JP4536546B2 - Positive resist composition and resist pattern forming method using the same - Google Patents

Description

  The present invention relates to a positive resist composition and a resist pattern forming method using the same.

  In recent years, in the manufacture of semiconductor elements and liquid crystal display elements, miniaturization has rapidly progressed due to advances in lithography technology. As a technique for miniaturization, the wavelength of an exposure light source is generally shortened. Specifically, in the past, ultraviolet rays typified by g-line and i-line were used, but now KrF excimer laser (248 nm) is the center of mass production, and ArF excimer laser (193 nm) is introduced in mass production. Being started.

A resist for a light source such as a KrF excimer laser or an ArF excimer laser is required to have a high resolution capable of reproducing a pattern having a fine dimension and a high sensitivity to such a short wavelength light source. As one of the resists satisfying such conditions, a chemically amplified positive resist composition containing a base resin whose alkali solubility is increased by the action of an acid and an acid generator (hereinafter referred to as PAG) that generates an acid upon exposure. Things are known.
The reaction mechanism of the chemically amplified positive resist is that, when exposed, the PAG blended in the resist generates an acid, and the solubility of the base resin is changed by the acid. For example, by introducing a dissolution inhibiting group that is eliminated by an acid into the base resin of a chemically amplified positive resist, the dissolution inhibiting group is eliminated only in the exposed area, and the solubility in the developer is greatly increased. .
In general, by performing a heat treatment (post exposure baking, hereinafter abbreviated as PEB) after exposure, the elimination of the dissolution inhibiting group and the diffusion of the acid in the resist are promoted. Compared with the non-chemically amplified resist, the sensitivity can be very high.

For example, in a chemically amplified resist for KrF excimer laser, as its base resin component, polyhydroxystyrene having high transparency to KrF excimer laser (248 nm) and its hydroxyl group are protected with an acid dissociable, dissolution inhibiting group ( Hereinafter, those using a hydroxystyrene resin have been proposed (for example, Patent Document 1).
JP 2002-365804 A

Nowadays, design rules required in the manufacture of semiconductor elements are further narrowed, and a resolution capable of forming a finer resist pattern is required. In addition, the application of applying the resist composition has been expanded, and different characteristics are required depending on the application.
In order to meet such various demands, development of materials and the like constituting the resist composition has been energetically advanced, and further provision of various types of resist compositions is desired.

  The present invention has been made to solve the above-described problems, and is a chemically amplified positive resist composition using a material different from the conventional one, which can be applied to a KrF excimer laser, and the same. An object is to provide a resist pattern forming method.

（式中、Ｒ^１は水素原子またはメチル基である）
で表されるアルケニルフェノールから誘導される繰り返し単位、及び
（２）一般式（ＩＩ）：

（式中、Ｒ^２は水素原子またはメチル基であり、Ｒ^３は３級炭素原子で結合する脂環式炭化水素基からなる酸解離性の溶解抑制基である）
で表されるアクリレートから誘導される繰り返し単位を含むポリマー鎖であり；
コア部が、一般式（ＩＩＩ）：

（式中、Ｒ^４及びＲ^８は、それぞれ独立に、水素原子、またはメチル基を表し、Ｒ^５、Ｒ^６、Ｒ^９、及びＲ^１０は、それぞれ独立に、アルキル基を表し、Ｒ^７は、アルキレン基を表す。）
で表されるジアクリレートから誘導される繰り返し単位を含むスターポリマー（Ａ１）を含むことを特徴とするポジ型レジスト組成物である。
第２の態様は、（Ａ）酸の作用によりアルカリ可溶性が増大する樹脂成分、および（Ｂ）放射線の照射により酸を発生する酸発生剤成分を含有するポジ型レジスト組成物であって、
前記（Ａ）成分は、中心核としてのコア部、および中心核に連結するポリマー鎖としてのアーム部を含むスターポリマーであって、
アーム部が、
（１）一般式（Ｉ）：

（式中、Ｒ^１は前記と同じ意味である）
で表されるアルケニルフェノールから誘導される繰り返し単位と、
一般式（ＩＶ）：

（式中、Ｒ^１は水素原子またはメチル基である）
で表されるアルケニルフェニルから誘導される繰り返し単位、
及び
（２）一般式（ＩＩ）：

（式中、Ｒ²及びＲ³は前記と同じ意味である）
で表されるアクリレートから誘導される繰り返し単位を含むポリマー鎖であり；
コア部が、一般式（ＩＩＩ）：

（式中、Ｒ⁴〜Ｒ¹⁰は前記と同じ意味である）
で表されるジアクリレートから誘導される繰り返し単位を含むスターポリマー（Ａ２）を含むことを特徴とするポジ型レジスト組成物である。
第１の態様と第２の態様においては、一般式（ＩＩ）中、Ｒ^３が１−アルキルシクロアルキル基および２−アルキル−２−アダマンチル基から選ばれる１種以上であることが好ましい。 In order to achieve the above object, the present invention employs the following configuration.
The first aspect is a positive resist composition containing (A) a resin component whose alkali solubility is increased by the action of an acid, and (B) an acid generator component that generates an acid by irradiation with radiation,
The component (A) is a star polymer including a core part as a central core and an arm part as a polymer chain connected to the central core,
Arm part is
(1) General formula (I):

(Wherein R ¹ is a hydrogen atom or a methyl group)
A repeating unit derived from an alkenylphenol represented by: (2) General Formula (II):

(In the formula, R ² is a hydrogen atom or a methyl group, and R ³ is an acid dissociable, dissolution inhibiting group composed of an alicyclic hydrocarbon group bonded by a tertiary carbon atom)
A polymer chain comprising a repeating unit derived from an acrylate represented by:
The core portion has the general formula (III):

(Wherein R ⁴ and R ⁸ each independently represent a hydrogen atom or a methyl group, R ⁵ , R ⁶ , R ⁹ and R ¹⁰ each independently represent an alkyl group, and R ⁷ represents Represents an alkylene group.)
And a star polymer (A1) containing a repeating unit derived from a diacrylate represented by the formula:
The second aspect is a positive resist composition containing (A) a resin component whose alkali solubility is increased by the action of an acid, and (B) an acid generator component that generates an acid by irradiation with radiation,
The component (A) is a star polymer including a core part as a central core and an arm part as a polymer chain connected to the central core,
Arm part is
(1) General formula (I):

(Wherein R ¹ has the same meaning as described above)
A repeating unit derived from an alkenylphenol represented by:
Formula (IV):

(Wherein R ¹ is a hydrogen atom or a methyl group)
A repeating unit derived from alkenylphenyl represented by:
And (2) general formula (II):

(Wherein R ² and R ³ have the same meaning as described above)
A polymer chain comprising a repeating unit derived from an acrylate represented by:
The core portion has the general formula (III):

(Wherein R ^{4 to} R ¹⁰ have the same meaning as described above)
And a star polymer (A2) containing a repeating unit derived from a diacrylate represented by the formula:
In the first aspect and the second aspect, in general formula (II), R ³ is preferably at least one selected from a 1-alkylcycloalkyl group and a 2-alkyl-2-adamantyl group.

  In the third aspect, the positive resist composition of the present invention is coated on a support, pre-baked, selectively exposed, then subjected to PEB (post-exposure heating), alkali development, and a resist pattern. Is a resist pattern forming method characterized in that

  In the present invention, a chemically amplified positive resist composition using a material different from the conventional material that can be applied for a KrF excimer laser and a resist pattern forming method using the same can be provided.

Hereinafter, the present invention will be described in detail.
[Positive resist composition]
The positive resist composition of the present invention is a positive resist composition containing (A) a resin component whose alkali solubility is increased by the action of an acid, and (B) an acid generator component which generates an acid upon irradiation with radiation. At least one of the specific star polymer (A1) and star polymer (A2) as described above is used.

Here, the component (A) is a resin component having an acid dissociable, dissolution inhibiting group, and the dissolution inhibiting group is dissociated by the action of an acid generated from the component (B), thereby increasing alkali solubility. .
More specifically, when the acid generated from the component (B) by exposure acts on the component (A), the dissolution inhibiting group in the component (A) is dissociated, thereby changing the entire positive resist from alkali-insoluble to alkali-soluble. To do. Therefore, when a positive resist is exposed through a mask pattern in the formation of a resist pattern, or when PEB is performed in addition to exposure, the exposed portion turns alkali-soluble while the unexposed portion remains alkali-insoluble. Therefore, a positive resist pattern can be formed by alkali development.

(A) Component “first aspect”
In the first embodiment, the component (A) includes the star polymer (A1) (hereinafter sometimes referred to as the component (A1)).
The component (A1) is a star polymer including a core part as a central core and an arm part as a polymer chain linked to the central core,
The arm portion is (1) a repeating unit derived from an alkenylphenol represented by the general formula (I) [hereinafter sometimes referred to as a unit (a1)], and (2) represented by the general formula (II). A polymer chain containing a repeating unit derived from an acrylate to be prepared [hereinafter sometimes referred to as a unit (a2)];
The core part is a star polymer containing a repeating unit derived from the diacrylate represented by the general formula (III) [hereinafter sometimes referred to as a unit (c1)].

・ Arm part ・ ・ Unit (a1)
The unit (a1) is a repeating unit derived from the alkenylphenol derivative represented by the general formula (I).
In general formula (I), R ¹ is a hydrogen atom or a methyl group.
The repeating unit derived from the alkenylphenol derivative represented by the general formula (I) has the following general formula (Ia):

（式中、Ｒ^１は前記と同じ意味である）
で表される繰り返し単位である。

(Wherein R ¹ has the same meaning as described above)
It is a repeating unit represented by

The proportion of the unit (a1) in all repeating units constituting the component (A1) is 40 to 90 mol%, preferably 50 to 85 mol%, and more preferably 75 to 85 mol%. By setting it to the lower limit value or more, moderate solubility in the developer can be obtained. By setting the lower limit value or less, it is possible to balance with other repeating units.
In the arm portion of the star polymer, the ratio of each repeating unit can be arbitrarily selected by the ratio of the monomer used in the reaction. For example, the content of the repeating unit represented by the general formula (I) is It can adjust with 99-10 mol% in a part all repeating unit.

・ Unit (a2)
The unit (a2) is a repeating unit derived from the acrylate represented by the general formula (II).
In general formula (II), R ² represents a hydrogen atom or a methyl group.
R ³ is an alicyclic hydrocarbon group bonded through a tertiary carbon atom.

The alicyclic hydrocarbon group bonded with a tertiary carbon atom may be monocyclic or polycyclic.
Specific examples include a 1-alkylcycloalkyl group and a 2-alkyl-2-adamantyl group, and a 1-alkylcycloalkyl group and a 2-alkyl-2-adamantyl group are preferable. The chain alkyl group bonded to the cycloalkyl group and the chain alkyl group bonded to the adamantyl group may be either linear or branched, for example, a lower alkyl group having about 1 to 5 carbon atoms. And particularly preferably a methyl group or an ethyl group.

  Examples of the acrylate represented by the general formula (II) include compounds represented by the following formula.

The alicyclic hydrocarbon group bonded at the tertiary carbon atom is an acid dissociable, dissolution inhibiting group, and R3 is a KrF such as a 1-alkylcycloalkyl group, a 2-alkyl-2-adamantyl group or the like. The thing used for the base resin of the resist for excimer lasers, etc. can be applied. Furthermore, the repeating structural unit induced | guided | derived from acrylates other than said acrylate may be included.
For example, a structural unit containing an aliphatic polycyclic group and derived from a (meth) acrylic acid ester is preferable. Examples of the polycyclic group include a 1-adamantyl group.
In all the repeating units constituting the component (A1), the proportion of the unit (a2) is 5 to 50 mol%, preferably 10 to 45 mol%, and more preferably 10 to 20 mol%. By setting it to the lower limit value or more, the solubility contrast between the unexposed area and the exposed area can be controlled. By setting the lower limit value or less, it is possible to balance with other repeating units.

  The number average molecular weight Mn of the arm part is preferably 1,000 to 100,000, more preferably 1,500 to 500,000, still more preferably 2, as a polystyrene standard by gel permeation chromatography (GPC) method. 000 to 200,000, particularly preferably in the range of 2,500 to 100,000, and the ratio (Mw / Mn) of the mass average molecular weight (Mw) to the number average molecular weight (Mn) is 1.01 to 3.00. The range of 1.01 to 2.00, more preferably 1.01 to 1.50 is preferable.

・ Core part ・ ・ Unit (c1)
The unit (c1) is a repeating unit derived from the diacrylate represented by the general formula (III).
In general formula (III), R ⁴ and R ⁸ each independently represents a hydrogen atom or a methyl group.
R ⁵ , R ⁶ , R ⁹ , and R ¹⁰ each independently represents a linear or branched alkyl group, specifically, a carbon number such as a methyl group, an ethyl group, a propyl group, or a butyl group. An alkyl group having 1 to 4 carbon atoms is preferable, and an alkyl group having 1 to 2 carbon atoms is more preferable.
R ⁷ is a linear or branched alkylene group, and more specifically, an alkylene group having 1 to 8 carbon atoms such as methylene, ethylene, trimethylene, or tetramethylene is preferable, and more preferably 2 to 6 carbon atoms. An alkylene group.
Examples of the diacrylate represented by the general formula (III) include 2,5-dimethylhexyl-2,5-diacrylate, 2,5-dimethylhexyl-2,5-dimethacrylate, and the like.

In the unit (c1), the carbon atom to which R ⁵ and R ⁶ are bonded in the general formula (III) is a tertiary carbon atom. The carbon atom to which R ⁹ and R ¹⁰ are bonded is a tertiary carbon atom. Therefore, in the unit (c) 1, “— (R ⁵ ) (R ⁶ ) C—C— (R ⁹ ) (R ¹⁰ ) —” is an acid dissociable, dissolution inhibiting group. That is, when an acid acts, a bond is cut between the tertiary carbon atom and an oxygen atom to which the tertiary carbon atom is bonded, and the core part is decomposed.
Thus, when forming a resist pattern, a difference in solubility between the unexposed portion and the exposed portion in the developer can be caused.

  In all repeating units constituting the component (A1), the proportion of the unit (c1) is 1 to 30 mol%, preferably 5 to 20 mol%, and further 5 to 15 mol%. By setting it to the lower limit value or more, the solubility contrast between the unexposed area and the exposed area can be controlled. By setting the lower limit value or less, it is possible to balance with other repeating units.

-Manufacturing method of (A1) component As a manufacturing method of (A1),
(1) A method in which an arm monomer is synthesized by anionic polymerization of an arm monomer in the presence of an anionic polymerization initiator, and then a core diacrylate is reacted.
(2) A method of reacting a core part diacrylate in the presence of an anionic polymerization initiator to form a core and then anionic polymerization of an arm part monomer,
(3) An example is a method of synthesizing an arm polymer by anionic polymerization of an arm monomer in the presence of an anionic polymerization initiator, then reacting a core diacrylate, and further reacting an arm monomer. it can.
The above methods (1) and (3) are preferable in that the reaction can be easily controlled and a star polymer having a controlled structure is produced.

Examples of the anionic polymerization initiator used in the anionic polymerization method include alkali metals and organic alkali metals.
Examples of the alkali metal include lithium, sodium, potassium, cesium and the like.
Examples of the organic alkali metal include alkylated products, allylated products, and arylated products of the above alkali metals. Specifically, ethyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, ethyl sodium, lithium biphenyl, lithium naphthalene, lithium triphenyl, sodium naphthalene, α-methylstyrene sodium dianion, 1,1- Diphenylhexyl lithium, 1,1-diphenyl-3-methylpentyl lithium and the like can be mentioned.

  As the polymerization reaction for synthesizing the arm polymer in the method of (1) above, a method of dropping an anionic polymerization initiator into a monomer (mixed) solution or a method of dropping a monomer (mixed) solution into a solution containing an anionic polymerization initiator. Any method can be used, but since the molecular weight and molecular weight distribution can be controlled, a method in which a monomer (mixed) solution is dropped into a solution containing an anionic polymerization initiator is preferable. This arm polymer synthesis reaction is usually carried out in an organic solvent under an inert gas atmosphere such as nitrogen or argon at a temperature in the range of −100 to 50 ° C., preferably −100 to 40 ° C.

Examples of the organic solvent used for the synthesis reaction of the arm polymer include aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and cyclopentane; aromatic carbonization such as benzene and toluene. In addition to hydrogens; ethers such as diethyl ether, tetrahydrofuran (THF) and dioxane; and organic solvents usually used in anionic polymerization such as anisole and hexamethylphosphoramide. These can be used as a single solvent or a mixed solvent of two or more.
Among these, from the viewpoint of polarity and solubility, a mixed solvent of THF and toluene, THF and hexane, THF and methylcyclohexane can be preferably exemplified.

  Examples of the polymerized form of the arm polymer include a random copolymer, a partial block copolymer, and a complete block copolymer in which each component is statistically distributed over the entire copolymer chain. Can be synthesized by selecting the addition method.

  The reaction for producing a star polymer using the arm polymer thus obtained as a branched polymer chain can be carried out by adding the above-mentioned diacrylate to the reaction solution after completion of the arm polymer synthesis reaction. This reaction is usually controlled by carrying out a polymerization reaction at −100 ° C. to 50 ° C., preferably −70 ° C. to 40 ° C. in an organic solvent under an inert gas atmosphere such as nitrogen or argon. In addition, a polymer having a narrow molecular weight distribution can be obtained. In addition, the star polymer formation reaction can be performed continuously in the solvent used to form the arm polymer, the composition is changed by adding a solvent, or the solvent is replaced with another solvent. It can also be done. As such a solvent, the same solvent as that used in the arm polymer synthesis reaction can be used.

In the star polymer production method, the molar ratio of the core part diacrylate (P) and the active terminal (D) of the polymer chain obtained by polymerizing the arm part monomer by an anionic polymerization method using an anionic polymerization initiator as a polymerization initiator [( P) / (D)] is preferably 0.1-10.
The reaction between the arm polymer chain and the core part diacrylate can be performed by either adding the core part diacrylate to the arm polymer chain having an active terminal or adding the arm polymer chain having an active terminal to the core part diacrylate. Can also be adopted.

The number of arms of the star polymer is determined by the amount of core diacrylate added, the reaction temperature, and the reaction time, but it is usually affected by the difference in reactivity between the end of the living polymer and the vinyl group of the core diacrylate, steric hindrance, etc. As a result, a plurality of star block copolymers having different numbers of arms are formed simultaneously.
Further, the ratio (Mw / Mn) of the mass average molecular weight (Mw) and the number average molecular weight (Mn) of the star polymer to be produced is preferably in the range of 1.00 to 1.50, and the number average molecular weight is 3 , Preferably from 3,000 to 300,000.

The arm core monomer is reacted with a central core having an active terminal (polyfunctional core) formed by reacting a previously prepared arm polymer chain with a core diacrylate to form a new arm polymer chain. In the method (3), star polymers having different types of arm polymer chains can be produced.
The active terminal present in the central core can be reacted directly with a polymerizable monomer, but after reacting with a compound such as diphenylethylene or stilbene, an alkali metal or alkaline earth metal such as lithium chloride is also available. After adding the mineral acid salt, if the monomer is reacted, if a highly reactive monomer such as an acrylic acid derivative is reacted, the polymerization reaction can proceed slowly, and the entire star polymer produced It may be advantageous in controlling the structure.
In addition, the above reaction can be continuously performed in the solvent used to form the central nucleus having an active end, the composition is changed by adding a solvent, or the solvent is replaced with another solvent. It can also be done. Examples of such a solvent include the same solvents as those used for the synthesis of the arm polymer.
Also, the reaction is performed by mixing two monomers as the arm polymer chain newly introduced to the active terminal existing in the central core in the method (3) or the arm polymer chain in the method (2). Thus, it is possible to obtain a polymer chain that is randomly copolymerized or a block polymer chain by sequentially adding two kinds of monomers.

  The component (A1) can be used alone or in combination of two or more.

"Second aspect"
In the second embodiment, the component (A) includes the star polymer (A2) (hereinafter sometimes referred to as the component (A2)).
In the component (A2), the arm part may be referred to as a unit (a1) and a repeating unit derived from the alkenylphenyl represented by the general formula (IV) [hereinafter referred to as unit (a3). ],
And a polymer chain composed of the unit (a2), and the core part is a star polymer composed of the same structure as the component (A1).
In the component (A2), the difference from the component (A1) is that the arm portion requires the unit (a3), and the rest is the same.
Hereinafter, only the changes will be described, and other descriptions will be omitted.

..Unit (a3)
In the general formula (IV), R ¹ is a hydrogen atom or a methyl group.
The ratio of the unit (a1) and the unit (a2) in the total repeating units constituting the component (A2) is 40 to 90 mol%, preferably 50 to 85 mol%, and more preferably 75 to 85 mol%. Furthermore, the ratio of the unit (a3) in all repeating units constituting the component (A2) is 1 to 30 mol%, preferably 2 to 15 mol%. By setting it to the lower limit value or more, the solubility contrast between the unexposed area and the exposed area can be controlled. By setting the lower limit value or less, it is possible to balance with other repeating units.
In the resist composition of the present invention, the star polymer arm portion contained in the base resin may have at least the unit (a1) and the unit (a2), and the arm portion particularly has the unit (a3). By having it, there exists an advantage that control of solubility etc. becomes easy.

  The component (A2) can be used alone or in combination of two or more.

（式中、Ｒ^２は前記と同じ意味である）
で表されるアクリレートから誘導される繰り返し単位（ａ４）［以下、単位（ａ４）ということがある。］を含むポリマー鎖を含んでいてもよい。
単位（ａ４）を含むことにより、（Ａ１）成分、（Ａ２）成分全体の親水性が高まり、現像液との親和性が高まって、露光部でのアルカリ溶解性が向上し、解像性が向上するという効果が得られる。
単位（ａ４）は、（Ａ１）成分または（Ａ２）成分を構成する全繰り返し単位中１０〜５０モル％、好ましくは２０〜４０モル％含まれていることが望ましい。 Further, in any of the components (A1) and (A2), the arm portion has the following general formula:

(Wherein R ² has the same meaning as described above)
A repeating unit derived from an acrylate represented by the formula (a4) [hereinafter sometimes referred to as a unit (a4). ] May be included.
By including the unit (a4), the hydrophilicity of the components (A1) and (A2) as a whole is increased, the affinity with the developer is increased, the alkali solubility in the exposed area is improved, and the resolution is improved. The effect of improving is acquired.
The unit (a4) is desirably contained in an amount of 10 to 50 mol%, preferably 20 to 40 mol%, in all repeating units constituting the component (A1) or the component (A2).

As the base resin of the positive resist composition of the present invention, at least one of the components (A1) and (A2) may be used, and these may be combined as appropriate.
Moreover, in (A) component, things other than (A1) component and / or (A2) component can also be mix | blended. For example, a hydroxystyrene resin proposed as a base resin for a KrF resist can be used as appropriate. However, it is desirable that the component (A1) and / or the component (A2) is 70% by mass or more, preferably 80% by mass or more, particularly 100% by mass in the component (A).

(B) Compound that generates an acid upon irradiation (exposure) of radiation In the present invention, the component (B) is not particularly limited from known so-called acid generators used in conventional chemically amplified resist compositions. Can be used. Examples of such acid generators include onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, poly (bissulfonyl) diazomethanes, There are various known diazomethane acid generators such as diazomethane nitrobenzyl sulfonates, imino sulfonate acid generators and disulfone acid generators.

  Specific examples of the onium salt-based acid generator include diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, bis (4-tert-butylphenyl) iodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, and triphenylsulfonium trifluoromethane. Sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, tri (4-methylphenyl) sulfonium trifluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, dimethyl (4-hydroxynaphthyl) sulfonium trifluoromethane Sulfonate, its heptafluoropropane sulphonate or its Nafluorobutane sulfonate, trifluoromethane sulfonate of monophenyldimethylsulfonium, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, trifluoromethane sulfonate of diphenylmonomethylsulfonium, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate .

  Specific examples of the oxime sulfonate acid generator include α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoromethylsulfonyloxyimino)- Phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (propylsulfonyloxyimino) -p-methylphenylacetonitrile, α- (methylsulfonyloxyimino) -p-bromophenylacetonitrile and the like can be mentioned. Of these, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile is preferred.

Among diazomethane acid generators, specific examples of bisalkyl or bisarylsulfonyldiazomethanes include bis (isopropylsulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (1,1-dimethylethylsulfonyl) diazomethane, Examples include bis (cyclohexylsulfonyl) diazomethane, bis (2,4-dimethylphenylsulfonyl) diazomethane, and the like.
Examples of poly (bissulfonyl) diazomethanes include 1,3-bis (phenylsulfonyldiazomethylsulfonyl) propane (Compound A, decomposition point 135 ° C.), 1,4-bis (phenyl) having the following structure. Sulfonyldiazomethylsulfonyl) butane (compound B, decomposition point 147 ° C.), 1,6-bis (phenylsulfonyldiazomethylsulfonyl) hexane (compound C, melting point 132 ° C., decomposition point 145 ° C.), 1,10-bis (phenyl) Sulfonyldiazomethylsulfonyl) decane (compound D, decomposition point 147 ° C.), 1,2-bis (cyclohexylsulfonyldiazomethylsulfonyl) ethane (compound E, decomposition point 149 ° C.), 1,3-bis (cyclohexylsulfonyldiazomethylsulfonyl) ) Propane (Compound F, decomposition point 153 ° C.), , 6-bis (cyclohexylsulfonyldiazomethylsulfonyl) hexane (Compound G, melting point 109 ° C., decomposition point 122 ° C.), 1,10-bis (cyclohexylsulfonyldiazomethylsulfonyl) decane (Compound H, decomposition point 116 ° C.), etc. Can be mentioned.

As the component (B), one type of acid generator may be used alone, or two or more types may be used in combination.
(B) Content of a component is 0.5-30 mass parts with respect to 100 mass parts of (A) component, Preferably it is 1-10 mass parts. By setting it to the lower limit value or more, pattern formation is sufficiently performed, and when it is set to the upper limit value or less, a uniform solution can be obtained and good storage stability can be obtained.

(D) Nitrogen-containing organic compound In the positive resist composition of the present invention, a nitrogen-containing organic compound (D) (hereinafter, (Referred to as component (D)).
Since a wide variety of components (D) have already been proposed, any known one may be used, but amines, particularly secondary lower aliphatic amines and tertiary lower aliphatic amines are preferred. .
Here, the lower aliphatic amine refers to an alkyl or alkyl alcohol amine having 5 or less carbon atoms, and examples of the secondary and tertiary amines include trimethylamine, diethylamine, triethylamine, di-n-propylamine, Tri-n-propylamine, tripentylamine, diethanolamine, triethanolamine, triisopropanolamine and the like can be mentioned, and tertiary alkanolamines such as triethanolamine are particularly preferable.
These may be used alone or in combination of two or more.
(D) component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

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

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

Other optional components In the positive resist composition of the present invention, there are further miscible additives as desired, for example, additional resins for improving the performance of the resist film, surfactants for improving the coating properties, A dissolution inhibitor, a plasticizer, a stabilizer, a colorant, an antihalation agent and the like can be appropriately added and contained.

[Resist pattern formation method]
The resist pattern forming method of the present invention can be performed, for example, as follows.
That is, first, the positive resist composition is applied onto a support such as a silicon wafer with a spinner or the like, and prebaked at a temperature of 80 to 150 ° C. for 40 to 120 seconds, preferably 60 to 90 seconds. For example, after KrF excimer laser light is selectively exposed (irradiated with radiation) through a desired mask pattern by a KrF exposure apparatus or the like, PEB (post-exposure heating) is performed at a temperature of 80 to 150 ° C. It is applied for -120 seconds, preferably 60-90 seconds. Subsequently, this is developed using an alkaline developer, for example, an aqueous 0.1 to 10% by mass tetramethylammonium hydroxide solution. In this way, a resist pattern faithful to the mask pattern can be obtained.
An organic or inorganic antireflection film may be provided between the support (substrate) and the coating layer of the resist composition.
Further, after the development, post-baking can be further performed under conditions of, for example, 100 ° C. and about 60 seconds.

The support is not particularly limited, and a conventionally known one can be used. Examples thereof include a substrate for electronic parts and a substrate on which a predetermined wiring pattern is formed.
Examples of the substrate include a silicon wafer, a metal substrate such as copper, chromium, iron, and aluminum, and a glass substrate.
As a material for the wiring pattern, for example, copper, solder, chrome, aluminum, nickel, gold or the like can be used.

The wavelength used for exposure (irradiation of radiation) is not particularly limited. ArF excimer laser, KrF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), EB (electron beam), X-ray, It can be performed using radiation such as soft X-rays. In particular, the resist composition according to the present invention is effective for a KrF excimer laser.

In the present invention, a chemically amplified positive resist composition using a material different from the conventional material that can be applied for a KrF excimer laser and a resist pattern forming method using the same can be provided.
Since the star polymer used in the present invention has a narrow molecular weight distribution and is obtained in a high yield, an inexpensive resist composition can be provided.
Further, in the polymer, the arrangement of each monomer unit can be controlled, and the improvement of resist characteristics can be achieved.

EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example, the scope of the present invention is not limited to an Example.
In addition, the meaning of the abbreviation used in an Example is as follows.
THF: Tetrahydrofuran NBL: n-butyllithium PEES: 4- [2-ethoxyethoxy] -styrene ECHMA: 1-ethylcyclohexyl methacrylate MDA: 2,5-dimethylhexyl-2,5-diacrylate

(Synthesis Example 1)
A star polymer was produced by the following method.

Under a nitrogen atmosphere, a mixed solvent of 300 g of THF and 75 g of n-hexane was maintained at −40 ° C., 4.2 g (10 mmol) of NBL was added, and 42.0 g (0.22 mol) of PEES was added over 30 minutes with stirring. The reaction was further continued for 30 minutes, and the completion of the reaction was confirmed by GC (gas chromatography). A small amount was collected from the reaction system at this stage, and the reaction was stopped with methanol, and then analyzed by GPC (gel permeation chromatography). As a result, the obtained polymer was a single polymer of Mn = 6300 and Mw / Mn = 1.14. It was a dispersed polymer.
Next, the reaction system was cooled to −60 ° C., 150 g of THF containing 0.1 mol of lithium chloride was added, 8.5 g (43 mmol) of ECHMA was added dropwise over 30 minutes, and the reaction was further continued for 30 minutes. The completion of the reaction was confirmed. A small amount was collected from the reaction system at this stage, and the reaction was stopped with methanol, and then analyzed by GPC. As a result, the obtained copolymer was a monodisperse polymer with Mn = 6700 and Mw / Mn = 1.17. It was.
Next, 7.4 g (29 mmol) of MDA was added dropwise, and the reaction was further continued for 1 hour, and the completion of the reaction was confirmed by GC. The reaction solution was poured into a large amount of methanol to precipitate a polymer, filtered and washed, and then dried under reduced pressure at 60 ° C. for 5 hours to obtain 57 g of a white powdery polymer. The polymerization yield based on the total amount of monomers used was 99%.
When this polymer was analyzed by GPC, it was a mixture of Mn = 31000 and Mw / Mn = 1.16 in the star polymer part, Mn = 7300 and Mw / Mn = 1.12 in the arm polymer part.

Next, 54 g of the obtained polymer was dissolved in THF to make a 30% solution, 2 g of concentrated hydrochloric acid was added and reacted at room temperature for 1 hour, and then the reaction solution was poured into a large amount of water to precipitate the polymer. After filtration and washing, it was dried under reduced pressure at 60 ° C. for 5 hours to obtain 41 g of a white powdery polymer.
When GPC analysis of this polymer was performed, it was a mixture of Mn = 26000 and Mw / Mn = 1.17 in the star polymer portion, and Mn = 6000 and Mw / Mn = 1.13 in the arm polymer portion.
^{By 13} C-NMR, a signal of para-position carbon of the aromatic ring of the p-hydroxystyrene unit is observed near 155 ppm, a signal of the ethyl group carbon of ECHMA unit near 85 ppm, and a signal of the methyl group carbon of MDA unit near 81 ppm. From the respective integration ratios, it was confirmed that the composition ratio of p-hydroxystyrene / ECHMA / MDA was 75/15/10.
From the above, the reaction and the subsequent elimination reaction were carried out as intended, and it was confirmed that p-hydroxystyrene-ECHMA-MDA star polymer was produced.

(Synthesis Example 2)
Under a nitrogen atmosphere, a mixed solvent of 300 g of THF and 75 g of n-hexane was maintained at −40 ° C., 4.2 g (10 mmol) of n-butyllithium (hereinafter abbreviated as NBL) was added, and 4- [2 -Ethoxyethoxy] -styrene (hereinafter abbreviated as PEES) 41.6 g (0.22 mol) was added dropwise over 30 minutes, the reaction was further continued for 30 minutes, and the completion of the reaction was confirmed by GC. A small amount was collected from the reaction system at this stage, and the reaction was stopped with methanol. After analysis by GPC, the obtained polyPEES was a monodisperse polymer with Mn = 6100 and Mw / Mn = 1.15. .

  Next, the reaction system was cooled to −60 ° C., 150 g of THF containing 0.1 mol of lithium chloride was added, and 5.3 g (27 mmol) of 1-ethylcyclohexyl methacrylate (ECHMA) was added dropwise over 30 minutes to further react. Was continued for 30 minutes, and the completion of the reaction was confirmed by GC. At this stage, a small amount was collected from the reaction system, and the reaction was stopped with methanol, and then analyzed by GPC. It was a polymer.

Then, 6.9 g (27 mmol) of 2,5-dimethylhexyl-2,5-diacrylate (hereinafter abbreviated as MDA) was added dropwise, and the reaction was further continued for 1 hour, and the completion of the reaction was confirmed by GC. . The reaction solution was poured into a large amount of methanol to precipitate a polymer, filtered, washed, and dried under reduced pressure at 60 ° C. for 5 hours to obtain 53 g of a white powdery polymer. The polymerization yield based on the total amount of monomers used was 99%.
When this polymer was analyzed by GPC, it was a mixture of Mn = 29000 and Mw / Mn = 1.17 in the star polymer portion, and Mn = 7100 and Mw / Mn = 1.15 in the arm polymer portion.

Next, 53 g of the obtained polymer was dissolved in THF to make a 30% solution, 2 g of concentrated hydrochloric acid was added and reacted at room temperature for 1 hour, and then the reaction solution was poured into a large amount of water to precipitate the polymer. After filtration and washing, it was dried under reduced pressure at 60 ° C. for 5 hours to obtain 38 g of a white powdery polymer.
As a result of GPC analysis of this polymer, it was a mixture of Mn = 24000 and Mw / Mn = 1.18 in the star polymer portion, and Mn = 5600 and Mw / Mn = 1.14 in the arm polymer portion.
^{By 13} C-NMR, a signal of para-position carbon of the aromatic ring of p-hydroxystyrene unit is observed around 155 ppm, a signal of ethyl group carbon of ECHMA unit around 85 ppm, and a signal of methyl group carbon of MDA unit around 81 ppm. From the respective integration ratios, it was confirmed that the composition ratio of p-hydroxystyrene / ECHMA / MDA was 80/10/10.
From the above, the reaction and the subsequent elimination reaction were carried out as intended, and it was confirmed that p-hydroxystyrene-ECHMA-MDA star polymer was produced.

(Synthesis Example 3)
Under a nitrogen atmosphere, a mixed solvent of 300 g of THF and 75 g of n-hexane was maintained at −40 ° C., 4.2 g (10 mmol) of NBL was added, and 38.5 g (0.20 mol) of PEES and styrene (hereinafter, referred to as “NES”) were stirred. 3.0 g (30 mmol) was agitated over 30 minutes, and the reaction was further continued for 30 minutes. The completion of the reaction was confirmed by GC. At this stage, a small amount was collected from the reaction system, and the reaction was stopped with methanol, and then analyzed by GPC. As a result, the obtained PEES / St copolymer was monodispersed with Mn = 6200 and Mw / Mn = 1.13. It was a polymer.
Next, the reaction system was cooled to −60 ° C., 150 g of THF containing 0.1 mol of lithium chloride was added, 9.1 g (46 mmol) of ECHMA was added dropwise over 30 minutes, and the reaction was further continued for 30 minutes. To confirm the completion of the reaction. At this stage, a small amount was collected from the reaction system, and the reaction was stopped with methanol, and then analyzed by GPC. As a result, the obtained PEES / St / ECHMA copolymer had Mn = 6600 and Mw / Mn = 1.16. It was a monodisperse polymer.

Next, 7.6 g (30 mmol) of MDA was added dropwise, and the reaction was further continued for 1 hour, and the completion of the reaction was confirmed by GC. The reaction solution was poured into a large amount of methanol to precipitate a polymer, filtered, washed, and dried under reduced pressure at 60 ° C. for 5 hours to obtain 58 g of a white powdery polymer. The polymerization yield based on the total amount of monomers used was 99%.
When this polymer was analyzed by GPC, it was a mixture of Mn = 30000 and Mw / Mn = 1.16 in the star polymer portion, and Mn = 7000 and Mw / Mn = 1.13 in the arm polymer portion.

Next, 58 g of the obtained polymer was dissolved in THF to form a 30% solution, 2 g of concentrated hydrochloric acid was added and reacted at room temperature for 1 hour, and then the reaction solution was poured into a large amount of water to precipitate the polymer. After filtration and washing, it was dried under reduced pressure at 60 ° C. for 5 hours to obtain 43 g of a white powdery polymer.
As a result of GPC analysis of this polymer, it was a mixture of Mn = 23000 and Mw / Mn = 1.15 in the star polymer portion, and Mn = 5800 and Mw / Mn = 1.14 in the arm polymer portion.
^{By 13} C-NMR, the signal of para-position carbon of the aromatic ring of p-hydroxystyrene unit at around 155 ppm, the signal of aromatic-bonded carbon of styrene unit at around 145 ppm, the signal of ethyl group carbon of ECHMA unit at around 85 ppm, 81 ppm The signal of the methyl group carbon of the MDA unit was observed in the vicinity, and from the respective integration ratios, it was confirmed that the composition ratio of p-hydroxystyrene / St / ECHMA / MDA was 65/10/15/10.
From the above, the reaction and the subsequent elimination reaction were carried out as intended, and it was confirmed that p-hydroxystyrene-St-ECHMA-MDA star polymer was produced.

(Synthesis Example 4)
In a nitrogen atmosphere, 200 g of THF was maintained at −40 ° C., 7.8 g (10 mmol) of SBL was added, and 38.5 g (0.20 mol) of PEES and 3.0 g (30 mmol) of St were added for 30 minutes with stirring. The reaction was continued for 30 minutes, and the completion of the reaction was confirmed by GC. At this stage, a small amount was collected from the reaction system, and the reaction was stopped with methanol. After analysis by GPC, the obtained PEES / St copolymer was monodispersed with Mn = 4500 and Mw / Mn = 1.07. It was a polymer.

  Next, the reaction system was cooled to −60 ° C., 120 g of THF containing 0.1 mol of lithium chloride was added, and 9.4 g (43 mmol) of 1-adamantyl methacrylate (hereinafter abbreviated as AdMA) was added dropwise over 30 minutes. Further, the reaction was continued for 30 minutes, and the completion of the reaction was confirmed by GC. A small amount was collected from the reaction system at this stage, and the reaction was stopped with methanol, and then analyzed by GPC. As a result, the obtained PEES / St / AdMA copolymer had Mn = 5500 and Mw / Mn = 1.07. It was a monodisperse polymer.

Next, 7.5 g (30 mmol) of MDA was added dropwise, and the reaction was further continued for 1 hour, and the completion of the reaction was confirmed by GC. The reaction solution was poured into a large amount of methanol to precipitate a polymer, filtered, washed, and dried under reduced pressure at 60 ° C. for 5 hours to obtain 58 g of a white powdery polymer. The polymerization yield based on the total amount of monomers used was 99%.
When this polymer was analyzed by GPC, it was a mixture of Mn = 27000 and Mw / Mn = 1.15 in the star polymer portion, and Mn = 5500 and Mw / Mn = 1.14 in the arm polymer portion.

Next, 58 g of the obtained polymer was dissolved in THF to form a 30% solution, 2 g of concentrated hydrochloric acid was added and reacted at room temperature for 1 hour, and then the reaction solution was poured into a large amount of water to precipitate the polymer. After filtration and washing, it was dried under reduced pressure at 60 ° C. for 5 hours to obtain 43 g of a white powdery polymer.
As a result of GPC analysis of this polymer, it was a mixture of Mn = 24000 and Mw / Mn = 1.15 in the star polymer portion, and Mn = 5100 and Mw / Mn = 1.14 in the arm polymer portion.
^{By 13} C-NMR, the signal of the para-position carbon of the aromatic ring of the p-hydroxystyrene unit at around 155 ppm, the signal of the aromatic ring-bonded carbon of the styrene unit at around 145 ppm, the signal of the ester-bonded carbon of the AdMA unit at around 79 ppm, 81 ppm The signal of the methyl group carbon of the MDA unit was observed in the vicinity, and it was confirmed from the respective integration ratios that the composition ratio of p-hydroxystyrene / St / AdMA / MDA was 65/10/15/10.
From the above, the reaction and the subsequent elimination reaction were carried out as intended, and it was confirmed that p-hydroxystyrene-St-AdMA-MDA star polymer was produced.

(Synthesis Example 5)
In a nitrogen atmosphere, 200 g of THF was maintained at −40 ° C., 7.8 g (10 mmol) of SBL was added, and 38.5 g (0.20 mol) of PEES and 3.0 g (30 mmol) of St were added for 30 minutes with stirring. The reaction was continued for 30 minutes, and the completion of the reaction was confirmed by GC. A small amount was collected from the reaction system at this stage, and the reaction was stopped with methanol, and then analyzed by GPC. As a result, the obtained PEES / St copolymer was monodispersed with Mn = 4900 and Mw / Mn = 1.07. It was a polymer.

  Next, 10.0 g (43 mmol) of 2-methyladamantyl methacrylate (hereinafter abbreviated as 2MAdMA) was added dropwise over 30 minutes, and the reaction was further continued for 30 minutes. The completion of the reaction was confirmed by GC. At this stage, a small amount was collected from the reaction system, and the reaction was stopped with methanol and then analyzed by GPC. As a result, the obtained PEES / St / 2MAdMA copolymer had Mn = 5300 and Mw / Mn = 1.10. It was a monodisperse polymer.

Next, the reaction system was cooled to −60 ° C., 120 g of THF containing 0.1 mol of lithium chloride was added, 7.5 g (30 mmol) of MDA was added dropwise, and the reaction was further continued for 1 hour, and the reaction was completed by GC. confirmed. The reaction solution was poured into a large amount of methanol to precipitate a polymer, filtered, washed, and dried under reduced pressure at 60 ° C. for 5 hours to obtain 58 g of a white powdery polymer. The polymerization yield based on the total amount of monomers used was 99%.
When this polymer was analyzed by GPC, it was a mixture of Mn = 35000 and Mw / Mn = 1.15 in the star polymer portion, and Mn = 5500 and Mw / Mn = 1.15 in the arm polymer portion.

Next, 58 g of the obtained polymer was dissolved in THF to form a 30% solution, 2 g of concentrated hydrochloric acid was added and reacted at room temperature for 1 hour, and then the reaction solution was poured into a large amount of water to precipitate the polymer. After filtration and washing, it was dried under reduced pressure at 60 ° C. for 5 hours to obtain 44 g of a white powdery polymer.
As a result of GPC analysis of this polymer, it was a mixture of Mn = 34000 and Mw / Mn = 1.15 in the star polymer portion, and Mn = 4700 and Mw / Mn = 1.15 in the arm polymer portion.
^{By 13} C-NMR, the signal of the para-position carbon of the aromatic ring of p-hydroxystyrene unit at around 155 ppm, the signal of the aromatic ring-bonded carbon of styrene unit at around 145 ppm, the signal of the ester-bonded carbon of 2 MAdMA unit at around 86 ppm, 81 ppm The signal of the methyl group carbon of the MDA unit was observed in the vicinity, and from the respective integration ratios, it was confirmed that the composition ratio of p-hydroxystyrene / St / 2MAdMA / MDA was 65/10/15/10.
From the above, the reaction and the subsequent elimination reaction were carried out as intended, and it was confirmed that p-hydroxystyrene-St-2MAdMA-MDA star polymer was produced.

(Synthesis Example 6)
In a nitrogen atmosphere, 200 g of THF was maintained at −40 ° C., 7.8 g (10 mmol) of SBL was added, and 38.5 g (0.20 mol) of PEES and 3.0 g (30 mmol) of St were added for 30 minutes with stirring. The reaction was continued for 30 minutes, and the completion of the reaction was confirmed by GC. A small amount was collected from the reaction system at this stage, and the reaction was stopped with methanol, and then analyzed by GPC. As a result, the obtained PEES / St copolymer was monodispersed with Mn = 4900 and Mw / Mn = 1.07. It was a polymer.

  Next, 10.6 g (43 mmol) of 2-ethyladamantyl methacrylate (hereinafter abbreviated as 2EAdMA) was added dropwise over 30 minutes, and the reaction was further continued for 30 minutes. The completion of the reaction was confirmed by GC. A small amount was collected from the reaction system at this stage, and the reaction was stopped with methanol, and then analyzed by GPC. As a result, the obtained PEES / St / 2EAdMA copolymer had Mn = 5600 and Mw / Mn = 1.08. It was a monodisperse polymer.

Next, the reaction system was cooled to −60 ° C., 120 g of THF containing 0.1 mol of lithium chloride was added, 7.5 g (30 mmol) of MDA was added dropwise, and the reaction was further continued for 1 hour, and the reaction was completed by GC. confirmed. The reaction solution was poured into a large amount of methanol to precipitate a polymer, filtered, washed, and dried under reduced pressure at 60 ° C. for 5 hours to obtain 59 g of a white powdery polymer. The polymerization yield based on the total amount of monomers used was 99%.
When this polymer was analyzed by GPC, it was a mixture of Mn = 36000 and Mw / Mn = 1.17 in the star polymer portion, and Mn = 5600 and Mw / Mn = 1.15 in the arm polymer portion.

Next, 59 g of the obtained polymer was dissolved in THF to make a 30% solution, 2 g of concentrated hydrochloric acid was added and reacted at room temperature for 1 hour, and then the reaction solution was poured into a large amount of water to precipitate the polymer. After filtration and washing, it was dried under reduced pressure at 60 ° C. for 5 hours to obtain 45 g of a white powdery polymer.
As a result of GPC analysis of this polymer, it was a mixture of Mn = 34000 and Mw / Mn = 1.16 in the star polymer portion, and Mn = 4800 and Mw / Mn = 1.15 in the arm polymer portion.
^{By 13} C-NMR, the signal of the para-position carbon of the aromatic ring of p-hydroxystyrene unit at around 155 ppm, the signal of the aromatic ring-bonded carbon of styrene unit at around 145 ppm, the signal of the ester-bonded carbon of 2EAdMA unit at around 90 ppm, 81 ppm A signal of methyl group carbon of MDA unit was observed in the vicinity, and from each integration ratio, it was confirmed that the composition ratio of p-hydroxystyrene / St / 2EAdMA / MDA was 65/10/15/10.
From the above, the reaction and the subsequent elimination reaction were carried out as intended, and it was confirmed that p-hydroxystyrene-St-2EAdMA-MDA star polymer was produced.

(Synthesis Example 7)
Under a nitrogen atmosphere, a mixed solvent of 300 g of THF and 75 g of n-hexane was kept at −40 ° C., 4.2 g (10 mmol) of NBL was added, and 38.5 g (0.20 mol) of PEES and 3.0 g of St were stirred. (30 mmol) was added dropwise over 30 minutes, and the reaction was further continued for 30 minutes, and the completion of the reaction was confirmed by GC. A small amount was collected from the reaction system at this stage, and the reaction was stopped with methanol, and then analyzed by GPC. As a result, the obtained PEES / St copolymer was monodispersed with Mn = 6000 and Mw / Mn = 1.14. It was a polymer.
Next, the reaction system was cooled to −60 ° C., 150 g of THF containing 0.1 mol of lithium chloride was added, 9.1 g (46 mmol) of ECHMA was added dropwise over 30 minutes, and the reaction was further continued for 30 minutes. To confirm the completion of the reaction. A small amount was collected from the reaction system at this stage, and the reaction was stopped with methanol, and then analyzed by GPC. As a result, the obtained PEES / St / ECHMA copolymer had Mn = 6400 and Mw / Mn = 1.18. It was a monodisperse polymer.

Subsequently, 8.7 g (30 mmol) of 2,5-dimethylhexyl-2,5-dimethacrylate (hereinafter abbreviated as MDMA) was added dropwise, and the reaction was further continued for 1 hour, and the completion of the reaction was confirmed by GC. . The reaction solution was poured into a large amount of methanol to precipitate a polymer, filtered, washed, and dried under reduced pressure at 60 ° C. for 5 hours to obtain 58 g of a white powdery polymer. The polymerization yield based on the total amount of monomers used was 99%.
When this polymer was analyzed by GPC, it was a mixture of Mn = 34000 and Mw / Mn = 1.16 in the star polymer portion, Mn = 6700 and Mw / Mn = 1.13 in the arm polymer portion.

Next, 58 g of the obtained polymer was dissolved in THF to form a 30% solution, 2 g of concentrated hydrochloric acid was added and reacted at room temperature for 1 hour, and then the reaction solution was poured into a large amount of water to precipitate the polymer. After filtration and washing, it was dried under reduced pressure at 60 ° C. for 5 hours to obtain 43 g of a white powdery polymer.
When GPC analysis of this polymer was performed, it was a mixture of Mn = 32000 and Mw / Mn = 1.17 in the star polymer portion, and Mn = 6000 and Mw / Mn = 1.13 in the arm polymer portion.
^{By 13} C-NMR, the signal of the para-position carbon of the aromatic ring of the p-hydroxystyrene unit at around 155 ppm, the signal of the aromatic ring-bonded carbon of the styrene unit at around 145 ppm, the signal of the ethyl group carbon of the ECHMA unit at around 85 ppm, 82 ppm The signal of the methyl group carbon of the MDMA unit was observed in the vicinity, and it was confirmed from the respective integration ratios that the composition ratio of p-hydroxystyrene / St / ECHMA / MDMA was 65/10/15/10.
From the above, the reaction and the subsequent elimination reaction were carried out as intended, and it was confirmed that p-hydroxystyrene-St-ECHMA-MDMA star polymer was produced.

(Example)
A positive resist composition having the following composition was produced.
(A) Component: Star polymer synthesized in Synthesis Example 1 100 parts by mass (B) Component: Bis (4-tert-butylphenyl) iodonium nonafluorobutanesulfonate (A) 5 parts by mass with respect to 100 parts by mass of component (D ) Component: Triethanolamine (A) 0.15 parts by mass with respect to 100 parts by mass of the component (E) Component: Salicylic acid 0.14 parts by mass with respect to 100 parts by mass of the component (A) Organic solvent: Propylene glycol monomethyl ether acetate 700 parts by mass

Next, a resist pattern was formed as follows using this positive resist composition.
That is, an organic antireflection film composition “ARC-29A” (trade name, manufactured by Brewer Science Co., Ltd.) was applied onto an 8-inch silicon wafer using a spinner, and baked on a hot plate at 205 ° C. for 60 seconds. By drying, an organic antireflection film having a thickness of 77 nm was formed.
Then, the positive resist composition was applied on the antireflection film using a spinner, prebaked (PAB) at 130 ° C. for 90 seconds on a hot plate, and dried to form a resist layer having a thickness of 450 nm. .
Next, a KrF excimer laser (248 nm) was selectively irradiated via a mask pattern (binary) by a KrF exposure apparatus S203B (manufactured by Nikon Corporation; NA (numerical aperture) = 0.68, 2/3 ring zone). .
Then, PEB treatment was performed at 130 ° C. for 90 seconds, and further paddle development was performed at 23 ° C. with a 2.38 mass% tetramethylammonium hydroxide aqueous solution for 60 seconds, followed by washing with water for 60 seconds, and further 100 ° C. for 60 seconds. Post bake was performed under the conditions of
In this way, a resist pattern was formed.

As a result, a 300 nm line and space was obtained, and the sensitivity at that time was 19 mJ / cm ² . Therefore, it was confirmed that the resist compositions of the examples are chemically amplified positive resist compositions that can be sufficiently applied to KrF excimer lasers.

Claims (5)

A positive resist composition comprising (A) a resin component whose alkali solubility is increased by the action of an acid, and (B) an acid generator component which generates an acid upon irradiation with radiation,
The component (A) is a star polymer including a core part as a central core and an arm part as a polymer chain connected to the central core,
Arm part is
(1) General formula (I):

(Wherein R ¹ is a hydrogen atom or a methyl group)
A repeating unit derived from an alkenylphenol represented by: (2) General Formula (II):

(In the formula, R ² is a hydrogen atom or a methyl group, and R ³ is an acid dissociable, dissolution inhibiting group composed of an alicyclic hydrocarbon group bonded by a tertiary carbon atom)
A polymer chain comprising a repeating unit derived from an acrylate represented by:
The core portion has the general formula (III):

(Wherein R ⁴ and R ⁸ each independently represent a hydrogen atom or a methyl group, R ⁵ , R ⁶ , R ⁹ and R ¹⁰ each independently represent an alkyl group, and R ⁷ represents Represents an alkylene group.)
A positive resist composition comprising a star polymer (A1) containing a repeating unit derived from diacrylate represented by the formula: A positive resist composition comprising (A) a resin component whose alkali solubility is increased by the action of an acid, and (B) an acid generator component which generates an acid upon irradiation with radiation,
The component (A) is a star polymer including a core part as a central core and an arm part as a polymer chain connected to the central core,
Arm part is
(1) General formula (I):

(Wherein R ¹ has the same meaning as described above)
A repeating unit derived from an alkenylphenol represented by:
Formula (IV):

(Wherein R ¹ has the same meaning as described above)
A repeating unit derived from alkenylphenyl represented by:
And (2) general formula (II):

(Wherein R ² and R ³ have the same meaning as above)
A polymer chain comprising a repeating unit derived from an acrylate represented by:
The core portion has the general formula (III):

A positive resist composition comprising a star polymer (A2) containing a structural unit derived from a diacrylate represented by the formula (wherein R ^{4 to} R ¹⁰ have the same meaning as described above). The positive resist composition according to claim 1 or 2, wherein in the general formula (II), R ³ is at least one selected from a 1-alkylcycloalkyl group and a 2-alkyl-2-adamantyl group. Resist composition. The positive resist composition according to any one of claims 1 to 3, wherein the arm portion has the following general formula.

(Wherein R ² has the same meaning as described above)
A positive resist composition comprising a polymer chain containing a repeating unit derived from an acrylate represented by the formula: The positive resist composition according to any one of claims 1 to 4 is coated on a support, pre-baked, selectively exposed, then subjected to PEB (post-exposure heating), and alkali development. And forming a resist pattern.