Resist composition and pattern formation method

Abstract

The present invention provides a resist composition that is highly sensitive, stable, and easy to handle in photolithography using high-energy beams, and a pattern formation method using the resist composition. [Solution] A resist composition characterized by comprising a germanium compound represented by the following general formula (1) and an organic solvent. TIFF2026166287000049.tif51102

Description

[Technical Field]

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

[0002] With the expansion of the IoT market, there is an increasing demand for higher integration, higher speed, and lower power consumption in LSIs, leading to rapid miniaturization of pattern rules. Logic devices, in particular, are driving this miniaturization. As cutting-edge miniaturization technology, mass production of 10nm node devices is underway using double, triple, and quadruple patterning in ArF immersion lithography, and research is progressing on 7nm node devices using next-generation 13.5nm extreme ultraviolet (EUV) lithography.

[0003] As miniaturization progresses, image blurring due to acid diffusion has become a problem (Non-Patent Literature 1). To ensure resolution in fine patterns of processing dimensions of 45 nm generation and beyond, it has been suggested that controlling acid diffusion is important, in addition to the conventionally proposed improvement of dissolution contrast (Non-Patent Literature 2). However, since chemically amplified resist compositions increase sensitivity and contrast through acid diffusion, if acid diffusion is suppressed to the extreme by lowering the post-exposure bake (PEB) temperature or shortening the PEB time, sensitivity and contrast decrease significantly.

[0004] Adding an acid generator that produces bulky acids to suppress acid diffusion is effective. Therefore, copolymerizing an onium salt acid generator with a polymerizable olefin into a polymer has been proposed. However, for pattern formation of resist films with processing dimensions of 16 nm and beyond, chemically amplified resist compositions are considered insufficient from the standpoint of acid diffusion, and the development of non-chemically amplified resist compositions is desired.

[0005] Polymethyl methacrylate (PMMA) is an example of a material for non-chemically amplified resist compositions. PMMA is a positive-type resist material whose main chain is cleaved by electron beam (EB) or EUV irradiation, reducing its molecular weight and improving its solubility in organic solvent developers. However, it lacks a ring structure, resulting in drawbacks such as low etching resistance and high outgassing during exposure.

[0006] Hydrogen silsesquioxane (HSQ) is a material for negative-type resist compositions that becomes insoluble in alkaline developers due to crosslinking by silanol condensation reactions caused by EB or EUV irradiation. Chlorine-substituted calixarenes also function as materials for negative-type resist compositions. These materials have small molecular sizes before crosslinking and do not blur due to acid diffusion, resulting in low edge roughness and very high resolution, and are used as pattern transfer materials to demonstrate the resolution limit of exposure equipment. However, these materials have insufficient sensitivity and require further improvement.

[0007] One factor that makes material development for EUV lithography difficult is the low number of photons in EUV exposure. The energy of EUV is far higher than that of ArF excimer laser light, and the number of photons in EUV exposure is 1 / 14th of that of ArF exposure. Furthermore, the dimensions of patterns formed by EUV exposure are less than half those of ArF exposure. For this reason, EUV exposure is susceptible to variations in the number of photons. Variations in the number of photons in the ultrashort wavelength synchrotron radiation region are a physical phenomenon called shot noise, and this effect cannot be eliminated. For this reason, so-called stochastics is attracting attention. Although the effect of shot noise cannot be eliminated, how to reduce this effect is being discussed. In addition to increasing dimensional uniformity (CDU) and line width roughness (LWR) due to the effect of shot noise, a phenomenon of hole blockage has been observed with a probability of one in several million. When holes are blocked, it results in poor electrical conductivity and the transistor does not operate, so it negatively affects the overall performance of the device.

[0008] As a method to reduce the effects of shot noise on the resist side, inorganic resist compositions using elements with high EUV absorption as the core have been proposed (Patent Document 1). However, although inorganic resist compositions are relatively sensitive, they are still not sufficient and have many problems such as insufficient solubility in solvents for resist compositions, storage stability, and defects.

[0009] Non-patent document 3 proposes a negative-type resist composition using a tin compound. This is a non-chemically amplified resist composition mainly composed of tin, which has high EUV light absorption. While it shows improved stochastics and significantly improved sensitivity and resolution, it suffers from stability issues, such as degradation of the resist composition during storage and changes in performance due to post-PEB delay (PPD) after PEB. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2015-108781 [Non-patent literature]

[0011] [Non-Patent Document 1] SPIE Vol.5039 p1 (2003) [Non-Patent Document 2] SPIE Vol.6520 p65203L-1 (2007) [Non-Patent Document 3] SPIE Vol.9051 p90511B-1 (2014) [Overview of the project] [Problems that the invention aims to solve]

[0012] The present invention has been made in view of the above circumstances, and an object thereof is to provide a resist composition that is excellent in sensitivity, stable, and easy to handle in photolithography using high-energy rays, and a pattern forming method using the resist composition. [Means for Solving the Problems]

[0013] In order to solve the above problems, the present invention provides a resist composition comprising a germanium compound represented by the following general formula (1) and an organic solvent. [Chemical Formula] (In the formula, R1 is a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. X - is an anion represented by a halide ion, nitrate ion, hydrogen sulfate ion, hydrogen carbonate ion, or tetraphenylborate ion, and Y + is a sulfonium cation represented by the following general formula (cation-1), an iodonium cation represented by the following general formula (cation-2), or an ammonium cation represented by the following general formula (cation-3).) [Chemical Formula] (In the formula, R ct1 to R ct9 are each independently a halogen atom, or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom.)

[0014] Such a resist composition becomes a resist composition that is excellent in sensitivity, stable, and easy to handle in photolithography using high-energy rays.

[0015] In the present invention, it is preferable that the resist composition further contains an organometallic compound having a metal atom selected from cobalt, nickel, copper, zinc, silver, indium, tin, antimony, tellurium, and platinum.

[0016] Such a resist composition will have improved stochastics and excellent sensitivity and LWR.

[0017] Furthermore, the present invention provides a pattern formation method comprising the steps of: forming a resist film on a substrate using the resist composition described above; exposing the resist film with high-energy rays; and developing the exposed resist film to form a resist pattern.

[0018] Such a pattern formation method provides a method for using a resist composition that is highly sensitive, stable, and easy to handle in photolithography using high-energy beams.

[0019] In this case, it is preferable to use an electron beam or extreme ultraviolet light as the high-energy beam.

[0020] In the pattern formation method of the present invention, it is preferable to use such high-energy rays. [Effects of the Invention]

[0021] As described above, the resist composition of the present invention is extremely useful in forming fine patterns because it exhibits excellent sensitivity, good stability, and ease of handling in photolithography using high-energy rays, particularly in EB lithography and EUV lithography. [Modes for carrying out the invention]

[0022] As described above, in photolithography using high-energy beams, there has been a need for the development of a resist composition that is highly sensitive, stable, and easy to handle, as well as a pattern formation method using the said resist composition.

[0023] As a result of diligent research to achieve the above objective, the inventors of the present invention have found that a resist composition mainly composed of a germanium compound having a specific structure exhibits excellent sensitivity and provides a resist film with excellent stability, making it extremely effective for precise microfabrication, and thus have come to the present invention.

[0024] In other words, the present invention is a resist composition comprising a germanium compound represented by the following general formula (1) and an organic solvent. [ka] (In the formula, R1 is a hydrocarbyl group having 1 to 10 carbon atoms, which may contain a hydrogen atom or a heteroatom. X - Y is an anion represented by a halide ion, nitrate ion, bisulfate ion, bicarbonate ion, or tetraphenylborate ion. + This is a sulfonium cation represented by the following general formula (cation-1), an iodonium cation represented by the following general formula (cation-2), or an ammonium cation represented by the following general formula (cation-3). [ka] (In the formula, R ct1 ~R ct9 Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain a halogen atom or a heteroatom.

[0025] The present invention will be described in detail below, but the present invention is not limited to these descriptions.

[0026] [Resist composition] The resist composition of the present invention comprises a predetermined germanium compound and an organic solvent.

[0027] [Germanium compounds] The germanium compound mentioned above is represented by the following general formula (1). [ka] (In the formula, R1 is a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a hetero atom. X - is an anion represented by a halide ion, nitrate ion, hydrogen sulfate ion, hydrogen carbonate ion, or tetraphenylborate ion, and Y + is a sulfonium cation represented by the following general formula (cation-1), an iodonium cation represented by the following general formula (cation-2), or an ammonium cation represented by the following general formula (cation-3).)

Chemical Formula

[0028] In the above general formula (1), R1 is a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a hetero atom.

[0029] The hydrocarbyl group having 1 to 10 carbon atoms represented by R1 may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 10 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, tert-pentyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group; cyclopentyl group, cyclohexyl group, cyclopentylmethyl group, cyclopentylethyl group, cyclopentylbutyl group, cyclohexylmethyl group, cyclohexylethyl group, cyclohexylbutyl group, norbornyl group, tricyclo[5.2.1.0 2,6Examples include cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as decanyl groups and adamantyl groups; alkenyl groups having 6 to 10 carbon atoms, such as vinyl groups and allyl groups; aryl groups having 6 to 10 carbon atoms, such as phenyl groups and naphthyl groups; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the -CH2- groups of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, the group may contain hydroxyl groups, cyano groups, halogen atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic acid anhydrides (-C(=O)-OC(=O)-), etc.

[0030] Specific examples of germanium compounds represented by the above general formula (1) are listed below, but are not limited to these. Note that in the following formula, X - and Y + It has been omitted.

[0031] [ka]

[0032] In the above general formula (1), X - These are anions represented by halide ions, nitrate ions, bisulfate ions, bicarbonate ions, or tetraphenylborate ions.

[0033] In the above general formula (1), Y + This is a sulfonium cation represented by the above general formula (cation-1), an iodonium cation represented by the above general formula (cation-2), or an ammonium cation represented by the above general formula (cation-3).

[0034] In the above general formulas (cation-1), (cation-2), and (cation-3), R ct1 ~R ct9Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain a halogen atom or a heteroatom.

[0035] R ct1 ~R ct9 Examples of halogen atoms represented by this formula include fluorine, chlorine, bromine, and iodine atoms.

[0036] R ct1 ~R ct9 The hydrocarbyl group, represented by , having 1 to 30 carbon atoms, may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C30 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl groups; C3-C30 cyclic saturated hydrocarbyl groups such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; C2-C30 alkenyl groups such as vinyl, allyl, propenyl, butenyl, and hexenyl groups; C3-C30 cyclic unsaturated hydrocarbyl groups such as cyclohexenyl groups; C6-C30 aryl groups such as phenyl, naphthyl, and thienyl groups; C7-C30 aralkyl groups such as benzyl, 1-phenylethyl, and 2-phenylethyl groups; and groups obtained by combining these, but aryl groups are preferred. Furthermore, 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, sulfur atom, nitrogen atom, or halogen atom, and some of the -CH2- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, or nitrogen atom, and as a result, it may contain a hydroxyl 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)-OC(=O)-), a haloalkyl group, etc.

[0037] Also, R ct1 and Rct2 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. In this case, the structure of the ring may be represented by the following formula, etc.

[0038] [ka] (In the formula, the dashed line represents R ct3 (This is a combination of the two.)

[0039] Specific examples of sulfonium cations represented by the above general formula (cation-1) are listed below, but are not limited to these.

[0040] [ka]

[0041] [ka]

[0042] [ka]

[0043] [ka]

[0044] [ka]

[0045] [ka]

[0046] [ka]

[0047]

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[0048]

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[0049]

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[0050]

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[0051]

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[0052]

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[0053]

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[0058] [ka]

[0059] [ka]

[0060] [ka]

[0061] [ka]

[0062] [ka]

[0063] [ka]

[0064] [ka]

[0065] [ka]

[0066] [ka]

[0067] Specific examples of iodonium cations represented by the above general formula (cation-2) are listed below, but are not limited to these.

[0068] [ka]

[0069] [ka]

[0070] Specific examples of ammonium cations represented by the above general formula (cation-3) include, but are not limited to, those listed below.

[0071] [ka]

[0072] The germanium compounds may be used individually or in combination of two or more. Furthermore, the germanium compounds can be synthesized, for example, based on the description in Chem. Eur. J., 25, 7860-7865.

[0073] [Organic solvents] The resist composition of the present invention contains an organic solvent. The organic solvent is not particularly limited as long as it can dissolve the germanium compound and form a film. Examples of such organic solvents include ketones such as cyclohexanone and methyl-2-n-pentyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol; ethers such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; and propylene glycol monomethyl ether acetate. Examples of solvents include esters such as glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 2-hydroxyisobutyrate, tert-butyl acetate, cyclohexyl acetate, tert-butyl propionate, and propylene glycol monotert-butyl ether acetate; lactones such as γ-butyrolactone; carboxylic acids such as acetic acid and propionic acid; aromatics such as toluene, xylene, cresol, anisole, and benztrifluoride; halogenated hydrocarbons such as dichloromethane, chloroform, and carbon tetrachloride; and mixed solvents of these.

[0074] The content of the organic solvent is preferably 200 to 20,000 parts by mass, and more preferably 500 to 15,000 parts by mass, per 100 parts by mass of the germanium compound.

[0075] The resist composition of the present invention is presumed to exhibit a change in development resistance between exposed and unexposed areas, resulting in contrast, due to the photodegradation of the germanium compound, which is the main component, and subsequent aggregation or crosslinking reactions between the partially degraded germanium compounds. Since this reaction is not catalytic, the resist composition of the present invention functions as a non-chemically amplified resist composition. Therefore, it can resolve even fine regions where pattern formation is difficult with conventional chemically amplified resist compositions mainly composed of multi-component polymers. Furthermore, since the germanium compound converges to a thermally stable structure, it also exhibits excellent storage stability. In addition, its performance does not change significantly over time after PEB (Photobleaching Embedding).

[0076] Because the germanium-carbon bond in the aforementioned germanium compound is energetically weak, it is thought that a cleavage reaction can efficiently occur upon light irradiation.

[0077] [Organometallic compound] In the present invention, it is preferable that the resist composition further comprises an organometallic compound having a metal atom selected from cobalt, nickel, copper, zinc, silver, indium, tin, antimony, tellurium, and platinum.

[0078] In EUV lithography, the aforementioned metal atoms have high EUV absorption capacity, so adding them to the resist composition improves stochastics and results in a resist composition with excellent sensitivity and LWR.

[0079] The aforementioned organometallic compounds can also be used in combination in order to adjust their properties, particularly radiation absorption.

[0080] The aforementioned organometallic compound can have any structure, but it is preferable that the compound has a small amount of organic compound components in its structure and has high EUV absorption capacity as a whole molecule, and it is desirable that the compound dissolves in the organic solvent used to dissolve the resist and can be spin-coated onto the substrate in an amorphous state.

[0081] [Photoacid Generator] The resist composition of the present invention may also contain a photoacid generator as a component other than the germanium compound and the organic solvent. By using a photoacid generator, it is expected that acid will be generated in the exposed area, thereby promoting the crosslinking reaction of the germanium compound. The photoacid generator is not particularly limited as long as it generates acid when irradiated with high-energy rays, and conventional photoacid generators known for chemically amplified resist compositions can be used, but those that generate sulfonic acid, imido acid, or methidoic acid are particularly preferred. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, oxime-O-sulfonate type acid generators, etc. Specific examples of the photoacid generators include those described in paragraphs

[0122] to

[0142] of Japanese Patent Application Publication No. 2008-111103 and those described in paragraphs

[0127] to

[0193] of Japanese Patent Application Publication No. 2022-163697.

[0082] If the resist composition of the present invention contains the photoacid generator, its content is preferably 0.01 to 20% by mass of the total solid content. In this invention, "solid content" refers to all components of the resist composition other than organic solvents. The photoacid generator may be used alone or in combination of two or more types.

[0083] [Radical scavenger] The resist composition of the present invention may also contain a radical scavenger as another component. By adding a radical scavenger, the photoreaction during photolithography can be controlled and the sensitivity can be adjusted.

[0084] Examples of the radical scavengers that can be used include hindered phenols, quinones, hindered amines, and thiol compounds. Specific examples of hindered phenols include dibutylhydroxytoluene and 2,2'-methylenebis(4-methyl-6-tert-butylphenol). Specific examples of quinones include 4-methoxyphenol (methoquinone) and hydroquinone. Specific examples of hindered amines include 2,2,6,6-tetramethylpiperidine and 2,2,6,6-tetramethylpiperidine-N-oxy radical. Specific examples of thiol compounds include dodecanethiol and hexadecanethiol.

[0085] If the resist composition of the present invention contains the radical scavenger, its content is preferably 0.01 to 10% by mass of the total solid content. The radical scavenger may be used alone or in combination of two or more types.

[0086] [Surfactants] The resist composition of the present invention may also contain a surfactant as another component. Examples of such surfactants can be found in Japanese Patent Publication No. 2010-215608 and Japanese Patent Publication No. 2011-016746. Among those described therein, FC-4430 (manufactured by 3M), Surflon® S-381 (manufactured by AGC Seimi Chemical Co., Ltd.), Olfin® E1004 (manufactured by Nisshin Chemical Industry Co., Ltd.), KH-20, KH-30 (manufactured by AGC Seimi Chemical Co., Ltd.), and oxetane ring-opening polymers represented by the following general formula (surf-1) are preferred. [ka]

[0087] In the above general formula (surf-1), R is a divalent to tetravalent aliphatic group having 2 to 5 carbon atoms. Examples of divalent aliphatic groups include ethylene, 1,4-butylene, 1,2-propylene, 2,2-dimethyl-1,3-propylene, and 1,5-pentylene groups, while examples of trivalent or tetravalent aliphatic groups are listed below. [ka] (In the formula, the dashed lines represent bonds, which are substructures derived from glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol, respectively.)

[0088] Among these, the 1,4-butylene group and the 2,2-dimethyl-1,3-propylene group are preferred.

[0089] Rf is a trifluoromethyl group or a pentafluoroethyl group, preferably a trifluoromethyl group. m is an integer from 0 to 3, n is an integer from 1 to 4, and the sum of n and m is the valence of R, an integer from 2 to 4. A is 1. B is an integer from 2 to 25, preferably an integer from 4 to 20. C is an integer from 0 to 10, preferably 0 or 1. Furthermore, the arrangement of each constituent unit in the above general formula (surf-1) is not specified, and they may be bonded in a block-like manner or randomly. For details on the production of partially fluorinated oxetane ring-opening polymer surfactants, please refer to U.S. Patent No. 5,650,483, etc.

[0090] If the resist composition of the present invention contains the surfactant, its content is preferably 0.001 to 20 parts by mass, and more preferably 0.1 to 10 parts by mass, per 100 parts by mass of the germanium compound. The surfactant may be used alone or in combination of two or more types.

[0091] [Pattern formation method] When the resist composition of the present invention is used in the manufacture of various integrated circuits, known lithography techniques can be applied. For example, a pattern formation method can be described, which includes the steps of forming a resist film on a substrate using the resist composition, exposing the resist film with high-energy rays, and developing the exposed resist film to form a resist pattern.

[0092] First, the resist composition of the present invention is applied to a substrate for integrated circuit manufacturing (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective coating, etc.) or a substrate for mask circuit manufacturing (Cr, CrO, CrON, MoSi2, SiO2, etc.) by a suitable coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, or doctor coating, so that the coating film thickness is 0.01 to 2 μm. This is then heated on a hot plate. Preferably, it is heated at 60 to 200°C for 10 seconds to 30 minutes, more preferably at 80 to 180°C for 30 seconds to 20 minutes to form a resist film.

[0093] Next, the resist film is exposed using a high-energy beam. Examples of high-energy beams include ultraviolet light, far ultraviolet light, electron beams (EB), extreme ultraviolet (EUV) with a wavelength of 2 to 15 nm including the water window, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation. It is preferable to use an electron beam or extreme ultraviolet light as the high-energy beam. For EUV, a wavelength of 2 to 13.5 nm is more preferable. When using ultraviolet light, far ultraviolet light, EUV, X-rays, soft X-rays, excimer laser light, gamma rays, synchrotron radiation, etc. as the high-energy beam, the exposure amount is preferably 1 to 200 mJ / cm², either directly or using a mask to form the desired pattern. 2 To the extent, more preferably 10-150 mJ / cm² 2 Irradiate to a degree that results in the desired level of exposure. When using electroluminescence (EB) as the high-energy beam, the exposure amount is preferably 0.1 to 5000 μC / cm², either directly or using a mask to form the desired pattern. 2 To a degree, more preferably 0.5 to 4000 μC / cm² 2The pattern is drawn to a certain extent. Furthermore, the resist composition of the present invention is particularly suitable for fine patterning using EB or EUV, among other high-energy rays.

[0094] PEB may be performed to accelerate or complete the reaction after photodegradation. If PEB is performed, it is preferable to carry it out on a hot plate or in an oven after exposure, preferably at 30-200°C for 10 seconds to 30 minutes, more preferably at 60-180°C for 30 seconds to 20 minutes.

[0095] The development method performed after exposure or PEB can be either wet development or dry development. In the case of wet development, alkaline development or organic solvent development can be applied, but organic solvent development is preferred when forming a pattern with the resist composition of the present invention. Wet development is preferably performed on the exposed resist film by conventional methods such as dipping, puddling, or spraying for 3 seconds to 3 minutes, more preferably 5 seconds to 2 minutes, to form the desired pattern. Since the resist composition of the present invention is negative type, the parts that are irradiated with light become insoluble in the developer, and the parts that are not exposed dissolve.

[0096] Organic solvents used as developing solutions include alkaline aqueous solutions such as tetramethylammonium hydroxide aqueous solution and tetrabutylammonium hydroxide aqueous solution; 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutylketone, 5-methyl-2-hexanone, methylcyclohexanone, acetophenone, methylacetophenone, isopropyl alcohol, isoamyl alcohol, n-butanol, tert- Butyl alcohol, tert-pentyl alcohol, n-pentanol, cyclohexanol, formic acid, acetic acid, propionic acid, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butenyl acetate, isopentyl acetate, cyclohexyl acetate, 4-tert-butylcyclohexyl acetate, octyl acetate, isobornyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonic acid, ethyl crotonic acid, propionic acid Methyl ionsate, 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, ethyl phenyl acetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, 2-phenylethyl acetate, 1- Examples of organic solvents include propanol, 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 3-methyl-1-butanol, diacetone alcohol, 4-methyl-2-pentanol, 3-methylcyclohexanol, 3,5,5-trimethylhexyl alcohol, 2,6-dimethyl-4-heptanol, toluene, anisole, ε-caprolactone, octane, nonane, decane, undecane, and dodecane. These developers may be used individually or in mixtures of two or more.

[0097] After development, rinsing is performed as needed. A solvent that mixes with the developer but does not dissolve the resist film is preferred as the rinsing solution. Preferred solvents include C3-C10 alcohols, C8-C12 ether compounds, C6-C12 alkanes, alkenes, alkynes, and aromatic solvents.

[0098] Specific examples of the C3-C10 alcohols 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, and 3-hexanol. Examples include 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 others.

[0099] Specific examples of the ether compounds 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, and di-n-hexyl ether.

[0100] Specific examples of the C6-C12 alkanes include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, and cyclononane. Specific examples of the C6-C12 alkenes include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, and cyclooctene. Specific examples of the C6-C12 alkynes include hexine, heptine, and octine.

[0101] Specific examples of the aforementioned aromatic solvents having 6 to 12 carbon atoms include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, and mesitylene.

[0102] Rinsing can reduce the occurrence of deformation and defects in the resist pattern. However, rinsing is not always necessary, and omitting it can reduce the amount of solvent used.

[0103] Dry development is also applicable as a developing method in the pattern formation method of the present invention. Dry development is a development method in which either the exposed or unexposed areas are removed by an etching process using gas, without using a developing solution. In the present invention, a desired pattern can be formed by removing the unexposed areas with etching gas. Dry etching preferably uses a gas containing oxygen, hydrogen, ammonia, halogen, etc., along with a diluent gas containing nitrogen, helium, argon, carbon dioxide, or carbon monoxide. [Examples]

[0104] The present invention will be specifically described below using examples and comparative examples, but the present invention is not limited to these.

[0105] [1] Synthesis of germanium compounds G-1 and G-2 Germanium compounds G-1 and G-2 were synthesized based on Chem.Eur.J.,25,7860-7865.

[0106] [ka]

[0107] [2] Preparation of resist composition [Examples 1-1 to 1-26, Comparative Example 1-1] The resist compositions R-01 to R-26 of the present invention, and the comparative resist composition RC-01, were prepared by dissolving each component in a solvent in the compositions shown in Table 1 below and filtering the resulting solutions through a 0.2 μm Teflon® filter.

[0108] [Table 1]

[0109] In Table 1, component A is an organometallic compound, component B is a photoacid generator, and component C is a radical scavenger. The structures of compounds (M-1) to (M-10) used as component A are as follows. M-1 (tin compound) was synthesized according to Angewandte Chemie, International Edition (2017), 56(34), 10140-10144, and M-2 to M-10 were purchased commercially. Details of components B and C are as follows.

[0110] (Component A) [ka]

[0111] (Component B) P-1: Triphenylsulfonium tosylate

[0112] (Component C) ·Sc-1: Dibutylhydroxytoluene

[0113] • Solvent: PGMEA (Propylene glycol monomethyl ether acetate) 4M2P (4-methyl-2-pentanol)

[0114] [3] EB lithography evaluation [Examples 2-1 to 2-26, Comparative Example 2-1] Each resist composition (R-01 to R-26, RC-01) was spin-coated onto a Si substrate coated with Nissan Chemical Corporation's DUV-42 anti-reflective film to a thickness of 60 nm. A 40 nm thick resist film was then fabricated by pre-baking at 100°C for 60 seconds using a hot plate. The resist film was exposed using an Elionix EB lithography system (ELS-F125, accelerating voltage 125 kV), and a pattern was formed by performing PEB on a hot plate at the temperatures listed in Table 2 for 60 seconds, followed by development using 2-heptanone as the developer for 30 seconds. As a result, a negative-type line-and-space (LS) pattern with a space width of 20 nm and a pitch of 40 nm was obtained. The sensitivity, LWR, and limiting resolution of the obtained LS pattern were evaluated according to the method described below. The results are shown in Table 2.

[0115] [Sensitivity evaluation] The aforementioned LS pattern was observed using an electron microscope, and the optimal exposure dose Eop(μC / cm²) was determined to obtain an LS pattern with a space width of 20 nm and a pitch of 40 nm. 2 We calculated this value and defined it as the sensitivity.

[0116] [LWR rating] The LS pattern obtained by irradiating with the optimal exposure was measured at 10 points along the longitudinal direction of the space width using a Hitachi High-Tech CD-SEM (CG-5000). From these results, three times the standard deviation (σ) (3σ) was calculated and defined as the LWR. The smaller this value, the less roughness and the more uniform the space width pattern obtained.

[0117] [Evaluation of Limit Resolution] The minimum line width (nm) at which a pattern can be formed by gradually increasing the exposure from the optimal exposure was determined using a Hitachi High-Tech SEM (CG-6300), and this was defined as the limiting resolution (nm). A smaller value indicates superior limiting resolution and the ability to form finer patterns.

[0118] [Post-exposure storage stability evaluation] After exposure at the optimal exposure level, PEB and development were performed under the conditions described above. Two types of wafers were prepared: one developed without post-PEB resting (PPD0h) and another developed after 6 hours of post-PEB resting (PPD6h). The line widths of these wafers were determined using a Hitachi High-Technologies Corporation length measuring SEM (CG-6300), and the change in line width (CD) due to post-exposure resting (ΔPPD) was calculated. The results are shown in Table 2.

[0119] [Table 2]

[0120] The results shown in Table 2 demonstrate that the resist composition of the present invention exhibits excellent LWR and limiting resolution in negative pattern formation using organic solvent development with EB lithography. Furthermore, it was confirmed that there was little change in CD even after exposure and that the resist remained stable after pattern formation.

[0121] [4] Storage stability evaluation [Examples 3-1 to 3-26, Comparative Example 3-1] Under room temperature conditions (20±5℃), each resist composition (R-01 to R-26, CR-01) was left for a specified period, and the presence or absence of precipitation was visually confirmed. Compositions that could be stored without precipitation for 6 months or more were marked with ○, while those that developed precipitation in less than 6 months were marked with ×. The results are shown in Table 3.

[0122] [Table 3]

[0123] The results shown in Table 3 demonstrate that the resist composition of the present invention exhibits excellent storage stability and is easy to handle.

[0124] [5] EUV lithography evaluation (line and space pattern) [Examples 4-1 to 4-4] Each resist composition (R-01, R-02, R-14, R-15) was spin-coated onto a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. had been formed to a thickness of 20 nm. The resist film was then pre-baked (PAB) at 100°C for 60 seconds using a hot plate to produce a resist film with a thickness of 40 nm. A 36 nm line-and-space (LS) 1:1 pattern was exposed onto the resist film using an ASML EUV scanner NXE3400 (NA0.33, σ0.9, 90-degree dipole illumination). PEB was then performed on a hot plate at the temperatures listed in Table 4 for 60 seconds, followed by development with 2-heptanone for 30 seconds to form an LS pattern with a space width of 18 nm and a pitch of 36 nm.

[0125] The obtained resist patterns were evaluated as follows. The results are shown in Table 4.

[0126] [Sensitivity evaluation] The aforementioned LS pattern was observed using a Hitachi High-Tech SEM (CG-6300) to determine the optimal exposure dose Eop(mJ / cm²) for obtaining an LS pattern with a space width of 18 nm and a pitch of 36 nm. 2 We calculated this value and defined it as the sensitivity.

[0127] [LWR rating] The LS pattern obtained by irradiating with the optimal exposure was measured at 10 points along the longitudinal direction of the space width using a Hitachi High-Tech SEM (CG-6300), and the LWR was calculated as three times the standard deviation (σ) (3σ) from the results. The smaller this value, the less roughness and the more uniform the space width pattern obtained.

[0128] [Evaluation of Limit Resolution] The minimum line width (nm) at which the pattern can be resolved by gradually increasing the exposure from the optimal exposure for forming the aforementioned LS pattern was determined using a Hitachi High-Tech SEM (CG-6300), and this was defined as the limiting resolution (nm). A smaller value indicates superior limiting resolution and the ability to form finer patterns.

[0129] [Table 4]

[0130] The results shown in Table 4 demonstrate that the resist composition of the present invention exhibits excellent LWR and limiting resolution in negative pattern formation by organic solvent development using EUV lithography. Furthermore, it was found that the addition of organometallic compounds with high EUV light absorption enables the formation of patterns with superior sensitivity, LWR, and resolution.

[0131] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention.

Claims

1. A resist composition characterized by comprising a germanium compound represented by the following general formula (1) and an organic solvent. 【Chemistry 1】 (In the formula, R １ This is a hydrocarbyl group having 1 to 10 carbon atoms, which may contain a hydrogen atom or a heteroatom. － Y is an anion represented by a halide ion, nitrate ion, bisulfate ion, bicarbonate ion, or tetraphenylborate ion. ＋ This is a sulfonium cation represented by the following general formula (cation-1), an iodonium cation represented by the following general formula (cation-2), or an ammonium cation represented by the following general formula (cation-3). 【Chemistry 2】 (In the formula, R ｃｔ１ ~R ｃｔ９ Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain a halogen atom or a heteroatom.

2. The resist composition according to claim 1, characterized in that the resist composition further comprises an organometallic compound having a metal atom selected from cobalt, nickel, copper, zinc, silver, indium, tin, antimony, tellurium, and platinum.

3. A pattern formation method comprising the steps of: forming a resist film on a substrate using the resist composition described in claim 1 or claim 2; exposing the resist film with a high-energy beam; and developing the exposed resist film to form a resist pattern.

4. The pattern formation method according to claim 3, characterized in that an electron beam or extreme ultraviolet light is used as the high-energy ray.

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