JP2013088763A - Photoresist composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoresist composition having excellent bridging resistance capable of suppressing occurrence of a hole bridge in the formation of a dense contact hole pattern, and having sufficient resolution.SOLUTION: A photoresist composition comprises: [A] a polymer having a structural unit (I-1) including a monocyclic lactone group and a structural unit (II) including an acid-dissociable group; [B] a polymer having a structural unit (I-2) including a polycyclic lactone group, and the structural unit (II) including an acid dissociable group; and [C] a radiation sensitive acid generator.

Description

  The present invention relates to a photoresist composition.

  In order to achieve high integration of large scale integrated circuit devices (LSIs) using semiconductors, development of circuit pattern miniaturization technology is underway. In particular, thinning of wiring patterns constituting a circuit, miniaturization of contact hole patterns that connect multilayered wirings via an insulating layer, and the like have become important. In particular, in recent years, it has become necessary to form fine patterns arranged densely at a pitch corresponding to the wavelength in the wiring pattern and contact pattern.

  On the other hand, the resist composition for forming a fine pattern is suitable for a short wavelength exposure light source represented by KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), etc., and has sensitivity, resolution, etc. It is required to be excellent. As such a resist composition, a chemically amplified photoresist composition containing an acid-dissociable group-containing component and an acid generator that generates an acid upon irradiation with radiation is generally used (Japanese Patent Application Laid-Open (JP-A)). (See Sho 59-45439).

  However, when forming a dense contact hole pattern densely arranged with a pitch corresponding to a wavelength using a conventional photoresist composition, a hole bridge that connects holes is likely to occur, and a desired pattern is formed. There is an inconvenience that it is difficult to obtain.

  In view of such a situation, it is desired to develop a photoresist composition that can suppress a hole bridge in forming a dense contact hole pattern and that can form a pattern with higher resolution.

JP 59-45439 A

  The present invention has been made based on the circumstances as described above, and its purpose is excellent in bridge resistance capable of suppressing the generation of hole bridges in the formation of dense contact hole patterns, and sufficiently satisfying the resolution. A photoresist composition is provided.

The invention made to solve the above problems is
[A] a polymer having a structural unit (I-1) containing a monocyclic lactone group and a structural unit (II) containing an acid dissociable group (hereinafter also referred to as “[A] polymer”),
[B] a polymer having a structural unit (I-2) containing a polycyclic lactone group and a structural unit (II) containing an acid dissociable group (hereinafter also referred to as “[B] polymer”), and [C ] Radiation sensitive acid generator (hereinafter also referred to as “[C] acid generator”)
Is a photoresist composition containing

  Since the photoresist composition of the present invention contains a [A] polymer containing a monocyclic lactone group and a [B] polymer containing a polycyclic lactone group, the developer is more liquid than the conventional photoresist composition. Since it has a high affinity for, it has excellent resolution and bridge resistance.

  The monocyclic lactone group is preferably a γ-butyrolactone group. When the monocyclic lactone group is a γ-butyrolactone group, the affinity of the photoresist composition with respect to the developer can be further improved. Therefore, the resolution is excellent, and even a small deprotection reaction can be applied to the developer. Since it is easy to dissolve, the exposure amount can be reduced, and unnecessary deprotection in the unexposed area can be suppressed, so that the bridge resistance is excellent.

（式（１）中、Ｒ^１は、水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。Ｒは、フッ素原子、水酸基又は１価の有機基である。ｎは０〜３の整数である。） The structural unit (I-1) is preferably a structural unit represented by the following formula (1).

(In Formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R is a fluorine atom, a hydroxyl group, or a monovalent organic group. N is an integer of 0-3. .)

  When the structural unit (I-1) has the above specific structure containing a γ-butyrolactone group, the affinity of the photoresist composition for the developer can be further improved, so that the resolution and the bridge resistance are further improved. .

  The polycyclic lactone group is preferably a norbornane lactone group. When the polycyclic lactone group is a norbornane lactone group, the affinity of the photoresist composition with respect to the developer can be further improved, so that the resolution and the bridge resistance are further improved.

（式（２）中、Ｒ^２は、水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。Ｒ’は、フッ素原子、水酸基又は１価の有機基である。ｍは、０〜６の整数である。） The structural unit (I-2) is preferably a structural unit represented by the following formula (2).

(In Formula (2), R ² is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ′ is a fluorine atom, a hydroxyl group, or a monovalent organic group. M is 0-6. Is an integer.)

  When the structural unit (I-2) has the specific structure containing a norbornane lactone group, the affinity of the photoresist composition for the developer can be further improved, and thus the resolution and the bridge resistance are further improved. .

（式（３）中、Ｒ^３は、水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。Ｒ^４〜Ｒ^６は、それぞれ独立して、炭素数１〜４のアルキル基又は炭素数４〜２０の脂環式基である。但し、Ｒ^４及びＲ^５は、互いに結合して、それらが結合している炭素原子と共に２価の脂環式基を形成していてもよい。また、上記アルキル基及び脂環式基が有する水素原子の一部又は全部は置換されていてもよい。） The structural unit (II) is preferably a structural unit represented by the following formula (3).

(In Formula (3), R ³ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ^{4 to} R ⁶ are each independently an alkyl group having 1 to 4 carbon atoms or a carbon number. It is an alicyclic group having 4 to 20. However, R ⁴ and R ⁵ may be bonded to each other to form a divalent alicyclic group together with the carbon atom to which they are bonded. A part or all of the hydrogen atoms of the alkyl group and alicyclic group may be substituted.)

  When the structural unit (II) containing the acid dissociable group in the [A] polymer and the [B] polymer has the specific structure, the photoresist composition can improve sensitivity.

  [A] The content of the structural unit (I-1) in the polymer is 10 mol% or more and 70 mol% or less, and the content of the structural unit (I-2) in the [B] polymer is 10 mol% or more. It is preferable that it is 70 mol% or less.

  By blending the [A] polymer and the [B] polymer each containing the structural unit (I-1) and the structural unit (I-2) in the above ranges, the developer composition with respect to the developer of the photoresist composition is blended. The reactivity can be further improved, and bridge resistance and resolution can be sufficiently satisfied.

  [A] The content of the structural unit (II) in the polymer is from 20 mol% to 80 mol%, and the content of the structural unit (II) in the [B] polymer is from 20 mol% to 80 mol%. It is preferable that

  By blending the [A] polymer and the [B] polymer each containing the structural unit (II) in the above range, the sensitivity of the photoresist composition is sufficiently satisfied, and bridge resistance and resolution are improved. Also excellent.

  [A] The content of the polymer is preferably 25 parts by mass or more and 400 parts by mass or less with respect to 100 parts by mass of the [B] polymer. By blending the [A] polymer and the [B] polymer in the above proportion, the reactivity of the photoresist composition with respect to the developer can be further improved, and the bridge resistance and resolution are further improved.

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

  Since the photoresist composition of the present invention has high reactivity with a developing solution, the formation of a hole pattern, particularly the formation of a dense contact hole pattern, can suppress the generation of a hole bridge and is excellent in resolution. Therefore, the said photoresist composition can form a fine pattern with high precision, and can be used suitably for the semiconductor device manufacture for which further refinement | miniaturization is anticipated from now on.

<Photoresist composition>
The photoresist composition of the present invention contains a [A] polymer, a [B] polymer, and a [C] acid generator. The photoresist composition has a moderate sensitivity and reactivity to the developer by blending the [A] polymer containing a monocyclic lactone group and the [B] polymer containing a polycyclic lactone group. Balanced and excellent in bridge resistance and resolution in hole pattern formation. Moreover, it is preferable that the said photoresist composition contains a [D] acid diffusion control agent and a [E] solvent. Furthermore, the said photoresist composition may contain the other arbitrary component, unless the effect of this invention is impaired. Hereinafter, each component will be described in detail.

<[A] polymer>
[A] The polymer is a polymer having a structural unit (I-1) containing a monocyclic lactone group and a structural unit (II) containing an acid dissociable group. The said photoresist composition can improve the reactivity with a developing solution by containing the [A] polymer containing a monocyclic lactone group and an acid dissociable group. Thereby, since the said photoresist composition can implement | achieve high developability with few deprotection reactions, it is thought that a hole bridge can be suppressed. Moreover, unless the effect of this invention is impaired, a [A] polymer can have another structural unit. In addition, the [A] polymer may have only 1 type of each structural unit, and may have 2 or more types. Hereinafter, each structural unit will be described.

[Structural unit (I-1)]
The structural unit (I-1) is a structural unit containing a monocyclic lactone group. Here, the lactone group refers to a cyclic group containing one ring (lactone ring) containing an —O—C (O) — structure. The lactone ring is counted as the first ring, and when it is only a lactone ring, it is called a monocyclic lactone group, and when it has another ring structure, it is called a polycyclic lactone group regardless of the structure.

  Examples of the monocyclic lactone group include a β-lactone group, a γ-butyrolactone group, and a δ-valerolactone group. Among these, from the viewpoint of improving the reactivity with the developer, a γ-butyrolactone group is preferable.

  As the structural unit (I-1), a structural unit represented by the above formula (1) is preferable. [A] When the structural unit (I-1) of the polymer is a structural unit represented by the above formula (1), the photoresist composition can further improve the reactivity with the developer. .

In said formula (1), R < ¹ > is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R is a fluorine atom, a hydroxyl group or a monovalent organic group. n is an integer of 0-3.

  Examples of the monovalent organic group represented by R include an alkoxy group having 1 to 10 carbon atoms and a cyano group.

  As a C1-C10 alkoxy group represented by said R, a methoxy group, an ethoxy group, a propoxy group, a butoxy group etc. are mentioned, for example. Of these, a methoxy group and an ethoxy group are preferable, and a methoxy group is more preferable.

  As said R, a hydroxyl group, a methoxy group, and a cyano group are preferable.

  n is preferably 0 to 2, more preferably 0 or 1, and still more preferably 0.

  Examples of the structural unit (I-1) include a structural unit represented by the following formula. Of these, β-γ-butyrolactone (βGBL) is more preferred.

In the above formula, ^{R 1} is as defined in the above formula (1).

  [A] The content of the structural unit (I-1) in the polymer is preferably 10% by mole to 70% by mole, and preferably 15% by mole to 65% by mole with respect to all the structural units constituting the [A] polymer. % Is more preferable, and 20 mol% to 60 mol% is more preferable. By making the content rate of a structural unit (I-1) into the said range, the reactivity with the developing solution of the said photoresist composition can be improved.

  As a monomer which gives structural unit (I-1), the monomer etc. which are represented by a following formula are mentioned, for example.

[Structural unit (II)]
The structural unit (II) is a structural unit containing an acid dissociable group. The structural unit (II) is preferably a structural unit represented by the above formula (3). [A] Since the structural unit (II) of the polymer is a structural unit having an acid-dissociable group having the above specific structure, the photoresist composition has an appropriate sensitivity, and thus forms a pattern with excellent lithography characteristics. In addition, it is possible to suppress hole bridges that are considered to occur due to excessive deprotection reaction.

In the formula (3), R ³ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ^{4 to} R ⁶ are each independently an alkyl group having 1 to 4 carbon atoms or an alicyclic group having 4 to 20 carbon atoms. However, R ⁴ and R ⁵ may be bonded to each other to form a divalent alicyclic group together with the carbon atom to which they are bonded. Moreover, one part or all part of the hydrogen atom which the said alkyl group and alicyclic group have may be substituted.

Examples of the alkyl group having 1 to 4 carbon atoms represented by R ^{4 to} R ⁶ include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, and a tert-butyl group. , 2-methylpropyl group, 1-methylpropyl group and the like.

The alicyclic group having 4 to 20 carbon atoms represented by the above R ^{4 to} R ⁶ , and R ⁴ and R ⁵ may be bonded to each other and may be formed together with the carbon atom to which each is bonded. Examples of the group include a polycyclic alicyclic group having a bridged skeleton such as an adamantane skeleton and a norbornane skeleton; and a monocyclic alicyclic group having a cycloalkane skeleton such as cyclopentane and cyclohexane. These groups may be substituted with one or more of, for example, a hydroxyl group, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms.

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

In the above formulas, ^{R 3} is as defined in the above formula (3). R ⁷ is an alkyl group having 1 to 4 carbon atoms. m1 and m2 are integers of 1-6.

  Of these, structural units represented by the following formulas (3-1) to (3-23) are preferable.

In the above formulas (3-1) to (3-23), R ³ has the same meaning as the above formula (3).

  Among these, the structural units represented by the above formulas (3-2) to (3-6) and (3-22) to (3-23) are more preferable.

  [A] In the polymer, the content of the structural unit (II) is preferably 20% by mole to 80% by mole, and 25% by mole to 75% by mole with respect to all the structural units constituting the [A] polymer. Is more preferable, and 30 mol% to 70 mol% is more preferable. By making the content rate of structural unit (II) into the said range, the lithography characteristic of the resist pattern obtained improves more.

Examples of the monomer that gives the structural unit (II) include (meth) acrylic acid-bicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-bicyclo [2.2.2] octa. 2-yl ester, (meth) acrylic acid-tricyclo [5.2.1.0 ^2,6 ] dec-7-yl ester, (meth) acrylic acid-tricyclo [3.3.1.1 ^3,7 ] Deca-1-yl ester, (meth) acrylic acid-tricyclo [3.3.1.1 ^3,7 ] dec-2-yl ester, a compound represented by the following formula, and the like.

[Other structural units]
[A] The polymer includes a structural unit containing a polar group (hereinafter, also referred to as “structural unit (III)”), a cyclic carbonate structure as another structural unit different from the structural units (I-1) and (II). (Hereinafter also referred to as “structural unit (IV)”).

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

In the above formula, R ⁸ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

  [A] The content of the structural unit (III) in the polymer is preferably 0 mol% to 40 mol%, more preferably 10 mol% to 25 mol%, based on all structural units constituting the [A] polymer. preferable.

  As a monomer which gives structural unit (III), the compound etc. which are represented by a following formula are mentioned, for example.

[Structural unit (IV)]
[A] The polymer preferably further has a structural unit (IV) containing a cyclic carbonate structure. By having the structural unit (IV), the adhesion of the resist film to the substrate can be improved.

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

In the above formula, R ⁹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ¹⁰ is a hydrogen atom or a methyl group.

  [A] In the polymer, the content of the structural unit (IV) is preferably 0 mol% to 50 mol%, preferably 10 mol% to 30 mol%, based on all structural units constituting the [A] polymer. Is more preferable. By making the content rate of structural unit (IV) into the said range, the adhesiveness of a resist and a board | substrate can be improved. On the other hand, when it exceeds 50 mol%, a good pattern may not be obtained.

  Examples of the monomer that gives the structural unit (IV) include monomers described in International Publication No. 2007/116664 pamphlet, compounds represented by the following formula, and the like.

<[A] Polymer Synthesis Method>
[A] The polymer can be synthesized, for example, by mixing a monomer that gives each predetermined structural unit together with a radical polymerization initiator in an appropriate solvent. For example, a method of dropping a solution containing a monomer and a radical initiator into a reaction solvent or a solution containing the monomer to cause a polymerization reaction, a solution containing the monomer, and a solution containing the radical initiator Separately, a method of dropping a reaction solvent or a monomer-containing solution into a polymerization reaction, a plurality of types of solutions containing each monomer, and a solution containing a radical initiator, It is preferable to synthesize by a method such as a method of dropping it into a reaction solvent or a solution containing a monomer to cause a polymerization reaction.

  What is necessary is just to determine the reaction temperature in these methods suitably with initiator seed | species. Usually, it is 30 degreeC-180 degreeC, 40 degreeC-160 degreeC is preferable, and 50 degreeC-140 degreeC is more preferable. 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), 2,2'-azobis (2-methylpropionitrile) and the like. Two or more of these initiators may be mixed and used.

  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 polymer obtained by the polymerization reaction is preferably recovered by a reprecipitation method. That is, after completion of the polymerization reaction, the polymer 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 polymer 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. In addition, the one where the said low molecular component is as few as possible is preferable.

  [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 500,000 or less, more preferably 2,000 or more and 400,000 or less. preferable. 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 [A] 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, more preferably from 1 to 2. preferable. By setting Mw / Mn in such a range, the photoresist film has excellent resolution performance.

  In addition, Mw and Mn of this specification use a GPC column (Tosoh, G2000HXL, G3000HXL, G4000HXL), flow rate of 1.0 ml / min, elution solvent tetrahydrofuran, column temperature of 40 ° C. It is a value measured by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard under conditions.

  The content of the [A] polymer in the photoresist composition is preferably 25 to 400 parts by mass, more preferably 50 to 300 parts by mass with respect to 100 parts by mass of the [B] polymer. 50 parts by mass or more and 200 parts by mass or less is more preferable, and 50 parts by mass or more and 100 parts by mass or less is particularly preferable. By making the content rate of the [A] polymer in the said photoresist composition into the said specific mass ratio with respect to a [B] polymer, the said photoresist composition improves the reactivity with respect to a developing solution. It is excellent in bridge resistance and resolution.

<[B] polymer>
[B] The polymer is a polymer having a structural unit (I-2) containing a polycyclic lactone group and a structural unit (II) containing an acid dissociable group. The said photoresist composition can improve the reactivity with a developing solution by containing the [B] polymer containing a polycyclic lactone group and an acid dissociable group with the [A] polymer mentioned above. . Thereby, since the said photoresist composition can implement | achieve high developability, it is excellent also in suppressing a hole bridge and being excellent in resolution. Furthermore, the polymer [B] can have other structural units as long as the effects of the present invention are not impaired. In addition, the [B] polymer may have each structural unit individually by 1 type, and may have 2 or more types. Hereinafter, each structural unit will be described.

[Structural unit (I-2)]
The structural unit (I-2) is a structural unit containing a polycyclic lactone group. Examples of the structural unit (I-2) include a structural unit represented by the following formula.

In the above formula, R ¹¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ¹² is a hydrogen atom or a methoxy group. R ¹³ is a hydrogen atom, a methoxy group, a cyano group or a hydroxyl group. Z ¹ is a single bond, a methylene group or an ester group. Z ² is a methylene group or an oxygen atom. a is 0 or 1.

  Of these, the structural unit (I-2) is preferably a structural unit represented by the above formula (2). [B] When the structural unit (I-2) of the polymer is a structural unit represented by the above formula (2), the photoresist composition can further improve the reactivity with the developer. .

In the formula (2), R ² is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ′ is a fluorine atom, a hydroxyl group or a monovalent organic group. m is an integer of 0-6.

  The description of the monovalent organic group represented by R in the above formula (1) can be applied to the monovalent organic group represented by R ′.

  R ′ is preferably a hydroxyl group, a methoxy group, or a cyano group.

  As said m, 0-3 are preferable, 0-2 are more preferable, and 0 or 1 is further more preferable.

  [B] The content of the structural unit (I-2) in the polymer is preferably 10% by mole to 70% by mole, and preferably 15% by mole to 65% by mole relative to all the structural units constituting the [B] polymer. % Is more preferable, and 20 mol% to 60 mol% is more preferable. By making the content rate of a structural unit (I-2) into the said range, the reactivity with the developing solution of the said photoresist composition can be improved.

  As a monomer which gives structural unit (I-2), the monomer etc. which are represented by a following formula are mentioned, for example.

In the above formula, R ¹² is a hydrogen atom or a methoxy group. R ¹³ is a hydrogen atom, a methoxy group, a cyano group or a hydroxyl group. Z ¹ is a single bond, a methylene group, an ester group or a group formed by combining these groups. Z ² is a methylene group or an oxygen atom. a is 0 or 1. Some or all of the hydrogen atoms of the polycyclic lactone group may be substituted.

[Structural unit (II)]
The structural unit (II) is a structural unit containing an acid dissociable group. The structural unit (II) is preferably a structural unit represented by the above formula (3). [B] Since the structural unit (II) of the polymer is a structural unit having an acid-dissociable group having the above specific structure, the photoresist composition has appropriate sensitivity and is generated by excessive deprotection reaction. Then, it is possible to suppress the considered hall bridge. In addition, about structural unit (II), the description in structural unit (II) which a [A] polymer has is applicable.

  [B] In the polymer, the content of the structural unit (II) is preferably 20% by mole to 80% by mole, more preferably 25% by mole to 75% by mole, with respect to all the structural units constituting the [B] polymer. Is more preferable, and 30 mol% to 70 mol% is more preferable. By making the content rate of structural unit (II) into the said range, the lithography characteristic of the resist pattern obtained improves more.

[Other structural units]
[B] The polymer further has a structural unit (III) containing a polar group, a structural unit (IV) containing a cyclic carbonate group, etc. as other structural units other than the structural units (I-2) and (II). May be. In addition, about structural unit (III) and structural unit (IV), description of structural unit (III) and (IV) in a [A] polymer is applicable.

  [B] The content of the structural unit (III) in the polymer is preferably 0 mol% to 40 mol%, more preferably 10 mol% to 25 mol%, based on all structural units constituting the [B] polymer. preferable. By making the content rate of structural unit (III) into the said range, the pattern excellent in a lithography characteristic can be formed.

  [B] In the polymer, the content of the structural unit (IV) is preferably 0 mol% to 50 mol%, and preferably 10 mol% to 30 mol%, based on all the structural units constituting the [B] polymer. Is more preferable. By making the content rate of structural unit (IV) into the said range, the adhesiveness of a resist and a board | substrate can be improved. On the other hand, when it exceeds 50 mol%, a good pattern may not be obtained.

<[B] Polymer Synthesis Method>
The above [B] polymer can be synthesized, for example, by mixing a monomer that gives each predetermined structural unit together with a radical polymerization initiator in an appropriate solvent.

  Examples of the solvent and radical polymerization initiator used in the polymerization include the same solvents and radical polymerization initiators as those mentioned in the method for synthesizing [A] polymer.

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

  In the photoresist composition, the content of the structural unit (I-1) in the [A] polymer is 10 mol% or more and 70 mol% or less, and the structural unit (I-2) in the [B] polymer. ) Is preferably 10 mol% or more and 70 mol% or less. By blending the [A] polymer having the structural unit (I-1) and the [B] polymer having the structural unit (I-2) at the above content, the photoresist composition is The reactivity is improved and the bridge resistance and resolution are excellent.

<[C] acid generator>
[C] The acid generator is a compound that generates an acid by light that has passed through a mask in an exposure process, which is one process of forming a resist pattern. As the form of inclusion of the [C] acid generator in the photoresist composition, even in an embodiment of a compound as described later (hereinafter, this embodiment is also referred to as “[C] acid generator”), It may be a built-in embodiment or both of these embodiments.

  [C] Examples of the acid generator include onium salt compounds, sulfonimide compounds, halogen-containing compounds, diazoketone compounds, and the like. Of these [C] acid generators, onium salt compounds are preferred.

  Examples of the onium salt compound include sulfonium salts (including tetrahydrothiophenium salts), iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, and the like. Of these, sulfonium salts are preferred.

  Examples of the sulfonium salt include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, triphenylsulfonium 2-bicyclo [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- -Yl-1,1,2,2-tetrafluoroethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium par Fluoro-n-octanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylphosphonium 1,1, Examples include 2,2-tetrafluoro-6- (1-adamantanecarbonyloxy) -hexane-1-sulfonate, a compound represented by the following formula, and the like. Of these, compounds represented by the following formula are preferred.

  These [C] acid generators may be used alone or in combination of two or more. [C] The amount used when the acid generator is an “agent” is [A] in the photoresist composition from the viewpoint of ensuring the sensitivity and lithography performance of the resist film formed from the photoresist composition. When the sum total of the mass of a polymer and a [B] polymer is 100 mass parts, 1 mass part or more and 25 mass parts or less are preferable, and 5 mass parts or more and 20 mass parts or less are more preferable.

<[D] Acid diffusion controller>
The photoresist composition preferably further contains a [D] acid diffusion controller. [D] The acid diffusion controller has an action of controlling the diffusion phenomenon in the resist film of the acid generated from the [C] acid generator by exposure and suppressing an undesirable chemical reaction in the unexposed area. Therefore, in addition to the [A] polymer, [B] polymer and [C] acid generator, the photoresist composition can further suppress acid diffusion by containing a [D] acid diffusion controller, Lithographic properties of the resulting resist pattern can be improved.

  [D] As the acid diffusion controller, for example, a nitrogen-containing compound having an Nt-alkoxycarbonyl group is preferably used. Specifically, Nt-butoxycarbonyldi-n-octylamine, Nt-amyloxycarbonyldi-n-octylamine, Nt-butoxycarbonyldi-n-nonylamine, Nt-amyloxy Carbonyl di-n-nonylamine, Nt-butoxycarbonyldi-n-decylamine, Nt-amyloxycarbonyldi-n-decylamine, Nt-butoxycarbonyldicyclohexylamine, Nt-amyloxycarbonyldicyclohexylamine Nt-butoxycarbonyl-1-adamantylamine, Nt-amyloxycarbonyl-1-adamantylamine, Nt-butoxycarbonyl-2-adamantylamine, Nt-amyloxycarbonyl-2-adamantylamine Nt-butoxycarbonyl-N-methyl-1 Adamantylamine, Nt-amyloxycarbonyl-N-methyl-1-adamantylamine, (S)-(-)-1- (t-butoxycarbonyl) -2-pyrrolidinemethanol, (S)-(-)- 1- (t-amyloxycarbonyl) -2-pyrrolidinemethanol, (R)-(+)-1- (t-butoxycarbonyl) -2-pyrrolidinemethanol, (R)-(+)-1- (t- Amyloxycarbonyl) -2-pyrrolidinemethanol, Nt-butoxycarbonyl-4-hydroxypiperidine, Nt-amyloxycarbonyl-4-hydroxypiperidine, Nt-butoxycarbonylpyrrolidine, Nt-amyloxycarbonyl Pyrrolidine, N, N′-di-t-butoxycarbonylpiperazine, N, N′-di-t-amyloxycarbonylpipe Gin, N, N-di-t-butoxycarbonyl-1-adamantylamine, N, N-di-t-amyloxycarbonyl-1-adamantylamine, Nt-butoxycarbonyl-4,4′-diaminodiphenylmethane, Nt-amyloxycarbonyl-4,4′-diaminodiphenylmethane, N, N′-di-t-butoxycarbonylhexamethylenediamine, N, N′-di-t-amyloxycarbonylhexamethylenediamine, N, N , N ′, N′-tetra-t-butoxycarbonylhexamethylenediamine, N, N, N ′, N′-tetra-t-amyloxycarbonylhexamethylenediamine, N, N′-di-t-butoxycarbonyl- 1,7-diaminoheptane, N, N′-di-t-amyloxycarbonyl-1,7-diaminoheptane, N, N '-Di-t-butoxycarbonyl-1,8-diaminooctane, N, N'-di-t-amyloxycarbonyl-1,8-diaminooctane, N, N'-di-t-butoxycarbonyl-1, 9-diaminononane, N, N′-di-t-amyloxycarbonyl-1,9-diaminononane, N, N′-di-t-butoxycarbonyl-1,10-diaminodecane, N, N′-di-t -Amyloxycarbonyl-1,10-diaminodecane, N, N'-di-t-butoxycarbonyl-1,12-diaminododecane, N, N'-di-t-amyloxycarbonyl-1,12-diaminododecane N, N′-di-t-butoxycarbonyl-4,4′-diaminodiphenylmethane, N, N′-di-t-amyloxycarbonyl-4,4′-diaminodiphenylmethane, N t-butoxycarbonylbenzimidazole, Nt-butoxycarbonylbenzimidazole, Nt-amyloxycarbonyl-2-methylbenzimidazole, Nt-butoxycarbonyl-2-phenylbenzimidazole, Nt-amyloxycarbonyl -2-phenylbenzimidazole, N- (n-undecylcarbonyloxyethyl) morpholine and the like.

  [D] In addition to the above compounds, for example, nitrogen-containing compounds such as tertiary amine compounds, quaternary ammonium hydroxide compounds, and other nitrogen-containing heterocyclic compounds are used as the acid diffusion controller.

Examples of tertiary amine compounds include triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine. , Tri (cyclo) alkylamines such as cyclohexyldimethylamine, dicyclohexylmethylamine, and tricyclohexylamine;
Fragrances such as aniline, N-methylaniline, N, N-dimethylaniline, 2-methylaniline, 3-methylaniline, 4-methylaniline, 4-nitroaniline, 2,6-dimethylaniline, 2,6-diisopropylaniline Group amines;
Alkanolamines such as triethanolamine and N, N-di (hydroxyethyl) aniline;
N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, 1,3-bis [1- (4-aminophenyl) -1- Methylethyl] benzenetetramethylenediamine, bis (2-dimethylaminoethyl) ether, bis (2-diethylaminoethyl) ether and the like.

  Examples of the quaternary ammonium hydroxide compound include tetra-n-propylammonium hydroxide and tetra-n-butylammonium hydroxide.

  In the photoresist composition, the [D] acid diffusion controller may be used alone or in combination of two or more. The amount of the acid diffusion control agent used is preferably 10 parts by mass or less, preferably 0.1 parts by mass or more and 5 parts by mass or less, with respect to 100 parts by mass in total of the amounts used of the [A] polymer and [B] polymer. Is more preferable. When the amount used exceeds 10 parts by mass, the sensitivity as a resist tends to decrease.

<[E] solvent>
The photoresist composition usually contains an [E] solvent. [E] Examples of the solvent include alcohol solvents, ketone solvents, amide solvents, ether solvents, ester solvents, and mixed solvents thereof. Two or more of these solvents may be used in combination.

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 ester solvents include diethyl carbonate, propylene carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec-butyl acetate, and n-acetate. -Pentyl, 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, methyl acetoacetate, ethyl acetoacetate , Ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-butyl acetate Ether ether, propylene glycol monomethyl ether, 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, glycol diacetate, methoxytriacetate Glycol, 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, Examples thereof include dimethyl phthalate and diethyl phthalate.

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, γ-butyrolactone, and cyclohexanone are preferred.

<Other optional components>
The said photoresist composition can contain other arbitrary components, such as a fluorine atom containing polymer, an alicyclic skeleton compound, surfactant, and a sensitizer, in the range which does not impair the effect of this invention. Hereinafter, these optional components will be described in detail. Such other optional components can be used alone or in admixture of two or more. Moreover, the compounding quantity of another arbitrary component can be suitably determined according to the objective.

[Fluorine atom-containing polymer]
The photoresist composition may further contain a polymer having a higher fluorine atom content than the [A] polymer and the [B] polymer. When the photoresist composition further contains a fluorine atom-containing polymer, when the resist film is formed, the distribution is near the resist film surface due to the oil-repellent characteristics of the fluorine atom-containing polymer in the film. Since there is a tendency to be unevenly distributed, it is possible to prevent the acid generator, the acid diffusion controller, and the like from being eluted into the immersion medium during the immersion exposure. Further, due to the water-repellent characteristics of this fluorine atom-containing polymer, the advancing contact angle between the resist film and the immersion medium can be controlled within a desired range, and the occurrence of bubble defects can be suppressed. Furthermore, the receding contact angle between the resist film and the immersion medium is increased, and high-speed scanning exposure is possible without leaving water droplets. Thus, when the said photoresist composition contains a fluorine atom containing polymer, the resist coating film suitable for an immersion exposure method can be formed.

  Although it will not specifically limit as long as it has a fluorine atom as said fluorine-containing polymer, It is essential that a fluorine atom content rate (mass%) is higher than a [A] polymer and a [B] polymer. [A] When the fluorine atom content is higher than that of the polymer, the degree of uneven distribution described above is further increased, and the properties such as water repellency and elution suppression of the resulting resist film are improved.

  The fluorine atom-containing polymer in the present invention is formed by polymerizing one or more monomers containing a fluorine atom in the structure.

  Examples of the structural unit possessed by the fluorine atom-containing polymer include structural units represented by the following formula (hereinafter also referred to as “structural unit (V)”).

In the above formula, R ¹⁴ is hydrogen, a methyl group or a trifluoromethyl group. Y is a linking group. R ¹⁵ is a linear or branched alkyl group having 1 to 6 carbon atoms containing at least one fluorine atom, or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof. .

  Examples of the linking group represented by Y include a single bond, an oxygen atom, a sulfur atom, a carbonyloxy group, an oxycarbonyl group, an amide group, a sulfonylamide group, and a urethane group.

  In addition to the structural unit (V), the fluorine atom-containing polymer includes, for example, a structural unit having an acid dissociable group, a structural unit containing a lactone group, a structural unit containing a polar group, in order to control the dissolution rate in a developer, In order to suppress light scattering due to reflection from the substrate, one or more “other structural units” such as a structural unit derived from an aromatic compound can be contained.

  The Mw of the fluorine atom-containing polymer is preferably 1,000 to 50,000, more preferably 1,000 to 30,000, and still more preferably 1,000 to 10,000. When the Mw of the fluorine atom-containing polymer is less than 1,000, a sufficient advancing contact angle cannot be obtained. On the other hand, when Mw exceeds 50,000, the developability of the resist tends to decrease. The ratio (Mw / Mn) between Mw and Mn of the fluorine atom-containing polymer is usually 1 to 3, preferably 1 to 2.

  As a content rate of the fluorine atom containing polymer in the said photoresist composition, 0-50 mass parts is preferable with respect to a total of 100 mass parts of the mass of a [A] polymer and a [B] polymer, and 0-20. Mass parts are more preferable, 0.5 to 10 parts by mass are further preferable, and 1 to 8 parts by mass are particularly preferable. By making the content rate of the said fluorine atom containing polymer in the said photoresist composition into the said range, the water repellency and elution suppression property of the resist film surface obtained can be improved more.

[Surfactant]
Surfactants are components that 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 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, manufactured by Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (above, manufactured by Tochem Products), MegaFac F171, F173 (above, manufactured by Dainippon Ink & Chemicals), Fluorad FC430, FC431 ( As above, manufactured by Sumitomo 3M, Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, manufactured by Asahi Glass) ) And the like.

[Sensitizer]
The sensitizer absorbs radiation energy and transmits the energy to the [C] acid generator, thereby increasing the amount of acid generated. It has the effect of improving the “sensitivity”. Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines and the like.

<Method for preparing photoresist composition>
The photoresist composition includes, for example, [A] polymer, [B] polymer, [C] acid generator, [D] acid diffusion controller and other optional components in a predetermined ratio in [E] solvent. It can be prepared by mixing. The photoresist composition is usually dissolved in an [E] solvent so that the total solid content concentration is 1% by mass to 30% by mass, preferably 1.5% by mass to 25% by mass. It is prepared by filtering with a filter of about 0.2 μm.

<Method for forming resist pattern>
Using the photoresist composition of the present invention, for example, a resist pattern can be formed by the following steps.
(1) A step of forming a resist film on a substrate using the photoresist composition (hereinafter also referred to as “step (1)”),
(2) a step of exposing the resist film (hereinafter also referred to as “step (2)”); and (3) a step of developing the exposed resist film (hereinafter also referred to as “step (3)”).
Have By using the photoresist composition in forming a hole pattern, particularly a dense contact hole pattern, a resist pattern having excellent hole bridge resistance and resolution can be formed. Therefore, a fine pattern can be formed from the photoresist composition with high accuracy and stability, and can be suitably used for manufacturing semiconductor devices, which are expected to be further miniaturized in the future. Hereinafter, each process is explained in full detail.

[Step (1)]
In this step, a photoresist composition or a solution of the photoresist composition obtained by dissolving the photoresist composition in a solvent is applied to a silicon wafer, silicon dioxide, reflection, or the like by a coating means such as spin coating, cast coating, or roll coating. The solvent in the coating film is volatilized by applying it to a predetermined film thickness on a substrate such as a wafer coated with a prevention film, and in some cases, pre-baking (PB) usually at a temperature of about 70 ° C to 160 ° C. To form a resist film.

[Step (2)]
In this step, the resist film formed in the step (1) is exposed by irradiation with radiation (in some cases through an immersion medium such as water). At this time, radiation is irradiated through a mask having a target pattern such as a contact hole pattern or a line and space pattern. Since the photoresist composition has high reactivity with a developer and is excellent in bridge resistance and resolution, it is preferably used for forming a dense elliptic contact hole pattern among contact hole patterns. The radiation used for the exposure is appropriately selected from visible light, ultraviolet light, far ultraviolet light, X-rays, charged particle beams, EUV, etc. according to the line width of the target pattern. Among these, far ultraviolet rays represented by ArF excimer laser (wavelength 193 nm) and KrF excimer laser (wavelength 248 nm) are preferable, and light sources capable of forming finer patterns such as EUV (extreme ultraviolet ray, wavelength 13.5 nm) are preferred. Even if it exists, it can be used conveniently. Subsequently, it is preferable to perform post-exposure baking (PEB). By this PEB, it is possible to smoothly proceed with elimination of the acid dissociable groups of the [A] polymer and the [B] polymer. The heating condition of PEB can be appropriately selected depending on the composition of the photoresist composition, but is usually about 50 ° C to 180 ° C.

[Step (3)]
In this step, a resist pattern is formed by developing the exposed resist film with a developer. After development, it is common to wash with water and dry. As the developer, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyl Dimethylamine, triethanolamine, tetramethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo- [4.3.0] An aqueous alkaline solution in which at least one alkaline compound such as -5-nonene is dissolved is preferable.

  In the case of performing immersion exposure, before the step (2), in order to protect the direct contact between the immersion liquid and the resist film, an immersion liquid insoluble immersion protective film is formed on the resist film. It may be provided. As the protective film for immersion, a solvent-peeling protective film that peels off with a solvent before the step (3) (see, for example, JP-A-2006-227632), a developer that peels off simultaneously with the development in the step (3) Any of peelable protective films (for example, see WO2005-069096, WO2006-035790, etc.) may be used.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The measurement and evaluation of each physical property value in Examples and Comparative Examples were performed by the following methods.

[Molecular weight (Mw, Mn) measurement method]
The molecular weight (Mw, Mn) of each polymer was measured using a Tosoh GPC column (2 G2000HXL, 1 G3000HXL, 1 G4000HXL), a flow rate of 1.0 mL / min, an elution solvent tetrahydrofuran, and a column temperature of 40 ° C. The measurement was performed by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard. Further, the dispersity (Mw / Mn) was calculated from the measurement results of each molecular weight (Mw, Mn).

[ ¹³ C-NMR analysis]
¹³ C-NMR analysis was measured using a nuclear magnetic resonance apparatus (JNM-ECX400, manufactured by JEOL Ltd.).

[Measurement of monomer-derived low molecular weight components]
Measured by high-performance liquid chromatography (HPLC) using an Intersil ODS-25 μm column (4.6 mmφ × 250 mm) manufactured by GL Sciences under the flow rate of 1.0 mL / min and elution solvent acrylonitrile / 0.1% phosphoric acid aqueous solution. did.

<Synthesis of [A] polymer and [B] polymer>
The structures of the monomers used for the synthesis of the [A] polymer and the [B] polymer are shown below.

[Synthesis Example 1]
51.29 g (60 mol%) of the above compound (M-13) giving the structural unit (I-1) and 19.72 g (20 mol%) of the above compound (M-1) giving the structural unit (II) and the compound (M-2) 28.28 g (20 mol%) was dissolved in 200 g of 2-butanone, and AIBN 4.13 g (5 mol%) was added to prepare a monomer solution. A 1,000 mL three-necked flask containing 100 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 2,000 g of methanol, and the precipitated white powder was filtered off. The filtered white powder was washed twice with 300 g of methanol, filtered and dried at 50 ° C. for 17 hours to obtain a white powdery polymer (A-1) (67 g, yield 67%). . Mw of the obtained polymer (A-1) was 6,700, Mw / Mn was 1.51, and the residual ratio of the low molecular weight component was 1%. As a result of ¹³ C-NMR analysis, the content of the structural unit derived from the compound (M-13): the structural unit derived from the compound (M-1): the structural unit derived from the compound (M-2) was 66:17. : 17 (mol%).

[Synthesis Examples 2 to 8]
Each polymer was synthesized in the same manner as in Synthesis Example 1 except that a predetermined amount of each monomer listed in Table 1 was blended. In addition, Table 2 shows the Mw, Mw / Mn of each polymer obtained, and the content of the structural unit derived from each monomer in each polymer. In addition, “-” in the table indicates that the component was not used.

<Preparation of photoresist composition>
The [C] acid generator, [D] acid diffusion controller and [E] solvent used in the preparation of the photoresist compositions of the examples and comparative examples are as follows.

<[C] acid generator>
Compound represented by the following formula

<[D] Acid diffusion controller>
Compound represented by the following formula

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

[Example 1]
[A] 50 parts by mass of copolymer (A-1) as a polymer, [B] 50 parts by mass of copolymer (B-1) as a polymer, [C] (C-1 as an acid generator 14.6 parts by mass, [D] 2.0 parts by mass of (D-1) acid diffusion controller, and (E-1) 2,336 parts by mass of (E-1) solvent and (E-3) 30 parts by mass were mixed and each component was mixed to obtain a uniform solution. Then, the photoresist composition was prepared by filtering using a 0.20 micrometer membrane filter.

[Examples 2 to 4 and Comparative Examples 1 to 2]
Each photoresist composition was prepared in the same manner as in Example 1 except that the components in the types and amounts shown in Table 3 were used.

<Evaluation>
About each said photoresist composition, the dense ellipse contact hole pattern was formed as follows, and various physical properties were evaluated. The results are shown in Table 4.

<Formation of dense elliptical contact hole pattern>
On a 12-inch silicon wafer on which a lower antireflection film (ARC66, manufactured by Nissan Chemical Industries) was formed, a resist film having a film thickness of 90 nm was formed from each photoresist composition, and PB was performed at 100 ° C. for 60 seconds. On this resist film, Lithius Pro-i (manufactured by Tokyo Electron) was used, and TCX041 (manufactured by JSR) was applied by spin coating, PB was performed on a hot plate at 90 ° C., and a top coat film having a film thickness of 90 nm Formed. Next, using an ArF excimer laser immersion exposure apparatus (NSR S610C, manufactured by NIKON), an elliptical contact having a minor axis of 46 nm Space 85 nm Pitch and a major axis of 138 nm Space 161 nm Pitch under the conditions of NA = 1.3, ratio = 0.800, Dipole. Exposure was through a hole mask pattern. After the exposure, each photoresist composition was subjected to PEB at the temperatures and times shown in Table 4. 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 (mJ / cm ² ) for forming the short axis of the elliptical contact hole exposed through the mask pattern of the elliptical contact hole having the short axis of 46 nm Space 85 nm Pitch and the long axis of 138 nm Space 161 nm Pitch is 30 nm is the optimum exposure amount (Eop). It was. For the measurement, a scanning electron microscope (CG4000, manufactured by Hitachi High-Technologies Corporation) was used.

[Bridge resistance]
In an elliptical contact hole pattern formed through an elliptical contact hole mask pattern having a minor axis of 46 nm Space 85 nm Pitch and a major axis of 138 nm Space 161 nm Pitch when exposed with radiation larger than Eop, adjacent contact hole patterns are not connected to each other. The short axis length (nm) was taken as the measured value (I). Using the measured value (I), the margin (%) was calculated according to the following formula to determine the bridge resistance. The greater the margin value, the better the bridge resistance. When the margin is 15% or more, the bridge resistance is “good”, and when it is less than 15%, the bridge resistance is determined to be “bad”.
Margin (%) = {measurement value (I) -30} / {measurement value (I)} × 100

[Resolution]
In the above Eop, the major axis length (nm) of an elliptical contact hole pattern formed through an elliptical contact hole mask pattern having a minor axis of 46 nm Space 85 nm Pitch and a major axis of 138 nm Space 161 nm Pitch was defined as a length measurement value (II). Using the measured value (II), the minor axis ratio was calculated by the following formula to obtain the resolution. This resolution was judged to be “good” when the minor axis ratio value was larger as 3.33 or higher, and “bad” when lower than 3.33.
Short / long axis ratio = {measurement value (II)} / 30

  As apparent from the results shown in Table 4, by using the photoresist composition, excellent bridge resistance and resolution can be realized in an elliptical dense contact hole pattern.

  Since the photoresist composition of the present invention has high reactivity with a developing solution, the formation of a hole pattern, particularly the formation of a dense contact hole pattern, can suppress the generation of a hole bridge and is excellent in resolution. Therefore, the said photoresist composition can form a fine pattern with high precision, and can be used suitably for the semiconductor device manufacture for which further refinement | miniaturization is anticipated from now on.

Claims (9)

[A] a polymer having a structural unit (I-1) containing a monocyclic lactone group and a structural unit (II) containing an acid dissociable group,
[B] A polymer having a structural unit (I-2) containing a polycyclic lactone group and a structural unit (II) containing an acid dissociable group, and [C] a photoresist composition containing a radiation-sensitive acid generator object.   The photoresist composition according to claim 1, wherein the monocyclic lactone group is a γ-butyrolactone group. The photoresist composition according to claim 1, wherein the structural unit (I-1) is represented by the following formula (1).

(In Formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R is a fluorine atom, a hydroxyl group, or a monovalent organic group. N is an integer of 0-3. .)   The photoresist composition according to claim 1, wherein the polycyclic lactone group is a norbornane lactone group. The photoresist composition according to any one of claims 1 to 4, wherein the structural unit (I-2) is represented by the following formula (2).

(In Formula (2), R ² is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ′ is a fluorine atom, a hydroxyl group, or a monovalent organic group. M is 0-6. Is an integer.) The photoresist composition according to any one of claims 1 to 5, wherein the structural unit (II) is represented by the following formula (3).

(In Formula (3), R ³ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ^{4 to} R ⁶ are each independently an alkyl group having 1 to 4 carbon atoms or a carbon number. It is an alicyclic group having 4 to 20. However, R ⁴ and R ⁵ may be bonded to each other to form a divalent alicyclic group together with the carbon atom to which they are bonded. A part or all of the hydrogen atoms of the alkyl group and alicyclic group may be substituted.)   [A] The content of the structural unit (I-1) in the polymer is 10 mol% or more and 70 mol% or less, and the content of the structural unit (I-2) in the [B] polymer is 10 mol% or more. The photoresist composition according to any one of claims 1 to 6, which is 70 mol% or less.   [A] The content of the structural unit (II) in the polymer is 20 mol% or more and 80 mol% or less, and the content of the structural unit (II) in the [B] polymer is 20 mol% or more and 80 mol% or less. The photoresist composition according to any one of claims 1 to 7, which is: The photoresist composition according to any one of claims 1 to 8, wherein the content of [A] polymer is 25 parts by mass or more and 400 parts by mass or less with respect to 100 parts by mass of [B] polymer. .