Salt, quencher, resist composition and method for producing resist pattern

Abstract

A salt represented by formula (I), a quencher, and a resist composition including the same: ##STR00001## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 each represent a halogen atom, an alkyl fluoride group having 1 to 6 carbon atoms or a hydrocarbon group having 1 to 18 carbon atoms, —CH.sub.2— included in the hydrocarbon group may be replaced by —O— or —CO—; and m1, m2, m3 and m4 represent an integer of 0 to 4. When m1 is 2 or more, a plurality of R.sup.1 may be the same or different from each other. When m2 is 2 or more, a plurality of R.sup.2 may be the same or different from each other. When m3 is 2 or more, a plurality of R.sup.3 may be the same or different from each other. When m4 is 2 or more, a plurality of R.sup.4 may be the same or different from each other.

Claims

1. A salt represented by formula (I): ##STR00218## wherein, in formula (I), R.sup.1, R.sup.2, R.sup.3 and R.sup.4 each independently represent a halogen atom, an alkyl fluoride group having 1 to 6 carbon atoms or a hydrocarbon group having 1 to 18 carbon atoms, and —CH.sub.2— included in the hydrocarbon group may be replaced by —O— or —CO—, m1 represents an integer of 0 to 4, and when m1 is 2 or more, a plurality of R.sup.1 may be the same or different from each other, m2 represents an integer of 0 to 4, and when m2 is 2 or more, a plurality of R.sup.2 may be the same or different from each other, m3 represents an integer of 0 to 4, and when m3 is 2 or more, a plurality of R.sup.3 may be the same or different from each other, and m4 represents an integer of 0 to 4, and when m4 is 2 or more, a plurality of R.sup.4 may be the same or different from each other.

2. A quencher comprising the salt according to claim 1.

3. A resist composition comprising the quencher according to claim 2, a resin including a structural unit having an acid-labile group, and an acid generator.

4. The resist composition according to claim 3, wherein the resin including a structural unit having an acid-labile group includes at least one selected from the group consisting of a structural unit represented by formula (a1-1) and a structural unit represented by formula (a1-2): ##STR00219## wherein, in formula (a1-1) and formula (a1-2), L.sup.a1 and L.sup.a2 each independently represent —O— or *—O—(CH.sub.2).sub.k1—CO—O—, k1 represents an integer of 1 to 7, and * represents a bonding site to —CO—, R.sup.a4 and R.sup.a5 each independently represent a hydrogen atom or a methyl group, R.sup.a6 and R.sup.a7 each independently represent an alkyl group having 1 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, or a group obtained by combining these groups, m1 represents an integer of 0 to 14, n1 represents an integer of 0 to 10, and n1′ represents an integer of 0 to 3.

5. The resist composition according to claim 3, wherein the resin including a structural unit having an acid-labile group includes a structural unit represented by formula (a2-A): ##STR00220## wherein, in formula (a2-A), R.sup.a50 represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, R.sup.a51 represents a halogen atom, a hydroxy group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylcarbonyl group having 2 to 4 carbon atoms, an alkylcarbonyloxy group having 2 to 4 carbon atoms, an acryloyloxy group or a methacryloyloxy group, A.sup.a50 represents a single bond or *—X.sup.a51-(A.sup.a52-X.sup.a52).sub.nb—, and * represents a bonding site to carbon atoms to which —R.sup.a50 is bonded, A.sup.a52 represents an alkanediyl group having 1 to 6 carbon atoms, X.sup.a51 and X.sup.a52 each independently represent —O—, —CO—O— or —O—CO—, nb represents 0 or 1, and mb represents an integer of 0 to 4, and when mb is an integer of 2 or more, a plurality of R.sup.a51 may be the same or different from each other.

6. The resist composition according to claim 3, wherein the acid generator includes a salt represented by formula (B1): ##STR00221## wherein, in formula (B1), Q.sup.b1 and Q.sup.b2 each independently represent a fluorine atom or a perfluoroalkyl group having 1 to 6 carbon atoms, L.sup.b1 represents a divalent saturated hydrocarbon group having 1 to 24 carbon atoms, —CH.sub.2— included in the divalent saturated hydrocarbon group may be replaced by —O— or —CO—, and a hydrogen atom included in the divalent saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group, Y represents a methyl group which may have a substituent, or an alicyclic hydrocarbon group having 3 to 24 carbon atoms which may have a substituent, and —CH.sub.2— included in the alicyclic hydrocarbon group may be replaced by —O—, —S(O).sub.2— or —CO—, and Z.sup.+ represents an organic cation.

7. The resist composition according to claim 3, further comprising a salt generating an acid having an acidity lower than that of an acid generated from the acid generator.

8. A method for producing a resist pattern, which comprises: (1) a step of applying the resist composition according to claim 3 on a substrate, (2) a step of drying the applied composition to form a composition layer, (3) a step of exposing the composition layer, (4) a step of heating the exposed composition layer, and (5) a step of developing the heated composition layer.

Description

EXAMPLES

(1) The present invention will be described more specifically by way of Examples. Percentages and parts expressing the contents or amounts used in the Examples are by mass unless otherwise specified.

(2) The weight-average molecular weight is a value determined by gel permeation chromatography under the following conditions.

(3) Apparatus: Model HLC-8120GPC (manufactured by TOSOH CORPORATION)

(4) Column: TSKgel Multipore IIXL-M×3+guardcolumn (manufactured by TOSOH CORPORATION)

(5) Eluent: tetrahydrofuran

(6) Flow rate: 1.0 mL/min

(7) Detector: RI detector

(8) Column temperature: 40° C.

(9) Injection amount: 100 μl

(10) Molecular weight standards: polystyrene standard (manufactured by TOSOH CORPORATION)

(11) Structures of compounds were confirmed by measuring a molecular ion peak using mass spectrometry (Liquid Chromatography: Model 1100, manufactured by Agilent Technologies, Inc., Mass Spectrometry: Model LC/MSD, manufactured by Agilent Technologies, Inc.). The value of this molecular ion peak in the following Examples is indicated by “MASS”.

Example 1: Synthesis of Salt Represented by Formula (I-3)

(12) ##STR00210##

(13) 2.76 Parts of a compound represented by formula (I-3-a), 50 parts of chloroform, 4.06 parts of a compound represented by formula (I-3-b) and 4.00 parts of trifluoromethanesulfonic acid were mixed, followed by stirring at 23° C. for 30 minutes and further cooling to 5° C. To the mixture thus obtained, 6.99 parts of trifluoroacetic anhydride was added dropwise over 15 minutes, followed by stirring at 23° C. for 18 hours. To the mixture thus obtained, 8.08 parts of triethylamine and 16.17 parts of ion-exchanged water were added and, after stirring at 23° C. for 30 minutes, an organic layer was isolated through separation. To the organic layer thus obtained, 50 part of an aqueous 5% oxalic acid solution was added and, after stirring at 23° C. for 30 minutes, an organic layer was isolated through separation. To the organic layer thus obtained, 50 parts of ion-exchanged water was added and, after stirring at 23° C. for 30 minutes, an organic layer was isolated through separation. This water washing operation was performed five times. The organic layer thus obtained was concentrated and then the concentrated residue was isolated from a column (silica gel 60N (spherical, neutral) 100-210 μm; manufactured by Kanto Chemical Co., Inc., developing solvent: chloroform/methanol=1/1) to obtain 0.52 part of a salt represented by formula (I-3).

(14) MASS (ESI (+) Spectrum): 545.1 [M+H].sup.+

Example 2: Synthesis of Salt Represented by Formula (I-13)

(15) ##STR00211##

(16) 3.61 Parts of a compound represented by formula (I-3-a), 30 parts of chloroform, 6.60 parts of a compound represented by formula (I-13-b) and 8.74 parts of trifluoromethanesulfonic acid were mixed, followed by stirring at 23° C. for 30 minutes and further cooling to 5° C. To the mixture thus obtained, 12.24 parts of trifluoroacetic anhydride was added dropwise over 15 minutes, followed by stirring at 23° C. for 12 hours. To the mixture thus obtained, 40 parts of ion-exchanged water was added and, after stirring at 23° C. for 30 minutes, an organic layer was isolated through separation. To the organic layer thus obtained, 35 parts of an aqueous 10% sodium hydroxide solution was added and, after stirring at 23° C. for 30 minutes, an organic layer was isolated through separation. This operation was performed three times. The organic layer thus obtained was concentrated and then the concentrate was made to pass through an ion exchange resin (Aldrich (QAE Sephadex® A-25 chloride form)) using methanol as a developing solvent. The solution passed therethrough was concentrated and then 80 parts of chloroform and 40 parts of an aqueous 10% sodium hydroxide solution were added and, after stirring at 23° C. for 30 minutes, an organic layer was isolated through separation. To the organic layer thus obtained, 40 parts of an aqueous 5% oxalic acid solution was added and, after stirring at 23° C. for 30 minutes, an organic layer was isolated through separation. To the organic layer thus obtained, 40 parts of ion-exchanged water was added and, after stirring at 23° C. for 30 minutes, an organic layer was isolated through separation. This water washing operation was performed five times. The organic layer thus obtained was concentrated and then the concentrated residue was isolated from a column (silica gel 60N (spherical, neutral) 100-210 μm; manufactured by Kanto Chemical Co., Inc., developing solvent: chloroform/methanol=1/1) to obtain 0.44 part of a salt represented by formula (I-13).

(17) MASS (ESI (+) Spectrum): 637.1 [M+H].sup.+

Example 3: Synthesis of Salt Represented by Formula (I-14)

(18) ##STR00212##

(19) 3.61 Parts of a compound represented by formula (I-3-a), 30 parts of chloroform, 6.19 parts of a compound represented by formula (I-14-b) and 8.74 parts of trifluoromethanesulfonic acid were mixed, followed by stirring at 23° C. for 30 minutes and further cooling to 5° C. To the mixture thus obtained, 12.24 parts of trifluoroacetic anhydride was added dropwise over 15 minutes, followed by stirring at 23° C. for 12 hours. To the mixture thus obtained, 40 parts of ion-exchanged water was added and, after stirring at 23° C. for 30 minutes, an organic layer was isolated through separation. To the organic layer thus obtained, 35 parts of an aqueous 10% sodium hydroxide solution was added and, after stirring at 23° C. for 30 minutes, an organic layer was isolated through separation. This operation was performed three times. The organic layer thus obtained was concentrated and then the concentrate was made to pass through an ion exchange resin (Aldrich (QAE Sephadex® A-25 chloride form)) using methanol as a developing solvent. The solution passed therethrough was concentrated and then 80 parts of chloroform and 40 parts of an aqueous 10% sodium hydroxide solution were added and, after stirring at 23° C. for 30 minutes, an organic layer was isolated through separation. To the organic layer thus obtained, 40 parts of an aqueous 5% oxalic acid solution was added and, after stirring at 23° C. for 30 minutes, an organic layer was isolated through separation. To the organic layer thus obtained, 40 parts of ion-exchanged water was added and, after stirring at 23° C. for 30 minutes, an organic layer was isolated through separation. This water washing operation was performed five times. The organic layer thus obtained was concentrated and then the concentrated residue was isolated from a column (silica gel 60N (spherical, neutral) 100-210 μm; manufactured by Kanto Chemical Co., Inc., developing solvent: chloroform/methanol=1/1) to obtain 0.38 part of a salt represented by formula (I-14).

(20) MASS (ESI (+) Spectrum): 609.1 [M+H].sup.+

(21) Synthesis of Resin

(22) Compounds (monomers) used in the synthesis of the resin (A) are shown below. Hereinafter, these compounds are referred to as “monomer (a1-1-3)” according to the number of formula.

(23) ##STR00213##

Synthesis Example 1 [Synthesis of Resin A1]

(24) Using a monomer (a1-4-2), a monomer (a1-1-3) and a monomer (a1-2-6) as monomers, these monomers were mixed in a molar ratio of 38:24:38 [monomer (a1-4-2):monomer (a1-1-3):monomer (a1-2-6)], and methyl isobutyl ketone was added to this monomer mixture in the amount of 1.5 mass times the total mass of all monomers. To the mixture thus obtained, azobisisobutyronitrile as an initiator was added in the amount of 7 mol % based on the total molar number of all monomers, and then the mixture was polymerized by heating at 85° C. for about 5 hours. To the polymerization reaction solution thus obtained, an aqueous p-toluenesulfonic acid solution was added. After stirring for 6 hours, an organic layer was isolated through separation. The organic layer thus obtained was poured into a large amount of n-heptane to precipitate a resin, followed by filtration and collection to obtain a resin A1 (copolymer) having a weight-average molecular weight of about 5.3×10.sup.3 in a yield of 78%. This resin A1 has the following structural units.

(25) ##STR00214##
<Preparation of Resist Compositions>

(26) As shown in Table 1, the following respective components were mixed, and the mixtures thus obtained were filtered through a fluorine resin filter having a pore diameter of 0.2 μm to prepare resist compositions.

(27) TABLE-US-00001 TABLE 1 Resist Acid Quencher composition Resin generator Salt (I) (C) PB/PEB Composi- A1 = B1-43 = I-3 = — 110° C./120° C. tion 1 10 parts 3.4 parts 0.7 parts Composi- A1 = B1-43 = I-3 = C1 = 110° C./120° C. tion 2 10 parts 3.4 parts 0.5 parts 0.2 parts Composi- A1 = B1-43 = I-13 = — 110° C./120° C. tion 3 10 parts 3.4 parts 0.7 parts Composi- A1 = B1-43 = I-14 = — 110° C./120° C. tion 4 10 parts 3.4 parts 0.7 parts Comparative A1 = B1-43 = — IX-1 = 110° C./120° C. Composi- 10 parts 3.4 parts 0.7 parts tion 1
<Resin>

(28) A1: Resin A1

(29) <Acid Generator (B)>

(30) B1-43: Salt represented by formula (B1-43) (synthesized in accordance with Examples of JP 2016-47815 A)

(31) ##STR00215##
<Salt (I)>

(32) I-3: Salt represented by formula (I-3)

(33) I-13: Salt represented by formula (I-13)

(34) I-14: Salt represented by formula (I-14)

(35) <Quencher (C)>

(36) IX-1:

(37) ##STR00216##

(38) C1: synthesized by the method mentioned in JP 2011-39502 A

(39) ##STR00217##
<Solvent>

(40) TABLE-US-00002 Propylene glycol monomethyl ether acetate 400 parts Propylene glycol monomethyl ether 150 parts γ-Butyrolactone  5 parts
(Evaluation of Exposure of Resist Composition With Electron Beam)

(41) Each 6 inch-diameter silicon wafer was treated with hexamethyldisilazane and then baked on a direct hot plate at 90° C. for 60 seconds. A resist composition was spin-coated on the silicon wafer so that the thickness of the composition layer became 0.04 μm. The coated silicon wafer was prebaked on the direct hot plate at the temperature shown in the column “PB” of Table 1 for 60 seconds to form a composition layer. Using an electron-beam direct-write system [“HL-800D 50 keV”, manufactured by Hitachi, Ltd.], line and space patters were directly written while changing the exposure dose stepwise.

(42) After the exposure, post-exposure baking was performed on the hot plate at the temperature shown in the column “PEB” of Table 1 for 60 seconds, followed by paddle development with an aqueous 2.38% by mass tetramethylammonium hydroxide solution for 60 seconds to obtain a resist pattern.

(43) The thus obtained resist pattern (line and space pattern) was observed by a scanning electron microscope, and effective sensitivity was expressed as the exposure dose at which the line width:space width of the line and space pattern of 60 nm became 1:1 after exposure.

(44) Evaluation of line edge roughness (LER): Trench width of irregularities on the side wall surface of the resist pattern produced at the effective sensitivity was measured by a scanning electron microscope to determine line edge roughness. The results are shown in Table 2.

(45) TABLE-US-00003 TABLE 2 Resist composition LER Example 4 Composition 1 3.68 Example 5 Composition 2 3.70 Example 6 Composition 3 3.52 Example 7 Composition 4 3.62 Comparative Example 1 Comparative Composition 1 3.88

(46) As compared with comparative composition 1, compositions 1 to 4 exhibited satisfactory line edge roughness (LER).

INDUSTRIAL APPLICABILITY

(47) A salt and a resist composition including the salt of the present invention exhibit satisfactory line edge roughness and are therefore useful for fine processing of semiconductors.