Resist composition and pattern formation method

Abstract

This invention provides a resist composition that is highly sensitive, stable, and easy to handle in photolithography using high-energy rays, particularly EB lithography and EUV lithography, as well as a pattern formation method using the resist composition. [Solution] A resist composition characterized by comprising a compound represented by the following general formula (1) and a solvent. TIFF2026088950000016.tif5450

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 p.1 (2003) [Non-Patent Document 2] SPIE Vol.6520 p.65203L-1(2007) [Non-Patent Document 3] SPIE Vol.9051 p.90511B-1(2014) [Overview of the Initiative] [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 having excellent sensitivity, stability, and ease of handling in photolithography using high-energy rays, particularly EB lithography and EUV lithography, 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 compound represented by the following general formula (1) and a solvent.

Chemical formula

[0014] Such a resist composition can provide a resist composition having excellent sensitivity, stability, and ease of handling in photolithography using high-energy rays, and a pattern forming method using the resist composition.

[0015] Further, it is preferable that the resist composition of the present invention contains a metal compound containing one or more metals selected from cobalt, nickel, copper, zinc, silver, indium, tin, antimony, tellurium, and platinum.

[0016] Since the metal atoms contained in the metal compound have high EUV absorption ability in EUV lithography, by adding them to the resist composition of the present invention, a resist composition excellent in sensitivity and LWR can be obtained.

[0017] Furthermore, the present invention can provide a pattern forming method including a step of forming a resist film on a substrate using the resist composition of the present invention, a step of exposing the resist film with high-energy rays, and a step of developing the exposed resist film to form a resist pattern.

[0018] The resist composition of the present invention can be suitably used in a patterning method.

[0019] Moreover, it is preferably a patterning method in which the high-energy ray is EB or EUV.

[0020] The resist composition of the present invention can be suitably used in a patterning method using EB or EUV among high-energy rays.

Effects of the Invention

[0021] The resist composition of the present invention is particularly excellent in sensitivity and has good stability in EB lithography and EUV lithography, and thus is very useful in fine pattern formation.

Embodiments for Carrying Out the Invention

[0022] As described above, in photolithography using high-energy rays, there has been a demand for the development of a resist composition excellent in sensitivity, stable, and easy to handle, and a patterning method using the resist composition.

[0023] As a result of intensive studies on the above problems, the present inventors have found that a resist composition containing a germanium compound having a specific structure as a main component exhibits excellent sensitivity, provides a resist film excellent in stability, and is extremely effective for precise microfabrication, and thus have arrived at the present invention.

[0024] That is, the present invention is a resist composition characterized by containing a compound represented by the following general formula (1) and a solvent.

Chem.

[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 a solvent.

[0027] [Germanium compounds] The aforementioned germanium compound is a compound represented by the following general formula (1). [ka] (In the formula, R 1 This is a hydrocarbyl group having 1 to 10 carbon atoms, which may contain a halogen atom or a heteroatom.

[0028] In the formula, R 1 This is a hydrocarbyl group having 1 to 10 carbon atoms, which may contain a halogen atom or a heteroatom.

[0029] R 1 Examples of halogen atoms represented by R include fluorine, chlorine, bromine, and iodine atoms. 1 The C1-C10 hydrocarbyl group represented by can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include C1-C10 alkyl groups such as methyl, ethyl, 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, and tricyclo[5.2.1.0 2,6Examples include cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as decanyl and adamantyl groups; alkenyl groups having 6 to 10 carbon atoms, such as vinyl and allyl groups; aryl groups having 6 to 10 carbon atoms, such as phenyl 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, sulfur, nitrogen, and halogen atoms, and some of the -CH2- groups of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen, sulfur, 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. Among these, R 1 A hydrocarbyl group having 1 to 4 carbon atoms is preferred.

[0030] Specific examples of germanium compounds represented by the above general formula (1) are listed below, but are not limited to these. [ka]

[0031] [ka]

[0032] [ka]

[0033] The germanium compound may be used alone or in combination of two or more types.

[0034] [solvent] The resist composition of the present invention contains a solvent. An organic solvent is preferred as the 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.

[0035] The solvent content 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.

[0036] 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).

[0037] 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.

[0038] [Metal compounds] The resist composition of the present invention may also contain a metal compound comprising one or more metals selected from cobalt, nickel, copper, zinc, silver, indium, tin, antimony, tellurium, and platinum.

[0039] The content of the metal compound is preferably 5 to 50 parts by mass per 100 parts by mass of the germanium compound.

[0040] 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.

[0041] The aforementioned metal compounds can also be used in combination in order to adjust their properties, particularly radiation absorption.

[0042] The metal compound is preferably an organometallic compound. While any structure of the organometallic compound is acceptable, it is preferable that the organic compound component in the structure is small and that the molecule as a whole has high EUV absorption capacity, and that the compound dissolves in an organic solvent used to dissolve the resist and can be spin-coated onto the substrate in an amorphous state.

[0043] [Photoacid Generator] The resist composition of the present invention may include a photoacid generator as a component other than the germanium compound and the 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 methido 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 generator 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.

[0044] 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 solids. In this specification, "solids" refers to all components of the resist composition other than the solvent. The photoacid generator may be used alone or in combination of two or more types.

[0045] [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.

[0046] As the radical scavenger, hindered phenols, quinones, hindered amines, thiol compounds, etc., can be used. 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.

[0047] 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.

[0048] [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. 2011-16746. 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]

[0049] 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.)

[0050] Among these, the 1,4-butylene group and the 2,2-dimethyl-1,3-propylene group are preferred.

[0051] In the above general formula (surf-1), 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, which is 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-based surfactants, please refer to U.S. Patent No. 5,650,483, etc.

[0052] 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.

[0053] [Pattern formation method] When the resist composition of the present invention is used for various integrated circuit manufacturing, known lithography techniques can be applied. As a pattern forming method, it is preferable to have a pattern forming method including a step of forming a resist film on a substrate using the resist composition of the present invention, a step of exposing the resist film with high energy rays, and a step of developing the exposed resist film to form a resist pattern.

[0054] The resist composition of the present invention is applied onto a substrate for integrated circuit manufacturing (such as Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflection film, etc.) or a substrate for mask circuit manufacturing (such as Cr, CrO, CrON, MoSi2, SiO2, 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 - 2 μm. This is heated on a hot plate. Preferably, it is heated at 60 - 200 °C for 10 seconds - 30 minutes, more preferably at 80 - 180 °C for 30 seconds - 20 minutes to form a resist film.

[0055] Examples of the high energy rays include ultraviolet rays, far ultraviolet rays, EB, EUV with a wavelength of 3 - 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 dose is preferably 1 - 200 mJ / cm 2 degree, more preferably 10 - 150 mJ / cm 2 degree and irradiated so as to be in such an amount range. When using EB as the high energy rays, the exposure dose is preferably 0.1 - 5000 μC / cm 2 degree, more preferably 0.5 - 4000 μC / cm 2 degree and drawn using a mask for forming a direct or target pattern. Note that the resist composition of the present invention is particularly suitable for fine patterning by EB or EUV among high energy rays.

[0056] 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.

[0057] 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 when forming a pattern with the resist composition of the present invention, organic solvent development is preferred. 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] Specific examples of the aromatic solvents mentioned above include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, and mesitylene.

[0064] 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.

[0065] 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 developer 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]

[0066] The present invention will be specifically described below using examples and comparative examples, but the present invention is not limited to these.

[0067] [1] Synthesis of germanium compound (G-1) Germanium compound (G-1) was synthesized with reference to Chemistry Letters 2002, pp. 1124-1125, and the germanium compound (G-1) shown in the following structural formula was obtained. [ka]

[0068] [2] Preparation of resist composition [Examples 1-1 to 1-13, and Comparative Example 1-1] The germanium compound and each component were dissolved in a solvent according to the composition and proportions shown in Table 1 below. The resulting solution was filtered through a 0.2 μm Teflon® filter to prepare the resist compositions of the present invention (R-01 to R-13) and a comparative resist composition (RC-01).

[0069] [Table 1]

[0070] In Table 1 above, component A is a metal compound, component B is a photoacid generator, and component C is a radical scavenger. The compounds used as component A (M-1 to M-10) have the structures shown in the following structural formulas. 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 the compounds used as components B and C are as follows.

[0071] [ka]

[0072] P-1: Triphenylsulfonium tosylate ·Sc-1: Dibutylhydroxytoluene

[0073] • Solvent: PGMEA (Propylene glycol monomethyl ether acetate) 4M2P (4-methyl-2-pentanol)

[0074] [3] EB lithography evaluation [Examples 2-1 to 2-13, and Comparative Example 2-1] Each resist composition (R-01 to R-13, and RC-01) was spin-coated onto a Si substrate pre-coated with a 60 nm thick anti-reflective coating (DUV-42) manufactured by Nissan Chemical Corporation. The resist film was then pre-baked at 100°C for 60 seconds using a hot plate to produce a 40 nm thick resist film. The resist film was then exposed using an EB lithography system (ELS-F125, accelerating voltage 125 kV) manufactured by Elionix Corporation. PEB was performed on a hot plate at the temperatures listed in Table 2 for 60 seconds, followed by development using 2-heptanone for 30 seconds to form a pattern. 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, limiting resolution, and post-exposure stability of the obtained LS pattern were evaluated according to the evaluation method described below. The results are shown in Table 2.

[0075] [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.

[0076] [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.

[0077] [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.

[0078] [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 line width (CD) and its change (ΔPPD) after post-exposure resting were calculated. The results are shown in Table 2.

[0079] [Table 2]

[0080] As shown in Table 2, Examples 2-1 to 2-13, using the resist compositions (R-01 to R-13) of the present invention, demonstrated superior LWR and critical 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 pattern remained stable after formation. On the other hand, Comparative Example 2-1, using the resist composition (RC-01), showed inferiority in LWR, critical resolution, and post-exposure recovery.

[0081] [4] Storage stability evaluation [Examples 3-1 to 3-13, and Comparative Example 3-1] Under room temperature conditions (20±5℃), each resist composition (R-01~R-13 and RC-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.

[0082] [Table 3]

[0083] As shown in Table 3 above, Examples 3-1 to 3-13, using the resist compositions (R-01 to R-13) of the present invention, demonstrated excellent storage stability and ease of handling. On the other hand, Comparative Example 3-1, using the resist composition (RC-01), showed poor storage stability.

[0084] [5] EUV lithography evaluation (line and space pattern) [Examples 4-1 and 4-2] Each resist composition of the present invention (R-01 and R-02) 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. was formed to a thickness of 20 nm. A resist film with a thickness of 40 nm was then fabricated by pre-baking (PAB) at 100°C for 60 seconds using a hot plate. 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 temperature 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.

[0085] The obtained resist patterns were evaluated as follows. The results are shown in Table 4.

[0086] [Sensitivity evaluation] The aforementioned LS pattern was observed using a Hitachi High-Tech Corporation measuring SEM (CG-6300), and the optimal exposure dose Eop(mJ / cm²) was determined to obtain 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.

[0087] [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 (nm) 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.

[0088] [Evaluation of critical 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.

[0089] [Table 4]

[0090] As shown in Table 4 above, Examples 4-1 and 4-2, using the resist compositions of the present invention (R-01 and R-02), were found to exhibit excellent LWR and limiting resolution in negative pattern formation by organic solvent development using EUV lithography. Furthermore, it was found that patterns with excellent sensitivity, LWR, and resolution can be formed by adding metal compounds with high absorption of EUV light.

[0091] 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 compound represented by the following general formula (1) and a solvent. 【Chemistry 1】 (In the formula, R １ (This is a hydrocarbyl group having 1 to 10 carbon atoms, which may contain a halogen atom or a heteroatom.)

2. The resist composition according to claim 1, wherein the resist composition comprises a metal compound containing one or more metals selected from cobalt, nickel, copper, zinc, silver, indium, tin, antimony, tellurium, and platinum.

3. A pattern forming method characterized by 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 forming method according to claim 3, characterized in that the high-energy rays are EB or EUV.

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