Cluster compound or salt thereof and photoresist composition comprising the same

Abstract

The present invention relates to a cluster compound or a salt thereof and a photoresist composition containing the same. By introducing surface molecules that facilitate bonding and dissociation, the invention provides a cluster compound or a salt thereof that ensures the chemical stability of the cluster compound while having significantly enhanced EUV sensitivity, thereby enabling the formation of a photoresist pattern with excellent sensitivity.

Description

Technology Field

[0001] The present invention relates to a cluster compound or a salt thereof and a photoresist composition containing the same. Background Technology

[0002] In the patterning process of semiconductor manufacturing, lithography using photoresist compositions is performed. I-line (365 nm), KrF (248 nm), and ArF (193 nm) have mainly been used as lithography light sources. With the high integration of semiconductors, the formation of ultrafine patterns is required, and to this end, the wavelength of light sources is gradually becoming shorter. In particular, extreme ultraviolet (EUV) with a wavelength of 13.5 nm is emerging as the next-generation light source for manufacturing ultra-highly integrated semiconductors.

[0003] In the EUV lithography process, photons with a strong energy of 92 eV (13.5 nm) are irradiated, and unlike the lithography process of a conventional light source in which the dissolution contrast of the photoresist is expressed through a photochemical reaction, the dissolution contrast of the photoresist is expressed through a radiochemical reaction by secondary electrons generated after EUV irradiation.

[0004] Conventional ArF, located in the ultraviolet region, could be captured by refracting it using lenses. However, EUV is closer to X-rays and is difficult to refract. Therefore, light is captured using reflection. The reflection efficiency of mirrors used in EUV lithography equipment is approximately 60–70% [Proc. of SPIE, 9658, 965814-2, 2015], and based on eight mirrors, the amount of light reaching the wafer is about 5.8% of the light source. Furthermore, the number of photons per unit volume under the same incident energy is only 7% of that of conventional ArF. Consequently, the use of photoresists with high EUV sensitivity is required.

[0005] Conventional chemically amplified resist (CAR) type organic photoresists have the advantage of very high photosensitivity, but due to the characteristics of organic materials, they have the disadvantage of low etch resistance, so these photoresist films must be formed with a thickness above a certain level. As the width of the photoresist pattern decreases due to semiconductor miniaturization, the aspect ratio of the pattern increases, and as a result, a problem of pattern collapse occurs during the cleaning process.

[0006] To overcome this, new EUV photoresists are required, and inorganic photoresists are attracting attention as EUV photoresists because they possess excellent etch resistance and mechanical strength, allowing them to be formed with very thin thicknesses even in ultrafine patterns, thereby preventing pattern collapse problems. In addition, inorganic photoresists have the advantage of having a superior level of EUV sensitivity compared to conventional organic photoresists, as they contain inorganic elements such as tin (Sn), which have a very high photoionization cross-section for EUV photons.

[0007] As an example of an inorganic photoresist, the paper [Microelectronic Engineering 2014, 127, 44-50] discloses tin oxide clusters. These clusters are small in size, enabling excellent line edge roughness (LER) characteristics, and due to the inclusion of tin, they possess superior EUV absorption coefficients and etch resistance compared to conventional organic photoresists. However, even the allyl tin oxo cluster, described as having the highest sensitivity, has a dose-to-size ratio of 180 mJ / cm² for EUV irradiation. 2 At this level, EUV sensitivity is not sufficiently high, making it difficult to apply to actual processes.

[0008] Therefore, there is a need to develop new inorganic cluster compounds that possess excellent etch resistance and mechanical strength, as well as significantly enhanced EUV sensitivity. The problem to be solved

[0009] One objective of the present invention is to provide a cluster compound having excellent etching resistance and mechanical strength, while also having significantly improved EUV sensitivity.

[0010] Another objective of the present invention is to provide a photoresist composition comprising the cluster compound described above and a method for forming a photoresist pattern using the same. means of solving the problem

[0011] The present invention provides a cluster compound represented by the following chemical formula 1 or a salt thereof.

[0012] [Chemical Formula 1]

[0013] Sn p X q O r (L1) s (L2) t

[0014] In the above Chemical Formula 1, X is a halogen, L1 and L2 are each independently ligands comprising one or more elements selected from nitrogen (N) and oxygen (O) and having at least one lone pair of electrons, and p, q, r, s, and t are 2≤p≤4, 0≤q≤2p, 0 <r≤2p 및 0<s+t≤2p을 만족한다.

[0015] In one embodiment, the cluster compound or its salt may not include a bond between a tin (Sn) atom and a carbon (C) atom.

[0016] In one embodiment, each tin (Sn) atom included in the cluster compound may form a bond with two or more oxygen (O) atoms.

[0017] In one embodiment, q in the above formula 1 may be 0.

[0018] In one embodiment, the tin (Sn) may be derived from a divalent tin (Sn) precursor compound.

[0019] In one embodiment, L1 and L2 may each independently be a C1-20 carboxylic acid compound or a heterocyclic compound containing nitrogen (N).

[0020] In one embodiment, L1 is R1COOH and L2 is R2COOH, R1 and R2 are each independently hydrogen (H), a C1-15 alkyl group, a C6-18 aryl group, or a C2-15 alkenyl group, and p, q, r, s, and t are each 2≤p≤4, 0≤q≤2, 0 <r≤4 및 0<s+t≤4을 만족하는 것일 수 있다.

[0021] In one embodiment, the cluster compound or its salt may have an average particle size of 0.5 nm to 5 nm in an organic solvent.

[0022] In one embodiment, the compound may be used for forming a photoresist pattern.

[0023] In one embodiment, the photoresist pattern may be an EUV photoresist pattern.

[0024] In addition, the present invention provides a photoresist composition comprising a cluster compound or a salt thereof as described above; and a solvent.

[0025] In one embodiment, the cluster compound or its salt may be included in an amount of 0.1% to 20% by weight based on the total weight of the photoresist composition.

[0026] In addition, the present invention provides a method for forming a photoresist pattern comprising: (a) applying a photoresist composition as described above onto a substrate and drying it to form a photoresist film; (b) exposing the photoresist film to an active light; and (c) developing the exposed photoresist film.

[0027] In one embodiment, the active light may be an electron beam or extreme ultraviolet light.

[0028] In one embodiment, the pattern may be a negative type pattern.

[0029] In addition, the present invention provides a semiconductor device comprising a photoresist pattern formed by a photoresist pattern forming method as described above.

[0030] In addition, the present invention provides a thin film transistor comprising: a substrate; and a thin film formed by coating a cluster compound or a salt thereof as described above on the substrate. Effects of the invention

[0031] The cluster compound according to the present invention has excellent etch resistance and mechanical strength, so it can be formed with a very thin thickness even in ultrafine patterns, thereby preventing pattern disintegration problems. In addition, by introducing surface molecules that facilitate bonding and dissociation, the chemical stability of the cluster compound is secured while having significantly improved EUV sensitivity, which has the advantage of being able to form photoresist patterns with excellent sensitivity. Brief explanation of the drawing

[0032] Figures 1 and 2 illustrate the results of analyzing the molecular structure of the cluster compound of Example 1 using field desorption mass spectrometry. Specifically, the blue spectrum is the spectrum of the compound synthesized in Example 1, and the red spectrum is the spectrum of the compound shown in the figure. Figure 3 is a graph of the results obtained by Dynamic Light Scattering (DLS) to analyze the average particle size of the cluster compound of Example 1 in an organic solvent. Figures 4 to 6 illustrate the EUV sensitivity results measured according to Experimental Example 1. Specific details for implementing the invention

[0033] The embodiments described in this specification may be modified in various different forms, and the technology according to one embodiment is not limited to the embodiments described below. Furthermore, the embodiment of one embodiment is provided to more fully explain the present disclosure to those skilled in the art.

[0034] Additionally, the singular form used in the specification and the appended claims may be intended to include the plural form unless specifically indicated otherwise in the context.

[0035] Additionally, the numerical ranges used in this specification include lower and upper limits and all values ​​within the range, increments logically derived from the form and width of the defined range, all of which are limited values, and all possible combinations of upper and lower limits of numerical ranges defined in different forms. Unless otherwise specifically defined in this specification, values ​​outside the numerical range that may occur due to experimental error or rounding are also included in the defined numerical range.

[0036] Furthermore, throughout the specification, the term "comprising" a component means that, unless specifically stated otherwise, it does not exclude other components but rather may include additional components.

[0037] In this specification, when a part such as a layer, film, region, plate, etc. is described as being “on” or “on” another part, this includes not only cases where it is “immediately on” another part, but also cases where there is another part in between.

[0038] Patterns are formed in conventional cluster compounds containing functional groups such as alkyl and allyl groups by linking radicals generated based on Sn-C bond cleavage upon irradiation with low-wavelength (high-energy) light, such as electron beams or EUV. These conventional clusters possess excellent LER characteristics due to their small size, and because they contain atoms with excellent photoionization cross-sections, such as tin, they exhibit superior EUV absorption coefficients and etch resistance compared to existing organic photoresists. However, even the Allyl tin oxo cluster, known to be the most sensitive, has a dose-to-size of 180 mJ / cm² for EUV irradiation. 2 At this level, the EUV sensitivity is not sufficiently high, making it unsuitable for actual use as a photoresist material. This is because, considering that using alkyl groups as capping ligands for inorganic nanoparticles imposes more restrictions on ligand exchange reactions compared to using carboxylates, the bonds between carbon and metal atoms in metal oxo cluster compounds do not easily dissociate during high-energy light irradiation. The undissociated alkyl groups hinder the cross-linking reaction between clusters, preventing the proper formation of patterns.

[0039] The inventor of the present invention synthesized a cluster compound in which a molecule that does not have Sn-C bonds and is easily bonded and dissociated is introduced to the surface of the cluster, and discovered that such a compound possesses significantly enhanced EUV sensitivity while ensuring chemical stability, thereby enabling the formation of photoresist patterns with excellent sensitivity, and thus completed the present invention.

[0040] Specifically, unlike conventional Allyl tin oxo clusters, the cluster compound according to one embodiment does not have Sn-C bonds and introduces specific ligand molecules that are easy to bond and dissociate onto the surface, thereby allowing the dissociable electron attachment reaction upon exposure to proceed faster than that of conventional Allyl tin oxo clusters. Accordingly, the ligand molecules are removed more easily, thereby promoting the cross-linking reaction between clusters and having the advantage of forming a photoresist pattern with excellent sensitivity.

[0041] In addition, the cluster compound according to one embodiment contains 2 to 4 tin atoms, thereby miniaturizing the size of the cluster and enabling improved LER performance.

[0042] A cluster compound according to one embodiment comprises 2-4 tin (Sn) atoms, includes -O- as a bridging ligand, includes a coordination bond formed between a nitrogen (N) or oxygen (O) atom included in L1 and L2 and a tin (Sn) atom, and has a cluster structure that may additionally include an MX bond.

[0043] The present invention provides a cluster compound or a salt thereof, wherein the cluster compound is characterized by being represented by the following chemical formula 1.

[0044] [Chemical Formula 1]

[0045] Sn p X q O r (L1) s (L2) t

[0046] In the above Chemical Formula 1, X is a halogen, L1 and L2 are each independently ligands comprising one or more elements selected from nitrogen (N) and oxygen (O) and having at least one lone pair of electrons, and p, q, r, s, and t are 2≤p≤4, 0≤q≤2p, 0 <r≤2p 및 0<s+t≤2p을 만족한다.

[0047] In one embodiment, the cluster compound may not contain a bond between a tin (Sn) atom and a carbon (C) atom, and accordingly, a surface molecule that facilitates bonding and dissociation is introduced, enabling pattern formation with significantly superior stability as well as sensitivity. Specifically, since it does not contain a bond between a tin (Sn) atom and a carbon (C) atom, it has the advantage of being able to form a robust photoresist pattern even at low light levels.

[0048] In one embodiment, each tin (Sn) atom included in the cluster compound may form a bond with two or more oxygen (O) atoms, specifically with two to four, and more specifically with three to four oxygen (O) atoms. Accordingly, a cluster compound having excellent chemical stability and EUV sensitivity can be provided.

[0049] In one embodiment, the above q may be 0. That is, the cluster compound according to one embodiment may not contain a bond between a tin (Sn) atom and a halogen (X) atom, and accordingly, HX gas is not generated during the photoresist pattern formation process, thereby suppressing damage to the device used during photoresist pattern formation.

[0050] In one embodiment, the tin (Sn) may be derived from a divalent tin (Sn) precursor compound. The tin derived from a divalent tin (Sn) precursor compound is preferred because it has lower stability compared to that derived from a tetravalent tin (Sn) precursor compound, allowing for more effective pattern formation when used as a photoresist. Additionally, using a divalent tin precursor (SnCl2·2H2O), which has fewer water molecules coordinated to tin than a tetravalent tin precursor (SnCl4·5H2O), can reduce the size of the cluster compound, which can improve LER performance.

[0051] In one embodiment, L1 and L2 may each independently be a C1-20 carboxylic acid compound or a heterocyclic compound containing nitrogen (N). For example, the C1-20 carboxylic acid compound may be RCOOH (where R is hydrogen (H), a C1-19 alkyl group, a C6-18 aryl group, or a C2-19 alkenyl group). As an example, L1 and L2 may each independently be formic acid, acetic acid, benzoic acid, pyrazole, pyridine, or imidazole, but are not necessarily limited thereto.

[0052] Specifically, L1 is R1COOH and L2 is R2COOH, where R1 and R2 are each independently hydrogen (H), a C1-15 alkyl group, a C6-18 aryl group, or a C2-15 alkenyl group, and p, q, r, s, and t are each 2≤p≤4, 0≤q≤2, 0 <r≤4 및 0<s+t≤4을 만족할 수 있다. 구체적으로 상기 R1및 R2는 각각 독립적으로 수소(H), C1-10 알킬기, C6-10 아릴기 또는 C2-10 알케닐기일 수 있으며, 보다 구체적으로 수소(H) 또는 C1-5 알킬기, 보다 더 구체적으로 수소(H) 또는 C1-3 알킬기일 수 있다. 또한, p, q, r, s 및 t는 구체적으로 각각 2≤p≤3, q=0, 0<r≤3 및 0<s+t≤3을 만족할 수 있다.

[0053] For example, a cluster compound according to one embodiment may be represented by the chemical formula Sn3O2(HCOOH)3 or Sn2O2(HCOOH)2.

[0054] In one embodiment, the cluster compound may have an average particle size of 0.5 nm to 5 nm in an organic solvent, specifically 0.5 nm to 3 nm, more specifically 1.0 nm to 2.5 nm, and more specifically 1.5 nm to 2.4 nm. At this time, the organic solvent may be, for example, one or more selected from formic acid, acetic acid, 2-methoxyethanol, methyl isobutyl carbinol, ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl acetate, ethyl lactate, and mixtures thereof, and preferably acetic acid.

[0055] When a photoresist pattern is formed using a cluster compound whose average particle size in an organic solvent satisfies the aforementioned range, the distinction between the exposed and unexposed regions can be made clearer, which has the advantage of enabling the formation of a photoresist pattern with improved half pitch and LER.

[0056] The above-described cluster compound has the characteristic that, as molecules on the surface of the cluster compound dissociate upon exposure and crosslinks are formed between clusters, a difference in solubility in the developer solution appears depending on the presence or absence of exposure. Therefore, it may be used for forming a photoresist pattern, and specifically, the photoresist pattern may be an EUV photoresist pattern. As described above, the compound has the advantage of being able to form a photoresist pattern with excellent sensitivity by introducing surface molecules that facilitate bonding and dissociation to secure the chemical stability of the cluster compound while possessing significantly enhanced EUV sensitivity. Furthermore, as the compound is an inorganic material, when used as a photoresist, it has excellent etching resistance and mechanical strength, allowing it to be formed with a very thin thickness even in ultrafine patterns, thereby preventing pattern disintegration problems.

[0057] The present invention provides a photoresist composition comprising a cluster compound or a salt thereof as described above; and a solvent; wherein the photoresist composition has the advantage of being able to prevent pattern disruption problems and form a photoresist pattern with excellent sensitivity by including a cluster compound having excellent etching resistance and mechanical strength while having significantly improved EUV sensitivity.

[0058] In the above photoresist composition, the solvent may be one or more selected from formic acid, acetic acid, 2-methoxyethanol, methyl isobutyl carbinol, ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl acetate, ethyl lactate, and mixtures thereof.

[0059] In one embodiment, the cluster compound or its salt may be included in an amount of 0.1% to 20% by weight based on the total weight of the photoresist composition, specifically 1% to 10% by weight, and more specifically 1% to 5% by weight.

[0060] A method for forming a photoresist pattern according to the present invention may include: (a) a step of forming a photoresist film by applying the above-described photoresist composition on a substrate and drying it; (b) a step of exposing the photoresist film to an active light; and (c) a step of developing the exposed photoresist film.

[0061] For the formation of a photoresist film, the photoresist composition may be applied to a substrate using any method known in the art without limitation, such as spin coating, dipping, roller coating, bar coating, spray coating, inkjet printing, screen printing, etc., but is not limited thereto.

[0062] For example, a photoresist composition can be applied to a substrate by a spin coating method, and the thickness of the desired photoresist film can be controlled based on the speed of the spinner and the time of the coating. For example, spin coating can be performed at a speed of 1000 rpm to 5000 rpm, specifically 2000 rpm to 4000 rpm, for 10 seconds to 60 seconds, specifically 20 seconds to 40 seconds, but is not limited thereto.

[0063] In one embodiment, a post-apply bake (PAB) process step for baking the photoresist film prior to step (b) may be further included, and the PAB process can improve adhesion between the photoresist film and the substrate by removing the solvent contained in the photoresist composition. As an example, the PAB process may be performed at a temperature of 80°C to 200°C, specifically 90°C to 150°C, for 0.1 to 10 minutes, specifically 0.5 to 5 minutes, but is not limited thereto, and the process conditions may be changed depending on the solvent used.

[0064] In one embodiment, the thickness of the photoresist film formed on the substrate may be 1 nm to 100 nm, specifically 1 nm to 50 nm, more specifically 10 nm to 50 nm. At this time, the thickness of the photoresist film may be the thickness measured after performing a PAB process after applying a photoresist composition to the substrate.

[0065] As the photoresist film is formed from cluster compounds with etch resistance and mechanical strength, pattern disruption does not occur even under the thickness range described above, and a photoresist pattern can be formed with excellent resolution and sensitivity.

[0066] The photoresist film may be a positive type that becomes soluble to the developer when exposed to light used in the photolithography process described later, or a negative type that becomes insoluble to the developer; specifically, it may be a negative type. That is, depending on the solubility of the photoresist film with respect to the developer, the pattern formed by the photoresist pattern formation method may be a positive type or a negative type pattern; specifically, it may be a negative type pattern.

[0067] A substrate on which a photoresist composition is applied may comprise one or more conductive layers selected from aluminum, copper, molybdenum, titanium, tungsten, alloys of these metals, nitrides of these metals, or silicides of these metals, one or more dielectric layers selected from silicon oxide, silicon nitride, silicon oxynitride, and metal oxide, a semiconductor layer such as single-crystal silicon, and combinations thereof, located on a lower base substrate. Here, the lower base substrate may be in the form of a wafer or a film, and may be a laminate in which two or more materials selected from semiconductors, ceramics, metals, polymers, or the like are stacked to form each layer.

[0068] For example, the lower base substrate may be a semiconductor substrate, and as a non-limiting example of a semiconductor substrate, it may be a group 4 semiconductor including silicon (Si), germanium (Ge) or silicon germanium (SiGe), a group 3-5 semiconductor including gallium arsenide (GaAs), indium phosphide (InP) or gallium phosphide (GaP), a group 2-6 semiconductor including cadmium sulfide (CdS) or zinc telluride (ZnTe), a group 4-6 semiconductor including lead sulfide (PbS), or a laminate in which two or more materials selected from these form each layer.

[0069] In one embodiment, step (b) is a step of exposing a photoresist film to an active light, wherein the active light may be one or more selected from electron beam (E-beam), extreme ultraviolet (EUV), eye-line, krypton fluoride (KrF) laser, argon fluoride (ArF) laser, deep ultraviolet (DUV), vacuum ultraviolet (VUV), X-ray, and ion beam, and specifically may be an electron beam (E-beam) or extreme ultraviolet (EUV).

[0070] In one embodiment, a post-exposure bake (PEB) process step for baking the exposed photoresist film after step (b) may be further included, and the PEB process may further increase the difference in solubility of the developer between the exposed area and the unexposed area. As an example, the PEB process may be performed at a temperature of 80°C to 200°C, specifically 90°C to 150°C, for 0.1 to 10 minutes, specifically 0.5 to 5 minutes, but is not limited thereto.

[0071] Step (c) above is a step of developing the exposed photoresist film, and specifically, the development may be performed using a developer comprising one or more combinations selected from the group consisting of quaternary ammonium salts, alcohols, ketones, and distilled water. Specific examples of the quaternary ammonium salt may be tetramethylammonium hydroxide (TMAH), tetrabutylammonium hydroxide (TBAH), tetrapropylammonium hydroxide (TPAH), tetraethylammonium hydroxide (TEAH), or a mixture thereof. As an example, the developer may contain 0.01 to 10 weight%, specifically 0.01 to 5 weight% of quaternary ammonium salt.

[0072] The present invention provides a semiconductor device comprising a photoresist pattern formed by the above-described photoresist pattern forming method. Since the semiconductor device comprises a photoresist pattern formed by the above-described method with excellent resolution, LER, and sensitivity, it can achieve superior performance and has the advantage of not damaging the underlying layer during device fabrication.

[0073] In addition, the present invention provides a thin-film transistor comprising: a substrate; and a thin film formed by coating the aforementioned cluster compound or a salt thereof on the substrate. The thin-film transistor can achieve superior performance by including a thin film having excellent electrical conductivity, wherein the cross-linking reaction between the cluster compounds is effectively carried out during thermal curing or light irradiation.

[0074] Specifically, the thin film transistor may be manufactured by the steps of: applying a thin film forming solution, which is a mixture of a cluster compound or a salt thereof and a solvent according to one embodiment, onto a substrate; and heat-treating the substrate on which the thin film forming solution is applied.

[0075] In a thin film transistor according to one embodiment, the solvent may be one or more selected from formic acid, acetic acid, 2-methoxyethanol, methyl isobutyl carbinol, ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl acetate, ethyl lactate, and mixtures thereof, and preferably may be formic acid or acetic acid.

[0076] In a thin film transistor according to one embodiment, for the formation of a thin film, a cluster compound or a salt thereof may be applied to a substrate using any method known in the art without limitation, and for example, may be applied using methods such as spin coating, dipping, roller coating, bar coating, spray coating, inkjet printing, screen printing, etc., but is not limited thereto.

[0077] In a thin film transistor according to one embodiment, the substrate can be the same as the substrate used in the photoresist pattern formation method described above.

[0078] In a thin film transistor according to one embodiment, the heat treatment may be performed at a temperature of 300°C to 500°C, specifically 300°C to 400°C for 1 hour to 10 hours, specifically 2 hours to 5 hours, but is not limited thereto.

[0079] The thin-film transistor described above may further include a gate electrode, a gate insulating film, a source electrode, a drain electrode, an organic interlayer insulating film, etc., and each component may be arranged as known to those skilled in the art. For example, a thin film formed on a substrate may include a channel region and a conductive region, a gate insulating film may be formed on the channel region of the thin film, a gate electrode may be formed on the gate insulating film, an organic interlayer insulating film may be formed to cover the gate electrode and the thin film, and a source electrode and a drain electrode may be formed on the organic interlayer insulating film and arranged to be electrically connected to the conductive region of the thin film.

[0080] Examples and experimental examples are described below with specific examples. However, the examples and experimental examples described below are merely illustrative of some aspects, and the technology described in this specification is not limited thereto.

[0081] <Example 1>

[0082] 0.9 g of Tin(II) chloride dehydrate, 20 ml of methanol, and 5 ml of ammonia water were added to a 40 ml vial and stirred for 10 minutes. Subsequently, the solvent was removed by centrifugation at 12,000 rpm for 10 minutes, and the mixture was washed three times with methanol to obtain a solid reaction product. Next, the solid reaction product, 16 ml of methanol, and 17 ml of formic acid were added sequentially to a flask, heated to 70 °C, and stirred for 1 hour. Afterward, the solvent was completely removed using a centrifuge to prepare a cluster compound in a white solid state.

[0083] The molecular structure of the cluster compound prepared above was analyzed using field desorption mass spectrometry, and the results are shown in Figures 1 and 2. The sample for field desorption mass spectrometry was prepared by dissolving the cluster compound in a formic acid solvent at a concentration of 2.5 wt% and then filtering it through a PTFE syringe filter. As shown in Figures 1 and 2, it can be seen that the structure of the cluster compound matches that of the cluster compounds represented by the chemical formulas Sn3O2(HCOOH)3 and Sn2O2(HCOOH)2. Through this, it was confirmed that the cluster compound has a tin cluster form in which oxygen atoms form crosslinks between tin atoms, and possesses a coordination bond formed between the oxygen atoms of formic acid and the tin atoms.

[0084] In addition, the average particle size of the cluster compound prepared above in an organic solvent was measured using Dynamic Light Scattering (DLS), and the results are shown in Fig. 3. Specifically, the solution for DLS analysis was prepared by dissolving the cluster compound in an acetic acid solvent at a concentration of 2.5 wt%. Referring to Fig. 3, the cluster compound has an average particle size of 2.1 nm in the organic solvent and a mode of 1.7 nm.

[0085] <Example 2>

[0086] A p-type silicon wafer with a 100 nm thick thermal oxide film (SiO2) deposited on it was cut into a 1.5 cm × 1.5 cm size, sonicated with acetone for 20 minutes, and washed to prepare a SiO2 / Si substrate. A coating solution was prepared by dissolving the cluster compound prepared in Example 1 in a formic acid solvent at a concentration of 2.5 wt%. The coating solution was applied to the prepared SiO2 / Si substrate. A thin film was formed by spin-coating at 3,000 rpm / 30 seconds.

[0087] <Experimental Example 1> EUV Sensitivity Analysis

[0088] EUV sensitivity was measured at the Pohang Accelerator Laboratory using the thin film prepared in Example 2, and the results are shown in Figures 4 to 6. Specifically, the thin film prepared in Example 2 was exposed to EUV. Subsequently, it was developed for 10 minutes using a tetramethylammonium hydroxide (TMAH, 25 wt%) solution. Figure 4 is a fluorescence microscope image measured before development after exposure to light intensity of 100 and 200 mJ / cm², Figure 5 is a fluorescence microscope image measured after exposure to light intensity of 100 mJ / cm² and development, and Figure 6 is a fluorescence microscope image measured after exposure to light intensity of 200 mJ / cm² and development. Referring to this, a pattern is formed not only at 200 mJ / cm² but also at 100 mJ / cm² of light intensity, so the cluster compound according to one embodiment has the advantage of being able to form a robust photoresist pattern even at low light intensity.

[0089] As described above, the present disclosure has been explained by specific details and limited embodiments in this specification; however, this is provided merely to aid in a more comprehensive understanding of the present disclosure, and the present disclosure is not limited to the above embodiments. A person skilled in the art to which the present disclosure pertains can make various modifications and variations from this description.

Claims

Claim 1 Cluster compound represented by the following chemical formula 1 or a salt thereof: [Chemical Formula 1]Sn p X q O r (L1) s (L2) t In the above chemical formula 1, X is a halogen, L1 and L2 are ligands, each independently a C1-20 carboxylic acid compound or a heterocyclic compound containing nitrogen (N), and p, q, r, s, and t are 2≤p≤4, 0≤q≤2p, 0 <r≤2p 및 0<s+t≤2p을 만족한다. Claim 2 In claim 1, a cluster compound or a salt thereof that does not include a bond between a tin (Sn) atom and a carbon (C) atom. Claim 3 A cluster compound or a salt thereof, wherein each tin (Sn) atom included in the cluster compound forms a bond with two or more oxygen (O) atoms. Claim 4 A cluster compound or a salt thereof, wherein q is 0 in claim 1. Claim 5 In claim 1, the cluster compound or salt thereof, wherein the tin (Sn) is derived from a divalent tin (Sn) precursor compound. Claim 6 In claim 1, L1 is R1COOH and L2 is R2COOH, R1 and R2 are each independently hydrogen (H), a C1-15 alkyl group, a C6-18 aryl group, or a C2-15 alkenyl group, and p, q, r, s, and t are each 2≤p≤4, 0≤q≤2, 0 <r≤4 및 0<s+t≤4을 만족하는, 클러스터 화합물 또는 이의 염. Claim 7 In claim 1, L1 and L2 are each independently cluster compounds or salts thereof, which are formic acid, acetic acid, benzoic acid, pyrazole, pyridine, or imidazole. Claim 8 In claim 1, a cluster compound or a salt thereof having an average particle size of 0.5 nm to 5 nm in an organic solvent. Claim 9 In claim 1, the compound is a cluster compound or a salt thereof that is used for forming a photoresist pattern. Claim 10 In claim 9, the above photoresist pattern is a cluster compound or a salt thereof, which is an EUV photoresist pattern. Claim 11 A photoresist composition comprising: a cluster compound or a salt thereof selected from any one of claims 1 to 10; and a solvent. Claim 12 A photoresist composition according to claim 11, wherein the cluster compound or salt thereof is included in an amount of 0.1% to 20% by weight based on the total weight of the photoresist composition. Claim 13 (a) a step of applying the photoresist composition of claim 11 onto a substrate and drying it to form a photoresist film; (b) a step of exposing the photoresist film to an active light; and (c) a step of developing the exposed photoresist film; comprising a method for forming a photoresist pattern. Claim 14 A method for forming a photoresist pattern according to claim 13, wherein the active light is an electron beam or extreme ultraviolet light. Claim 15 In paragraph 13, a method for forming a photoresist pattern, wherein the above pattern is a negative type pattern. Claim 16 A semiconductor device comprising a photoresist pattern formed by the photoresist pattern forming method of claim 13. Claim 17 A thin film transistor comprising: a substrate; and a thin film formed by applying a cluster compound of any one of claims 1 to 10 or a salt thereof on the substrate.

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