JP5130164B2 - 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 photofabrication processes. More specifically, the present invention relates to a positive photoresist capable of forming a high-definition pattern using an electron beam, EUV light or the like, and can be suitably used for fine processing of a semiconductor element using an electron beam or EUV light. The present invention relates to a positive resist composition and a pattern forming method using the same.

  Conventionally, in the manufacturing process of semiconductor devices such as IC and LSI, fine processing by lithography using a photoresist 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 to shorten the exposure wavelength from g-line to i-line and further to KrF excimer laser light. Furthermore, at present, in addition to excimer laser light, lithography using electron beams, X-rays, or EUV light is also being developed.

Lithography using an electron beam or EUV light is positioned as a next-generation or next-generation pattern forming technique, and a positive resist with high sensitivity is desired.
In particular, high sensitivity is an important issue for shortening the wafer processing time. A chemically amplified positive resist generally comprises a resin in which an alkali-soluble group is protected with an acid-decomposable group to make it insoluble in alkali, a photoacid generator, and a basic compound. The photoacid generator is decomposed by exposure to generate an acid, and the acid decomposes the acid-decomposable group while diffusing in the resist film, solubilizing the resin with alkali. Therefore, for high sensitivity, it is desirable that the acid diffuses to promote the deprotection reaction.
On the other hand, process margins such as exposure latitude (EL) are also important requirements in terms of performance. It is known that EL deteriorates when acid diffuses.
In order to achieve high sensitivity, it is preferable to increase the amount of deprotection per number of generated acids, but at this time, acid diffusion is accompanied at the same time, so it is difficult to achieve both high sensitivity and high EL.

  In order to achieve high sensitivity while suppressing acid diffusion, it is considered effective to increase acid generation efficiency. For that purpose, it is sufficient if the decomposition efficiency of the photoacid generator can be increased or the concentration thereof can be increased, but if the concentration of the photoacid generator is increased, the photoacid generator aggregates, deterioration of stability over time, precipitation There were harmful effects such as.

Patent Documents 1 to 6 disclose resist compositions using a phenolic acid-decomposable resin copolymerized with an acid-decomposable acrylate monomer having an alicyclic group as an acid-decomposable group.
Patent Document 7 contains a predetermined amount of a resin, an acid generator, a basic compound, and a solvent, and the resin includes a hydrophilic monomer and an aromatic ring in which some polar groups are protected by unstable groups having low activation energy. A resist which is a copolymer of a hydrophobic monomer having a group is disclosed.
Patent Document 8 discloses a photosensitive composition containing a specific sulfonium salt as an acid generator in order to improve sensitivity, resolution, and pattern shape and reduce problems of roughness and outgas.
Patent Document 9 discloses a positive resist composition that contains a specific resin and a sulfonic acid generator and defines the concentration of the sulfonic acid generator.
Patent Document 10 discloses a photosensitive composition containing a sulfonium salt compound having a lactone structure as an acid generator as a photosensitive composition having a reduced line edge roughness and providing a good pattern profile.

US Pat. No. 5,561,194 JP 2001-166474 A JP 2001-166478 A JP 2003-107708 A JP 2001-194792 A JP 2005-234434 A US Patent Application Publication No. 2007/0248908 JP 2007-210904 A JP 2004-271629 A JP 2007-178848 A

  An object of the present invention is to provide a positive resist composition having high sensitivity, high resolution, and good pattern shape as well as reduction of line edge roughness (LER) in patterning by electron beam, X-ray or EUV light, and the positive resist composition. It is providing the pattern formation method using a type | mold resist composition.

(1) (A) A positive resist composition comprising at least 21% by mass of a sulfonium salt compound represented by the following general formula (I) with respect to the total solid content in the positive resist composition: .

In general formula (I),
A represents a (m + 1) -valent linking group. When there are a plurality of A, they may be bonded to each other to form a cyclic structure.
R represents a monovalent organic group. When there are two R, they may be bonded to each other to form a cyclic structure.
L represents a lactone ring structure.
X ⁻ represents an anion.
n represents an integer of 1 to 3.
m represents 1 or 2.
When there are a plurality of A, R and L, they may be the same or different.

(2) (B) A positive resist composition as described in (1) above, which contains a resin having a weight average molecular weight of 4000 or less, decomposed by the action of an acid, and increased in solubility in an alkaline developer. object.
(3) The positive resist composition as described in (1) or (2) above, wherein the (m + 1) -valent linking group of A in the general formula (I) has an aromatic ring.
(4) In the general formula (I), the anion of X ⁻ is an organic sulfonate anion (R ¹ —SO ₃ ⁻ ), an organic carboxylate anion (R ¹ —CO ₂ ⁻ ), an organic imido acid anion ( N ^- and characterized in that the _{^{- ((SO 2 -R 1 C}} ) 3) - (SO 2 -R 1) 2, N (SO 2 -R 1) (CO-R 1)) or an organic methide anion The positive resist composition according to any one of (1) to (3) above. Here, R ¹ represents a monovalent organic group, and when there are a plurality of R ¹ groups, they may be the same or different.

(5) including a step of forming a resist film from the resist composition according to any one of (1) to (4) above, and exposing and developing the resist film with an electron beam, an X-ray, or EUV light. A pattern forming method characterized by the above.
Furthermore, the following structures are mentioned as a preferable embodiment of this invention.
(6) The positive resist composition as described in any one of (2) to (5) above, wherein the resin as the component (B) has a hydroxystyrene structural unit.
(7) The positive resist composition as described in any one of (1) to (6) above, further comprising a basic compound.
(8) The positive resist composition as described in any one of (1) to (7) above, further comprising a surfactant.

  According to the present invention, in patterning by electron beam, X-ray, or EUV light, a positive resist composition having high sensitivity, high resolution, and good pattern shape as well as LER reduction, and the positive resist composition are used. A pattern forming method can be provided.

Hereinafter, the present invention will be described in detail.
In addition, in the description of a group (atomic group) in this specification, the description which does not describe substituted and unsubstituted includes what has a substituent with the thing which does not have 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) Sulphonium Salt Compound Represented by General Formula (I) The positive resist composition of the present invention is a sulfonium salt compound represented by the following general formula (I) (also referred to as “compound (A)”). ) At least 21% by mass with respect to the total solid content in the positive resist composition.

In general formula (I),
A represents a (m + 1) -valent linking group. When there are a plurality of A, they may be bonded to each other to form a cyclic structure.
R represents a monovalent organic group. When there are two R, they may be bonded to each other to form a cyclic structure.
L represents a lactone ring structure.
X ⁻ represents an anion.
n represents an integer of 1 to 3.
m represents 1 or 2.
When there are a plurality of A, R and L, they may be the same or different.

  The compound (A) is a compound that generates an acid upon irradiation with actinic rays or radiation.

In the general formula (I), the (m + 1) -valent linking group of A is a linking group that connects S ⁺ and L.
when m is 1, A represents a divalent linking group that connects S and L, and a divalent group or bond such as an arylene group, an alkylene group, a cycloalkylene group, an alkenylene group, an ether bond or an ester bond; And the bivalent group formed by the combination can be mentioned, These may have a substituent.
The arylene group is preferably an arylene group having 6 to 15 carbon atoms, and examples thereof include a phenylene group and a naphthylene group.
The alkylene group is preferably a linear or branched alkylene group having 1 to 8 carbon atoms, and examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group, a hexylene group, and an octylene group.
The cycloalkylene group is preferably a cycloalkylene group having 5 to 12 carbon atoms, and examples thereof include monocyclic residues such as cyclopentylene group and cyclohexylene group, and polycyclic residues such as norbornane skeleton and adamantane skeleton. be able to.
The alkenylene group is preferably an alkenylene group having 2 to 6 carbon atoms, and examples thereof include an ethenylene group, a propenylene group, and a butenylene group.
When m is 2, A can include a group in which any hydrogen atom in the divalent linking group when m is 1 is used as a bond for another L bond.
The (m + 1) -valent linking group as A preferably has 20 or less carbon atoms, and more preferably 15 or less.

The (m + 1) -valent linking group of A preferably has an aromatic ring, whereby the stability of the compound (A) is improved, and the storage stability of the composition using the same is improved. The aromatic ring may or may not be directly connected to the sulfur atom (S ⁺ ). The aromatic ring is preferably an aromatic ring having 5 to 30 carbon atoms, and examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a biphenylene ring, a fluorene ring, and a pyrene ring. One or more of these may be bonded to the same A. As the aromatic ring, a benzene ring, a naphthalene ring and an anthracene ring are particularly preferable, and the solvent solubility is improved.

The arylene group, alkylene group, cycloalkylene group, and alkenylene group in the (m + 1) -valent linking group of A may be substituted with one or more organic groups (B).
Examples of the organic group (B) include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkenyl group, an alkoxy group, an alkoxycarbonylamino group, an alkylthio group, an alkyliminosulfonyl group, a cycloalkylaryloxysulfonyl group, and a cyano group. Examples include groups. When there are a plurality of organic groups (B), the plurality of organic groups (B) may be the same or different.
The alkyl group as the organic group (B) may have a substituent, and is preferably a linear or branched alkyl group having 1 to 30 carbon atoms, and an oxygen atom, a sulfur atom, or a nitrogen atom in the alkyl chain. You may have. Specifically, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-octyl group, n-dodecyl group, n-tetradecyl group, n-octadecyl group, etc. And a branched alkyl group such as isopropyl group, isopropyl group, isobutyl group, t-butyl group, neopentyl group, 2-ethylhexyl group.
The cycloalkyl group as the organic group (B) may have a substituent, preferably a cycloalkyl group having 3 to 20 carbon atoms, and may have an oxygen atom in the ring. Specific examples include a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, and the like.
The aryl group as the organic group (B) may have a substituent and is preferably an aryl group having 6 to 14 carbon atoms, and examples thereof include a phenyl group and a naphthyl group.
The aralkyl group as the organic group (B) may have a substituent, preferably an aralkyl group having 7 to 20 carbon atoms, such as a benzyl group, a phenethyl group, a naphthylmethyl group, or a naphthylethyl group. Is mentioned.
Examples of the alkenyl group as the organic group (B) include a group having a double bond at an arbitrary position of the alkyl group.
The alkoxy group in the alkoxy group and the alkoxycarbonylamino group as the organic group (B) is preferably an alkoxy group having 1 to 30 carbon atoms, such as a methoxy group, an ethoxy group, a propoxy group, an n-butoxy group, or a pentyloxy group. Group, hexyloxy group, heptyloxy group and the like.
Examples of the alkyl group in the alkylthio group and the alkyliminosulfonyl group as the organic group (B) include the above alkyl groups.
Examples of the cycloalkyl group and aryl group in the cycloalkylaryloxysulfonyl group as the organic group (B) include the above cycloalkyl groups and aryl groups.
Examples of the further substituent that each organic group (B) may have include, for example, a halogen atom, a hydroxyl group, a nitro group, a cyano group, a carboxy group, a carbonyl group, and a cycloalkyl group (preferably having 3 to 10 carbon atoms). ), An aryl group (preferably 6 to 14 carbon atoms), an alkoxy group (preferably 1 to 10 carbon atoms), an acyl group (preferably 2 to 20 carbon atoms), an acyloxy group (preferably 2 to 10 carbon atoms), Examples include an alkoxycarbonyl group (preferably having 2 to 20 carbon atoms), an aminoacyl group (preferably having 2 to 10 carbon atoms), and the like. As for the cyclic structure in the aryl group, cycloalkyl group and the like, examples of the further substituent include an alkyl group (preferably having a carbon number of 1 to 10). As for the aminoacyl group, examples of the further substituent include 1 or 2 alkyl groups (preferably having 1 to 10 carbon atoms).

  The (m + 1) -valent linking group of A may be further substituted with a halogen atom (preferably a fluorine atom) or the like.

Examples of the monovalent organic group for R include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and an alkenyl group.
The alkyl group as a monovalent organic group for R may have a substituent, and is preferably a linear or branched alkyl group having 1 to 30 carbon atoms, and an oxygen atom, a sulfur atom, It may have a nitrogen atom. Specifically, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-octyl group, n-dodecyl group, n-tetradecyl group, n-octadecyl group, etc. And a branched alkyl group such as isopropyl group, isopropyl group, isobutyl group, t-butyl group, neopentyl group, 2-ethylhexyl group.
The cycloalkyl group as a monovalent organic group for R may have a substituent, preferably a cycloalkyl group having 3 to 20 carbon atoms, and may have an oxygen atom in the ring. . Specific examples include a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, and the like.
The aryl group as a monovalent organic group for R may have a substituent and is preferably an aryl group having 6 to 14 carbon atoms, such as a phenyl group and a naphthyl group.
The aralkyl group as a monovalent organic group for R may have a substituent, preferably an aralkyl group having 7 to 20 carbon atoms, such as benzyl group, phenethyl group, naphthylmethyl group, naphthyl. An ethyl group is mentioned.
Examples of the alkenyl group as a monovalent organic group for R include a group having a double bond at an arbitrary position of the alkyl group.
Examples of the further substituent that the monovalent organic group of R may have include, for example, a halogen atom, a hydroxyl group, a nitro group, a cyano group, a carboxy group, a carbonyl group, and a cycloalkyl group (preferably having 3 to 10 carbon atoms). ), An aryl group (preferably 6 to 14 carbon atoms), an alkoxy group (preferably 1 to 10 carbon atoms), an acyl group (preferably 2 to 20 carbon atoms), an acyloxy group (preferably 2 to 10 carbon atoms), Examples include an alkoxycarbonyl group (preferably having 2 to 20 carbon atoms), an aminoacyl group (preferably having 2 to 10 carbon atoms), and the like. As for the cyclic structure in the aryl group, cycloalkyl group and the like, examples of the further substituent include an alkyl group (preferably having a carbon number of 1 to 10). As for the aminoacyl group, examples of the further substituent include 1 or 2 alkyl groups (preferably having 1 to 10 carbon atoms).

In the lactone ring structure of L, the number of atoms constituting the ring is preferably 4 to 20, and more preferably 4 to 10. The lactone ring structure of L may be substituted with one or more organic groups (B).
The lactone ring structure of L is preferably a 5- to 7-membered ring lactone structure, and other ring structures may be condensed so as to form a bicyclo structure or a spiro structure in the 5- to 7-membered ring lactone structure. The lactone ring structure is more preferably a structure represented by any of the following general formulas (LC1-1) to (LC1-16). Particularly preferred lactone ring structures are (LC1-1), (LC1-4), (LC1-5), (LC1-6), (LC1-13), (LC1-14), and a specific lactone ring structure Some development defects are improved.

The lactone ring structure may or may not have a substituent (Rb ₂ ). Preferred substituents (Rb ₂ ) include an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an alkoxycarbonyl group having 1 to 8 carbon atoms, and a carboxyl group. , Halogen atom, hydroxyl group, cyano group, acid-decomposable group and the like. n ₂ is, 0-4
Represents an integer. When n ₂ is an integer of 2 or more, a plurality of Rb ₂ may be the same or different, and a plurality of Rb ₂ may be bonded to form a ring.

  The lactone ring structure as L should just be couple | bonded with the coupling group as A in the arbitrary places on a ring.

  Hereinafter, although the specific example of a cation part in a compound (A) is given, this invention is not limited to this.

Examples of the anion of X ^{− in} the general formula (I) include an organic sulfonate anion (
R ¹ —SO ₃ ⁻ ), organic carboxylate anion (R ¹ —CO ₂ ⁻ ), organic imido acid anion (N ⁻ (
_{^{SO 2 -R 1) 2, N}} - (SO 2 -R 1) (CO-R 1)), organic methide anion _{^{(C - (SO 2 -R 1}} ) 3), halogen anions (Br ^-, Cl ^- ), BF ₄ ⁻ and PF ₆ −. Examples of the anion of X ⁻ include an organic sulfonate anion (R ¹ —SO ₃ ⁻ ), an organic carboxylate anion (R ¹ —CO ₂ ⁻ ), an organic imido acid anion (N ⁻ (SO ₂ —R ¹ ) ₂ , _{^{N - (SO 2 -R 1)}} (CO-R 1
)), Organic methide anion _{^{(C - (SO 2 -R 1}} ) 3) is especially preferred. Here, R ¹ represents a monovalent organic group.
The monovalent organic group for R ¹ preferably has 1 to 40 carbon atoms, and examples thereof include an alkyl group, an aryl group, and a camphor residue. Plural R ^{1 s} may be the same or different and may be bonded to form a ring, and may be further substituted by a halogen atom (preferably a fluorine atom), the organic group (B), or the like. .
The alkyl group as R ¹ is preferably a linear or branched alkyl group having 1 to 30 carbon atoms, and has an oxygen atom, a sulfur atom, a sulfur atom having an oxygen atom added thereto, and a plurality of nitrogen atoms in the alkyl chain. May be. R ¹ is specifically a methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-octyl group, n-dodecyl group, n-tetradecyl group, n -A linear alkyl group such as an octadecyl group, and a branched alkyl group such as an isopropyl group, an isobutyl group, a t-butyl group, a neopentyl group, and a 2-ethylhexyl group. The alkyl group is more preferable because 30 to 100% of the number of hydrogen atoms is replaced with a fluorine atom, thereby improving thermal stability. Examples of the alkyl group substituted with a fluorine atom include perfluoroalkyl groups such as a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, and a perfluorobutyl group.
The aryl group as R ¹ may have a substituent, and preferably has 6 to 6 carbon atoms.
14 aryl groups such as a phenyl group and a naphthyl group. The aryl group is preferably substituted with a fluorine atom. Examples of the aryl group substituted with a fluorine atom include a perfluorophenyl group.

  Hereinafter, although the specific example of the anion part in a compound (A) is given, this invention is not limited to this.

  Although the specific example of a compound (A) is shown in the following table | surface, this invention is not limited to this.

Compound (A) is synthesized by reacting a sulfonium compound having a hydroxyl group that can be easily obtained and synthesized with a compound having a lactone structure in which a leaving group (such as a halogen atom) is introduced, according to the Williamson method. (Scheme 1 below).
In addition, a sulfonium skeleton can be constructed by a method in which a diphenyl sulfoxide derivative and an aryl compound having a lactone structure are reacted in the presence of an activating agent such as an acid condition or an acid anhydride (reference: JP 2002-193925 A, The following scheme 2).

  The amount of compound (A) added is at least 21% by mass, preferably 21-60% by mass, more preferably 30-50% by mass, based on the total solid content in the positive resist composition.

[2] (B) Compound that generates acid upon irradiation with actinic ray or radiation In addition to compound (A), the positive resist composition of the present invention further generates an acid upon irradiation with actinic ray or radiation. It is preferable to contain a compound (hereinafter also referred to as “combination acid generator”).
As the combined acid generator, photo-initiator of photocation polymerization, photo-initiator of photo-radical polymerization, photo-decoloring agent of dyes, photo-discoloring agent, irradiation of actinic ray or radiation used for micro resist, etc. The known compounds that generate an acid 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.

  Preferred compounds among the combined acid generators include compounds represented by the following general formulas (ZI), (ZII), and (ZIII).

In the 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.

Examples of the non-nucleophilic anion as Z ⁻ include a sulfonate anion, a carboxylate anion, a sulfonylimide anion, a bis (alkylsulfonyl) imide anion, and 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 aliphatic sulfonate anion, an aromatic sulfonate anion, and a camphor sulfonate anion.

  Examples of the carboxylate anion include an aliphatic carboxylate anion, an aromatic carboxylate anion, and an aralkylcarboxylate anion.

  The aliphatic moiety in the aliphatic sulfonate anion may be an alkyl group or a cycloalkyl group, preferably an alkyl group having 1 to 30 carbon atoms and a cycloalkyl group having 3 to 30 carbon atoms such as methyl. Group, ethyl 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 aromatic group in the aromatic 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.

The alkyl group, cycloalkyl group and aryl group in the aliphatic sulfonate anion and aromatic sulfonate anion may have a substituent. Examples of the substituent of the alkyl group, cycloalkyl group, and aryl group in the aliphatic sulfonate anion and aromatic 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 having 1 to 15 carbon atoms), cycloalkyl group (preferably having 3 to 15 carbon atoms), aryl group (preferably having 6 to 14 carbon atoms), alkoxycarbonyl group ( Preferably 2 to 7 carbon atoms, acyl group (preferably 2 to 12 carbon atoms), alkoxycarbonyloxy group (preferably 2 to 7 carbon atoms), alkylthio group (preferably 1 to 15 carbon atoms), alkylsulfonyl group (Preferably having 1 to 15 carbon atoms), alkyliminosulfonyl group (preferably having 2 to 15 carbon atoms), aryl Ruoxysulfonyl group (preferably having 6 to 20 carbon atoms), alkylaryloxysulfonyl group (preferably having 7 to 20 carbon atoms), cycloalkylaryloxysulfonyl group (preferably having 10 to 20 carbon atoms), alkyloxyalkyloxy group (Preferably having 5 to 20 carbon atoms), a cycloalkylalkyloxyalkyloxy group (preferably having 8 to 20 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 aliphatic moiety in the aliphatic carboxylate anion include the same alkyl group and cycloalkyl group as in the aliphatic sulfonate anion.

  Examples of the aromatic group in the aromatic carboxylate anion include the same aryl group as in the aromatic sulfonate 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.

  The alkyl group, cycloalkyl group, aryl group and aralkyl group in the aliphatic carboxylate anion, aromatic carboxylate anion and aralkylcarboxylate anion may have a substituent. Examples of the substituent of the alkyl group, cycloalkyl group, aryl group and aralkyl group in the aliphatic carboxylate anion, aromatic carboxylate anion and aralkylcarboxylate anion include, for example, the same halogen atom and alkyl as in the aromatic sulfonate anion Group, cycloalkyl group, alkoxy group, alkylthio group and the like.

  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 substituents for these alkyl groups include halogen atoms, alkyl groups substituted with halogen atoms, alkoxy groups, alkylthio groups, alkyloxysulfonyl groups, aryloxysulfonyl groups, cycloalkylaryloxysulfonyl groups, and the like. Alkyl groups substituted with fluorine atoms are preferred.

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

Examples of the non-nucleophilic anion of Z ⁻ include an aliphatic sulfonate anion in which the α-position of the sulfonic acid is substituted with a fluorine atom, an aromatic sulfonate anion substituted with a fluorine atom or a group having a fluorine atom, and an alkyl group. A bis (alkylsulfonyl) imide anion substituted with a fluorine atom and a tris (alkylsulfonyl) methide anion wherein an alkyl group is substituted with a fluorine atom are preferred. The non-nucleophilic anion is more preferably a perfluoroaliphatic sulfonic acid anion having 4 to 8 carbon atoms, a benzenesulfonic acid anion having a fluorine atom, still more preferably a nonafluorobutanesulfonic acid anion, a perfluorooctanesulfonic acid anion, It is a pentafluorobenzenesulfonic acid anion and 3,5-bis (trifluoromethyl) benzenesulfonic acid anion.

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

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 (ZI) components include compounds (ZI-1), (ZI-2), and (ZI-3) described below.

The compound (ZI-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 triarylsulfonium compounds, diarylalkylsulfonium compounds, aryldialkylsulfonium compounds, diarylcycloalkylsulfonium compounds, and aryldicycloalkylsulfonium compounds.

  The aryl group of the arylsulfonium compound is preferably a phenyl group or a naphthyl group, and more preferably a phenyl group. The aryl group may be an aryl group having a heterocyclic structure having an oxygen atom, a nitrogen atom, a sulfur atom or the like. Examples of the aryl group having a heterocyclic structure include a pyrrole residue (a group formed by losing one hydrogen atom from pyrrole) and a furan residue (a group formed by losing one hydrogen atom from furan). Groups), thiophene residues (groups formed by the loss of one hydrogen atom from thiophene), indole residues (groups formed by the loss of one hydrogen atom from indole), benzofuran residues ( A group formed by losing one hydrogen atom from benzofuran), a benzothiophene residue (a group formed by losing one hydrogen atom from benzothiophene), and the like. 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, more 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 (ZI-2) will be described.
Compound (ZI-2) is a compound in which R _{201 to} R ₂₀₃ in formula (ZI) each independently represents an organic group having no 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 each independently preferably an alkyl group, a cycloalkyl group, an allyl group, or a vinyl group, more preferably a linear or branched 2-oxoalkyl group, 2-oxocycloalkyl group, alkoxy group. A carbonylmethyl group, particularly 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 alkoxy group having 1 to 5 carbon atoms (methoxy group, ethoxy group, propoxy group, butoxy group, pentoxy 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.

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

In general formula (ZI-3),
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 each independently represents a hydrogen atom, an alkyl group or a cycloalkyl group.
R _x and R _y each 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 , R _6c and R _7c , 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 and a sulfur atom. , An ester bond and an amide bond may be included. Examples of the group formed by combining any two or more of R _{1c to} R _5c , R _6c and R _7c , and R _x and R _y include a butylene group and a pentylene group.

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

The alkyl group as R _{1c to} R _7c 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. Examples of the cycloalkyl group include cyclohexane 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 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 2-15. 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 _7c , such as 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 _7c .

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

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 general formulas (ZII) and (ZIII),
R ₂₀₄ to 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. Aryl group R ₂₀₄ to R ₂₀₇ represents an oxygen atom, a nitrogen atom, may be an aryl group having a heterocyclic structure having a sulfur atom and the like. Examples of the aryl group having a heterocyclic structure include a pyrrole residue (a group formed by losing one hydrogen atom from pyrrole) and a furan residue (a group formed by losing one hydrogen atom from furan). Groups), thiophene residues (groups formed by the loss of one hydrogen atom from thiophene), indole residues (groups formed by the loss of one hydrogen atom from indole), benzofuran residues ( A group formed by losing one hydrogen atom from benzofuran), a benzothiophene residue (a group formed by losing one hydrogen atom from benzothiophene), and the like.

The alkyl group and cycloalkyl group in R ₂₀₄ to R _207, 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).

Aryl group, alkyl group of R ₂₀₄ to R _207, cycloalkyl groups may have a substituent. Aryl group, alkyl group of R ₂₀₄ to R _207, the cycloalkyl group substituent which may be possessed by, for example, 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, having 6 to 15 carbon atoms), an alkoxy group (for example, having 1 to 15 carbon atoms), a halogen atom, a hydroxyl group, and a phenylthio group.

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

  Examples of the combined acid generator may further include compounds represented by the following general formulas (ZIV), (ZV), and (ZVI).

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 independently represents an alkyl group, a cycloalkyl group or an aryl group.
A represents an alkylene group, an alkenylene group or an arylene group.

Of the combined acid generators, compounds represented by the general formulas (ZI) to (ZIII) are more preferable.
Further, as the combined acid generator, a compound that generates an acid having one sulfonic acid group or imide group is preferable, more preferably a compound that generates monovalent perfluoroalkanesulfonic acid, or a monovalent fluorine atom or fluorine. A compound that generates an aromatic sulfonic acid substituted with a group containing an atom, or a compound that generates an imide acid substituted with a monovalent fluorine atom or a group containing a fluorine atom. And a sulfonium salt of fluorine-substituted benzenesulfonic acid or fluorine-substituted imidic acid. The combined acid generator that can be used is particularly preferably a fluorinated substituted alkane sulfonic acid, a fluorinated substituted benzene sulfonic acid, or a fluorinated substituted imido acid whose pKa of the generated acid is pKa = -1 or less, and the sensitivity is improved. To do.

  Among the combined acid generators, particularly preferred examples are given below.

The combined acid generator can be used alone or in combination of two or more.
The content of the combined acid generator in the positive resist composition is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, based on the total solid content of the positive resist composition. Preferably it is 1-7 mass%.
The content of the combined acid generator in the positive resist composition is preferably 1 to 8% by mass relative to the compound (A).

[2] Resin (B) which decomposes by the action of an acid and increases the solubility in an alkaline developer
The positive resist composition of the present invention preferably contains a resin (B) (hereinafter also referred to as “acid-decomposable resin”) that decomposes with an acid and increases the solubility in an alkaline developer.
The acid-decomposable resin is a resin having a group (acid-decomposable group) that is decomposed by the action of an acid to generate an alkali-soluble group in the main chain or side chain of the resin or in both the main chain and the side chain. Among these, a resin having an acid-decomposable group in the side chain is more preferable.

A preferable group as the acid-decomposable group is a group in which a hydrogen atom of an alkali-soluble group such as a —COOH group or a —OH group is substituted with a group capable of leaving with an acid.
In the present invention, the acid-decomposable group is preferably an acetal group or a tertiary ester group.

  The base resin in the case where these acid-decomposable groups are bonded as side chains is an alkali-soluble resin having —OH or —COOH groups in the side chains. For example, the alkali-soluble resin mentioned later can be mentioned.

  The alkali dissolution rate of these alkali-soluble resins, when formed as a resist film, is preferably 80 kg / sec or more as measured with 0.261N tetramethylammonium hydroxide (TMAH) (23 ° C.). Particularly preferably, it is 160 Å / second or more.

The acid-decomposable resin preferably contains a repeating unit having an aromatic group, and particularly preferably an acid-decomposable resin having a hydroxystyrene repeating unit (hereinafter also referred to as “resin (B1)”). More preferably, hydroxystyrene / hydroxystyrene copolymer protected with an acid-decomposable group and hydroxystyrene / (meth) acrylic acid tertiary alkyl ester are preferred.
Specific examples of the resin (B1) are shown below, but are not limited thereto.

  In the above specific example, tBu represents a t-butyl group.

  The content of the group that can be decomposed by an acid is determined by the number of groups (B) that can be decomposed by an acid in the resin and the number of alkali-soluble groups that are not protected by a group capable of leaving by an acid (S). B + S). The content is preferably 0.01 to 0.7, more preferably 0.05 to 0.50, and still more preferably 0.05 to 0.40.

  As the resin (B1), a resin having a repeating unit represented by the following general formula (II) and a repeating unit represented by the general formula (III) is particularly preferable.

In general formulas (II) and (III):
R ₀₁ each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, a halogen atom, a cyano group, or an alkoxycarbonyl group.
L ₁ and L ₂ may be the same or different and each represents a hydrogen atom, an alkyl group, a cycloalkyl group or an aralkyl group.
M represents a single bond or a divalent linking group.
Q represents an alicyclic group or an aromatic ring group which may contain an alkyl group, a cycloalkyl group, an aryloxy group, or a hetero atom.
At least two of Q, M, and L ₁ may combine to form a 5-membered or 6-membered ring.
When there are a plurality of A's, each independently represents a halogen atom, a cyano group, an acyl group, an alkyl group, an alkoxy group, an acyloxy group, or an alkoxycarbonyl group.
m and n each independently represents an integer of 0 to 4. However, m and n are preferably not 0 at the same time.

Further, as the resin (B1), a repeating unit represented by the general formula (II), the general formula (III)
And a resin having a repeating unit represented by formula (IV). In this case, m = n = 0 may be used.

In general formula (IV),
R ₀₁ each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, a halogen atom, a cyano group, or an alkoxycarbonyl group.
B represents a halogen atom, a cyano group, an acyl group, an alkyl group, an alkoxy group, an acyloxy group or an alkoxycarbonyl group.
p represents an integer of 0 to 5.

  The substituent that the benzene ring in the repeating unit represented by the general formula (II) has is a group (acid-decomposable group) that is decomposed by the action of an acid to generate a hydroxyl group (an alkali-soluble group). Hydroxystyrene units are produced, and the resin is a resin with increased solubility in an alkaline developer.

In the general formulas (II) to (IV), R ₀₁ each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, a halogen atom, a cyano group, or an alkoxycarbonyl group, and preferably has 20 or less carbon atoms. It is.
The alkyl group or cycloalkyl group in R ₀₁ preferably has 20 or less carbon atoms, and is a methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, pentyl group, cyclopentyl group. Hexyl group, cyclohexyl group, octyl group, dodecyl group and the like. These groups may have a substituent, for example, alkoxy group, hydroxyl group, halogen atom, nitro group, acyl group, acyloxy group, acylamino group, sulfonylamino group, alkylthio group, arylthio group, aralkylthio group, thiophene. Examples include carbonyloxy groups, thiophenemethylcarbonyloxy groups, and heterocyclic residues such as pyrrolidone residues, and those having 8 or less carbon atoms are preferred. CF ₃ group, alkoxycarbonylmethyl group, alkylcarbonyloxymethyl group, hydroxymethyl group, alkoxymethyl group and the like are more preferable.
Examples of the halogen atom for R ₀₁ include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and a fluorine atom is preferred.
As the alkyl group contained in the alkoxycarbonyl group in R _01, the same alkyl groups represented by R ₀₁ are preferred.

The alkyl group as L ₁ and L ₂ is, for example, an alkyl group having 1 to 8 carbon atoms, and specifically includes a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, a hexyl group. An octyl group can be preferably mentioned.
The cycloalkyl group as L ₁ and L ₂ is, for example, a cycloalkyl group having 3 to 15 carbon atoms, and specifically, a cyclopentyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group can be preferably exemplified.
The aryl group as L ₁ and L ₂ is, for example, an aryl group having 6 to 15 carbon atoms, and specific examples thereof include a phenyl group, a tolyl group, a naphthyl group, and an anthryl group.
The aralkyl group as L ₁ and L ₂ has, for example, 6 to 20 carbon atoms, and examples thereof include a benzyl group and a phenethyl group.
Further, it is preferable that either one of L _1, L ₂ is a hydrogen atom.

The divalent linking group as M contains, for example, an alkylene group, a cycloalkylene group, an alkenylene group, an arylene group, —OCO—, —COO—, or —CON (R ₀ ) —, and a plurality thereof. A linking group. R ₀ is a hydrogen atom or an alkyl group.

The alkyl group and cycloalkyl group as Q are the same as the above groups as L ₁ and L ₂ .
Examples of the aryloxy group as Q include a phenoxy group, a naphthoxy group, and a terphenyloxy group.
Examples of the alicyclic group or aromatic ring group which may contain a hetero atom as Q include the cycloalkyl group and aryl group as L ₁ and L ₂ described above, preferably 3 to 15 carbon atoms. It is.
Examples of the alicyclic group or aromatic ring group containing a hetero atom include thiirane, cyclothiolane, thiophene, furan, pyrrole, benzothiophene, benzofuran, benzopyrrole, triazine, imidazole, benzimidazole, triazole, thiadiazole, thiazole, pyrrolidone, and the like. Is a structure generally called a heterocycle (a ring formed from carbon and a heteroatom, or a ring formed from a heteroatom).

As a 5-membered or 6-membered ring that may be formed by combining at least two of Q, M, and L ₁ ,
Examples include a case where at least two of Q, M, and L ₁ are bonded to form, for example, a propylene group or a butylene group to form a 5-membered or 6-membered ring containing an oxygen atom.

As the group represented by -M-Q, 1 to 30 carbon atoms, more preferably from 5 to 20 carbon atoms, for _{example, -OC (L 1) (L} 2) a group represented by O-M-Q The following may be mentioned.

The acyl group as A is, for example, an acyl group having 2 to 8 carbon atoms. Specifically, a formyl group, an acetyl group, a propanoyl group, a butanoyl group, a pivaloyl group, a benzoyl group and the like can be preferably exemplified. .
The alkyl group as A is, for example, an alkyl group having 1 to 8 carbon atoms, and specifically includes a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, a hexyl group, and an octyl group. Can be preferably mentioned.
The alkoxy group as A is, for example, the above alkoxy group having 1 to 8 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, a hexyloxy group, and a cyclohexyloxy group. .
Examples of the acyloxy group or alkoxycarbonyl group as A include groups corresponding to the above acyl group and alkoxy group.

  Each of the above groups may have a substituent, and preferred substituents include a hydroxyl group, a carboxyl group, a cyano group, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), an alkoxy group (methoxy group, Ethoxy group, propoxy group, butoxy group, etc.). As for the cyclic structure, examples of the substituent further include an alkyl group (preferably having 1 to 8 carbon atoms).

  m and n independently represent an integer of 0 to 4. m and n are each preferably 0 to 2, and more preferably 1.

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

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

R ₀₁ in the general formula (IV) independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, a halogen atom, a cyano group, or an alkoxycarbonyl group, and preferably has 20 or less carbon atoms. The same as R ₀₁ in (II) or (III).
Examples of the acyl group, alkyl group, alkoxy group, acyloxy group or alkoxycarbonyl group as B in the general formula (IV) include the same groups as A in the general formula (II). An acyloxy group and an alkoxycarbonyl group are preferable, and an acyloxy group is more preferable. Among acyloxy groups (represented by the general formula —O—CO—R _A , where R _A is an alkyl group), those having 1 to 6 carbon atoms in _RA are preferred, and those having 1 to 3 carbon atoms in _RA. Are more preferable, and those in which R _A has 1 carbon atom (that is, an acetoxy group) are particularly preferable.
p represents an integer of 0 to 5, preferably 0 to 2, more preferably 1 to 2, and still more preferably 1.

  Each of the above groups may have a substituent, and preferred substituents include a hydroxyl group, a carboxyl group, a cyano group, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), an alkoxy group (methoxy group, Ethoxy group, propoxy group, butoxy group, etc.). As for the cyclic structure, examples of the substituent further include an alkyl group (preferably having 1 to 8 carbon atoms).

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

  The resin (B1) may have a repeating unit represented by the following general formula (V).

In general formula (V),
R _{a to} R _c each independently represents a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group or an alkyl group.
X ₁ represents a hydrogen atom or an organic group.

In general formula (V), the alkyl group as R _{a to} R _c is preferably an alkyl group having 1 to 5 carbon atoms, and examples thereof include a methyl group, an ethyl group, and a propyl group. .

The organic group as X ₁ preferably has 1 to 40 carbon atoms and may be an acid-decomposable group or a non-acid-decomposable group.

When X ₁ is a non-acid-decomposable group, examples of the non-acid-decomposable group include an alkyl group, a cycloalkyl group, and an aryl group. However, those corresponding to the structures of (pI) to (pVI) described later are excluded as the alkyl group and cycloalkyl group. As an alkyl group, a C1-C10 thing is preferable and a C1-C6 thing is more preferable. As a cycloalkyl group, a C3-C12 thing is preferable and a C6-C10 thing is more preferable. The cycloalkyl group may be monocyclic or polycyclic. As the aryl group, those having 6 to 10 carbon atoms are preferable. These substituents may further have a substituent.
In the non-acid-decomposable group, the alkyl group is preferably a group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, an n-butyl group or a sec-butyl group. Those having 3 to 10 carbon atoms such as propyl group, cyclobutyl group, cyclohexyl group and adamantyl group are preferable, and aryl group is carbon such as phenyl group, xylyl group, toluyl group, cumenyl group, naphthyl group and anthracenyl group. Those of several 6 to 14 are preferable.

As the organic group of the acid-decomposable group for X ₁ , for example, —C (R _11a ) (R _12a ) (R _13a ), —C (R _14a ) (R _15a ) (OR _16a ), —CO—OC ( R _11a ) (R _12a ) (R _13a ) can be mentioned.
R _{11a to} R _13a each independently represents an alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl group or an aryl group. R _14a and R _15a each independently represents a hydrogen atom or an alkyl group. R _16a represents an alkyl group, a cycloalkyl group, an alkenyl group,
Represents an aralkyl group or an aryl group. Two of R _11a , R _12a and R _13a , or two of R _14a , R _15a and R _16a may be bonded to form a ring.
Note that a group having an acid-decomposable group can be introduced into X ₁ by modification. In this way, X ₁ introduced with the acid decomposable group is, for example, as follows.
-[C ( _R17a ) ( _R18a )] _p- CO-OC ( _R11a ) ( _R12a ) ( _R13a ) _R17a and _R18a each independently represents a hydrogen atom or an alkyl group. p is an integer of 1 to 4.

The organic group as X ₁ is preferably an acid-decomposable group having at least one cyclic structure selected from alicyclic, aromatic and bridged alicyclic, and an aromatic group (particularly a phenyl group). Or a structure containing an alicyclic or bridged alicyclic structure represented by the following general formulas (pI) to (pVI).

In the formula, R ₁₁ represents a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group or a sec-butyl group, and Z forms an alicyclic hydrocarbon group together with a carbon atom. Represents the atomic group necessary to do.
R _{12 to} R ₁₆ each independently represents a linear or branched alkyl group or alicyclic hydrocarbon group having 1 to 4 carbon atoms, provided that at least one of R _{12 to} R ₁₄ , or Either R ₁₅ or R ₁₆ represents an alicyclic hydrocarbon group.
R _{17 to} R ₂₁ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or an alicyclic hydrocarbon group, provided that at least one of R _{17 to} R ₂₁ Represents an alicyclic hydrocarbon group. Further, either R ₁₉ or R ₂₁ represents a linear or branched alkyl group or alicyclic hydrocarbon group having 1 to 4 carbon atoms.
R _{22 to} R ₂₅ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or an alicyclic hydrocarbon group, provided that at least one of R _{22 to} R ₂₅ Represents an alicyclic hydrocarbon group. R ₂₃ and R ₂₄ may be bonded to each other to form a ring.

In the general formulas (pI) to (pVI), the alkyl group in R _{12 to} R ₂₅ may be substituted or unsubstituted, and is a linear or branched alkyl group having 1 to 4 carbon atoms. Represents. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a t-butyl group.
Further, the further substituent of the alkyl group includes an alkoxy group having 1 to 4 carbon atoms, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), acyl group, acyloxy group, cyano group, hydroxyl group, A carboxy group, an alkoxycarbonyl group, a nitro group, etc. can be mentioned.

The alicyclic hydrocarbon group in R _{11 to} R _{25 or} the alicyclic hydrocarbon group formed by Z and a carbon atom may be monocyclic or polycyclic. Specific examples include groups having a monocyclo, bicyclo, tricyclo, tetracyclo structure or the like having 5 or more carbon atoms. The carbon number is preferably 6-30, and particularly preferably 7-25. These alicyclic hydrocarbon groups may have a substituent.
Below, the structural example of an alicyclic part is shown among alicyclic hydrocarbon groups.

  In the present invention, preferred examples of the alicyclic moiety include an adamantyl group, a noradamantyl group, a decalin residue, a tricyclodecanyl group, a tetracyclododecanyl group, a norbornyl group, a cedrol group, a cyclohexyl group, and a cycloheptyl group. Group, cyclooctyl group, cyclodecanyl group and cyclododecanyl group. More preferred are an adamantyl group, a decalin residue, a norbornyl group, a cedrol group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclodecanyl group, and a cyclododecanyl group.

Examples of the substituent that the alicyclic hydrocarbon group may have include an alkyl group, a halogen atom, a hydroxyl group, an alkoxy group, a carboxyl group, and an alkoxycarbonyl group.
The alkyl group is preferably a lower alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, or a butyl group, more preferably a substituent selected from the group consisting of a methyl group, an ethyl group, a propyl group, and an isopropyl group. Can be mentioned. Examples of the alkoxy group include those having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group.
The alkyl group, alkoxy group, and alkoxycarbonyl group may further have a substituent. Examples of such a substituent include an alkoxy group having 1 to 4 carbon atoms (methoxy group, ethoxy group, butoxy group). Group), hydroxy group, oxo group, alkylcarbonyl group (preferably 2 to 5 carbon atoms), alkylcarbonyloxy group group (preferably 2 to 5 carbon atoms), alkoxycarbonyl group (preferably 2 to 5 carbon atoms) And halogen atoms (chlorine atom, bromine atom, fluorine atom, etc.).

Further, the resin (B1) contains an alkali-soluble group such as a phenolic hydroxyl group, a carboxyl group, a sulfonic acid group, a hexafluoroisopropanol group (—C (CF ₃ ) ₂ ) in order to maintain good developability for an alkali developer. Other suitable polymerizable monomers may be copolymerized so that (OH) can be introduced, and other hydrophobic polymerizable monomers such as alkyl acrylates and alkyl methacrylates may be copolymerized to improve film quality. May be.

The content of the repeating unit represented by the general formula (II) is preferably 5 to 60 mol%, more preferably 10 to 50 mol%, and particularly preferably 10 to 40 mol% in all repeating units constituting the resin. It is.
The content of the repeating unit represented by the general formula (III) is preferably 40 to 90 mol%, more preferably 45 to 80 mol%, particularly preferably 50 to 75 mol% in all repeating units constituting the resin. It is.

The content of the repeating unit represented by the general formula (IV) is preferably 0 to 50 mol%, more preferably 10 to 40 mol%, and particularly preferably 15 to 30 mol% in all repeating units constituting the resin. It is.
The content of the repeating unit represented by the general formula (V) is preferably 0 to 30 mol%, more preferably 0 to 20 mol%, and particularly preferably 0 to 10 mol% in all repeating units constituting the resin. It is.

The content of the repeating unit having an alkali-soluble group such as a carboxy group or a sulfonic acid group other than a hydroxyl group is preferably 0 to 10 mol%, more preferably 1 to 8 mol%, in all repeating units constituting the resin. Most preferably, it is 2-6 mol%.
The content of the repeating unit having an acid-decomposable group is preferably 5 to 60 mol%, more preferably 10 to 55 mol%, particularly preferably 10 to 50 mol% in all repeating units constituting the resin (B1). It is.

  The synthesis of the resin (B1) is a precursor of a group that can be decomposed with an acid into an alkali-soluble resin, as described in European Patent No. 254853, JP-A-2-258500, 3-223860, and 4-251259. It can be synthesized by a known synthesis method such as a method of reacting the above, or a method of copolymerizing a monomer having a group decomposable with an acid with various monomers.

The weight average molecular weight of the resin (B1) is preferably 4,000 or less, more preferably 1,000 to 3,000, in terms of polystyrene by GPC method.
The dispersity (Mw / Mn) of the resin (B1) is preferably 1.0 to 3.0, more preferably 1.05 to 2.0, and even more preferably 1.1 to 1.7. .

  Moreover, you may use resin (B1) in combination of 2 or more types.

  Specific examples of the resin (B1) are shown below, but are not limited thereto.

  When irradiating the positive resist composition of the present invention with ArF excimer laser light, the resin of component (B) has a monocyclic or polycyclic alicyclic hydrocarbon structure, and is decomposed by the action of an acid. A resin (resin (B2)) having increased solubility in an alkali developer is preferred.

Resin (B2) having a monocyclic or polycyclic alicyclic hydrocarbon structure, decomposed by the action of an acid, and increased in solubility in an alkali developer (hereinafter also referred to as “alicyclic hydrocarbon-based acid-decomposable resin”) )
As a repeating unit having a partial structure containing an alicyclic hydrocarbon represented by the following general formula (pI) to general formula (pV) and a repeating unit represented by the following general formula (II-AB) A resin having at least one selected is preferable.

In general formulas (pI) to (pV),
R ₁₁ represents a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group or a sec-butyl group, and Z is an atom necessary for forming a cycloalkyl group together with a carbon atom. Represents a group.
R _{12 to} R ₁₆ each independently represents a linear or branched alkyl group or a cycloalkyl group. However, at least one of R _{12 to} R ₁₄ , or any of R ₁₅ and R ₁₆ represents a cycloalkyl group.
R _{17 to} R ₂₁ each independently represents a hydrogen atom, a linear or branched alkyl group, or a cycloalkyl group. However, at least one of R _{17 to} R ₂₁ represents a cycloalkyl group. In addition, any of R ₁₉ and R ₂₁ represents a linear or branched alkyl group or a cycloalkyl group.
R _{22 to} R ₂₅ each independently represents a hydrogen atom, a linear or branched alkyl group, or a cycloalkyl group. However, at least one of R _{22 to} R ₂₅ represents a cycloalkyl group. R ₂₃ and R ₂₄ may be bonded to each other to form a ring.

In general formula (II-AB),
R ₁₁ ′ and R ₁₂ ′ each independently represents a hydrogen atom, a cyano group, a halogen atom or an alkyl group.
Z ′ represents an atomic group for forming an alicyclic structure containing two bonded carbon atoms (C—C).

  The general formula (II-AB) is preferably the following general formula (II-AB1) or general formula (II-AB2).

In general formulas (II-AB1) and (II-AB2),
R ₁₃ ′ to R ₁₆ ′ each independently represents a hydrogen atom, a halogen atom, a cyano group, —COOH, —COOR ₅ , a group that decomposes by the action of an acid, —C (═O) —XA′—R. ₁₇ ′ represents an alkyl group or a cycloalkyl group. At least two _{members out of} R ₁₃ ′ to R ₁₆ ′ may combine to form a ring.
R ₅ represents an alkyl group, a cycloalkyl group, or a group having a lactone structure.
X represents an oxygen atom, a sulfur atom, -NH -, - NHSO ₂ - or an -NHSO ₂ NH-.
A ′ represents a single bond or a divalent linking group.
R ₁₇ ′ represents —COOH, —COOR ₅ , —CN, a hydroxyl group, an alkoxy group, —CO—NH—R ₆ , —CO—NH—SO ₂ —R ₆ or a group having a lactone structure.
R ₆ represents an alkyl group or a cycloalkyl group.
n represents 0 or 1.

In the general formulas (pI) to (pV), the alkyl group of R _{12 to} R ₂₅ is preferably a linear or branched alkyl group having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, n -Propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group and the like can be mentioned.

The cycloalkyl group or the cycloalkyl group formed by Z and the carbon atom in R _{12 to} R ₂₅ may be monocyclic or polycyclic. Specific examples include groups having a monocyclo, bicyclo, tricyclo, tetracyclo structure or the like having 5 or more carbon atoms. The carbon number is preferably 6-30, and particularly preferably 7-25.

Preferred cycloalkyl groups include adamantyl group, noradamantyl group, decalin residue, tricyclodecanyl group, tetracyclododecanyl group, norbornyl group, cedrol group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, A cyclodecanyl group and a cyclododecanyl group can be mentioned. More preferable examples include an adamantyl group, norbornyl group, cyclohexyl group, cyclopentyl group, tetracyclododecanyl group, and tricyclodecanyl group.

  These alkyl groups and cycloalkyl groups may have a further substituent. As further substituents of these alkyl groups and cycloalkyl groups, alkyl groups (1 to 4 carbon atoms), halogen atoms, hydroxyl groups, alkoxy groups (1 to 4 carbon atoms), carboxyl groups, alkoxycarbonyl groups (carbon numbers) 2-6). Examples of the substituent that the alkyl group, alkoxy group, alkoxycarbonyl group and the like may further have include a hydroxyl group, a halogen atom, and an alkoxy group.

  The structures represented by the general formulas (pI) to (pV) in the resin can be used for protecting alkali-soluble groups. Examples of the alkali-soluble group include various groups known in this technical field.

  Specific examples include a structure in which a hydrogen atom of a carboxylic acid group, a sulfonic acid group, a phenol group, or a thiol group is substituted with a structure represented by the general formulas (pI) to (pV). This is a structure in which a hydrogen atom of a carboxylic acid group or a sulfonic acid group is substituted with a structure represented by general formulas (pI) to (pV).

  As the repeating unit having an alkali-soluble group protected by a structure represented by the general formulas (pI) to (pV), a repeating unit represented by the following general formula (pA) is preferable.

In the general formula (pA),
R represents a hydrogen atom, a halogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms. A plurality of R may be the same or different.
A represents a single bond, an alkylene group, an ether group, a thioether group, a carbonyl group, an ester group, an amide group, a sulfonamide group, a urethane group or a urea group, or a combination of two or more groups. Represent. Preferably, it is a single bond.
Rp ₁ represents any group of the general formulas (pI) to (pV).

  The repeating unit represented by the general formula (pA) is most preferably a repeating unit of 2-alkyl-2-adamantyl (meth) acrylate and dialkyl (1-adamantyl) methyl (meth) acrylate.

  Hereinafter, although the specific example of the repeating unit represented by general formula (pA) is shown, this invention is not limited to this.

In the general formula (II-AB), examples of the halogen atom for R ₁₁ ′ and R ₁₂ ′ include a chlorine atom, a bromine atom, a fluorine atom, and an iodine atom.
Examples of the alkyl group for R ₁₁ ′ and R 1 ₂ ′ include linear or branched alkyl groups having 1 to 10 carbon atoms.
The atomic group for forming the alicyclic structure of Z ′ is an atomic group that forms a repeating unit having an alicyclic hydrocarbon structure which may have a substituent, and in particular, a bridged alicyclic ring An atomic group forming a repeating unit having the formula hydrocarbon structure is preferred.

Examples of the skeleton of the alicyclic hydrocarbon formed include the same alicyclic hydrocarbon groups as R _{12 to} R _{25 in} the general formulas (pI) to (pV).

The skeleton of the alicyclic hydrocarbon structure may have a substituent. Examples of such a substituent include R ₁₃ ′ to R ₁₆ ′ in the general formula (II-AB1) or (II-AB2).

  In the resin (B2), the group decomposed by the action of an acid is a repeating unit having a partial structure containing an alicyclic hydrocarbon represented by the general formula (pI) to the general formula (pV), a general formula It can be contained in at least one type of repeating unit among the repeating unit represented by (II-AB) and the repeating unit of the copolymerization component described later.

Various substituents of R ₁₃ ′ to R ₁₆ ′ in general formula (II-AB1) or general formula (II-AB2) form an alicyclic hydrocarbon structure in general formula (II-AB). It can also be a substituent for the atomic group Z for forming an atomic group for forming a bridged alicyclic hydrocarbon structure.

  Hereinafter, although the specific example of the repeating unit represented by general formula (II-AB1) or general formula (II-AB2) is given, this invention is not limited to these specific examples.

The resin (B2) preferably has a repeating unit having a group having a lactone structure.
Examples of the group having a lactone structure include those described as the atomic group L in the sulfonium salt compound represented by the aforementioned general formula (I). As a preferable lactone structure, a structure represented by any of the general formulas (LC1-1) to (LC1-16) described above is preferable, and as a more preferable lactone structure, (LC1-1), (LC1-4), ( LC1-5), (LC1-6), (LC1-13), and (LC1-14). The substituent (Rb ₂ ) is the same as described above.

The lactone structure moiety may or may not have a substituent (Rb ₂ ). Preferred substituents (Rb ₂ ) include an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an alkoxycarbonyl group having 1 to 8 carbon atoms, and a carboxyl group. , Halogen atom, hydroxyl group, cyano group, acid-decomposable group and the like. n ₂ represents an integer of 0-4. When n ₂ is 2 or more, a plurality of Rb ₂ may be the same or different, and a plurality of Rb ₂ may be bonded to form a ring.

As the repeating unit having a group having a lactone structure represented by any of the general formulas (LC1-1) to (LC1-16), R _{13 in the} general formula (II-AB1) or (II-AB2) may be used. Wherein at least one of 'to R ₁₆ ' is a group having a lactone structure represented by the general formulas (LC1-1) to (LC1-16) (for example, R _{5 of} -COOR ₅ is a group represented by the general formula And (LC1-1) to (LC1-16)), or a repeating unit represented by the following general formula (AI).

In general formula (AI),
Rb ₀ represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms. Preferred substituents that the alkyl group represented by Rb ₀ may have include a hydroxyl group and a halogen atom.
Examples of the halogen atom for Rb ₀ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Rb ₀ is preferably a hydrogen atom or a methyl group.
Ab represents a single bond, an alkylene group, a divalent linking group having a monocyclic or polycyclic alicyclic hydrocarbon structure, an ether group, an ester group, a carbonyl group, a carboxyl group, or a divalent group obtained by combining these. Represent.
Ab is preferably a single bond or a linking group represented by —Ab ₁ —CO ₂ —. Ab ₁ is
A linear, branched alkylene group, a monocyclic or polycyclic cycloalkylene group, preferably a methylene group, an ethylene group, a cyclohexyl group, an adamantyl group, or a norbornyl group.
V represents a group having a lactone structure represented by any one of the general formulas (LC1-1) to (LC1-16).

  The repeating unit having a lactone structure usually has an optical isomer, but any optical isomer may be used. One optical isomer may be used alone, or a plurality of optical isomers may be mixed and used. When one kind of optical isomer is mainly used, the optical purity (ee) thereof is preferably 90 or more, more preferably 95 or more.

  Specific examples of the repeating unit having a group having a lactone structure are given below, but the present invention is not limited thereto.

  The resin (B2) preferably has a repeating unit having a group having an alicyclic hydrocarbon structure substituted with a polar group. This improves the substrate adhesion and developer compatibility. The alicyclic hydrocarbon structure of the alicyclic hydrocarbon structure substituted with a polar group is preferably an adamantyl group, a diamantyl group, or a norbornane group. As the polar group, a hydroxyl group and a cyano group are preferable. As the group having an alicyclic hydrocarbon structure substituted with a polar group, groups represented by the following general formulas (VIIa) to (VIId) are preferable.

In general formulas (VIIa) to (VIIc),
R ₂ c to R ₄ c each independently represents a hydrogen atom, a hydroxyl group or a cyano group. However, at least one of R ₂ c to R ₄ c represents a hydroxyl group or a cyano group. Preferably, one or two of R ₂ c to R ₄ c are a hydroxyl group and the remaining is a hydrogen atom. In the general formula (VIIa), more preferably, _two of R ₂ c to R ₄ c are hydroxyl groups and the rest are hydrogen atoms.

The repeating unit having a group represented by general formulas (VIIa) to (VIId) includes at least one of R ₁₃ ′ to R ₁₆ ′ in general formula (II-AB1) or (II-AB2). , Having a group represented by general formulas (VIIa) to (VIId) (for example, R _{5 of} —COOR ₅ represents a group represented by general formulas (VIIa) to (VIId)), or the following general formula (A
The repeating units represented by IIa) to (AIId) can be mentioned.

In general formulas (AIIa) to (AIId),
R ₁ c represents a hydrogen atom, a methyl group, a trifluoromethyl group or a hydroxymethyl group.

  Although the specific example of the repeating unit represented by general formula (AIIa)-(AIIb) is given to the following, this invention is not limited to these.

  Resin (B2) may have a repeating unit represented by the following general formula (VIII).

In general formula (VIII):
Z ₂ represents —O— or —N (R ₄₁ ) —. R ₄₁ represents a hydrogen atom, a hydroxyl group, an alkyl group, or —OSO ₂ —R ₄₂ . R ₄₂ represents an alkyl group, a cycloalkyl group or a camphor residue. The alkyl group of R ₄₁ and R ₄₂ may be substituted with a halogen atom (preferably a fluorine atom) or the like.

Examples of the repeating unit represented by the general formula (VIII) include the following specific examples.
The present invention is not limited to these.

The resin (B2) preferably has a repeating unit having an alkali-soluble group, and more preferably has a repeating unit having a carboxyl group. By containing this, the resolution in contact hole applications increases. The repeating unit having a carboxyl group includes a repeating unit in which a carboxyl group is directly bonded to the main chain of the resin, such as a repeating unit of acrylic acid or methacrylic acid, or a carboxyl group in the main chain of the resin through a linking group. Either a repeating unit that is bonded, or a polymerization initiator or chain transfer agent having an alkali-soluble group is introduced at the end of the polymer chain at the time of polymerization, and the linking group is a monocyclic or polycyclic hydrocarbon. You may have a structure. Particularly preferred are repeating units of acrylic acid or methacrylic acid.
The weight average molecular weight of the resin (B2) is preferably 4,000 or less, more preferably 1,000 to 3,000, in terms of polystyrene by GPC method.
The dispersity (Mw / Mn) of the resin (B2) is preferably 1.0 to 3.0, more preferably 1.05 to 2.0, and even more preferably 1.1 to 1.7. .

  In the positive resist composition of the present invention, the blending amount of the resin (B) in the composition is preferably 40 to 79% by mass, more preferably 50 to 70% by mass, based on the total solid content of the composition.

[3] Basic compound (C)
The resist composition of the present invention preferably contains a basic compound in order to reduce the change in performance over time from exposure to heating. The basic compound serves to quench the deprotection reaction by the acid generated by exposure, and its diffusibility and basicity affect the substantial acid diffusibility.

  Preferable structures include basic compounds having structures represented by the following formulas (A) to (E).

Here, R ²⁵⁰ , R ²⁵¹ and R ²⁵² are each independently a hydrogen atom, an alkyl group (preferably having 1 to 20 carbon atoms), a cycloalkyl group (preferably having 3 to 20 carbon atoms) or an aryl group (preferably carbon). Where R ²⁵⁰ and R ²⁵¹ may combine with each other to form a ring.
These may have a substituent. 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, and 1 to 1 carbon atoms. A 20 hydroxyalkyl group or a C 3-20 hydroxycycloalkyl group is preferred.
These may contain an oxygen atom, a sulfur atom, or a nitrogen atom in the alkyl chain.

In the formula, R ²⁵³ , R ²⁵⁴ , R ²⁵⁵ and R ²⁵⁶ each independently represents an alkyl group (preferably having 1 to 6 carbon atoms) or a cycloalkyl group (preferably having 3 to 6 carbon atoms).

  Preferable compounds include guanidine, aminopyrrolidine, pyrazole, pyrazoline, piperazine, aminomorpholine, aminoalkylmorpholine, and piperidine, and may have a substituent. More preferable compounds include compounds having an imidazole structure, a diazabicyclo structure, an onium hydroxide structure, an onium carboxylate structure, a trialkylamine structure, an aniline structure or a pyridine structure, an alkylamine derivative having a hydroxyl group and / or an ether bond, a hydroxyl group and / or Or the aniline derivative which has an ether bond etc. can be mentioned.

Examples of the compound having an imidazole structure include imidazole, 2,4,5-triphenylimidazole, benzimidazole, and the like. Examples of the compound having a diazabicyclo structure include 1,4-diazabicyclo [2,2,2] octane, 1,5-diazabicyclo [4,3,0] non-5-ene, and 1,8-diazabicyclo [5,4,0. ] Undec-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.

  Further, at least one nitrogen-containing compound selected from an amine compound having a phenoxy group, an ammonium salt compound having a phenoxy group, an amine compound having a sulfonic acid ester group, and an ammonium salt compound having a sulfonic acid ester group can be exemplified. .

As the amine compound, a primary, secondary or tertiary amine compound can be used, and an amine compound in which at least one alkyl group is bonded to a nitrogen atom is preferable. The amine compound is more preferably a tertiary amine compound. As long as at least one alkyl group (preferably having 1 to 20 carbon atoms) is bonded to a nitrogen atom, the amine compound has an cycloalkyl group (preferably having 3 to 20 carbon atoms) or an aryl group (preferably having 3 to 20 carbon atoms). Preferably C6-C12) may be bonded to a nitrogen atom.
The amine compound preferably has an oxygen atom in the alkyl chain and an oxyalkylene group is formed. The number of oxyalkylene groups is one or more in the molecule, preferably 3 to 9, and more preferably 4 to 6. Among the oxyalkylene groups, an oxyethylene group (—CH ₂ CH ₂ O—) or an oxypropylene group (—CH (CH ₃ ) CH ₂ O— or —CH ₂ CH ₂ CH ₂ O—) is preferable, and more preferably oxy Ethylene group.

As the ammonium salt compound, a primary, secondary, tertiary, or quaternary ammonium salt compound can be used, and an ammonium salt compound in which at least one alkyl group is bonded to a nitrogen atom is preferable. As long as at least one alkyl group (preferably having 1 to 20 carbon atoms) is bonded to a nitrogen atom, the ammonium salt compound has a cycloalkyl group (preferably having 3 to 20 carbon atoms) or an aryl group in addition to the alkyl group. (Preferably having 6 to 12 carbon atoms) may be bonded to a nitrogen atom.
The ammonium salt compound preferably has an oxygen atom in the alkyl chain and an oxyalkylene group is formed. The number of oxyalkylene groups is one or more in the molecule, preferably 3 to 9, and more preferably 4 to 6. Among the oxyalkylene groups, an oxyethylene group (—CH ₂ CH ₂ O—) or an oxypropylene group (—CH (CH ₃ ) CH ₂ O— or —CH ₂ CH ₂ CH ₂ O—) is preferable, and more preferably oxy Ethylene group.
Examples of the anion of the ammonium salt compound include halogen atoms, sulfonates, borates, and phosphates. Among them, halogen atoms and sulfonates are preferable. As the halogen atom, chloride, bromide, and iodide are particularly preferable. As the sulfonate, an organic sulfonate having 1 to 20 carbon atoms is particularly preferable. Examples of the organic sulfonate include alkyl sulfonates having 1 to 20 carbon atoms and aryl sulfonates. The alkyl group of the alkyl sulfonate may have a substituent, and examples of the substituent include fluorine, chlorine, bromine, alkoxy groups, acyl groups, and aryl groups. Specific examples of the alkyl sulfonate include methane sulfonate, ethane sulfonate, butane sulfonate, hexane sulfonate, octane sulfonate, benzyl sulfonate, trifluoromethane sulfonate, pentafluoroethane sulfonate, and nonafluorobutane sulfonate. Examples of the aryl group of the aryl sulfonate include a benzene ring, a naphthalene ring, and an anthracene ring. The benzene ring, naphthalene ring and anthracene ring may have a substituent, and the substituent is preferably a linear or branched alkyl group having 1 to 6 carbon atoms or a cycloalkyl group having 3 to 6 carbon atoms. Specific examples of the linear or branched alkyl group and cycloalkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, i-butyl, t-butyl, n-hexyl, cyclohexyl and the like. Examples of the other substituent include an alkoxy group having 1 to 6 carbon atoms, a halogen atom, cyano, nitro, an acyl group, and an acyloxy group.

  The amine compound having a phenoxy group and the ammonium salt compound having a phenoxy group are those having a phenoxy group at the terminal opposite to the nitrogen atom of the alkyl group of the amine compound or ammonium salt compound. The phenoxy group may have a substituent. Examples of the substituent of the phenoxy group include an alkyl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, a carboxyl group, a carboxylic acid ester group, a sulfonic acid ester group, an aryl group, an aralkyl group, an acyloxy group, and an aryloxy group. Etc. The substitution position of the substituent may be any of the 2-6 positions. The number of substituents may be any in the range of 1 to 5.

It is preferable to have at least one oxyalkylene group between the phenoxy group and the nitrogen atom. The number of oxyalkylene groups is one or more in the molecule, preferably 3 to 9, and more preferably 4 to 6. Among the oxyalkylene groups, an oxyethylene group (—CH ₂ CH ₂ O—) or an oxypropylene group (—CH (CH ₃ ) CH ₂ O— or —CH ₂ CH ₂ CH ₂ O—) is preferable, and more preferably oxy Ethylene group.

  In the amine compound having a sulfonic acid ester group and the ammonium salt compound having a sulfonic acid ester group, the sulfonic acid ester group may be any of alkyl sulfonic acid ester, cycloalkyl group sulfonic acid ester, and aryl sulfonic acid ester. In the case of an alkyl sulfonate ester, the alkyl group has 1 to 20 carbon atoms, in the case of a cycloalkyl sulfonate ester, the cycloalkyl group has 3 to 20 carbon atoms, and in the case of an aryl sulfonate ester, the aryl group has 6 carbon atoms. ~ 12 are preferred. Alkyl sulfonic acid ester, cycloalkyl sulfonic acid ester, and aryl sulfonic acid ester may have a substituent. Examples of the substituent include a halogen atom, a cyano group, a nitro group, a carboxyl group, a carboxylic acid ester group, and a sulfonic acid. An ester group is preferred.

It is preferable to have at least one oxyalkylene group between the sulfonate group and the nitrogen atom. The number of oxyalkylene groups is one or more in the molecule, preferably 3 to 9, and more preferably 4 to 6. Among the oxyalkylene groups, an oxyethylene group (—CH ₂ CH ₂ O—) or an oxypropylene group (—CH (CH ₃ ) CH ₂ O— or —CH ₂ CH ₂ CH ₂ O—) is preferable, and more preferably oxy Ethylene group.

  The amine compound having a phenoxy group is prepared by reacting a primary or secondary amine having a phenoxy group with a haloalkyl ether by heating, and then adding an aqueous solution of a strong base such as sodium hydroxide, potassium hydroxide or tetraalkylammonium. It can be obtained by extraction with an organic solvent such as ethyl acetate or chloroform. Alternatively, after reacting by heating a primary or secondary amine and a haloalkyl ether having a phenoxy group at the end, an aqueous solution of a strong base such as sodium hydroxide, potassium hydroxide, or tetraalkylammonium is added, and then ethyl acetate, It can be obtained by extraction with an organic solvent such as chloroform.

These basic compounds are used alone or in combination of two or more.
The molecular weight of the basic compound is preferably 250 to 1000, more preferably 250 to 800, and still more preferably 400 to 800.
The content of the basic compound is preferably 1.0 to 8.0% by mass, more preferably 1.5 to 5.0% by mass, and still more preferably based on the total solid content of the composition. It is 2.0-4.0 mass%.

[4] Solid content concentration and solvent (D)
The resist composition of the present invention is prepared by dissolving the above components in a solvent.
It is preferable to adjust the total solid content concentration in the resist composition to 1.0 to 4.5% by mass, more preferably 2.0 to 4% in terms of suppressing sensitivity fluctuations due to refrigeration and storage at room temperature. It is 0.0 mass%, More preferably, it is 2.0-3.0 mass%.
The total solid content corresponds to the composition obtained by removing the solvent, and corresponds to the mass of the dried coating film formed from the composition.

Solvents for preparing the resist composition 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-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, tetrahydrofuran, and other organic solvents Preferably, more preferably cyclohexanone, .gamma.-butyrolactone, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, and particularly preferably propylene glycol monomethyl ether.
The solvent may be a single solvent or a mixed solvent in which two or more are mixed.
Of the total amount of solvent, it is particularly preferable to contain 50% by mass or more of propylene glycol monomethyl ether, most preferably 50 to 80% by mass. As the solvent used in combination with propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, cyclohexanone and ethyl lactate are preferable, and propylene glycol monomethyl ether acetate is most preferable.

  In addition to the above components, the resist composition of the present invention may contain the following components.

[5] Fluorine-based and / or silicon-based surfactant (E)
The resist composition of the present invention further includes any one of fluorine-based and / or silicon-based surfactants (fluorine-based surfactants and silicon-based surfactants, surfactants containing both fluorine atoms and silicon atoms). Or it is preferable to contain 2 or more types.

  When the resist composition of the present invention contains fluorine and / or a silicon-based surfactant, it is possible to provide a resist pattern with less adhesiveness and development defects with good sensitivity and resolution.

Examples of these fluorine and / or silicon surfactants include, for example, JP-A No. 62-36663, JP-A No. 61-226746, JP-A No. 61-226745, JP-A No. 62-170950, JP 63-34540 A, JP 7-230165 A, JP 8-62834 A, JP 9-54432 A, JP 9-5988 A, JP 2002-277862 A, US Patent Nos. 5,405,720, 5,360,692, 5,529,881, 5,296,330, 5,436,098, 5,576,143, 5,294,511, 582
The surfactant described in the specification of No. 4451 can be mentioned, and the following commercially available surfactants can also be used as they are.

Examples of commercially available surfactants that can be used include F-top EF301, EF303 (manufactured by Shin-Akita Kasei Co., Ltd.), Florard FC430, 431 (manufactured by Sumitomo 3M Co., Ltd.), MegaFuck F171, F173, F176, F189, 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. The fluoroaliphatic compound can be synthesized by the method described in JP-A-2002-90991.

  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. It 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.

  The amount of fluorine and / or silicon surfactant used is preferably 0.0001 to 2% by mass, more preferably 0.001 to 1% by mass, based on the total solid content of the resist composition.

[6] Dissolution inhibiting compound (F) having a molecular weight of 3000 or less, which is decomposed by the action of an acid to increase the solubility in an alkaline developer.
Hereinafter, it is also referred to as “component (F)” or “dissolution inhibitor compound”.
(F) As a dissolution-inhibiting compound having a molecular weight of 3000 or less that decomposes by the action of an acid and increases its solubility in an alkaline developer, the transmittance of 220 nm or less is not lowered, so Proceeding of SPIE, 2724, 355 (1996) An alicyclic or aliphatic compound containing an acid-decomposable group is preferred, such as a cholic acid derivative containing an acid-decomposable group described in 1).

  When the resist composition of the present invention is irradiated with an electron beam, it preferably contains a structure in which the phenolic hydroxyl group of the phenol compound is substituted with an acid-decomposable group. As a phenol compound, what contains 1-9 phenol frame | skeleton is preferable, More preferably, it contains 2-6 pieces.

  The molecular weight of the dissolution inhibiting compound in the present invention is 3000 or less, preferably 300 to 3000, and more preferably 500 to 2500.

  The addition amount of the dissolution inhibiting compound is preferably 3 to 50% by mass, more preferably 5 to 40% by mass, based on the total solid content of the resist composition.

  Specific examples of the dissolution inhibiting compound are shown below, but the present invention is not limited thereto.

[7] Other Additives The resist composition of the present invention further promotes solubility in dyes, plasticizers, surfactants other than the above component (E), photosensitizers, and developers as necessary. The compound to be made can be contained.

  The dissolution accelerating compound for the developer that can be used in the present invention is a low molecular weight compound having a molecular weight of 1,000 or less and having two or more phenolic OH groups or one or more carboxy groups. When it has a carboxy group, an alicyclic or aliphatic compound is preferable.

  A preferable addition amount of these dissolution promoting compounds is 2 to 50% by mass, and more preferably 5 to 30% by mass with respect to the resin of the component (A). 50 mass% or less is preferable at the point of development residue suppression and the pattern deformation prevention at the time of image development.

  Such phenolic compounds having a molecular weight of 1000 or less can be obtained by referring to methods described in, for example, JP-A-4-1222938, JP-A-2-28531, U.S. Pat. No. 4,916,210, European Patent 219294, and the like. Can be easily synthesized.

  Specific examples of alicyclic or aliphatic compounds having a carboxyl group include carboxylic acid derivatives having a steroid structure such as cholic acid, deoxycholic acid, lithocholic acid, adamantane carboxylic acid derivatives, adamantane dicarboxylic acid, cyclohexane carboxylic acid, cyclohexane Examples thereof include, but are not limited to, dicarboxylic acids.

  In the present invention, a surfactant other than the above (E) fluorine-based and / or silicon-based surfactant may be added. Specifically, nonionic interfaces such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene / polyoxypropylene block copolymers, sorbitan aliphatic esters, polyoxyethylene sorbitan aliphatic esters, etc. Mention may be made of activators.

  These surfactants may be added alone or in some combination.

[8] Pattern Forming Method The resist composition of the present invention is coated on a support such as a substrate to form a resist film. The thickness of this resist film is preferably 0.02 to 0.1 μm, and more preferably 0.04 to 0.06 μm.
As a method of coating on the substrate, spin coating is preferable, and the rotation speed is preferably 1000 to 3000 rpm.

For example, a resist film is formed by applying and drying a resist composition on a substrate (eg, silicon / silicon dioxide coating) used for manufacturing a precision integrated circuit element by an appropriate application method such as a spinner or a coater. . In addition, a known antireflection film can be applied in advance.
The resist film is irradiated with an electron beam, X-rays or EUV, preferably baked (heated) and developed. Thereby, a good pattern can be obtained.

In the development step, an alkaline developer is used as follows. As an alkaline developer of the resist composition, inorganic hydroxides such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and 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, tetramethylammonium hydroxide, tetraethylammonium hydroxide and the like Alkaline aqueous solutions such as quaternary ammonium salts, cyclic amines such as pyrrole and pihelidine can be used.
Furthermore, alcohols and surfactants can be added in appropriate amounts to the alkaline developer.
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 still in detail, the content of this invention is not limited by this.

<Synthesis of Compound (A)>
The compound (A) used in the following Examples was synthesized based on the method described in JP-A-2007-178848.

<Resin (B)>
The structure, molecular weight, and dispersity of the resin (B) used in the examples are shown. The number on the right side of the repeating unit represents the molar ratio. The same shall apply hereinafter.

[Examples 1-29 and Comparative Examples 1-3]
<Resist preparation>
The components shown in the following table were dissolved in a solvent to prepare a solution having a solid content concentration of 4% by mass, and this was filtered through a polyethylene filter having a pore size of 0.1 μm to prepare a positive resist solution. The prepared positive resist solution was evaluated by the following method, and the results are shown in the table.

<Resist evaluation>
The positive resist solution prepared as described above is uniformly applied on a silicon wafer subjected to hexamethyldisilazane treatment using a spin coater, and is heated and dried at 120 ° C. for 90 seconds to obtain a positive film thickness of 0.06 μm. A mold resist film was formed. The 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, it was baked at 110 ° C. for 90 seconds, immersed in an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution for 60 seconds, rinsed with water for 30 seconds and dried. The obtained pattern was evaluated by the following method.

[sensitivity]
The cross-sectional shape of the obtained pattern was observed using a scanning electron microscope (S-4800, manufactured by Hitachi, Ltd.). The minimum irradiation energy when resolving a 150 nm line (line: space = 1: 1) was defined as sensitivity.
[resolution]
The line size (line: space = 1: 1) in which separation resolution is recognized even when a part of the pattern is tilted is used as the limit resolution size at the irradiation dose showing the above sensitivity, and this is the resolution. Defined.

[Line edge roughness (LER)]
The distance from the reference line where there should be an edge using a scanning electron microscope (S-9220, manufactured by Hitachi, Ltd.) at any 30 points in the length direction of 50 μm of the 150 nm line pattern at the irradiation dose showing the sensitivity described above. Was measured, the standard deviation was obtained, and 3σ was calculated. A smaller value means better performance.

[Pattern profile]
The profile of the 150 nm line (line: space = 1: 1) in the sensitivity was observed with a scanning microscope (SEM).

  The evaluation results are shown in the table.

[Basic compounds]
N-1: Trioctylamine N-2: 1,5-diazabicyclo [4.3.0] -5-nonene N-3: 2,4,6-triphenylimidazole [surfactant]
W-1: Megafuck F176 (manufactured by Dainippon Ink & Chemicals, Inc.)
W-2: Megafuck R08 (Dainippon Ink Chemical Co., Ltd.)
W-3: Troisol S-366 (manufactured by Troy Chemical Co., Ltd.)
W-4: Polyoxyethylene lauryl ether [solvent]
S-1: Propylene glycol monomethyl ether acetate (PGMEA)
S-2: Propylene glycol monomethyl ether (PGME)
S-3: Ethyl lactate S-4: Cyclohexanone

  From the above results, it can be seen that the resist composition of the present invention has high sensitivity, high resolution, low LER, and good pattern shape as compared with the composition of the comparative example in the evaluation in electron beam lithography. It is expected to show similar performance in EUV exposure.

Claims (5)

(A) A positive resist composition comprising at least 21% by mass of a sulfonium salt compound represented by the following general formula (I) with respect to the total solid content in the positive resist composition.

In general formula (I),
A represents a (m + 1) -valent linking group. When there are a plurality of A, they may be bonded to each other to form a cyclic structure.
R represents a monovalent organic group. When there are two R, they may be bonded to each other to form a cyclic structure.
L represents a lactone ring structure.
X ⁻ represents an anion.
n represents an integer of 1 to 3.
m represents 1 or 2.
When there are a plurality of A, R and L, they may be the same or different.   2. The positive resist composition according to claim 1, further comprising (B) a resin having a weight average molecular weight of 4000 or less, decomposed by the action of an acid, and increased in solubility in an alkali developer.   3. The positive resist composition according to claim 1, wherein the (m + 1) -valent linking group of A in the general formula (I) has an aromatic ring. In formula (I), the anion of X ⁻ is an organic sulfonate anion (R ¹ —SO ₃ ⁻ ), an organic carboxylate anion (R ¹ —CO ₂ ⁻ ), an organic imido acid anion (N ⁻ ( _{^{SO 2 -R 1) 2, N}} - (SO 2 -R 1) (CO-R 1)) or an organic methide anion ^(C - (claims, characterized in that SO ₂ -R ¹⁾ ₃₎ is The positive resist composition according to any one of 1 to 3 . Here, R ¹ represents a monovalent organic group, and when there are a plurality of R ¹ groups, they may be the same or different.   A pattern formation comprising a step of forming a resist film from the resist composition according to claim 1, and exposing and developing the resist film with an electron beam, an X-ray, or EUV light. Method.