KR102295267B1 - Resist composition and patterning process - Google Patents

Abstract

A resist material comprising a base polymer and an onium salt of N-carbonylsulfonamide having an iodinated benzene ring provides high sensitivity, minimum LWR and improved CDU for both positive and negative resist materials .

Description

RESIST COMPOSITION AND PATTERNING PROCESS

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-application is filed under 35 U.S.C. Priority is claimed to Patent Application Nos. 2018-104855 and 2019-028583, filed in Japan on May 31, 2018 and February 20, 2019, respectively, under §119(a), the entire contents of which are incorporated herein by reference cited as

technical field

The present invention relates to a resist material and a method for forming a pattern.

With the expansion of the IoT market, higher integration, higher speed, and lower power consumption of LSIs are more demanded, and the refinement of pattern rules is rapidly progressing. In particular, logic devices are driving miniaturization. As a state-of-the-art miniaturization technology, mass production of 10 nm node microelectronic devices by double patterning, triple patterning, and quadro patterning of immersion ArF lithography is being made. The next generation of research is being conducted on the production of a 7 nm node device by EUV lithography with a wavelength of 13.5 nm.

In EUV lithography, a line width of 20 nm or less can be formed in a line pattern, and a chemically amplified resist material can be applied. However, since the influence of image blur due to acid diffusion becomes larger, EUV lithography requires acid diffusion control than ArF lithography.

A chemically amplified resist material containing an acid generator capable of generating an acid upon irradiation with light or EB is a chemically amplified positive resist material that causes a deprotection reaction with an acid and a chemically amplified negative resist material that causes a crosslinking reaction with an acid type resist material. A quencher is often added to these resist materials for the purpose of improving contrast by controlling the diffusion of acid into the unexposed portion. The addition of quencher was very effective for this purpose. Therefore, as disclosed in Patent Documents 1 to 3, many amine quenchers have been proposed.

As the pattern miniaturization progresses and approaches the diffraction limit of light, the contrast of light decreases. A decrease in light contrast causes a decrease in the resolution and focus margin of a hole pattern or a trench pattern in a positive resist film. In order to prevent the effect of the decrease in the resolution of the resist pattern due to the decrease in the contrast of light, an attempt has been made to improve the dissolution contrast of the resist film.

A chemically amplified resist material using an acid propagation mechanism capable of generating an acid with an acid has been proposed. Usually, the concentration of the acid increases linearly with the increase of the exposure amount. In the case of the acid propagation mechanism, the concentration of the acid rapidly increases nonlinearly with the increase of the exposure dose. The acid propagation system has the advantage of further increasing the advantages such as high contrast and high sensitivity of the chemically amplified resist film. further exacerbate the defect. If you want to put this into practical use, it is a very difficult instrument to control.

Another method for increasing the contrast is a method of lowering the concentration of the amine according to the increase of the exposure amount. For this, application of a compound that loses its function as a quencher by irradiation with light is conceivable.

The acid labile group used in the methacrylate polymer for ArF lithography resist material is removed by using a photoacid generator (referred to as "α-fluorinated sulfonic acid") capable of generating a sulfonic acid substituted with fluorine at the α position. The protection reaction proceeds, but the deprotection reaction does not proceed in a sulfonic acid in which the α-position is not substituted with fluorine (referred to as “α-nonfluorinated sulfonic acid”) or an acid generator capable of generating a carboxylic acid. When a sulfonium salt or iodonium salt capable of generating α-fluorinated sulfonic acid is mixed with a sulfonium salt or iodonium salt capable of generating α non-fluorinated sulfonic acid, a sulfonium salt or iodonium salt capable of generating α non-fluorinated sulfonic acid is mixed. The nium salt causes ion exchange with α-fluorinated sulfonic acid. Since α-fluorinated sulfonic acid generated by light irradiation is returned to a sulfonium salt or iodonium salt by ion exchange, α non-fluorinated sulfonic acid or a sulfonium salt or iodonium salt of a carboxylic acid functions as a quencher.

In addition, sulfonium salts and iodonium salts capable of generating α-nonfluorinated sulfonic acid lose their ability as a quencher due to photolysis, and thus function also as a photodegradable quencher. Non-patent document 1 discloses that the margin of the trench pattern is enlarged by the addition of a photodegradable quencher, although the structural formula is not known. However, the effect on performance improvement is slight. Development of the quencher which improves contrast more is calculated|required.

Patent Document 4 proposes an onium salt type quencher in which basicity decreases by generating carboxylic acid having an amino group upon irradiation with light and generating lactam with the acid. The acid diffusion is controlled by the high basicity in the unexposed portion with a small amount of acid generated by the mechanism in which the basicity is lowered by the acid, and the acid diffusion is controlled by the high basicity in the overexposed portion with a large amount of acid generated by decreasing the basicity of the quencher. this is getting bigger Thereby, the difference in the amount of acid between the exposed part and the unexposed part can be widened, and contrast improvement is expected. However, in this case, although there is an advantage in that the contrast is improved, the acid diffusion control effect is lowered.

Along with the miniaturization of the pattern, the edge roughness (LWR) of the line pattern or the critical dimension uniformity (CDU) of the hole pattern are being questioned. The effect of localization or agglomeration of the base polymer and acid generator on the LWR, and the effect of diffusion of the generated acid are pointed out. The LWR tends to increase with thinning of the resist film. The deterioration of the LWR due to thinning with the progress of miniaturization has become a serious problem.

In EUV lithography resist materials, it is necessary to simultaneously achieve high sensitivity, high resolution, low LWR, and CDU improvement. If the acid diffusion distance is shortened, the LWR becomes small, but the sensitivity is reduced. For example, by lowering the PEB temperature, the LWR becomes small, but the sensitivity is reduced. Although the LWR becomes small even if the addition amount of the quencher is increased, the sensitivity is reduced. There is a need to overcome the trade-off relationship between sensitivity, LWR and CDU. EB is a high energy ray like EUV, and there is a trade-off relationship between sensitivity and LWR or CDU.

The energy of EUV is much higher compared to ArF excimer lasers. The number of photons in EUV exposure is one-fourteenth that of ArF exposure. Moreover, the dimension of a pattern formed by EUV lithography is less than half that of ArF lithography. For this reason, EUV lithography is susceptible to variations in the number of photons. The fluctuation of the number of photons in the emission light region of the extreme wavelength is shot noise of a physical phenomenon, and this influence cannot be eliminated.

Stochastics is attracting attention. Although the effect of shot noise cannot be eliminated, how to reduce this effect is being discussed. A phenomenon in which the CDU and LWR increase due to the influence of shot noise, as well as hole occlusion with a probability of one in a million has been observed. When the hole is blocked, an electric conduction failure occurs and the transistor does not operate, which adversely affects the performance of the entire device. As a method of reducing the effect of shot noise on the resist side, a method of absorbing more photons by increasing the absorption of the resist, but the development of a single-component low molecular weight resist has been proposed because the polymer type resist material causes fluctuations.

As an acid generator for increasing resist absorption, Patent Documents 5 and 6 propose a resist material to which an acid generator of an onium salt having iodine on the anion side is added. This can improve both the sensitivity of the resist material and the LWR or CDU.

Patent Document 1: JP-A 2001-194776 Patent Document 2: JP-A 2002-226470 Patent Document 3: JP-A 2002-363148 Patent Document 4: JP-A 2015-090382 Patent Document 5: JP-A 2018-005224 Patent Document 6: JP-A 2015-025789

Non-Patent Document 1: SPIE Vol. 7639 p76390W (2010) Non-Patent Document 2: SPIE Vol. 9776 p97760V-1 (2016)

In chemically amplified resists using an acid as a catalyst, there is a demand for the development of a quencher or acid generator capable of reducing LWR and CDU with high sensitivity and development of a resist material capable of contributing to shot noise reduction.

An object of the present invention is to provide a resist material with high sensitivity and low LWR or improved CDU for both positive and negative resist materials, and a pattern forming method using the same.

The present inventors have found that by using an onium salt of N-carbonylsulfonamide having an iodinated benzene ring as a quencher or acid generator, high sensitivity, low LWR or improved CDU, high contrast, excellent resolution, and process It has been found that a resist material with a wide margin can be obtained.

In one aspect, the present invention provides a resist material comprising a base polymer and an onium salt having the following formula (A).

wherein R ¹ is hydrogen, hydroxy, C ₁ -C ₆ alkyl group, C ₁ -C ₆ alkoxy group, C ₂ -C ₇ acyloxy group, C ₂ -C ₇ alkoxycarbonyl group, C ₁ -C ₄ alkylsulfo nyloxy group, fluorine, chlorine, bromine, amino, nitro, cyano group, -NR ^1A -C(=O)-R ^1B or -NR ^1A -C(=O)-OR ^1B , wherein the alkyl group, alkoxy group, acyl group Some or all of the hydrogen atoms of the oxy group, the alkoxycarbonyl group and the alkylsulfonyloxy group may be substituted with halogen, R ^1A is hydrogen or a C ₁ -C ₆ alkyl group, R ^1B is a C ₁ -C ₆ alkyl group or C ₂ -C _{8 is an} alkenyl group; R ² is a C ₁ -C ₁₀ alkyl group or a C ₆ -C ₁₀ aryl group, and some or all of the hydrogens are amino, nitro, cyano, C ₁ -C ₁₂ alkyl, C ₁ -C ₁₂ alkoxy, C ₂ - may be substituted with C ₁₂ alkoxycarbonyl, C ₂ -C ₁₂ acyl, C ₂ -C ₁₂ alkylcarbonyloxy, hydroxy or halogen; X ¹ is a single bond or a C ₁ -C ₂₀ divalent linking group, and may contain an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen, a hydroxy group or a carboxy group; m and n are integers satisfying 1≤m≤5, 0≤n≤4, and 1≤m+n≤5.

M ⁺ is a sulfonium cation having the following formula (Aa), an iodonium cation having the following formula (Ab) or an ammonium cation having the following formula (Ac).

In the formula, R ^a1 to ^{R a3} are each independently a halogen or a C ₁ -C ₂₀ monovalent hydrocarbon group which ^{may contain a hetero atom, or any two of R a1} , R ^a2 and R ^a3 are bonded to each other so that they are may form a ring together with the sulfur atom to which it binds; R ^a4 and R ^a5 are each independently a halogen or a C ₁ -C ₂₀ monovalent hydrocarbon group which may contain a hetero atom; R ^a6 to ^{R a9} are each independently hydrogen or a C ₁ -C ₂₄ monovalent hydrocarbon group, halogen, hydroxy, carboxy, ether bond, ester bond, thiol, thioester bond, thionoester bond, dithioester bond , may contain an amino group, nitro group, sulfone group or ferrocenyl group, R ^a6 and R ^a7 may be bonded to each other to form a ring together with the nitrogen atom to which they are bonded, and a pair of ^{R a6} and R ^{a7 and R a8} and R ^a9 may combine with each other to form a spiro ring together with the nitrogen atom to which they are bonded, or R ^a8 and R ^a9 may combine to form =C(R ^a10 )(R ^a11 ), R ^a10 and R ^a11 is each independently hydrogen or a C ₁ -C ₁₆ monovalent hydrocarbon group, and R ^a10 and R ^a11 may be bonded to each other to form a ring together with the carbon and nitrogen atoms to which they are bonded, in the ring a double bond, oxygen It may contain an atom, a sulfur atom, or a nitrogen atom.

Preferably, m is an integer satisfying 2≤m≤4.

The resist material may further contain an acid generator capable of generating sulfonic acid, imide acid or methic acid, and/or an organic solvent.

In one preferred embodiment, the base polymer comprises a repeating unit having the following formula (a1) or a repeating unit having the following formula (a2).

wherein R ^A is each independently hydrogen or methyl, Y ¹ is a single bond, a phenylene group, a naphthylene group, or a C ₁ -C ₁₂ linking group including an ester bond or a lactone ring, and Y ² is a single bond or It is an ester bond, and R ¹¹ and R ¹² are each an acid labile group.

In one embodiment, the resist material is a chemically amplified positive resist material.

The base polymer may not include an acid labile group.

In one preferred embodiment, the resist material may further comprise a crosslinking agent. Typically, the resist material is a chemically amplified negative resist material.

In one preferred embodiment, the base polymer further includes at least one repeating unit selected from repeating units having the following formulas (f1) to (f3).

wherein ^{each R A} is independently hydrogen or methyl; Z ¹ is a single bond, a phenylene group, -OZ ¹¹ -, -C(=O)-OZ ¹¹ - or -C(=O)-NH-Z ¹¹ -, and Z ¹¹ is a C ₁ -C ₆ alkanediyl group , C ₂ -C ₆ alkenediyl group or phenylene group, which may contain a carbonyl, ester bond, ether bond or hydroxyl group; Z ² is a single bond, -Z ²¹ -C(=O)-O-, -Z ²¹ -O-, or -Z ²¹ -OC(=O)-, Z ²¹ is a C ₁ -C ₁₂ alkanediyl group , may contain a carbonyl group, an ester bond or an ether bond; Z ³ is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, -C(=O)-OZ ³¹ - or -C(=O)-NH-Z ³¹ -, and Z ³¹ is C ₁ -C ₆ an alkanediyl group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, or a C ₂ -C ₆ alkenediyl group, which may contain a carbonyl group, an ester bond, an ether bond or a hydroxy group; A is hydrogen or trifluoromethyl; R ²¹ to ^{R 28} _{are each independently a C 1} -C ₂₀ monovalent hydrocarbon group which may contain a hetero atom, ^{and any two of R 23} , R ²⁴ and R ²⁵ or any of R ²⁶ , R ²⁷ and R ²⁸ two may be bonded to each other to form a ring together with the sulfur atom to which they are bonded; M ⁻ is a non-nucleophilic counter ion.

The resist material may further include a surfactant.

In another aspect, the present invention provides the steps of applying a resist material as defined herein on a substrate, subjecting it to heat treatment to form a resist film, exposing the resist film to high energy rays, and developing the exposed resist film in a developer solution. It provides a pattern forming method comprising the step of.

Most often, the high energy ray is an ArF excimer laser with a wavelength of 193 nm, or a KrF excimer laser with a wavelength of 248 nm, EB, or EUV with a wavelength of 3-15 nm.

In a further aspect, the present invention provides a sulfonium salt having the formula (B):

wherein R ¹ , R ² , X ¹ , m, n and R ^a1 to ^{R a3} are as defined above.

The resist film containing the onium salt of N-carbonylsulfonamide having an iodinated benzene ring has large absorption of EB and EUV of the sulfonamide having an iodinated benzene ring, so a large number of secondary electrons are generated in the film to increase the sensitivity. It is possible to improve The anion of the onium salt has a long bonding distance with the onium cation due to steric hindrance in which substituents are attached to both sides of the amide bond. . That is, the ability as a quencher is high, and thus high contrast can be obtained. Moreover, when it has a fluorinated alkyl group or an aryl group before a sulfonamide group, since the intensity|strength of the generated acid is high, it functions as an acid generator. In this case, it functions as an acid generator with controlled acid diffusion.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the <^1> H-NMR spectrum of the sulfonium salt 1 obtained in Synthesis Example 1-1.
^{Fig. 2 is a diagram showing a 19} F-NMR spectrum of sulfonium salt 1 obtained in Synthesis Example 1-1.

As used herein, the singular includes references to the plural unless the context clearly dictates otherwise. The notation (C _n -C _m ) denotes groups comprising from n to m carbon atoms per group. The term "iodinated" compound as used herein refers to an iodine containing compound. In the formula, Me means methyl and Ac means acetyl.

Abbreviations and acronyms have the following meanings.

EB: electron beam

EUV: extreme ultraviolet

Mw: weight average molecular weight

Mn: number average molecular weight

Mw/Mn: molecular weight distribution or dispersion

GPC: Gel Permeation Chromatography

PEB: Post-exposure firing

PAG: photoacid generator

LWR: Line Width Roughness

CDU: Critical Dimension Uniformity

resist ingredient

The resist material of the present invention is defined as comprising a base polymer and an onium salt of N-carbonylsulfonamide having an iodinated benzene ring (hereinafter referred to as a sulfonamide containing a benzene iodinated ring). When the said onium salt is a sulfonium salt or an iodonium salt, these are acid generators which generate|occur|produce a sulfonamide containing a benzene iodide ring by light irradiation, but since they have the form of a strong basic sulfonium salt or an iodonium salt, they also function as a quencher. . The sulfonamide containing a benzene iodide ring functions as an acid generator because a strong acid is generated when bonded to an alkyl group or an aryl group substituted with fluorine. On the other hand, in the absence of a fluorine atom, since there is no acidity to cause a deprotection reaction of the acid labile group, as described later, in order to separately cause a deprotection reaction of the acid labile group, a strong acid such as sulfonic acid, imide acid or It is effective to add an acid generator that generates methic acid. Here, the acid generator for generating sulfonic acid, imide acid or methic acid may be of an additive type added to the base polymer, or may be of a bound type bonded to the base polymer.

When a resist material containing a mixture of the sulfonium salt or iodonium salt of the sulfonamide containing a benzene iodide ring and an acid generator generating a super acid or perfluoroalkyl sulfonic acid is irradiated, the sulfonamide containing a benzene iodide ring and purple Luoroalkylsulfonic acids occur. Since not all of the acid generator is decomposed, an undecomposed acid generator exists in the vicinity. Here, when a sulfonium salt or iodonium salt of a sulfonamide containing a benzene iodide ring and a perfluoroalkylsulfonic acid coexist, the first perfluoroalkylsulfonic acid undergoes ion exchange with a sulfonium salt or an iodonium salt of a sulfonamide containing a benzene iodide ring. As a result, a sulfonium salt or an iodonium salt of perfluoroalkylsulfonic acid is produced, and a sulfonamide containing a benzene ring of iodide is released. This is because the perfluoroalkylsulfonate salt with high strength as an acid is more stable. On the other hand, even if the sulfonium salt or iodonium salt of perfluoroalkylsulfonic acid and the sulfonamide containing a benzene iodide ring coexist, ion exchange does not occur. The same ion exchange takes place not only with perfluoroalkylsulfonic acids, but also with arylsulfonic acids, alkylsulfonic acids, imide acids, methic acids, etc., which have higher acid strength than sulfonamides containing a benzene iodide ring.

The sulfonium salt, iodonium salt or ammonium salt of sulfonamide containing a benzene iodide ring not only suppresses acid diffusion, but also has high EUV absorption, thereby generating secondary electrons, which increases the sensitivity of the resist and reduces shot noise. can The sulfonium salt, iodonium salt, or ammonium salt of a sulfonamide containing a benzene iodide ring has a function not only as an acid generator or quencher for acid diffusion control, but also as a sensitizer.

The resist material of the present invention essentially contains a sulfonium salt, iodonium salt or ammonium salt of a sulfonamide containing a benzene iodide ring, but another sulfonium salt or iodonium salt may be separately added as a quencher. At this time, as the sulfonium salt or iodonium salt to be added as a quencher, sulfonium salts and iodonium salts such as carboxylic acid, sulfonic acid, imide acid, and saccharin are suitable. In this case, the carboxylic acid may not be fluorinated at the α-position.

The resist material of the present invention comprises an acid generator comprising a sulfonium salt or iodonium salt of a fluorosulfonamide bonded to an alkyl or aryl group substituted with fluorine, and a fluorosulfonamide bonded to an alkyl or aryl group having no fluorine atom. It can also be used in combination with the quencher which consists of a sulfonium salt of

For LWR improvement, it is effective to suppress aggregation of the polymer and/or the acid generator as described above. In order to suppress the aggregation of the polymer, it is an effective means to reduce the difference between hydrophobicity and hydrophilicity or to lower the glass transition point (Tg) thereof. Specifically, it is effective to reduce the polarity difference between the hydrophobic acid labile group and the hydrophilic adhesive group or to lower the Tg by using a compact adhesive group such as a monocyclic lactone. In order to suppress the aggregation of the acid generator, it is an effective means to introduce a substituent into the cationic moiety of triphenylsulfonium. In particular, with respect to the methacrylate polymer for ArF lithography formed with the alicyclic protecting group and the adhesive group of the lactone, the triphenylsulfonium formed with the aromatic group has a heterogeneous structure and low compatibility. As a substituent to be introduced into triphenylsulfonium, the same alicyclic group and lactone as those used for the base polymer can be considered. Since the sulfonium salt is hydrophilic, when a lactone is introduced, the hydrophilicity becomes too high, compatibility with the polymer decreases, and aggregation of the sulfonium salt occurs. By introducing a hydrophobic alkyl group, the sulfonium salt can be uniformly dispersed in the resist film. WO 2011/048919 proposes a method for improving LWR by introducing an alkyl group into a sulfonium salt capable of generating α-fluorinated sulfonimidic acid.

A further noteworthy point regarding LWR improvement is the dispersibility of the quencher. Even if the dispersibility of the acid generator in the resist film is improved, if the quencher is non-uniform, it may cause a decrease in LWR. Also in the sulfonium salt type quencher, introducing a substituent such as an alkyl group into the cation moiety of triphenylsulfonium is effective for LWR improvement. Moreover, introducing a halogen atom into the sulfonium salt type quencher effectively increases hydrophobicity and improves dispersibility. Introduction of bulky halogen atoms such as iodine is effective not only in the cation moiety of the sulfonium salt but also in the anion moiety. The sulfonium salt of a sulfonamide containing a benzene iodide ring according to the present invention improves dispersibility of a quencher in a resist film and reduces LWR by introducing an iodine atom into the anion moiety.

The LWR reduction effect by the sulfonium salt, iodonium salt or ammonium salt of the benzene iodide ring-containing sulfonamide is effective in both positive pattern formation and negative pattern formation by alkali development, negative pattern formation by organic solvent development do.

iodide benzene ring containing sulfonamides onium salt

The resist material of the present invention contains an onium salt of a benzene iodide ring-containing sulfonamide having the following formula (A).

In formula (A), R ¹ is a hydrogen atom, a hydroxy group, a C ₁ -C ₆ alkyl group, a C ₁ -C ₆ alkoxy group, a C ₂ -C ₇ acyloxy group, a C ₂ -C ₇ alkoxycarbonyl group, C ₁ -C ₄ alkylsulfonyloxy group, fluorine atom, chlorine atom, bromine atom, amino group, nitro group, cyano group, -NR ^1A -C(=O)-R ^1B or -NR ^1A -C(=O)-OR ^1B . Part or all of the hydrogen atoms of the alkyl group, alkoxy group, acyloxy group, alkoxycarbonyl group and alkylsulfonyloxy group may be substituted with halogen atoms. R ^1A is a hydrogen atom or a C ₁ -C ₆ alkyl group. R ^1B is a C ₁ -C ₆ alkyl group or a C ₂ -C ₈ alkenyl group.

The C ₁ -C ₆ alkyl group may be linear, branched or cyclic, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a cyclopropyl group, an n-butyl group, an isobutyl group, and a sec-butyl group. , tert-butyl group, cyclobutyl group, n-pentyl group, cyclopentyl group, n-hexyl group, cyclohexyl group, and the like. Examples of the alkyl moiety of the C ₁ -C ₆ alkoxy group, the C ₂ -C ₇ acyloxy group, and the C ₂ -C ₇ alkoxycarbonyl group include those similar to those of the alkyl group described above. Examples of the alkyl group of the C ₁ -C ₄ alkylsulfonyloxy group include those having 1 to 4 carbon atoms among the examples of the above-described alkyl group. The C ₂ -C ₈ alkenyl group may be linear, branched or cyclic, and examples thereof include a vinyl group, 1-propenyl group, 2-propenyl group, and the like. A benzyl group, a phenethyl group, etc. are mentioned as said aralkyl group. Among these, R ^{1 is a} fluorine atom, a chlorine atom, a bromine atom, a hydroxy group, an amino group, a C ₁ -C ₃ alkyl group, a C ₁ -C ₃ alkoxy group, a C ₂ -C ₄ acyloxy group, -NR ^1A -C (= O)-R ^1B or -NR ^1A -C(=O)-OR ^1B and the like are preferred.

In formula (A), R ² is a C ₁ -C ₁₀ alkyl group or a C ₆ -C ₁₀ aryl group, and some or all of the hydrogen atoms are an amino group, a nitro group, a cyano group, a C ₁ -C ₁₂ alkyl group, or C ₁ It may be substituted with a -C ₁₂ alkoxy group, a C ₂ -C ₁₂ alkoxycarbonyl group, a C ₂ -C ₁₂ acyl group, a C ₂ -C ₁₂ alkylcarbonyloxy group, a hydroxy group or a halogen atom.

The C ₁ -C ₁₀ alkyl group may be linear, branched or cyclic, and examples thereof include, in addition to the aforementioned C ₁ -C ₆ alkyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, an adamantyl group etc. are mentioned. Examples of the C _{6 -C 10} aryl group include a phenyl group and a naphthyl group.

In formula (A), X ¹ is a single bond or a C ₁ -C ₂₀ divalent linking group, and includes an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxy group or a carboxy group. it's fine to do Among these, a single bond is preferable as ^{X 1 .}

In the formula (A), m and n are integers satisfying 1≤m≤5, 0≤n≤4, and 1≤m+n≤5, preferably m is an integer satisfying 2 to 4, n is 0 or 1.

Although those shown below are mentioned as an anion of the onium salt which has Formula (A), It is not limited to these.

In the formula (A), M ⁺ is a sulfonium cation having the following formula (Aa), an iodonium cation having the following formula (Ab), or an ammonium cation having the following formula (Ac).

When M ⁺ is a sulfonium cation having the formula (Aa), for example, the onium salt having the formula (A) is a sulfonium salt having the following formula (B).

wherein R ¹ , R ² , X ¹ , m, n and R ^a1 to ^{R a3} are as defined above.

In formulas (Aa) and (Ab), R ^a1 to ^{R a3} each independently represent a halogen atom or a C ₁ -C ₂₀ monovalent hydrocarbon group which may contain a hetero atom. Any two of R ^a1 , R ^a2 and R ^a3 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. R ^a4 and R ^a5 are each independently a halogen atom or a C ₁ -C ₂₀ monovalent hydrocarbon group which may contain a hetero atom.

The monovalent hydrocarbon group may be linear, branched or cyclic, and examples thereof include C ₁ -C ₂₀ alkyl group, C ₂ -C ₁₂ alkenyl group, C ₂ -C ₁₂ alkynyl group, C ₆ -C ₂₀ aryl group, C ₇ -C ₁₂ aralkyl group, C ₇ -C ₁₂ aryloxyalkyl group, and the like. In addition, some or all of the hydrogen atoms of these groups may be substituted with a hydroxyl group, a carboxyl group, a halogen atom, an oxo group, a cyano group, an amide bond, a nitro group, a sultone group, a sulfone group or a sulfonium salt-containing group, or A part of carbon atoms may be substituted with an ether bond, an ester bond, a carbonyl group, a carbonate bond, or a sulfonic acid ester bond.

In the formula (Ac), R ^a6 to ^{R a9} each independently represent a hydrogen atom or a C ₁ -C ₂₄ monovalent hydrocarbon group, and a halogen atom, a hydroxyl group, a carboxy group, an ether bond, an ester bond, a thiol group, a thioester bond, or a thi Onoester bond, dithioester bond, amino group, nitro group, sulfone group or ferrocenyl group may be included. R ^a6 and R ^a7 may be bonded to each other to form a ring together with the nitrogen atom to which they are bonded, or ^{a pair of R a6} and R ^{a7 and} a pair of R ^a8 and R ^a9 may be bonded to each other to form a spiro ring together with the nitrogen atom to which they are bonded may be formed, or R ^a8 and R ^a9 may be combined to form =C(R ^a10 )(R ^a11 ), and R ^a10 and R ^a11 are each independently a hydrogen atom or a C ₁ -C ₁₆ monovalent hydrocarbon group. and R ^a10 and R ^a11 may combine with each other to form a ring together with the carbon and nitrogen atoms to which they are bonded, and the ring may contain a double bond, an oxygen atom, a sulfur atom, or a nitrogen atom.

The C ₁ -C ₂₄ monovalent hydrocarbon group may be linear, branched or cyclic, and examples thereof include a C ₁ -C ₂₄ alkyl group, a C ₂ -C ₂₄ alkenyl group, a C ₂ -C ₂₄ alkynyl group, and a C ₆ -C _{20 group.} an aryl group, a C ₇ -C ₂₀ aralkyl group, and combinations thereof.

Although those shown below are mentioned as a sulfonium cation which has a formula (Aa), It is not limited to these.

Although those shown below are mentioned as an iodonium cation which has a formula (Ab), It is not limited to these.

Although those shown below are mentioned as an ammonium cation which has a formula (Ac), It is not limited to these.

As a synthesis method of the onium salt which has Formula (A), the method of performing ion exchange with the onium salt of weak acid rather than the sulfonamide containing a benzene iodide ring is mentioned. Examples of the acid weaker than the benzene iodide ring-containing sulfonamide include hydrochloric acid, carbonic acid, carboxylic acid, and sulfonic acid containing no fluorine atom. Alternatively, an onium salt may be synthesized by ion-exchanging a sodium salt of a sulfonamide containing a benzene iodide ring with an onium chloride.

In the resist material of the present invention, the amount of the onium salt having the formula (A) to be used is preferably 0.001 to 50 parts by weight, more preferably 0.01 to 20 parts by weight, based on 100 parts by weight of the base polymer, in terms of sensitivity and acid diffusion inhibitory effect. desirable.

Base polymer

The base polymer contained in the resist material of the present invention includes, in the case of a positive resist material, a repeating unit containing an acid labile group, and as the repeating unit containing an acid labile group, a repeating unit having the following formula (a1) or ( A repeating unit having a2) is preferred. These units are simply referred to as repeating units (a1) and (a2).

In the formula, ^{each R A} is independently a hydrogen atom or a methyl group. Y ¹ is a single bond, a phenylene group or a naphthylene group, or a C ₁ -C ₁₂ linking group including an ester bond or a lactone ring. Y ² is a single bond or an ester bond. R ¹¹ and R ¹² are each an acid labile group. When the base polymer includes both repeating units (a1) and (a2), R ¹¹ and R ¹² may be the same or different.

Although those shown below are mentioned as a monomer which provides a repeating unit (a1), It is not limited to these. R ^A and R ¹¹ are as defined above.

Although those shown below are mentioned as a monomer which provides a repeating unit (a2), It is not limited to these. R ^A and R ¹² are as defined above.

^{The acid labile groups represented by R 11} and R ¹² in the repeating units (a1) and (a2) are various of these groups, such as those described in JP-A 2013-080033 (USP 8,574,817) and JP-A 2013-083821 (USP 8,846,303). is chosen from

Typically, the acid labile group includes groups having the following formulas (AL-1) to (AL-3).

In formulas (AL-1) and (AL-2), R ^L1 and R ^L2 are each independently a C ₁ -C ₄₀ monovalent hydrocarbon group, and a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom; may be included. The monovalent hydrocarbon group may be linear, branched or cyclic, preferably a _{C 1} -C ₄₀ alkyl group, more preferably a _{C 1} -C _{20 alkyl group.} In formula (AL-1), a is an integer of 0-10, and the integer of 1-5 is preferable.

In the formula (AL-2), R ^L3 and R ^L4 are each independently a hydrogen atom or a C ₁ -C ₂₀ monovalent hydrocarbon group, even if they contain a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom good. The monovalent hydrocarbon group may be linear, branched or cyclic, and a C ₁ -C ₂₀ alkyl group is preferable. any two of R ^L2 , R ^L3 and R ^L4 combine with each other to form a ring having 3 to 20 carbon atoms, preferably a ring having 4 to 16 carbon atoms, typically an alicyclic ring together with the carbon atom or carbon atom and oxygen atom to which they are attached do.

In formula (AL-3), R ^L5 , R ^L6 and R ^L7 are each independently a C ₁ -C ₂₀ monovalent hydrocarbon group, even if they contain a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom good. The monovalent hydrocarbon group may be linear, branched or cyclic, and a C ₁ -C ₂₀ alkyl group is preferable. Any two of R ^L5 , R ^L6 and R ^L7 are bonded to each other to form, together with the carbon atom to which they are attached, a ring having 3 to 20 carbon atoms, preferably a ring having 4 to 16 carbon atoms, typically an alicyclic ring.

The said base polymer may further contain the repeating unit (b) containing a phenolic hydroxyl group as an adhesive group. Although those shown below are mentioned as a monomer which provides a repeating unit (b), It is not limited to these. wherein R ^A is as defined above.

The base polymer may further contain, as another adhesive group, a repeating unit (c) selected from a hydroxyl group (other than the phenolic hydroxyl group), a carbonyl group, a lactone ring, an ether bond, an ester bond, a carbonyl group and a cyano group. Suitable monomers for imparting the repeating unit (c) include, but are not limited to, those shown below. wherein R ^A is as defined above.

In another preferred embodiment, the base polymer further comprises a repeating unit (d) selected from units of indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene or derivatives thereof. may do Suitable monomers are exemplified below.

In addition to the repeating units described above, the base polymer may further include a repeating unit (e), examples of which include styrene, vinylnaphthalene, vinylanthracene, vinylpyrene, methyleneindane, vinylpyridine and vinylcarbazole.

In a further embodiment, the base polymer may further include a repeating unit (f) derived from an onium salt containing a polymerizable unsaturated bond. JP-A 2005-084365 proposes a sulfonium salt and an iodonium salt containing a polymerizable unsaturated bond in which a specific sulfonic acid is generated. JP-A 2006-178317 proposes a sulfonium salt in which sulfonic acid is directly linked to the main chain.

In a preferred embodiment, the base polymer may further include at least one repeating unit selected from the following formulas (f1), (f2) and (f3). These units are simply referred to as repeating units (f1), (f2) and (f3), and these may be used alone or in combination of two or more.

In formulas (f1) to (f3), R ^A is as defined above. Z ¹ is a single bond, a phenylene group, -OZ ¹¹ -, -C(=O)-OZ ¹¹ - or -C(=O)-NH-Z ¹¹ -, and Z ¹¹ is a C ₁ -C ₆ alkanediyl group , C ₂ -C ₆ alkenediyl group or phenylene group, and may contain a carbonyl group, ester bond, ether bond or hydroxyl group. Z ² is a single bond, -Z ²¹ -C(=O)-O-, -Z ²¹ -O-, or -Z ²¹ -OC(=O)-, Z ²¹ is a C ₁ -C ₁₂ alkanediyl group , a carbonyl group, an ester bond, or an ether bond may be included. Z ³ is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, -C(=O)-OZ ³¹ - or -C(=O)-NH-Z ³¹ -, and Z ³¹ is C ₁ - It is a C ₆ alkanediyl group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, or a C ₂ -C ₆ alkenediyl group, and may contain a carbonyl group, an ester bond, an ether bond or a hydroxyl group. A is a hydrogen atom or a trifluoromethyl group.

In formulas (f1) to (f3), R ²¹ to ^{R 28} each independently represent a C ₁ -C ₂₀ monovalent hydrocarbon group which may contain a hetero atom. Any two of R ²³ , R ²⁴ and R ²⁵ or any two of R ²⁶ , R ²⁷ and R ²⁸ may be bonded to each other to form a ring together with the sulfur atom to which they are bonded.

The monovalent hydrocarbon group may be linear, branched or cyclic, and examples thereof include those described above for ^{R a1 to R a3 in the formula (Aa).} Examples of the sulfonium cation in the formulas (f2) and (f3) include those described above as the sulfonium cation having the formula (Aa).

In formula (f1), M ⁻ is a non-nucleophilic counter ion. Examples of the non-nucleophilic counter ion include halide ions such as chloride ions and bromide ions, triflate ions, 1,1,1-trifluoroethanesulfonate ions, and fluoroalkylsulfonates such as nonafluorobutanesulfonate ions. arylsulfonate ions such as ions, tosylate ions, benzenesulfonate ions, 4-fluorobenzenesulfonate ions, and 1,2,3,4,5-pentafluorobenzenesulfonate ions; Alkylsulfonate ion such as mesylate ion and butanesulfonate ion, bis(trifluoromethylsulfonyl)imide ion, bis(perfluoroethylsulfonyl)imide ion, bis(perfluorobutylsulfonyl) imide ions such as imide ions; and methide ions such as tris(trifluoromethylsulfonyl)methide ion and tris(perfluoroethylsulfonyl)methide ion.

Examples of the non-nucleophilic counter ion include a sulfonate ion having the following formula (K-1) in which the α-position is substituted with a fluorine atom, and a sulfonic acid ion having the following formula (K-2) in which the α and β-positions are substituted with a fluorine atom. can

In formula (K-1), R ⁵¹ is a hydrogen atom, or a C ₁ -C ₂₀ alkyl group, a C ₂ -C ₂₀ alkenyl group, or a C ₆ -C ₂₀ aryl group, and is an ether bond, an ester bond, a carbonyl group, or a lactone ring. Or it may contain a fluorine atom. The alkyl group and the alkenyl group may be linear, branched or cyclic.

In formula (K-2), R ⁵² is a hydrogen atom, or a C ₁ -C ₃₀ alkyl group, C ₂ -C ₃₀ acyl group, C ₂ -C ₂₀ alkenyl group, C ₆ -C ₂₀ aryl group, or C ₆ - It is a C ₂₀ aryloxy group and may contain an ether bond, an ester bond, a carbonyl group, or a lactone ring. The alkyl group and the alkenyl group may be linear, branched or cyclic.

Although those shown below are mentioned as a monomer which provides a repeating unit (f1), It is not limited to these. R ^A and M ^- are as defined above.

Although those shown below are mentioned as a monomer which provides a repeating unit (f2), It is not limited to these. R ^A is as defined above.

Although those shown below are mentioned as a monomer which provides a repeating unit (f3), It is not limited to these. R ^A is as defined above.

By binding an acid generator to the polymer main chain, it is effective in reducing acid diffusion and preventing a decrease in resolution due to slowing of acid diffusion. In addition, since the acid generator is uniformly dispersed, edge roughness is improved. When the base polymer including the repeating unit (f) is used, the compounding of the individual acid generator can be omitted.

The base polymer for constituting a positive resist material contains, as an essential component, a repeating unit (a1) or (a2) having an acid labile group, and further repeating units (b), (c), (d), (e) and (f) is included as an optional component. The content ratio of the repeating units (a1), (a2), (b), (c), (d), (e) and (f) is 0≤a1<1.0, 0≤a2<1.0, 0<a1+a2 <1.0, 0≤b≤0.9, 0≤c≤0.9, 0≤d≤0.8, 0≤e≤0.8 and 0≤f≤0.5 are preferred, 0≤a1≤0.9, 0≤a2≤0.9, 0.1≤ a1+a2≤0.9, 0≤b≤0.8, 0≤c≤0.8, 0≤d≤0.7, 0≤e≤0.7 and 0≤f≤0.4 are more preferable, 0≤a1≤0.8, 0≤a2≤ 0.8, 0.1 ≤ a1+a2 ≤ 0.8, 0 ≤ b ≤ 0.75, 0 ≤ c ≤ 0.75, 0 ≤ d ≤ 0.6, 0 ≤ e ≤ 0.6, and 0 ≤ f ≤ 0.3 are more preferable. Further, when the repeating unit (f) is at least one of the repeating units (f1) to (f3), f=f1+f2+f3, and a1+a2+b+c+d+e+f=1.0.

The base polymer for constituting the negative resist material does not necessarily require an acid labile group. Such a base polymer contains a repeating unit (b) and optionally contains repeating units (c), (d), (e) and/or (f). The content ratio of these repeating units is preferably 0<b≤1.0, 0≤c≤0.9, 0≤d≤0.8, 0≤e≤0.8 and 0≤f≤0.5, 0.2≤b≤1.0, 0≤c ≤0.8, 0≤d≤0.7, 0≤e≤0.7 and 0≤f≤0.4 are more preferable, 0.3≤b≤1.0, 0≤c≤0.75, 0≤d≤0.6, 0≤e≤0.6 and 0 ?f?0.3 is more preferable. Further, when the repeating unit (f) is at least one of the repeating units (f1) to (f3), f=f1+f2+f3 and b+c+d+e+f=1.0.

The base polymer can be synthesized by any predetermined method, for example, by heating polymerization by adding a radical polymerization initiator in an organic solvent to one or more monomers selected from the above-mentioned monomers imparting repeating units. . Toluene, benzene, tetrahydrofuran, diethyl ether, dioxane etc. are mentioned as an organic solvent used at the time of superposition|polymerization. Examples of the polymerization initiator used in the present invention include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis ( 2-methylpropionate), benzoyl peroxide, lauroyl peroxide, and the like. To initiate polymerization, the system is preferably heated to 50-80°C. The reaction time is 2 to 100 hours, preferably 5 to 20 hours.

When copolymerizing a monomer having a hydroxyl group, the hydroxyl group may be substituted with an acetal group that is easy to deprotect with an acid such as an ethoxyethoxy group before polymerization, and deprotection may be performed with a weak acid and water after polymerization. Alternatively, the hydroxy group may be substituted with an acetyl group, formyl group, pivaloyl group or the like before polymerization, and alkali hydrolysis may be performed after polymerization.

In the case of copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, an alternative method is possible. Specifically, acetoxystyrene or acetoxyvinylnaphthalene is used instead of hydroxystyrene or hydroxyvinylnaphthalene, and after polymerization, the acetoxy group is deprotected by the alkali hydrolysis to convert the polymer product to hydroxystyrene or hydroxy It may be converted to vinyl naphthalene. As a base in the case of alkaline hydrolysis, aqueous ammonia, triethylamine, etc. can be used. The reaction temperature is preferably -20 to 100°C, more preferably 0 to 60°C, and the reaction time is preferably 0.2 to 100 hours, more preferably 0.5 to 20 hours.

The said base polymer has a polystyrene conversion weight average molecular weight (Mw) by GPC using tetrahydrofuran (THF) as a solvent, Preferably it is 1,000-500,000, More preferably, it is 2,000-30,000. When Mw is too small, a resist material will become inferior in heat resistance. When the Mw of the polymer is too large, the alkali solubility decreases, and the footing phenomenon tends to occur after pattern formation.

When the molecular weight distribution or dispersion (Mw/Mn) of the base polymer is wide, there is a risk that a foreign material may be seen on the pattern or the shape of the pattern may deteriorate because a polymer fraction having a low molecular weight or a high molecular weight exists. . As the pattern rule is refined, the influence of molecular weight and dispersion tends to increase. Therefore, in order to obtain a resist material suitable for a fine pattern dimension, it is preferable that the dispersion (Mw/Mn) of the base polymer be 1.0 to 2.0, particularly 1.0 to 1.5, and narrow dispersion.

The base polymer may contain two or more polymers having different composition ratios, Mw, and Mw/Mn. In the range which does not impair the effect of this invention, although the said base polymer may contain the polymer different from the above-mentioned polymer, it is preferable not to contain it.

acid generator

The resist material of the present invention may further contain an acid generator (additive acid generator) in order to function as a chemically amplified positive resist material or a chemically amplified negative resist material. As a result, a resist material with higher sensitivity is obtained, and various properties are further improved, which is very useful. When the base polymer contains the repeating unit (f), that is, when the acid generator is contained in the base polymer, the addition type acid generator may not be included.

Acid generators are typically compounds (PAGs) that generate acids in response to actinic light or radiation. The PAG may be any compound as long as it generates an acid upon irradiation with a high energy ray, but one that generates sulfonic acid, imidic acid or methic acid is preferable. Suitable PAGs include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, oxime-O-sulfonate type acid generators and the like. Examples of the PAG include those described in paragraphs [0122] to [0142] of JP-A 2008-111103 (USP 7,537,880).

Moreover, it is preferable to have following formula (1) as PAG.

In formula (1), R ¹⁰¹ , R ¹⁰² and R ¹⁰³ are each independently a C ₁ -C ₂₀ monovalent hydrocarbon group which may contain a hetero atom. Any two of R ¹⁰¹ , R ¹⁰² and R ¹⁰³ may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. The monovalent hydrocarbon group may be linear, branched or cyclic, and examples thereof include those described above for ^{R a1 to R a3 in the formula (Aa).}

Examples of the cation of the sulfonium salt having the formula (1) include those described above as the sulfonium cation having the formula (Aa).

In formula (1), X ⁻ is an anion having the following formula (1A), (1B), (1C) or (1D).

In formula (1A), R ^fa _{is a C 1} -C ₄₀ monovalent hydrocarbon group which may contain a fluorine atom or a hetero atom. The monovalent hydrocarbon group may be linear, branched or cyclic, and examples thereof include the same as those described in the description of ^{R 105 to be described later.}

Among the anions of formula (1A), those having the following formula (1A') are preferable.

In formula (1A'), R ¹⁰⁴ is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. R ¹⁰⁵ _{is a C 1} -C ₃₈ monovalent hydrocarbon group which may contain a hetero atom. As said hetero atom, an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, etc. are preferable, and an oxygen atom is the most preferable. The ^{monovalent hydrocarbon group represented by R 105} is particularly preferably having 6 to 30 carbon atoms from the viewpoint of obtaining high resolution in fine pattern formation. The monovalent hydrocarbon group may be linear, branched or cyclic. Examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, a no linear or branched alkyl groups such as nyl group, undecyl group, tridecyl group, pentadecyl group, heptadecyl group and icosanyl group; Cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-adamantyl group, 1-adamantylmethyl group, norbornyl group, norbornylmethyl group, tricyclodecanyl group, tetracyclododecanyl group, tetracyclodo monovalent saturated cyclic aliphatic hydrocarbon groups such as decanylmethyl group and dicyclohexylmethyl group; monovalent unsaturated aliphatic hydrocarbon groups such as allyl group and 3-cyclohexenyl group; Aralkyl groups, such as a benzyl group and a diphenylmethyl group, etc. are mentioned. As a monovalent hydrocarbon group containing a hetero atom, tetrahydrofuryl group, methoxymethyl group, ethoxymethyl group, methylthiomethyl group, acetamidomethyl group, trifluoroethyl group, (2-methoxyethoxy)methyl group, acetoxy group A methyl group, 2-carboxy-1-cyclohexyl group, 2-oxopropyl group, 4-oxo-1-adamantyl group, 3-oxocyclohexyl group, etc. are mentioned. A part of the hydrogen atoms of these groups may be substituted with a hetero atom-containing group such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, or a part of the carbon atoms of these groups may be substituted with a hetero atom-containing group such as an oxygen atom, a sulfur atom, or a nitrogen atom It may be substituted with an atom-containing group, and as a result, it may contain a hydroxyl group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc. .

For the synthesis of a sulfonium salt comprising an anion having the formula (1A'), reference may be made to JP-A 2007-145797, JP-A 2008-106045, JP-A 2009-007327, JP-A 2009-258695 and the like. can Also useful are sulfonium salts described in JP-A 2010-215608, JP-A 2012-041320, JP-A 2012-106986, JP-A 2012-153644 and the like.

Although those shown below are mentioned as an anion which has Formula (1A), It is not limited to these.

In formula (1B), R ^fb1 and R ^fb2 are each independently a fluorine atom or a C ₁ -C ₄₀ monovalent hydrocarbon group which may contain a hetero atom. The monovalent hydrocarbon group may be linear, branched, or cyclic, and examples thereof include those exemplified in the description of ^{R 105 above.} R ^fb1 and R ^fb2 are preferably a fluorine atom or a C ₁ -C ₄ linear fluorinated alkyl group. Further, R ^fb1 and R ^fb2 may be mutually bonded to form a ring together with the group to which they are bonded: -CF ₂ -SO ₂ -N ^- -SO ₂ -CF _{2 -.} In this case, it is preferable that the group obtained by mutual bonding of ^{R fb1} and R ^{fb2 is a fluorinated ethylene group or a fluorinated propylene group.}

In formula (1C), R ^fc1 , R ^fc2 and R ^fc3 are each independently a fluorine atom or a C ₁ -C ₄₀ monovalent hydrocarbon group which may contain a hetero atom. The monovalent hydrocarbon group may be linear, branched, or cyclic, and examples thereof include those exemplified in the description of ^{R 105 above.} R ^fc1 , R ^fc2 and R ^fc3 are preferably a fluorine atom or a C ₁ -C ₄ linear fluorinated alkyl group. Further, R ^fc1 and R ^fc2 may be mutually bonded to form a ring together with the group to which they are bonded: -CF ₂ -SO ₂ -C ^- -SO ₂ -CF _{2 -.} In this case, it is preferable that the group obtained by mutual bonding of ^{R fc1} and R ^{fc2 is a fluorinated ethylene group or a fluorinated propylene group.}

In formula (1D), R ^fd _{is a C 1} -C ₄₀ monovalent hydrocarbon group which may contain a hetero atom. The monovalent hydrocarbon group may be linear, branched, or cyclic, and examples thereof include those exemplified in the description of ^{R 105 above.}

Regarding the synthesis of a sulfonium salt comprising an anion having the formula (1D), reference may be made to JP-A 2010-215608 and JP-A 2014-133723.

Although those shown below are mentioned as an anion which has Formula (1D), It is not limited to these.

Further, the compound containing an anion having the formula (1D) does not have a fluorine at the α-position of the sulfo group, but has two trifluoromethyl groups at the β-position. Due to this, it has sufficient acidity to cleave acid labile groups in the resist polymer. As such, the compound is a useful PAG.

As another preferable PAG, the compound which has a following formula (2) is mentioned.

In formula (2), R ²⁰¹ and R ²⁰² are each independently a C ₁ -C ₃₀ monovalent hydrocarbon group which may contain a hetero atom. R ²⁰³ _{is a C 1} -C ₃₀ divalent hydrocarbon group which may contain a hetero atom. Any two of R ²⁰¹ , R ²⁰² and R ²⁰³ may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. L ^A is a single bond, an ether bond, or a C ₁ -C ₂₀ divalent hydrocarbon group which may contain a hetero atom. X ^A , X ^B , X ^C and X ^D are each independently a hydrogen atom, a fluorine atom or a trifluoromethyl group, provided ^{that at least one of X A} , X ^B , X ^C and X ^D is a fluorine atom or trifluoro It is a methyl group, and k is an integer of 0-3.

The monovalent hydrocarbon group may be linear, branched or cyclic. Examples thereof include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, tert-pentyl group, n-hexyl group, n-octyl group, n- linear or branched alkyl groups such as nonyl group, n-decyl group, and 2-ethylhexyl group; Cyclopentyl group, cyclohexyl group, cyclopentylmethyl group, cyclopentylethyl group, cyclopentylbutyl group, cyclohexylmethyl group, cyclohexylethyl group, cyclohexylbutyl group, norbornyl group, oxanorbornyl group, tricyclo[5.2.1.0 ^{2 ,6} ] a monovalent saturated cyclic hydrocarbon group such as a decanyl group and an adamantyl group; Although aryl groups, such as a phenyl group, a naphthyl group, and anthracenyl group, etc. are mentioned, it is not limited to these. A part of the hydrogen atoms of these groups may be substituted with a hetero atom-containing group such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and a part of the carbon atoms of these groups is a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom It may be substituted with a containing group, and as a result, it may contain a hydroxyl group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, and the like.

The divalent hydrocarbon group may be linear, branched or cyclic. Examples thereof include methylene group, ethylene group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7- Diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group, Tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, heptadecane-1,17-diyl group, etc. a linear or branched alkanediyl group; divalent saturated cyclic hydrocarbon groups such as cyclopentanediyl group, cyclohexanediyl group, norbornanediyl group and adamantanediyl group; Unsaturated cyclic divalent hydrocarbon groups, such as a phenylene group and a naphthylene group, etc. are mentioned. A part of the hydrogen atoms in these groups may be substituted with an alkyl group such as a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group, and a part of the hydrogen atoms in these groups is an oxygen atom, a sulfur atom, a nitrogen atom, It may be substituted with a hetero atom-containing group such as a halogen atom, or some of the carbon atoms of these groups may be substituted with a hetero atom-containing group such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, a hydroxy group, a cyano group, or a carbonyl group , may contain an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, or the like. As said hetero atom, an oxygen atom is preferable.

As PAG which has Formula (2), it is preferable to have following Formula (2').

In formula (2'), L ^A is as defined above. R is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. R ³⁰¹ , R ³⁰² and R ³⁰³ are each independently a hydrogen atom or a C ₁ -C ₂₀ monovalent hydrocarbon group which may contain a hetero atom. The monovalent hydrocarbon group may be linear, branched, or cyclic, and examples thereof include those exemplified in the description of ^{R 105 above.} The subscripts x and y are each independently an integer from 0 to 5, and z is an integer from 0 to 4.

Although those shown below are mentioned as PAG which has Formula (2), It is not limited to these. Meanwhile, R is as defined above.

Among the above-mentioned PAGs, those containing an anion having the formula (1A') or (1D) are particularly preferable because of their low acid diffusion and excellent solubility in resist solvents. In addition, those containing an anion having the formula (2') are particularly preferable because acid diffusion is very small.

Moreover, as said PAG, the sulfonium salt or iodonium salt which has an anion containing an iodine atom can also be used. Examples of such salts include sulfonium salts and iodonium salts of benzoyloxy iodide group-containing fluorinated sulfonic acid having the following formula (3-1) or (3-2).

In formulas (3-1) and (3-2), R ⁴⁰¹ is a hydrogen atom, a hydroxyl group, a carboxy group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an amino group, or a fluorine atom, a chlorine atom, or a bromine atom _{, C 1} -C ₂₀ alkyl group, C ₁ -C ₂₀ alkoxy group, C ₂ -C ₂₀ alkoxycarbonyl group, C ₂ -C ₂₀ acyloxy group or C ₁ -C ₄ alkyl which may contain hydroxy group, amino group or alkoxy group a sulfonyloxy group, or -NR ⁴⁰⁷ -C(=O)-R ⁴⁰⁸ or -NR ⁴⁰⁷ -C(=O)-OR ⁴⁰⁸ , and R ⁴⁰⁷ is a hydrogen atom, or a halogen atom, a hydroxy group, an alkoxy group, an acyl group, or _{a C 1} -C ₆ alkyl group which may contain an acyloxy group, R ⁴⁰⁸ is a C ₁ -C ₁₆ alkyl group, a C ₂ -C ₁₆ alkenyl group, or a C ₆ -C ₁₂ aryl group, and a halogen atom, a hydroxyl group, an alkoxy group , an acyl group or an acyloxy group may be included.

X ¹¹ is, or r = 1 one bond or a divalent connecting group when C ₁ -C ₂₀ 2, r = 2 or 3, when a C ₁ -C ₂₀ 3 or a tetravalent linking group, the linking group is an oxygen atom, a sulfur atom, Or a nitrogen atom may be included. Rf ^{11 to Rf 14} each independently represent a hydrogen atom, a fluorine atom, or a trifluoromethyl group. At least one of Rf ^{11 to Rf 14} may be a fluorine atom or a trifluoromethyl group, or Rf ¹¹ and Rf ¹² may be combined to form a carbonyl group.

R ⁴⁰² , R ⁴⁰³ , R ⁴⁰⁴ , R ⁴⁰⁵ and R ⁴⁰⁶ are each independently a C ₁ -C ₂₀ monovalent hydrocarbon group which may contain a heteroatom. Any two of R ⁴⁰² , R ⁴⁰³ and R ⁴⁰⁴ may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. The monovalent hydrocarbon group may be linear, branched or cyclic, and examples thereof include those described above for ^{R a1 to R a3 in the formula (Aa).}

In formulas (3-1) and (3-2), r is an integer of 1-3, s is an integer of 1-5, and t is an integer of 0-3.

The alkyl group, alkoxy group, alkoxycarbonyl group, acyloxy group, alkylsulfonyloxy group, alkenyl group and acyl group may be linear, branched or cyclic.

Examples of the sulfonium salt or iodonium salt having an anion containing an iodine atom include a sulfonium salt or an iodonium salt of a benzene iodide ring-containing fluorinated sulfonic acid having the following formula (3-3) or (3-4).

In formulas (3-3) and (3-4), R ⁴¹¹ is a hydroxyl group, a C ₁ -C ₂₀ alkyl group or an alkoxy group, a C ₂ -C ₂₀ acyl group or an acyloxy group, a fluorine atom, a chlorine atom, a bromine atom, an amino group, or an alkoxycarbonyl-substituted amino group.

R ⁴¹² is each independently a single bond or a C ₁ -C ₄ alkylene group. R ⁴¹³ is, u = 1 and it indicates a single bond or C ₁ -C ₂₀ 2-valent linking group, when the u = 2 or 3 C ₁ -C ₂₀ is a trivalent or tetravalent linking group. This coupling group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

Rf ^{21 to Rf 24} are each independently a hydrogen atom, a fluorine atom or a trifluoromethyl group, and ^{at least one of Rf 21 to Rf 24} is a fluorine atom or a trifluoromethyl group. Rf ²¹ and Rf ²² may combine to form a carbonyl group.

R ⁴¹⁴ , R ⁴¹⁵ , R ⁴¹⁶ , R ⁴¹⁷ and R ⁴¹⁸ are each independently a C ₁ -C ₂₀ monovalent hydrocarbon group which may contain a hetero atom. Any two of R ⁴¹⁴ , R ⁴¹⁵ and R ⁴¹⁶ may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. The monovalent hydrocarbon group may be linear, branched or cyclic, and examples thereof include those described above for ^{R a1 to R a3 in the formula (Aa).}

The subscript u is an integer from 1 to 3, v is an integer from 1 to 5, and w is an integer from 0 to 3.

The alkyl group, alkoxy group, acyl group, acyloxy group and alkenyl group may be linear, branched or cyclic.

Examples of the cation of the sulfonium salt having the formulas (3-1) and (3-3) include those described above as the sulfonium cation having the formula (Aa). Examples of the cation of the iodonium salt having the formula (3-2) or (3-4) include those described above as the iodonium cation having the formula (Ab).

Although those shown below are mentioned as an anion part of the onium salt which has Formula (3-1) - (3-4), It is not limited to these.

Further, as the PAG, a sulfonium salt or an iodonium salt having an anion containing a bromine atom may be used. Examples of the anion containing a bromine atom include those in which an iodine atom is substituted with a bromine atom in the formulas (3-1) to (3-4). Examples of this include those in which an iodine atom is substituted with a bromine atom in the above-described anion containing an iodine atom.

When used, the content of the additive type acid generator is preferably 0.1 to 50 parts by weight, more preferably 1 to 40 parts by weight, based on 100 parts by weight of the base polymer.

other ingredients

In addition to the above-described onium salt, base polymer, and acid generator, other components such as organic solvents, surfactants, dissolution inhibitors and crosslinking agents are appropriately combined and blended according to the purpose to form a chemically amplified positive resist material or negative resist material. materials can be constructed. In the exposed portion, since the dissolution rate of the base polymer in the developer is accelerated by the catalytic reaction, a very highly sensitive positive resist material or negative resist material can be obtained. In addition, the resist film has high dissolution contrast and resolution, has an exposure margin, is excellent in process adaptability, has a good pattern shape after exposure, can suppress acid diffusion, and has a small difference in density. From this point of view, the material is highly practical and can be made very effective as a pattern forming material for VLSI production.

As the organic solvent, those described in paragraphs [0144] to [0145] of JP-A 2008-111103 (USP 7,537,880) are used. Examples of the solvent include ketones such as cyclohexanone, cyclopentanone, and methyl-2-n-pentyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol and diacetone alcohol; ethers such as propylene glycol monomethyl ether (PGME), ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; Propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, 3-methoxymethyl propionate, 3-ethoxypropionate ethyl, t-butyl acetate, t-butyl propionate, esters such as propylene glycol monot-butyl ether acetate; Lactones, such as (gamma)-butyrolactone, are mentioned, These solvents may be used individually or in mixture.

The content of the organic solvent is preferably 100 to 10,000 parts by weight, more preferably 200 to 8,000 parts by weight, based on 100 parts by weight of the base polymer.

Examples of the surfactant include those described in paragraphs [0165] to [0166] of JP-A 2008-111103. By adding a surfactant, it is possible to improve or control the applicability of the resist material. The surfactant may be used alone or in combination, and the content of the surfactant is preferably 0.0001 to 10 parts by weight based on 100 parts by weight of the base polymer.

In the case of a positive resist material, by mix|blending a dissolution inhibitor, the difference in the dissolution rate of an exposed part and an unexposed part can be enlarged further, and the resolution can be improved further. In the case of a negative resist material, by adding a crosslinking agent, the rate of dissolution of the resist film in the exposed portion can be reduced to form a negative pattern.

Examples of the dissolution inhibitor include a compound in which hydrogen atoms in the phenolic hydroxyl groups of a compound having two or more phenolic hydroxyl groups in a molecule are substituted with an acid labile group in an average ratio of 0 to 100 mol%, or at least one in a molecule A compound in which the hydrogen atom of the carboxyl group of the compound having a carboxyl group is substituted with an acid labile group in an average ratio of 50 to 100 mol% may be used, and the two compounds have a molecular weight of 100 to 1,000, preferably 150 to 800. Typically, bisphenol A, trisphenol, phenolphthalein, cresol novolac, naphthalene carboxylic acid, adamantane carboxylic acid, and cholic acids include derivatives in which a hydroxyl group or a carboxyl group is substituted with an acid labile group. USP 7,771,914 (paragraphs [0155] to [0178] of JP-A 2008-122932).

In the case of a positive resist material, the content of the dissolution inhibitor is preferably 0 to 50 parts by weight, more preferably 5 to 40 parts by weight, based on 100 parts by weight of the base polymer. The dissolution inhibitor may be used alone or in combination.

Examples of the crosslinking agent include an epoxy compound, a melamine compound, a guanamine compound, a glycoluril compound and a urea compound, an isocyanate compound, an azide compound, and an alkenyl ether substituted with at least one group selected from a methylol group, an alkoxymethyl group and an acyloxymethyl group. A compound having a double bond, such as a group, etc. can be used suitably. These materials may be used as additives, or may be introduced as pendant groups in the polymer side chain. A compound containing a hydroxyl group can also be used as a crosslinking agent. A crosslinking agent may be used individually or in mixture.

As the epoxy compound among the crosslinking agents, tris(2,3-epoxypropyl)isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, triethylolethane triglycidyl ether, and the like are suitable. Examples of the melamine compound include hexamethylolmelamine, hexamethoxymethylmelamine, a compound obtained by methoxymethylation of 1 to 6 methylol groups of hexamethylolmelamine, and a mixture thereof, hexamethoxyethylmelamine, hexaacyloxymethylmelamine, and hexamethylolmelamine. A compound in which 1 to 6 of the methylol groups of methylolmelamine are acyloxymethylated, and a mixture thereof, etc. are mentioned. Examples of the guanamine compound include tetramethylolguanamine, tetramethoxymethylguanamine, a compound obtained by methoxymethylation of 1 to 4 methylol groups of tetramethylolguanamine, and a mixture thereof, tetramethoxyethylguanamine, tetraacyloxy guanamine, a compound obtained by acyloxymethylation of 1 to 4 methylol groups of tetramethylol guanamine, a mixture thereof, and the like. Examples of the glycoluril compound include tetramethylol glycoluril, tetramethoxy glycoluril, tetramethoxymethyl glycoluril, a compound in which 1 to 4 of the methylol groups of tetramethylol glycoluril are methoxymethylated, and a mixture thereof, tetramethylol glycol and compounds in which 1 to 4 of the methylol groups of uril are acyloxymethylated, and mixtures thereof. Examples of the urea compound include tetramethylolurea, tetramethoxymethylurea, a compound obtained by methoxymethylation of 1 to 4 methylol groups of tetramethylolurea, a mixture thereof, and tetramethoxyethylurea.

As an isocyanate compound, tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, etc. are suitable. As the azide compound, 1,1'-biphenyl-4,4'-bisazide, 4,4'-methylidenebisazide, 4,4'-oxybisazide and the like are suitable. Examples of the compound containing an alkenyl ether group include ethylene glycol divinyl ether, triethylene glycol divinyl ether, 1,2-propanediol divinyl ether, 1,4-butanediol divinyl ether, tetramethylene glycol divinyl ether, and neopentyl. Glycol divinyl ether, trimethylol propane trivinyl ether, hexanediol divinyl ether, 1,4-cyclohexanediol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, sorbitol tetravinyl ether, sorbitol pentavinyl ether and trimethylol propane trivinyl ether.

In the case of a negative resist material, the content of the crosslinking agent is preferably 0.1 to 50 parts by weight, more preferably 1 to 40 parts by weight, based on 100 parts by weight of the base polymer.

The resist material of the present invention may contain a quencher other than the sulfonium salt of the iodinated benzene ring-containing sulfonamide. Other quenchers are typically selected from basic compounds of conventional type. As a basic compound of a conventional form, primary, secondary, and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxyl group, nitrogen-containing compounds having a sulfonyl group, and hydroxyl groups A nitrogen-containing compound, the nitrogen-containing compound which has a hydroxyphenyl group, alcoholic nitrogen-containing compound, amides, imides, carbamates, etc. are mentioned. The primary, secondary, and tertiary amine compounds described in paragraphs [0146] to [0164] of JP-A 2008-111103, in particular, a hydroxyl group, an ether bond, an ester bond, a lactone ring, a cyano group, and a sulfonic acid ester Also included are an amine compound having a group and a compound having a carbamate group described in JP 3790649. By adding such a basic compound, the diffusion rate of the acid in the resist film can be further suppressed or the pattern shape can be corrected.

As other quenchers, onium salts such as sulfonium salts, iodonium salts and ammonium salts of sulfonic acids and carboxylic acids in which the α-position described in USP 8,795,942 (JP-A 2008-158339) are not fluorinated can be used. Although α-fluorinated sulfonic acid, imide acid and methic acid are required to deprotect the acid labile group of the carboxylic acid ester, salt exchange with the α non-fluorinated onium salt releases α-nonfluorinated sulfonic acid and carboxylic acid. The α non-fluorinated sulfonic acid and carboxylic acid function as a quencher because they do not undergo a deprotection reaction.

As other quenchers, polymeric quenchers described in USP 7,598,016 (JP-A 2008-239918) are also useful. This polymer type quencher improves the sphericity of the resist after patterning by aligning it to the resist surface after coating. The polymer type quencher also has an effect of preventing a reduction in the film thickness of the resist pattern and rounding of the pattern top when a protective film for immersion exposure is applied.

0-5 weight part is preferable with respect to 100 weight part of base polymers, and, as for content of another quencher, 0-4 weight part is more preferable.

The resist material of the present invention may be blended with a polymer additive (or water repellency improving agent) for improving the water repellency of the surface of the resist film after spin coating. The water repellency improving agent may be used for immersion lithography without using a topcoat. As the water repellency improving agent, a polymer compound having a fluoroalkyl group, a polymer compound having a 1,1,1,3,3,3-hexafluoro-2-propanol residue having a specific structure, etc. are suitable, and JP-A 2007- 297590, JP-A 2008-111103 and the like. The water repellency improving agent added to the resist material needs to be dissolved in an organic solvent developer. The water repellency improver having a 1,1,1,3,3,3-hexafluoro-2-propanol residue having the above-described specific structure has good solubility in a developer. A polymer compound having an amino group or an amine salt copolymerized as a repeating unit can act as a water repellent additive, and it is highly effective in preventing the evaporation of acid in the PEB to prevent defective opening of the hole pattern after development. The water repellency improving agent may be used alone or in combination. An appropriate amount of the water repellency improving agent is 0 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the base polymer.

Acetylene alcohol can also be mix|blended with the resist material of this invention. As the acetylene alcohols, those described in paragraphs [0179] to [0182] of JP-A 2008-122932 are suitable. A suitable blending amount of acetylene alcohol is 0 to 5 parts by weight based on 100 parts by weight of the base polymer.

How to form a pattern

The resist material of the present invention is used in the manufacture of a variety of integrated circuits. Pattern formation using the resist material can be performed by a known lithography technique. These techniques generally include coating, pre-firing, exposure and development. Additional steps may be added if necessary.

For example, the resist material may be used as a substrate for manufacturing an integrated circuit (eg, Si, SiO ₂ , SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflection film, etc.) or a substrate for manufacturing a mask circuit (eg, Cr, CrO, CrON, MoSi). ₂ , SiO ₂ etc.), it is first applied by an appropriate coating technique such as spin coating, roll coating, flow coating, dip coating, spray coating, and doctor coating. This coating is pre-fired on a hot plate at 60 to 150° C. for 10 seconds to 30 minutes, preferably at 80 to 120° C. for 30 seconds to 20 minutes. The resulting resist film is generally 0.01 to 2.0 mu m thick.

Next, the target pattern is exposed directly or through a predetermined mask with high energy rays such as ultraviolet rays, far ultraviolet rays, EB, EUV, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation. The exposure dose is preferably about 1 to 200 mJ/cm 2 , more preferably about 10 to 100 mJ/cm 2 , or about 0.1 to 100 μC/cm 2 , more preferably about 0.5 to 50 μC/cm 2 . Next, on a hot plate, the resist film is further baked (PEB) at 60 to 150° C. for 10 seconds to 30 minutes, preferably at 80 to 120° C. for 30 seconds to 20 minutes.

PEB may or may not be performed. In particular, in the case of the anion-bound PAG polymer containing the repeating unit (f2) or (f3), sulfonic acid is generated upon exposure to improve alkali solubility. Therefore, even if PEB is not performed, the exposed portion of the resist film is dissolved in alkali. If PEB is not performed, image blur due to acid diffusion is eliminated, and finer pattern formation than in the case of PEB can be expected.

When PEB is not performed, the deprotection reaction by acid does not occur, so the resist material of the present invention functions as a non-chemically amplified resist material. In this case, since the dissolution contrast is low, a film decrease in the pattern or a residual film in the space portion occurs after development. In a non-chemically amplified resist material, how to improve the dissolution contrast is a key point.

In the case of the anion-bound PAG polymer containing the repeating unit (f2) or (f3), ?-fluorosulfonic acid is generated upon exposure to improve solubility in an alkaline developer. By adding the onium salt of sulfonic acid in which the α-position is not fluorinated, the generation of α-fluorosulfonic acid is suppressed by salt exchange therewith. When the exposure dose is further increased, the alkali solubility is improved by decomposing the onium salt of the sulfonic acid or carboxylic acid in which the α-position is not fluorinated. That is, in the area|region with a small exposure amount, the dissolution inhibiting property improves, and the dissolution promoting property improves in the area|region with a large exposure amount, and contrast improves. Since the rate of the ion exchange reaction is fast and proceeds at room temperature, there is no need to perform PEB. Since the onium salt having the formula (A) is also a salt weaker than α-fluorosulfonic acid, ion exchange of the same formula occurs. Thereby, even when PEB is not performed, the contrast is improved.

Then, the resist film is developed with a developer in the form of an aqueous base solution for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes, by a conventional method such as an immersion method, a puddle method, or a spray method. A typical developer is 0.1 to 10% by weight, preferably 2 to 5% by weight of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetrabutyl It is an aqueous solution, such as ammonium hydroxide (TBAH). When the resist film is dissolved in the developer, the portion irradiated with light is dissolved in the developer, and the unexposed portion does not dissolve. In this way, an objective positive pattern is formed on the substrate. In the case of a negative resist, in contrast to the case of a positive resist, that is, the portion of the resist film irradiated with light is insolubilized in the developer, and the unexposed portion is dissolved. It should be understood that the resist material of the present invention is optimal for fine patterning by KrF excimer laser, ArF excimer laser, EB, EUV, X-ray, soft X-ray, gamma-ray, and synchrotron radiation among high-energy rays.

In an alternative embodiment, using a positive resist material including a base polymer having an acid labile group, a negative pattern may be formed by organic solvent development. The developing solution used at this time is preferably 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclo Hexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, valeric acid Methyl, methyl penthenate, methyl crotonate, ethyl crotonate, methyl propionate, ethyl propionate, 3-ethoxypropionate ethyl, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, Methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenyl acetate, benzyl formate, phenyl ethyl formate, 3-phenylpropionate methyl, benzyl propionate, phenylacetic acid ethyl, 2-phenylethyl acetate, and mixtures thereof.

At the end of development, the resist film is rinsed. As the rinsing solution, a solvent that is miscible with the developer and does not dissolve the resist film is preferable. Suitable solvents include alcohols having 3 to 10 carbon atoms, ether compounds having 8 to 12 carbon atoms, alkanes, alkenes, alkynes, and aromatic solvents having 6 to 12 carbon atoms. Specifically, as the alcohol having 3 to 10 carbon atoms, n-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, t-butyl alcohol, 1-pentanol, 2-pentanol, 3 -Pentanol, t-pentyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexane ol, 3-hexanol, 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, 2-methyl-1 -Pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4 -Methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol, 1-octanol and the like are suitable. Examples of the ether compound having 8 to 12 carbon atoms include di-n-butyl ether, diisobutyl ether, di-s-butyl ether, di-n-pentyl ether, diisopentyl ether, di-s-pentyl ether, and di-t. -pentyl ether, di-n-hexyl ether, etc. are suitable. Examples of the alkane having 6 to 12 carbon atoms include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, and cyclononane. etc. are appropriate. As the alkene having 6 to 12 carbon atoms, hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, cyclooctene and the like are suitable. As the alkyne having 6 to 12 carbon atoms, hexine, heptine, octyne and the like are suitable. As an aromatic solvent, toluene, xylene, ethylbenzene, isopropylbenzene, t-butylbenzene, mesitylene, etc. are suitable. These solvents may be used individually or in mixture.

By rinsing, it is possible to reduce the risk of collapse of the resist pattern or occurrence of defects. However, rinsing is not necessarily required. By not rinsing, the amount of solvent used can be reduced.

The hole pattern or trench pattern after development can also be shrunk by thermalflow, RELACS® or DSA technology. By applying a shrink agent on the hole pattern, crosslinking of the shrink agent can occur on the surface of the resist by diffusion of an acid catalyst from the resist layer during firing, so that the shrink agent can adhere to the sidewall of the hole pattern. The firing temperature is preferably 70 to 180°C, more preferably 80 to 170°C, and the time is preferably 10 to 300 seconds. Reduces the hole pattern by removing unnecessary constrictors.

Example

Hereinafter, although an Example of this invention is shown and this invention is demonstrated concretely, this invention is not limited to the following Example. The abbreviation “pbw” is parts by weight.

Synthesis example 1-1

Synthesis of triphenylsulfonium N-[(trifluoromethyl)sulfonyl]-2,3,5-triiodobenzamide (sulfonium salt 1)

After heating a mixture of 100 g of 2,3,5-triiodobenzoic acid, 0.73 g of dimethylformamide, and 700 g of chloroform at 60°C, 47.6 g of thionyl chloride was added dropwise. The solution was stirred at 60° C. for 21 hours, and then concentrated under reduced pressure to remove chloroform and unreacted thionyl chloride. To the concentrate, 500 g of hexane was added, followed by stirring for 1 hour to precipitate a solid. 97 g of 2,3,5-triiodobenzoyl chloride was obtained as a solid by filtering the obtained solid and washing|cleaning once with hexane.

To a mixture of 2.24 g of trifluoromethanesulfonylamide, 3.73 g of potassium carbonate, and 40 g of acetonitrile, a portion of the 2,3,5-triiodobenzoyl chloride (10.1 g) was added, and the mixture was stirred at room temperature for 15 hours. . Then, 120 g of deionized water was added dropwise to the reaction solution to quench the reaction, and then 6.74 g of triphenylsulfonium methyl sulfate and 80 g of methylene chloride were added and stirred. After removing the insoluble content by filtration, the organic layer was fractionated. The obtained organic layer was washed in this order with 40 g of deionized water, 40 g of 2.5 mass% hydrochloric acid, 40 g of deionized water, 60 g of an aqueous sodium hydrogen carbonate solution and 40 g of deionized water. The washed organic layer was concentrated under reduced pressure. To the obtained concentrate, 60 g of tert-butylmethyl ether was added and stirred. After removing the supernatant, the residue was concentrated under reduced pressure, and the target product, triphenylsulfonium N-[(trifluoromethyl)sulfonyl]-2,3,5-triiodobenzamide (referred to as sulfonium salt 1) 10.5 g was obtained as an oil (yield 78%).

Sulfonium salt 1 was analyzed by spectroscopy. IR spectrum data is shown below. NMR spectra, ¹ H-NMR and ¹⁹ _{F-NMR in DMSO-d 6} are shown in FIGS. 1 and 2 , respectively. ^{In 1} H-NMR analysis, trace amounts of residual solvents (tert-butylmethyl ether and water) were observed.

IR (D-ATR): ν = 3520, 3061, 2972, 1628, 1518, 1476, 1447, 1387, 1363, 1304, 1238, 1196, 1117, 1078, 1021, 998, 925, 865, 821, 748, 711 , 684, 614, 581, 502 cm ^-1

Synthesis example 1-2~1-24

Synthesis of sulfonium salts 2 to 15, iodonium salts 1 to 3 and ammonium salts 1 to 6

The structures of sulfonium salts 1 to 15, iodonium salts 1 to 3 and ammonium salts 1 to 6 of sulfonamides containing a benzene iodide ring used in the resist material of the present invention are collectively shown below.

Sulfonium salts 2 to 15 and iodonium salts 1 to 3 were similar to Synthesis Example 1-1, respectively, for ion exchange of benzene iodide ring-containing sulfonamide giving the following anion and sulfonium methanesulfonate giving the following cation. synthesized by Ammonium salts 1 and 2 were synthesized by a neutralization reaction of quaternary ammonium hydroxide with benzene iodide ring-containing sulfonamide giving the following anion, and ammonium salts 3 to 6 were sulfonamide containing benzene iodide ring giving the following anion and It synthesize|combined by the neutralization reaction of a tertiary amine compound.

Synthesis example 2-1~2-5

Synthesis of base polymers (Polymers 1 to 5)

By combining appropriate monomers, copolymerization reaction was carried out in a tetrahydrofuran (THF) solvent, and the reaction solution was poured into methanol for crystallization, washed with hexane, and then isolated and dried to prepare a base polymer. The compositions of the obtained base polymers, referred to as base polymers 1 to 6 ^{, were analyzed by 1} H-NMR spectroscopy, and Mw and Mw/Mn were analyzed in terms of polystyrene by GPC using THF as a solvent.

Example 1-30 and comparative example 1-7

A polymer and selected components having the compositions shown in Tables 1 to 3 were dissolved in a solvent and filtered through a filter having a pore size of 0.2 µm to prepare a resist material. The solvent contained 100 ppm of surfactant FC-4430 (3M). Components in Tables 1 to 3 are as follows.

Organic solvents:

PGMEA (propylene glycol monomethyl ether acetate)

GBL (γ-butyrolactone)

CyH (cyclohexanone)

PGME (propylene glycol monomethyl ether)

DAA (diacetone alcohol)

Acid generator: PAG 1 to PAG 7 of the following structural formula

Comparative quenchers 1 to 6 of the following structural formulas

EB lithography exam

On the silicon substrate, an antireflection film (DUV-62, Nissan Chemical Corp.) having a thickness of 60 nm was coated. Each of the resist materials shown in Tables 1 to 3 was spin-coated on the substrate, and pre-baked on a hot plate at 105 DEG C for 60 seconds to prepare a resist film having a thickness of 50 nm. The resist film was exposed to an electron beam using an EB drawing apparatus ELS-F125 (Elionix Co. Ltd., acceleration voltage 125 kV), and then baked (PEB) on a hot plate at the temperature shown in Tables 1 to 3 for 60 seconds. and development was performed for 30 seconds with a 2.38 wt% TMAH aqueous solution to form a pattern. In Examples 1 to 13 and 15 to 30 and Comparative Examples 1 to 6, a positive resist pattern, that is, a hole pattern having a dimension of 24 nm was formed. In Example 14 and Comparative Example 7, a negative resist pattern, that is, a dot pattern having a dimension of 24 nm was formed.

The resist pattern was observed under CD-SEM (CG-5000, Hitachi High-Technologies Corp.). The exposure amount when a hole or dot pattern was formed with a dimension of 24 nm was reported as the sensitivity. At this time, the diameter of the hole or dot was measured at 50 points, and the dimensional variation (3σ) was calculated and reported as CDU.

The resist composition is shown in Tables 1-3 together with the sensitivity and CDU of EB lithography.

From Tables 1 to 3, it was found that the resist material of the present invention containing the onium salt of the formula (A) had high sensitivity and improved CDU.

Japanese Patent Application Nos. 2018-104855 and 2019-028583 are incorporated herein by reference.

While some preferred embodiments have been described, many modifications and variations can be made in light of the above teachings. Accordingly, it is to be understood that the present invention may be practiced otherwise than as specifically described without departing from the scope of the appended claims.

Claims (15)

A resist material comprising a base polymer and an onium salt having the following formula (A):

wherein R ¹ is hydrogen, hydroxy, C ₁ -C ₆ alkyl group, C ₁ -C ₆ alkoxy group, C ₂ -C ₇ acyloxy group, C ₂ -C ₇ alkoxycarbonyl group, C ₁ -C ₄ alkylsulfo nyloxy group, fluorine, chlorine, bromine, amino, nitro, cyano group, -NR ^1A -C(=O)-R ^1B or -NR ^1A -C(=O)-OR ^1B , wherein the alkyl group, alkoxy group, acyl group Some or all of the hydrogen atoms of the oxy group, the alkoxycarbonyl group and the alkylsulfonyloxy group may be substituted with halogen atoms, R ^1A is hydrogen or a C ₁ -C ₆ alkyl group, R ^1B is a C ₁ -C ₆ alkyl group or C ₂ -C _{8 is an} alkenyl group,
R ² is a C ₁ -C ₁₀ alkyl group or a C ₆ -C ₁₀ aryl group, some or all of the hydrogen atoms are amino, nitro, cyano, C ₁ -C ₁₂ alkyl, C ₁ -C ₁₂ alkoxy, C ₂ -C ₁₂ alkoxycarbonyl, C ₂ -C ₁₂ acyl, C ₂ -C ₁₂ alkylcarbonyloxy, hydroxy or halogen may be substituted;
X ¹ is a single bond or a C ₁ -C ₂₀ divalent linking group, and may contain an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen, a hydroxyl group or a carboxy group;
m and n are integers satisfying 2≤m≤4, 0≤n≤3, and 2≤m+n≤5,
M ⁺ is a sulfonium cation having the formula (Aa), an iodonium cation having the formula (Ab) or an ammonium cation having the formula (Ac):

In the formula, R ^a1 to ^{R a3} are each independently a halogen or a C ₁ -C ₂₀ monovalent hydrocarbon group which ^{may contain a hetero atom, or any two of R a1} , R ^a2 and R ^a3 are mutually bonded to each other. It may form a ring with the sulfur atom to which it bonds,
R ^a4 and R ^a5 are each independently a halogen or a C ₁ -C ₂₀ monovalent hydrocarbon group which may contain a hetero atom,
R ^a6 to ^{R a9} are each independently hydrogen or a C ₁ -C ₂₄ monovalent hydrocarbon group, halogen, hydroxy, carboxy, ether bond, ester bond, thiol, thioester bond, thionoester bond, dithioester bond , may contain an amino group, nitro group, sulfone group or ferrocenyl group, R ^a6 and R ^a7 may be bonded to each other to form a ring together with the nitrogen atom to which they are bonded, and a pair of ^{R a6} and R ^{a7 and R a8} and R ^a9 may combine with each other to form a spiro ring together with the nitrogen atom to which they are bonded, or R ^a8 and R ^a9 may combine to form =C(R ^a10 )(R ^a11 ), R ^a10 and R ^a11 is each independently hydrogen or a C ₁ -C ₁₆ monovalent hydrocarbon group, and R ^a10 and R ^a11 may be bonded to each other to form a ring together with the carbon and nitrogen atoms to which they are bonded, in which a double bond, oxygen , a sulfur or nitrogen atom may be included. delete The resist material according to claim 1, further comprising an acid generator capable of generating sulfonic acid, imide acid or methic acid. The resist material according to claim 1, further comprising an organic solvent. The resist material according to claim 1, wherein the base polymer comprises a repeating unit having the following formula (a1) or a repeating unit having the following formula (a2):

wherein R ^A is each independently hydrogen or methyl, Y ¹ is a single bond, a phenylene group or a naphthylene group, or a C ₁ -C ₁₂ linking group including an ester bond or a lactone ring, and Y ² is a single bond or It is an ester bond, and R ¹¹ and R ¹² are each an acid labile group. The resist material according to claim 5, which is a chemically amplified positive resist material. The resist material of claim 1, wherein the base polymer does not contain acid labile groups. 8. The resist material of claim 7, further comprising a crosslinking agent. The resist material according to claim 7, which is a chemically amplified negative resist material. The resist material according to claim 1, wherein the base polymer further comprises at least one repeating unit selected from repeating units having the following formulas (f1) to (f3):

wherein R ^A is each independently hydrogen or methyl;
Z ¹ is a single bond, a phenylene group, -OZ ¹¹ -, -C(=O)-OZ ¹¹ - or -C(=O)-NH-Z ¹¹ -, and Z ¹¹ is a C ₁ -C ₆ alkanediyl group , C ₂ -C ₆ an alkenediyl group or a phenylene group, and may contain a carbonyl, ester bond, ether bond or hydroxyl group,
Z ² is a single bond, -Z ²¹ -C(=O)-O-, -Z ²¹ -O-, or -Z ²¹ -OC(=O)-, Z ²¹ is a C ₁ -C ₁₂ alkanediyl group , may contain a carbonyl group, an ester bond or an ether bond,
Z ³ is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, -C(=O)-OZ ³¹ - or -C(=O)-NH-Z ³¹ -, and Z ³¹ is C ₁ -C ₆ an alkanediyl group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with trifluoromethyl, or a C ₂ -C ₆ alkenediyl group, which may contain a carbonyl group, an ester bond, an ether bond or a hydroxyl group;
A is hydrogen or trifluoromethyl,
R ²¹ to ^{R 28} _{are each independently a C 1} -C ₂₀ monovalent hydrocarbon group which may contain a hetero atom, ^{and any two of R 23} , R ²⁴ and R ²⁵ or any of R ²⁶ , R ²⁷ and R ²⁸ Two may be bonded to each other to form a ring together with the sulfur atom to which they are bonded,
M ⁻ is a non-nucleophilic counter ion. The resist material of claim 1 , further comprising a surfactant. A pattern forming method comprising the steps of applying the resist material of claim 1 on a substrate, heat-treating to form a resist film, exposing the resist film to high energy rays, and developing the exposed resist film in a developer solution. . The pattern forming method according to claim 12, wherein the high energy ray is an ArF excimer laser having a wavelength of 193 nm or a KrF excimer laser having a wavelength of 248 nm. The pattern forming method according to claim 12, wherein the high energy ray is EB or EUV having a wavelength of 3 to 15 nm. A sulfonium salt having the formula (B):

wherein R ¹ is hydrogen, hydroxy, C ₁ -C ₆ alkyl group, C ₁ -C ₆ alkoxy group, C ₂ -C ₇ acyloxy group, C ₂ -C ₇ alkoxycarbonyl group, C ₁ -C ₄ alkylsulfo nyloxy group, fluorine, chlorine, bromine, amino, nitro, cyano group, -NR ^1A -C(=O)-R ^1B or -NR ^1A -C(=O)-OR ^1B , wherein the alkyl group, alkoxy group, acyl group Some or all of the hydrogen atoms of the oxy group, the alkoxycarbonyl group and the alkylsulfonyloxy group may be substituted with halogen, R ^1A is hydrogen or a C ₁ -C ₆ alkyl group, R ^1B is a C ₁ -C ₆ alkyl group or C ₂ -C _{8 is an} alkenyl group,
R ² is a C ₁ -C ₁₀ alkyl group or a C ₆ -C ₁₀ aryl group, some or all of the hydrogen atoms are amino, nitro, cyano, C ₁ -C ₁₂ alkyl, C ₁ -C ₁₂ alkoxy, C ₂ -C ₁₂ alkoxycarbonyl, C ₂ -C ₁₂ acyl, C ₂ -C ₁₂ alkylcarbonyloxy, hydroxy or halogen may be substituted;
X ¹ is a single bond or a C ₁ -C ₂₀ divalent linking group, and may contain an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen, a hydroxy group or a carboxy group;
m and n are integers satisfying 2≤m≤4, 0≤n≤3, and 2≤m+n≤5,
R ^a1 to ^{R a3} are each independently halogen or a C ₁ -C ₂₀ monovalent hydrocarbon group which may contain a hetero atom, or sulfur to which any two of ^{R a1} , R ^a2 and R ^{a3 are bonded to each other} You may form a ring with an atom.

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