An ultraviolet-cured nanoimprint photoresist with a semi-interpenetrating network structure and a preparation method thereof

Abstract

The application discloses a kind of semi-interpenetrating network structure ultraviolet curing nanoimprint photoresist and preparation method thereof, belong to ultraviolet nanoimprint photoresist field.The application obtains semi-interpenetrating network structure without phase separation in nanoscale by introducing hydrogen bond interaction between nanoimprint photoresist components, successfully applies semi-interpenetrating network structure in nanoimprint photoresist field.The application provides a new method for the design of high mechanical property nanoimprint photoresist, which improves mechanical property while reducing photoresist shrinkage to some extent.Compared with the prior art nanoimprint photoresist, it has the advantages of high mechanical property, low volume shrinkage, and can efficiently perform high-resolution nanostructure imprinting by simple spin-coating film formation.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of ultraviolet curing nanoimprint photoresist, and particularly relates to a semi-interpenetrating network structure ultraviolet curing nanoimprint photoresist and a preparation method thereof. BACKGROUND

[0002] Nanoimprint is a new high-resolution micro-nano manufacturing method, which has important application prospects in the fields of integrated circuits, optical devices, biochips and flexible electronics. Compared with traditional photolithography, nanoimprint has the potential to exceed the pattern resolution limit of traditional technology, and can reach sub-10 nm scale, providing an efficient and low-cost technical solution for the manufacture of nano-scale features, and being suitable for large-area substrate, especially for batch manufacturing of functional nanostructures.

[0003] Nanoimprint lithography is a micro-nano manufacturing method that transfers micro-nano structures on a template to a photoresist layer by mechanical imprinting combined with ultraviolet curing or thermal curing process. According to the curing method of nanoimprint photoresist, nanoimprint can be divided into ultraviolet imprinting and thermal imprinting. Thermal imprinting refers to using a thermoplastic material as a photoresist. When the photoresist is heated above the glass transition temperature, the chain segments begin to move, the pattern of the template is transferred to the photoresist by applying pressure, and the pattern is fixed by cooling. The continuous manufacturing process is significantly reduced in efficiency by the heating and cooling rate, and the difference in thermal expansion coefficient between the mold and the imprinting glue also causes additional instability, while high temperature will reduce the durability of the mold. In contrast, ultraviolet imprinting well balances these problems, so the industry prefers to use ultraviolet nanoimprint technology.

[0004] Nanoimprint photoresist is a key material in nanoimprint technology. For the design of high-resolution nanoimprint photoresist, shrinkage is an important parameter affecting the fidelity of the imprinted pattern and the demolding. The shrinkage of the photoresist will cause distortion of the pattern after imprinting, and the internal stress generated by shrinkage will also increase the demolding force and increase the risk of photoresist fracture. The shrinkage of the nanoimprint photoresist is due to the reduction of the distance between the photoresist molecules from the van der Waals distance before curing to the covalent bond distance after curing. Purely from the perspective of shrinkage, the smaller the shrinkage, the more conducive to pattern fidelity and demolding process. Therefore, many researchers focus on shrinkage control. There are many methods for reducing the shrinkage of nanoimprint photoresist, such as adding inorganic particle fillers to the system, introducing reversible bonds such as disulfide bonds, introducing volume expansion monomers, reducing the concentration of photo-curing groups, using flexible polymeric monomers, using step-by-step polymerization, using pulse UV curing, and reducing the intensity of ultraviolet light. Although there are many methods to reduce shrinkage, it is difficult to control the photoresist to produce no shrinkage.

[0005] In fact, high mechanical properties are an effective way to solve the fidelity and demolding problems caused by photoresist shrinkage. A higher modulus can resist internal shrinkage stress, thus suppressing shrinkage after imprinting and improving pattern fidelity. Higher elongation at break and fracture strength, on the other hand, give the material better fracture resistance during demolding. Therefore, with the support of good mechanical properties, photoresist only needs to control the shrinkage rate within a certain range to achieve high-resolution structure imprinting.

[0006] Traditional methods for improving the mechanical properties of photoresist, such as increasing the degree of crosslinking or using rigid monomers, inevitably reduce the elongation at break. While adding flexible monomers can increase the elongation at break, it reduces the modulus and strength. It is difficult to resolve the contradiction between strength, modulus, and elongation at break. At the same time, increasing the degree of crosslinking or using rigid monomers will also lead to a greater shrinkage rate, which may increase the risk of breakage of the imprinted pattern and the imprinting mold to some extent.

[0007] In the field of polymer science, semi-interpenetrating polymer networks (SIPs) are an effective method for resolving the contradiction between strength, modulus, and elongation at break. A SIP refers to a composite material structure formed by the interpenetration of a linear polymer and a cross-linked network polymer. The core advantage of SIPs lies in their ingenious combination of the advantages of both polymers, achieving a balance of performance strengths and weaknesses. In some systems, the linear polymer chains can act as toughening agents, absorbing energy and preventing crack propagation under external forces through segment slippage and orientation. This allows the material to maintain high modulus while significantly improving toughness and fracture resistance. In other systems, the linear component can also act as a toughening agent while simultaneously entangled and binding the network structure, thus maintaining elongation at break while significantly increasing modulus.

[0008] Meanwhile, theoretically, semi-interpenetrating polymer (SIP) networks also have significant potential in reducing shrinkage and improving spin-coating film formation. During curing, only the monomer components undergo cross-linking shrinkage, while the linear polymers, acting as fillers, do not shrink or shrink very little. These linear polymer chains can physically penetrate the cross-linked network, acting as a skeletal support and dilution agent, effectively absorbing and dispersing shrinkage stress, thus possessing the potential to reduce the overall volume shrinkage rate. The addition of linear polymers can also adjust the system viscosity, improve the film-forming quality of the adhesive, and has the potential to reduce dewetting phenomena during spin-coating.

[0009] However, while introducing semi-interpenetrating networks into imprinting adhesives has many potential advantages, the miscibility between the network components and the linear polymer components poses a significant challenge to the design of semi-interpenetrating network nanoimprinting adhesives. The phase separation structure of semi-interpenetrating network materials is often on the scale of hundreds of nanometers or even micrometers, which makes it difficult to guarantee the uniformity of the structure for high-resolution nanoimprinting patterns, and may even lead to situations where imprinting is impossible. Summary of the Invention

[0010] To address the shortcomings of existing technologies, this invention provides a semi-interpenetrating network structure UV-curable nanoimprint photoresist and its preparation method. This invention utilizes supramolecular interactions to introduce a nanoscale, phase-separated semi-interpenetrating network structure into the system. The semi-interpenetrating network structure comprehensively improves the mechanical properties of the photoresist, and the nanoscale, phase-separated structure ensures the uniformity and stability of each nanoimprint structure, which is fundamental to ensuring the application of the semi-interpenetrating network structure in the field of high-resolution nanoimprinting. Simultaneously, this method reduces the density of polymerizable groups in the photoresist, not only without increasing the system's shrinkage rate but also to a certain extent reducing the photoresist shrinkage rate. Furthermore, the nanoimprint photoresist of this invention can be more easily imprinted with high-resolution nanopatterns using a spin-coating method.

[0011] The semi-interpenetrating network structure UV-curable nanoimprint photoresist of this invention comprises the following components by weight:

[0012] 50-95 parts of hydroxy acrylate monomer, 1-20 parts of mercapto compound, 1-30 parts of linear polymer, and 1-5 parts of photoinitiator.

[0013] The hydroxyacrylate monomers are selected from 4-hydroxybutyl acrylate, 5-hydroxypentyl acrylate, 2-hydroxycyclohexyl acrylate, 3-hydroxyadamantane-1-yl acrylate, pentaerythritol triacrylate, 3,5-dihydroxyphenol methacrylate, 3-chloro-2-hydroxypropyl methacrylate, 2-(2-hydroxyethoxy)ethyl acrylate, 6-(4-hydroxyphenoxy)hexyl acrylate, 2-(2-hydroxyethoxy)ethyl methacrylate, 3,5-dihydroxyadamantane-1-yl methacrylate, 4-((4-hydroxyphenyl)sulfonyl)phenyl acrylate, 3-(acryloyloxy)-2- One or more of the following: hydroxypropyl methacrylate, 2-(4-benzoyl-3-hydroxyphenoxy)ethyl methacrylate, 2-(2-(2-hydroxyethoxy)ethoxy)ethyl methacrylate, 5,5,5-trifluoro-4-hydroxy-4-(trifluoromethyl)pent-2-yl methacrylate, 2-(2-(2-(2-hydroxyethoxy)ethoxy)ethoxy)ethyl methacrylate, 4,4,4-trifluoro-3-hydroxy-2-methyl-3-(trifluoromethyl)but-2-yl methacrylate, glyceryl dimethacrylate, poly(ethylene glycol) methacrylate, and glycerol 1,3-diglyceryl alcohol diacrylate.

[0014] The linear polymer is selected from one or more of poly(4-vinylpyridine), poly(2-vinylpyridine), polyamide, polyvinyl alcohol, polyacrylamide, polyurethane, polyurea, and polyvinylpyrrolidone.

[0015] The linear polymer has a number-average molecular weight range of 1k-10000k. Further optimization resulted in a number-average molecular weight range of 10k-1000k for the linear polymer.

[0016] The thiol compounds are selected from dithiothreitol, 2,3-butanedithiol, 1,2-ethanedithiol, 1,8-octanedithiol, 1,4-butanedithiol, 1,6-hexanedithiol, 1,5-dimercaptonaphthalene, 2,4-dimercaptopyrimidine, 1,4-benzenedimethylthiol, 1,3-benzenedimethylthiol, 1,3-dimercaptopropane, 2,5-dimercaptothiadiazole, toluene-3,4-dithiophenol, 2,3-dimercaptosuccinic acid, 3,5-dimercaptobenzoic acid, 4',4-dimercaptodiphenyl sulfide, 2,3-dimercaptophthalic acid, 2,3-dimercaptoprop-1-ol, 2,5-dimercaptoterephthalic acid, 4,4'-dimercaptostilbene, tetramercaptobenzene, pentaerythritol tetramercaptoacetate, 2,6-naphthyldithiol, 4,4 One or more of the following: '-dimercaptodiphenyl ether, 4,4′-thiodiphenylthiol, biphenyl-4,4'-dithiol, 1,3,5-benzenetrithiophenol, trimercaptotriazine, 2,7-naphthyldithiol, 2,2'-dimercaptobiphenyl, 2,5-dimercaptobenzene, 2,2'-dimercaptobipyridine, 2,5-dimercaptopyrazole, dimercaptoacetylbenzene, 2,6-dimercaptothiophene, 3,5-dimercapto-1,2,4-triazacyclohexane, dimercaptosilane, and 2,6-dimercaptopyridine.

[0017] The photoinitiator is selected from one or more of the following: benzoin dimethyl ether, 2-hydroxy-2-methyl-1-phenylpropanone, benzoin ethyl ether, bibenzoyl, benzophenone, methyl o-benzoyl, 2-hydroxy-4-(2-hydroxyethoxy)-2-methylphenylpropanone, 2-isopropyl-thioxanth-9-one, 4-phenylbenzophenone, methyl α-oxophenylacetate, 2-hydroxy-2-methylphenylpropane-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone, and 2,2-dimethoxyphenylacetophenone.

[0018] The method for preparing the semi-interpenetrating network structure UV-curable nanoimprint photoresist of the present invention includes the following steps:

[0019] Under UV-free conditions, linear polymers are added to hydroxy acrylate monomers and stirred until the linear polymers are completely dissolved in the hydroxy acrylate monomers. Then, a mercapto compound is added while stirring for 5-10 minutes, followed by the addition of a photoinitiator. Stirring continues for 10-20 minutes, and the mixture is filtered to obtain a semi-interpenetrating network structure UV-curable nanoimprint photoresist.

[0020] The filtration operation uses a 2000-2500 mesh filter.

[0021] The application method of the semi-interpenetrating network structure UV-curable nanoimprint photoresist of the present invention includes the following steps:

[0022] The semi-interpenetrating network structure UV-curable nanoimprint photoresist is spin-coated onto a silicon wafer after adhesion enhancement treatment to obtain a uniform photoresist film. A certain pressure is applied to the nanoimprint mold with microstructures using weights to allow the photoresist to fill the microstructure gaps in the imprint mold. After full contact, the mold and the square quartz sheet are placed in a vacuum environment for a period of time to remove residual air in the imprint structure. The mold and the square quartz sheet are then removed and placed in the center of 365 nm UV irradiation. After curing, the mold is removed to obtain the photoresist of the desired imprint structure.

[0023] The spin coating operation speed is 500-5000 r / min, and the spin coating time is 10-600 s. More preferably, the spin coating speed is 1500-2500 r / min, and the spin coating time is 60-120 s.

[0024] The intensity of the ultraviolet light irradiation is 10-200 mW / cm². 2 The illumination time is 1-300 s. Further optimization yields a light intensity of 20-80 mW / cm². 2 The illumination time is 1-30 seconds.

[0025] The thickening treatment involves uniformly spin-coating 0.1-2 mL of thickening agent onto a silicon wafer, heating it on a 120°C hot plate for 2 minutes, and then cooling it to room temperature.

[0026] Compared with the prior art, the beneficial effects of this invention are as follows:

[0027] This invention utilizes supramolecular interactions to obtain a nanoscale, phase-separated semi-interpenetrating network structure, enabling its successful application in high-resolution nanoimprint lithography. This method improves mechanical properties while also reducing the shrinkage rate of the photoresist to some extent.

[0028] In addition, the preparation method of the semi-interpenetrating network nanoimprint photoresist in this invention is simple to operate and easy to implement. It does not require inkjet printing and can achieve high-resolution nanostructure imprinting replication simply by spin coating. Attached Figure Description

[0029] Figure 1 Imprinted nanostructure patterns for nanoimprint photoresist PR-1-8%.

[0030] Figure 2 Imprinted nanostructure patterns for nanoimprint photoresist PR-2-16%.

[0031] Figure 3 Imprinted nanostructure patterns for nanoimprint photoresist PR-3.

[0032] Figure 4 These are physical images of mixed materials M-1, M-2, and M-3. Image a corresponds to M-1, image b corresponds to M-2, and image c corresponds to M-3.

[0033] Figure 5 The images show the AFM morphology and phase diagram of photoresist PR-1-8%. Figure a is the phase diagram, and figure b is the morphology diagram.

[0034] Figure 6 The images show the AFM morphology and phase diagram of photoresist R-1. Figure a is the phase diagram, and figure b is the morphology diagram.

[0035] Figure 7 The images show the AFM morphology and phase diagram of the photoresist PR-2-16%. Figure a is the phase diagram, and figure b is the morphology diagram.

[0036] Figure 8 The images show the AFM morphology and phase diagram of photoresist R-2. Figure a is the phase diagram, and figure b is the morphology diagram.

[0037] Figure 9 The images show the AFM morphology and phase diagram of photoresist PR-4. Figure a is the phase diagram, and figure b is the morphology diagram.

[0038] Figure 10 The images show the AFM morphology and phase diagram of photoresist R-4. Figure a is the phase diagram, and figure b is the morphology diagram.

[0039] Figure 11 The figures show the stress-strain curves after curing of photoresists R-1, PR-1-4%, PR-1-8%, and PR-1-12%. Figure a corresponds to R-1, figure b to PR-1-4%, figure c to PR-1-8%, and figure d to PR-1-12%.

[0040] Figure 12 These are the stress-strain curves after curing of photoresists R-2, PR-2-4%, PR-2-8%, PR-2-12%, and PR-2-16%. Figure a corresponds to R-2, figure b to PR-2-4%, figure c to PR-2-8%, figure d to PR-2-12%, and figure e to PR-2-16%. Detailed Implementation

[0041] The technical solution of the present invention will be further analyzed and explained through specific embodiments below.

[0042] Example 1:

[0043] The purpose of Example 1 is mainly to demonstrate the semi-interpenetrating network structure nanoimprint adhesive of the present invention, its imprinting process, and the imprinted structure.

[0044] The preparation method of the semi-interpenetrating network structure UV-curable nanoimprint adhesive (PR-1-8%) in this embodiment includes the following steps:

[0045] Under UV-free conditions, 0.24 g of poly(4-vinylpyridine) (Mw=6w) was added to 3 g of pentaerythritol triacrylate and stirred at room temperature for 1 h. After the poly(4-vinylpyridine) was completely dissolved in the pentaerythritol triacrylate, 0.3 g of pentaerythritol tetramercaptoacetate was added and stirred for 5-10 min. Then, 0.15 g of photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone was added and stirred for another 10-20 min. The mixture was then filtered through a 2500-mesh screen to obtain a semi-interpenetrating network structure UV nanoimprint photoresist.

[0046] The photoresist prepared in this embodiment was subjected to high-resolution nanoimprinting according to the following process:

[0047] (1) The silicon wafer substrate was ultrasonically treated in acetone, isopropanol, and water for 15 min in sequence, and then treated with an oxygen plasma cleaner for 2 min to obtain a clean silicon wafer substrate. 0.5 mL of tackifier was then added to the silicon wafer for spin coating at a speed of 2000 r / min for 60 s. After spin coating, the wafer was transferred to a 120°C container. o The silicon wafer was obtained by heating on a C-heat plate for 2 minutes. The adhesive was prepared by mixing propyl 3-trimethoxysilane acrylate, propylene glycol methyl ether acetate, and acetone in a mass ratio of 1:0.7:0.1.

[0048] (2) The photoresist is spin-coated onto the silicon wafer after the adhesion enhancement treatment to obtain a uniform photoresist film. The spin-coating speed is 2000 r / min and the spin-coating time is 90 s.

[0049] (3) Apply pressure to the nano-imprint quartz mold with microstructure (240 nm linewidth, 200 nm spacing grating structure mold) with weights to make the photoresist fill the gaps in the microstructure in the imprint mold. After sufficient contact, place the mold and the substrate in a vacuum environment for a period of time to remove residual air in the imprint structure.

[0050] (4) Remove the mold and substrate and place them in a 365 nm ultraviolet light irradiation center at 50 mW / cm². 2 After curing with light intensity for 5 seconds, the mold can be removed to obtain a photoresist nanostructure that is the opposite of the mold's microstructure.

[0051] Nanostructures obtained by imprinting, such as Figure 1 As shown, the photoresist PR-1-8% can complete the transfer of a 200 nm linewidth grating structure under simple spin coating conditions.

[0052] Example 2:

[0053] The purpose of Example 2 is mainly to demonstrate the semi-interpenetrating network structure nanoimprint adhesive of the present invention, its imprinting process, and the imprinted structure.

[0054] The preparation method of the semi-interpenetrating network structure UV-curable nanoimprint adhesive (PR-2-16%) in this embodiment includes the following steps:

[0055] Under UV-free conditions, 0.48 g of poly(4-vinylpyridine) was added to 3 g of glyceryl dimethacrylate and stirred at room temperature for 1 h. After the poly(4-vinylpyridine) was completely dissolved in the glyceryl dimethacrylate, 0.3 g of pentaerythritol tetramercaptoacetate was added and stirred for 5-10 h. Then, 0.15 g of photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone was added and stirring was continued for 10-20 min. The mixture was then filtered through a 2500-mesh screen to obtain a semi-interpenetrating network structure UV nanoimprint photoresist.

[0056] The photoresist prepared in this embodiment was subjected to high-resolution nanoimprinting according to the following process:

[0057] (1) The silicon wafer substrate was ultrasonically treated in acetone, isopropanol, and water for 15 min in sequence, and then treated with an oxygen plasma cleaner for 2 min to obtain a clean silicon wafer substrate. 0.5 mL of tackifier was then added to the silicon wafer for spin coating at a speed of 2000 r / min for 60 s. After spin coating, the wafer was transferred to a 120°C container. o The silicon wafer was obtained by heating on a C-heat plate for 2 minutes. The adhesive was prepared by mixing propyl 3-trimethoxysilane acrylate, propylene glycol methyl ether acetate, and acetone in a mass ratio of 1:0.7:0.1.

[0058] (2) The photoresist is spin-coated onto the silicon wafer after the adhesion enhancement treatment to obtain a uniform photoresist film. The spin-coating speed is 2000 r / min and the spin-coating time is 90 s.

[0059] (3) Apply pressure to the nano-imprint quartz mold with microstructure (80 nm linewidth, 50 nm line spacing grating structure mold) with weights to make the photoresist fill the gaps in the microstructure in the imprint mold. After sufficient contact, place the mold and the substrate in a vacuum environment for a period of time to remove residual air in the imprint structure.

[0060] (4) Remove the mold and substrate and place them in a 365 nm ultraviolet light irradiation center at 50 mW / cm². 2 After curing with light intensity for 5 seconds, the mold can be removed to obtain a photoresist nanostructure that is the opposite of the mold's microstructure.

[0061] Nanostructures obtained by imprinting, such as Figure 2As shown, the photoresist PR-2-16% can complete the transfer of a 50 nm linewidth grating structure under simple spin coating conditions.

[0062] Example 3:

[0063] The purpose of Example 3 is mainly to demonstrate the semi-interpenetrating network structure nanoimprint adhesive of the present invention, its imprinting process, and the imprinted structure.

[0064] The preparation method of the semi-interpenetrating network structure UV-curable nanoimprint adhesive (PR-3) in this embodiment includes the following steps:

[0065] Under UV-free conditions, 0.24 g of polyvinyl alcohol (Mw=6.1w) was added to 3 g of dimethacrylate and stirred at room temperature for 1 h. After the polyvinyl alcohol was completely dissolved in the dimethacrylate, 0.3 g of pentaerythritol tetramercaptoacetate was added and stirred for 5-10 min. Then, 0.15 g of photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone was added and stirred for another 10-20 min. The mixture was then filtered through a 2500-mesh screen to obtain a semi-interpenetrating network structure UV nanoimprint photoresist.

[0066] The photoresist prepared in this embodiment was subjected to high-resolution nanoimprinting according to the following process:

[0067] (1) The silicon wafer substrate was ultrasonically treated in acetone, isopropanol, and water for 15 min in sequence, and then treated with an oxygen plasma cleaner for 2 min to obtain a clean silicon wafer substrate. 0.5 mL of tackifier was then added to the silicon wafer for spin coating at a speed of 2000 r / min for 60 s. After spin coating, the wafer was transferred to a 120°C container. o The silicon wafer was obtained by heating on a C-heat plate for 2 minutes. The adhesive was prepared by mixing propyl 3-trimethoxysilane acrylate, propylene glycol methyl ether acetate, and acetone in a mass ratio of 1:0.7:0.1.

[0068] (2) The photoresist is spin-coated onto the silicon wafer after the adhesion enhancement treatment to obtain a uniform photoresist film. The spin-coating speed is 2000 r / min and the spin-coating time is 90 s.

[0069] (3) Apply pressure to the nano-imprint quartz mold with microstructure (200 nm linewidth, 240 nm line spacing grating structure mold) with weights to make the photoresist fill the gaps in the microstructure in the imprint mold. After sufficient contact, place the mold and the substrate in a vacuum environment for a period of time to remove residual air in the imprint structure.

[0070] (4) Remove the mold and substrate and place them in a 365 nm ultraviolet light irradiation center at 50 mW / cm². 2After curing with light intensity for 5 seconds, the mold can be removed to obtain a photoresist nanostructure that is the opposite of the mold's microstructure.

[0071] Nanostructures obtained by imprinting, such as Figure 3 As shown, the photoresist PR-3 can complete the transfer of a 200 nm line pitch grating structure under simple spin coating conditions.

[0072] Comparative Example 1:

[0073] The purpose of Comparative Example 1 is to compare the difference in solubility and compatibility of linear polymers in acrylate monomers before and after the introduction of hydrogen bonding interactions.

[0074] The preparation method of the mixed material (M-1) in this comparative example includes the following steps:

[0075] Under UV-free conditions, 0.24 g of poly(4-vinylpyridine) (Mw=6w) was added to 3 g of pentaerythritol triacrylate and stirred at room temperature for 1 h.

[0076] The preparation method of the mixed material (M-2) in this comparative example includes the following steps:

[0077] Under UV-free conditions, 0.24 g of poly(4-vinylpyridine) (Mw=6w) was added to 3 g of trimethylolpropane triacrylate and stirred at room temperature for 1 h.

[0078] The preparation method of the mixed material (M-3) in this comparative example includes the following steps:

[0079] Under UV-free conditions, 0.24 g of polystyrene (Mw=6w) was added to 3 g of pentaerythritol triacrylate and stirred at room temperature for 1 h.

[0080]

[0081] The component structures of the composite materials M-1, M-2, and M-3 are shown in Table 1, and their physical images are shown below. Figure 4 As shown in the diagram, the hydroxyl groups in the acrylate monomer of M-1 can form hydrogen bonds with the pyridine groups in the linear polymer. M-2 uses trimethylolpropane triacrylate instead of pentaerythritol triacrylate, and M-3 uses polystyrene instead of poly4-vinylpyridine. Comparison revealed that after the loss of hydrogen bond interactions, the compatibility between the two components of M-2 and M-3 was extremely poor, and the linear polymer component could not dissolve in the acrylate monomer. This preliminarily demonstrates that hydrogen bond interactions can effectively improve the compatibility between the two components.

[0082] Comparative Example 2:

[0083] The purpose of Comparative Example 2 is to compare whether phase separation occurs inside the photoresist material before and after the introduction of the ordinary semi-interpenetrating network structure and the semi-interpenetrating network structure of the present invention, and the effect of phase separation on the surface morphology of the material.

[0084] The preparation method of the UV-curable nanoimprint photoresist (R-1) in this comparative example includes the following steps:

[0085] Under UV-free conditions, 3 g of pentaerythritol triacrylate and 0.3 g of pentaerythritol tetramercaptoacetate were stirred and mixed at room temperature for 5-10 min. Then, 0.15 g of photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone was added and stirring was continued for 10-20 min. The mixture was then filtered through a 2500-mesh screen to obtain UV-curable nanoimprint photoresist.

[0086] The preparation method of the UV-curable nanoimprint photoresist (R-2) in this comparative example includes the following steps:

[0087] Under UV-free conditions, 3 g of glyceryl dimethacrylate and 0.3 g of pentaerythritol tetramercaptoacetate were stirred and mixed at room temperature for 5-10 min. Then, 0.15 g of photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone was added and stirring was continued for 10-20 min. The mixture was then filtered through a 2500-mesh screen to obtain UV-curable nanoimprint photoresist.

[0088] The preparation method of the semi-interpenetrating network structure UV-curable nanoimprint photoresist (PR-4) in this comparative example includes the following steps:

[0089] Under UV-free conditions, 0.15 g of styrene-acrylonitrile copolymer was added to a mixture of 0.21 g of ethoxylated bisphenol A diacrylate and 0.9 g of 1,6-hexanediol diacrylate and stirred at room temperature for 1 h. After the styrene-acrylonitrile copolymer was completely dissolved, 0.3 g of pentaerythritol tetramercaptoacetate was added and stirred for 5-10 min. Then, 0.15 g of photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone was added and stirring was continued for 10-20 min. The mixture was filtered through a 2500-mesh screen to obtain a semi-interpenetrating network structure UV nanoimprint photoresist.

[0090] The preparation method of the UV-curable nanoimprint photoresist (R-4) in this comparative example includes the following steps:

[0091] Under UV-free conditions, 0.21 g of ethoxylated bisphenol A diacrylate and 0.9 g of 1,6-hexanediol diacrylate were mixed and stirred at room temperature for 1 min. Then, 0.3 g of pentaerythritol tetramercaptoacetate was added and stirred for 5-10 min. Finally, 0.15 g of photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone was added and stirred for 10-20 min. The mixture was then filtered through a 2500-mesh screen to obtain the UV-curable nanoimprint photoresist.

[0092] The ultraviolet nanoimprint photoresists PR-1-8%, PR-2-16%, PR-4, R-1, R-2, and R-4 were characterized by atomic force microscopy (AFM) morphology and phase diagrams to observe phase separation, following the steps described below.

[0093] (1) Using the scraping function of the MF-MP1100 microelectronic printer, the above-mentioned imprinted photoresist is scraped onto a clean quartz plate to form a 100 µm thick film.

[0094] (2) Place the coated quartz plate in a 365 nm ultraviolet light irradiation center, at 50 mW / cm 2 AFM samples were obtained by light-curing for 60 seconds.

[0095] (3) Tests were performed using the Tapping mode of the Bruker Dimension Icon atomic force microscope.

[0096] The final AFM morphology and phase diagram data of the photoresist are as follows: Figures 5-10 As shown, where Figure 5 Corresponding to PR-1-8%, Figure 6 Corresponding to R-1, Figure 7 Corresponding to PR-2-16%, Figure 8 Corresponding to R-2, Figure 9 Corresponding to PR-4, Figure 10 Corresponding to R-4.

[0097] PR-4 is a conventional semi-interpenetrating network (SIP) UV nanoimprint lithography (UV nanoimprint lithography) without hydrogen bonding interactions. The only difference between UV-curable UV nanoimprint lithography (UV nanoimprint lithography) lithography ...

[0098] A comparison of the AFM morphology and phase diagrams of photoresists PR-1-8% and R-1 shows that introducing a semi-interpenetrating network structure with supramolecular interactions into the photoresist does not cause phase separation in the system, and the order of introduction of linear components does not disrupt the surface smoothness of the film. This provides a foundation for the nanoscale uniformity of the imprinted structure. Similarly, a comparison of the AFM morphology and phase diagrams of photoresists PR-2-16% and R-2 yields the same conclusion.

[0099] Comparative Example 3:

[0100] The purpose of Comparative Example 3 is to compare the effect of the proportion of semi-interpenetrating network structure introduced on the mechanical properties of photoresist.

[0101] The preparation method of the semi-interpenetrating network structure UV-curable nanoimprint adhesive (PR-1-4%) in this comparative example is the same as that of PR-1-8%, except that the amount of poly(4-vinylpyridine) added is changed to 0.12 g.

[0102] The preparation method of the semi-interpenetrating network structure UV-curable nanoimprint adhesive (PR-1-12%) in this comparative example is the same as that of PR-1-8%, except that the amount of poly(4-vinylpyridine) added is changed to 0.36 g.

[0103] The preparation method of the semi-interpenetrating network structure UV-curable nanoimprint adhesive (PR-2-4%) in this comparative example is the same as that of PR-2-16%, except that the amount of poly(4-vinylpyridine) added is changed to 0.12 g.

[0104] The preparation method of the semi-interpenetrating network structure UV-curable nanoimprint adhesive (PR-2-8%) in this comparative example is the same as that of PR-2-16%, except that the amount of poly(4-vinylpyridine) added is changed to 0.24 g.

[0105] The preparation method of the semi-interpenetrating network structure UV-curable nanoimprint adhesive (PR-2-12%) in this comparative example is the same as that of PR-2-16%, except that the amount of poly(4-vinylpyridine) added is changed to 0.36 g.

[0106] The UV-curable nanoimprint photoresists R-1, PR-1-4%, PR-1-8%, PR-1-12%, R-2, PR-2-4%, PR-2-8%, PR-2-12%, and PR-2-16% were characterized by mechanical properties according to the following steps:

[0107] (1) Use a 2×35 (mm) type 4 cutter conforming to GB / T 528-2009 to cut a 300 mm thick polytetrafluoroethylene film to obtain a polytetrafluoroethylene film with standard dumbbell-shaped strip cutouts.

[0108] (2) A polytetrafluoroethylene film containing a standard dumbbell-shaped cutout is sandwiched between two quartz plates as a photocuring mold.

[0109] (3) Take 0.5-1 mL of the nanoimprint photoresist obtained by the above preparation method and inject it into the polytetrafluoroethylene quartz dumbbell strip hollow mold obtained in the previous step through a filter with a pore size of 0.2 micrometers.

[0110] (4) Place the polytetrafluoroethylene quartz containing nanoimprint adhesive obtained in the previous step into a 365 nm ultraviolet light irradiation center, at 50 mW / cm 2 Photopolymerization was performed for 300 seconds. After curing, the photoresist was removed to obtain a cured nanoimprint photoresist standard dumbbell sample.

[0111] (5) The standard dumbbell-shaped nanoimprint photoresist obtained in the previous step was subjected to stress-strain testing on a universal tensile testing machine at a tensile rate of 1 mm / min. The final mechanical property test data of the photoresist are as follows: Figures 11-12 As shown in Tables 2 and 3.

[0112]

[0113]

[0114] A comparison of the mechanical properties of photoresists R-1, PR-1-4%, PR-1-8%, and PR-1-12% shows that introducing the linear component poly(4-vinylpyridine) into the network system composed of pentaerythritol triacrylate monomers improves Young's modulus and strength while maintaining stable elongation at break. With increasing relative content of the linear component, Young's modulus and strength initially increase and then decrease, while elongation at break remains relatively stable.

[0115] A comparison of the mechanical properties of photoresists R-2, PR-2-4%, PR-2-8%, PR-2-12%, and PR-2-16% shows that introducing the linear component poly(4-vinylpyridine) into the network system composed of glyceryl dimethacrylate monomers significantly improves the elongation at break and strength of the photoresist. Furthermore, by controlling the amount of linear component added, the original Young's modulus can be maintained.

[0116] The above comparison of the two sets of mechanical properties demonstrates that by introducing the semi-interpenetrating network structure of this invention into the photoresist system and controlling the proportion of linear components, it is possible to improve a certain mechanical property while maintaining its relative mechanical property stability. This endows the material with better overall performance and adjustability.

[0117] Comparative Example 4:

[0118] The purpose of Comparative Example 4 is to compare the effect of introducing a semi-interpenetrating network structure on the volume shrinkage rate of the photoresist.

[0119] Volume shrinkage tests were conducted on photoresists R-1, PR-1-4%, PR-1-8%, PR-1-12%, R-2, PR-2-4%, PR-2-8%, PR-2-12%, and PR-2-16%. The density of the nanoimprint photoresist before and after curing was measured using the hydrostatic bottle method. The volume shrinkage rate of the imprint photoresist was calculated based on the density (ρ) data and the shrinkage rate calculation formula. The shrinkage rate test results are shown in Tables 4 and 5.

[0120] The formula for calculating shrinkage rate (ε) is as follows:

[0121]

[0122]

[0123]

[0124] The comparison of the volume shrinkage test results shows that the introduction of the semi-interpenetrating network structure reduces the volume shrinkage of the photoresist, and the higher the proportion of linear components, the lower the volume shrinkage. This proves that the introduction of the semi-interpenetrating network structure has a certain effect on reducing the volume shrinkage of the photoresist.

Claims

1. A semi-interpenetrating network structure UV-curable nanoimprint photoresist, characterized in that... It contains the following components by mass: 50-95 parts of hydroxy acrylate monomer, 1-20 parts of mercapto compound, 1-30 parts of linear polymer, and 1-5 parts of photoinitiator; The linear polymer is selected from one or more of poly(4-vinylpyridine), poly(2-vinylpyridine), polyamide, polyvinyl alcohol, polyacrylamide, polyurethane, polyurea, and polyvinylpyrrolidone. The linear polymer has a number-average molecular weight range of 1k-10000k; The hydroxyacrylate monomers are selected from 4-hydroxybutyl acrylate, 5-hydroxypentyl acrylate, 2-hydroxycyclohexyl acrylate, 3-hydroxyadamantane-1-yl acrylate, pentaerythritol triacrylate, 3,5-dihydroxyphenol methacrylate, 3-chloro-2-hydroxypropyl methacrylate, 2-(2-hydroxyethoxy)ethyl acrylate, 6-(4-hydroxyphenoxy)hexyl acrylate, 2-(2-hydroxyethoxy)ethyl methacrylate, 3,5-dihydroxyadamantane-1-yl methacrylate, 4-((4-hydroxyphenyl)sulfonyl)phenyl acrylate, 3-(acryloyloxy)-2- One or more of the following: hydroxypropyl methacrylate, 2-(4-benzoyl-3-hydroxyphenoxy)ethyl methacrylate, 2-(2-(2-hydroxyethoxy)ethoxy)ethyl methacrylate, 5,5,5-trifluoro-4-hydroxy-4-(trifluoromethyl)pent-2-yl methacrylate, 2-(2-(2-(2-hydroxyethoxy)ethoxy)ethoxy)ethyl methacrylate, 4,4,4-trifluoro-3-hydroxy-2-methyl-3-(trifluoromethyl)but-2-yl methacrylate, glyceryl dimethacrylate, poly(ethylene glycol) methacrylate, and glycerol 1,3-diglyceryl alcohol diacrylate.

2. The semi-interpenetrating network structure UV-curable nanoimprint photoresist according to claim 1, characterized in that: The thiol compounds are selected from dithiothreitol, 2,3-butanedithiol, 1,2-ethanedithiol, 1,8-octanedithiol, 1,4-butanedithiol, 1,6-hexanedithiol, 1,5-dimercaptonaphthalene, 2,4-dimercaptopyrimidine, 1,4-benzenedimethylthiol, 1,3-benzenedimethylthiol, 1,3-dimercaptopropane, 2,5-dimercaptothiadiazole, toluene-3,4-dithiophenol, 2,3-dimercaptosuccinic acid, 3,5-dimercaptobenzoic acid, 4',4-dimercaptodiphenyl sulfide, 2,3-dimercaptophthalic acid, 2,3-dimercaptoprop-1-ol, 2,5-dimercaptoterephthalic acid, 4,4'-dimercaptostilbene, tetramercaptobenzene, pentaerythritol tetramercaptoacetate, 2,6-naphthyldithiol, 4,4 One or more of the following: '-dimercaptodiphenyl ether, 4,4′-thiodiphenylthiol, biphenyl-4,4'-dithiol, 1,3,5-benzenetrithiophenol, trimercaptotriazine, 2,7-naphthyldithiol, 2,2'-dimercaptobiphenyl, 2,5-dimercaptobenzene, 2,2'-dimercaptobipyridine, 2,5-dimercaptopyrazole, dimercaptoacetylbenzene, 2,6-dimercaptothiophene, 3,5-dimercapto-1,2,4-triazacyclohexane, dimercaptosilane, and 2,6-dimercaptopyridine.

3. The semi-interpenetrating network structure UV-curable nanoimprint photoresist according to claim 1, characterized in that: The photoinitiator is selected from one or more of the following: benzoin dimethyl ether, 2-hydroxy-2-methyl-1-phenylpropanone, benzoin ethyl ether, bibenzoyl, benzophenone, methyl o-benzoyl, 2-hydroxy-4-(2-hydroxyethoxy)-2-methylphenylpropanone, 2-isopropyl-thioxanth-9-one, 4-phenylbenzophenone, methyl α-oxophenylacetate, 2-hydroxy-2-methylphenylpropane-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone, and 2,2-dimethoxyphenylacetophenone.

4. A method for preparing the semi-interpenetrating network structure UV-curable nanoimprint photoresist according to any one of claims 1-3, characterized in that... Includes the following steps: Under UV-free conditions, linear polymers are added to hydroxy acrylate monomers and stirred until the linear polymers are completely dissolved in the hydroxy acrylate monomers. Then, a mercapto compound is added while stirring, followed by a photoinitiator. After stirring and dispersing evenly, the semi-interpenetrating network structure UV-curable nanoimprint photoresist is obtained.

5. The preparation method according to claim 4, characterized in that: The filtration operation uses a 2000-2500 mesh filter.

6. A method for applying the semi-interpenetrating network structure UV-curable nanoimprint photoresist according to any one of claims 1-3, characterized in that... Includes the following steps: The semi-interpenetrating network structure UV-curable nanoimprint photoresist is spin-coated onto a silicon wafer after adhesion enhancement treatment to obtain a uniform photoresist film. A nanoimprint mold with microstructures is subjected to a certain pressure to allow the photoresist to fill the microstructure gaps in the imprint mold. After full contact, the mold and a square quartz sheet are placed in a vacuum environment for a period of time to remove residual air in the imprint structure. The mold and the square quartz sheet are then removed and placed in the center of 365 nm UV irradiation. After curing, the mold is removed to obtain the photoresist of the desired imprint structure.

7. The application method according to claim 6, characterized in that: The spin coating operation speed is 500-5000 r / min, and the spin coating time is 10-600 s.

8. The application method according to claim 6, characterized in that: The intensity of the ultraviolet light irradiation is 10-200 mW / cm². 2 The illumination time is 1-300 s.

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