Zinc-titanium composite clusters, synthesis method thereof and lithographic patterning application

Abstract

The application discloses a zinc-titanium composite cluster, a synthesis method thereof and a lithographic patterning application, and relates to a zinc-titanium composite cluster with a general formula I structure, which has the characteristics of high thermal stability, small particle size, uniform distribution, high sensitivity and high resolution. The synthesis method comprises the following steps: dissolving benzoic acid with a R1 substituent group in anhydrous organic solvent, adding a mixture of titanium isopropoxide and zinc acetate, and then washing, filtering and vacuum drying the crystal precipitate after standing to obtain a pure solid product. The zinc-titanium composite cluster is used as a photosensitizer and resin in extreme ultraviolet lithography and electron beam lithography, has excellent high sensitivity and high resolution, and is suitable for the fields of semiconductor manufacturing, nanotechnology and optical element manufacturing. The zinc-titanium composite cluster also has excellent thermal stability and chemical stability, so that the application of the zinc-titanium composite cluster in various extreme environments is possible.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fine chemical industry, and particularly relates to a zinc-titanium composite cluster and synthesis and application thereof. BACKGROUND

[0002] With the rise of artificial intelligence and other fields, the demand for computer computing power in various industries is increasing day by day, which undoubtedly puts higher requirements on the semiconductor industry. As a key link in the production of semiconductor chips, photolithography plays a decisive role in the performance of chips. In the process of exposure, ultraviolet light will pass through a specific pattern of a photomask to irradiate the surface of a silicon wafer coated with a photoresist film. After irradiation, the photoresist will undergo a photochemical reaction. According to the different solubility changes before and after exposure, the photoresist can be divided into positive photoresist and negative photoresist. The positive photoresist refers to the part irradiated by ultraviolet light after exposure, which increases in solubility during the development process, and vice versa for the negative photoresist. Through the change of solubility, a specific pattern is transferred to the photoresist layer, and then the pattern is finally transferred to the surface of the silicon wafer through etching and stripping processes.

[0003] In order to meet the growing demand for computing power, the photolithography process in the semiconductor industry is also constantly iterating. According to the Rayleigh formula CD=k1λ / NA, under the condition that the numerical aperture (NA) of the photolithography machine and the process parameters (k1) are constant, the most effective way to reduce the critical dimension (CD) and improve the integration is to reduce the wavelength of the incident light during exposure. Therefore, the wavelength of the light source of the photolithography machine has also undergone a change from 436nm-365nm-248nm-193nm-13.5nm. The current wavelength of 13.5nm extreme ultraviolet (EUV) has been widely used in industrial production and has become the mainstream of developing 3nm and below process.

[0004] Due to the sharp shortening of the wavelength of the light source, the energy carried by a single photon is also greatly increased to 92eV, which makes the photon density of EUV lower under the same dose. At the same time, due to the easy absorption of EVU light, even though the photolithography machine of ASML has been improved from the traditional lens light path to the mirror light path, the EUV efficiency that can finally reach the photoresist film layer is still not high. Therefore, in order to maximize the use of the light source and reduce production costs, a series of metal elements with high EUV absorption have been introduced into the EUV photoresist in recent years, such as metal nanoparticle photoresist, metal complex photoresist, metal oxygen cluster photoresist, and metal modified polymer photoresist.

[0005] Currently, there is only one published literature on zinc-titanium complex cluster photoresist, which is my previous article (https: / / doi.org / 10.1016 / j.cej.2024.152315). The design idea of this literature is to regulate the core of the cluster with the same ligand (methyl methacrylate). However, this photoresist still has many challenges in terms of lithographic sensitivity, pattern roughness, and resolution in practical applications.

[0006] The existing zinc-titanium complex cluster photoresist requires a high EUV light dose (30 mJ / cm 2 ) to achieve patterning, which not only increases the manufacturing cost but also may affect the stability of the photoresist and the quality of the pattern.

[0007] Currently, only one zinc-titanium complex cluster photoresist with methyl methacrylate as the ligand has been synthesized. However, there is a lack of systematic study on the influence of different ligand types on the performance of the photoresist (such as sensitivity, pattern roughness, and resolution), which leads to an incomplete understanding of the structure-activity relationship and exposure mechanism of the photoresist. Therefore, further in-depth exploration is urgently needed.

[0008] Under the existing technical conditions, the resolution and etch resistance of the EUV photoresist in the patterning process still need to be improved, especially in the application scenarios that pursue smaller feature sizes (such as 8 nm and below). These defects have become a bottleneck limiting the development of EUV lithography.

[0009] Due to the various problems existing in the prior art, it is necessary for technical personnel in the field to improve. Therefore, solving the above problems has important significance for promoting the development of EUV lithography technology. SUMMARY

[0010] To overcome the defects of insufficient patterning resolution and poor etch resistance of the EUV photoresist in the prior art, the present application changes the electronic orbital distribution of the cluster by regulating the type of ligand, thereby achieving precise control of the photosensitivity of the zinc-titanium complex cluster. This application aims to provide a more efficient and stable lithography solution to meet the demand for higher integration of chip manufacturing in the semiconductor industry.

[0011] To achieve the above purpose, the technical solution of the present application is as follows: a type of zinc-titanium complex cluster, which has the following general formula I structure:

[0012]

[0013] In general formula I,

[0014] R1is selected from the group consisting of alkyl having 0-18 carbons, alkenyl having 2-18 carbons, alkynyl having 2-18 carbons, cycloalkyl having 3-20 carbons, heterocycloalkyl having 3-20 carbons, halogen, nitro, cycloalkenyl having 3-20 carbons, or aryl having 6-20 carbons, wherein the aryl group contains at least one or no substituents selected from the group consisting of halogen, nitro, sulfonic acid, alkyl having 1-10 carbons, alkenyl having 2-18 carbons, alkynyl having 2-18 carbons, fluoroalkyl having 1-10 carbons.

[0015] In a further preferred embodiment, R1is selected from the group consisting of alkyl having 0-8 carbons, alkenyl having 2-8 carbons, alkynyl having 2-8 carbons, cycloalkyl having 3-12 carbons, halogen, nitro, or aryl having 6-12 carbons, wherein the aryl group contains at least one or no substituents selected from the group consisting of halogen, nitro, alkyl having 1-8 carbons, alkenyl having 2-8 carbons.

[0016] In a further preferred embodiment, R1is selected from the group consisting of alkyl having 0-8 carbons, alkenyl having 2-8 carbons, alkynyl having 2-8 carbons, cycloalkyl having 3-12 carbons, halogen, nitro, or aryl having 6-12 carbons, wherein the aryl group contains at least one or no substituents selected from the group consisting of halogen, nitro, alkyl having 1-8 carbons, alkenyl having 2-8 carbons.

[0017] The present application provides a method for synthesizing a zinc-titanium complex cluster having the structure of the above general formula I:

[0018] The synthesis comprises dissolving benzoic acid with R1substituent modification in anhydrous organic solvent, adding the dissolved organic acid solution to a mixture of titanium isopropoxide: zinc acetate with a molar ratio of 1-5: 1-5, completely dissolving, and placing the obtained solution under closed conditions at 25-60°C for 7-30d, after the crystal precipitate is generated, the obtained solid product is washed, suction filtered, and vacuum dried to obtain pure solid product.

[0019] The reaction formula is as follows:

[0020]

[0021] Further, the molar ratio of benzoic acid with R1substituent modification to titanium isopropoxide is 1-15: 1, and the further preferred molar ratio range is 5-10: 1.

[0022] Further, the molar ratio of benzoic acid with R1substituent modification to titanium isopropoxide is 1-15: 1, and the further preferred molar ratio range is 5-10: 1.

[0023] Further, the organic solvent is selected from one of the following mixed solutions: a mixed solution of isopropyl alcohol and dichloromethane with a molar ratio of 1-5:1-5, a mixed solution of isopropyl alcohol and tetrahydrofuran with a molar ratio of 1-8:1-5, a mixed solution of isopropyl alcohol and dichloromethane with a molar ratio of 8-15:1-5, a mixed solution of tetrahydrofuran and dichloromethane with a molar ratio of 5-10:1-5; further preferably, the organic solvent is selected from one of the following mixed solutions: a mixed solution of isopropyl alcohol and dichloromethane with a molar ratio of 1:1, a mixed solution of isopropyl alcohol and tetrahydrofuran with a molar ratio of 2:1, a mixed solution of isopropyl alcohol and dichloromethane with a molar ratio of 10:1, and a mixed solution of tetrahydrofuran and dichloromethane with a molar ratio of 6:1.

[0024] The zinc-titanium composite cluster is expected to be applied in the following fields:

[0025] Semiconductor manufacturing industry: In the extreme ultraviolet lithography technology, the photoresist of the application can be used to manufacture semiconductor chips with higher integration, and promote the development of next-generation high-performance computing devices.

[0026] Nanotechnology field: Due to its high resolution characteristics, the photoresist is also suitable for precision manufacturing at the nanoscale, such as nanosensors, nanoelectronics devices, etc.

[0027] Optical element manufacturing: In the microstructure processing of optical elements, high-sensitivity and high-resolution photoresists can be used to manufacture complex optical components, such as high-precision lenses, fiber connectors, etc.

[0028] In a further preferred case, the zinc-titanium composite cluster is used in extreme ultraviolet lithography and electron beam lithography as a photosensitizer and resin in the photoresist formulation.

[0029] Further, the photoresist is prepared by adding chloroform to the zinc-titanium composite cluster, ultrasonic treatment for 10 minutes, and then filtering to obtain a photoresist solution.

[0030] Further, the zinc-titanium composite cluster is used as a photosensitizer and resin in the electron beam photoresist formulation, and can complete the patterning of 8nm-25nm line width lines in electron beam lithography with high sensitivity.

[0031] Further, the zinc-titanium composite cluster is used as a photosensitizer and resin in the extreme ultraviolet photoresist formulation, and can complete the patterning of 75nm-300nm periodic lines in extreme ultraviolet lithography exposure, and the further preferred period is 75nm.

[0032] In summary, the application has the following beneficial effects:

[0033] 1. Since the aromatic carboxylic acid has a higher boiling point, it has higher thermal stability than the clusters with methacrylic acid as ligand disclosed in the prior art, which is more advantageous for long-term storage of photoresist.

[0034] 2. The particle size of the zinc-titanium composite cluster described in the present application is about 2 nm, which is smaller and more uniform than that of the traditional CAR photoresist. At the same time, since no additives such as photoacid are added during the lithography process, on the one hand, the post-exposure bake (PEB) process can be omitted after exposure, reducing production costs, on the other hand, resolution degradation due to acid diffusion does not occur during the exposure process. For example, Example 1 shows that the line width of the line formed at a period of 70 nm is about 9.6 nm, which has reached the advanced level in the current industry.

[0035] 3. In the present application, by introducing aromatic carboxylic acid with electron-donating group into the cluster, the HOMO energy level of the cluster is improved, which on the one hand reduces the vertical ionization potential (VIP) of the cluster, increases the photoelectrons and secondary electrons generated during the exposure process, and improves the exposure sensitivity, on the other hand, also reduces the dissociation energy of the ligand, which is also beneficial to the improvement of the sensitivity of the cluster. Especially in Example 3, when 32wt% and 48wt% of hydroquinone (HQ) are added, the sensitivity of the photoresist reaches 36μC / cm 2 and 62μC / cm 2 , respectively, which is much higher than that of other examples without HQ, which shows that the sensitivity of the photoresist can be significantly improved by properly adjusting the ligand.

[0036] 4. The zinc-titanium composite cluster provided by the present application is applied to extreme ultraviolet lithography and electron beam lithography, such as zinc-titanium composite cluster containing carboxylic acid ligand of preferably p-vinylbenzoic acid. During the exposure process, in addition to the electron-donating effect of the vinyl group improving the HOMO energy level of the cluster, the synergistic effect of the two makes the zinc-titanium composite cluster have great improvement in sensitivity.

[0037] 5. In EUV lithography, Example 3 containing 32wt% HQ can complete exposure at an exposure dose of only 25mJ / cm 2 , which greatly reduces the required exposure energy compared to traditional materials, helping to improve production efficiency and reduce costs.

[0038] 6. By introducing different types of ligands (such as electron-donating or electron-withdrawing groups), the electronic orbit of the photoresist can be effectively regulated, and then the photosensitivity is controlled, realizing the fine adjustment of the lithography effect. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort based on these drawings.

[0040] Figure 1 The crystal structure of the compound prepared in Embodiment 1 of the present application shows that the synthesized cluster is the expected structure;

[0041] Figure 2 The nuclear magnetic hydrogen spectrum of the compound prepared in Embodiment 1 of the present application shows that the synthesized structure is accurate;

[0042] Figure 3 The crystal structure of the compound prepared in Embodiment 2 of the present application shows that the synthesized cluster is the expected structure;

[0043] Figure 4 The nuclear magnetic hydrogen spectrum of the compound prepared in Embodiment 2 of the present application shows that the synthesized structure is accurate;

[0044] Figure 5 The crystal structure of the compound prepared in Embodiment 3 of the present application shows that the synthesized cluster is the expected structure;

[0045] Figure 6 The nuclear magnetic hydrogen spectrum of the compound prepared in Embodiment 3 of the present application shows that the synthesized structure is accurate;

[0046] Figure 7 The crystal structure of the compound prepared in Embodiment 4 of the present application shows that the synthesized cluster is the expected structure;

[0047] Figure 8 The nuclear magnetic hydrogen spectrum of the compound prepared in Embodiment 4 of the present application shows that the synthesized structure is accurate;

[0048] Figure 9 The nuclear magnetic fluorine spectrum of the compound prepared in Embodiment 4 of the present application shows that the synthesized structure is accurate;

[0049] Figure 10 The crystal structure of the compound prepared in Embodiment 5 of the present application shows that the synthesized cluster is the expected structure;

[0050] Figure 11 The nuclear magnetic hydrogen spectrum of the compound prepared in Embodiment 5 of the present application shows that the synthesized structure is accurate;

[0051] Figure 12 The crystal structure of the compound prepared in Embodiment 6 of the present application shows that the synthesized cluster is the expected structure;

[0052] Figure 13 AFM images of the re-prepared thin film of the compound prepared in Example 1, 2, 4 under EBL, which shows that the zinc-titanium complex cluster can react under EBL to obtain a pattern;

[0053] Figure 14 AFM images of the re-prepared thin film of the mixture prepared by co-disposing Example 3 and 32wt% / 48wt% hydroquinone under EBL, which shows that Example 3 containing different concentrations of radical inhibitors can react under EBL to obtain a pattern;

[0054] Figure 15 The contrast curve of the re-prepared thin film of the compound prepared in Example 1, 2, 4 under EBL, which shows that the exposure sensitivity of the zinc-titanium complex cluster decreases with the introduction of the electron-withdrawing group;

[0055] Figure 16 The contrast curve of the re-prepared thin film of the mixture prepared by co-disposing Example 3 and 32wt% / 48wt% hydroquinone under EBL, which shows that the sensitivity of Example 3 decreases with the increase of the concentration of the radical inhibitor;

[0056] Figure 17 SEM images of the periodic lines formed by the re-prepared thin film of the compound prepared in Example 1, 2, 4, 6 under EBL, which shows that the zinc-titanium complex cluster can obtain a high-resolution image under EBL;

[0057] Figure 18 SEM images of the periodic lines formed by the re-prepared thin film of the mixture prepared by co-disposing Example 3 and 32wt% / 48wt% hydroquinone under EBL, which shows that Example 3 containing different concentrations of radical inhibitors can obtain a high-resolution image under EBL;

[0058] Figure 19 SEM and AFM images of the periodic lines formed by the re-prepared thin film of the solution prepared by Example 1 and Example 3 and 32wt% hydroquinone under different EUVL doses, which shows that the zinc-titanium complex cluster can react under EUV to obtain a high-resolution pattern, and the electron- donating olefin group can greatly improve the sensitivity of the zinc-titanium complex cluster under extreme ultraviolet; DETAILED DESCRIPTION

[0059] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0060] Example 1

[0061]

[0062] 0.681 g of p-toluic acid was dissolved in a mixed solution of 2 mL isopropanol and 2 mL dichloromethane. Separately, a 20 mL glass sample vial was prepared, into which 0.284 g of titanium isopropoxide and 0.184 g of zinc acetate were added. Finally, the organic solution of the acid was added, and the vial was sealed. The solution was dissolved by sonication for 20 min. After complete dissolution, the vial was allowed to stand at room temperature for 7 days. Colorless crystals formed at the bottom of the vial. The mother liquor was poured off, and the vial was washed three times with anhydrous n-heptane. The resulting solid was placed in a vacuum drying oven and dried under vacuum at 45 °C for 48 hours to obtain the dried solid product.

[0063] Crystal structure see Figure 1 . Figure 1 The crystal structure of the compound prepared in Example 1 of this invention is shown, illustrating that the synthesized cluster has the expected structure;

[0064] Crystal data: Space Group: C2 / c, Cell: a = 22.2623(6)b = 22.2623(6)c =

[0065] 23.5196(7), alpha=90beta=93.0620(10)gamma=90.

[0066] 1 HNMR (400MHz, DMSO-d6, ppm): δ = 7.83 (d, J = 7.8Hz, 20H), 7.24 (d, J = 7.8Hz, 20H), 3.77 (s, 2H), 2.35 (s, 30H), 1.04 (d, J = 6.1Hz, 12H). See for details Figure 2 .

[0067] Figure 2 The above is the 1H NMR spectrum of the compound prepared in Example 1 of this invention, demonstrating the accuracy of the synthesized structure; Example 2

[0068]

[0069] A 20 mL glass vial was charged with 0.284 g of titanium isopropoxide and 0.184 g of zinc acetate. The acid solution was added to the vial and the vial was sealed. The solution was sonicated for 20 min, and then allowed to stand at room temperature for 7 d. The mother liquor was decanted and the solid was washed with anhydrous n-heptane three times. The solid was placed in a vacuum oven and dried at 45 °C for 48 h to give the dried solid product.

[0070] The crystal structure of the compound prepared in Example 2 of the present invention is shown below, which illustrates that the synthesized cluster is the expected structure. Figure 3 . Figure 3 The crystal structure of the compound prepared in Example 2 of the present invention is shown below, which illustrates that the synthesized cluster is the expected structure.

[0071] Crystal data: Space Group: P-1, Cell: a = 13.0090(7) b = 13.6517(8) c = 13.7854(7), alpha = 92.897(2) beta = 116.307(2) gamma = 110.101(2).

[0072] 1 HNMR (400 MHz, DMSO-d6, ppm): δ = 7.96 (d, J = 7.5 Hz, 20H), 7.51 (t, J = 7.3 Hz, 10H), 7.43 (t, J = 7.5 Hz, 20H), 3.83-3.73 (m, 2H), 1.05 (d, J = 6.1 Hz, 12H). See Figure 4 . Figure 4 The nuclear magnetic resonance hydrogen spectrum of the compound prepared in Example 2 of the present invention is shown below, which illustrates that the synthesized structure is accurate.

[0073] Example 3

[0074]

[0075] A 20 mL glass vial was charged with 0.284 g of titanium isopropoxide and 0.184 g of zinc acetate. The acid solution was added to the vial and the vial was sealed. The solution was sonicated for 20 min, and then allowed to stand at room temperature for 7 d. The mother liquor was decanted and the solid was washed with anhydrous n-heptane three times. The solid was placed in a vacuum oven and dried at 45 °C for 48 h to give the dried solid product.

[0076] The crystal structure of the compound prepared in Example 2 of the present invention is shown below, which illustrates that the synthesized cluster is the expected structure. Figure 5 .

[0077] Crystal data: Space Group: P-1, Cell: a = 13.7176(10) b = 14.0786(10) c = 15.0858(10), alpha = 109.467(2) beta = 107.184(2) gamma = 105.364(2).

[0078] Figure 5 Crystal structure of the compound prepared in Example 3 of the present application.

[0079] 1 H NMR (400 MHz, DMSO-d6, ppm): δ = 7.91 (d, J = 8.0 Hz, 20H), 7.52 (d, J = 8.0 Hz, 20H), 6.79 (dd, J = 17.7, 10.9 Hz, 10H), 5.93 (d, J = 17.6 Hz, 10H), 5.36 (d, J = 10.9 Hz, 10H), 3.77 (s, 2H), 1.04 (d, J = 6.1 Hz, 12H). See Figure 6 .

[0080] Figure 6 NMR of the compound prepared in Example 3 of the present application, which illustrates the accuracy of the synthesis structure; Example 4

[0081]

[0082] Dissolve 0.7 g of p-fluorobenzoic acid in a mixed solution of 6 mL of isopropyl alcohol and 0.6 mL of dichloromethane. Take another 20 mL glass sample bottle, add 0.284 g of titanium isopropyl alcohol and 0.184 g of zinc acetate, and finally add the organic solution of the above acid, and then seal the sample bottle. Dissolve for 20 min using ultrasonic, and after the solid is completely dissolved, filter, and place the filtrate in a high temperature and high pressure reaction kettle, and stand in a constant temperature oven at 60°C for 7d, and there are colorless crystals generated at the bottom of the sample bottle, pour out the mother liquor, and use anhydrous n-heptane to wash the obtained solid three times, and place the solid in a vacuum drying box, and vacuum dry at 45°C for 48 hours to obtain dry solid product.

[0083] Crystal structure of the compound prepared in Example 4 of the present application, which illustrates that the synthesized cluster is the expected structure; Figure 7 . Figure 7 Crystal structure of the compound prepared in Example 4 of the present application, which illustrates that the synthesized cluster is the expected structure;

[0084] Crystal data: Space Group: P-1, Cell: a = 13.2926(19) b = 13.4912(19) c = 14.562(2), alpha = 86.204(6) beta = 63.227(5) gamma = 65.871(6).

[0085] 1 H NMR (400 MHz, DMSO-d6, ppm): δ = 8.23-7.84 (m, 20H), 7.24 (t, J = 8.7 Hz, 20H), 3.77 (p, J = 6.2 Hz, 2H), 1.04 (d, J = 6.1 Hz, 12H). See Figure 8 .

[0086] Figure 8 The nuclear magnetic hydrogen spectrum of the compound prepared in Example 4 of the present application illustrates the synthesis structure is accurate;

[0087] 19 F NMR (377 MHz, DMSO-d6, ppm): δ = -104.03. See Figure 9 .

[0088] Figure 9 The nuclear magnetic fluorine spectrum of the compound prepared in Example 4 of the present application illustrates the synthesis structure is accurate;

[0089]

[0090] Dissolve 0.8 g of p-ethynylbenzoic acid in a mixed solution of 4 mL of dichloromethane and 4 mL of isopropyl alcohol. Take another 20 mL glass sample bottle, add 0.284 g of titanium isopropyl alcohol and 0.184 g of zinc acetate, and finally add the organic solution of the above acid, then seal the sample bottle. Dissolve for 20 min using ultrasonic, after the solid is completely dissolved, filter, let the filtrate stand for 30 d, there are light yellow crystals generated at the bottom of the sample bottle, pour the mother liquor, wash the obtained solid with anhydrous n-heptane for three times, put the solid into a vacuum drying oven, vacuum dry at 45 °C for 48 hours, obtain the dried solid product.

[0091] The crystal structure of the compound prepared in Example 5 of the present application is shown in Figure 10 . Figure 10 The crystal structure of the compound prepared in Example 5 of the present application illustrates that the synthesized cluster is the expected structure;

[0092] Crystal data: Space Group: C2 / c, Cell: a = 17.0606 (5) b = 21.4103 (9) c = 25.6078 (8), alpha = 90 beta = 91.506 (3) gamma = 90.

[0093] 1H NMR (400 MHz, DMSO-d6): δ = 7.93 (d, J = 8.0 Hz, 20H), 7.53 (d, J = 7.9 Hz, 20H), 3.77 (p, J = 6.1 Hz, 2H), 3.34 (s, 10H), 1.04 (d, J = 6.1 Hz, 12H). See Figure 1 for the1H NMR spectrum of the compound prepared in Example 1. Figure 11 .

[0094] Figure 11 The1H NMR spectrum of the compound prepared in Example 5 is shown in Figure 5, which indicates that the synthesized structure is accurate;

[0095] Example 6

[0096]

[0097] A 20 mL glass sample bottle was prepared by adding 0.284 g of titanium isopropoxide and 0.184 g of zinc acetate, and then the above-mentioned acid organic solution was added and the sample bottle was sealed. The sample was dissolved using ultrasonic for 20 min, and after the solid was completely dissolved, the filtrate was placed in a high-temperature and high-pressure reaction kettle, and was placed in a constant-temperature oven at 60°C for 7 d. Crystals were generated at the bottom of the sample bottle, and after the mother liquor was poured, the obtained solid was washed with anhydrous n-heptane for three times, and was placed in a vacuum drying box and dried at 45°C for 48 h to obtain a dry solid product.

[0098] The crystal structure of the compound prepared in Example 6 is shown in Figure 6, which indicates that the synthesized cluster is the expected structure; Figure 12 .

[0099] Crystal data: Space Group: P-1, Cell: a = 14.8911 (6) b = 14.8911 (6) c = 15.9062 (6), alpha = 92.748 (2) beta = 117.641 (2) gamma = 112.536 (2).

[0100] Figure 12 The crystal structure of the compound prepared in Example 6 is shown in Figure 6, which indicates that the synthesized cluster is the expected structure;

[0101] Example 7

[0102]

[0103] Dissolve 0.825 g of p-dimethylaminobenzoic acid in a mixed solution of 8 mL of dichloromethane and 4 mL of isopropyl alcohol. Take another 20 mL glass sample bottle, add 0.284 g of titanium isopropoxide and 0.184 g of zinc acetate to it, and finally add the organic solution of the above acid to it and seal the sample bottle. Dissolve for 20 min using ultrasonic, filter after the solid is completely dissolved, and let the filtrate stand for 15 d. Solid is generated at the bottom of the sample bottle, pour out the mother liquor, and wash the obtained solid with anhydrous n-heptane three times. Put the solid into a vacuum drying oven, and dry at 45 °C for 48 h to obtain the dried solid product.

[0104] Application Example 1

[0105] Application of a zinc-titanium composite cluster in electron beam lithography and extreme ultraviolet lithography:

[0106] To obtain a photoresist film layer with a thickness of about 30 nm, accurately weigh 8 mg of Examples 1 and 2, 15 mg of Examples 4 and 6, respectively, into 1 mL of chloroform solution, ultrasonic oscillation for 10 min, and filter twice with a 0.22 μm PTFE filter membrane to obtain a photoresist solution.

[0107] Due to the high sensitivity of Example 3, a free radical inhibitor is needed to control the free radical diffusion during the lithography process. Accurately weigh 15 mg of Example 3 and 4.8 mg / 7.2 mg of hydroquinone (HQ) into 1 mL of chloroform solution, respectively, ultrasonic oscillation for 10 min, and filter twice with a 0.22 μm PTFE filter membrane to obtain a photoresist solution.

[0108] During spin coating, 35 μL of photoresist solution is dropped on a 1 cm*1 cm silicon wafer with a pipette. The solution of Example 1 is rotated at a speed of 2000 rpm for 30 s, the solution of Example 2 is rotated at a speed of 6000 rpm for 30 s, and the rest of the photoresist solutions are all rotated at a speed of 8000 rpm for 30 s. Then, bake at 50 °C for 1 min to obtain a smooth film with a thickness of about 30 nm.

[0109] Test Example 1

[0110] The films made by the compounds provided by Examples 1, 2, 3, and 4 using the method described in the application example are subjected to normalized electron beam exposure test, with an acceleration voltage of 2 kV, a size of each square of 5 μm*5 μm, and a spacing of 5 μm, a total of 8*8 = 64. After exposure, the film made by Example 3 is developed using 4-methyl-2-pentanone for 45 s, and the rest is developed using isopropyl alcohol for 30 s and then blown dry with nitrogen. The thickness change graph of the above four zinc-titanium composite clusters is obtained using AFM, as shown in Figure 13 and Figure 14The measured thickness of the square was normalized and compared with the corresponding dose to make a contrast curve, as shown in Figure 15 and Figure 16 The contrast was calculated using the following formula: The contrast of the compounds prepared in the above examples was calculated and shown in Table 1. The e-beam exposure sensitivity (D 100 ) of the compounds prepared in the above examples was shown in Table 2. The HOMO energy level of Examples 1, 2, 3, and 4 in Table 3, the vertical ionization potential (VIP) of each cluster, and the dissociation energy of ligands at different sites in Table 4 were calculated by DFT.

[0111] Table 1. Contrast of the compounds prepared in the above examples

[0112]

[0113] Table 2. Sensitivity of the compounds prepared in the above examples

[0114]

[0115] Table 3. HOMO and VIP of the compounds prepared in the above examples

[0116] Example HOMO (eV) VIP (eV) Example 1 -6.37 7.54 Example 2 -7.17 7.97 Example 3 -6.86 7.55 Example 4 -7.53 8.86

[0117] Table 4. Average dissociation energy of ligands of the compounds prepared in the above examples

[0118] Example Decarboxylation (eV) Decarbonylation (eV) Example 1 3.11 2.87 Example 2 3.76 3.42 Example 3 2.32 1.88 Example 4 5.27 4.74

[0119] In combination Figure 15 , Figure 16 and Table 1, the contrast of Examples 1, 2, and 4 and Example 3+48wt% HQ is between 1 and 2, which is suitable for the currently commercial photoresist, and the line pattern with more vertical sidewall can be easily obtained in the process of periodic line patterning.

[0120] From Table 2, the sensitivity of Example 3 is the highest, followed by Example 1, then Example 2, and the sensitivity of Example 4 is the lowest. In combination with the molecular structure, it can be known that when the electron-donating group is introduced into the aromatic acid ligand of the cluster, the exposure sensitivity of the cluster will be improved, and the introduction of the electron-withdrawing group is opposite. In combination with the molecular structure and Table 3, it can be known that the introduction of the electron-donating group will improve the HOMO energy level of the cluster, and then improve the VIP of the cluster, so that the cluster is more likely to produce secondary electrons and photoelectrons to improve the reaction efficiency during exposure. In combination with the molecular structure and Table 4, it can be known that the introduction of the electron-donating group can also reduce the ligand dissociation energy of the cluster, which can also improve the sensitivity of the cluster during exposure.

[0121] The vinyl group introduced in Example 3 is not only a push electron group, but also provides another way to improve the sensitivity of cluster lithography because it can undergo crosslinking polymerization of double bonds upon exposure, so its sensitivity is greatly improved compared to other clusters, and is higher than the sensitivity of most photoresists disclosed, which is conducive to improving the light quantum utilization efficiency, and high sensitivity means less energy is required for exposure, which is conducive to improving energy utilization efficiency and realizing industrialization.

[0122] Test Example 2

[0123] The zinc-titanium composite clusters provided in Examples 1, 2, 3, 4, and 6 were made into thin films using the method described in the application example, and electron beam exposure tests were performed. The acceleration voltage of the electron beam exposure was 30 kV. After exposure, the thin film prepared in Example 3 was developed using 4-methyl-2-pentanone for 45 s, and the rest were developed using isopropanol for 30 s and then dried using nitrogen. Figure 17 The SEM results of the periodic pattern after development of Example 3 containing different mass fractions of HQ are shown in Figure 18 .

[0124] In combination with Figure 17 and Figure 18 It can be seen that the compound shown in Example 1 formed a line with a line width of about 9.6 nm at a period of 70 nm; the compound shown in Example 2 formed a line with a line width of about 12.6 nm at a period of 70 nm; the compound shown in Example 4 formed a line with a line width of about 12.2 nm at a period of 70 nm; the compound shown in Example 6 formed a line with a line width of about 18.2 nm at a period of 70 nm; the compound shown in Example 3 containing 32 wt% HQ formed a line with a line width of about 19.2 nm at a period of 150 nm; and the compound (Ph-Sn-Oc) shown in Example 3 containing 48 wt% HQ also formed a line with a line width of about 19.2 nm at a period of 150 nm.

[0125] Test Example 3

[0126] The thin films prepared in Examples 1 and 3 containing 32 wt% HQ were patterned using XIL (X-ray interference lithography) at EUV (13.5 nm) exposure at SSRF (Shanghai Synchrotron Radiation Facility) using the method described in the application example. After exposure, Example 1 was developed using isopropanol for 30 s, and Example 3 containing 32 wt% HQ was developed using 4-methyl-2-pentanone for 45 s, and both were dried using nitrogen after development.

[0127] The EUV exposure test uses grating diffraction exposure, and the diffraction grating can form periodic lines with a period of 70 nm (L / S). After exposure, the obtained pattern is measured using SEM and AFM, and the test results are shown in Table 1. Figure 19 Example 1 can be exposed at an exposure dose of 150 mJ / cm 2 to obtain clear lines, while Example 3 containing 32 wt% HQ can be exposed at 25 mJ / cm 2 , indicating that the synergistic effect of the electron-donating effect of the double bond and the cross-linking polymerization greatly improves the sensitivity of this type of photoresist.

[0128] In summary, the zinc-titanium composite cluster photoresist provided by the present application has the beneficial effects of high resolution and extremely high sensitivity.

[0129] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A type of zinc-titanium composite cluster, characterized in that, It has the following general formula I structure: In general formula I, R1 is selected from H, alkyl groups having 1-8 carbons, alkenyl groups having 2-8 carbons, alkynyl groups having 2-8 carbons, halogens, and nitro groups.

2. The zinc-titanium composite cluster according to claim 1, characterized in that, R1 is selected from H atom, methyl, vinyl, ethynyl, F atom, and nitro.

3. The method for synthesizing a type of zinc-titanium composite cluster as described in claim 1, characterized in that, The reaction formula is as follows: The synthesis steps include: dissolving benzoic acid modified with R1 substituent in an anhydrous organic solvent, adding the dissolved organic acid solution to a mixture of titanium isopropoxide and zinc acetate in a molar ratio of 1-5:1-5, dissolving completely, and allowing the resulting solution to stand at 25-60℃ for 7-30 days under sealed conditions until crystal precipitate forms. The resulting solid product is then washed, filtered, and vacuum dried to obtain a pure solid product.

4. The method according to claim 3, characterized in that, The molar ratio of benzoic acid modified with R1 substituent to titanium isopropoxide is 1-15:

1.

5. The method according to claim 3, characterized in that, The molar ratio of benzoic acid modified with the R1 substituent to the organic solvent is 1 mmol: 1-20 mL; the organic solvent is selected from one of the following: a mixed solution of isopropanol: dichloromethane with a molar ratio of 1-5:1-5, a mixed solution of isopropanol: tetrahydrofuran with a molar ratio of 1-8:1-5, a mixed solution of isopropanol: dichloromethane with a molar ratio of 8-15:1-5, or a mixed solution of tetrahydrofuran: dichloromethane with a molar ratio of 5-10:1-5.

6. The application of the zinc-titanium composite cluster as described in claim 1 in extreme ultraviolet lithography and electron beam lithography, wherein the zinc-titanium composite cluster serves as a photosensitizer and resin in a photoresist formulation.

7. The application according to claim 6, characterized in that, The photoresist is prepared by adding chloroform to the zinc-titanium composite cluster, ultrasonically treating it for 10 minutes, and then filtering it to obtain a photoresist solution. The zinc-titanium composite cluster serves as a photosensitizer and resin in the electron beam photoresist formulation, enabling the patterning of 8nm-25nm linewidth lines with high sensitivity in electron beam lithography.

8. The application according to claim 6, characterized in that, The zinc-titanium composite clusters, as photosensitizers and resins in the extreme ultraviolet (EUV) photoresist formulation, complete the patterning of periodic lines ranging from 75nm to 300nm during EUV lithography exposure.

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