Poor metal cluster compound, multimer structure having same, method for producing same, photosensitive composition containing same, pattern forming method using said composition, substrate, and method for producing substrate

Abstract

The present invention provides a poor metal cluster compound that makes it possible to obtain a photosensitive composition that is highly useful as a photoresist capable of forming an ultrafine pattern.　A poor metal cluster compound according to the present invention is characterized by containing a poor metal atom, a carboxylate ligand A, and an oxo ligand and / or a hydroxo ligand, the carboxylate ligand having an alicyclic structure that binds to a carboxylate group. The poor metal atom is preferably bismuth, antimony, indium, or the like.　

Description

Metal-poor cluster compound, macrostructure containing same, method for producing same, photosensitive composition containing same, pattern forming method using this composition, substrate and method for producing substrate

[0001] The present invention relates to a poor metal cluster compound suitable for use in ultra-microlithography processes such as the manufacture of ultra-LSIs and high-capacity microchips, and other photofabrication processes, a polymeric structure containing the compound, a method for producing the compound, a photosensitive composition containing the compound, a pattern formation method using the photosensitive composition, a substrate, and a method for producing the substrate.

[0002] In the semiconductor device manufacturing process, microfabrication is performed using lithography with photoresist compositions. In semiconductor photolithography, circuit patterns become smaller as semiconductor devices become smaller, according to Moore's Law, and further miniaturization is desired. The advancement of photolithography can be broadly attributed to the shortening of wavelengths of light sources used in exposure tools and the associated development of new photoresists. Photoresists are required to satisfy all of the following requirements: high resolution, low roughness, and high sensitivity. Conventional resists are photosensitive compositions containing organic polymer-based photoacid generators and are called chemically amplified resists. This resist promotes chemical reactions through the diffusion of acid. However, the acid diffusion process can cause line edge roughness (LER), resulting in reduced resolution, making them incompatible with ultrafine patterning.

[0003] In recent years, non-chemically amplified photoresists (hereinafter referred to as metal-containing resists) have been proposed, which are primarily composed of compounds containing metal elements such as Zn and Sn. In metal-containing resists, the metal component itself is the photosensitive substance and functions as the base material. Because they do not involve acid diffusion, they can improve line edge roughness, making them promising next-generation resist materials for forming finer pattern structures. In fact, it has been reported that finer patterns can be formed using next-generation exposure equipment using extreme ultraviolet (EUV) light.

[0004] For example, Patent Documents 1 to 5 and Non-Patent Documents 1 to 3 listed below disclose methods of forming resist patterns using extreme ultraviolet rays (EUV light) or electron beams.

[0005] JP 2015-108781 A JP 2001-072716 A JP 2017-173537 A JP 2012-185484 A JP 2021-102604 A

[0006] Minoru Toriumi etc.,Proc.SPIE,9779(2016)97790GLianjia Wu etc.,Proc.SPIE,10957(2019)109570BNeha Thakur etc.,Proc.SPIE,10957(2019)10957D

[0007] In photolithography, particularly in semiconductor photolithography, there is a demand for photosensitive compositions and pattern formation methods that can realize even finer circuit patterns.

[0008] As a result of extensive research, the present inventors have found that cluster compounds having specific structures are suitable as photoresists compatible with ultrafine patterns. Accordingly, an object of the present invention is to provide a cluster compound suitable for a photosensitive composition capable of realizing finer circuit patterns, as well as a photosensitive composition containing the cluster compound, a pattern formation method using the photosensitive composition, and a substrate and a substrate manufacturing method using the pattern formation method.

[0009] The present invention has the following aspects [1] to

[20] .

[0010] [1] A poor metal cluster compound comprising a poor metal atom, a carboxylate ligand A, and an oxo ligand and / or a hydroxo ligand, wherein the carboxylate ligand A has an alicyclic structure to which the carboxylate group is bonded.

[0011] [2] The poor metal cluster compound according to [1], wherein the alicyclic structure is a 3- to 8-membered ring.

[0012] [3] The poor metal cluster compound according to [1] or [2], wherein the alicyclic structure is a cycloalkyl group.

[0013] [4] The poor metal cluster compound according to any one of [1] to [3], wherein the carboxylate ligand A is represented by the following general formula B-1:

[0014] In the above general formula B-1, R is a hydrogen atom, a halogen atom, or an organic group. Ａ are each independently a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms. Ａ They may be the same or different, and n is an integer of 1 to 6.

[0015] [5] The poor metal cluster compound according to [1] or [2], wherein the alicyclic structure is a cycloalkenyl group.

[0016] [6] The poor metal cluster compound according to [1], [2] or [5], wherein the carboxylate ligand A is at least one selected from the groups represented by the following general formulae C-1 to C-12:

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029] In the above general formulas C-1 to C-12, R is a hydrogen atom, a halogen atom, or an organic group. １ ~R １００ are each independently a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms. １ ~R １００ may be the same or different.

[0030] [7] The poor metal cluster compound according to any one of [1] to [6], wherein the poor metal atom is at least one selected from the group consisting of bismuth, indium, and antimony.

[0031] [8] The poor-metal cluster compound according to any one of [1] to [7], wherein the poor-metal atoms are bonded to each other via oxygen atoms.

[0032] [9] The poor metal cluster compound according to any one of [1] to [8], wherein a functional group selected from an organic group having 1 to 20 carbon atoms, an alkoxy group, and an amino group is bonded to any carbon atom of the alicyclic structure.

[0033]

[10] A polymeric structure having the poor metal cluster compound according to any one of [1] to [9] as a constituent unit.

[0034]

[11] A method for producing a poor metal cluster compound according to any one of [1] to [9], comprising a step of reacting a compound containing the poor metal atom with a carboxylic acid having the structure of the carboxylate ligand A in a solution.

[0035]

[12] A method for producing a poor metal cluster compound according to any one of [1] to [9], comprising the steps of reacting a complex containing the poor metal atom and an aryl ligand with a carboxylic acid having the structure of the carboxylate ligand A in a solution, and further adding an alcohol to cause the reaction.

[0036]

[13] A photosensitive composition containing the poor metal cluster compound according to any one of [1] to [9].

[0037]

[14] The photosensitive composition according to

[13] , further comprising a solvent.

[0038]

[15] The photosensitive composition according to claim

[13] or

[14] , wherein the poor metal cluster compound accounts for 50% by mass or more of the total solids of the components excluding the solvent.

[0039]

[16] The photosensitive composition according to any one of

[13] to

[15] , which reacts with actinic radiation having a wavelength of 6 nm to 15 nm.

[0040]

[17] A pattern forming method comprising the steps of applying the photosensitive composition according to any one of

[13] to

[16] to a substrate, exposing the applied photosensitive composition to actinic radiation, and developing the exposed photosensitive composition.

[0041]

[18] The pattern formation method according to

[17] , wherein the organic solvent contained in the developer used in the developing step is an organic solvent having a solubility parameter (SP value) of 7.5 to 11.

[0042]

[19] A substrate having a patterned layer obtained by the pattern forming method according to

[17] or

[18] .

[0043]

[20] A method for manufacturing a substrate in which a pattern layer is formed by the pattern forming method according to

[17] or

[18] .

[0044] The poor-metal cluster compound of the present invention is highly sensitive to extreme ultraviolet (EUV light), has high resolution, and is highly useful as a photoresist capable of forming ultrafine patterns. Because the poor-metal cluster compound of the present invention contains a carboxylate ligand A having an alicyclic structure, the bond between the carboxylate group and the alicyclic structure is easily cleaved by actinic radiation such as electron beam (EB) irradiation or extreme ultraviolet (EUV light) exposure. This cleavage makes the compound insoluble in organic solvents, resulting in the formation of negative patterns and excellent developability. Furthermore, because the metals have already aggregated in the cluster compound, the compound is considered to be a photosensitive composition with higher EUV sensitivity than complex compounds. Detailed Description of the Invention

[0045] The present invention will be described below based on one embodiment, but the present invention is not limited to this embodiment.

[0046] In addition, in this specification, there are some descriptions using "~" as a description expression to indicate a numerical range from a lower limit value to an upper limit value of a numerical value, but the numerical range in this description is a numerical range specified as being equal to or greater than the lower limit value and equal to or less than the upper limit value, including the lower limit value itself and the upper limit value itself.

[0047] In the present invention, the substituent refers to a (hydrogen atom), an alkyl group, a cycloalkyl group, an aromatic group, an ester group, a sulfonyl group, an alkoxy group, an amide group, an amino group, a carbonyl oxygen group, a halogen atom, or a group consisting of a combination of these groups. The organic group includes carbon-containing functional groups such as an aldehyde group or a carboxy group, or a hydrocarbon group, as well as functional groups such as a hydroxy group, a nitro group, an amino group, a sulfo group, and an alkoxy group, and groups having a structure consisting of two or more of these groups. Furthermore, the hydrocarbon group of the present invention may be substituted with one or more functional groups or halogen atoms. Examples of such functional groups include a hydroxy group, an aldehyde group, a carboxy group, a nitro group, an amino group, a sulfo group, and an alkoxy group, and examples of halogen atoms include fluorine, chlorine, bromine, and iodine. The organic group may contain a heteroatom, such as oxygen, nitrogen, phosphorus, sulfur, silicon, fluorine, chlorine, bromine, and iodine.

[0048] [Poor Metal Cluster Compound] A poor metal cluster compound according to one embodiment of the present invention (hereinafter also referred to as the present cluster compound) comprises a poor metal atom, a carboxylate ligand A, and an oxo ligand and / or a hydroxo ligand, wherein the carboxylate ligand has a carboxylate group bonded to an alicyclic structure. The carbon atom bonded to the carboxylate group in the alicyclic structure is preferably a tertiary or quaternary carbon.

[0049] The term "poor metal cluster compound" as used herein refers to a compound having multiple metal atoms, in which the metal atoms are bonded to each other via a metal-metal bond or are bonded to each other via one to three atoms, and it is preferable that the metal atoms are bonded to each other via an oxygen atom. Furthermore, the term "carboxylate ligand" refers to a ligand having at least one carboxylate group, and the carboxylate group is a functional group having the chemical structure -C(=O)O-. To more effectively obtain the effects of the present invention, a ligand having only one carboxylate group is preferred.

[0050] The oxo and / or hydroxo ligands of the present cluster compound are preferably μ-oxo ligands (—O—) in which an oxygen atom is coordinated between metals and / or μ-hydroxy ligands (—OH) in which a hydroxy group is coordinated to a metal, and there are 1 to 3, preferably 1 to 2, oxo and / or hydroxo ligands per poor metal atom.

[0051] The present cluster compound contains two or more poor-metal atoms. The poor-metal atoms are atoms of a poor-metal element, and a poor metal refers to a metal or metalloid element in the P-block elements (elements with valence electrons in the outermost P orbital) on the periodic table. Compared to transition metals, poor metals tend to have lower melting points and boiling points, higher electronegativity, and softer materials. Examples of poor-metal atoms include bismuth, antimony, aluminum, gallium, indium, thallium, tin, and lead. The poor-metal atoms in the present cluster compound are preferably one or more selected from these. Among these, bismuth, indium, or antimony are preferred from the viewpoints of high absorption of ionizing radiation and safety, with bismuth being particularly preferred. Bismuth is preferred because of its high mass number and high elemental density, resulting in high absorption of actinic radiation such as EUV, which is proportional to elemental density. The number of poor metal atoms in the present cluster compound is two or more, preferably 2 to 50, more preferably 4 to 40, and particularly preferably 6 to 20.

[0052] The alicyclic structure of the carboxylate ligand A of the present cluster compound is preferably a 3- to 8-membered ring, and more preferably a 3- to 6-membered ring. Examples of the alicyclic structure include a cycloalkyl group or a cycloalkenyl group. From the viewpoint of suppressing the occurrence of roughness after development, a cycloalkyl group (saturated) is preferred, and from the viewpoint of improving development contrast, a cycloalkenyl group (unsaturated) is preferred. In the case of a cycloalkenyl group, the position of the double bond is not particularly limited.

[0053] The carboxylate ligand A has an alicyclic structure to which a carboxylate group is directly bonded, from the viewpoints of ease of removal upon exposure and stability when not exposed. The carbon in the alicyclic structure to which the carboxylate group is bonded is preferably a tertiary or quaternary carbon. In the case of a tertiary carbon, it is preferable that a hydrogen atom is bonded, and in the case of a quaternary carbon, it is preferable that the carbon have a substituent R.

[0054] The substituent R is an organic group or a halogen atom. Such an organic group may contain a halogen atom or a heteroatom. Examples of the organic group include hydrocarbon groups, such as linear alkyl groups such as methyl and ethyl groups, branched alkyl groups such as isopropyl and butyl groups, halogenated alkyl groups such as halogenated methyl groups, halogenated ethyl groups, and halogenated propyl groups, cycloalkyl groups such as cyclopropyl and cyclobutyl groups, aryl groups such as phenyl and naphthyl groups, arylalkyl groups, and alkylaryl groups. Examples of organic groups containing a heteroatom include ester groups, sulfonyl groups, alkoxy groups, amide groups, amino groups, and carbonyl oxygen groups. Examples of ester groups include alkyl ester groups such as acetyl groups, ethyl ester groups, and n-propyl ester groups, and aromatic ester groups such as phenyl ester groups. Examples of sulfonyl groups include methylsulfonyl groups, ethylsulfonyl groups, and n-propylsulfonyl groups. Examples of alkoxy groups include alkoxyalkyl groups such as alkoxymethyl groups, alkoxyethyl groups, and alkoxypropyl groups. Examples of the amino group include amino alkyl groups such as amino (-NH), aminomethyl (NH-CH-), aminoethyl (NH-C-H-), and aminopropyl (NH-C-H-), as well as dialkylamino groups such as dimethylamino ((CH)N-) and diethylamino ((C-H)N-). Examples of the amide group include alkylamide groups such as methylamide ((CH)N(C=O)-) and ethylamide ((C-H)N(C=O)-). Examples of the halogen atom include fluorine, chlorine, and bromine. The substituent R preferably has 1 to 10 carbon atoms, more preferably 1 to 7, and particularly preferably 1 to 5. From the viewpoints of film formability, exposure sensitivity, and solvent solubility, the substituent R is preferably a hydrocarbon group, more preferably a saturated hydrocarbon group, and particularly preferably an alkyl group. The heteroatom or halogen atom that may be contained in the organic group includes oxygen, nitrogen, phosphorus, sulfur, silicon, chlorine, bromine, iodine, and the like.

[0055] In the present cluster compound, the carbon bonded to the carboxylate group refers to the carbon bonded to the carbonyl carbon of the carboxylate group. Such a carbon is preferably a carbon constituting the cyclic structure of the alicyclic structure, and it is preferable that the carbon constituting the cyclic structure of the alicyclic structure is directly bonded to the carbonyl carbon of the carboxylate group.

[0056] More specifically, the carboxylate ligand A of the present cluster compound is preferably one in which the carbon atom to which the carboxylate group is bonded, among the carbon atoms constituting the cyclic structure of the alicyclic structure, is further bonded to a hydrogen atom or the above-mentioned substituent R, and another carbon atom constituting the cyclic structure is bonded to a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms which may contain a heteroatom. More preferably, the other carbon atom constituting the cyclic structure is bonded to a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an amino group having 1 to 20 carbon atoms. Examples include those represented by the following general formula B-1 or general formulas C-1 to C-12.

[0057]

[0058] In the above general formula B-1, the substituent R represents a hydrogen atom or the above-mentioned substituent R. Specific examples and preferred embodiments of the substituent R are the same as those of the above-mentioned substituent R. Ａ are each independently a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms. Ａ may be the same or different. n is an integer of 1 to 6, preferably 1 to 3. However, from the viewpoint of reactivity, the substituent R and any of the substituents R Ａ It is preferable that the substituent R Ａ are each independently hydrogen, a halogen atom, or an organic group having 1 to 20 carbon atoms. Such an organic group may contain a halogen atom or a heteroatom. ＡSpecific examples of the organic group or halogen atom in the substituent R include the same as those of the substituent R. Preferred examples of the organic group include hydrocarbon groups, alkoxy groups, and amino groups. Ａ The organic group preferably has 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and particularly preferably 1 to 5 carbon atoms. Ａ is preferably a hydrogen atom, a halogen atom, a hydrocarbon group, an alkoxy group, or an amino group. More preferably, it is any one of a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an amino group having 1 to 20 carbon atoms, and even more preferably, it is any one of a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an amino group having 1 to 10 carbon atoms. Particularly preferably, it is any one of a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an amino group having 1 to 5 carbon atoms. Most preferably, it is a hydrogen atom.

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071] In the general formulas C-1 to C-12, the substituent R represents a hydrogen atom or the above-described substituent R. １~R １００ are each independently a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms. １ ~R １００ may be the same or different. Such organic groups may contain halogen atoms or heteroatoms. １ ~R １００ Specific examples of the organic group or halogen atom of the substituent R include the same as those of the substituent R. １ ~R １００ When R is an organic group, the number of carbon atoms is more preferably 1 to 10, and particularly preferably 1 to 6. １ ~R １００ When the substituent R is an organic group, it is preferably a hydrocarbon group, an alkoxy group, or an amino group. １ ~R １００ is preferably a hydrocarbon group or a hydrogen atom, and particularly preferably a hydrogen atom. １ ~R １００ are each independently preferably any one of a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and an amino group having 1 to 20 carbon atoms, more preferably any one of a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and an amino group having 1 to 10 carbon atoms. Further preferably, any one of a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and an amino group having 1 to 6 carbon atoms, and particularly preferably any one of a hydrogen atom and a hydrocarbon group having 1 to 6 carbon atoms. Most preferably, it is a hydrogen atom. However, from the viewpoint of reactivity, in each general formula, the substituent R and any one of the substituents R １ ~R １００ It is preferred that the and do not form a fused ring structure by linking them to each other.

[0072] The structure of the carboxylate ligand A can be analyzed by known techniques, for example, by NMR.

[0073] The molecular weight of the cluster compound is preferably 1,000 to 8,000, more preferably 1,000 to 6,000, and particularly preferably 1,500 to 5,000. If the molecular weight of the cluster compound is below the upper limit, the volume is small, and therefore roughness and resolution are expected to be improved. On the other hand, if the molecular weight is above the lower limit, coating properties and etching resistance tend to be improved. Note that this molecular weight is a guideline and does not determine lithography properties by itself, so it is not limited to this. The molecular weight of the cluster compound can be analyzed by known techniques, for example, mass spectrometry.

[0074] The present cluster compound may form a higher-order multimeric structure by linking together the above-described cluster structures as single units. Examples of such multimeric structures include dimeric to infinitemeric cluster compound structures. The present multimeric structure has a metal-poor cluster compound as a constituent unit, and may be formed by linking each cluster unit to another cluster unit through coordinate bonds of the ligands possessed by the cluster, or by crosslinking the cluster units with a linker ligand. The present multimeric structure can be analyzed by known techniques, for example, single-crystal X-ray crystallography.

[0075] [Production Method] The present cluster compound can be produced, for example, by reacting a compound containing a poor metal atom with a carboxylic acid having a carboxylate ligand A structure in a solution to obtain a complex compound, contacting this complex compound with an aqueous solvent or alcohol to promote clustering and precipitate, and filtering the precipitate. Alternatively, the complex compound may be produced by reacting a solution containing a compound containing a poor metal atom with a carboxylic acid having the above-mentioned carboxylate ligand A structure. Examples of aqueous solvents include acetone, methanol, ethanol, tetrahydrofuran, dichloromethane, and chloroform, which have absorbed moisture from the atmosphere or have a desired amount of water added. Examples of alcohols include methanol, ethanol, 1-propanol, 1-methoxy-2-propanol, and 4-methyl-2-pentanol.

[0076] Examples of compounds containing a poor metal atom include organic compounds containing poor metals such as bismuth, indium, antimony, and tin, and specific examples include trisphenylbismuth, tris-paratoluylbismuth, trialkoxybismuth, trisphenylantimony, and tris-paratoluylantimony.

[0077] Examples of carboxylic acids having a carboxylate ligand A structure include carboxylic acids in which a carboxy group is bonded to an alicyclic structure made of saturated hydrocarbon. The carboxylic acids exemplified below have a cyclohexane ring as the alicyclic structure, with a carboxy group and an organic group bonded to one carbon of the cyclohexane ring.

[0078]

[0079] Further, for example, a carboxylic acid in which a carboxy group is bonded to an alicyclic structure having one double bond in the cyclic structure can be mentioned. The carboxylic acids exemplified below have a cyclohexene ring as the alicyclic structure, with a carboxy group bonded to one carbon of the cyclohexene ring, and from the left, there are listed a structure without an organic group, a structure with an organic group at the ortho (o-) or para (p-) position, and a structure in which an organic group is bonded to the same carbon as the carbon to which the carboxy group is bonded.

[0080]

[0081] More specific examples of carboxylic acids having a structure of a carboxylate ligand A include cyclohexanecarboxylic acid, 1-phenylcyclopropane-1-carboxylic acid, 1-methylcyclopropane-1-carboxylic acid, 2-methyl-1-cyclohexanecarboxylic acid, 2-methoxycarbonyl-1-cyclohexanecarboxylic acid, 1-methyl-3-oxocyclobutane-1-carboxylic acid, 1-methyl-1-carboxylic acid, and 1-methylcyclobutane-1-carboxylic acid.

[0082] To explain the production method in more detail, a solution containing a compound containing a poor metal atom and a carboxylic acid having the above-mentioned carboxylate ligand structure are placed in a reaction vessel and stirred. A solvent may be added to dissolve the raw materials.

[0083] The reaction temperature is preferably room temperature to 150°C, more preferably room temperature to 120°C, from the viewpoints of completing the reaction and avoiding undesirable side reactions. The reaction time is preferably 1 to 100 hours, more preferably 3 to 24 hours. Subsequently, the residue obtained by distilling off the solvent from the reaction solution is dissolved or suspended in a water-containing solvent or alcohol and stirred. The reaction temperature is preferably room temperature to 100°C, more preferably room temperature to 60°C, from the viewpoints of completing the reaction and avoiding undesirable side reactions. The reaction time is preferably 0.5 hours or more, more preferably 1 to 100 hours, and even more preferably 3 to 24 hours. If the product precipitates or precipitates in a crystalline form after the reaction, it can be filtered to obtain the cluster compound. The solution after the reaction may be cooled to -30°C to 20°C to obtain the product precipitate or crystallize it. If no product precipitate is observed after the reaction, the target product can be recovered by distilling off the solvent by applying a reduced pressure to the reaction vessel. Alternatively, the product can be reprecipitated by contacting the reaction solution with a poor solvent. The reaction vessel is preferably a sealed vessel, and for small amounts, a Schlenk tube or the like can be used, and the reaction is preferably carried out under a nitrogen or argon atmosphere. The reaction vessel is preferably a flask equipped with a reflux condenser, and when heating, the reaction is preferably carried out under a nitrogen or argon atmosphere.

[0084] The solution containing the compound containing a poor metal atom and the carboxylic acid having the structure of carboxylate ligand A are preferably mixed in a ratio of 1:1 to 1:3, more preferably 1:3, in terms of the amount of the substances.

[0085] The present cluster compound can also be produced, for example, by reacting a complex containing a poor metal atom and an aryl ligand with a carboxylic acid having a structure of carboxylate ligand A in a solution, and then adding an alcohol to the solution and reacting the resulting mixture. Examples of complexes containing poor metal atoms and aryl ligands include trisphenylbismuth, tris-paratoluylbismuth, trisphenylantimony, and tris-paratoluylantimony, and examples of alcohols include methanol, ethanol, 1-propanol, 1-methoxy-2-propanol, and 4-methyl-2-pentanol.

[0086] [Photosensitive Composition] A photosensitive composition according to one embodiment of the present invention (hereinafter also referred to as the present photosensitive composition) contains the present cluster compound. The present photosensitive composition may contain only one type of the present cluster compound, or may contain two or more types of the present cluster compound.

[0087] The photosensitive composition contains the cluster compound at a concentration of 50% by mass or more, preferably 60 to 100% by mass, and particularly preferably 70 to 90% by mass of total solids relative to the total components of the photosensitive composition other than the solvent. The term "total solids" refers to the solid obtained by evaporating the photosensitive composition to dryness. The concentration of the cluster compound in the photosensitive composition is preferably 0.1% by mass or more and 70% by mass or less, more preferably 0.5% by mass or more and 50% by mass or less, and particularly preferably 1% by mass or more and 40% by mass or less. When the concentration of the cluster compound in the photosensitive composition is equal to or greater than the lower limit, good exposure sensitivity can be obtained.

[0088] [Photoacid Generator] The photosensitive composition can also function by containing, together with the cluster compound, a photoacid generator that generates an acid when exposed to actinic radiation. Examples of actinic radiation include the bright line spectrum of a mercury lamp, far ultraviolet radiation represented by an excimer laser, extreme ultraviolet radiation (EUV light), X-rays, and electron beams. From the viewpoint of resolution, a shorter exposure wavelength is preferred, and extreme ultraviolet radiation (EUV light) emitting light with a wavelength of 6 nm to 15 nm is preferred.

[0089] The photoacid generator that generates an acid when exposed to actinic radiation is not particularly limited as long as it is a known compound, but is preferably a compound that generates an organic acid, such as at least one of sulfonic acid, bis(alkylsulfonyl)imide, and tris(alkylsulfonyl)methide, when exposed to actinic radiation.

[0090] The photoacid generators can be used alone or in combination of two or more. When two or more types are used in combination, preferred embodiments include (1) the use of two photoacid generators with different acid strengths, and (2) the use of two photoacid generators with different sizes (molecular weights or carbon numbers) of the acids they generate. Examples of the embodiment (1) include the use of a fluorine-containing sulfonic acid generator and a tris(fluoroalkylsulfonyl)methide acid generator, a fluorine-containing sulfonic acid generator and a non-fluorine-containing sulfonic acid generator, and an alkylsulfonic acid generator and an arylsulfonic acid generator. Examples of the embodiment (2) include the use of two photoacid generators whose acid anions differ in the number of carbon atoms by four or more.

[0091] In particular, the present photosensitive composition is preferably a photosensitive composition for use with actinic radiation. A photosensitive composition that reacts with actinic radiation is preferred because its development speed in a developer changes, allowing a pattern to be formed after a certain period of development. As actinic radiation, a shorter wavelength is preferred because higher resolution can be obtained, and actinic radiation with a wavelength of 6 nm to 15 nm is preferred, and more preferably actinic radiation with a wavelength of 6.5 nm to 13.5 nm is preferred. In other words, extreme ultraviolet (EUV) light is preferred. In other words, the present photosensitive composition is preferably a photosensitive composition that reacts with actinic radiation with a wavelength of 6 nm to 15 nm. "Reaction" refers to the photosensitive composition absorbing the irradiated actinic radiation and then being modified by the generated active species, such as radicals and ions.

[0092] The present photosensitive composition reacts with light even when used alone in the photosensitive composition. Adding a photoacid generator synergistically enhances the photosensitivity of the present cluster compound in the photosensitive composition, thereby enhancing the photosensitivity of the present cluster compound. Therefore, adding a photoacid generator is preferable when a photosensitive composition composed solely of the present cluster compound does not have sufficient photosensitivity for the required specifications. When the present photosensitive composition contains a photoacid generator, the content of the photoacid generator in the present photosensitive composition (the total amount when multiple photoacid generators are used) is preferably 0.1 to 30 mass %, more preferably 0.5 to 20 mass %, and even more preferably 1 to 15 mass %, based on the total of all components of the photosensitive composition other than the solvent. When the content of the photoacid generator in the photosensitive composition is at or above the lower limit, the effect of enhancing photosensitivity is obtained. When the content is below the upper limit, the composition is less susceptible to the poor film-forming properties of the photoacid generator, thereby achieving good film-forming properties based on the photosensitive compound of the present invention, which is preferable.

[0093] [Solvent] The present photosensitive composition may generally contain a solvent for preparing the composition. The solvent for preparing the photosensitive composition is not particularly limited as long as it dissolves each component, and examples thereof include toluene, alkylene glycol monoalkyl ether carboxylates (such as propylene glycol monomethyl ether acetate (PGMEA, also known as 1-methoxy-2-acetoxypropane)), alkylene glycol monoalkyl ethers (such as propylene glycol monomethyl ether (PGME; 1-methoxy-2-propanol)), alkyl lactate esters (such as ethyl lactate and methyl lactate), cyclic lactones (such as γ-butyrolactone, preferably having 4 to 10 carbon atoms), linear or cyclic ketones (such as 2-heptanone and cyclohexanone, preferably having 4 to 10 carbon atoms), alkylene carbonates (such as ethylene carbonate and propylene carbonate), alkyl carboxylates (preferably alkyl acetates such as butyl acetate), alkyl alkoxyacetates (ethyl ethoxypropionate), alkylamides (N,N-dimethylformamide), and alkyl sulfoxides (dimethyl sulfoxide). Other usable solvents include, for example, the solvents described in paragraphs

[0244] and after of US Patent Application Publication No. 2008 / 0248425A1.

[0094] Of the above, toluene, PGMEA, ethyl lactate, cyclohexanone, 2-heptanone, N,N-dimethylformamide, dimethyl sulfoxide, alkylene glycol monoalkyl ether carboxylate, and alkylene glycol monoalkyl ether are preferred.

[0095] These solvents may be used alone or in combination of two or more. When two or more solvents are mixed, it is preferable to mix a solvent having a hydroxyl group with a solvent not having a hydroxyl group. As the solvent having a hydroxyl group, alkylene glycol monoalkyl ether is preferred, and as the solvent not having a hydroxyl group, alkylene glycol monoalkyl ether carboxylate, N,N-dimethylformamide, and dimethyl sulfoxide are preferred.

[0096] The solvent for the present photosensitive composition preferably has a solubility parameter (SP value) of 7.5 to 11, more preferably 8 to 11. The solubility parameter (SP value) will be described later.

[0097] The content of the solvent in the total amount of the photosensitive composition can be adjusted as appropriate depending on the film thickness of the pattern to be formed, etc., but is generally adjusted so that the total concentration of components other than the solvent in the photosensitive composition is 0.5 to 30 mass %, preferably 1.0 to 20 mass %, more preferably 1.5 to 10 mass %, and particularly preferably 1.5 to 5 mass %.

[0098] [Surfactant] The photosensitive composition preferably further contains a surfactant. The surfactant is preferably a fluorine-based and / or silicone-based surfactant. Examples of such surfactants include Megafac F176 and Megafac R08 manufactured by Dainippon Ink and Chemicals, Inc., PF656 and PF6320 manufactured by OMNOVA, Troisol S-366 manufactured by Troy Chemical Co., Ltd., Fluorad FC430 manufactured by Sumitomo 3M Limited, and Polysiloxane Polymer KP-341 manufactured by Shin-Etsu Chemical Co., Ltd. Surfactants other than fluorine-based and / or silicone-based surfactants can also be used. More specifically, examples include polyoxyethylene alkyl ethers and polyoxyethylene alkylaryl ethers.

[0099] Other known surfactants may also be used as appropriate. Examples of usable surfactants include those described in paragraphs

[0273] and after in U.S. Patent Application Publication No. 2008 / 0248425A1.

[0100] The surfactant may be used alone or in combination of two or more kinds. The content of the surfactant is preferably 0.0001 to 2% by mass, more preferably 0.001 to 1% by mass, based on the total mass of the components other than the solvent in the photosensitive composition.

[0101] [Resin] The photosensitive composition can be used alone to form a pattern, but it may also contain a resin material in addition to the cluster compound. Resin materials are not particularly limited as long as they are soluble in a solvent, and examples include novolac resins, styrene resins, and acrylic resins. They may be used alone or in combination of two or more types. Their molecular structure may contain dissolution-inhibiting groups that decompose in the presence of chemically active species such as acids or radicals, or crosslinking groups that crosslink, or they may be copolymer resins of two or more types. Examples of dissolution-inhibiting groups that decompose in the presence of chemically active species such as acids or radicals include alkoxycarbonyl groups and acetal groups. Examples of crosslinking groups that crosslink in the presence of chemically active species such as acids or radicals include vinyl groups, carbodiimide groups, N-hydroxyester groups, imide ester groups, maleimide groups, haloacetyl groups, pyridyl disulfide groups, hydrazide groups, alkoxyamino groups, and diazirine groups.

[0102] [Other Additives] In addition to the components described above, the photosensitive composition may contain, as appropriate, carboxylic acids, carboxylic acid onium salts, dissolution-inhibiting compounds with a molecular weight of 3,000 or less as described in, for example, Proceedings of SPIE, 2724, 355 (1996), dyes, plasticizers, photosensitizers, light absorbers, crosslinking agents, antioxidants, and the like. Carboxylic acids are particularly preferred for improving performance. Preferred carboxylic acids include aromatic carboxylic acids such as benzoic acid and naphthoic acid. The carboxylic acid content is preferably 0.01 to 10% by mass, more preferably 0.01 to 5% by mass, and even more preferably 0.01 to 3% by mass, based on the total weight of the components of the photosensitive composition other than the solvent.

[0103] [Method for Producing the Photosensitive Composition] The photosensitive composition can be produced by dissolving the cluster compound, a photoacid generator (if used) and other components in a solvent for preparation, and filtering the solution through a filter, if necessary. The filter is preferably made of polytetrafluoroethylene, polyethylene, or nylon, with a pore size of 0.2 μm or less, more preferably 0.1 μm or less, and even more preferably 0.05 μm or less.

[0104] [Pattern Forming Method] A pattern forming method according to one embodiment of the present invention (hereinafter also referred to as the present pattern forming method) comprises the steps of applying the present photosensitive composition to a substrate, exposing the applied photosensitive composition to actinic radiation, and developing the exposed photosensitive composition. More specifically, the steps comprise the steps of applying the present photosensitive composition to a substrate to form a photosensitive layer, irradiating predetermined regions of the photosensitive layer with actinic radiation to perform pattern exposure, and developing the exposed photosensitive layer to selectively remove exposed or unexposed regions of the photosensitive layer. The photosensitive layer forming step yields a substrate having a photosensitive layer. The pattern exposure step yields a substrate having a photosensitive layer with a latent image. The development step yields a substrate having a patterned layer.

[0105] [Photosensitive Layer Formation Step] The photosensitive layer can be formed by applying the photosensitive composition to a substrate (e.g., silicon or silicon dioxide coated) such as those used in the manufacture of integrated circuit devices using a suitable coating method such as a spinner, followed by drying at 50 to 150°C. In this case, a commercially available inorganic or organic antireflective film can be used, if necessary. Furthermore, an antireflective film can be applied to the resist underlayer.

[0106] [Exposure Step] In the present invention, unless otherwise specified, "exposure to actinic radiation" includes not only exposure with far ultraviolet light typified by mercury lamps and excimer lasers, X-rays, extreme ultraviolet light (EUV light), and the like, but also exposure with particle beams such as electron beams and ion beams. Exposure can be performed by irradiating predetermined regions of the formed photosensitive layer with actinic radiation through a predetermined mask to perform pattern exposure, or by irradiating with an electron beam to perform pattern exposure without using a mask (direct writing). The actinic radiation is not particularly limited, but examples include KrF excimer lasers, ArF excimer lasers, extreme ultraviolet light (EUV light), and electron beams. Extreme ultraviolet light (EUV light) and electron beams are preferred, and as described above, extreme ultraviolet light (EUV light) emitting actinic radiation with a wavelength of 6 nm to 15 nm is preferred.

[0107] After the exposure, baking (heating) may or may not be performed before development. When baking (heating) is performed, the heating temperature is preferably 50 to 200°C, more preferably 60 to 180°C, and even more preferably 80 to 150°C. When baking (heating) is performed, the heating time is preferably 30 to 300 seconds, more preferably 30 to 180 seconds, and even more preferably 30 to 90 seconds. Heating can be performed by means provided in a typical exposure / developing machine, and may be performed using a hot plate or the like.

[0108] [Development Step] After exposure, development is carried out to selectively remove the exposed or unexposed areas of the photosensitive layer. As the development method, a known method can be adopted, for example, a method using a gas or a method using a developer.

[0109] <Developer> It is preferable to use an organic solvent as the developer, and an organic solvent having a vapor pressure of 5 kPa or less at 20° C. is preferred, more preferably 3 kPa or less, and particularly preferably 2 kPa or less. By setting the vapor pressure of the organic solvent to 5 kPa or less, evaporation of the developer on the substrate or in the developing cup is suppressed, improving the temperature uniformity within the surface of the pattern-formed substrate, and as a result, improving the dimensional uniformity within the surface of the pattern-formed substrate.

[0110] As the organic solvent used as the developer, various organic solvents can be used, and for example, at least one solvent selected from ester-based solvents, ketone-based solvents, alcohol-based solvents, amide-based solvents, sulfoxide-based solvents, ether-based solvents, hydrocarbon-based solvents, and the like can be used.

[0111] Examples of ester solvents include alkyl carboxylate solvents such as methyl acetate, butyl acetate, ethyl acetate, isopropyl acetate, amyl acetate, ethyl-3-ethoxypropionate, propylene glycol diacetate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, methyl formate, ethyl formate, butyl formate, propyl formate, ethyl lactate, butyl lactate, and propyl lactate; alkylene glycol monomethyl ether acetate (PGMEA; also known as 1-methoxy-2-acetoxypropane), ethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, and propylene glycol monoethyl ether acetate; and alkylene glycol monoalkyl ether carboxylate solvents such as butyl acetate, amyl acetate, ethyl lactate, and propylene glycol monomethyl ether acetate are more preferred.

[0112] Examples of ketone solvents include 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetone, 4-heptanone, 1-hexanone, 2-hexanone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, phenylacetone, methyl ethyl ketone, methyl amyl ketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, ionone, diacetonyl alcohol, acetylcarbinol, acetophenone, methyl naphthyl ketone, isophorone, and propylene carbonate. Alkyl ketone solvents, such as methyl isobutyl ketone, methyl amyl ketone, cyclopentanone, cyclohexanone, and 2-heptanone, are more preferred.

[0113] Examples of alcohol-based solvents include alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol including 1-propanol or 2-propanol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, hexyl alcohol such as n-hexyl alcohol, heptyl alcohol such as n-heptyl alcohol, octyl alcohol such as n-octyl alcohol, and n-decanol; and glycols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, and 1,4-butylene glycol. Examples of suitable solvents include alkylene glycol monoalkyl ether solvents such as ethylene glycol monomethyl ether, propylene glycol monomethyl ether (PGME; also known as 1-methoxy-2-propanol), ethylene glycol monoethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, and triethylene glycol monoethyl ether; glycol ether solvents such as methoxymethylbutanol and propylene glycol dimethyl ether; and phenolic solvents such as phenol and cresol, with 1-hexanol, 2-hexanol, 1-octanol, 2-ethylhexanol, propylene glycol monomethyl ether, and cresol being more preferred.

[0114] Examples of the amide solvent that can be used include N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, hexamethylphosphoric triamide, 1,3-dimethyl-2-imidazolidinone, etc. Examples of the sulfoxide solvent that can be used include dimethyl sulfoxide, etc.

[0115] Examples of the ether solvent include the alkylene glycol monoalkyl ether solvents and glycol ether solvents described above, as well as dioxane, tetrahydrofuran, tetrahydropyran, and the like.

[0116] Examples of hydrocarbon solvents include aromatic hydrocarbon solvents such as toluene and xylene, and aliphatic hydrocarbon solvents such as pentane, hexane, octane, decane, and dodecane.

[0117] The developer preferably contains one or more solvents selected from alkylene glycol monoalkyl ether carboxylate solvents, alkylene glycol monoalkyl ether solvents, alkyl carboxylate solvents, and alkyl ketone solvents, and more preferably contains one or more solvents selected from dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, ethylene glycol, methyl alcohol, ethyl alcohol, 1-propanol, and 2-propanol.

[0118] As the developer, it is preferable to use a developer containing at least one organic solvent selected from the group consisting of ester solvents having no hydroxyl group in the molecule, ketone solvents having no hydroxyl group in the molecule, and ether solvents having no hydroxyl group in the molecule, amide solvents, and sulfoxide solvents.

[0119] The organic solvent used as the developer in the present invention is preferably an organic solvent having a solubility parameter (SP value) of 7.5 to 11. An organic solvent with a solubility parameter of 7.5 or more increases the development rate of the dissolved portion, while an organic solvent with a solubility parameter of 11 or less can suppress the development rate of the pattern formation portion, and is therefore preferred. The solubility parameter of the organic solvent of the developer is more preferably 8 to 11.

[0120] In the present invention, the solubility parameter (SP value) is calculated by the method proposed by Fedors et al. Specifically, the value is determined by referring to "POLYMER ENGINEERING AND SCIENCE, FEBRUARY, 1974, Vol. 14, No. 2, ROBERT F. FEDORS. (pp. 147-154)." The SP value is a physical property determined by the content of hydrophobic and hydrophilic groups in the molecule, and when a mixed solvent is used, the SP value refers to the value of the mixture.

[0121] Examples of organic solvents that satisfy the above SP values ​​include diethylene glycol monomethyl ether (SP value = 10.7), triethylene glycol monomethyl ether (SP value = 10.7), ethylene glycol monoisopropyl ether (SP value = 10.9), ethylene glycol monobutyl ether (SP value = 10.2), diethylene glycol monobutyl ether (SP value = 10.0), triethylene glycol monobutyl ether (SP value = 10.0), ethylene glycol monoisobutyl ether (SP value = 9.1), ethylene glycol monohexyl ether (SP value = 9.9), diethylene glycol monohexyl ether (SP value = 9.7), diethylene glycol mono-2-ethylhexyl ether (SP value = 9.3), ethylene glycol monoallyl ether (SP value = 10.8), ethylene glycol monophenyl ether (SP value = 10.8), ethylene glycol monobenzyl ether (SP value = 10.9), propylene glycol monomethyl ether (SP value = 10.0), dipropylene glycol monomethyl ether (SP value = 10.0), and dipropylene glycol monomethyl ether (SP value = 10.0). propylene glycol monomethyl ether (SP value = 9.7), tripropylene glycol monomethyl ether (SP value = 9.4), propylene glycol monopropyl ether (SP value = 9.6), dipropylene glycol monopropyl ether (SP value = 9.8), propylene glycol monobutyl ether (SP value = 9.0), dipropylene glycol monobutyl ether (SP value = 9.6), ethylene glycol monomethyl ether acetate (SP value = 10.0), ethylene glycol monoethyl ether acetate ether acetate (SP value = 9.6), ethylene glycol monobutyl ether acetate (SP value = 8.9), diethylene glycol monoethyl ether acetate (SP value = 9.4), diethylene glycol monobutyl ether acetate (SP value = 9.0), propylene glycol monomethyl ether acetate (SP value = 9.4), propylene glycol monoethyl ether acetate (SP value = 9.0), or dipropylene glycol monomethyl ether acetate (SP value = 9.2).

[0122] The organic solvents mentioned above may be used in combination, or may be used in combination with a solvent other than those mentioned above or with water.

[0123] The concentration of the organic solvent (total when a plurality of organic solvents are mixed) in the developer is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. It is particularly preferred that the developer essentially consists of an organic solvent. The term "essentially consisting of an organic solvent" includes the case where the developer contains trace amounts of a surfactant, an antioxidant, a stabilizer, an antifoaming agent, etc.

[0124] The water content in the developer is preferably 10% by mass or less, more preferably 5% by mass or less, particularly preferably 3% by mass or less, and most preferably substantially no water. By keeping the water content at 10% by mass or less, good development characteristics can be obtained.

[0125] If necessary, an appropriate amount of a surfactant can be added to the developer used in the present invention. The surfactant may be the same as those described above as surfactants used in the photosensitive composition of the present invention. The amount of the surfactant used is usually 0.001 to 5% by mass, preferably 0.005 to 2% by mass, and more preferably 0.01 to 0.5% by mass, based on the total amount of the developer.

[0126] <Development Method> Examples of development methods that can be used include a method in which a substrate is immersed in a tank filled with a developer for a certain period of time (dip method), a method in which a developer is piled up on the surface of a substrate by surface tension and left standing for a certain period of time (puddle method), a method in which a developer is sprayed onto the surface of the substrate (spray method), and a method in which a developer is continuously dispensed onto a substrate rotating at a constant speed while a developer dispenser nozzle is scanned at a constant speed (dynamic dispense method). Furthermore, after the development step, a step of stopping development by replacing the solvent with another solvent may be carried out. The development time is preferably a time required for the cluster compound and the like in the photosensitive layer in the unexposed or exposed areas to be sufficiently dissolved, typically 10 to 300 seconds, more preferably 20 to 120 seconds. The temperature of the developer is preferably 0 to 50°C, more preferably 15 to 35°C. The amount of developer can be appropriately adjusted depending on the development method.

[0127] [Rinsing Step] The pattern forming method of the present invention may include, after the developing step, a step of washing with a rinse liquid containing an organic solvent.

[0128] <Rinse Liquid> The organic solvent used in the rinse liquid preferably has a vapor pressure of 0.05 kPa or more and 5 kPa or less, more preferably 0.1 kPa or more and 5 kPa or less, and most preferably 0.12 kPa or more and 3 kPa or less at 20° C. By adjusting the vapor pressure of the organic solvent used in the rinse liquid to 0.05 kPa or more and 5 kPa or less, the temperature uniformity within the wafer surface is improved, and further swelling due to penetration of the rinse liquid is suppressed, improving the dimensional uniformity within the wafer surface.

[0129] Various organic solvents can be used as the rinse solution. However, for the present cluster compound, it is preferable to use a rinse solution containing at least one organic solvent selected from hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents, amide solvents, and ether solvents, or water. More preferably, after development, a cleaning step is performed using a rinse solution containing at least one organic solvent selected from ketone solvents, ester solvents, alcohol solvents, amide solvents, and hydrocarbon solvents. Even more preferably, after development, a cleaning step is performed using a rinse solution containing at least one organic solvent selected from the group consisting of alcohol solvents and hydrocarbon solvents. Specific examples of ketone solvents, ester solvents, alcohol solvents, amide solvents, ether solvents, and hydrocarbon solvents used as the rinse solution are the same as those described above for the developer. It is particularly preferable to use a rinse solution containing at least one organic solvent selected from the group consisting of monohydric alcohol solvents, hydrocarbon solvents, and amide solvents.

[0130] Here, examples of the monohydric alcohol solvent used in the rinsing step after development include linear, branched, and cyclic monohydric alcohols. Specific examples include 1-butanol, 2-butanol, 3-methyl-1-butanol, tert-butyl alcohol, isopropyl alcohol, cyclopentanol, and cyclohexanol, with 1-butanol, 2-butanol, 3-methyl-1-butanol, and isopropyl alcohol being preferred. Examples of the hydrocarbon solvent include aromatic hydrocarbon solvents such as toluene and xylene, and aliphatic hydrocarbon solvents such as octane, decane, and dodecane. Examples of the amide solvent include N,N-dimethylformamide.

[0131] The above-mentioned components may be mixed in plural, or may be mixed with an organic solvent other than those mentioned above.

[0132] The organic solvent may be mixed with water, but the water content in the rinse solution is usually 30% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 3% by mass or less. Most preferably, the rinse solution does not contain water. By keeping the water content at 30% by mass or less, good development properties can be obtained.

[0133] The rinse solution may contain an appropriate amount of a surfactant, which may be the same as those used in the photosensitive composition described above, and the amount of surfactant used is usually 0.001 to 5 mass %, preferably 0.005 to 2 mass %, and more preferably 0.01 to 0.5 mass %, based on the total amount of the rinse solution.

[0134] <Rinsing Method> In the rinsing step, the developed pattern-formed substrate is washed with a rinse solution containing the organic solvent. The washing method is not particularly limited, but examples include a method in which the rinse solution is continuously applied to a substrate rotating at a constant speed (spin coating method), a method in which the substrate is immersed in a tank filled with the rinse solution for a certain period of time (dipping method), and a method in which the rinse solution is sprayed onto the substrate surface (spray method). Among these, the spin coating method is preferred for washing, and after washing, the substrate is rotated at a speed of 2000 to 4000 rpm to remove the rinse solution from the substrate. The substrate rotation time can be set depending on the rotation speed within a range that achieves removal of the rinse solution from the substrate, but is typically 10 seconds to 3 minutes. Rinsing is preferably performed at room temperature. The rinse time is preferably set so that no developing solvent remains on the substrate, typically 10 to 300 seconds, more preferably 20 to 120 seconds. The temperature of the rinse solution is preferably 0 to 50°C, and even more preferably 15 to 35°C. The amount of the rinse solution can be adjusted appropriately depending on the rinse method.

[0135] [Post-treatment Step] After the development treatment or rinsing treatment, a treatment can be performed using a supercritical fluid to remove the developer or rinsing solution adhering to the pattern. Furthermore, after the development treatment, rinsing treatment, or treatment with a supercritical fluid, a heat treatment can be performed to remove the solvent remaining in the pattern. The heating temperature and time are not particularly limited as long as a good resist pattern can be obtained, and are usually 40 to 160°C and 10 seconds to 3 minutes. The heat treatment may be performed multiple times.

[0136] [Uses] The photosensitive composition and the pattern forming method are suitable for use in producing semiconductor microcircuits, such as in the production of VLSIs and high-capacity microchips, and can produce substrates having patterned layers. During the production of semiconductor microcircuits, the patterned resist film is subjected to circuit formation and etching, and the remaining resist film portion is ultimately removed with a solvent or the like.

[0137] An example of the present invention will be described below. However, the present invention is not limited to this example. In the example, "parts" and "%" are by mass unless otherwise specified.

[0138] The following complex compounds 1 and 2 were synthesized to obtain cluster compounds 1 and 2. The composition and ligand structure of each compound are as follows: １ The cluster compounds were identified by H-NMR. The structure of the cluster compounds was also identified by single-crystal X-ray crystal structure analysis. This measurement was performed using an XtaLAB Synergy-S manufactured by Rigaku Corporation, with a Mo(Kα) radiation source and a measurement temperature of 100K.

[0139] [Synthesis of Complex Compound 1] Paratolyl bismuth (5.0 g, 10.4 mmol) and 3-cyclohexene-1-carboxylic acid (3.92 g, 31.1 mmol) were placed in a flask and dissolved in 30 mL of toluene. A reflux condenser was attached to the flask and the mixture was heated at 80°C for 3 hours. The solvent was removed under reduced pressure, leaving a white waxy solid. This solid was dried in a vacuum oven (90°C), cooled to room temperature, and crushed to obtain a white powder of Complex Compound 1 (6.05 g, 10.4 mmol) shown below. Complex Compound 1 was identified by NMR measurement. 1 H-NMR: 1.6-1.8 (m, 1H), 1.9-2.2 (m, 3H), 2.1-2.4 (m, 2H), 2.4-2.6 (m, 1H), 5.7 (m, 2H). Bi: carboxlate=1:3

[0140]

[0141] [Synthesis of Cluster Compound 1] Paratolyl bismuth (28.6 g, 59.3 mmol) and 3-cyclohexene-1-carboxylic acid (21.9 g, 176 mmol) were placed in a flask and dissolved in 50 mL of toluene. A reflux condenser was attached to the flask and the mixture was heated at 75°C for 3 hours. The solvent was removed under reduced pressure to obtain a waxy solid. Methanol (150 mL) was added to this and stirred for 1 hour, causing the waxy solid to precipitate as a powdery solid. This was filtered to recover the white precipitate (19.3 g, 4.86 mmol), which was then dried under vacuum to obtain a white powder. NMR analysis confirmed that the white powder was Cluster Compound 1, shown below. 1 H-NMR: 1.6-1.8 (m, 1H), 1.9-2.2 (m, 3H), 2.1-2.4 (m, 2H), 2.4-2.6 (m, 1H), 5.7 (m, 2H). Bi / ligand=1: 1.4

[0142]

[0143] [Creation of Single Crystals of Cluster Compound 1] The structure of cluster compound 1 was determined separately by single crystal X-ray crystal structure analysis. Complex compound 1 (100 mg) was dissolved in 5 mL of methanol in a vial and left at room temperature for more than one week, resulting in the precipitation of colorless, transparent crystals. This single crystal was analyzed by single crystal X-ray crystal structure analysis. From Bi １０ O ８ It was confirmed that a cluster structure consisting of a core was formed. That is, this cluster structure had an oxo ligand. Furthermore, this cluster structure was linked to each other via a carboxylate ligand to form a multimeric structure with the cluster structure as one unit.

[0144] [Synthesis of Complex Compound 2] A white powder of Complex Compound 2 was obtained in the same manner as in Complex Compound 1, except that 3-cyclohexene-1-carboxylic acid was changed to cyclohexanecarboxylic acid. Complex Compound 2 was identified by NMR measurement. 1H-NMR: 1.1-1.3 (m, 3H), 1.4-1.6 (m, 2H), 1.6-1.7 (m, 1H), 1.7-1.8 (m, 2H), 1.8-2.0 (m, 2H), 2.2-2.3 (m, 1H). Bi: carboxlate=1:3

[0145]

[0146] [Creation of single crystals of cluster compound 2] Single crystals of cluster compound 2 were obtained in the same manner as in the case of cluster compound 1. The single crystals were analyzed by single crystal X-ray crystallography. From Bi １０ O ８ It was confirmed that a cluster structure consisting of a core had been formed. In other words, this cluster structure had oxo ligands. Furthermore, these cluster structures were linked to each other via carboxylate ligands to form a metal-organic framework with the cluster structure as one unit. The single crystal was dried in a vacuum oven to obtain a white powder. NMR measurement confirmed that the white powder was cluster compound 2 shown below. 1 H-NMR: 1.1-1.3 (m, 3H), 1.4-1.6 (m, 2H), 1.6-1.7 (m, 1H), 1.7-1.8 (m, 2H), 1.8-2.0 (m, 2H), 2.2-2.3 (m, 1H). Bi / ligand=1: 1.4

[0147]

[0148] <Preparation of Photosensitive Composition (Resist Solution)> The above cluster compound 1 was dissolved in ethyl lactate at a concentration of 5% by mass and filtered through a 0.2 μm filter to obtain resist solution 1. As a comparative compound, polystyrene manufactured by Aldrich (hereinafter sometimes referred to as PS, weight average molecular weight 4000) was dissolved in propylene glycol monomethyl ether acetate at a concentration of 2% by mass and filtered through a 0.2 μm filter to obtain resist solution 2.

[0149] <Formation of Resist Film> The prepared resist solution was applied by spin coating onto a patterned substrate (silicon wafer) to form a resist film with a thickness of about 40 nm.

[0150] <Sensitivity Measurement> Example 1: The resist film of the above-mentioned cluster compound 1 was exposed to extreme ultraviolet light (EUV) at different doses and then developed. Development was carried out using ethyl lactate (25°C, 30 seconds), and the film thickness of the negative pattern obtained by development was measured with a contact step gauge, and the EUV dose at which the amount of change in film thickness increased was maximized was determined as an index of sensitivity. The sensitivity was measured using the exposure dose (unit: mJ / cm ２ The sensitivity was measured in the same manner as in Example 1, except that the resist film was changed to a PS resist film and the development was changed to PGMEA (25°C, 60 seconds). The results are shown in Table 1.

[0151]

[0152] From the results in Table 1, it was confirmed that, compared with Comparative Example 1, Example 1 had a smaller EUV irradiation dose when the amount of change in film thickness was at its maximum, and therefore had a higher sensitivity.

[0153] <Pattern Writing> Example 2: A pattern was written on a resist film of the above-mentioned cluster compound 1 using an electron beam writing apparatus (electron beam acceleration voltage: 100 keV). The resist film after electron beam writing was developed in the same manner as in Example 1. Resolution was evaluated by writing line and space (line:space = 1:1) patterns with hp (half pitch) of 100 nm, 50 nm, and 30 nm, developing the patterns, and observing each pattern with a scanning electron microscope. The case where a line and space pattern was confirmed was rated "A," the case where a pattern was confirmed but partially crosslinked was rated "B," and the case where no pattern was confirmed was rated "C."

[0154] Comparative Example 2: Pattern writing was carried out in the same manner as in Example 2, except that the resist was changed to a PS (polystyrene) resist film and the development was changed to PGMEA (25° C., 60 seconds). The results are shown in Table 2.

[0155]

[0156] From the results in Table 2, it was confirmed that Example 2 was superior in pattern resolution at hp 50 nm and hp 30 nm compared to Comparative Example 2.

Claims

1. A poor metal cluster compound comprising a poor metal atom, a carboxylate ligand A, and an oxo and / or hydroxo ligand, wherein the carboxylate ligand A has an alicyclic structure to which the carboxylate group is bonded.

2. The poor metal cluster compound according to claim 1, wherein the alicyclic structure is a 3- to 8-membered ring.

3. The poor metal cluster compound according to claim 1, wherein the alicyclic structure is a cycloalkyl group.

4. The poor metal cluster compound according to claim 1, wherein the carboxylate ligand A is represented by the following general formula B-1: In the above general formula B-1, R is a hydrogen atom, a halogen atom, or an organic group. Ａ are each independently a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms. Ａ They may be the same or different, and n is an integer of 1 to 6.

5. The poor metal cluster compound according to claim 1, wherein the alicyclic structure is a cycloalkenyl group.

6. The poor metal cluster compound according to claim 1, wherein the carboxylate ligand A is at least one selected from the compounds represented by the following general formulae C-1 to C-12: In the above general formulas C-1 to C-12, R is a hydrogen atom, a halogen atom, or an organic group. １ ~R １００ are each independently a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms. １ ~R １００ may be the same or different.

7. The poor metal cluster compound according to claim 1, wherein the poor metal atom is at least one selected from the group consisting of bismuth, indium, and antimony.

8. The poor metal cluster compound according to claim 1, wherein the poor metal atoms are bonded to each other via oxygen atoms.

9. The poor metal cluster compound according to claim 1, wherein a functional group selected from an organic group having 1 to 20 carbon atoms, an alkoxy group, and an amino group is bonded to any carbon atom in the alicyclic structure.

10. A polymeric structure having the poor metal cluster compound according to any one of claims 1 to 9 as a constituent unit.

11. A method for producing a poor metal cluster compound according to any one of claims 1 to 9, comprising the step of reacting a compound containing the poor metal atom with a carboxylic acid having the structure of the carboxylate ligand A in a solution.

12. A method for producing a poor metal cluster compound according to any one of claims 1 to 9, comprising the steps of reacting a complex containing the poor metal atom and an aryl ligand with a carboxylic acid having the structure of the carboxylate ligand A in a solution, and further adding an alcohol to cause the reaction.

13. A photosensitive composition comprising the poor metal cluster compound according to any one of claims 1 to 9.

14. The photosensitive composition of claim 13, further comprising a solvent.

15. The photosensitive composition according to claim 13, wherein the poor metal cluster compound accounts for 50% by mass or more of the total solids of the components excluding the solvent.

16. The photosensitive composition according to claim 13, which reacts with actinic radiation having a wavelength of 6 nm to 15 nm.

17. A pattern forming method comprising the steps of applying the photosensitive composition according to claim 13 to a substrate, exposing the applied photosensitive composition to actinic radiation, and developing the exposed photosensitive composition.

18. The pattern formation method according to claim 17, wherein a developer is used in the developing step, and the organic solvent contained in the developer is an organic solvent having a solubility parameter (SP value) of 7.5 to 11.

19. A substrate having a patterned layer obtained by the patterning method according to claim 17.

20. A method for manufacturing a substrate, in which a pattern layer is formed by the pattern forming method according to claim 17.

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