JP2024068697A - Organometallic compounds, photosensitive materials for photoresists, and photoresists - Google Patents

Abstract

To provide an organometallic compound suitable for resist materials that enable the formation of a resist film with high-resolution patterns and superior etching resistance through exposure to ultrashort-wavelength light.SOLUTION: An organometallic compound includes a metal or metal oxide (1), and a ligand (2) bound to the (1). The (2) includes a ligand represented by the formula (2) (where L is a single bond or a linking group, and X- is a monovalent counter anion. A carbon atom constituting a benzene ring may be combined with a substituent. If two or more substituents are combined with one benzene ring, the two or more substituents may be linked to each other, forming a ring together with a carbon atom with which the substituents are combined).SELECTED DRAWING: None

Description

The present invention relates to a novel organometallic compound, a photosensitive material for photoresist containing the organometallic compound, and a photoresist containing the organometallic compound.

In the manufacture of semiconductor devices, a method is used in which a patterned resist film is formed using a photoresist (chemically amplified photoresist) that contains a photosensitive resin and a photoacid generator and has the property of changing its solubility in an alkaline developer upon exposure to light, and the resulting resist film is then used to etch a substrate (e.g., dry etching using reactive gas or plasma). As patterns become finer, the exposure wavelength is becoming shorter.

Patent Document 1 describes that when a positive resist resin containing triphenylsulfonium trifluoromethanesulfonate, a photoacid generator, and a photosensitive resin is irradiated with KrF excimer laser light (wavelength 248 nm), a fine pattern can be formed with high precision.

JP 2003-177541 A

In recent years, there has been a demand for finer patterns to accommodate the trend toward smaller, higher capacity, and higher performance electronic devices. As a result, the use of light with ultra-short wavelengths, such as extreme ultraviolet (EUV; wavelength 13.5 nm), as exposure light is being considered.

However, ultrashort wavelength light is easily absorbed by photoresist, and if the resist film is thick, the light has difficulty reaching the bottom of the film, making it difficult to form patterns with good precision. Furthermore, while reducing the thickness of the resist film can improve pattern precision, there is the problem of reduced etching resistance.

Therefore, an object of the present invention is to provide an organometallic compound suitable for a resist material that forms a resist film having a high-resolution pattern and excellent etching resistance by exposure to light with an ultrashort wavelength.
Another object of the present invention is to provide a resist material which, when exposed to light with an ultrashort wavelength, forms a resist film having a high-resolution pattern and excellent etching resistance.Another object of the present invention is to provide a resist which, when exposed to light with an ultrashort wavelength, forms a resist film having a high-resolution pattern and excellent etching resistance.

As a result of intensive research conducted by the present inventors to solve the above problems, they have found that an organometallic compound in which a ligand represented by the following formula (2) is bonded to a metal or metal oxide (1) has a photoresponsive property in which, when irradiated with light, it quickly aggregates to form an aggregate (or agglomerate), even if the irradiated light is of an ultrashort wavelength. The present invention was completed based on this finding.

（式中、Ｌは単結合又は連結基を示し、Ｘ^-は１価の対アニオンを示す。ベンゼン環を構成する炭素原子には置換基が結合していても良い。１つのベンゼン環に２個以上の置換基が結合する場合、２個以上の置換基は互いに連結して、置換基が結合する炭素原子と共に環を形成していても良い） That is, it comprises a metal or metal oxide (1) and a ligand (2) bonded to said (1),
The present invention provides an organometallic compound, wherein the (2) contains a ligand represented by the following formula (2):

(In the formula, L represents a single bond or a linking group, and ^X- represents a monovalent counter anion. A substituent may be bonded to a carbon atom constituting a benzene ring. When two or more substituents are bonded to one benzene ring, the two or more substituents may be bonded to each other to form a ring together with the carbon atom to which the substituent is bonded.)

（式中、Ｒ¹¹、Ｒ¹²はそれぞれ独立にハロゲン原子又はＣ_1-5ハロアルキル基を示す。Ｒ¹³はハロゲン原子、Ｃ_1-5アルキル基、Ｃ_1-5アルコキシ基、Ｃ_1-5ハロアルキル基、又はＣ_1-5ハロアルコキシ基を示す。ｎ１１、ｎ１２はそれぞれ独立に１～５の整数を示し、ｎ１３は０～４の整数を示す。Ｌは単結合又は連結基を示し、Ｘ^-は１価の対アニオンを示す） The present invention also provides the above organometallic compound, wherein the ligand represented by formula (2) is a ligand represented by the following formula (2-1):

(In the formula, R ¹¹ and R ¹² each independently represent a halogen atom or a C _1-5 haloalkyl group. R ¹³ represents a halogen atom, a C _1-5 alkyl group, a C _1-5 alkoxy group, a C _1-5 haloalkyl group, or a C _1-5 haloalkoxy group. n11 and n12 each independently represent an integer of 1 to 5, and n13 represents an integer of 0 to 4. L represents a single bond or a linking group, and X ⁻ represents a monovalent counter anion.)

（式中、Ｒ¹¹、Ｒ¹²はそれぞれ独立にハロゲン原子又はＣ_1-5ハロアルキル基を示す。Ｒ¹³はハロゲン原子、Ｃ_1-5アルキル基、Ｃ_1-5アルコキシ基、Ｃ_1-5ハロアルキル基、又はＣ_1-5ハロアルコキシ基を示す。ｎ１１、ｎ１２はそれぞれ独立に１～５の整数を示し、ｎ１３は０～４の整数を示す。Ｌ¹は酸素原子又は硫黄原子を示し、ｎは１～５の整数を示す。Ｘ^-は１価の対アニオンを示す） The present invention also provides the above organometallic compound, wherein the ligand represented by formula (2) is a ligand represented by the following formula (2-3):

(In the formula, R ¹¹ and R ¹² each independently represent a halogen atom or a C _1-5 haloalkyl group. R ¹³ represents a halogen atom, a C _1-5 alkyl group, a C _1-5 alkoxy group, a C _1-5 haloalkyl group, or a C _1-5 haloalkoxy group. n11 and n12 each independently represent an integer of 1 to 5, and n13 represents an integer of 0 to 4. L ¹ represents an oxygen atom or a sulfur atom, and n represents an integer of 1 to 5. ^{X -} represents a monovalent counter anion.)

The present invention also provides the organometallic compound, in which (1) is at least one selected from hafnium, zirconium, tin, cobalt, palladium, antimony, and oxides thereof.

The present invention also provides a photosensitive material for photoresist containing the organometallic compound.

The present invention also provides the photoresist photosensitive material, which is a photosensitive material for extreme ultraviolet rays or a photosensitive material for electron beams.

The present invention also provides a photoresist containing the organometallic compound and a solvent.

The organometallic compound of the present invention is an organic-inorganic composite having a structure in which a ligand (2) is coordinated to a metal or metal oxide (1), and exhibits good solubility in a solvent. The organometallic compound has excellent photoresponsiveness, and when irradiated with light, it efficiently senses even light of an ultrashort wavelength and forms an aggregate. The aggregate of the organometallic compound no longer exhibits solubility in a solvent. Furthermore, since the aggregate has a structure in which a metal or metal oxide (1) is aggregated, it has a toughness that can withstand etching.
Therefore, if a layer containing the organometallic compound in a highly dispersed state and thinned to a thickness that allows the ultrashort wavelength light to reach the bottom is exposed to ultrashort wavelength light in a pattern shape and then washed with a solvent, the organometallic compound in the unexposed areas will be washed away, but the organometallic compound in the exposed areas will remain as aggregates without being washed away, making it possible to accurately produce a resist film having a high-resolution fine pattern. Furthermore, the resist film obtained in this manner has etching resistance even though it is thin.
By subjecting a substrate to an etching process (e.g., dry etching using a reactive gas or plasma) using the resist film produced by the above-mentioned method, semiconductor devices having high-resolution patterns (e.g., wiring patterns, circuit patterns, etc.) can be produced with good yield.

[Organometallic Compounds]
The organometallic compound of the present invention is an assembly (=organic-inorganic composite) of a metal or metal oxide (1) and a ligand (2). In the organometallic compound, the ligand (2) is contained in a state of being bonded to the metal or metal oxide (1).

The organometallic compound may contain components other than the metal or metal oxide (1) and the ligand (2), but the proportion of the total weight of the metal or metal oxide (1) and the ligand (2) in the total amount of the organometallic compound (100% by weight) is, for example, 60% by weight or more, preferably 70% by weight or more, more preferably 80% by weight or more, particularly preferably 90% by weight or more, most preferably 95% by weight or more, and particularly preferably 99% by weight or more. The upper limit is 100% by weight.

The organometallic compound has excellent solubility (or dispersibility) in a solvent, and the average particle size (particle size determined by dynamic light scattering) in the solvent (e.g., PGMEA) is, for example, 200 nm or less, preferably 100 nm or less, and particularly preferably 50 nm or less. The lower limit is, for example, 1 nm.

The organometallic compound has excellent sensitivity to light rays, and when irradiated with light rays, it generates acid (HX) and rapidly aggregates. The wavelength of the light rays is, for example, 100 nm or less (e.g., 0 to 100 nm), preferably 80 nm or less, particularly preferably 50 nm or less, most preferably 30 nm or less, and particularly preferably 20 nm or less. Examples of the light rays include X-rays, electron beams (EB), EUV, etc.

(Metal or Metal Oxide (1))
The metal or metal oxide (1) is a component that forms the core of the organometallic compound, and includes at least one selected from metals and metal oxides.

Examples of the metals include hafnium, zirconium, tin, cobalt, palladium, antimony, titanium, and aluminum.

The metal oxide includes oxides of the metals and their partial hydroxides (or hydrates). Examples of the metal oxide include hafnium oxide ( _HfO2 ), zirconium oxide ( _ZrO2 , _Zr6O4 (OH) ₄ ), tin oxide ( _SnO2 , _{Sn2O3, Sn3O4, Sn6O12, Sn12O25H16 , ( C4H9Sn ) 12O14 (} OH) ₆ ), _cobalt oxide ₍ CoO _{, Co2O3 , Co3O4 )} , palladium oxide ( _PdO ), antimony oxide ( _{Sb2O3 )} , titanium oxide ( _{TiO2 ) , and aluminum oxide (Al2O3 )} .

The metal oxide can be produced, for example, by the sol-gel method. In detail, a metal alkoxide is used as the starting material, and the metal oxide is finally obtained through hydrolysis and polycondensation reactions via a sol/gel state.

The shape of the metal or metal oxide (1) is not particularly limited, and examples thereof include a spherical shape (such as a true sphere, an almost true sphere, or an elliptical sphere), a polyhedral shape, a rod shape (such as a cylindrical shape or a prismatic shape), a flat plate shape, a scale shape, and an irregular shape. The metal or metal oxide (1) may be hollow, porous, or solid.

The average particle size of the metal or metal oxide (1) (particle size determined by dynamic light scattering) is, for example, 1 to 200 nm, preferably 2 to 100 nm, and particularly preferably 2 to 50 nm.

The proportion of the metal or metal oxide (1) in the total amount of the organometallic compound (or the combined weight of the metal or metal oxide (1) and the ligand (2)) is, for example, 10 to 90% by weight, preferably 30 to 70% by weight.

（式中、Ｌは単結合又は連結基を示し、Ｘ^-は１価の対アニオンを示す。ベンゼン環を構成する炭素原子には置換基が結合していても良い。１つのベンゼン環に２個以上の置換基が結合する場合、２個以上の置換基は互いに連結して、置換基が結合する炭素原子と共に環を形成していても良い） (Ligand (2))
The ligand (2) is a compound that forms a coordinate bond with the metal or metal oxide (1). The ligand (2) includes at least a ligand represented by the following formula (2).

(In the formula, L represents a single bond or a linking group, and ^X- represents a monovalent counter anion. A substituent may be bonded to a carbon atom constituting a benzene ring. When two or more substituents are bonded to one benzene ring, the two or more substituents may be bonded to each other to form a ring together with the carbon atom to which the substituent is bonded.)

The L represents a single bond or a linking group. The linking group is a divalent group having one or more atoms, such as a divalent hydrocarbon group, a carbonyl group (-CO-), an ether bond (-O-), a thioether bond (-S-), an ester bond (-COO-, -OCO-), an amide bond (-CONH-), a carbonate bond (-OCOO-), and groups in which multiple of these are linked together.

Examples of the divalent hydrocarbon group include linear or branched alkylene groups having 1 to 5 carbon atoms, such as methylene, methylmethylene, dimethylmethylene, ethylene, propylene, and trimethylene; cycloalkylene groups having 3 to 18 carbon atoms, such as 1,2-cyclopentylene, 1,3-cyclopentylene, cyclopentylidene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, and cyclohexylidene; and arylene groups having 6 to 14 carbon atoms, such as o-phenylene, m-phenylene, p-phenylene, and naphthylene.

As the L, a divalent group in which an ether bond (-O-) or a thioether bond (-S-) is bonded to a divalent hydrocarbon group is preferred, and a divalent group in which an ether bond (-O-) or a thioether bond (-S-) is bonded to a linear or branched alkylene group having 1 to 5 carbon atoms [C _n H _2n ; n = an integer from 1 to 5] is particularly preferred.

Therefore, the L is preferably a divalent group represented by the formula [-L ¹ -C _n H _2n -]. In the formula, L ¹ represents an oxygen atom or a sulfur atom, and n represents an integer of 1 to 5. The bond on the left side of L ¹ bonds to the benzene ring represented by C in formula (2). In addition, the bond on the right side of the formula (i.e., the right side of the alkylene group) bonds to the carboxy carbon in formula (2).

The benzene rings represented by A, B, and C in formula (2) may each have a substituent bonded to one or more of the carbon atoms constituting the ring. Examples of the substituent include a halogen atom, a hydrocarbon group, a halogenated hydrocarbon group, and a group represented by the following formula (r).
^-X1 -R(r)
(In formula (r), ^X1 represents -O-, -S-, or -CO-, and R represents a hydrocarbon group or a halogenated hydrocarbon group. The bond coming out from the left end of formula (r) bonds to a carbon atom constituting a benzene ring in formula (2-1).)

The halogen atom is preferably a fluorine atom or an iodine atom, and more preferably a fluorine atom.

The hydrocarbon group includes an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, and a group in which two or more of these are bonded via a single bond.

The aliphatic hydrocarbon group is preferably an aliphatic hydrocarbon group having 1 to 5 carbon atoms (=C _1-5 ), and examples thereof include alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, s-butyl group, t-butyl group, and pentyl group; and alkenyl groups such as vinyl group, allyl group, and 1-butenyl group.

The alicyclic hydrocarbon group is preferably a _C3-10 alicyclic hydrocarbon group, and examples thereof include cycloalkyl groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group; cycloalkenyl groups such as a cyclopentenyl group and a cyclohexenyl group; and bridged cyclic hydrocarbon groups such as a perhydronaphthalene-1-yl group, a norbornyl group, an adamantyl group, a tricyclo[ ^5.2.1.02,6 ]decan-8-yl group, and a ^tetracyclo [ ^{4.4.0.12,5.17,10} ]dodecan-3-yl group.

The aromatic hydrocarbon group is preferably a C _6-14 (particularly, a C _6-10 ) aromatic hydrocarbon group, and examples thereof include aryl groups such as a phenyl group and a naphthyl group.

The halogenated hydrocarbon group includes a group in which at least one of the hydrogen atoms of the hydrocarbon group is replaced with a halogen atom (e.g., a fluorine atom and/or an iodine atom).

The group represented by formula (r) includes, for example, an acyl group, a halogenated acyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, and the like.

When two or more substituents are bonded to the benzene ring represented by A, B, or C in formula (2), the two or more substituents may be linked to each other to form a ring (e.g., a condensed ring such as a naphthalene ring) together with the carbon atom to which the substituents are bonded (= the carbon atom constituting the benzene ring).

The benzene ring in formula (2) (particularly the benzene ring represented by A and B in formula (2)) preferably has a substituent in terms of improving photosensitivity to ultrashort wavelength light, and among these, it is preferable for it to have at least one substituent selected from a halogen atom, a _C1-5 alkyl group, a _C1-5 alkoxy group, a _C1-5 haloalkyl group, and a _C1-5 haloalkoxy group, and it is particularly preferable for it to have at least one substituent selected from a halogen atom, a _C1-5 haloalkyl group, and a _C1-5 haloalkoxy group, and it is especially preferable for it to have at least one substituent selected from a halogen atom and a _C1-5 haloalkyl group.

The benzene ring represented by C in formula (2) preferably has a substituent, in order to improve the photosensitivity to ultrashort wavelength light, and among these, it is preferable for it to have at least one substituent selected from a halogen atom, a _C1-5 alkyl group, a _C1-5 alkoxy group, a _C1-5 haloalkyl group, and a _C1-5 haloalkoxy group, and it is particularly preferable for it to have at least one substituent selected from a _C1-5 alkyl group and a _C1-5 alkoxy group, and it is particularly preferable for it to have a _C1-5 alkyl group as a substituent.

As the ligand represented by the formula (2), from the viewpoint of improving the photosensitivity to light of an ultrashort wavelength, a ligand represented by the following formula (2-1), a ligand represented by the following formula (2-1'), or a ligand represented by the following formula (2-1") is preferred, and a ligand represented by the following formula (2-1) is particularly preferred.

In the above formula, R ¹¹ and R ¹² are, for example, a group selected from a halogen atom, a C _1-5 alkyl group, a C _1-5 alkoxy group, a C _1-5 haloalkyl group, and a C _1-5 haloalkoxy group, particularly preferably a group selected from a halogen atom, a C _1-5 haloalkyl group, and a C _1-5 haloalkoxy group, and particularly preferably a group selected from a halogen atom and a C _1-5 haloalkyl group.

In the above formula, R ¹³ is, for example, a group selected from a halogen atom, a C _1-5 alkyl group, a C _1-5 alkoxy group, a C _1-5 haloalkyl group, and a C _1-5 haloalkoxy group, particularly preferably a group selected from a C _1-5 alkyl group and a C _1-5 alkoxy group, and especially preferably a C _1-5 alkyl group.

In the above formula, n11 and n12 each independently represent an integer of 1 to 5, preferably an integer of 1 to 3, particularly preferably 1 or 2, and most preferably 2. n13 represents an integer of 0 to 4, preferably an integer of 1 to 4, particularly preferably 1 or 2, and most preferably 2.

In the above formula, there is no particular limitation on the bonding positions of the groups represented by R ¹¹ and R ¹² to the benzene ring.

In the above formula, the bonding position of the group represented by R ¹³ to the benzene ring is not particularly limited, but the meta position to the position to which the sulfur atom in the above formula is bonded is preferred.

In the above formula, the bonding position of the group represented by [-L-COO ^- ] to the benzene ring is preferably the para position relative to the bonding position of the sulfur atom represented in the above formula.

In the above formula, L is the same as above.

As the ligand represented by the formula (2), a ligand represented by the following formula (2-2) is preferable in terms of improving the photosensitivity to light rays of ultrashort wavelengths.

In the above formula, L ¹ represents an oxygen atom or a sulfur atom, and n represents an integer of 1 to 5. X ⁻ represents a monovalent counter anion.

In the above formula, a substituent may be bonded to the carbon atom constituting the benzene ring. When two or more substituents are bonded to one benzene ring, the two or more substituents may be linked to each other to form a ring together with the carbon atom to which the substituent is bonded. Examples of the substituent and the ring that may be formed are the same as those of the substituent that the ligand represented by formula (2) above may have and the ring that may be formed.

From the above, as the ligand represented by formula (2), the ligand represented by the following formula (2-3) is particularly preferable in terms of improving the photosensitivity to ultrashort wavelength light: In the following formula, R ¹¹ , R ¹² , R ¹³ , n11, n12, n13, L ¹ , n and X ⁻ are the same as above.

In the above formula, X ⁻ represents a monovalent counter anion, examples of which include a halogen ion, a halogen oxo acid anion, a boron anion, a phosphate anion, a sulfate anion, a sulfonate anion, a sulfonylimide anion, a carboxylate anion, a methide anion, an antimony anion, OH ⁻ , SCN ⁻ , NO ₂ ⁻ , NO ₃ ⁻ , and the like.

Examples of the halogen ion include Cl ⁻ , Br ⁻ , and I ⁻ .

Examples of the halogen oxo acid anion include ClO ₄ ⁻ , IO ₃ ⁻ , and BrO ₃ ⁻ .

Examples of _the boron _anion include inorganic boron anions such as _Br3- and _BF4- ^{, and} organic boron anions such as ( _C6F5 ) _4B- , (( _CF3 ) _2C6H3 ) ^{4B- ,} tetraphenylborate, tetrakis _{( monofluorophenyl} )borate, tetrakis(difluorophenyl)borate, and tetrakis(trifluorophenyl)borate.

_{Examples of} the phosphate anion include inorganic phosphate anions such as _PF6- ^, PF( _{C2F5 ) 5-} ^, _{PF2 ( C2F5 ) 4-} , _{PF3 ( C2F5} ) _3- ^, PF4( _C2F5 ^{) 2-} , _PF5 ⁽ _C2F5 ) ^- , and _{PO43- .}

The sulfonate anion is represented, for example, by the following formula (s1).
R ^s1 -SO ₃ ^- (s1)
(In the formula, R represents ^an organic group.)

Examples of the organic group in R ^s1 include a C _1-30 hydrocarbon group which may have a substituent, a heterocyclic group which may have a substituent, and a group in which two or more of the above groups are linked by a single bond or a linking group selected from -O-, -CO ₂ -, -S-, -SO ₃ -, and -SO ₂ N(R ^s2 )-. R ^s2 represents a hydrogen atom or an alkyl group (for example, a C _1-30 alkyl group). Examples of the substituent include a halogen atom such as a fluorine atom.

The C _1-30 hydrocarbon group includes a C _1-30 aliphatic hydrocarbon group, a C _3-30 alicyclic hydrocarbon group, a C _6-30 aromatic hydrocarbon group, and a group in which two of these are combined.

The C _1-30 hydrocarbon group is preferably a C _1-30 alkyl group, a C _6-15 aryl group, a C _6-15 cycloalkylene group, a C _6-15 bridged cyclic hydrocarbon group, or a group in which two of these are bonded together.

The heterocyclic group is a group in which one hydrogen atom has been removed from the structural formula of a heterocycle. The heterocycle includes aromatic heterocycles and non-aromatic heterocycles. Examples of such heterocycles include 3- to 10-membered rings (preferably 4- to 6-membered rings) whose ring-constituting atoms include carbon atoms and at least one heteroatom (e.g., oxygen atom, sulfur atom, nitrogen atom, etc.), and condensed rings thereof.

Specific examples of the sulfonate anion include CH ₃ SO ₃ ⁻ , C ₄ H ₉ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , C ₂ F ₅ C ₄ H ₄ SO ₃ ⁻ , C ₄ F ₉ SO ₃ ⁻ , benzenesulfonate anion, p-toluenesulfonate anion, and camphorsulfonate anion.

The sulfonylimide anion is represented, for example, by the following formula (n1).
(R ⁿ¹ SO ₂ ) ₂ N ^- (n1)
(In the formula, two R ⁿ¹ each independently represent an organic group.)

Examples of the organic group in R ⁿ¹ include the same organic groups as those in R ^s1 .

Specific examples of the sulfonylimide anion include (FSO ₂ ) ₂ N ^- , (CF ₃ SO ₂ ) ₂ N ^- , (C ₄ F ₉ SO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^{- ,} and the like.

The carboxylate anion is represented, for example, by the following formula (c1).
R ^c1 -COO ^- (c1)
(In the formula, ^R represents an organic group.)

Examples of the organic group in R ^c1 include the same organic groups as those in R ^s1 .

Specific examples of the carboxylate anion include CF ₃ CO ₂ ⁻ , CH ₃ CO ₂ ⁻ , C ₂ H ₅ CO ₂ ⁻ , and PhCO ₂ ⁻ .

Examples of the methide anion include a sulfonylmethide anion represented by the following formula (m1).
( ^Rm1SO2 _{) 3C-} ( ^m1 )
(In the formula, each of the three R ^m1s independently represents an organic group.)

Examples of the organic group in R ^m1 include the same organic groups as those in R ^s1 .

Specific examples of the methide anion include (CF ₃ SO ₂ ) ₃ C ^— .

The antimony anion may, for example, be SbF ₆ ⁻ .

In addition to the above, the monovalent counter anion includes, for example, the anions described in JP-A-2013-47211, JP-A-2021-81708, JP-A-2013-80245, JP-A-2013-80240, and JP-A-2013-33161.

As the counter anion, a sulfonate anion or a sulfonylimide anion is preferred because of their excellent solvent solubility and fine pattern forming properties.

The organometallic compound may contain, as the ligand (2), other ligands in addition to the ligand represented by the above formula (2). In other words, the metal or metal oxide (1) may be coordinately bonded with one or more other ligands in addition to the ligand represented by the above formula (2).

Other ligands include, for example, carboxylates, phosphates, phosphonates, and sulfonates.

Examples of the coordinating compound that forms the carboxylate include C 1-10 alkyl carboxylic acids such as citric acid, oxalic acid, malic acid, maleic acid, tartaric acid, glutaric acid, adipic acid, pimelic acid, succinic acid, malonic acid, fumaric acid, phthalic acid, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, glycolic acid, glyceric acid, and lactic acid; C _2-10 alkenyl carboxylic acids such as acrylic acid, methacrylic acid _{, tiglic acid, 2-methylisocrotonic acid, and 3-methylcrotonic acid; and C 6-10 aryl} carboxylic acids such as benzoic acid, salicylic acid, and crotonic acid.

Examples of the coordinating compound that forms the phosphate include C1-10 alkyl phosphates such as methyl phosphate, ethyl phosphate, propyl phosphate, butyl phosphate, hexyl phosphate, phenyl phosphate _{, dimethyl phosphate, diethyl phosphate, dipropyl phosphate, dibutyl phosphate, and dihexyl phosphate; and C6-10 aryl} phosphates such as diphenyl phosphate.

Examples of the coordinating compound that forms the phosphonate include _C1-10 alkylphosphonic acids such as methylphosphonic acid, ethylphosphonic acid, propylphosphonic acid, butylphosphonic acid, and hexylphosphonic acid; _C2-10 alkenylphosphonic acids such as vinylphosphonic acid; and _C6-10 arylphosphonic acids such as phenylphosphonic acid.

Examples of the coordinating compound that forms the sulfonate include _C1-10 alkylsulfonic acids such as methylsulfonic acid, ethylsulfonic acid, propylsulfonic acid, butylsulfonic acid, and hexylsulfonic acid; _C6-10 arylsulfonic acids such as phenylsulfonic acid; and _C2-10 alkenylsulfonic acids such as vinylsulfonic acid.

As the other ligand, from the viewpoint of imparting good dispersibility to the organometallic compound, a ligand having a _C6-10 aryl group (for example, a carboxylate, a phosphate, a phosphonate, or a sulfonate) is preferable, and a _C6-10 arylcarboxylate is particularly preferable.

When the ligand (2) contains other ligands in addition to the ligand represented by the above formula (2), the proportion of the ligand represented by the above formula (2) in the total amount of the ligands is, for example, 0.1% by weight or more, preferably 0.5% by weight or more, and particularly preferably 1.0% by weight or more. The upper limit is, for example, 50% by weight, preferably 30% by weight.

The proportion of the ligand represented by the above formula (2) in the total amount of the organometallic compound (or the total weight of the metal or metal oxide (1) and the ligand (2)) is, for example, 0.1 to 50% by weight, preferably 0.5 to 30% by weight.

The content of the ligand represented by the above formula (2) is, for example, 0.1 to 50 parts by weight, preferably 0.5 to 30 parts by weight, and particularly preferably 1 to 20 parts by weight, per 100 parts by weight of the metal or metal oxide (1).

The organometallic compound aggregates when irradiated with light. The mechanism of this aggregation is thought to be the reaction shown in the following formula:
That is, the metal or metal oxide (1) is a fine particle and has a tendency to aggregate, but the ligand represented by formula (2) is bonded to the surface of the metal or metal oxide (1) in the organometallic compound, suppressing aggregation between the metal or metal oxide (1) and acquiring dispersibility. When irradiated with light, it is considered that the number of bonded ligands decreases through the following reactions 1, 2, and 3, causing the dispersibility to be lost and forming aggregates.
1. A part of the ligand represented by formula (2) decomposes to generate an acid (HX).
2. The generated acid (HX) reacts with the metal oxide (1) and releases the ligands bound to the surface.
3. The number of ligands bonded to the surface of the metal or metal oxide (1) decreases, resulting in loss of dispersibility.

In the following formula, M represents a metal or metal oxide (1). L and X are the same as L and X in formula (2). In addition, a substituent may be bonded to the carbon atom constituting the benzene ring in the following formula. R in the following formula represents the portion other than the carboxy group of the ligand represented by formula (2) above (i.e., the portion surrounded by the dashed line in the following formula).

[Method of producing organometallic compounds]
The organometallic compound can be produced, for example, by mixing a metal or metal oxide (1) with a compound represented by the following formula (2a) that exhibits coordination with (1) (hereinafter, sometimes referred to as "metal coordination compound (2a)") in a solvent.

The compound represented by the following formula (3) is an example of the organometallic compound, and is a schematic diagram showing how a ligand derived from a metal coordination compound (2a) is bonded to a metal or metal oxide (1) to form an organic-inorganic composite.
In the following formula, M represents a metal or metal oxide (1).
X ⁻ and L in the following formula (2a) are the same as X ⁻ and L in formula (2). In addition, the benzene ring in the following formula (2a) may have a substituent, similar to the benzene ring in formula (2).
In the following formula (3), R represents the portion other than the carboxy group of the compound represented by the following formula (2a) (i.e., the portion surrounded by the dashed line).

The amount of the metal coordination compound (2a) used is, for example, 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, per part by weight of the metal or metal oxide (1).

Examples of the solvent include ethers such as diethyl ether, diisopropyl ether, dibutyl ether, tetrahydrofuran, dioxane, 1,2-dimethoxyethane, and cyclopentyl methyl ether. These can be used alone or in combination of two or more.

The amount of the solvent used is, for example, about 50 to 300% by weight based on the total amount of the metal or metal oxide (1) and the ligand (2).

After the reaction is complete, the resulting reaction product can be separated and purified by standard methods such as precipitation, washing, and filtration.

An example of a method for producing the metal coordination compound (2a) is shown below. Through the following steps [I], [II] and [III], a compound represented by the above formula (2a-1) (a compound represented by the above formula (2a) in which L is [—O—C _n H _2n ; n = an integer of 1 to 5]) is obtained.

(Step I)
Step I is a step of reacting a compound represented by formula (11) (=compound (11)) with a compound represented by formula (12) (=compound (12)) to obtain a compound represented by formula (13) (=compound (13)).

The molar ratio of compound (11) to compound (12) (compound (11)/compound (12)) to be reacted is, for example, 1/50 to 3/1, preferably 1/10 to 2/1.

The reaction is preferably carried out in the presence of a dehydrating agent (HX'). Examples of the dehydrating agent (HX') include concentrated sulfuric acid, phosphoric anhydride, methanesulfonic acid, trifluoromethanesulfonic acid, and their anhydrides. These can be used alone or in combination of two or more.

(Step II)
Step II is a step of reacting compound (13) obtained through step I with M ¹ X (X represents a monovalent counter anion, and M ¹ represents an alkali metal) to obtain a compound represented by formula (14) (=compound (14)).

The molar ratio of compound (13) to M ¹ X (compound (13)/M ¹ X) to be reacted is, for example, 1/3 to 3/1, preferably 1/2 to 2/1.

(Step III)
Step III is a step of reacting compound (14) obtained via step II with a compound represented by formula (15) (=compound (15)) to obtain a compound represented by formula (2a-1).

In the formula (15), X ¹ represents a halogen atom, and X ² represents a hydrogen atom or a protecting group (for example, a t-butyl group, etc.) Compound (15) acts as an alkylating agent.

The molar ratio of compound (14) to compound (15) (compound (14)/compound (15)) to be reacted is, for example, 1/3 to 3/1, preferably 1/2 to 2/1.

The reaction can be carried out in the presence of a solvent. Examples of the solvent include acetone, acetonitrile, and dimethyl sulfoxide. These can be used alone or in combination of two or more.

The reaction atmosphere in each step is not particularly limited as long as it does not inhibit the reaction, and may be, for example, an air atmosphere, a nitrogen atmosphere, an argon atmosphere, etc. Furthermore, the reaction may be carried out in any method, such as a batch method, a semi-batch method, or a continuous method.

After the reaction in each step is completed, the reaction product obtained may be subjected to a general separation and purification process (e.g., precipitation, washing, filtration, etc.).

[Photoresist photosensitive material]
The photosensitive material for photoresist is a photosensitive material used in the field of photolithography (for example, a compound whose solubility in a solvent changes upon exposure to light), and includes the above-mentioned organometallic compounds.

The photoresist photosensitive material may contain other components (e.g., ligands other than the ligand represented by formula (2)) in addition to the organometallic compound described above, but the proportion of the organometallic compound in the total amount of the photoresist photosensitive material is, for example, 70% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more, particularly preferably 95% by weight or more, most preferably 99% by weight or more, and particularly preferably 99.9% by weight or more. The upper limit is 100% by weight.

The photoresist photosensitive material has excellent solubility (or dispersibility) in a solvent (e.g., PGMEA, etc.). The average particle size of the photoresist photosensitive material in a solvent (particle size determined by dynamic light scattering) is, for example, 200 nm or less, preferably 100 nm or less, and particularly preferably 50 nm or less. The lower limit is, for example, 1 nm.

The photoresist photosensitive material has excellent sensitivity to light rays with ultra-short wavelengths, and when irradiated with the light rays, it quickly forms aggregates. The wavelength of the light rays is, for example, 100 nm or less, preferably 80 nm or less, and particularly preferably 50 nm or less. The light rays include, for example, X-rays, electron beams (EB), EUV, etc.

The photoresist photosensitive material has thermal stability, and aggregation is suppressed even when it is subjected to a heat treatment (for example, heating at a temperature of 50°C or higher and lower than 130°C for 1 to 5 minutes). Therefore, a coating film containing the photoresist photosensitive material can be heated and dried while suppressing aggregation, and it has excellent workability.

Since the photoresist photosensitive material has the above-mentioned characteristics, it can be suitably used as a negative photoresist photosensitive material. It can also be suitably used as a photosensitive material for photoresists that use ultrashort wavelength light such as extreme ultraviolet rays and electron beams.

[Photoresist]
The photoresist of the present invention is a resist for forming a patterned resist film used in the field of photolithography, and contains the above-mentioned organometallic compound and solvent, with the organometallic compound being contained in a dissolved (or highly dispersed) state in the solvent.

In the photoresist, the organometallic compound is contained in a stably dissolved (or highly dispersed) state. The average particle size of the organometallic compound in the photoresist (particle size determined by dynamic light scattering) is, for example, 200 nm or less, preferably 100 nm or less, and particularly preferably 50 nm or less. The lower limit is, for example, 1 nm. Therefore, by using the photoresist, a resist film having a low LER and a high-resolution fine pattern can be obtained.

Examples of the solvent include lactones such as γ-butyrolactone; ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl n-pentyl ketone, methyl isopentyl ketone, and 2-heptanone; polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol; (poly)C _1-5 alkylene glycol esters such as ethylene glycol monoacetate, diethylene glycol monoacetate, diethylene glycol diacetate, propylene glycol monoacetate, propylene glycol diacetate, and dipropylene glycol monoacetate; (poly)C alkylene glycol esters such as ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol n-propyl ether, propylene glycol phenyl ether, and tripropylene glycol methyl n-propyl ether. Examples of such esters include _1-5 alkylene glycol ethers, (poly)C _1-5 alkylene glycol ether esters such as ethylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, and propylene glycol monomethyl ether acetate (PGMEA), cyclic ethers such as dioxane, esters such as methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, and ethyl ethoxypropionate, aromatic hydrocarbons such as anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, dibenzyl ether, phenetole, butyl phenyl ether, ethylbenzene, diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymene, and mesitylene, and dimethyl sulfoxide. These esters may be used alone or in combination of two or more.

The content of the organometallic compound is, for example, 0.5 to 50% by weight, preferably 1.0 to 30% by weight, of the total amount of the photoresist (100% by weight).

The content of the solvent is, for example, 50 to 99.5% by weight, preferably 70 to 99% by weight, of the total amount of the photoresist (100% by weight).

The photoresist may contain other components in addition to the organometallic compound and the solvent, such as a bearing agent and a quencher.

In the total amount of the photoresist (100% by weight), the ratio of the total weight of the organometallic compound and the solvent is, for example, 60% by weight or more, preferably 70% by weight or more, more preferably 80% by weight or more, particularly preferably 90% by weight or more, most preferably 95% by weight or more, and particularly preferably 99% by weight or more. The upper limit is 100% by weight.

The photoresist contains at least the organometallic compound as a non-volatile content. The content of the organometallic compound in the total amount of the non-volatile content (100% by weight) is, for example, 60% by weight or more, preferably 70% by weight or more, more preferably 80% by weight or more, particularly preferably 90% by weight or more, most preferably 95% by weight or more, and particularly preferably 99% by weight or more. The upper limit is 100% by weight.

In this specification, the non-volatile components of the photoresist are components that contain the organometallic compound, for example, components that remain after the photoresist is heated at 100°C for 1 hour under normal pressure.

Furthermore, when the photoresist is irradiated with light (accumulated light amount, for example, 5 to 500 mJ/ ^cm2 ), the organometallic compound contained in the photoresist quickly forms aggregates. From the viewpoint of making the pattern finer, it is preferable to shorten the wavelength of the light, for example, 100 nm or less (for example, 1 to 100 nm), more preferably 80 nm or less, particularly preferably 50 nm or less, most preferably 30 nm or less, and particularly preferably 20 nm or less. Examples of the light include X-rays, electron beams (EB), EUV, etc.

Since the photoresist has the above-mentioned characteristics, it can be suitably used as a negative photoresist. It can also be suitably used as a resist for photolithography using ultrashort wavelength light such as extreme ultraviolet rays or electron beams.

By using the photoresist, for example, through steps 1 to 3 below, it is possible to form a resist film that has a highly accurate fine pattern and has excellent etching resistance.

Step 1: A step of applying the photoresist onto a substrate and drying to form an organometallic compound layer. Step 2: A step of irradiating the organometallic compound layer with light to transfer a pattern. Step 3: A step of performing development.

(Step 1)
In this step, the photoresist is applied onto the substrate to be etched, and then dried to form an organometallic compound layer. Through this step, a [substrate/organometallic compound layer] laminate is obtained.

The photoresist can be applied by known methods such as spin coating, curtain coating, roll coating, spray coating, and screen printing.

The substrate onto which the photoresist is applied may be subjected to a surface treatment as necessary. For example, an adhesion agent such as hexamethyldisilazane (HMDS) may be applied to the surface of the substrate to improve the adhesion of the resist film.

The photoresist coating may be dried naturally, but since the organometallic compound is thermally stable, it can also be dried by heating (for example, at a temperature of 50°C or higher and lower than 130°C for 1 to 5 minutes), which provides excellent workability.

The thickness of the organometallic compound layer is, for example, 1000 nm or less, preferably 100 nm or less. The lower limit of the thickness is, for example, 1 nm. The aggregates of the organometallic compound contain a metal or a metal oxide, and therefore have toughness. Therefore, even if the organometallic compound layer is thinned, a resist film with excellent etching resistance can be formed.

(Step 2)
This step is a step of transferring a pattern by irradiating the organometallic compound layer obtained through step 1 with light, for example, through a photomask having a pattern.

When irradiated with light through a patterned photomask, the organometallic compounds in the exposed areas aggregate and adhere to the substrate, while the organometallic compounds in the unexposed areas do not aggregate and maintain their solubility.

There are no particular limitations on the light used for photoirradiation, so long as it can initiate the aggregation of the organometallic compounds contained in the coating film, but it is preferable to use a light source with an ultrashort wavelength, such as EUV or an electron beam, since this allows for the transfer of extremely fine patterns with high precision.

In addition, because the organometallic compound aggregates are tough, etching resistance can be maintained even when the organometallic compound layer is thinned. By thinning the organometallic compound layer and irradiating it with ultrashort wavelength light, the light can reach the bottom of the organometallic compound layer, forming a highly accurate pattern.

(Step 3)
This step involves subjecting the substrate/organometallic compound layer laminate after light irradiation to a development process, in which the unexposed areas of the organometallic compound layer are washed away, while the exposed areas remain in close contact with the substrate.

The developer used in the development process can be an alkaline aqueous solution or an organic solvent, either alone or in combination of two or more.

Examples of the alkaline aqueous solution include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, aqueous ammonia, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene.

The organic solvent may be, for example, the same as the solvent that can be used in a photoresist. Among them, it is preferable that the organic solvent contains at least one selected from polyhydric alcohols, esters, ethers, ketones, and aromatic hydrocarbons, it is particularly preferable that the organic solvent contains at least an ester, and it is most preferable that the organic solvent contains at least butyl acetate.

Examples of the development process include a method in which the developer is applied to the substrate/organometallic compound layer laminate by dipping, showering, spraying, or other methods.

The temperature of the developer is, for example, 25 to 40°C. The development time is determined appropriately depending on the thickness of the organometallic compound layer, but is, for example, about 0.5 to 5 minutes.

Ideally, unexposed areas should be completely removed during development processing. This is because the presence of development residues can easily cause problems such as wiring shape abnormalities. The photoresist of the present invention contains an organometallic compound that has high dispersibility and thermal stability, so unexposed areas can be easily and completely removed by washing with a developer, and no development residues are produced. This allows defect-free products to be manufactured with a high yield.

Through step 3, a resist film can be formed on the substrate, which is made of aggregates of organometallic compounds, has a highly accurate fine pattern, and has excellent etching resistance. By etching the substrate using the resist film thus obtained, high-precision electronic devices can be manufactured.

The electronic devices include, for example, display devices such as organic electroluminescence displays and liquid crystal displays; input devices such as touch panels; light-emitting devices; sensor devices; and MEMS (Micro Electro Mechanical Systems) devices such as optical scanners, optical switches, acceleration sensors, pressure sensors, gyroscopes, microchannels, and inkjet heads.

The above configurations and combinations of the present invention are merely examples, and additions, omissions, substitutions, and modifications of the configurations are possible as appropriate without departing from the spirit of the present invention.

The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

Production Example 1
<Synthesis of bis(3,5-difluorophenyl)sulfoxide>
To a dispersion obtained by dispersing 13.4 g (0.55 mol) of magnesium in 400 g of tetrahydrofuran (THF), 96.5 g (0.50 mol) of 1-bromo-3,5-difluorobenzene was added dropwise while stirring, while maintaining the temperature in the system within the range of 40 to 50° C., to prepare a THF solution of 3,5-difluorophenylmagnesium bromide.
To the prepared THF solution of 3,5-difluorophenylmagnesium bromide, a solution prepared by diluting 28.6 g (0.24 mol) of thionyl chloride with 50 g of THF was added dropwise at a rate such that the temperature in the system did not exceed −5° C. After completion of the dropwise addition, the reaction was continued at room temperature for 1 hour to complete the reaction.

The solution after the reaction was added to 500 g of ion-exchanged water at a rate such that the temperature in the system did not exceed 15°C, and the mixture was stirred for 1 hour. Then, 300 g of ethyl acetate was added, and the mixture was stirred for 1 hour. After removing the aqueous layer, the mixture was washed three times with 300 g of ion-exchanged water. The organic layer was passed through a silica gel column for decolorization. Next, the organic layer after the decolorization treatment was desolvated, and recrystallized with cyclohexane to obtain 26.0 g of bis(3,5-difluorophenyl)sulfoxide.

<Synthesis of metal coordination compounds>
6.86 g (0.025 mol) of the obtained bis(3,5-difluorophenyl)sulfoxide was dissolved in 15.3 g (0.125 mol) of 2,6-dimethylphenol and 24.0 g (0.25 mol) of methanesulfonic acid, and 7.1 g (0.05 mol) of phosphoric anhydride was added dropwise at a rate such that the temperature in the system did not exceed 25°C. After the dropwise addition, the reaction was continued at room temperature for 24 hours to complete the reaction. Next, the reaction solution was slowly poured into 150 g of ion-exchanged water, stirred for a while, and then 50 g of methanol was added. 50 g of toluene was added to this solution, stirred for 30 minutes, and then allowed to stand to remove the upper toluene layer. This toluene washing was carried out two more times.

After removing the toluene layer, 4.7 g (0.025 mol) of potassium trifluoromethanesulfonate and 80 g of dichloromethane were added to the aqueous layer, and the mixture was stirred for 1 hour, then allowed to stand and the upper aqueous layer was removed. This water washing procedure was repeated two more times. After removing the aqueous layer, the dichloromethane layer was concentrated to obtain 3.1 g (0.006 mol) of a sulfonium intermediate.

Next, 10 g of acetonitrile, 1.7 g (0.009 mol) of t-butyl bromoacetate, and 2.5 g (0.018 mol) of potassium carbonate were added to this intermediate, and the reaction was carried out at 60°C for 36 hours. The reaction solution was then filtered, and the filtrate was collected. The collected filtrate was concentrated and washed with t-butyl methyl ether, and 3.5 g of insoluble matter was collected.

This insoluble portion was dissolved in 100 g of isopropanol, 1 g of sulfuric acid was added, and the mixture was allowed to react at 70°C for 5 hours, after which the solvent was removed by concentration. Next, 50 g of dichloromethane and 50 g of ion-exchanged water were added, and the mixture was stirred for 1 hour, then allowed to stand and the upper aqueous layer was removed. This water washing operation was repeated two more times. After removing the aqueous phase, the dichloromethane layer was concentrated and recrystallized with butyl acetate. This yielded 2.3 g of the target product, [bis(3,5-difluorophenyl)](4-carboxymethoxy-3,5-dimethylphenyl)sulfonium trifluoromethanesulfonate.

Production Example 2
<Synthesis of bis(2-trifluoromethylphenyl)sulfoxide>
The same method as in Production Example 1 was repeated except that 112.5 g (0.50 mol) of 2-bromobenzotrifluoride was used instead of 96.5 g of 1-bromo-3,5-difluorobenzene, to obtain 20.0 g of bis(2-trifluoromethylphenyl)sulfoxide.

<Synthesis of metal coordination compounds>
[Bis(2-trifluoromethylphenyl)](4-(1-carboxypropoxy)-3,5-dimethylphenyl)sulfonium nonafluorobutanesulfonate was obtained in the same manner as in Production Example 1, except that bis(2-trifluoromethylphenyl)sulfoxide was used instead of bis(3,5-difluorophenyl)sulfoxide, t-butyl 2-bromobutyrate was used instead of t-butyl bromoacetate, and potassium nonafluorobutanesulfonate was used instead of potassium trifluoromethanesulfonate.

Production Example 3
<Synthesis of bis(4-trifluoromethylphenyl)sulfoxide>
The same method as in Production Example 1 was repeated except that 112.5 g (0.50 mol) of 4-bromobenzotrifluoride was used instead of 96.5 g of 1-bromo-3,5-difluorobenzene, to obtain 29.1 g of bis(4-trifluoromethylphenyl)sulfoxide.

<Synthesis of metal coordination compounds>
[Bis(4-trifluoromethylphenyl)](4-carboxymethylthiophenyl)sulfonium bis(trifluoromethanesulfonyl)imide was obtained in the same manner as in Example 1, except that bis(4-trifluoromethylphenyl)sulfoxide was used instead of bis(3,5-difluorophenyl)sulfoxide, thiophenol was used instead of 2,6-dimethylphenol, and potassium bis(trifluoromethanesulfonyl)imide was used instead of potassium trifluoromethanesulfonate.

Production Example 4
<Synthesis of bis(4-iodophenyl)sulfoxide>
To a solution of 28.6 g (0.24 mol) of thionyl chloride and 100 g (0.48 mol) of iodobenzene diluted with 500 g of THF, 50 g (0.48 mol) of perchloric acid was added dropwise. After the completion of the dropwise addition, the reaction was continued at room temperature for 5 hours to complete the reaction. Next, the reaction solution was slowly poured into 1500 g of ion-exchanged water, after which 300 g of dichloromethane was added and stirred for 1 hour, and then the mixture was allowed to stand and the upper aqueous layer was removed. The dichloromethane layer after removing the aqueous phase was concentrated and recrystallized with butyl acetate to obtain 54 g of bis(4-iodophenyl)sulfoxide.

<Synthesis of metal coordination compounds>
[Bis(4-iodophenyl)](4-carboxyphenyl)sulfonium nonafluorobutanesulfonate was obtained in the same manner as in Example 1, except that bis(4-iodophenyl)sulfoxide was used instead of bis(3,5-difluorophenyl)sulfoxide, t-butyl benzoate was used instead of 2,6-dimethylphenol, potassium nonafluorobutanesulfonate was used instead of potassium trifluoromethanesulfonate, and t-butyl bromoacetate was not used.

Production Example 5
<Synthesis of bis(3,5-difluoro-2-iodophenyl)sulfoxide>
27.4 g (0.10 mol) of bis(3,5-difluorophenyl)sulfoxide was dissolved in 200 g of sulfuric acid, 45.0 g (0.20 mol) of N-iodosuccinimide was added in portions, and the mixture was allowed to react at room temperature for 3 hours. The reaction solution was then slowly added to 1500 g of ion-exchanged water, followed by the addition of 200 g of dichloromethane, and the mixture was stirred for 1 hour, and then allowed to stand to remove the upper aqueous layer. The dichloromethane layer after removing the aqueous phase was concentrated and recrystallized with butyl acetate to obtain 23.3 g of bis(3,5-difluoro-2-iodophenyl)sulfoxide.

<Synthesis of metal coordination compounds>
[Bis(3,5-difluoro-2-iodophenyl)](4-carboxymethoxy-3,5-dimethylphenyl)sulfonium bis(trifluoromethanesulfonyl)imide was obtained in the same manner as in Example 1, except that bis(3,5-difluoro-2-iodophenyl)sulfoxide was used instead of bis(3,5-difluorophenyl)sulfoxide, and potassium bis(trifluoromethanesulfonyl)imide was used instead of potassium trifluoromethanesulfonate.

Production Example 6
<Synthesis of metal coordination compounds>
Diphenyl-4-carboxymethoxy-3,5-dimethylphenyl)sulfonium trifluoromethanesulfonate was obtained in the same manner as in Production Example 1, except that diphenyl sulfoxide was used instead of bis(3,5-difluorophenyl)sulfoxide.

Example 1
3 g of zirconium isopropoxide was dissolved in 20 g of THF. A solution obtained by mixing 4 g of benzoic acid, 1 g of the metal coordination compound obtained in Production Example 1, and 20 g of THF was added thereto at room temperature. The resulting mixture was kept at 65° C., and 2 mL of ion-exchanged water was added thereto, followed by a sol-gel reaction for 24 hours.
After the reaction was completed, the precipitate was collected and washed with acetone/water (volume ratio 1:4), and then dried at 40° C. under vacuum for 24 hours. Thus, an organometallic compound was obtained.
From the results of ^19F -NMR analysis of the obtained organometallic compound (using an apparatus named "JNM-ECX400P" manufactured by JEOL Ltd.), a peak (-104 ppm) derived from the cation of the metal coordination compound and a peak (-78 ppm) derived from the anion were confirmed, confirming that the metal coordination compound was coordinated.

0.3 g of the obtained organometallic compound was dissolved in 9.0 g of PGMEA, and then filtered through a filter with a pore size of 0.20 μm to remove insoluble aggregates. This resulted in the production of a photoresist.

Examples 2 to 7
An organometallic compound and a photoresist were obtained in the same manner as in Example 1, except that the ligand, metal, or metal oxide was changed as shown in Tables 1 and 2 below.

Comparative Examples 1 to 2
0.3 g of a metal or metal oxide and 0.15 g of a photoacid generator shown in Table 3 below were dissolved in 9.0 g of PGMEA, and the solution was filtered through a filter having a pore size of 0.20 μm to remove insoluble aggregates, thereby obtaining a photoresist.

The photosensitivity of the photoresists obtained in the Examples and Comparative Examples was evaluated by the following method.
<Method of evaluating photosensitivity>
A photoresist was applied onto the substrate that had been treated with hexamethyldisilazane using a spin coater, and then the solvent was removed by heating at 80° C. for 60 seconds to obtain a coating film with a thickness of about 50 nm.
The obtained coating film was placed in BL-3 at the University of Hyogo's NewSUBARU Synchrotron Radiation Facility and irradiated with 13.5 nm synchrotron radiation for irradiation times varying from 1 to 30 seconds. The coating film was then developed by immersing it in butyl acetate for 30 seconds and dried.
The coating film after development and drying was observed under a microscope, and the minimum exposure dose (Eth) at which the resist film remaining in the irradiated area had a thickness of 40 nm or more was measured.
The ratio of the minimum exposure dose (Eth) to the minimum exposure dose (Eth') when the photoresist of Comparative Example 1 was used was calculated from the following formula and used as an index of photosensitivity. The smaller the minimum exposure dose ratio, the better the photosensitivity.
Minimum exposure ratio=Eth/Eth'

From the above table, it can be seen that the organometallic compounds of the present invention have high sensitivity to light having ultrashort wavelengths, and that the sensitivity is further improved by introducing a halogen atom or a haloalkyl group as a substituent into the benzene ring constituting the cation moiety.
On the other hand, in the comparative examples, the photoacid generator is not coordinated to a metal or metal oxide, and therefore, it is understood that the sensitivity to light of ultrashort wavelengths is low.

In summary, the configuration of the present invention and its variations are described below.
[1] A compound comprising a metal or metal oxide (1) and a ligand (2) bonded to said (1),
The organometallic compound includes a ligand represented by formula (2) (wherein L represents a single bond or a linking group, and ^X- represents a monovalent counter anion. A substituent may be bonded to a carbon atom constituting a benzene ring. When two or more substituents are bonded to one benzene ring, the two or more substituents may be bonded to each other to form a ring together with the carbon atom to which the substituent is bonded).
[2] The organometallic compound according to [1], wherein the ligand represented by formula (2) is a ligand represented by formula (2-1) (wherein R ¹¹ and R ¹² each independently represent a halogen atom or a C _1-5 haloalkyl group; R ¹³ represents a halogen atom, a C _1-5 alkyl group, a C _1-5 alkoxy group, a C _1-5 haloalkyl group, or a C _1-5 haloalkoxy group; n11 and n12 each independently represent an integer of 1 to 5, and n13 represents an integer of 0 to 4; L represents a single bond or a linking group; and X ^- represents a monovalent counter anion).
[3] The organometallic compound according to [1], wherein the ligand represented by formula (2) is a ligand represented by formula (2-3) (wherein R ¹¹ and R ¹² each independently represent a halogen atom or a C _1-5 haloalkyl group; R ¹³ represents a halogen atom, a C _1-5 alkyl group, a C _1-5 alkoxy group, a C _1-5 haloalkyl group, or a C _1-5 haloalkoxy group; n11 and n12 each independently represent an integer of 1 to 5, and n13 represents an integer of 0 to 4; L ¹ represents an oxygen atom or a sulfur atom; n represents an integer of 1 to 5; and ^{X -} represents a monovalent counter anion).
[4] The organometallic compound according to any one of [1] to [3], wherein the (1) is at least one selected from hafnium, zirconium, tin, cobalt, palladium, antimony, and oxides thereof.
[5] A photosensitive material for photoresist, comprising the organometallic compound according to any one of [1] to [4].
[6] The photosensitive material for photoresist according to [5], which is a photosensitive material for extreme ultraviolet rays or a photosensitive material for electron beams.
[7] A photoresist comprising the organometallic compound according to any one of [1] to [4] and a solvent.

Claims (7)

A metal or metal oxide (1) and a ligand (2) bonded to said (1),
The organometallic compound (2) contains a ligand represented by the following formula (2):

(In the formula, L represents a single bond or a linking group, and ^X- represents a monovalent counter anion. A substituent may be bonded to a carbon atom constituting a benzene ring. When two or more substituents are bonded to one benzene ring, the two or more substituents may be bonded to each other to form a ring together with the carbon atom to which the substituent is bonded.) 2. The organometallic compound according to claim 1, wherein the ligand represented by the formula (2) is a ligand represented by the following formula (2-1):

(In the formula, R ¹¹ and R ¹² each independently represent a halogen atom or a C _1-5 haloalkyl group. R ¹³ represents a halogen atom, a C _1-5 alkyl group, a C _1-5 alkoxy group, a C _1-5 haloalkyl group, or a C _1-5 haloalkoxy group. n11 and n12 each independently represent an integer of 1 to 5, and n13 represents an integer of 0 to 4. L represents a single bond or a linking group, and X ⁻ represents a monovalent counter anion.) 2. The organometallic compound according to claim 1, wherein the ligand represented by the formula (2) is a ligand represented by the following formula (2-3):

(In the formula, R ¹¹ and R ¹² each independently represent a halogen atom or a C _1-5 haloalkyl group. R ¹³ represents a halogen atom, a C _1-5 alkyl group, a C _1-5 alkoxy group, a C _1-5 haloalkyl group, or a C _1-5 haloalkoxy group. n11 and n12 each independently represent an integer of 1 to 5, and n13 represents an integer of 0 to 4. L ¹ represents an oxygen atom or a sulfur atom, and n represents an integer of 1 to 5. ^{X -} represents a monovalent counter anion.) The organometallic compound according to any one of claims 1 to 3, wherein (1) is at least one selected from hafnium, zirconium, tin, cobalt, palladium, antimony, and oxides thereof. A photosensitive material for photoresist containing the organometallic compound according to any one of claims 1 to 3. The photoresist photosensitive material according to claim 5, which is an extreme ultraviolet photosensitive material or an electron beam photosensitive material. A photoresist comprising the organometallic compound according to any one of claims 1 to 3 and a solvent.