A hexaarylbiimidazole-based ultraviolet positive working linear photoresist and methods of making and using the same

Abstract

The application belongs to the technical field of microelectronic processing materials, and more particularly relates to a kind of linear ultraviolet positive photoresist based on hexaarylbiimidazole and its preparation and use method.The application takes hexaarylbiimidazole as photosensitive point, first polymerizes low polymer dihydric alcohol, diisocyanate and dihydroxy functional hexaarylbiimidazole to prepare a kind of linear ultraviolet photoresist, then adds free radical quencher in solution to obtain light-controllable linear polyurethane photoresist.When the photoresist is used for photoetching, under the irradiation of ultraviolet light, the dynamic C-N covalent bond between the two imidazole rings in the hexaarylbiimidazole unit in the linear photoresist responds to photolysis to form oligomer;At the same time, the free radical quencher combines with the hexaarylbiimidazole monomer formed after photodepolymerization to inhibit the recovery of polymer, so that the area exposed to ultraviolet light can be dissolved in developer, so as to obtain high-resolution target positive pattern.

Description

Technical Field

[0001] This application belongs to the field of microelectronic processing materials technology, and more specifically, relates to a UV positive linear photoresist based on hexaarylbiimidazole and its preparation and use methods. Background Technology

[0002] Photolithography is a technique that transfers patterns from a photomask to a substrate such as a silicon wafer by illuminating it. Photoresist, as a key material in the electronic manufacturing fields such as semiconductors, flat panel displays, and printed circuit boards, occupies a vital position in today's high-tech industries.

[0003] Photoresists are classified into positive and negative photoresists. Positive photoresists, due to their high contrast and high pattern resolution, are widely used in the fabrication of semiconductor devices with high pattern requirements. Traditional positive photoresists are phenolic resin-DNQ photoresist systems. During exposure, the diazo groups in this type of photoresist undergo Wolfman rearrangement, producing easily soluble carboxyindanic acid. However, the coupling between DNQ and phenolic resin in unexposed areas results in lower solubility. This type of photoresist exhibits good heat resistance and dry etching resistance, and also has good resolution. However, phenolic resin exhibits non-photobleaching absorption under 248nm ultraviolet light, making deep ultraviolet lithography impossible. Subsequently, chemically amplified photoresists were studied to enhance the photoresist's light sensitivity. The photoacid generator in these photoresists produces acid molecules during exposure, further promoting many continuous chemical transformation reactions within the photoresist. However, most current photoresist systems have poor solubility, requiring immediate preparation and use, and cannot be stored for long periods.

[0004] Patent CN115963696A discloses a UV positive photoresist based on hexaarylbiimidazole molecular switches and its application method. This photoresist utilizes hexaarylbiimidazole as a crosslinking unit and a photoresponsive unit, forming a three-dimensional network polymer photoresist. Under illumination, the CN covalent bonds between the two imidazole rings in hexaarylbiimidazole are correspondingly photolytically broken, and the polymer depolymerizes to form oligomers. At the same time, a free radical quencher prevents the oligomers formed after exposure from self-recovering, thus forming oligomers with an unrecoverable polymer structure. This allows the oligomers formed in the exposed areas of the photoresist to be dissolved by the developer, while the unexposed areas remain insoluble in the developer. After development, a high-resolution target positive pattern is obtained.

[0005] However, the photoresist prepared in this patent document has a three-dimensional network cross-linked structure, and the degree of cross-linking increases further with prolonged storage time, resulting in a poorly soluble solid. To ensure that the polymer dissolves more easily after light exposure, the initial degree of cross-linking should generally not be too high. However, after premature polymerization, the molecular weight of the polymer changes with storage time. Therefore, the photoresist in this patent document requires immediate preparation and is complex to prepare, which is not conducive to long-term storage and commercial application. In addition, the free radical quencher in this patent document is a solid, and after dissolution, it participates in the polymerization reaction together with the monomer, which will also affect the polymerization effect of the polymer to a certain extent, thus affecting the film-forming properties of the photoresist. These problems urgently need to be solved. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this application is to provide a hexaaryl biimidazole-based ultraviolet positive linear photoresist and its preparation and application methods, aiming to solve the technical problems of existing hexaaryl biimidazole-based ultraviolet positive photoresists, such as the need for immediate preparation and use, short storage time, and poor solubility.

[0007] To achieve the above objectives, in a first aspect, this application provides a hexaarylbiimidazole-based ultraviolet positive linear photoresist, comprising a hexaarylbiimidazole linear polymer and a free radical quencher; The hexaaryl biimidazole linear polymer is a linear polymer obtained by polymerizing a dihydroxy-functionalized hexaaryl biimidazole molecular switch and an oligomeric diol with diisocyanate in the presence of a solvent and under the catalysis of a catalyst; the free radical quencher is a small molecule free radical quencher containing thiol and carboxyl groups.

[0008] Preferably, the oligomeric diol is polyethylene glycol or a polyether diol; the molecular weight of the oligomeric diol is 90-1000.

[0009] Preferably, the free radical quencher is one or more of 3-mercaptopropionic acid, mercaptoacetic acid, mercaptobutyric acid, and thioproline.

[0010] Preferably, the molar ratio of the oligomeric diol to the dihydroxy-functionalized hexaarylbiimidazole molecular switch is 1:1 to 10:1, more preferably 2:1 to 5:1. The molar amount of the free radical quencher is greater than the molar amount of the dihydroxy-functionalized hexaarylbiimidazole molecular switch; and the molar ratio of the free radical quencher to the dihydroxy-functionalized hexaarylbiimidazole molecular switch is preferably 2:1 to 15:1; more preferably 2:1 to 5:1; the molar amount of the diisocyanate is greater than or equal to the sum of the molar amounts of the oligomeric diol and the dihydroxy-functionalized hexaarylbiimidazole molecular switch; the molar amount of the catalyst does not exceed 5% of the total molar amount of the monomers participating in the polymerization, wherein the monomers participating in the polymerization include the oligomeric diol, the dihydroxy-functionalized hexaarylbiimidazole molecular switch, and the diisocyanate; and the dihydroxy-functionalized hexaarylbiimidazole molecular switch accounts for 10-20% of the total molar amount of the monomers participating in the polymerization.

[0011] According to another aspect of the present invention, a method for preparing the photoresist is provided, comprising the following steps: mixing an oligomeric diol with a dihydroxy-functionalized hexaarylbiimidazole molecular switch, a catalyst, and a diisocyanate dissolved in an organic solvent, stirring and heating to induce a polymerization reaction, and then adding the free radical quencher to the solution after the polymerization reaction and stirring until homogeneous to obtain a linear polyurethane photoresist solution based on hexaarylbiimidazole.

[0012] According to another aspect of the present invention, a method of using the photoresist is provided, comprising the following steps: (1) Spin-coating the photoresist solution into a film and then drying it to obtain a linear polyurethane photoresist film based on hexaaryl biimidazole; (2) The linear polyurethane photoresist film obtained in step (1) is exposed to ultraviolet light. The CN covalent bond between the two imidazole rings in the hexaaryl biimidazole connecting node of the linear polymer is broken, and the polymer is depolymerized to form oligomers. Then, a developer is added for development. The free radical quencher in the photoresist can inhibit the repolymerization of hexaaryl biimidazole free radicals, so that the exposed area is easily dissolved in the developer, while the unexposed area is insoluble in the developer. After development, a target positive pattern with high resolution is obtained.

[0013] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art: (1) This invention uses hexaarylbiimidazole as the photosensitive unit. First, a linear ultraviolet photoresist is prepared by polymerizing oligomeric diol, diisocyanate, and dihydroxy-functionalized hexaarylbiimidazole. Then, a free radical quencher is added to the solution to obtain a light-tunable linear polyurethane photoresist. The hexaarylbiimidazole, as the photosensitive unit, has excellent photosensitivity to both ultraviolet and deep ultraviolet light sources and can be used as a photosensitive agent for ultraviolet and deep ultraviolet lithography. The photoresist has a linear structure, which has greater solubility and is in the post-polymerization state, thus exhibiting higher stability and commercial value. This photoresist can be applied in the fields of semiconductor, flat panel display, and printed circuit board manufacturing.

[0014] (2) In this invention, hexaarylbiimidazole serves as both a photosensitive unit and a linking unit for polyurethane. By utilizing the photoinduced structural changes of the hexaarylbiimidazole molecule, it can significantly influence the molecular weight of the polymer. In the ultraviolet light exposure region, the CN covalent bond of hexaarylbiimidazole breaks to form two triphenylimidazole free radicals, which are then inhibited from repolymerizing by the free radical quencher. This results in a sharp decrease in the molecular weight of the linear polymer, giving the system a very high photolithographic resolution, reaching the submicron level.

[0015] (3) In this invention, the linear polymer in the exposed area undergoes depolymerization and has very good solubility in the developer, while the polymer in the unexposed area maintains its linear structure and cannot be dissolved by the developer. Therefore, the photoresist film in the unexposed area can be completely preserved. At the same time, there will be a significant difference in solubility between the illuminated and unilluminated areas, which will result in a photolithographic pattern with good contrast.

[0016] (4) In this invention, by controlling the breaking of the CN covalent bond of hexaaryl bimidazole as the control factor for polymer structure change, the defects such as line broadening caused by acid diffusion in traditional diazonaphthoquinone and chemical amplification systems can be avoided.

[0017] (5) In this invention, the free radical quencher is one of the core components, and its type has an important impact on the overall photolithography effect. It has been found that different types of free radical quenchers have different quenching effects, resulting in different photolithography effects. The selection of free radical quenchers should follow the selection criteria of not only having excellent quenching effects but also having no other side reactions. In this invention, mercaptopropionic acid and its analogues are selected as free radical quenchers. The free radical quencher is added after the monomer dihydroxy functionalized hexaaryl biimidazole, oligomeric diol and diisocyanate have undergone polymerization reaction to form a linear polymer. The free radical quencher does not participate in the polymerization reaction of hexaaryl biimidazole molecules and will not affect the polymerization effect and film quality of the polymer. Moreover, the linear polymer of this invention is itself in a liquid state and the polymer structure is regular and stable. Mercaptopropionic acid is a liquid free radical quencher. Therefore, the UV positive photoresist provided by this invention is not only simple to prepare but can also be stored for a long time without the need for fresh preparation and use, making it suitable for commercial applications. Attached Figure Description

[0018] Figure 1 This is a technical roadmap for the preparation of the positive linear polyurethane photoresist based on hexaaryl biimidazole in Example 1.

[0019] Figure 2 It is a curve showing the change in film thickness of the optical pattern and exposed area after photolithography and development in Example 1.

[0020] Figure 3 This is the optical pattern after photolithography and development of the photoresist in Example 2.

[0021] Figure 4 It is the optical pattern after photolithography and development of the photoresist in Example 3.

[0022] Figure 5 This is the optical pattern after photolithography and development of the photoresist in Example 4. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0024] The embodiments of the present invention are implemented under the premise of the technical solution of the present invention, and detailed implementation methods and processes are given. However, the protection scope of the present invention is not limited to the following embodiments. The process parameters in the following embodiments that do not specify specific conditions are generally in accordance with conventional conditions.

[0025] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0026] This invention provides a hexaarylbiimidazole-based ultraviolet positive linear photoresist, comprising a hexaarylbiimidazole linear polymer and a free radical quencher; the hexaarylbiimidazole linear polymer is a linear polymer obtained by polymerizing a dihydroxy-functionalized hexaarylbiimidazole molecular switch and an oligomeric diol with diisocyanate in the presence of a solvent and under the catalysis of a catalyst; the free radical quencher is a small molecule free radical quencher containing thiol and carboxyl groups.

[0027] In some embodiments, the oligomeric diol is polyethylene glycol or a polyether diol; preferably polyethylene glycol; the molecular weight of the oligomeric diol is 90-1000. The free radical quencher is one or more of 3-mercaptopropionic acid, mercaptoacetic acid, mercaptobutyric acid, and thioproline.

[0028] In some embodiments, the dihydroxy-functionalized hexaarylbiimidazole molecular switch is a molecular switch with two hydroxyl functional groups designed by modifying hexaarylbiimidazole as the molecular host, wherein the hexaarylbiimidazole has the structure shown in formula (I):

[0029] Formula (1).

[0030] The hexaaryl biimidazole shown in Formula (I) is the main molecule. The molecule is composed of two triphenylimidazoles covalently linked by CN bonds. Under ultraviolet light irradiation, the molecule breaks down to form two triphenylimidazole free radicals, accompanied by a color change. After the light is removed, the two free radicals rejoin through CN bonds to return to the initial dimer form.

[0031] In some embodiments, some hydrogen atoms on the benzene ring in the molecular switch structure are replaced by electron-withdrawing groups, preferably halogen atoms or nitro groups. More preferably, the structure has the following formulas (ii) to (vii):

[0032] Formula (II) Formula (III) Formula (IV)

[0033] Formula (5) Formula (6) Formula (7) In formulas (ii) to (vii), R is an alkyl alcohol containing one hydroxyl group, specifically an alkyl alcohol with 1 to 10 carbon atoms, more preferably an alkyl alcohol with 1 to 5 carbon atoms, and even more preferably an alkyl alcohol with 1 to 3 carbon atoms.

[0034] In this embodiment of the invention, the dihydroxy-functionalized hexaarylbiimidazole is obtained by modifying the parent structure of formula (I), and any one of formulas (II) to (VII) can be used. In addition to the listed structures, electron-withdrawing or electron-donating groups can also be modified on the benzene ring of hexaarylbiimidazole to change the optical properties of hexaarylbiimidazole and give it different photosensitizing properties.

[0035] In some embodiments, the free radical quencher is one or more selected from 3-mercaptopropionic acid, mercaptoacetic acid, mercaptobutyric acid, and thioproline. The structural formula of 3-mercaptopropionic acid is shown in formula (viii).

[0036] Formula (8).

[0037] Mercaptoacetic acid (chemical formula C2H4O2S), mercaptobutyric acid (chemical formula C4H8O2S), and thioproline (chemical formula C5H9NO2S) are analogs of 3-mercaptopropionic acid and can also be used as free radical quenchers in this invention.

[0038] In some embodiments, the solvent is anhydrous tetrahydrofuran, ethyl acetate, acetone, acetonitrile, etc., preferably anhydrous ethyl acetate. The solvent is an organic solvent used to dissolve the oligomeric diol, the functionalized hexaarylbiimidazole molecular switch, and the free radical quencher.

[0039] In some embodiments, the molar ratio of the oligomeric diol to the dihydroxy-functionalized hexaarylbiimidazole molecular switch is 1:1 to 10:1, more preferably 2:1 to 5:1. The molar amount of the free radical quencher is greater than the molar amount of the dihydroxy-functionalized hexaarylbiimidazole molecular switch; and the molar ratio of the free radical quencher to the dihydroxy-functionalized hexaarylbiimidazole molecular switch is preferably 2:1 to 15:1; more preferably 2:1 to 5:1. The molar amount of the diisocyanate is greater than or equal to the sum of the molar amounts of the oligomeric diol and the dihydroxy-functionalized hexaarylbiimidazole molecular switch; the molar amount of the catalyst does not exceed 5% of the total molar amount of the monomers participating in the polymerization, wherein the monomers participating in the polymerization include the oligomeric diol, the dihydroxy-functionalized hexaarylbiimidazole molecular switch, and the diisocyanate. The catalyst is bis(dimethylaminoethyl) ether, pentamethyldiethylenetriamine, dimethylcyclohexylamine, or dibutyltin dilaurate, preferably dibutyltin dilaurate. Furthermore, the dihydroxy-functionalized hexaaryl biimidazole molecular switch accounts for 10-20% of the total molar amount of the monomers participating in the polymerization.

[0040] The present invention also provides a method for preparing the above-mentioned photoresist, comprising the following steps: mixing an oligomeric diol with a dihydroxy-functionalized hexaarylbiimidazole molecular switch, a catalyst, and a diisocyanate dissolved in an organic solvent, stirring and heating to induce a polymerization reaction, and then adding a free radical quencher to the solution after the polymerization reaction and stirring until homogeneous to obtain a linear polyurethane photoresist solution based on hexaarylbiimidazole.

[0041] In some embodiments, the polymerization reaction takes 2 to 10 hours and is carried out at a temperature of 60-80°C. The present invention also provides a method for using the above-mentioned photoresist, comprising the following steps: (1) Spin-coating the photoresist solution into a film and then drying it to obtain a linear polyurethane photoresist film based on hexaaryl biimidazole; (2) The linear polyurethane photoresist film obtained in step (1) is exposed to ultraviolet light. The CN covalent bond between the two imidazole rings in the hexaaryl biimidazole connecting node of the linear polymer is broken, and the polymer is depolymerized to form oligomers. Then, a developer is added for development. The free radical quencher in the photoresist can inhibit the repolymerization of hexaaryl biimidazole free radicals, so that the exposed area is easily dissolved in the developer, while the unexposed area is insoluble in the developer. After development, a target positive pattern with high resolution is obtained.

[0042] More preferably, the oligomeric diol in step (1) is polyethylene glycol, which is polyethylene glycol obtained after thorough dehydration under vacuum heating conditions.

[0043] In some embodiments, the drying temperature in step (1) is 30~70°C and the drying time is 2~10 hours.

[0044] In some embodiments, the developer is one or more of a mixture of methanol, ethanol, tetrahydrofuran, IPA, and water.

[0045] This invention provides a UV-positive linear photoresist based on hexaarylbiimidazole in some embodiments. During photolithography, the dihydroxy-functionalized hexaarylbiimidazole acts not only as a linking unit but also as a photosensitive unit. In the UV-exposed region, the CN covalent bonds within the hexaarylbiimidazole unit break, forming two triphenylimidazolium free radicals. These free radicals further bind to surrounding mercaptopropionic acid or its analogues as quenchers, inhibiting the recovery of the CN covalent bonds and causing the hexaarylbiimidazole free radicals to polymerize again. Therefore, in the UV-exposed region, the polymer depolymerizes, its molecular weight is greatly reduced, and it is easily soluble in the developer. In contrast, the unexposed region maintains a linear structure and cannot be dissolved by the developer. This difference in solubility between the exposed and unexposed regions allows the pattern on the photomask to be transferred to the photoresist film while maintaining high contrast. This photoresist formulation uses a linear polyurethane structure, avoiding the defects of cross-linked polymers that need to be prepared and used immediately and have poor solubility. It can be stored for a longer time, the preparation process is simpler, and it is more conducive to the long-term preservation of the photoresist and its commercial application. The ultraviolet positive linear photoresist based on hexaarylbiimidazole provided by this invention can be applied to the semiconductor industry, printed circuit board field, and flat panel display field, etc.

[0046] This invention involves mixing the components of a photoresist under a nitrogen atmosphere, heating and polymerizing to obtain a polymer solution, and then adding a free radical quencher to the solution to obtain a polyurethane photoresist solution with hexaarylbiimidazole as the photosensitive unit. The photoresist is then dropped onto a cleaned silicon wafer and spin-coated to form a film. Heating removes the solvent, forming a photoresist film. Under ultraviolet exposure, the CN covalent bonds within the hexaarylbiimidazole units break, forming two triphenylimidazolium free radicals. These free radical quenchers further inhibit repolymerization, significantly reducing the polymer molecular weight and making it more easily dissolved by the developer. This creates a solubility difference between exposed and unexposed areas, allowing the transfer of patterns from a photomask to the photoresist film surface. Experiments show that linear photoresists have higher solubility, and the prepared photoresist solution is a pre-polymerized solution, exhibiting high stability in photolithography, which is beneficial for photoresist commercialization. This invention, based on a hexaarylbiimidazole molecular switch, presents a UV-positive linear photoresist with significant commercial potential.

[0047] The process parameters in the following examples, unless otherwise specified, are generally performed under conventional conditions.

[0048] The following are examples of embodiments of this application: Example 1 The oligomeric diol is polyethylene glycol with a molecular weight of 400 (PEG). 400Isophorone diisocyanate (IPDI) serves as the isocyanate source, dihydroxy-functionalized hexaarylbiimidazole (2-OH-HABI) serves as the photosensitizing and linking unit, dibutyltin dilaurate (DBTDL) is the catalyst, and mercaptopropionic acid (MPA) corresponding to formula (VIII) is the quencher. The structure of 2-OH-HABI is shown in formula (IX):

[0049] Formula (Nine) Formula (Eight) Figure 1 This describes the preparation technique for a linear polyurethane positive photoresist using 2-OH-HABI as the photosensitive unit and MPA as the quencher. Weigh 0.1g of PEG... 400 Place in a 50 ml round-bottom flask, evacuate to remove water at 75°C for 10 minutes, purge with nitrogen atmosphere and cool to room temperature. Weigh 0.079 g of 2-OH-HABI and dissolve it in 4 ml of anhydrous ethyl acetate, then inject into a container containing PEG. 400 In a round-bottom flask, the mixture was vigorously stirred until homogeneous. Then, 5 mg of dibutyltin dilaurate catalyst was added to the flask, and 0.097 g (approximately 0.092 ml) of IPDI was weighed and added directly to the reaction flask. After vigorous stirring to ensure thorough mixing of the monomers, the mixture was heated at 75°C for 3 hours to induce linear polymerization. Subsequently, 30 μL of mercaptopropionic acid free radical quencher was added to the solution to obtain a UV positive linear photoresist.

[0050] The cleaned silicon wafer was placed on a spin coater, and the photoresist solution was dropped onto the wafer. The spin coater was set to 1000 rpm for 20 seconds in the first step and 8000 rpm for 20 seconds in the second step. The silicon wafer with the photoresist was then placed on a heating stage at 45°C and heated for 3 hours to remove the solvent, resulting in a linear contact with 2-OH-HABI as the connecting unit and photosensitive unit, and MPA as the quencher. The mask channel width was 5 μm. The wafer was exposed to a 365nm UV light source for 100 seconds. After exposure, the wafer was developed in a 2:1 H2O:IPA mixed solution for 30 seconds, and then the surface solvent was dried with nitrogen to obtain a photolithographic pattern with a linewidth of 5 μm.

[0051] Figure 2 Contents (a) and (b) show the photolithographic patterns of photoresist after development in regions with different channel sizes under an optical microscope. In content (b), a pattern with a channel width of 5 μm can be observed on the photoresist surface in the smaller channel size region. The thickness of the developed photoresist film was characterized using a profilometer, revealing that the residual thickness gradually decreases with increasing exposure dose. Figure 2 As shown in content (c), MPA free radical quencher has excellent free radical quenching effect.

[0052] Example 2 The oligomeric diol is polytetrahydrofuran with a molecular weight of 400 (PTMG). 400 Isophorone diisocyanate (IPDI) serves as the isocyanate source, dihydroxy-functionalized hexaaryl biimidazole (2-OH-HABI) serves as the photosensitive unit and linking unit, dibutyltin dilaurate (DBTDL) serves as the catalyst, and mercaptopropionic acid (MPA) serves as the quencher.

[0053] Weigh out 0.1g PTMG 400 Place in a 50 ml round-bottom flask, evacuate to remove water at 75°C for 10 minutes, purge with nitrogen atmosphere, then switch to nitrogen environment and cool to room temperature. Weigh 0.079 g of 2-OH-HABI and dissolve it in 4 ml of anhydrous ethyl acetate, then inject into a container containing PTMG. 400 In a round-bottom flask, the mixture was vigorously stirred until homogeneous. Then, 5 mg of dibutyltin dilaurate catalyst was added to the flask, and 0.097 g (approximately 0.092 ml) of IPDI was weighed and directly added to the reaction flask. After vigorous stirring to ensure thorough mixing of the monomers, the mixture was heated at 75°C for 3 hours to induce linear polymerization. Subsequently, 30 μL of mercaptopropionic acid was added to the solution to obtain a UV positive linear photoresist.

[0054] A clean silicon wafer was placed on a spin coater, and photoresist solution was dropped onto it. The spin coater was set to 1000 rpm for 20 seconds in the first step and 8000 rpm for 20 seconds in the second step. The photoresist-coated wafer was then heated on a 45°C stage for 3 hours to remove the solvent, resulting in a linear polyurethane positive photoresist with 2-OH-HABI as the linker and photosensitive unit, and MPA as the quencher. The spin-coated silicon wafer was then placed on the stage of a lithography machine, in contact with a 5 μm mask channel. Contact exposure was performed at 365 nm for 100 seconds. After exposure, the wafer was developed in a 2:1 H2O:IPA mixture for 30 seconds, and then the surface solvent was dried with nitrogen gas to obtain the desired product. Figure 3 The lithographic patterns shown in content (a) and content (b) have a linewidth of 5 μm.

[0055] Example 3 The diol is 1,2-decanediol with a molecular weight of 174.28. Isophorone diisocyanate (IPDI) is used as the isocyanate source, dihydroxy-functionalized hexaarylbiimidazole (2-OH-HABI) is used as the photosensitive unit and linking unit, the catalyst is dibutyltin dilaurate (DBTDL), and the quencher is mercaptopropionic acid. Weigh 0.044 g of 1,2-decanediol and place it in a 50 ml round-bottom flask. Remove water under vacuum at 75°C for 10 minutes, then purge with nitrogen and cool to room temperature. Weigh 0.079 g of 2-OH-HABI and dissolve it in 4 ml of anhydrous ethyl acetate. Pour this solution into the round-bottom flask containing 1,2-decanediol and stir vigorously until homogeneous. Then, add 5 mg of dibutyltin dilaurate catalyst to the flask and weigh 0.097 g (approximately 0.092 ml) of IPDI directly into the reaction flask. After thoroughly mixing the monomers under vigorous stirring, heat at 75°C for 3 hours to induce linear polymerization. Finally, add 30 μL of mercaptopropionic acid to the solution to obtain a UV positive linear photoresist.

[0056] The cleaned silicon wafer was placed on a spin coater, and the photoresist solution was dropped onto it. The spin coater was set to 1000 rpm for 20 seconds in the first step and 8000 rpm for 20 seconds in the second step. The photoresist-coated wafer was then heated on a 45°C heating stage for 3 hours to remove the solvent. The silicon wafer with the spin-coated linear polyurethane photoresist was then placed on the stage of a lithography machine, ensuring it was in contact with a mask (5 μm channel width). Contact exposure was performed at 365 nm for 100 seconds. After exposure, the wafer was developed in a 2:1 H₂O:IPA mixture for 30 seconds, and then the surface solvent was dried with nitrogen gas to obtain the desired result. Figure 4 The lithographic patterns shown in content (a) and content (b) have a linewidth of 5 μm.

[0057] Example 4 The oligomeric diol is polyethylene glycol with a molecular weight of 200 (PEG). 200 Isophorone diisocyanate (IPDI) serves as the isocyanate source, dihydroxy-functionalized hexaaryl biimidazole (2-OH-HABI) serves as the photosensitizing and linking unit, dibutyltin dilaurate (DBTDL) serves as the catalyst, and mercaptopropionic acid corresponding to formula (viii) serves as the quencher. Weigh out 0.1g of PEG. 200 Place in a 50 ml round-bottom flask, evacuate to remove water at 75°C for 10 minutes, purge with nitrogen atmosphere, then switch to nitrogen environment and cool to room temperature. Weigh 0.079 g of 2-OH-HABI and dissolve it in 4 ml of anhydrous ethyl acetate, then inject into a container containing PEG. 200In a round-bottom flask, the mixture was vigorously stirred until homogeneous. Then, 10 mg of dibutyltin dilaurate catalyst was added to the flask, and 0.1455 g of IPDI was directly added to the system. After vigorous stirring to ensure thorough mixing of the monomers, the mixture was heated at 75°C for 3 hours to induce linear polymerization. Subsequently, 50 μL of mercaptopropionic acid was added to the solution to obtain a UV positive linear photoresist.

[0058] A cleaned silicon wafer was placed on a spin coater, and photoresist solution was dropped onto it. The spin coater was set to 1000 rpm for 20 seconds in the first step and 8000 rpm for 20 seconds in the second step. The photoresist-coated wafer was then heated on a 45°C heating stage for 3 hours to remove the solvent, resulting in a linear polyurethane positive photoresist with 2-OH-HABI as the linker and photosensitive unit, and MPA as the quencher. The spin-coated silicon wafer was then placed on the stage of a lithography machine, in contact with a 5μm mask channel. Contact exposure was performed at 365nm light source for 100 seconds. After exposure, the wafer was developed in a 2:1 H2O:IPA mixture for 30 seconds, and then the surface solvent was dried with nitrogen gas to obtain the desired product. Figure 5 The lithographic patterns with a linewidth of 5 μm shown in contents (a) and (b) are as follows.

[0059] Example 5 The oligomeric diol is polyethylene glycol with a molecular weight of 200 (PEG). 200 Isophorone diisocyanate (IPDI) serves as the isocyanate source, dihydroxy-functionalized hexaaryl biimidazole (2-OH-HABI) serves as the photosensitizing and linking unit, dibutyltin dilaurate (DBTDL) serves as the catalyst, and mercaptopropionic acid corresponding to formula (viii) serves as the quencher. Weigh out 0.05g of PEG. 200 Place in a 50 ml round-bottom flask, evacuate to remove water at 75°C for 10 minutes, purge with nitrogen atmosphere, then switch to nitrogen environment and cool to room temperature. Weigh 0.158 g of 2-OH-HABI and dissolve it in 4 ml of anhydrous ethyl acetate, then inject into a container containing PEG. 200 In a round-bottom flask, the mixture was vigorously stirred until homogeneous. Then, 10 mg of dibutyltin dilaurate catalyst was added to the flask, and 0.1455 g of IPDI was directly added to the system. After vigorous stirring to ensure thorough mixing of the monomers, the mixture was heated at 75°C for 3 hours to induce linear polymerization. Subsequently, 50 μL of mercaptopropionic acid was added to the solution to obtain a UV positive linear photoresist.

[0060] A clean silicon wafer was placed on a spin coater, and photoresist solution was dropped onto it. The spin coater was set to 1000 rpm for 20 seconds in the first step and 8000 rpm for 20 seconds in the second step. The silicon wafer with photoresist was then placed on a 45°C heating stage and heated for 3 hours to remove the solvent, resulting in a linear polyurethane positive photoresist with 2-OH-HABI as the linking and photosensitive units and MPA as the quencher. The silicon wafer with the linear polyurethane photoresist was then placed on the stage of a lithography machine, making contact with a mask with a channel width of 5 μm. Contact exposure was performed for 100 seconds under a 365 nm light source. After exposure, the wafer was placed in a 2:1 H2O:IPA mixed solution for development for 30 seconds, and then the surface solvent was dried with nitrogen gas to obtain a photolithographic pattern with a line width of 5 μm.

[0061] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A UV-positive linear photoresist based on hexaarylbiimidazole, characterized in that, Including hexaaryl biimidazole linear polymers and free radical quenchers; The hexaaryl biimidazole linear polymer is a linear polymer obtained by polymerizing a dihydroxy-functionalized hexaaryl biimidazole molecular switch and an oligomeric diol with diisocyanate in the presence of a solvent and under the catalysis of a catalyst; the oligomeric diol is polyethylene glycol or a polyether diol. The free radical quencher is one or more of 3-mercaptopropionic acid, mercaptoacetic acid, and mercaptobutyric acid.

2. The photoresist as described in claim 1, characterized in that, The molecular weight of the oligomeric diol is 90-1000.

3. The photoresist as described in claim 1, characterized in that, The dihydroxy-functionalized hexaarylbiimidazole molecular switch is a molecular switch with two hydroxyl functional groups designed by modifying hexaarylbiimidazole as the main molecular host, wherein hexaarylbiimidazole has the structure shown in formula (I): Formula (1).

4. The photoresist as described in claim 1, characterized in that, The solvent is an organic solvent used to dissolve the oligomeric diol, the dihydroxy-functionalized hexaaryl biimidazole molecular switch, and the free radical quencher; the solvent is one or more of anhydrous tetrahydrofuran, ethyl acetate, acetone, and acetonitrile.

5. The photoresist as described in claim 1, characterized in that, The molar ratio of the oligomeric diol to the dihydroxy-functionalized hexaaryl biimidazole molecule switch is 1:1 to 10:1; and / or, The molar amount of the free radical quencher is greater than the molar amount of the dihydroxy-functionalized hexaaryl biimidazole molecular switch; and the molar ratio of the free radical quencher to the dihydroxy-functionalized hexaaryl biimidazole molecular switch is 2:1 to 15:1; and / or, The molar amount of the diisocyanate is greater than or equal to the sum of the molar amounts of the oligomeric diol and the dihydroxy-functionalized hexaarylbiimidazole molecular switch; the molar amount of the catalyst does not exceed 5% of the total molar amount of the monomers participating in the polymerization, wherein the monomers participating in the polymerization include the oligomeric diol, the dihydroxy-functionalized hexaarylbiimidazole molecular switch, and the diisocyanate; and the dihydroxy-functionalized hexaarylbiimidazole molecular switch accounts for 10-20% of the total molar amount of the monomers participating in the polymerization; and / or, The catalyst is one or more of dimethylaminoethyl ether, pentamethyldiethylenetriamine, dimethylcyclohexylamine, and dibutyltin dilaurate.

6. The method for preparing photoresist according to any one of claims 1 to 5, characterized in that, The process includes the following steps: mixing an oligomeric diol with a dihydroxy-functionalized hexaarylbiimidazole molecular switch, a catalyst, and a diisocyanate dissolved in an organic solvent, stirring and heating to induce a polymerization reaction, and then adding the free radical quencher to the solution after the polymerization reaction and stirring until homogeneous to obtain a linear polymer photoresist solution based on hexaarylbiimidazole.

7. The preparation method according to claim 6, characterized in that, The polymerization reaction takes 2 to 10 hours.

8. The method of using the photoresist as described in any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Spin-coating the photoresist solution into a film and then drying it to obtain a linear polymer photoresist film based on hexaarylbiimidazole; (2) The linear polymer photoresist film obtained in step (1) is exposed to ultraviolet light. The CN covalent bond between the two imidazole rings in the hexaaryl biimidazole connecting node of the linear polymer is broken, and the polymer is depolymerized to form oligomers. Then, a developer is added for development. The free radical quencher in the photoresist can inhibit the repolymerization of hexaaryl biimidazole free radicals, so that the exposed area is easily dissolved in the developer, while the unexposed area is insoluble in the developer. After development, a target positive pattern with high resolution is obtained.

9. The method of use as described in claim 8, characterized in that, The drying temperature in step (1) is 30~70℃ and the drying time is 2~10 hours.

10. The method of use as described in claim 8, characterized in that, The developing solution is one or more of a mixture of methanol, ethanol, tetrahydrofuran, IPA, and water.

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