1, 2, 10, 11, 12, 13, and 14 of the said specific example.

When the acid-decomposable group-containing repeating unit represented by the general formula (I) is used in combination with another acid-decomposable group-containing repeating unit (preferably the repeating unit represented by the general formula (II)), the general The molar ratio of the acid-decomposable group-containing repeating unit: the other acid-decomposable group-containing repeating unit represented by formula (I) is 90:10 to 10:90, and more preferably 80:20 to 20:80.

As for the total content of the said acid-decomposable group containing repeating unit in resin of the said component (A), 20-50 mol% is preferable with respect to all the repeating units of the said polymer, More preferably, it is 25-45 mol%.

It is preferable that the resin of the component (A) has a repeating unit having at least one group selected from lactone groups, hydroxyl groups, cyano groups, and alkali-soluble groups.

It is preferable that resin of the said component (A) has a repeating unit which has a lactone structure.

Although the said lactone structure is not limited at all, A 5-7 member cyclic lactone structure is preferable, It is preferable to form a bicyclo structure or a spiro structure with the 5-7 member cyclic lactone structure cyclically condensed with another cyclic structure. The said resin which has a repeating unit which has a lactone structure represented by any of the following general formula (LC1-1)-(LC1-16) is more preferable. The lactone structure may be directly bonded to the main chain. Preferred lactone structures include (LC1-1), (LC1-4), (LC1-5), (LC1-6), (LC1-13), and (LC1-14). The use of certain lactone structures reduces line edge roughness and developing defects.

Part of the lactone structure may have a substituent (Rb ₂ ) or may not have a substituent. Preferred examples of the substituent (Rb ₂₎ is a C _{1 -8} alkyl group, C _{4 -7} cycloalkyl group, C _{1 -8} alkoxy group, C _{1 -8} alkoxy group, a carboxyl group, a halogen atom, a hydroxyl group, a cyano group, and Acid-decomposable groups are included. More preferred examples thereof include a C _{1 -4} alkyl group, a cyano group, and an acid-decomposable group. In the said general formula, n <_2> represents the integer of 0-4. n ₂ is 2 or more, a plurality of Rb ₂ which may be the same or different, or may be a plurality of Rb ₂ are combined to form a ring.

Examples of the repeating unit having a lactone structure represented by any one of the general formulas (LC1-1) to (LC1-16) include the repeating unit represented by the following general formula (AI):

In the general formula (AI),

Rb ₀ represents a hydrogen atom, a halogen atom or a C _{1 -4} alkyl group; Preferable examples of the substituent which the alkyl group of Rb ₀ may have include a hydroxyl group and a halogen atom.

Examples of the halogen atom of Rb ₀ include fluorine atom, chlorine atom, bromine atom, and iodine atom. Rb ₀ is preferably a hydrogen atom or a methyl group.

Ab represents a divalent linking group including a single bond, an alkylene group, a divalent linking group having a monocyclic or polycyclic alicyclic hydrocarbon structure, an ether group, an ester group, a carbonyl group, or a combination thereof. Preference is given to a single bond or a divalent linking group represented by -Ab ₁ -CO _2- . Ab ₁ -is a linear or branched alkylene group or a monocyclic or polycyclic cycloalkylene group, and is preferably a methylene group, an ethylene group, a cyclohexylene group, an adamantylene group, or a norbornylene group.

V represents a group having a structure represented by any one of General Formulas (LC-1) to (LC-16).

The repeating unit having a lactone structure generally has optical isomers. Any of these optical isomers may be used. The optical isomers may be used alone or in combination. When one optical isomer is mainly used, it is preferable to have optical purity ee of 90 or more, More preferably, it is 95 or more.

The content of the repeating unit having a lactone structure is preferably 15 to 60 mol%, more preferably 20 to 50 mol%, even more preferably 30 to 50 mol% with respect to all the repeating units of the polymer.

Although the following is the specific example of the said repeating unit which has a lactone structure, this invention is not limited to them.

(Rx represents H, CH ₃ , CH ₂ OH, or CF _3. )

(Rx represents H, CH ₃ , CH ₂ OH, or CF _3. )

(Rx represents H, CH ₃ , CH ₂ OH, or CF _3. )

As said repeating unit which has a lactone structure, the following repeating unit is especially preferable. Selection of the optimal lactone structure improves pattern profile and roughness / fineness dependence.

(Rx represents H, CH ₃ , CH ₂ OH, or CF _3. )

It is preferable that resin of the said component (A) has a hydroxyl or cyano containing repeating unit. The resin having such repeating units improves the adhesion to the substrate and the affinity for the developer. It is preferable that the said hydroxyl or cyano containing repeating unit is a repeating unit which has an alicyclic hydrocarbon structure substituted by the hydroxyl group or the cyano group. It is preferable that the said alicyclic hydrocarbon structure of the said alicyclic hydrocarbon structure substituted by the hydroxyl group or the cyano group is an adamantyl group, diamantyl group, or norbornane group.

It is preferable that the said alicyclic hydrocarbon structure substituted by the hydroxyl group or the cyano group is some structure represented by either of following general formula (VIIa)-(VIId):

In the general formulas (VIIa) to (VIIc),

R ₂ c to R ₄ c each independently represent a hydrogen atom, a hydroxyl group, or a cyano group, under conditions in which one or more of R ₂ c to R ₄ c represent a hydroxyl group or a cyano group. Preferably, one or two of R ₂ c to R ₄ c is a hydroxyl group, and the rest are hydrogen atoms. More preferably, in the said general formula (VIIa), _{two of} R <_2> c ~ R <_4> c represent a hydroxyl group, respectively, and the remainder represents a hydrogen atom.

Examples of the repeating unit having some structures represented by the formulas (VIIa) to (VIId) include repeating units represented by the following formulas (AIIa) to (AIId), respectively.

In the said general formula (AIIa)-(AIIb),

R ₁ c represents a hydrogen atom, a methyl group, a trifluoromethyl group, or a hydroxymethyl group,

R ₂ c ~ R ₄ c have the same meanings as R ₂ c ~ c R ₄ in the formula (Ⅶa) ~ (Ⅶd).

The content of the repeating unit having an alicyclic hydrocarbon structure substituted with a hydroxyl group or a cyano group is preferably 5 to 40 mol%, more preferably 5 to 30 mol%, more preferably all the repeating units of the polymer. Preferably it is 10-25 mol%.

Although the following is the specific example of a hydroxyl or cyano containing repeating unit, this invention is not limited to them.

It is preferable that resin of the said component (A) has a repeating unit which has alkali-soluble group. Examples of the alkali-soluble group include a carboxyl group, a sulfonamide group, a sulfonylimide group, a bissulfonylimide group, and an aliphatic alcohol substituted with an electron withdrawing group at their α position (for example, hexafluoroisopropanol group). This includes. Resin which has a carboxyl containing repeating unit is more preferable. When the said resin has the said repeating unit which has alkali-soluble group, the resolution at the time of formation of a contact hole improves. As said repeating unit having an alkali-soluble group, a repeating unit having an alkali-soluble group directly bonded to the main chain of the resin, such as a repeating unit by acrylic acid or methacrylic acid, having an alkali-soluble group bonded to the main chain of the resin via a linking group Any of the repeating units having a repeating unit and an alkali-soluble group introduced into the terminal of the polymer chain at the time of polymerization using an alkali-soluble group-containing polymerization initiator or a chain transfer agent is preferable. The linking group may have a monocyclic or polycyclic hydrocarbon structure. Particularly preferred are the repeating units with acrylic acid or methacrylic acid.

It is preferable that content of the said repeating unit which has alkali-soluble group is 1-20 mol% with respect to all the repeating units of the said polymer, More preferably, it is 3-15 mol%, More preferably, it is 5-10 mol%.

Although the following is the specific example of the said repeating unit which has alkali-soluble group, this invention is not limited to them.

(Rx represents H, CH ₃ , CF ₃ , or CH ₂ OH.)

A repeating unit having at least one group selected from a lactone group, a hydroxyl group, a cyano group, and an alkali soluble group, the repeating unit having two or more groups selected from a lactone group, a hydroxyl group, a cyano group, and an alkali soluble group Unit is more preferable, and the repeating unit which has both a cyano group and a lactone group is further more preferable. Particular preference is given to repeating units having a lactone structure of LCI-4 substituted with a cyano group.

The resin of the component (A) may further have a repeating unit which has an alicyclic hydrocarbon structure and does not exhibit acid decomposability. By using the resin having such repeating units, the release of low molecular weight components from the resist film into the immersion liquid can be reduced during the immersion exposure. Examples of such repeating units include 1-adamantyl (meth) acrylate, diamantyl (meth) acrylate, tricyclodecanyl (meth) acrylate and cyclohexyl (meth) acrylate.

The resin of component (A) is the repeating structural unit in order to control the properties generally required for resists such as dry etching resistance, suitability for standard developer, adhesion to substrate, resist profile, and resolution, heat resistance and sensitivity. In addition, it may have various repeat structural units.

Examples of such repeating structural units include, but are not limited to, repeating units corresponding to monomers below.

The addition of such repeating units is required for the resin of component (A), in particular, (1) solubility in coating solvents, (2) film formation properties (glass transition point), (3) alkali development properties, (4) Fine control of film loss (selection of hydrophilic, hydrophobic or alkali-soluble groups), (5) adhesion of the substrate to unexposed areas, (6) dry etching resistance, and the like are possible.

Examples of such monomers include compounds having addition polymerizable unsaturated bonds selected from acrylates, methacrylates, acrylamides, methacrylamides, allyl compounds, vinyl ethers, vinyl esters and the like.

Moreover, the addition polymerizable unsaturated compound copolymerizable with the monomer corresponded to the said repeating structural unit may be copolymerized.

In the resin of the component (A), the molar ratio of the repeating structural unit contained in the resin is, if necessary, the dry etching resistance, suitability to a standard developer, adhesion to a substrate, and profile of the resist, and resolution, It is determined to control the performance typically required for such resists, such as heat resistance and sensitivity.

When the positive photosensitive composition of the present invention is used for ArF exposure, the resin of the component (A) is preferably free of aromatic groups from the viewpoint of light transmittance to ArF light.

As resin of the said component (A), resin in which the repeating unit consists only of a (meth) acrylate repeating unit is preferable. In this case, any of the resin whose repeating units are all methacrylate repeating units, the resin whose repeating units are all the acrylate repeating units, and the resin whose repeating units consist of a methacrylate repeating unit and an acrylate repeating unit Can be used. It is preferable that the said resin contains 50 mol% or less of acrylate repeating units with respect to all the said repeating units, The resin has 20-50 mol% of (meth) acrylate repeating units which have an acid-decomposable group, and has a lactone structure 20 to 50 mol% of (meth) acrylate repeating units, 5 to 30 mol% of (meth) acrylate repeating units having an alicyclic hydrocarbon structure substituted with a hydroxyl group or a cyano group, and other (meth) acrylates Copolymer containing 0-20 mol% of repeating units is more preferable.

The resin of component (A) can be synthesized by conventional methods (eg, radical polymerization). Examples of general synthetic methods include batch polymerization methods in which monomer species and an initiator are dissolved in a solvent and the solution is heated; And a dropwise addition polymerization method of adding a solution of a monomer species and an initiator dropwise added to the heated solvent for 1 to 10 hours. Among them, the dropwise addition polymerization is preferable. Examples of the reaction solvent include ethers such as tetrahydrofuran, 1,4-dioxane and diisopropyl ether, ketones such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate, dimethylformamide and dimethylacetic acid Amide solvents such as amides, and solvents for dissolving the composition of the present invention, such as propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, and cyclohexanone described below. More preferred are polymerizations using the same solvents as those used in the positive photosensitive compositions of the present invention. This makes it possible to inhibit the generation of particles during storage.

It is preferable that the said polymerization reaction is performed in inert-light gas atmosphere, such as nitrogen or argon. The polymerization is initiated using a commercially available radical initiator (such as an azo initiator or peroxide) as the polymerization initiator. As said radical initiator, an azo initiator is preferable and the azo initiator which has an ester group, a cyano group, or a carboxyl group is more preferable. Preferred examples of the initiator include azobisisobutyronitrile, azobi dimethylvaleronitrile and dimethyl 2,2'-azobis (2-methylpropionate). If necessary, the initiator may be further added, or may be added after being distributed. After completion of the reaction, the reaction mixture is filled in a solvent and collected by the method in which the preferred polymer is used to collect, for example, a powder or a solid. The said reaction concentration is 5-50 mass%, Preferably it is 10-30 mass%. The said reaction temperature is generally 10-150 degreeC, Preferably it is 30-120 degreeC, More preferably, it is 60-100 degreeC.

The resin of component (A) has a weight average molecular weight of preferably 1,000 to 200,000, more preferably 3,000 to 20,000 and most preferably 5,000 to 15,000, as determined by GPC for polystyrene. The adjustment of the weight average molecular weight to 1,000 to 200,000 makes it possible to prevent deterioration of heat resistance or dry etching resistance, and at the same time to prevent deterioration of film formation characteristics caused by deterioration of developing capability and otherwise densification. do.

Dispersibility (molecular weight distribution) is 1-5 normally, Preferably it is 1-3, More preferably, it is 1-2. When the molecular weight distribution is small, the resolution and the resist shape are excellent, the resist pattern has a smooth wall surface, and the roughness property is excellent.

When the resin of component (A) is used in a positive photosensitive composition exposed to KrF excimer laser light, electron beam, X-ray or high energy beam (EUV, etc.) having a wavelength of 50 nm or less, the resin of component (A) is It is preferable to have a repeating unit represented by the said general formula (I), and a repeating unit which has a hydroxy styrene structure. Examples of such repeating structures with hydroxystyrene include hydroxystyrene protected with o-, m- and p-hydroxystyrene and / or acid-decomposable groups. As the hydroxystyrene repeating unit protected with an acid-decomposable group, 1-alkoxyethoxystyrene and t-butylcarbonyloxystyrene are preferable.

In addition to the said repeating unit represented by the said General formula (I), and the repeating unit which has a hydroxystyrene structure, you may have a repeating unit represented by the said General formula (II).

Although the specific example of the said resin used for this invention and having both the said repeating unit which has a hydroxystyrene structure and the repeating unit represented by the said general formula (I) will be shown later, this invention is not limited to them. In these specific examples, Xa ₁ represents a hydrogen atom, an alkyl group, a cyano group or a halogen atom.

As for content of resin of the said component (A), 50-99.9 mass% of the total solid content of the positive photosensitive composition of this invention is preferable, More preferably, it is 60-99.0 mass%.

In this invention, resin of the said component (A) may be used individually or in combination.

(B) compounds that generate acids when irradiated with actinic radiation or radiation

The positive photosensitive composition of the present invention contains a compound (may be referred to as an "acid generator" or "compound of component (B)") that generates an acid upon irradiation with actinic light or radiation.

Examples of such compounds that decompose to generate an acid upon irradiation with actinic radiation or radiation include diazonium salts, phosphonium salts, sulfonium salts, iodonium salts, imidosulfonates, oxime sulfonates and o-nitrobenzyl sulfonates. Included.

Further, compounds obtained by introducing these groups or compounds which generate an acid upon irradiation of actinic radiation or radiation to the polymer backbone or side chain, for example, US Pat. No. 3,849,137, German Patent 3914407, JP-A-63-26653, Compounds described in JP-A-55-164824, JP-A-62-69263, JP-A-63-146038, JP-A-63-163452, JP-A-62-153853 and JP-A-63-146029 May also be used.

In addition, for example, compounds described in US Pat. No. 3,779,778 and European Patent 126,712 and in which an acid is generated upon irradiation with light may also be used.

As the acid generator, those having a non-nucleophilic anion are preferable. Preferred examples include sulfonate anion, carboxylate anion, bis (alkylsulfonyl) amide anion, a tris (alkylsulfonyl) methide anion, BF ₄ ^- include ^-, PF ₆ ^- and SbF _6. Among these, organic anions having carbon atoms are preferable.

Preferred examples of the non-nucleophilic anion include organic anions represented by the following general formulas AN1 to AN4.

Rc ₁ represents an organic group.

Examples of the organic group as Rc ₁ include groups C _{1 -30.} Preferred examples include a plurality of alkyl groups which may be substituted, an aryl group which may be substituted, and a linking group such as -O-, -CO _2- , -S-, -SO _3- , or -SO ₂ N (Rd ₁ ). These groups are included.

Rd ₁ represents a hydrogen atom or an alkyl group, and may form a ring structure with the alkyl group or aryl group to which Rd ₁ is bonded.

As said organic group of Rc <_1> , the alkyl group substituted by the fluorine atom or the fluoroalkyl group in their 1 position, or the phenyl group substituted by the fluorine atom or the fluoroalkyl group is preferable. Having a fluorine atom or a fluoroalkyl group leads to an increase in acidity of the acid generated by exposure and an improvement in sensitivity. When Rc ₁ has 5 or more carbon atoms, it is preferable that one or more carbon atoms are substituted with a hydrogen atom. More preferably, the number of hydrogen atoms is larger than the fluorine atom. Acid generators that do not contain a perfluoroalkyl group having five or more carbon atoms reduce environmental toxicity.

Further, it is preferable that Rc ₁ is a group represented by the following formula.

Rc ₇ -Ax-Rc ₆

Rc ₆ represents a perfluoroalkylene group or a phenylene group substituted with 3 to 5 fluorine atoms and / or 1 to 3 fluoroalkyl groups.

Ax is a linking group (preferably a single bond, -O-, -CO _2- , -S-, -SO _3- , or Rd ₁ represents a hydrogen atom or an alkyl group, or combines with Rc ₇ to form a ring structure Good SO ₂ N (Rd ₁ )).

Rc ₇ represents a hydrogen atom, a fluorine atom, a linear, branched, monocyclic or polycyclic substituted alkyl group or optionally substituted aryl group. The alkyl group or aryl group which may be substituted does not contain a fluorine atom as a substituent.

Rc ₃ , Rc ₄ and Rc ₅ each represent an organic group.

Rc _3, Rc ₄ and Rc of the organic group ₅ is preferably the same organic group as that given as a preferable example of the organic group of Rc _1.

Rc ₃ and Rc ₄ may be bonded to each other to form a ring. Examples of the machine formed by a combination of Rc ₃ and Rc ₄ is an alkylene group and includes an arylene group, an alkylene group is preferred to a C _{2 -4} perfluoroalkyl. It is preferable to combine Rc ₃ and Rc ₄ to form a ring because it increases the acidity of the acid generated by exposure and improves the sensitivity.

As the acid generator used in the present invention, a compound in which an acid represented by the general formula (BII) is generated is preferable.

In the said general formula (BII),

Rb ₁ represents a group having an electron withdrawing group,

Rb ₂ represents an organic group having no electron withdrawing group,

m and n respectively represent the integer of 0-5, provided that m + n <= 5,

When m represents 2 or more, some Rb < ₁ > may be the same or different,

when n represents 2 or more, a plurality of Rb ₂ may be the same or different.

In said general formula, it is preferable that m represents the integer of 1-5, More preferably, it is an integer of 2-5. The presence of the electron withdrawing group increases the acidity of the acid generated by exposure to actinic light and improves sensitivity.

The group having an electron withdrawing group as Rb ₁ is a group having one or more electron withdrawing groups, and is preferably a group having ten or less carbon atoms. The group having an electron withdrawing group may be an electron withdrawing group itself.

The electron withdrawing group is preferably a fluorine atom, a fluoroalkyl group, a nitro group, an ester group or a cyano group, and more preferably a fluorine atom.

Rb ₂ as the organic group having no electron attractive group and preferably a C _{1 -20,} more preferably C _{4 -20,} and more preferably from _-15 C ₄ organic groups. Preferred examples of the organic group include alkyl group, alkoxy group, alkylthio group, acyl group, acyloxy group, acylamino group, alkylsulfonyloxy group, and alkylsulfonylamino group. The organic group may have a hetero atom-containing linking group in their alkyl chains. Preferred examples of the hetero atom-containing linking group include -C (= 0) O-, -C (= 0)-, -SO _2- , -SO _3- , -SO ₂ N (A2)-, -O-, and- S- is included. Two or more of these groups may be used in combination. In the above general formula, A2 is a hydrogen atom or an optionally substituted alkyl group. When two or more groups are used in combination, they are preferably bonded through a heteroatom-free linking group such as an alkylene group or an arylene group.

These groups may have other substituents. Preferred examples of the other substituent may include a hydroxyl group, a carboxyl group, a sulfo group and a formyl group.

In the general formula (BⅡ), m represents an integer of 0 to 5, n is an integer of 1-5, provided, m + n≤5 and, Rb ₁ and Rb ₂ are each C ₄ alkyl _-20 It is preferable to have a structure. C _{4 -20} those having an alkyl structure enables the increase of the acid diffusion suppressing sex and the exposure latitude of the generated by the exposure of the actinic ray.

In General Formula (BII), each of Rb ₁ and Rb ₂ preferably has an alicyclic group. In particular, it is preferable that the organic group of Rb ₂ which does not have an electron withdrawing group is a group which has an alicyclic group.

The following is a specific example of the said acid represented by the said general formula (BII).

Examples of the compound which generates an acid upon irradiation with actinic light or radiation represented by the general formula (BII) include diazonium salt, phosphonium salt, sulfonium salt, iodonium salt, imidosulfonate, oxime sulfonate and o Nitrobenzyl sulfonate.

Among the compounds which decompose and decompose upon irradiation with actinic light or radiation, an acid is generated, compounds represented by the following general formulas (ZIa) and (ZIIa) are preferable.

In General Formula (ZIa), R ₂₀₁ , R ₂₀₂ , and R ₂₀₃ each independently have an organic group.

Xd ⁻ represents an anion of the acid represented by General Formula (BII).

Specific examples of the organic group as R ₂₀₁ , R ₂₀₂ , and R ₂₀₃ include groups corresponding to the compounds (ZI-1a), (ZI-2a), and (ZI-3a) described later.

The organic group may be a compound having a plurality of structures represented by General Formula (ZIa). For example, the compound is in at least one of R ₂₀₁ ~ R ₂₀₃ of another compound is at least one of R ₂₀₁ ~ R ₂₀₃ of a compound represented by the formula (ZIa) represented by the formula (ZIa) It may have a structure to be joined.

The following compounds (ZI-1a), (ZI-2a) and (ZI-3a) can be given as more preferred examples of component (ZIa).

Compound (ZI-1a) is an arylsulfonium compound having an aryl group in at least one of R ₂₀₁ to R ₂₀₃ of the general formula (ZIa), that is, a compound having arylsulfonium as a cation.

In the arylsulfonium compound, all of R ₂₀₁ to R ₂₀₃ may be aryl groups, or some of R ₂₀₁ to R ₂₀₃ may be aryl groups, and the rest may be alkyl groups.

Examples of the arylsulfonium compound include a triarylsulfonium compound, a diarylalkylsulfonium compound, and an aryldialkylsulfonium compound.

The aryl group of the arylsulfonium compound is preferably an aryl group such as a phenyl group or a naphthyl group, or a heteroaryl group such as an indole residue or a pyrrole residue, and more preferably a phenyl group and an indole residue. When an arylsulfonium compound has two or more aryl groups, these two or more aryl groups may be same or different.

An alkyl group having arylsulfonium compound according to necessity, a straight chain, branched or cyclic C _{1 ~15} alkyl group is preferable, and examples thereof include a methyl group, ethyl group, propyl group, n- butyl group, sec- butyl group, t- A butyl group, a cyclopropyl group, a cyclobutyl group, and a cyclohexyl group are included.

Aryl group or an alkyl group of R ₂₀₁ ~ R ₂₀₃ is (for example, C _{1 ~ 15} alkyl) group as a substituent, an aryl group (e.g., C _{6 ~ 14} aryl group), an alkoxy group (e.g., C _{1 15} alkoxy group), a halogen atom, a hydroxyl group, or a phenylthio group. Substituents are straight chain, branched or cyclic C _{1 ~ 12} as an alkyl group, a straight-chain, branched or cyclic C _{1 ~ 12} alkoxy group, more preferably C _{1 ~ 4} alkyl groups or C _{1 ~ 4} alkoxy group. The substituent is R ₂₀₁ to R ₂₀₃ Three It may be substituted by any one of them, or may be substituted by all three. When R ₂₀₁ to R ₂₀₃ are each an aryl group, the substituent is preferably substituted at the p-position of the aryl group.

Preferred arylsulfonium cations include triphenylsulfonium cations which may be substituted, naphthyl tetrahydrothiophenium cations which may be substituted, and phenyltetrahydrothiophenium cations which may be substituted.

Next, compound (ZI-2a) is described.

Compound (ZI-2a) is a compound of formula (ZIa) in which each of R ₂₀₁ to R _{203 in} formula (ZIa) independently represents an organic group that does not contain an aromatic ring. As used herein, the "aromatic ring" further includes an aromatic ring containing a hetero atom.

The organic group which does not contain an aromatic ring as R ₂₀₁ to R ₂₀₃ is usually 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms.

R ₂₀₁ to R ₂₀₃ are each independently an alkyl group, a 2-oxoalkyl group, an alkoxycarbonylmethyl group, an allyl group or a vinyl group, more preferably a linear, branched, or cyclic 2-oxoalkyl group, or alkoxycarbonyl It is a methyl group, Most preferably, it is a linear or branched 2-oxoalkyl group.

R ₂₀₁ ~ as R ₂₀₃ alkyl group is straight, branched may be any one of or cyclic, and preferably, for a linear or branched alkyl group of C _{1 ~ 10} (for example, a methyl group, an ethyl group, a pro-taking, a butyl group, or a pentyl group) or a cyclic alkyl group of C _{3 -10} (e.g., a cyclopentyl group, a cyclohexyl group or a norbornyl group).

The 2-oxoalkyl group may be linear, branched or cyclic as R ₂₀₁ to R ₂₀₃ , and a group having> C = 0 at two positions of the alkyl group is preferable.

As R ₂₀₁ ~ R ₂₀₃ is an alkoxycarbonyl group the alkoxy group is preferably C _{1 ~ 5} alkoxy group (e.g., methoxy, ethoxy, propoxy, butoxy, or pentoxy group).

R ₂₀₁ ~ R ₂₀₃ is (for example, an alkoxy group of C _{1 ~ 5)} a halogen atom, an alkoxy group, a hydroxyl group, a cyano group, or further may be substituted with a nitro group.

Two of R ₂₀₁ to R _{203 may be} bonded to each other to form a ring structure, and the ring may contain an oxygen atom, a sulfur atom, an ester bond, an amide bond, or a carbonyl group. Groups formed by combining two of R ₂₀₁ to R ₂₀₃ include an alkylene group (for example, butylene group and pentylene group).

Compound (ZI-3a) is a compound represented by the following General Formula (ZI-3a) and having a phenacylsulfonium salt structure.

R ₁ c to R ₅ c each independently represent a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom.

R ₆ c and R ₇ c is a hydrogen atom or an alkyl group.

Rx and Ry each independently represent an alkyl group, a 2-oxoalkyl group, an alkoxycarbonylmethyl group, an allyl group or a vinyl group.

R ₁ c to R ₅ c Two or more of these, or Rx and Ry may combine to form a ring structure, and these ring structures may contain an oxygen atom, a sulfur atom, an ester bond or an amide bond.

Xd ⁻ represents an anion of an acid represented by the general formula (BII).

As R ₁ c ~ R ₅ c is an alkyl group may be a straight chain, branched or cyclic alkyl group includes, for example, a C _{1 ~ 20} alkyl group; Preferably a straight chain or branched C _{1 ~ 12} alkyl group (e.g., methyl group, ethyl group, straight chain or branched propyl group, straight chain or branched butyl group, and straight chain or branched pentyl group) and cyclic C _3-8 alkyl group can be cited (for example, a cyclopentyl group and a cyclohexyl group).

R _1c ~ R _5c as alkoxy groups, straight, branched or cyclic may be a any one of the alkoxy group includes, for example, C _{1 ~ 10} alkoxy group. Preferably a straight chain or branched C _{1 ~ 5} alkoxy group (e.g., methoxy group, an ethoxy group, a straight chain or branched propoxy group, straight chain or branched butoxy group, and linear or branched pentoxy group ), and the example of the cyclic alkoxy groups (for example, a C _{3 ~ 8,} there may be mentioned a cyclopentyl tilok group and cyclohexyloxy group).

R _1c to R _5c It is preferable that either is a linear, branched or cyclic alkyl group, or a linear, branched or cyclic alkoxy group. As for the total number of carbon numbers of R <_1c> -R <_5c> , it is more preferable that it is 2-15. This improves solvent solubility and can suppress generation of particles during storage.

Examples of the alkyl group as Rx and Ry are the same as the alkyl group as R ₁ c to R ₅ c.

Examples of 2-oxoalkyl groups include alkyl groups provided as R ₁ c to R ₅ c and having> C = 0 at the 2 position.

Examples of the alkoxy group of the alkoxycarbonylmethyl group are the same as the alkoxy group as R ₁ c to R ₅ c.

Examples of the group formed by combining Rx and Ry include a butylene group and a pentylene group.

Rx and Ry are each preferably an alkyl group having 4 or more carbon atoms, more preferably 6 or more carbon atoms, still more preferably 8 or more carbon atoms.

In formula (ZIIa), R ₂₀₄ And R ₂₀₅ each independently represent an aryl group which may be substituted or an alkyl group which may be substituted.

The aryl group as R ₂₀₄ or R ₂₀₅ is preferably a phenyl group or a naphthyl group, and more preferably a phenyl group.

The alkyl group as R ₂₀₄ or R ₂₀₅ may be a linear, branched or cyclic alkyl group. Preferred examples are straight-chain or branched alkyl group of C _{1 ~ 10} (for example, a methyl group, an ethyl group, a propyl group, a butyl group, and pentyl group) and a C _{3 ~ 10} cycloalkyl (e.g., cyclopentyl, Cyclohexyl group, and norbornyl group).

Examples of R ₂₀₄ ~ R ₂₀₅ is brought FIG substituents include an alkyl group (e.g., an alkyl group of C _{1 ~ 15),} aryl group (e.g., an aryl group of C _{6 ~ 15),} an alkoxy group (e.g., alkoxy group), a C _{1 ~ 15,} include a halogen atom, a hydroxyl group and a phenylthio group.

More preferable compounds which decompose upon irradiation with actinic light or radiation to generate an acid include compounds represented by the following general formulas (ZIIIa) and (ZIVa).

In general formula (ZIIIa) and general formula (ZIVa),

Xd represents a monovalent group obtained by removing a hydrogen atom from an acid represented by the general formula (BII).

R ₂₀₇ and R ₂₀₈ each represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or an electron withdrawing group. R ₂₀₇ is preferably a substituted or unsubstituted aryl group.

R ₂₀₈ is preferably an electron withdrawing group, more preferably a cyano group or a fluoroalkyl group.

A represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkenylene group, or a substituted or unsubstituted arylene group.

Among the compounds which generate an acid by irradiation with actinic radiation or radiation, compounds represented by the general formulas (ZIa) to (ZIIIa) are more preferable, and compounds represented by the general formula (ZIa) are more preferable. The compound represented by (ZI-1a)-general formula (ZI-3a) is the most preferable.

Although the especially preferable compound (B) is shown below, this invention is not limited to these.

Examples of other preferred acid generators include, but are not limited to, the following compounds.

As a component (B), a compound may be used individually or in combination. When used in combination of two or more kinds, it is preferable to use a compound in which the total number of atoms except hydrogen atoms is two or more different and generates two kinds of organic acids.

The content of the compound as component (B) in the composition is preferably from 0.1 to 20% by mass, more preferably from 1 to 10% by mass, still more preferably from 3 to 8% by mass, based on the total solids of the resist composition. %, Especially preferably, it is 4-7 mass%.

(C) Resin having no repeating unit selected from repeating units represented by the following general formulas (C-I) to (C-III) without containing a fluorine atom and silicon

The photosensitive composition of the present invention is a resin (C) having a repeating unit selected from repeating units represented by the following general formulas (CI) to (C-III) without containing a fluorine atom and a silicon atom (hereinafter referred to as "hydrophobic resin ( HR) "in some cases).

In general formula (C-I)-general formula (C-III),

R ₁ each independently represent a hydrogen atom or a methyl group,

Each R ₂ independently represents a hydrocarbon group having at least one —CH ₃ partial structure (ie, a methyl group),

P ₁ represents a single bond or an alkylene group, an ether group or a linking group having two or more thereof,

P ₂ represents a linking group selected from —O—, —NR—, wherein R represents a hydrogen atom or an alkyl group, and —NHSO ₂ —,

n represents the integer of 1-4.

These repeating units may be used alone or in combination.

In general formulas (CI) to (C-III), a hydrocarbon group having at least one -CH ₃ partial structure (ie, a methyl group) as R ₂ is an alkyl group or alkyloxy group having at least one -CH ₃ partial structure. , An alkyl substituted cycloalkyl group, an alkenyl group, an alkyl substituted alkenyl group, an alkyl substituted cycloalkenyl group, an alkyl substituted aryl group and an alkyl substituted aralkyl group. Among these, an alkyl group and an alkyl substituted cycloalkyl group are preferable. More preferably, the hydrocarbon group having at least one -CH ₃ partial structure of R ₂ has at least two -CH ₃ partial structures.

Alkyl group having at least one partial structure -CH ₃ R ₂ is preferably an alkyl group branched C _{3 -20.} Preferred alkyl groups are isopropyl group, isobutyl group, t-butyl group, 3-pentyl group, 2-methyl-3-butyl group, 3-hexyl group, 2-methyl-3-pentyl group, 3-methyl-4- Hexyl group, 3,5-dimethyl-4-pentyl group, isooctyl group, 2,4,4-trimethylpentyl group, 2-ethylhexyl group, 2,6-dimethylheptyl group, 1,5-dimethyl-3-hep And a 2,3,5,7-tetramethyl-4-heptyl group. Among them, more preferably isobutyl group, t-butyl group, 2-methyl-3-butyl group, 2-methyl-3-pentyl group, 3-methyl-4-hexyl group, 3,5-dimethyl-4 -Pentyl group, 2,4,4-trimethylpentyl group, 2-ethylhexyl group, 2,6-dimethylheptyl group, 1,5-dimethyl-3-heptyl group and 2,3,5,7-tetramethyl- 4-heptyl group.

As the alkyl group having a partial structure -CH ₃ R _2, is preferably a straight chain alkyl group of C _{1 -20.} Specific examples of the preferred alkyl group include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group and nonyl group.

Alkyloxy groups having one or more -CH ₃ partial structures of R ₂ include groups in which an ether group is bonded to an alkyl group having two or more -CH ₃ partial structures.

The cycloalkyl group of R ₂ may be monocyclic or polycyclic. Specifically, the group which has a C5 or more monocyclo, bicyclo, tricyclo, or tetracyclo structure is mentioned. 6-30 are preferable and, as for carbon number, 7-25 are especially preferable.

Preferred cycloalkyl groups are adamantyl groups, noradamantyl groups, decalin residues, tricyclodecanyl groups, tetracyclododecanyl groups, norbornyl groups, cedrol groups, cyclopentyl groups, cyclohexyl groups, cycloheptyl groups and cyclooctyl groups , Cyclodecanyl group and cyclododecanyl group. More preferably, they are an adamantyl group, norbornyl group, a cyclohexyl group, a cyclopentyl group, a tetracyclo dodecanyl group, and a tricyclo decanyl group, and a norbornyl group, a cyclopentyl group, and a cyclohexyl group are more preferable.

Alkenyl group of R ₂ groups are preferably straight chain or branched alkenyl group of C _{1 -20,} more preferably a branched alkenyl group.

Aryl in the R ₂ group is preferably an aryl group of C _{6 -20} and, for example, there may be mentioned a phenyl group and a naphthyl group, a phenyl group is preferred.

The R ₂ group is preferably an aralkyl group of C _{7 -12} aralkyl and may be, for example, a benzyl group, a phenethyl group and a naphthylmethyl group.

Specific examples of the hydrocarbon structure having two or more -CH ₃ partial structures of R ₂ in formula (CI) and formula (C-II) include isopropyl group, isobutyl group, t-butyl group, 3-pen Methyl, 2-methyl-3-butyl, 3-hexyl, 2,3-dimethyl-2-butyl, 2-methyl-3-pentyl, 3-methyl-4-hexyl, 3,5-dimethyl -4-pentyl group, isooctyl group, 2,4,4-trimethylpentyl group, 2-ethylhexyl group, 2,6-dimethylheptyl group, 1,5-dimethyl-3-heptyl group, 2,3,5, And 7-tetramethyl-4-heptyl group, 3,5-dimethylcyclohexyl group, 4-isopropylcyclohexyl group, 4-t-butylcyclohexyl group and isobornyl group. More preferably, isobutyl group, t-butyl group, 2-methyl-3-butyl group, 2,3-dimethyl-2-butyl group, 2-methyl-3-pentyl group, 3-methyl-4-hexyl group , 3,5-dimethyl-4-pentyl group, 2,4,4-trimethylpentyl group, 2-ethylhexyl group, 2,6-dimethylheptyl group, 1,5-dimethyl-3-heptyl group, 2,3 , 5,7-tetramethyl-4-heptyl group, 3,5-dimethylcyclohexyl group, 4-isopropylcyclohexyl group, 4-t-butylcyclohexyl group and isobornyl group.

Specific examples of the hydrocarbon structure having two or more -CH ₃ partial structures of R ₃ in General Formula (C-III) include isobutyl group, t-butyl group, 3-pentyl group, and 2,3-dimethylbutyl group. , 2-methyl-3-butyl group, 3-hexyl group, 2-methyl-3-pentyl group, 3-methyl-4-hexyl group, 3,5-dimethyl-4-pentyl group, isooctyl group, 2,4 , 4-trimethylpentyl group, 2-ethylhexyl group, 2,6-dimethylheptyl group, 1,5-dimethyl-3-heptyl group, 2,3,5,7-tetramethyl-4-heptyl group, 3, 5-dimethylcyclohexyl group, 4-isopropylcyclohexyl group and 4-t-butylcyclohexyl group are included. More preferably, the hydrocarbon group of R ₃ has 5 to 20 carbon atoms, and examples thereof include 2-methyl-3-butyl group, 2-methyl-3-pentyl group, 3-methyl-4-hexyl group, and 3,5-dimethyl-. 4-pentyl group, 2,4,4-trimethylpentyl group, 2-ethylhexyl group, 2,6-dimethylheptyl group, 1,5-dimethyl-3-heptyl group, 2,3,5,7-tetramethyl 4-heptyl group, 2,6-dimethylheptyl group, 3,5-dimethylcyclohexyl group, 4-isopropylcyclohexyl group and 4-t-butylcyclohexyl group are included.

As for the total content of the repeating unit selected from the repeating unit represented by general formula (CI)-general formula (C-III), 80-100 mol% is preferable based on the total repeating unit of a polymer, More preferably, 90-100 Molar%.

The following are specific examples of preferred repeating units represented by the general formula (C-I), but the present invention is not limited thereto or by them.

The following are specific examples of preferred repeating units represented by the general formula (C-II), but the present invention is not limited thereto or by them.

In the general formula (C-III), when P ₂ represents an oxygen atom, the carbon atom directly bonded to the oxygen atom is preferably secondary or tertiary.

The following are specific examples of preferred repeating units represented by the general formula (C-III), but the present invention is not limited thereto or by them. In these examples, Rx represents a hydrogen atom or a methyl group, Rxa and Rxb represents an alkyl group of C _{1 -4,} respectively.

Resin of component (C) does not have a silicon atom and a fluorine atom.

It is preferable that the resin of component (C) does not have an element other than a carbon atom, a hydrogen atom, an oxygen atom, a nitrogen atom, and a sulfur atom.

It is preferable that resin of component (C) further has a repeating unit represented with the following general formula (C).

In General Formula (C), X ₁ , X ₂ and X ₃ each independently represent a hydrogen atom, an alkyl group or a halogen atom.

L represents a single bond or a divalent linking group,

Rp ₁ represents an acid-decomposable group.

It is preferable that the repeating unit represented by general formula (C) is a repeating unit represented by the following general formula (C1).

In general formula (C1),

X ₁ , X ₂ and X ₃ each independently represent a hydrogen atom, an alkyl group or a halogen atom.

R ₁₂ , R ₁₃ and R ₁₄ each independently represent an alkyl group, a cycloalkyl group, an alkenyl group or an aryl group, provided that at least one of R ₁₂ , R ₁₃ and R ₁₄ represents an allyl group, and R ₁₂ , R ₁₃ and R Two of ₁₄ may combine to form a ring.

Since the hydrophobic resin (HR) is localized on the surface layer of the photosensitive film and improves the receding contact angle of the photosensitive film surface by using water as the liquid immersion medium, the photosensitive composition containing the hydrophobic resin (HR) is capable of following the immersion liquid. This is improved.

As the hydrophobic resin (HR), any resin capable of improving the surface receding contact angle can be used, but a resin having at least one of a fluorine atom and a silicon atom is preferable. 60 degrees-90 degrees are preferable, and, as for the receding contact angle of the photosensitive film formed using the photosensitive composition of this invention, 70 degrees or more are more preferable.

The said hydrophobic resin (HR) can be added, adjusting the recessed contact angle of a photosensitive film | membrane so that it may become in the said range as needed. It is preferable that it is 0.1-10 mass% on the basis of the total solid of the photosensitive composition, and 0.1-5 mass% is more preferable.

The "retract contact angle" defined herein refers to the retracted contact angle measured by the extension / contraction method. More specifically, it can measure using a fully automatic contact angle meter ("DM700", brand name: Kyowa Interface Science). Droplets (36 μL) are formed using a syringe on the positive resist composition formed on the silicon wafer, followed by suction at a rate of 6 μL / sec. The contact angle which became stable during suction is made into retreat contact angle.

The hydrophobic resin (HR) is ubiquitous at the interface, but unlike the surfactant (E), it is not necessarily required to have a hydrophilic group in the molecule and does not need to contribute to uniform mixing of the polar / nonpolar material.

The resin (HR) may further contain at least one group selected from the group consisting of the following (x) to (z):

(x) alkali soluble groups,

(y) a group which is decomposed by the action of an alkaline developer and has increased solubility in the alkaline developer, and

(z) groups decomposed by the action of acids.

Examples of the alkali-soluble group (x) include phenolic hydroxyl group, carboxylic acid group, sulfonic acid group, sulfonamide group, sulfonimide group, (alkylsulfonyl) (alkylcarbonyl) methylene group, (alkylsulfonyl) (Alkylcarbonyl) imide group, bis (alkylcarbonyl) methylene group, bis (alkylcarbonyl) imide group, bis (alkylsulfonyl) methylene group, bis (alkylsulfonyl) imide group, tris (alkylcarbonyl) And groups having a methylene group and a tris (alkylsulfonyl) methylene group.

Among these alkali-soluble groups, sulfonimide groups and bis (carbonyl) methylene groups are preferable.

Repeating unit having an alkali-soluble group (x) as a repeating unit having an alkali-soluble group directly bonded to the main chain of the resin, such as a repeating unit by acrylic acid or methacrylic acid, having an alkali-soluble group bonded to the main chain of the resin through a linking group Any of the repeating units and the repeating unit having an alkali-soluble group introduced into the polymer chain terminal using an alkali-soluble group-containing polymerization initiator and a chain transfer agent at the time of polymerization are preferable.

As for content of the repeating unit which has alkali-soluble group (x), 0-20 mol% is preferable with respect to the total repeating unit in a polymer, and 0-10 mol% is more preferable.

The specific example of the repeating unit which has alkali-soluble group (x) is shown below.

Examples of the group (y) decomposed by the action of the alkaline developer and in which the solubility is increased in the alkaline developer include a group having a lactone structure, an acid anhydride and an acid imide group, and a group having a lactone structure is preferable.

A repeating unit having a group (y) decomposed by the action of an alkaline developer and having increased solubility in the alkaline developer, and a repeating unit having an alkali-soluble group bonded to the main chain of the resin through a linking group such as a repeating unit by acrylate or methacrylate. And repeating units having alkali-soluble groups introduced at the ends of the polymer chain during polymerization using a polymerization initiator or a chain transfer agent having a group (y) having increased solubility in the alkaline developer.

The content of the repeating unit having a group (y) in which solubility is increased in the alkaline developer is preferably 0 to 20 mol%, more preferably O to 10 mol%, based on the total repeating units in the polymer.

The specific example of the repeating unit which has group (y) in which solubility increases in alkaline developing solution is illustrated below.

Examples of groups decomposed by the action of an acid are the same as those exemplified in the resin (A). The content of the repeating unit having a group (z) decomposed by the action of an acid is preferably from 0 to 100 mol%, more preferably from 0 to 80 mol%, more preferably from 0 to 50 mol%, based on the total repeating units in the polymer. More preferred.

The content of the resin of the component (C) is 0.1 to 20% by mass, more preferably 0.1 to 10% by mass, still more preferably 0.1 to 5% by mass based on the solids (the total solids constituting the resist film) of the positive resist composition. %to be.

Resin (HR) has a weight average molecular weight in terms of standard polystyrene, preferably 1,000 to 100,000, more preferably 2,000 to 50,000, even more preferably 3,000 to 15,000. It is preferable that dispersion degree (Mw / Mn) of resin of (C) component is 1.0-3.0, More preferably, it is 1.2-2.5, More preferably, it is 1.2-2.0.

Of course, the resin (HR) is the same as the acid-decomposable resin (A) and at the same time there are few impurities such as metals, and the residual monomer or oligomer component is preferably 0 to 10% by mass, more preferably 0 to 5% by mass, More preferably, it is 0-1 mass%. Such resins can provide resists with no foreign matter or sensitivity in the liquid over time. In terms of resolution, resist shape, sidewalls and roughness of the resist pattern, the molecular weight distribution (Mw / Mn, also referred to as "dispersion degree") is preferably in the range of 1 to 5, more preferably 1 to 3, and even more Preferably it is 1-2.

As resin (HR), a commercial item can be used or the said resin can be synthesize | combined by a conventional method (for example, radical polymerization). Examples of common synthetic methods include batch polymerization method in which monomer species and an initiator are dissolved in a solvent, and the solution is heated to polymerize; And a dropwise polymerization method in which the monomer species and the initiator solution are added dropwise to the heating solvent over 1 to 10 hours. Among these, the dropwise polymerization method is preferable. Examples of the reaction solvent include ethers such as tetrahydrofuran, 1,4-dioxane and diisopropyl ether, ketones such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate, amides such as dimethylformamide and dimethylacetamide The solvent and the solvent which melt | dissolved the composition of this invention, such as propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, and cyclohexanone which are mentioned later are included. More preferred is a polymerization using the same solvent as used in the positive resist composition of the present invention. This makes it possible to suppress the generation of particles during storage.

It is preferable to perform a polymerization reaction in inert gas atmosphere, such as nitrogen or argon. Polymerization is initiated using commercially available radical initiators (such as azo initiators or peroxides) as polymerization initiators, and chain transfer agents may be used as necessary. As a radical initiator, an azo initiator is preferable and the azo initiator which has an ester group, a cyano group, and a carboxyl group is more preferable. Preferred examples of initiators include azobisisobutyronitrile, azobisdimethylvaleronitrile and dimethyl 2,2'-azobis (2-methylpropionate). Reaction concentration is 5-50 mass%, Preferably it is 30-50 mass%. The reaction temperature is generally 10 ° C to 150 ° C, preferably 30 ° C to 120 ° C, and more preferably 60 ° C to 100 ° C.

After completion of the reaction, the reaction product is cooled to room temperature and purified. Purification can use conventional methods. Examples of the purification method include a liquid-liquid extraction method for removing residual monomer or oligomer components by washing with water or a suitable solvent, and ultrafiltration for extracting and removing components having a molecular weight below a specific value, and resin. The solution is added dropwise to the poor solvent to solidify the resin in the poor solvent to remove residual monomers and the like, and to purify the filtered resin slurry into a solid solvent. For example, the resin may be prepared by contacting the reaction solution with a solvent (poor solvent) in which the resin is poorly soluble or insoluble, used in a volume amount of 10 times or less, preferably 10 to 5 times that of the resin. Precipitates.

The solvent (precipitation or reprecipitation solvent) used for precipitation or reprecipitation from the polymer solution may be any one as long as it is a poor solvent for the polymer. Depending on the type of the polymer, a solvent may be selected as necessary from a hydrocarbon, a halogenated hydrocarbon, a nitro compound, an ether, a ketone, an ester, a carbonate, an alcohol, a carboxylic acid, water, a mixed solvent containing them, and the like. Among these, as the precipitation or reprecipitation solvent, a solvent containing at least alcohol (particularly methanol or the like) or water is preferable.

The amount of the precipitated or reprecipitated solvent may be determined as necessary in consideration of efficiency, yield, and the like, but is generally 100-10000 parts by mass, preferably 200-2000 parts by mass, and more preferably 100 parts by mass of the polymer solution. It is 300-1000 mass parts.

The temperature at the time of precipitation or reprecipitation may be selected as needed in view of efficiency and operability, but is usually about 0 to 50 ° C., preferably around room temperature (eg, about 20 to 35 ° C.). Precipitation or reprecipitation operation can be performed by a well-known process, such as batch type or continuous type, using mixing vessels, such as a stirring tank.

Precipitated or reprecipitated polymers can be provided for use by conventional solid-liquid separation, such as filtration or centrifugation, and drying. Filtration can be carried out using a solvent resistant filter under pressure.

Drying is performed at a temperature of about 30 to 100 ° C., preferably about 30 to 50 ° C. under normal pressure or reduced pressure (preferably under reduced pressure).

The resin once precipitated and separated can then be dissolved again in a solvent to contact the solvent with a poorly soluble or insoluble solvent. Specifically, after completion of the radical polymerization reaction, the polymer is contacted with a solvent which is poorly soluble or insoluble (step a), and the step of separating the resin from the solution (step b), and again the solvent A step (step c) of dissolving a resin to prepare a resin solution A, wherein the resin is used in an amount of less than 10 times (preferably 5 times or less) of the volume of the resin solution A. It may be a process including a step (step d) of depositing a resin body by contacting an insoluble solvent and the resin solution A and a step of separating the precipitated resin (step e).

The following is a specific example of resin. The molar ratio of the repeating units of each resin (corresponding to the left to right order of repeating units shown in the specific examples), the weight average molecular weight and the degree of dispersion are shown in the table below.

A film that is poorly soluble in the immersion liquid (hereinafter referred to as "topcoat") may be formed between the immersion liquid and the resist film formed using the resist composition of the present invention to prevent the resist film from directly contacting the immersion liquid. have. Functions required for the topcoat include application titration to the top layer of resist, transparency to radiation, in particular having a wavelength of 193 nm, and poor solubility for immersion liquids. The top coat is preferably mixed evenly on the resist surface without mixing with the resist.

The topcoat is preferably a polymer that does not contain abundant aromatics from the viewpoint of transparency at 193 nm. Specific examples include hydrocarbon polymers, acrylate polymers, poly (methacrylates), poly (acrylates), poly (vinylethers), silicone-containing polymers and fluorine-containing polymers. The hydrophobic resin (HR) is also suitable as a top coat. It is desirable that the residual monomer component of the polymer in the top coat be as small as possible because impurities will elute the liquid into the liquid in the top coat.

Top coat peeling may use a developer. Alternatively, the top coat can be removed using a separate release agent. The release agent is preferably a solvent which is less penetrated into the photosensitive film. Since the peeling process of a top coat can be performed simultaneously with the image development process process of a photosensitive film, peeling using alkaline developing solution is preferable. The topcoat is preferably acidic in that it is peeled off with an alkaline developer, but the topcoat may be neutral or alkaline to prevent mixing with the photosensitive film.

The smaller the difference in refractive index between the topcoat and the immersion liquid, the better the resolution. When the ArF excimer laser (wavelength: 193 nm) is used in combination with water which is an immersion liquid, the ArF immersion exposure top coat preferably has a refractive index close to that of the immersion liquid. In order to obtain a refractive index close to the refractive index of the immersion liquid, the top coat preferably contains a fluorine atom. In view of transparency and refractive index, the top coat is preferably a thin film.

It is preferred that the topcoat is not mixed with the resist or immersion liquid.

From this point of view, when the immersion liquid is water, the solvent used for the top coat is preferably a medium that is poorly soluble in water and insoluble in the solvent used in the photosensitive composition. If the immersion liquid is an organic solvent, the top coat can be water soluble or water insoluble.

(D) solvent

In the photosensitive composition of the present invention, the above components are dissolved in a predetermined solvent.

An organic solvent can be used as a normal solvent. Examples of the solvent include ethylene dichloride, cyclohexanone, cyclopentanone, 2-heptanone, γ-butyrolactone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, Ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, toluene, ethyl acetate, methyl lactate, ethyl lactate, methoxymethyl propionate, ethoxyethyl propionate, methylpyruvate , Ethylpyruvate, propylpyruvate, N, N-dimethylformamide, dimethylsulfoxide, N-methylpyrrolidone and tetrahydrofuran.

In the present invention, the organic solvent may be used alone or in combination, but it is preferable to use a mixed solvent containing two or more solvents each having different functional groups. This not only improves the solubility of the material and suppresses particle generation over time, but also enables the formation of good pattern profiles. Preferred functional groups contained in the solvent include ester groups, lactone groups, hydroxyl groups, ketone groups and carbonate groups. As a mixed solvent which has the said functional group, the mixed solvent represented by the following (S1)-(S5) is preferable.

(S1) A solvent in which a solvent containing a hydroxyl group and a solvent not containing a hydroxyl group are mixed.

(S2) A solvent in which a solvent having a ester structure and a solvent having a ketone structure are mixed.

(S3) A solvent in which a solvent having an ester structure and a solvent having a lactone structure are mixed.

(S4) A solvent in which a solvent having an ester structure, a solvent having a lactone structure, and a hydroxyl group-containing solvent are mixed.

(S5) A solvent in which a solvent having an ester structure, a solvent having a carbonate structure, and a hydroxyl group-containing solvent are mixed.

The use of such a mixed solvent enables both reduction of particle generation during storage and suppression of defect generation during application.

Examples of hydroxyl group-containing solvents include ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether and ethyl lactate. Of these, propylene glycol monomethyl ether and ethyl lactate are particularly preferred.

Examples of solvents containing no hydroxyl group include propylene glycol monomethyl ether acetate, ethyl ethoxy propionate, 2-heptanone, γ-butyrolactone, cyclohexanone, butyl acetate, N-methylpyrrolidone, N, N-dimethylacetamide and dimethyl sulfoxide. Among these, propylene glycol monomethyl ether acetate, ethyl ethoxy propionate, 2-heptanone, γ-butyrolactone, cyclohexanone and butyl acetate are particularly preferable, and propylene glycol monomethyl ether acetate and ethyl ethoxy propionate. Most preferred are cypionate, 2-heptanone and cyclohexanone.

Examples of the solvent having a ketone structure include cyclohexanone and 2-heptanone. Among these, cyclohexanone is preferable.

Examples of the solvent having an ester structure include propylene glycol monomethyl ether acetate, ethyl ethoxy propionate, butyl acetate. Among these, propylene glycol monomenal ether acetate is preferable.

Examples of the solvent having a lactone structure include γ-butyrolactone.

Examples of the solvent having a carbonate structure include propylene carbonate and ethylene carbonate. Of these, propylene carbonate is preferred.

In the resist composition of the present invention, a mixed solvent containing at least one of propylene glycol monomethyl ether acetate, 2-heptanone and γ-butyrolactone is particularly preferred.

The solvent containing a hydroxyl group and the solvent containing no hydroxyl group are 1/99 to 99/1, preferably 10/90 to 90/10, more preferably 20/80 to 60/40 ( Mass ratio). The mixed solvent containing 50 mass% or more of the solvent which does not contain a hydroxyl group is especially preferable at the point of coating uniformity.

The solvent having an ester structure and the solvent having a ketone structure are mixed at a ratio (mass ratio) of 1/99 to 99/1, preferably 10/90 to 90/10, and more preferably 40/60 to 80/20. do. The mixed solvent containing 50 mass% or more of solvent which has an ester structure is especially preferable at the point of application uniformity.

The solvent having an ester structure and the solvent having a lactone structure are mixed at a ratio (mass ratio) of 70/30 to 99/1, preferably 80/20 to 99/1, and more preferably 90/10 to 99/1. do. A mixed solvent containing 70% by mass or more of a solvent having an ester structure is particularly preferable in terms of stability over time.

When mixing a solvent having an ester structure, a solvent having a lactone structure, and a solvent containing a hydroxyl group, the mixed solvent is 30 to 80% by weight of the solvent having an ester structure, and 1 to 20% by weight of a solvent having a lactone structure. It is preferable to contain 10 to 60 weight% of a solvent containing% and a hydroxyl group.

When mixing a solvent having an ester structure, a solvent having a carbonate structure and a solvent containing a hydroxyl group, the mixed solvent is 30 to 80% by weight of a solvent having an ester structure and a solvent having a carbonate structure. It is preferable to contain 1 to 20 weight% and 10 to 60 weight% of the solvent containing a hydroxyl group.

(E) basic compounds

It is preferable that the positive photosensitive composition of this invention contains (E) basic compound in order to reduce the performance change with time-lapse from exposure to heating, or to control the diffusion of the acid generated by exposure in the film | membrane.

Examples of the basic compound include nitrogen-containing basic compounds and onium salt compounds.

Preferable nitrogen-containing basic compound structures include compounds having partial structures represented by the following general formulas (A) to (E).

In the above formulas, R ^250, R ²⁵¹ and R ²⁵² each independently represents a hydrogen atom, an alkyl group C _{1 ~20, ~20} C ₃ cycloalkyl group or an aryl group of C ₆ of the _~20, or R ²⁵⁰ and R ²⁵¹ may combine with each other to form a ring. These groups may have a substituent. The alkyl group and cycloalkyl group having a substituent include an amino-cycloalkyl group, and hydroxy cycloalkyl group of C _{3 ~20} of C _{1 ~ 20-amino-alkyl} group, a hydroxy group, a C _{1 ~20 3~20} of C are preferred, respectively.

These groups may further contain an oxygen atom, a sulfur atom or a nitrogen atom in the alkyl chain.

Said general ^{formula, R 253, R 254, R} 255 and R ²⁵⁶ independently represent a cycloalkyl group of C _{1 ~6} alkyl group or a C _{3 -6,} respectively.

Preferred compounds include guanidine, aminopyrrolidine, pyrazole, pyrazoline, piperazine, aminomorpholine, aminoalkylmorpholine and piperidine, which may have a substituent. More preferred compounds include imidazole structures, diazabicyclo structures, onium hydroxide structures, onium carboxylate structures, trialkylamine structures, aniline structures or pyridine structures, alkylamine derivatives having hydroxyl groups and / or ether bonds, and And aniline derivatives having hydroxyl groups and / or ether bonds.

Compounds having an imidazole structure include imidazole, 2, 4, 5-triphenylimidazole, and benzimidazole. Compounds having a diazabicyclo structure include 1,4-diazabicyclo [2,2,2] octane, 1,5-diazabicyclo [4,3,0] nona-5-ene and 1,8-diazabi Cyclo [5,4,0] undeca-7-ene. Examples of the compound having an onium hydroxide structure include triarylsulfonium hydroxide, phenacylsulfonium hydroxide, and sulfonium hydroxide having a 2-oxoalkyl group. Specifically triphenylsulfonium hydroxide, tris (t-butylphenyl) sulfonium hydroxide, bis (t-butylphenyl) iodium hydroxide, phenacylthiophenium hydroxide and 2-oxopropylthiope Nium hydroxide is mentioned. Compounds having an onium carboxylate structure include those in which the anion portion of the compound having an onium hydroxide structure is converted to a carboxylate, for example acetate, adamantane-1-carboxylate and perfluoroalkyl carboxylate Can be mentioned. Compounds having a trialkylamine structure include tri (n-butyl) amine and tri (n-octyl) amine. Aniline compounds include 2,6-diisopropylaniline and N, N-dimethylaniline. Alkylamine derivatives having hydroxyl groups and / or ether bonds include ethanolamine, diethanolamine, triethanolamine and tris (methoxyethoxyethyl) amine. Aniline derivatives having a hydroxyl group and / or an ether bond include N, N-bis (hydroxyethyl) aniline.

It is particularly preferred that the resist composition of the present invention contains at least one of 2,6-diisopropylaniline and tetrabutylammonium hydroxide.

You may use these basic compounds individually or in combination. The basic compound is generally used in an amount of 0.001% by mass to 10% by mass, and preferably 0.01% by mass to 5% by mass, with respect to the solid content in the positive photosensitive composition. In order to obtain sufficient effect of the addition, the content is preferably 0.001% by mass or more, and on the other hand, it is 10% by mass or more from the viewpoint of the sensitivity and developing characteristics of the unexposed part.

(F) surfactant

It is preferable that the said positive photosensitive composition of this invention contains surfactant. The surfactant preferably contains any one or two or more of fluorine and / or silicon-containing surfactants (fluorine-containing surfactants, silicon-containing surfactants, and surfactants containing both fluorine and silicon atoms). .

The positive photosensitive composition of the present invention contains fluorine and / or silicon-containing surfactants, so that when a light source having a wavelength of 250 nm or less, in particular 220 nm or less, is used for exposure, it exhibits excellent adhesion at high sensitivity and resolution and develops development defects. Less resist pattern can be provided.

Examples of the fluorine and / or silicon-containing surfactants include JP-A-62-36663, JP-A-61-226746, JP-A-61-226745, JP-A-62-170950, JP-A-63- 34540, JP-A-7-230165, JP-A-8-62834, JP-A-9-54432, JP-A-9-5988, and JP-A-2002-277862, and US Patent Nos. 5,405,720, 5,360,692 And 5,529,881, 5,296,330, 5,436,098, 5,576,143, 5,294,511 and 5,824,451. In addition, the following commercial surfactant can be used as it is.

Examples of commercially available surfactants that can be used herein include "Eftop EF301" and "Eftop EF303" (trade name; Shin-Akita Kasei, respectively), "Fluorad FC430" and "Fluorad 431" (trade name; Sumitomo 3M products, respectively). ), "Megaface F171", "Megaface F173", "Megaface F176", "Megaface F189" and "Megaface R08" (trade names; Dainippon Ink & Chemicals, respectively), "Surflon S-382", "Surflon SC101", "Surflon SC102", "Surflon 103", "Surflon 104", "Surflon 105" and "Surflon 106" (trade name; Asahi Glass products, respectively), and "Troysol S-366" (trade name; products of Troy Corporation) Fluorine-containing surfactants and silicone-containing surfactants. Polysiloxane polymer "KP341" (trade name; manufactured by Shin-Etsu Chemical) may also be used as the silicone-containing surfactant.

In addition to the above known surfactants, surfactants using fluoroaliphatic group-containing polymers derived from fluoroaliphatic compounds produced by the telomerization method (also called telomer method) or oligomerization method (also called oligomer method) Can be used. Such fluoro aliphatic compounds can be synthesized by the method described in JP-A-2002-90991.

As said fluoro aliphatic group containing polymer, the copolymer of a fluoro aliphatic group containing monomer, poly (oxyalkylene) acrylate, and / or poly (oxyalkylene) methacrylate is preferable. In the copolymer, these monomers may be distributed irregularly or block copolymerized. Examples of the poly (oxyalkylene) group include poly (oxyethylene) group, poly (oxypropylene) group and poly (oxybutylene) group. Further, the unit may be an alkylene having a different chain length in the same chain, such as block-linked poly (oxyethylene, oxypropylene and oxyethylene) and block-linked poly (oxyethylene and oxypropylene). In addition, copolymers of fluoro aliphatic group-containing monomers and poly (oxyalkylene) acrylates and / or poly (oxyalkylene) methacrylates are not only two copolymers but also trimers or two or more other fluoro aliphatic groups at the same time. The copolymer of the trimmer or more obtained by copolymerizing the monomer which has and two or more other poly (oxyalkylene) acrylate (or methacrylate) may be sufficient.

Examples of commercially available surfactants include "Megaface F178", "Megaface F-470", "Megaface F-473", "Megaface F-475", "Megaface F-476" and "Megaface F-472" (trade names, respectively); Dainippon Ink & Chemicals). Other examples include copolymers of C ₆ F ₁₃ containing acrylate (or methacrylate) and poly (oxyalkylene) acrylate (or methacrylate), C ₆ F ₁₃ containing acrylate (or methacrylate), poly Copolymers of (oxyethylene) acrylate (or methacrylate) and poly (oxypropylene) acrylate (or methacrylate), C ₈ F ₁₇ containing acrylate (or methacrylate) and poly (oxyalkylene) Copolymers of acrylate (or methacrylate), C ₈ F ₁₇ containing acrylate (or methacrylate), poly (oxyethylene) acrylate (or methacrylate) and poly (oxypropylene) acrylate (or meta Acrylates) copolymers.

Examples of surfactants other than the fluorine and / or silicon containing surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene / polyoxypropylene block copolymers, sorbitan aliphatic esters, and polyoxyethylene sorbets. Nonionic surfactants, such as a carbon aliphatic ester, are included.

These surfactants may be used alone or in combination.

It is preferable that the said surfactant is used in the quantity of 0.0001-2 mass% with respect to the total content (excluding a solvent) of the said positive photosensitive composition, More preferably, it is 0.001-1 mass%.

(G) A dissolution inhibiting compound (hereinafter may be described as a “dissolution blocking compound”) having at least one group selected from alkali-soluble groups, hydrophilic groups and acid-decomposable groups and having a molecular weight of 3000 or less may be added.

As the dissolution inhibiting compound (G), a compound having an alkali-soluble group such as a carboxyl group, a sulfonylimide group or a hydroxyl group whose α-position is substituted with a fluoroalkyl group, a hydroxyl group, a lactone group, a cyano group, an amide group And compounds having a hydrophilic group such as a pyrrolidone group or a sulfonamide group, or a compound having a group which is decomposed by the action of an acid to release its alkali-soluble group or a hydrophilic group. The group which decomposes by the action of an acid and releases its alkali-soluble group or hydrophilic group is preferably a carboxyl group or a hydroxyl group protected with an acid-decomposable group. In order to prevent a decrease in permeability of 200 nm or less, a compound containing no aromatic ring is used as the dissolution inhibiting compound, or an aromatic ring-containing compound is added in an amount of 20% by weight or less based on the solids content of the composition. It is preferable.

Preferred examples of the dissolution inhibiting compound include a carboxylic acid compound having an alicyclic hydrocarbon structure such as adamantane (di) carboxylic acid, norbornanecarboxylic acid and cholic acid, and obtained by protecting such a carboxylic acid with an acid-decomposable group. Polyols, such as a compound and a polysaccharide, and the compound obtained by protecting the hydroxyl group of the said polyol with an acid-decomposable group are contained.

In the present invention, the dissolution inhibiting compound has a molecular weight of 3000 or less, preferably 300 to 3000, more preferably 500 to 2500.

The dissolution inhibiting compound is preferably added in an amount of 3 to 40 mass% with respect to the solid content of the photosensitive composition, and more preferably 5 to 20 mass%.

Although the following is the specific example of the said dissolution inhibiting compound, this invention is not limited to them.

<Other additives>

The positive photosensitive composition of the present invention may further contain a compound which promotes dissolution in a dye, a plasticizer, a photosensitizer and a developing solution, if necessary.

The dissolution promoting compound in the developing solution which can be used in the present invention is a low molecular weight compound having a molecular weight of 1,000 or less and having two or more phenolic OH groups or one or more carboxyl groups. It is preferable that the said compound in the case of having a carboxyl group is an alicyclic or aliphatic compound.

It is preferable that the said dissolution promoting compound is added in 2-50 mass% with respect to the said acid-decomposable resin, More preferably, it is 5-30 mass%. At the time of development, an amount of 50% by mass or less is preferable from the viewpoint of reducing the development residue and preventing the pattern deformation.

Such phenolic compounds having a molecular weight of 1,000 or less can be readily synthesized by those skilled in the art with reference to, for example, the processes described in JP-A-4-122938 and JP-A-2-28531, US Pat. No. 4,916,210 and EP219294. Can be.

Specific examples of the carboxyl-containing alicyclic or aliphatic compound include carboxylic acid derivatives having a steroid structure such as cholic acid, deoxycholic acid, and lithocholic acid, adamantanecarboxylic acid derivatives, adamantanedicarboxylic acid, Cyclohexanecarboxylic acid, cyclohexanecarboxylic acid, and cyclohexanedicarboxylic acid are included, but are not limited to these.

(Pattern formation method)

The positive photosensitive composition of the present invention is used by dissolving the component in a predetermined organic solvent, preferably the mixed solvent, filtering the aqueous solution, and applying the filtrate onto a predetermined support as follows. The filter used for filtration consists of polytetrafluoroethylene, polyethylene or nylon and preferably has a pore size of 0.1 micron or less, more preferably 0.05 micron or less, even more preferably 0.03 micron or less.

For example, the positive photosensitive composition is applied on a substrate (silicon / silicon dioxide coated substrate, etc.) such as used in the manufacture of precision integrated circuit devices by a suitable coating method such as spinner or coater, and then dried. A photosensitive film is formed.

The photosensitive film is exposed to actinic light or radiation through a predetermined mask, preferably baked (heated), and then developed and cleaned to obtain an excellent pattern.

When exposing to actinic light or radiation, it is preferable that exposure (immersion exposure) is performed by filling a liquid having a refractive index higher than air between the photosensitive film and the lens. By this immersion exposure, the resolution can be improved. The immersion medium may be any liquid as long as it has a higher refractive index than air, but pure water is preferred. In order to prevent the immersion medium and the photosensitive film from directly contacting during immersion exposure, an overcoat layer may be provided on the photosensitive film. This prevents the release of the composition from the photosensitive film into the immersion medium, thereby reducing development defects.

Prior to formation of the photosensitive film, an antireflection film may be formed in advance by coating.

As the anti-reflection film, an inorganic film such as titanium, titanium dioxide, titanium nitride, chromium oxide, carbon or amorphous silicon, or an organic film made of a light absorber and a polymer material can be used. Examples of the organic antireflection film include "DUV-30 series" or "DUV-40 series" (trade name) of Brewer Science or "AR-2", "AR-3" or "AR-5" (trade name) of Shipley. Commercially available organic antireflective films can also be used.

Examples of actinic or radiation include infrared light, visible light, ultraviolet light, far ultraviolet light, X-rays and electron beams. Among them, far ultraviolet light having a wavelength of 250 nm or less, more preferably 220 nm or less is preferable. Specific examples include KrF excimer laser light (248 nm), ArF excimer laser light (193 nm), F ₂ excimer laser light (157 nm), X-rays and electron beams, ArF excimer laser light, F ₂ excimer laser light, EUV ( 13 nm) and electron beams are preferred.

In the developing step, an alkaline developer is used as follows. As the alkaline developer for the resist composition, inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate or ammonia water, primary amines such as ethylamine or n-propylamine , Secondary amines such as diethylamine or di-n-butylamine, tertiary amines such as triethylamine or methyldiethylamine, alcohol amines such as dimethylethanolamine or triethanolamine, tetramethylammonium hydroxide or tetra Aqueous solutions of quaternary ammonium salts such as ethylammonium hydroxide, or alkaline aqueous solutions such as cyclic amines such as pyrrole or piperidine can be used.

In addition, the alkali developer may be used to which an appropriate amount of alcohol or surfactant is added.

The alkali developer usually has an alkali concentration of 0.1 to 20% by mass.

The alkaline developer usually has a pH of 10.0 to 15.0.

Example 1

In the following, the present invention is described in more detail. However, it should be kept in mind that the present invention is not limited to them.

Synthesis Example: Synthesis of Resin (C)

25.63 g tert-butylacrylate was dissolved in propylene glycol monomethyl ether acetate to prepare 117.92 g of a solution having a 20% solids content concentration. To the solution was added 2.0 mole% (0.921 g) of polymerization initiator "V601" (trade name, manufactured by Wako Pure Chemical Industries). In a nitrogen atmosphere, the mixture was added dropwise to 10.25 g of propylene glycol monomethyl ether acetate heated to 80 ° C. for 4 hours. After the dropwise addition, the reaction mixture was stirred at 80 ° C. for 2 hours. The reaction mixture was cooled to room temperature and then added dropwise to 20 times methanol relative to the reaction mixture. The precipitated solid was collected through filtration to give 22.1 g of resin HR-1 as the intended product.

The resin had a weight average molecular weight of 12000 and a degree of dispersion of 2.0 as measured by GPC measurements on polystyrene standards.

The other resin as resin (C) was similarly manufactured.

<Resist Manufacturing>

The components shown in Table 2 below were dissolved in a solvent, and solutions having a solid content concentration of 7% by mass were prepared, respectively. The solution was filtered through a polyethylene filter with a pore size of 0.1 μm to prepare a positive resist composition. The positive resist composition thus prepared was evaluated by the following method, and the results are shown in the table below.

Those mass ratios when a plurality of components are used are shown in the table.

[Image Performance Test] (Condition 1)

An organic antireflective coating " ARC291 " (trade name; manufactured by Nissan Chemical) was applied onto the silicon wafer, and then baked at 205 ° C. for 60 seconds to form an antireflection film of 78 nm. Subsequently, the prepared positive resist composition was applied to the antireflection film, and then baked at 120 ° C. for 60 seconds to prepare a resist film of 250 nm. The wafer thus obtained was subjected to pattern exposure with an ArF excimer laser scanner (“PAS 5500/1100”, trade name; ASML, NA: 0.75, sigma 0 / σ1 = 0.85 / 0.55). After heating at 120 ° C. for 60 seconds, development for 30 seconds with aqueous tetramethyl ammonium hydroxide solution (2.38 wt%), washing with pure water, and spin drying were performed successfully to obtain a resist pattern.

(Condition 2)

This condition is for formation of a resist pattern following immersion exposure using pure water.

An organic antireflective coating " ARC291 " (trade name; manufactured by Nissan Chemical) was applied on the silicon wafer, and then baked at 205 DEG C for 60 seconds to form an antireflection film of 78 nm. Subsequently, the prepared positive resist composition was applied to the antireflection film, and then baked at 120 ° C. for 60 seconds to prepare a resist film of 250 nm. The wafer thus obtained was subjected to pattern exposure with an ArF excimer laser scanner (NA: 0.75). As the immersion liquid, ultra pure water having an impurity concentration of 5 ppb or less was used. After heating at 120 ° C. for 60 seconds, development for 30 seconds with aqueous tetramethyl ammonium hydroxide solution (2.38 wt%), washing with pure water, and spin drying were performed successfully to obtain a resist pattern.

[Evaluation of Line Edge Roughness]

The evaluation of the line edge roughness (LER) was observed through a length-measuring scanning electron microscope (SEM) to observe an isolated pattern of 120 nm, and the baseline at which the edge should exist for the longitudinal edge of the line pattern in the range of 5 μm. The distance from the line was measured at 50 locations using the length measurement SEM ("S-8840", trade name; manufactured by Hitachi Ltd.), and the standard deviation was measured to calculate 3σ. The unit is nm. Smaller values indicate better performance.

Harvestability

Each of the prepared positive resist compositions was applied onto a silicon wafer and baked at 115 ° C. for 60 seconds to form a resist film of 200 nm. As illustrated in FIG. 1, 15 ml of distilled water was dropped from the pipette to the center of the wafer 1 with the resist film formed thereon. Subsequently, the combustion chamber 2 and the provided 10 cm square quartz plate were placed in the distilled water pond so that the entire space between the wafer 1 and the quartz plate 3 was filled with distilled water 4.

Subsequently, the combustion chamber 2 attached to the quartz plate 3 in the state in which the wafer 1 was fixed was wound around the rotating part of the motor 5 rotating at a speed of 30 cm / sec. The motor was driven for 0.5 seconds to move the quartz plate 3. After the quartz plate 3 was moved, the amount of distilled water remaining under the quartz plate 3 was evaluated according to the following criteria and used as an index of harvestability.

2A to 2D schematically illustrate various patterns observed when the quartz plate is observed after the movement. The slanted portion 6 is an area of distilled water remaining under the quartz plate 3, while the blank portion 7 is an area into which the distilled water does not track the movement of the quartz plate 3 but enters air.

As shown in Fig. 2A, when the distilled water remains on the entire surface of the substrate even after the quartz plate 3 is moved, the harvestability is A; As shown in FIG. 2B, when the air-containing cotton foot does not exceed about 10% of the total substrate area, the harvest is B, and as shown in FIG. 2C, the air-filled area is 20% of the total substrate area. Above, but less than 50%, the harvest is C; As shown in Fig. 2D, when the area of the entire substrate area containing air is about 50% or more, the harvest is called D.

The symbols used in Table 2 have the following meanings, respectively.

The structure and the like of the acid-decomposable resin (A) used in the examples will be shown below.

The structure of compound (B) used in the examples will be shown below.

N-1: N, N-dibutylaniline

N-2: tetrabutylammonium hydroxide

N-3: 2,6-diisopropylaniline

N-4: tri-n-octylamine

N-5: N, N-dihydroxyethylaniline

N-6: N, N-dihexylaniline

W-1: "Megaface F176" (trade name; Dainippon Ink & Chemicals) (containing fluorine)

W-2: "Megaface R08" (trade name; Dainippon Ink & Chemicals) (containing fluorine and silicone)

W-3: Polysiloxane Polymer "KP-341" (trade name; manufactured by Shin-Etsu Chemical) (contains silicone)

W-4: "Troysol S-366" (trade name; manufactured by Troy Corporation)

W-5: "PF656" (trade name; product of OMNOVA, containing fluorine)

W-6: "PF6320" (trade name; product of OMNOVA, containing fluorine)

SL-1: cyclohexanone

SL-2: Propylene Glycol Monomethyl Ether Acetate

SL-3: 2-heptanone

SL-4: Propylene Glycol Monomethyl Ether

SL-5: γ-butyrolactone

SL-6: Propylene Carbonate

From the results shown in Table 2, it is evident that the photosensitive composition of the present invention has good harvestability during immersion exposure and has reduced line edge roughness.

The present invention relates to a positive resist composition which causes less line edge roughness due to general exposure or immersion exposure and is excellent in harvestability during immersion exposure; And it provides a pattern forming method using the composition.

The entire publication of each and every foreign patent application for which the benefit of foreign priority is claimed in this application has been introduced as described herein with reference.

1 is a schematic diagram (side view) related to the evaluation of harvest;

2A-2D are schematic diagrams (plan views) related to the evaluation of harvest.

Claims (10)

(A) Resin which has an acid-decomposable repeating unit represented by general formula (I), and whose solubility to alkaline developing solution increases by the action of an acid; (B) a compound that generates an acid upon irradiation with actinic light or radiation; (C) Resin which does not contain fluorine and silicone and has at least 1 repeating unit chosen from repeating units represented by general formula (C-I)-(C-III); And (D) A positive photosensitive composition comprising a solvent.

[In the general formula (I), Xa ₁ represents a hydrogen atom, an alkyl group, a cyano group or a halogen atom, Ry ₁ to Ry ₃ each independently represent an alkyl group or a cycloalkyl group, and two or more of Ry ₁ to Ry ₃ may be bonded to each other to form a ring structure, Z represents a divalent linking group.]

[In the above general formula (C-I) to (C-III), R ₁ each independently represent a hydrogen atom or a methyl group, Each R ₂ independently represents a hydrocarbon group having at least one —CH ₃ partial structure, P ₁ represents a single bond or an alkylene group, an ether group or a linking group having two or more thereof, P ₂ represents a linking group selected from —O—, —NR— (R represents a hydrogen atom or an alkyl group) and —NHSO ₂ —, n represents the integer of 1-4.] The positive resist composition according to claim 1, wherein Z in General Formula (I) is a divalent linear hydrocarbon group or a divalent cyclic hydrocarbon group. The positive resist composition according to claim 1, wherein the resin (A) further has a repeating unit having at least one group selected from lactone groups, hydroxyl groups, cyano groups, and acid groups. The method of claim 1, The compound (B) is a positive resist composition comprising a compound for generating an acid represented by the general formula (BII):

[In the above general formula (BII), Rb ₁ represents a group having an electron withdrawing group, Rb ₂ represents an organic group having no electron withdrawing group, m and n respectively represent the integer of 0-5, provided that m + n <= 5, When m represents 2 or more, some Rb < ₁ > may be the same or different, when n represents 2 or more, a plurality of Rb ₂ may be the same or different.] The compound of claim 4, wherein in formula (BII), m represents 1 to 5, and the electron withdrawing group of Rb ₁ is one or more selected from a fluorine atom, a fluoroalkyl group, a nitro group, an ester group, and a cyano group A positive resist composition characterized by an atom or a group. The method of claim 1, Said resin (C) further has a repeating unit represented by general formula (C), The positive resist composition characterized by the above-mentioned.

[In the general formula (C), X ₁ , X ₂ and X ₃ each independently represent a hydrogen atom, an alkyl group, or a halogen atom, L represents a single bond or a divalent linking group, Rp ₁ represents an acid-decomposable group.] The method of claim 6, The repeating unit represented by the general formula (C) is a repeating unit represented by the general formula (C1).

[In the general formula (C1), X ₁ , X ₂ and X ₃ each independently represent a hydrogen atom, an alkyl group, or a halogen atom, R ₁₂ , R ₁₃ and R ₁₄ each independently represent an alkyl group, a cycloalkyl group, an alkenyl group and an aryl group, provided that R ₁₂ , R ₁₃ and R ₁₄ At least one of which represents an alkyl group, R ₁₂ , R ₁₃ and R ₁₄ Two of them may combine to form a ring.] The positive resist composition according to claim 1, wherein light having a wavelength of 200 nm or less is used for exposure. Forming a resist film from the positive resist composition according to claim 1; And Exposing and developing the resist film. The method of claim 9, And the resist film is exposed through an immersion liquid.

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