Negative resist material and pattern forming method

Abstract

To provide a negative resist material for organic solvent development having high resolution and improved LWR and CDU, and a patterning method using the same.SOLUTION: A negative resist material comprises: a base polymer; and an acid generator, which is a sulfonium salt, comprising a sulfonic acid anion having a maleimide group and a cation having a polymerizable double bond.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a negative resist material and a patterning method.

Background Art

[0002] With the increasing integration density and speed of LSIs, the miniaturization of pattern rules has been rapidly progressing. This is because the high-speed communication of 5G and the spread of artificial intelligence (AI) are advancing, and high-performance devices for processing them are required. As the most advanced miniaturization technology, mass production of 5nm node devices by extreme ultraviolet (EUV) lithography with a wavelength of 13.5nm is being carried out. Furthermore, studies using EUV lithography are also underway for next-generation 3nm node and next-next-generation 2nm node devices.

[0003] As miniaturization progresses, image blur due to acid diffusion has become a problem. In order to ensure the resolution of fine patterns with a dimensional size of 45nm or less, it has been proposed that not only the improvement of the dissolution contrast conventionally proposed but also the control of acid diffusion is important (Non-Patent Document 1). However, since chemically amplified resist materials increase sensitivity and contrast by acid diffusion, if the post-exposure bake (PEB) temperature is lowered or the time is shortened to suppress acid diffusion to the limit, the sensitivity and contrast will be significantly reduced.

[0004] When forming a pattern with a pitch narrower than the wavelength, it is effective to use interference lithography. In particular, due to the interference of light with high contrast between the lines in the X direction and the lines in the Y direction, high-contrast black dots are generated. By combining this with a negative resist material, a hole pattern with large dimensional uniformity (CDU) can be formed (Non-Patent Document 2). Non-Patent Document 2 uses a negative resist material that uses a crosslinking agent in which polymers react with an acid. Such a chemically amplified negative resist material has problems of image blur due to the acid diffusion described above, swelling occurs due to the developer penetrating between the partially crosslinked polymers, and problems of pattern collapse, deterioration of CDU, and edge roughness (LWR) due to this.

[0005] Here, the production of a negative pattern by organic solvent development is a method that has been used for a long time. For a cyclized rubber-based resist material, xylene or the like is used as a developer, and for an initial chemically amplified resist material based on poly-tert-butoxycarbonyloxystyrene, anisole was used as a developer to obtain a negative pattern (Non-Patent Document 3).

[0006] Using a chemically amplified resist material having a polymethacrylate with a carboxy group substituted with an acid-labile group as a base polymer, a negative pattern can be formed by exposure with ArF excimer laser light and organic solvent development (Patent Document 1). This organic solvent development process is used in device manufacturing after the 20 nm node in combination with immersion lithography or double patterning using an optical system with an NA exceeding 1.

[0007] In EUV lithography, a pattern with a pitch below the exposure wavelength is not formed. This is because the NA of EUV exposure is 0.33, which is significantly smaller than 1.35 of ArF immersion exposure, and the effect of interference lithography is small. The next NA of EUV lithography is 0.55, but even in this generation, the negative resist material is not advantageous in forming a hole pattern.

[0008] In EUV lithography, a negative pattern is required when forming isolated patterns or pillar patterns. In this case, since the proportion of the light-blocking part of the mask is high, there is an advantage that it is less affected by defects in the mask blanks.

[0009] Also, when forming isolated patterns or pillar patterns on a photomask, a negative resist material is preferably used. This is because when using a negative resist material, the drawing area is smaller, so the drawing time can be shortened, resulting in improved throughput. For this reason, high resolution is also required for the resist material for electron beam (EB) lithography for mask pattern formation.

[0010] Organic solvent development has less swelling compared to alkaline aqueous solution development, and thus may be excellent in CDU and LWR. However, since the dissolution contrast is lower than that of alkaline aqueous solution development, it has a problem of low resolution. When a crosslinking agent that reacts with an acid is added to the resist material to increase the dissolution contrast of organic solvent development, the above-mentioned swelling problem also occurs in organic solvent development. It is necessary to improve the dissolution contrast without swelling.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Non-Patent Documents

[0012]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0013] It is desired to develop a negative resist material compatible with an organic solvent process that can reduce LWR of a line pattern and CDU of a hole pattern and has high resolution. For this purpose, it is necessary to have characteristics of low swelling and high contrast during organic solvent development.

[0014] The present invention has been made in view of the above circumstances, and an object thereof is to provide a negative resist material for organic solvent development having high resolution and improved LWR and CDU, and a pattern forming method using the same.

Means for Solving the Problems

[0015] As a result of intensive studies to achieve the above object, the present inventor has found that a resist material containing a base polymer and an acid generator which is a sulfonium salt composed of a sulfonic acid anion having a maleimide group and a cation having a polymerizable double bond has a high effect of suppressing acid diffusion by crosslinking the sulfonium salt upon exposure, and the solubility in an organic solvent decreases and the dissolution contrast improves, thereby improving LWR and CDU, having excellent resolution, and widening the process margin, and completed the present invention.

[0016] That is, the present invention provides the following negative resist material and pattern forming method. 1. A negative resist material containing a base polymer and an acid generator which is a sulfonium salt composed of a sulfonic acid anion having a maleimide group and a cation having a polymerizable double bond. 2. The negative resist material of 1, wherein the sulfonium salt composed of a sulfonic acid anion having a maleimide group and a cation having a polymerizable double bond is represented by the following formula (A).

Chemical Formula

Chemical formula

Advantages of the Invention

[0017] The resist material containing the base polymer and the sulfonium salt composed of a sulfonic acid anion having a maleimide group and a cation having a polymerizable double bond undergoes a crosslinking reaction upon exposure, resulting in low acid diffusion, and the crosslinking reaction promotes insolubilization in the developer. By these means, it becomes possible to construct a resist material with high resolution and improved LWR and CDU.

Embodiments for Carrying Out the Invention

[0018] [Negative resist material] The negative resist material of the present invention contains a base polymer and an acid generator which is a sulfonium salt composed of a sulfonate anion having a maleimide group and a cation having a polymerizable double bond.

[0019] [A sulfonium salt composed of a sulfonate anion having a maleimide group and a cation having a polymerizable double bond] The sulfonium salt composed of the sulfonate anion having a maleimide group and the cation having a polymerizable double bond functions as an acid generator, and those represented by the following formula (A) are preferred. [Chemical formula]

[0020] In formula (A), m is an integer of 1 to 3, and n is an integer of 0 to 2. However, m + n = 3. p is 1 or 2, and q is an integer of 0 to 4. However, 1 ≤ p + q ≤ 5. r is an integer of 0 to 5.

[0021] In formula (A), X 1 is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms. The hydrocarbylene group may contain an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom.

[0022] X 1The hydrocarbylene group having 1 to 20 carbon atoms represented by may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include alkanediyl groups having 1 to 20 carbon atoms such as methanediyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,2-diyl 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; cyclic saturated hydrocarbylene groups having 3 to 20 carbon atoms such as cyclopentanediyl group, cyclohexanediyl group, norbornanediyl group, adamantanediyl group; unsaturated aliphatic hydrocarbylene groups having 2 to 20 carbon atoms such as vinylene group, propene-1,3-diyl group; arylene groups having 6 to 20 carbon atoms such as phenylene group, naphthylene group; groups obtained by combining these, and the like. Further, some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and a part of -CH 2 - of the hydrocarbylene group may be substituted with a group containing an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, it may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, 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 (-C(=O)-O-C(=O)-), a haloalkyl group, and the like.

[0023] In formula (A), X 2 is an ester bond or an alkanediyl group having 1 to 8 carbon atoms. Examples of the alkanediyl group include those having 1 to 8 carbon atoms among the alkanediyl groups exemplified as the hydrocarbylene group having 1 to 20 carbon atoms represented by X 1 .

[0024] In formula (A), X 3is a single bond, an ester bond, an ether bond, an amide bond, a urethane bond or an alkanediyl group having 1 to 10 carbon atoms, and -CH of the alkanediyl group 2 - may be partially substituted with an ester bond, an ether bond, an amide bond or a urethane bond. Examples of the alkanediyl group include a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a nonane-1,9-diyl group, a decane-1,10-diyl group, and the like.

[0025] In formula (A), R 1 and R 2 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. The saturated hydrocarbyl group may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 10 carbon atoms such as 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 nonyl group, a decyl group; and cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms such as a cyclopentyl group and a cyclohexyl group. Further, R 1 and R 2 may be bonded to each other to form a ring together with the carbon atom to which they are bonded. At this time, the ring formed is preferably a 5-membered ring or a 6-membered ring.

[0026] In formula (A), R 3 ~R 5 are each independently a hydrogen atom, a halogen atom or a saturated hydrocarbyl group having 1 to 40 carbon atoms, and a part or all of the hydrogen atoms of the saturated hydrocarbyl group may be substituted with a fluorine atom or a hydroxy group, and -CH of the saturated hydrocarbyl group 2 - may be partially substituted with an ether bond or an ester bond, and a part of the carbon-carbon bonds of the saturated hydrocarbyl group may be a double bond.

[0027] R 3 ~R 5 The saturated hydrocarbyl group having 1 to 40 carbon atoms represented by may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 40 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, 2-ethylhexyl group, nonyl group, decyl group, undecyl group, tridecyl group, pentadecyl group, heptadecyl group, icosanyl group, etc.; and cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms such as cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-adamantyl group, 1-adamantylmethyl group, norbornyl group, norbornylmethyl group, tricyclodecanyl group, tetracyclododecanyl group, tetracyclododecanylmethyl group, dicyclohexylmethyl group, etc.

[0028] In formula (A), R 6 and R 7 are each independently a halogen atom, a cyano group, a nitro group, a mercapto group, a sulfo group, a saturated hydrocarbyl group having 1 to 10 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, and the saturated hydrocarbyl group and the aralkyl group may contain an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom. Further, two R 6 or two R 7 may be bonded to each other to form a ring together with the benzene ring to which they are bonded, and R 6 and R 7 may be bonded to each other to form a ring together with the benzene ring to which they are bonded and the sulfur atom therebetween. At this time, as the ring, those having the following structures are preferable. However, substituents on the aromatic ring are shown with omission.

Chemical formula

[0029] In formula (A), Rf 1 ~Rf 4is independently a hydrogen atom, a fluorine atom or a trifluoromethyl group, provided that at least one of these is a fluorine atom or a trifluoromethyl group. Also, Rf 1 and Rf 2 may combine to form a carbonyl group.

[0030] Examples of the sulfonate anion having a maleimide group include, but are not limited to, the following. [Chemical formula]

[0031] [Chemical formula]

[0032] [Chemical formula]

[0033] [Chemical formula]

[0034] [Chemical formula]

[0035] [Chemical formula]

[0036] [Chemical formula]

[0037] [Chemical formula]

[0038] [Chemical formula]

[0039]

Chem.

[0040]

Chem.

[0041]

Chem.

[0042]

Chem.

[0043]

Chem.

[0044]

Chem.

[0045]

Chem.

[0046]

Chem.

[0047]

Chem.

[0048]

Chem.

[0049] [Chemistry]

[0050] [Chemistry]

[0051] [Chemistry]

[0052] [Chemistry]

[0053] [Chemistry]

[0054] [Chemistry]

[0055] Examples of the sulfonium cation having a polymerizable double bond of the sulfonium salt represented by formula (A) include, but are not limited to, those shown below. [Chemistry]

[0056] [Chemistry]

[0057] [Chemistry]

[0058] [Chemistry]

[0059]

Chem.

[0060]

Chem.

[0061]

Chem.

[0062]

Chem.

[0063]

Chem.

[0064]

Chem.

[0065]

Chem.

[0066]

Chem.

[0067] As a method for synthesizing the sulfonium salt represented by formula (A), there may be mentioned a method of ion-exchanging a fluorosulfonic acid that gives the anion and a sulfonium salt that is a weaker acid than the fluorosulfonic acid and contains the sulfonium cation. Examples of the weak acid include carbonic acid and halogen. Further, it can also be synthesized by ion-exchanging a sodium salt or ammonium salt of the fluorosulfonic acid that gives the anion and a sulfonium chloride containing the sulfonium cation.

[0068] In the negative resist material of the present invention, the content of the acid generator which is a sulfonium salt represented by formula (A) is preferably 0.01 to 1,000 parts by mass, more preferably 0.05 to 500 parts by mass, based on 100 parts by mass of the base polymer described later, from the viewpoints of sensitivity and acid diffusion suppressing effect.

[0069] [Base Polymer] The base polymer contained in the negative resist material of the present invention preferably contains a repeating unit represented by the following formula (a1) (hereinafter also referred to as repeating unit a1). [Chemical formula]

[0070] In formula (a1), R A is a hydrogen atom or a methyl group. Y 1 is a single bond, a phenylene group or a naphthylene group, or a linking group having 1 to 12 carbon atoms containing at least one selected from an ester bond, an ether bond and a lactone ring. R 11 is an acid-labile group.

[0071] Examples of the monomer that gives the repeating unit a1 include, but are not limited to, the following. In the following formula, R A and R 11 are the same as described above. [Chemical formula]

[0072] The base polymer may contain a repeating unit represented by the following formula (a2) (hereinafter, also referred to as repeating unit a2).

Chemical formula

[0073] In formula (a2), R A is a hydrogen atom or a methyl group. Y 2 is a single bond or an ester bond. Y 3 is a single bond, an ether bond or an ester bond. R 12 is an acid-labile group. R 13 is a fluorine atom, a trifluoromethyl group, a cyano group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 7 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 7 carbon atoms or a saturated hydrocarbyloxycarbonyl group having 2 to 7 carbon atoms. R 14 is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and a part of the carbon atoms thereof may be substituted with an ether bond or an ester bond. a is 1 or 2. b is an integer of 0 to 4.

[0074] Examples of the monomer that gives the repeating unit a2 include, but are not limited to, those shown below. In the following formula, R A and R 12 are the same as those described above.

Chemical formula

[0075] Examples of the acid-labile group represented by R 11 and R 12 in the repeating units a1 and a2 include, for example, those described in JP-A-2013-80033 and JP-A-2013-83821.

[0076] Typically, examples of the acid-labile group include those represented by the following formulas (AL-1) to (AL-3). [Chemical formula] (In the formula, the broken line represents a bond.)

[0077] In formulas (AL-1) and (AL-2), R L1 and R L2 are each independently a hydrocarbyl group having 1 to 40 carbon atoms, and may contain heteroatoms such as an oxygen atom, a sulfur atom, a nitrogen atom, and a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. As the hydrocarbyl group, a saturated hydrocarbyl group having 1 to 40 carbon atoms is preferable, and a saturated hydrocarbyl group having 1 to 20 carbon atoms is more preferable.

[0078] In formula (AL-1), c is an integer of 0 to 10, and an integer of 1 to 5 is preferable.

[0079] In formula (AL-2), R L3 and R L4 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and may contain heteroatoms such as an oxygen atom, a sulfur atom, a nitrogen atom, and a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. As the hydrocarbyl group, a saturated hydrocarbyl group having 1 to 20 carbon atoms is preferable. Further, any two of R L2 , R L3 and R L4 may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom to which they are bonded or a carbon atom and an oxygen atom. As the ring, a ring having 4 to 16 carbon atoms is preferable, and an alicyclic ring is particularly preferable.

[0080] In formula (AL-3), R L5 , R L6 and R L7is, independently of each other, a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms such as oxygen atom, sulfur atom, nitrogen atom, fluorine atom, etc. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched or cyclic. As the hydrocarbyl group, a saturated hydrocarbyl group having 1 to 20 carbon atoms is preferred. Also, R L5 , R L6 and R L7 any two of them may combine with each other to form a ring having 3 to 20 carbon atoms together with the carbon atoms to which they are attached. As the ring, a ring having 4 to 16 carbon atoms is preferred, and an alicyclic ring is particularly preferred.

[0081] The base polymer may further contain a repeating unit b containing a phenolic hydroxy group as an adhesion group. Examples of the monomer that gives the repeating unit b include, but are not limited to, the following. In the following formula, R A is the same as described above.

Chemical formula

[0082] The base polymer may further contain a repeating unit c containing a hydroxy group other than a phenolic hydroxy group, a lactone ring, a sultone ring, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonyl group, a sulfonyl group, a cyano group or a carboxy group as another adhesion group. Examples of the monomer that gives the repeating unit c include, but are not limited to, the following. In the following formula, R A is the same as described above.

Chemical formula

[0083]

Chemical formula

[0084]

Chemical formula

[0085]

Chem.

[0086]

Chem.

[0087]

Chem.

[0088]

Chem.

[0089]

Chem.

[0090]

Chem.

[0091]

Chem.

[0092] The base polymer may further include a repeating unit d derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene, or derivatives thereof. Examples of the monomer that gives the repeating unit d include, but are not limited to, the following.

Chem.

[0093] The base polymer may further contain a repeating unit e derived from styrene, vinylnaphthalene, vinylanthracene, vinylpyrene, methylene indane, vinylpyridine or vinylcarbazole.

[0094] The base polymer for a negative resist material for organic solvent development essentially contains a repeating unit a1 containing an acid-labile group. In this case, the content ratios of the repeating units a1, a2, b, c, d and e are preferably 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, more preferably 0.1 ≤ 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 still more preferably 0.2 ≤ a1 ≤ 0.8, 0 ≤ a2 ≤ 0.8, 0.2 ≤ a1 + a2 ≤ 0.8, 0 ≤ b ≤ 0.75, 0 ≤ c ≤ 0.75, 0 ≤ d ≤ 0.6, 0 ≤ e ≤ 0.6. Also, a1 + a2 + b + c + d + e = 1.0.

[0095] To synthesize the base polymer, for example, a monomer that gives the above-described repeating unit may be heated in an organic solvent with a radical polymerization initiator added thereto to perform polymerization.

[0096] Examples of the organic solvent used during polymerization include toluene, benzene, tetrahydrofuran (THF), diethyl ether, dioxane and the like. Examples of the polymerization initiator include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, lauroyl peroxide and the like. The temperature during polymerization is preferably 50 to 80°C. The reaction time is preferably 2 to 100 hours, more preferably 5 to 20 hours.

[0097] When copolymerizing a monomer containing a hydroxy group, the hydroxy group may be replaced with an acetal group that can be easily deprotected by an acid such as an ethoxyethoxy group during polymerization, and then deprotected with a weak acid and water after polymerization, or may be replaced with an acetyl group, a formyl group, a pivaloyl group, etc., and then subjected to alkaline hydrolysis after polymerization.

[0098] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, instead of hydroxystyrene or hydroxyvinylnaphthalene, acetoxystyrene or acetoxyvinylnaphthalene may be used, and after polymerization, the acetoxy group may be deprotected by the above-mentioned alkaline hydrolysis to form hydroxystyrene units or hydroxyvinylnaphthalene units.

[0099] As the base for alkaline hydrolysis, aqueous ammonia, triethylamine, etc. can be used. Also, the reaction temperature is preferably -20 to 100°C, more preferably 0 to 60°C. The reaction time is preferably 0.2 to 100 hours, more preferably 0.5 to 20 hours.

[0100] The base polymer preferably has a polystyrene-equivalent weight average molecular weight (Mw) of 1,000 to 500,000, more preferably 2,000 to 30,000, as determined by gel permeation chromatography (GPC) using THF as a solvent. If Mw is within the above range, the heat resistance of the resist film and its solubility in an organic solvent developer are good.

[0101] Also, when the molecular weight distribution (Mw / Mn) of the base polymer is broad, there are low molecular weight and high molecular weight polymers, so there is a risk that foreign matter may be seen on the pattern or the pattern shape may deteriorate after exposure. As the pattern rules become finer, the influence of Mw and Mw / Mn tends to increase. Therefore, in order to obtain a resist material suitably used for fine pattern dimensions, the Mw / Mn of the base polymer is preferably narrowly dispersed at 1.0 to 2.0, particularly 1.0 to 1.5.

[0102] The base polymer may include two or more polymers having different composition ratios, Mw, and Mw / Mn.

[0103] [Organic solvent] The negative resist material of the present invention may contain an organic solvent. The organic solvent is not particularly limited as long as it can dissolve each of the above-described components and each of the components described below. Examples of the organic solvent include ketones such as cyclohexanone, cyclopentanone, methyl-2-n-pentyl ketone, and 2-heptanone, 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, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether, esters such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol monotert-butyl ether acetate, and lactones such as γ-butyrolactone, as described in paragraphs

[0144] to

[0145] of JP-A-2008-111103.

[0104] In the negative resist material of the present invention, the content of the organic solvent is preferably 100 to 10,000 parts by mass, more preferably 200 to 8,000 parts by mass, per 100 parts by mass of the base polymer. The organic solvent may be used alone or in combination of two or more.

[0105] [Quencher] The negative resist material of the present invention may contain a quencher. The quencher means a compound that can prevent the diffusion to the unexposed portion by trapping the acid generated from the acid generator in the resist material.

[0106] Examples of the quencher include conventional basic compounds. Examples of the conventional basic compounds include primary, secondary, and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxy group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxy group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amides, imides, carbamates, and the like. In particular, the primary, secondary, and tertiary amine compounds described in paragraphs

[0146] to

[0164] of JP-A-2008-111103, particularly amine compounds having a hydroxy group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonic acid ester bond, and compounds having a carbamate group described in Japanese Patent No. 3,790,649 are preferable. By adding such a basic compound, for example, the acid diffusion rate in the resist film can be further suppressed or the shape can be corrected.

[0107] Examples of the quencher also include onium salts such as sulfonic acids, carboxylic acids, or sulfonium salts, iodonium salts, and ammonium salts of fluorinated alkoxides in which the α-position is not fluorinated. Sulfonic acids, imidic acids, or methidic acids in which the α-position is fluorinated are necessary for deprotecting the acid-labile groups of carboxylic acid esters, but sulfonic acids, carboxylic acids, or fluorinated alcohols in which the α-position is not fluorinated are released by salt exchange with the onium salts. Since sulfonic acids, carboxylic acids, and fluorinated alcohols in which the α-position is not fluorinated do not cause a deprotection reaction, they function as quenchers.

[0108] Examples of such quenchers include, for example, a compound represented by the following formula (B) (onium salt of a sulfonic acid in which the α-position is not fluorinated), a compound represented by the following formula (C) (onium salt of a carboxylic acid), and a compound represented by the following formula (D) (onium salt of an alkoxide). [Chemical formula]

[0109] In formula (B), R 101 is a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a hetero atom, provided that the hydrogen atom bonded to the carbon atom at the α-position of the sulfo group is excluded from those substituted with a fluorine atom or a fluoroalkyl group.

[0110] The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 40 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, tert-pentyl group, n-pentyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, etc.; cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms such as cyclopentyl group, cyclohexyl group, cyclopentylmethyl group, cyclopentylethyl group, cyclopentylbutyl group, cyclohexylmethyl group, cyclohexylethyl group, cyclohexylbutyl group, norbornyl group, tricyclo[5.2.1.0 2,6 decanyl group, adamantyl group, adamantylmethyl group, etc.; alkenyl groups having 2 to 40 carbon atoms such as vinyl group, allyl group, propenyl group, butenyl group, hexenyl group, etc.; cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 40 carbon atoms such as cyclohexenyl group, etc.; aryl groups having 6 to 40 carbon atoms such as phenyl group, naphthyl group, alkylphenyl group (2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butylphenyl group, 4-n-butylphenyl group, etc.), dialkylphenyl group (2,4-dimethylphenyl group, 2,4,6-triisopropylphenyl group, etc.), alkylnaphthyl group (methylnaphthyl group, ethylnaphthyl group, etc.), dialkylnaphthyl group (dimethylnaphthyl group, diethylnaphthyl group, etc.), etc.; aralkyl groups having 7 to 40 carbon atoms such as benzyl group, 1-phenylethyl group, 2-phenylethyl group, etc.

[0111] Further, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and a part of -CH 2 - of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, it may contain a hydroxy group, a cyano group, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc. Examples of the hydrocarbyl group containing a heteroatom include heteroaryl groups such as a thienyl group; alkoxyphenyl groups such as a 4-hydroxyphenyl group, a 4-methoxyphenyl group, a 3-methoxyphenyl group, a 2-methoxyphenyl group, a 4-ethoxyphenyl group, a 4-tert-butoxyphenyl group, and a 3-tert-butoxyphenyl group; alkoxynaphthyl groups such as a methoxynaphthyl group, an ethoxynaphthyl group, an n-propoxynaphthyl group, and an n-butoxynaphthyl group; dialkoxynaphthyl groups such as a dimethoxynaphthyl group and a diethoxynaphthyl group; aryl oxoalkyl groups such as a 2-aryl-2-oxoethyl group such as a 2-phenyl-2-oxoethyl group, a 2-(1-naphthyl)-2-oxoethyl group, and a 2-(2-naphthyl)-2-oxoethyl group, etc.

[0112] In formula (C), R 102 is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. Examples of the hydrocarbyl group represented by R 102 are the same as those exemplified as the hydrocarbyl group represented by R 101 In addition, as other specific examples, fluorine-containing alkyl groups such as a trifluoromethyl group, a trifluoroethyl group, a 2,2,2-trifluoro-1-methyl-1-hydroxyethyl group, and a 2,2,2-trifluoro-1-(trifluoromethyl)-1-hydroxyethyl group; fluorine-containing aryl groups such as a pentafluorophenyl group and a 4-trifluoromethylphenyl group, etc. are also included.

[0113] In formula (D), R 103is a saturated hydrocarbyl group having 1 to 8 carbon atoms and at least 3 fluorine atoms or an aryl group having 6 to 10 carbon atoms and at least 3 fluorine atoms, and the saturated hydrocarbyl group and the aryl group may contain a nitro group.

[0114] In formulas (B), (C) and (D), Mq + is an onium cation. As the onium cation, a sulfonium cation represented by the following formula (B-1), an iodonium cation represented by the following formula (C-1) or an ammonium cation represented by the following formula (D-1) is preferable.

Chemical formula

[0115] In formulas (B-1), (C-1) and (D-1), R 111 ~R 119 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. Further, R 111 and R 112 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded, and R 116 and R 117 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded.

[0116] R 111 ~R 119The hydrocarbyl group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, n-octyl group, n-nonyl group, n-decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group; cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms such as cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclopropylmethyl group, 4-methylcyclohexyl group, cyclohexylmethyl group, norbornyl group, adamantyl group; alkenyl groups having 2 to 20 carbon atoms such as vinyl group, propenyl group, butenyl group, hexenyl group; cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 20 carbon atoms such as cyclohexenyl group, norbornenyl group; alkynyl groups having 2 to 20 carbon atoms such as ethynyl group, propynyl group, butynyl group; aryl groups having 6 to 20 carbon atoms such as phenyl group, methylphenyl group, ethylphenyl group, n-propylphenyl group, isopropylphenyl group, n-butylphenyl group, isobutylphenyl group, sec-butylphenyl group, tert-butylphenyl group, naphthyl group, methylnaphthyl group, ethylnaphthyl group, n-propylnaphthyl group, isopropylnaphthyl group, n-butylnaphthyl group, isobutylnaphthyl group, sec-butylnaphthyl group, tert-butylnaphthyl group; aralkyl groups having 7 to 20 carbon atoms such as benzyl group, phenethyl group; groups obtained by combining these, and the like. Further, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and a part of -CH 2 - of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, it may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro 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 (-C(=O)-O-C(=O)-), a haloalkyl group, and the like.

[0117] Also, Mq + As the onium cation represented by Mq, the sulfonium cation of the sulfonium salt represented by formula (A) can also be preferably used.

[0118] As another example of the quencher, a polymer-type quencher described in JP-A-2008-239918 can be mentioned. This enhances the rectangularity of the resist pattern by aligning on the resist film surface. The polymer-type quencher also has the effect of preventing film loss of the pattern and rounding of the pattern top when a protective film for immersion exposure is applied.

[0119] When the negative resist material of the present invention contains the quencher, its content is preferably 0 to 5 parts by mass, more preferably 0 to 4 parts by mass, based on 100 parts by mass of the base polymer. The quencher may be used alone or in combination of two or more.

[0120] [Other Components] In addition to the components described above, the negative resist material of the present invention may contain an acid generator other than the sulfonium salt represented by formula (A) (hereinafter also referred to as other acid generators), a surfactant, a crosslinking agent, a radical generator, a radical scavenger, a water repellency improver, acetylene alcohols, etc.

[0121] Examples of the other acid generators include compounds (photoacid generators) that generate an acid upon exposure to actinic rays or radiation. Any compound that generates an acid upon irradiation with high-energy rays may be used as the photoacid generator, but those that generate sulfonic acid, imidic acid, or methidic acid are preferred. Preferred photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, oxime-O-sulfonate type acid generators, etc. Specific examples of the acid generator are described in paragraph of JP-A-2008-111103

[0122] -

[0142] , those described in JP-A No. 2018-5224 and JP-A No. 2018-25789 can be mentioned. When the negative resist material of the present invention contains other acid generators, the content thereof is preferably 0 to 200 parts by mass, and preferably 0.1 to 100 parts by mass with respect to 100 parts by mass of the base polymer. The other acid generators may be used alone or in combination of two or more.

[0122] As the surfactant, those described in paragraphs

[0165] to

[0166] of JP-A No. 2008-111103 can be mentioned. By adding a surfactant, the coatability of the resist material can be further improved or controlled. When the negative resist material of the present invention contains the surfactant, the content thereof is preferably 0.0001 to 10 parts by mass with respect to 100 parts by mass of the base polymer. The surfactant may be used alone or in combination of two or more.

[0123] By adding a crosslinking agent to the negative resist material of the present invention, the rectangularity of the negative pattern can be improved by further reducing the dissolution rate of the exposed portion. Examples of the crosslinking agent include epoxy compounds, melamine compounds, guanamine compounds, glycoluril compounds, urea compounds, isocyanate compounds, azide compounds, compounds containing double bonds such as alkenyloxy groups, acrylic groups, methacrylic groups, and styryl groups, which are substituted with at least one group selected from methylol groups, alkoxymethyl groups, and acyloxymethyl groups. These may be used as additives, or may be introduced as pendant groups into the polymer side chain. In addition, compounds containing a hydroxy group can also be used as a crosslinking agent.

[0124] Examples of the epoxy compound include tris(2,3-epoxypropyl) isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, and triethanolamine triglycidyl ether.

[0125] Examples of the melamine compound include hexamethylol melamine, hexamethoxymethyl melamine, a compound in which 1 to 6 methylol groups of hexamethylol melamine are methoxymethylated or a mixture thereof, hexamethoxyethyl melamine, hexaacyloxymethyl melamine, a compound in which 1 to 6 methylol groups of hexamethylol melamine are acyloxymethylated or a mixture thereof, and the like.

[0126] Examples of the guanamine compound include tetramethylol guanamine, tetramethoxymethyl guanamine, a compound in which 1 to 4 methylol groups of tetramethylol guanamine are methoxymethylated or a mixture thereof, tetramethoxyethyl guanamine, tetraacyloxy guanamine, a compound in which 1 to 4 methylol groups of tetramethylol guanamine are acyloxymethylated or a mixture thereof, and the like.

[0127] Examples of the glycoluril compound include tetramethylol glycoluril, tetramethoxy glycoluril, tetramethoxymethyl glycoluril, a compound in which 1 to 4 methylol groups of tetramethylol glycoluril are methoxymethylated or a mixture thereof, a compound in which 1 to 4 methylol groups of tetramethylol glycoluril are acyloxymethylated or a mixture thereof, and the like.

[0128] Examples of the urea compound include tetramethylol urea, tetramethoxymethyl urea, a compound in which 1 to 4 methylol groups of tetramethylol urea are methoxymethylated or a mixture thereof, tetramethoxyethyl urea, and the like.

[0129] Examples of the isocyanate compound include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, and the like.

[0130] Examples of the azide compound include 1,1'-biphenyl-4,4'-bisazide, 4,4'-methylidenebisazide, 4,4'-oxybisazide, and the like.

[0131] Examples of the compound containing an alkenyloxy group include ethylene glycol divinyl ether, triethylene glycol divinyl ether, 1,2-propanediol divinyl ether, 1,4-butanediol divinyl ether, tetramethylene glycol divinyl ether, neopentyl glycol divinyl ether, trimethylolpropane trivinyl ether, hexanediol divinyl ether, 1,4-cyclohexanediol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, sorbitol tetravinyl ether, sorbitol pentavinyl ether, trimethylolpropane trivinyl ether, and the like.

[0132] When the negative resist material of the present invention contains the crosslinking agent, its content is preferably 0.1 to 50 parts by mass, more preferably 1 to 40 parts by mass, based on 100 parts by mass of the base polymer. The crosslinking agent may be used alone or in combination of two or more.

[0133] The negative resist material of the present invention may contain a radical generator in order to increase the reactivity of the double bond in the acid generator. As the radical generator, a photo radical generator is preferable, and specific examples thereof include acetophenone, 4,4'-dimethoxybenzyl, benzyl, benzoin, benzophenone, 2-benzoylbenzoic acid, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, benzoin isobutyl ether, 4-benzoylbenzoic acid, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, methyl 2-benzoylbenzoate, 2-(1,3-benzodioxol-5-yl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone, 4,4'-dichlorobenzophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,4-diethylthioxanthen-9-one, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 1,4-dibenzoylbenzene, 2-ethylanthraquinone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methylpropiophenone, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 2-isonitroso-propiophenone, 2-phenyl-2-(p-toluenesulfonyloxy)acetophenone (BAPO), camphorquinone, and the like.

[0134] When the negative resist material of the present invention contains the radical generator, its content is preferably 0.1 to 50 parts by mass with respect to 100 parts by mass of the base polymer. The radical generator may be used alone or in combination of two or more.

[0135] The negative resist material of the present invention may contain a radical scavenger in order to suppress the diffusion of radicals. Examples of the radical scavenger include hindered phenol compounds, quinone compounds, hindered amine compounds, thiol compounds, TEMPO compounds, etc. Specifically, examples of the hindered phenol compound include dibutylhydroxytoluene (BHT), 2,2'-methylenebis(4-methyl-6-tert-butylphenol) (Antage W-400), etc. Examples of the quinone compound include 4-methoxyphenol (methoquinone), hydroquinone, etc. Examples of the hindered amine compound include 2,2,6,6-tetramethylpiperidine, etc. Examples of the thiol compound include dodecanethiol, hexadecanethiol, etc. Examples of the TEMPO compound include 2,2,6,6-tetramethylpiperidine N-oxyl radical, etc.

[0136] When the negative resist material of the present invention contains the radical scavenger, its content is preferably 0 to 5 parts by mass, more preferably 0 to 4 parts by mass, per 100 parts by mass of the base polymer. The radical scavenger may be used alone or in combination of two or more.

[0137] The water repellency improver is used to improve the water repellency of the resist film surface and can be used in immersion lithography without using a top coat. As the water repellency improver, a polymer containing an alkyl fluoride group, a polymer containing a 1,1,1,3,3,3-hexafluoro-2-propanol residue with a specific structure, etc. are preferable, and those exemplified in JP-A-2007-297590, JP-A-2008-111103, etc. are more preferable. The water repellency improver needs to be dissolved in an organic solvent developer. The water repellency improver having the above-mentioned specific 1,1,1,3,3,3-hexafluoro-2-propanol residue has good solubility in the developer. As the water repellency improver, a polymer containing a repeating unit containing an amino group or an amine salt has a high effect of preventing the evaporation of the acid in PEB and preventing the opening defect of the hole pattern after development. When the negative resist material of the present invention contains a water repellency improver, its content is preferably 0 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, based on 100 parts by mass of the base polymer. The water repellency improver may be used alone or in combination of two or more.

[0138] Examples of the acetylene alcohols include those described in paragraphs

[0179] to

[0182] of JP-A-2008-122932. When the negative resist material of the present invention contains acetylene alcohols, its content is preferably 0 to 5 parts by mass based on 100 parts by mass of the base polymer. The acetylene alcohols may be used alone or in combination of two or more.

[0139] [Pattern formation method] When the negative resist material of the present invention is used in the manufacture of various integrated circuits, known lithography techniques can be applied. For example, as a pattern formation method, a method including a step of forming a resist film on a substrate using the above-mentioned negative resist material, a step of exposing the resist film with high energy rays, and a step of developing the exposed resist film using a developer can be mentioned.

[0140] First, the negative resist material of the present invention is applied onto a substrate for integrated circuit manufacturing (Si, SiO 2 , SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflection film, etc.) or a substrate for mask circuit manufacturing (Cr, CrO, CrON, MoSi 2 , SiO 2 , etc.) by an appropriate coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, doctor coating, etc., so that the coating film thickness becomes 0.01 to 2 μm. This is prebaked on a hot plate, preferably at 60 to 150°C for 10 seconds to 30 minutes, more preferably at 80 to 120°C for 30 seconds to 20 minutes, to form a resist film.

[0141] Next, the resist film is exposed using high-energy rays. Examples of the high-energy rays include ultraviolet rays, far ultraviolet rays, EB, EUV with a wavelength of 3 to 15 nm, X-rays, soft X-rays, excimer laser light, γ-rays, synchrotron radiation, etc. When using ultraviolet rays, far ultraviolet rays, EUV, X-rays, soft X-rays, excimer laser light, γ-rays, synchrotron radiation, etc. as the high-energy rays, the exposure amount is preferably about 1 to 200 mJ / cm 2 , more preferably about 10 to 100 mJ / cm 2 , and irradiation is performed so as to be in this range. When using EB as the high-energy ray, the exposure amount is preferably about 0.1 to 500 μC / cm 2 , more preferably about 0.5 to 400 μC / cm 2 , and drawing is performed directly or using a mask for forming a target pattern so as to be in this range. Note that the negative resist material of the present invention is particularly suitable for fine patterning by KrF excimer laser light, ArF excimer laser light, EB, EUV, X-rays, soft X-rays, γ-rays, synchrotron radiation among high-energy rays, and is particularly suitable for fine patterning by EB or EUV.

[0142] During high-energy radiation exposure, radicals are generated from anions having maleimide groups, and the double bonds of the cations of the acid generator represented by the formula (A) in the exposed portion of the resist film polymerize, and the crosslinking reaction proceeds. As the crosslinking reaction proceeds, the remaining film in the exposed portion increases, the dissolution contrast improves, and the mechanical strength of the film in the exposed portion increases, making it difficult for pattern collapse to occur.

[0143] After exposure, PEB may or may not be performed on a hot plate or in an oven, preferably at 30 to 150 °C for 10 seconds to 30 minutes, more preferably at 50 to 120 °C for 30 seconds to 20 minutes.

[0144] Next, a negative pattern is obtained by organic solvent development. Examples of the developer used at this time include 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, isopentyl acetate, 2-methylbutyl acetate, hexyl acetate, butenyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonate, ethyl crotonate, methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, 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 phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, 2-phenylethyl acetate, etc. These organic solvents may be used alone or in combination of two or more.

[0145] At the end of development, rinsing is performed. As the rinsing liquid, a solvent that is miscible with the developer and does not dissolve the resist film is preferred. As such a solvent, 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 are preferably used.

[0146] Specifically, examples of the alcohol having 3 to 10 carbon atoms include n-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-pentyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, 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.

[0147] Examples of the ether compound having 8 to 12 carbon atoms include di-n-butyl ether, diisobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, di-sec-pentyl ether, di-tert-pentyl ether, di-n-hexyl ether, and the like.

[0148] Examples of alkanes having 6 to 12 carbon atoms include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, cyclononane, etc. Examples of alkenes having 6 to 12 carbon atoms include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, cyclooctene, etc. Examples of alkynes having 6 to 12 carbon atoms include hexyne, heptyne, octyne, etc.

[0149] Examples of aromatic solvents include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, mesitylene, etc.

[0150] By performing rinsing, the collapse of the resist pattern and the occurrence of defects can be reduced. Also, rinsing is not necessarily essential, and the amount of solvent used can be reduced by not performing rinsing.

[0151] The developed hole pattern or trench pattern can also be shrunk by thermal flow, RELACS technology, or DSA technology. A shrinking agent is applied onto the hole pattern, and cross-linking of the shrinking agent occurs on the surface of the resist film due to the diffusion of the acid catalyst from the resist film during baking, and the shrinking agent adheres to the sidewalls of the hole pattern. The baking temperature is preferably 70 to 180 °C, more preferably 80 to 170 °C, and the baking time is preferably 10 to 300 seconds, removing the excess shrinking agent and shrinking the hole pattern.

Examples

[0152] Hereinafter, the present invention will be specifically described by showing synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples.

[0153] The structures of acid generators PAG-1 to PAG-14 used in the resist material are shown below. PAG-1 to PAG-14 were synthesized by ion exchange between an ammonium salt of a fluorinated sulfonic acid that gives the following anions and a sulfonium chloride that gives the following cations, respectively. [Chemical formula]

[0154] [Chemical formula]

[0155] [Chemical formula]

[0156] [Chemical formula]

[0157] [Synthesis Example] Synthesis of Base Polymers (Polymers P-1 to P-5) Each monomer was combined and copolymerized in THF as a solvent, then put into methanol. The precipitated solid was washed with hexane, isolated, and dried to obtain base polymers (polymers P-1 to P-5) with the following compositions. The compositions of the obtained base polymers were 1 Determined by 1H-NMR, and Mw and Mw / Mn were confirmed by GPC (solvent: THF, standard: polystyrene). [Chemical formula]

[0158] [Examples 1 to 23, Comparative Examples 1 to 3] Preparation and Evaluation of Negative Resist Materials (1) Preparation of Negative Resist Materials A solution in which each component was dissolved in the composition shown in Tables 1 and 2 in a solvent in which 100 ppm of Polyfox PF-636 manufactured by Omnova Solutions Inc. was dissolved as a surfactant was filtered through a 0.2-μm size filter to prepare a negative resist material.

[0159] In Tables 1 and 2, each component is as follows. · Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) PGME (propylene glycol monomethyl ether) EL (ethyl lactate) DAA (diacetone alcohol)

[0160] · Comparative acid generator: cPAG-1 to cPAG-3

Chemical formula

[0161] · Quencher: Q-1 to Q-4

Chemical formula

[0162] · Radical scavenger: RC-1, RC-2

Chemical formula

[0163] · Crosslinking agent: CL-1

Chemical formula

[0164] (2) EB Lithography Evaluation DUV-42 manufactured by Nissan Chemical Industries, Ltd. was applied onto a silicon substrate and baked at 200 °C for 60 seconds to form an antireflection film (film thickness: 60 nm). Each of the negative resist materials shown in Tables 1 and 2 was spin-coated onto the antireflection film and prebaked at 105 °C for 60 seconds using a hot plate to produce a resist film with a film thickness of 35 nm. In contrast, using an EB lithography apparatus ELS-F125 manufactured by Elionix, lithography was performed at an acceleration voltage of 125 kV and a current of 50 pA, PEB was carried out at the temperatures described in Tables 1 and 2 for 60 seconds on a hot plate, and after developing with 2-methylbutyl acetate for 30 seconds, spin drying was performed to obtain a 30 nm line and space 1:1 pattern. The formed pattern was observed using a length measuring SEM (CG5000) manufactured by Hitachi High-Technologies Corporation. The exposure amount at which a 30 nm line and space could be obtained was defined as the sensitivity, and the minimum line width (nm) of the line and space separated at the exposure amount was determined as the limit resolution. The results are shown in Tables 1 and 2.

[0165]

Table 1

[0166]

Table 2

[0167] From the results shown in Tables 1 and 2, it was found that the negative resist material of the present invention containing a sulfonium salt composed of a sulfonate anion having a maleimide group and a cation having a polymerizable double bond as an acid generator is excellent in limit resolution.

Claims

1. A negative resist material containing a base polymer and an acid generator which is a sulfonium salt composed of a sulfonic acid anion having a maleimide group and a cation having a polymerizable double bond.

2. The negative resist material according to Claim 1, wherein the sulfonium salt composed of the sulfonic acid anion having a maleimide group and the cation having a polymerizable double bond is represented by the following formula (A). 【Chemical 1】 (In the formula, m is an integer of 1 to 3, n is an integer of 0 to 2. However, m + n = 3. p is 1 or 2, q is an integer of 0 to 4. However, 1 ≤ p + q ≤ 5. r is an integer of 0 to 5.) X 1 is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms, and the hydrocarbylene group may contain an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom. X 2 is an ester bond or an alkanediyl group having 1 to 8 carbon atoms. X 3 is a single bond, an ester bond, an ether bond, an amide bond, a urethane bond, or an alkanediyl group having 1 to 10 carbon atoms, and a part of 2 -CH- of the alkanediyl group may be substituted with an ester bond, an ether bond, an amide bond, or a urethane bond. R 1 and R 2 each independently represents a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms, and R 1 and R 2 may be bonded to each other to form a ring together with the carbon atom to which they are bonded. R 3 to R 5 each independently represents a hydrogen atom, a halogen atom or a saturated hydrocarbyl group having 1 to 40 carbon atoms, and part or all of the hydrogen atoms of the saturated hydrocarbyl group may be substituted with fluorine atoms or hydroxy groups, and part of -CH 2 - may be substituted with an ether bond or an ester bond, and part of the carbon-carbon bonds of the saturated hydrocarbyl group may be double bonds. R 6 and R 7 each independently represents a halogen atom, a cyano group, a nitro group, a mercapto group, a sulfo group, a saturated hydrocarbyl group having 1 to 10 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, and the saturated hydrocarbyl group and the aralkyl group may contain an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom. Further, two R 6 or two R 7 may be bonded to each other to form a ring together with the benzene ring to which they are bonded, and R 6 and R 7 may be bonded to each other to form a ring together with the benzene ring to which they are bonded and the sulfur atom therebetween. Rf 1 ~Rf 4 is, independently of one another, a hydrogen atom, a fluorine atom or a trifluoromethyl group, provided that at least one of these is a fluorine atom or a trifluoromethyl group. Further, Rf 1 and Rf 2 may combine to form a carbonyl group.)

3. The negative resist material according to Claim 1, wherein the base polymer contains a repeating unit represented by the following formula (a1). 【Chemical 2】 (wherein, R A is each independently a hydrogen atom or a methyl group.) Y 1 is a linking group having 1 to 12 carbon atoms and containing at least one selected from a single bond, a phenylene group or a naphthylene group, or an ester bond, an ether bond and a lactone ring. R 11 is an acid-labile group.)

4. The negative resist material according to Claim 1, further containing an organic solvent.

5. The negative resist material according to Claim 1, further containing a quencher.

6. The negative resist material according to Claim 1, further containing a crosslinking agent.

7. The negative resist material according to Claim 1, further containing a surfactant.

8. A pattern forming method including a step of forming a resist film on a substrate using the negative resist material according to any one of Claims 1 to 7, a step of exposing the negative resist film with high energy rays, and a step of developing the exposed negative resist film using an organic solvent developer.

9. The pattern forming method according to claim 8, wherein the organic solvent developer is at least one selected from 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, isopentyl acetate, 2-methylbutyl acetate, hexyl acetate, butenyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonate, ethyl crotonate, methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, 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 phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate and 2-phenylethyl acetate.

10. The pattern forming method according to claim 8, wherein the high energy ray is KrF excimer laser light, ArF excimer laser light, an electron beam or extreme ultraviolet light having a wavelength of 3 to 15 nm.

Images