JP5003548B2 - Polymer for semiconductor resist and radiation-sensitive composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiosensitive composition and a polymer for a semiconductor resist, having a high transparency for a radiation and being excellent in basic physical properties for a resist, such as sensitivity and resolution, as well as in EL, LWR and a minimum collapse size when forming a line pattern. <P>SOLUTION: This polymer for a semiconductor resist contains a formula (1) unit and a formula (2) unit, wherein a content rate of a repeating unit represented by formula (1) is 0.5-10 mol% and a content rate of a repeating unit represented by formula (2) is 50-70 mol% when total repeating units included in the polymer for a semiconductor resist are 100 mol%. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a polymer for semiconductor resist and a radiation-sensitive composition. More specifically, a chemically amplified resist useful for microfabrication using various types of radiation such as deep ultraviolet rays typified by KrF excimer lasers and ArF excimer lasers, X-rays such as synchrotron radiation, and charged particle beams such as electron beams. The present invention relates to a radiation-sensitive composition that can be suitably used as a semiconductor resist polymer.

In the field of microfabrication represented by the manufacture of integrated circuit elements, in order to obtain a higher degree of integration, recently, lithography technology capable of microfabrication at a level of 0.20 μm or less is required. However, in the conventional lithography process, near ultraviolet rays such as i rays are generally used as radiation, and it is said that fine processing at the subquarter micron level is extremely difficult with this near ultraviolet rays. Therefore, in order to enable fine processing at a level of 0.20 μm or less, use of radiation having a shorter wavelength is being studied.
Examples of such short-wavelength radiation include an emission line spectrum of a mercury lamp, far-ultraviolet rays typified by an excimer laser, an X-ray, an electron beam, and the like. ) Or ArF excimer laser (wavelength 193 nm) has been attracting attention.

As a resist suitable for irradiation with such an excimer laser, a component having an acid-dissociable functional group and a component that generates acid upon irradiation with radiation (hereinafter referred to as “exposure”) (hereinafter referred to as “acid generator”). )) And a resist utilizing the chemical amplification effect (hereinafter referred to as “chemically amplified resist”) have been proposed.
As this chemically amplified resist, for example, a resist containing a polymer having a t-butyl ester group of carboxylic acid or a t-butyl carbonate group of phenol and an acid generator has been proposed (see Patent Document 1). ). This resist is an acidic group in which a t-butoxycarbonyl group or a t-butyl carbonate group present in a polymer is dissociated by the action of an acid generated by exposure, and the polymer is composed of a carboxyl group or a phenolic hydroxyl group. As a result, it utilizes the phenomenon that the exposed region of the resist film becomes readily soluble in an alkaline developer.

  By the way, most of the conventional chemically amplified resists are based on phenolic polymers. However, in the case of such polymers, if far ultraviolet rays are used as radiation, it is caused by the aromatic ring in the polymer. Since far ultraviolet rays are absorbed, the exposed far ultraviolet rays cannot sufficiently reach the lower layer of the resist film. Therefore, the exposure amount is large in the upper layer part of the resist film and smaller in the lower layer part, and the pattern profile of the resist pattern after development is thin at the upper part and becomes a trapezoidal shape thicker toward the lower part, and sufficient resolution can be obtained. There was no problem. In addition, when the pattern profile after development has a trapezoidal shape, a desired dimensional accuracy cannot be achieved in the next process, that is, etching or ion implantation, which is a problem. In addition, if the upper side of the pattern profile and the side walls are not rectangular, the resist disappears at a high rate due to dry etching, which makes it difficult to control the etching conditions.

On the other hand, the resist pattern profile can be improved by increasing the radiation transmittance of the resist film. For example, a (meth) acrylate polymer represented by polymethyl methacrylate is highly transparent to far ultraviolet rays and is a very preferable polymer from the viewpoint of radiation transmittance. For example, a methacrylate polymer is used. A chemically amplified resist has been proposed (see Patent Document 2).
However, although this composition is excellent in terms of microfabrication performance, it does not have an aromatic ring and thus has a drawback of low dry etching resistance. In this case as well, it is difficult to perform highly accurate etching. Therefore, it cannot be said that it has both transparency to radiation and dry etching resistance.

In addition, as a method for improving dry etching resistance without impairing transparency to radiation for a chemically amplified resist, a method of introducing an aliphatic ring instead of an aromatic ring into a polymer component in the resist For example, a chemically amplified resist using a (meth) acrylate polymer having an aliphatic ring has been proposed (see Patent Document 3).
In this resist, as the acid dissociable functional group of the polymer component, a group that is relatively easily dissociated by a conventional acid (for example, an acetal functional group such as a tetrahydropyranyl group) or a group that is relatively difficult to dissociate by an acid ( For example, t-butyl functional groups such as t-butyl ester groups and t-butyl carbonate groups) are used. However, in the case of the former polymer component having an acid-dissociable functional group, the basic physical properties of the resist, particularly the sensitivity and pattern profile, are good, but there are difficulties in storage stability as a composition. The latter polymer component having an acid-dissociable functional group, on the other hand, has good storage stability, but has the disadvantage that the basic physical properties of the resist, particularly the sensitivity and pattern profile, are impaired. Furthermore, since an aliphatic ring is introduced into the polymer component in the resist, the polymer itself has a very high hydrophobicity, resulting in insufficient adhesion to the substrate.

  In addition, when a resist pattern is formed using a chemically amplified resist, heat treatment is usually performed after exposure in order to promote dissociation of the acid-dissociable functional group. Normally, when the heating temperature is changed, the resist pattern is changed. It is inevitable that the line width of the line fluctuates to some extent. However, reflecting the recent miniaturization of integrated circuit elements, development of a resist having a small line width variation (that is, temperature dependency) with respect to a change in heating temperature after exposure has been strongly demanded. .

Furthermore, in chemically amplified resists, it is known that acid generators have a great influence on the function as a resist. Today, the reason is that the quantum yield of acid generation by exposure is high and the sensitivity is high. Therefore, onium salt compounds are widely used as acid generators for chemically amplified resists. As this onium salt compound, for example, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium naphthalenesulfonate, cyclohexylmethyl (2-oxocyclohexyl) sulfonium trifluoromethanesulfonate, and the like are used.
However, these conventional onium salt compounds are generally unsatisfactory in terms of sensitivity, and even when the sensitivity is relatively high, it is still not sufficient in terms of resist performance that combines resolution, pattern profile, and the like.
Under such circumstances, from the viewpoint of technological development that can cope with the progress of miniaturization in integrated circuit elements, it is adaptable to short-wavelength radiation typified by far ultraviolet rays, has high transparency to radiation, and is sensitive. There is a strong demand for chemically amplified resists that are excellent in basic physical properties as resists such as resolution and pattern profile.

JP 59-45439 A JP-A-4-226461 JP-A-7-234511

  The present invention has been made in view of the above circumstances, has high transparency to radiation, is excellent in basic physical properties as a resist such as sensitivity and resolution, and has an EL (exposure margin) when forming a line pattern, An object of the present invention is to provide a radiation sensitive composition excellent in LWR (Line Width Roughness, variation in line width generated when a pattern is formed) and a minimum collapse dimension (fall) and a polymer for semiconductor resist.

〔一般式（１）において、Ｒ^１及びＲ^２は、それぞれ、水素原子又は炭素数１〜４の置換基を有してもよいアルキル基を表す。〕

〔一般式（２）において、Ｒ^３及びＲ^４は、それぞれ、水素原子又は炭素数１〜４の置換基を有してもよいアルキル基を表す。〕
［２］ゲルパーミエーションクロマトグラフィ法により測定される重量平均分子量が、３０００〜５０００である前記［１］に記載の半導体レジスト用重合体。
［３］前記重合体は、重合に用いられる単量体の総量を１００ｍｏｌ％とした場合に、重合開始剤としてアゾビスイソブチロニトリルを６〜１５ｍｏｌ％用いて重合されたものである前記［１］又は［２］に記載の半導体レジスト用重合体。
［４］（Ａ）前記［１］乃至［３］のいずれかに記載の半導体レジスト用重合体と、（Ｂ）感放射線性酸発生剤と、（Ｃ）溶剤と、を含有することを特徴とする感放射線性組成物。 The present invention is as follows.
[1] A polymer for semiconductor resist containing a repeating unit represented by the following general formula (1) and a repeating unit represented by the following general formula (2), wherein the polymer for semiconductor resist: When the total repeating unit contained is 100 mol%, the content ratio of the repeating unit represented by the following general formula (1) is 0.5 to 10 mol%, and the repeating is represented by the following general formula (2) A polymer for semiconductor resist, wherein the unit content is 50 to 70 mol%.

[In General formula (1), R < ¹ > and R < ² > represents the alkyl group which may have a hydrogen atom or a C1-C4 substituent, respectively. ]

In [general formula (2), R ³ and R ⁴ each represent a hydrogen atom or an alkyl group which may have a substituent group having 1 to 4 carbon atoms. ]
[2] The polymer for semiconductor resist according to [1], wherein the weight average molecular weight measured by a gel permeation chromatography method is 3000 to 5000.
[3] The polymer is polymerized using 6 to 15 mol% of azobisisobutyronitrile as a polymerization initiator when the total amount of monomers used for polymerization is 100 mol%. The polymer for semiconductor resists according to [1] or [2].
[4] A polymer containing a semiconductor resist according to any one of [1] to [3], (B) a radiation-sensitive acid generator, and (C) a solvent. A radiation-sensitive composition.

  The radiation-sensitive composition of the present invention is a chemically amplified resist that is sensitive to actinic radiation, particularly far-ultraviolet rays represented by ArF excimer laser (wavelength 193 nm), and has high transparency, resolution, sensitivity, etc. to radiation. In addition, the pattern shape is good, and particularly in the line pattern (L / S pattern), the LWR is very good. Furthermore, the minimum collapse size (falling) is good, and it can be used very suitably for the manufacture of semiconductor devices that are expected to be miniaturized in the future.

  Hereinafter, the present invention will be described in detail. In the present specification, “(meth) acryl” means acrylic and methacrylic. Further, “(meth) acrylate” means acrylate and methacrylate.

[1] Polymer for semiconductor resist Polymer for semiconductor resist of the present invention [hereinafter also referred to as “polymer (A)”. ] Is an alkali-insoluble or alkali-insoluble polymer that becomes alkali-soluble by the action of an acid, the repeating unit represented by the following general formula (1), and the following general formula (2) The repeating unit represented by these is contained. The term “alkali insoluble or alkali insoluble” as used herein refers to the alkali development conditions employed when a resist pattern is formed from a resist film formed from a radiation-sensitive composition containing the polymer (A). Thus, when a film using only the polymer (A) is developed instead of the resist film, it means that 50% or more of the initial film thickness of the film remains after development.

〔一般式（１）において、Ｒ^１及びＲ^２は、それぞれ、水素原子又は炭素数１〜４の置換基を有してもよいアルキル基を表す。〕

[In General formula (1), R < ¹ > and R < ² > represents the alkyl group which may have a hydrogen atom or a C1-C4 substituent, respectively. ]

〔一般式（２）において、Ｒ^３及びＲ^４は、それぞれ、水素原子又は炭素数１〜４の置換基を有してもよいアルキル基を表す。〕

In [general formula (2), R ³ and R ⁴ each represent a hydrogen atom or an alkyl group which may have a substituent group having 1 to 4 carbon atoms. ]

Examples of the alkyl group which may have a substituent of carbon 1 to 4 of R ¹ in the general formula (1) include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, and an n-butyl group. , 2-methylpropyl group, 1-methylpropyl group, t-butyl group and the like.
In addition, as the alkyl group which may have a substituent of carbon 1 to 4 of R ² in the general formula (1), the above description of R ¹ can be applied as it is. R ¹ and R ² may be the same or different.

  Specific examples of the monomer that gives the repeating unit (1) include a compound (1-1) represented by the following formula.

Examples of the alkyl group that may have a substituent of carbon 1 to 4 of R ³ in the general formula (2) include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, and an n-butyl group. , 2-methylpropyl group, 1-methylpropyl group, t-butyl group and the like.
Moreover, as an alkyl group which may have a substituent of carbon 1-4 of R ⁴ in the general formula (2), the description of R ³ described above can be applied as it is. R ³ and R ⁴ may be the same or different.

  Specific examples of the monomer that gives the repeating unit (2) include a compound (2-1) represented by the following formula.

The polymer (A) may further contain other repeating units in addition to the repeating units (1) and (2).
As this other repeating unit, for example, a repeating unit having a lactone skeleton [hereinafter also referred to as “repeating unit (3)”. And the like.

Examples of the repeating unit (3) having a lactone skeleton include (meth) acrylic acid-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] non-2-yl ester, (Meth) acrylic acid-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] non-2-yl ester, (meth) acrylic acid-5-oxo-4- Oxa-tricyclo [5.2.1.0 ^3,8 ] dec-2-yl ester, (meth) acrylic acid-10-methoxycarbonyl-5-oxo-4-oxa-tricyclo [5.2.1.0 ^3,8 ] Nona-2-yl ester, (meth) acrylic acid-6-oxo-7-oxa-bicyclo [3.2.1] oct-2-yl ester, (meth) acrylic acid-4-methoxycarbonyl -6 So-7-oxa-bicyclo [3.2.1] oct-2-yl ester, (meth) acrylic acid-7-oxo-8-oxa-bicyclo [3.3.1] oct-2-yl ester, (Meth) acrylic acid-4-methoxycarbonyl-7-oxo-8-oxa-bicyclo [3.3.1] oct-2-yl ester, (meth) acrylic acid-2-oxotetrahydropyran-4-yl ester , (Meth) acrylic acid-4-methyl-2-oxotetrahydropyran-4-yl ester, (meth) acrylic acid-4-ethyl-2-oxotetrahydropyran-4-yl ester, (meth) acrylic acid-4 -Propyl-2-oxotetrahydropyran-4-yl ester, (meth) acrylic acid-5-oxotetrahydrofuran-3-yl ester, (meth) acrylic Acid-2,2-dimethyl-5-oxotetrahydrofuran-3-yl ester, (meth) acrylic acid-4,4-dimethyl-5-oxotetrahydrofuran-3-yl ester, (meth) acrylic acid-2-oxotetrahydrofuran -3-yl ester, (meth) acrylic acid-4,4-dimethyl-2-oxotetrahydrofuran-3-yl ester, (meth) acrylic acid-5,5-dimethyl-2-oxotetrahydrofuran-3-yl ester, (Meth) acrylic acid-2-oxotetrahydrofuran-3-yl ester, (meth) acrylic acid-5-oxotetrahydrofuran-2-ylmethyl ester, (meth) acrylic acid-3,3-dimethyl-5-oxotetrahydrofuran- 2-ylmethyl ester, (meth) acrylic acid-4,4-dimethyl Polymerizable unsaturated bond such as 5-oxo-tetrahydrofuran-2-yl methyl ester may be mentioned units cleaved, and those represented by the following formula formula (3).

〔前記一般式（３）において、Ｒ^５は水素原子、メチル基、又はトリフルオロメチル基を示し、Ｒ^６は炭素数１〜１２の直鎖状若しくは分岐状のアルキル基、シクロアルキル基、炭素数１〜１２のアルキルカルボニル基、又は炭素数１〜１２のヒドロキシアルキル基を示す。〕

[In the general formula (3), R ⁵ represents a hydrogen atom, a methyl group, or a trifluoromethyl group, and R ⁶ represents a linear or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, a carbon A C1-C12 alkylcarbonyl group or a C1-C12 hydroxyalkyl group is shown. ]

Examples of the linear or branched alkyl group having 1 to 12 carbon atoms in R ⁶ of the general formula (3) include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, and an n-butyl group. 2-methylpropyl group, 1-methylpropyl group, t-butyl group, n-pentyl group, neopentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group , N-decyl group, n-undecyl group, n-dodecyl group and the like.

Examples of the alkylcarbonyl group having 1 to 12 carbon atoms in R ⁶ include a methylcarbonyl group, an ethylcarbonyl group, an n-propylcarbonyl group, an i-propylcarbonyl group, an n-butylcarbonyl group, and a t-butylcarbonyl group. Group, n-pentylcarbonyl group, n-hexylcarbonyl group, n-heptylcarbonyl group and the like.

Furthermore, examples of the hydroxyalkyl group having 1 to 12 carbon atoms in R ⁶ include a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, a hydroxybutyl group, a hydroxypentyl group, a hydroxyhexyl group, and a hydroxyheptyl group. be able to.

  Furthermore, as the other repeating unit, a repeating unit represented by the following general formula (4) [hereinafter referred to as “repeating unit (4)”. ] Or the following general formula (5) [hereinafter referred to as “repeating unit (5)”. And the like.

〔一般式（４）において、Ｒ^７は水素原子、炭素数１〜４のアルキル基、トリフルオロメチル基、又はヒドロキシメチル基を示し、Ｒ^８は２価の有機基を示す。〕

[In General Formula (4), R ⁷ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a trifluoromethyl group, or a hydroxymethyl group, and R ⁸ represents a divalent organic group. ]

〔一般式（５）において、Ｒ^９は水素原子又はメチル基を示し、Ｘは単結合又は炭素数１〜３の２価の有機基を示し、Ｚは相互に独立に単結合又は炭素数１〜３の２価の有機基を示し、Ｒ^１０は相互に独立に水素原子、ヒドロキシル基、シアノ基、又はＣＯＯＲ^１１基を示す。〕

[In General Formula (5), R ⁹ represents a hydrogen atom or a methyl group, X represents a single bond or a divalent organic group having 1 to 3 carbon atoms, and Z represents a single bond or 1 carbon atom independently of each other. ˜3 represents a divalent organic group, and R ¹⁰ independently represents a hydrogen atom, a hydroxyl group, a cyano group, or a COOR ¹¹ group. ]

Examples of the alkyl group having 1 to 4 carbon atoms in R ⁷ of the general formula (4) include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a 2-methylpropyl group, Examples thereof include alkyl groups such as 1-methylpropyl group and t-butyl group.
In addition, examples of the divalent organic group represented by R ⁸ in the general formula (4) include a divalent hydrocarbon group, an alkylene glycol group, and an alkylene ester group. Among these, a divalent monovalent hydrogen group is preferable, and a chain or cyclic divalent hydrocarbon group is more preferable.

Preferred as R ⁸ is a methylene group, an ethylene group, a propylene group such as a 1,3-propylene group or a 1,2-propylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group, an octamethylene group. , Nonamethylene group, decamethylene group, undecamethylene group, dodecamethylene group, tridecamethylene group, tetradecamethylene group, pentadecamethylene group, hexadecamethylene group, heptacamethylene group, octadecamethylene group, nonacamethylene group , Insalene group, 1-methyl-1,3-propylene group, 2-methyl-1,3-propylene group, 2-methyl-1,2-propylene group, 1-methyl-1,4-butylene group, 2-methyl -1,4-butylene group, methylidene group, ethylidene group, propylidene group, or 2-propylidene group Saturated chain hydrocarbon group such as den group, cyclobutylene group such as 1,3-cyclobutylene group, cyclopentylene group such as 1,3-cyclopentylene group, cyclohexylene such as 1,4-cyclohexylene group Group, monocyclic hydrocarbon ring group such as cycloalkylene group having 3 to 10 carbon atoms such as cyclooctylene group such as 1,5-cyclooctylene group, 1,4-norbornylene group or 2,5-norbornylene group Such as norbornylene group, 1,5-adamantylene group, 2,6-adamantylene group, etc. bridged cyclic hydrocarbon ring such as 2-4 cyclic hydrocarbon ring group having 4-30 carbon atoms Groups and the like.

In particular, when R ⁸ contains a divalent aliphatic cyclic hydrocarbon group, an alkylene having 1 to 4 carbon atoms as a spacer between the bistrifluoromethyl-hydroxy-methyl group and the aliphatic cyclic hydrocarbon group. It is preferred to insert a group.
R ⁸ is preferably a hydrocarbon group containing a 2,5-norbornylene group, a 1,2-ethylene group, or a propylene group.

Examples of the divalent organic group having 1 to 3 carbon atoms in X and Z in the general formula (5) include a methylene group, an ethylene group, and a propylene group.
Further, ^{R 11} of COOR ¹¹ group in ^{R 10} in the general formula (5) is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, or an alicyclic alkyl having 3 to 20 carbon atoms Represents a group.
Examples of the linear or branched alkyl group having 1 to 4 carbon atoms in R ¹¹ include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a 2-methylpropyl group, 1 -A methylpropyl group and a t-butyl group can be mentioned.
Examples of the alicyclic alkyl group having 3 to 20 carbon atoms in R ¹¹ include —C _n H _2n— such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, and cyclooctyl group. ₁ (n is an integer of 3 to 20); a bicyclo [2.2.1] heptyl group, a tricyclo [5.2.1.0 ^2,6 ] decyl group, a tetracyclo [6.2 ^.1,3,6 . 0 ^2,7 ] dodecanyl group, adamantyl group, and other polycyclic alicyclic alkyl groups. Furthermore, groups obtained by substituting a part of these cycloalkyl groups or polycyclic alicyclic alkyl groups with at least one of linear, branched, or cyclic alkyl groups are exemplified.
In addition, when at least one of the three R ¹⁰ in the general formula (5) is other than a hydrogen atom and X is a single bond, at least one of the three Z has a carbon number of 1 to 1. 3 is preferably the above divalent organic group.

Furthermore, as the other repeating unit, (meth) acrylic acid-bicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-bicyclo [2.2.2] oct-2-yl Ester, (meth) acrylic acid-tricyclo [5.2.1.0 ^2,6 ] dec-7-yl ester, (meth) acrylic acid-tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] dodec-9-yl ester, (meth) acrylic acid-tricyclo [3.3.1.1 ^3,7 ] dec-1-yl ester, (meth) acrylic acid-tricyclo [3.3. ^1.1,7 ] units having a polymerizable unsaturated bond cleaved such as deca-2-yl ester.
In addition, these other repeating units may contain only 1 type and may contain 2 or more types.

Moreover, as a specific polymer (A), what is comprised by the combination of the repeating unit shown below etc. can be mentioned, for example.
In addition, R < ¹² > -R < ¹⁴ > in each following repeating unit shows a hydrogen atom or a methyl group, respectively.

The content ratio of the repeating unit (1) in the polymer (A) is 0.5 to 10 mol% when the total of all repeating units contained in the polymer (A) is 100 mol%, preferably It is 3-10 mol%, More preferably, it is 5-9 mol%. When the content ratio of the repeating unit (1) is less than 0.5 mol%, the resist pattern shape such as LWR may be insufficient. On the other hand, when it exceeds 10 mol%, EL and the minimum collapse dimension (fall) may be insufficient.
The content of the repeating unit (2) is 50 to 70 mol%, preferably 50 to 65 mol%, more preferably, when the total of all repeating units contained in the polymer (A) is 100 mol%. It is 50-60 mol%. When the content ratio of the repeating unit (2) is less than 50 mol%, the minimum collapse size and resolution may be insufficient. On the other hand, when it exceeds 70 mol%, the adhesion to the substrate may be insufficient.
The content of the other repeating units is preferably 20 to 49.5 mol%, more preferably 30 when the total of all the repeating units contained in the polymer (A) is 100 mol%. It is -49.5 mol%, More preferably, it is 35-49.5 mol%. When the content rate of this other repeating unit is 20-49.5 mol%, it is preferable from viewpoints of resolution, adhesiveness, etc.

The weight average molecular weight in terms of polystyrene (hereinafter referred to as “Mw”) measured by gel permeation chromatography (GPC) of the polymer (A) is usually 1000 to 5000, preferably 2000 to 5000, and more preferably 3000 to 5000. 5000. When this Mw is less than 1000, the heat resistance as a resist may be reduced. On the other hand, when it exceeds 5000, LWR and the like may be lowered.
Moreover, the ratio (Mw / Mn) of Mw of the polymer (A) and polystyrene-equivalent number average molecular weight (hereinafter referred to as “Mn”) by GPC is usually 1 to 5, preferably 1 to 3.

  The polymer (A) is prepared, for example, by polymerizing a monomer corresponding to each repeating unit in a suitable solvent in the presence of a chain transfer agent, if necessary, using a polymerization initiator. be able to.

Examples of the polymerization initiator include radical polymerization initiators such as hydroperoxides, dialkyl peroxides, diacyl peroxides, and azo compounds. Among these, azo compounds are preferable, and azobisisobutyronitrile is particularly preferable.
When the azobisisobutyronitrile is used as a polymerization initiator, the blending amount of azobisisobutyronitrile is 6 to 15 mol% when the total amount of monomers used for the polymerization is 100 mol%. More preferably, it is 7-14 mol%, More preferably, it is 8-13 mol%. A blending amount of 6 to 15 mol% is preferable because the balance between LWR and collapse is good.

  Examples of the solvent used for the polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; cyclohexane, cycloheptane, cyclooctane, decalin, Cycloalkanes such as norbornane; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene; halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, chlorobenzene; ethyl acetate Saturated carboxylic acid esters such as n-butyl acetate, i-butyl acetate, methyl propionate, propylene glycol monomethyl ether acetate; alkyl lactones such as γ-butyrolactone; tetrahydrofuran, dimethoxyethanes, diethoxyethanes, etc. Eru acids; can be exemplified alcohols such as 2-propanol, propylene glycol monomethyl ether; cycloalkyl ketones such as cyclohexanone; 2-butanone, 2-heptanone, alkyl ketones such as methyl isobutyl ketone. These solvents may be used alone or in combination of two or more.

  The reaction temperature in the polymerization is usually 40 to 120 ° C, preferably 50 to 100 ° C. The reaction time in the polymerization is usually 1 to 48 hours, preferably 1 to 24 hours.

  The polymer (A) preferably has few impurities such as halogen and metal, and the residual monomer and oligomer components are not more than predetermined values, for example, 0.1% by mass or less by HPLC. preferable. Thereby, the sensitivity, resolution, process stability, pattern shape, etc. as a resist can be further improved, and a resist free from changes over time such as foreign matter in liquid or sensitivity can be provided.

Moreover, as a purification method of the said polymer (A), the following method is mentioned, for example.
As a method for removing impurities such as metals, a metal is adsorbed on the polymer solution using a zeta potential filter, or the metal solution is chelated by washing the polymer solution with an acidic aqueous solution such as oxalic acid or sulfonic acid. And the like.
Methods for removing residual monomers and oligomer components below the specified value include washing with water and a liquid-liquid extraction method that removes residual monomers and oligomer components by combining appropriate solvents, as well as extracting and removing only those with a specific molecular weight or less. Purification method in solution state such as external filtration, reprecipitation method that removes residual monomers by coagulating the polymer in the poor solvent by dropping the polymer solution into the poor solvent, or filtered polymer There is a purification method in a solid state such as washing the slurry with a poor solvent. These methods can be used in combination.
The poor solvent used in the reprecipitation method is appropriately selected depending on the physical properties of the polymer to be purified.

[2] Radiation sensitive composition The radiation sensitive composition of the present invention is characterized by containing a polymer, a radiation sensitive acid generator, and a solvent.

(2-1) Polymer The polymer is the above-described resist polymer for semiconductors [polymer (A)] of the present invention, and the above description can be applied as it is.
The radiation-sensitive composition of the present invention may contain only one type of the polymer (A), or may contain two or more types.

(2-2) Radiation sensitive acid generator The radiation sensitive acid generator [hereinafter also referred to as “acid generator (B)”. ] Generates an acid upon exposure and functions as a photoacid generator. This acid generator uses an acid generated by exposure to dissociate an acid-dissociable group present in the polymer (A) contained in the radiation-sensitive composition (eliminate a protecting group), and thereby generate heavy ions. The coalescence (A) is alkali-soluble. As a result, the exposed portion of the resist film becomes readily soluble in an alkaline developer, thereby forming a positive resist pattern.

  As said acid generator (B), the compound represented by following General formula (6) can be mentioned, for example.

K in the said General formula (6) is an integer of 0-2.
R ¹⁵ is a hydrogen atom, a fluorine atom, a hydroxyl group, a linear or branched alkyl group having 1 to 10 carbon atoms, a linear or branched alkoxyl group having 1 to 10 carbon atoms, or a carbon number 2-11 linear or branched alkoxycarbonyl groups are shown.
Further, R ¹⁶ is a linear or branched alkyl group having 1 to 10 carbon atoms, a linear or branched alkoxyl group having 1 to 10 carbon atoms, a linear or branched chain having 1 to 10 carbon atoms, or A cyclic alkanesulfonyl group is shown. In addition, r is an integer of 0-10.
R ¹⁷ independently represents a linear or branched alkyl group having 1 to 10 carbon atoms, an optionally substituted phenyl group, or an optionally substituted naphthyl group, or 2 a divalent group number of R ¹⁷ is 2 to 10 carbon atoms bound formed with each other. This divalent group may be substituted.
Further, X ^- is the _{^{formula; R 18 C n F 2n SO}} 3 -, or ^R 18 SO ₃ ^- (In the ^{formula, R 18} is a hydrogen atom, a fluorine atom or an optionally substituted C 1 -C 12 carbon A hydrocarbon group, and n is an integer of 1 to 10.) or an anion represented by the following general formula (7-1) or (7-2).

R ¹⁹ in the general formulas (7-1) and (7-2) independently represents an alkyl group containing a linear or branched fluorine atom having 1 to 10 carbon atoms, or 2 R ¹⁹ is a divalent group containing a fluorine atom having 2 to 10 carbon atoms formed by bonding to each other. This divalent group may be substituted.

Examples of the linear or branched alkyl group having 1 to 10 carbon atoms in R ¹⁵ , R ¹⁶ and R ¹⁷ in the general formula (6) include, for example, a methyl group, an ethyl group, an n-propyl group, i, -Propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group, n-pentyl group, neopentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2 -An ethylhexyl group, n-nonyl group, n-decyl group etc. can be mentioned. Of these alkyl groups, a methyl group, an ethyl group, an n-butyl group, a t-butyl group, and the like are preferable.

^Examples of the linear or branched alkoxy group having 1 to 10 carbon atoms in ^{R 15} and ^{R 16,} for example, respectively, a methoxy group, an ethoxy group, n- propoxy group, i- propoxy, n- butoxy group 2-methylpropoxy group, 1-methylpropoxy group, t-butoxy group, n-pentyloxy group, neopentyloxy group, n-hexyloxy group, n-heptyloxy group, n-octyloxy group, 2-ethylhexyl An oxy group, n-nonyloxy group, n-decyloxy group, etc. can be mentioned. Of these alkoxyl groups, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, and the like are preferable.

Examples of the linear or branched alkoxycarbonyl group having 2 to 11 carbon atoms of R ¹⁵ include, for example, a methoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, an i-propoxycarbonyl group, and an n-butoxycarbonyl group. Group, 2-methylpropoxycarbonyl group, 1-methylpropoxycarbonyl group, t-butoxycarbonyl group, n-pentyloxycarbonyl group, neopentyloxycarbonyl group, n-hexyloxycarbonyl group, n-heptyloxycarbonyl group, n -An octyloxycarbonyl group, 2-ethylhexyloxycarbonyl group, n-nonyloxycarbonyl group, n-decyloxycarbonyl group, etc. can be mentioned. Of these alkoxycarbonyl groups, a methoxycarbonyl group, an ethoxycarbonyl group, an n-butoxycarbonyl group, and the like are preferable.

Examples of the linear, branched or cyclic alkanesulfonyl group having 1 to 10 carbon atoms of R ¹⁶ include a methanesulfonyl group, an ethanesulfonyl group, an n-propanesulfonyl group, an n-butanesulfonyl group, and a tert- Butanesulfonyl group, n-pentanesulfonyl group, neopentanesulfonyl group, n-hexanesulfonyl group, n-heptanesulfonyl group, n-octanesulfonyl group, 2-ethylhexanesulfonyl group n-nonanesulfonyl group, n-decanesulfonyl group , Cyclopentanesulfonyl group, cyclohexanesulfonyl group and the like. Of these alkanesulfonyl groups, a methanesulfonyl group, an ethanesulfonyl group, an n-propanesulfonyl group, an n-butanesulfonyl group, a cyclopentanesulfonyl group, a cyclohexanesulfonyl group, and the like are preferable.

  Moreover, r in the said General formula (6) is an integer of 0-10, and it is preferable that it is 0-2.

Examples of the optionally substituted phenyl group in R ¹⁷ of the general formula (6) include a phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 2,3-dimethylphenyl group, 2 , 4-dimethylphenyl group, 2,5-dimethylphenyl group, 2,6-dimethylphenyl group, 3,4-dimethylphenyl group, 3,5-dimethylphenyl group, 2,4,6-trimethylphenyl group, 4 -Substituted with phenyl groups such as ethylphenyl group, 4-t-butylphenyl group, 4-cyclohexylphenyl group, 4-fluorophenyl group, or linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms. And a phenyl group (hereinafter referred to as “alkyl-substituted phenyl group”). Furthermore, these phenyl groups or alkyl-substituted phenyl groups are substituted with at least one of hydroxyl group, carboxyl group, cyano group, nitro group, alkoxyl group, alkoxyalkyl group, alkoxycarbonyl group, alkoxycarbonyloxy group, and the like. And the like.

Among the substituents for the phenyl group and the alkyl-substituted phenyl group, the alkoxyl group includes, for example, methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, 2-methylpropoxy group, 1 -A linear, branched or cyclic alkoxyl group having 1 to 20 carbon atoms such as a methylpropoxy group, a t-butoxy group, a cyclopentyloxy group and a cyclohexyloxy group.
Among the substituents, examples of the alkoxyalkyl group include a methoxymethyl group, an ethoxymethyl group, a 1-methoxyethyl group, a 2-methoxyethyl group, a 1-ethoxyethyl group, and a 2-ethoxyethyl group. Examples thereof include linear, branched or cyclic alkoxyalkyl groups having 2 to 21 carbon atoms.

Furthermore, among the substituents, examples of the alkoxycarbonyl group include methoxycarbonyl group, ethoxycarbonyl group, n-propoxycarbonyl group, i-propoxycarbonyl group, n-butoxycarbonyl group, 2-methylpropoxycarbonyl group, Examples thereof include linear, branched or cyclic alkoxycarbonyl groups having 2 to 21 carbon atoms such as 1-methylpropoxycarbonyl group, t-butoxycarbonyl group, cyclopentyloxycarbonyl group and cyclohexyloxycarbonyl.
Of the substituents, the alkoxycarbonyloxy group includes, for example, a methoxycarbonyloxy group, an ethoxycarbonyloxy group, an n-propoxycarbonyloxy group, an i-propoxycarbonyloxy group, an n-butoxycarbonyloxy group, t Examples thereof include linear, branched or cyclic alkoxycarbonyloxy groups having 2 to 21 carbon atoms such as butoxycarbonyloxy group, cyclopentyloxycarbonyl group, cyclohexyloxycarbonyl and the like.

In particular, among the optionally substituted phenyl groups represented by R ¹⁷ in the general formula (6), phenyl group, 4-cyclohexylphenyl group, 4-t-butylphenyl group, 4-methoxyphenyl group, 4-t- A butoxyphenyl group and the like are preferable.

Examples of the optionally substituted naphthyl group for R ¹⁷ include 1-naphthyl group, 2-methyl-1-naphthyl group, 3-methyl-1-naphthyl group, 4-methyl-1-naphthyl group, 4-methyl-1-naphthyl group, 5-methyl-1-naphthyl group, 6-methyl-1-naphthyl group, 7-methyl-1-naphthyl group, 8-methyl-1-naphthyl group, 2,3-dimethyl -1-naphthyl group, 2,4-dimethyl-1-naphthyl group, 2,5-dimethyl-1-naphthyl group, 2,6-dimethyl-1-naphthyl group, 2,7-dimethyl-1-naphthyl group, 2,8-dimethyl-1-naphthyl group, 3,4-dimethyl-1-naphthyl group, 3,5-dimethyl-1-naphthyl group, 3,6-dimethyl-1-naphthyl group, 3,7-dimethyl- 1-naphthyl group, 3,8-dimethyl- 1-naphthyl group, 4,5-dimethyl-1-naphthyl group, 5,8-dimethyl-1-naphthyl group, 4-ethyl-1-naphthyl group, 2-naphthyl group, 1-methyl-2-naphthyl group, 3 A naphthyl group substituted with a naphthyl group such as a methyl-2-naphthyl group or 4-methyl-2-naphthyl group or a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms (hereinafter referred to as “alkyl A substituted naphthyl group ”) and the like. Furthermore, these naphthyl groups or alkyl-substituted naphthyl groups are substituted with at least one of hydroxyl group, carboxyl group, cyano group, nitro group, alkoxyl group, alkoxyalkyl group, alkoxycarbonyl group, alkoxycarbonyloxy group and the like. And the like.
In addition, about the substituent with respect to the said naphthyl group and an alkyl substituted naphthyl group, the description of the substituent with respect to the above-mentioned phenyl group and an alkyl substituted phenyl group is applicable as it is.

In particular, among the optionally substituted naphthyl groups of R ¹⁷ in the general formula (6), a 1-naphthyl group, a 1- (4-methoxynaphthyl) group, a 1- (4-ethoxynaphthyl) group, 1- (4-n-propoxynaphthyl) group, 1- (4-n-butoxynaphthyl) group, 2- (7-methoxynaphthyl) group, 2- (7-ethoxynaphthyl) group, 2- (7-n-propoxy) A naphthyl) group, a 2- (7-n-butoxynaphthyl) group, and the like are preferable.

In addition, the divalent group having 2 to 10 carbon atoms formed by bonding two R ¹⁷ to each other, together with the sulfur atom in the general formula (6), a 5-membered or 6-membered ring, particularly preferably 5 Groups that form member rings (ie, tetrahydrothiophene rings) are preferred. Further, this divalent group may be substituted. Examples of the substituent at this time include, for example, the hydroxyl group, carboxyl group, cyano group, nitro group, alkoxyl group, alkoxyalkyl group, alkoxycarbonyl group, alkoxy group exemplified as the substituent for the above-mentioned phenyl group or alkyl-substituted phenyl group. A carbonyloxy group etc. can be mentioned.

R ¹⁷ in the general formula (6) is a methyl group, an ethyl group, a phenyl group, a 4-methoxyphenyl group, a 1-naphthyl group, or two R ¹⁷ 's bonded to each other among the above-mentioned examples. A divalent group that forms a tetrahydrothiophene ring structure with a sulfur atom is preferred.

  Preferred cation sites of the general formula (6) include triphenylsulfonium cation, tri-1-naphthylsulfonium cation, tri-tert-butylphenylsulfonium cation, 4-fluorophenyl-diphenylsulfonium cation, and di-4-fluorophenyl. -Phenylsulfonium cation, tri-4-fluorophenylsulfonium cation, 4-cyclohexylphenyl-diphenylsulfonium cation, 4-methanesulfonylphenyl-diphenylsulfonium cation, 4-cyclohexanesulfonyl-diphenylsulfonium cation, 1-naphthyldimethylsulfonium cation, 1 -Naphthyl diethylsulfonium cation, 1- (4-hydroxynaphthalen-1-yl) dimethylsulfonium kathi 1- (4-methylnaphthalen-1-yl) dimethylsulfonium cation, 1- (4-methylnaphthalen-1-yl) diethylsulfonium cation, 1- (4-cyanonaphthalen-1-yl) dimethylsulfonium cation, 1- (4-cyanonaphthalen-1-yl) diethylsulfonium cation, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium cation, 1- (4-methoxynaphthalen-1-yl) tetrahydrothio Phenium cation, 1- (4-ethoxynaphthalen-1-yl) tetrahydrothiophenium cation, 1- (4-n-propoxynaphthalen-1-yl) tetrahydrothiophenium cation, 1- (4-n-butoxy Naphthalen-1-yl) tetrahydrothiophenium Thione, 2- (7-methoxynaphthalen-2-yl) tetrahydrothiophenium cation, 2- (7-ethoxynaphthalen-2-yl) tetrahydrothiophenium cation, 2- (7-n-propoxynaphthalene-2- Yl) tetrahydrothiophenium cation, 2- (7-n-butoxynaphthalen-2-yl) tetrahydrothiophenium cation, and the like.

The C _n F _2n — group in the anion represented by R ¹⁸ C _n F _2n SO ₃ ^— represented by X ⁻ in the general formula (6) is a perfluoroalkylene group having n carbon atoms. May be linear or branched. N is preferably 1, 2, 4 or 8.
^{_{Also, R 18 C n F 2n SO}} 3 - and ^R 18 SO ₃ ^- as a hydrocarbon group having 1 to 12 carbon atoms which may be substituted in ^{R 18} of each anion represented, carbon 1 to 12 An alkyl group, a cycloalkyl group, and a bridged alicyclic hydrocarbon group are preferred. Specifically, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group, n-pentyl group, neopentyl group N-hexyl group, cyclohexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, norbornyl group, norbornylmethyl group, hydroxynorbornyl group, adamantyl group Etc.

Examples of the alkyl group containing a linear or branched fluorine atom having 1 to 10 carbon atoms in R ¹⁹ of the general formulas (7-1) and (7-2) include a trifluoromethyl group and a pentafluoro group. Examples thereof include an ethyl group, a heptafluoropropyl group, a nonafluorobutyl group, a dodecafluoropentyl group, and a perfluorooctyl group.

In the general formulas (7-1) and (7-2), the group containing a divalent fluorine atom having 2 to 10 carbon atoms formed by bonding two R ¹⁹ to each other is tetrafluoro. Examples thereof include an ethylene group, a hexafluoropropylene group, an octafluorobutylene group, a decafluoropentylene group, and an undecafluorohexylene group.

  In addition, preferable anion sites of the general formula (6) include trifluoromethanesulfonate anion, perfluoro-n-butanesulfonate anion, perfluoro-n-octanesulfonate anion, 2- (bicyclo [2.2.1] hepta. -2-yl) -1,1,2,2-tetrafluoroethanesulfonate anion, 2- (bicyclo [2.2.1] hept-2-yl) -1,1-difluoroethanesulfonate anion, 1-adamantylsulfonate Examples include anions and anions exemplified by the following formulas (8-1) to (8-7).

  The acid generator represented by the general formula (6) is given by the combination of the cation and the anion exemplified as described above, but the combination is not particularly limited and can be appropriately selected.

  Moreover, as said acid generator (B), an onium salt compound, a halogen containing compound, a diazoketone compound, a sulfone compound, a sulfonic acid compound etc. can also be used, for example.

  Examples of the onium salt compounds include iodonium salts, sulfonium salts, phosphonium salts, diazonium salts, pyridinium salts, and the like. Specific examples of the onium salt compound include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hepta-2. -Yl-1,1,2,2-tetrafluoroethanesulfonate, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, bis ( 4-t-butylphenyl) iodonium perfluoro-n-octanesulfonate, bis (4-t-butylphenyl) iodonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2- Te La tetrafluoroethane sulfonate, cyclohexyl 2-oxo-cyclohexyl methyl trifluoromethanesulfonate, dicyclohexyl-2-oxo-cyclohexyl trifluoromethane sulfonate, and 2-oxo-cyclohexyl dimethyl sulfonium trifluoromethanesulfonate, and the like.

  Examples of the halogen-containing compound include haloalkyl group-containing hydrocarbon compounds and haloalkyl group-containing heterocyclic compounds. Specific examples of halogen-containing compounds include (trichloromethyl such as phenylbis (trichloromethyl) -s-triazine, 4-methoxyphenylbis (trichloromethyl) -s-triazine, 1-naphthylbis (trichloromethyl) -s-triazine. ) -S-triazine derivatives and 1,1-bis (4-chlorophenyl) -2,2,2-trichloroethane.

  Examples of the diazoketone compound include a 1,3-diketo-2-diazo compound, a diazobenzoquinone compound, a diazonaphthoquinone compound, and the like. Specific examples of the diazo ketone include 1,2-naphthoquinonediazide-4-sulfonyl chloride, 1,2-naphthoquinonediazide-5-sulfonyl chloride, 1,2, naphthoquinonediazide of 2,3,4,4′-tetrahydroxybenzophenone. -4-sulfonic acid ester or 1,2-naphthoquinonediazide-5-sulfonic acid ester, 1,1,1-naphthoquinonediazide-4-sulfonic acid ester of 1,1,1-tris (4-hydroxyphenyl) ethane Examples include 2-naphthoquinonediazide-5-sulfonic acid ester.

  Examples of the sulfone compound include β-ketosulfone, β-sulfonylsulfone, and α-diazo compounds of these compounds. Specific examples of the sulfone compound include 4-trisphenacylsulfone, mesitylphenacylsulfone, bis (phenylsulfonyl) methane, and the like.

  Examples of the sulfonic acid compounds include alkyl sulfonic acid esters, alkyl sulfonic acid imides, haloalkyl sulfonic acid esters, aryl sulfonic acid esters, and imino sulfonates. Specific examples of the sulfonic acid compounds include benzoin tosylate, pyrogallol tris (trifluoromethanesulfonate), nitrobenzyl-9,10-diethoxyanthracene-2-sulfonate, trifluoromethanesulfonylbicyclo [2.2.1] hept- 5-ene-2,3-dicarbodiimide, nonafluoro-n-butanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide, perfluoro-n-octanesulfonylbicyclo [2.2 .1] Hept-5-ene-2,3-dicarbodiimide, 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonylbicyclo [2.2. 1] Hept-5-ene-2,3-dicarbodiimide, N- (trifluoromethanesulfonyl Xyl) succinimide, N- (nonafluoro-n-butanesulfonyloxy) succinimide, N- (perfluoro-n-octanesulfonyloxy) succinimide, N- (2-bicyclo [2.2.1] hept-2-yl- 1,1,2,2-tetrafluoroethanesulfonyloxy) succinimide, 1,8-naphthalenedicarboxylic imide trifluoromethanesulfonate, 1,8-naphthalenedicarboxylic imidononafluoro-n-butanesulfonate, 1,8-naphthalenedicarboxylic Examples include acid imido perfluoro-n-octane sulfonate.

Among these acid generators (B), those represented by the general formula (8) are preferable.
In addition, these acid generators (B) may be used independently and may be used in combination of 2 or more type. Moreover, when this acid generator (B) is used in combination with the acid generator represented by the general formula (8) and other acid generators, the total amount of the acid generator (B) is 100 masses. %, The content of the acid generator other than the acid generator represented by the general formula (8) is preferably 80% by mass or less, and more preferably 60% by mass or less.

  The blending amount of the acid generator (B) is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the polymer (A) from the viewpoint of ensuring sensitivity and developability as a resist. More preferably, it is 0.5-10 mass parts. If the amount is less than 0.1 parts by mass, the sensitivity and developability may be reduced. On the other hand, when it exceeds 20 parts by mass, the transparency to radiation is lowered, and it may be difficult to obtain a rectangular resist pattern.

(2-3) Solvent When using the radiation-sensitive composition of the present invention, the total solid content concentration is usually 1 to 50% by mass, preferably 1 to 25% by mass. Also referred to as “solvent (C)”. After being dissolved, the composition solution is prepared by, for example, filtering with a filter having a pore size of about 0.2 μm.

  Examples of the solvent (C) include 2-butanone, 2-pentanone, 3-methyl-2-butanone, 2-hexanone, 4-methyl-2-pentanone, 3-methyl-2-pentanone, 3,3- Linear or branched ketones such as dimethyl-2-butanone, 2-heptanone, 2-octanone; cyclopentanone, 3-methylcyclopentanone, cyclohexanone, 2-methylcyclohexanone, 2,6-dimethylcyclohexanone, Cyclic ketones such as isophorone; propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol mono-n-propyl ether acetate, propylene glycol mono-i-propyl ether acetate, propylene glycol mono-n-butyl Propylene glycol monoalkyl ether acetates such as ether acetate, propylene glycol mono-i-butyl ether acetate, propylene glycol mono-sec-butyl ether acetate, propylene glycol mono-t-butyl ether acetate; methyl 2-hydroxypropionate, 2-hydroxypropionic acid Ethyl, 2-hydroxypropionate n-propyl, 2-hydroxypropionate i-propyl, 2-hydroxypropionate n-butyl, 2-hydroxypropionate i-butyl, 2-hydroxypropionate sec-butyl, 2-hydroxy Alkyl 2-hydroxypropionates such as t-butyl propionate; methyl 3-methoxypropionate, ethyl 3-methoxypropionate, 3-ethoxy Methyl propionate, other 3-alkoxy propionic acid alkyl such as ethyl 3-ethoxypropionate,

  n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, t-butyl alcohol, cyclohexanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-n-butyl ether , Diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-propyl ether, diethylene glycol di-n-butyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, propylene glycol monomethyl ether , Propylene glycol monoethyl Ether, propylene glycol mono-n-propyl ether, toluene, xylene, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutyrate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl propionate, 3-methyl-3-methoxybutyl butyrate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl acetoacetate, Ethyl acetoacetate, methyl pyruvate, ethyl pyruvate, N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, benzyl ethyl ether, di-n-hexyl ether, diethylene glycol monomethyl ether, diethylene glycol Cole monoethyl ether, caproic acid, caprylic acid, 1-octanol, 1-nonanol, benzyl alcohol, benzyl acetate, ethyl benzoate, diethyl oxalate, diethyl maleate, γ-butyrolactone, ethylene carbonate, propylene carbonate, etc. Can do.

Among these, linear or branched ketones, cyclic ketones, propylene glycol monoalkyl ether acetates, alkyl 2-hydroxypropionate, alkyl 3-alkoxypropionate, γ-butyrolactone and the like are preferable. .
These solvent (C) may be used independently and may be used in combination of 2 or more type.

(2-4) Additive In the radiation-sensitive composition of the present invention, an acid diffusion controller, an alicyclic additive, a surfactant, and a sensitizer are added as necessary unless the effects of the present invention are impaired. Various additives such as can be blended.

<Acid diffusion control agent>
The acid diffusion control agent is a component having an action of controlling a diffusion phenomenon of an acid generated from an acid generator upon exposure in a resist film and suppressing an undesirable chemical reaction in a non-exposed region.
By blending such an acid diffusion controller, the storage stability of the resulting radiation-sensitive composition can be improved. In addition, the resolution of the resist can be further improved, and the change in the line width of the resist pattern due to fluctuations in the holding time (PED) from exposure to post-exposure heat treatment can be suppressed, resulting in extremely high process stability. An excellent composition can be obtained.

Examples of the acid diffusion controller include nitrogen-containing compounds such as tertiary amine compounds, amide group-containing compounds, quaternary ammonium hydroxide compounds, and other nitrogen-containing heterocyclic compounds.
Examples of the tertiary amine compound include triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n- Tri (cyclo) alkylamines such as octylamine, cyclohexyldimethylamine, dicyclohexylmethylamine, tricyclohexylamine; aniline, N-methylaniline, N, N-dimethylaniline, 2-methylaniline, 3-methylaniline, 4- Aromatic amines such as methylaniline, 4-nitroaniline, 2,6-dimethylaniline, 2,6-diisopropylaniline; alkanolamines such as triethanolamine, N, N-di (hydroxyethyl) aniline; N, N, N ′, N′-Tetramethylethyl Diamine, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, 1,3-bis [1- (4-aminophenyl) -1-methylethyl] benzenetetramethylenediamine, bis (2- Examples thereof include dimethylaminoethyl) ether and bis (2-diethylaminoethyl) ether.

  Examples of the amide group-containing compound include Nt-butoxycarbonyldi-n-octylamine, Nt-butoxycarbonyldi-n-nonylamine, Nt-butoxycarbonyldi-n-decylamine, Nt-butoxy. Carbonyldicyclohexylamine, Nt-butoxycarbonyl-1-adamantylamine, Nt-butoxycarbonyl-2-adamantylamine, Nt-butoxycarbonyl-N-methyl-1-adamantylamine, (S)-(- ) -1- (t-butoxycarbonyl) -2-pyrrolidinemethanol, (R)-(+)-1- (t-butoxycarbonyl) -2-pyrrolidinemethanol, Nt-butoxycarbonyl-4-hydroxypiperidine, Nt-butoxycarbonylpyrrolidine, Nt-butoxycarbonylpipe Gin, N, N-di-t-butoxycarbonyl-1-adamantylamine, N, N-di-t-butoxycarbonyl-N-methyl-1-adamantylamine, Nt-butoxycarbonyl-4,4′- Diaminodiphenylmethane, N, N′-di-t-butoxycarbonylhexamethylenediamine, N, N, N′N′-tetra-t-butoxycarbonylhexamethylenediamine, N, N′-di-t-butoxycarbonyl-1 , 7-diaminoheptane, N, N′-di-t-butoxycarbonyl-1,8-diaminooctane, N, N′-di-t-butoxycarbonyl-1,9-diaminononane, N, N′-di- t-butoxycarbonyl-1,10-diaminodecane, N, N′-di-t-butoxycarbonyl-1,12-diaminododecane, N, N′- -T-butoxycarbonyl-4,4'-diaminodiphenylmethane, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl-2-methylbenzimidazole, Nt-butoxycarbonyl-2-phenylbenzimidazole, etc. Examples thereof include Nt-butoxycarbonyl group-containing amino compounds.

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

Examples of the other nitrogen-containing heterocyclic compounds include: pyridine, 2-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 4-ethylpyridine, 2-phenylpyridine, 4-phenylpyridine, 2-methyl- Pyridines such as 4-phenylpyridine, nicotine, nicotinic acid, nicotinamide, quinoline, 4-hydroxyquinoline, 8-oxyquinoline and acridine; in addition to piperazines such as piperazine and 1- (2-hydroxyethyl) piperazine, Pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, piperidine, 3-piperidino-1,2-propanediol, morpholine, 4-methylmorpholine, 1,4-dimethylpiperazine, 1,4-diazabicyclo [2.2.2 ] Octane, imidazole, 4-methylimida 1-benzyl-2-methylimidazole, 4-methyl-2-phenylimidazole, benzimidazole, 2-phenylbenzimidazole, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl-2-methylbenz Examples thereof include imidazole and Nt-butoxycarbonyl-2-phenylbenzimidazole.
These nitrogen-containing compounds may be used alone or in combination of two or more.

  The blending amount of the acid diffusion controller is usually 10 parts by mass or less, preferably 5 parts by mass or less with respect to 100 parts by mass of the polymer (A) from the viewpoint of ensuring high sensitivity as a resist. When this compounding quantity exceeds 10 mass parts, there exists a possibility that the sensitivity as a resist may fall remarkably. In addition, when the compounding quantity of an acid diffusion control agent is less than 0.001 mass part, there exists a possibility that the pattern shape and dimension fidelity as a resist may fall depending on process conditions.

<Alicyclic additive>
The alicyclic additive is a component having an action of further improving dry etching resistance, pattern shape, adhesion to a substrate, and the like.
Examples of such alicyclic additives include 1-adamantanecarboxylic acid, 2-adamantanone, 1-adamantanecarboxylic acid t-butyl, 1-adamantanecarboxylic acid t-butoxycarbonylmethyl, 1-adamantanecarboxylic acid α. -Butyrolactone ester, 1,3-adamantane dicarboxylic acid di-t-butyl, 1-adamantane acetate t-butyl, 1-adamantane acetate t-butoxycarbonylmethyl, 1,3-adamantane diacetate di-t-butyl, 2, Adamantane derivatives such as 5-dimethyl-2,5-di (adamantylcarbonyloxy) hexane; alkylcarboxyl such as dimethyl adipate, diethyl adipate, dipropyl adipate, di-n-butyl adipate, di-t-butyl adipate Acid esters and 5- [2-hydroxy 2,2-bis (trifluoromethyl) ethyl] tetracyclo [6.2.1.1 ^{3, 6.} 0 ^2,7 ] dodecane and the like. Examples of other compounds include deoxycholic acid t-butoxycarbonylmethyl ester and richolic acid t-butoxycarbonylmethyl ester.
These alicyclic additives may be used alone or in combination of two or more.

<Surfactant>
The surfactant is a component having an action of improving coating properties, striations, developability and the like.
Examples of such surfactants include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, and polyethylene glycol dilaurate. In addition to nonionic surfactants such as polyethylene glycol distearate, KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (manufactured by Kyoeisha Chemical Co., Ltd.), Ftop EF301, EF303, EF352 (manufactured by Tochem Products Co., Ltd.), Megafax F171, F173 (manufactured by Dainippon Ink & Chemicals, Inc.), Florard FC430, FC431 ( Sumitomo 3M Limited), Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-105, SC-106 (Asahi Glass Co., Ltd.) And the like.
These surfactants may be used alone or in combination of two or more.

<Sensitizer>
The sensitizer absorbs radiation energy and transmits the energy to the acid generator (B), thereby increasing the amount of acid produced. The apparent sensitivity of the radiation-sensitive composition It has the effect of improving sensitivity.
Examples of such sensitizers include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines, and the like.
These sensitizers may be used alone or in combination of two or more.

  Furthermore, the radiation-sensitive composition of the present invention includes, in addition to the above-mentioned additives, an alkali-soluble polymer, a low-molecular alkali-solubility control agent having an acid-dissociable protecting group, and antihalation as necessary. An agent, a storage stabilizer, an antifoaming agent and the like can be blended. In addition, by blending a dye or pigment, the latent image of the exposed area can be visualized, and the influence of halation during exposure can be alleviated, and by blending an adhesion aid, adhesion to the substrate can be improved. it can.

[3] Method of forming resist pattern The radiation-sensitive composition of the present invention is useful as a chemically amplified resist. In this chemically amplified resist, the acid-dissociable group in the polymer component [mainly polymer (A)] is dissociated by the action of the acid generated from the acid generator by exposure to produce a carboxyl group, As a result, the solubility of the exposed portion of the resist in the alkaline developer is increased, and the exposed portion is dissolved and removed by the alkaline developer to obtain a positive resist pattern.

  When forming a resist pattern from the radiation-sensitive composition of the present invention, first, the polymer composition solution is applied to a silicon wafer, aluminum, or the like by an appropriate application means such as spin coating, cast coating, roll coating or the like. A resist film is formed by coating on a substrate such as a wafer coated with, so that a predetermined resist pattern is formed after heat treatment (hereinafter referred to as “PB”) in some cases. The resist film is exposed. The radiation used at that time is appropriately selected from visible rays, ultraviolet rays, far ultraviolet rays, X-rays, charged particle beams, etc., depending on the type of the acid generator used. ArF excimer laser Far ultraviolet rays represented by (wavelength 193 nm) or KrF excimer laser (wavelength 248 nm) are preferable, and ArF excimer laser (wavelength 193 nm) is particularly preferable.

  Moreover, exposure conditions, such as exposure amount, are suitably selected according to the compounding composition of a radiation sensitive composition, the kind of additive, etc. When using the radiation sensitive composition of this invention, it is preferable to heat-process (PEB) after exposure. When performing this PEB, the dissociation reaction of the acid dissociable group in a polymer component can be smoothly advanced. Although the heating conditions of PEB are suitably adjusted with the compounding composition of a radiation sensitive composition, they are 30-200 degreeC normally, Preferably it is 50-170 degreeC.

  Further, when forming a resist pattern, for example, in Japanese Patent Publication No. 6-12252 (Japanese Patent Laid-Open No. 59-93448), etc., in order to maximize the potential of the radiation-sensitive composition of the present invention. As disclosed, an organic or inorganic antireflection film may be formed on a substrate to be used. Further, in order to prevent the influence of basic impurities contained in the environmental atmosphere, a protective film can be provided on the resist film as disclosed in, for example, JP-A-5-188598. Further, in order to prevent the acid generator and the like from flowing out of the resist film in immersion exposure, a liquid immersion protective film is provided on the resist film as disclosed in, for example, JP-A-2005-352384. You can also. These techniques can be used in combination.

Next, by developing the exposed resist film, a predetermined resist pattern is formed. Examples of the developer used for this development include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, and di-n-propyl. Amine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo -An alkaline aqueous solution in which at least one of alkaline compounds such as [4.3.0] -5-nonene is dissolved is preferable.
The concentration of the alkaline aqueous solution is usually 10% by mass or less. If the concentration of the alkaline aqueous solution exceeds 10% by mass, the unexposed area may be dissolved in the developer, which is not preferable.

An organic solvent can also be added to the developer composed of the alkaline aqueous solution.
Examples of the organic solvent include ketones such as acetone, methyl ethyl ketone, methyl i-butyl ketone, cyclopentanone, cyclohexanone, 3-methylcyclopentanone, and 2,6-dimethylcyclohexanone; methyl alcohol, ethyl alcohol, and n-propyl. Alcohols such as alcohol, i-propyl alcohol, n-butyl alcohol, t-butyl alcohol, cyclopentanol, cyclohexanol, 1,4-hexanediol, 1,4-hexanedimethylol; ethers such as tetrahydrofuran and dioxane Esters such as ethyl acetate, n-butyl acetate and i-amyl acetate; aromatic hydrocarbons such as toluene and xylene; phenol, acetonylacetone and dimethylformamide.
These organic solvents may be used alone or in combination of two or more.
The amount of the organic solvent used is preferably 100% by volume or less with respect to the alkaline aqueous solution. When the amount of the organic solvent used exceeds 100% by volume, the developability is lowered, and there is a possibility that the development residue in the exposed area increases.
An appropriate amount of a surfactant or the like can be added to the developer composed of the alkaline aqueous solution.
In addition, after developing with the developing solution which consists of alkaline aqueous solution, generally it wash | cleans with water and dries.

  Hereinafter, the embodiment of the present invention will be described more specifically with reference to examples. However, the present invention is not limited to this embodiment. In the description of Examples, “part” and “%” are based on mass unless otherwise specified.

[1] Synthesis of polymer for semiconductor resist (A) Polymers (A-1) to (A-10) were synthesized as shown in the following synthesis examples. The details of the compounds (M-1) to (M-3) used as monomers in each synthesis example are as follows.

(Synthesis Example 1)
The compound (M-1) 1.20 g (3 mol%), the compound (M-2) 29.30 g (57 mol%), and the compound (M-3) 19.50 g (40 mol%) were converted into 2-butanone 100 g. And a monomer solution charged with 2.88 g (8 mol%) of azobisisobutyronitrile was prepared. Thereafter, a 500 mL three-necked flask charged with 50 g of 2-butanone was purged with nitrogen for 30 minutes. After the nitrogen purge, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise over 3 hours using a dropping funnel. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution was cooled with water to 30 ° C. or lower, poured into 1000 g of methanol, and the precipitated white powder was filtered off. The filtered white powder was washed twice with 200 g of methanol as a slurry, then filtered and dried at 50 ° C. for 17 hours to obtain a white powder polymer (39 g, yield 78%). ).
This copolymer had a weight average molecular weight (Mw) of 3750, an Mw / Mn of 1.417, ¹³ C-NMR analysis, and ¹ H-NMR analysis. As a result, compound (M-1) and compound (M-2) And the content rate of each repeating unit derived from a compound (M-3) was a copolymer of 3.1: 58.0: 38.9 (mol%). This copolymer is referred to as “polymer (A-1)”.

(Synthesis Example 2)
2.82 g (7 mol%) of the compound (M-1), 27.50 g (53 mol%) of the compound (M-2), and 19.68 g (40 mol%) of the compound (M-3) were added to 100 g of 2-butanone. And a monomer solution charged with 2.91 g (8 mol%) of azobisisobutyronitrile was prepared. Thereafter, a 500 mL three-necked flask charged with 50 g of 2-butanone was purged with nitrogen for 30 minutes. After the nitrogen purge, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise over 3 hours using a dropping funnel. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution was cooled with water to 30 ° C. or lower, poured into 1000 g of methanol, and the precipitated white powder was filtered off. The filtered white powder was washed twice with 200 g of methanol as a slurry, then filtered and dried at 50 ° C. for 17 hours to obtain a white powder polymer (38 g, yield 76%). ).
This copolymer had Mw of 3742, Mw / Mn of 1.417, ¹³ C-NMR analysis and ¹ H-NMR analysis, and as a result, compound (M-1), compound (M-2) and compound (M- The content ratio of each repeating unit derived from 3) was a copolymer of 7.1: 57.6: 35.3 (mol%). This copolymer is referred to as “polymer (A-2)”.

(Synthesis Example 3)
2.82 g (7 mol%) of the compound (M-1), 27.50 g (53 mol%) of the compound (M-2), and 19.68 g (40 mol%) of the compound (M-3) were added to 100 g of 2-butanone. And a monomer solution charged with 1.82 g (5 mol%) of azobisisobutyronitrile was prepared. Thereafter, a 500 mL three-necked flask charged with 50 g of 2-butanone was purged with nitrogen for 30 minutes. After the nitrogen purge, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise over 3 hours using a dropping funnel. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution is cooled with water to 30 ° C. or less, put into 1000 g of methanol, and the precipitated white powder is filtered off. The filtered white powder was washed twice with 200 g of methanol as a slurry, then filtered and dried at 50 ° C. for 17 hours to obtain a white powder polymer (38 g, yield 76%). ).
As for this copolymer, Mw is 5121, Mw / Mn is 1.576, and as a result of ¹³ C-NMR analysis and ¹ H-NMR analysis, compound (M-1), compound (M-2) and compound (M- The content ratio of each repeating unit derived from 3) was a copolymer of 7.0: 54.8: 38.2 (mol%). This copolymer is referred to as “polymer (A-3)”.

(Synthesis Example 4)
2.65 g (9 mol%) of the compound (M-1), 26.58 g (51 mol%) of the compound (M-2), and 19.77 g (40 mol%) of the compound (M-3) were added to 100 g of 2-butanone. And a monomer solution charged with 2.92 g (8 mol%) of azobisisobutyronitrile was prepared. Thereafter, a 500 mL three-necked flask charged with 50 g of 2-butanone was purged with nitrogen for 30 minutes. After the nitrogen purge, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise over 3 hours using a dropping funnel. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After the completion of the polymerization, the polymerization solution was cooled with water to 30 ° C. or less, poured into 1000 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 200 g of methanol as a slurry, then filtered and dried at 50 ° C. for 17 hours to obtain a white powder polymer (38 g, yield 76%). .
This copolymer had Mw of 3748, Mw / Mn of 1.418, ¹³ C-NMR analysis and ¹ H-NMR analysis. As a result, compound (M-1), compound (M-2) and compound (M- The content ratio of each repeating unit derived from 3) was a copolymer of 9.2: 52.6: 38.2 (mol%). This copolymer is referred to as “polymer (A-4)”.

(Synthesis Example 5)
2.82 g (7 mol%) of the compound (M-1), 27.50 g (53 mol%) of the compound (M-2), and 19.68 g (40 mol%) of the compound (M-3) were added to 100 g of 2-butanone. And a monomer solution charged with 4.36 g (12 mol%) of azobisisobutyronitrile was prepared. Thereafter, a 500 mL three-necked flask charged with 50 g of 2-butanone was purged with nitrogen for 30 minutes. After the nitrogen purge, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise over 3 hours using a dropping funnel. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution was cooled with water to 30 ° C. or less, poured into 1000 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 200 g of methanol as a slurry, then filtered and dried at 50 ° C. for 17 hours to obtain a white powder polymer (38 g, yield 76%). .
As for this copolymer, Mw was 3258, Mw / Mn was 1.341, and as a result of ¹³ C-NMR analysis and ¹ H-NMR analysis, compound (M-1), compound (M-2) and compound (M- The content ratio of each repeating unit derived from 3) was a copolymer of 7.2: 57.4: 35.4 (mol%). This copolymer is referred to as “polymer (A-5)”.

(Synthesis Example 6)
6.35 g (15 mol%) of the compound (M-1), 23.02 g (45 mol%) of the compound (M-2), and 20.64 g (40 mol%) of the compound (M-3) were added to 100 g of 2-butanone. And a monomer solution charged with 2.91 g (8 mol%) of azobisisobutyronitrile was prepared. Thereafter, a 500 mL three-necked flask charged with 50 g of 2-butanone was purged with nitrogen for 30 minutes. After the nitrogen purge, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise over 3 hours using a dropping funnel. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After the completion of the polymerization, the polymerization solution was cooled with water to 30 ° C. or less, poured into 1000 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 200 g of methanol as a slurry, then filtered and dried at 50 ° C. for 17 hours to obtain a white powder polymer (38 g, yield 76%). .
This copolymer had Mw of 3748, Mw / Mn of 1.420, ¹³ C-NMR analysis and ¹ H-NMR analysis, and as a result, compound (M-1), compound (M-2) and compound (M- The content ratio of each repeating unit derived from 3) was a copolymer of 15.2: 44.6: 40.2 (mol%). This copolymer is referred to as “polymer (A-6)”.

(Synthesis Example 7)
6.35 g (15 mol%) of the compound (M-1), 23.02 g (45 mol%) of the compound (M-2), and 20.64 g (40 mol%) of the compound (M-3) were added to 100 g of 2-butanone. And a monomer solution charged with 0.73 g (2 mol%) of azobisisobutyronitrile was prepared. Thereafter, a 500 mL three-necked flask charged with 50 g of 2-butanone was purged with nitrogen for 30 minutes. After the nitrogen purge, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise over 3 hours using a dropping funnel. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After the completion of the polymerization, the polymerization solution was cooled with water to 30 ° C. or less, poured into 1000 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 200 g of methanol as a slurry, then filtered and dried at 50 ° C. for 17 hours to obtain a white powder polymer (38 g, yield 76%). .
This copolymer had Mw of 9867, Mw / Mn of 1.882, ¹³ C-NMR analysis and ¹ H-NMR analysis. As a result, compound (M-1), compound (M-2) and compound (M- The content ratio of each repeating unit derived from 3) was a copolymer of 15.0: 44.4: 40.6 (mol%). This copolymer is referred to as “polymer (A-7)”.

(Synthesis Example 8)
12.78 g (30 mol%) of the compound (M-1), 16.43 g (30 mol%) of the compound (M-2), and 20.78 g (40 mol%) of the compound (M-3) were added to 100 g of 2-butanone. And a monomer solution charged with 2.91 g (8 mol%) of azobisisobutyronitrile was prepared. Thereafter, a 500 mL three-necked flask charged with 50 g of 2-butanone was purged with nitrogen for 30 minutes. After the nitrogen purge, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise over 3 hours using a dropping funnel. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After the completion of the polymerization, the polymerization solution was cooled with water to 30 ° C. or less, poured into 1000 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 200 g of methanol as a slurry, then filtered and dried at 50 ° C. for 17 hours to obtain a white powder polymer (38 g, yield 76%). .
This copolymer had Mw of 3805, Mw / Mn of 1.380, and as a result of ¹³ C-NMR analysis and ¹ H-NMR analysis, compound (M-1), compound (M-2) and compound (M- The content ratio of each repeating unit derived from 3) was a copolymer of 30.5: 30.6: 38.9 (mol%). This copolymer is referred to as “polymer (A-8)”.

(Synthesis Example 9)
22.53 g (50 mol%) of the compound (M-1) and 27.47 g (50 mol%) of the compound (M-3) were dissolved in 100 g of 2-butanone, and further 2.03 g of azobisisobutyronitrile ( A monomer solution charged with 5 mol%) was prepared. Thereafter, a 500 mL three-necked flask charged with 50 g of 2-butanone was purged with nitrogen for 30 minutes. After the nitrogen purge, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise over 3 hours using a dropping funnel. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution was cooled with water to 30 ° C. or less, poured into 1000 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 200 g of methanol as a slurry, then filtered and dried at 50 ° C. for 17 hours to obtain a white powder polymer (38 g, yield 76%). .
As for this copolymer, Mw is 4480, Mw / Mn is 1.264, ¹³ C-NMR analysis and ¹ H-NMR analysis result, each repetition derived from compound (M-1) and compound (M-3) The unit content ratio was a copolymer of 50.5: 49.5 (mol%). This copolymer is referred to as “polymer (A-9)”.

(Synthesis Example 10)
30.63 g (60 mol%) of the compound (M-2) and 19.37 g (40 mol%) of the compound (M-3) are dissolved in 100 g of 2-butanone, and further 1.79 g of azobisisobutyronitrile ( A monomer solution charged with 5 mol%) was prepared. Thereafter, a 500 mL three-necked flask charged with 50 g of 2-butanone was purged with nitrogen for 30 minutes. After the nitrogen purge, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise over 3 hours using a dropping funnel. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After the completion of the polymerization, the polymerization solution was cooled with water to 30 ° C. or less, poured into 1000 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 200 g of methanol as a slurry, then filtered and dried at 50 ° C. for 17 hours to obtain a white powder polymer (40 g, yield 80%). .
This copolymer has a Mw of 4632, a Mw / Mn of 1.660, and ¹³ C-NMR analysis and ¹ H-NMR analysis, as a result of each repetition derived from the compound (M-2) and the compound (M-3). The unit content ratio was a copolymer of 60.5: 39.5 (mol%). This copolymer is referred to as “polymer (A-10)”.

In addition, the measurement and evaluation in each said synthesis example were performed in the following way.
<Mw and Mn>
Gel permeation based on monodisperse polystyrene using GPC columns (2 G2000HXL, 1 G3000HXL, 1 G4000HXL) manufactured by Tosoh Corporation under the analysis conditions of a flow rate of 1.0 ml / min, elution solvent tetrahydrofuran, and column temperature of 40 ° C. It was measured by an association chromatography (GPC). Further, the degree of dispersion Mw / Mn was calculated from the measurement results.
< ^13C -NMR analysis>
The ¹³ C-NMR analysis of each polymer was measured using “JNM-EX270” manufactured by JEOL Ltd.

[2] Preparation of radiation-sensitive composition solution Table 1 shows the types (A) polymer, (B) acid generator and (D) acid diffusion controller shown in Table 1 in (C) solvent. Dissolved in proportion. Then, each radiation sensitive composition solution of Example 1-7 and Comparative Example 1-5 was prepared by filtering this mixed solution with a membrane filter having a pore size of 0.2 μm.

Here, each detail of (B) acid generator, (C) solvent, and (D) acid diffusion control agent of Table 1 is demonstrated.
<Acid generator (B)>
B-1: Triphenylsulfonium 2- (3-tetracyclo [4.4.0.1 ^2,5 .1, ^7,10 ] dodecanyl) -1,1-difluoroethanesulfonate B-2: 1- (4-n -Butoxynaphthalen-1-yl) tetrahydrothiophenium / nonafluoro-n-butanesulfonate B-3: triphenylsulfonium / nonafluoro-n-butanesulfonate B-4: 1- (4-n-butoxynaphthalen-1-yl) ) Tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate
<Solvent (C)>
C-1: Propylene glycol monomethyl ether acetate C-2: Cyclohexanone C-3: Gamma butyrolactone
<Acid diffusion control agent (D)>
D-1: Nt-butoxycarbonyl-4-hydroxypiperidine

[3] Performance Evaluation of Radiation-Sensitive Composition The following performance evaluation was performed using the radiation-sensitive composition solutions of Examples 1 to 7 and Comparative Examples 1 to 5, and the results are shown in Table 2.

<Sensitivity>
When exposure is performed with an ArF light source, a silicon wafer having an ARC29 (Nissan Chemical Industries Co., Ltd.) film having a film thickness of 770 mm is formed on the wafer surface, and each composition solution is placed on a substrate on a clean track ACT8 (Tokyo Electron). ), And a resist film having a film thickness of 0.16 μm formed by performing PB on a hot plate at 110 ° C. for 60 seconds on a hot plate, NiF ArF excimer laser exposure apparatus “S306C” (Numerical aperture 0.78) was used and exposed through a mask pattern (using a 6% halftone mask). Thereafter, PEB was performed using a clean track ACT8 (manufactured by Tokyo Electron) at 115 ° C. for 60 seconds, followed by development with a 2.38% tetramethylammonium hydroxide aqueous solution at 25 ° C. for 60 seconds, followed by washing with water. And dried to form a positive resist pattern. At this time, an exposure amount such that a line and space pattern (1L1S) having a diameter of 0.075 μm in the mask becomes a size having a diameter of 0.075 μm was set as the optimum exposure amount, and this optimum exposure amount was set as the sensitivity.

<Resolution>
The dimension (diameter) of the smallest resist pattern that can be resolved at the optimum exposure dose was taken as the resolution.

<EL (exposure margin)>
Using a silicon wafer having an ARC29 (Nissan Chemical Industries Co., Ltd.) film with a film thickness of 770 mm on the wafer surface, each composition solution was applied onto the substrate by spin coating using a clean track ACT8 (manufactured by Tokyo Electron). Using a Nikon ArF excimer laser exposure apparatus “S306C” (numerical aperture of 0.78) on a resist film having a film thickness of 0.16 μm formed by performing PB on a hot plate at 110 ° C. for 60 seconds. The film was exposed at a predetermined exposure amount through a mask pattern (using a 6% halftone mask). Thereafter, PEB was performed using a clean track ACT8 (manufactured by Tokyo Electron) at 115 ° C. for 60 seconds, followed by development with a 2.38% tetramethylammonium hydroxide aqueous solution at 25 ° C. for 60 seconds, followed by washing with water. And dried to form a positive resist pattern [line and space pattern (1L1S, diameter 0.075 μm)].
At this time, in a range amount of exposure 40~60mJ / cm ^2, definitive when the varied 1.0 mJ / cm ² steps, plotting the size of the line pattern was the slope as EL (nm / mJ) .

<LWR (Line Widow Roughness)>
At the optimum exposure amount, a 75 nm (1L / 1S) pattern formed on the resist film on the substrate was observed from the top of the pattern using a length measuring SEM (manufactured by Hitachi, Ltd., model number “S9380”), and the diameter was measured. Measurement is performed at an arbitrary point, and the measurement variation is expressed by 3 sigma.
In addition, this value is so preferable that it is small, and the case where it was 8.0 nm or less was made favorable.

<Minimum collapse dimension (fall)>
The CD dimension at the exposure amount 1 mJ before the exposure amount at which the line collapsed was measured by a length measurement SEM (manufactured by Hitachi, Ltd., model number “S-9380”).
In addition, this value is so preferable that it is small, and the case where it was 50 nm or less was made favorable.

Claims (4)

A polymer for a semiconductor resist containing a repeating unit represented by the following general formula (1) and a repeating unit represented by the following general formula (2):
When the total repeating unit contained in the polymer for semiconductor resist is 100 mol%, the content of the repeating unit represented by the following general formula (1) is 0.5 to 10 mol%, and the following general formula ( The polymer for semiconductor resists, wherein the content ratio of the repeating unit represented by 2) is 50 to 70 mol%.

[In General formula (1), R < ¹ > and R < ² > represents the alkyl group which may have a hydrogen atom or a C1-C4 substituent, respectively. ]

In [general formula (2), R ³ and R ⁴ each represent a hydrogen atom or an alkyl group which may have a substituent group having 1 to 4 carbon atoms. ]   The polymer for semiconductor resist according to claim 1, wherein the weight average molecular weight measured by gel permeation chromatography is 3000 to 5000.   The polymer is polymerized using 6 to 15 mol% of azobisisobutyronitrile as a polymerization initiator when the total amount of monomers used for polymerization is 100 mol%. The polymer for semiconductor resists described in 1.   A radiation-sensitive composition comprising (A) the polymer for semiconductor resist according to any one of claims 1 to 3, (B) a radiation-sensitive acid generator, and (C) a solvent. object.