Upward EUV Photoresist and Method of Using the Same

Abstract

When incorporated into an EUV photoresist, novel non-polymeric aromatic core molecules containing oxygen and having acid- or base-reactive, crosslinkable functional groups, having improved sensitivity (photospeed), improved resolution (linewidth roughness), or both, are disclosed and claimed herein. Also disclosed are formulations and processes made from the disclosed molecules.

Description

Technical Field

[0001] This patent application discloses non-polymeric aromatic core molecules containing oxygen, acid- or base-reactive, crosslinkable functional groups that, when incorporated into EUV photoresists, have improved sensitivity (photospeed), improved resolution (line width roughness), or both. Also disclosed are formulations made from the disclosed molecules.

Background Art

[0002] Extreme ultraviolet lithography (EUVL) is one of the leading-edge technology options to replace optical lithography for high-volume semiconductor manufacturing at feature sizes below 20 nm. The very short wavelength (13.4 nm) is an important factor enabling the high resolution required in multiple technology generations. In addition, the overall system concepts such as scanning exposure, projection optics, mask format, and resist technology are very similar to those used in current optical technologies. Similar to previous lithography generations, EUVL consists of resist technology, exposure tool technology, and mask technology. Important issues are EUV source output and throughput. Improvements in EUV power directly affect current stringent resist sensitivity specifications. In fact, the major problem in EUVL imaging is resist sensitivity; the lower the sensitivity, the higher the required source output or the longer the exposure time required to fully expose the resist. The lower the output level, the more noise affects line width roughness (LWR), affecting line edge growth in negative resists or line edge recession in positive resists of printed lines. Since the feature size of resist dimensions is reduced to the wavelength of the imaging radiation, it is very difficult to obtain patterns with acceptable LWR.

[0003] Various attempts have been made to change the composition of EUV photoresist compositions in order to improve the performance of functional characteristics. Electronic device manufacturers continuously seek high resolution of the patterned photoresist image. It would be desirable to have a new photoresist composition that can provide improved imaging capabilities, including new photoresist compositions useful for EUVL.

[0004] As is well known, the manufacturing processes of various types of electronic or semiconductor devices such as ICs and LSIs involve, for example, forming a fine pattern of a resist layer on the surface of a substrate material such as a semiconductor silicon wafer. This fine patterning process has traditionally been carried out by photolithography, in which the substrate surface is uniformly coated with a positive-type or negative-type photosensitive composition to form a thin layer, selectively irradiated with actinic rays (such as ultraviolet rays (UV), deep ultraviolet rays, vacuum ultraviolet rays, extreme ultraviolet rays, X-rays, electron beams, and ion beams) through a transmission mask or a reflection mask, and then developing the coated photosensitive layer by selectively dissolving the exposed or unexposed regions of the actinic rays, leaving a resist layer patterned on the substrate surface. The thus obtained patterned resist layer can be used as a mask in subsequent processes on the substrate surface such as etching. Fabrication of structures having dimensions on the nanometer order is a field of significant interest in order to enable the realization of electronic and optical devices that also utilize novel phenomena such as quantum confinement effects to enable even higher density component packing. As a result, resist patterns are required to have an ever-increasing fineness that can be achieved by using actinic rays having wavelengths shorter than those of conventional ultraviolet rays. Thus, instead of conventional ultraviolet rays, electron beams (e-beams), excimer laser beams, EUV, BEUV, and X-rays may be used as actinic rays having short wavelengths. Needless to say, the minimum size that can be obtained is determined in part by the performance of the resist material and in part by the wavelength of the actinic rays. Various materials have been proposed as suitable resist materials. For example, in the case of a negative-type resist based on polymer crosslinking, there is an inherent resolution limit of about 10 nm, which is approximately the radius of a single polymer molecule.

[0005] It is also known to apply a technique called "chemical amplification" to resist materials. Chemically amplified resist materials are generally multi-component formulations that have a matrix material (such as a polyhydroxystyrene (PHOST) resin protected by acid-labile groups and a photoacid generator (PAG), with many of the main polymer components), as well as one or more additional components that impart the desired properties to the resist. The matrix material contributes to properties such as etching resistance and mechanical stability. By definition, chemical amplification occurs through a catalytic process involving PAG that results in a single irradiation event that causes the conversion of multiple resist molecules. The acid generated by the PAG undergoes a catalytic reaction with the polymer to cause it to lose functional groups or, alternatively, to cause a crosslinking event. The reaction rate can be accelerated, for example, by heating the resist film. In this way, a small number of irradiation events generate a large number of solubility change events, so the sensitivity of the material to actinic radiation is greatly increased. As described above, chemically amplified resists can be either positive or negative working.

[0006] Without being bound by theory, it is believed that the improvement in sensitivity leads to an improvement in the structural integrity of the photopattern of the resist. This can be due to a reduction in stray radiation, diffracted radiation, or scattered radiation. Also, in systems where crosslinking and ultimately photochemically enhanced polymerization are important ways to create the photopattern, controlling the crosslinking and / or polymerization is thought to improve the accuracy of the desired pattern, such as removal or reduction, of undesired problems such as line width roughness (LWR), line growth, and line sharpening.

[0007] In addition, in a negative photoresist system based on a curing mechanism that depends on a crosslinking and / or polymerization reaction, it is generally accepted that reactions occur almost uncontrollably due to the chain reaction that cures the resist. In a typical photoresist, when the exposure is insufficient, the photopattern is not sufficiently cured, and when the exposure is excessive, it causes the width of the photopattern to spread. In almost all negative working resist processes, post-exposure baking (PEB) is required to cure the resist to the point where it can withstand the development process including high pH developers, as well as solvent and semi-aqueous developers. When the exposed photoresist is exposed to the high temperatures of a standard resist process, it is difficult to maintain the desired photopattern.

Summary of the Invention

Problems to be Solved by the Invention

[0008] Patent documents describe numerous photoresist formulations containing epoxy materials as crosslinking agents used in acid-catalyzed curing processes. Patent documents describe a number of compounds useful in resists, and each compound has been shown to be as good as other compounds, but only a very small number of compounds are supported by experiments and process results. Many of the materials are disclosed in a list of all possible variations, but there is no supporting data. The resist pattern literature does not describe the novelty, uniqueness, or improvement regarding crosslinking agents, particularly crosslinking solutions for improving resist photospeed and / or reducing LWR. We conducted a detailed study to determine the validity that all crosslinkable compounds are equivalent to provide sensitivity and fine line photopatterns, and surprisingly, we found that some novel and unique crosslinking agents actually provide major improvements in the generation of photopatterns created with EUV radiation.

Means for Solving the Problems

[0009] This patent application discloses and claims novel crosslinking agents based on tris(triphenyl)methane as a core functional group and novel crosslinking agents based on 1,4-bis-(diphenylmethyl)benzene as a core functional group. The unexpected discovery disclosed in this application is not limited to tris(triphenyl)methane or 1,4-bis-(diphenylmethyl)benzene, and can be expected to be applicable to other aromatic systems that function as crosslinking agents, including, for example, polycyclic aromatic compounds, aromatic heterocyclic compounds, biphenyl compounds, monocyclic aromatic compounds, etc.

[0010] Also, these unique and novel crosslinking agents are proposed to be useful in conventional photoresist exposure processes such as exposure schemes of 365 nm, 248 nm, and 193 nm.

Brief Description of the Drawings

[0011]

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[0012] In a first embodiment, an acid- or base-sensitive crosslinking agent containing a core tris(4-hydroxyphenyl)methane group having Structure I is disclosed and claimed herein, **[Chemical formula]** wherein -O-R1 to -O-R3 are individually ortho, meta, or para to the methane atom, and R1 to R3 are the same or different and consist of at least one epoxy-ether crosslinkable functional group, a cycloepoxy-ether crosslinkable functional group, and / or an oxetane-ether crosslinkable functional group.

[0013] In a second embodiment, an acid- or base-sensitive crosslinking agent containing a core 1,4-(bis-4'-hydroxydiphenylmethyl)benzene core having Structure II is disclosed and claimed herein, **[Chemical formula]** wherein -O-R1 to -O-R4 are individually ortho, meta, or para to the methane atom, and R1 to R4 are the same or different and consist of at least one epoxy-ether crosslinkable functional group, a cycloepoxy-ether crosslinkable functional group, and / or an oxetane-ether crosslinkable functional group.

[0014] In the third embodiment, the acid or base-sensitive crosslinking agent described in any of the above embodiments is disclosed and claimed herein, wherein R1 to R4 may be the same or different and include a glycidyl ether, 1,2-epoxy 4-butyl ether, 1,2-epoxycyclohexane-4-methyl ether, or an oxetane ether group.

[0015] In the fourth embodiment, the acid or base-sensitive crosslinking agent described in any of the above embodiments is disclosed and claimed herein, wherein at least one hydrogen of at least one of the hydroxyphenyl groups is substituted with an iodide, a fluoride, or a fluoride-containing group, or a combination thereof.

[0016] In the fifth embodiment, a photosensitive composition comprising at least one epoxy ether having a structure selected from the following I or II, at least one photoacid or photobase generator, optionally an amphoteric ion component, and at least one solvent is disclosed and claimed herein,

Chemical formula

[0017] In the sixth embodiment, the composition of the above embodiment is disclosed and claimed herein, wherein R1 to R4 may be the same or different and include a glycidyl ether, 1,2-epoxy 4-butyl ether, 1,2-epoxycyclohexane-4-methyl ether, or an oxetane ether group.

[0018] In the seventh embodiment, the composition of the above embodiment is disclosed and claimed herein, wherein any of the phenyl groups is substituted with an iodide, a fluoride, or a fluoride-containing group, or a combination thereof.

[0019] In the eighth embodiment, the composition of the above embodiment further comprising a nucleophilic quencher is disclosed and claimed herein, and the nucleophilic quencher is triphenylsulfonium triflate or triphenylsulfonium tosylate.

[0020] In the ninth embodiment, the composition of the above embodiment is disclosed and claimed herein, and at least one photoacid generator is selected from sulfonium salts, iodonium salts, sulfonimides, halogen-containing compounds, sulfone compounds, ester sulfonate compounds, diazomethane compounds, dicarboxyimidyl sulfonic acid esters, iridene aminooxysulfonic acid esters, sulfanyl-diazomethane, or mixtures thereof, and at least one solvent comprises esters, ethers, ether-esters, ketones, cyclic ketones, halogenated solvents, alkyl-aryl ethers, alcohols, or combinations thereof.

[0021] As used herein, the terms ortho, meta, and para are positioned on the core aromatic ring relative to the methanecarbon to which the aromatic group is attached.

[0022] As used herein, the conjunction "and" is intended to be inclusive, and the conjunction "or" is not intended to be exclusive unless otherwise indicated. For example, the phrase "or, alternatively" is intended to be exclusive.

[0023] As used herein, terms such as "having", "containing", "including", "comprising", etc. are non-limiting terms indicating the presence of the recited element or feature, but do not exclude additional elements or features. The articles "a", "an", and "the" are intended to include plural as well as singular unless clearly indicated otherwise by the context.

[0024] As used herein, the term "photo speed" means the EUV radiation dose required to obtain 22 nm lines when processed through the formulation tests described below.

[0025] As used herein, the term "blend" refers to the mixing of at least two crosslinking agents that may differ in basic structure, substituents, and / or isomers.

[0026] The novel crosslinking agents of the present disclosure contain a core of tris(4-hydroxyphenyl)methane or a core of 1,4-(bis-4'-hydroxydiphenylmethyl)benzene. Oxygen substituents are arranged on three core phenyl groups on the ortho, meta, or para of Structure I relative to the methyl atom of the core structure. The three oxygen substituents can be arranged at different positions in that one oxygen substituent can be para, while another oxygen substituent can be meta, and the third oxygen substituent can be ortho, meta, or para. The oxygen substituents are arranged on four core phenyl groups bonded to the central core phenyl group on the ortho, meta, or para of Structure II relative to the methyl atom of the core structure. The oxygen substituents can be arranged at different positions in that one oxygen substituent can be para, while another oxygen substituent can be meta, and the third oxygen substituent can be ortho, meta, or para.

[0027] The zwitterionic component of the photosensitive composition of the present disclosure can have the following structure. [Chemical formula] [Examples]

[0028] Experiment Synthesis of materials The following is a general procedure for synthesizing representative novel crosslinking agents of the present disclosure: A) Condense the selected aldehyde with phenol to create a triphenylmethyl core: Under an argon atmosphere, an aldehyde (1.00 equivalent), phenol (4.0 equivalents), PTSA (20 mol%), and zinc chloride (20 mol%) were placed in a flask of appropriate size. The reaction mixture was heated to 50 °C and stirred overnight. Water (25 mL) was added, and the reaction mixture was extracted with EtOAc (3 × 25 mL). The combined organic fractions were washed with water (3 × 15 mL) and brine (15 mL), dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to obtain a crude residue purified by automated flash column chromatography (0 - 100% Hx / EtOAc).

[0029] B) Synthesis of the selected epoxide: Under an argon atmosphere, the triphenylmethyl core from A) (1.0 equivalent) was dissolved in epichlorohydrin (30.0 equivalents). Tetraethylammonium iodide (20 mol%) was added, and the mixture was heated to 80 °C overnight. An aqueous solution of NaOH (50%, (weight / weight), 4.5 equivalents) was added, and the reaction was stirred for an additional 3 hours. Upon cooling to room temperature, the mixture was stirred through cotton wool, and the filtrate was collected. Water (25 mL) was added, and the reaction mixture was extracted with EtOAc (2 × 25 mL). The combined organic fractions were washed with water (3 × 15 mL) and brine (15 mL), dried over anhydrous MgSO 4 and filtered, and concentrated under reduced pressure to obtain a crude residue purified by automated flash column chromatography (0 - 100% Hx / EtOAc).

[0030] C) Demethylation reaction (if necessary) Under an argon atmosphere, boron tribromide (1.0 M in heptane, 4.5 equivalents) was added dropwise at 0 °C to a cooled solution of the selected triphenylmethane core (1.0 equivalent) in anhydrous dichloromethane (0.2 M). The resulting solution was warmed to room temperature and stirred overnight. Water (25 mL) was added, and the reaction mixture was extracted with EtOAc (3 × 25 mL). The combined organic fractions were washed with water (3 × 15 mL) and brine (15 mL), dried over anhydrous MgSO 4It was dried above, filtered, concentrated under reduced pressure, and the crude residue was purified by automated flash column chromatography (0 - 100% Hx / EtOAc) to obtain a crude residue.

[0031] D) Iodination (if necessary) Under an argon atmosphere, the selected triphenylmethane core (1.0 equiv), NaOH (3.3 equiv), and KI (3.3 equiv) were dissolved in a solution of water / ethanol (75:25, (v / v)). The solution was cooled to 0 °C, and I2 (3.3 equiv) was added. The resulting mixture was covered with aluminum foil, warmed to room temperature, and stirred overnight. An aqueous solution of HCl (4.0 M, 40 mL) was added, and the mixture was extracted with EtOAc (1 × 400 mL). The combined organic fractions were washed with a saturated aqueous solution of sodium thiosulfate (1 × 100 mL), brine (1 × 100 mL), and anhydrous MgSO 4 It was dried above, filtered, concentrated under reduced pressure, and the crude product was purified by automated flash column chromatography (0 - 100% Hx / EtOAc) to obtain a crude product. Synthesis of Compound 19 Synthesis of 4,4'-((4-ethoxyphenyl)methylene)diphenol 7 The compound prepared from 4-ethoxybenzaldehyde was condensed on a 13.35 mmol scale according to the general procedure. 7 was obtained in a 58% yield as an off-white solid (2.470 g, 58%).

[0032] Synthesis of 4,4'-((4-ethoxyphenyl)methylene)bis(2,6-diiodophenol) 8 The procedure of the literature was partially modified. 24,4’-((4-Ethoxyphenyl)methylene)diphenol 7 (2.470 g, 7.71 mmol) was dissolved in a solution of KOH (3.24 g, 57.82 mmol) in MeOH (39.0 mL). To this solution, I2 (7.830 g, 30.84 mmol) was added in one portion, and the reaction mixture was stirred for about 10 minutes under argon protection. An aqueous solution of HCl (4.0 M, 20 mL) was added until pH 4 - 5 was reached, and thus the mixture was extracted with EtOAc (3 × 25 mL). The combined organic fractions were washed with brine (25 mL), dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to obtain a crude product purified by automated flash column chromatography (0 - 100% Hex / EtOAc). The title compound was obtained as a dark solid (2.80 g, 44%).

[0033] Synthesis of 4,4’-((4-Hydroxyphenyl)methylene)bis(2,6-diiodophenol) 9 The compound prepared from 8 was dialkylated on a 2.38 mmol scale according to the general procedure. 9 was obtained as a pale yellow solid (1.80 g, 95). Synthesis of ((((4-(Oxiran-2-ylmethoxy)phenyl)methylene)bis(2,6-diiodo-4,1-phenylene))bis(oxy))bis(methylene)bis(oxetane-3,3-diyl))dimethanol 9 (1.70 g, 2.14 mmol) was dissolved in MeCN (7.1 mL), and the resulting solution was added to K2CO3 (0.82 g, 5.99 mmol), followed by addition to (3-(Bromomethyl)oxetan-3-yl)methanol (1.07 g, 5.88 mmol). The mixture was stirred at 60 °C overnight, at which point another portion of potassium carbonate (0.41 g, 2.99 mmol) was added, followed by epichlorohydrin (0.24 g, 2.57 mmol). After a further 16 hours, water (10 mL) was added, and the mixture was extracted with EtOAc (3 × 25 mL). The combined organic fractions were washed with brine (25 mL), anhydrous MgSO 4It was dried above, filtered, and concentrated under reduced pressure. The obtained crude residue was purified by automated flash column chromatography (0 - 100% Hx / EtOAc). CL2134 was obtained as a white solid (0.20 g, 9%).

[0034] Synthesis of Compound 5 Synthesis of 4,4’-((3-Fluoro-4-methoxyphenyl)methylene)diphenol 15 Under nitrogen, a mixture of 2-fluoro-p-anisaldehyde (4.00 g, 25.97 mmol), phenol (12.21 g, 129.87 mmol), ZnCl2 (0.32 g, 2.34 mmol), and PTSA (0.49 g, 2.6 mmol) was stirred at room temperature for 1 hour, and then a viscous slurry formed. This was heated to 45 °C and left for 24 hours. The reaction was cooled to room temperature. Ethyl acetate (40 mL) was added and washed with water (2×10 mL). The organic phase was dried over MgSO4 and evaporated to dryness under vacuum. The solid was further purified by column chromatography (silica, 80% hexane:20% ethyl acetate) to obtain 15 as a pale yellow solid (5.90 g, 65%).

[0035] Synthesis of 4,4’-((3-Fluoro-4-methoxyphenyl)methylene)bis(2,6-diiodophenol) 16 Under nitrogen, a solution of 15 (0.70 g, 2.16 mmol), NaOH (0.52 g, 12.96 mmol), and KI (1.98 g, 11.88 mmol) in water / ethanol (1:1, 50 mL) was cooled to 0 °C. Iodine (3.02 g, 11.88 mmol) was added, the reaction was covered with foil, and warmed to room temperature. After 24 hours, HCl (6 M, 10 mL) was added. The precipitate was filtered and washed with water (3×20 mL), followed by hexane (10 mL). The precipitate was further purified by column chromatography (silica, 60% n-hexane:40% ethyl acetate) to obtain 16 as a white solid (0.90 g, 50%).

[0036] Synthesis of 4,4'-((3-Fluoro-4-hydroxyphenyl)methylene)bis(2,6-diiodophenol) 17 Under nitrogen, a solution of 16 (0.33 g, 0.40 mmol) in degassed dichloromethane (5 mL) was cooled to -78 °C. BBr3 (1 M in dichloromethane, 1.32 mL) was added over 5 minutes. The solution was left to warm to room temperature. After 20 hours, the reaction was quenched with ice (3 g). After the ice had melted, ethyl acetate (20 mL) was added. The mixture was washed with water (10 mL), followed by brine (10 mL), and then dried over MgSO 4 4. The organic phase was evaporated to dryness under vacuum to give 17 as a white solid (0.27 g, 83%). Further purification was not necessary. 1 H NMR: 4I3FOH F1 otter 10 / 12 / 20 Synthesis of 2,2'-(((((3-Fluoro-4-(oxiran-2-ylmethoxy)phenyl)methylene)bis(2,6-diiodo-4,1-phenylene))bis(oxy))bis(methylene))bis(oxirane) Under nitrogen, a solution of 17 (170 mg, 0.21 mmol) and tetraethylammonium iodide (20 mg, 0.06 mmol) in epichlorohydrin (5 mL) was heated and maintained at 80 °C for 20 hours. Sodium hydroxide (50% (w / w) in water, 0.94 mmol) was added to the reaction and left for a further 3 hours. The reaction was cooled to room temperature and then gravity filtered. The precipitate was washed with ethyl acetate (2 × 10 mL). The washings were combined with the filtrate. The filtrate was washed with water (3 × 20 mL), dried over MgSO4, and evaporated to dryness under vacuum. The solid was further purified by recrystallization using ethyl acetate:hexane (1:5) and column chromatography (silica, 30% hexane:70% ethyl acetate) to give Compound 5 as a white solid (30 mg, 15). Synthesis of Representative Novel Compounds of the Present Disclosure [Chemical formula] Molecular weight: 1032.11

[0037] Synthesis of 4,4'-((4-methoxy-3-(trifluoromethyl)phenyl)methylene)diphenol 20 The compound prepared from 19 was condensed on a 4.9 mmol scale according to the general procedure. 20 was obtained as a light red solid (1.7 g, 93%).

[0038] Synthesis of 4,4'-((4-methoxy-3-(trifluoromethyl)phenyl)methylene)bis(2,6-diiodophenol) 21 The compound 21 prepared from 20 was iodinated (Method I) on a 2.14 mmol scale according to the general procedure. 21 was obtained as an orange / red solid (0.77 g, 41% yield).

[0039] Synthesis of 4,4'-((4-hydroxy-3-(trifluoromethyl)phenyl)methylene)bis(2,6-diiodophenol) 22 The compound 22 prepared from 21 was dialkylated on a 0.88 mmol scale according to the general procedure. 22 was obtained as an orange solid (0.32 g, 42). Synthesis of 2,2'-(((((4-(oxiran-2-ylmethoxy)-3-(trifluoromethyl)phenyl)methylene)bis(2,6-diiodo-4,1-phenylene))bis(oxy))bis(methylene))bis(oxirane) CL2103 This compound prepared from 22 was obtained as an epoxide adduct on a 0.37 mmol scale according to the general procedure. CL2103 was obtained as a white solid (0.17 g, 51%).

[0040] Synthesis of Compound 16 Synthesis of 4,4',4'',4'''-(1,4-phenylenebis(methanetriyl))tetraphenol 25 The compound prepared from terephthalaldehyde was condensed on a 7.46 mmol scale according to the general procedure. Phenol was used in 9 molar equivalents. ZnCl 2 and PTSA were used in 0.2 molar equivalents. 25 was obtained as a white solid (1.7 g, 48%).

[0041] 1,4-bis(bis(4-(oxiran-2-ylmethoxy)phenyl)methyl)benzene The compound 16 prepared from 25 was used to obtain an epoxide adduct on a 1.54 mmol scale according to a general procedure. Epichlorohydrin was used in 100 molar equivalents, and Et 4 NI was used in 0.4 molar equivalents.

[0042] Synthesis of Compound 14 Synthesis of 4,4’,4’’,4’’’-((perfluoro-1,4-phenylene)bis(methanetriyl))tetraphenol 26 The compound prepared from tetrafluoro-terephthalaldehyde was condensed on a 9.7 mmol scale according to a general procedure. Phenol was used in 9 molar equivalents. ZnCl 2 and PTSA were used in 0.2 molar equivalents. 26 was obtained as a pale yellow solid (5.04 g, 95%). Synthesis of 2,2’,2’’,2’’’-(((((perfluoro-1,4-phenylene)bis(methanetriyl))tetrakis(benzene-4,1-diyl))tetrakis(oxy))tetrakis(methylene))tetrakis(oxirane) CL2122 The compound 14 prepared from 26 was used to obtain an epoxide adduct on a 4.85 mmol scale according to a general procedure. Epichlorohydrin was used in 100 molar equivalents, and Et 4 Nl was used in 0.4 molar equivalents to obtain a pale yellow solid (0.95 g, 25). Synthesis of Compound 10 (3-((4-(bis(4-(oxiran-2-ylmethoxy)phenyl)methyl)phenoxy)methyl)oxetan-3-yl)methanol synthesis Under nitrogen, a solution of 4,4,4-trihydroxyphenylmethane (1 g, 3.42 mmol) and NaH (82 mg, 3.42 mmol) in DMF (10 mL) was stirred for 5 minutes, then (3-(bromomethyl)oxetan-3-yl)methanol (1.24 g, 6.84 mmol) was added. The reaction mixture was heated to 50 °C for 16 hours. Epichlorohydrin (5 mL, 64 mmol) was added, followed by Et 4 NI (260 mg, 1 mmol) was added and the mixture was heated to 80 °C for an additional 16 hours. 50% (weight / weight) NaOH in water (0.82 mL) was added to the reaction mixture and the reaction was maintained for an additional 3 hours. The reaction mixture was cooled to room temperature and filtered through cotton. The mixture was washed with EtOAc (2 × 10 mL), followed by water (15 mL). The organic layer was washed with brine (15 mL) and dried over MgSO 4 4. The organic phase was evaporated to dryness under reduced pressure. The solid was further purified by column chromatography (silica, 90% dichloromethane:10% ethyl acetate).

[0043] Synthesis of Compound 15 Synthesis of 4,4’-((4-methoxy-2-(trifluoromethyl)phenyl)methylene)diphenol 27 The compound prepared from 4-methoxy-2-(trifluoromethyl)benzaldehyde was condensed on a 4.9 mmol scale according to the general procedure. 27 was obtained as a white solid (1.7 g, 93). Synthesis of 4,4’-((4-hydroxy-2-(trifluoromethyl)phenyl)methylene)diphenol 28 Compound 28 prepared from 27 was dialkylated on a 4.8 mmol scale according to the general procedure. 28 was obtained as a white solid (1.1 g, 63). Synthesis of 2,2’-(((((4-(oxiran-2-ylmethoxy)-2-(trifluoromethyl)phenyl)methylene)bis(4,1-phenylene))bis(oxy))bis(methylene))bis(oxirane) Compound 15 prepared from 28 was used to obtain an epoxide adduct on a 3.05 mmol scale according to the general procedure. CL2128 was obtained as a colorless solid (0.7 g, 44%).

[0044] Synthesis of Compound 22 Synthesis of 4,4’-((2-Hydroxy-3,5-diiodophenyl)methylene)bis(2,6-diiodophenol) 32 The procedure in the literature was partially modified. 1KI (4.70 g, 28.32 mmol) was added portionwise to a solution of 4,4’-((2-hydroxyphenyl)methylene)diphenol 13 (synthesis shown in Scheme 7, 1.38 g, 4.72 mmol), NaIO4 (6.06 g, 28.32 mmol), and NaCl (3.31 g, 56.65 mmol) in AcOH / water (9:1, (volume / volume), 16 mL). The resulting mixture was stirred at room temperature until complete consumption of the starting materials was observed by TLC. Water (30 mL) was added and the mixture was extracted with EtOAc (3 × 25 mL). The combined organic fractions were washed with brine (35 mL), dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure. The resulting crude residue was purified by automated flash column chromatography (0 - 50% Hex / EtOAc). The title compound was obtained as a dark red solid (0.430 g, 0.41 mmol) in 9% yield.

[0045] Synthesis of 2,2’-(((((3,5-Diiodo-2-(oxiran-2-ylmethoxy)phenyl)methylene)bis(2,6-diiodo-4,1-phenylene))bis(oxy))bis(methylene))bis(oxirane) Compound 22 The compound prepared from 4,4’-((2-Hydroxy-3,5-diiodophenyl)methylene)bis(2,6-diiodophenol) 32 was used to obtain an epoxide adduct on a 0.41 mmol scale according to the general procedure. The title compound was obtained as a clear, highly viscous oil (0.200 g, 0.16 mmol) in 40% yield.

[0046] 1. C. Ge, H. Wang, B. Zhang, J. Yao, X. Li, W. Feng, P. Zhou, Y. Wang and J. Fang, Chem. Commun., 2015, 51, 14913 - 14916. 2. K. Omura, J. Org. Chem., 1984, 49, 3046 - 3050. 3. A. A. Kelkar, N. M. Patil and R. V. Chaudhari, Tetrahedron Lett., 2002, 43, 7143 - 7146. 4. T. Dohi, N. Yamaoka and Y. Kita, Tetrahedron, 2010, 66, 5775 - 5785.

[0047] Blending General blending: Since each of the novel crosslinking agents has a different molecular weight, the blending is described in molar ratios. Crosslinking agents having a high opacity crosslinking agent (Compounds 1 - 7 and 9 - 15) are blended at a different molar equivalent (Formula B below) from the non - high opacity crosslinking agents (Compounds 8 and 16) (Formulas A1 - A2 below).

[0048] Formula A1: To ethyl lactate, add 1 molar equivalent of the novel crosslinking agent, 0.461 molar equivalent of PAG, and 0.090 molar equivalent of the nucleophilic quencher to prepare 16.5 g / L.

[0049] Formula A2: To ethyl lactate, add 0.128 molar equivalent of EX2, 1 molar equivalent of the novel crosslinking agent, 0.461 molar equivalent of PAG, and 0.090 molar equivalent of the nucleophilic quencher to prepare 16.5 g / L.

[0050] Formula B1: To ethyl lactate, add 1 molar equivalent of the novel crosslinking agent, 0.455 molar equivalent of PAG, and 0.077 molar equivalent of the nucleophilic quencher.

[0051] Formula B2: To ethyl lactate, add 0.063 molar equivalent of EX2, 1 molar equivalent of the novel crosslinking agent, 0.455 molar equivalent of PAG, and 0.077 molar equivalent of the nucleophilic quencher.

[0052] It has also been found that two or more crosslinking agents containing different isomers of the present disclosure can be combined in various ratios to obtain a combination for forming a blend of the properties of those blend crosslinking agents.

[0053] The percent solids in the formulation can be varied to obtain a 20 nm film thickness when spun and dried.

[0054] Testing of the formulation Note: When the formulation is prepared at such concentrations and spun and dried at 1500 - 2500 rpm, a 20 nm film thickness is obtained. The film thickness is measured using polarized analytical optical techniques.

[0055] Silicon wafers were spin - coated at 2000 rpm using a Brewer Science Optistack AL 212 underlayer and baked at 205 °C for 30 seconds. The resist formulation was dispensed onto the wafers using a pipette and spun at the rotational speed required to obtain a 20 nm film thickness target, generally 1200 - 2300 rpm. The wafers were baked at 60 °C for 3 minutes to confirm that the film was still suitable for exposure (e.g., no solder repulsion).

[0056] The wafers were exposed using a PSI synchrotron and a non - contact mask. The mask contained a pattern of line - spaces with a pitch of 44 nm, and multiple dies were exposed on one wafer while increasing the radiation dose. The wafers can optionally be subjected to post - exposure baking, generally at 60 °C - 80 °C for 1 - 2 minutes. The wafers were immersed in nBA (n - butyl acetate) for 30 - 60 seconds for development and then optionally rinsed in MIBC (methyl isobutyl carbinol) for 15 seconds.

[0057] The pattern was then inspected using SEM, and images were taken through the radiation dose. The line width and line width roughness were measured using a software package called SMILE.

[0058] Plot the line width and LWR against the radiation dose, calculate the trend line, calculate the radiation dose required to achieve 22 nm lines from this plot, and record the LWR at 22 nm lines.

[0059] Results Figures 4 - 8 show scanning electron microscope images of formulations using the specified novel crosslinkers of the present disclosure.

[0060] Note: In some SEMs, for example, the SEMs of Compounds 6 and 7 do not have an acceptable resist structure, but the photospeed is very high and may be able to make the pattern more acceptable at a lower radiation dose.

[0061] The results show that when using EUV photoresists, various very specific acid - sensitive epoxy and oxetane crosslinkers show major improvements in line - width roughness or photospeed, or both, compared to commercially available or other classes of oxygen - containing crosslinkers. Also notable are the improved results associated with crosslinkers containing high - EUV - absorbance iodide substituents, fluoride substituents, and combinations thereof at various positions throughout the molecule.

[0062] Improvement in line - width roughness As can be seen from Table 1 below, for Compound 1, compared to a commercial control, the addition of a methylene group between the oxygen functional group and the epoxy functional group in the phenol moiety improves the line - width roughness by 30%. [Table 1]

[0063] In Table 1, when the epoxy group is located on the cyclohexane structure, Compound 2 shows a 7.7% improvement in line width roughness. Also in Table 1, when the oxetane group is replaced with epoxy (Compounds 3 and 4), the line width roughness improves by 21% and 18% respectively. In Table 1, Compound 5 has the core of Compound 1, but both iodide and fluoride are substituted on the phenyl ring, and the line width roughness improves by 15%.

[0064] Improvement in photospeed When incorporated into EUV photoresists, the crosslinkable compounds in Tables 2, 3, and 4 provided an improvement in photospeed compared to commercially available crosslinking agents. Without being bound by theory, it is believed that the additional degrees of freedom provided by extending the reactive epoxy or oxetane groups further away from the core structure, similar to Compounds 1 and 2, make the crosslinking reaction easier. Interestingly, it was surprisingly found that the oxetane group of Compound 3 provided an increase in photospeed, but not as much as that of Compound 1 or 2. The epoxy group is considered to be more reactive because it has more strain than oxetane.

[0065] Compounds 1 and 6, which are different in that compound, contained three iodides substituted on the aromatic ring. Surprisingly, the non-iodinated compound showed a very high speed. Compound 7, which is different from the control and Compound 6 in that the epoxy chain contains another methylene group and thus moves the reactive epoxy further away from the core molecule, also showed a very high photospeed.

Table 2

[0066] Other variations of the novel crosslinking agents presented in this disclosure are shown in Tables 3 and 4 below. As shown in Table 3, compounds 8, 9, and 2 are all members of the epoxycyclohexane crosslinkable functional group. As can be seen, the photospeed is improved compared to the commercial control, but has essentially equal photospeed despite molecular changes or blends of isomers. Compound 10 has two epoxy group pendants and one oxetane on the molecule. The photospeed is essentially the same as that of all epoxy molecules and has essentially the same I photospeed, i.e., it is much improved compared to the commercial control.

[0067] Compound 11 contains six trifluoromethyl groups substituted on the methylene group α to the phenolic oxygen. Again, the photospeed is much improved compared to the commercial crosslinker.

Table 3

[0068] Table 4 discloses other novel crosslinkers of this application. Compound 12 represents a member of the fluorinated molecules of this disclosure. Here, three trifluoromethyl groups are substituted on the phenyl ring. The photospeed is better than the control, but not as fast as some of the other novel crosslinkers presented. The photospeed did not increase as high as some of the other crosslinkers presented here, but the presence of the fluorinated group shows other advantages such as solubility.

[0069] Compound 13 is similar to Compound 12, but has an extra methylene group α to the phenolic oxygen, thus extending the ether chain and moving the reactive epoxy group further from the core molecule. As can be seen, the photospeed is significantly improved by extending the chain about 7-fold. Compound 15 is similar to Compound 12, but has only one trifluoromethyl group substituted on the phenyl group. The photospeed increases compared to the trisubstituted crosslinker.

[0070] Compounds 14 and 16 contain a penta-aryl basic core structure (Structure II): 1,4-bis-(diphenylmethyl)benzene. The epoxy group is a glycidyl ether, and compound 14 contains four fluorides substituted on the central phenyl ring. As can be seen, the photospeed of compound 14 is significantly improved, while the non-fluorinated compound 16 shows only a slight improvement in photospeed.

Table 4

Claims

1. An acid or base-sensitive crosslinking agent comprising a coatris(4-hydroxyphenyl)methane group having structure I, 【Chemistry 1】 A crosslinking agent wherein R1 to R3 are the same or different and consist of at least one epoxy-ether crosslinkable functional group, a cycloepoxy-ether crosslinkable functional group, and / or an oxetane-ether crosslinkable functional group.

2. The crosslinking agent according to claim 1, wherein R1 to R3 may be the same or different and comprises at least one of glycidyl ether, 1,2-epoxy 4-butyl ether, 1,2-epoxycyclohexane-4-methyl ether, or oxetane ether group.

3. An acid or base-sensitive crosslinking agent comprising a coatris(4-hydroxyphenyl)methane group having the following structure, 【Chemistry 2】 A crosslinking agent wherein R1 to R3 are the same or different and consist of at least one of an epoxy ether crosslinking functional group, a cycloepoxy-ether crosslinking functional group, and / or an oxetane-ether crosslinking functional group, and at least one of the hydrogens of at least one of the hydroxyphenyl groups is substituted with iodide, fluoride, or a fluoride-containing group, or a combination thereof.

4. The crosslinking agent according to claim 3, wherein R1 to R3 may be the same or different and comprises at least one of glycidyl ether, 1,2-epoxy 4-butyl ether, 1,2-epoxycyclohexane-4-methyl ether, or oxetane ether group.

5. An acid or base-sensitive crosslinking agent comprising a core 1,4-(bis-4'-hydroxydiphenylmethyl)benzene core having structure II, 【Transformation 3】 A crosslinking agent wherein R1 to R4 are the same or different and consist of at least one epoxy-ether crosslinkable functional group, a cycloepoxy-ether crosslinkable functional group, and / or an oxetane-ether crosslinkable functional group.

6. The crosslinking agent according to claim 5, wherein R1 to R4 may be the same or different and comprises a glycidyl ether, 1,2-epoxy-4-butyl ether, 1,2-epoxycyclohexane-4-methyl ether, or an oxetane ether group.

7. An acid or base-sensitive crosslinking agent comprising a coatris(4-hydroxyphenyl)methane group having structure II, 【Chemistry 4】 II A crosslinking agent wherein R1 to R4 are the same or different and consist of an epoxy-ether crosslinkable functional group, a cycloepoxy-ether crosslinkable functional group, and / or an oxetane-ether crosslinkable functional group, and at least one of the hydrogen atoms of the hydroxyphenyl group is substituted with iodide, fluoride, or a fluoride-containing group, or a combination thereof.

8. The crosslinking agent according to claim 7, wherein R1 to R4 may be the same or different and comprises a glycidyl ether, 1,2-epoxy-4-butyl ether, 1,2-epoxycyclohexane-4-methyl ether, or an oxetane ether group.

9. A photosensitive composition, a. At least one epoxy ether having a structure selected from I or II below, 【Transformation 5】 b. At least one photoacid or photobase generator, c. comprising at least one solvent, A photosensitive composition comprising, in the formula, R1 to R4 being the same or different, and containing an epoxy-ether crosslinkable functional group, a cycloepoxy-ether crosslinkable functional group, and / or an oxetane-ether crosslinkable functional group.

10. The composition according to claim 9, wherein R1 to R4 may be the same or different and comprises a glycidyl ether, 1,2-epoxy-4-butyl ether, 1,2-epoxycyclohexane-4-methyl ether, or an oxetane ether group.

11. The composition according to claim 9, wherein R1 to R4 are the same or different and consist of an epoxy-ether crosslinkable functional group, a cycloepoxy-ether crosslinkable functional group, and / or an oxetane-ether crosslinkable functional group, and at least one of the hydrogen atoms of the hydroxyphenyl group is substituted with iodide, fluoride, or a fluoride-containing group, or a combination thereof.

12. The composition according to claim 9, further comprising a nucleophilic quencher.

13. The composition according to claim 12, wherein the nucleophilic quencher is triphenylsulfonium triflate or triphenylsulfonium tosylate.

14. The composition according to claim 9, wherein the at least one solvent comprises an ester, ethyl lactate, ether, ether-ester, propylene glycol monomethyl ether acetate, and propylene glycol monomethyl ether.

15. The photosensitive composition according to claim 9, further comprising at least a zwitterionic component, wherein R1 to R4 are the same or different and comprise an epoxy-ether crosslinkable functional group, a cycloepoxy-ether crosslinkable functional group, and / or an oxetane-ether crosslinkable functional group.

16. The composition according to claim 14, wherein R1 to R4 are the same or different and consist of an epoxy-ether crosslinkable functional group, a cycloepoxy-ether crosslinkable functional group, and / or an oxetane-ether crosslinkable functional group, and at least one of the hydrogens of at least one hydroxyphenyl group is substituted with iodide, fluoride, or a fluoride-containing group, or a combination thereof.

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