Resist composition and pattern forming method

Abstract

The invention relates to a resist composition and a pattern forming method. The present invention addresses the problem of providing a non-chemically amplified resist composition having excellent sensitivity and resolution in optical lithography using high-energy rays, and a pattern forming method using the resist composition. [Solution] The resist composition contains a superatomic bismuth compound, a carboxylic acid compound, and a solvent.

Description

Technical Field

[0001] The present invention relates to a resist composition and a pattern forming method. Background Art

[0002] With the expansion of the IoT market, demands for higher integration, higher speed, and lower power consumption in LSIs are increasing, and the miniaturization of patterning is also progressing rapidly. Logic devices are leading the way in miniaturization. Among the most advanced miniaturization technologies, mass production of 10nm node devices using double, triple, and quadruple patterning with ArF immersion lithography is already underway, while research is progressing on 7nm node devices using next-generation extreme ultraviolet (EUV) lithography with a wavelength of 13.5nm.

[0003] As miniaturization progresses, image blurring caused by acid diffusion has become a problem (Non-Patent Document 1). To ensure resolution in fine patterns with processing sizes below 45 nm, some have proposed that controlling acid diffusion is important, not just improving dissolution contrast, as previously advocated (Non-Patent Document 2). However, chemically amplified resist compositions improve sensitivity and contrast through acid diffusion. Therefore, limiting acid diffusion to the limit by lowering the post-exposure bake (PEB) temperature or shortening the PEB time can significantly reduce sensitivity and contrast.

[0004] Adding an acid generator that generates bulky acids to inhibit acid diffusion is effective. For this reason, acid generators that copolymerize onium salts with polymerizable olefins have been proposed. However, in patterning resist films with a process size of 16 nm or less, chemically amplified resist compositions are believed to be incapable of patterning due to acid diffusion, leading to a desire for the development of non-chemically amplified resist compositions.

[0005] Examples of materials used in non-chemically amplified resist compositions include polymethyl methacrylate (PMMA), a positive-tone resist material whose solubility in organic solvent developers is improved by EUV irradiation, as its main chain is cut and its molecular weight is reduced.

[0006] Hydrogen silsesquioxane (HSQ) is a crosslinked material formed by the condensation reaction of silanols produced by EUV irradiation, thereby becoming a negative resist material that is insoluble in alkaline developer. In addition, chlorine-substituted calixarene also functions as a negative resist material. Because these negative resist materials have a small molecular size before crosslinking and do not blur due to acid diffusion, they can be used as pattern transfer materials with low edge roughness and very high resolution, and can exhibit the resolution limit of exposure equipment. However, the sensitivity of these materials is insufficient, and further improvement is needed.

[0007] The main reason for the difficulty in developing materials for EUV lithography is the low photon count during EUV exposure. EUV energy is much higher than that of ArF excimer lasers, and the photon count during EUV exposure is only one-fourteenth of that during ArF exposure. Furthermore, the size of a pattern formed using EUV exposure is less than half that of an ArF exposure. Therefore, EUV exposure is susceptible to photon count variation. Photon count variation in the extremely short-wavelength emission region is known as shot noise, a physical phenomenon that cannot be eliminated. Consequently, stochastics has attracted attention. While the effects of shot noise cannot be eliminated, how can they be reduced? Shot noise can lead to increased dimensional uniformity (CDU) and line width roughness (LWR), and there is also a one-in-million chance of pore blockage. Blocked pores result in poor conductivity and transistor inoperability, negatively impacting overall device performance. Considering practical sensitivity, resist compositions containing PMMA or HSQ as main components are significantly affected by stochastics and may not achieve the desired resolution.

[0008] As a method for reducing the effects of shot noise in resists, the introduction of elements that strongly absorb EUV light has attracted attention. Patent Document 1 proposes a chemically amplified resist composition containing iodine atoms that strongly absorb EUV light. However, as previously mentioned, chemically amplified resist compositions cannot achieve excellent resolution in EUV lithography, where process dimensions are increasingly miniaturized.

[0009] Patent Document 2 claims a negative-type resist composition using a tin compound. This is because tin, a major component with high EUV light absorption, improves stochastics and achieves high sensitivity and high resolution. However, such metal resists have numerous issues, including insufficient solubility in resist solvents, insufficient storage stability due to excessive reactivity, and defects caused by post-etching residue.

[0010] Prior art literature

[0011] Patent Literature

[0012] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-5224

[0013] [Patent Document 2] Japanese Patent Publication No. 2021-503482

[0014] Non-patent literature

[0015] [Non-Patent Document 1] SPIE Vol. 5039 p1 (2003)

[0016] [Non-Patent Document 2] SPIE Vol. 6520p65203L-1 (2007) Summary of the Invention

[0017] [Problems to be Solved by the Invention]

[0018] The present invention is made in view of the above situation, and its purpose is to provide a non-chemically amplified resist composition with excellent sensitivity and resolution in optical lithography using high-energy rays, especially electron beam (EB) lithography and EUV lithography, and to provide a pattern forming method using the resist composition.

[0019] [Methods for solving the problem]

[0020] As a result of repeated and intensive research to achieve the aforementioned objectives, the present inventors have gained the following insights, leading to the completion of the present invention: a resist composition containing a specific bismuth compound and a carboxylic acid compound as main components can provide a resist film with extremely high sensitivity and excellent resolution, which is extremely effective in precise microfabrication.

[0021] That is, the present invention provides the following resist composition and pattern forming method.

[0022] 1. A resist composition comprising: a supervalent bismuth compound, a carboxylic acid compound, and a solvent.

[0023] 2. The resist composition according to 1., wherein the supervalent bismuth compound is represented by the following formula (1).

[0024] [Chemistry 1]

[0025]

[0026] In the formula, p, q, and r are each independently an integer of 0 to 5.

[0027] R 1 and R 2 are each independently a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may contain a hetero atom. 1 and R 2 They may also be bonded to each other and to the carbon atoms to which they are bonded and the atoms between the carbon atoms to form a ring.

[0028] R 3 、R 4 and R 5 Each independently represents a halogen atom or a hydrocarbon group having 1 to 40 carbon atoms which may contain a heteroatom.

[0029] 3. The resist composition according to 1. or 2., wherein the carboxylic acid compound is represented by the following formula (2).

[0030] [Chemistry 2]

[0031]

[0032] In the formula, m is an integer from 1 to 4.

[0033] R 11 is an m-valent hydrocarbon group having 1 to 40 carbon atoms or an m-valent heterocyclic group having 2 to 40 carbon atoms, and when m is 2, R 11 Alternatively, it may be an ether bond, a carbonyl group, an azo group, a thioether bond, a carbonate bond, a carbamate bond, a sulfinyl group, or a sulfonyl group. Furthermore, some or all of the hydrogen atoms of the aforementioned m-valent hydrocarbon group or m-valent heterocyclic group may be substituted with a group containing a heteroatom, and some of the -CH2- groups of the aforementioned m-valent hydrocarbon group may be substituted with a group containing a heteroatom.

[0034] R 12 is a single bond or an alkylene group having 1 to 10 carbon atoms, and part or all of the hydrogen atoms of the alkylene group may be substituted by a group containing a heteroatom, and part of the -CH2- of the alkylene group may be substituted by a group containing a heteroatom. When m is 2 to 4, each R 12 They can be the same or different.

[0035] 4. A pattern forming method comprising the following steps:

[0036] Using the resist composition according to any one of 1. to 3., forming a resist film on a substrate,

[0037] exposing the resist film to high-energy radiation, and

[0038] The exposed resist film is developed using a developer.

[0039] 5. The pattern forming method according to 4., wherein the high-energy rays are EB or EUV.

[0040] 6. The pattern forming method according to 4. or 5., wherein the developer dissolves the exposed portion and does not dissolve the unexposed portion.

[0041] 7. The pattern forming method according to 4. or 5., wherein the developer dissolves the unexposed portion and does not dissolve the exposed portion.

[0042] [Effects of the Invention]

[0043] The resist composition of the present invention is particularly useful in forming fine patterns while achieving both high sensitivity and high resolution in EB lithography and EUV lithography. DETAILED DESCRIPTION

[0044] [Resist composition]

[0045] The resist composition of the present invention contains a hypervalent bismuth compound and a carboxylic acid compound as main components.

[0046] [Supervalent Bismuth Compounds]

[0047] Supervalent bismuth compounds are a general term for bismuth compounds that formally have valence electrons exceeding the octet rule. Examples of the supervalent bismuth compounds include pentacoordinate bismuth compounds with an oxidation number of +5.

[0048] The aforementioned supervalent bismuth compound is particularly preferably a pentacoordinate supervalent bismuth compound represented by the following formula (1).

[0049] [Chemistry 3]

[0050]

[0051] In formula (1), p, q, and r are each independently an integer of 0 to 5.

[0052] In formula (1), R 1 and R 2 are each independently a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may contain a hetero atom. 1 and R 2 They may also bond to each other and form a ring together with the carbon atoms to which they are bonded and the atoms between the carbon atoms. Specific examples of the aforementioned halogen atoms include: fluorine atom, chlorine atom, bromine atom, iodine atom, etc. The aforementioned hydrocarbon group having 1 to 10 carbon atoms may be saturated or unsaturated, and may be straight-chain, branched, or cyclic. Specific examples thereof include: alkyl groups having 1 to 10 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, tricyclo[5.2.1.0 2,6 ] Cyclic saturated hydrocarbon groups having 3 to 10 carbon atoms, such as decyl and adamantyl; alkenyl groups having 2 to 10 carbon atoms, such as vinyl and allyl; aryl groups having 6 to 10 carbon atoms, such as phenyl and naphthyl; groups obtained by combining them, etc. In addition, part or all of the hydrogen atoms of the aforementioned hydrocarbon groups may be substituted by groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and part of the -CH2- of the aforementioned hydrocarbon groups may be substituted by groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, hydroxyl groups, cyano groups, halogen atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonate bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic anhydride (-C(=O)-OC(=O)-), etc. R 1 and R 2 It is preferably a hydrocarbon group having 1 to 4 carbon atoms.

[0053] In formula (1), R 3 、R 4 and R 5 Each is independently a halogen atom, or a hydrocarbon group having 1 to 40 carbon atoms which may also contain a heteroatom. Specific examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc. The aforementioned hydrocarbon group having 1 to 40 carbon atoms may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 40 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, tricyclo[5.2.1.0 2,6 ] cyclic saturated hydrocarbon groups having 3 to 40 carbon atoms, such as decyl, adamantyl, and adamantylmethyl; aryl groups having 6 to 40 carbon atoms, such as phenyl, naphthyl, and anthracenyl. In addition, part or all of the hydrogen atoms of the aforementioned hydrocarbon groups may be substituted by groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and part of the -CH2- of the aforementioned hydrocarbon groups may be substituted by groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, hydroxyl groups, cyano groups, halogen atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonate bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic anhydride (-C(=O)-OC(=O)-), and the like may be contained. When p is 2 to 5, each R 3 They can be the same or different. When q is 2 to 5, each R 4 They can be the same or different from each other. When r is 2 to 5, each R 5 They can be the same or different.

[0054] Specific examples of the supervalent bismuth compound represented by formula (1) include the following, but are not limited thereto.

[0055] [Chemistry 4]

[0056]

[0057] [Chemistry 5]

[0058]

[0059] [Chemistry 6]

[0060]

[0061] [Chemistry 7]

[0062]

[0063] [Carboxylic acid compound]

[0064] As the carboxylic acid compound used in the present invention, all carboxylic acid compounds generally defined in organic chemistry can be applied, and those represented by the following formula (2) are preferred.

[0065] [Chemistry 8]

[0066]

[0067] In formula (2), m is an integer of 1 to 4. 11 is an m-valent hydrocarbon group having 1 to 40 carbon atoms or an m-valent heterocyclic group having 2 to 40 carbon atoms, and when m is 2, R 11 It may also be an ether bond, a carbonyl group, an azo group, a thioether bond, a carbonate bond, a carbamate bond, a sulfinyl group, or a sulfonyl group. Furthermore, some or all of the hydrogen atoms of the aforementioned m-valent hydrocarbon group or m-valent heterocyclic group may be substituted with a group containing a heteroatom, and some of the -CH2- groups of the aforementioned m-valent hydrocarbon group may be substituted with a group containing a heteroatom. 12 is a single bond or an alkylene group having 1 to 10 carbon atoms, and part or all of the hydrogen atoms of the alkylene group may be substituted by a group containing a heteroatom, and part of the -CH2- of the alkylene group may be substituted by a group containing a heteroatom. When m is 2 to 4, each R 12 They can be the same or different.

[0068] R 11 The m-valent hydrocarbon group represented by may be saturated or unsaturated and may be linear, branched, or cyclic. The m-valent hydrocarbon group is a group derived from a hydrocarbon by removing m hydrogen atoms. Specific examples of the hydrocarbon include alkanes having 1 to 40 carbon atoms, alkenes having 2 to 40 carbon atoms, alkynes having 2 to 40 carbon atoms, cyclic saturated hydrocarbons having 3 to 40 carbon atoms, cyclic unsaturated hydrocarbons having 3 to 40 carbon atoms, and aromatic hydrocarbons having 6 to 40 carbon atoms.

[0069] Specific examples of the alkane having 1 to 40 carbon atoms include methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, and structural isomers thereof.

[0070] Specific examples of the olefin having 2 to 40 carbon atoms include ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, decene, and structural isomers thereof.

[0071] Specific examples of the alkyne having 2 to 40 carbon atoms include acetylene, propyne, butyne, pentyne, hexyne, heptyne, octyne, nonyne, decyne, and structural isomers thereof.

[0072] Specific examples of the cyclic saturated hydrocarbon having 3 to 40 carbon atoms include cyclopropane, cyclobutane, cyclohexane, cycloheptane, cyclooctane, adamantane, and norbornane.

[0073] Specific examples of the cyclic unsaturated hydrocarbon having 3 to 40 carbon atoms include cyclopropene, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, and norbornene.

[0074] Specific examples of the aromatic hydrocarbon having 6 to 40 carbon atoms include benzene, naphthalene, and biphenyl.

[0075] R 11 The m-valent heterocyclic group represented by is a group obtained by removing m hydrogen atoms from a heterocyclic compound. Specific examples of the heterocyclic compound include furan, pyridine, pyrazole, and tetrahydrothiazole.

[0076] The aforementioned m-valent hydrocarbon group or m-valent heterocyclic group may have some or all of its hydrogen atoms substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, or halogen atoms, and may contain hydroxyl groups, cyano groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, and the like. Furthermore, in the aforementioned m-valent hydrocarbon group, a portion of the -CH2- groups constituting the group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, or nitrogen atoms, and may contain carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonate bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic anhydrides (-C(=O)-OC(=O)-), and the like.

[0077] R 12 The alkylene group represented by may be saturated or unsaturated, and may be straight-chain, branched, or cyclic. Specific examples thereof include methanediyl, ethane-1,1-diyl, ethane-1,2-diyl, propane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, nonane-1,9-diyl, decane-1,10-diyl, undecane-1, Alkanediyl groups having 1 to 20 carbon atoms, such as cyclopentanediyl, cyclohexanediyl, norbornanediyl, and adamantanediyl; unsaturated aliphatic alkylene groups having 2 to 20 carbon atoms, such as vinylene and propene-1,3-diyl; arylene groups having 6 to 20 carbon atoms, such as phenylene and naphthylene; and groups derived from combinations thereof. Furthermore, a part or all of the hydrogen atoms of the aforementioned alkylene group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and a part of the -CH2- constituting the aforementioned alkylene group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the group may contain a hydroxyl group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonate bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), and the like.

[0078] Specific examples of the carboxylic acid compound include the following, but are not limited thereto.

[0079] [Chemistry 9]

[0080]

[0081] [Chemistry 10]

[0082]

[0083] [Chemistry 11]

[0084]

[0085] In the resist composition of the present invention, the molar ratio of the supervalent bismuth compound to the carboxylic acid compound is preferably 10:90 to 90:10, more preferably 20:80 to 80:20, and even more preferably 30:70 to 70:30.

[0086] [Solvent]

[0087] The resist composition of the present invention contains a solvent. The aforementioned solvent is not particularly limited as long as it can dissolve the aforementioned supervalent bismuth compound, carboxylic acid compound and other components described later and can form a film. Such a solvent is preferably an organic solvent, and specific examples thereof include: ketones such as cyclohexanone, methyl-2-n-pentyl ketone, and methyl isoamyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, diacetone alcohol, 4-methyl-2-pentanol, and methyl 2-hydroxyisobutyrate; propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, and ethyl ether. Ethers such as 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 mono-tert-butyl ether acetate; carboxylic acids such as formic acid, acetic acid, and propionic acid; lactones such as γ-butyrolactone; and mixed solvents thereof.

[0088] In the resist composition of the present invention, the solvent is preferably present in an amount such that the solids concentration in the resist composition is 0.1 to 20% by mass, more preferably 0.1 to 15% by mass, and even more preferably 0.1 to 10% by mass. In the present invention, the term "solids" collectively refers to all components of the resist composition other than the solvent. The solvent may be used alone or as a mixture of two or more.

[0089] [Other ingredients]

[0090] The resist composition of the present invention may further contain a surfactant. The surfactant is preferably a fluorine-based and / or silicone-based surfactant. Specific examples of such surfactants include the surfactants described in paragraph

[0276] of U.S. Patent Application Publication No. 2008 / 0248425. Surfactants other than the fluorine-based and / or silicone-based surfactants described in paragraph

[0280] of U.S. Patent Application Publication No. 2008 / 0248425 may also be used.

[0091] When the resist composition of the present invention contains the surfactant, its content is preferably 0.0001 to 2% by mass based on the total solid content. The surfactant may be used alone or in combination of two or more.

[0092] The resist composition of the present invention may further contain a radical scavenger. By adding the radical scavenger, the photoreaction in optical lithography can be controlled and the sensitivity can be adjusted.

[0093] Specific examples of the radical scavenger include hindered phenols, quinones, hindered amines, and thiol compounds. Specific examples of the hindered phenols include butylated hydroxytoluene (BHT) and 2,2'-methylenebis(4-methyl-6-tert-butylphenol). Specific examples of the quinones include 4-methoxyphenol (MEHQ) and hydroquinone. Specific examples of the hindered amines include 2,2,6,6-tetramethylpiperidine and 2,2,6,6-tetramethylpiperidinium-N-oxide. Specific examples of the thiols include dodecanethiol and hexadecanethiol.

[0094] When the resist composition of the present invention contains the radical scavenger, the content thereof is preferably 0.01 to 10% by mass based on the total solid content. The radical scavengers may be used alone or in combination of two or more.

[0095] The resist composition of the present invention contains a supervalent bismuth compound and a carboxylic acid compound as main components, but does not contain a base polymer containing an acid-labile group or a photoacid generator, as found in conventional chemically amplified resist compositions. However, the resist composition of the present invention can form a pattern by varying its developer solubility between unexposed and exposed areas, particularly during EB or EUV exposure. The mechanism of this behavior is not fully elucidated, but is speculated as follows, for example.

[0096] The aforementioned super-valent bismuth compound is a 5-coordinate compound formed by bonding an aromatic group to two carboxylate ligands as represented by formula (1). It is believed that such a 5-coordinate bismuth compound will undergo an exchange of carboxylate ligands due to an equilibrium reaction when mixed with a carboxylic acid compound. At this time, if the original carboxylate ligand can be removed by any method, a super-valent bismuth compound having a new ligand will be generated. For example, if triphenyl bismuth diacetate, which is easier to obtain as a super-valent bismuth compound, is mixed with a carboxylic acid compound with a large molecular weight and the generated low-boiling acetic acid is removed, the ligand exchange will be completed. If the ligand has a large enough molecular weight, a strong resist film can be formed. In particular, if a compound having multiple carboxyl groups is used as a carboxylic acid compound (such as a dicarboxylic acid compound), it is believed that a high molecular weight body having a polyester structure of a super-valent bismuth compound can be formed, and film forming properties can be ensured.

[0097] The bond between the hypervalent bismuth compound and the carboxylic acid compound is formed during film formation. Specifically, during film formation and the subsequent baking step, the original low-molecular-weight carboxylic acid component is removed, thereby completing the ligand exchange reaction and forming the resist film.

[0098] The film-forming supervalent bismuth compound decomposes due to light, changing its polarity and forming a pattern during the development step. Furthermore, by appropriately selecting the developer, positive or negative patterns can be formed.

[0099] Based on the above speculation, the resist composition of the present invention can be described as a non-chemically amplified resist composition. Therefore, the resist composition of the present invention does not suffer from the image blurring caused by acid diffusion observed in conventional chemically amplified resist compositions (compositions containing a base polymer and a photoacid generator), allowing for resolution of fine patterns.

[0100] The resist composition of the present invention is particularly effective in EUV lithography. This is due to the high absorption of EUV light by bismuth atoms. This reduces shot noise, enabling higher resolution and lower LWR.

[0101] With regard to EUV resist compositions that can form fine patterns, there are reports of metal resists (e.g., patent document 2) with metal tin compounds having high absorption capacity for EUV light, similar to bismuth atoms, as main components. However, as mentioned above, such metal resists have problems such as insufficient solubility in solvents and storage stability. On the other hand, the solvent solubility of the resist composition of the present invention is excellent. In addition, the resist composition of the present invention is applicable to either positive or negative types, so its use is wide. For example, in the contact hole formation step, the metal resist implemented with negative development requires an inversion processing step after the column pattern is formed, but the positive resist does not need such a step. Therefore, considering the viewpoint of ease of processing, the resist composition of the present invention can also be said to be more useful than the metal resist.

[0102] [Pattern Formation Method]

[0103] When the resist composition of the present invention is used in the manufacture of various integrated circuits, known photolithography techniques can be employed. For example, a specific example of a pattern forming method includes forming a resist film on a substrate using the resist composition, exposing the resist film to high-energy radiation, and developing the exposed resist film using a developer.

[0104] First, the resist composition of the present invention is applied to a substrate (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective film, etc.) for integrated circuit manufacturing or a substrate (Cr, CrO, CrON, MoSi2, SiO2, etc.) for mask circuit manufacturing using an appropriate coating method such as spin coating, roller coating, flow coating, dip coating, spray coating, or blade coating to a coating thickness of 0.01 to 2 μm. The resist composition is then pre-baked on a hot plate at a temperature of preferably 60 to 200° C. for 10 seconds to 30 minutes, and more preferably 80 to 180° C. for 30 seconds to 20 minutes to form a resist film.

[0105] Then, the resist film is exposed to high-energy radiation. Specific examples of the high-energy radiation include ultraviolet radiation, extreme ultraviolet radiation, EB, EUV, X-rays, soft X-rays, excimer lasers, gamma rays, and synchrotron radiation. When ultraviolet radiation, extreme ultraviolet radiation, EUV, X-rays, soft X-rays, excimer lasers, gamma rays, and synchrotron radiation are used as the high-energy radiation, the exposure dose is preferably about 1 to 300 mJ / cm2, either directly or through a mask for forming a target pattern. 2 More preferably, it is about 10 to 200 mJ / cm 2 When EB is used as high energy ray, it is preferably irradiated with an exposure dose of about 0.1 to 5000 μC / cm2 directly or through a mask for forming the target pattern. 2More preferably, it is about 0.5 to 4000 μC / cm 2 Furthermore, the resist composition of the present invention is suitable for fine patterning using EB or EUV, particularly among high-energy rays.

[0106] After exposure, PEB is performed as needed, preferably on a hot plate or in an oven at 30-120° C. for 10 seconds to 30 minutes, more preferably at 60-100° C. for 30 seconds to 20 minutes.

[0107] After exposure or PEB, patterning is performed using a developer. Specific examples of the developer used at this time include alkaline aqueous solutions such as tetramethylammonium hydroxide aqueous solution or 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, isopropyl alcohol, n-butanol, n-pentanol, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butyl acetate, isoamyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isoamyl formate, methyl valerate, methyl pentenoate, methyl crotonate, ethyl crotonate, methyl propionate, ethyl propionate, 3-ethylhexyl acrylate ... Organic solvents such as ethyl oxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, amyl lactate, isoamyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, ethyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, 2-phenylethyl acetate, 2-propanol, 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, diacetone alcohol, and 4-methyl-2-pentanol can be used. In the present invention, development with an organic solvent forms a positive pattern in which the exposed portion dissolves and the unexposed portion does not dissolve, while development with an alkaline aqueous solution forms a negative pattern in which the unexposed portion dissolves and the exposed portion does not dissolve. These developers can be used alone or in combination of two or more.

[0108] After development, rinsing is performed as needed. The rinsing solution should preferably be a solvent that is miscible with the developer and does not dissolve the resist film. Suitable solvents include alcohols with 3 to 10 carbon atoms, ether compounds with 8 to 12 carbon atoms, alkanes, alkenes, and alkynes with 6 to 12 carbon atoms, and aromatic solvents. Alternatively, water can be used as the rinsing solution in place of the organic solvent.

[0109] By performing rinsing, the occurrence of resist pattern collapse and defects can be reduced. In addition, rinsing is not essential, and by not performing rinsing, the amount of solvent used can be reduced.

[0110] Example

[0111] Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[0112] [1] Preparation of resist composition

[0113] [Examples 1-1 to 1-16, Comparative Examples 1-1 to 1-3]

[0114] A hypervalent bismuth compound and a carboxylic acid compound were dissolved in a solvent according to the composition shown in Table 1 below, and the resulting solution was filtered through a 0.2 μm Teflon (registered trademark) filter to prepare resist compositions (R-01 to R-16). Furthermore, a polymer, a photoacid generator, a sensitivity adjuster, a solvent, and 0.01 mass% of a surfactant (PF-636, manufactured by OMNOVA) were mixed according to the composition shown in Table 2 below, and the mixture was filtered through a 0.2 μm Teflon (registered trademark) filter to prepare comparative resist compositions (CR-01 to CR-03).

[0115] [Table 1]

[0116]

[0117]

[0118] [Table 2]

[0119]

[0120] In Table 1, the hypervalent bismuth compounds (B-1 to B-3), the carboxylic acid compounds (CA-1 to CA-11), and the solvent are as follows.

[0121] [Chemistry 12]

[0122]

[0123] [Chemistry 13]

[0124]

[0125] Solvent: PGMEA (propylene glycol monomethyl ether acetate)

[0126] HBM (2-hydroxyisobutyric acid methyl ester)

[0127] GBL (γ-butyrolactone)

[0128] In Table 2, the base polymer (P-1), the photoacid generators (PAG-1, PAG-2), and the sensitivity adjusters (Q-1, Q-2) are as follows.

[0129] [Chemistry 14]

[0130]

[0131] [Chemistry 15]

[0132]

[0133] [Chemistry 16]

[0134]

[0135] [2] EUV lithography evaluation (line and space patterning, positive tone development)

[0136] [Examples 2-1 to 2-16, Comparative Examples 2-1 to 2-3]

[0137] Each resist composition (R-01 to R-16, CR-01 to CR-03) was spin-coated onto a Si substrate having a 20 nm thick film of a Shin-Etsu Chemical Co., Ltd. silicon-containing spin-on hard mask SHB-A940 (silicon content: 43 mass%) formed thereon. The film was prebaked (PAB) for 60 seconds using a hot plate at the temperature listed in Table 3 to form a 40 nm thick resist film. The resist film was then exposed using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9, 90-degree dipole illumination) to form a 48 nm line-to-space (LS) pattern with a 1:1 ratio. PEB was then performed on the hot plate for 60 seconds at the temperature listed in Table 3, followed by development for 30 seconds using the developer listed in Table 3 to form an LS pattern with a 24 nm line width and a 48 nm pitch.

[0138] The obtained resist pattern was subjected to the following evaluation. The results are shown in Table 3.

[0139] [Sensitivity evaluation]

[0140] The LS pattern was observed using a Hitachi High-Tech (CG-6300) measurement SEM to obtain the optimum exposure dose Eop (mJ / cm) for obtaining an LS pattern with a pitch width of 24 nm and a pitch of 48 nm. 2 ) and let it be sensitivity.

[0141] [LWR evaluation]

[0142] For the LS pattern obtained by irradiation at the optimal exposure dose, the dimensions of the pattern were measured at 10 locations along the pitch width longitudinal direction using a Hitachi High-Tech Co., Ltd. length measurement SEM (CG-6300). The results were used to calculate the value (3σ) times the standard deviation (σ), and this value was defined as the LWR (nm). The smaller this value, the less roughness and the more uniform the wide-pitch pattern.

[0143] [Limiting resolution evaluation]

[0144] The exposure dose was gradually increased from the optimal exposure dose for forming the LS pattern. Using a Hitachi High-Tech Co., Ltd. CG-6300 SEM, the line width (nm) at which resolution was achieved during pattern formation was determined. This value was designated as the limiting resolution (nm). A smaller value indicates a better limiting resolution, and finer patterns can be formed.

[0145] [Table 3]

[0146]

[0147]

[0148] Developer: nBA (butyl acetate)

[0149] TMAH (2.38 mass% tetramethylammonium hydroxide aqueous solution)

[0150] [3] EUV lithography evaluation (line and space patterning, negative tone development)

[0151] [Examples 3-1 to 3-16, Comparative Examples 3-1 to 3-3]

[0152] Each resist composition (R-01 to R-16, CR-01 to CR-03) was spin-coated onto a Si substrate having a 20 nm thick film of a Shin-Etsu Chemical Co., Ltd. silicon-containing spin-on hard mask SHB-A940 (silicon content: 43 mass%) formed thereon. The film was then prebaked (PAB) for 60 seconds using a hot plate at the temperature listed in Table 4 to form a 40 nm thick resist film. The resist film was then exposed using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9, 90-degree dipole illumination) to form a 48 nm line-to-space (LS) pattern with a 1:1 ratio. PEB was then performed on a hot plate for 60 seconds at the temperature listed in Table 4, followed by development for 30 seconds using the developer listed in Table 4 to form an LS pattern with a 24 nm line width and a 48 nm pitch.

[0153] The obtained resist pattern was subjected to the following evaluation. The results are shown in Table 4.

[0154] [Sensitivity evaluation]

[0155] The above pattern was observed using a Hitachi High-Tech (CG-6300) long-range SEM to obtain an optimum exposure dose Eop (mJ / cm2) for obtaining an LS pattern with a pitch width of 24 nm and a pitch of 48 nm. 2 ) and let it be sensitivity.

[0156] [LWR evaluation]

[0157] For the LS pattern obtained by irradiation at the optimal exposure dose, the dimensions of the pattern were measured at 10 locations along the pitch width longitudinal direction using a Hitachi High-Tech Co., Ltd. length measurement SEM (CG-6300). The results were used to calculate the value (3σ) times the standard deviation (σ), and this value was defined as the LWR (nm). The smaller this value, the less roughness and the more uniform the wide-pitch pattern.

[0158] [Limiting resolution evaluation]

[0159] The exposure dose was gradually increased from the optimal exposure dose for forming the LS pattern. Using a Hitachi High-Tech Co., Ltd. CG-6300 SEM, the line width (nm) at which resolution was achieved during pattern formation was determined. This value was designated as the limiting resolution (nm). A smaller value indicates a better limiting resolution, and finer patterns can be formed.

[0160] [Table 4]

[0161]

[0162]

[0163] The results shown in Tables 3 and 4 indicate that the resist composition of the present invention exhibits excellent sensitivity, LWR, and resolution when forming an LS pattern by EUV exposure, regardless of whether the development is positive-tone or negative-tone.

[0164] [4] EUV lithography evaluation (contact hole pattern)

[0165] [Examples 4-1 to 4-16, Comparative Examples 4-1 to 4-3]

[0166] Each resist composition (R-01 to R-15, CR-01 to CR-03) was spin-coated onto a Si substrate having a 20 nm thick silicon-containing spin-on hard mask SHB-A940 (silicon content: 43 mass%) manufactured by Shin-Etsu Chemical Co., Ltd., formed thereon. The resist film was prebaked (PAB) for 60 seconds using a hot plate at the temperature listed in Table 5 to form a 50 nm thick resist film. The resist film was then exposed using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadrupole illumination, mask with a hole pattern having a 64 nm pitch and a +20% offset on the wafer). PEB was performed on a hot plate for 60 seconds at the temperature listed in Table 5, followed by development for 30 seconds using the developer listed in Table 5 to obtain a hole pattern having a size of 32 nm.

[0167] The obtained resist pattern was subjected to the following evaluation. The results are shown in Table 5.

[0168] [Sensitivity evaluation]

[0169] The contact hole pattern was observed using a Hitachi High-Tech (CG-6300) long-range SEM to determine the optimal exposure dose Eop (mJ / cm) for obtaining a hole pattern with a size of 32 nm. 2 ) and let it be sensitivity.

[0170] [CD Uniformity (CDU) Evaluation]

[0171] The dimensions of 50 holes in the pattern obtained by irradiation with the optimal exposure dose were measured, and the value (3σ) tripled by the standard deviation (σ) obtained from the results was set as CDU (nm). The smaller this value, the more uniform the hole diameter pattern can be obtained.

[0172] [Limiting resolution evaluation]

[0173] The exposure dose was gradually reduced from the optimal exposure dose for forming the aforementioned hole pattern. Using a Hitachi High-Tech Co., Ltd. long-range SEM (CG-6300), the limiting hole diameter (nm) at which the hole pattern could be resolved was determined. This value was designated as the limiting resolution (nm). A smaller value indicates a better limiting resolution, and a pattern with a finer hole diameter can be obtained.

[0174] [Table 5]

[0175]

[0176] The results shown in Table 5 show that the resist composition of the present invention is excellent in sensitivity, CDU, and resolution in contact hole pattern formation by EUV exposure.

Claims

1. A resist composition comprising: a supervalent bismuth compound, a carboxylic acid compound, and a solvent.

2. The resist composition according to claim 1, wherein The supervalent bismuth compound is represented by the following formula (1): Wherein, p, q and r are each independently an integer from 0 to 5; R 1 and R 2 are independently a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may contain a hetero atom; and R 1 and R 2 They may also bond to each other and to the carbon atoms to which they are bonded and the atoms between the carbon atoms to form a ring; R 3 、R 4 and R 5 Each independently represents a halogen atom or a hydrocarbon group having 1 to 40 carbon atoms which may contain a heteroatom.

3. The resist composition according to claim 1, wherein The carboxylic acid compound is represented by the following formula (2): Wherein, m is an integer from 1 to 4; R 11 is an m-valent hydrocarbon group having 1 to 40 carbon atoms or an m-valent heterocyclic group having 2 to 40 carbon atoms, and when m is 2, R 11 It may also be an ether bond, a carbonyl group, an azo group, a thioether bond, a carbonate bond, a carbamate bond, a sulfinyl group, or a sulfonyl group; furthermore, a part or all of the hydrogen atoms of the m-valent hydrocarbon group or the m-valent heterocyclic group may be substituted with a group containing a heteroatom, and a part of the -CH2- of the m-valent hydrocarbon group may be substituted with a group containing a heteroatom; R 12 is a single bond or an alkylene group having 1 to 10 carbon atoms, and part or all of the hydrogen atoms of the alkylene group may be substituted by a group containing a heteroatom, and part of the -CH2- of the alkylene group may be substituted by a group containing a heteroatom; when m is 2 to 4, each R 12 They can be the same or different.

4. A pattern forming method comprising the following steps: forming a resist film on a substrate using the resist composition according to any one of claims 1 to 3, The resist film is exposed to high energy radiation, and The exposed resist film is developed using a developer.

5. The pattern forming method according to claim 4, wherein The high-energy rays are electron beams or extreme ultraviolet rays.

6. The pattern forming method according to claim 4, wherein The developer dissolves the exposed portion and does not dissolve the unexposed portion.

7. The pattern forming method according to claim 4, wherein: The developer dissolves the unexposed portion but does not dissolve the exposed portion.

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