JP5879719B2 - Radiation sensitive resin composition and pattern forming method - Google Patents

Description

  The present invention relates to a radiation-sensitive resin composition and a pattern forming method.

  In the field of microfabrication for manufacturing integrated circuit elements, etc., lithography using radiation with shorter wavelengths such as KrF excimer laser (wavelength 248 nm) and ArF excimer laser (wavelength 193 nm) in order to obtain a higher degree of integration. Technology is being developed. As a material for forming a photoresist film for excimer laser, a chemically amplified resist containing a component having an acid dissociable group and an acid generator that generates an acid upon irradiation with radiation is generally used. According to this chemically amplified resist, an acid is generated in the exposed area by the irradiation of the radiation, and a chemical reaction using this acid as a catalyst causes a difference in the dissolution rate in the developer between the exposed area and the unexposed area, thereby forming a pattern. Can be made.

  As a lithographic material corresponding to such an ArF excimer laser, for example, a radiation-sensitive resin composition containing a lactone-containing (meth) acrylic polymer is known as one capable of obtaining excellent resolution and depth of focus. (See Patent Documents 1 to 3). As such lithography materials, a resist composition using a resin containing a specific lactone structural unit in which a spacer is introduced between a polymer main chain and a lactone skeleton has been developed. In addition to resolution and line edge roughness, Improvements such as dependency and exposure margin have been studied (see Patent Documents 4 to 9).

  However, in recent years when further miniaturization of devices is progressing, the above-mentioned conventional composition cannot sufficiently satisfy these requirements. Accordingly, a radiation-sensitive resin composition having improved LWR (Line Width Roughness) and cross-sectional shape in a line and space pattern, CDU (Critical Dimension Uniformity) in a narrow pitch in a contact hole pattern, particularly a line width of 45 nm or less. There is an urgent need to develop a radiation-sensitive resin composition that can be adapted to an immersion process and a pattern forming method using the same.

JP-A-9-90637 JP-A-10-274852 JP 2000-26446 A JP 2005-352466 A JP 2004-210917 A JP 2008-31298 A JP 2003-5375 A JP 2003-255537 A JP 2003-252933 A

  The present invention has been made based on the above circumstances, and the object thereof is excellent in LWR and cross-sectional shape in a line-and-space pattern, and CDU in a narrow pitch in a contact hole pattern, and particularly in a line width of 45 nm or less. A radiation-sensitive resin composition that can be adapted to an immersion process and a pattern forming method using the same.

（式（１）中、Ｒ^１は水素原子、メチル基、フッ素原子、又はトリフルオロメチル基である。Ａは炭素数１〜４の２価の連結基である。Ｑは１価のラクトン基又はスルトン基である。上記ラクトン基及びスルトン基の水素原子の一部又は全部は置換されていてもよい。
式（２）中、Ｘ^＋はオニウムカチオンである。Ｙはフッ素原子を含有しないｔ＋１価の炭化水素基である。Ｚは水素原子又は１価の有機基である。ｔは１〜３の整数である。但し、ｔが２以上の場合、複数のＺは同一でも異なっていてもよい。） The invention made to solve the above problems is
[A] a polymer having a structural unit (I) represented by the following formula (1) (hereinafter also referred to as “[A] polymer”), and [B] a compound represented by the following formula (2). Containing acid generator (hereinafter also referred to as “[B] acid generator”)
Is a radiation-sensitive resin composition.

(In Formula (1), R ¹ is a hydrogen atom, a methyl group, a fluorine atom, or a trifluoromethyl group. A is a divalent linking group having 1 to 4 carbon atoms. Q is a monovalent lactone group. Or a part or all of hydrogen atoms of the lactone group and sultone group may be substituted.
In the formula (2), X ⁺ is an onium cation. Y is a t + 1 valent hydrocarbon group containing no fluorine atom. Z is a hydrogen atom or a monovalent organic group. t is an integer of 1 to 3. However, when t is 2 or more, the plurality of Z may be the same or different. )

  The radiation-sensitive resin composition is excellent in LWR and cross-sectional shape in a line-and-space pattern of a resist film to be formed by containing the [A] polymer and the [B] acid generator having the specific structure. In addition, the CDU in the contact hole pattern is satisfied. The reason is not necessarily clear, but the [A] polymer has a linking group represented by A in the above formula (1) between the lactone group or sultone group and the ester group bonded to the polymer molecular chain. Therefore, an appropriate space is ensured, whereby the rigidity of the polymer is appropriately lowered, the affinity for the developer is increased and the solubility is improved, and at the same time, the [B] acid generator is also present in the resist film. As a result, it can be considered that the above-described characteristics of the resulting resist film are improved.

（式（ｑ−１）中、ｍは０〜２の整数である。Ｒ^２はアルキル基、アルコキシ基、ヒドロキシル基、シアノ基、−ＣＯＯＲ^４、又は−ＯＣ（＝Ｏ）Ｒ^５であり、このアルキル基の水素原子の一部又は全部はハロゲン原子又はヒドロキシル基で置換されていてもよい。ｍが２の場合、２つのＲ^２は同一でも異なっていてもよい。Ｒ^４及びＲ^５はそれぞれ独立して水素原子又はアルキル基である。Ｒ^３はメチレン基、炭素数２〜５のアルキレン基、酸素原子又は硫黄原子であり、このアルキレン基は炭素鎖中に酸素原子又は硫黄原子を含んでいてもよい。＊は上記式（１）中のＡに結合する部位を示す。） Q in the structural unit (I) is preferably represented by the following formula (q-1).

(In Formula (q-1), m is an integer of 0 to ^2. R ² is an alkyl group, an alkoxy group, a hydroxyl group, a cyano group, —COOR ⁴ , or —OC (═O) R ⁵ , in this case some or all of the hydrogen atoms of the alkyl group may be substituted with a halogen atom or a hydroxyl group .m is 2, the two R ² are good .R ⁴ and R ⁵ may be the same or different Each independently represents a hydrogen atom or an alkyl group, and R ³ represents a methylene group, an alkylene group having 2 to 5 carbon atoms, an oxygen atom or a sulfur atom, and the alkylene group contains an oxygen atom or a sulfur atom in the carbon chain. (* Indicates a site that binds to A in the above formula (1).)

  When the Q is a lactone group represented by the formula (q-1), the resist film formed from the radiation-sensitive resin composition is excellent in LWR and cross-sectional shape in a line and space pattern, and contact The CDU in the hole pattern is further improved.

（式（ｑ−２）中、ｎは０〜２の整数である。Ｒ^６はアルキル基、アルコキシ基、ヒドロキシル基、シアノ基、−ＣＯＯＲ^８、又は−ＯＣ（＝Ｏ）Ｒ^９であり、このアルキル基の水素原子の一部又は全部はハロゲン原子又はヒドロキシル基で置換されていてもよい。ｎが２の場合、２つのＲ^２は同一でも異なっていてもよい。Ｒ^８及びＲ^９はそれぞれ独立して水素原子又はアルキル基である。Ｒ^７はメチレン基、炭素数２〜５のアルキレン基、酸素原子又は硫黄原子であり、上記アルキレン基は炭素鎖中に酸素原子又は硫黄原子を含んでいてもよい。＊は上記式（１）中のＡに結合する部位を示す。） Q in the structural unit (I) is preferably represented by the following formula (q-2).

(In formula (q-2), n is an integer of 0 to 2. R ⁶ is an alkyl group, an alkoxy group, a hydroxyl group, a cyano group, —COOR ⁸ , or —OC (═O) R ⁹ , A part or all of the hydrogen atoms of this alkyl group may be substituted with a halogen atom or a hydroxyl group, and when n is 2, two R ² may be the same or different, and R ⁸ and R ⁹ are Each independently represents a hydrogen atom or an alkyl group, and R ⁷ is a methylene group, an alkylene group having 2 to 5 carbon atoms, an oxygen atom or a sulfur atom, and the alkylene group contains an oxygen atom or a sulfur atom in the carbon chain. (* Indicates a site that binds to A in the above formula (1).)

  When the Q is a sultone group represented by the formula (q-2), the resist film formed from the radiation-sensitive resin composition is excellent in LWR and cross-sectional shape in a line and space pattern, and contact The CDU in the hole pattern is further improved.

A in the structural unit (I) is preferably —CH ₂ CH ₂ O— * or —CH ₂ COO— *.
(However, * indicates a site that binds to the lactone group or sultone group.)

  When the A is the specific structure, in the [A] polymer, an appropriate space is formed between the lactone group or the sulfone group and the ester group bonded to the polymer molecular chain. As a result, the rigidity of the polymer is suitably reduced, and the affinity for the developer and the like is further increased to improve the solubility, so that the properties of CDU and the like are further improved.

  [A] The polymer preferably further has a structural unit (II) containing an acid dissociable group. The resist film formed from the radiation-sensitive resin composition containing the [A] polymer having such a structural unit (II) is excellent in LWR and cross-sectional shape in a line and space pattern, and a contact hole pattern The CDU at is further improved.

（Ｘ^２＋はオニウムカチオンである。Ｒ^１０はフッ素原子又は炭素数１〜４の炭化水素基であり、この炭化水素基の水素原子の一部又は全部は置換されていてもよい。Ｚ^２は水素原子又は１価の有機基である。） [B] It is preferable that the acid generator further includes a compound represented by the following formula (3).

(X ²⁺ is .R ¹⁰ is an onium cation is a fluorine atom or a hydrocarbon group having 1 to 4 carbon atoms, optionally .Z ² substituted in some or all of the hydrogen atoms of the hydrocarbon group It is a hydrogen atom or a monovalent organic group.)

  [B] When the acid generator further contains a compound represented by the above formula (3), two acid generators having the specific structure are used in combination, and the acid generator is formed from the radiation-sensitive resin composition. The resist film is excellent in LWR and cross-sectional shape in a line and space pattern, and can further improve CDU in a contact hole pattern.

  The radiation-sensitive resin composition preferably further contains a polymer containing [C] fluorine atoms. When the radiation-sensitive composition contains the [C] polymer, the hydrophobicity of the resist film is improved. In particular, when immersion exposure is performed, the material elution is excellent, and the resist film and the immersion liquid The receding contact angle can be sufficiently high, and there are effects such as no water droplets remaining when scanning exposure is performed at high speed. As a result, the resist film formed from the radiation-sensitive resin composition is excellent in the LWR and the cross-sectional shape in the line and space pattern, and the CDU in the contact hole pattern is further improved.

The present invention
(1) a resist film forming step of applying the radiation sensitive resin composition on a substrate;
(2) an exposure step of exposing the resist film, and (3) a development step of developing the exposed resist film,
Including a pattern forming method.

  According to the pattern forming method of the present invention, it is possible to form a fine resist pattern that is superior in LWR and sectional shape in a line and space pattern, further improves CDU in a contact hole pattern, and has excellent lithography characteristics.

  The “radiation” of the “radiation-sensitive resin composition” in the present specification is a concept including visible light, ultraviolet light, far ultraviolet light, X-rays, charged particle beams and the like.

  According to the radiation-sensitive resin composition of the present invention, it is possible to form a fine resist pattern having excellent lithography characteristics such as LWR and cross-sectional shape in a line and space pattern, CDU at a narrow pitch in a contact hole pattern, and the like. .

<Radiation sensitive resin composition>
The radiation sensitive resin composition of the present invention contains a [A] polymer and a [B] acid generator. Moreover, the polymer containing a [C] fluorine atom can be contained suitably. Furthermore, as long as the effects of the present invention are not impaired, the [D] acid diffusion controller, the [E] solvent, and other optional components can be contained. Hereinafter, each component will be described in detail.

<[A] polymer>
[A] polymer which the said radiation sensitive resin composition contains has the structural unit (I) represented by the said Formula (1). Since the structural unit (I) has a linking group represented by A between the lactone group or sultone group and the ester group bonded to the polymer molecular chain, [A] the rigidity of the polymer is It is considered that the solubility is moderately decreased, the affinity for the solvent and the developer is increased, and the solubility is improved. At the same time, the [B] acid generator is easily dispersed in the resist film. As a result, the resulting resist film is superior in LWR and cross-sectional shape in a line and space pattern, and has true CDU in a contact hole pattern. It is thought that it will further improve. [A] The polymer preferably further has the structural unit (II). Moreover, you may have structural unit (III) and structural unit (IV) as needed. Each will be described in detail below.

[Structural unit (I)]
The structural unit (I) is represented by the above formula (1). In the above formula (1), R ¹ is hydrogen atom, a methyl group, a fluorine atom or a trifluoromethyl group. A is a C1-C4 bivalent coupling group. Q is a monovalent lactone group or sultone group. Some or all of the hydrogen atoms of the lactone group and sultone group may be substituted.

Although the C1-C4 bivalent coupling group represented by A in said formula (1) is not specifically limited, The group represented by following formula (4) is preferable.
^{-R 11 -R 12 -O- * ··· (} 4)

In the formula (4), R ¹¹ is a methylene group or a linear or branched alkylene group having 2 to 4 carbon atoms. R ¹² is a single bond or a carbonyl group. However, * shows the site | part couple | bonded with Q in Formula (1).

Examples of R ¹¹ include a methylene group, an ethylene group, and a propylene group. Of these, a methylene group and an ethylene group are preferable. As the above-mentioned _{A, -CH 2 CH 2 O- *} , or _-CH 2 COO- * are preferred.

  In the above formula (1), the lactone group represented by Q is a group obtained by removing one of the hydrogen atoms of the lactone ring, and the lactone ring is a simple substance including a structure represented by —O—C (O) —. Refers to a ring or polycycle. The sultone group refers to a group obtained by removing one hydrogen atom of the sultone ring, and the sultone ring refers to a ring including a cyclic sulfonate structure.

  Examples of the lactone group represented by Q include groups represented by the following formulas (L-1) to (L-6).

In the above formulas (L-1) to (L-6), R ^Lc1 is a methylene group, an alkylene group having 2 to 5 carbon atoms, an oxygen atom, or a sulfur atom. R ^Lc2 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n _Lc1 is 0 or 1. _nLc2 is an integer of 0-3. * Shows the site | part couple | bonded with A in said formula (1). In addition, the group represented by Formula (L-1)-(L-6) may have a substituent.

  Examples of the substituent that the lactone group may have include a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, and the like. Of these, a methyl group or an ethyl group is preferable. Moreover, as a preferable aspect, the thing by which the monovalent organic group containing the said lactone ring is substituted by substituents other than a cyano group can be mentioned. Furthermore, another preferred embodiment is one in which the monovalent organic group containing the lactone ring has no substituent.

  Among the above formulas (L-1) to (L-6), a lactone group represented by (L-1) is preferable, and among the lactone groups represented by (L-1), a lactone group represented by the above formula (q-1). Is more preferable.

In said formula (q-1), m is an integer of 0-2. R ² is an alkyl group, an alkoxy group, a hydroxyl group, a cyano group, —COOR ⁴ , or —OC (═O) R ⁵ , and a part or all of the hydrogen atoms of this alkyl group are substituted with a halogen atom or a hydroxyl group May be. When m is 2, two R ² may be the same or different. R ⁴ and R ⁵ are each independently a hydrogen atom or an alkyl group. R ³ is a methylene group, an alkylene group having 2 to 5 carbon atoms, an oxygen atom or a sulfur atom, and this alkylene group may contain an oxygen atom or a sulfur atom in the carbon chain. * Shows the site | part couple | bonded with A in the said Formula (1).

Examples of the alkyl group represented by R ² include a methyl group, an ethyl group, a propyl group, and a butyl group.

Examples of the alkoxy group represented by R ² include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group.

^{R 4} in -COOR ⁴ where the ^{R 2} represents, and the alkyl group ^{R 5} in -OC (= O) ^{R 5,} for example, be mentioned the same group as those exemplified as the alkyl group above ^{R 2} represents it can.

Examples of the alkylene group represented by R ³ include an ethylene group, a propylene group, and a butylene group.

  In the above formula (1), examples of the sultone group represented by Q include groups represented by the following formulas (S-1) to (S-6).

In formulas (S-1) to (S-6), R ^Sc1 represents a methylene group, an alkylene group having 2 to 5 carbon atoms, an oxygen atom, or a sulfur atom. R ^Sc2 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n _Sc1 is 0 or 1. n _Sc2 is an integer of 0 to 3. * Shows the site | part couple | bonded with A in said formula (1). In addition, the group shown by Formula (S-1)-(S-6) may have a substituent.

  Examples of the substituent that the sultone group may have include the same groups as those exemplified as the substituent that the lactone group may have.

  Of the above formulas (S-1) to (S-6), the sultone group represented by (S-1) is preferable, and the sultone group represented by the above formula (q-2) among the sultone groups represented by (S-1). Is more preferable.

In formula (q-2), n is an integer of 0-2. R ⁶ is an alkyl group, an alkoxy group, a hydroxyl group, a cyano group, —COOR ⁸ , or —OC (═O) R ⁹ , and a part or all of the hydrogen atoms of this alkyl group are substituted with a halogen atom or a hydroxyl group. May be. When n is 2, two R ² may be the same or different. R ⁸ and R ⁹ are each independently a hydrogen atom or an alkyl group. R ⁷ is a methylene group, an alkylene group having 2 to 5 carbon atoms, an oxygen atom or a sulfur atom, and the alkylene group may contain an oxygen atom or a sulfur atom in the carbon chain. * Shows the site | part couple | bonded with A in the said Formula (1).

Examples of the alkyl group represented by R ⁶ include a methyl group, an ethyl group, a propyl group, and a butyl group.

Examples of the alkoxy group represented by R ⁶ include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group.

The alkyl group ^{R 9} in the ^{R 8} in -COOR ^{8 in which R 6} represents, and -OC (= O) ^{R 9,} may include the same groups as those exemplified as the alkyl group above ^{R 2} represents .

Examples of the alkylene group represented by R ⁷ include the same groups as those exemplified as the alkylene group represented by R ⁷ .

  Examples of the structural unit (I) include structural units represented by the following formulas.

In the above formula, R ^L1 and R ^S1 are a hydrogen atom, a methyl group, or a trifluoromethyl group.

  Of these, structural units represented by (1-1), (1-2), and (1-5) are preferred.

  As content rate of structural unit (I), 5 mol%-70 mol% are preferable with respect to all the structural units which comprise a [A] polymer, and 10 mol%-60 mol% are more preferable. In addition, the [A] polymer may have 1 type, or 2 or more types of structural units (I).

[Structural unit (II)]
[A] The polymer preferably further has a structural unit (II) containing an acid dissociable group. The structural unit (II) is represented by the following formula (5).

In the above formula (5), R ¹³ is a hydrogen atom, a methyl group, a fluorine atom or a trifluoromethyl group. R ^p is an acid dissociable group.

The acid dissociable group represented by R ^p is preferably a group represented by the following formula (6).

In said formula (6), R ^<p1> is a C1-C4 alkyl group or a C4-C20 monovalent alicyclic hydrocarbon group. R ^p2 and R ^p3 are each independently an alkyl group having 1 to 4 carbon atoms or an alicyclic hydrocarbon group having 4 to 20 carbon atoms. R ^p2 and R ^p3 may be bonded to each other to form a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms together with the carbon atoms to which R ^p2 and R ^p3 are bonded.

Examples of the alkyl group having 1 to 4 carbon atoms represented by R ^p1 , R ^p2 and R ^p3 include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a 2-methylpropyl group, Examples include 1-methylpropyl group and t-butyl group.

Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by R ^p1 , R ^p2 and R ^p3 include a polycyclic alicyclic group having a bridged skeleton such as an adamantane skeleton and a norbornane skeleton. ;
And monocyclic alicyclic groups having a cycloalkane skeleton such as cyclopentane and cyclohexane. In addition, these groups may be substituted with one or more linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms, for example.

The acid dissociable group represented by R ^p, R ^p1 is an alkyl group having 1 to 4 carbon atoms, adamantane skeleton, or a cycloalkyl together with the carbon atom to which R ^p2 and R ^p3 are attached respectively bonded to each other It is preferable to form a divalent group having an alkane skeleton.

  Examples of the structural unit (II) include structural units represented by the following formulas (2-1) to (2-4).

In the above formulas (2-1) to (2-4), R ¹³ has the same meaning as the above formula (5). R ^p1 , R ^p2 and R ^p3 are as defined in the above formula (6). n _p is an integer of 1 to 3.

  Examples of the structural unit represented by the formula (5) or (2-1) to (2-4) include a structural unit represented by the following formula.

In said formula, R < ¹³ > is synonymous with the said Formula (5).

  As a content rate of structural unit (II), 20 mol%-60 mol% are preferable with respect to all the structural units which comprise a [A] polymer. In addition, the [A] polymer may have 1 type, or 2 or more types of structural units (II).

[Structural unit (III)]
[A] The polymer may further contain a structural unit (III) having a lactone group or a sultone group. [A] When the polymer further includes a structural unit (III) having a lactone group or a sultone group, basic resist characteristics such as adhesion between the resist film and the substrate can be further improved. Further, the solubility of the resist film in the developer can be increased. The structural unit (III) does not include the structural unit represented by the above formula (1).

  [A] It is more preferable that the polymer has a structural unit (III-2) represented by the following formula (7) together with the structural unit (I) represented by the above formula (1). The structural unit (I) represented by the above formula (1) has a group represented by the above A between an organic group containing a lactone ring and an ester group. On the other hand, in the structural unit (III-2), a lactone group is directly bonded to an ester group. [A] When the polymer contains both of these structural units, both lactone skeleton parts are dispersed and arranged around the polymer chain, so that space is secured and the rigidity of the polymer is moderately reduced. To do. As a result, the affinity between the polymer [A] and the developer is improved, and the solubility in the developer is increased. For the same reason as described above, for example, a reaction between an acid generated from an acid generator or the like and an acid dissociable group is also promoted. As a result, it is considered that the resolution of the obtained pattern is improved. In addition, when the [A] polymer has the structural unit (I) and the structural unit (III-2) represented by the above formula (1), the groups each having a lactone skeleton are groups having the same structure. Preferably there is. By doing so, it is excellent in the LWR and the cross-sectional shape in the line and space pattern of the resist film obtained, and the roundness CDU in the contact hole pattern is further improved. There is also an advantage that synthesis is easy.

In the above formula (7), R ^LS1 is a hydrogen atom, a methyl group, a fluorine atom or a trifluoromethyl group. W is a lactone group or a sultone group. A part or all of the hydrogen atoms of the lactone group may be substituted with a substituent.

  Examples of the structural unit (III) include a structural unit represented by the following formula.

In the above formula, R ^LS1 has the same ^{meaning as} in the above formula (7).

  As content rate of structural unit (III), 1 mol%-60 mol% are preferable with respect to all the structural units which comprise a [A] polymer, and 5 mol%-40 mol% are more preferable. If the content of the structural unit (III) is less than 1 mol%, the adhesion between the resist film and the substrate may not be improved. On the other hand, when the content ratio of the structural unit (III) exceeds 60 mol%, the pattern formability may be lowered. In addition, the [A] polymer may have 1 type, or 2 or more types of structural units (III).

[Structural unit (IV)]
[A] The polymer may further have a structural unit containing a hydroxyl group represented by the following formula (hereinafter sometimes referred to as “structural unit (IV)”). The structural unit (IV) is not particularly limited as long as the structural unit has a hydroxyl group. The number of hydroxyl groups in the structural unit may be one or two or more. Further, the position of the hydroxyl group in the structural unit is not particularly limited. Examples of the structural unit (IV) include a structural unit represented by the following formula.

In the above formula, R ¹⁴ is a hydrogen atom, a methyl group, a fluorine atom or a trifluoromethyl group.

  As a content rate of structural unit (IV), 1 mol%-50 mol% are preferable with respect to all the structural units which comprise a [A] polymer, and 5 mol%-30 mol% are more preferable. In addition, the [A] polymer may have 1 type, or 2 or more types of structural units (IV).

  [A] The polymer may have other structural units in addition to the structural units (I) to (IV). For example, the structural unit etc. which have a carbonate structure are mentioned.

<[A] Polymer Synthesis Method>
[A] The polymer can be synthesized according to a conventional method such as radical polymerization. As a synthesis method, for example,
A method in which a solution containing a monomer and a radical initiator is dropped into a reaction solvent or a solution containing a monomer to cause a polymerization reaction;
A method in which a solution containing a monomer and a solution containing a radical initiator are separately dropped into a reaction solvent or a solution containing a monomer to cause a polymerization reaction;
A method such as a method in which a plurality of types of solutions containing each monomer and a solution containing a radical initiator are separately added to a reaction solvent or a solution containing a monomer to cause a polymerization reaction is preferable. In addition, when the monomer solution is dropped and reacted with respect to the monomer solution, the monomer amount in the dropped monomer solution is 30 mol with respect to the total amount of monomers used for polymerization. % Or more is preferable, 50 mol% or more is more preferable, and 70 mol% or more is particularly preferable.

  What is necessary is just to determine the reaction temperature in these methods suitably with initiator seed | species. Usually, it is 30 to 180 ° C, preferably 40 to 160 ° C, and more preferably 50 to 140 ° C. The dropping time varies depending on the reaction temperature, the type of initiator, the monomer to be reacted, etc., but is usually 30 minutes to 8 hours, preferably 45 minutes to 6 hours, and more preferably 1 hour to 5 hours. . Further, the total reaction time including the dropping time varies depending on the conditions similarly to the dropping time, but is usually 30 minutes to 8 hours, preferably 45 minutes to 7 hours, and more preferably 1 hour to 6 hours.

  Examples of the radical initiator used in the polymerization include azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2 -Cyclopropylpropionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile) and the like. These initiators can be used alone or in admixture of two or more.

  The polymerization solvent is not limited as long as it is a solvent other than a solvent that inhibits polymerization (nitrobenzene having a polymerization inhibiting effect, mercapto compound having a chain transfer effect, etc.) and can dissolve the monomer. Examples of the polymerization solvent include alcohol solvents, ketone solvents, amide solvents, ester / lactone solvents, nitrile solvents, and mixed solvents thereof. These solvents can be used alone or in combination of two or more.

  The resin obtained by the polymerization reaction is preferably recovered by a reprecipitation method. That is, after completion of the polymerization reaction, the target resin is recovered as a powder by introducing the polymerization solution into a reprecipitation solvent. As the reprecipitation solvent, alcohols or alkanes can be used alone or in admixture of two or more. In addition to the reprecipitation method, the resin can be recovered by removing low-molecular components such as monomers and oligomers by a liquid separation operation, a column operation, an ultrafiltration operation, or the like.

  [A] The weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is not particularly limited, but is preferably 1,000 or more and 100,000 or less, more preferably 2,000 or more and 50,000 or less. Preferably, it is 3,000 or more and 10,000 or less. In addition, when the Mw of the [A] polymer is less than 1,000, the heat resistance when used as a resist tends to decrease. On the other hand, when the Mw of the [B] polymer exceeds 500,000, the developability when used as a resist tends to be lowered.

  [A] The ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC of the polymer is usually from 1 to 5, preferably from 1 to 3, preferably from 1 to 2. More preferred. By setting Mw / Mn in such a range, the photoresist film has excellent resolution performance.

  Mw and Mn in this specification are GPC columns (Tosoh Corp., 2 G2000HXL, 1 G3000HXL, 1 G4000HXL) under the analysis conditions of a flow rate of 1.0 ml / min, elution solvent tetrahydrofuran, and column temperature of 40 ° C. The value measured by GPC using monodisperse polystyrene as a standard.

<[B] Acid generator>
[B] The acid generator generates an acid upon exposure. The acid dissociates the acid dissociable group present in the [A] polymer, and as a result, the [A] polymer becomes soluble in the developer. The contained form of the [B] acid generator in the radiation-sensitive resin composition is a cation or anion even in the form of a compound as described later (hereinafter sometimes referred to as “[B] acid generator” as appropriate). Or both may be incorporated as part of the polymer, or both.

  [B] The acid generator includes a compound represented by the above formula (2).

In the above formula (2), X ⁺ is an onium cation. Y is a t + 1 valent carbon hydrogen group containing no fluorine atom. Z is a hydrogen atom or a monovalent organic group. t is an integer of 1 to 3. However, when t is 2 or more, the plurality of Z may be the same or different.

In the above formula (2), examples of the onium cation represented by X ⁺ include a sulfonium cation, an ammonium cation, a phosphonium cation, an iodonium cation, and a pyridinium cation. Of these cations, sulfonium cations are preferred, and preferred specific examples include those represented by the following formula.

  In the above formula (2), examples of the t + 1 valent hydrocarbon group represented by Y include a linear, branched or cyclic t + 1 valent aliphatic hydrocarbon group, a t + 1 valent aromatic hydrocarbon group, and the like.

  Examples of the t + 1 valent aliphatic hydrocarbon group include a methylene group, an ethylene group, a propylene group, a butylene group, a cyclobutylene group, and a cyclohexylene group. Of these, an ethylene group is preferred.

  Examples of the t + 1 valent aromatic hydrocarbon group include groups obtained by removing t + 1 hydrogen atoms from a benzene ring, naphthalene ring, phenanthrene ring, anthracene ring, and the like.

  In the above formula (2), examples of the monovalent organic group represented by Z include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group and the like, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group and the like, and a carboxyl group. And a group formed in combination with a group, an ether group, an amide group, and the like.

  Examples of the anion in the compound represented by the above formula (2) include an anion represented by the following formula.

  [B] The acid generator preferably further contains a compound represented by the above formula (3).

In the formula (3), ^{X 2} is an onium cation. R ¹⁰ is a fluorine atom or a hydrocarbon group having 1 to 4 carbon atoms. Some or all of the hydrogen atoms of the hydrocarbon group may be substituted. Z ² is a hydrogen atom or a monovalent organic group.

In the above formula (3), examples of the onium cation represented by X ² include onium cations equivalent to those exemplified as the onium cation represented by X. Of these, a sulfonium cation is preferable, and a triphenylsulfonium cation is more preferable.

In the above formula (3), the hydrocarbon group having 1 to 4 carbon atoms represented by R ^10, a methyl group, an ethyl group, a propyl group, a butyl group.

In the above formula (3), examples of the monovalent organic group represented by Z ² include the same groups as those exemplified as the monovalent organic group represented by Z.

  Examples of the sulfonium salt represented by the above formula (3) include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, triphenylsulfonium 2-bicyclohexane. [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-cyclohexylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyldiphenylsulfonium 2-bicyclo 2.2.1] Hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium 1,1,2,2-tetrafluoro-6- (1-adamantane carbonyloxy)- Examples include hexane-1-sulfonate. Among these, triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylphosphonium 1,1,2,2-tetrafluoro-6- (1-adamantanecarbonyloxy) -hexane-1 -Sulfonate is preferred. Of these, triphenylsulfonium 1,1,2,2-tetrafluoro-6- (1-adamantanecarbonyloxy) -hexane-1-sulfonate represented by the following formula is more preferable.

  [B] The acid generator may contain compounds other than those described above. For example, sulfonimide compounds, halogen-containing compounds, diazoketone compounds and the like can be mentioned.

Examples of the sulfonimide compound include N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (nonafluoro-n-butanesulfonyloxy) bicyclo [ 2.2.1] Hept-5-ene-2,3-dicarboximide, N- (perfluoro-n-octanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3- Dicarboximide, N- (2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene 2,3-dicarboximide, N- (2- (3- tetracyclo ^[4.4.0.1 2,5 ^{.1 7,10]} dodecanyl) -1,1-difluoroethane-sulfonyl Oxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (camphorsulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-di Carboximide etc. can be mentioned. Of these sulfonimide compounds, N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide is preferred.

  These [B] acid generators may be used alone or in combination of two or more. [B] The amount used when the acid generator is an acid generator is usually 0.1 mass with respect to 100 parts by mass of the polymer [A] from the viewpoint of ensuring sensitivity and developability as a resist. Part to 20 parts by mass, preferably 5 parts to 18 parts by mass. Moreover, as a compound represented by said Formula (2), it is 0.1 mass part or more and 20 mass parts or less normally with respect to 100 mass parts of [A] polymers, Preferably it is 1 mass part or more and 18 mass parts or less. It is. As a compound represented by the said Formula (3), it is 1 to 20 mass parts normally with respect to 100 mass parts of [A] polymers, Preferably it is 5 to 15 mass parts. In this case, if the amount of the [B] acid generator used is less than 0.1 parts by mass, the sensitivity and developability tend to decrease. On the other hand, if the amount exceeds 20 parts by mass, the transparency to radiation decreases, which is desired. It tends to be difficult to obtain a resist pattern.

<[C] Polymer containing fluorine atom>
The radiation-sensitive resin composition can further contain a polymer containing [C] fluorine atom (hereinafter, also referred to as “[C] polymer”) as a suitable component. When the radiation-sensitive composition contains a [C] polymer, the hydrophobicity of the resist film is improved, and even when immersion exposure is performed, it is excellent in suppression of substance elution, and the resist film and the immersion liquid The receding contact angle can be made sufficiently high, and when the scan exposure is performed at a high speed, there are effects such as no water droplets remaining, so that the usefulness of the radiation sensitive composition for immersion exposure is enhanced. The [C] polymer does not include the polymer [A].

[C] Examples of the polymer include, for example, a structure in which a fluorinated alkyl group is bonded to the main chain;
A structure in which a fluorinated alkyl group is bonded to the side chain;
Examples include a structure in which a fluorinated alkyl group is bonded to the main chain and the side chain.

  As a monomer that gives a structure in which a fluorinated alkyl group is bonded to the main chain, for example, an α-trifluoromethyl acrylate compound, a β-trifluoromethyl acrylate compound, an α, β-trifluoromethyl acrylate compound, one or more types Examples thereof include compounds in which the hydrogen at the vinyl moiety is substituted with a fluorinated alkyl group such as a trifluoromethyl group.

  Monomers that give a structure in which a fluorinated alkyl group is bonded to the side chain include, for example, those in which the side chain of an alicyclic olefin compound such as norbornene is a fluorinated alkyl group or a derivative thereof, acrylic acid or methacrylic acid side Examples thereof include ester compounds in which the chain is a fluorinated alkyl group or a derivative thereof, and one or more olefin side chains (sites not including a double bond) being a fluorinated alkyl group or a derivative thereof.

  Examples of the monomer that gives a structure in which a fluorinated alkyl group is bonded to the main chain and the side chain include α-trifluoromethylacrylic acid, β-trifluoromethylacrylic acid, α, β-trifluoromethylacrylic acid, and the like. Is a fluorinated alkyl group or its derivative ester compound. One or more vinyl moiety hydrogens are substituted with a fluorinated alkyl group such as a trifluoromethyl group. The hydrogen bonded to the double bond of one or more alicyclic olefin compounds is replaced with a fluorinated alkyl group such as a trifluoromethyl group, and the side chain is a fluorinated alkyl group or a derivative thereof. And the like. In addition, an alicyclic olefin compound shows the compound in which a part of ring is a double bond.

  [C] The polymer preferably has (c1) structural unit represented by the following formula (8) and / or (c2) structural unit represented by formula (9), and (c1) structural unit and (c2) ) You may have "other structural units" other than a structural unit. Hereinafter, each structural unit will be described in detail.

[(C1) Structural unit]
(C1) The structural unit is a structural unit represented by the following formula (8).

In the above formula (8), R ¹⁵ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ¹⁶ is a linear or branched alkyl group having 1 to 6 carbon atoms having a fluorine atom, or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms having a fluorine atom. However, in the alkyl group and alicyclic hydrocarbon group, part or all of the hydrogen atoms may be substituted.

  As said C1-C6 linear or branched alkyl group, a methyl group, an ethyl group, a propyl group, a butyl group etc. are mentioned, for example.

  Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms include a cyclopentyl group, a cyclopentylpropyl group, a cyclohexyl group, a cyclohexylmethyl group, a cycloheptyl group, a cyclooctyl group, and a cyclooctylmethyl group.

  (C1) Monomers that give structural units include, for example, trifluoromethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, perfluoroethyl (meth) acrylate, perfluoro n-propyl ( (Meth) acrylate, perfluoro i-propyl (meth) acrylate, perfluoro n-butyl (meth) acrylate, perfluoro i-butyl (meth) acrylate, perfluoro t-butyl (meth) acrylate, perfluorocyclohexyl (meth) Acrylate, 2- (1,1,1,3,3,3-hexafluoro) propyl (meth) acrylate, 1- (2,2,3,3,4,4,5,5-octafluoro) pentyl ( (Meth) acrylate, 1- (2,2,3,3,4,4,5,5-octafluoro) hex (Meth) acrylate, perfluorocyclohexylmethyl (meth) acrylate, 1- (2,2,3,3,3-pentafluoro) propyl (meth) acrylate, 1- (2,2,3,3,4, 4,4-Heptafluoro) penta (meth) acrylate, 1- (3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10- Heptadecafluoro) decyl (meth) acrylate, 1- (5-trifluoromethyl-3,3,4,4,5,6,6,6-octafluoro) hexyl (meth) acrylate and the like.

  Examples of the structural unit (c1) include structural units represented by the following formulas (8-1) and (8-2).

In the formulas (8-1) and (8-2), R ¹⁵ has the same meaning as the formula (8).

  (C1) The content of the structural unit is preferably 10 mol% to 70 mol%, more preferably 20 mol% to 50 mol%, based on all the structural units constituting the [C] polymer. [B] The polymer may have (c1) one or more structural units.

[(C2) Structural unit]
(C2) The structural unit is a structural unit represented by the following formula (9).

In the above formula (9), R ¹⁷ is a hydrogen atom, a methyl group or a trifluoromethyl group. R ¹⁸ is a (k + 1) -valent linking group. V is a divalent linking group having a fluorine atom. R ¹⁹ is a hydrogen atom or a monovalent organic group. k is an integer of 1 to 3. However, when k is 2 or 3, the plurality of V and R ¹⁹ may be the same or different.

In the above formula (9), examples of the (k + 1) -valent linking group represented by R ¹⁸ include a linear or branched hydrocarbon group having 1 to 30 carbon atoms and an alicyclic hydrocarbon having 3 to 30 carbon atoms. A group, an aromatic hydrocarbon group having 6 to 30 carbon atoms, or one or more groups selected from the group consisting of these groups and an oxygen atom, a sulfur atom, an ether group, an ester group, a carbonyl group, an imino group, and an amide group And a combination of these. The (k + 1) -valent linking group may have a substituent.

  Examples of the linear or branched hydrocarbon group having 1 to 30 carbon atoms include (k + 1) hydrocarbon groups such as methane, ethane, propane, butane, pentane, hexane, heptane, decane, icosane and triacontane. And a group in which a hydrogen atom is removed.

Examples of the alicyclic hydrocarbon group having 3 to 30 carbon atoms include monocyclic saturated hydrocarbons such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclodecane, methylcyclohexane, and ethylcyclohexane;
Monocyclic unsaturated hydrocarbons such as cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclodecene, cyclopentadiene, cyclohexadiene, cyclooctadiene, cyclodecadiene;
Bicyclo [2.2.1] heptane, bicyclo [2.2.2] octane, tricyclo [5.2.1.0 ^2,6 ] decane, tricyclo [3.3.1.1 ^3,7 ] decane, Tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] polycyclic saturated hydrocarbons such as dodecane and adamantane;
Bicyclo [2.2.1] heptene, bicyclo [2.2.2] octene, tricyclo [5.2.1.0 ^2,6 ] decene, tricyclo [3.3.1.1 ^3,7 ] decene, Tetracyclo [6.2.1.1 ^3,6 . And a group obtained by removing (m + 1) hydrogen atoms from a polycyclic hydrocarbon group such as 0 ^2,7 ] dodecene.

  Examples of the aromatic hydrocarbon group having 6 to 30 carbon atoms include an aromatic hydrocarbon group such as benzene, naphthalene, phenanthrene, anthracene, tetracene, pentacene, pyrene, picene, toluene, xylene, ethylbenzene, mesitylene, cumene and the like (m + 1). ) Groups from which a single hydrogen atom has been removed.

  In said formula (9), as a bivalent coupling group which has a fluorine atom which V shows, a C1-C20 bivalent linear hydrocarbon group which has a fluorine atom is mentioned. Examples of V include structures represented by the following formulas (V-1) to (V-6).

  V is preferably a structure represented by the above formulas (V-1) and (V-2).

In the above formula (9), examples of the organic group represented by R ¹⁹ include a linear or branched hydrocarbon group having 1 to 30 carbon atoms, an alicyclic hydrocarbon group having 3 to 30 carbon atoms, and 6 carbon atoms. To 30 aromatic hydrocarbon groups, or a combination of these groups and one or more groups selected from the group consisting of oxygen, sulfur, ether, ester, carbonyl, imino and amide groups Is mentioned.

  Examples of the structural unit (c2) include structural units represented by the following formulas (9-1) and (9-2).

In the formula (9-1), R ¹⁸ is a divalent linear, branched or cyclic hydrocarbon group of saturated or unsaturated having 1 to 20 carbon atoms. R ¹⁷ , V and R ¹⁹ are as defined in the above formula (9).
In the formula (9-2), R ¹⁷ , V, R ¹⁹ and k are as defined in the above formula (9). However, when k is 2 or 3, the plurality of V and R ¹⁹ may be the same or different.

  As the structural unit represented by the above formula (9-1) and formula (9-2), for example, the following formula (9-1-1), formula (9-1-2) and formula (9-2-1) The structural unit etc. which are shown are mentioned.

In the formulas (9-1-1), (9-1-2), and (9-2-1), R ¹⁷ has the same meaning as the formula (9).

  (C2) Monomers that give structural units include, for example, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-3-propyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-butyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy -5-pentyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester, (meth) acrylic acid 2-{[5- ( 1 ′, 1 ′, 1′-trifluoro-2′-trifluoromethyl-2′-hydroxy) propyl] bicyclo [2.2.1] heptyl} ester and the like.

  (C2) The content of the structural unit is preferably 20 mol% to 80 mol%, more preferably 30 mol% to 70 mol%, based on all the structural units constituting the [C] polymer. In addition, a [C] polymer may have 1 type, or 2 or more types of (c2) structural units.

  In the [C] polymer, the content of other structural units is usually 90 mol% or less, preferably 20 mol% to 80 mol%, based on all the structural units constituting the [C] polymer, 30 More preferred is mol% to 70 mol%. In addition, the [C] polymer may have 1 type, or 2 or more types of other structural units.

  [C] As a compounding quantity of a polymer, 0.1 mass part-20 mass parts are preferable with respect to 100 mass parts of [A] polymers, 1 mass part-10 mass parts are more preferable, and 1 mass part- 7.5 parts by mass is particularly preferable. If it is less than 0.1 part by mass, the effect of containing the [C] polymer may not be sufficient. On the other hand, when the amount exceeds 20 parts by mass, the water repellency of the resist surface becomes too high and development failure may occur.

[C] The fluorine atom content in the polymer is preferably larger than that of the polymer [A]. The content ratio of fluorine atoms in the [C] polymer is usually 5% by mass or more, preferably 5% by mass to 50% by mass, more preferably 5%, based on 100% by mass of the total amount of the [C] polymer. It is mass%-45 mass%. In addition, this fluorine atom content rate can be measured by ¹³ C-NMR. [C] A photoresist formed of a radiation-sensitive resin composition containing the [C] polymer and the [A] polymer when the fluorine atom content in the polymer is larger than that of the [A] polymer. The water repellency of the film surface can be increased, and there is no need to separately form an upper layer film during immersion exposure. In order to sufficiently exhibit the above effect, the difference between the fluorine atom content in the [C] polymer and the fluorine atom content in the [C] polymer is 1% by mass or more. Preferably, it is 5 mass% or more.

<[C] Polymer Synthesis Method>
[C] The polymer can be produced, for example, by polymerizing a monomer corresponding to each predetermined structural unit in a suitable solvent using a radical polymerization initiator.

Examples of the solvent used for the polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane;
Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane;
Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene;
Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, chlorobenzene;
Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate and methyl propionate;
Ketones such as acetone, 2-butanone, 4-methyl-2-pentanone, 2-heptanone;
Ethers such as tetrahydrofuran, dimethoxyethanes, diethoxyethanes;
Examples include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol. These solvents may be used alone or in combination of two or more.

  As reaction temperature in the said superposition | polymerization, 40 to 150 degreeC and 50 to 120 degreeC are preferable normally. The reaction time is usually preferably 1 hour to 48 hours and 1 hour to 24 hours.

  [C] The Mw of the polymer is preferably 1,000 to 50,000, more preferably 2,000 to 20,000, and particularly preferably 3,000 to 10,000. [C] When the Mw of the polymer is less than 1,000, a sufficient receding contact angle cannot be obtained. On the other hand, when Mw exceeds 50,000, the developability of the resist tends to decrease.

  [C] The ratio (Mw / Mn) between the polymer Mw and the polystyrene-equivalent number average molecular weight (Mn) by the GPC method is preferably 1 to 5, and more preferably 1 to 4.

<[D] Acid diffusion controller>
[D] The acid diffusion controller controls the diffusion phenomenon of the acid generated from the [B] acid generator upon exposure in the resist film, and has the effect of suppressing undesirable chemical reactions in the unexposed areas. Moreover, while the radiation sensitive resin composition contains the [D] acid diffusion controller, the storage stability of the radiation sensitive resin composition is further improved, and the resolution as a resist is further improved. It is possible to suppress a change in the line width of the resist pattern due to a change in the holding time from exposure to development processing. Furthermore, the process stability is also excellent. The content of the acid diffusion controller in the radiation-sensitive resin composition was incorporated as part of the polymer even in the form of a free compound (hereinafter also referred to as “[D] acid diffusion controller” as appropriate). It may be in the form or both forms.

  [D] Examples of the acid diffusion controller include amine compounds, amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, and the like.

  Examples of the amine compound include mono (cyclo) alkylamines; di (cyclo) alkylamines; tri (cyclo) alkylamines; substituted alkylanilines or derivatives thereof; ethylenediamine, N, N, N ′, N′-tetra Methylethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminobenzophenone, 4,4′-diaminodiphenylamine, 2,2-bis (4 -Aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2- (4-aminophenyl) -2- (3-hydroxyphenyl) propane, 2- (4-amino) Phenyl) -2- (4-hydroxyphenyl) propane, 1, -Bis (1- (4-aminophenyl) -1-methylethyl) benzene, 1,3-bis (1- (4-aminophenyl) -1-methylethyl) benzene, bis (2-dimethylaminoethyl) ether Bis (2-diethylaminoethyl) ether, 1- (2-hydroxyethyl) -2-imidazolidinone, 2-quinoxalinol, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, N, N, N ′, N ″ N ″ -pentamethyldiethylenetriamine and the like.

  Examples of amide group-containing compounds include Nt-butoxycarbonyl group-containing amino compounds, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, Examples thereof include benzamide, pyrrolidone, N-methylpyrrolidone, N-acetyl-1-adamantylamine, and isocyanuric acid tris (2-hydroxyethyl).

  Examples of urea compounds include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tri-n-butylthiourea and the like. Is mentioned.

  Examples of the nitrogen-containing heterocyclic compound include imidazoles; pyridines; piperazines; pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, piperidine, piperidine ethanol, 3-piperidino-1,2-propanediol, morpholine, 4- Methylmorpholine, 1- (4-morpholinyl) ethanol, 4-acetylmorpholine, 3- (N-morpholino) -1,2-propanediol, 1,4-dimethylpiperazine, 1,4-diazabicyclo [2.2.2 ] Octane etc. are mentioned.

  Further, as the [D] acid diffusion control agent, a photodisintegratable base that is exposed to light and generates a weak acid by exposure can also be used. As an example of the photodegradable base, there is an onium salt compound that is decomposed by exposure and loses acid diffusion controllability. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (10) and an iodonium salt compound represented by the following formula (11).

In the above formula (10) and formula (11), R ^{20 to} R ²⁴ are each independently a hydrogen atom, an alkyl group, an alkoxyl group, a hydroxyl group or a halogen atom. In the formula (10) and equation (11), G ^- is ^{OH -,} R 25 -COO - or ^R 25 -SO ₃ ^- is. However, R ²⁵ is an alkyl group, an aryl group, an alkaryl group, or an anion represented by the following formula (12).

In the above formula (12), R ²⁶ is a linear or branched alkyl group having 1 to 12 carbon atoms in which part or all of the hydrogen atoms may be substituted with fluorine atoms, or C 1 to 12 carbon atoms. It is a linear or branched alkoxyl group. u is 1 or 2.

  These [D] acid diffusion inhibitors may be used alone or in combination of two or more. [D] The content of the acid diffusion controller is preferably less than 10 parts by mass with respect to 100 parts by mass of the [A] polymer. When the total amount used exceeds 10 parts by mass, the sensitivity as a resist tends to decrease.

[[E] solvent]
The radiation sensitive resin composition usually contains a solvent. The solvent is not particularly limited as long as it can dissolve at least the [A] polymer and [B] acid generator, the [C] polymer, [D] acid diffusion controller and other optional components added as necessary. [E] Examples of the solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, and mixed solvents thereof.

Examples of alcohol solvents include methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, 2-methylbutanol, sec-pentanol, tert-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol , Sec-octanol, n-nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec -Monoalcohol solvents such as heptadecyl alcohol, furfuryl alcohol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, diacetone alcohol;
Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2 -Polyhydric alcohol solvents such as ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol;
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, polyhydric alcohol partial ether solvents such as dipropylene glycol monopropyl ether.

  Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, methyl-n-pentyl ketone, ethyl-n-butyl ketone, methyl-n- Ketones such as hexyl ketone, di-iso-butyl ketone, trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, diacetone alcohol, acetophenone A solvent is mentioned.

  Examples of the amide solvents include N, N′-dimethylimidazolidinone, N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropionamide, N-methylpyrrolidone and the like can be mentioned.

  Examples of the ester solvents include diethyl carbonate, propylene carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, γ-valerolactone, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec sec -Butyl, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, n-nonyl acetate, acetoacetic acid Methyl, ethyl acetoacetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol acetate Cole mono-n-butyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, diacetic acid Glycol, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate , Diethyl malonate, dimethyl phthalate, diethyl phthalate and the like.

Examples of other solvents include n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, cyclohexane, Aliphatic hydrocarbon solvents such as methylcyclohexane;
Fragrances such as benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, iso-propylbenzene, diethylbenzene, iso-butylbenzene, triethylbenzene, di-iso-propylbenzene and n-amylnaphthalene Group hydrocarbon solvents;
And halogen-containing solvents such as dichloromethane, chloroform, chlorofluorocarbon, chlorobenzene, and dichlorobenzene.

  Of these solvents, propylene glycol monomethyl ether acetate, cyclohexanone, and γ-butyrolactone are preferred.

<Other optional components>
The radiation-sensitive resin composition includes an essential component [A] polymer and [B] acid generator, a suitable component [C] polymer, an optionally added [D] acid nucleic acid control agent, and In addition to the solvent [E], a surfactant, an alicyclic skeleton-containing compound, a sensitizer and the like can be contained as other optional components as long as the effects of the present invention are not impaired.

[Surfactant]
Surfactants have the effect of improving coatability, striation, developability, and the like. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol diacrylate. In addition to nonionic surfactants such as stearate, the following trade names are KP341 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, Kyoeisha Chemical Co., Ltd.), F-Top EF301, EF303, EF352 (above, Tochem Products), MegaFuck F171, F173 (above, Dainippon Ink and Chemicals), Florard FC430, FC431 ( Sumitomo 3M), Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, Asahi Glass Industry) Company). These surfactants may be used alone or in combination of two or more.

[Alicyclic skeleton-containing compound]
The alicyclic skeleton-containing compound has an effect of improving dry etching resistance, pattern shape, adhesion to the substrate, and the like.

Examples of the alicyclic skeleton-containing compound include adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and 1-adamantanecarboxylic acid t-butyl;
Deoxycholic acid esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholic acid, 2-ethoxyethyl deoxycholic acid;
Lithocholic acid esters such as t-butyl lithocholic acid, t-butoxycarbonylmethyl lithocholic acid, 2-ethoxyethyl lithocholic acid;
3- [2-Hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] nonane, and the like. These alicyclic skeleton containing compounds may be used independently and may use 2 or more types together.

[Sensitizer]
The sensitizer exhibits the effect of increasing the amount of [B] acid generators produced, and has the effect of improving the “apparent sensitivity” of the composition.

  Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines and the like. These sensitizers may be used alone or in combination of two or more.

<Preparation of radiation-sensitive resin composition>
In the composition, [A] polymer, [B] acid generator, [C] polymer, [D] acid diffusion controller, [E] solvent, and other optional components are mixed at a predetermined ratio. Can be prepared. Moreover, the said radiation sensitive resin composition can be prepared and used in the state melt | dissolved or disperse | distributed to the appropriate organic solvent.

<Pattern formation method>
The present invention includes (1) a resist film forming step of applying a radiation-sensitive resin composition on a substrate (hereinafter also referred to as “(1) step”), and (2) an exposure step of exposing the resist film (hereinafter referred to as “step”). (3) a pattern forming method including a step of developing the exposed resist film (hereinafter also referred to as “(3) step”). Hereinafter, each process is explained in full detail.

[(1) Process]
In this step, the composition used in the present invention is applied onto a substrate to form a resist film. As the substrate, for example, a conventionally known substrate such as a silicon wafer or a wafer coated with aluminum can be used. Further, for example, an organic or inorganic antireflection film disclosed in Japanese Patent Publication No. 6-12452, Japanese Patent Application Laid-Open No. 59-93448, or the like may be formed on the substrate.

  Examples of the coating method include spin coating (spin coating), cast coating, and roll coating. In addition, as a film thickness of the resist film formed, it is 0.01 micrometer-1 micrometer normally, and 0.01 micrometer-0.5 micrometer are preferable.

  After apply | coating the said composition, you may volatilize the solvent in a coating film by prebaking (PB) as needed. The heating conditions for PB are appropriately selected depending on the composition of the composition, but are usually about 30 ° C to 200 ° C, preferably 50 ° C to 150 ° C.

  In order to prevent the influence of basic impurities contained in the environmental atmosphere, a protective film disclosed in, for example, Japanese Patent Laid-Open No. 5-188598 can be provided on the resist layer. Furthermore, in order to prevent the acid generator and the like from flowing out of the resist layer, a liquid immersion protective film disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-352384 can be provided on the resist layer. These techniques can be used in combination.

[(2) Process]
In this step, exposure is performed by reducing and projecting onto a desired region of the resist film formed in the step (1) through a mask having a specific pattern and, if necessary, an immersion liquid. For example, an isotrench pattern can be formed by performing reduced projection exposure on a desired region through an isoline pattern mask. Moreover, you may perform exposure twice or more with a desired pattern and a mask pattern. When performing exposure twice or more, it is preferable to perform exposure continuously. In the case of performing multiple exposures, for example, a first reduced projection exposure is performed on a desired area via a line and space pattern mask, and then the second is so that the line intersects the exposed portion where the first exposure has been performed. Reduced projection exposure is performed. The first exposure part and the second exposure part are preferably orthogonal. By being orthogonal, it becomes easy to form a perfect circular contact hole pattern in the unexposed area surrounded by the exposed area. Examples of the immersion liquid used for exposure include water and a fluorine-based inert liquid. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has a refractive index temperature coefficient that is as small as possible so as to minimize distortion of the optical image projected onto the film. In the case of excimer laser light (wavelength 193 nm), it is preferable to use water from the viewpoints of availability and easy handling in addition to the above-described viewpoints. When water is used, an additive that decreases the surface tension of water and increases the surface activity may be added in a small proportion. This additive is preferably one that does not dissolve the resist layer on the wafer and can ignore the influence on the optical coating on the lower surface of the lens. The water used is preferably distilled water.

  The radiation used for the exposure is appropriately selected according to the type of the [B] acid generator, and examples thereof include ultraviolet rays, far ultraviolet rays, X-rays, and charged particle beams. Among these, far ultraviolet rays represented by ArF excimer laser and KrF excimer laser (wavelength 248 nm) are preferable, and ArF excimer laser is more preferable. The exposure conditions such as the exposure amount are appropriately selected according to the composition of the composition, the type of additive, and the like. In the pattern forming method of the present invention, the exposure process may be performed a plurality of times, and the plurality of exposures may be performed using the same light source or different light sources, but ArF excimer laser light is used for the first exposure. Is preferably used.

  In addition, post exposure baking (PEB) is preferably performed after exposure. By performing PEB, the dissociation reaction of the acid dissociable group in the composition can proceed smoothly. As a heating condition of PEB, it is 30 degreeC-200 degreeC normally, and 50 degreeC-170 degreeC is preferable.

[(3) Process]
Next, the exposed coating film is developed to remove unnecessary portions (non-irradiated portions of radiation) and form a predetermined pattern. As the developer used in the development step, an alkaline aqueous solution is preferable. Examples of the alkali include inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and ammonia; quaternary ammonium salts such as tetramethylammonium hydroxide and tetraethylammonium hydroxide. It is done.
In addition, an appropriate amount of a water-soluble organic solvent such as methanol or ethanol or a surfactant can be added to such an alkaline aqueous solution. The concentration of alkali in the aqueous alkali solution is preferably from 0.1% by mass to 5% by mass from the viewpoint of obtaining appropriate developability. As a developing method, for example, an appropriate method such as a liquid piling method, a dipping method, a rocking dipping method, a shower method, or the like can be used. The development time varies depending on the composition of the composition, but is preferably about 10 seconds to 180 seconds. Subsequent to such development processing, for example, washing with running water is performed for 30 seconds to 90 seconds, and then a desired pattern can be formed by, for example, air drying with compressed air or compressed nitrogen.

  As a developing method, for example, a method in which a substrate is immersed in a tank filled with a developer for a certain period of time (dip method), a method in which the developer is raised on the surface of the substrate by surface tension and is left stationary for a certain time (paddle method) ), A method of spraying the developer on the substrate surface (spray method), a method of continuously applying the developer while scanning the developer coating nozzle on the substrate rotating at a constant speed (dynamic dispensing method) Etc.

  The resist pattern thus obtained has excellent resolution and is suitable for fine processing using a lithography technique.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. Moreover, the measuring method of various physical-property values and the evaluation method of various characteristics are shown below.

[Weight average molecular weight (Mw) and number average molecular weight (Mn)]
Using GPC columns (2 G2000HXL, 1 G3000HXL, 1 G4000HXL) manufactured by Tosoh Corporation, flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, column temperature: 40 ° C., with monodisperse polystyrene as standard Measured by gel permeation chromatography (GPC). The degree of dispersion (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[Remaining ratio of low molecular weight component (%)]
Using an Inertsil ODS-25 μm column (4.6 mmφ × 250 mm) manufactured by GL Sciences, high-performance liquid chromatography under analysis conditions of flow rate: 1.0 mL / min, elution solvent: acrylonitrile / 0.1% phosphoric acid aqueous solution (HPLC). In addition, a low molecular weight component means the component which has a monomer as a main component, More specifically, it is a component below the molecular weight of a molecular weight below 1000, Preferably it means the component below the molecular weight of a trimer.

[ ¹³ C-NMR analysis]
The analysis was conducted using the trade name “JNM-EX400” manufactured by JEOL Ltd. and using DMSO as a measurement solvent.

<[A] Synthesis of polymer>

[Synthesis Example 1]
12.4 g (50 mol%) of compound (M-2) and 17.6 g (50 mol%) of compound (M-13) are dissolved in 60 g of 2-butanone, and 1.03 g (5 mol%) of AIBN is added. Thus, a monomer solution was prepared. A 1000 mL three-necked flask containing 30 g of 2-butanone was purged with nitrogen for 30 minutes, then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled with water and cooled to 30 ° C. or lower. The cooled polymerization solution was put into 600 g of methanol, and the precipitated white powder was filtered off. The filtered white powder was washed twice with 120 g of methanol, filtered, and dried at 50 ° C. for 17 hours to obtain a white powdery polymer (A-1) (18.9 g, yield 63). %). Mw of the obtained resin (A-1) was 6,900, Mw / Mn was 1.50, and the residual ratio of the low molecular weight component was 0.05%. Further, as a result of ¹³ C-NMR analysis, a copolymer in which the content ratio of the repeating unit derived from the compound (M-2) to the repeating unit derived from the compound (M-13) is 48.2: 51.8 (mol%). Met. Table 2 shows the formulation used in Synthesis Example 1. In addition, Table 3 shows the measurement results of Mw, Mw / Mn, yield of the obtained copolymer, and the ratio of the repeating unit derived from each monomer in the copolymer.

[Synthesis Examples 2 to 14]
Polymers (A-2) to (A-13) and (a-1) were prepared in the same manner as in Synthesis Example 1 except that a predetermined amount of the types of monomers shown in Table 1 were blended. Moreover, the measurement result of the ratio of the repeating unit derived from each monomer of Mw, Mw / Mn, a yield, and a copolymer of the obtained polymer is shown according to Table 1. In addition, the structure of the used monomer is shown by the following formula.

<Synthesis of [C] polymer>
[Synthesis Example 15]
11.2 g (40 mol%) of compound (M-7) and 18.8 g (60 mol%) of compound (M-18) are dissolved in 30 g of 2-butanone, and 1.44 g (7 mol%) of AIBN is added. Thus, a monomer solution was prepared. A 1000 mL three-necked flask containing 30 g of 2-butanone was purged with nitrogen for 30 minutes, then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled with water and cooled to 30 ° C. or lower. The polymerization solution was concentrated under reduced pressure using an evaporator until the weight of the polymerization solution reached 150 g. Thereafter, the concentrated solution was poured into a mixed solution of 760 g of methanol and 40 g of water to precipitate a slime-like white solid. The liquid part was removed by decantation, and the collected solid was vacuum-dried at 60 ° C. for 15 hours to obtain 18 g of white powdery polymer (C-1). Mw was 3,700 and Mw / Mn was 1.40. As a result of ¹³ C-NMR analysis, the content ratio of the repeating unit derived from the compound (M-7): the repeating unit derived from the compound (M-18) was 39.5: 60.5 (mol%). It was a coalescence. The chemical formula of the monomer used is shown below.

<Preparation of radiation-sensitive resin composition>
The [B] acid generator, [D] acid diffusion controller and [E] solvent used in the preparation of the radiation sensitive resin composition are as follows.

<[B] Acid generator>
B-1: 4-cyclohexylsulfonylphenylsulfonium 1,2-di (cyclohexyloxycarbonyl) ethane-1-sulfonate B-2: triphenylsulfonium 1,1,2,2-tetrafluoro-6- ( 1-adamantanecarbonyloxy) -hexane-1-sulfonate

<[D] Acid diffusion controller>
D-1: Nt-butoxycarbonyl-4-hydroxypiperidine

<[E] solvent>
E-1: Propylene glycol monomethyl ether acetate E-2: Cyclohexanone E-3: γ-butyrolactone

[Example 1]
100 parts by mass of the polymer (A-1) obtained in Synthesis Example 1, 3 parts by mass of the polymer (C-1) obtained in Synthesis Example 15, 3.6 parts by mass of the acid generator (B-1), 8.4 parts by mass of acid generator (B-2), 1 part by mass of acid diffusion controller (D-1), 1633 parts by mass of solvent (E-1), 700 parts by mass of (E-2), (E- 3) 30 parts by mass was mixed, and the resulting mixed solution was filtered with a filter having a pore size of 0.20 μm to prepare a radiation sensitive resin composition. This radiation-sensitive resin composition was designated as composition (J-1).

[Examples 2-14, Comparative Examples 1-3]
The compositions (J-2) to (J-14) and (j-1) to (j-) of the respective radiation-sensitive resin compositions were made in the same manner as in Example 1 except that the formulation shown in Table 2 was used. 3) was prepared.

<Evaluation of contact hole pattern>
The radiation sensitive resin compositions of Examples 1 to 14 and Comparative Examples 1 to 3 were evaluated as follows using an ArF excimer laser as a light source. The results are shown in Table 3 below.

[Measurement of optimal exposure (Eop)]
First, a film having a thickness of 110 nm is formed from a radiation-sensitive resin composition on a 12-inch silicon wafer on which an underlayer antireflection film (“ARC66”, manufactured by Nissan Chemical Co., Ltd.) is formed, and soft baking is performed at 100 degrees for 60 seconds. (SB) was performed. Next, this film was coated with an ArF excimer laser immersion exposure apparatus (“NSR S610C”, manufactured by NIKON) using NA = 1.3, iNA = 1.27, ratio = 0.800, Crosssole (Blade angle 35 degrees). ) Through a mask pattern for pattern formation of 65 nm Hole 110 nm Pitch (6% halftone). After the exposure, each radiation-sensitive resin composition was post-baked (PEB) at the temperature shown in Table 7 for 60 seconds. Thereafter, the resist film was developed with a 2.38 mass% tetramethylammonium hydroxide aqueous solution, washed with water, and dried to form a positive resist pattern. At this time, the exposure amount at which the portion exposed through the 65 nm Hole 110 nm Pitch pattern forming mask pattern forms a hole with a diameter of 57 nm was defined as the optimum exposure amount (Eop). A scanning electron microscope (“CG-4000”, manufactured by Hitachi High-Technologies Corporation) was used for length measurement.

[Evaluation of Critical Dimension Uniformity (CDU)]
A total of 30 hole patterns with a diameter of 57 nm formed by Eop were measured, the average deviation of the total 30 measured values was calculated, and the value obtained by multiplying by 3 was defined as CDU. It can be evaluated that the smaller the CDU value, the better the roundness.

<Evaluation of line & space pattern>
About the radiation sensitive resin composition of the said Examples 1-14 and Comparative Examples 1-3, various evaluation was performed as follows using an ArF excimer laser as a light source. The results are shown in Table 3 below.

[Measurement of optimal exposure (Eop)]
First, a film having a thickness of 110 nm is formed from a radiation-sensitive resin composition on a 12-inch silicon wafer on which an underlayer antireflection film (“ARC66”, manufactured by Nissan Chemical Co., Ltd.) is formed, and soft baking is performed at 100 degrees for 60 seconds. (SB) was performed. Next, this film was coated with an ArF excimer laser immersion exposure apparatus (“NSR S610C”, manufactured by NIKON) using NA = 1.3, iNA = 1.27, ratio = 0.800, DipoleX (Blade Angle 35 degrees). ), Exposure was performed through a mask pattern (6% halftone) for 45 nm Line 90 nm Pitch pattern formation depending on the polarization conditions. After the exposure, each radiation-sensitive resin composition was post-baked (PEB) at the temperature shown in Table 7 for 60 seconds. Thereafter, the resist film was developed with a 2.38 mass% tetramethylammonium hydroxide aqueous solution, washed with water, and dried to form a positive resist pattern. At this time, the exposure amount at which the Line exposed through the mask pattern for pattern formation of 45 nm Line 90 nm Pitch forms 45 nm was defined as the optimum exposure amount (Eop). A scanning electron microscope (“CG-4000”, manufactured by Hitachi High-Technologies Corporation) was used for length measurement.

[Evaluation of Line Width Roughness (LWR)]
A line having a line width of 45 nm formed by the above Eop was observed from the upper part of the pattern, and the line width was measured at arbitrary 10 points. The 3 sigma value (variation) of the measured line width was defined as LWR. A smaller value is more preferable.

[Evaluation of cross-sectional shape]
The case where the cross-sectional shape of the 45 nm Line 90 nm Pitch Line pattern formed by the above Eop was observed with “S-4800” manufactured by Hitachi High-Technologies Corporation and showed a T-top shape (ie, a shape other than a rectangle). The case where it was evaluated as “bad” and showed a rectangular shape was evaluated as “good”.

  As shown in Table 3, an excellent CDU was obtained in the contact hole pattern by using the radiation sensitive resin composition. Moreover, also in the line and space pattern, the LWR and the cross-sectional shape were favorable compared to the comparative example.

  According to the radiation-sensitive resin composition of the present invention, it is possible to form a fine resist pattern having excellent lithography characteristics such as LWR and cross-sectional shape in a line and space pattern, CDU at a narrow pitch in a contact hole pattern, and the like. . It is possible to sufficiently meet the demands corresponding to the further miniaturization of devices in recent years.

Claims (7)

[A] A polymer having a structural unit (I) represented by the following formula (1) and a structural unit (III-2) represented by any of the following formulas (7-1) to (7-11) And [B] a radiation sensitive resin composition containing an acid generator containing a compound represented by the following formula (2) and a compound represented by the following formula (3).

(In Formula (1), R ¹ is a hydrogen atom, a methyl group, a fluorine atom or a trifluoromethyl group. Q is a monovalent lactone group. Some or all of the hydrogen atoms of the lactone group are substituted. A is —CH ₂ CH ₂ O— * or —CH ₂ COO— *, where * represents a site bonded to a lactone group.
In the formula (2), X ⁺ is an onium cation. Y is a linear, branched or cyclic t + 1 valent aliphatic hydrocarbon group containing no fluorine atom. Z is a hydrogen atom or a monovalent organic group. t is an integer of 1 to 3. However, when t is 2 or more, the plurality of Z may be the same or different.
In formula (3), X ²⁺ is a monovalent onium cation. R ¹⁰ is a fluorine atom or a hydrocarbon group having 1 to 4 carbon atoms, and part or all of the hydrogen atoms of this hydrocarbon group may be substituted. Z ² is a hydrogen atom or a monovalent organic group. )

(In formulas (7-1) to (7-11), ^RLS1 is a hydrogen atom, a methyl group, a fluorine atom, or a trifluoromethyl group.) The radiation sensitive resin composition according to claim 1, wherein Q in the structural unit (I) is represented by the following formula (q-1).

(In Formula (q-1), m is an integer of 0 to ^2. R ² is an alkyl group, an alkoxy group, a hydroxyl group, a cyano group, —COOR ⁴ , or —OC (═O) R ⁵ , in this case some or all of the hydrogen atoms of the alkyl group may be substituted with a halogen atom or a hydroxyl group .m is 2, the two R ² are good .R ⁴ and R ⁵ may be the same or different Each independently represents a hydrogen atom or an alkyl group, and R ³ represents a methylene group, an alkylene group having 2 to 5 carbon atoms, an oxygen atom or a sulfur atom, and the alkylene group contains an oxygen atom or a sulfur atom in the carbon chain. (* Indicates a site that binds to A in the above formula (1).)   [A] The radiation sensitive resin composition according to claim 1 or 2, wherein the polymer further has a structural unit (II) containing an acid dissociable group.   [C] The radiation sensitive resin composition according to claim 1, 2 or 3, further comprising a polymer containing a fluorine atom.   [D] The radiation sensitive resin composition according to any one of claims 1 to 4, further comprising an acid diffusion controller.   The content rate of the said structural unit (I) is 10 mol% or more and 60 mol% or less with respect to all the structural units which comprise a [A] polymer, The any one of Claims 1-5. Radiation sensitive resin composition. (1) A resist film forming step of applying the radiation-sensitive resin composition according to any one of claims 1 to 6 on a substrate,
(2) An exposure step of exposing the resist film, and (3) a pattern forming method including a developing step of developing the exposed resist film.