JP2012153644A - Sulfonium salt, resist material, and pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide sulfonium salt that is used as a photoacid generator, has high resolution, and forms a resist pattern of a low crude density dependence in photolithography using, as a light source, a high energy beam such as ArF excimer laser beam or EUV, provide a resist material containing the sulfonium salt, and provide a pattern forming method using the resist material.SOLUTION: This sulfonium salt is represented by general formula (1a) or (1b). In the formula, R shows straight-chain, divergent, or cyclic 7C-30C univalent hydrocarbon group that may contain a heteroatom, and n shows an integer of 1-4.

Description

  The present invention relates to (1) a naphthylsulfonium cation having a hydroxyl group or an ethylene glycol chain and a sulfonium salt of a specific anion, (2) a resist material containing the sulfonium salt, and (3) a pattern forming method using the resist material. . In the present invention, the high energy rays include ultraviolet rays, far ultraviolet rays, electron beams, EUV, X-rays, excimer lasers, γ rays, and synchrotron radiation.

  In recent years, with the high integration and high speed of LSIs, miniaturization of pattern rules is demanded, and far ultraviolet lithography and vacuum ultraviolet lithography are promising as next-generation fine processing techniques. Among them, photolithography using ArF excimer laser light as a light source is an indispensable technique for ultrafine processing of 0.13 μm or less.

ArF lithography began to be used in part from the fabrication of 130 nm node devices and became the main lithography technology from 90 nm node devices. As lithography technology for the next 45nm node, initially 157nm lithography using F ₂ laser is promising, its development was retarded by several problems have been pointed out, water between the projection lens and the wafer, ethylene glycol, glycerin, etc. By inserting a liquid having a refractive index higher than that of air, the numerical aperture (NA) of the projection lens can be designed to be 1.0 or more, and ArF immersion lithography capable of achieving high resolution has rapidly emerged (for example, non-reflective) Patent Document 1: Journal of photopolymer Science and Technology Vol. 17, No. 4, p587 (2004)), is in a practical stage. For this immersion lithography, a resist material that does not easily dissolve in water is required.

  In ArF lithography, in order to prevent deterioration of precise and expensive optical system materials, a resist material with high sensitivity that can exhibit sufficient resolution with a small exposure amount is required. It is most common to select a highly transparent material at a wavelength of 193 nm. For example, with respect to the base resin, polyacrylic acid and its derivatives, norbornene-maleic anhydride alternating polymer, polynorbornene and ring-opening metathesis polymer, ring-opening metathesis polymer hydrogenated product, etc. have been proposed. Some achievements have been achieved in terms of raising the nature.

  Various studies have also been made on photoacid generators. As a photoacid generator for an ArF chemically amplified resist material, a triphenylsulfonium salt that is excellent in stability in the resist material is generally used (Patent Document 1: Japanese Patent Laid-Open No. 2009-7327). However, there is a drawback that absorption at the ArF exposure wavelength (193 nm) is large, the transmittance of the resist film is lowered, and resolution may be low. Therefore, 4-alkoxynaphthyl-1-tetrahydrothiophenium cation and the like have been developed for the purpose of high sensitivity and high resolution (Patent Document 2: Japanese Patent No. 3632410) and have a plurality of acid labile groups. Although a resist composition (Patent Document 3: Japanese Patent No. 3955575) in combination with a resin or the like is also disclosed, this naphthyl-1-tetrahydrothiophenium is derived from an alkylsulfonium salt structure that is susceptible to a nucleophilic substitution reaction or the like. The problem is low stability in resist solutions, line widths between dense patterns and isolated patterns, and pattern shape differences. In particular, the pattern shape difference between the dark area and the bright area is a problem. The dark area is, for example, a light shielding area of a bulk pattern on both sides of 10 line and space patterns (in the case of a positive resist), and the bright area is a vast space on both sides of, for example, 10 line and space patterns. Part transmission area (in the case of a positive resist). The optical condition at the center of the 10 line and space patterns is the same for both the dark area and the bright area, but there is a pattern difference between the dark area and the bright area, which is a problem.

JP 2009-7327 A Japanese Patent No. 3632410 Japanese Patent No. 3955575

Journal of photopolymer Science and Technology Vol. 17, no. 4, p587 (2004)

  The present invention has been made in view of the above circumstances, and is used as a photoacid generator in photolithography using a high energy beam such as ArF excimer laser light or EUV as a light source, and has excellent resolution and low density dependency. An object of the present invention is to provide a sulfonium salt capable of forming a resist pattern, a resist material containing the sulfonium salt, and a pattern forming method using the resist material.

  As a result of intensive investigations to achieve the above object, the present inventors have developed a naphthylsulfonium cation having a hydroxyl group or an ethylene glycol chain represented by the following general formula (1a) or (1b) and a sulfonium salt of a specific anion. It has been found that the resist material used as the acid generator is excellent in the resolution of the resist film and is extremely effective for precise microfabrication, and has led to the present invention.

（式中、Ｒはヘテロ原子を含んでもよい炭素数７〜３０の直鎖状、分岐状又は環状の１価の炭化水素基を示し、ｎは１〜４の整数を示す。）
請求項２：
請求項１記載の式（１ｂ）で示されるスルホニウム塩において、ｎが１であることを特徴とするスルホニウム塩。
請求項３：
請求項１又は２記載のスルホニウム塩を含むことを特徴とする化学増幅型レジスト材料。
請求項４：
請求項１又は２記載のスルホニウム塩を含むことを特徴とする化学増幅ポジ型レジスト材料。
請求項５：
請求項３又は４記載のレジスト材料を基板上に塗布する工程と、加熱処理後フォトマスクを介して高エネルギー線で露光する工程と、必要に応じて加熱処理した後、現像液を用いて現像する工程とを含むことを特徴とするパターン形成方法。
請求項６：
請求項３又は４記載のレジスト材料を基板上に塗布する工程と、加熱処理後、水に不溶でアルカリ現像液に可溶な保護膜を塗布する工程と、当該基板と投影レンズの間に水を挿入しフォトマスクを介して高エネルギー線で露光する工程と、必要に応じて加熱処理した後、現像液を用いて現像する工程とを含むことを特徴とするパターン形成方法。 That is, the present invention provides the following sulfonium salt, resist material and pattern forming method.
Claim 1:
A sulfonium salt represented by the following general formula (1a) or (1b).

(In the formula, R represents a linear, branched or cyclic monovalent hydrocarbon group having 7 to 30 carbon atoms which may contain a hetero atom, and n represents an integer of 1 to 4.)
Claim 2:
The sulfonium salt represented by the formula (1b) according to claim 1, wherein n is 1.
Claim 3:
A chemically amplified resist material comprising the sulfonium salt according to claim 1.
Claim 4:
A chemically amplified positive resist material comprising the sulfonium salt according to claim 1.
Claim 5:
A step of applying the resist material according to claim 3 or 4 on a substrate, a step of exposing to high energy rays through a photomask after heat treatment, and heat treatment as necessary, followed by development using a developer. The pattern formation method characterized by including the process to perform.
Claim 6:
A step of applying the resist material according to claim 3 or 4 on a substrate, a step of applying a protective film insoluble in water and soluble in an alkaline developer after heat treatment, and water between the substrate and the projection lens. A pattern forming method comprising: a step of exposing with a high energy beam through a photomask; and a step of developing with a developer after heat treatment as necessary.

  The resist material of the present invention can also be applied to immersion lithography. In immersion lithography, exposure is performed by inserting an immersion medium between the pre-baked resist film and the projection lens. In ArF immersion lithography, pure water is mainly used as an immersion medium. It is an important technique for extending the life of ArF lithography to the 65 nm node and beyond by combining with a projection lens having an NA of 1.0 or more, and development is accelerated.

  Further, the resist material of the present invention can reduce the pattern size after development by various shrink methods. For example, the hole size can be shrunk by a known method such as thermal flow, RELACS, SAFIRE, or WASOOM. Particularly when a hydrogenated ROMP polymer (cycloolefin ring-opening metathesis polymer hydrogenated product) having a low polymer Tg is blended, the hole size can be effectively reduced by thermal flow.

  Unlike the normal sulfonium salt, the sulfonium salt of the present invention has a highly hydrophilic phenolic hydroxyl group or ethylene glycol chain. When the sulfonium salt of the present invention combined with a specific anion is used as a resist material, It is very useful as a photoacid generator for chemically amplified resist materials because it has little elution into immersion water and has little pattern dependency (dark bright difference).

₆ is a diagram showing ¹ H-NMR / DMSO-d ₆ of [PAG-1] in Synthesis Example 2. FIG. ₆ is a diagram showing ¹⁹ F-NMR / DMSO-d ₆ of [PAG-1] in Synthesis Example 2. FIG. ₆ is a diagram showing ¹ H-NMR / DMSO-d ₆ of [PAG-2] in Synthesis Example 4. FIG. ₆ is a diagram showing ¹⁹ F-NMR / DMSO-d ₆ of [PAG-2] in Synthesis Example 4. FIG. ₆ is a diagram showing ¹ H-NMR / DMSO-d ₆ of [PAG-3] in Synthesis Example 5. FIG. ₆ is a diagram showing ¹⁹ F-NMR / DMSO-d ₆ of [PAG-3] in Synthesis Example 5. FIG. ₆ is a diagram showing ¹ H-NMR / DMSO-d 6 of [PAG-4] in Synthesis Example 6. FIG. It is a diagram showing the ^{19 F-NMR / DMSO-d} 6 of [PAG-4] of Synthesis Example 6.

（式中、Ｒはヘテロ原子を含んでもよい炭素数７〜３０の直鎖状、分岐状又は環状の１価の炭化水素基を示し、ｎは１〜４の整数を示す。） The present invention first provides a sulfonium salt represented by the following general formula (1a) or (1b).

(In the formula, R represents a linear, branched or cyclic monovalent hydrocarbon group having 7 to 30 carbon atoms which may contain a hetero atom, and n represents an integer of 1 to 4.)

Hereinafter, the sulfonium salt represented by the general formula (1a) or (1b) will be described in detail.
In the above formulas (1a) and (1b), R represents a linear, branched or cyclic monovalent hydrocarbon group having 7 to 30 carbon atoms which may contain a hetero atom, a hydroxyl group, a carbonyl group, a carboxyl group Those containing a polar group such as a group are also preferably used. Specific examples include the following, but are not limited thereto.

（式中、破線は結合手を示す。）

(In the formula, a broken line indicates a bond.)

  n shows the integer of 1-4. As the number of n increases, the hydrophilicity increases. However, crystallization is often difficult, and is preferably 1.

A method for synthesizing the sulfonium cation of the general formula (1a) is known, and can be synthesized by a reaction of 1-naphthol and tetramethylene sulfoxide with hydrogen chloride gas in methanol. The sulfonium salt of the general formula (1b) can also be synthesized by a known method. When n = 1, specifically, 2-methoxyethyl chloride and 1-naphthol are reacted under basic conditions to synthesize 1- (2-methoxyethoxy) naphthalene. This is then combined with tetramethylene sulfoxide in a diphosphorus pentoxide / methanesulfonic acid solution to synthesize a sulfonium cation. When n is 2 to 4, it can be synthesized by using a corresponding substituted alkyl halide.
The anion of the sulfonium salt represented by the general formula (1a) or (1b) can be synthesized with reference to JP2009-7327A or JP2009-91350A.
The ion exchange reaction between the cation and the anion can be carried out by using an organic solvent alone such as dichloromethane, ethyl acetate, methyl isobutyl ketone, methanol, ethanol, acetonitrile, or water in combination.

In the present invention, secondly, a chemically amplified resist material characterized by containing a sulfonium salt represented by the above general formula (1a) or (1b) as a photoacid generator is provided.
Here, the resist material of the present invention is:
(A) the photoacid generator (that is, the sulfonium salt represented by the formula (1a) or (1b)),
(B) an organic solvent,
(C) a base resin whose solubility in an alkaline developer is changed by the action of an acid,
(D) quencher, if necessary
If necessary, (S) a surfactant that is insoluble or hardly soluble and soluble in alkali developer, and / or a surfactant that is insoluble or hardly soluble in water and alkali developer,
If necessary, (E) a photoacid generator other than the photoacid generator,
If necessary, (F) an organic acid derivative and / or a fluorine-substituted alcohol,
Furthermore, (G) a chemically amplified positive resist material characterized by containing a dissolution inhibitor having a weight average molecular weight of 3,000 or less, if necessary,
Or (A) the photoacid generator (that is, the sulfonium salt represented by the formula (1a) or (1b)),
(B) an organic solvent,
(C ′) an alkali-soluble resin, which is hardly soluble in alkali by a crosslinking agent,
(H) a crosslinking agent that crosslinks with an acid,
(D) quencher, if necessary
If necessary, (S) a surfactant that is insoluble or hardly soluble and soluble in alkali developer, and / or a surfactant that is insoluble or hardly soluble in water and alkali developer,
If necessary, (E) a chemically amplified negative resist material containing a photoacid generator other than the photoacid generator.

  The photoacid generator of the component (A) of the present invention is as described above, and the blending amount thereof is 0.1 to 40 parts, particularly 100 parts by weight of the base resin in the resist material (parts by mass, the same applies hereinafter). 1 to 20 parts.

  (B) component organic solvent used in the present invention, (C) base resin whose solubility in an alkaline developer is changed by the action of acid, (D) quencher, (S) water-insoluble or hardly soluble and alkaline A developer-soluble surfactant, and / or a surfactant that is insoluble or hardly soluble in water and an alkaline developer, (E) a photoacid generator other than the photoacid generator, (F) an organic acid derivative, and / or Or a fluorine-substituted alcohol, (G) a dissolution inhibitor having a weight average molecular weight of 3,000 or less, (C ′) an alkali-soluble resin, which is a base resin that is hardly alkali-soluble by a crosslinking agent, and (H) a crosslinking that is crosslinked by an acid. Details of the agent and the like are described in detail in JP2009-269953A or JP2010-215608A.

  Among the organic solvents of component (B), diethylene glycol dimethyl ether, 1-ethoxy-2-propanol, propylene glycol monomethyl ether acetate, cyclohexanone, 4-butyrolactone and mixed solvents thereof, which have the highest solubility of the acid generator in the resist component Are preferably used.

  The amount of the organic solvent used is preferably 200 to 5,000 parts, particularly 400 to 3,000 parts, based on 100 parts of the base resin.

  As the base resin for the component (C), those described in JP-A-2009-269953 or JP-A-2010-215608 can be used. As the acid labile group, the acid labile group definition (L3) or (L4) described in the above publication is preferably used. Polymethacrylate is preferably used as the resin, and the base resin is not limited to one type, and two or more types can be added. By using a plurality of types, the performance of the resist material can be adjusted.

Further, the base resin of component (C) or component (C ′) used in the present invention is polyhydroxystyrene (PHS), hydroxystyrene and styrene, (meth) acrylic for KrF excimer laser resist materials. For acid esters, copolymers with other polymerizable olefin compounds, and ArF excimer laser resist materials, poly (meth) acrylic acid esters, alternating copolymers of cycloolefin and maleic anhydride, and further vinyl ethers or Copolymers containing (meth) acrylic acid esters, polynorbornenes, cycloolefin ring-opening metathesis polymerization systems, cycloolefin ring-opening metathesis polymer hydrogenated products, etc., and the above KrF for F ₂ excimer laser resist materials, Fluorine-substituted product of ArF polymer That, without being limited to these polymerization type polymer. Base resins can be used alone or in admixture of two or more. In the case of a positive resist material, the dissolution rate of unexposed areas is generally reduced by substituting phenol or carboxyl groups or hydroxyl groups of fluorinated alkyl alcohols with acid labile groups.

  In this case, the component (C) used in the present invention is any one of repeating units represented by the following general formulas (C2) to (C4) other than the acid labile group represented by the following general formula (C1). It is preferable to contain the above.

（式中、Ｒ^C01は水素原子、フッ素原子、メチル基又はトリフルオロメチル基を示す。Ｒ^C02及びＲ^C03はそれぞれ独立に水素原子又は水酸基を示す。ＸＡは酸不安定基を示す。ＹＬはラクトン構造を有する置換基を示す。ＺＡは水素原子、炭素数１〜１５のフルオロアルキル基、又は炭素数１〜１５のフルオロアルコール含有置換基を示す。）

(Wherein R ^C01 represents a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ^C02 and R ^C03 each independently represent a hydrogen atom or a hydroxyl group. XA represents an acid labile group. YL represents A substituent having a lactone structure, ZA represents a hydrogen atom, a fluoroalkyl group having 1 to 15 carbon atoms, or a fluoroalcohol-containing substituent having 1 to 15 carbon atoms;

  The polymer containing the repeating unit represented by the general formula (C1) is decomposed by the action of an acid to generate a carboxylic acid, thereby giving a polymer that becomes alkali-soluble. The acid labile group XA can be variously used, specifically, a group represented by the following general formulas (L1) to (L4), a tertiary alkyl group having 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, Examples of each alkyl group include a trialkylsilyl group having 1 to 6 carbon atoms and an oxoalkyl group having 4 to 20 carbon atoms.

Here, a broken line shows a bond (hereinafter the same).
In the formula (L1), R ^L01 and R ^L02 represent a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms. R ^L03 represents a monovalent hydrocarbon group which may have a hetero atom such as an oxygen atom having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, a linear, branched or cyclic alkyl group, Examples thereof include those in which a part of hydrogen atoms are substituted with a hydroxyl group, an alkoxy group, an oxo group, an amino group, an alkylamino group, or the like. R ^L01 and R ^L02 , R ^L01 and R ^L03 , R ^L02 and R ^L03 may be bonded to each other to form a ring together with the carbon atom or oxygen atom to which they are bonded, and in the case of forming a ring, R ^L01 , R ^L02 and R ^L03 each represents a linear or branched alkylene group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms.

In the formula (L2), R ^L04 is a tertiary alkyl group having 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, each alkyl group is a trialkylsilyl group having 1 to 6 carbon atoms, and oxoalkyl having 4 to 20 carbon atoms. Or a group represented by the above general formula (L1). y is an integer of 0-6.

In the formula (L3), R ^L05 represents an ^optionally substituted linear, branched or cyclic alkyl group having 6 to 20 carbon atoms or an optionally substituted aryl group having 6 to 20 carbon atoms. m is 0 or 1, n is 0, 1, 2, or 3, and 2m + n = 2 or 3.

In the formula (L4), R ^L06 represents an ^optionally substituted linear, branched or cyclic alkyl group or an optionally substituted aryl group having 6 to 20 carbon atoms. R ^{L07 to} R ^L16 each independently represent a hydrogen atom or a monovalent hydrocarbon group having 1 to 15 carbon atoms. R ^{L07 to} R ^L16 may be bonded to each other to form a ring together with the carbon atom to which they are bonded (for example, R ^L07 and R ^L08 , R ^L07 and R ^L09 , R ^L08 and R ^L10 , R ^L09 and R ^L10 , R ^L11 and R ^L12 , R ^L13 and R ^L14, etc.), in which case those involved in the bond represent a divalent hydrocarbon group having 1 to 15 carbon atoms, specifically Can be exemplified by those obtained by removing one hydrogen atom from those exemplified above for the monovalent hydrocarbon group. R ^{L07 to} R ^L16 may be bonded to each other adjacent to each other to form a double bond (for example, R ^L07 and R ^L09 , R ^L09 and R ^L15 , R ^L13 and R ^L15 etc.).

  As the quencher of the component (D), a compound capable of suppressing the diffusion rate when the acid generated from the photoacid generator diffuses into the resist film is suitable. By blending such a quencher, In addition to easy adjustment of resist sensitivity, the diffusion rate of acid in the resist film is suppressed to improve resolution, suppress sensitivity changes after exposure, reduce substrate and environmental dependence, and expose A margin, a pattern profile, etc. can be improved.

  Such quenchers include primary, secondary, and tertiary aliphatic amines, hybrid amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxyl group, and sulfonyl groups. Preferred examples include nitrogen-containing compounds having a hydroxyl group, nitrogen-containing compounds having a hydroxyl group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amides, imides, carbamates, and ammonium salts.

  In this case, a compound having high nucleophilicity or a compound having too strong basicity is unsuitable because it reacts with the sulfonium salt of the present invention. A compound obtained by protecting a primary or secondary amine with tBOC (tert-butoxycarbonyl) is preferable. In addition, compounds described in JP 2007-298869 A, JP 2010-20204 A, and the like can also be preferably used.

  In addition, these quenchers can be used individually by 1 type or in combination of 2 or more types, and a compounding quantity is 0.001-8 parts with respect to 100 parts of base resins, Especially 0.01-4 parts are preferable. When the blending amount is less than 0.001 part, there is no blending effect, and when it exceeds 8 parts, the sensitivity may be excessively lowered.

  In the case of adding the photoacid generator of component (E), any compound may be used as long as it generates an acid upon irradiation with high energy rays. Suitable photoacid generators include sulfonium salts, iodonium salts, N-sulfonyloxydicarboximides, oxime-O-aryl sulfonate type acid generators, and the like described in the above-mentioned JP 2009-7327 A. The compounds defined in (F) below are used in the same manner as (F-1) described in JP2009-269953A or (C) -1 described in JP2010-215608A be able to.

Here, in the formula, R ⁴⁰⁵ , R ⁴⁰⁶ and R ⁴⁰⁷ are each independently a hydrogen atom or a linear, branched or cyclic monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom, In particular, it represents an alkyl group or an alkoxy group, and as a hydrocarbon group which may contain a hetero atom, specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, tert-amyl group, n-pentyl group, n-hexyl group, cyclopentyl group, cyclohexyl group, ethylcyclopentyl group, butylcyclopentyl group, ethylcyclohexyl group, butylcyclohexyl group, adamantyl group, ethyladamantyl group, butyladamantyl group, and these , - - -O between carbon bonds - any carbon of group S -, - SO -, - SO 2 -, - NH-, C (= O) -, - C (= O) O -, - C (= O) NH- or a group hetero atom group is inserted, such as, any of the hydrogen atoms are -OH, -NH _2, -CHO And a group substituted with a functional group such as —CO ₂ H. R ⁴⁰⁸ represents a linear, branched or cyclic monovalent hydrocarbon group having 7 to 30 carbon atoms which may contain a hetero atom.

  In addition, since there is a possibility of impairing the stability of this compound, use an alkanesulfonic acid or arylsulfonic acid that is not fluorine-substituted such as triphenylsulfonium = 4-toluenesulfonate or triphenylsulfonium = 10-camphorsulfonate. Is unsuitable. Preferred are non-onium salt photoacid generators such as compounds defined by (F-1) described in JP-A-2009-269953 and imidosulfonates and oximesulfonates.

  The addition amount of the photoacid generator added as the component (E) in the chemically amplified resist material of the present invention may be any as long as it does not interfere with the effects of the present invention. It is 0 to 40 parts, particularly 0.1 to 40 parts, preferably 0.1 to 20 parts. When the proportion of the photoacid generator as the component (E) is too large, there is a possibility that the resolution is deteriorated or a foreign matter problem occurs during development / resist film peeling. The photoacid generator for the component (E) can be used alone or in admixture of two or more. Furthermore, a photoacid generator having a low transmittance at the exposure wavelength can be used, and the transmittance in the resist film can be controlled by the amount of addition.

In addition, a compound capable of decomposing with an acid to generate an acid (acid-growing compound) may be added to the resist material of the present invention. For these compounds, reference can be made to JP2009-269953A or JP2010-215608A.
The addition amount of the acid multiplication compound in the resist material of the present invention is 2 parts or less, preferably 1 part or less, relative to 100 parts of the base resin in the resist material. When the addition amount is too large, it is difficult to control the diffusion, resulting in degradation of resolution and pattern shape.

  The addition of an organic acid derivative as component (F) and a compound having a weight average molecular weight of 3,000 or less (dissolution inhibitor) whose solubility in an alkali developer is changed by the action of the acid of component (G) is arbitrary. As with the above components, the compounds described in JP2009-269953A or JP2010-215608A can be referred to.

  Similarly to the above components, the base resin of component (C ′) for the negative resist material, the component (H), and the acid crosslinking agent that forms a crosslinked structure by the action of acid are also disclosed in JP-A-2009-269953. Alternatively, compounds described in JP 2010-215608 A can be referred to.

  A surfactant (S) component can be added to the chemically amplified resist material of the present invention, and this is also the (E) definition component described in JP2009-269953A or JP2010-215608A. Can be referred to. JP 2008-122932 A, JP 2010-134012 A, JP 2010-107695 A, JP 2009-276363 A, JP 2009-192784 A, JP 2009-191151 A, JP-A-2009-98638 can also be referred to, and normal surfactants and alkali-soluble surfactants can be used.

  The amount of the polymeric surfactant added is in the range of 0.001 to 20 parts, preferably 0.01 to 10 parts, relative to 100 parts of the base resin of the resist material. These are detailed in Japanese Patent Application Laid-Open No. 2007-297590.

The present invention thirdly provides a pattern forming method using the resist material described above.
In order to form a pattern using the resist material of the present invention, a known lithography technique can be adopted, for example, a substrate for manufacturing an integrated circuit (Si, SiO ₂ , SiN, SiON, TiN, WSi). , BPSG, SOG, organic antireflection film, etc.) or a mask circuit manufacturing substrate (Cr, CrO, CrON, MoSi, etc.) so that the film thickness becomes 0.05 to 2.0 μm by a technique such as spin coating. It is applied and prebaked on a hot plate at 60 to 150 ° C. for 1 to 10 minutes, preferably at 80 to 140 ° C. for 1 to 5 minutes. Next, a mask for forming a target pattern is placed over the resist film, and a high energy beam such as deep ultraviolet light, excimer laser, or X-ray or an electron beam is applied in an exposure amount of 1 to 200 mJ / cm ² , preferably 10 to 100 mJ. Irradiate to / cm ² . Alternatively, an electron beam is directly drawn without using a mask for pattern formation. In addition to a normal exposure method, exposure may be performed by an immersion method (immersion exposure method) in which a mask and a resist film are immersed. In that case, it is possible to use a protective film insoluble in water. Next, post exposure baking (PEB) is performed on a hot plate at 60 to 150 ° C. for 1 to 5 minutes, preferably 80 to 140 ° C. for 1 to 3 minutes. Further, 0.1 to 5% by mass, preferably 2 to 3% by mass of an aqueous developer solution such as tetramethylammonium hydroxide (TMAH) is used for 0.1 to 3 minutes, preferably 0.5 to 2%. The target pattern is formed on the substrate by developing by a conventional method such as a dip method, a paddle method, or a spray method for a minute. The resist material of the present invention is particularly suitable for fine patterning using deep ultraviolet rays of 250 to 190 nm or excimer laser, X-rays and electron beams among high energy rays. Moreover, when the said range remove | deviates from an upper limit or a minimum, the target pattern may be unable to be obtained.

The above-mentioned protective film insoluble in water is used to prevent elution from the resist film and increase the water slidability of the film surface. One type is an organic solvent peeling type that requires peeling before alkali development with an organic solvent that does not dissolve the resist film, and the other type is an alkali that is soluble in an alkali developer and removes the resist film soluble portion and removes the protective film. It is a soluble type.
The latter is based on a polymer compound having a 1,1,1,3,3,3-hexafluoro-2-propanol residue which is insoluble in water and soluble in an alkaline developer, and is an alcohol solvent having 4 or more carbon atoms. , A C8-12 ether solvent, and a material dissolved in a mixed solvent thereof are preferable.
The above-mentioned surfactant that is insoluble in water and soluble in an alkaline developer may be made into a material in which it is dissolved in an alcohol solvent having 4 or more carbon atoms, an ether solvent having 8 to 12 carbon atoms, or a mixed solvent thereof. it can.
Further, as a pattern forming method, after forming the photoresist film, pure water rinsing (post-soak) may be performed to extract an acid generator or the like from the film surface, or to wash away the particles. You may perform the rinse (post-soak) for removing the water which remained on the top.

  EXAMPLES Hereinafter, although a synthesis example, an Example, and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.

[Synthesis Example 1] Synthesis of 4-hydroxynaphthyl-1-tetrahydrothiophenium chloride 1-naphthol 10 g (0.069 mol) and tetramethylene sulfoxide 7.2 g (0.069 mol) were dissolved in methanol 50 g, Cooled to 16 ° C. An excess of hydrogen chloride was fed at a temperature not exceeding 20 ° C. After bubbling nitrogen to expel excess hydrogen chloride gas, the reaction mixture was concentrated, water and diisopropyl ether were added, and the aqueous layer was separated. 4-Hydroxynaphthyl-1-tetrahydrothiophenium chloride aqueous solution was obtained. This was used in the next reaction as an aqueous solution without further isolation.

[Synthesis Example 2] Synthesis of 4-hydroxynaphthyl-1-tetrahydrothiophenium 2- (adamantane-1-carbonyloxy) -1,1,3,3,3-pentafluoropropanesulfonate (PAG-1) 1,1-difluoro-2- (adamantane-1-carbonyloxy) ethanesulfonic acid sodium (corresponding to 0.02 mol) synthesized according to the formulation described in Japanese Patent Application Publication No. 2009-7327 and 4 prepared in Synthesis Example 1 -A hydroxy naphthyl-1-tetrahydrothiophenium chloride aqueous solution (corresponding to 0.03 mol) was mixed and extracted with 200 g of dichloromethane. The organic layer was washed with water, and the solvent was distilled off under reduced pressure to precipitate crystals. The crystal-dichloromethane solution mixture was filtered, washed with diisopropyl ether, and dried to obtain the desired product (6.4 g of white crystals, yield 57%).

The spectrum data of the obtained target product is shown below. The results of nuclear magnetic resonance spectra ( ¹ H-NMR, ¹⁹ F-NMR / DMSO-d ₆ ) are shown in FIG. 1 and FIG. In ¹ H-NMR, a trace amount of residual solvent (diisopropyl ether) is observed.
Infrared absorption spectrum (IR (KBr); cm ⁻¹ )
3085, 2906, 2851, 1738, 1586, 1572, 1518, 1453, 1373, 1355, 1324, 1278, 1219, 1154, 1311, 1103, 1076, 1013, 987, 976, 942, 756, 634

Synthesis Example 3 Synthesis of 1- (2-methoxyethoxy) -naphthalene 1-naphthol 50.0 g (0.0347 mol), 2-methoxyethyl chloride 34.4 g (0.0364 mol), sodium hydroxide 14. 6 g (0.0364 mol) and 2.6 g (0.017 mol) of sodium iodide were dissolved in 100 g of ethanol, and the mixture was heated and stirred at 80 ° C. for 8 hours. After cooling, 100 g of water and 200 g of toluene were added, the organic layer was separated, and washed 5 times with 100 g of a 5 mass% aqueous sodium hydroxide solution. Subsequently, after washing with 100 g of water four times, the organic layer was concentrated to obtain 45 g of an oily substance. This was distilled under reduced pressure (110 ° C./13 Pa) to obtain 41 g of the desired product (yield 58%).

[Synthesis Example 4] Synthesis of 4- (2-methoxyethoxy) naphthalene-1-tetrahydrothiophenium 2- (adamantane-1-carbonyloxy) -1,1-difluoroethanesulfonate (PAG-2) 1 of Synthesis Example 3 8.1 g (0.04 mol) of-(2-methoxyethoxy) -naphthalene is dispersed in 16 g of a diphosphorus pentoxide-methanesulfonic acid solution manufactured by Tokyo Chemical Industry Co., Ltd., and 4.1 g (0.04 mol) of tetramethylene sulfoxide is dispersed. Drop-mixed. The mixture was aged overnight at room temperature, 100 g of water and 30 g of diisopropyl ether were added, and the aqueous layer was separated. The aqueous layer was washed again with 30 g of diisopropyl ether, and sodium 1,1-difluoro-2- (adamantane-1-carbonyloxy) ethanesulfonate synthesized in accordance with the formulation described in JP 2009-7327 A in this aqueous solution Extraction was performed using a dichloromethane-methylisobutyl ketone mixed solvent (equivalent to 0.02 mol). The organic layer was washed with water and the solvent was distilled off under reduced pressure, followed by crystallization with isopropyl ether, filtration and drying to obtain the desired product (9.1 g of white crystals, yield 81%).

The spectrum data of the obtained target product is shown below. The results of nuclear magnetic resonance spectra ( ¹ H-NMR, ¹⁹ F-NMR / DMSO-d ₆ ) are shown in FIG. 3 and FIG. In ¹ H-NMR, a trace amount of residual solvent (diisopropyl ether, methyl isobutyl ketone) is observed.
Infrared absorption spectrum (IR (KBr); cm ⁻¹ )
2906, 2849, 1783, 1508, 1377, 1326, 1262, 1247, 1226, 1209, 1191, 1127, 1087, 965, 943, 829, 755, 637

Synthesis Example 5 4-Hydroxynaphthyl-1-tetrahydrothiophenium 2- (5-oxoadamantane-1-carbonyloxy) -1,1,3,3,3-pentafluoropropanesulfonate (PAG-3) Synthesis Benzyltrimethylammonium 1,1-difluoro-2- (5-oxoadamantane-1-carbonyloxy) ethanesulfonate (0.01 mol) synthesized according to the formulation described in JP-A-2009-7327 and synthesis example The 4-hydroxynaphthyl-1-tetrahydrothiophenium chloride aqueous solution (equivalent to 0.02 mol) prepared in 1 was mixed and extracted with 100 g of dichloromethane. The organic layer was washed with water, and the solvent was distilled off under reduced pressure to precipitate crystals. The crystal-dichloromethane solution mixture was filtered, washed with methyl isobutyl ketone and diisopropyl ether, and then dried to obtain the desired product (2.5 g of white crystals, yield 41%).

The spectrum data of the obtained target product is shown below. The results of nuclear magnetic resonance spectra ( ¹ H-NMR, ¹⁹ F-NMR / DMSO-d ₆ ) are shown in FIGS. In ¹ H-NMR, residual solvents (dichloromethane, methyl isobutyl ketone, diisopropyl ether) are observed. In the resist evaluation to be described later, the evaluation was performed with the addition amount in terms of purity with a purity of 93.3 wt%.
Infrared absorption spectrum (IR (KBr); cm ⁻¹ )
3071, 2935, 1716, 1571, 1370, 1352, 1279, 1230, 1209, 1082, 1061, 1014, 983, 945, 824, 761, 639

Synthesis Example 6 Synthesis of 4- (2-methoxyethoxy) naphthalene-1-tetrahydrothiophenium 2- (4- (dehydrocholyloxy) butanoyloxy) -1,1-difluoroethanesulfonate (PAG-4) Synthesis In the same manner as in Example 4, an aqueous 4- (2-methoxyethoxy) naphthalene-1-tetrahydrothiophenium solution (corresponding to 0.01 mol) was prepared. To this, benzyltrimethylammonium = 2- (4- (dehydrocholyloxy) butanoyloxy) -1,1-difluoroethanesulfonate (corresponding to 0.008 mol) synthesized according to the formulation described in JP2009-7327A Extraction was performed using 50 g of dichloromethane. The organic layer was washed with water, the solvent was distilled off under reduced pressure, and the residue was purified using silica gel column chromatography (eluent dichloromethane-methanol). The purified product was dissolved in dichloromethane-methylisobutylketone solution, washed with water, the solvent was distilled off under reduced pressure, crystallized by adding isopropyl ether, filtered and dried to obtain the desired product (4.3 g of white crystals). , 66% yield).

The spectrum data of the obtained target product is shown below. The results of nuclear magnetic resonance spectra ( ¹ H-NMR, ¹⁹ F-NMR / DMSO-d ₆ ) are shown in FIG. 7 and FIG. In ¹ H-NMR, a trace amount of residual solvent (diisopropyl ether, methyl isobutyl ketone) is observed.
Infrared absorption spectrum (IR (KBr); cm ⁻¹ )
2965, 1721, 1704, 1588, 1571, 1509, 1427, 1384, 1321, 1250, 1235, 1160, 1130, 1088, 1031, 989, 950, 764, 644

The polymer compound used for the resist material of the present invention was synthesized according to the following formulation.
Synthesis Example 7 Synthesis of Polymer 1 50.6 g of methacrylic acid = 1- (1-methylethyl) cyclopentyl and 23.1 g of methacrylic acid = 2-oxo-4-oxahexahydro-3 were added to a flask in a nitrogen atmosphere. , 5-methano-2H-cyclopenta [b] furan-6-yl, 26.3 g 2-oxotetrahydrofuran-3-yl methacrylate, 1.19 g V-601 (manufactured by Wako Pure Chemical Industries, Ltd.), 1.51 g of 2-mercaptoethanol and 175 g of PMA (propylene glycol methyl ether acetate) were taken to prepare a monomer-polymerization initiator solution. In another flask in a nitrogen atmosphere, 58.3 g of PMA (propylene glycol methyl ether acetate) was taken, heated to 80 ° C. with stirring, and then the monomer-polymerization initiator solution was added dropwise over 4 hours. After completion of dropping, stirring was continued for 2 hours while maintaining the temperature of the polymerization solution at 80 ° C., and then cooled to room temperature. The obtained polymerization solution was dropped into 1.6 kg of methanol which was vigorously stirred, and the precipitated copolymer was separated by filtration. The copolymer was washed twice with 0.6 kg of methanol and then vacuum dried at 50 ° C. for 20 hours to obtain 83.3 g of a white powdery copolymer. When the copolymer was analyzed by ¹³ C-NMR, the copolymer composition ratio was 46.4 / 22.2 / 31.4 mol% in the order of the above monomers. When analyzed by GPC (solvent: tetrahydrofuran), the polystyrene-reduced weight average molecular weight (Mw) was 6,100.

[Examples 1 to 6 and Comparative Examples 1 to 4]
The photoacid generator and polymer 1 shown in the above synthesis example were used as a base resin, and a quencher having the composition shown in Table 1 was dissolved in a solvent containing 0.01% by mass of the following surfactant A (Omnova). Then, a resist material was prepared, and the resist material was further filtered through a 0.2 μm Teflon (registered trademark) filter to prepare resist solutions.

界面活性剤Ａ：
３−メチル−３−（２，２，２−トリフルオロエトキシメチル）オキセタン・テトラヒドロフラン・２，２−ジメチル−１，３−プロパンジオール共重合物（オムノバ社製）（構造式を以下に示す。）

In Table 1, the solvent, quencher, photoacid generator and alkali-soluble surfactant (SF) used in the comparative examples are as follows.
P-01: Polymer 1
PAG-1, PAG-2, PAG-3, PAG-4: As described above PGMEA: propylene glycol monomethyl ether acetate CyHO: cyclohexanone GBL: γ-butyrolactone BASE-1: N-tBOCated 2-phenylbenzimidazole PAG-X :
Triphenylsulfonium 2- (adamantane-1-carbonyloxy) -1,1-difluoroethanesulfonate PAG-Y:
4-Butoxynaphthyl-1-tetrahydrothiophenium 2- (adamantane-1-carbonyloxy) -1,1-difluoroethanesulfonate PAG-Z1:
4- (2-methoxyethoxy) naphthyl-1-tetrahydrothiophenium trifluoromethanesulfonate PAG-Z2:
4-Hydroxynaphthyl-1-tetrahydrothiophenium nonafluoro-1-butanesulfonate SF-1:
The following polymer 11 (compound described in JP-A-2008-122932)
Poly (methacrylic acid = 3,3,3-trifluoro-2-hydroxy-1,1-dimethyl-2-trifluoromethylpropyl methacrylic acid = 1,1,1-trifluoro-2-hydroxy-6-methyl -2-Trifluoromethylhept-4-yl)
Weight average molecular weight (Mw) = 7,300, dispersity (Mw / Mn) = 1.86

Surfactant A:
3-methyl-3- (2,2,2-trifluoroethoxymethyl) oxetane / tetrahydrofuran / 2,2-dimethyl-1,3-propanediol copolymer (Omnova Co., Ltd.) (Structural formula is shown below. )

Evaluation of resolution and dark pattern profile of resist material: An antireflection film solution (ARC-29A, manufactured by Nissan Chemical Industries, Ltd.) was applied on an ArF exposed silicon substrate and baked at 200 ° C. for 60 seconds. A resist solution was spin-coated on an antireflection film (100 nm film thickness) substrate and baked at 100 ° C. for 60 seconds using a hot plate to prepare a resist film with a film thickness of 120 nm. This was subjected to immersion exposure with water using an ArF excimer laser scanner (Nikon Corporation, NSR-S610C, NA = 1.30, double pole, Cr mask), and baked (PEB) at 80 ° C. for 60 seconds. And developed with an aqueous solution of 2.38 mass% tetramethylammonium hydroxide for 60 seconds.

In the evaluation of the resist material, the exposure amount for resolving the 40 nm group line and space at 1: 1 was determined as the optimum exposure amount (Eop, mJ / cm ² ). A dark area line and space pattern was used for this evaluation (10 lines and space patterns are shielded from light by a bulk pattern). The pattern shapes in the dark area and the bright area at the optimum exposure amount (the transmission area of the wide space portion on both sides of the 10 line and space patterns) were observed with an electron microscope and evaluated.
The evaluation criteria for the dark area pattern shape were as follows.
Rectangle:
The line side wall is vertical, and there is little change in dimensions from the bottom (near the substrate) to the top.
taper:
The line side wall is inclined, and the dimensions gradually decrease from the bottom to the top.
T Top:
Unsuitable due to large dimensions near the line top.
Top rounding:
The area near the line top is rounded and the dimensions are reduced, making it unsuitable.
Further, the line width of the line and space pattern in the bright area in the above Eop was measured and set to Dark / Bright bias. A smaller numerical value indicates a smaller dimensional difference between the dark area and the bright area.
Table 2 shows the evaluation results of each resist material.

From the results in Table 2, the resist material of the present invention functions sufficiently as a photoacid generator compared to existing photoacid generators, and the pattern shape of the dark area is good, and the dimensional difference between the dark area and the bright area is small. It was confirmed.
As described above, the resist material using the photoacid generator of the present invention is excellent in resolution, particularly in the line and space pattern shape in the dark part.

Claims (6)

A sulfonium salt represented by the following general formula (1a) or (1b).

(In the formula, R represents a linear, branched or cyclic monovalent hydrocarbon group having 7 to 30 carbon atoms which may contain a hetero atom, and n represents an integer of 1 to 4.)   The sulfonium salt represented by the formula (1b) according to claim 1, wherein n is 1.   A chemically amplified resist material comprising the sulfonium salt according to claim 1.   A chemically amplified positive resist material comprising the sulfonium salt according to claim 1.   A step of applying the resist material according to claim 3 or 4 on a substrate, a step of exposing to high energy rays through a photomask after heat treatment, and heat treatment as necessary, followed by development using a developer. The pattern formation method characterized by including the process to perform.   A step of applying the resist material according to claim 3 or 4 on a substrate, a step of applying a protective film insoluble in water and soluble in an alkaline developer after heat treatment, and water between the substrate and the projection lens. A pattern forming method comprising: a step of exposing with a high energy beam through a photomask; and a step of developing with a developer after heat treatment as necessary.

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