JP4568667B2 - Positive resist composition and pattern forming method using the same - Google Patents

Description

  The present invention relates to a positive resist composition suitably used in an ultramicrolithography process such as the manufacture of VLSI and high-capacity microchips and other photo-publishing processes. More specifically, the present invention relates to a positive resist that can form a highly refined pattern using electron beam, X-ray, EUV light (Extreme Ultra-violet: wavelength of around 13 nm), etc. The present invention relates to a positive resist composition that can be suitably used for fine processing of a semiconductor element using EUV light or the like.

  Conventionally, in the manufacturing process of semiconductor devices such as IC and LSI, fine processing by lithography using a resist composition has been performed. In recent years, with the high integration of integrated circuits, the formation of ultrafine patterns in the submicron region and the quarter micron region has been required. Along with this, there is a tendency for the exposure wavelength to be shortened from g-line to i-line, and further to KrF excimer laser light. In addition to the excimer laser light, lithography using electron beams, X-rays, or EUV light is also being developed.

  As a resist suitable for a lithography process using such an electron beam, X-ray or EUV light, a chemically amplified resist using an acid catalyst reaction is mainly used from the viewpoint of high sensitivity. Is a polymer having a property of being insoluble or hardly soluble in an alkaline aqueous solution and soluble in an alkaline aqueous solution by the action of an acid (hereinafter sometimes abbreviated as an acid-decomposable resin), and an acid generator. The chemically amplified composition is effectively used.

  Regarding a positive resist for electron beam or X-ray, for example, Patent Document 1 (Japanese Patent Laid-Open No. 4-219757) discloses that 20 to 70% of the phenolic hydroxy group of poly (p-hydroxystyrene) is an acetal group. Resist compositions containing substituted polymers are disclosed.

Patent Document 2 (Japanese Patent Application Laid-Open No. 2000-66382) discloses p-hydroxystyrene and (
A radiation sensitive resin composition containing a copolymer of (meth) acrylic acid ester is disclosed.
Patent Document 3 (Japanese Patent Laid-Open No. 2001-33970) discloses a radiation-sensitive resin composition containing a copolymer of (meth) acrylic acid ester having a specific structure.
Patent Document 4 (Japanese Patent Application Laid-Open No. 2002-55457) discloses a method of forming a pattern by radiation or electron beam having a short wavelength (less than about 160 nm) using a photoresist composition containing 5% by mass or more of an acid generator. Is disclosed.

Patent Document 5 (Japanese Patent Application Laid-Open No. 2002-323768) discloses a resist composition for positive electron beam, X-ray or EUV containing a resin having a specific acetal structure.
Patent Document 6 (Japanese Patent Laid-Open No. 2003-177537) discloses a resist composition for positive electron beam, X-ray or EUV containing a resin having an acetal structure having an ether linking group.
Patent Document 7 (Japanese Patent Application Laid-Open No. 2003-57819) discloses a photoresist composition containing a branched polymer having a polymerizable terminal group.
Patent Document 8 (Japanese Patent Laid-Open No. 2000-347412) discloses a resist material containing a denstyrene polymer or a hyperbranched polymer of a hydroxystyrene derivative.

However, even with the above technology, the present situation is that the resolution, line edge roughness, sensitivity, and pattern shape are not satisfied at the same time.
Line edge roughness means that due to the characteristics of the resist composition, the line pattern of the resist composition and the edge of the substrate interface exhibit a shape that varies irregularly in a direction perpendicular to the line direction. When this pattern is observed from directly above, the edges appear to be uneven (approximately ± several tens of nm). Since the unevenness is transferred to the substrate by the etching process, if the unevenness is large, an electrical characteristic defect is caused and the yield is reduced. As the resist pattern size becomes less than quarter micron, there is an increasing demand for improving line edge roughness.

  The pattern shape is the rectangularity of the created pattern. When the pattern cross section is observed from the side, only the upper part of the pattern protrudes (T-top), the upper surface of the pattern becomes round (round top), and the pattern width is If a shape (taper) that widens from the top to the bottom and a shape that narrows the pattern width from the top to the bottom (reverse taper) are seen, pattern transfer by etching cannot be performed faithfully.

Further, when EUV is used as a light source, the wavelength of light belongs to the extreme ultraviolet region and has high energy, and thus there has been a problem such as a decrease in contrast due to concerted photochemical reactions such as negation due to EUV light.
In the combination of conventionally known techniques, it is difficult to have both a sufficiently good line edge roughness and a good pattern shape under electron beam or X-ray irradiation, and both of these are desired. Further, it has been desired to have sufficiently good sensitivity and contrast even under EUV irradiation.

JP-A-4-219757 JP 2000-66382 A JP 2001-33970 A JP 2002-55457 A JP 2002-323768 A JP 2003-177537 A JP 2003-57819 A Japanese Patent Application Laid-Open No. 2000-347412

  An object of the present invention is to solve the problem of performance improvement technology in microfabrication of a semiconductor device using a high energy beam, particularly a KrF excimer laser, an electron beam, an X-ray or EUV light. Another object is to provide a positive resist composition that satisfies both line edge roughness and pattern shape at the same time, and is excellent in sensitivity and dissolution contrast when using EUV light.

That is, the positive resist composition according to the present invention has the following constitution.
(1) (A) a polymer having three or more polymer chains via at least one branch, and having increased solubility in an alkali developer by the action of an acid; and
(B) A positive resist composition comprising a sulfonium salt having a cation represented by formula (I).

In general formula (I),
R ^{1 to} R ¹³ each independently represent a hydrogen atom or a substituent, and may be bonded to each other to form a ring.
Z is —CO— or —SO ₂ — .

  (2) The positive resist composition as described in (1) above, wherein the polymer (A) is a comb polymer.

(3) The positive resist composition as described in (1) above, wherein the polymer (A) is a star polymer.
(4) The positive resist composition as described in (1) above, wherein the polymer (A) is a hyperbranched polymer.

(5) The positive resist composition as described in any one of (1) to (4) above, wherein at least one of the polymer chains forming the polymer (A) comprises a vinyl-type repeating unit.
(6) The positive resist composition as described in (5) above, wherein the vinyl-type repeating unit contains a repeating unit derived from a styrene derivative and / or a repeating unit derived from a (meth) acrylic acid derivative. object.

Further preferred embodiments include the following configurations.
(7) Any of (1) to (6) above, wherein the amount of (D) the surfactant is 0.0001% by mass to 2% by mass per 100% by mass of the solid content in the composition A positive resist composition as described above.
(8) The polymer (A) contains a repeating unit having a group that decomposes by the action of an acid, a group having at least one of an alicyclic ring and an aromatic ring is eliminated, and generates an alkali-soluble group. The positive resist composition according to any one of (1) to (7) above.
(9) The positive resist composition as described in any one of (1) to (8) above, which is exposed to an electron beam, an X-ray or EUV.
(10) The positive resist composition as described in any one of (1) to (8), wherein the actinic ray or radiation is an ultraviolet ray having a wavelength of 100 to 300 nm.
(11) The positive resist composition as described in any one of (1) to (8), wherein the actinic ray or radiation is an ultraviolet ray having a wavelength of 200 to 300 nm.

(12) The positive resist composition as described in any one of (1) to (11), further comprising (C) an organic basic compound.
(13) The positive resist according to any one of (1) to (12), wherein the component (B) contains (B1) a compound capable of generating an organic sulfonic acid by the action of actinic rays or radiation. Composition.
(14) The positive resist according to any one of (1) to (12), wherein the component (B) contains (B2) a compound capable of generating arylsulfonic acid by the action of actinic rays or radiation. Composition.
(15) The positive resist composition as described in any one of (1) to (14), further comprising a solvent.

(16) The positive resist composition as described in any one of (1) to (15) above, which contains propylene glycol monomethyl ether acetate as the solvent.
(17) The positive resist composition as described in (16), further containing propylene glycol monomethyl ether as the solvent.
(18) Furthermore, the acetal compound represented by the following general formula (A) and / or the acetal compound represented by the general formula (B) is contained, and any one of (1) to (17) A positive resist composition.

In general formulas (A) and (B), R ₁ ′ and R ₂ ′ each independently represents an organic group having 1 to 30 carbon atoms. The present invention is the invention according to the above (1) to (18), but will be described below including other matters.

  According to the present invention, it is possible to provide a positive resist composition exhibiting good performance even in pattern formation using an electron beam or EUV light.

Hereinafter, the positive resist composition of the present invention will be described in detail.
In addition, in the description of the group (atomic group) in this specification, the description which does not describe substitution and non-substitution includes what does not have a substituent and what has a substituent. . For example, the “alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).

[1] (A) A polymer (hereinafter referred to as “acid-decomposable polymer (A) having three or more polymer chains via at least one branch portion”, which is decomposed by the action of an acid to increase the solubility in an alkaline developer. ) ")
The acid-decomposable polymer (A) is a resin (acid-decomposable resin) that has three or more polymer chains via at least one branch part and decomposes by the action of an acid to increase the solubility in an alkali developer. And a repeating unit having a group (acid-decomposable group) that decomposes by the action of an acid as described later and generates an alkali-soluble group such as a carboxy group or a hydroxyl group.

The acid-decomposable polymer (A) used in the present invention is a so-called branched polymer having three or more polymer chains via at least one branched part, and one conventionally used polymer chain. The structure is different from that of a linear polymer composed only of Regarding branched polymers, edited by Koji Ishizu, “Nanotechnology of Branched Polymers” (IPC) Chapter 1, Chapter 6, Chapter 7 and Takuhei Nose, Seiichi Nakahama, Kiyozo Miyata “Graduate Polymer Chemistry” ( Kodansha) p. 39. In general, since a branched polymer has physical properties derived from a branched (branched) structure, it is known that a solution and a solid physical property are greatly different from a normal linear polymer.
The molecular weight of each polymer chain is preferably 50 or more, more preferably 100 or more, and still more preferably 200 or more.
The polymer chain has a plurality of repeating units.

Examples of the branched polymer include a comb polymer (A1), a star polymer (A2), and a hyperbranched polymer (A3). The comb polymer is a branched polymer in which a large number of branches appear on the trunk at equal intervals. Among comb polymers, those having a side chain (branch) having a different configuration or arrangement from the main chain (trunk) are called graft polymers. A star-shaped polymer is a branched polymer with a structure in which atoms or atomic groups are the core and a plurality of three or more branched chains extend radially. A hyperbranched polymer is a total of two types of substituents in one molecule. It is a multi-branched polymer obtained by polymerization of so-called AB _x type molecules having three or more. For the comb type, graft, star type and hyperbranched polymer, see “Graduate Polymer Chemistry” p. 39-43.

Examples of the method for confirming the presence or absence of the branched chain of the branched polymer include a method by GPC (gel permeation chromatography) -light scattering measurement. That is, GPC / MALLS (multi-angle light scattering) measurement of the polymer is performed, and at each elution position, <R ² > ^1/2 (square root of the mean square of the radius R) is obtained from the slope of the scattered light intensity, and the scattered light The weight average molecular weight Mw is obtained from the intensity intercept, the logarithm of <R ² > ^1/2 and Mw is plotted, and the slope α is calculated by the least square method. A slope α _x of a certain polymer X and a linear polymer having the same monomer composition as that of the polymer X and having a similar copolymer composition (for example, an error in the copolymer composition is within 10%, that is, in each of the two polymers When the slope α _{l in} the case of the difference in content (mol%) of the same repeating unit containing the largest amount (within 10 mol%) is compared, when (α _l / α _x )> 1, the polymer X is branched When a chain is present and the value of (α _l / α _x ) is larger than 1, the proportion of branching in the polymer X molecule is larger. When (α _l / α _x ) ≦ 1, the polymer X has a branched chain. Evaluate not. When the slope obtained from the above plot is α _b when the branched polymer of the present invention is used, the value of (α _l / α _b ) is preferably 1.02 or more, more preferably 1.03 or more, still more preferably Is 1.04 or more, most preferably 1.05 or more.

  Regarding polymerization of each polymer chain (not limited to the trunk and branches) forming the branched polymer, conventional techniques (radical polymerization, cationic polymerization, anionic polymerization, or living radical polymerization, living cationic polymerization, living anionic polymerization, chain polymerization) Chain polymerization is preferred. That is, each polymer chain forming the branched polymer is preferably composed of a vinyl-type repeating unit. As the polymerization method, radical polymerization and living radical polymerization are particularly preferable among chain polymerizations.

  The vinyl-type repeating unit is preferably a styrene derivative represented by the following formula (I) or a (meth) acrylic acid derivative represented by the following formula (II).

In the formula (I), Z represents a hydrogen atom or an organic group (acid-decomposable or non-acid-decomposable). Y represents a hydrogen atom or an organic group (acid-decomposable or non-acid-decomposable). R ₁ represents a hydrogen atom, a halogen atom or an alkyl group. a, b and c are integers and satisfy a ≧ 0, b ≧ 0, c ≧ 0, and 0 ≦ a + b + c ≦ 5.
Among the organic groups of Z, as the acid-decomposable group, —C (R ₁₁ ) (R ₁₂ ) (R ₁₃ ), —C (R ₁₄ ) (R ₁₅ ) (OR ₁₆ ), — [C (R ₁₇ ) (R _{18)] n -CO-OC (R 11)} (R 12) (R 13) are preferred. R _{11 to} R ₁₃ each independently represents an alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl group or an aryl group. R ₁₄ , R ₁₅ , R ₁₇ and R ₁₈ each independently represent a hydrogen atom or an alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl group or an aryl group. R ₁₆ represents an alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl group or an aryl group. Two of R ₁₁ , R ₁₂ and R ₁₃ , two of R ₁₄ , R ₁₅ and R ₁₆ , or two of R ₁₇ and R ₁₈ may be bonded to form a ring.
The alkyl group, the cycloalkyl group, the alkenyl group, and the aralkyl group each include —O—, —S—, —CO ₂ —, —CO—, —CONH—, —SO ₂ —, in each alkylene chain. -SO- or a combination thereof may be included.
Of the organic groups of Y, the acid-decomposable group is preferably —C (R ₁₁ ) (R ₁₂ ) (R ₁₃ ) or —C (R ₁₄ ) (R ₁₅ ) (OR ₁₆ ).

In formula (II), R ₂ represents a hydrogen atom or an alkyl group. X ₁ represents —ORa, —SRb or —N (Rc) Rb. Ra represents a hydrogen atom or an organic group (acid-decomposable or non-acid-decomposable). Rb represents a hydrogen atom or a non-acid-decomposable organic group. Rc represents a hydrogen atom or an alkyl group.
Among the organic groups of Ra, the acid-decomposable group includes -C (R ₁₁ ) (R ₁₂ ) (R ₁₃ ), -C (R ₁₄ )
R ₁₅ ) (OR ₁₆ ) is preferred.

The non-acid-decomposable organic group for Ra or Rb is an organic group that is not decomposed by the action of an acid, such as an alkyl group, a cycloalkyl group, an aryl group, that is not decomposed by the action of an acid, Examples thereof include an aralkyl group, an alkoxy group, an alkoxycarbonyl group, an amide group, and a cyano group. The alkyl group and cycloalkyl group preferably have 1 to 10 carbon atoms. For example, methyl group, ethyl group, propyl group, n-butyl group, sec-butyl group, hexyl group, 2-ethylhexyl group, octyl group, cyclohexane A propyl group, a cyclobutyl group, a cyclohexyl group, an adamantyl group, etc. can be mentioned. The aryl group is preferably an aryl group having 6 to 14 carbon atoms, and examples thereof include a phenyl group, a naphthyl group, and an anthracenyl group. The aralkyl group is preferably an aralkyl group having 6 to 12 carbon atoms, and examples thereof include a benzyl group, a phenethyl group, and a cumyl group. The alkoxy group in the alkoxy group and the alkoxycarbonyl group is preferably an alkoxy group having 1 to 5 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, a propoxy group, an n-butoxy group, and an isobutoxy group.
The alkyl group of R ₂ and Rc is preferably an alkyl group having 1 to 5 carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, a t-butyl group or the like is preferable. Can be mentioned.

  Examples of the substituent that each of the above groups may have include, for example, those having active hydrogen such as amide group, ureido group, urethane group, hydroxyl group, carboxyl group, and halogen atoms (fluorine atom, chlorine atom, bromine atom). , Iodine atom), alkoxy group (methoxy group, ethoxy group, propoxy group, butoxy group, etc.), thioether group, acyl group (acetyl group, propanoyl group, benzoyl group, etc.), acyloxy group (acetoxy group, propanoyloxy group, Benzoyloxy group etc.), alkoxycarbonyl group (methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group etc.), cyano group, nitro group and the like.

  Specific examples of the repeating unit represented by the formula (I) are shown below, but are not limited thereto.

  Specific examples of the repeating unit represented by the formula (II) are shown below, but are not limited thereto.

Next, a method for synthesizing each branched polymer will be described.
The method for synthesizing the comb polymer (A1) is not limited as long as it can synthesize a polymer having a structure that matches the definition of the comb polymer. Specifically, a polymerization starting point is generated in some way by a polymer that becomes a trunk, a monomer that is a trunk is polymerized therefrom, and branches are formed, and a polymer having an activity such as a living polymer is made into a backbone polymer. The method of making it react, the method of polymerizing the polymer (macromonomer) which has a polymerizable functional group at the terminal, etc. are mentioned. Of the above synthesis methods, the macromonomer method is preferred. The synthesis of the macromonomer and the polymer synthesis using it are described in Chapter 2 and Chapter 3 of the “Chemical Monomer Chemistry and Industry” edited by Yuya Yamashita.

The synthesis method of star polymer (A2) includes the arm-first method in which a polymer that becomes a branched chain (branch) is first synthesized and then bonded to a nucleus atom or atomic group (hereinafter referred to as a core), The core-first method of synthesizing a polyfunctional initiator as a core and then synthesizing a polymer as a branch can be roughly divided into two types, and either method may be used. The synthesis method of the star polymer (A2) is described in Chapter 1 of Koji Ishizu, “Nanotechnology of Branched Polymers” (IPC).
The synthesis method of the hyperbranched polymer (A3) is a method of applying a condensation reaction used in the synthesis of a linear polymer to a polyfunctional molecule (AB _x type monomer) when using condensation polymerization.
In the case of using chain polymerization, a method of synthesizing by a cationic polymerization or radical polymerization of a monomer in which a compound having a double bond has a reaction point serving as an initiator can be mentioned, and the latter is preferable. The method for synthesizing the hyperbranched polymer (A3) is described in Chapter 6 of Koji Ishizu, “Nanotechnology of Branched Polymers” (IPC).
In addition, when a normal linear polymer is synthesized by radical polymerization, it is generated suddenly due to the influence of chain transfer or the like, and it is generated from a growing radical having two or more radical active sites in one molecule. The polymer is completely different from the branched polymer of the present invention because the structure of the branched chain and the degree of generation of the branched chain are completely irregular and the structure cannot be defined. Such polymers are not included in the branched polymer of the present invention.

  The acid-decomposable polymer (A) of the present invention does not contain a dendrimer. The acid-decomposable polymer (A) of the present invention contains a mixture of branched (branched) units and linear units, but dendrimers contain only branched repeating units regardless of generation. The acid-decomposable polymer (A) of the present invention is polydisperse and exhibits a molecular weight dispersity of at least 1.08, but the dendrimer is a monodisperse type (generally having a dispersity of less than about 1.02). It has a clear outline. Therefore, the acid-decomposable polymer (A) of the present invention and the dendrimer can be distinguished.

  Specific examples of the comb polymer (A1), star polymer (A2), and hyperbranched polymer (A3) are shown below, but are not limited thereto.

[Comb type polymer (A1)]

[Star polymer (A2)]

[Hyperbranched polymer (A3)]

  m1 is a number greater than 0, and each of m2, m, n1, n2, and n is a number greater than or equal to 0.

  The acid-decomposable polymer (A) preferably contains 5 mol% or more, more preferably 10 mol% or more of the repeating unit represented by the general formula (I) or the general formula (II) in all repeating units. Preferably it is 20 mol% or more. Moreover, you may contain another repeating unit collectively as needed. Examples of the monomer corresponding to the other repeating unit include maleic acid derivatives, maleic anhydride derivatives, (meth) acrylonitrile, vinyl pyrrolidone, vinyl pyridine, and vinyl acetate.

The acid-decomposable polymer (A) preferably contains 5 to 90 mol% of repeating units having an acid-decomposable group in all repeating units, more preferably 7 to 80 mol%, still more preferably 10 to 70 mol%. %. As the repeating unit having an acid-decomposable group, a structure in which Z is —C (R ₁₄ ) (R ₁₅ ) (OR ₁₆ ) in the formula (I), or X in the formula (II) is —ORa, and Ra is A structure of —C (R ₁₁ ) (R ₁₂ ) (R ₁₃ ) or —C (R ₁₄ ) (R ₁₅ ) (OR ₁₆ ) is preferred.

In addition, the acid-decomposable polymer (A) is a repeating unit having an acid-decomposable group, and a group having an alkali-soluble group by removing a group having at least one of an alicyclic ring and an aromatic ring by the action of an acid. It is preferable to have a unit.
As such a repeating unit, for the repeating units represented by the general formulas (I) and (II), an acid-decomposable organic group as Y and Z in the general formula (I) and the general formula (II) The case where the acid-decomposable organic group as Ra is a group having at least one of an alicyclic ring and an aromatic ring is mentioned.
The acid-decomposable polymer (A) is decomposed by the action of an acid, a group having at least one of an alicyclic ring and an aromatic ring is eliminated, and the content of the repeating unit having a group that generates an alkali-soluble group is acid-decomposable. It is 3-95 mol% normally with respect to all the repeating units which comprise a polymer (A), Preferably it is 5-80 mol%.
Further, the acid-decomposable organic group as Y and Z in the general formula (I) and the acid-decomposable organic group as Ra in the general formula (II) preferably have a total carbon number of 4 to 50, preferably 5 to 45. Is more preferable, and 6 to 40 is particularly preferable.

  As a method for introducing an acid-decomposable group in the acid-decomposable polymer (A), a method in which a monomer in which an alkali-soluble group such as a phenolic hydroxyl group or a carboxyl group is previously protected with an acid-decomposable group is copolymerized and introduced, There is a method in which a polymer skeleton containing an alkali-soluble group is constructed, and then the alkali-soluble group is introduced after protecting with an acid-decomposable group. Either method may be used. An example of the latter method is a method in which a part of the phenolic hydroxyl group of a polymer having a phenolic hydroxyl group is obtained by an acetalization reaction using a corresponding vinyl ether compound and an acid catalyst. An acetal group can be introduced by the method described in JP-A-5-249682, JP-A-8-123032 and JP-A-10-221854. It is also possible to introduce a desired acetal group using S. Malik's acetal exchange reaction described in J. Photo Polym. Sci. Tech., 11 (3) 431 (1998).

That is, it is a method in which a polymer having a phenolic hydroxyl group is reacted with a vinyl ether compound represented by the following general formula (C) and an alcohol compound represented by the following general formula (D) in the presence of an acid catalyst. Here, as an acid catalyst, p-toluenesulfonic acid, p-toluenesulfonic acid pyridinium salt, etc. can be used. In this method, for example, as shown in the following reaction formula, a resin having a phenolic hydroxyl group, a vinyl ether compound represented by the following general formula (C) and an alcohol compound represented by the following general formula (D) are present in the presence of an acid catalyst. By reacting, only R ₃ ′ and R ₄ ′ or R ₄ ′ can be introduced as an acetal group as shown in the following general formula (F).

  The acid-decomposable polymer (A) may have one or more acid-decomposable groups.

The weight average molecular weight of the acid-decomposable polymer (A) is preferably 1000 to 200,000, and particularly preferably 1,500 to 20,000. That is, a molecular weight of 200,000 or less is preferable from the viewpoint of solubility and resolving power. Here, the weight average molecular weight is a value obtained by gel permeation chromatography (GPC) by light scattering detection.
The lower limit of the molecular weight dispersity (weight average molecular weight / number average molecular weight) of the acid-decomposable polymer (A) is 1.1 as described above. Regarding the upper limit, the higher the molecular weight dispersibility of the acid-decomposable polymer (A), the more likely the line edge roughness tends to be worse, so it is generally 3.0 or less, preferably 2.5 or less, more preferably 2 0.0 or less, more preferably 1.5 or less, and most preferably 1.3 or less.

  For such polymers with low molecular weight dispersibility, the polymer synthesis conditions (amount of polymerization solvent, amount of polymerization initiator) and polymer purification conditions (type / amount of reprecipitation solvent, number of reprecipitation operations) are variously changed. Can be obtained. For example, the molecular weight can be adjusted by changing the amount of the polymerization solvent or initiator, and the degree of dispersion of the resin can be reduced by changing the reprecipitation solvent or increasing the number of reprecipitation operations. As the reprecipitation solvent, it is preferable to use a mixture of two or more solvents, or to perform the reprecipitation operation twice or more, and to perform the reprecipitation operation using a reprecipitation solvent in which two or more solvents are mixed. More preferably, it is performed more than once. Alternatively, a polymer having a low molecular weight dispersity can also be synthesized via a living anion, living radical, or living cation polymerization method.

(A1) when the comb polymer and the average degree of polymerization of the partial (backbone) of the stem and n _m, n _m is the weight average molecular weight of the polymer may be any range as long as within the range described above. Further, when the average polymerization degree of the branched chains extending from the branching repeating units and n _b, preferably n _b ≧ 3 is the lower limit of n _b, more preferably n _b ≧ 5, more preferably from n _b ≧ 10. When _nb is too small, it becomes close to a normal linear polymer, and the effect of the present invention cannot be obtained. The upper limit of n _b may be any range as long as the weight average molecular weight of the polymer falls within the above range, but n _b ≦ 15 _nm is preferable, n _b ≦ 13 _nm , more preferably n _b ≦ _{10 nm.} It is. If _nb is too large with respect to _nm , the solubility is remarkably slow, and the effects of the present invention cannot be obtained.
Moreover, when the average number of branch points in one polymer molecule is x, x is 0.05 _nm ≦ x ≦ 0.
. 8 _nm is preferable, more preferably 0.1 _nm ≤ x ≤ 0.7 _nm , and still more preferably 0.8 _nm .
It is 15 _nm <= x <= 0.6 _nm . If x is too small, it becomes almost the same as a normal linear polymer, and if x is too large, the solubility is remarkably slow, and neither of the effects of the present invention can be obtained.

(A2) In the case of a star polymer, y is 3 or more by definition, where y is the average number of branches (branches) extending from the core portion. The upper limit of y is preferably y ≦ 20, more preferably y ≦ 17, and still more preferably y ≦ 14. Further, assuming that the average degree of polymerization of each branched chain is n _h , n _h is preferably 5 ≦ n _h ≦ 1000, more preferably 10 ≦ n _h ≦, assuming that the weight average molecular weight of the polymer falls within the above range. 800, more preferably 15 ≦ n _h ≦ 600. The molecular weight of the core portion is preferably 2000 or less, more preferably 1800 or less, and still more preferably 1500 or less. The lower limit of the molecular weight of the core portion is not particularly limited. However, when the value of y is 4 or more, a structure in which the connecting portions with a plurality of branched chains existing in the core portion are separated and are not close to each other is preferable. . Specifically, a structure having one or more monocyclic or polycyclic aromatic rings is preferable.

  (A3) In the case of a hyperbranched polymer, the average molar ratio of a repeating unit having a branching point and a repeating unit having no branching point in one polymer molecule (for example, in the structure of the hyperbranched polymer exemplified above) Is (average of (m1 + m2 + ...) :( n1 + n2 + ...)) is usually 1:99 to 99: 1, preferably 5:95 to 95: 5, more preferably 10:90 to 90:10. It is.

  As content in the composition of an acid-decomposable polymer (A), it is 70-98 mass% normally with respect to the mass of the total solid of this composition, Preferably it is 75-96 mass%, More preferably Is 80-96 mass%.

[2] A sulfonium compound (B) having a cation represented by the general formula (I)
The photosensitive composition of the present invention comprises a sulfonium compound having a cation represented by the general formula (I) (hereinafter simply referred to as a sulfonium salt (B)) as a compound (acid generator) that generates an acid upon irradiation with actinic rays or radiation. (Also called).

In general formula (I),
R ^{1 to} R ¹³ each independently represent a hydrogen atom or a substituent, and may be bonded to each other to form a ring.
Z is a single bond or a divalent linking group.

R ^{1 to} R ¹³ are each independently a hydrogen atom or a substituent, and the substituent may be any, and is not particularly limited. For example, a halogen atom, an alkyl group (a cycloalkyl group, a bicycloalkyl group, Including tricycloalkyl groups), alkenyl groups (including cycloalkenyl groups and bicycloalkenyl groups), alkynyl groups, aryl groups, heterocyclic groups (also referred to as heterocyclic groups), cyano groups, hydroxyl groups, nitro groups , Carboxyl group, alkoxy group, aryloxy group, silyloxy group, heterocyclic oxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group (including anilino group), ammonio group, acylamino Group, aminocarbonylamino group, alkoxycal Nylamino group, aryloxycarbonylamino group, sulfamoylamino group, alkyl and arylsulfonylamino group, mercapto group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, sulfo group, alkyl and arylsulfinyl group, alkyl and Arylsulfonyl group, acyl group, aryloxycarbonyl group, alkoxycarbonyl group, carbamoyl group, aryl and heterocyclic azo group, imide group, phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, phosphono group, Examples include silyl groups, hydrazino groups, ureido groups, boronic acid groups (—B (OH) ₂ ), phosphato groups (—OPO (OH) ₂ ), sulfato groups (—OSO ₃ H), and other known substituents. As mentioned.

Two of R ^{1 to} R ¹³ may jointly form a ring (aromatic or non-aromatic hydrocarbon ring or heterocyclic ring). Examples of the combination of two or more of R ^{1 to} R ^{13 that} form a ring include R ¹ and R ¹³ , and R ⁸ and R ⁹ .
The ring to be formed may be a polycyclic fused ring. Specific examples of the ring include, for example, a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, fluorene ring, triphenylene ring, naphthacene ring, biphenyl ring, pyrrole ring, furan ring, thiophene ring, imidazole ring, oxazole ring, thiazole ring, Pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, indolizine ring, indole ring, benzofuran ring, benzothiophene ring, isobenzofuran ring, quinolidine ring, quinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring, quinoxazoline ring, isoquinoline ring Carbazole ring, phenanthridine ring, acridine ring, phenanthroline ring, thianthrene ring, chromene ring, xanthene ring, phenoxathiin ring, phenothiazine ring, and phenazine ring. ) Can also be formed.

R ^{1 to} R ¹³ are preferably hydrogen atoms or halogen atoms, alkyl groups (including cycloalkyl groups, bicycloalkyl groups, and tricycloalkyl groups), alkenyl groups (including cycloalkenyl groups and bicycloalkenyl groups), alkynyl groups, Aryl, cyano, hydroxyl, carboxyl, alkoxy, aryloxy, acyloxy, carbamoyloxy, acylamino, aminocarbonylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfamoylamino Group, alkyl and arylsulfonylamino group, alkylthio group, arylthio group, sulfamoyl group, alkyl and arylsulfonyl group, aryloxycarbonyl group, alkoxycarbonyl group, carbamoyl group, imi Group, a silyl group, a ureido group.

More preferably, R ^{1 to} R ¹³ are a hydrogen atom or a halogen atom, an alkyl group (including a cycloalkyl group, a bicycloalkyl group, and a tricycloalkyl group), a cyano group, a hydroxyl group, an alkoxy group, an acyloxy group, an acylamino group, and amino. A carbonylamino group, an alkoxycarbonylamino group, an alkyl and arylsulfonylamino group, an alkylthio group, a sulfamoyl group, an alkyl and arylsulfonyl group, an alkoxycarbonyl group, and a carbamoyl group.

Furthermore, R ^{1 to} R ¹³ are particularly preferably a hydrogen atom or an alkyl group (including a cycloalkyl group, a bicycloalkyl group, and a tricycloalkyl group), a cyano group, a hydroxyl group, an alkoxy group, and an alkylsulfonyl group.
The substituent as R ^{1 to} R ¹³ preferably has 20 or less carbon atoms, and more preferably 15 or less carbon atoms.

Z represents a single bond or a divalent linking group, and examples of the divalent linking group include a single bond, an alkylene group, an arylene group, a carbonyl group, a sulfonyl group, a carbonyloxy group, a carbonylamino group, a sulfonylamide group, Ether group, thioether group, amino group, disulfide group, acyl group, alkylsulfonyl group, —CH═CH—, —C≡C—, aminocarbonylamino group, aminosulfonylamino group, etc. May be. These substituents are the same as the substituents shown for R1 to R13 above.
The connection as Z preferably has 15 or less carbon atoms, more preferably 10 or less carbon atoms.

  Z is preferably a single bond, an alkylene group, a carbonyl group, a sulfonyl group, an ester group, an ether group or a thioether group, and particularly preferably a single bond, an alkylene group, a carbonyl group or a sulfonyl group.

The sulfonium salt (B) having a cation represented by the general formula (I) has a counter anion. As an anion, an organic anion is desirable. An organic anion represents an anion containing at least one carbon atom. Furthermore, the organic anion is preferably a non-nucleophilic anion. A non-nucleophilic anion is an anion that has an extremely low ability to cause a nucleophilic reaction, and is an anion that can suppress degradation over time due to an intramolecular nucleophilic reaction.
Examples of the non-nucleophilic anion include a sulfonate anion, a carboxylate anion, a sulfonylimide anion, a bis (alkylsulfonyl) imide anion, and a tris (alkylsulfonyl) methyl anion.
Examples of the non-nucleophilic sulfonate anion include an alkyl sulfonate anion, an aryl sulfonate anion, and a camphor sulfonate anion. Examples of the non-nucleophilic carboxylate anion include an alkylcarboxylate anion, an arylcarboxylate anion, and an aralkylcarboxylate anion.

The alkyl moiety in the alkyl sulfonate anion may be an alkyl group or a cycloalkyl group, and preferably an alkyl group having 1 to 30 carbon atoms and a cycloalkyl group having 3 to 30 carbon atoms, such as a methyl group or an ethyl group. Group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group Tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, adamantyl group, norbornyl group, boronyl group and the like.
The aryl group in the aryl sulfonate anion is preferably an aryl group having 6 to 14 carbon atoms, such as a phenyl group, a tolyl group, and a naphthyl group.

  Examples of the substituent of the alkyl group, cycloalkyl group and aryl group in the alkyl sulfonate anion and aryl sulfonate anion include, for example, a nitro group, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), carboxyl group, Hydroxyl group, amino group, cyano group, alkoxy group (preferably 1 to 5 carbon atoms), cycloalkyl group (preferably 3 to 15 carbon atoms), aryl group (preferably 6 to 14 carbon atoms), alkoxycarbonyl group (preferably May include 2 to 7 carbon atoms, an acyl group (preferably 2 to 12 carbon atoms), an alkoxycarbonyloxy group (preferably 2 to 7 carbon atoms), and the like. About the aryl group and ring structure which each group has, an alkyl group (preferably C1-C15) can further be mentioned as a substituent.

Examples of the alkyl moiety in the alkylcarboxylate anion include the same alkyl group and cycloalkyl group as in the alkylsulfonate anion. Examples of the aryl group in the arylcarboxylate anion include the same aryl groups as in the arylsulfonate anion. The aralkyl group in the aralkyl carboxylate anion is preferably an aralkyl group having 6 to 12 carbon atoms, such as a benzyl group, a phenethyl group, a naphthylmethyl group, a naphthylethyl group, and a naphthylmethyl group.
Examples of the alkyl group, cycloalkyl group, aryl group and aralkyl group substituent in the alkylcarboxylate anion, arylcarboxylate anion and aralkylcarboxylate anion include, for example, the same halogen atom, alkyl group as in the arylsulfonate anion, A cycloalkyl group, an alkoxy group, an alkylthio group, etc. can be mentioned. Examples of the sulfonylimide anion include saccharin anion.

The alkyl group in the bis (alkylsulfonyl) imide anion and tris (alkylsulfonyl) methyl anion is preferably an alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, An isobutyl group, a sec-butyl group, a pentyl group, a neopentyl group, and the like can be given. Examples of the substituent for these alkyl groups include a halogen atom, an alkyl group substituted with a halogen atom, an alkoxy group, and an alkylthio group.
Examples of other non-nucleophilic anions include fluorinated phosphorus, fluorinated boron, and fluorinated antimony.

As a counter anion of the sulfonium salt (B) having a cation represented by the general formula (I), a sulfonate anion is preferable, and an aryl sulfonic acid is more preferable.
Specific examples of the counter anion include (B2-1) methanesulfonate anion, (B2-2) trifluoromethanesulfonate anion, (B2-3) pentafluoroethanesulfonate anion, and (B2-4) heptafluoropropane. Sulfonate anion, (B2-5) perfluorobutane sulfonate anion, (B2-6) perfluorohexane sulfonate anion, (B2-7) perfluorooctane sulfonate anion, (B2-8) pentafluorobenzene sulfonate Anion, (B2-9) 3,5-bistrifluoromethylbenzenesulfonate anion, (B2-10) 2,4,6-triisopropylbenzenesulfonate anion, (B2-11) perfluoroethoxyethanesulfonate anion, (B2-12) 2,3,5,6-tetrafluoro-4-dodecyl Xylbenzenesulfonate anion, (B2-13) methanesulfonate anion, (B2-14) p-toluenesulfonate anion, (B2-15) 3,5-bistrifluorobenzenesulfonate anion, (B2-16) penta Examples thereof include a fluorobenzenesulfonic acid anion and (B2-17) 2,4,6-trimethylbenzenesulfonic acid anion.

  The anion which the sulfonium salt (B) has together with the cation represented by the general formula (I) may be monovalent or divalent. When the anion is divalent or more, the sulfonium salt (A) can have two or more cations represented by the general formula (I).

  The molecular weight of the sulfonium salt (B) having a cation represented by the general formula (I) is generally 250 to 1500, preferably 250 to 1000.

The compound of general formula (I) is obtained by oxidizing a cyclic sulfide compound with hydrogen peroxide to form a sulfoxide, reacting the diphenyl sulfoxide compound in the presence of an acid catalyst to synthesize a triphenylsulfonium salt structure, and then exchanging the salt with the desired anion. Can be synthesized.

  The content of the sulfonium salt (B) is preferably 0.1 to 20% by mass, more preferably 0.5 to 15% by mass, and further preferably 1 to 10% by mass based on the total solid content of the composition. .

  Specific examples of the cation are listed below, but are not limited thereto.

  Although the specific example of the compound (acid generator) which generate | occur | produces an acid by irradiation of actinic light or a radiation is given, it is not limited to these.

(Combination acid generator)
In the present invention, in addition to the compound (A), a compound capable of decomposing upon irradiation with actinic rays or radiation to generate an acid (acid generator) may be further used.

  The amount of the photoacid generator that can be used in combination is usually 100/0 to 20/80, preferably 100/0 to 40/60, and more preferably in molar ratio (compound (A) / other acid generator). 100/0 to 50/50.

  As such photoacid generators that can be used in combination, they are used in photocationic photoinitiators, photoinitiators of radical photopolymerization, photodecolorants of dyes, photochromic agents, or microresists. Known compounds that generate acids upon irradiation with actinic rays or radiation and mixtures thereof can be appropriately selected and used.

  Examples thereof include diazonium salts, phosphonium salts, sulfonium salts, iodonium salts, imide sulfonates, oxime sulfonates, diazodisulfones, disulfones, and o-nitrobenzyl sulfonates.

  Further, a group that generates an acid upon irradiation with these actinic rays or radiation, or a compound in which a compound is introduced into the main chain or side chain of the polymer, for example, US Pat. No. 3,849,137, German Patent No. 3914407. JP, 63-26653, JP, 55-164824, JP, 62-69263, JP, 63-146038, JP, 63-163452, JP, 62-153853, The compounds described in JP-A 63-146029 can be used.

Furthermore, compounds capable of generating an acid by light described in US Pat. No. 3,779,778, European Patent 126,712 and the like can also be used.

  Among the compounds capable of decomposing upon irradiation with actinic rays or radiation that may be used in combination, preferred compounds include compounds represented by the following general formulas (ZI), (ZII), and (ZIII). it can.

In the above general formula (ZI), R ₂₀₁ , R ₂₀₂ and R ₂₀₃ each independently represents an organic group.
The carbon number of the organic group as R ₂₀₁ , R ₂₀₂ and R ₂₀₃ is generally 1 to 30, preferably 1
~ 20.
Two of R _{201 to} R ₂₀₃ may be bonded to form a ring structure, and the ring may contain an oxygen atom, a sulfur atom, an ester bond, an amide bond, or a carbonyl group.
The two of the group formed by bonding of the R ₂₀₁ to R _203, there can be mentioned an alkylene group (e.g., butylene, pentylene).
Z ⁻ represents a non-nucleophilic anion.

Z ^- The non-nucleophilic anion as examples thereof include sulfonate anion, carboxylate anion, sulfonylimide anion, bis (alkylsulfonyl) imide anion, a tris (alkylsulfonyl) methyl anion.

  A non-nucleophilic anion is an anion that has an extremely low ability to cause a nucleophilic reaction, and is an anion that can suppress degradation over time due to an intramolecular nucleophilic reaction. This improves the temporal stability of the resist.

  Examples of the sulfonate anion include an alkyl sulfonate anion, an aryl sulfonate anion, and a camphor sulfonate anion.

  Examples of the carboxylate anion include an alkylcarboxylate anion, an arylcarboxylate anion, and an aralkylcarboxylate anion.

  The alkyl moiety in the alkyl sulfonate anion may be an alkyl group or a cycloalkyl group, and preferably an alkyl group having 1 to 30 carbon atoms and a cycloalkyl group having 3 to 30 carbon atoms, such as a methyl group or an ethyl group. Group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group Tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, adamantyl group, norbornyl group, boronyl group and the like.

  The aryl group in the aryl sulfonate anion is preferably an aryl group having 6 to 14 carbon atoms, such as a phenyl group, a tolyl group, and a naphthyl group.

  Examples of the substituent of the alkyl group, cycloalkyl group and aryl group in the alkyl sulfonate anion and aryl sulfonate anion include, for example, a nitro group, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), carboxyl group, Hydroxyl group, amino group, cyano group, alkoxy group (preferably 1 to 5 carbon atoms), cycloalkyl group (preferably 3 to 15 carbon atoms), aryl group (preferably 6 to 14 carbon atoms), alkoxycarbonyl group (preferably May include 2 to 7 carbon atoms, an acyl group (preferably 2 to 12 carbon atoms), an alkoxycarbonyloxy group (preferably 2 to 7 carbon atoms), and the like. About the aryl group and ring structure which each group has, an alkyl group (preferably C1-C15) can further be mentioned as a substituent.

  Examples of the alkyl moiety in the alkylcarboxylate anion include the same alkyl group and cycloalkyl group as in the alkylsulfonate anion.

  Examples of the aryl group in the arylcarboxylate anion include the same aryl groups as in the arylsulfonate anion.

  The aralkyl group in the aralkyl carboxylate anion is preferably an aralkyl group having 6 to 12 carbon atoms, such as a benzyl group, a phenethyl group, a naphthylmethyl group, a naphthylethyl group, and a naphthylmethyl group.

  Examples of the alkyl group, cycloalkyl group, aryl group and aralkyl group substituent in the alkylcarboxylate anion, arylcarboxylate anion and aralkylcarboxylate anion include, for example, the same halogen atom, alkyl group as in the arylsulfonate anion, A cycloalkyl group, an alkoxy group, an alkylthio group, etc. can be mentioned.

  Examples of the sulfonylimide anion include saccharin anion.

  The alkyl group in the bis (alkylsulfonyl) imide anion and tris (alkylsulfonyl) methyl anion is preferably an alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, An isobutyl group, a sec-butyl group, a pentyl group, a neopentyl group, and the like can be given. Examples of the substituent of these alkyl groups include a halogen atom, an alkyl group substituted with a halogen atom, an alkoxy group, and an alkylthio group, and an alkyl group substituted with a fluorine atom is preferable.

  Examples of other non-nucleophilic anions include fluorinated phosphorus, fluorinated boron, and fluorinated antimony.

Examples of the non-nucleophilic anion of Z ⁻ include an alkanesulfonic acid anion in which the α-position of the sulfonic acid is substituted with a fluorine atom, an arylsulfonic acid anion substituted with a fluorine atom or a group having a fluorine atom, and an alkyl group having a fluorine atom And a tris (alkylsulfonyl) methide anion in which the alkyl group is substituted with a fluorine atom. The non-nucleophilic anion is particularly preferably a perfluoroalkanesulfonic acid anion having 4 to 8 carbon atoms, a benzenesulfonic acid anion having a fluorine atom, most preferably nonafluorobutanesulfonic acid anion, perfluorooctanesulfonic acid anion, penta Fluorobenzenesulfonate anion, 3,5-bis (trifluoromethyl) benzenesulfonate anion.

Examples of the organic group as R ₂₀₁ , R ₂₀₂ and R ₂₀₃ include, for example, a compound described later (Z1-1
), (Z1-2) and (Z1-3), the corresponding groups.

In addition, the compound which has two or more structures represented by general formula (ZI) may be sufficient. For example, the general formula at least one of R ₂₀₁ to R ₂₀₃ of a compound represented by (ZI) is, at least one bond with structure of R ₂₀₁ to R ₂₀₃ of another compound represented by formula (ZI) It may be a compound.

  More preferable examples of the (ZI) component include compounds (Z1-1), (Z1-2), and (Z1-3) described below.

Compound (Z1-1) is at least one of the aryl groups R ₂₀₁ to R ₂₀₃ in formula (ZI), arylsulfonium compounds, namely, compounds containing an arylsulfonium as a cation.

In the arylsulfonium compound, all of R _{201 to} R ₂₀₃ may be an aryl group, or R ₂₀₁
Some of to R ₂₀₃ is an aryl group and the remainder may be an alkyl group or a cycloalkyl group.

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

  The aryl group of the arylsulfonium compound is preferably a phenyl group or a naphthyl group, and more preferably a phenyl group. When the arylsulfonium compound has two or more aryl groups, the two or more aryl groups may be the same or different.

  The alkyl group or cycloalkyl group that the arylsulfonium compound has as necessary is preferably a linear or branched alkyl group having 1 to 15 carbon atoms and a cycloalkyl group having 3 to 15 carbon atoms, such as a methyl group, Examples thereof include an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, a t-butyl group, a cyclopropyl group, a cyclobutyl group, and a cyclohexyl group.

Aryl group, alkyl group of R ₂₀₁ to R _203, cycloalkyl group, an alkyl group (for example, 1 to 15 carbon atoms), a cycloalkyl group (for example, 3 to 15 carbon atoms), an aryl group (for example, 6 to 14 carbon atoms) , An alkoxy group (for example, having 1 to 15 carbon atoms), a halogen atom, a hydroxyl group, or a phenylthio group may be substituted. Preferred substituents are linear or branched alkyl groups having 1 to 12 carbon atoms, cycloalkyl groups having 3 to 12 carbon atoms, and linear, branched or cyclic alkoxy groups having 1 to 12 carbon atoms, most preferably carbon. These are an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms. The substituent may be substituted with any one of the three R _{201 to} R ₂₀₃ , or may be substituted with all three. When R _{201 to} R ₂₀₃ are an aryl group, the substituent is preferably substituted at the p-position of the aryl group.

Next, the compound (Z1-2) will be described.
Compound (Z1-2) is a compound in the case where R _{201 to} R ₂₀₃ in formula (ZI) each independently represents an organic group not containing an aromatic ring. Here, the aromatic ring includes an aromatic ring containing a hetero atom.

The organic group having no aromatic ring as R ₂₀₁ to R ₂₀₃ generally has 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms.

R _{201 to} R ₂₀₃ are preferably each independently an alkyl group, a cycloalkyl group, an allyl group,
A vinyl group, more preferably a linear or branched 2-oxoalkyl group, a 2-oxocycloalkyl group, an alkoxycarbonylmethyl group, and most preferably a linear or branched 2-oxoalkyl group.

The alkyl group and cycloalkyl group of R ₂₀₁ to R _203, preferably a linear or branched alkyl group having 1 to 10 carbon atoms (e.g., methyl group, ethyl group, propyl group, butyl group, pentyl group), carbon Examples thereof include cycloalkyl groups of several 3 to 10 (cyclopentyl group, cyclohexyl group, norbornyl group). More preferred examples of the alkyl group include a 2-oxoalkyl group and an alkoxycarbonylmethyl group. More preferred examples of the cycloalkyl group include a 2-oxocycloalkyl group.

The 2-oxoalkyl group may be either linear or branched, and a group having> C = O at the 2-position of the above alkyl group is preferable.
The 2-oxocycloalkyl group is preferably a group having> C═O at the 2-position of the cycloalkyl group.

  The alkoxy group in the alkoxycarbonylmethyl group is preferably an alkyl group having 1 to 5 carbon atoms (methyl group, ethyl group, propyl group, butyl group, pentyl group).

R _{201 to} R ₂₀₃ may be further substituted with a halogen atom, an alkoxy group (for example, having 1 to 5 carbon atoms), a hydroxyl group, a cyano group, or a nitro group.

Two members out of R _{201 to} R ₂₀₃ may combine to form a ring structure, and the ring may contain an oxygen atom, a sulfur atom, an ester bond, an amide bond, or a carbonyl group. The two of the group formed by bonding of the R ₂₀₁ to R _203, there can be mentioned an alkylene group (e.g., butylene, pentylene).

  The compound (Z1-3) is a compound represented by the following general formula (Z1-3), and is a compound having a phenacylsulfonium salt structure.

R _1c to R _5c each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkoxy group or a halogen atom.
R _6c and R _7c represent a hydrogen atom, an alkyl group, or a cycloalkyl group.
R _x and R _y independently represents an alkyl group, a cycloalkyl group, an allyl group or a vinyl group.

Any two or more of R _{1c to} R _5c , and R _x and R _y may be bonded to each other to form a ring structure, and this ring structure includes an oxygen atom, a sulfur atom, an ester bond, and an amide bond. May be included.

Zc ⁻ represents a non-nucleophilic anion, and examples thereof include the same non-nucleophilic anion as X ⁻ in the general formula (ZI).

The alkyl group as R _{1c to} R _{5c may} be either linear or branched, for example, an alkyl group having 1 to 20 carbon atoms, preferably a linear or branched alkyl group having 1 to 12 carbon atoms ( Examples thereof include a methyl group, an ethyl group, a linear or branched propyl group, a linear or branched butyl group, and a linear or branched pentyl group. The cycloalkyl group is, for example, a cyclic group having 3 to 8 carbon atoms. An alkyl group (for example, a cyclopentyl group, a cyclohexyl group) can be mentioned.

The alkoxy group as R _{1c to} R _{5c may} be linear, branched or cyclic, for example, an alkoxy group having 1 to 10 carbon atoms, preferably a linear or branched alkoxy group having 1 to 5 carbon atoms. (For example, methoxy group, ethoxy group, linear or branched propoxy group, linear or branched butoxy group, linear or branched pentoxy group), C3-C8 cyclic alkoxy group (for example, cyclopentyloxy group, cyclohexyloxy group) ).

Preferably, any one of R _{1c to} R _5c is a linear or branched alkyl group, a cycloalkyl group, or a linear, branched or cyclic alkoxy group, and more preferably the sum of the carbon number of R _1c to R _5c is 2 to 2. 15. Thereby, solvent solubility improves more and generation | occurrence | production of a particle is suppressed at the time of a preservation | save.

_Examples of the alkyl group and cycloalkyl group as R _x and R _y include the same alkyl group and cycloalkyl group as in R _{1c to} R _5c, and include a 2-oxoalkyl group, a 2-oxocycloalkyl group, an alkoxy group. A carbonylmethyl group is more preferred.

Examples of the 2-oxoalkyl group and 2-oxocycloalkyl group include a group having> C═O at the 2-position of the alkyl group or cycloalkyl group as R _{1c to} R _5c .

Examples of the alkoxy group in the alkoxycarbonylmethyl group include the same alkoxy groups as in R _{1c to} R _5c .

Examples of the group formed by combining R _x and R _y include a butylene group and a pentylene group.

R _x and R _y are preferably an alkyl group or cycloalkyl group having 4 or more carbon atoms, more preferably 6 or more, and still more preferably 8 or more alkyl groups or cycloalkyl groups.

In formula (ZII) and (ZIII), R ₂₀₄ ~R ₂₀₇ each independently represents an aryl group, an alkyl group or a cycloalkyl group.

Phenyl group and a naphthyl group are preferred as the aryl group of R ₂₀₄ to R _207, more preferably a phenyl group.

The alkyl group and cycloalkyl group in R _{204 to} R ₂₀₇ are preferably a linear or branched alkyl group having 1 to 10 carbon atoms (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group), carbon Examples thereof include cycloalkyl groups of several 3 to 10 (cyclopentyl group, cyclohexyl group, norbornyl group).

Examples of the substituent that R _{204 to} R ₂₀₇ may have include an alkyl group (for example, 1 to 15 carbon atoms), a cycloalkyl group (for example, 3 to 15 carbon atoms), and an aryl group (for example, 6 carbon atoms).
To 15), alkoxy groups (for example, having 1 to 15 carbon atoms), halogen atoms, hydroxyl groups, phenylthio groups, and the like.

Z ⁻ represents a non-nucleophilic anion, and examples thereof include the same as the non-nucleophilic anion of Z ^{− in} formula (ZI).

  Of the compounds that decompose upon irradiation with actinic rays or radiation that may be used in combination, preferred compounds further include compounds represented by the following general formulas (ZIV), (ZV), and (ZVI). be able to.

In general formulas (ZIV) to (ZVI), Ar ₃ and Ar ₄ each independently represents an aryl group.

R ₂₀₆ , R ₂₀₇ and R _{208 each} represents an alkyl group, a cycloalkyl group or an aryl group.
A represents an alkylene group, an alkenylene group or an arylene group.

Among the compounds that may be used in combination and decompose upon irradiation with actinic rays or radiation to generate an acid, compounds represented by general formulas (ZI) to (ZIII) are more preferable.
Further, as a compound that decomposes upon irradiation with actinic rays or radiation that may be used in combination, a compound that generates a sulfonic acid having one sulfonic acid group is preferable, and a monovalent perfluoroalkanesulfone is more preferable. A compound that generates an acid, or a compound that generates an aromatic sulfonic acid substituted with a fluorine atom or a group containing a fluorine atom, particularly preferably a sulfonium salt of monovalent perfluoroalkanesulfonic acid.

  Of the compounds that decompose upon irradiation with actinic rays or radiation that may be used in combination, particularly preferred examples are listed below.

[3] Alkali-soluble resin In addition to the acid-decomposable polymer (A), the resist composition of the present invention can contain an alkali-soluble resin that does not contain an acid-decomposable group. Will improve.

An alkali-soluble resin that does not contain an acid-decomposable group (hereinafter simply referred to as “alkali-soluble resin”) is a resin that is soluble in an alkali developer, and is an acid-decomposable group in the acid-decomposable polymer (A) of the present invention. In addition to resins that are all deprotected in terms of form, polyhydroxystyrene, novolak resins and derivatives thereof can be preferably exemplified. In addition to these, a copolymer resin containing a p-hydroxystyrene unit can also be used if it is alkali-soluble.

  In the present invention, the addition amount in the composition of the alkali-soluble resin not containing the acid-decomposable group is preferably 2 to 60% by mass, more preferably, based on the total mass of the solid content of the composition. It is 5-30 mass%.

[4] (C) Organic Basic Compound The positive resist composition of the present invention preferably contains (C) a basic compound in order to reduce a change in performance over time from exposure to heating.
Preferable structures include structures represented by the following formulas (A) to (E).

In formulas (A) to (E), R ²⁵⁰ , R ²⁵¹ and R ²⁵² are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or 6 to 6 carbon atoms. 20 aryl groups, wherein R ²⁵⁰ and R ²⁵¹ may combine with each other to form a ring. Examples of the alkyl group and cycloalkyl group having a substituent include an aminoalkyl group having 1 to 20 carbon atoms, an aminocycloalkyl group having 3 to 20 carbon atoms, a hydroxyalkyl group having 1 to 20 carbon atoms, and a 3 to 20 carbon atom. A hydroxycycloalkyl group is preferred.
These may contain an oxygen atom, a sulfur atom, or a nitrogen atom in the alkyl chain.
R ²⁵³ , R ²⁵⁴ , R ²⁵⁵ and R ²⁵⁶ each independently represent an alkyl group or cycloalkyl group having 1 to 20 carbon atoms.

  Preferred compounds include guanidine, aminopyrrolidine, pyrazole, pyrazoline, piperazine, aminomorpholine, aminoalkylmorpholine, piperidine, and more preferred compounds include imidazole structure, diazabicyclo structure, onium hydroxide structure, onium carboxylate structure, Examples thereof include a compound having a trialkylamine structure, an aniline structure or a pyridine structure, an alkylamine derivative having a hydroxyl group and / or an ether bond, and an aniline derivative having a hydroxyl group and / or an ether bond. These compounds may have a substituent.

Examples of the compound having an imidazole structure include imidazole, 2,4,5-triphenylimidazole, benzimidazole, and the like. The compound having a diazabicyclo structure is 1,4-diazabicyclo [2,2,2] octane, 1,5-diazabicyclo [4,3,0] noner-5-ene, 1,8-diazabicyclo [5,4,0]. Undecar 7-ene. Examples of the compound having an onium hydroxide structure include triarylsulfonium hydroxide, phenacylsulfonium hydroxide, sulfonium hydroxide having a 2-oxoalkyl group, specifically triphenylsulfonium hydroxide, tris (t-butylphenyl) sulfonium. Examples thereof include hydroxide, bis (t-butylphenyl) iodonium hydroxide, phenacylthiophenium hydroxide, and 2-oxopropylthiophenium hydroxide. The compound having an onium carboxylate structure is a compound having an onium hydroxide structure in which the anion moiety is converted to a carboxylate, and examples thereof include acetate, adamantane-1-carboxylate, and perfluoroalkylcarboxylate. Examples of the compound having a trialkylamine structure include tri (n-butyl) amine and tri (n-octyl) amine. Examples of aniline compounds include 2,6-diisopropylaniline and N, N-dimethylaniline. Examples of the alkylamine derivative having a hydroxyl group and / or an ether bond include ethanolamine, diethanolamine, triethanolamine, and tris (methoxyethoxyethyl) amine. Examples of aniline derivatives having a hydroxyl group and / or an ether bond include N, N-bis (hydroxyethyl) aniline.

  These basic compounds are used alone or in combination of two or more. The usage-amount of a basic compound is 0.001-10 mass% normally on the basis of solid content of a positive resist composition, Preferably it is 0.01-5 mass%. In order to obtain a sufficient addition effect, 0.001% by mass or more is preferable, and 10% by mass or less is preferable in terms of sensitivity and developability of the non-exposed area.

[5] (D) Fluorine-based and / or silicon-based surfactant The positive resist composition of the present invention further comprises (D) a fluorine-based and / or silicon-based surfactant (fluorine-based surfactant and silicon-based interface). It is preferable to contain any one or two or more of activators and surfactants containing both fluorine atoms and silicon atoms.
When the positive resist composition of the present invention contains the surfactant (D), a resist having good sensitivity and resolution and less adhesion and development defects when using an exposure light source of 250 nm or less, particularly 220 nm or less. A pattern can be given.

As these (D) surfactants, for example, JP-A-62-36663, JP-A-61-226746, JP-A-61-226745, JP-A-62-170950, JP-A-62-170950 are disclosed. No. 63-34540, JP-A-7-230165, JP-A-8-62834, JP-A-9-54432, JP-A-9-5988, JP-A 2002-277862, US Pat. No. 5,405,720 , No. 5,360,692, No. 5,529,881, No. 5,296,330, No. 5,436,098, No. 5,576,143, No. 5,294,511, No. 5,824,451 The following commercially available surfactants can also be used as they are.
Examples of commercially available surfactants that can be used include EFTOP EF301 and EF303 (manufactured by Shin-Akita Kasei Co., Ltd.), Florard FC430 and 431 (manufactured by Sumitomo 3M Co., Ltd.), MegaFuck F171, F173, F176, F189, and R08. (Dainippon Ink Chemical Co., Ltd.), Surflon S-382, SC101, 102, 103, 104, 105, 106 (Asahi Glass Co., Ltd.), Troisol S-366 (Troy Chemical Co., Ltd.), etc. Fluorine type surfactant or silicon type surfactant can be mentioned. Polysiloxane polymer KP-341 (manufactured by Shin-Etsu Chemical Co., Ltd.) can also be used as a silicon-based surfactant.

In addition to the known surfactants described above, the surfactant is derived from a fluoroaliphatic compound produced by a telomerization method (also called telomer method) or an oligomerization method (also called oligomer method). A surfactant using a polymer having a fluoroaliphatic group can be used. Fluoroaliphatic compounds are disclosed in JP-A-2002.
It can be synthesized by the method described in Japanese Patent No. -90991.
As the polymer having a fluoroaliphatic group, a copolymer of a monomer having a fluoroaliphatic group and (poly (oxyalkylene)) acrylate and / or (poly (oxyalkylene)) methacrylate is preferable and distributed irregularly. Or may be block copolymerized. Examples of the poly (oxyalkylene) group include a poly (oxyethylene) group, a poly (oxypropylene) group, a poly (oxybutylene) group, and the like, and a poly (oxyethylene, oxypropylene, and oxyethylene group). A unit having different chain lengths in the same chain length, such as a block link) or poly (block link of oxyethylene and oxypropylene) may be used. Furthermore, a copolymer of a monomer having a fluoroaliphatic group and (poly (oxyalkylene)) acrylate (or methacrylate) is not only a binary copolymer but also a monomer having two or more different fluoroaliphatic groups, Further, it may be a ternary or higher copolymer obtained by simultaneously copolymerizing two or more different (poly (oxyalkylene)) acrylates (or methacrylates).

Examples of commercially available surfactants include Megafac F178, F-470, F-473, F-475, F-476, and F-472 (Dainippon Ink Chemical Co., Ltd.). Further, a copolymer of an acrylate (or methacrylate) having a C ₆ F ₁₃ group and (poly (oxyalkylene)) acrylate (or methacrylate), an acrylate (or methacrylate) having a C ₆ F ₁₃ group and (poly (oxy) (Ethylene)) acrylate (or methacrylate) and (poly (oxypropylene)) acrylate (or methacrylate) copolymer, acrylate (or methacrylate) and (poly (oxyalkylene)) acrylate having C ₈ F ₁₇ groups (or Copolymer of acrylate (or methacrylate), (poly (oxyethylene)) acrylate (or methacrylate), and (poly (oxypropylene)) acrylate (or methacrylate) having a C ₈ F ₁₇ group Coalesce, etc. Can.
(D) The amount of the surfactant used is preferably 0.0001 to 2% by mass, more preferably 0.001 to 1% by mass, based on the total amount of the positive resist composition (excluding the solvent).

[6] Solvent The composition of the present invention is dissolved in a solvent that dissolves the above-described components and the components described later, and is applied onto a support. Solvents used here include ethylene dichloride, cyclohexanone, cyclopentanone, 2-heptanone, γ-butyrolactone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, ethylene glycol monoethyl ether acetate , Propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, toluene, ethyl acetate, methyl lactate, ethyl lactate, methyl methoxypropionate, ethyl ethoxypropionate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, N, N-dimethyl Formamide, dimethyl sulfoxide, N-methylpyrrolidone, tetrahydrofuran and the like are preferable. These organic solvents can be used individually by 1 type or in combination of 2 or more types.

  Among these, preferable organic solvents include 2-heptanone, γ-butyrolactone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl. Examples include ether acetate, methyl lactate, ethyl lactate, methyl methoxypropionate, ethyl ethoxypropionate, N-methylpyrrolidone, and tetrahydrofuran.

Among the above, it is more preferable to contain propylene glycol monomethyl ether acetate as a solvent. In addition to propylene glycol monomethyl ether acetate, it is preferable to further contain propylene glycol monomethyl ether from the viewpoint of line edge roughness and performance change reduction due to PED in vacuum.

[7] Pattern Forming Method The positive resist composition according to the present invention is applied to a substrate (eg, silicon / silicon dioxide coating) used for manufacturing a precision integrated circuit element by an appropriate coating method such as a spinner or a coater. After coating, a resist film is formed by drying or pre-baking, exposing through a predetermined mask, preferably post-baking, and developing to obtain a good resist pattern. An antireflection film may be provided on the substrate in advance.
Here, as the exposure light, for example, far ultraviolet light having a wavelength of 250 nm or less, specifically, KrF excimer laser (248 nm), ArF excimer laser (193 nm), F ₂ excimer laser (157 nm), EUV (13 nm), X And KrF excimer laser, electron beam, X-ray and EUV are particularly preferable.

  In the pattern formation by the positive resist composition of the present invention, as an alkaline developer used for development, inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, Primary amines such as ethylamine and n-propylamine, secondary amines such as diethylamine and di-n-butylamine, tertiary amines such as triethylamine and methyldiethylamine, alcohol amines such as dimethylethanolamine and triethanolamine Alkaline aqueous solutions such as quaternary ammonium salts such as tetramethylammonium hydroxide and tetraethylammonium hydroxide, and cyclic amines such as pyrrole and pihelidine can be used.

Furthermore, an appropriate amount of alcohol or surfactant may be added to the alkaline aqueous solution.
The alkali concentration of the alkali developer is usually from 0.1 to 20% by mass.
The pH of the alkali developer is usually from 10.0 to 15.0.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

Synthesis Example 1 Synthesis of Macromonomer 1

In a reaction vessel, 76.9 g (0.4 mol) of p- (1-ethoxyethyl) styrene (manufactured by Tosoh Corporation) and 76.9 g (0.6 mol) of t-butyl acrylate were dissolved in 250 ml of tetrahydrofuran, and the system was stirred. Nitrogen gas was allowed to flow through. Thereto were added 18.42 g (0.2 mol) of 3-mercaptoacetic acid and 12.42 g (0.05 mol) of a polymerization initiator V-65 (manufactured by Wako Pure Chemical Industries, Ltd.), and the reaction solution was heated to 60 ° C. After stirring with heating for 10 hours, the reaction solution was allowed to cool to room temperature and dropped into 3 L of distilled water to precipitate the polymer. The filtered solid was dissolved in 150 ml of acetone, dropped again into 3 L of distilled water, and the filtered solid was dried under reduced pressure to obtain 135.3 g of an intermediate.
100 g of the intermediate obtained above, 9.41 g of triethylamine, 8.94 g of glycidyl acrylate, 0.1 g of hydroquinone and 200 ml of methyl ethyl ketone were added to the reaction vessel, and the mixture was heated to 60 ° C. and stirred for 2 hours. The reaction solution was allowed to cool to room temperature and dropped into 3 L of distilled water. The filtered solid was dissolved in 150 ml of acetone, dropped again into 3 L of distilled water, and the filtered solid was dried under reduced pressure to obtain 120.3 g of macromonomer 1. The weight average molecular weight by GPC / MALLS (multi-angle light scattering) was 4300. From the 1H-NMR analysis, it was found that the ratio of p- (1-ethoxyethyl) styrene / t-butyl acrylate was 43/57, and the double bond abundance ratio was 0.215 mmol / g. Therefore, the above-described n _b (average degree of polymerization of the portion to be a branched chain) is 27.6.

(Synthesis Example 2) Synthesis of Polymer A-1

2.98 g (0.016 mol) of p- (1-ethoxyethyl) styrene (Tosoh), 2.63 g (0.021 mol) of t-butyl acrylate, 65.12 g of macromonomer 1 (average double) 0.014 mol) was dissolved in 150 ml of tetrahydrofuran, and nitrogen gas was allowed to flow through the system while stirring. 0.89 g (0.0036 mol) of polymerization initiator V-65 (manufactured by Wako Pure Chemical Industries, Ltd.) was added thereto, and the reaction solution was heated to 60 ° C. After stirring with heating for 10 hours, the reaction solution was allowed to cool to room temperature and dropped into 3 L of distilled water to precipitate the polymer. The filtered solid was dissolved in 150 ml of acetone, dropped again into 3 L of distilled water and filtered to obtain a solid. This solid was added to a reaction vessel, 200 ml of methanol, 20 ml of distilled water and 1.0 g of p-toluenesulfonic acid were added, heated to 60 ° C. and stirred for 3 hours. Thereafter, the reaction solution was dropped into 3 L of distilled water, the filtered solid was dissolved in 150 ml of acetone, and the filtered solid was dropped again into 3 L of distilled water and dried under reduced pressure to obtain 38.4 g of a polymer. Thereafter, this polymer was dissolved in PGMEA to obtain a 30% by mass solution. This polymer is designated as A-1. The weight average molecular weight by GPC / MALLS was 32000. From 1H-NMR analysis, the ratio of p-hydroxystyrene / t-butyl acrylate / macromonomer 1 was 31/41/28, and the overall ratio of p-hydroxystyrene / t-butyl acrylate was 41/59. Therefore, the above-mentioned n _m (average degree of polymerization of the main portion (main chain)) is 38.0, and x (average number of branch points in one polymer molecule) is 10.6.

Synthesis Example 3 Synthesis of Multifunctional Initiator 1

In a reaction vessel, 73.10 g (0.2 mol) of 2,2-6,6-tetramethyl-1- (2-hydroxy-1-phenylethoxy) -piperidine and ml of tetrahydrofuran were added, and nitrogen was added to the system while stirring. Gas was flowed and the solution was cooled to -40 ° C. Thereto was added 4.8 g (0.2 mol) of sodium hydride, and the mixture was further stirred for 20 minutes. Thereafter, 20.24 g (0.045 mol) of 1,2,4,5-tetrakis (bromomethyl) benzene was added, and the reaction solution was gradually warmed to room temperature. Thereafter, a saturated aqueous ammonium chloride solution was added to stop and neutralize the reaction, and extraction was performed with 300 ml of ethyl acetate and 100 ml of distilled water. Magnesium sulfate was added to the ethyl acetate layer for dehydration, the solvent was distilled off, and the residue was purified by silica gel column chromatography to obtain 185.3 g of polyfunctional initiator 1.
The 2,2-6,6-tetramethyl-1- (2-hydroxy-1-phenylethoxy) -piperidine described above is journaled except that the raw material is changed from styrene to p- (1-ethoxyethyl) styrene. of American Chemical Society 1994, Vol. 116, p.11185.

  The structure of 2,2-6,6-tetramethyl-1- (2-hydroxy-1-phenylethoxy) -piperidine is as follows:

(Synthesis Example 4) Synthesis of Polymer A-2

3.18 g (0.002 mol) of polyfunctional initiator 1 and 38.45 g (0.2 mol) of p- (1-ethoxyethyl) styrene (manufactured by Tosoh) were added to the reaction vessel, and the system was stirred. Nitrogen gas was flowed and the reaction solution was heated to 130 ° C. After 10 hours of heating and stirring, the reaction solution was allowed to cool to room temperature. Further, 100 ml of ethyl acetate, 20 ml of methanol, 5 ml of distilled water and 0.5 g of p-toluenesulfonic acid were added, and the reaction solution was heated to 60 ° C. and stirred for 2 hours. Thereafter, the reaction solution was dropped into 2 L of distilled water to precipitate the polymer. The filtered solid was dissolved in 100 ml of acetone, dropped again into 2 L of distilled water, filtered, and dried under reduced pressure to obtain 23.7 g of a powder. 65.1 g of this powder was dissolved in 300 g of PGMEA, this solution was depressurized to 60 mm and 20 mmHg, and about 60 g of the solvent was distilled off together with water remaining in the system. After cooling to 20 ° C., 16.03 g of 2-cyclohexaneethanol, 12.52 g of t-butoxyvinyl ether and 0.5 g of p-toluenesulfonic acid pyridinium salt were added, and the mixture was stirred at room temperature for 4 hours. Thereafter, 0.4 g of triethylamine was added for neutralization, and the washing operation was performed 3 times with 100 g of ethyl acetate and 100 g of water. Thereafter, the amount of the solvent was adjusted to obtain a 30% by mass polymer solution. This polymer is designated as A-2. The weight average molecular weight measured by GPC / MALLS (multi-angle light scattering) was 18000, 1H and 13C-NMR analysis showed that the acetal protection rate of phenolic OH was 14.5%. Therefore, y (average of the number of branched chains (branches) extending from the core portion) is 4, n _h (average degree of polymerization of each branched chain) is 31.3, and the molecular weight of the core portion is 194.

Synthesis Example 5 Synthesis of Intermediate 1

  In a reaction vessel, 203.0 g (1.0 mol) of 5-bromo-2-hydroxybenzyl alcohol was dissolved in 500 ml of carbon tetrachloride, and 314.75 g (1.2 mol) of triphenylphosphine was added, followed by heating under reflux for a period of time. It was. The reaction solution was allowed to cool to room temperature, and then washed and separated using a saturated aqueous sodium hydrogen carbonate solution and distilled water. Magnesium sulfate was added to the organic layer for dehydration, the solvent was distilled off, and purification was performed by silica gel column chromatography to obtain 197.6 g of Intermediate 1.

Synthesis Example 6 Synthesis of Intermediate 2

  177.18 g (0.8 mol) of Intermediate 1 obtained in Synthesis Example 5 and 200 ml of pyridine were added to the reaction vessel, and 163.34 g (1.6 mol) of acetic anhydride was added dropwise over 1 hour. After the dropwise addition, the mixture was further stirred for 2 hours, further added with 500 ml of ethyl acetate, washed twice with a 0.1N HCl aqueous solution, and the organic layer was further washed with a saturated aqueous sodium bicarbonate solution and distilled water and separated. Magnesium sulfate was added to the organic layer for dehydration, the solvent was distilled off, and purification was performed by silica gel column chromatography to obtain 202.38 g of Intermediate 2.

Synthesis Example 7 Synthesis of Monomer 1

In a reaction vessel, 131.76 g (0.5 mol) of Intermediate 2 obtained in Synthesis Example 6 was dissolved in 250 ml of dehydrated tetrahydrofuran, and the system was purged with nitrogen. 5 mol% and 10 mol% of nickel (II) chloride and triphenylphosphine were added to the intermediate 2 and stirred, and 500 ml of vinylmagnesium bromide (1.0 M tetrahydrofuran solution) was added and heated to 60 ° C. Stir for 4 hours. After returning to room temperature, washing with ethyl acetate-water,
Extraction was performed. The organic layer was dehydrated with anhydrous sodium sulfate g and the solvent was distilled off. Then, the product was purified by silica gel chromatography to obtain 84.26 g of monomer 1.

(Synthesis Example 8) Synthesis of Polymer A-3

In a reaction vessel, 42.13 g (0.2 mol) of monomer 1 obtained in Synthesis Example 7 was dissolved in 100 ml of chlorobenzene, and nitrogen gas was allowed to flow through the system while stirring. Thereto, 0.2 equivalent and 0.1 equivalent of 2,2′-bipyridyl and CuCl were added to monomer 1, respectively, heated to 115 ° C. and stirred for 4 hours. The reaction solution was allowed to cool to room temperature, 100 ml of tetrahydrofuran was added, and the mixture was further stirred for 2 hours. Thereafter, the reaction solution was filtered through alumina, and the filtrate was dropped into 3 L of methanol to precipitate a polymer. The filtered solid was acetone 100
It was dissolved in ml, dropped again into 3 L of methanol, filtered, and dried under reduced pressure to obtain 27.81 g of powder. This powder was added to the reaction vessel, and further 100 ml of methanol and 0.91 g (0.01 mol) of tetramethylammonium hydroxide were added, followed by heating under reflux for 3 hours. Thereafter, 1N-HCl aqueous solution was added for neutralization, and the resulting solution was dropped into 2 L of distilled water to precipitate the polymer. The filtered solid was dissolved in 50 ml of acetone, dropped again in 2 L of distilled water, filtered, and dried under reduced pressure to obtain 19.37 g of powder. This powder was dissolved in 100 g of PGMEA, this solution was decompressed to 60 mm and 20 mmHg, and about 20 g of the solvent was distilled off with water remaining in the system.
The mixture was cooled to 20 ° C., 3.77 g of 2-phenoxyethyl vinyl ether and 1.0 g of p-toluenesulfonic acid were added, and the mixture was stirred at room temperature for 1 hour. Thereafter, 1.16 g of triethylamine was added for neutralization, and the washing operation was performed 3 times with 40 g of ethyl acetate and 40 g of water. Thereafter, the amount of the solvent was adjusted to obtain a 30% by mass polymer solution. This polymer is designated as A-3. The weight average molecular weight measured by GPC / MALLS (multi-angle light scattering) was 26000. From 1H and 13C-NMR analysis, the average molar ratio of the repeating unit having a branch point and the repeating unit having no branch point in one molecule of the polymer was 76:24. Moreover, the acetal protection rate of phenolic OH was 21.5%.

(Synthesis Example 8) Synthesis of Polymer A-4 Polymer A-4 having the following structure was synthesized in the same manner except that the vinyl ether in Synthesis Example 4 was changed. The weight average molecular weight was 15000, and the protection ratio of phenolic hydroxyl group was 37.6%. y = 4, n _h = 25.5, and the molecular weight of the core part was 194.

(Synthesis Example 9) Synthesis of linear polymers T-1 to T-4 and K Using existing methods, the polymers A-1 to A-4 of the present invention and the monomer composition / weight average molecular weight are equivalent. The linear polymers T-1 to T-4 shown below were synthesized to obtain a 30% by mass PGMEA solution. Separately, polymer K was obtained.
T-4: Weight average molecular weight 15000, protection ratio of phenolic hydroxyl group: 37.5%

(Confirmation of branching degree)
Table 1 shows the weight average molecular weight (Mw) of the polymers A-1 to A-4 and T-1 to T-4 as measured by GPC / MALLS (multi-angle light scattering), and the values of α ₁ / α _x . Where α _x , α _l
Is obtained by the following definition.
α _x : <L ₂ > ^1/2 (square root of the root mean square of radius R) obtained from GPC / MALLS of the polymers A-1 to A-4 of the present invention and a logarithm of Mw by a least square method Slope α _l : Slope obtained in the same manner as α _x for linear polymers T-1 to T-4 corresponding to A-1 to A-4, respectively.

From the results in Table 1, it can be seen that the polymers A-1 to A-4 of the present invention all have (α ₁ / α _x )> 1, and a branched chain exists in the polymer.

(Synthesis Example 10) Synthesis of 10-tolyl-9-oxothioxanthenium nonafluorobutanesulfonate (A1) 10 g of thioxanthen-9-one was stirred in 40 ml of trifluoroacetic acid, and 30% under ice cooling. A solution obtained by mixing 5.4 ml of hydrogen peroxide and 10.8 ml of trifluoroacetic acid was slowly added. Thereafter, the mixture was stirred for 30 minutes under ice cooling, and then stirred at room temperature for 1 hour. Further, the reaction solution was poured into water, and the precipitated crystals were collected by filtration. The obtained crystals were recrystallized from acetonitrile to obtain 4.6 g of a sulfoxide form. 3 g of the sulfoxide compound was stirred in 20 ml of toluene, and 3.7 ml of trifluoroacetic anhydride and 2.2 ml of nonafluorobutanesulfonic acid were added under ice cooling. The reaction was gradually warmed to room temperature and stirred for 1 hour. Diisopropyl ether was added to the reaction solution to precipitate crystals, which were recrystallized with a mixed solvent of ethyl acetate and diisopropyl ether to give 10-tolyl-9-oxothioxanthenium nonafluorobutanesulfonate (A1) 3 .9 g was obtained.
¹ H-NMR (400 MHz, CDCl ₃ ) σ2.38 (s, 3H), 7.34 (d, 2H), 7.72 (m, 2H), 7.95 (m, 4H), 8.28 (m, 2H), 8.63 (d , 2H)

Synthesis Example 11 Synthesis of 10-tolyl-9-oxothioxanthenium 3,5-bistrifluoromethylbenzenesulfonate (A2) 10-tolyl-9-oxothioxanthenium obtained in Synthesis Example 1 1.5 g of nonafluorobutane sulfonate (A1) is dissolved in a methanol / water = 1/1 solution and passed through an ion exchange resin (amberlite IRA402Cl in which NaOH has been replaced with OH) and 3,5 -1.7 g of 10-tolyl-9-oxothioxanthenium 3,5-bistrifluoromethylbenzenesulfonate (A2) whose salt was changed by adding 1 g of bistrifluoromethylbenzenesulfonic acid and extracting with chloroform Got.
¹ H-NMR (400 MHz, CDCl ₃ ) σ2.37 (s, 3H), 7.34 (d, 2H), 7.79 (m, 3H), 7.93 (m, 4H), 8.34 (m, 4
H), 8.62 (d, 2H)

Synthesis Example 12 Synthesis of 2-acetyl-10-tolyl-9-oxothioxanthenium nonafluorobutanesulfonate (A8) 15 g of thiosalicylic acid, 20 g of 4-bromoacetophenone, 12 g of sodium carbonate, and 0.2 g of a copper catalyst Was stirred in 170 ml of dimethylformamide at 200 ° C. for 6 hours, and the reaction solution was poured into an aqueous hydrochloric acid solution and collected by filtration. The obtained crystals were recrystallized from acetonitrile to obtain 16 g of sulfide. 10 g of the obtained sulfide was stirred in 60 g of polyphosphoric acid at 60 ° C. for 5 hours and then poured into ice water. The crystals were collected by filtration, washed with an aqueous sodium hydrogen carbonate solution and water, and recrystallized with ethanol to obtain 5 g of 2-acetyl-9H-thioxan-9-one. Further, 3 g of the obtained 2-acetyl-9H-thioxan-9-one was stirred in 12 ml of trifluoroacetic acid under ice-cooling, and a mixed solution of 1.4 ml of 30% hydrogen peroxide and 2.7 ml of trifluoroacetic acid was slowly added. added. After the addition, the mixture was stirred for 30 minutes under ice cooling, followed by stirring at room temperature for 1 hour to complete the reaction. The reaction solution was poured into water, and separated with ethyl acetate and an aqueous sodium hydroxide solution, and the organic layer was distilled off under reduced pressure to obtain 3.6 g of a sulfoxide form. It was stirred in 15 g of toluene, 3.3 ml of trifluoroacetic anhydride and 1.9 ml of nonafluorobutanesulfonic acid were added under ice cooling, and the mixture was stirred for 30 minutes under ice cooling and at room temperature for 1 hour. Diisopropyl ether was added to the reaction solution to crystallize, and the resulting crystals were recrystallized with a mixed solvent of ethyl acetate and diisopropyl ether to give 2-acetyl-10-tolyl-9-oxothioxanthenium nonafluorobutanesulfonic acid 1 g of salt (A8) was obtained.
¹ H-NMR (400 MHz, CDCl ₃ ) σ2.39 (s, 3H), 2.74 (s, 3H), 7.37 (d, 2H), 7.72 (m, 2H), 7.97 (m, 2H), 8.19 (m , 1H), 8.39 (m, 2H), 8.67 (d, 1H), 9.09 (s, 1H)

  Other sulfonium salts (A) were synthesized in the same manner.

[Examples 1-12 and Comparative Examples 1-6]
(I) Preparation and coating of positive resist As shown in Table 2 below, an acid-decomposable resin, an acid generator, a basic compound and a surfactant are dissolved in propylene glycol monomethyl ether acetate, and the solid content concentration is 8. After preparing a 5 mass% solution, the obtained solution was microfiltered with a membrane filter having a 0.1 μm aperture to obtain a resist solution. This resist solution was applied onto a 6-inch silicon wafer using a spin coater Mark8 manufactured by Tokyo Electron, and baked at 110 ° C. for 90 seconds to obtain a resist film having a thickness of 0.30 μm.

(Ii) Formation and Evaluation of Positive Resist Pattern This resist film was irradiated with an electron beam using an electron beam drawing apparatus (HL750 manufactured by Hitachi, Ltd., acceleration voltage 50 KeV). After irradiation, bake at 110 ° C for 90 seconds, 2.3
After immersing in an 8% by mass tetramethylammonium hydroxide (TMAH) aqueous solution for 60 seconds, it was rinsed with water for 30 seconds and dried. The obtained pattern was evaluated by the following method.

〔sensitivity〕
Scanning electron microscope (S-4300, manufactured by Hitachi, Ltd.) was used for the cross-sectional shape of the obtained pattern.
Was observed. Sensitivity was defined as the minimum irradiation energy when resolving a 0.15 μm line (line: space = 1: 1).
[Resolution]
The resolving power was defined as the limiting resolving power (line and space were separated and resolving) at the irradiation dose showing the above sensitivity.
[Pattern shape]
Using a scanning electron microscope (S-4300, manufactured by Hitachi, Ltd.), observe the cross-sectional shape of the 0.15 μm line pattern at the irradiation dose showing the above sensitivity, and perform a three-step evaluation of rectangular, slightly tapered, and tapered. It was.
[Line edge roughness (LER)]
The line width was measured at any 30 points in the length direction of 50 μm of the 0.15 μm line pattern at the irradiation dose showing the above sensitivity, and the variation was evaluated by 3σ.
The evaluation results are shown in Table 2.

Abbreviations for each component in Table 2 are as follows.
Polymers and acid generators are as described above.
[Basic compounds]
E-1: Tri-n-hexylamine E-2: 2,4,6-triphenylimidazole E-3: Tetra- (n-butyl) ammonium hydroxide [surfactant]
W-1: Fluorosurfactant, MegaFuck F-176 (Dainippon Ink Chemical Co., Ltd.)
W-2: Fluorine / silicone surfactant, MegaFac R08 (Dainippon Ink and Chemicals)
W-3: Silicone surfactant, polysiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.)

  From Table 2, it can be seen that the positive resist composition of the present invention has high sensitivity and high resolution in pattern formation by electron beam irradiation, and is excellent in pattern shape and line edge roughness.

[Examples 13 to 17 and Comparative Examples 7 and 8]
Using the resist compositions of Examples 1, 4, 5, 9, 11 and Comparative Examples 1 and 4, resist films were obtained in the same manner as in Example 1. However, the resist film thickness was 0.15 μm. The obtained resist film was subjected to surface exposure using EUV light (wavelength: 13.5 nm, RISOTEC Japan) while changing the exposure amount by 0 to 5.0 mJ, and further baked at 110 ° C. for 90 seconds. Thereafter, using a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution, the dissolution rate at each exposure amount was measured to determine the sensitivity.
Next, a sample irradiated with EUV light having an exposure amount equivalent to 1/2 of the sensitivity obtained in the above experiment was prepared, and the resist film surface after 60 seconds development with an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution Was observed with an AFM (atomic force microscope). The results are shown in Table 3.

  From Table 3, it can be seen that the positive resist composition of the present invention is excellent in sensitivity and surface roughness in property evaluation by irradiation with EUV light.

[Examples 18 to 22 and Comparative Examples 9 and 10]
Using the resist compositions of Examples 1, 4, 5, 9, 11 and Comparative Examples 1 and 4, resist films were obtained in the same manner as in Example 1. However, the resist film thickness was 0.40 μm. The obtained resist film was subjected to pattern exposure using a KrF excimer laser stepper (FPA3000EX-5 manufactured by Canon Inc., wavelength 248 nm). The post-exposure processing was performed in the same manner as in Example 1. The results are shown in Table 4 below.

  From Table 4, it can be seen that the positive resist composition of the present invention is higher in sensitivity and resolution than the comparative example in terms of pattern formation by KrF excimer laser exposure, and is excellent in pattern shape and line edge roughness. .

Claims (7)

(A) a polymer having three or more polymer chains via at least one branch, and having increased solubility in an alkali developer by the action of an acid; and
(B) A positive resist composition comprising a sulfonium salt having a cation represented by formula (I).

In general formula (I),
R ^{1 to} R ¹³ each independently represent a hydrogen atom or a substituent, and may be bonded to each other to form a ring.
Z is —CO— or —SO ₂ — .   The positive resist composition according to claim 1, wherein the polymer (A) is a comb polymer.   The positive resist composition according to claim 1, wherein the polymer (A) is a star polymer.   The positive resist composition according to claim 1, wherein the polymer (A) is a hyperbranched polymer.   5. The positive resist composition according to claim 1, wherein at least one of the polymer chains forming the polymer (A) comprises a vinyl-type repeating unit.   6. The positive resist composition according to claim 5, wherein the vinyl-type repeating unit contains a repeating unit derived from a styrene derivative and / or a repeating unit derived from a (meth) acrylic acid derivative.   A pattern forming method comprising: forming a resist film from the positive resist composition according to claim 1; and exposing and developing the resist film.