JP7634650B2 - High energy ray resist composition, method for producing high energy ray resist composition, method for forming resist pattern, and method for producing semiconductor device - Google Patents

Description

The present invention relates to a resist composition for high-energy radiation. More specifically, the present invention relates to a resist composition for extreme ultraviolet radiation and/or an electron beam resist composition. The present invention also relates to a method for producing a resist composition for high-energy radiation, a method for forming a resist pattern, and a method for producing a semiconductor device.

Lithography using extreme ultraviolet (EUV) or electron beams is a promising method for high-productivity, high-resolution microfabrication in the manufacture of semiconductors and the like, and there is a demand for the development of highly sensitive, high-resolution resist compositions for use therein.
For example, Non-Patent Document 1 discloses EUV lithography using a resist composition for high-energy radiation that contains a compound that contains a tin-oxocage and OH ⁻ , an acetate anion, a malonate anion, or a tosylate anion.

Jarich Haitjema et al. , “Extreme ultraviolet patterning of tin-oxo cages”, J. Micro/Nanokith. HEMS MOEMS. , 16(3), 033510 (2017)

As described above, various resist compositions for use with high-energy rays have been reported. However, there has been a demand for improvements in the film quality (definition of the resist pattern) and substrate adhesion (developer resistance) of the resist film (resist pattern) formed when the resist composition is applied to lithography using high-energy rays.
Therefore, an object of the present disclosure is to provide a resist composition for high-energy rays, which is capable of forming a resist film (resist pattern) that has good film quality and substrate adhesion when used in lithography using high-energy rays.

The present inventors conducted various investigations to achieve the above object and arrived at the present invention.
That is, the composition of the present disclosure is a resist composition for high-energy radiation, which contains an anion represented by the following general formula (1) and a cluster containing a metal.

In the above general formula (1), R ¹ represents an organic group having 1 to 30 carbon atoms, and R ² and R ³ each independently represent a fluorine atom, a hydrogen atom, or an organic group having 1 to 5 carbon atoms.

The high-energy beam resist composition disclosed herein makes it possible to create good patterns in high-energy beam lithography with reduced defect generation.

This is an SEM image of a pattern formed by electron beam lithography using a resist composition containing tin oxocluster hydroxide (compound A). The concentration of compound A in the resist composition is 20 mg/ml, the magnification of the SEM image is 10,000 times, the pattern has a size of 200 nm with a pitch of 600 nm, and the output of the high energy beam is 2000 μC/cm ² . This is an SEM image of a pattern formed by electron beam lithography using a resist composition (high energy beam resist composition (1) of the present disclosure) containing tin oxocluster vinyl trifluoroborate (compound 1). The concentration of compound 1 in the resist composition is 20 mg/ml, the magnification of the SEM image is 10,000 times, the pattern has a size of 200 nm with a pitch of 600 nm, and the output of the high energy beam is 2000 μC/cm ² . This is an SEM image of a pattern formed by electron beam lithography using a resist composition containing tin oxocluster hydroxide (compound A). The concentration of compound A in the resist composition is 20 mg/ml, the magnification of the SEM image is 2,500 times, the pattern has a size of 200 nm with a pitch of 600 nm, and the output of the high energy beam is 2000 μC/cm ² . This is an SEM image of a pattern formed by electron beam lithography using a resist composition (high energy beam resist composition (1) of the present disclosure) containing tin oxocluster vinyl trifluoroborate (compound 1). The concentration of compound 1 in the resist composition is 20 mg/ml, the magnification of the SEM image is 2,500 times, the pattern has a size of 200 nm with a pitch of 600 nm, and the output of the high energy beam is 2000 μC/cm ² . This is an SEM image of a pattern formed by electron beam lithography using a resist composition (high-energy beam resist composition (1) of the present disclosure) containing tin oxocluster vinyl trifluoroborate (compound 1). The concentration of compound 1 in the resist composition is 20 mg/ml, the magnification of the SEM image is 100,000 times, the pattern has a size of 20 nm with a pitch of 60 nm, and the output of the high-energy beam is 240 μC/cm ² . 1 is a ¹¹⁹ Sn NMR chart of tin oxocluster vinyl trifluoroborate (compound 1).

The present disclosure will be described in detail below.
In addition, a combination of two or more of the individual preferred embodiments of the present disclosure described below is also a preferred embodiment of the present disclosure.

[High-energy ray resist composition]
The resist composition for high-energy radiation of the present disclosure contains a fluorinated borate anion and a cluster containing a metal. Hereinafter, the compound containing the fluorinated borate anion and the cluster containing a metal is also referred to as the "compound of the present disclosure."
In the present disclosure, the term "high-energy rays" refers to ionizing radiation or non-ionizing radiation with a wavelength of 13.5 nm or less, and examples of such rays include non-ionizing radiation particles (electromagnetic waves) such as X-rays, light rays (non-ionizing radiation) such as EUV having a wavelength of 1 to 13.5 nm (particularly 13.5 nm), and ionizing radiation particles such as electron beams.

Fluorinated borate anions of the present disclosure
The high-energy ray resist composition and the compound of the present disclosure contain a fluorinated borate anion (hereinafter also referred to as the "fluorinated borate anion of the present disclosure"). The fluorinated borate anion of the present disclosure may be an anion having at least one B-F bond, but is preferably an anion having a structure represented by the following general formula (1).

In the above general formula (1), R ¹ represents an organic group having 1 to 30 carbon atoms, and R ² and R ³ each independently represent a fluorine atom, a hydrogen atom, or an organic group having 1 to 5 carbon atoms.
In the above general formula (1), examples of the organic group represented by R ¹ include an alkyl group, an alkenyl group, an aryl group, a heterocyclic group, a group in which a hydrocarbon group is bonded to a silicon atom, a cyano group, and an acyl group, which may have a substituent. Examples of the hydrocarbon group bonded to a silicon atom include an aliphatic hydrocarbon group and an aromatic hydrocarbon group. The aliphatic hydrocarbon group may be saturated or unsaturated, and may be linear or alicyclic. The hydrocarbon group bonded to a silicon atom is preferably an aliphatic hydrocarbon group having 1 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 15 carbon atoms, more preferably a saturated linear aliphatic hydrocarbon group having 1 to 6 carbon atoms, or an aromatic hydrocarbon group having 6 to 12 carbon atoms.
Examples of the substituent that the organic group represented by ^R1 may have include an alkyl group, an alkenyl group, an aryl group, a heterocyclic group, a cyano group, an acyl group, an amino group, an alkoxy group, an aryloxy group (also called an aryloxy group), a hydroxyl group, a carboxyl group, a sulfonic acid group, a sulfate ester group, a phosphoric acid group, a halogen atom, etc. The organic group represented by ^R1 may have one or more substituents, and may have one or more types of substituents.

The organic group represented by ^R1 preferably has a carbon number of 1 or more, more preferably 2 or more, and preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less. When the organic group represented by ^R1 has a substituent, the carbon number including the substituent is preferably within the above range.
In the above general formula (1), examples of the organic group represented by R ¹ include unsubstituted or substituted alkyl groups such as methyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-hexyl, n-octyl, n-decyl, cyclopentyl, cyclohexyl, benzyl, p-methoxybenzyl, and phenylethyl groups; unsubstituted or substituted alkenyl groups such as vinyl, allyl, crotyl, and cinnamyl groups; phenyl, biphenyl, naphthyl, anthracenyl, toluyl, and p-tert-butyl groups. Examples of the organic group represented by R 1 include unsubstituted or substituted aryl groups such as phenyl, m-methoxyphenyl, p-iodophenyl, and p-fluorophenyl groups; unsubstituted or substituted heterocyclic groups such as thienyl, thiazolyl, isothiazolyl, furyl, oxazolyl, imidazolyl, pyridyl, pyrimidyl, piperidyl, and morpholyl groups; groups in which a hydrocarbon group is bonded to a silicon atom such as trimethylsilyl, dimethylsilyl, monomethylsilyl, triphenylsilyl, diphenylsilyl, and monophenylsilyl groups; cyano groups; and acyl groups such as formyl groups. The organic group represented by R ¹ is preferably an unsubstituted or substituted alkyl group, an unsubstituted or substituted alkenyl group, or an unsubstituted or substituted aryl group.

In the above general formula (1), examples of the substituent that the organic group represented by R ¹ may have include, for example, the groups exemplified as the organic group represented by R ^1. In addition, examples of the substituent that the organic group represented by R ¹ may have include, in addition to the groups exemplified as the organic group represented by R ¹ , halogen atoms such as iodine, bromine, and fluorine; unsubstituted or substituted alkoxy groups such as methoxy and ethoxy groups; unsubstituted or substituted aryloxy groups such as phenoxy groups; unsubstituted amino groups; substituted amino groups such as monomethylamino groups, dimethylamino groups, monodiethylamino groups, and diethylamino groups; acid group-containing groups such as carboxy groups, sulfonic acid groups, sulfate ester groups, phosphoric acid groups, and salts thereof; sulfur-containing groups such as thiol groups and methylsulfanyl groups; and the like. Examples of the substituent that the organic group represented by R ¹ may have include halogen atoms and unsubstituted or substituted alkoxy groups, and more preferably halogen atoms and unsubstituted alkoxy groups.

In the above general formula (1), when the organic group represented by R ¹ has a substituent, it may have one or two or more substituents, and it may have one type or two or more types.

Examples and preferred forms of ^R2 and/or ^R3 when they are organic groups having 1 to 5 carbon atoms are the same as the examples and preferred forms of the organic groups represented by ^R1 above when they are organic groups having 1 to 5 carbon atoms. The organic groups represented by ^R2 and/or ^R3 may have a substituent, and examples and preferred forms of the substituent are the same as the examples and preferred forms of the substituents that the organic groups represented by ^R1 above may have. However, when the organic groups represented by ^R2 and/or ^R3 have a substituent, it is preferable that the number of carbon atoms including the substituent is in the range of 1 to 5.

At least one of R ² and R ³ is preferably a fluorine atom, and it is more preferable that both of R ² and R ³ are fluorine atoms.

Metal-containing clusters of the present disclosure
The resist composition for high energy radiation and the compound of the present disclosure contain a cluster containing a metal (hereinafter also referred to as the "metal cluster of the present disclosure"). The metal cluster of the present disclosure preferably contains a metal having sensitivity to high energy radiation, and more preferably contains at least one selected from Sn, Hf, Zr, Co, Pt, Pd, and Zn. The metal is preferably contained as a constituent element of the cluster. In the present disclosure, "having sensitivity to high energy radiation" means that the absorption cross section for one or more types of ionizing radiation or non-ionizing radiation of 13.5 nm or less (particularly EUV of 13.5 nm) is 1.2 times or more than that of carbon, preferably 2 times or more, more preferably 4 times or more, and even more preferably 8 times or more. The absorption cross section of carbon is, for example, 3.5×10 ⁵ cm ² /mol when the wavelength is 13.5 nm (92 eV) and 7.7×10 ⁴ cm ² /mol when the wavelength is 6.75 nm (183 eV).

In the present disclosure, a metal-containing cluster (metal cluster) is a metal compound in which a plurality of metal atoms are directly or indirectly linked by a ligand, and may be a cage-type compound. The metal-containing cluster of the present disclosure may be any, but may contain one or more ligands selected from aqua ligands, hydroxo ligands, oxo ligands, peroxo ligands, thiolato ligands, sulfide ligands, fluoro ligands, chloro ligands, iodo ligands, hydride ligands, cyanato ligands, azide ligands, carboxylato ligands, oxalato ligands, etc. The metal cluster of the present disclosure preferably contains one or two ligands selected from oxo ligands and peroxo ligands, and more preferably, a plurality of metal atoms are indirectly linked by oxo ligands and/or peroxo ligands. For example, when two or more metal atoms are linked via an oxo ligand, this includes structures such as M-O-M, M-O(-M)-M, etc. (wherein M represents a metal atom). When two metal atoms are linked via a peroxo ligand, this includes a structure such as M-O-O-M (wherein M represents a metal atom). The metal cluster of the present disclosure is preferably a metal oxide cluster.
The metal cluster of the present disclosure preferably contains 2 or more metal atoms in one molecule, preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less. When the number is within the above range, sensitivity in lithography using high-energy beams tends to be improved.
The metal clusters of the present disclosure are preferably divalent cations.
Specific examples of the metal cluster of the present disclosure include tin oxoclusters, tin hydroxoclusters, Hf oxoclusters, and Zr oxoclusters.

In the metal cluster of the present disclosure, an organic group is preferably bonded to a part or all of the metal atoms. The organic group bonded to the metal atom is exemplified by the same organic group as the organic group represented by R ¹ in the general formula (1) above, but is preferably one or more organic groups selected from an alkyl group, an alkenyl group, and an aryl group. The alkyl group and the alkenyl group may be linear, branched, or cyclic. The organic group bonded to the metal atom is preferably an organic group having 1 to 30 carbon atoms, and the organic group may have one or more substituents. The preferred form of the organic group bonded to the metal atom is the same as R ¹ in the general formula (1) above, unless otherwise specified. The organic group bonded to the metal atom is preferably an alkyl group, an alkenyl group, or an aryl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 20 carbon atoms, and even more preferably an alkyl group having 1 to 10 carbon atoms.

<Other ingredients>
The high-energy radiation resist composition of the present disclosure may contain any optional components in addition to the fluorinated borate anion of the present disclosure and the metal-containing cluster of the present disclosure.
The resist composition for high energy radiation of the present disclosure may contain an organic solvent. Examples of the organic solvent include alcohols such as ethanol, isopropanol, and 1-butanol; polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol; ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl-n-amyl ketone, methyl isoamyl ketone, and 2-heptanone; ethyl acetate, propyl acetate, butyl acetate, methyl lactate, ethyl lactate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl methoxypropionate, methyl ethoxypropionate, ethoxypropionate, ethyl butyl ketone ... Examples of the organic solvent include esters such as ethyl propionate and propylene glycol monomethyl ether acetate; aromatic organic solvents such as anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, dibenzyl ether, phenetole, butylphenyl ether, ethylbenzene, diethylbenzene, isopropylbenzene, amylbenzene, toluene, xylene, and trimethylbenzene; lactones such as γ-butyrolactone; cyclic ethers such as dioxane; amines such as N,N-dimethylacetamide; and halogens such as chloroform and methylene chloride. The organic solvent may be used alone or in combination of two or more kinds. When two or more kinds are combined, the types and ratios thereof are arbitrary.

<Composition of high energy ray resist composition>
The ratio of boron atoms to metal contained in the high-energy ray resist composition of the present disclosure is preferably 1 to 1 x ¹⁰⁵ moles of metal per mole of boron atoms, more preferably 1 to 1000 moles, and even more preferably 1 to 20 moles. When the ratio is within the above range, the film quality of the resist film tends to be improved. The metal is preferably at least one selected from Sn, Hf, Zr, Co, Pt, Pd, and Zn.
The ratio of the fluorinated borate anion of the present disclosure to the metal cluster of the present disclosure contained in the high-energy radiation resist composition of the present disclosure is preferably 0.001 to 5×10 ⁴ moles of metal cluster per mole of fluorinated borate anion, more preferably 0.01 to 100 moles, and even more preferably 0.1 to 10 moles. When within the above range, the film quality of the resist film tends to be improved.

The high-energy resist composition of the present disclosure preferably contains 1 ppm or more of boron atoms, more preferably 10 ppm or more, and even more preferably 100 ppm or more. When the content is within the above range, the film quality of the resist film tends to improve. In the present invention, unless otherwise specified, "ppm" means a value calculated in mass conversion (for example, 10,000 ppm corresponds to 1 mass%).

The resist composition for high energy radiation of the present disclosure preferably contains 1 ppm or more of metal, more preferably 10 ppm or more, and even more preferably 100 ppm or more. The metal content in the resist composition for high energy radiation of the present disclosure is preferably 60 mass% or less, more preferably 50 mass% or less, and even more preferably 40 mass% or less. When the metal content is within the above range, the film quality of the resist film tends to be improved. The metal is preferably at least one selected from Sn, Hf, Zr, Co, Pt, Pd, and Zn. The boron atom content and the metal content can usually be analyzed by, for example, ICP, ICP-AES, or ICP-MS.

The content of the organic solvent in the resist composition for high energy radiation of the present disclosure is not particularly limited and may be appropriately set according to, for example, the coating film thickness, etc., but is preferably 50% by mass or more, more preferably 80% by mass or more, and even more preferably 100% by mass or more, based on 100% by mass of the total solid content of the resist composition for high energy radiation of the present disclosure. In addition, it is preferably 1000% by mass or less, more preferably 800% by mass or less, and even more preferably 500% by mass or less, based on 100% by mass of the total solid content of the resist composition for high energy radiation of the present disclosure. When it is within the above range, the film quality of the resist film tends to be improved. The total solid content of the resist composition for high energy radiation refers to the amount obtained by excluding the content of the solvent from the total amount of the resist composition for high energy radiation. The total solid content can be measured by known analytical means such as liquid chromatography or gas chromatography.

[Method of producing a resist composition for use with high-energy rays according to the present disclosure]
The high-energy ray resist composition or compound of the present disclosure is preferably produced by including a step of mixing a metal-containing cluster with a fluorinated borate salt (hereinafter also referred to as a “mixing step”).

In the mixing step, it is preferable to perform salt exchange between the anion contained in the metal-containing cluster and the fluorinated borate anion contained in the salt of the fluorinated borate. In particular, it is preferable to react the anion represented by the formula (1) with the metal-containing cluster.
In the mixing step, a solvent can be used. The type and amount of the solvent may be appropriately selected.

The method for producing the high-energy ray resist composition or the compound of the present disclosure preferably includes a purification step. Examples of the purification step include distilling off the solvent after the mixing step and washing with water or an organic solvent.

The method for producing the high-energy ray resist composition or the compound of the present disclosure preferably includes a solvent addition step. For example, it is preferable to add a solvent to the high-energy ray resist composition or the compound of the present disclosure after the purification step to dissolve or disperse the composition.

The cluster containing a metal used in the production of the high-energy ray resist composition or the compound of the present disclosure may be produced by a known method. For example, in the case of a metal oxocluster, a method of producing the cluster by reacting a compound represented by R ^A -M ^A (=O)-OH (wherein R ^A represents an organic group and M ^A represents a metal atom) in the presence of an acid catalyst is preferred. Note that M ^A is preferably a metal having sensitivity to high-energy rays, and the preferred form of R ^A is the same as R ¹ in the above general formula (1). M ^A is more preferably one selected from Sn, Hf, Zr, Co, Pt, Pd, and Zn, and R ^A is more preferably an alkyl group, alkenyl group, or aryl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 20 carbon atoms, and even more preferably an alkyl group having 1 to 10 carbon atoms.
The acid catalyst may be either an organic acid or an inorganic acid. For example, inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, etc.; paratoluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, etc. may be used.
The fluorinated borate salt used in the manufacture of the high-energy ray resist composition or the compound of the present disclosure may be manufactured by a known method, but the method of synthesis from boronic acid is simple and preferable.According to the synthesis method described by Vedejs, E.; Chapman, R. W.; Fields, S. C.; Lin, S.; Schrimpf, M. R. et al. in J. Org. Chem. 1995, 60, 3020., it can be easily synthesized from any boronic acid.

[Method of forming a resist pattern]
The pattern forming method of the present disclosure includes a step (i) of applying a high-energy ray resist composition of the present disclosure, a step (ii) of drying the coating film of the high-energy ray resist composition, a step (iii) of exposing the coating film of the high-energy ray resist composition to high-energy rays, and a step (iv) of developing the film of the high-energy ray resist composition.

<Step (i)>
The method for forming a resist pattern according to the present disclosure includes a step (step (i)) of applying a resist composition for high-energy radiation according to the present disclosure. By applying the resist composition for high-energy radiation according to the present disclosure, a coating film of the resist composition for high-energy radiation according to the present disclosure is formed.
In the pattern forming method of the present disclosure, the method for applying the high-energy ray resist composition of the present disclosure is not particularly limited, and a resist film can be formed using any application method such as an inkjet method, a spray method, a spin coating method, a dip coating method, or a roll coating method. From the viewpoint of forming a uniform thin film, the spin coating method is preferred.

The resist composition for high energy radiation of the present disclosure is applied to, for example, a substrate, but the substrate is not particularly limited and may have any dimensions or size, and examples of the material include silicon, SiC, nitride semiconductors, GaAs, and AlGaAs. The substrate on which the resist film is formed may have a thin film that is processed into a desired pattern by dry etching or the like, and examples of the thin film include a polysilicon thin film, a laminated film of a polysilicon thin film and a metal thin film, a metal thin film, a Si oxide film, a Si nitride film, a Si oxynitride film, and other insulating thin films. An organic film may be further formed on the thin film. The resist composition for high energy radiation of the present disclosure may be used to form an upper resist film in a multilayer resist structure.

The amount of the high-energy ray resist composition of the present disclosure applied in step (i) can be adjusted appropriately, for example, so that the resist film has a thickness described below.

<Step (ii)>
The method of forming a resist pattern according to the present disclosure includes a step (step (ii)) of drying the coating film of the high-energy ray resist composition. By drying the coating film of the high-energy ray resist composition, a coating film of the high-energy ray resist composition having a reduced solvent content is formed. Step (ii) is usually carried out after step (i).
In the pattern forming method of the present disclosure, the method of drying the coating film of the high energy ray resist composition of the present disclosure is not particularly limited. For example, it is preferable to remove the organic solvent remaining in the resist film by heating the coating film. The heating temperature is preferably 70°C or higher, more preferably 80°C or higher, even more preferably 90°C or higher, preferably 300°C or lower, more preferably 250°C or lower, and even more preferably 200°C or lower. Heating may be performed under two or more different conditions. The heating time is preferably 10 seconds or more, more preferably 20 seconds or more, even more preferably 30 seconds or more, preferably 300 seconds or lower, more preferably 200 seconds or lower, and even more preferably 150 seconds or lower. When step (ii) is performed within the above range, the productivity of the resist film, the film quality of the resist film, and the substrate adhesion tend to be improved.
Step (ii) may be carried out under reduced pressure, normal pressure, or elevated pressure, or may be carried out in an inert atmosphere.
In the step (ii), the coating film after drying (resist film after drying) is preferably dried so that the amount of remaining solvent is as small as possible. For example, the coating film after drying is preferably dried so that the solvent content is 1000 ppm or less.

<Step (iii)>
The method for forming a resist pattern of the present disclosure includes a step (step (iii)) of exposing a coating film of the resist composition for high-energy radiation to high-energy radiation. By exposing the coating film of the resist composition for high-energy radiation to high-energy radiation, a coating film is formed in which the exposed and unexposed portions are cured. Step (iii) is usually performed after step (ii).
In the pattern forming method of the present disclosure, the method of exposing the coating film of the high-energy ray resist composition of the present disclosure to high-energy rays is not particularly limited, but is preferably performed using a high-energy light source through a desired mask pattern. The preferred form of the high-energy rays is as described above.

Examples of exposure sources used for exposure include EUV exposure sources (LPP) that extract EUV light from plasma generated by irradiating a target such as tin, its compounds, or xenon with laser light, EUV exposure sources (DPP) that extract EUV light from plasma generated by high-voltage discharge in the presence of tin, its compounds, or xenon near an electrode made of tungsten, silicon carbide, or the like, EUV exposure sources that irradiate a target with laser light and extract EUV light from plasma generated by discharge, EUV exposure sources that extract EUV light from a synchrotron radiation source, electron beam irradiation sources, etc. A reflective or transmissive filter may be used to extract high-energy rays from a high-energy light source.

In the above step (iii), the output of the high energy beam is preferably 0.5 mJ/cm ² or more, more preferably 1 mJ/cm 2 or more, and even more preferably 2 mJ/cm ² or more, and preferably 500 mJ/cm ² or less, more preferably 200 mJ/cm ² or less, and even more preferably 100 mJ/cm ² or ^less , in the case of ionizing radiation non-particle beams such as X-rays and non-ionizing radiation such as EUV light. In the case of ionizing radiation particle beams such as electron beams, the output is preferably 10 μC/cm ² or more, more preferably 20 μC/cm ² or more, and even more preferably 50 μC/cm ² or more, and preferably 10000 μC/cm ² or less, more preferably 5000 μC/cm ² or less, and even more preferably 2500 μC/cm ² or less. When step (iii) is carried out within the above range, the productivity of the resist film, and the film quality and substrate adhesion of the resist film tend to be improved.

<Step (iv)>
The method for forming a resist pattern according to the present disclosure includes a step (step (iv)) of developing a film of the resist composition for high-energy radiation according to the present disclosure. A resist pattern can be formed by the development treatment. Step (iv) is usually carried out after step (iii).

In the pattern forming method of the present disclosure, the development of the film (resist film) of the high-energy ray resist composition of the present disclosure can be carried out using any of water, alkaline water, organic solvents, and mixtures thereof. Examples of solvents that can be used as developers include the organic solvents listed above. Examples of suitable organic solvents include alcohols such as 4-methyl-2-pentanol, 1-butanol, isopropanol, 1-propanol, and methanol; esters such as ethyl lactate; ethers such as tetrahydrofuran, dioxane, and anisole; and amines such as tetramethylammonium hydroxide.

The developer may optionally contain viscosity modifiers, solubilizing agents, surfactants, etc., as desired.

The developing time is preferably 10 seconds or more, more preferably 20 seconds or more, and even more preferably 30 seconds or more, and is preferably 300 seconds or less, more preferably 200 seconds or less, and even more preferably 100 seconds or less. When step (iv) is performed within the above range, the productivity of the resist film, the film quality of the resist film, and the substrate adhesion tend to be improved.
The developing method is not particularly limited, and examples thereof include a dipping method, a paddle method, a spray method, and the like.

In the resist pattern forming method of the present disclosure, the film thickness of the resist film after development is preferably 10 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more, and is preferably 100 nm or less, more preferably 80 nm or less, and even more preferably 60 nm or less. The film thickness may also be determined according to the minimum processing dimension of the desired pattern. If it is within the above range, the film quality of the resist film and the dimensional stability of the resist pattern tend to be improved.

<Other processes>
The pattern forming method of the present disclosure may include any step other than the above steps (i), (ii), (iii), and (iv), such as a step (v) of baking the resist film after exposure to high-energy radiation.

The above step (v) is optional, but is usually performed after step (iii). As for the baking conditions, the heating temperature is preferably 70°C or higher, more preferably 90°C or higher, even more preferably 110°C or higher, preferably 300°C or lower, more preferably 250°C or lower, and even more preferably 200°C or lower. Heating may be performed under two or more different conditions. The heating time is preferably 10 seconds or more, more preferably 30 seconds or more, even more preferably 60 seconds or more, preferably 300 seconds or lower, more preferably 150 seconds or lower, and even more preferably 120 seconds or lower. When step (v) is performed within the above range, the productivity of the resist film, the film quality of the resist film, and the substrate adhesion tend to be improved.

From the viewpoint of miniaturization of semiconductor devices, the line width of the resist pattern is, for example, preferably 500 nm or less, more preferably 400 nm or less, and even more preferably 300 nm or less.
According to the resist composition for high-energy beams of the present disclosure, a resist film having excellent film quality (pattern clarity) and substrate adhesion (developer resistance) can be formed. Therefore, even in a pattern with a narrow line width such as the above-mentioned, it is possible to create a good pattern in which the occurrence of defects is suppressed and residual film in unnecessary portions is also suppressed.

[Method of Manufacturing Semiconductor Device]
The method for producing a semiconductor device of the present disclosure includes a step (ib) of applying the high-energy ray resist composition of the present disclosure onto a substrate, a step (ii-b) of drying the coating of the high-energy ray resist composition to form a resist film, a step (iii-b) of exposing the coating of the high-energy ray resist composition to high-energy rays, and a step (iv-b) of developing the coating of the high-energy ray resist composition. Unless otherwise specified, the form and preferred form of the step (ib-b), the step (ii-b), the step (iii-b), and the step (iv-b) are the same as the form and preferred form of the above step (i), the step (ii), the step (iii), and the step (iv), respectively. The method for producing a semiconductor device of the present disclosure may include any step other than the above steps. Examples of the optional step include the steps exemplified in the pattern forming method of the present disclosure.

[Uses of the high-energy radiation resist composition of the present disclosure]
The resist composition for high-energy radiation of the present disclosure can be used in the manufacture of semiconductor devices, masks for semiconductor manufacturing equipment, and the like.

A resist film (resist pattern) formed using the resist composition for high-energy radiation of the present disclosure has good substrate adhesion (developer resistance). Specifically, it is preferable that the resist film does not peel off upon development.
Furthermore, the resist film (resist pattern) formed using the resist composition for high-energy radiation of the present disclosure has good film quality. Specifically, it is preferable that the resist pattern is clear without any joining or disappearance.

This application claims the benefit of priority based on Japanese Patent Application No. 2021-059689, filed on March 31, 2021. The entire contents of the specification of Japanese Patent Application No. 2021-059689, filed on March 31, 2021, are incorporated by reference into this application.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass."

<Synthesis Example 1>
Into a 1L four-neck flask, 20 g (95.8 mmol) of monobutyltin oxide and 5.8 g (30.3 mmol) of paratoluenesulfonic acid monohydrate were added, and 500 mL of toluene was further added. Under a nitrogen atmosphere, the mixture was heated and refluxed for 48 hours while removing water generated in the reaction system using a Dean-Stark apparatus. The mixture was then cooled to room temperature, and the unreacted solid was filtered off, and the solution was evaporated to dryness under reduced pressure. 1,4-dioxane was added to the resulting solid, which was recrystallized and purified, and then filtered to obtain 14 g of the target tin oxocluster paratoluenesulfonate.

<Synthesis Example 2>
In a 200 mL eggplant flask, 11.4 g of the tin oxocluster paratoluenesulfonate obtained in Synthesis Example 1 was added, and 58 mL of isopropyl alcohol was added to dissolve it. While heating and stirring at 40° C., a solution of 5.5 g of 15% by mass tetramethylammonium hydroxide aqueous solution, 5.7 mL of isopropyl alcohol, and 4 mL of water was slowly added dropwise. After the addition was completed, the mixture was stirred for 10 minutes and then cooled to room temperature.
The mixture was left to stand at room temperature for one day, and the resulting solid was filtered and washed with acetonitrile to obtain 4.5 g of the target tin oxocluster hydroxide (compound A).

<Synthesis Example 3>
In a 100 mL recovery flask, 400 mg of the tin oxocluster hydroxide (compound A) obtained in Synthesis Example 2 and 53.6 mg of potassium vinyltrifluoroborate were added, and 10 mL of tetrahydrofuran was added thereto, followed by stirring at room temperature for 30 minutes.
The solvent was then distilled off, and the resulting solid was washed with water and acetonitrile and dried to obtain 320 mg of tin oxocluster vinyl trifluoroborate (compound 1). When ¹¹⁹ Sn NMR was confirmed, the spectrum shown in Figure 6 was obtained. ¹¹⁹ Sn NMR: δ = -282.77 ppm, -460.97 ppm.

<Synthesis Example 4>
In a 100 mL eggplant flask, 400 mg of tin oxocluster hydroxide (compound A) and 65.6 mg of potassium normal butyl trifluoroborate were added, and 10 mL of tetrahydrofuran was added thereto, followed by stirring at room temperature for 30 minutes. After that, the solvent was distilled off, and the resulting solid was washed with water and acetonitrile, and dried to obtain 330 mg of tin oxocluster normal butyl trifluoroborate (compound 2). ¹¹⁹ Sn NMR: δ = -282.99 ppm, -460.63 ppm.

<Synthesis Example 5>
In a 100 mL recovery flask, 400 mg of tin oxocluster hydroxide (compound A) and 82.8 mg of potassium (4-fluorophenyl) trifluoroborate were added, and 10 mL of tetrahydrofuran was added thereto, followed by stirring at room temperature for 30 minutes. After that, the solvent was distilled off, and the resulting solid was washed with water and acetonitrile, and dried to obtain 350 mg of tin oxocluster (4-fluorophenyl) trifluoroborate (compound 3). ¹¹⁹ Sn NMR: δ=-282.56 ppm, -460.42 ppm.

<Synthesis Example 6>
In a 100 mL eggplant flask, 400 mg of tin oxocluster hydroxide (compound A) and 85.6 mg of potassium (3-methoxyphenyl) trifluoroborate were added, and 10 mL of tetrahydrofuran was added thereto, followed by stirring at room temperature for 30 minutes. After that, the solvent was distilled off, and the resulting solid was washed with water and acetonitrile, and dried to obtain 345 mg of tin oxocluster (3-methoxyphenyl) trifluoroborate (compound 4). ¹¹⁹ Sn NMR: δ = -283.54 ppm, -461.06 ppm.

<Synthesis Example 7>
In a 100 mL eggplant flask, 400 mg of tin oxocluster hydroxide (compound A) and 60.7 mg of potassium allyl trifluoroborate were added, and 10 mL of tetrahydrofuran was added, followed by stirring at 70° C. for 1 hour. After cooling to room temperature, the solvent was distilled off, and the resulting solid was washed with water and acetonitrile and dried to obtain 250 mg of tin oxocluster allyl trifluoroborate (compound 5). ¹¹⁹ Sn NMR: δ=−282.56 ppm, −461.02 ppm.

<Synthesis Example 8>
In a 100 mL recovery flask, 400 mg of tin oxocluster hydroxide (compound A) and 127.0 mg of potassium (4-iodophenyl) trifluoroborate were added, and 10 mL of tetrahydrofuran was added thereto and stirred for 1 hour at 70° C. After that, the mixture was cooled to room temperature and the solvent was distilled off, and the obtained solid was washed with water and acetonitrile and dried to obtain 390 mg of tin oxocluster (4-iodophenyl) trifluoroborate (compound 6).

<Synthesis Example 9>
In a 100 mL recovery flask, 400 mg of tin oxocluster hydroxide (compound A) and 98.4 mg of potassium (4-t-butylphenyl) trifluoroborate were added, and 10 mL of tetrahydrofuran was added thereto and stirred at room temperature for 30 minutes. After that, the solvent was distilled off, and the obtained solid was washed with water and acetonitrile and dried to obtain 370 mg of tin oxocluster (4-t-butylphenyl) trifluoroborate (compound 7).

<Synthesis Example 10>
In a 100 mL recovery flask, 400 mg of tin oxocluster hydroxide (compound A) and 98.4 mg of potassium (2-naphthalene) trifluoroborate were added, and 10 mL of tetrahydrofuran was added thereto and stirred at 70° C. for 1 hour. After cooling to room temperature, the solvent was distilled off, and the resulting solid was washed with water and acetonitrile and dried to obtain 260 mg of tin oxocluster (2-naphthalene) trifluoroborate (compound 8). ¹¹⁹ Sn NMR: δ=−282.77 ppm, −461.02 ppm.

<Synthesis Example 11>
In a 100 mL recovery flask, 400 mg of tin oxocluster hydroxide (compound A) and 83.6 mg of potassium cyclohexyl trifluoroborate were added, and 10 mL of tetrahydrofuran was added thereto, followed by stirring at 40° C. for 1 hour. After cooling to room temperature, the solvent was distilled off, and the resulting solid was washed with water and acetonitrile and dried to obtain 340 mg of tin oxocluster cyclohexyl trifluoroborate (compound 9). ¹¹⁹ Sn NMR: δ=−283.07 ppm, −461.32 ppm.

<Silicon wafer cleaning and surface treatment>
The silicon wafer was cut into a square of about 1.5 cm and ultrasonically cleaned in isopropanol for 10 minutes. The silicon wafer was then boiled in isopropanol for 3 minutes. The silicon wafer was then removed from the isopropanol, dried with nitrogen blow, and UV ozone cleaned for 2 minutes. The silicon wafer was then placed on a spin coater, 150 μL of hexamethyldisilazane was dripped onto the wafer, and the wafer was rotated at 4000 rpm for 35 seconds, after which the wafer was baked on a hot plate at 150° C. for 1 minute to complete the surface treatment.

<Deposition of film on silicon wafer>
As a reference, a 20 mg/mL 1-butanol solution of tin oxocluster hydroxide (compound A) was prepared (comparative resist composition). Also, a 20 mg/mL 1-butanol solution of tin oxocluster vinyl trifluoroborate (compound 1) was prepared (high-energy radiation resist composition (1) of the present disclosure).
The surface-treated silicon wafer was placed on a spin coater, and each of the prepared solutions was dropped onto it. After rotating at 1500 rpm for 45 seconds, the wafer was baked on a hot plate at 90° C. for 1 minute to complete the surface film formation.

<EB Lithography and Subsequent Development Treatment>
The silicon wafer on which the film was formed was set in an ultra-high-definition electron beam lithography device (ELS-100T manufactured by Elionix), and lithography was performed while changing the output from 240 μC/cm ² to 2000 μC/cm ^2. After completion of lithography, the silicon wafer was removed from the device and baked on a hot plate at 150°C for 2 minutes. Thereafter, it was immersed in a developer of isopropanol:water=2:1 for 30 seconds, rinsed with water for 10 seconds, and then dried by nitrogen blowing.

<Surface observation>
The surface of the pattern obtained by lithography was observed by SEM.
A SEM image at 10,000 times magnification of a pattern formed by electron beam lithography (high energy beam output: 2000 μC/cm ² ) using a resist composition containing tin oxocluster hydroxide (compound A) is shown in FIG. 1, and a SEM image at 2,500 times magnification is shown in FIG. 3. A SEM image at 10,000 times magnification of a pattern formed by electron beam lithography (high energy beam output: 2000 μC/cm ² ) using a resist composition containing tin oxocluster vinyl trifluoroborate (compound 1) is shown in FIG. 2, and a SEM image at 2,500 times magnification is shown in FIG. 4. Also, a SEM image at 100,000 times magnification of a pattern formed by electron beam lithography (high energy beam output: 240 μC/cm ² ) using a resist composition containing tin oxocluster vinyl trifluoroborate (compound 1) is shown in FIG. 5.

<<Substrate adhesion, film quality evaluation>>
As a result of observing the surface with an SEM, the pattern having no defects was evaluated as having good substrate adhesion, and the pattern having defects was evaluated as having poor substrate adhesion.
Moreover, a film having a clear pattern without any joining or disappearance of the resist was evaluated as having good film quality.
As shown in FIGS. 2, 4 and 5, the resist patterns obtained using the resist composition containing tin oxocluster vinyl trifluoroborate (compound 1) had good substrate adhesion and film quality.

1 and 2, and 3 and 4, it can be seen that the resist pattern obtained by using the composition containing tin oxocluster vinyl trifluoroborate (compound 1) has fewer defects, has good film quality, and is highly precise (clear pattern) compared to tin oxocluster hydroxide (compound A). Also, as shown in FIG. 5, by using the high energy beam resist composition (1) of the present disclosure containing tin oxocluster vinyl trifluoroborate (compound 1), it is possible to draw a pattern of about 20 nm, and it can be confirmed that with a weak light amount of about 240 μC/cm ² , the negative type and the positive type are inverted and act as a positive type.

From the above, it has become clear that the high-energy ray resist composition disclosed herein is capable of producing clear resist patterns in lithography using high-energy rays, and is capable of forming a resist film with good film quality and substrate adhesion.

Claims (5)

A resist composition for use with high-energy radiation, comprising an anion represented by the following general formula (1) and a cluster containing a metal, the cluster containing the metal being a tin oxocluster or a tin hydroxocluster:

In the above general formula (1), R ¹ represents an organic group having 1 to 30 carbon atoms, the organic group being an unsubstituted or substituted alkyl group, an unsubstituted or substituted alkenyl group, or an unsubstituted or substituted aryl group; and R ² and R ³ represent fluorine atoms . The high-energy radiation resist composition according to claim 1, wherein the metal-containing cluster is a divalent cation. A step (i) of applying the high-energy ray resist composition according to claim 1 or 2 ;
(ii) drying the coating film of the high-energy ray resist composition;
(iii) exposing the coating film of the high-energy ray resist composition to high-energy rays;
(iv) developing the film of the high-energy ray resist composition;
A method for forming a resist pattern comprising the steps of: A step of applying the high-energy ray resist composition according to claim 1 or 2 onto a substrate;
drying the coating film of the high-energy ray resist composition;
exposing a coating film of the high-energy ray resist composition to high-energy rays;
developing the film of the high-energy ray resist composition;
A method for manufacturing a semiconductor device comprising the steps of: A method for producing a resist composition for use with high-energy radiation, comprising the step of reacting an anion represented by the following general formula (1) with a cluster containing a metal, wherein the cluster containing a metal is a tin oxocluster or a tin hydroxocluster :

In the above general formula (1), R ¹ represents an organic group having 1 to 30 carbon atoms, the organic group being an unsubstituted or substituted alkyl group, an unsubstituted or substituted alkenyl group, or an unsubstituted or substituted aryl group; and R ² and R ³ represent fluorine atoms .